OECD’s work on environmental exposure assessment of chemicals focuses on the following 4 areas.
These activities, supervised by the Task Force on Exposure Assessment (TFEA), are composed of experts nominated by OECD member countries and observer organisations. This Task Force was established in 1995, following a recommendation from the OECD Workshop on Environmental Hazard/Risk Assessment.
In 2008, OECD member countries agreed to extend the scope of the work to human health exposure assessment. The 4 topics were identified by the Task Force as initial activities of interests on human exposure assessment, and several follow-up projects have also started.
(1) Release estimation
The OECD develops emission scenario documents (ESDs) that describe the conditions and parameters for release estimation in specific industry and use categories. These ESDs improve the estimation of releases of chemicals to the environment.
Estimation of releases of chemicals to the environment related to the use of products and articles is becoming increasingly important in risk assessment of chemicals of concern. Although these releases are covered in some of the ESDs, further activities to address this issue are under consideration. This work is in close co-operation with the Pollutant Release and Transfer Register (PRTR) Programme) . A Joint project on removal emission predictions of wastewater treatment for exposure assessment and PRTRs has been initiated between the TFEA and the Task Force on PRTRs.
Industry categories and/or use categories shown below have been applied for the development of emission scenario documents. A mapping table used in the United States, Canada and EU was developed in 2012.
(2) Exposure models
A variety of computer models are used in environmental exposure assessment. OECD compiled the descriptions of existing models and tools used for exposure assessment following the results of an OECD survey in 2010. It includes a table summarising descriptions of existing models and tools used for exposure assessment, as well as responses to the survey
OECD developed a guidance document on the use of multimedia models in the assessment of overall persistence (POV) and long-range transport potential (LRTP) as well as an OECD POV and LRTP Screening Tool. These were developed as a follow-up to an OECD/UNEP Workshop in October 2001.
Harmonised approaches for the use of exposure models were discussed in the Workshop on the Application of Simple Models for Environmental Exposure Assessment in 1991.
(3) Use of monitoring data
Guidance document for exposure assessment based on environmental monitoring data (2013) provides guidance for performing an exposure assessment based on environmental monitoring data. It covers topics such as: environmental levels and distribution of contaminants;
- ways of using monitoring data in exposure assessments for differing purposes;
- the collection of data;
- quality of monitoring activities
- examples of data compilation in member countries and their use in exposure assessment.
This guidance document was developed as a follow-up activity of the Workshop on Improving the Use of Monitoring Data in the Exposure Assessment of Industrial Chemicals (Berlin, May 1998). The workshop delivered a number of recommendations on improving the availability of monitoring data, better design of monitoring programmes, and enhanced dialogue between monitoring and risk assessment communities. Specific projects to follow up on these recommendations are on-going.
(4) Reporting of exposure information
OECD published a Guidance Document on Reporting Summary Information on Environmental Occupational Exposure in December 2003. A set of formats for reporting information including monitoring and modelling studies is included in the guidance document.
The TFEA has been discussing collecting use pattern information and developing a harmonised template to gather and exchange exposure information.
The TFEA has initiated work on children’s exposure to chemicals, combined exposure to multiple chemicals, emissions/releases from products.