RDE671 Regulatory threshold values for PFAS

PFAS are a very large and chemically diverse group of synthetic fluorinated organic chemicals, widely used in industrial applications and consumer items. They are extremely persistent in the environment. Some PFAS bioaccumulate and are harmful to human health, with reported effects including reproductive and developmental effects and impaired immune function. In the UK, available monitoring data for surface waters indicates significant environmental contamination by variable and complex mixtures of PFAS, especially in locations near sites with high PFAS use and release such as airports and PFAS manufacturing and formulation sites. Understanding the impact of PFAS on the environment and on human health via environmental exposure is a rapidly developing area of research. Whilst a few PFAS, such as PFOA, are relatively well studied, the majority of PFAS lack sufficient data to fully identify and characterise their hazards. Additionally, there is uncertainty over how to assess mixture toxicity for this group of substances. Development of adequately robust approaches for identifying and characterising the hazards for both individual PFAS and mixtures are an urgent need globally, as regulators and the scientific research community strive to interpret the significance of environmental PFAS concentrations measured and determine acceptable environmental thresholds for regulatory risk management action. In the UK, there is currently an Environmental Quality Standard (EQS) for PFOS, which is used in the regulation of discharges of water. However, there is an operational need for robust, evidence-based thresholds for additional PFAS to assist the Environment Agency to manage environmental risk from other PFAS, either as individual chemicals or as a group. This includes those PFAS frequently detected in the water environment, for example, PFBS, PFHxS, PFHxA and PFPeA. Several approaches for determining regulatory thresholds for PFAS have been proposed globally by regulatory authorities. This includes thresholds for individual PFAS as well as groups of PFAS. A recent example is a proposal published by the EU to use the Relative Potency Factor (RPF) approach to derive an EQS for 24 PFAS (EU, 2024)*. Varying approaches have been taken when deriving such thresholds to deal with the existing knowledge gaps on the hazardous properties of PFAS. We require a review of the existing regulatory and research landscape to establish a robust scientific understanding of knowledge globally on approaches to standard setting for PFAS. This is needed to inform our future approach to derive robust regulatory thresholds for PFAS in England including future EQS derivation for PFAS.