Two-day training  /  October 19, 2020  -  October 21, 2020

EFSA training no. 1: Combined exposure to multiple chemicals

Harmonization of risk assessment methodologies for human health and ecological risk assessment of combined exposure to multiple chemicals

Human and ecological risk assessment of combined exposure to multiple chemicals (also referred to as “chemical mixtures”) poses a number of challenges to researchers, risk assessors and risk managers. The development and application of harmonized methodologies for the assessment of multiple chemicals has been identified as a key priority area for the European Food Safety Authority (EFSA). Hence, the Scientific Committee of EFSA published a guidance on harmonized methodologies for human health, animal health and ecological risk assessment of combined exposure to multiple chemicals in March 2019.

Training topic

First, a short review of the key terms, scientific basis for combined exposure risk assessment and approaches to assessing (eco)toxicology of combined exposures will be provided. Existing frameworks for risk assessment of combined exposure to multiple chemicals were evaluated by EFSA, resulting in a harmonized framework for risk assessment of combined exposure to multiple chemicals. The framework as published as EFSA Guidance in 2019 is based on the risk assessment steps (problem formulation, exposure assessment, hazard identification and characterization, and risk characterization including uncertainty analysis), with tiered and stepwise approaches for both whole-mixture approaches and component-based approaches.

The course will provide demonstration materials on the component-based approaches including the grouping of chemicals into common assessment groups, the use of dose or concentration addition as a default assumption, approaches to integrate evidence of interactions and the refinement of assessment groups. In particular cases, the default dose or concentration addition assumption might need further testing. Based on that, further refinements might be included into the risk assessment.  

During the training, the trainees will perform case studies. These case studies will illustrate how to perform lower tier risk assessment of combined exposure to multiple chemicals based on default or conservative assumptions. The pro’s and con’s as well as the feasibility of lower tier approaches will be discussed. The outcome of lower tier case studies will be compared with the health-based guidance values or human and environmental protection goals.

In those cases where the latter are exceeded using lower tier assumptions or data, higher tier assessment using more advanced methods such as probabilistic modeling might be needed. The principles of probabilistic modeling will be explained and trainees will learn about the models by performing exercises using deterministic and probabilistic approaches. The applicability of these approaches in various EFSA panels and/or chemical sectors will be discussed. 

Organizational details

EFSA staff is kindly asked to register via the EFSA workflow, not via this website.

EFSA reserves the right to select the participants of this two-day training course from all registered persons. Shortly after the registration deadline, all registrants will be informed whether they can actually attend the selected training.

Training materials will be sent to all participants a few days prior to the training.