Interim position statement on the approach to PMT concept to support UK REACH risk management of PFAS

The Department for Environment, Food and Rural Affairs (Defra) recently published a policy paper outlining an interim approach to the Persistent, Mobile, and Toxic (PMT) concept to support the UK REACH risk management of per- and polyfluoroalkyl substances (PFAS). This approach aims to enhance regulatory control over PFAS, which are known for their extreme persistence and mobility in the environment. It applies to England, Scotland and Wales.

The paper considers the PMT approach to be more suitable for regulating PFAS than the established persistent, bioaccumulative and toxic (PBT) and very persistent and very bioaccumulative (vPvB) categories in UK REACH because many PFAS do meet the regulatory criteria to be classified as 'bioaccumulative' or 'toxic'. However, the persistence and mobility of PFAS, combined with potential toxicity, presents risks to environmental quality and public health through environmental exposure routes.

Understanding the PMT Concept

The PMT concept is designed to address the unique challenges posed by substances that are not only persistent but also highly mobile and toxic. Unlike traditional risk assessment models that rely on thresholds or predicted no-effect concentrations, the PMT concept focuses on the intrinsic properties of chemicals – their persistence, mobility and toxicity properties. This approach is particularly relevant for PFAS, due to their resistance to environmental breakdown and their ability to spread widely through water systems.

The interim approach emphasizes a non-threshold regulatory principle, which prioritizes minimizing emissions of PMT substances throughout their lifecycle rather than identifying safe exposure levels. This precautionary approach is intended to guide early regulatory intervention and prevent irreversible environmental harm. The document also highlights the use of Article 57(f) of UK REACH, which allows substances identified as PMT to be considered substances of very high concern (SVHCs) due to their equivalent levels of concern.

Future implications

While the interim approach currently targets PFAS, the methodology may later be expanded to cover other PMT substances. The Environment Agency has been tasked with advancing the scientific and technical tools needed to support this strategy. This includes improving environmental monitoring and developing new risk assessment models that better capture the unique challenges posed by PMT substances.

With appreciation to Vidisha Singh for her contribution in preparing this blog.