Policy paper

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

Published 4 June 2025

Applies to England, Scotland and Wales

Setting out an approach to PMT or vPvM supporting PFAS risk management

1. A healthy environment and clean water are important resources. They are essential to life, modern society, and a productive economy. Chemical pollution presents a risk to environmental quality and to human health through environmental exposure. In line with the environmental principles of prevention and rectification at source, management of chemicals to reduce substances entering the environment is preferable to remediation or removal through treatment. This is costly and can require onward management through waste streams.

2. Given the scale of chemicals manufacturing and use, there is a need for chemicals management that ensures high levels of environmental and human health protection. Action can be prioritised by our understanding of the risks. The risks will be determined by a combination of certain intrinsic properties of chemicals as well as factors such as production volumes and pathways to receptors. There may be data gaps and uncertainties within risk assessments. So a lack of full scientific certainty shall not be used as a reason for inaction where there are threats of serious or irreversible environmental damage. This is in line with the precautionary principle.

3. For poly- and perfluoroalkyl substances (PFAS), high persistence is a key concern which may drive action. In addition, PFAS movement around environmental and biological systems is a risk factor. Substances with combined high persistence and environmental mobility properties have an increased potential to reach aquatic environments that are physically and temporally remote from their origin. PFAS with these characteristics are long lived in such environments and cannot be removed efficiently using conventional remediation techniques.

4. The development and use of a concept to capture this concern more clearly in regulation is needed. It is similar to the established persistent, bioaccumulative and toxic (PBT) and very persistent and very bioaccumulative (vPvB) categories in UK REACH. A regulatory description of PBT or vPvB concerns was developed to identify chemicals that have the potential to cause impacts on food chains and exert toxic effects through accumulation in organisms. The impacts may be difficult to predict and may occur remote from their source of release. In both concepts, the intrinsic property of high environmental persistence is a key determining factor. This is because the environmental concentrations will take a long time to decline following source control. This has been used as a basis for developing the PMT concept.

5. While some PFAS meet the criteria to be identified as PBT or vPvB, others do not meet the regulatory criteria as bioaccumulative or toxic. They are still persistent and detected widely in the environment, including places remote from sources. For example, since 2021, the Environment Agency has monitored for 43 PFAS in over 2,000 groundwater and 1,000 surface water samples. Recent analyses of the data show PFAS are detected in

• 46% of groundwater samples
• 88% of surface water samples
• all fish samples

6. The breaching of groundwaters by PFAS demonstrates their ability to remain intact and penetrate barriers such as soils which can retain and degrade other substances. This environmental contamination requires management to mitigate risks of human exposure. Outside of occupational settings, the major sources of exposure to humans could occur through dietary exposure (ingestion of contaminated drinking water, foods and via food packaging containing PFAS). There may also be indoor exposure pathways, including inhalation of indoor dust and its ingestion, and dermal contact with other media containing PFAS.

7. The persistence and mobility, combined with potential toxicity, present a risk to environmental quality and public health through environmental exposure routes. Currently, risks from PMT-type substances can be addressed within UK REACH but in a limited way. For example, it may be possible under Article 57(f) to demonstrate that a persistent, mobile, and toxic substance has an equivalent level of concern (ELoC) to the recognised hazard presented by PBTs. Developing this concept further provides greater regulatory clarity and a pathway to manage the risks posed by PFAS and potentially other substances. Therefore, an approach to PMT addresses a regulatory gap between risk management of chemicals under UK REACH and objectives to protect water resources.

Applying the PMT concept

8. There are currently no globally agreed criteria to identify PMT-like substances. The EU has adopted criteria for use within their . Agreement has been given by the UN Sub-Committee of Experts on the Globally Harmonized System of Classification and Labelling of Chemicals (UN GHS Sub-Committee) to set up an informal working group to examine the state of the science in the context of the United Nations바카라 사이트� Globally Harmonised System of classification and labelling of chemicals (UN GHS). Further work is required before any possible agreement on inclusion into UN GHS can be proposed.

9. The EU바카라 사이트檚 criteria (see Annex A) have been established under EU CLP. The criteria have not been adopted into EU REACH legislation. However, concern over combined persistence and mobility (the PMT concept) has been used within the EU바카라 사이트檚 REACH restrictions proposals for PFAS, recognising that substances with properties of high persistence and mobility may present a risk that is not adequately controlled.

10. Similarly, development of the PMT concept as set out here, and its use to inform risk management actions in GB is beneficial. This is currently focused on PFAS risk management actions under UK REACH.

11. While the elements of persistence, mobility and toxicity are discussed below, it is the combination of these properties that informs on the level of potential concern. Whether this is realised as a risk in more localised environments will also depend upon other considerations such as

• geographic differences
• production volumes
• use pattern

12. These may be the most important influences when determining risk of environmental contamination in some cases. Substances may still be found during groundwater monitoring activities that are not considered PMT or vPvM. This is not a failure of the PMT concept but recognises that, all things being equal in terms of a chemical바카라 사이트檚 release and exposure, use of the PMT concept is a way to identify priority substances of concern for more detailed consideration and prioritisation of regulatory efforts, to further understand and address risks.

Persistence

13. Persistence is a measure of the resistance of a substance to degrade under environmental conditions. Criteria for identifying substances as persistent (P) or very persistent (vP) already exists within our regulatory framework (footnote 1) for chemicals. However, most registered substances only have screening level information on degradation so are data poor in relation to the P/vP criteria. The EU REACH Registration data base contains definitive environmental half-life data for approximately 5% of registered substances. This makes a full assessment of the impact of introducing new criteria for PMT uncertain currently.

14. PFAS as a class are internationally recognised as being extremely persistent, primarily because of the strength of the Carbon-Fluorine bond. The few environmental fate studies of PFAS conducted to internationally recognised test methods typically show negligible degradation. Therefore, realistic environmental transformation half-lives cannot be measured as they will exceed the length of the study by an unknown amount, likely to be far more than the vP half-life criteria in Annex 13 of UK REACH. Even where a PFAS can undergo primary degradation over a measurable time frame, the resulting oxidised degradation products are themselves persistent (known as arrowhead PFAS).

Mobility

15. Substances may have the potential to move through environmental compartments and breach natural barriers. In the case of the PMT concept, mobility aims to describe the particular concern associated with the movement of chemicals through the terrestrial environment to water bodies.

16. The EU CLP criteria to identify mobile substances uses the organic carbon adsorption coefficient (Koc) which provides an indication of the strength of retention in soils (footnote 2). For mobility, while the criteria may help initially identify substances of concern, , including the weight-of-evidence determination to assess all reliable and relevant information on mobility as a whole. This will help inform the use of PMT in regulation as Koc is too simplistic to determine the potential mobility of PFAS. The dominant retention mechanisms in soils are not yet well understood and vary depending on soil and PFAS properties. Nonetheless, Koc is a useful screening measure of mobility and is suitable for identifying many substances that may need additional assessment.

17. Monitoring programmes indicate that PFAS can travel far from their source of emission via water. Movement via air is not considered part of mobility as defined here but may also contribute to the long-range transport observed to remote areas. GB monitoring data of selected PFAS from water industry influents and effluents, indicate that they can pass through the solid sorbents that remove unwanted substances to varying degrees. Therefore, a conclusion of very mobile (vM) is warranted for certain sub-groups of PFAS, despite uncertainties around颅 the relevance of the (Koc) metric.

Toxicity

18. As with persistence, existing criteria for toxicity exists within our regulatory framework, such as those set out in Annex 13 of UK REACH that are used for PBT assessment.

19. Analyses by the Health and Safety Executive (HSE) in the 2023 concluded that while relevant toxicology data exists for a limited number of individual PFAS, there is limited evidence on the human health hazard for the majority. The Committee on Toxicity (COT) is currently , focusing on several critical endpoints, and considering the biological relevance of the endpoints assessed.

Risk management of PMT substances in the context of UK REACH restrictions

20. The combination of persistence and mobility is a cause for some concern. The benefit of applying the concept of PMT now is to provide a prioritisation tool for identifying substances for further assessment to guard against widespread continued and potentially irreversible contamination.

21. Given the extreme persistence and high mobility of PFAS (whether the substances themselves or their transformation products), quantitative risk assessment is not compatible with application of the precautionary principle. For PFAS, the PMT concept can be used within the preparation of a UK REACH restriction dossier to assess if they represent a risk that is not adequately controlled to human health, the environment, or both.

Threshold versus non-threshold approach to risk management

22. Risk management responses need to consider if PMT or vPvM substances should be treated as threshold or non-threshold concerns, as this will determine what actions may be required. This decision is not substance-specific but is determined by the regulatory need and context of the risk assessment being undertaken. In this case, that context is PFAS risk management under UK REACH. A threshold approach assumes there is an acceptable concentration, below which risks are assumed to be adequately controlled. A non-threshold approach assumes that it is too difficult or not possible to establish an acceptable concentration, and so emissions need to be minimised to be as low as possible. This helps to reduce environmental and human exposure.

23. PFAS can enter the environment from diverse sources and pathways. This introduces significant uncertainty into risk assessments. This uncertainty, which may also be the case for other PMT substances, makes it challenging to confidently predict the effectiveness of risk management measures in maintaining environmental levels below specific thresholds. By meeting the toxicity criteria testing may provide a determination of their hazards. However, there may be uncertainties in terms of interpreting these to determine overall risk to human health, that is from long-term relatively low environmental exposure. Likewise, due to their high levels of persistence, precaution is needed to minimise the risk that toxic thresholds may be breached in future. For PMT or vPvM substances there is also concern over difficulty in remediation supporting the use of a non-threshold approach as proportionate for generic risk assessment purposes. Therefore, based on their high persistence and high mobility potential, a non-threshold approach is an appropriate way to manage the risks. This can be justified when considering risk control measures concerned with placing on the market and use of PMT substances, such as PFAS, to control environmental emissions and reduce environmental and human exposure.

24. The use of a non-threshold approach to prevent emissions to the environment in general does not discount the possibility of determining thresholds relating to risk management interventions for other purposes.

25. Not all substances that may be persistent and mobile will have enough data to perform the 바카라 사이트榯oxicity바카라 사이트� assessment. Substances identified as vPvM, have even greater potential to contaminate the water environment and would be harder to remove than those with lower persistence and mobility that may be considered as PMT substances. In these cases, as the exposure route is plausible, and it would be highly regrettable if a substance were subsequently found to be T. In line with the precautionary principle this may justify the need for risk management measures despite the lack of toxicity data. The risk assessment and management of vPvM substances should be reviewed as further toxicity data is generated.

Conclusions and future work

26. The discussion above is based on the concept of PMT that has been developed over several years. The concept is now being used to guide determination of risk management action that may be taken in GB, starting with consideration of PFAS risks managed under UK REACH. Definitive criteria are not being formally adopted in UK REACH, or other legislation, as discussions are ongoing internationally, and knowledge and data are evolving.

27. The discussion has also been informed by application to the case of PFAS. The PMT (including vPvM) concept will apply to more substances than just PFAS but, in taking a case study approach, this provides a basis to support risk management on this high priority issue, such as providing justification to support preparation of UK REACH restriction dossiers on PFAS. Through application of the PMT concept in practice to address PFAS, this will provide an opportunity to learn and improve our regulation in relation to the PMT or vPvM concept for future application to other substances (or groups of substances). It will also provide a clearer understanding of factors required to inform potential future legislative changes that may be required, for example in UK REACH.

28. The ongoing development process will include discussion with international partners in the interests of global harmonisation and regulatory cooperation. The UK will continue to participate in UN GHS discussions on proposed new hazard issues (which includes PMT as the EU has implemented this into EU CLP as new hazard classes). If criteria are defined within UN GHS, the UK will still have to consider implementation in GB CLP.

29. Some limitations in our current understanding of the number of substances that may be considered a risk due to combined persistence, mobility and toxicity are described above. Three areas have been identified where further research would contribute to the development of the criteria and their use for risk management of chemicals. These are developing a:

a. new method to define the inherent mobility of any substance accounting for both intrinsic substance and extrinsic environmental properties

b.聽聽screening tool to aid prioritisation at registration that accounts for hazard and different exposure scenarios.

c.聽聽monitoring programme to target persistent and mobile substances

30. To begin addressing these identified gaps, the Environment Agency will undertake a research project to develop a refined screening assessment, that can be used in parallel or sequentially with current methods. The data collected:

• will help to prioritise substances in the short term
• could be used to develop a new internationally accepted test guideline in the Organization for Economic Cooperation and Development (OECD) Test Guideline Programme
• will help to refine current exposure and risk assessment modelling tools in the medium term
• will lead to development of predictive screening tools in the long term

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Annex A: EU바카라 사이트檚 CLP criteria for classification of PMT and vPvM

The below criteria are taken from the as regards hazard classes and criteria for the classification, labelling and packaging of substances and mixtures.

4.4. Persistent, Mobile, and Toxic or Very Persistent, Very Mobile properties

4.4.1. Definitions and general considerations

4.4.1.1. For the purposes of Section 4.4 the following definitions shall apply: 바카라 사이트�PMT바카라 사이트� means a persistent, mobile, and toxic substance or mixture that meets the classification criteria set out in Section 4.4.2.1.

바카라 사이트�vPvM바카라 사이트� means a very persistent and very mobile substance or mixture that meets the classification criteria set out in Section 4.4.2.2.

바카라 사이트渓og Koc바카라 사이트� means the common logarithm of the organic carbon-water partition coefficient (i.e. Koc).

4.4.1.2 The hazard class Persistent, Mobile, and Toxic or Very Persistent, Very Mobile properties is differentiated into:

• PMT properties
• vPvM properties

4.4.2. Classification criteria for substances

4.4.2.1. Classification criteria for PMT

A substance shall be considered a PMT substance when it fulfils the persistence, mobility and toxicity criteria set out in Sections 4.4.2.1.1, 4.4.2.1.2 and 4.4.2.1.3. and assessed according to Section 4.4.2.3.

4.4.2.1.1. Persistence

A substance shall be considered to fulfil the persistence criteria (P) in any of the following situations: (a) the degradation half-life in marine water is higher than 60 days; (b) the degradation half-life in fresh or estuarine water is higher than 40 days; (c) the degradation half-life in marine sediment is higher than 180 days; (d) the degradation half-life in fresh or estuarine water sediment is higher than 120 days; (e) the degradation half-life in soil is higher than 120 days.

4.4.2.1.2. Mobility

A substance shall be considered to fulfil the mobility criteria (M) when the log Koc is less than 3. For an ionisable substance, the mobility criteria shall be considered fulfilled when the lowest log Koc value for pH between 4 and 9 is less than 3.

4.4.2.1.3. Toxicity

A substance shall be considered to fulfil the toxicity criteria (T) in any of the following situations: (a) the long-term no-observed effect concentration (NOEC) or ECx (e.g. EC10) for marine or freshwater organisms is less than 0,01 mg/l; (b) the substance meets the criteria for classification as carcinogenic (category 1A or 1B), germ cell mutagenic (category 1A or 1B), or toxic for reproduction (category 1A, 1B, or 2) according to Sections 3.5, 3.6 or 3.7; (c) there is other evidence of chronic toxicity, as identified by the substance meeting the criteria for classification as specific target organ toxicity after repeated exposure (STOT RE category 1 or 2) according to Section 3.9; (d) the substance meets the criteria for classification as endocrine disruptor (category 1) for human health or the environment according to Sections 3.11 or 4.2.

4.4.2.2. Classification criteria for vPvM

A substance shall be considered a vPvM substance when it fulfils the persistence and mobility criteria set out in Sections 4.4.2.2.1 and 4.4.2.2.2 and assessed according to Section 4.4.2.3.

4.4.2.2.1. Persistence

A substance shall be considered to fulfil the 바카라 사이트渧ery persistent바카라 사이트� criteria (vP) in any of the following situations: (a) the degradation half-life in marine, fresh or estuarine water is higher than 60 days; (b) the degradation half-life in marine, fresh or estuarine water sediment is higher than 180 days; (c) the degradation half-life in soil is higher than 180 days.

4.4.2.2.2. Mobility

A substance shall be considered to fulfil the 바카라 사이트渧ery mobile바카라 사이트� criteria (vM) when the log Koc is less than 2. For an ionisable substance, the mobility criteria shall be considered fulfilled when the lowest log Koc value for pH between 4 and 9 is less than 2.

Footnotes

1: A substance shall be considered to fulfil the persistence criteria (P) in any of the following situations: (a) the degradation half-life in marine water is higher than 60 days; (b) the degradation half-life in fresh or estuarine water is higher than 40 days; (c) the degradation half-life in marine sediment is higher than 180 days; (d) the degradation half-life in fresh or estuarine water sediment is higher than 120 days; (e) the degradation half-life in soil is higher than 120 days.

A substance shall be considered to fulfil the 바카라 사이트渧ery persistent바카라 사이트� criteria (vP) in any of the following situations: (a) the degradation half-life in marine, fresh or estuarine water is higher than 60 days; (b) the degradation half-life in marine, fresh or estuarine water sediment is higher than 180 days; (c) the degradation half-life in soil is higher than 180 days.

2: Within EU CLP criteria, a substance shall be considered to fulfil the mobility criteria (M) when the log Koc is less than 3. For an ionisable substance, the mobility criteria shall be considered fulfilled when the lowest log Koc value for pH between 4 and 9 is less than 3.

A substance shall be considered to fulfil the 바카라 사이트渧ery mobile바카라 사이트� criteria (vM) when the log Koc is less than 2. For an ionisable substance, the mobility criteria shall be considered fulfilled when the lowest log Koc value for pH between 4 and 9 is less than 2.