General information about EUSES
EUSES

EUROPEAN UNION SYSTEM FOR THE EVALUATION OF SUBSTANCES

DRAFT FINAL VERSION

The PC program EUSES is designed to be a decision-support system for the evaluation of the risks of substances to man and the environment. The system is fully described in the EUSES documentation and is based on the EU Technical Guidance Documents for risk assessment of new and existing substances. The documentation and program can be obtained from the European Chemicals Bureau, Ispra, Italy. This bureau also provides helpdesk facilities.  Tel: +(39) 332-785.866

Select one of the following subjects for further information:

Background information

Program structure and usage

Model information

Release notes


How to use EUSES
Program Information

Please select one of the following topics:

Main window of EUSES	The EUSES main window and its components

Input windows	Input windows of EUSES - general information

Key usage	General keys, accelerators and keys in the outline

Menu options	Description of the menu options

Working with EUSES	How to work with EUSES...

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Input parameters of EUSES
Input parameters

No further information in this version


Defaults of EUSES

The term default is used in two ways:

1.	A default value for a parameter, i.e. a value used by the model if no value is entered by the user or if no value can be estimated.

2.	The defaults of EUSES is another name for the non-substance data model parameters that can be modified.

More information on default model parameters


Results of EUSES

No further information in this version


Database - general information

The EUSES database contains Studies, Substances, Components and Defaults.

More information about working with the EUSES database


Introduction to EUSES
Background information

EUROPEAN UNION SYSTEM FOR THE EVALUATION OF SUBSTANCES

DRAFT FINAL VERSION

The PC program EUSES is designed to be a decision-support system for the evaluation of the risks of substances to man and the environment. The system is fully described in the EUSES documentation and is based on the EU Technical Guidance Documents for risk assessment of new and existing substances. The documentation and program can be obtained from the European Chemicals Bureau, Ispra, Italy. This bureau also provides helpdesk facilities, tel: +(39) 332-785.866

The development of EUSES was commissioned by the Netherlands Ministry of Housing, Spatial Planning and the Environment, the European Commission, the UK Department of the Environment, the Danish EPA, the German Umweltbundesamt, and the Swedish National Chemicals Inspectorate.

The work was supervised by an EU working group comprised of representatives of the organisations mentioned above, the European Centre for Ecotoxicology and Toxicology of Chemicals (ECETOC) for the chemical industry and the French authorities. The Netherlands National Institute of Public Health and the Environment (RIVM) was responsible for the scientific aspects of the development of EUSES and was also represented in the working group.

The OECD and the UK Health and Safety Executive were observers in the working group. The latter were responsible for the development of the EASE model, which was incorporated in EUSES.

TSA Group Delft bv was responsible for programming the system.

It is recommended that experts in the risk assessment of substances are responsible for the evaluation and selection of data and the application of the system. Adequate interpretation of the results of the system is required as a basis for risk management decisions.

The parties mentioned above are not responsible for the consequences of the operational use of EUSES.

Back to EUSES


Preliminary version 1

General

The preliminary version 1 (P1) is intended for the evaluation of the user interface and the model calculations by a selected group of experts. It must not be used for risk-assessment. It does not support import from other systems, database operations or reporting. These issues will be present in the preliminary version 2 (P2).

Program Restrictions

Only one chemical and one usage is allowed. The ability to add more chemicals (HBM) and usages will be present in the P2 version.

All life cycle steps are generated for testing purposes. The P1 version ignores the selections of the relevant life cycle steps.

Import of Hedset and Snif files is not possible. Only the file selection dialog boxes are implemented.

No database operations are allowed in this version. Use Import/EUSES to load studies and Export/EUSES to save studies. The database user interface is implemented.

No actual reporting is done. The P1 version contains the interface structures necessary for reporting (File/Print Setup and Assess/Print options).

The Edit/Cut, Edit/Copy and Edit/Paste options are not implemented.

Model Restrictions

The Ease model (Assessment type 5) is not supported in the P1 version. It will be present in the P2 version.

A separate list, containing model interpretations and restrictions, will be shipped with the P1 version. Please inspect this list carefully.


Definitions
Definitions of EUSES

Assessment type	Mode

Base set	Node

Block	Outline

Defaults	Parameter

EUSES	Section

HBM	SNIF

HEDSET	Substance

Hydrocarbon Block Method	Study

Intermediate results	Use pattern


Study identification

The study identification section contains :

Name 	Name of the study, must be unique because it is used as a key value in the database.

Description	Description you can use to search for a study in the database.

Author	Author of the study and address information. These data will be added to the report.

Institute

Address

Zipcode

City

Country

Telephone	Telephone, fax and E-mail (optional).

Telefax

E-mail


TSA Group Delft

TSA Group Delft bv programmed this EUSES version:

TSA Group Delft bv

Poortweg 4e

2612 PA Delft

Netherlands

Tel:	+(31) 15 - 2.624.955

Fax:	+(31) 15 - 2.569.736

E-mail:	tsagroup@dataweb.net


RIVM

RIVM (National Institute of Public Health and Environmental Protection)

Toxicology Advisory Centre

Antonie van Leeuwenhoeklaan 9

P.o. box 1

3720 BA Bilthoven

Netherlands

Tel:	+(31) 30 - 2.749.111

Fax:	+(31) 30 - 2.744.401


VROM
Netherlands Ministry of VROM

Netherlands Ministry of Housing, Spatial Planning and the Environment.

Directorate-General for the Environment

Directorate for Chemicals, Safety and Radiation Protection

Risk Assessment and Environmental Quality Division

IPC 655

P.O. Box 30945

NL-2500 GX THE HAGUE

The Netherlands


European Chemicals Bureau

European Chemicals Bureau

Joint Research Centre I

I-21020 Ispra (VA)

Italy

Tel: +(39) 332-785.866


Technical Guidance Documents

EC (1996).

Technical Guidance Documents in support of the Commission Directive 93/67/EEC on risk assessment for new notified substances and the Commission Regulation (EC) No. 1488/94 on risk assessment for existing substances. Brussels, Belgium, Commission of the European Communities.


Background report on EUSES

EUSES, the European Union System for the Evaluation of Substances.  March 1996

Bilthoven, National Institute of Public Health and the Environment ( RIVM).


Accelerators

Accelerators are keys that give you direct access to a menu option. E.g. <Ctrl-A> to select an assessment.


Components of EUSES

The following figure shows the main window of EUSES. Click on the appropriate section for more information.


Keys of EUSES

Select one of the following subjects:

Standard keys

The standard key usage of EUSES is the standard key usage of Windows.

Accelerators

Some menu options are accessible by a special key (also known as an accelerator).

Outline keys

Select this subject to find out which keys you may use in the outline.


Working with EUSES

To run an assessment :

1.	Load a study from the database or work on a new study.

2.	Choose Assess/Select from the menu (or press <Ctrl-A>)

2.1	Select the assessment types, determining the scope of the risk characterization

2.2	Check whether you want to use the Hydrocarbon Block Method (HBM)

2.3	Choose the mode

-	Direct mode if you prefer minimal input and do not want to inspect and/or edit the intermediate results.

-	Interactive mode if you want to inspect the intermediate results and replace them if necessary.

-	Outline mode if you want to work directly on the outline. While the other modes guide you through the input and (intermediate) results, the outline mode will not.

3.	Press the [Ok] button. The outline will be rebuild to reflect the selections you made.


Menu options of EUSES

The menu options of EUSES are:

File	Access to database functions, import, export, printer setup and exit

Edit	Edit option, search option and outline collapse and expand options.

Assess	Select assessment types, start assessment, reset calculations and reporting options.

Defaults	Edit, load, save and reset defaults.

System	System options (interface settings) and EUSES directories.

Help	Access to several help pages and the about EUSES window.


Save to the database

You can save database entities  to the EUSES database. However, you must always supply a name and a description. These can be entered in the identification section. E.g. to supply a name and description for the defaults, locate the defaults section in the outline, expand it (double-click or '+' key), go to the defaults identification section and edit it (Edit/View option in the Edit menu, or <F2>). Save these values with [Ok]. Next, choose Defaults/Save and press [Ok]. Defaults already containing the name will be overwritten. If the name is new, the set of default data will be appended to the database.


Load from the database

You can load database entities from the EUSES database. These entities are always identified by a unique name and a description. You can search for a given name and/or partial description with the [Search] button.

Loading a study from the database


Erase from the database

To erase a database entity from the EUSES database do the following:

-	Select the entity you want to erase from the table

-	Select [Erase] followed by [Ok]. Choose [Cancel] if you selected the wrong entity, or you do not want to erase the entity at all.


Search through the database

You can search through the database on the (first letters of the) name and/or a part of the description. If a database entity is found that matches the given conditions, it will be highlighted, else an error message appears. Press the [Close] button to stop the search.


EUSES error messages

EUSES error messages contain a description of the error and one or more possible solutions.


EUSES range error

The range error message appears if you enter a value that is outside an advised range. You may select one of the following options:

Set to minimum	-	Set the value of the parameter to the advised minimum

Set to maximum	-	Set the value of the parameter to the advised maximum

Accept value	-	Accept the value as entered (bypass the advised range)

Resume editing	-	Enter a new value


System menu
Windows system menu

The windows system menu button allows you to close the application, change it size or activate the task manager (Windows 3.1). See your Windows manual for more information.


Windows caption
Windows caption.

The windows caption contains the name of the window. Click and hold your left-mouse button to drag the window. See your Windows manual for more information.


Windows size buttons

The minimize button minimizes your window. Only an icon will be shown on the desktop. The maximize button enlarges your window to full screen size. See your Windows manual for more information.


EUSES menu

Click on this part to select the menu options. The options are explained in more detail in the menu options of EUSES.


EUSES Toolbar

The toolbar contains buttons that give you direct access to several EUSES functions. A button description appears after a few seconds if you place the mouse cursor on the button.


EUSES Outline

All data of EUSES are organized in the outline. You can browse through this outline, open sections that you want to inspect or edit, close sections that you are not interested in and edit or view the corresponding parameters.

A pop-up menu appears if you click on the right-button of the mouse or press <F10>.


EUSES Statusbar

The statusbar contains the name of the current study, the name of the selected defaults (non-substance data), the selected assessment types (I - V), use of the Hydrocarbon Block Method (HBM), the working mode (direct or interactive - not shown in this example) and the 'base set completed' indicator


Selected section in the outline

The selected section in the outline is highlighted. Menu and toolbar operations on sections (like edit, view, collapse and expand) are always on the selected section. You can select a section by clicking on it, or by using the cursor keys.


Versions of  EUSES
EUSES Versions

Several versions of EUSES were released during development. These versions were:

P1	Preliminary version 1

IR1	Intermediate release 1

P2	Preliminary version 2

IR2	Intermediate release 2

DF	EUSES draft final version

EU	EUSES Final version


Intermediate Release 1

The EUSES Intermediate Release 1 is the direct successor of preliminary version 1

Many enhancements are introduced in this version, but it has several limitations that you should check first.

The enhancements are:

-	Several model calculations are fixed. These are presented in the blacklist with a solution.

-	Performance is better

-	Intermediate results can be explicitly overwritten by the user ; these overwritten values will be used in subsequent calculations

-	Extra options are introduced to search for parameters and to get more information about them (model name, range and default).

-	Parameters show their state (defaulted, set, output). Precision is limited for result parameters.

-	Edit will guide you to the first editable section. (<F2> key, Edit in pop-up and main menu). All windows are implemented.

-	STP model supports monod kinetics

-	Input windows can be maximized on startup with a special system option.

-	A preliminary reporting option is implemented. This report is for testing purposes only. It is not the EUSES report.


Limitations of Intermediate Release 1

The EUSES IR1 version has got the following limitations:

-	Only one chemical is supported if you use the Hydrocarbon Block Method

-	Only one use pattern is supported if you do not use the Hydrocarbon Block Method

-	All life-cycle steps are generated, regardless of the settings of 'Emission Input Data'

-	Direct and interactive mode are not supported

-	No database options

-	No HEDSET import

-	No SNIF import

-	Cut, copy and paste options are not operational

-	System/Directories settings do not keep their data

-	Intermittent releases are not supported

-	No EASE model


Standard keys of EUSES

The standard key usage of EUSES is the standard key usage of Windows.

<F1>	Help.

<Tab>	Move to the next field or button.

<Shift-Tab>	Move to the previous field or button.

<Enter>	Select a menu option, move to next field, select button

<Esc>	Leave current window (no values are stored) or menu item. Clicking the [Cancel] button in a window gives the same reaction.

<Alt- Underlined letter>	Select the menu or menu option with the underlined letter, e.g. <AltA> selects the Assess option.

<PgDn>	In interactive/direct mode: move to the previous input window

<PgUp>	In interactive/direct mode: move to the next input window

Keys of EUSES


Accelerator keys of EUSES

Some menu options are accessible by a special key (also known as an accelerator): These keys are :

<Ctrl-A>	Assess/Assess select

<Ctrl-D>	Assess/Direct mode assessment

<Ctrl-I>	Assess/Interactive mode assessment

<Ctrl-L>	File/Study/Load

<Ctrl-P>	Assess/Print

<Ctrl-O>	Assess/Outline mode assessment

<Ctrl-S>	File/Study/Save

<Ctrl-X>	File/Exit

<F1>	Help/Context

<Ctrl-F1>	Help about selected parameter in the outline or input window.

<F2>	Edit/Edit/View

<Ctrl-F2>	Edit/Goto

<F3>	Edit/Search

<F9>	Assess/Start

<F10>	Outline pop-up menu.

Keys of EUSES


Accelerator keys of EUSES
Outline keys of EUSES

The following table contains the keys that may be used in the outline:

+	Expand current section

-	Collapse current section

*	Expand all subsections of current section

<Enter>	Expand, collapse, edit (Same as double-clicking the mouse)

<Home>	Move to top of outline

<End>	Move to end of outline

<PgUp>	Move one page up

<PgDn>	Move one page down

<Ctrl-PgUp>	Move to section at the top of the window

<Ctrl-PgDn>	Move to section at the bottom of the window

<F1>	Context help (description of current section)

<Ctrl-F1>	Help on current parameter

<F2>	Edit/view

<Ctrl-F2>	Edit/Goto - Goto this window in the selected working mode

<F3>	Edit/Search

<F10>	Pop-up menu (or right mouse-button)

Keys of EUSES


Definition of blocks
Blocks

Components of a substance are chemically pure entities in principle characterised by one structural formula.

Blocks consist of single component or a large number of components with similar fate and distribution properties. This concept is applied in the Hydrocarbon Block Method.


Definition of HEDSET
HEDSET

Harmonized Electronic Data SET.


Definition of intermediate results
Intermediate results

Parameters that get a value as the result of the calculation of a EUSES submodule. If they can be used in further EUSES calculations, they are open (i.e. editable), else they are closed (i.e. non-editable).


Definition of modes
Mode

A method of interaction. EUSES supports a direct mode with minimal input, an interactive mode that shows all intermediate results and allows you to change them and an outline mode that operates directly on the outline, giving you full control.

See also:

Working with EUSES


Definition of node
Node

A part of the outline that cannot be expanded further. Nodes represent values of parameters.


Definition of outline
Outline

The part of the interface that contains all data for the current study in a hierarchical manner. The structure of the outline will reflect the selected assessment types and the use of the HBM.


Definition of parameter
Parameter

Parameters represent model variables, either input, defaults, intermediate results or output. Parameters which values can not be changed are called closed parameters. Parameters can be defaulted (no value assigned yet), set (value was input or overridden) or calculated (the result of a calculation).


Definition of section
Section

A part of the outline that can be expanded. It contains other sections and/or nodes.


Definition of SNIF
SNIF

Substance Notification Interchange Format.


Definition of use pattern
Use pattern

All data related to a single usage of a chemical, characterized by one Industry Category and one Use category.


Preliminary version 2

General

The preliminary version 2 (P2) is intended for evaluation purposes by a selected group of experts. It must not be used for risk-assessment.  It has certain restrictions, that you should check first. If you did not see the intermediate release 1 version (IR1), you are advised to inspect the IR1 version information, because it contains many fixes on the preliminary version 1. A second intermediate release (IR2) is planned to be distributed on the workshop. This version will contain the EUSES database and some further enhancements.

The enhancements of P2 are:

-	Direct and interactive mode are available

-	The outline is restructured entirely

-	You may supply several use patterns for a single substance

-	The Hydrocarbon Block Method  is implemented

-	The term 'Component' is introduced for 'Chemical'.

-	Facilities to produce the full report (all data in the outline), limited compact report

-	More help available explaining model backgrounds

-	Table browsers for use patterns and components replace the cut, copy, paste, add and delete options.

-	Implementation of the EASE model as assessment type V

-	All RCRs and MOS represented in a single table.


Outline enhancements of P2
Outline enhancements of version P2

The outline of version P2 is restructured entirely according to proposals of the testers and the RIVM.

Substance

-	No component (former chemical) identification if a single substance is used

-	All effects and exposure data moved to the Effects and Exposure sections of the outline

Defaults

-	Tab controls used for a better arrangement of data

Release estimation

-	Industrial categories 11 and 13 available

-	Intermittent releases

-	Local emissions available in one table, with the ability to hide insignificant emissions, bypass the STP and select the type of local STP (with or without primary settler)

Distribution

-	Monod kinetics (already available in IR1)

-	STP as a separate subsection of Distribution in the outline

Exposure

-	Separate exposure section in the outline with all relevant data

-	Separate subsection for bioconcentration factors

-	Rearrangement of consumer exposure

Effects

-	Separate effects section in the outline with all relevant data

-	Birds, mammal and humans effects in separate subsections (and windows)

Risk characterization

-	Separate risk characterization section in the outline with all relevant data


Use of Enter in the outline
Use of <Enter> in the outline

If you use the <Enter> key or the mouse double-click in the outline:

On a node:	Edit or view the corresponding parameter

On a section:	Expand the section if it is collapsed, collapse the section if it is expanded.


Working in direct mode

The direct mode is the easiest manner to operate EUSES. Novice users are advised to start with this mode before they start working with the more advanced features like the interactive and the outline mode. Users that do not want to change the intermediate results should use this mode also.

4.	Select Assess/Start (or press <F9>), or type <Ctrl-I>

5.	EUSES will present the first input window. Enter the necessary values. Use the help key (<F1>) if you are not sure which parameters are required, or what is meant by a certain parameter. Click here for a further explanation of entering values.

6.	The window contains the following navigation buttons:

[Next] 	Go to the next input window.

[Finish] 	Finishes the assessment and leads you to the reporting options.

[Previous] 	Step back to the previous input window

[Abort] 	Leave the window and return in the outline.

Use the [Next] button to skip to the next window. Next, enter the input parameters and continue until the [Finish] button is enabled. This button will finish the assessment and start the reporting options.

Back to working with EUSES


Working in interactive mode

The interactive mode is an enhancement of the direct mode. It operates in the same manner, but it contains all intermediate results. Their values may be changed. When you continue, using the [Next] buttons, the changed values are used in the calculations. This mode therefore allows you to replace estimated values with better measured data.

4.	Select Assess/Start (or press <F9>) or type <Ctrl-D>

5.	EUSES will present the first input window. Enter the necessary values. Use the help key (<F1>) if you are not sure which parameters are required, or what is meant by a certain parameter. Click here for a further explanation of entering values.

6.	The window contains the following navigation buttons:

[Next] 	Go to the next input window.

[Finish] 	Finishes the assessment and leads you to the reporting options.

[Previous] 	Step back to the previous input window

[Abort] 	Leave the window and return in the outline.

Use the [Next] button to skip to the next window. Next, enter the input parameters, view the intermediate results and change them where needed. The [Finish] button allows you to skip the intermediate results. This button behaves as a switch to the direct mode.

Back to working with EUSES


Working in outline mode

The outline mode offers you the highest level of control, but no navigation facilities. It is intended for expert users. You can replace results with better values, adjust input or defaults again and restart the assessment. The organization of the outline allows you to open the sections of interest and close any results that might not be interesting at first.

A user who works in the outline mode would :

4.	Locate the appropriate sections by either expanding the sections (‘+’ and ‘*’ keys or pop-up outline menu (<F10>)) or search a certain parameter (Edit/Search or <F3>).

5.	Enter values with Edit/Edit (<F2>)

6.	Start the assessment with Assess/Start (<F9>), or type <Ctrl-O>

7.	Inspect the results (like step 4)

8.	Replace estimates with better values, adjust defaults if necessary (like step 5)

9.	Start the assessment again (like 6), etc.

This method of risk assessment is based on a very important EUSES principle:

A parameter that is set by the user can not be overwritten by a calculated value

The user can however ‘unset’ a parameter. This is one of the methods to enter a value for a parameter.

Back to working with EUSES


Entering values in EUSES

Parameters in EUSES can be numerical, text only (e.g. study name), or offer a choice from a fixed list (e.g. Industrial Category).

Parameters have the following properties:

-	The description

E.g. 'Vapour pressure'

-	The input area

This is the box containing the value. If this box has the same background colour as the window, the parameter can not be altered. Such a parameter is closed.

-	The unit	(Numerical parameters only)

E.g. [Pa]. If several units are allowed, there will be a box around the unit.

-	The state indicator

The little square box with a single letter.


Units of numerical parameters

If the unit is surrounded by a box, you may change it. Use the up and down cursor keys to browse through the unit list. Note that a EUSES unit should not be interpreted as a physical unit; it is a conversion factor for representation purposes. The octanol-water partitioning coefficient (Kow) supports units [-] and [log10], allowing you to enter the value or its log.

If you first enter the number and then the unit, EUSES assumes that you want to enter the value in the given unit and does not convert the number.

However, if you change the unit and not the number, EUSES assumes that you want to convert the number to this unit and represents it according to its new unit.

E.g., you enter 2.8 for Kow; next select the [log10]; press the <Tab> key, the number will not change. Now select unit [-], and press <Tab> again. The number will be converted.

Note that although some parameters are closed, you can change the unit.


State of parameters

The state indicator reflects the last change of the parameter. It contains one of the following letters:

d	The parameter was defaulted (neither set nor output)

o	The parameter is output (estimated)

s	The parameter was set by the user


Working with the EUSES database

You can save your study at any moment and continue later on. The part of EUSES used to save and store data is called the database. This database supports four kinds of related data groups (or database entities):

Study

All data related to the current assessment

Defaults

The non-substance related data

Substance

Physico-chemical properties, exposure, effects and usage data.

Block

Part of a Hydrocarbon Block. Physico-chemical properties, exposure and effects data

You can select the database operations from the File menu for study, substance and block and from the Defaults menu for the defaults.

Every database entity has an identification section. It contains at least:

Name	This name must be unique for the entity

Description	The description can be used to search through the database

Saving a study

Loading a study

Back to working with EUSES


Saving a study

1.	Select the section ‘Study identification’ and click the left-mouse button. Next press <F2>.

2.	Enter at least a (unique) name.

3.	Select option File/Study/Save (or type <Ctrl-S>). A message appears that confirms that your study was saved. If the study already existed, you will get a warning before the study in the database will be overwritten.


Loading a study

1.	Select option File/Study/Load from the menu (or type <Ctrl-L>)

2.	If you made any changes to the current study in the outline, EUSES will advise you to save your study first,

3.	EUSES shows a special input window : the database browser. You can use the scroll bar at the right,  the cursor keys and the <PgUp> and <PgDn> keys to browse through the list of names and descriptions. If you know the name, use the [Search] button.

If you found the study, select it with either the cursor keys or the mouse and press the [Load] button.

4.	The outline will be rebuild, containing the study from the database.


Entering a numerical value

To enter a value for a numerical parameter, move the mouse cursor to the input area and click the left mouse button. You can also use the <Tab> and <Shift-Tab> keys to move to the input area. Note that you can not move to a closed parameter.

Next you enter the numerical data by typing:

1.	The number

2.	A question mark (?) if you want to assign the default value (or previous calculated value)

3.	The greater-than sign (>) followed by a number, e.g. ‘> 12e3'. The parameter has a value that is greater than the entered value.

4.	The less-than sign (<) followed by a number, e.g. ‘<1.414'. The parameter has a value that is less than the entered value.

All digits entered are considered to be significant. Calculated parameters show only 3 significant digits. Defaults show as many digits as necessary (e.g. 8.314 for the gas constant).

Parameters that have no value yet or are calculated using illegal input values (e.g. result of a division by zero) are represented by ‘???’. Such a parameter has the value ‘no-value’.


Restrictions of preliminary version 2

Program Restrictions

Import of Hedset and Snif files is not possible. Only the file selection dialog boxes are implemented.

Compact report prints set parameters only. The summary report will be present in the IR2 version.

No database operations are allowed in this version. Use Import/EUSES to load studies and Export/EUSES to save studies. The database user interface is implemented. The database will be part of the IR2 version.

Model Restrictions

A separate list, containing model interpretations and restrictions, will be shipped with the P2 version. Please inspect this list carefully.


Exposure

Select one of the following subjects for further information:

Bioconcentration factors

Secondary poisoning

Humans exposed to or via the environment

Consumer exposure

Humans exposed at the workplace


Search for a parameter

Use the search option if you want to locate a certain parameter, but do not know the exact position in the outline. You can either search on the exact name as it is specified in the  background report or on the (partial) description. The search option is case insensitive.

If you want to search on a specific description, check 'Search on description'. EUSES will now search for parameters with a description containing the search text. If you want to find multiple occurrences of a parameter or find parameters with the same text in a certain description, check 'Search from current position'.

E.g. if you want to locate BcfFish, check 'Search on name', check 'Search from top', enter bcffish as search text and click the [Search] button. EUSES will show the corresponding parameter and its value.

If you want to locate all parameters containing ‘bioaccumulation’ in their descriptions, check ‘Search on description’ and ‘Search from top’, next click the [Search] button. To view the next parameter, check ‘Search from current position’ and click the [Search] button again.

If no parameter is found, an error message will pop-up.

Please note that this option is valid for parameters, not for sections!


Report options

EUSES offers the following report options:

Full report

Reports all parameters in the outline (including defaults and intermediate results). Only data that are relevant for the current assessment types are printed.

Compact report

Reports only input data, set defaults, set intermediate results and output.

Summary

Special short summary report.

Furthermore you can select the output device:

Printer

Send the report directly to the printer. No additional options (e.g. page selection). No preview. Use the [Select] button to select the printer or alter the options of the printer.

Preview

The report is first shown on the screen. If you want to print it, press the [Print] button in the previewer. You may now select the page(s) to be printed and the number of copies in the Customize Print window.

File

Send the report directly to a file. You can specify the file name in a standard Windows save file dialog.


RCR Result Table
The Risk Characterization Ratio result table

The RCRs and MOSses for environmental assessments (types I,II and III) are presented in a special table: the RCR result table. This table contains all applicable local and/or regional RCRs and MOS.

Rows (horizontal) contain all RCRs and MOS for a certain spatial scale (either a local use pattern with life-cycle step or regional).

The 'Spatial' column (spatial scale) shows the number of the use pattern and the corresponding life-cycle step for local assessment. It contains the word 'Regional' in case of regional RCRs and MOS.

The 'Relevant' column is used to indicate which RCRs are relevant for reporting. It contains the letter 'X' if the row  is relevant, otherwise it is empty. You can change the relevance by double-clicking on the row.

P2 restriction: Although you can check relevant columns, the report will always output all spatial scales.

Other columns contain either a RCR or a MOS. The appearance of the table depends on the selected assessment types. If you do not select assessment type II (Predators exposed to the environment), the RCRs for fish and worms will be missing.


System options

The System/Options menu item allows you to alter the look of the EUSES interface. You may:

Show the toolbar or hide it

Show the statusbar or hide it

Show the about box on startup

Maximize input windows on edit

Change the font of the outline

Change the font of the report

Select the [Ok] button to save the entered data and return to the outline. Select the [Cancel] button to ignore all changes and return to the outline.


Input windows
Input windows of EUSES

Select one of the following subjects for further information:

An input window	called from the outline with Edit (<F2>)

An input window	in direct or interactive mode

A table window	used to add use patterns or blocks


Input window called from the outline

Use Edit/Edit or <F2> to show the input window belonging to the current section. The figure below shows the physico-chemical input window.


Input window called during the modes

In interactive or direct mode EUSES shows all input windows belonging to the selected assessment types.. The figure below shows the physico-chemical input window.


Table windows

Table windows are used for use patterns and blocks. You may add and/or delete these items. The following window shows an example of the use patterns table window.


Input area

Part of the window that contains parameters that can be viewed and/or input.


Parameter description

Description of the parameter.


Parameter input area

Area where you can specify the value of the parameter.

More information about entering values


Parameter unit

Area that contains the unit of a parameter


Parameter state area
Parameter state

Area that contains the state of the parameter.


Parameter unit box

Area that contains the unit of the parameter. This unit can be altered.


Previous button

This button closes the current window and goes to the previous one.


Next button

This button closes the current window and goes to the next one.


Abort button

This button aborts either the direct or interactive mode and leads you back to the outline


Finish button

This button skips all intermediate result windows (in interactive mode) and goes to the next real input window.


Help button

This button shows the help subject about the current window


Ok button

This button closes the current window, saves all entered results and returns in the outline.


Cancel button

This button closes the current window, restores the previous values and returns in the outline.


Insert button

This button inserts a new use pattern or block, depending on the window you are using. The new line is always inserted before the highlighted row.


Delete button

This button deletes an existing use pattern or block, depending on the window you are using.


Table area

This area contains the table. It consists of rows (horizontal) and columns (vertical).


Focus cell in a table area

The cell that has focus might be changed by double-clicking.


Edit button

This button presents the input window with the data of the current row in the table.


Intermediate Release 2

The EUSES Intermediate Release 2 is the direct successor of preliminary version 2

Many enhancements are introduced in this version, but it has several limitations that you should check first.

The enhancements are:

-	Database functions are implemented

-	Summary report is available

-	Extra NOECs for aquatic and terrestrial effects input


Limitations of Intermediate Release 2

The EUSES IR2 version has got the following limitations:

-	No HEDSET import

-	No SNIF import


Obsolete feature

This feature is not supported anymore in the current version


EUSES Helpdesk

The European Chemicals Bureau provides the EUSES helpdesk facilities.

Tel: +(39) 332-785.866


System directories

In this window you can change:

EUSES directory	This directory contains the executable, emission tables and initialization file (euses.ini)

Database directory	This directory contains the database

To change the directory, press the appropriate directory button and select the drive and directory. You can view the subdirectories by double clicking on a directory.


Substance identification

The substance identification section contains :

Name 	Name of the substance, must be unique because it is used as a key value in the database.

Description	Description you can use to search for a substance in the database.

CAS-no	Further identification numbers for new and existing substances

EC-notification no.

EINECS no.


Block identification

The block identification section contains :

Name 	Name of the block, must be unique because it is used as a key value in the database.

Description	Description you can use to search for a block in the database.

Fraction	Fraction of the total Hydrocarbon Block


Defaults identification

The defaults identification section contains :

Name 	Name of the defaults data set, must be unique because it is used as a key value in the database.

Description	Description you can use to search for a defaults data set in the database.


Printer options

The following printer options are supported:

Full

Print all pages

Current page

Print the current page in the preview window

Select

Enter the pages you want to be printed

Copies

Number of copies to be printed


Local emissions table

This table contains the local release estimations. You may check the emissions you want to be shown in the outline, the compact and the summary report. Note that the full report always contains all local emissions, regardless of these selections.

Use edit to view and/or alter the data of the selected local emission.


Base set

The Base Set of input parameters is considered complete according to annex VIIa of EC Directive 92/93/EEC when the following input parameters are all set by the user:

1.	Substance name

The default text must be replaced by something else

2.	Quantity produced in EC

Although Tonnage has a default value (0) it must be explicitly set (parameter status “s”) in order to satisfy the condition for “Base Set complete”

3.	Industrial category

Although IndCat has a default value (“15/0") it must be explicitly set (parameter status “s”) in order to satisfy the condition for “Base Set complete”

4.	Use category

Although UseCat has a default value (“55/0") it must be explicitly set (parameter status “s”) in order to satisfy the condition for “Base Set complete”

5.	Melting point

6.	Boiling point

7.	Vapour pressure

8.	Octanol-water partition coefficient

9.	Water solubility

10.	Result of biodegradability test

Although BioDegradable has a default value (“not biodegradable") it must be explicitly set (parameter status “s”) in order to satisfy the condition for “Base Set complete”

11.	L(E)C50 for fish

12.	L(E)C50 for Daphnia

13.	L(E)50 and/or NOEC for algae

This condition is satisfied when at least one of these two is given

14.	IC50 and/or NOEC for micro-organisms (STP)

This conditions is satisfied when at least one of these two is given

15.	At least one of the following:

- Ld50MammalOral/ DdMammalOral

16.	At least one of the following:

- Ld50MammalDer/ Lc50MammalInh

17.	At least one of the following:

-	NoecMammalFoodChr/ NoaelMammalOralChr/ NoaelMammalInhChr/ NoaelMammalDerChr/

NoecManMediumChr/ NoaelManOralChr/ NoaelManInhChr/ NoaelManDerChr

The molecular weight (Molw) is not required for the “Base Set complete” test. However, the EUSES program also needs this parameter for making calculation.


EUSES Draft Final Version

The EUSES Draft Final Version is intended for evaluation purposes by a selected group of experts. It must not be used for risk-assessment. This version is the immediate successor of Intermediate Release 2 (IR2).

It contains the following new features:

-	HEDSET import according to the Chemical Interchange Format

-	The statusbar contains a 'base set complete' indicator

-	The compact and summary report suppress spatial scales that are marked irrelevant in the Risk Characterization Result table

-	Reports can be sent to the previewer, printer and/or file. Using the previewer, you can select which pages to print

-	A flag shows when the concentration (surface water and STP effluent) exceeds the solubility

-	Release estimation input contains a flag that shows whether a specific emission document is available

-	You can goto a window that belongs to the selected section in the outline and continue from this point in the chosen mode. Use either the Edit/Goto menu option, the goto option in the pop-up menu or the <CtrlF2> key

-	The influent concentration (as well as the emission mass) can be used as STP input

The following changes are introduced:

-	Consumer exposure was restructured. It estimates data directly from other input parameters

-	Human and mammalian input are further separated

-	More unit lists are available for several parameters


Physico chemical properties

Physico-chemical properties are the primary data of the chemical required to run EUSES. These parameters must be entered by the user, there are no defaults or estimation routines in EUSES to estimate these properties.

The following physico-chemical properties can be entered:

1. Molecular weight. The main use of this parameter is in the unit conversion of Henrys law constant.

2. Octanol-water partition coefficient or Kow. A measure of the hydrophobicity of the chemical. Kow is a key parameter of the system since many estimation routines are based on this parameter. It should be noted that for surface-active compounds and inorganic compounds (e.g. metals and metal compounds), Kow may not be an accurate predictor for estimating partition coefficients or bioconcentration factors. For ionising chemicals, the pH dependence of Kow must be investigated. QSARs for Kow are discussed in Chapter 4 of the TGD.

When no Kow is entered by the user, partition coefficients and bioconcentration factors must be entered manually. It should be noted that the BCF for aquatic biota in the regional model will always be calculated from Kow (using the standard QSAR for BCF fish) since a measured BCF for fish cannot be representative for all aquatic biota. This BCF is only used to calculate the dissolved fraction in surface water in the regional/continental distribution model. If no Kow value is available, this BCF is set to zero. When, however, sorption to biota is thought to be relevant, this can be taken into account by manually adjusting the partition coefficient for suspended matter in water.

3. Water solubility. For ionising chemicals, the pH dependence of the water solubility must be investigated. In general, water solubility is correlated with the octanol-water partition coefficient. However, no QSARs to estimate solubility are implemented. No temperature correction is implemented.

4. Vapour pressure. A value is required which is measured at 25 Celsius. No temperature correction is implemented for the local and regional fate models. In the assessment of human exposure at the workplace, a correction of vapour pressure from 25 degrees to the process temperature is always applied.

5. Boiling point. This parameter is only required for emission estimation in the Industrial Category 11 (polymers industry) and for human exposure at the workplace.

6. Melting point. The melting point is used in the calculation of the sub-cooled liquid vapour pressure which is used to estimate the fraction of the chemical bound to aerosol particles. When this parameter is not entered, the chemical is assumed to be liquid at the environmental temperature. This parameter is furthermore used for human exposure at the workplace.

Parameters 1 to 4 are required for all environmental risk assessments.


Note on temperature correction

Experimentally derived chemical properties will usually be measured at a standard temperature which is different from the temperature used in the models of EUSES. For most chemicals and most properties, a temperature correction will not be necessary between the standard 20 or 25 degrees and the environmental temperature used in the system (by default 12 degrees Celsius in the environment and 15 degrees in the STP). For the local and regional fate models, no temperature correction is carried out as no extrapolation method is specified in the TGD.

Nevertheless, for chemicals were considerable differences are expected within this temperature range, entering a more relevant value (measured or extrapolated) is advised (note that in that case care must be taken with the assessment of human exposure at the workplace where a correction of vapour pressure from 25 degrees to the process temperature is always applied).

When applying simple temperature corrections for the vapour pressure, care must be taken when the melting point is within the extrapolated temperature range. The vapour pressure of the solid phase is always lower than the extrapolated vapour pressure of the liquid phase. A correction will therefore tend to overestimate the vapour pressure.

Biodegradation

In the extrapolation of rate constants for biodegradation from standard biodegradation tests, the temperature difference between experiment and environment is already accounted for. When measured degradation rate constants are available, the temperature dependence may be investigated. The STP module offers an option to apply a temperature correction to degradation rate constants.


QSAR

Quantitative Structure-Activity Relationships. Estimation routines for a certain parameter, based on the known properties of a chemical (e.g. physico-chemical properties). Chapter 4 of the TGD gives guidance for the use of QSARs in risk assessment. Several QSARs are implemented in EUSES (e.g. for the estimation of Koc and BCFs).


The EUSES Model

The European Union System for the Evaluation of Substances (EUSES) was developed for quantitative assessment of the risks posed by new and existing chemical substances to man and the environment. This assessment must be transparent to all users and easy to perform, and EUSES is therefore, well-documented and available as a user-friendly computer program. As required, the risk assessment system is attuned to current chemical management policies and in accordance with the principles laid down in the TGDs for new and existing substances of the European Commission. An assessment is performed for human and environmental endpoints. EUSES is an update of USES 1.0.

EUSES is designed to support decision-making by risk managers in government agencies, scientific institutes and industry in the evaluation of new and existing chemical substances. On the basis of the results of the risk assessment process, of which EUSES can be an important element, and taking other factors into account (e.g. political, social, economic and engineering factors), risk managers may take decisions with respect to regulatory actions to be taken.

In line with most assessment procedures, EUSES can be used to carry out tiered risk assessments of increasing complexity, requiring additional data. Using OECD terminology, EUSES can specifically be used in the initial, or screening, and intermediate, or refined, stages of assessment With the system, substances can be assessed for their potential risks to man and the environment. On the basis of this screening, it can be decided if more data need to be generated and if a more refined (i.e. intermediate) assessment is necessary. When dealing with (large) numbers of chemicals, this screening can be used to set priorities for data gathering or refined assessments.

EUSES can also be applied for intermediate or refined assessments by allowing the replacement of default values, estimated parameter values, or intermediate results by more accurately estimated values or by measured data. EUSES is not specifically designed for site-specific assessments, but adjustment of parameters may allow for insight into specific local or regional situations.

Risk assessment with EUSES is carried out in a step-wise manner encompassing exposure assessment, effects assessment and risk characterisation. The exposure assessment departs from generic model scenarios at various spatial scales. Both short-term/acute and long-term/chronic exposure are considered. The environmental exposure assessment takes account of the complete life cycle of substances as well as their environmental fate in all environmental compartments. The exposure assessment aims at reasonable worst case results by applying unfavourable, but not unrealistic, standard exposure scenarios and, as much as possible, mean, mean or typical parameter values.

At the risk characterisation stage the estimated exposure level is compared to a suitable effect or no-effect parameter at the appropriate time scale and for the relevant route of exposure. The resulting RCRs can be regarded as indicators for the likelihood of adverse effects occurring.

Preliminary studies into a quantitative uncertainty analysis of EUSES have been performed and will be pursued further. Validation studies have been, and are, performed on parts of the system.

Modules and sub modules of EUSES


USES 1.0

USES 1.0 was released in 1994 and already largely, but not fully, in line with the at that time separate packages of Technical Guidance Documents (TGD) for new and existing substances. It was also much in line with the amalgamated TGD for new and existing substances published in 1996. The major scientific differences between EUSES/TGD and USES 1.0 are:

- USES 1.0 includes a risk assessment system for agricultural and non-agricultural pesticides.

- USES 1.0 allows an uncertainty analysis in the exposure assessment for aquatic organisms; EUSES does not support uncertainty analysis.

- EUSES includes a risk assessment for sediment organisms.

- EUSES includes a risk assessment system for workers (EASE).

- EUSES includes a risk assessment system for complex mixtures (Hydrocarbon Block Method).

- In EUSES, bioconcentration factors for fish are estimated with a different QSAR.

- The model for biotransfer from soil and air to plants in EUSES is an adapted version of that in USES 1.0; the model is adapted according to the approach of Trapp and Matthies.

- EUSES automatically adds up the PEC on the regional spatial scale in the local assessment; USES 1.0 does not.

- EUSES can estimate releases of one substance in different main, industry and use categories in one run; USES 1.0 cannot.

- The sewage treatment plant model SimpleTreat in EUSES is version 2.0 of the one implemented in USES 1.0: more options in defining the sewage treatment environment are possible and formulations of the interaction between the chemical and the engineered environment are improved.

- Default biodegradation rates in sewage treatment plant, water and soil in EUSES differ from those in USES 1.0, although they are still estimated on the basis of the results of standard tests.

- The sludge concentration will be calculated as an average during emission episodes and not recalculated to an annual average as done in USES 1.0. The concentration in soil in the steady-state year resulting from deposition and sludge application is averaged over 180 days in the risk assessment for man (both in EUSES and USES 1.0) and over 30 days in the risk assessment for terrestrial organisms in EUSES (180 days in USES 1.0).

More......

To general information on EUSES


USES 1.0 (continued)

- EUSES distinguishes agricultural soil and grassland; USES 1.0 only includes the former.

- EUSES estimates the concentration in the top soil layer and pore water applying a one-compartment soil model taking into account degradation, volatilisation and leaching to groundwater. USES 1.0 contained the numerical soil and groundwater model PESTLA.

- In case only one experimental data point is available for terrestrial organisms, EUSES derives a PNEC both by using assessment factors and by the equilibrium partitioning method on the PNEC for aquatic organisms. An extra assessment factor of 10 on the PEC for terrestrial organisms is applied in case of substances with a Kow > 5 in view of additional exposure through ingestion. USES 1.0 does not incorporate these methods.

- In case of intermittent release to the aquatic compartment a dedicated PNEC is used in EUSES, i.e. a default assessment factor of 100 is proposed to be applied to the lowest L(E)C50 of at least three short-term tests from three trophic levels. USES 1.0 does not incorporate this method. The risk characterisation for sewage treatment plant micro-organisms will then be based on the influent concentration and not on the effluent concentration (normal situation in EUSES) or the concentration in the aeration tank (USES 1.0).

- EUSES, but not USES 1.0, incorporates a qualitative risk assessment for aquatic organisms in case a PNEC cannot be calculated (no toxicity value or a value indicated by > x mg/l). If required, the PECs on the  local and regional spatial scales are compared to a value derived by dividing the water solubility by 100. This specifically applies to non-polar organic substances with log Kow > 3 or BCF_fish > 100 (see TGD Section 4.5).

- The risk characterisation for predators in USES 1.0 is performed at both the local and the regional spatial scale. In EUSES this risk characterisation is based on an exposure level derived from the average of the local concentration in fish or worm and the background level (regional concentration).

- Many default values for a/o. emission rates, parameters describing the local or regional environment, intakes and assessment factors, differ between EUSES and USES 1.0.

Major technical differences are:

- The operating environment for USES 1.0 is MS-DOS and  for EUSES MS-Windows 3.1 or higher.

- EUSES can import HEDSET-files, SNIF-files and EUSES-files; USES 1.0 does not have these facilities.

- EUSES allows virtually all defaults and estimated parameters, including emission rates,  degradation rate constants and bioconcentration factors, to be overwritten; USES 1.0 contains many closed parameters.

To general information on EUSES


Metals and metal compounds
Metals and organo-metallo compounds

In principle, the models and approaches for organic substances can also be used to estimate exposure to metals. However, there are several differences compared to the use of these models for organic substances. Below, the differences are described.

1.	Physico-chemical properties

In general, water solubility, boiling point and vapour pressure cannot be used. The octanol-water partition coefficient is not appropriate and measured partition coefficients (Kp) should be used instead.

2.	Partition coefficients

Most of the metal present in the atmosphere will be bound to aerosols. Therefore, an extremely low value for the vapour pressure should be used to estimate the fraction bound to aerosol, e.g. 1e-20 Pa. This leads to a value for the aerosol-bound fraction almost equal to one. If a valid measured value is available for the aerosol-bound fraction, this value can be used.

Volatilisation can be ignored for metals, except for mercury compounds and several organo-metallo compounds. Therefore, the Henry coefficient should generally be set to a very low value.

Formulae to estimate Koc cannot be used. Measured Kp-values must be used for water-soil, water-sediment and water-suspended matter. Kp values are influenced by speciation and the speciation behaviour must therefore be accounted for in Kp.

3.	Biotic and abiotic degradation rates

Not relevant for metals. The substances must be specified as non-biodegradable (very high DT50). It should be noted that organo-metallo compounds may be metabolised (the organic part) or even degraded through photolysis.

4.	Sewage treatment plant

For applying the STP model, a partition coefficient is used for water-sludge. For metals, a measured Kp-value must be used.

5.	Calculation of the regional PEC

The values applied for model parameters for the regional model, inter-media mass-transfer coefficients and model parameters for the continental concentration can be used.

6. Environmental effects assessment

PNECs can be derived through the application of assessment factors on the basis of the available data. Evaluation of the toxicity data is critical (TGD, Chapter 3, Appendix VIII). Standard methods applied for organic compounds can be used for this. However, because of the specific mode of action that metals may have for some species, care should be taken in extrapolating short term toxicity data to the PNEC using the standard assessment factors. A prerequisite for the derivation of the PNEC is that it is done on the basis of the same level of availability as in exposure assessment.


Degradation and transformation rates

Transport and  transformation (fate) processes determine the distribution of a substance in the environment, or in organisms, and the changes of the substance in time. Fate thus includes both biotic and abiotic transformation processes. Since measured data on degradation processes are usually not available for the various compartments, they must be extrapolated from standardised laboratory tests. In general, risk assessment focuses on the parent compound. Nevertheless, if stable degradation products are formed, these should be assessed as well.

Biotic and abiotic degradation in air, surface water and sediment is at this moment only taken into account in the calculations of the regional PEC. On the local scale, the residence times in water and air are usually to short too allow for degradation of the chemical.

Biotic degradation

Most of the ready biodegradation tests that are used at the moment are aimed at measuring the mineralisation of a chemical. Hence, they give valuable information on the mineralisation  of a substance and the possible formation of metabolites. However, they do not give information on the primary degradation rate of the parent compound nor do they give a quantitative estimate of the percentage removal in a sewage treatment plant. Therefore, in order to make use of the biodegradation test results that are available and that are requested in the present chemical legislation, rate constants are assigned to the results of the standard tests for use in STP and environmental-fate models. These constants are based on a relatively limited number of empirical data.

Data from non-standardised tests and/or tests not performed according to the principles of GLP may be used if expert judgement has confirmed them to be equivalent to results from the standardised degradation tests.

The following categories of biodegradability are distinguished:

1. Ready biodegradable

2. Ready biodegradable, but failing 10-day window

3. Inherently biodegradable, fulfilling specific criteria

4. Inherently biodegradable, not fulfilling specific criteria

5. Not biodegradable

From this classification, rate constants are derived for the biodegradation in sewage treatment plant, surface water, soil and sediment. However, if better estimates or measured data are available, the half-lifes or rate constants may be used directly. Note on temperature correction.

Abiotic degradation

Apart from biodegradation, abiotic processes can also significantly affect chemical fate in the environment. When half-lifes or rate constants are known, these can be entered:

1. Hydrolysis

2. Photolysis in water

3. Photochemical reaction in the atmosphere

Rate constants for abiotic degradation in the sewage treatment plant, soil and sediment are set to zero. If abiotic rate constants can be derived, these can be changed in the defaults section.


Ready biodegradation
Ready biodegradable

Ready biodegradability testing (28d) (92/69/EEC C.4 A-F, respectively, OECD 301 A-F (1992) or equivalent according to expert judgement).

The conditions used in ready biodegradation tests do not favour biodegradation because the ratio of test substance to micro-organisms is high and the number and/or type of competent organisms may be insufficient for metabolism of the substance.

The degree of degradation may be determined by the loss of dissolved organic carbon (DOC), the evolution of carbon dioxide or the amount of oxygen consumed. It is generally accepted that a substance is considered to be readily biodegradable if the substance fulfils the pass criteria of a test for ready biodegradability (cf. the OECD Test Guidelines or the Annex V methods) which may include the concept of the 10 days time window as a simple kinetic criterion. All biodegradation results should refer to true biodegradation i.e. mineralisation excluding abiotic elimination processes (e.g., volatilisation, adsorption).


Ten-day window
10-day window

If the chemical reaches the biodegradation pass levels within 28 days but not within the 10 day time window, a slower degradation rate is assumed. In case only old ready biodegradation test results (i.e. tests executed prior to the introduction of the 10 days time window criterion and documenting only on the pass level) are available the failing 10-day window  category should be applied in case the pass level is reached.


Inherent biodegradation

Inherent biodegradability testing (28d) (87/302/EEC, respectively, OECD 302 B-C (1981-1992) or equivalent according to expert judgement).

In tests for inherent biodegradability, the test conditions are designed to be more favourable to the micro-organisms in that the ratio of substance to cells is lower than in the ready tests and there is no requirement for the (bio)degradation to follow a time  pattern as in the ready tests. Usually, more than 70% (bio)degradation within 28 days indicates that the substance is inherently biodegradable. However, extrapolation of the results of the inherent tests should be done with great caution because of the strongly favourable conditions for biodegradation that are present in these tests.


Specific criteria for inherent tests

For the STP model, a rate constant of zero is applied for inherently biodegradable compounds, unless it fulfils specific criteria for the different inherent biodegradation tests:

Zahn-Wellens test: Pass level must be reached within 7 days, log-phase should be no longer than 3 days, percentage removal in the test before biodegradation occurs should be below 15 %.

MITI-II test: Pass level must be reached within 14 days, log-phase should be no longer than 3 days.

SCAS test: No specific criteria were developed for positive results in a SCAS test. The chemical will be treated as not biodegradable, irrespective whether it passes this test or not.


Hydrolysis

Values for the half-life (DT50) of a hydrolysable substance can be converted to degradation rate constants, which can be used in the fate models. QSAR methods are available for certain groups of substances, but not implemented in EUSES (they are discussed in Chapter 4 of the TGD). It should be noted that for many substances, the rate of hydrolysis will be highly dependent on the specific environmental pH and temperature.


Photolysis in water

In the vast majority of surface water bodies dissolved organic matter is responsible for intensive light attenuation. Thus photolysis processes are normally restricted to the upper zones of water bodies. The following aspects have to be considered when estimating the photochemical transformation in natural water bodies:

1. The intensity of the incident light depends on seasonal and geographic conditions and varies within wide ranges. For long-term considerations average values can be used, while for short-term exposure an unfavourable solar irradiance (winter season) should be chosen.

2. In most natural water bodies, the rate of photoreaction is affected by dissolved and suspended matter. Since the concentration of the chemical under consideration is normally low compared to the concentration of e.g. dissolved humic acids, by far the majority of the sunlight penetrating the water is absorbed by the natural constituents. Using the standard parameters of the regional model (water depth, suspended solids concentration), the reduction may be as large as 98%.

A half life (DT50) for photolysis can be entered in EUSES and will be applied in the calculation of the regional PEC. In the selection of a DT50, the user should consider the season, attenuation and direct and indirect photolysis processes.


Photochemical reactions in the atmosphere
Photochemical reaction in the atmosphere

Although for some chemicals direct photolysis may be an important breakdown process, for most substances the most effective elimination process in the troposphere results from reactions with photochemically generated species such as OH-radicals, ozone and nitrate radicals. The specific, pseudo first-order degradation rate constant of a substance with OH-radicals can either be determined experimentally or estimated by QSAR-methods (see Chapter 4 of the TGD).


Biodegradation in the sewage treatment plant
Biodegradation in a sewage treatment plant

Most of the ready biodegradability tests in use at the moment are aimed at measuring the mineralisation of a chemical but do not give information on the degradation rate of the parent compound, nor do they give a quantitative estimate of the removal percentage in a sewage treatment plant (STP). Therefore, it is necessary to assign rate constants to the results of the standard tests for use in STP models. These constants are based on a relatively limited number of empirical data. These rate constants have the following prerequisites:

1. They are used only for the water-dissolved fraction of the substance. Calculation of partitioning between water and sludge phases is calculated prior to application of the rate constant.

2. Sufficiently valid data from internationally standardised tests are preferred.

3. For some substances (e.g. certain detergents), higher biodegradation rates may be justified if this can be confirmed by experimental data.

For readily-biodegradable compounds, a rate constant of 1 hr-1 is used. When the chemical is readily but fails the 10-day window, a rate constant of 0.3 hr-1 is used. For the STP model, a rate constant of zero is applied for inherently biodegradable compounds, unless it fulfills specific criteria for the different inherent biodegradation tests (in that case, a rate constant of 0.1 hr-1 is used).

To degradation and transformation


Biodegradation in surface water

The rate of biodegradation in surface water is related to the structure of the chemical, microbial numbers, organic carbon content and temperature. Apart from chemical structure, these properties vary spatially and an accurate estimate of the rate of biodegradation is very difficult, even if laboratory or field data are available. The kinetics of biodegradation are assumed to be pseudo-first order. Rate constants are assigned to the results of the standard tests for use in environmental-fate models. These constants are based on a relatively limited number of empirical data.

It should be noted that the assigned degradation half-lives will only affect the predicted regional concentrations if the residence time of the chemical in that compartment is (much) larger than the assigned half-life (i.e. for inherently biodegradable substances usually only in the soil and sediment compartment).

For readily-biodegradable compounds, a half life of 15 days is used. When the chemical is readily but fails the 10-day window, a half life of 50 days is used. A half life of 150 days is applied for inherently biodegradable compounds.

To degradation and transformation

To water distribution model


Biodegradation in soil and sediment

The rate of biodegradation in soil and sediment is related to the structure of the chemical, microbial numbers, organic carbon content and temperature. Apart from chemical structure, these properties vary spatially and an accurate estimate of the rate of biodegradation is very difficult, even if laboratory or field data are available. The kinetics of biodegradation are assumed to be pseudo-first order.

Normally, specific information on biodegradability in sediment or soil is not available. Hence, rate constants for these compartments have to be estimated from the results of standardised tests. These constants are based on a relatively limited number of empirical data.

Since it is assumed that no degradation takes place in the bound phase, the rate constant for the bulk sediment or soil in principle, also depends on the sediment-water or soil-water partition coefficient of the chemical. However, for substances with a low solids-water partition coefficient (Kp), insufficient empirical data are presently available to assume any sort of dependence of the soil biodegradation half-life on Kp. Nevertheless, for substances with high Kp-values there is evidence that some sort of Kp-dependence exists. Therefore, degradation half-life classes for (bulk) soil, partly based on this sorption parameter, have been defined. The rate constants are given in Section III.4.2.6 of the documentation.

The extrapolation of biodegradation test results to rate constants for sediment is problematic, given the fact that sediment generally consists of a relatively thin oxic top layer and anoxic deeper layers. For the degradation in the anoxic layers a default rate constant of zero (infinite half-life) is assumed, unless specific information on degradation under anaerobic conditions is available (the defaults can be changed in the degradation defaults section). For the oxic zone, the same rate constants as those for soil are assumed.

To degradation and transformation

To soil distribution model


Partition coefficients

Transport and  transformation (fate) processes determine the distribution of a substance in the environment, or in organisms, and the changes of the substance in time. Since measured data on fate processes are not usually available for the various compartments, they must be extrapolated from the primary data of the input module. This sub-module estimates the air-aerosol, air-water and solids-water partitioning processes in the various compartments. Measured data or other, more specific, estimation routines should be used when available

Many estimation routines are based on the octanol-water partition coefficient. It should be noted that for surface-active compounds and inorganic compounds (e.g. metals and metal compounds), Kow may not be an accurate predictor for estimating partition coefficients or bioconcentration factors. For ionising chemicals, the pH dependence of Kow must be investigated.

Gas-aerosol partitioning

The fraction of the chemical associated with aerosol particles is estimated on the basis of the chemical's vapour pressure. In this equation the sub-cooled liquid vapour pressure should be used. This implies that for solid substances, vapour pressure needs to be corrected.

Estimation routine for the sub-cooled liquid vapour pressure

Estimation of the fraction associated with aerosols

Air-water partitioning

The transfer of a substance from the aqueous phase to the gas phase (e.g. stripping in the aeration tank of an STP, volatilisation from surface water) is estimated by means of its Henry's Law constant. If the value is not available in the input data set, the required Henry's Law constant and the K_air-water (also known as the 'dimensionless' Henry's Law constant) are estimated from the ratio of the vapour pressure and the water solubility.

Estimation routine for air-water partitioning

Solids-water partitioning

Besides volatilisation, adsorption to solid surfaces is the main partitioning process driving distribution in soil, surface waters and sediments. If no measured data are available for a specific adsorbing material, it is assumed that all adsorption can be related to the organic matter in the medium. A normalisation to the organic carbon fraction is common to reduce the variance of the sorption coefficients measured in different media. This yields a carbon-normalised partition coefficient (Koc). For organic, non-ionic substances, Koc can be estimated from Kow.

Estimation routine for Koc

The solids-water partition coefficient (Kp) in each compartment (soil, sediment, suspended matter, sewage sludge) is calculated by multiplying the Koc value with the fraction of organic carbon in the compartment (see Eq. 25-28). Furthermore, Kp is used to estimate the dimensionless total compartment-water partition coefficients (K_comp-water).


Sub-cooled liquid vapour pressure

The fraction of the chemical associated with aerosol particles can be estimated on the basis of the chemical's vapour pressure. In this equation, the sub-cooled liquid vapour pressure should be used. For solids, a correction is applied according to Mackay (1991):

(Eq. 21)

Input

VP	vapour pressure [Pa]

TEMP	environmental temperature [K]

TEMPmelt	melting point of substance [K]

Output

VPL	sub-cooled liquid vapour pressure [Pa]

Reference

Mackay, D. (1991). Multimedia environmental models. Lewis Publishers, Chelsea, MI.

To partition coefficients


Fraction of the chemical associated with aerosol

The fraction of the chemical associated with aerosol particles can be estimated on the basis of the chemical's vapour pressure according to Junge (1977). In this equation, the sub-cooled liquid vapour pressure should be used.

(Eq. 19)

Input

CONjunge	constant of Junge equation [Pa.m]

SURF_aer	surface area of aerosol particles [m2.m-3]

VP_L	sub-cooled liquid vapour pressure [Pa]

Output

Fass_aer	fraction of chemical associated with aerosol particles [-]

Reference

Junge, C.E. (1977). In: Fate of pollutants in the air and water environment. I.H. Suffet (ed), Wiley interscience, New York, 7-25.

To partition coefficients


Organic-carbon normalised partition coefficient
Organic carbon-normalised partition coefficient

If no measured data are available for a specific adsorbing material, it is assumed that all adsorption can be related to the organic matter in the medium. A normalisation to the organic carbon fraction is common to reduce the variance of the sorption coefficients measured in different media. This yields a organic carbon-normalised partition coefficient (Koc). If no Koc-value is available from the data set, it may be estimated from the octanol-water partition coefficient (Kow).

Several models have been developed for different classes of chemicals. Most relationships are based on Kow, since hydrophobic interactions are the most dominant type of interactions between non-polar organic chemicals and the soil organic carbon. Chapter 4 of the TGD discusses these estimation routines in more detail, and proposes the following equation as a general default for non-polar, organic compounds (Sabljic et al., 1995). The equation given for the class 'predominantly hydrophobics' is implemented in EUSES. For specific groups of substances, other QSARs are given in the TGD.

The QSAR was derived from a range of log Kow values from 1 -7.5.

(eq. 24)

Input

Kow	octanol-water partition coefficient [-]

Output

Koc	organic carbon-water partition coefficient [m3.kg-1]

Reference

Sabljic, A., H. Güsten, H. Verhaar and J. Hermens (1995). QSAR modelling of soil sorption. Improvements and systematics of log Koc vs. log Kow correlations. Chemosphere 31, 4489-4514.

To partition coefficients


Air-water partitioning

The transfer of substances from the aqueous phase to the gas is estimated by means of its Henry's Law constant. If the value is not available in the input data set, the required Henry's Law constant and K_air-water  (also known as the 'dimensionless' Henry's Law constant) can be estimated from the ratio of the vapour pressure to the water solubility:

(Eq. 22)

(Eq. 23)

Input

VP	vapour pressure [Pa]

MOLW	molecular weight [kg.mol-1]

SOL	water solubility [kg.m-3]

R	gas constant [Pa.m3.mol-1.K-1]

TEMP	temperature at air-water interface [K]

Output

HENRY	Henry's law constant [Pa.m3.mol-1]

K_air-water	air-water partition coefficient [-]

To partition coefficients


Total compartment-water partition coefficients

Each compartment is described as consisting of three phases: solids, water and air (only relevant in soil). Kp describes the partitioning between solids and water in a compartment, since Kp is expressed as the concentration of the chemical adsorbed to solids divided by the concentration of the chemical dissolved in pore water. The dimensionless form of Kp, or the total compartment-water partition coefficient (K_comp-water), describes the ratio between the total concentration in the compartment and the pore-water concentration. This parameter is used extensively in the fate models of EUSES and is derived from the definition of the compartments in three phases (see Eq. 29-31).

To partition coefficients


Environmental distribution

The environmental distribution module contains all models necessary to estimate the distribution of a substance at the local and regional spatial scales. Results of this module are concentrations in the environmental compartments: surface water, sediment, soil, air, groundwater, sewage treatment plant. These results are used as PECs in risk characterisation and to estimate indirect human exposure and secondary poisoning of birds and mammals.

This module contains the following sub modules:

1. Partition coefficients

2. Degradation and transformation rates

3. Sewage treatment

4. Regional distribution models

5. Local distribution models


Regional and continental distribution
Regional and continental environmental distribution

Distribution in the environment at regional and continental spatial scales is calculated if local exposure assessment in the direct vicinity of point sources does not suffice. This is the case if exposure results from multiple point sources, or from non-point sources. Regional and continental assessments are based on year-averaged emissions to air, water, and soil. The regional and continental environmental distribution module calculates PECs for the compartments air, surface water, sediment, natural soil, agricultural soil, and industrial soil, at the regional and continental spatial scales.

In its default settings, the regional/continental distribution module represents a typical densely populated area (EU-region = regional scale), located in the margin of Western Europe (sum of EU Member States = continental scale).

The model SimpleBox is implemented for calculating the regional and continental PECs. SimpleBox is a multi-media environmental fate model of the so-called Mackay type. SimpleBox makes use of nesting: a regional model is nested within a continental model. This is done to account for the phenomenon that emissions at the regional scale affect concentrations at the continental scale, and vice versa.

General information on environmental distribution


Mackay model

Multi-media environmental fate model, or multi-media box model are often referred to as Mackay models, after one of the early developers of this kind of model. In this sort of model, different environmental media (air, water, sediment, soil) are modelled as homogeneous, well-mixed compartments or boxes. Inter-media transport and transformation are represented by simple, first-order processes.

The Mackay-type models can produce steady-state or time-dependent concentrations. The most commonly used (also applied in EUSES) is the steady-state or level III calculation mode. In the steady-state mode, all model settings, including the emissions, are kept constant in time. The calculated concentrations represent the steady state that has developed (or will develop) a considerable period of time after the emission has started. The time required to develop a steady state depends on the properties of the chemical, notably the rate of degradation in the environment.

The SimpleBox model is of the Mackay type.

Literature

C.E. Cowan et al. (eds.).  The multi-media fate model: a vital tool for predicting the fate of chemicals.  SETAC Press, Pensacola FL (1995).

D. Mackay.  Multimedia fate models, the fugacity approach.  Lewis Publishers (1991).

General information on regional and continental distribution


SimpleBox references
SimpleBox

D. van de Meent.  SimpleBox: a generic multi-media fate evaluation model.  Bilthoven, National Institute of Public Health and the Environment (RIVM), Report no. 672720 001 (1993).

L.J. Brandes, H.A. den Hollander, and D. van de Meent.  SimpleBox 2.0: a nested multi-media fate model for evaluating the environmental fate of chemicals.  Bilthoven, National Institute of Public Health and the Environment (RIVM), Report no. 719101 029 (1996).


Local distribution
Local environmental distribution

Distribution on the local scale is assessed in the vicinity of point sources. The figure below shows the relationship between the local emission routes and the subsequent distribution processes modelled for the different environmental compartments. Each application of the substance and each stage of the life cycle are assumed to occur at different point sources. Therefore, in principle, a local assessment has to be performed for each relevant use pattern and each relevant life-cycle step.

A generic standard environment is defined to allow for a risk assessment on the European level. As it is impossible to characterise an 'average European environment', default parameter values are chosen which reflect typical, or reasonable worst-case, settings. Dedicated modelling approaches are used to calculate the concentrations in air, surface water and soil. The sediment and groundwater concentrations are estimated from the surface water and soil concentration respectively.

Concentration in the local standard environment are used to calculate local PECs for the environmental endpoints. Furthermore, longer-term environmental PECs are calculated to assess secondary poisoning for predating birds/mammals and indirect exposure for humans.

General information on environmental distribution


Calculation of local PECs

As local PEC, the concentrations from the local distribution models are taken, adding the concentrations from the regional model as background level.

The following PECs are used for direct exposure of endpoints:

PEC in surface water during emission episode (aquatic ecosystem)

PEC in agricultural soil, averaged over 30 days (terrestrial ecosystem)

PEC in sediment during emission episode (sediment ecosystem)

PEC in effluent* of STP (micro-organisms in STP)

* For the micro-organisms, the influent is taken when intermittent release is identified. Furthermore, for this endpoint there is no regional background level.

The following PECs are used for secondary poisoning and indirect exposure:

PEC in surface water, annual average (uptake by fish)

PEC in grassland, averaged over 180 days (intake by cattle)

PEC in porewater of grassland averaged over 180 days (uptake by grass)

PEC in porewater of agricultural soil, averaged over 180 days (uptake by food crops)

PEC in air, annual average (inhalation for human and cattle)

PEC in groundwater below agric. soil (preparation of drinking water)

General information on environmental distribution


Sewage treatment plant

Across the European Union, taken as a whole, approximately 70% of the municipal wastewater volume (domestic and industrial loads) is treated in a biological wastewater treatment plant (TGD). Nevertheless, the situation is evolving. The situation with respect to wastewater treatment at industrial plants is less clear. It may be assumed that many of the larger industrial plants are either connected to a municipal wastewater treatment plant or have treatment facilities on site. In many cases, these treatment plants are not biological treatment plants but physico-chemical treatment plants.

In EUSES, the above situation is taken into account as follows:

1. On a local scale, it is assumed that wastewater will pass through a STP before being discharged into the environment. For the largest local PEC in surface water, additionally, a concentration assuming no sewage treatment is calculated. This value should be determined in addition to the normal PEC, which assumes sewage treatment, to flag for possible local problems (this PEC/PNEC ratio will not normally be used in risk characterisation).

2. On a regional and continental scale, it is assumed that 70% of the wastewater is treated in a biological STP and the remaining 30% released directly into surface waters.

The degree of removal in a wastewater treatment plant is determined by processes substance may undergo such as biodegradation, adsorption onto sludge, removal due to sludge withdrawal, volatilisation and the operating conditions of the plant. If only base-set information of the chemical is available the relative emission/removal can be estimated on the basis  of log Kow (Koc or more specific partition coefficients can also be used), Henry's Law constant and the results of biodegradation tests as input parameters. However, it should be remembered that the distribution behaviour of transformation products is not considered in this approach. The relative fate in the STP may be slightly different on each spatial scale because of differences in the number of inhabitants feeding the STP.

The fate of a chemical in a communal sewage treatment plant is modelled by means of a non-equilibrium, steady-state box model, known as SimpleTreat. In EUSES a revised version of this model is employed, SimpleTreat 3.0 having a greater flexibility. The revised model is suitable for a wide variety of wastewater scenarios in the EU. The main features are:

1. Operation without a primary settler is optional (specified on the local emission screen, for each stage of the life cycle separately; regional and continental calculations are always performed with primary settler);

2. The activated sludge technique consists of an activated sludge tank and a solids-liquid separator. Any realistic BOD loading of the activated sludge tank, expressed as the sludge loading rate, is allowed. The sludge retention time and the hydraulic retention time are dependent on this parameter;

3. Although the result of a standardised biodegradability test is often of the yes or no-type, any first-order degradation-rate constant for the aqueous phase in the environment can be assigned. Also Monod kinetics can be simulated if the maximum growth rate and the half saturation constant are specified.

Input parameters refer to the following items:

1. chemical loading of the STP (emission to wastewater) and data of raw sewage;

2. size of the plant specified by the number of inhabitants feeding one STP (this parameter should be distinguished from number of inhabitants of region and in the EU);

3. mode of operation of the plant, specified by the sludge loading rate, the mode of aeration which is surface aeration or bubble aeration and the absence/presence of primary sedimentation;

4. environmental conditions such as temperature and windspeed.

Local distribution models

General information on environmental distribution


Background information SimpleTreat

SimpleTreat

J.Struijs, J.Stoltenkamp & D.van de Meent, A Spreadsheet-Based Box Model to Predict the Fate of Xenobiotics in a Municipal Wastewater Treatment Plant,

Wat. Res. Vol 25, pp. 891-900, 1991.

SimpleTreat 3.0

J.Struijs, SimpleTreat 3.0: A Model to Predict the Distribution and Elimination of Chemicals By Sewage Treatment Plants, RIVM-report no. 719101025, January 1996.

J. Struijs

Laboratory for Ecotoxicology,

National Institute for Public Health and the Environment,

PO Box 1,

3720 BA Bilthoven,

The Netherlands,

Tel: +31 (0)30 274 2001

Fax: +31 (0)30 274 4439

e-mail: j.struijs@rivm.nl


Raw sewage

Raw sewage is thought to consist of water and certain amounts of suspended solids and O2 binding material (BOD). The Sewage flow is the volume of raw sewage per capita entering the wastewater treatment plant per day. The default value is 200 L per inhabitant per day. The mass of O2 binding material per person per day (default value: 54 g O2 per inhabitant per day), the mass of Dry weight solids produced per person per day (default value: 0.09 kg dwt per inhabitant per day) and the Sewage flow specify the raw sewage. The density solids in raw sewage is the mass per litre dry weight of solids - default value is 1,500 kg per litre dry weight solids. The organic carbon fraction of solids of raw sewage has a default value of 0.3 (this value can be changed in the default section for characteristics of compartments).

The modelled chemical is assumed to occur homogeneously in raw sewage where there is equilibrium between the aqueous and the solid phase. The equilibrium partitioning is derived from the above mentioned parameters and the properties of the compound. The overall concentration in raw sewage slurry is derived from the chemical loading of the STP (emission) and the sewage flow.

Sewage treatment, general information


Primary settler of STP

The depth of the primary settler has a default value of 4 m. Area and volume are proportional to number of inhabitants feeding one STP. Also the hydraulic retention time of primary settler has a fixed default value (2 hr). Multiplying the latter by the sewage flow gives the volume of the primary settler per person. Dividing this volume by the depth of primary settler results in the area of the primary settler per person. The density of suspended and settled solids in primary settler has the same default value as in raw sewage. It is assumed that in the primary settler 2/3 of the solids in raw sewage is withdrawn. As a consequence, in the primary settler the steady state suspended solids concentration is one third of that in raw sewage. The slurry flowing out of the primary settler into the aeration tank is called settled sewage.

It is strongly recommended to accept the given default values!

Sewage treatment, general information


Activated sludge tank of STP

The depth of the aeration tank has a fixed default value of 3 m. Other fixed parameters have the following default values:

- Density solids of activated sludge tank = 1.3 kg per L dry weight.

- Concentration solids of activated sludge tank = 4 g dry weight per L.

- Steady state O2 concentration in activated sludge = 2 mg O2 per L.

- Aeration rate of bubble aeration = 1.31e-5 m3 per second per inhabitant.

It is strongly recommended to accept the given default values!

The sludge loading rate describes the BOD loading of the aerator and typically is an input parameter. The default value is 0.15 kg BOD per kgdw per day. The concentration of O2 binding material in raw sewage is the ratio of the mass of O2 binding material per person per day and the sewage flow. If the treatment plant is equipped with a primary sedimentation tank only a fraction 23/36 of the O2 binding material will enter the aeration tank. The concentration in this settled sewage is reduced accordingly.

The volume of the aeration tank is a derived parameter. It is obtained by first evaluating the product of the sewage flow and the concentration of O2 binding material in raw or settled sewage flowing into the aerator. Secondly, this product has to be devided by the sludge loading rate and the concentration solids of activated sludge tank. Dividing this volume by the depth of aeration tank gives the area of the aerator. The volume of the aerator divided by the sewage flow yields the hydraulic retention time. The BOD loading of the aerator is often referred to as the sludge retention time or sludge age. In SimpleTreat 3.0 this parameter is dependent on the sludge loading rate.

Sewage treatment, general information


Solids-liquid separator of STP

The operation of this tank is entirely described by fixed parameters with the following defaults:

Depth of solids-liquid separator = 3 m;

Density suspended and settled solids in solids-liquid separator = 1.3 kg/L dwt;

Concentration solids in effluent = 30 mg dwt/L;

Hydraulic retention time of solids-liquid separator 6 hr.

It is strongly recommended to accept the given default values!

Sewage treatment, general information


Number of inhabitants feeding one STP

This parameter largely determines the size of an STP and is the scaling factor for the area of the different tanks. With fixed depths the volumes of these tanks are proportional to the number of inhabitants feeding one STP. The default value is 10000, being different from the number of inhabitants of the regional and continental spatial scales for which the default values are 20 and 370 million people, respectively.

In EUSES, the STP at the regional and continental scales is calculated as one, extremely large, STP fed by the total number of inhabitants of that system. Since the size of the plant depends upon the number of inhabitants, a slight difference in relative fate may occur between the different spatial scales.


BOD loading of the aeration tank of the STP
BOD loading of the aeration tank

The operation of the activated sludge reactor is largely specified by the sludge loading rate and the mode of aeration. The BOD loading of an activated sludge tank is expressed as sludge loading rate. This input parameter is in units of kg BOD per kg dry weight per day and is related to the sludge retention time (sludge age) and the hydraulic Retention time according to the following table.

Sludge loading rate	Sludge retention time	Hydraulic retention time	Nitrification possible

(kgBOD   kgdw-1  d-1)	(d)	(hr)	(yes/no)

0.04 (low)	37	26.4	yes

0.06 (low)	24.1	17.6	yes

0.1 (low)	14.1	10.6	yes

0.15 (medium)	9.2	7.1	yes	default

0.2 (high)	6.8	5.3	no

0.3 (high)	4.5	3.5	no

0.6 (high)	2.2	1.8	no

In Appendix II of Chapter 3 of the TGD, tables are given for the fate of chemicals for varying physico-chemical properties. These table are based upon model calculations carried out with an older version of SimpleTreat. For the calculation a BOD loading scenario was chosen corresponding to a sludge loading rate equal to 0.2 kg BOD per kg dry weight per day. Although this older version of SimpleTreat was modified in view of the correction for the gas phase resistance, the operation parameters deviate from SimpleTreat 3.0 as the hydraulic and sludge retention time are 10.4 hr and 7.3 d, respectively. In SimpleTreat 3.0 with 0.2 kg BOD per kg dry weight per day, these parameters would have been respectively 5.2 hr and 6.8 d. These values differ significantly, however because for other parameters different defaults have been taken, the relative fate predictions are almost similar.


Mode of aeration of STP
Mode of aeration

The mode of aeration is either surface aeration or bubble aeration (or diffuse aeration). Default is surface aeration. In SimpleTreat 3.0, a gas phase resistance correction was inserted in the equation for the first order transfer rate constant for surface aeration. This correction was ignored in SimpleTreat but this has been shown satisfactory if Henrys law constant exceeds 250 Pa.m3.mol-1. Process formulation as to elimination due to surface aeration in SimpleTreat 3.0 is also valid for volatile chemicals.

If bubble aeration is chosen the default value for aeration rate of bubble aeration is 1.31e-5 m3 per second per inhabitant.

In SimpleTreat 3.0, surface volatilisation, described by the so-called two layer resistance model  (Liss & Slater, 1974), is taken as the minimum transfer rate constant to which the first order stripping constant - either for surface or for bubble aeration - is added.

Reference

Liss, P.S. and P.G. Slater (1974). Flux of gases across the air/sea interface. Nature 247, 181-184.


Absence/Presence of primary sedimentation

In the Figure below two scenarios are schematically represented: sewage treatment with and without primary sedimentation. In the model SimpleTreat 3.0 the chemical fate in these systems is obtained from non-equilibrium steady state box model calculations.


Monod kinetics in STP

Non-linear kinetics for biodegradation in the Activated sludge tank is simulated by calculating the concentration of the chemical in the water flowing out of the aeration tank (Cout). Applying Monod kinetics to the activated sludge technique, according to Birch (1991), shows that Cout is only determined by the sludge retention time and the Monod parameters maximum growth rate, max, and the half saturation constant, Ks, provided that the sludge retention time is longer than the so-called critical sludge retention time, SRTcrit. This SRTcrit (Birch, 1991) is evaluated from the Monod constants and the concentration of the degradable chemical in the wastewater flowing into the STP (Cin). From the concentrations Cout and Cin and the hydraulic retention time a first order biodegradation rate constant is calculated from a simple mass balance equation, taking only advective transport (into and out of the reactor) and first order degradation into account. This rate constant is equal to the overall elimination rate constant if sorption and volatilisation can be completely neglected. This first order biodegradation rate constant is used in the mass balance computations.

Reference

Birch, R.R. (1991). Prediction of the fate of detergent chemicals during sewage treatment. J. Chem. Tech. Biotechnol. 50, 411-422.


Environmental conditions for STP

The temperature in air is used in air-water partioning calculations. The water temperature is used for deriving dissociation and degradation constants. The default setting is that there is no temperature correction. This means that the factor by which the first-order biodegradation constant has to be multiplied equals FT = 1. If temperature correction is desired, this factor is calculated according to:

with Tref is 20 degrees C.


Defaults for sewage treatment

The degree of removal in a wastewater treatment plant is largely determined by the physico-chemical and biological properties of the substance (solids-water partition coefficients, air-water partition coefficients and biodegradability) and the operating conditions of the plant. The distribution and elimination of a chemical by a communal sewage treatment plant can be modelled by means of a non-equilibrium steady state box model, known as SimpleTreat. In EUSES a revised version of this model is employed, SimpleTreat 3.0 which has a greater flexibility. The model is suitable for a wide variety of wastewater scenarios occurring in the EU. The main features are:

1. Operation without a primary settler is optional.

2.  The activated sludge technique is simulated by an activated sludge tank connected in series with a solids-liquid separator. Any realistic BOD loading of the activated sludge, expressed as the sludge loading rate, is allowed. The sludge retention time and the hydraulic retention time are dependent on this parameter.

3. Although the result of a standardised biodegradability test is often of the yes or no-type, a value for the first-order degradation-rate constant in the aqueous phase of activated sludge can be chosen. Also Monod kinetics can be simulated if the maximum growth rate and the half saturation constant are specified.

Input parameters refer to the following items:

1. chemical loading of the STP (emission) and data of raw sewage;

2. size of the plant specified by the number of inhabitants feeding one STP (this parameter should be distinguished from number of inhabitants of region and in the EU);

3. mode of operation of the plant, specified by the sludge loading rate, the mode of aeration which is surface aeration or bubble aeration and the absence/presence of primary sedimentation;

4. environmental conditions such as temperature and windspeed.


Intermittent release

Many substances are released to the environment from industrial sources as a result of batch, rather than continuous, processes. In extreme cases, substances may be emitted a few times a year only. Intermittent release needs to be defined, although rapporteurs will have to justify the use of this scenario on a case-by-case basis. Intermittent release can be defined as:

intermittent but only recurring infrequently, i.e. less than once per month and for no more than 24 hours.

This would correspond to a typical batch process required only for a short period of the year (releases to the environment may be of limited duration only). Thus, for the aquatic compartment, transport processes may ensure that the exposure of aquatic organisms is of short duration. For intermittent releases to the aquatic compartment a dedicated PNEC is used in the risk characterisation. When intermittent release is identified for a substance, this is not necessarily applicable to all releases during the life cycle.


Local distribution in air

The concentration in air is used as input for the calculation of the intake of substances through inhalation in the indirect exposure of humans. Deposition fluxes are used as input for the soil and groundwater model. Therefore, both deposition flux and concentration are calculated as annual average values. The air compartment receives its input from direct emission to air, and volatilisation from the sewage treatment plant (STP).

Model

A standardised exposure assessment is carried out making a number of explicit assumptions and using a number of fixed model settings and assumptions. The Gaussian plume model OPS is used with a number of standard parameters in order to describe a relationship between the basic characteristics of substances (vapour pressure and Henry's Law constant) and the concentration in near a point source. The deposition flux of gaseous and aerosol-bound chemicals is estimated analogously.

At this small spatial scale physical mixing processes are the dominant fate processes. Therefore, a simple linear relationship between source strength and concentration or deposition can be assumed. The concentration on the regional scale is used as background concentration and therefore summed to the local concentration.

Both the emission from a point source and the emission from a STP are taken into account. The higher of the two concentrations is used as the PEC. For deposition, the contributions of both sources are summed.

Defaults for the air model

Scenario

The concentration in air at a distance of 100 meters from both point sources is estimated. This distance is chosen to represent the average distance between the emission source and the border of the industrial site. The deposition flux to soil is averaged over a circular area around the source, with a radius of 1000 m to represent the local agricultural area.

From the background document:

Section II.4.5.1

Section III.4.5.1 an Equations 59-63

Local distribution models


OPS

Operational atmospheric transport model for Priority Substances (OPS). An air-distribution model, used in a simplified manner in EUSES.

Reference

Van Jaarsveld, J.A. (1990). An operational atmospheric transport model for Priority Substances; specifications and instructions for use. Bilthoven, National Institute of Public Health and the Environment (RIVM), Report No. 222501002.


OPS model settings

The following assumptions/model settings are used in the OPS model:

1. Realistic average atmospheric conditions are used, obtained from a 10-year dataset of weather conditions for the Netherlands.

2. Transport of vaporised and aerosol-bound chemicals is calculated separately. The partitioning between gas and aerosol is determined by the equation of Junge.

3. The atmospheric reaction rate is fixed at a value of 5% per hour. On the spatial scale that is regarded, however, atmospheric reactions do not play any role in the removal of the substance (even at very high reaction rates).

4. Losses due to deposition are neglected for estimation of the concentration and deposition fluxes at this short distance from the source.

5. Assumed source characteristics are: source height: 10 metres, representing the height of buildings in which production, processing or use take place; heat content of emitted gases: 0; this assumes there is no extra plume rise caused by excess heat of vapours compared to the outdoor temperature; source area: 0 meter; representing an ideal point source which is obviously not always correct but which is an acceptable choice.

6. Calculated concentrations are long-term averages.

7. Deposition velocities are used for three different categories: dry deposition of gas/vapour: estimated at 0.01 cm/s; wet deposition of gas/vapour: determined with the OPS model; dry and wet deposition of aerosol particles; determined within the OPS model using an average particle-size distribution.


Local distribution in surface water and sediment

The effluent of the sewage treatment plant (STP) is diluted in the surface water. For the calculations, the following assumptions are made:

1. Complete mixing of the effluent in the surface water is assumed as a representative exposure situation for the aquatic ecosystem.

2. For the initial local assessments, volatilisation, degradation and sedimentation are ignored, because of the short distance between the point of effluent discharge and the exposure location.

Model

The distance from the point of discharge where complete mixing may be assumed will vary between different locations. A fixed dilution factor is applied to the effluent concentration. Dilution factors are dependent on flow rates and the industry-specific discharge flow. Owing to the different seasonal, climatic and geographical conditions in the Member States, these dilution factors may vary over wide ranges. A default dilution factor of 10 is used if no specific data are available. If a more site-specific assessment is appropriate, the actual dilution factor after complete mixing can be calculated from the flow rate of the river and the effluent discharge rate of the STP. This approach should be used for rivers only and not for estuaries or lakes.

Defaults for the surface water model

PEC exceeding solubility

For some substances is possible that PECs may be calculated in water which are in excess of the water solubility. These results need to be interpreted carefully on a case-by-case basis. The concentration in surface water will not be corrected, but the results flagged. The PEC has to be interpreted on the basis of on the effects found in the aquatic toxicity tests. This is especially the case for poorly water-soluble compounds like metals and organometallo compounds.

Sediment

The PEC in sediment is compared to the PNEC for sediment-dwelling organisms. The concentration in freshly deposited sediment is taken as the PEC for sediment and the properties of suspended matter are therefore used. The concentration in bulk sediment is derived from the corresponding water-body concentration, assuming a thermodynamic partition equilibrium.

From the background document:

Section II.4.5.2

Section III.4.5.2, Section III.4.5.3 and Equations 64-69

Local distribution models


Local distribution in soil and groundwater

Exposure assessment for the soil compartment is important with respect to exposure of terrestrial organisms. Furthermore, crops for human consumption are grown on agricultural soils and cattle, producing meat and milk, graze on grasslands. These two soil types are distinguished in the model and differ in amount of applied sludge and mixing depth.

The soil compartment receives its input through application of sewage sludge in agriculture, and through dry and wet deposition from the atmosphere. Sludge application is treated as a single event once a year, atmospheric deposition is assumed to be a continuous flux throughout the year. It should be noted that the deposition flux is averaged over a year.

Model

A simple, one-compartment soil model is used. The top layer of the soil compartment is described, with influx of airborne deposition and removal from the box by degradation, volatilisation and leaching. The overall removal-rate constant is given by the sum of the rate constants for these processes.

Defaults for the soil model

Scenario

Accumulation of a substance may occur when sludge is applied over consecutive years. As a reasonable worst-case scenario, sludge is assumed to be applied for 10 consecutive years. To provide an indication of the potential persistence of the substance, the percentage of the steady-state situation is calculated. Different averaging times are used for the different end-points: for the ecosystem a period of 30 days after sludge application is used. In order to determine biomagnification effects and indirect exposure to man, an extended period of 180 days is used.

Groundwater

The concentration in groundwater is calculated for indirect exposure of humans through drinking water. The concentration in the pore water of agricultural soil is taken as an indication of potential groundwater levels. It should be noted that this is a worst-case assumption, neglecting transformation and dilution in deeper soil layers.

From the background document:

Section II.4.5.3

Section III.4.5.4, III.4.5.5 and Equations 70-85

Local distribution models


Volatilisation from soil

The diffusive transfer from soil to air is estimated using the classical two-film resistance model. The soil side of the interface is treated as a pair of parallel resistances (air phase and water phase of soil) (Mackay et al., 1992). The rate constant for volatilisation from soil is given by:

(Eq. 70)

Input

kasl _air	partial mass-transfer coeff. at air side of air-soil interface [m.d-1]

kasl_soilair	partial mass-transfer coeff. at soil-air side of air-soil int. [m.d-1]

kasl_soilwater	partial mass-transfer. coeff. at soil-water side of air-soil int. [m.d-1]

K_air-water	air-water partition coefficient [m3.m-3]

K_soil-water	soil-water partition coefficient [m3.m-3]

DEPTH	mixing depth of soil [m]

Output

k_volat	rate constant for volatilisation from soil [d-1]

Reference

Mackay, D., S. Paterson and W.Y. Shiu, (1992). Generic models for evaluating the regional fate of chemicals; Chemosphere 24, (6), 695-717.

Local soil and groundwater distribution


Leaching from top-soil layer

A first-order rate constant for leaching can be calculated from the amount of rain flushing the liquid phase of the soil compartment.

(Eq. 71)

Input

Finf_soil	fraction of rainwater that infiltrates into soil [-]

RAINRATE	rate of wet precipitation [m.d-1]

K_soil-water	soil-water partition coefficient [m3.m-3]

DEPTH	mixing depth of soil [m]

Output

k_leach	rate constant for leaching from soil	[d-1]

To local soil and groundwater distribution


Exposure of humans and predators

In the exposure module, exposure levels for humans and predating birds and mammals are estimated.

The assessment of secondary poisoning of birds and mammals considers exposure through fish and earthworms.

For humans, three assessments can be made:

1. Indirect exposure through the environment

2. Exposure through consumer products

3. Exposure at the workplace

For estimating exposure of humans and predators through the environment, bioconcentration factors are required.


Bioconcentration factors

For exposure of humans and predators through the environment, an estimate of the concentration in their food must be made. This is done by multiplying the concentration in the environment (from the distribution module) with the measured or estimated BCF or BAF. Since measured data on bioconcentration are usually not available, EUSES contains QSARs for the following organisms:

Fish (both for humans and predators)

Earthworms (for predators only)

Plants (root crops, leaf crops and grass; for human exposure only)

Cattle (meat and milk for human exposure only)

The estimation of most BCFs or BAFs is highly dependent on Kow. These estimations are therefore only valid for organic, non-ionised or non-dissociating chemicals. Other substances can of course be evaluated if experimental BCFs are known. The use of static BCFs or BAFs implies that these factors describe a steady-state situation in which the exposure period is assumed long enough to achieve a steady state. It should be noted that reliable (and relevant) experimental bioconcentration factors are always preferable to estimated factors.

It should be noted that most QSARs are log-linear regressions of BCF against Kow. They were derived for a certain Kow range (the range of the training set) and, therefore, are only valid within this range. In applying these QSARs, EUSES will use the maximum or minimum allowable Kow value when this range is exceeded.


Secondary poisoning

Secondary poisoning means the toxic effects in the higher members of the food chain resulting from ingestion of  organisms at the different trophic levels that contain accumulated substances.

In EUSES, an estimation is made of whether the PEC in water or soil can lead to deleterious effects in higher organisms feeding on fish or earthworms. If secondary poisoning is to be avoided, the concentration of chemicals in food should be below the PNEC derived from the NOEC in effects assessment for birds and mammals.

Starting from the concentration in the environment, the resulting concentration in food of higher organisms is estimated. This exposure concentration is compared to the avian or mammalian toxicity of the chemical as an indication of possible effects on birds and mammals in the environment via the food chain. Two example food chains are considered:

1. Water to fish to fish-eating birds or mammals.

2. Soil to earthworm to worm-eating birds or mammals.

The concentrations in fish and earthworms are calculated from the concentration in the environment (surface water and agricultural soil) and the measured or estimated BCF for fish and BCF for worms. These two food chains are examples of secondary poisoning pathways. However, safe levels for fish-eating animals do not exclude the possibility of risks to other birds or mammals feeding on other aquatic organisms (e.g. mussels and worms). It is therefore emphasised that the proposed methodology merely gives an indication that secondary poisoning is a critical process in the aquatic risk characterisation of a chemical.

Scenario

It is difficult to justify whether the concentrations on the regional or local spatial scale are most appropriate for risk characterisation. Using the local PEC may lead to overestimation of the risk, as birds or mammals also forage from other sites than the area around the point of discharge. However, using regional concentrations may have the opposite effect, as there may be large areas in the region with higher concentrations. Foraging ranges can vary enormously among species, which makes it difficult to decide on the appropriate scale. A scenario is used where 50% of the diet is derived from the local environment and 50% from the regional environment. For local surface water, the annual average concentration is used. For the soil compartment, the concentration is averaged over a period of 180 days. Due to the lack of experience with this approach, the assessment is considered provisional.


Bioconcentration in fish

Fish living in contaminated surface water are able to take up appreciable amounts of (especially hydrophobic) substances through the gills or through their food. The concentration in fish may be orders of magnitude greater than the concentration in water. The bioconcentration factor in fish for non-ionic, organic compounds is found to be well correlated with the octanol-water partitioning coefficient (Kow), indicating that lipid or fat is the main dissolving medium. Many QSARs are available. Because these methods are based on several assumptions, such as a constant water concentration and no metabolism of the substance by the organism, the resulting values should be considered as a relative measure for the bioaccumulation potential of a substance. Furthermore, these methods may not have the same accuracy for different classes of chemicals.

For existing substances, experimentally derived BCFs may be available. For new substances, a BCF test is mandatory at level I. In most cases, experimentally determined BCF values are preferred.

Estimation of BCF for fish

To secondary poisoning

To indirect exposure of humans


BCF

BioConcentration Factor: ratio between the concentration in an organisms and the concentration in an environmental compartment. Bioconcentration is the net result of the uptake, distribution and elimination of a substance in an organism due to water-borne exposure.

See also BAF.


BAF

BioAccumulation Factor: ratio between concentration in (part of) organism and exposure level. Bioaccumulation is the net result of the uptake, distribution and elimination of a substance in an organism due uptake including all routes, i.e. air, water, soil and food.

See also BCF.


QSAR for bioconcentration in fish

The methods that estimate a BCF for fish from log Kow are widely used and, in general, the most reliable. For substances with a log Kow, from 1 to 6, the relation by Veith et al. (1979) is used, while for substances in the log Kow range between 6 and 10 a parabolic equation is applied (TGD).

It should be noted that due to experimental difficulties in determining BCF values for highly hydrophobic substances, the parabolic relationship has a higher degree of uncertainty than the linear one. Domain of physico-chemical properties: log Kow 1 to 10 (outside this range the minimum or maximum Kow is used), molecular weight less than 700 g/mol. For chemicals with a molecular weight of more than 700 g/mol, the BCF tends to decrease but in lack of experimental data, the QSAR can be used as an initial worst-case estimate.

Only uptake from the water phase is accounted for, uptake through food is ignored.

If log Kow 1-6 :

(Eq. 86)

If log Kow 6-10 :

(Eq. 87)

Input

Kow	octanol-water partition coefficient [m3.m-3]

Output

BCF_fish	bioconcentration factor for fish (wet weight) [m3.kg-1]

References

Veith, G.D., D.L. Defoe and B.V. Bergstedt (1979). Measuring and estimating the bioconcentration factor of chemicals in fish. J. Fish Board Can. 36, 1040-1048.

Estimation of BCF for fish

Secondary poisoning

Indirect exposure of humans


Bioconcentration in earthworms

The concentration in earthworms is thought to be proportional to the concentration in the pore water of soil. The hypothesis is that uptake through the solid phase contributes significantly to bioaccumulation for extremely hydrophobic substances only (log Kow > 5). The experimental data, analysed by Connell and Markwell (1990), are broadly consistent with the transfer of hydrophobic substances through a three-phase system, involving soil to pore water, and pore water to organism partitioning. This is thought to be a passive process and is principally dependent on the lipid content of the worm and the properties of the soil type. The worms are assumed to be in equilibrium with the concentration in soil.

No internationally accepted guidelines are available at the moment for deriving BCFs for earthworms. The BCF for earthworms is estimated using a QSAR.

To secondary poisoning


Bioconcentration in earthworms
QSAR for bioconcentration in earthworms

The BCF for worm is estimated using a QSAR from Connell and Markwell (1990). They derived an empirical equation for the worm-pore water partitioning through regression on experimental data for pesticides with a log Kow ranging from 1.0 to 6.5 (outside this range the minimum or maximum Kow is used). As data from experiments conducted under different conditions are included, it should be noted that the sources of variation in this study are substantial.

Only uptake from the water phase is accounted for, uptake through food is ignored. The worm-porewater partition coefficient is, in principle, valid for all soil types. BCF for worm is converted to the default soil properties.

(Eq. 89)

(Eq. 90)

Input

Kow	octanol-water partition coefficient [m3.m-3]

RHO_soil	wet bulk density of soil [kg.m-3]

K_soil-water	soil-water partition coefficient [m3.m-3]

Output

K_worm-porew	worm-pore water partition coefficient [m3.kg-1]

BCF_worm	bioconcentration factor for earthworms (wet weight soil and worm) [kg.kg-1]

Reference

Connell, D.W. and R.D. Markwell (1990). Bioaccumulation in the soil to earthworm system. Chemosphere 20, 91-100.

Estimation of BCF for earthworms

Secondary poisoning


Human exposure through the environment

Indirect exposure of humans via the environment may occur by consumption of food and drinking water, inhalation of air and ingestion of soil. Exposure via soil ingestion and dermal contact is not addressed because these represent significant exposure routes for specific situations of soil pollution only, and are therefore not appropriate for a generic exposure scenario. The other pathways are included in EUSES. Assessment of indirect exposure via the environment comprises the following steps:

1. Assessing the concentrations in intake media (food, drinking water, air). The concentration of a substance in food is estimated from its concentration in water, soil and air (from the distribution module) and its bioconcentration or bioaccumulation behaviour. The exposure assessment in EUSES includes seven pathways: drinking water, fish (from surface water), root and leaf crops (from agricultural soil), meat and milk (from cattle grazing on grassland), and inhalation of air.

2. Assessing the intake rate of each medium (using a standard consumption pattern).

3. Combining the concentrations in the media with the intake of each medium, using a standard exposure scenario. The total daily intake of humans is estimated by multiplying these concentrations by the daily intake rate of each medium and summing the contribution of each medium. Each of these intake media is retrieved exclusively from within the contaminated system.

The calculation methods described are simple methods for predicting indirect exposure. Owing to the considerable uncertainties accompanying the methodology, it serves primarily for screening purposes.


Human exposure scenario

Human behaviour shows an appreciable amount of variation among the different EU countries, but within countries, too, there may be large deviations among individuals. As a consequence, indirect exposure will vary greatly among the population we seek to protect. The choice for an exposure scenario will have a major influence on the result of the assessment. This choice will always be a compromise, as a scientifically sound solution is extremely difficult to obtain.

Indirect exposure is principally assessed on two spatial scales: locally near a point source of the substance, and regionally using averaged concentrations over a larger area. In the local assessment all food products are derived from the vicinity of one point source, while in the regional assessment all food products are taken from the regional model environment. Clearly, the local situation represents a worst case. People do not consume 100% of their food products from the immediate vicinity of a point source. Therefore, the local assessment represents a situation which does not exist in reality. However, one or two routes usually dominate the total exposure and local exposure via these routes may not be unrealistic.

In contrast, the regional assessment represents a highly averaged exposure situation which cannot ensure protection of individuals who consume food products from the vicinity of point sources. A regional assessment indicates potential average exposure of the inhabitants of the region. In the light of the above limitations, it is clear that a generic indirect-exposure assessment, as required in this framework, can only be used to indicate potential problems. The assessment should be seen as a helpful tool for decision-making and not as a prediction of human exposure actually occurring at some place or time.

Standard EU consumption pattern

Indirect exposure of humans


Standard EU consumption pattern

For an indirect-exposure assessment at EU level, a standard consumption pattern is defined. To account for the fact that intake rates vary among countries, for each food product the highest country-average consumption rate from the member states will be used. This will of course lead to a total food basket which is an unrealistic, worst-case scenario. In practice, however, as one or two routes usually dominate indirect exposure, the fact that worst-case intake also occurs via other routes is less important. This makes this scenario appropriate as an initial approximation to indicate possible concern. It should be noted that extreme consumers of certain food products are not accounted for, as this would lead to more severe worst-case local assessments.

The intake rates are presented in Section III.5.2.5 of the background documentation.

To indirect exposure of humans


Human exposure via inhalation of air

For volatile compounds, this exposure route can contribute significantly to the total exposure. The concentration in the intake medium (air local and regional) is calculated using the distribution models. The intake scenario chosen has important consequences for exposure via this route; the human individual that is modelled is exposed continuously and chronically to the annual average concentration in air. Exposure through inhalation is summed to exposure through oral routes, accounting for the generally lower bioavailability for inhalation.

Indirect exposure of humans


Purification of drinking water

Drinking water is prepared from surface water or groundwater. Groundwater can be contaminated through leaching from the soil surface, while surface water can be polluted through direct or indirect emission. Hrubec and Toet (1992) evaluated the predictability of the fate of organic chemicals during drinking-water treatment. One of their conclusions was that groundwater treatment, which is generally not intended to remove organic chemicals, can be ignored. The accuracy of the predicted removal efficiencies for surface-water treatment is rather low. This is due mainly to uncertainties in the most effective treatment processes (such as activated carbon filtration).

Purification is modelled as described by Hrubec and Toet (1992). The drinking-water module assumes complete removal of suspended particles from surface water and groundwater. Dependent on the type of storage, two different water-treatment systems for surface water can be distinguished: system 1 includes storage in open reservoirs, while system 2 includes dune recharge. Removal of the dissolved fraction of a xenobiotic from the surface water is modelled by means of purification factors. For the choice between the two systems and the choice between surface water and groundwater, a worst-case approach will be followed.

From the background document:

Section II.5.2.3

Section III.5.2.4 and Equations 114-115

Reference

Hrubec, J. and C. Toet (1992). Predictability of the removal of organic compounds by drinking water treatment. Bilthoven, National Institute of Public Health and the Environment (RIVM), Report No. 714301007.

Indirect exposure of humans


Biotransfer from soil and air to plants

Plant products form a major fraction of the food products consumed by humans and cattle. Contamination of plants may therefore have a significant influence on human exposure. In endeavouring to predict concentrations in plant tissues, several important conceptual problems will immediately be encountered:

1. There are hundreds of different plant species forming the heterogeneous group of food crops. Furthermore, varietal differences can also account for large differences.

2. Different plant tissues are consumed (roots, tubers, fruit, leaves).

3. Crops differ in contaminant exposure; many crops are grown in greenhouses, for instance.

4. Crops can be exposed through uptake from soil, but also through gas uptake and airborne deposition.

From the above it will be clear that a modelling approach can only roughly approximate concentrations in plants. In the calculations a distinction is made between roots and leaf crops. The exposure of plants includes uptake from soil as well as uptake from air. Uptake from soil is, in general, a passive process governed by the transpiration stream of the plant (in the case of accumulation in leaves) or physical sorption (in the case of roots). Uptake into the leaves from the gaseous phase can be viewed as a passive process, in which the leaf components (air, water, lipids) equilibrate with the air concentration. Kow and Kaw (the air-water partition coefficient) are used to assess the distribution between air and plant.

The modelling approach of Trapp and Matthies (1995) is used to estimate levels in leaves and roots. This approach integrates uptake from pore water and air (gas phase) into a one-compartment model. The sink term in the model is formed by diffusive transfer from leaf to air, elimination in the plant tissue and dilution by growth. The source term is formed by uptake and translocation from soil and gaseous uptake from air. Aerosol deposition is not considered in the model. Although this route may be important for some chemicals, it is not yet clear how this route can be satisfactorily quantified and incorporated into the model.

From the background document:

Section II.5.2.5

Section III.5.2.2 and Equations 93-106

Reference

Trapp, S. and M. Matthies (1995). Generic one-compartment model for uptake of organic chemicals by foliar vegetation. Environ. Sci. Technol. 29, 2333-2338.

Indirect exposure of humans

Default section plants


Biotransfer to meat and milk

Hydrophobic substances are known to accumulate in meat, and can be subsequently transferred to milk. Cattle can be exposed to substances in grass (or other feed), via adhering soil, drinking water, and through inhalation of air. BAFs can be defined as the steady-state concentration in meat or milk divided by the daily intake of the chemical (through air, grass, soil and drinking water).

Due to lack of measured data, a QSAR is implemented to estimate BAFs for the meat and milk of cows. Even though the theoretical background is limited, these factors provide a useful tool in risk assessment. The uncertainties in the estimated BAFs are considerable. No distinction is made between different milk products like cheese or yoghurt. For all dairy products, the concentration in milk is used.

Estimation routine for meat and milk

Scenario

The cows are continuously grazing on grassland on the local scale, on agricultural soil on the regional scale, thereby also taking in adhering soil, inhaling air and drinking water (for the concentration in water drinking water is used). The consumption rates for cattle are given in the defaults section for cattle.

Indirect exposure of humans


Biotransfer to meat and milk
QSAR for biotransfer to meat and milk

Travis and Arms (1988) performed a log-linear regression analysis on experimentally derived bioaccumulation factors and the octanol-water partition coefficient. It should be noted that the uncertainty in these estimates is considerable. The concentrations in meat and milk are calculated by applying the bioaccumulation factors and summing the contributions from air, soil, grass and drinking water. The BAF for meat is derived from data on 36 organic compounds, with a log Kow range of 1.5 - 6.5. The BAF for milk was derived from data on 28 organic compounds, with a log Kow range of 3 - 6.5. Outside these ranges the minimum or maximum Kow is used.

(Eq. 107)

(Eq. 108)

Input

Kow	octanol-water partition coefficient [-]

Output

BAFmeat	bioaccumulation factor for meat [d.kg-1]

BAFmilk	bioaccumulation factor for milk [d.kg-1]

Reference

Travis, C.C. and A.D. Arms (1988). Bioconcentration of organics in beef, milk, and vegetation. Environmental Science and Technology 22, 271-274.

Biotransfer to meat and milk

Indirect exposure of humans


Environmental effects assessment

The protection goals for the environment are the aquatic, sediment and terrestrial ecosystem, top predators and microbial activity in an STP. This means that a PNEC has to be derived for each of the protection goals.

Certain assumptions are made concerning the extrapolation from single-species short-term toxicity data to ecosystem effects:

1. ecosystem sensitivity depends on the most sensitive species; and

2. protecting ecosystem structure protects community function.

These two assumptions have important consequences. By establishing which species is the most sensitive to the toxic effects of a chemical in the laboratory, extrapolation can subsequently be based on the data for that species. Furthermore, the functioning of any ecosystem in which that species exists is protected, provided the structure is not sufficiently distorted as to cause an imbalance.

In establishing the size of the assessment factors, a number of uncertainties must be addressed, summarised under the following headings:

1. Intra- and inter-laboratory variation of toxicity data.

2. Intra- and inter-species variations (biological variance).

3. Short-term to long-term toxicity extrapolation.

4. Laboratory data to field impact extrapolation.

In principle, the PNEC is calculated by dividing the lowest short-term L(E)C50 or long-term NOEC value by an appropriate assessment factor. The assessment factors reflect the degree of uncertainty in extrapolation from laboratory toxicity-test data for a limited number of species to the 'real' environment. Assessment factors applied for long-term tests are lower, as there is less uncertainty involved in the extrapolation from laboratory data to the natural environment.

The size of the assessment factor depends on the confidence with which a PNEC can be derived from the available data. This confidence increases if data are available on the toxicity to organisms at a number of trophic levels, belonging to taxonomic groups and with lifestyles representing various feeding strategies. Thus, lower assessment factors can be used with larger and more relevant data sets than the base-set data.

The effects assessment for aquatic and terrestrial ecosystem can be supported by a statistical extrapolation method if at least four NOECs are available for different taxonomic groups.

More specific information for effects assessment for the protection goals:

1. Aquatic ecosystem

2. Terrestrial ecosystem

3. Sediment ecosystem

4. Micro-organisms in a sewage treatment plant

5. Top predators


Statistical extrapolation method

The effects assessment performed with assessment factors can be supported by a statistical extrapolation method (Aldenberg and Slob, 1993) if at least four NOECs are available for different taxonomic groups. The method is applied automatically when more than four NOECs are entered and the resulting PNEC is presented together with the PNEC resulting from the extrapolation with assessment factors. The statistical PNEC is not used to derive RCRs

The no-effect level calculated here is the 50% confidence limit of the concentration that protects 95% of the species in the system for which the experimental NOECs are a representative sample. The method is used for aquatic as well as terrestrial, toxicity data. Values of the extrapolation constant E are dependent on the number of NOECs given. In EUSES, it is not checked whether the toxicity data deviate from the assumed log-logistic distribution. The number of NOECs given is usually too small for the test to be able to reject the log-logistic distribution.

Reference

Aldenberg, T. and W. Slob (1993). Confidence limits for hazardous concentrations based on logistically distributed NOEC toxicity data. Ecotoxicol. Environ. Saf. 25, 48-63.


PNEC

Predicted No-Effect Concentration. A PNEC is regarded as a concentration (in environment or food) below which an unacceptable effect will most likely not occur. The PNEC is combined with the PEC in risk characterisation.


PEC

Predicted Environmental Concentration. The PEC is used as exposure parameter and is compared with the PNEC in risk characterisation.


Spatial scales

For the risk assessment system, a distinction is made between four spatial dimensions: the personal scale, the local scale, the regional scale and the continental scale. At the 'personal scale', individual consumers or workers are considered, exposed directly to individual substances and preparations, and to substances embedded in a solid matrix. The local scale considers the protection goals in the vicinity of one large point source of the substance. The regional scale assesses the risks to protection targets due to all releases in a larger region. A fourth spatial scale, the continental scale (defined as the sum of all EU Member States), is added to serve as background for the regional system (these concentrations are not used for risk characterisation).

The local scale receives the background concentration from the regional scale. The regional and continental calculations are done with a nested multi-media model. The regional scale receives the inflowing air and water from the continental scale.

The local scale

The concentrations of substances released from point sources are assessed for a generic local environment. This is not an actual site, but a hypothetical site with predefined, agreed environmental characteristics, the so-called 'standard environment'. These standard environmental conditions can be average values, or reasonable worst-case values, depending on the parameter in question. The exposure targets are assumed to be exposed in, or at the border of, the area. In general, concentrations during an emission episode are calculated. Only for the soil compartment (being a less dynamic environment than air or surface water) do longer-term averages apply.

Local distribution models

The regional scale

The concentrations of substances released from point and diffuse sources in a larger area are assessed for a generic regional environment, assuming the same environmental characteristics as the local standard environment. The regional model takes into account the further distribution and fate of the chemical upon release, resulting in steady-state concentrations in the environmental compartments. The regional concentrations are used as background concentrations in the calculation of the local concentrations.

Regional distribution models


LC50, EC50 and EC10

LC50

The median Lethal Concentration:

A statistically derived concentration that can be expected to cause death in 50% of the animals exposed for a specified time. This can either be a concentration in the environment (water, soil, sediment, air) or a concentration in food (for bird or mammalian tests).

EC50

The median Effective Concentration:

1. The concentration resulting in a 50% change in a parameter (e.g. algal growth), relative to the control.

2. The concentration at which a particular effect (e.g. Daphnia immobilisation) is observed in 50% of the organism population, relative to the control.

EC10

Same as EC50 but then for 10% effect.


LD50

The median Lethal Dose: statistically derived expression of a single administered dose of a material that can be expected to cause death in 50% of the dosed animals.


NOEC
N(L)OEC

NOEC: No-Observed-Effect-Concentration: the highest concentration without adverse effects.

LOEC: Lowest-Observed-Effect-Concentration: the lowest concentration with adverse effects.

This can either be a concentration in the environment (water, soil, sediment, air) or a concentration in food (for bird or mammalian tests).


NOAEL
N(L)OAEL

NOAEL: No-Observed-Adverse-Effect Level: the greatest concentration or amount of a substance, found by experiment or observation, which causes no detectable adverse alteration of morphology, functional capacity, growth, development, or life span of the target organism under defined conditions of exposure.

LOAEL: Lowest-Observed-Adverse-Effect Level: the lowest concentration or amount of a substance, found by experiment or observation, which causes an adverse alteration of morphology, functional capacity, growth, development, or life span of the target organism distinguishable from normal (control) organisms of the same species and strain under defined conditions of exposure.


Micro-organism effects assessment

As chemicals may cause adverse effects on microbial activity in sewage treatment plants (STP), it is necessary to derive a PNEC. Current test systems for measuring the impact of chemicals on microbial activity have different end-points and sensitivities. At present, only a few internationally accepted test systems exist, such as OECD 209 (inhibition of respiration of activated sludge) and ISO 9509 (inhibition of nitrification). For assessing the toxicity of a substance to micro-organisms in an STP, the effluent concentration is compared to microbial effect data. A PNEC is derived as follows:

1. The PNEC is set equal to a NOEC from a test performed with 'specific bacterial populations' like nitrifying bacteria and P. putida. An EC50 from this test is divided by an assessment factor of 10.

2. A NOEC or EC10 from other test systems like the respiration inhibition test (OECD 209) is divided by an assessment factor of 10. An EC50 from this test is divided by an assessment factor of 100. It should be noted that the effluent concentration is used, while heterotrophic micro-organisms in the aeration tank are probably exposed to a concentration which relates more to the influent concentration. Therefore a higher assessment factor is applied compared with the assessment factor for nitrifying bacteria. For nitrifying bacteria the exposure concentration is more related to the effluent concentration, since nitrification is the last treatment step in an STP.

3. The lowest resulting value is selected as the PNEC.

General help on environmental effects assessment


Aquatic effects assessment

Depending on the available toxicity data for aquatic organisms, assessment factors are selected for extrapolating single-species toxicity tests to a PNEC for the water compartment.

The following trophic levels are distinguished:

1. primary producers (e.g. green algae);

2. primary consumers (e.g. Daphnia species);

3. secondary consumers (e.g. fish species);

4. decomposers.

Assessment factors are applied to the lowest LC50 or lowest NOEC. The procedure for effects assessment is outlined in more detail in Section II.6.1.3 and III.6.1.1 of the background document.

Intermittent release

For a stage of the life cycle were intermittent release is defined, exposure may be of short duration only. For dynamic systems like rivers at least, the likelihood of long-term effects arising from such exposure is low, the principal risk being short-term toxicity effects. In extrapolating to a PNEC, generally only short-term effects need be considered. Therefore, an assessment factor of 100 is applied to the lowest L(E)C50 of at least three short-term tests from three trophic levels to derive a PNEC for such situations.

General help on environmental effects assessment


Terrestrial effects assessment

The terrestrial ecosystem comprises an above-ground community, a soil community and a groundwater community. In EUSES, only effects on soil organisms exposed directly via pore water and/or soil are addressed.

For most chemicals, the number of toxicity data on soil organisms will be limited. At the base-set level for new and existing substances there is no requirement for toxicity tests with soil organisms. For new substances, toxicity tests with plants and earthworms can be requested at level I. For existing substances data will probably be scarce: for most chemicals the data set will consist of short-term tests for earthworms and plants. To compensate for this lack of toxicity data, the equilibrium-partitioning method is therefore used.

Three situations can be distinguished for deriving a PNEC for soil:

1. If no toxicity data are available for soil organisms, the equilibrium-partitioning method is applied to identify a potential risk to soil organisms. This method is regarded as a 'screening approach'.

2. If toxicity data are available for a producer, a consumer and/or a decomposer, the PNEC is calculated using assessment factors.

3. If only one test result with soil-dwelling organisms is available, the risk assessment is performed both on the basis of this test, using assessment factors, and on the basis of the equilibrium-partitioning method. From these two PNECs, the lowest is chosen for risk characterisation.

The same assessment factors are used for the terrestrial system as for the effects assessment for aquatic system. It should be noted that the assessment factors for the soil compartment are not based on comprehensive experience, and as more information on the sensitivity of soil organisms becomes available these factors may have to be adjusted.

The following trophic levels are distinguished:

1. primary producers (e.g. plants);

2. consumers (e.g. earthworms);

3. decomposers (e.g. micro-organisms).

General help on environmental effects assessment


Sediment effects assessment

No data for sediment-dwelling organisms will be available for new substances. To date, only a few tests on sediment organisms have been conducted in Europe with existing substances. However, research is in progress in this field in various countries. In the absence of any ecotoxicological data for sediment-dwelling organisms, the PNEC is provisionally calculated using the equilibrium-partitioning method.

On the local scale, the concentration in sediment will also be calculated assuming an equilibrium with the surface water. This could lead to exposure and effects for the sediment ecosystem both based on the water compartment and thus provide little information. Therefore, if no measured data are available for the determination of PEC in sediment nor for the calculation of PNEC, no quantitative risk characterisation for sediment can be performed.

General help on environmental effects assessment


Equilibrium partitioning

Equilibrium partitioning (EP) refers to the situation where, in a certain environmental compartment, a solid phase and a water phase are in thermodynamical equilibrium. When the solids-water partition coefficient in that compartment is known, the concentration in the solid phase can be estimated from the water phase and vice versa. This approach can be used on the exposure side as well as the effects side.

Exposure

Uptake of chemicals by soil-dwelling organisms and plant roots is usually related to the water phase of the soil compartment. Assuming equilibrium, partition coefficients can be used to estimate porewater concentrations from total concentrations.

Effects

Due to a general lack of toxicity data for soil and sediment organisms, the EP method is applied to estimate a PNEC for the soil and sediment ecosystem from the PNEC for the aquatic organisms. In applying this method, it is assumed that:

1. Soil and sediment-dwelling organisms and water-column organisms are equally sensitive to the chemical.

2. Concentration in sediment, interstitial water and organisms are in thermodynamic equilibrium: the concentration in any of these phases can be predicted using the appropriate partition coefficients.

3. Solids-water partition coefficients can either be measured or derived on the basis of a generic partition method from separately measurable characteristics of the sediment and the properties of the chemical.

It should be noted that the EP approach considers uptake via the water phase only, but uptake may also occur via ingestion of sediment. This may become important, especially for adsorbing chemicals. Thus, for these compounds the total uptake may be underestimated. To avoid a possible underestimation of risks, for compounds with a log Kow greater than 5 the equilibrium method is used in a modified form. In order to take uptake via ingestion of soil or sediment into account, the PEC in soil or sediment is increased by a factor of 10 in risk characterisation for these compounds. It should be kept in mind that this approach is considered as a screening assessment.

General help on environmental effects assessment


Bird effects
Predator effects assessment

For the protection of predating birds and mammals from the effects of secondary poisoning, an effects assessment for these organisms is required.

Available toxicity data

Effects on birds and mammal populations are rarely in the form of mortality following short-term exposure. Therefore, results from (sub-)chronic studies are preferable, such as NOECs for mortality, reproduction or growth. For new substances, the results of mammalian repeated-dose toxicity test(s) are used in the assessment of secondary poisoning effects. For existing substances, toxicity data for birds may be available.

Only toxicity studies reporting on dietary and oral exposure are relevant, as the pathway for secondary poisoning refers exclusively to uptake through the food chain. For the assessment of secondary poisoning, the results must be expressed as the concentration in food (NOEC in mg/kg food). In the absence of an NOEC, EUSES converts the NOAEL (in mg/kg body weight/day) for mammals to a concentration in food. Conversion factors for several experimental mammalian species are given in Section III.6.1.5. This conversion factor is formed by the ratio of the animals bodyweight and its daily food intake. Extrapolation from such test results gives a PNEC in food that should be protective of other mammalian and avian species.

Bird toxicity tests are not usually given for the test durations specified in the pick list (28/90 days or chronic). This test duration is however only used to arrive at a representative assessment factor. The user therefore has to decide whether a longer-term bird toxicity test is comparable to 90 day or chronic mammal test.

Assessment procedure

Assessment factors are used which take into account inter-species variation, sub-chronic to chronic toxicity extrapolation, and laboratory data to field impact extrapolation.

Acute lethal doses (LD50, rat, bird) are not suitable for extrapolation to chronic toxicity, as these tests are not dietary tests. Acute-effect concentrations (LC50, 5 day avian dietary studies) are acceptable for extrapolation because these are dietary studies. An assessment factor of 1,000 is applied to the results from such a test. An assessment factor of 100 (10x10) is applied to the NOEC for the 28-day repeated-dose study with mammals to derive the PNECoral. If a 90-day toxicity text is submitted instead of the 28-day test, this assessment factor may be reduced to 30. When chronic studies are available, an assessment factor of 10 may be used. Reproduction-toxic effects are regarded as chronic effects and the same assessment factor may be used. The suggested assessment factors should be seen as default values. When other factors are judged to be more appropriate, they can be entered by the user.

If both effects data for birds and mammals are given, the lower resulting PNEC is used in risk characterisation. The procedure for effects assessment is outlined in Section III.6.1.5.

General help on environmental effects assessment


Environmental risk characterisation

For the environmental endpoints, RCRs are calculated by comparing the results of the environmental distribution and effects assessment in a ratio of PEC and PNEC. Usually, an RCR exceeding one, indicates reason for concern and may require refinement of the assessment.

More guidance on the interpretation of RCRs, refinement of the risk assessment and the appropriate testing strategies is given in Chapter 4 and 5 of the TGD.

Spatial scales

For most environmental endpoints, an RCR is calculated on both the regional and the local spatial scale. For micro-organisms, however, only the local scale is assessed since these organisms are exposed to the concentration in the STP.

Note on risk characterisation for soil and sediment:

When the equilibrium partitioning is used to derive a PNEC in soil or sediment, and log Kow of the compound exceeds 5 the risk characterisation is slightly modified. In this case, the PEC will be increased by a factor of 10 to account for uptake via ingestion (see Eq. 177 and 181).


Endpoints of the risk assessment

The risk assessment, as laid down in the TGD and implemented in EUSES, considers the following endpoints or protection targets:

Human endpoints

1. Humans exposed at the workplace

2. Humans exposed through use of consumer products

3. Humans exposed indirectly via the environment

Environment

1. The aquatic ecosystem. The organisms are exposed to surface water.

2. The terrestrial ecosystem. The organisms are exposed to the concentration in agricultural soil.

3. The sediment ecosystem. The organisms are exposed to fresh-water sediment.

4. Micro-organisms living in the sewage treatment plant

5. Top predators. Birds or mammals exposed via consumption of fish or earthworms.


RCR

Risk Characterisation Ratio. The general name for the quantitative comparison of exposure and effects.

Risk Characterisation Ratios (RCR) are derived for all end-points, environmental and human. RCRs are derived by comparing exposure levels to suitable (no-)effect levels. In the risk characterisation for the environment this is done by dividing the predicted environmental exposure PEC by the predicted no-effect concentration PNEC. In the risk characterisation for human health this is done by dividing the (no-)effect level, e.g. the NOAEL or LOAEL, by the estimated exposure level. This is the inverse of the RCR for the environment and is called Margin of Safety.

Risk characterisation for the environment

Risk characterisation for human health


MOS

The Margin Of Safety is the risk characterisation ratio (RCR) of a suitable effect or no-effect parameter value (e.g. an acute, oral LD50, a sub-chronic, inhalatory NOAEL or a chronic LOEC in food) and a human exposure value of corresponding time scale and route of exposure.


Release estimation

The releases of a substance at different stages of its life cycle should be estimated by order of preference from:

1. specific information for the substance (e.g. from producers, product registers or open literature);

2. emission scenario documents (use category documents);

3. emission factors as included in the release tables of Appendix IV of the EUSES documentation and implemented in EUSES.

Emission factors

In many cases, little or no specific information on releases will be available, and emission scenario documents are scarce. Therefore use will have to be made of the emission factors of the release tables of Appendix IV, which have been implemented in EUSES. For all industrial categories distinguished in the HEDSET, emission factors have been generated for all (relevant) stages of the life cycle. The estimated emission factors are expressed as the fractions of the tonnage of the substance which will be released to the air, (waste) water and industrial soil.

Results from these tables depend upon the use of the chemical (characterisation, tonnage and use patterns).

Emissions to the environment

The total volume released is averaged over the year and used for the exposure calculation on the regional scale. For the local scale the 'B-tables' of Appendix IV are used for determining the releases from point sources on the local scale. They provide the fraction of the total volume released that can be assumed to be released through a single point source, and the number of days during which the substance is released, thus allowing the daily release rate at a main point source to be calculated. Local emissions are estimated for every environmental compartment and each relevant stage of the life cycle, and for every use pattern that is selected. The emission rate is given averaged per day (24 hours). This implies that, even when an emission only takes place a few hours a day, the emission will be averaged over 24 hours. Emissions to air and water will be presented as release rates during an emission episode.

For the regional and continental spatial scales, it is assumed that 70% of the emission to waste water is treated in an STP and 30% reaches surface water directly. This split is accounted for in the total regional/continental emissions but not in the regional/continental releases per life-cycle stage. This cannot be done as the regional releases are also used to estimate local emissions where all of the chemical passes an STP. See also page III-9 to III-13 of the background document for more explanation.

For each stage, the losses in the previous stage are taken into account (see Section III.3, Release estimation). Note that releases during production are not taken into account in the other stages, as these releases will generally already be accounted for in the reported production volume. The rapporteur must specify whether or not releases are relevant during each stage. If release is not applicable during a certain life-cycle stage, the release fraction must be set to zero. Furthermore, for each stage of the life cycle it is possible to define if intermittent release is appropriate. In that case, exposure may be of short duration only and a specific PNEC is used in aquatic effects assessment.

After losses during the five stages of the life cycle are accounted for, the part of the tonnage remaining is assumed to end up entirely in waste streams. Quantitative methods for estimating emissions at the disposal stage are not currently available.

Defaults section for release estimation.


Use of a chemical

The use of a chemical is specified by two items:

1. Characterisation and tonnage

For the first stage of the life cycle, production, every chemical is characterised as a High Production Volume Chemical (HPVC) or as a New Substance or Existing Chemical (NSEC). Concerning the tonnage of the chemical, the production volume and the volumes imported and exported are input here.

2. Use patterns

Up to 5 use patterns may be specified for one chemical. For every use pattern the emission input data must be specified, consisting of Industrial Category, Use Category and (if appropriate) extra details on Use Category, and the fraction of tonnage for each application. Furthermore it needs to be indicated here which stages of the life cycle are relevant for the current use pattern in the assessment. If relevant for the following stages of the life cycle, i.e. production, formulation and processing, the Main Category may be specified (otherwise the default value is used).

It should be note that when the Hydrocarbon Block Method is used, only one use pattern can be selected.

General information on release estimation


High Production Volume Chemicals (HPVC)

EUSES makes a distinction between High Production Volume Chemicals and New Substances and Existing Chemicals (NSEC).

According to an OECD document a chemical is classified as a High Production Volume Chemical, when it is produced in excess of 10,000 tonnes/year in any one member country, or in two or more countries in excess of 1,000 tonnes. For every Industrial Category the program uses a default value above which the chemical is treated as an HPVC. Some chemicals with a relatively low production volume may be specified as an HPVC in the respect that the substance only can be produced in small quantities and the production takes place at a specific plant over the whole year. In EUSES the user can specify (on account of information of the producer) that the chemical is an HPVC. All other chemicals, described as New Substances and Existing Chemicals (NSEC), are usually produced in smaller tonnages and during a shorter period.


New Substances and Existing Chemicals (NSEC)

In EUSES, a distinction is made between High Production Volume Chemicals and New Substances and Existing Chemicals (NSEC).

Most new substances and many existing chemicals are produced during a limited period and in relatively small amounts. Chemicals produced at a high level and throughout the year are termed High Production Volume Chemicals. Until a certain default value (dependent on the Industrial Category for which the chemical is produced) every chemical is treated as an NSEC. This can be  overruled in the input.


Stages of the life cycle

Releases into the environment can take place at any stage of the life cycle of a chemical substance. The life cycle is represented schematically in Figure II-5 of the EUSES documentation. There is a distinction in five stages:

1. Production

Production is the stage in which the substance is manufactured, i.e. formed by chemical reaction(s), isolated, purified, drummed or bagged, etc.

2. Formulation

Formulation is the stage in which chemicals are combined in a process of blending and mixing to obtain a product or a preparation.

3. Processing

The processing stage consists of all kinds of processes whereby the substance as such, as a formulation or an article containing the substance assessed is applied or used. The substance may be used as a processing aid or be incorporated in a product.

4. Private use

This stage considers the use and application of substances (as such or in formulations) on the scale of households.

5. Disposal

At the stage of disposal, the substance (or the products containing the substance) is disposed of with waste or waste water. Waste water may be treated in a sewage treatment plant. Waste materials may be incinerated or dumped. At the stage of disposal recovery may take place. For some Industrial Categories recovery is considered.

More information is found in the EUSES documentation (Chapter II.3).

General information on release estimation

Specification of the chemicals use


Industrial Category (IC)

The Industrial Categories specify the branch of industry (including personal and domestic use, and use in the public domain) where emissions occur during applications of the substance as such, or during the application and use of preparations and products containing the substance. The 16 ICs considered are available by the pull-down menu in the input section Emission input data and are stated below. Emission-scenario documents have recently been developed and described in the context of the TGD. These documents cover the industrial categories 3, 5, 7, 8, 10, 12, 13 and 14, but were not yet used for the release estimates of EUSES as described in Appendix IV of the EUSES documentation.

The following IC are available:

1. Agricultural industry

2. Chemical industry: basic chemicals

3. Chemical industry: chemicals used in synthesis

4. Electrical/electronic industry

5. Personal/domestic

6. Public domain

7. Leather processing industry

8. Metal extraction, refining and processing industry

9. Mineral oil and fuel industry

10. Photographic industry

11. Polymers industry

12. Pulp, paper and board industry

13. Textile processing industry

14. Paints, lacquers and varnishes industry

16. Engineering industry: civil and mechanical

15/0. Others

General information on release estimation

Specification of the chemicals use


IC 1: Agricultural industry

There are no use-category documents for this IC. Emissions due to the application (processing stage) of pesticides are beyond the scope of the TGD and EUSES. Several UCs are distinguished, e.g. UC=19 'Fertilisers' and UC=41 'Pharmaceuticals'.


IC 2: Chemical industry: basic chemicals

There are no use-category documents for this IC. If a basic chemical is formulated, A- and B-tables are implemented in EUSES as described in Appendix IV of the EUSES documentation. Recovery is not considered as a separate emission stage; emissions of chemicals such as catalysts are included in the emissions at the processing stage. So far, no distinction has been made between UCs, apart from UC=48 'Solvents'. Most chemicals will have to be classified as UC=43 'Process regulators' or UC=55/0 'Others'.


IC 3: Chemical industry: chemicals used in synthesis

Apart from UC=33 'Intermediates' in this IC, most chemicals will have to be classified as UC=43 'Process regulators' or UC=55/0 'Others'. Formulation may be feasible for some chemicals, whilst recovery is unlikely. The release tables are based on Ros and Van der Poel (1989).

Ros, J.P.M. and P. van der Poel (1989). Uitworpverwachting tussenstoffen in de farmaceutische industrie. Bilthoven, National Institute of Public Health and the Environment (RIVM), Internal note RIVM/LAE (in Dutch). (Predicted emissions of intermediates in the pharmaceutical industry)


IC 4: Electrical/electronic industry

There are no use category documents for this IC. There are many different applications in this IC, however, e.g. during production of printed circuits and the application of dielectric fluids in transformers and capacitors. The only distinction is between chemicals included into or onto a matrix (MC=II) and others used at point sources (MC=III) in a process.


IC 5: Personal/domestic

Chemicals used in this IC will in many cases be present in formulations, e.g. in cleaners (soaps, detergents, washing powders, etc.) and products for the care of leather, textiles and cars. Emissions will be very diffuse and the only emissions regarded as a point source situation are those of wastewater to an STP (assuming more or less uniform usage by populations and a uniform usage per week and season). For products like fuels and fuel additives the emissions are calculated in IC=9 'Mineral-oil and fuel industry' at the stage of private use. For paint products and photochemicals this is done in IC=14 'Paint, lacquers and varnishes industry' and IC=10 'Photographic industry', respectively.


IC 6: Public domain

There are no use category documents for this IC. Most chemicals used in this IC will be present in formulations, e.g. in 'cleaners' (UC=9 'Cleaning and washing agents and disinfectants'), non-agricultural pesticides (UC=39 'Pesticides, non-agricultural') and products for the maintenance of roads, buildings, etc. For UC=9, UC=39 and all other UCs, a differentiation in the number of days ( B-tables) and the emission factors (A-tables) has been made.


IC 7: Leather processing industry

A general scenario is presented with default values in the tables for common functions of chemicals such as tanning agents (UC=51). For specific UCs (UC=6 'Anti-set-off and anti-adhesive agents', UC=9 'Cleaning/washing agents and disinfectants', UC=10 'Colorants' and UC=31 'Impregnation agents') different values are used.


IC 8: Metal extraction, refining and processing industry

Although these chemicals are used in many different processes, in this IC a use category document is present for metal-working fluids only (processing stage). The basis for the tables is the document of Van der Poel and Ros (1987). The functions of the fluids are cooling and lubrication, so the tables have specific data for UC=29 'Heat transferring agents' and UC=35 'Lubricants and additives'.

Van der Poel, P. and J.P.M. Ros (1987). Uitworpverwachting snijvloeistoffen en hydraulische vloeistoffen. Bilthoven, National Institute of Public Health and the Environment (RIVM), Report No. 738620001 (in Dutch). (Predicted emissions from cutter fluids and hydraulic fluids)


IC 9: Mineral oil and fuel industry

There are no use-category documents for this IC.


IC 10: Photographic industry

Several use-category documents are available for this IC. The values in the tables are based on the document of Ros and Bogte (1985).

Ros, J.P.M.  and J.J. Bogte (1985). Beoordelingssysteem Nieuwe Stoffen; Onderdeel: Uitworpverwachting fotochemicaliën. Bilthoven, National Institute of Public Health and the Environment (RIVM), Report No. 851502002 (in Dutch). (System for assessing new substances: Predicted emissions of photochemicals)


IC 11: Polymers industry

Although there is a detailed use-category document on the processing stage of polymers, this has not yet been implemented in the tables. The reactions in which the polymers (and prepolymers such as polyesters) are produced are considered to take place in IC=10 'Polymers industry' at the processing stage (i.e. the substances from the production stage are processed by companies in IC=10). For the processing stage a distinction has been made between 'true' polymerisation reactions (see A-tables) and other reactions (polyadditions, polycondensations, etc.). The processing of polymeric materials (thermoplastics and thermosetting resins) is also considered. In the text accompanying the A-tables a short explanation is given on how to interpret the functions of chemicals and the relevant UCs. Today, many thermoplastics are recycled, but this has not yet been taken into account.


IC 12: Pulp, paper and board industry

The tables are based on the use-category documents of Cathie et al. (1991) and Ros and Berns (1988) on paper production (including dyeing of paper) and recycling. Specific tables have been introduced to cover the printing process, which has been included in this IC.

Cathie, K., J. Staves and N. Kirkpatrick (1991). Consultancy Report, Paper recycling industry: Review of processes and effluent. Composition PIRA International, 33/TENQ/012/588.

Ros, J.P.M. and J.A.S. Berns (1988). Beoordelingssysteem Nieuwe Stoffen; Onderdeel: Uitworpverwachting papierchemicaliën. Bilthoven, National Institute of Public Health and the Environment (RIVM), Report No. 738620002 (in Dutch). (System for the assessment of new substances: Predicted emissions ofrom the paper industry)


IC 13: Textile processing industry

The original scenario derived from the document of Ros (1985) has been used for the emission tables.

Ros, J.P.M. (1985). Beoordelingssysteem Nieuwe Stoffen; Onderdeel: Uitworpverwachting textielkleurstoffen. Bilthoven, National Institute of Public Health and the Environment (RIVM), Report No. 851502001 (in Dutch). (System for assessing new substances: Expected emissions of textile dyes)


IC 14: Paints, lacquers and varnishes industry
IC 14. Paints, lacquers and varnishes industry

There are documents available on paint production and paint application, but these have not yet been considered in the emission tables. To obtain better estimates, a distinction has been made between UCs, water-based and solvent-based types, and application by industries and households.


IC 16: Engineering industry: civil and mechanical

For this IC no use-category documents exist. Most tables match the ones applied for chemicals classified in IC=15/0 'Others'.


IC 15/0: Others

General tables have been used.


Use Category (UC)

The Use Category (or function category) depicts the specific function or goal of the substance. Only (possibly) relevant UCs can be chosen in the input section Emission input data. For some Industrial Categories extra information is required to obtain a more accurate emission estimation. This information is input in the input section Emission input data at the questions extra details on use category.

The 55 Use categories are stated in Table II-2 of the EUSES documentation.

More information is found in the EUSES documentation (Chapter II.3.3).


Main Category (MC)

In the context of environmental risk assessment the classification in Main Categories is used to characterise release scenarios for the estimation of emissions during specific stages of the life cycle of the substance, namely production, formulation and processing. The interpretation can differ for the stage of the life cycle considers:

MC	Stage	Interpretation

Ia	Production	Non-isolated intermediates (Industrial Category 3, Use Category 33)

Ib	Production	Isolated intermediates stored on-site, or substances (other than 	intermediates) produced in a continuous production process

Ic	Production	Isolated intermediates stored off-site, or substances (other 	than intermediates) produced in dedicated equipment

II	Formulation	Inclusion into or onto a matrix

Processing	Inclusion into or onto a matrix

III	Production	Multi-purpose equipment

Formulation	Multi-purpose equipment

Processing	Non-dispersive use (industrial point sources)

IV	Processing 	Wide dispersive use (many small point sources or diffuse releases; 	normally no emission reduction measures)

More information is found in the EUSES documentation (Section II.3.3).


Tonnage

The tonnage of a chemical is expressed in tonnes/year and consists of three volumes:

1. Production volume in EU: This is the total amount of the chemical produced in the European Union

2. Volume of chemical imported to EU: This comprises the total amount of the substance (in the form as placed on the market) imported into the European Union.

3. Volume of chemical exported from EU: This comprises the total amount of the substance (in the form as placed on the market) exported into the European Union.

The tonnage that is used for the risk assessment of the chemical for the stages of the life cycle after the stage of production equals the production volume + the volume imported - the volume exported.

The tonnages that are estimated by EUSES at the regional and continental spatial scales are calculated from the EU tonnages. A default fraction of the tonnage at EU level is assumed to be produced and used in the standard region. The continental tonnage will be diminished with this fraction since the calculations at the regional and continental scales are performed with a nested multi-media model. This fraction can be changed in the defaults section for release estimation.

General information on release estimation

Specification of the chemicals use


Fraction of tonnage for application

In the input section Emission input data the fraction of the tonnage applicable for the current use pattern is entered. The sum of the fractions for each of the use patterns must not exceed 1. If there is only one use pattern the fraction has the value one.


Model defaults of EUSES

The default parameters are grouped in separate sections. Click on one of the following items for more information:

Release estimation

Characteristics of compartments

Degradation and transformation rates

Sewage treatment

Regional and continental distribution

Local distribution

Human and predator exposure via the environment

Humans

Exposure variables workers and consumers


Release estimation defaults

The defaults for release estimation that can be changed by the user are:

1. Fraction of EU production volume for region

This is the fraction of the tonnage at EU level, that is assumed to be produced and used in the standard region. The continental tonnage will be diminished with this fraction since the calculations at the regional and continental spatial scales are performed with a nested multi-media model.

2. Fraction connected to sewer system

This is the fraction of the release to waste water which will pass through a sewage treatment plant (STP) on the regional scale. On the local scale, the waste water will always be treated in an STP.

General information on release estimation


Characteristics of compartments defaults

This section contains the defaults for the characteristics of the environmental compartments. Obviously, the characterisation of the real environment will vary in time and space. Since the TGD requires one risk characterisation at EU level, parameter values were chosen, reflecting a typical EU environment. In particular, it should be noted that the parameter settings are not worst case. In fact, it would be difficult to set a worst case since one parameter usually effects more than one process (e.g. increasing the fraction organic carbon in soil will increase accumulation in soil, but at the same time will decrease leaching and bioavailability). The values are set equal on the local, regional and continental spatial scales.

Each compartment is viewed as consisting of the three phases solids, water and air (only relevant in soil). the bulk densities of the environmental compartments (air, water, soil, sediment) are therefore calculated from the bulk densities of these phases and their volume fractions. This three-phase compartment definition is also used to calculate the wet weight-dry weight conversions, the total compartment-water partition coefficients, and .various inter-media transport processes in the regional model

Bulk densities of solids, water and air

Basic property of the three phases. It should be noted that the values are assumed equal for all environmental compartments. Changing any of these values will affects the total bulk density of the compartments and may affect chemical-transport processes. In principle, the air density depends on the environmental temperature but due to the limited importance of the air density in the model, this fact is ignored.

Temperature

At this moment, the environmental temperature is only used to calculate the air-water partition coefficient. No temperature correction of chemical properties is applied.

Constant of Junge equation and surface area aerosol

These parameters are used to calculate the fraction of the chemical associated with aerosol particles. This fraction is again used in the calculation of fate processes in air.

Gas constant

Truly a constant. This parameter cannot be changed by the user.

Properties of suspended matter, sediment, soil and STP sludges

Basic characterisation of the environmental compartments in terms of volume fractions air, water and solids and fraction organic carbon. Changing these values will affect the total bulk density of the compartments, the wet-dry conversions (see below), and may affect chemical-transport processes.

Bulk densities of compartments

The bulk density of each compartment is defined by the fraction and bulk density of each phase. This implies that the bulk density of a compartment cannot be changed independently of the fractions of the separate phases and vice versa. (See Eq. 14, 15 and 16 of the background document).

Conversions for soil and sediment

Intermediate results can be presented and changed on wet-weight or dry-weight basis. The conversion factors for soil and sediment are derived from the compartment definition in phases. The conversion to dry weight can also be used for entering terrestrial toxicity data. (See Eq. 17 and 18 of the background document).


Degradation and transformation rates defaults

This section contains the defaults for the derivation of degradation rates. For air, a default value for the concentration of OH-radicals is given. The default value of 5e5 molec/cm3 is seen as a typical 24-hour average value for Western Europe.

For the degradation in the STP, degradation in soil, and degradation in sediment, rate constants for abiotic degradation can be entered (if known). Usually, no information on abiotic degradation will be known, therefore, the default is set to zero.

Furthermore, for the sediment, the fraction of the compartment that is aerated and the anaerobic degradation rate can be entered. Since only a small portion of the sediment layer is under aerobic conditions, aerobic biodegradation is limited to this layer. For the anaerobic layer, a specific rate constant can be added. The total depth of the sediment layer can be changed in the defaults section on the regional environment.

It should be noted that degradation in sediment and air is only accounted for in the regional distribution model.

General information on degradation and transformation in EUSES.


Regional and continental distribution defaults

In its standard settings, the regional/continental distribution module represents the continent European Union as the sum of all EU Member States, with a typical densely populated region in it. By default, it is assumed that 10% of the EU production and use of the chemical takes place in this region.

The defaults for regional and continental distribution are divided in several sections:

1. Regional and continental (general system definitions)

2. The air compartment

3. Water and sediment

4. The soil compartments

5. Mass transfer coefficients

General information on regional and continental distribution

General information on different spatial scales


Regional and continental system definition

Area, number of inhabitants

The whole of the EU is represented by the sum of the continental and regional systems. The area and number of inhabitants of the continental system are, therefore, calculated in EUSES by difference of the whole of the EU and the regional system:

area continental system = 3.56 x 106 - 40 x 103 = 3.52 x106 km2

inhabitants continental system = 3.8 x 106 - 20 x 106 = 3.6 x 106

Area fractions

The surface of the system is the composite of water, natural soil, agricultural soil, and industrial/urban soil. The default area fractions represent the average of the European Union. The area fractions can be changed; the user should take care to maintain the sum of the area fractions at 1.

Fraction water flow from one scale to another

The water flow from outside the system is used in EUSES for calculating the residence time of water in the system. By default, no water enters the continental system from elsewhere. The standard parameter value (0) for continental system cannot be changed, since the present version of EUSES does not model a global system. In the standard settings, the regional system is thought to be located at the downstream margin of the continental system. A moderate fraction (0.034 or 3.4%) of the water that flows from the continent is directed into the regional system. The value of this parameter can be changed. Its setting affects the residence time of water in the regional system.

Water depth

The default water depth is that of a shallow lake or stream. The water depth can be changed. The value of this parameter is used in EUSES to calculate the residence time of water in the system.

Suspended solids concentration

The standard concentration of suspended solids in water are set somewhat arbitararily. For the continental waters, the value is 25 mg/L: as for a river. For the regional water, the standard value is 15 mg/L: as for a downstream lake. These parameters can be changed. The settings are used in EUSES for two purposes: (i) for calculating fractions of the chemical dissolved in water (which, in turn is used for calculating rates of volatilization, sedimentation and degradation), and (ii) for calculating net sedimentation rates.

Residence times of air and water

Residence times of mobile media are calculated in EUSES as the result of compartment volumes and flow rates (see Section III 4.4.3/2 of the EUSES background document), and cannot be changed.

The residence time of air in the system is determined by the parameters AREA and WINDSPEED.

The residence time of water in the system is determined by the parameters AREA(water), DEPTH, FLOW(water), WASTEWATER, RUNOFF and RAINDIRECT.

Sedimentation rate

Net sedimentation rates are calculated in EUSES by balance of all inputs and outputs of solids (see Section III 4.4.4 of the EUSES background document), and cannot be changed. The net sedimentation rate is determined by the SUSPended solids concentrations in the incoming and outflowing water FLOWs, rates of EROSION from soil, and by the rate of (biogenic) production, SUSPPROD, in the water system itself.

General entry for regional and continental defaults

Regional and continental air

Atmospheric mixing height

The standard mixing height represents average conditions. The parameter can be changed to match more specific atmospheric conditions. Its value sets the volume of the air compartment, and directly influences the calculated PEC in air (and, consequently, all other PECs).

Windspeed

The standard windspeed represents a typical value at 10 m above the surface. The parameter can be changed. Its setting is used in EUSES for calculating the residence times of air in the regional and continental systems.

Aerosol deposition velocity

The aerosol deposition velocity is used for calculating the deposition flux of aerosol-bound chemical. Because deposition velocities of aerosol particles vary greatly with the particle size, the value of this parameter should be set to match the aerosol size in which the chemical occurs in the environment. The standard deposition velocity of aerosol particles is set at an average value of 0.1 cm/s, and should be taken as a starting point only.

Aerosol collection efficiency

This parameter is used for calculating the scavenging of aerosol-bound chemical with rain. It represents the volume of air (m3) that originally contained the amount of aerosol present in one unit (m3) of rain water, and relates to the size-fraction of aerosol responsible for binding the chemical. The standard setting of 200,000 should be taken as a starting point.

Average precipitation

The average amount of rain (m3) per unit of area (m2), per unit time (s). The standard setting of 700 mm yr-1 (average for the European Union) can be changed. The value of this parameter directly affects the transfer rates of the chemical from air to soil and water (atmospheric deposition fluxes), from soil to water (run-off fluxes), and from soil to groundwater (leaching fluxes). In addition, it contributes to the calculated residence times of water at the regional and continental scales.

General entry for regional and continental defaults


Regional and continental water and sediment

Concentration biota

Biota in water stands for all living matter in the surface water compartment: from bacteria to mammals. The standard value is 1 mg/L and can be changed. The settings are used in EUSES for two purposes: (i) for calculating fractions of the chemical dissolved in water (which, in turn is used for calculating rates of volatilization, sedimentation and degradation), and (ii) for calculating net sedimentation rates.

Sediment mixing depth

The standard mixing depth of 3 cm represents typical conditions. The parameter can be changed to match more specific hydraulic conditions. Its value sets the volume of the sediment compartment, and directly influences the calculated PEC in sediment.

Settling velocity of solids

The standard value of 2.5 m/day represents the settling velocity of suspended particles observed in quiet Dutch waters. The parameter can be changed. Its setting affects the transfer flux of chemical from water to sediment.

Production of solids

By default, it is assumed that no production of suspended matter in the water system itself takes place. The parameter can be changed. Its value contributes to the calculation by EUSES of the net sedimentation rate.

General entry for regional and continental defaults


Regional and continental water and sediment
Regional and continental soil

Mixing depth natural soil

The standard mixing depth for natural soil is 5 cm. This value is meant to represent undisturbed soil systems that are reworked only by natural influences. The parameter can be changed. Its value sets the volume of the natural soil compartment, and directly influences the calculated PEC in natural soil.

Mixing depth agricultural soil

The standard mixing depth for agricultural soil is 20 cm. This represents the typical plowing depths in agricultural practice. The parameter can be changed. Its value sets the volume of the agricultural soil compartment, and directly influences the calculated PEC in agricultural soil.

Mixing depth industrial/urban soil

The standard mixing depth for agricultural soil is 5 cm. This value is meant to represent undisturbed soil systems in predominantly paved systems. The parameter can be changed. Its value sets the volume of the industrial/urban soil compartment, and directly influences the calculated PEC in industrial/urban soil.

Fractions rain water infiltrating and running off

By default, it is assumed that 25% of the precipitation to soil infiltrates, the rest evaporates (50%) or runs off directly from the soil to the surface water (25%). These values represent average European conditions. The parameters can be changed. The infiltration rate affects the downward movement of the chemical (leaching flux) from the upper soil to the groundwater. The run-off rate directly affects the transfer of chemical from soil to surface water (run-off flux). It also contributes to the calculation by EUSES of the residence time of water.

Soil erosion

The standard erosion rate of 0.05 mm yr-1 represents flat-land conditions with near-negligible erosion. The value can be changed. The parameter directly affects the transfer of chemical from soil to surface water (erosion flux). It also contributes to the calculation by EUSES of the net sedimentation rate.

General entry for regional and continental defaults


Mass-transfer coefficients

Diffusive mass transfer between air and water, between water and sediment, and between air and soil is calculated in EUSES by film resistance models. These calculations assume that the restance to mass transfer is confined to narrow layers (films) at either sides of the interface. The require partial mass transfer coefficients for the various films. The partial mass transfer coefficients are chemical-specific, but vary more so with the characteristics of the physical interfaces, notably the turbulence. In EUSES, it is assumed that the same partial mass transfer coefficients apply to all chemicals. Standard values are taken from the literature.

General entry for regional and continental defaults


Local distribution defaults

Air

The defaults for the standard concentration and standard deposition flux of aerosol-bound chemical can be changed by the user. These standard figures represent the concentration and flux calculated with the OPS model at a source strength of 1 kg/d. These defaults are used in the air distribution calculations.

Water

The default dilution factor can be changed by the user. Alternatively, the dilution can be calculated based on the flow rate of the river and the effluent discharge of the STP (Eq. 66). The STPs effluent discharge is calculated from the STP defaults (number of inhabitants and sewage flow per inhabitant). The default for the concentration of suspended matter can be changed in the regional water defaults section (local and regional spatial scales share the same value). These defaults are used in the water distribution calculations.

Soil

Two soil types are distinguished on the local scale: agricultural soil and grassland. Three different concentration in soil are required for risk assessment: a PEC for terrestrial organisms, an exposure concentration for crops for human nutrition, and an exposure concentration for grass for cattle consumption. These defaults are used in the soil distribution calculations.

The following parameters can be changed:

1. Mixing depth for terrestrial ecosystem and grasslands. The mixing depth for agricultural soils can be changed in the regional soil defaults section (local and regional spatial scales share the same value). This depth reflects the part of the soil which can be assumed homogeneously mixed (for agricultural soil this is more since this soil type is usually mechanically mixed). The exposure is assumed to occur strictly via this top-soil layer.

2. Sludge-application rate. The amount of sludge from the STP which is applied each year, at the beginning of the growing season.

3. Averaging times. The period of time used to calculate an average concentration in soil. The default period of 30 days for the terrestrial ecosystem reflects the relatively short life span of these organisms. This period can therefore be assumed chronic. The longer period of 180 days reflects the growing season of crops and grass to be used for indirect-human exposure assessment

Several other parameters affecting the fate in soil on the local scale can be changed in the regional defaults section: average precipitation, mass-transfer coefficients, fraction infiltration.

General information on local distribution models.


Defaults for human and predator exposure via the environment
Defaults for exposure via the environment

Plants

Defaults are given which specify a typical or generic plant. These defaults are used both for food crops and grass. Because a typical plant does not exist, due care should be taken when changing these values.

Cattle

Defaults are given for the intake rates of grass, soil, drinking water and air. Furthermore, a conversion factor for plant concentrations is given. The required conversion factor for soil is calculated from the soil properties.

General information on indirect expoure.


Defaults for humans

Daily intake rates

Used in the assessment of exposure of man via the environment (TGD, Section 2.4). A standard consumption pattern is defined, comprising fish, root crops, leaf crops, meat, dairy products and drinking water. For each food product the highest country-average consumption rate of all EU-member states will be used. This will of course lead to a total food basket which is an unrealistic, worst-case scenario. Nevertheless, since usually only one or two routes form the bulk of the exposure, this procedure is acceptable for the initial risk assessment.

Data for food products are taken from ECETOC (1994) Assessment of non-occupational  exposure to chemicals. Brussels, Technical Report No. 58. The water intake value is taken from US-EPA (1989) Exposure factors handbook. Washington DC, EPA/600/8-89/043, PB90-106774.

Inhalation rate

Synonym is daily ventilaton rate. Used in the assessment of the total daily intake for man exposed via the environment (TGD , Chapter 3, Appendix VII), in consumer exposure assessment (TGD, Chapter 3, Appendix IV), and in route-to-route extrapolation  (EUSES background document, Section II.6.2). The default value is taken from US-EPA (1989) Exposure factors handbook. Washington DC, EPA/600/8-89/043, PB90-106774.

Bioavailability through intake routes

Used in the assessment of the total daily intake for man exposed via the environment (TGD , Chapter 3, Appendix VII), the calculation of total exposure in consumer exposure assessment (TGD, Chapter 3, Appendix IV), in risk characterisation for total exposure of consumers (EUSES background document, Section III.7.2.2)  and in route-to-route extrapolation (EUSES background document, Section II.6.2).

The default assumptions are that substances are totally bioavailable through the oral and dermal route (bioavailability factor = 1), and that via inhalation, 75% of the substance is absorbed (bioavailability factor = 1). This is, for instance, also assumed by Vermeire et al. (1993) Estimation of consumer exposure to chemicals: application of simple models. Sci. Total Environ. 136: 155-176.

Bodyweight

Used in various calculations in the risk assessment for man. The default value of 70 kg is based on statistical data from European countries which show that the average body weight for adult men and women combined is near this value.

Oral to inhalatory extrapolation

This box is used to select between the two methods available for extrapolating toxicity data from oral to inhalatory route of exposure.


Bioavailability

Synonym is biological availability. The extent to which a chemical substance to which the body is exposed (by ingestion, inhalation, injection, or skin contact) reaches the systemic circulation, and the rate at which this occurs (WHO, 1979, Agreed terms on health effects evaluation and risk and hazard assessment of environmental agents. Internal report of a Working Group. Geneva, EHE/EHC/79.19).


Defaults exposure variables for workers and consumers
Defaults exposure variables workers and consumers

Defaults for consumer exposure

Respirable fraction of product inhaled

Synonym is inhalable fraction. Used in the estimation of the inhalatory intake by consumers (TGD, Chapter 3, Appendix IV and EUSES background report , Section III.5.3.1). The default assumption is that all material inhaled will be available for absorption (respirable fraction = 1).

Fraction of product swallowed

The fraction of the product that will be ingested. Used in the estimation of the oral intake by consumers (TGD, Chapter 3, Appendix IV and EUSES background report, Section III.5.3.2). The default assumption is that all product will be ingested (fraction of product swallowed = 1).

Thickness of layer of product on skin

Used in the estimation of dermal  intake by consumers scenario A and scenario B (TGD, Chapter 3, Appendix IV and EUSES background report, Section III.5.3.2).  The value of 0.01 cm is taken from Vermeire et al. (1993) Estimation of consumer exposure to chemicals: application of simple models. Sci. Total Environ. 136: 155-176.

Defaults for workers exposure

Average temperature at the workplace

Used in the conversion from ppm to kg.m-3. The default assumption is that the average workplace temperature during working hours is 293 degrees K (25 degrees Celsius).


Selection of assessment types

The assessment type refers to the protection goals to be studied: the environment (i.e. aquatic and terrestrial organisms, sediment organisms), predators exposed via the environment (i.e. fish eating birds and mammals, worm eating birds and mammals), man exposed via the environment (i.e. via air, drinking water and food), man exposed to or via consumer products and man exposed at the workplace. The user furthermore can select the spatial scales to be considered in the environmental assessment(s).

The modes to be selected are the direct mode and the interactive mode. In the direct mode

all output is presented simultaneously after all input has been entered. The calculation steps do not interact. In the interactive mode, the user can assess a substance one calculation step at a time. After each calculation step the user can view and/or modify the intermediate results. The (modified) intermediate results are used as input for the next calculation step.

The Hydrocarbon Block Method (HBM) is implemented for the environmental risk assessment of petroleum substances.


Modules and sub modules of EUSES

The calculation steps or the modules and sub modules are:

1. Physico-chemical properties.

2. Release estimation.

3. Distribution, with the sub modules:

  3.1. partition coefficients,

  3.2. degradation and transformation rates,

  3.3. sewage treatment,

  3.4. regional distribution,

  3.5. local distribution,

4. Exposure, with the sub modules:

  4.1. bioconcentration factors,

  4.2. exposure of predators via the environment,

  4.3. exposure of man via the environment,

  4.4. consumer exposure,

  4.5. workers exposure,

5. Effects assessment, with the sub modules:

  5.1. environmental effects assessment (micro-organisms, aquatic organisms, terrestrial organisms, birds, mammals),

  5.2. human effects assessment.

6. Risk characterisation, with the sub modules:

  6.1. risk characterisation for the environment,

  6.2. risk characterisation for human health.


Effects assessment

In this module, the (eco-)toxicological can be entered. For the environmental endpoints, extrapolation to a PNEC is performed. For human risk characterisation, the experimental data are used directly or with minor conversions.

The module effects assessment, contains two sub modules:

1. Environmental effects assessment (including predators)

2. Human effects assessment.


Risk characterisation

In the risk characterisation module, RCRs are calculated for all endpoints.

The risk characterisation module contains two sub modules:

1. Risk characterisation for the environment,

2. Risk characterisation for human health.


Study, substance, components and blocks

A study describes the complete risk assessment of a substance with EUSES. It holds information on:

1. the substance being assessed

2. the defaults used

3. the assessment path (assessment type, spatial scale, use sewage treatment plant or not)

4. the intermediate and final results.

The user can can load, save and erase studies from the database or start a new study.

The study can be frozen at any point in time in the assessment path. E.g. during an interactive assessment the substance data can be stored after the distribution calculations. At a later point in time the user can load the study from the database and continue the assessment.

Substances means chemical elements and their compounds in the natural state or obtained by any production process, including any additive necessary to preserve the stability of the product and any impurity deriving from the process used, but excluding any solvent which may be separated without affecting the stability of the substance or changing its composition (EC Council Directive 92/32/EC; Council Regulation (EC) No. 793/93). A substance consists of one or more components. In the context of EC regulation a substance normally is characterised by one set of physico-chemical and (eco)toxicological properties. However, in case the Hydrocarbon Block Method concept is applied, data sets are required for each of the blocks within the substance.

Components of a substance are chemically pure entities, in principle characterised by one structural formula. In EUSES, components are relevant entities in the Hydrocarbon Block Method only.

Blocks consist of a single component or a large number of components with similar fate and distribution properties. This concept is applied in the Hydrocarbon Block Method.


Interactive assessment

In the interactive assessment, the user can assess the substance one calculation step at a time. After each calculation step the user can view and/or modify the intermediate results The (modified) intermediate results are used as input for the next calculation step.


Hydrocarbon Block Method (HBM)

The Hydrocarbon Block Method (HBM) is implemented in EUSES for the environmental risk assessment of petroleum substances. The method was originally devised by CONCAWE (The Oil Companies' European Organisation for Environmental and Health Protection). and described in the TGD, Section II.8.The approach has been devised only recently and, hence, experience with its application is limited.

There are many petroleum substances (e.g. refinery streams and solvents) which, although described by a single EINECS number, are hydrocarbon mixtures of varying degrees of complexity. Since hydrocarbons of similar structure will have similar physico chemical properties and environmental-degradation potentials, they will have similar distributions and fates within a given environment. It is therefore possible to group or 'block' such hydrocarbons, so that components having similar properties may be considered together (it should be noted that a 'block' may consist of a single component or a large number of components with similar fate and distribution properties). Once the blocks for a substance have been established, PEC values can be calculated for each block for each environmental compartment.

Since PECs can be obtained for single components, or groups of similar components only, it follows that PNECs must also be estimated for the same individual components or groups of components. Therefore, ecotoxicity data obtained on the whole substance, whether obtained using Water-Accommodated Fractions (WAFs) or dispersions, cannot be used to estimate PNECs. PNECs must be based on the toxicity of the individual blocks. These blocks should show similar modes of action.

From the above it is clear that the PEC/PNEC ratio of the whole substance cannot be derived directly, as neither the PEC nor the PNEC for the whole substance will be available. The PEC/PNEC ratio is therefore derived from the PEC/PNEC ratios of the blocks of components, based on the proportional contribution of each of the blocks to the composition of the whole substance, and assuming that effects will be concentration-additive:

where A,B,C etc. are the blocks.

Blocks will primarily be defined on the basis of those physico chemical and degradation properties that are key in determining the distribution and fate of their components. Care should be taken to ensure that blocks are not so wide as to include components without broadly similar fates and distributions after release. Similarly, blocks should, whenever possible, contain substances with a similar mode of action and a narrow range of toxicity. Both the fate and toxicity criteria for block definition need to be satisfied simultaneously.


Workers exposure

EUSES provides a general-purpose predictive model for exposure assessment in the workplace. The model predicts external exposure only: it does not take into account absorption and bioavailability. If reliable and representative measured data are available these can be used to overwrite the model results before the risk characterisation is carried out. The general-purpose model is called EASE (Estimation and Assessment of Substance Exposure). This model is described in Section 2.2 of the TGD.

EASE was specifically developed by the UK Health and Safety Executive for the purpose of modelling inhalation and dermal workplace exposure across a wide range of circumstances. EASE is an analogue model, i.e. it is based on measured data which are assigned to specific scenarios. The user can build scenarios by choosing between several options for each of the following variables: physical properties during processing (tendency to become airborne, potential for dermal contact), use pattern and pattern of control. The options for these variables are shown in Section 2.2.4.3.2 of the TGD.  Numerical ranges have been assigned to these fields using measured data contained within the UK National Exposure Database for inhalation exposure, and experimental data and expert judgement for dermal exposure. The logic of deriving scenarios and assigning ranges to the scenarios is described in Chapter 2, Appendix I of the TGD.

The data used to assign ranges within the model are all 8-hour time weighted averages and the numbers generated by the model are only valid when the exposures being assessed can be related to such averages.

The output of EASE, numerical ranges of concentrations or ppm (these are subsequently converted from ppm to kg.m-3.), are input for the risk characterisation in which the exposure estimates are compared to the results of the human effects assessment.


Mammalian effects data

Effects data from toxicity tests with mammals are used for two purposes:

1. To extrapolate to a PNEC for predators. This PNEC is used to indicate a chemicals potential to cause secondary poisening. The extrapolation is outlined in the section on effects assessment for predators.

2. The protection goals for the human species are three distinct sub populations: workers, consumers and man exposed through the environment. A range of different data, human as well as experimental, acute as well as (sub-)chronic, needs to be considered as possible input from the available data sets.

For human risk characterisation, effects data from mammals or human studies are used directly or with minor conversions. The procedure is outlined in the section on human effects assessment. Implemented in EUSES are route-to-route extrapolation and other conversions relevant for the human risk assessment: NOEC to NOAEL, ppm to mg.m-3, intermittent to continuous exposure.


Human effects assessment

In EUSES, the quantitative risk characterisation for man is carried out by comparing the results of the effects assessment with those of the exposure assessment. Both spatial and time scales need to be comparable between the effect parameter and the exposure parameter as well as the route of exposure. In the case of workers and consumers, the scenarios can represent an acute situation or a more chronic type of exposure. Risk characterisation for acute exposures is carried out on the basis of acute toxicity data. Risk characterisation is for subchronic or chronic exposure is carried out on the basis of subchronic or chronic toxicity data..

Relevant effect-parameters for the risk characterisation for workers, consumers and man exposed via the environment are shown in Table II-9 of the EUSES background report. Effects data need to be entered only as far as is necessary for the risk characterisation, depending on the sub population (worker, consumer, man exposed via the environment), time scale (acute, (sub-)chronic) and route of exposure (oral, dermal, inhalatory) for which the assessment is made.

General decision rules for the choice of effect parameters in the risk characterisation:

1. If both animal data and human data are available, as a general rule well-reported relevant human data for any given toxicological end-point and route of exposure are to be given preference in the risk characterisation for man. However, the potential differences in sensitivity of human studies and animal studies should be taken into account, on a case-by-case basis.

2. A no-observed effect level is always preferred over a lowest-observed effect level.

3. In case no dermal or inhalatory data are available, EUSES can estimate (no-)effect levels from oral data by route-to-route extrapolation.

In two distinct cases no quantitative risk characterisation is possible: in those cases, a qualitative risk characterisation for human health is required.


Acute exposure

Acute exposure is considered to occur infrequently and over a discrete period of time which is usually significantly less than one day. Reasonable foreseeable misuses will often belong to this category.


(Sub)chronic exposure

If exposures can be judged to occur repeatedly over a longer period of time, the scenario is qualified as subchronic or chronic. Chronic exposure means exposure over the entire lifespan of an organism.


Acute toxicity test

Toxicity test serving to study the effects occurring in a short time following the administration of a single dose or multiple doses within this short time period


(Sub)chronic toxicity test

Chronic toxicity test

A study in which animals are observed during the whole lifespan and in which exposure to a substance takes place over the whole observation period thereof

Subchronic toxicity test

Toxicity test serving to study the effects produced by a substance when administered in repeated doses or continuously over a period of up to 90 days.


Qualitative risk characterisation for human health

If a threshold for toxicity can be assumed but has not been established for the route of exposure under investigation, such data gaps may be filled by EUSES by route-to-route extrapolation. Alternatively, effect parameters may be available for analogue substances and considered relevant input for the substance under investigation by the user. Since a threshold for local irritation very often cannot be derived form the toxicological database, EUSES allows the user to flag substances for this property in the output by entering the appropriate EU classification in the input.

If a threshold cannot be identified in relation to an end-point in case of substances considered genotoxic or (possibly) carcinogenic to man by a genotoxic mechanism of action or in case of sensitising substances, the user can flag substances for these properties in the output by entering the appropriate EU classification in the input.

The classification flags in EUSES are:

Corrosive (C, R34 or R35)

Irritating to skin (Xi, R38)

Irritating to eyes (Xi, R36)

Risk of serious damage to eyes (Xi, R41)

Irritating to the respiratory system (Xi, R37)

May cause sensitisation by inhalation (Xn, R42)

May cause sensitisation by skin contact (Xi, R43)

May cause cancer (T, R45)

May cause cancer by inhalation (T, R49)

Possible risk of irreversible effects (Xn, R40)


Route-to-route extrapolation in human effects assessment

When data are lacking for a relevant route of human exposure, the possibility of using data derived from another route of exposure may be considered. However, it should be realised that there is no simple, direct and generally applicable way in which toxicity data derived from one route of exposure can be used to assess the risks to man from exposure by another route. Factors to be taken into account are differences among routes of exposure with respect to degree and rate of absorption and metabolism. Route to route extrapolation should be used only for substances that produce systemic toxicity distant from the site of entry into the body. It should not be used for substances that act directly and locally at the anatomical point of contact.

EUSES provides some pragmatic approaches to calculating an approximate effect parameter by route-to-route extrapolation. Application of these methods is optional for the user.

The following extrapolations are available:

1. Dermal effect parameter from an oral value: the extrapolation assumes that the dermal value is the same as the oral value on a mg/kg body weight basis. If oral and dermal absorption rates are known, these can be used to adjust the default values. Example

2. Inhalatory effect parameter from an oral value: two methods are available and the user will have to choose (selection can be made in the human defaults section). In the first method, applicable to the (sub-)chronic N(L)OAEL, the ratio of the inhalatory LC50 to the oral LD50 is used to estimate the inhalatory N(L)OAEL. Example

The second method (which is used by default) is direct calculation of the inhalatory effect parameter from the value of the oral effect parameter using the absorption rates via either route and the respiration rate for the appropriate test species. This extrapolation is also used in the estimation of the contribution of exposure via air to the total exposure of man via the environment (see TGD, Chapter 3, Appendix VII, Eq. 20 or EUSES background report, Section III.5.2.5). Example

Other conversions relevant for the human risk assessment are:

NOEC to NOAEL

Ppm to mg.m-3

Intermittent to continuous exposure


Route-to-route example 1

Dermal effect parameter from an oral value, example:

(Eq. 156)

Input

LD50_mammal,oral	oral LD50 for mammals [kg.kg-1]

BIO_oral	bioavailability for oral uptake [-]

BIO_der	bioavailability for dermal uptake [-]

Output

LD50_mammal,der	dermal LD50 for mammals [kg.kg-1]


Route-to-route example 2.1

Inhalatory effect parameter from an oral value, example 1:

(Eq. 161)

Input

LD50_mammal,oral	oral LD50 for mammals [kg.kg-1]

LC50_mammal,inh	inhalatory LC50 for mammals [kg.m-3]

NOAEL_mammal,oral,chr	oral NOAEL for mammals exposed (sub-)chronically [kg.kg-1.d-1]

Output

NOAEL_mammal,inh,chr	inh. NOAEL for mammals/man exposed (sub-)chronically [kg.m-3]


Route-to-route example 2.2

Inhalatory effect parameter from an oral value, example 2.2:

(Eq. 165)

Input

LD50_mammal,oral	oral LD50 for mammals [kg.kg-1]

BIO_oral	bioavailability for oral uptake [-]

BIO_inh	bioavailability for inhalation [-]

BW	body weight of the human considered [kg]

IH_air	daily inhalation rate [m3.d-1]

Output

LC50_mammal,inh	inhalatory LC50 for mammals [kg.m-3]


NOEC to NOAEL

If a (sub-)chronic N(L)OAEL (in mg/kg body weight/day) for mammals is not available but an N(L)OEC (in mg/kg diet) for mammals in food is known, EUSES converts the latter value to the former by taking into account the daily food consumption and the average body weight of the species concerned.

Example:

(Eq. 173)

Input

NOEC_mammal,food,chr	NOEC via food for mammals exposed (sub-)chronically [kgc.kgfood-1]

CONV_mammal	conversion factor NOAEL to NOEC [kg.d.kg-1]

Output

NOAEL_mammal,oral,chr	oral NOAEL for mammals exposed (sub-)chronically [kg.kg-1.d-1]

The conversion factors, available in a picklist in EUSES, are also tabulated in Chapter 3, Appendix VII of the TGD.


Ppm to mg.m-3

In the exposure assessment for vapours, the unit ppm is often preferred by toxicologists since adverse effects are thought to be related to molecules per volume of air, rather than to weight of chemical per unit of volume. Dusts are measured gravimetrically and therefore, their concentration is expressed on a weight-per-volume basis. The sub module EASE therefore predicts vapour exposure ranges in ppm whereas no-effect levels for inhalation exposure are expressed in kg.m-3 (internally) or mg.m-3 (on screen). EUSES will convert the output of EASE in ppm to a concentration in kg.m-3:

(Eq. 172)

Input

TEMP_work	average temperature on the workplace [K]

MOLW	molecular weight [kg.mol-1]

C1_inh,worker,vapour	vapour concentration in air for workers [ppm]

Output

C_inh,worker,vapour	vapour concentration in air for workers [kg.m-3]


Intermittent to continuous exposure

EUSES does not recalculate effect parameters which are derived from experiments with an intermittent exposure schedule to yield a continuous effect parameter. If required, the user will have to make his or her own correction. For instance, the following formula can be used to recalculate the intermittent inhalatory NOAEL to yield a continuous value:

NOAELihl,continuous = NOAELihl,intermittent . x / 24 . y / 7

with 	x = hours per day of intermittent exposure

y = days per week of intermittent exposure

This formula should be used with caution, since it is certainly not applicable to all substances and all tests. Repeated exposure schedules allow time for recovery, whereas on the other hand threshold doses may be exceeded sooner. Therefore, the underlying assumption that the product of time and concentration is constant will not always be valid.


Risk characterisation for human health

The quantitative risk characterisation is carried out by calculating 'Margins of Safety' (MOS). The risk characterisation can be performed for each sub population to be protected and for the time scales and route(s) of exposure chosen. The following combinations of sub population, time scales and routes of exposure can occur:

1. Man exposed via the environment:

    - Time scale: chronic.

    - Routes of exposure: oral and inhalatory combined.

2. Consumers:

    - Time scales: acute and (sub)chronic.

    - Routes of exposure: inhalatory, dermal and oral.

3. Workers:

    - Time scales: acute and (sub)chronic.

    - Routes of exposure: inhalatory and dermal.

For more information on the interpretation of the MOS: see EUSES Background document, Section, II.7.2.1.

General decision rules for the choice of human effect parameters in the risk characterisation are given in the section on human effects assessment. If no quantitative risk characterisation is possible, the user can make this visible in the output of EUSES by using a qualitative risk characterisation for human health.

Specific topics:

Risk characterisation for humans exposed via the environment

Risk characterisation for consumers

Risk characterisation for workers


Risk characterisation for humans exposed via the environment

The exposure of man via the environment is assessed by estimating the total daily intake of a substance in food, drinking water and air at both the local and the regional scale. The total intake via air is converted to an external oral dose by route to route extrapolation and taken together with estimated intakes via food and  drinking water. The risk characterisation is performed by calculating the MOS, i.e. the ratio between this total daily intake and the relevant exposure parameter, which is the (sub)chronic oral N(L)OAEL. It is assumed here that man is exposed throughout his or her lifetime. A subchronic N(L)OAEL is only used if no chronic value is available, and such cases need extra attention in the evaluation of the MOS. Additionally, the air concentration to which man is estimated to be exposed can be compared to the (sub)chronic inhalatory N(L)OAEL, if available. This inhalatory N(L)OAEL will not be estimated from oral data.

General decision rules for the choice of human effect parameters in the risk characterisation are given in the section on human effects assessment.


Consumer exposure

Consumer Exposure Models

The consumer, i.e. a member of the general public who may be of any age, either sex, and in any stage of health may be exposed to a new or existing substance by using consumer products. A consumer product is one which can be purchased from retail outlets by members of the general public and may be the substance itself, or a preparation, or an article containing the substance.

The equations for consumer exposure can be used to estimate external exposure substances used as or in consumer products. Absorption or bioavailability is not taken into account by the equations implemented in EUSES, but should be considered during the risk characterisation stage. Suggestions are given as to when each model could appropriately be applied. Five consumer-exposure scenarios are implemented in EUSES:

The equations can also be adapted to estimate exposure arising from reasonably foreseeable misuse", i.e. when products are not used conform their instructions, but as if they were other, allied products. To adapt the equations, the values for the parameters used in the equations are changed to reflect values foreseen in "reasonably foreseeable misuse". For example, the volume of product or the area of application is set to a different value, reflecting reasonable foreseeable misuse.

Limitations and uncertainties of the models

The equations described here and presented in Section III.5.3 are derived from work in the context of the OECD (OECD, 1993; Vermeire et al., 1993; Van de Meent et al., 1995). Some changes in the equations are implemented, to merge similar equations within the same route of exposure into one general equation for that route. The equations are intended to provide a simple description of consumer exposure, by using only first principles. Most equations give a worst case estimation of exposure, by assuming that all of the compound in the product is at once available for intake and uptake. Intake and uptake themselves are modelled as simple fractions.

If more refined exposure assessments are necessary, the user is referred to programs that contain more complex models, such as CONSEXPO (Van Veen, 1995), THERdbASE, or the US-EPA Household models (Versar, 1991; Versar, 1992).

References


Consumer-exposure references

OECD (1993) Occupational and consumer exposure assessments, OECD environment monographs, OCDE/GD(93)128, Paris.

Van Veen, M.P. (1995) CONSEXPO, a program to to estimate consumer product exposure  and uptake. RIVM report 612810.002, Bilthoven, The Netherlands.

Vermeire T.G., Van der Poel, P., Van de Laar R.T.H., and Roelfzema, H. (1993) Estimation of consumer exposure to chemicals: application of simple models. Science of the Total Environment, 136: 155 176.

Van de Meent, D., De Bruijn, J.H.M., De Leeuw F.A.A.M., De Nijs A.C.M., Jager D.T. and Vermeire T.G. 1995. Exposure Modelling, In Risk Assessment Methods, Kluwer.

Versar Inc. (1991) Screening-Level Consumer Inhalation Exposure Software (SCIES): description and User's Manual Version 3.0, Draft Report. US-EPA 68-D9-0166.

Versar Inc. (1992) DERMAL Exposure Model Description and User's Manual, Final Draft Report. US-EPA 68-D6-0166.


Consumer-exposure scenarios

1. Inhalation: a substance that is released as a gas, vapour or airborne particulate into a room (e.g. a component of an aerosol insecticide, a carrier/solvent in a cosmetic formulation, a powder detergent). Release may be the result of direct release as a gas, vapour or particulate, or by evaporation from liquid or solid matrices. In the latter case, the equation represent a worst-case situation by assuming that the substance is directly available as a gas or vapour.

2. Dermal A: a substance contained in a medium. This dermal scenario also applies to i) a non-volatile substance in a medium used without further dilution (set dilution D=1), and ii) a non-volatile substance in a volatile medium.

3. Dermal B: a non-volatile substance migrating from an article (e.g. dyed clothing, residual fabric conditioner, dyestuff/newsprint from paper).

5. Oral A: a substance in a product unintentionally swallowed during normal use (e.g. toothpaste).

6. Oral B: a substance migrating from an article into food or drink (e.g. plastic film, plastic-coated cups/plates).

General explanation for consumer exposure


Consumer exposure: inhalatory route

A substance used indoors for a relatively short period of time per event (e.g. a component of an aerosol insecticide; a carrier/solvent in a cosmetic formulation; a powder detergent). The equation applies to both volatile substances and airborne particulates. It is assumed the substance is released as a vapour, gas, or airborne particulates, and the room is filled immediately and homogeneously with the substance. Ventilation of the room is assumed to be absent.

It should be noted that for short-term local exposure the value for the room volume V_room  should be reduced (e.g. to 2 m3) to represent the volume of air immediately surrounding the user. If a substance is released relatively slowly from a solid or liquid matrix (e.g. solvent in paint, plasticiser or monomer in a polymer, fragrance in furniture polish), the equation (presented in Section III.5.3) acts as a worst case estimation, estimating the maximum possible concentration.

The equation applies to both volatile substances and airborne particulates. The concentration in air after using an amount q of the product becomes

The air concentration C_air results in an inhalatory intake of

Input

q	amount of product released [kg]

w_f	weight fraction of compound in product [-]

V_room	room size [m3]

f_resp	respirable fraction of the inhalated compound [-]

Q_inh	ventilation rate of person [m3/day]

T	duration of contact per event [days]

BW	body weight [kg]

n	mean number of events per day [1/day]

Output

I_inh	inhalatory intake of compound [kg/kg body weight/day]

C_inh	air concentration [kg/m3]

Consumer exposure scenarios


Consumer exposure: dermal route, model A

A substance contained in a medium

The assumption behind the equations is that all of the substance on the skin is potentially available for uptake. This is the case when the medium is well mixed or only present as a thin film on the skin. The dermal equations apply for

i) a non-volatile substance in a diluted product,

ii) a non-volatile substance in a medium used without further dilution, and,

iii) a non-volatile substance in a volatile medium.

In the latter case, the dermal exposure concentration C_der is only valid at the very beginning of exposure. However, this concentration can still be used to calculate the total amount of substance A_der present on the skin, because the substance is non-volatile and the amount available for uptake does not change when the medium evaporates. The equations can also be used in case of a volatile substance, but in that case they represent a worst case situation because the volatilisation is not accounted for.

Model equations

Consumer exposure scenarios


Consumer exposure: equations dermal A

The concentration in the product as used is calculated from

The total amount to which the skin is exposed is then given by

The potential uptake per kilogram body weight per day is derived as

The above dermal equations apply also for i) a non-volatile substance in a medium used without further dilution (set dilution D=1), and, ii) a non-volatile substance in a volatile medium. In the latter case, the concentration C_der is only valid at the very beginning of exposure. However, this concentration can still be used to calculate A_der, because the substance is non-volatile. The above dermal equations can also be used in case of a volatile substance, but in that case they represent a worst case situation.

Input

C_prod,der	concentration of compound in product before dilution [kg/m3]

D_der	dilution factor [times diluted]

RHO_prod,der	density of product before dilution [kg/m3]

q_prod,der	amount of product used [mg]

Fc_prod,der	weight fraction of compound in product before dilution [-]

V_prod,der	volume or product used before dilution [m3]

V_appl	volume of diluted product actually contacting the skin [m3]

T_der	thickness of product layer on skin [m]

S_der	area of contact between product and skin [m2]

BW	body weight [kg]

n	mean number of events per day [1/day]

output

C_der	dermal concentration of compound on the skin [mg/m3]

A_der	amount of compound on skin per event [mg]

U_der,pot	amount of compound that can potentially be taken up [kg/kg body weight/day]

Consumer exposure scenarios


Consumer exposure: dermal route, model B

A non-volatile substance migrating from an article

The assumption behind the equation is that only part of the substance will migrate from the article (e.g. dyed clothing, residual fabric conditioner, dyestuff/newsprint from paper) and contact the skin. The migration is assumed to be slow enough to be represented by a constant migration rate multiplied by the time of contact. The exposure calculation will involve estimating the amount of substance which will migrate from the area of the article in contact with skin during the time of contact. Dyestuff amounts in fabrics and paper are usually given as weight of product per unit area (e.g. mg/m2).

The amount to which the skin is exposed is given by

where C_der T_der is equal to weight per unit of area.

Extractability in simulated body fluids for several classes of dyestuffs and different fabric types has been evaluated by ETAD (Project A 4007 Final report on extractability of dyestuffs from textiles 1983). For migrating substances, only a part of the total amount A_der is able to reach the skin. The amount to be used is

where Fc_migr,der  T must be much smaller than 1.

The potential uptake per kilogram body weight per day is then derived as

.

Input

Fc_migr,der	fraction of compound migrating per unit time [kg/day]

T	duration of contact per event [day]

T_der	thickness of product [m]

S_der	area of contact between product and skin [m2]

C_der 	concentration of compound [mg/m3]

BW	body weight [kg]

n	mean number of events per day [1/day]

Output

A_der	total amount of compound to which the skin is potentially exposed [kg]

A_migr,der	amount to which the skin is expected to be exposed due to migration [kg]

U_der,pot	potential uptake [kg/kg body weight/day]

Consumer exposure scenarios


Consumer exposure: oral route, model A

Substance in unintentionally swallowed product

A substance in a product unintentionally swallowed during normal use (e.g. toothpaste). The exposure equations may also be used to estimate exposures arising from ingestion of the non-respirable fraction of inhaled airborne particulates. The equations may also be used to estimate exposures arising from ingestion of the non-respirable fraction of inhaled airborne particulates.

The concentration in the product as swallowed is calculated from

and the intake is then given by

If an undiluted product is swallowed, D=1.

Input

C_prod	concentration of compound in product before dilution [mg/m3]

D_oral	dilution factor [times diluted]

q_oral	amount of product before dilution [mg]

Fc_oral	weight fraction of compound in product before dilution [-]

V_prod,oral	volume of product before dilution [m3]

V_appl	volume of diluted product that is per event in contact with the mouth [m3]

f_orl	fraction of Vappl that is ingested [-]

BW	body weight [kg]

n	mean number of events per day [1/day]

Output

C_oral	concentration in ingested product [mg/m3]

I_oral	Intake [mg/kg body weight/day]

Consumer exposure scenarios


Consumer exposure: oral route, model B

A substance migrating from an article into food or drink

It is assumed that the substance in a layer of thickness T_a of article (e.g. plastic film, plastic-coated cups/plates) in contact with the food will migrate to the food. The migration rate is assumed to be constant, and the migration rate multiplied by the contact duration is the fraction of substance that is migrated to the food. The equation can be used to give a conservative estimate of substance uptake by a defined volume of food. The value of the migration rate m_f will be influenced by the type of food (eg fatty/dry/moist), the period of exposure and the temperature at which it occurs. Consumer exposure level will be influenced by the proportion of the contaminated food eaten.

The following equation can be used to give a conservative estimate of substance uptake by a defined volume of food.

Oral intake is given by

Input

S_a	surface of article in contact with food [m2]

T_a	thickness of article in contact with food [m]

C_a	concentration of compound in article [mg/m3]

Fc_migr	migrated fraction per time [mg/day]

V_p	volume of food [m3]

T	contact duration between article and food [day]

BW	body weight [kg]

n	mean number of events per day [1/day]

Output

C_oral	concentration in ingested product [kg/m3]

I_oral	intake [kg/kg body weight/day]

Consumer exposure scenarios


Risk characterisation for consumers

The concentration of the substance in air, a medium swallowed or on the skin is compared to an effect or no-effect concentration of the corresponding time scale and route of exposure (see also effects assessment for human health). Likewise, a potential dermal uptake rate for a substance in contact with the skin and an intake rate for a substance in a medium swallowed are compared to effect or no-effect doses of the corresponding time scale and route of exposure. It should be noted that in the context of the risk characterisation for human health, only one effect parameter will be available per time scale and per exposure route.

The following table shows the Margins of Safety (MOS) which can be calculated for consumers, provided the required effects and exposure results are available. It is essential to realise that the risk assessment is based on external exposure estimates or measurements only. It may be the case that absorption and bioavailability should be taken into account, e.g. if the MOS in the table indicates reasons for concern and further refinement of the risk assessment is required. This refinement is outside the scope of EUSES. Additional tools offering uptake models have been incorporated into CONSEXPO (Van Veen, 1995).

Risk characterisation for consumers: inhalation exposure

Risk characterisation for consumers: dermal exposure

Risk characterisation for consumers: oral exposure

Risk characterisation for consumers: all routes combined


CONSEXPO

Van Veen, M.P. (1995) CONSEXPO, a program to to estimate consumer product exposure  and uptake. RIVM report 612810.002, Bilthoven, The Netherlands.


Risk characterisation for consumers: inhalatory

If the time scale is acute, the Margin of Safety is calculated by dividing the acute inhalatory NOAEL for man, LOAEL for man or LC50 for experimental animals by the estimated concentration in the air of a room. For chronic exposure, the (sub)chronic inhalatory NOAEL or LOAEL is divided by the estimated annual average  concentration in air.

The following RCRs are used for the risk characterisation. The effects to compare the exposure measure to are mentioned at the right, and have to be provided by the user at the Effects-data dialogues.

The following RCRs are used for the risk characterisation.

RCR	exposure measure	available effects data

RCRacute_cons,inh	C_inh	LC50 (mammal, inhalatory)

NOAEL (man, inhalatory, acute)

LOAEL (man, inhalatory, acute)

RCRchronic_cons,inh	C_inh,annual	NOAEL (man, inhalatory, chronic)

LOAEL (man, inhalatory, chronic)

See also: Acute and Chronic exposure measures, Effects and Risk Characterisation

General decision rules for the choice of human effect parameters in the risk characterisation are given in the section on human effects assessment.


Risk characterisation for consumers: dermal

Two exposure parameters can be calculated at both the acute and the chronic timescale: the potential dermal uptake and the concentration of the substance in the product on the skin.

If the time scale is acute, two Margins of Safety can be calculated provided the required input parameters are available:

1. one by dividing the relevant toxicity parameter, i.e. the dermal NOAEL for man or the dermal LOAEL for man or the dermal LD50 for experimental animals, by the acute dermal potential uptake;

2. one by dividing the relevant toxicity parameter, i.e. the dermal NOEC in a medium for man, or the dermal LOEC in a medium for man, by the concentration of the substance in the product on the skin.

For chronic exposure, again two Margins of Safety can be calculated provided the required input parameters are available:

1. one by dividing the relevant toxicity parameter, i.e. the dermal NOAEL for man/mammals or the dermal LOAEL for man/mammals, by the chronic dermal potential uptake;

2. one by dividing the relevant toxicity parameter, i.e. the dermal NOEC in a medium for man, or the dermal LOEC in a medium for man, by the annual average concentration of the substance in the product on the skin.

The following RCRs are used for the risk characterisation. The effects to compare the exposure measure to are mentioned at the right, and have to be provided by the user at the Effects data dialogues.

RCR	exposure measure	available effects data

RCRacute_cons,der	U_der,pot	LD50 (mammal, dermal)

NOAEL (man, dermal, acute)

LOAEL (man, dermal, acute)

C_der	NOEC (man, medium, acute)

LOEC (man, medium, acute)

RCRchronic_cons,der	U_der,pot	LD50 (mammal, dermal)

NOAEL (man, dermal, chronic)

LOAEL (man, dermal, chronic)

C_der	NOEC (man, medium, chronic)

LOEC (man, medium, chronic)

See also: Acute and Chronic exposure measures, Effects and Risk Characterisation

General decision rules for the choice of human effect parameters in the risk characterisation are given in the section on human effects assessment.


Risk characterisation for consumers: oral

If the time scale is acute, the Margin of Safety is calculated by dividing the acute oral NOAEL or LOAEL for man or the LD50 or Discriminating Dose for experimental animals by the estimated ingestion rate of the substance.

Two exposure parameters can be calculated at the chronic time scale: the ingestion rate of the substance and the concentration of the substance in the ingested product. Therefore, two Margins of Safety can be calculated provided the required input parameters are available:

1. one by dividing the relevant toxicity parameter, i.e. the oral  NOAEL or LOAEL for man or mammals, by the chronic estimated ingestion rate of the substance;

2. one by dividing the relevant toxicity parameter, i.e. the oral NOEC or LOEC in food for experimental animals by the annual average concentration of the substance in the ingested product.

The following RCRs are used for the risk characterisation. The effects to compare the exposure measure to are mentioned at the right, and have to be provided by the user at the Effects-data dialogues.

RCR	exposure measure	available effects data

RCRacute_cons,oral	I_oral	LD50 (mammal, oral)

DD (mammal, oral)

NOAEL (man, oral, acute)

LOAEL (man, oral, acute)

RCRchronic_cons,oral	I_oral	NOAEL (mammal, oral, chronic)

LOAEL (mammal, oral, chronic)

NOAEL (man, oral, chronic)

LOAEL (man, oral, chronic)

C_oral,ann/RHO_prod	NOEC (man, food, chronic)

LOEC (man, food, chronic)

See also: Acute and Chronic exposure measures, Effects and Risk Characterisation

General decision rules for the choice of human effect parameters in the risk characterisation are given in the section on human effects assessment.


Consumer exposure: acute and chronic exposure

Effects related to acute and chronic exposures differ in the sense that acute exposure will cause effects related to the mean or maximum event exposure, while chronic exposure will cause effects related to the lifetime average exposure. Because consumer products are used lifelong, the lifetime average exposure is well approximated by the year average exposure, averaging out seasonal usage differences. The equations used for consumer exposure model exposures as constant concentration, thereby equalling mean and maximum event concentrations. For acute exposure, exposure is characterised by the inhalatory, dermal, and oral concentrations, C_inh, C_dermal, and C_oral respectively. For chronic exposures, the exposure is characterised by the year average exposure:

Both the acute as well as the chronic characterisation of exposure is given. The acute one is compared to the LD50, the chronic one to the chronic NOAEL or LOAEL.

See also: Effects and Risk Characterization


Consumer exposure: total exposure

If a consumer is exposed to a substance in a particular consumer product via different routes, the contribution of each route to the total uptake can be summed as  more routes may be relevant at the same time. Differences in bioavailability for the various routes are accounted for by multiplying the intakes (or potential uptakes) with absolute absorption factors. This summation is done separately for the acute time scale and for the chronic time scale according to the following equation:

Input

I_inh	inhalatory intake of substance [kg.kg_bw-1.d-1]

U_der,pot	potential uptake [kg.kg_bw-1.d-1]

I_oral	intake	[kg.kg_bw-1.d-1]

BIO_oral	bioavailability for oral intake [-]

BIO_inh	bioavailability for inhalation [-]

BIO_der	bioavailability for dermal uptake [-]

Output

U_tot	total uptake for one product via different routes [kg.kg_bw-1.d-1]

If the time scale is acute, the Margin of Safety is calculated by dividing the acute oral NOAEL or LOAEL for man or the LD50 or Discriminating Dose for experimental animals by the estimated total intake of the substance (U_tot/BIO_oral for acute exposures).

If the time scale is chronic, the Margin of Safety is calculated by dividing the (sub)chronic NOAEL or LOAEL for mammals or by the estimated total intake of the substance (U_tot/BIO_oral for (sub)chronic exposures).

The risk characterisation can be summarised by the following RCRs:

 RCR	exposure measure	available effects data

 RCR_acute,consumer	U_tot/BIO_oral	LD50 (mammal, oral)

DD (mammal, oral)

NOAEL (man, oral, acute)

LOAEL (man, oral, acute)

RCR_chronic, consumer	U_tot/BIO_oral	NOAEL (mammal, oral, chronic)

LOAEL (mammal, oral, chronic)

NOAEL (man, oral, chronic)

LOAEL (man, oral, chronic)


Reasonable foreseeable misuse

Reasonable foreseeable misuse covers extremes of normal use patterns and allied use of a product not conform the instructions of the producer. Reasonable foreseeable misuse with regard to a dye for cloths is, for example, a baby sucking or chewing on the cloths. See also Sections 2.1 and 2.3.4 of the TGD.


DD

Discriminating Dose

The highest of four pre-set acute dose levels which can be administered without causing compound-related mortality. The dose administered should aim at producing evident toxicity, but no mortality. Evident toxicity refers to toxic effects seen following administration of a test substance, which are of a severity such that administration of the next higher dose level could result in mortality (Commission Directive 92/69/EC, Official Journal of the European Communities, L383 en L383A) . Used in the Fixed Dose Procedure which is an acute oral toxicity test alternative to the LD50 test as described in test guidelines OECD 401 and EC Annex V.B1.


Risk characterisation for workers

Exposure of workers is estimated by means of the model EASE. Exposure ranges are estimated for inhalatory exposure to vapours, fibres and dust and for dermal exposure. The data used to assign ranges within the model are all 8-hour time weighted averages and the numbers generated by the model are only valid when the exposures being assessed can be related to such averages. The timescale of these estimates is regarded as chronic.

In the risk characterisation for inhalatory exposure, the Margin of Safety is calculated by dividing the (sub-)chronic inhalatory NOAEL or LOAEL for mammals/man by the estimated exposure of workers to vapour, fibres or dust.

For dermal exposure, the Margin of Safety can be calculated in two ways:

1. one by dividing the (sub-)chronic NOAEL or LOAEL for mammals/man by the estimated potential dermal uptake;

2. one by dividing the (sub-)chronic NOEC or LOEC in a medium for man by the estimated concentration of the substance in the product in immediate contact with the skin. This concentration is calculated from the output of EASE, W_der,worker, as follows:

Concentration in the product in immediate contact with the skin = W_der,worker  / (TH_der  . n)

Input

W_der,worker	dermal weight of substance on skin of worker per day [kg.m2.d-1]

TH_der	thickness of product [m]

n	mean number of events per day [d-1]

Decision rules regarding the choice of effect parameters are given in the section on human effects assessment.