Assessment of chemicals

OECD activities on exposure assessment


The OECD work on exposure assessment of chemicals focuses on the following 4 areas inclucing several on-going projects:


These activities, supervised by the Working Party on Exposure Assessment (WPEA), are composed of experts nominated by OECD member countries and observer organisations. The Working Party was established in 1995, following a recommendation from the OECD Workshop on Environmental Hazard/Risk Assessment.


(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 WPEA and the Working Group on PRTRs.  


(2) Exposure models

A variety of computer models are used in environmental exposure assessment. OECD published a database and document for exposure assessment models used in a regulatory context, which were gathered from member countries through a survey in 2021.  It could illustrate the varied uses of models in regulatory exposure assessments.

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 on the Use of Multimedia Models held in Ottawa, Canada in 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

The Guidance document for exposure assessment based on environmental monitoring data (2013) provides guidance for performing an exposure assessment based on environmental monitoring data and 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. 


(5) Combined exposure to multiple chemicals

The Working Party on Hazard Assessment and the WPEA have been working on assessing risks from the combined exposures to multiple chemicals to develop guidance documents on considerations for problem formulation, hazard assessment and exposure assessment, and risk characterisation.


(6) Exposure via products

OECD published a document on International Harmonised Use Codes in May 2017 which compares function and cosumer product codes in different countries. Specific projects on evaluating the exposure via products are on-going.




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