• Open Access

International Frameworks Dealing with Human Risk Assessment of Combined Exposure to Multiple Chemicals


  • European Food Safety Authority

  • Correspondence: emrisk@efsa.europa.eu
  • Acknowledgement: EFSA wishes to thank the members of the task force on chemical mixtures for the preparatory work on this scientific output: Jean Lou Dorne, Marco Binaglia, Anna Castoldi, Arianna Chiusolo, Jose Cortinas-Abrahantes, Fanny Heraud, Georges Kass, Ragnor Pedersen, Johann Steinkellner, Anthony Smith, Nathalie Thatcher. EFSA greatly acknowledges Jan Alexander, Diane Benford, Jean Charles Leblanc and Susanne Hougaard Bennekou and the members of the Scientific Committee for reviewing this scientific report. EFSA's Scientific Committee, Scientific Panels and units are acknowledged for providing recommendations on future activities.
  • Approval date: 9 July 2013
  • Published date: 12 July 2013
  • Question number: EFSA-Q-2011-00765
  • On request from: EFSA


The development of harmonised terminology and frameworks for the human risk assessment of combined exposure to multiple chemicals (“chemical mixtures”) is an important area for EFSA and a number of activities have already been undertaken, i.e. in the fields of pesticides and contaminants. The first step prior to a risk assessment of combined exposure to multiple chemicals is problem formulation defining the relevant exposure, hazard and population to be considered. In practice, risk assessment of multiple chemicals is conducted using a tiered approach for exposure assessment, hazard assessment and risk characterisation. Higher tiers require increasing knowledge about the group of chemicals under assessment and the tiers can range from tier 0 (default values, data poor situation) to tier 3 (full probabilistic models). This scientific report reviews the terminology, methodologies and frameworks developed by national and international agencies for the human risk assessment of combined exposure to multiple chemicals and provides recommendations for future activities at EFSA in this area.