Worker Exposure Tool - User guide

V2.0

 

INTRODUCTION

The ECETOC TRA Worker tool is available as a stand-alone tool (Excel spreadsheet).
It allows the user to calculate predictions for inhalatory and dermal exposure (Tier 1 level) for the benefit of performing Chemical Safety Assessments. For more information on the background, the underlying science and the structure of the tool refer to the ECETOC Technical Report No. 93 and addendum to it, Technical Report No. 107.

 

OPENING THE TOOL

Upon opening the tool the user will be presented with a Security Warning.

 

Click on ‘Enable Macros'. The tools opens with showing the input module.

At the bottom of the screen the tabs indicate the worksheets in the tool (Input module, Fugacity, Value look up, PROC, Duration of Activity, RPE, Mixtures, Dermal, Demosub1 (01-02-03)).

 

The worksheets ‘fugacity' till ‘Dermal' contain the tables used in the calculation of exposure. The worksheet ‘Demosub1 (01-02-03)' is an example of a linear report. The linear report contains the results of the calculations for all exposure scenarios of a substance as well as a basic risk assessment (when reference levels have been stated by the user).

 

USING THE TOOL

Stepwise approach to generate an estimate of worker exposure for a substance.

START: Enter the Substance Specific Data in the input fields.

For more information on each of the input fields, hover over upper right corner (red triangle) of the cell with the question mark: a comment will pop up.

Note regarding Indicative Reference Values
The tool enables the user to evaluate whether the predicted exposure constitutes a risk. Therefore Indicative Reference Values (both for inhalatory and dermal exposure) can be entered. The type of reference value used is up to the user and does not necessarily be a DNEL. 
Note that the tool will generate exposure estimations without the input of Indicative Reference Values (however, this currently has its impact on the Linear Report; refer to STEP 4, page 4).

Note regarding Likelyhood to become airborne
When the substance is a solid (select ‘Yes' in the drop-down box of the question ‘Is this substance solid?'), the tool will consequently ask you to select a dustiness degree from a drop-down box (Dustiness: Low, Medium, High). The ‘Volatility' box cannot be populated (disabled).

When the substance is a liquid (select ‘No' in the drop-down box of the question ‘Is this substance solid?'), the tool will consequently ask you to enter the vapour pressure of the substance in Pascal (Volitility). The ‘Dustiness' box cannot be populated (disabled).

When the vapour pressure of a liquid is below 0.01 Pa, the tool will generate an exposure estimate of 0.1 ppm, for those scenarios (PROC and presence of LEV) for which it is assumed that no aerosol formation will occur. The following message will be shown after generating the exposure estimate.

 

STEP 1. Enter a scenario name and select the appropiate Process Category (PROC) and area of use (Industrial or Professional setting) in the Exposure Scenario Builder.

Note regarding the selection of PROCs
For more information on the PROC, open the tab ‘PROC'.
In the example above (scenario on industrial formulation) it is fairly easy to select the proper PROC; PROC no. 5 (Mixing or blending in batch processes (multistage and/or significant contact)) is covering this scenario properly. However, there are activities (e.g. maintenance) for which the selection of the PROC is more difficult. In this situation the user has to select a PROC which, based on the specific characteristics of the task, best reflects this activity or task. So for maintenance, depending on the extent of exposure opportunities, one might select PROC 8a (Transfer of chemicals from/to vessels/ large containers at non dedicated facilities) or PROC 4 (Use in batch and other process (synthesis) where opportunity for exposure arises).

Some of the PROCs (7, 12, 20) are restricted to industrial or professional setting. The tool will disable the option that is not applicable (either ‘Industrial Activity' or ‘Public domain (Professional) Activity').

Some combinations of PROCs and aggregation state are not valid. The tool will display the following message, when generating the exposure estimate. You will need to change one of the input parameters to enable the tool to calculate an exposure estimate.

 

STEP 2. Select the relevant conditions for the Exposure Modifiers by clicking the appropriate radiobuttons or selecting the appropriate option from the drop-down boxes.

Notes on populating some of the fields
The field ‘Is Local Exhaust Ventilation present?' can only be populated, when in the previous field (Does this activity take place indoors or outdoors?) ‘Indoors' was selected.

The field ‘Select the concentration range (w/w)' can only be populated, when in the previous field (Is the substance used in a Preparation' the option ‘Yes' was selected.

 

STEP 3. Click on ‘Generate Report'.

This will display a box report on the right of the data entry area (green/blue), stating the exposure scenario with the conditions selected and the exposure predictions calculated by the tool. Further iteration on this scenario with the Exposure Scenario Builder is possible: make the desired changes in the exposure scenario and click again the "Generate Report" button. The box will be updated with information from the new calculations.

 

STEP 4. Create a Linear Report

Having finished the iteration on the scenario and in order to perform a basic risk characterization, click the button ‘Copy Scenario results to the Linear Report' to generate a report that will be stored under a separate tab (name: substance name + CAS no). The scenario will be added to the report in a linear way. After completing a new scenario, clicking this button will add this new scenario to the report (new line). In this way all scenarios related to a substance can be collected under the same tab and further processed in the CSA.

NOTE that a complete and proper Linear Report will ONLY be generated when having entered Indicative Reference Values!! This will be modified in the next version of the tool.

When starting with a new substance and after entering the new substance details, any new exposure scenarios related to the new substance will be stored under a new tab, stating the name of the new substance.

 

DELETING SCENARIOS.

By clicking "Clear Scenario", the information in the Exposure Scenario Builder is cleared, allowing a new exposure scenario to be built for the same substance. 
Clicking "Clear All" will remove all the input parameters for the substance and allows the user to work on a new substance.