EFSA and RIVM organised an international symposium to reflect on the state of play in research with regard to the risk assessment and toxicity testing of chemical mixtures in Europe. On 18 and 19 May 2016, Dutch researchers, scientists, stakeholders and policy-makers were joined by their European and international peers to discuss scientific progress in this field. 

The European Food Safety Authority (EFSA) and the European Commission are developing a process by which risk assessment of mixtures can be integrated into future decision making on the safe use of pesticides. EFSA and the Commission highlighted their ongoing work and illustrated how the results of the EU European Union (European Union) funded ACROPOLIS project are being used in the follow-up activities. A number of stakeholders reflected on the proposed methodology for grouping pesticides based on their toxicological properties. Questions were raised on practical future use. The methodology is based on the animal tests that are currently available to assess the toxicological properties of a single compound. The limitation in the current approach is, that it is based on an observation of effects only, without understanding the precise working mechanism of mixtures. Therefore many uncertainties remain and a conservative approach is adopted leading to large numbers of pesticides within one group.

Challenges and innovation 

There is a need for new challenges and innovation in mixture testing for a broad range of chemicals. A range of innovative research projects was presented at the two-day symposium. Recently the European Commission has funded a research project focusing on the toxicological risks of mixtures: the EuroMix project. This project will improve the understanding of how chemicals should be grouped based on a better understanding of the mechanism of action. The EUToxRisk21 project will also contribute to a better understanding of these mechanisms of actions. The feasibility of screening a high number of chemicals will be studied in this project. Other topics of these projects include societal needs for reducing animal testing.



Health effect

People can become exposed to chemicals via the environment, food, the workplace or via the use of consumer products. In this regard the new European Biomonitoring Initiative was presented and how it will contribute to better understanding the overall health effect based on questionnaires, health examination and biomonitoring results. The effect of early exposure to chemicals later in life was addressed in presentations from the Exposomics project and the EDC-MixRisk project, essential for making scientific progress on the risks of endocrine-disrupting chemicals. These projects demonstrated the advantages of close cooperation between toxicology and epidemiology.

Future testing 

Furthermore, the way forward was discussed. EFSA announced a working group on mixtures that will start in June 2016, which goes beyond the current work already performed by EFSA on risk assessment of pesticides only. The current methodology is limited by a lack of understanding of the mechanism or mode of action of mixtures. The European projects presented at the symposium might contribute to a better understanding of this. 

International collaboration 

The symposium highlighted the need for collaboration on mixture research between European Member States and the international organisations in a sustainable form, rather than on an ad hoc basis. An open platform, on which future risk models addressing mixture effects can be used by all stakeholders, was advocated and will be delivered by the EuroMix project. For future acceptance of mixture risk assessment, world-wide harmonisation of the methodology is very important. Experts from Europe and the United States of America provided presentations and it was discussed how mixture research could be better aligned internationally.