People and organisms in the environment are exposed to complex mixtures of chemicals from food contact materials, cosmetics, pesticides, and many more (FPF reported and here). It has empirically been demonstrated that the combined exposure to chemicals can have harmful effects even when each chemical in the mixture is present below its regulatory limit (FPF reported). Still, current regulations assess and manage chemical risks individually. This results in an underestimation of the risk of real-world chemical exposure.
Food Packaging Forum board member, Thomas Backhaus from RWTH Aachen University and the University of Gothenburg, together with co-authors, call on European policymakers to explicitly account for mixture effects by integrating a Mixture Allocation Factor (MAF) into the upcoming revision of the EU’s REACH Regulation (FPF reported) in a policy brief published on November 13, 2025, in Science.
The scientists propose concentration addition as a principle to estimate the combined effects of multiple chemicals (FPF reported). They illustrate the MAF with a “risk cup,” where the cup represents the maximum chemical pressure humans or ecosystems can safely tolerate. Each chemical contributes to filling the cup, and by adjusting the fraction of each chemical, regulators can ensure that the cup does not overflow. This approach ensures that risk-driving chemicals undergo stricter risk mitigation measures while not penalizing producers of low-risk chemicals and limiting bureaucracy. Backhaus and co-authors discuss the difficulty of determining a protective enough MAF value. They propose starting with a modest MAF of five and refining it with new data becoming available.
The authors argue that the adoption of a MAF is a pragmatic step forward given that it is included in the EU’s Chemicals Strategy for Sustainability (FPF reported) and aligns with CO2 equivalents used in greenhouse gas comparison. “It’s time chemical risk management catches up with what biology and environmental science have long shown,” Backhaus says. “A more mixture-aware REACH would improve the protection of both, human health as well as the environment, while supporting innovation in chemical industry.”
In June 2025, over 250 leading European scientists signed an open letter to the European Commission, calling for inclusion of a MAF in REACH revision (FPF reported).
Reference
Backhaus, T. et al. (2025). “Include a mixture allocation factor to improve EU chemical risk management.” Science. DOI: 10.1126/science.aeb6374
