Mixture risk assessment approaches to evaluate oral exposure to PFAS: Outputs and recommendations of an expert workshop

Per- and polyfluoroalkyl substances (PFAS) often co-occur as contaminants in drinking water and food. Various mixture risk assessment (MRA) approaches have been published to address the associated human health risks.

The Dutch National Institute for Public Health and the Environment (RIVM) organized an online workshop to discuss PFAS MRA approaches. Over 50 experts participated, representing research institutes, universities and government organizations internationally. A discussion document with scientific literature and considerations on PFAS MRA approaches was shared with participants ahead of the workshop.

The workshop yielded overall agreement among participants in support of evidence pointing towards no interaction and dose-additivity of PFAS mixtures. Participants broadly supported the need for a flexible, component-based MRA approach to accommodate the variability in PFAS mixtures and the integration of new PFAS. Overall, the workshop underscored the need to ensure that risk assessments are both scientifically robust and practically feasible, and showed that the global mixture risk assessment community is largely in agreement regarding evaluation of PFAS.

The input received as well as the outcomes of this workshop were used by RIVM in a recommendation to the World Health Organisation (WHO) on suitable approaches for assessment of PFAS in food and drinking water.