B19: Extrapolating the Applicability of Worker Exposure Measurement Data

Description

The purpose of this project is to develop criteria and examples (case studies) that can be applied to evaluate if exposure measurements for a given substance(s) and use scenario(s) might be reasonably representative for another substance used in the same or similar manner, as well as for the same substance in other use scenarios. The goal is to develop a pragmatic and agreed process for incorporating existing exposure measurement data on chemical substances (that have been obtained experimentally as opposed to modeled estimates) into worker exposure assessments that are typically undertaken in support of chemicals regulations.

It is anticipated that the process may also be applicable to other settings e.g. occupational hygiene, epidemiology, but in the first instance it is driven by the needs of the European REACH regulation.

The final result should be a structured framework which will enable exposure assessors to consistently and transparently use available workplace exposure data on chemicals to improve the reliability of assessments with less extensive supporting measurement data.

To build this framework, a number of aspects needs to be studied and criteria or approaches need to be developed. These aspects, criteria and approaches include:

• Adequacy of measured data sets for use in chemical safety assessment, in relation to the variability in exposure levels and the distance between the exposure values and toxicologically relevant reference values
• Data types and data quality with regard to worker exposure data and a pragmatic scheme for evaluating and classifying measured data in relation to data types and data quality
• Comparability or similarity of substance properties in relation to worker exposure
• Comparability or similarity of work situations in relation to worker exposure

The approach of using adequate and sufficiently similar measured data from the source situation (i.e. other substances and or situations) should help to improve the confidence in the safe use in situations where exposure levels are not very far below the toxicological threshold values or where the datasets for the target situation (i.e. the situation to be assessed) is (very) limited.