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Will a mixture assessment factor improve the regulatory assessment of combination effects of chemicals?

Could implementing a mixture assessment factor improve the regulatory assessment of combination effects of chemicals?

More than 200 participants joined the FRAM zoominar where Prof. Thomas Backhaus presented the result of a project with the Swedish Chemicals Agency about a possible implementation of an additional safety factor considering mixtures in the regulatory assessment of combination effects of chemicals.

Hazardous chemicals do not occur as isolated entities in an otherwise pristine environment but form complex multi-component mixtures, which can easily comprise dozens of chemicals. Empirical data clearly show that the risk of such mixtures exceeds the risk of each mixture component, which is also recognized in policy documents such as the new European chemical strategy for sustainability that was published by the EU Commission in 2020. The Mixture Assessment Factor (MAF, also termed Mixture Allocation Factor) has been suggested as a pragmatic tool to account for the risks from a mixture already during the risk and safety assessment of individual chemicals.

In the FRAM seminar from July 1, our Director Prof. Thomas Backhaus presented an overview of the current ongoing discussion in regulatory policy and science and then presented an algorithm on how the MAF can be estimated from the risk profile of a mixture. The algorithm was applied to selected case studies that was presented. Knowledge gaps, suitable MAF sizes as well as the general pros and cons of applying the MAF for regulatory mixture risk assessment was also discussed.

- The aim is to reduce the need for dedicated and data-demanding scenario-specific mixture risk assessments. Several decision makers and regulatory authorities seem to be reaching a consensus that the MAF is indeed a pragmatically useful approach. However, several operational details still need to be further discussed, says Thomas Backhaus, Professor in Ecotoxicology at the University of Gothenburg and director of the FRAM centre.

The presentation was based on a recent project together with Swedish Chemicals Agency.  Prof. Thomas Backhaus is the author of the report “Improving the regulatory assessment of combination effects: steps towards implementing the mixture assessment factor (MAF) in chemical regulation (PM 8/21)”.

“The aim of this report was to provide an overview of the recent scientific information on the need for an additional mixture assessment factor (MAF), in order to account for combination/mixture effects during the evaluation of risks for humans and the environment. A second aim was to develop an approach on how to estimate a sufficiently protective, but not overly conservative, MAF. The report is intended as a contribution to the current discussions on how to deal with combination effects of chemicals in EU legislation.”

Find the report on the Chemicals Agency Website.

Watch the presentation here (27:45 min).

How the EU's new chemicals strategy relates to chemical mixtures

The European Commission published the Chemicals Strategy for Sustainability on 14 October 2020. In December 2020, FRAM hosted a seminar about what does this strategy meant for chemical mixtures.

Read a report from the seminar and watch the recording here