Improving 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.

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 discussed.

This presentation will first present an overview of the current discussion in regulatory policy and science and then presents an algorithm on how the MAF can be estimated from the risk profile of a mixture. The algorithm will be applied to selected case studies. Finally, we will discuss knowledge gaps, suitable MAF sizes as well as the general pros and cons of applying the MAF for regulatory mixture risk assessment.

Read more about Chemical Risk Assessment.