Guidance for Effective Use of Human Exposure Data in Risk Assessment of Chemicals

Background

The structures and processes by which risks are assessed and managed should themselves be risk-informed. This requires that full and proper account needs to be taken of the human exposure situation. Accepted practices for the hazard assessment of human health and environmental safety of chemicals include the use of models and analogues to fill data gaps for specific endpoints (either for single or multiple chemicals that share structural similarities or similarities in metabolism in mammals, fish and other organisms). For example, this approach is acceptable, with limitations, in preparing dossiers for REACH and, in this respect, the OECD has published guidance on the formation and use of chemical categories for data gap filling.

However, such a structured approach is absent for how human exposure data might be reliably assessed. Moreover, with an ever increasing number of models becoming available for addressing different aspects of human health exposure, it would appear prudent to identify best practices (which models might best be applied when and with what purpose in mind). This is particularly relevant for chemical safety assessments on lower volume registrants under REACH, where it is generally acknowledged that there is a paucity of measured data and hence recourse to modelled approaches will be necessary.

Terms of reference

The Task Force is asked to address the following remits:

a) Identify what types of exposure data are required for current and near future risk assessment purposes.
b) Review current sources of exposure data /information with respect to these needs.
c) Identify quality criteria for exposure data that enables different types of data to be suitably weighted and accounted for.
d) Identify ways in which more efficient use of exposure data can be achieved (e.g. by utilising existing category and read across approaches, exposure banding).
e) Develop a set of illustrative worked examples to support the validity and practicability of the framework and quality criteria.
f) Organise a workshop with participation of key stakeholders (to be identified by the TF) for dissemination and discussion of the TF‘s work

29 November 2016

The Task Force published their findings as Technical Report no.126: Guidance for Effective Use of Human Exposure Data in Risk Assessment of Chemicals.

To understand and predict health risks posed by exposure to substances it is necessary to interpret both the toxic properties and the potential exposure to that substance:
Risk = Fn(Hazard, Exposure)

While standardised, internationally accepted methods are available to understand hazard and toxicity, standardised methods and tools to measure, describe or make accurate and robust exposure predictions are not so common. In addition, there is sometimes confusion and misunderstanding about what tools and data should be applied to predict exposures for specific circumstances, what the level of precision of these methods is, and in particular how to predict aggregate consumer exposure to a substance that might be contained in a number of consumer products.

This task force activity had two principle aims:
1.    Review the landscape of the various tools and methods available currently to estimate consumer exposures.
2.    By using case studies, the strengths and weaknesses of the various tools and methods for assessing consumer exposures to different classes of substances were examined. In particular, a focus on aggregate exposure was considered and various methodologies and data inputs were reviewed.

Based on these analyses the task force produced:
1.    A set of best practices guiding the use of existing tools that are best suited for specific applications
2.    A set of recommendations to reduce variability and improve quality of exposure predictions, and to broaden cooperation between industry, academics and the regulatory community to drive activities improving exposure quality.

A workshop was also organised involving experts from industry, academia and the regulatory community to review and discuss the task force output. A synopsis of the meeting together with recommendations for improving quality and reducing variability in consumer predictions are found in ECETOC Workshop Report no. 31: Advances in Consumer Exposure Science: Data, Modelling and Aggregate Exposure Assessment. 26th January 2016, Brussels. (available at http://bit.ly/ecetoc-wr31)

It is hoped that the task force report will be of use to both regulatory bodies and industry in providing guidance on the appropriate use of different exposure tools and data for different purposes. Additionally, the task force output should provide a path forward with regards to further research and data that can be gathered by the broader risk assessment community in order to facilitate better exposure assessments in the future.

The task force report has been published as ECETOC Technical Report no.126: Guidance for Effective Use of Human Exposure Data in Risk Assessment of Chemicals. The Executive Summary and free PDF of the report are available at http://bit.ly/ecetoc-tr126 

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