Guidance on harmonised methodologies for human health, animal health and ecological risk assessment of combined exposure to multiple chemicals

harmonised methodologies, risk assessment, combined exposure to multiple chemicals, mixtures, dose addition, response addition, interactions
First published in the EFSA Journal
25 March 2019
20 February 2019


This Guidance document describes harmonised risk assessment methodologies for combined exposure to multiple chemicals for all relevant areas within EFSA's remit, i.e. human health, animal health and ecological areas. First, a short review of the key terms, scientific basis for combined exposure risk assessment and approaches to assessing (eco)toxicology is given, including existing frameworks for these risk assessments. This background was evaluated, resulting in a harmonised framework for risk assessment of combined exposure to multiple chemicals. The framework is based on the risk assessment steps (problem formulation, exposure assessment, hazard identification and characterisation, and risk characterisation including uncertainty analysis), with tiered and stepwise approaches for both whole mixture approaches and component‐based approaches. Specific considerations are given to component‐based approaches including the grouping of chemicals into common assessment groups, the use of dose addition as a default assumption, approaches to integrate evidence of interactions and the refinement of assessment groups. Case studies are annexed in this guidance document to explore the feasibility and spectrum of applications of the proposed methods and approaches for human and animal health and ecological risk assessment. The Scientific Committee considers that this Guidance is fit for purpose for risk assessments of combined exposure to multiple chemicals and should be applied in all relevant areas of EFSA's work. Future work and research are recommended.

Panel members at the time of adoption

Simon John More, Anthony Hardy, Vasileios Bampidis, Diane Benford, Susanne Hougaard Bennekou, Claude Bragard, Thorhallur Ingi Halldorsson, Antonio F Hernández‐Jerez, Michael John Jeger, Konstantinos Panagiotis Koutsoumanis, Hanspeter Naegeli, Antonia Ricci, Guido Rychen, Josef R Schlatter, Vittorio Silano, Søren Saxmose Nielsen, Dieter Schrenk, Dominique Turck and Maged Younes.
Scientific Committee
sc.secretariat [at]
EFSA Journal 2019;17(3):5634
Question Number
On request from
EFSA Scientific Committee