PFAS0113
Written evidence submitted by Dr Emily O’Rourke and Dr Elizabeth Chadwick, Cardiff University Otter Project
Addressing the risks from Perfluoroalkyl and Polyfluoroalkyl Substances
Dr Elizabeth Chadwick is the Principal Investigator for the Cardiff University Otter Project (CUOP). Dr Emily O’Rourke is a postdoctoral researcher in CUOP. The project uses a biobank of tissues (from otters found dead) to research changes in the environment, particularly in chemical pollution.
Dr Chadwick represents CUOP on the WILDCOMS (Wildlife disease and contaminant monitoring and surveillance) network, and sits on a number of relevant Working Groups including the Welsh Government Emerging Threats to Waters group, and the PFAS subgroup, as well as the Emerging Risks group of Defra’s H4 Indicator programme (which includes PFAS in its’ remit).
Dr Emily O’Rourke gained her PhD at Cardiff University, entitled: Eurasian otters (Lutra lutra) as sentinels of persistent, bioaccumulative and toxic contaminants: investigating drivers of pollution, time trends and biomagnification in freshwater ecosystems. Two of the peer reviewed papers referred to in this written evidence arose from this body of research. Dr O’Rourke also sits on the WG Emerging Threats to Waters group, and the PFAS subgroup.
Our response focuses primarily on challenges relating to monitoring, and highlights some of the inadequacies and inconsistencies in current monitoring, while evidencing relevant information arising from our research on PFAS in otters. We touch on regulation where this is pertinent to monitoring.
Background (Q1: benefits, and usage)
PFAS are widely used for their oil-, water-, and heat-resistant properties, making them valuable in products ranging from food packaging and textiles to firefighting foams and industrial processes. These uses create numerous pathways for PFAS to enter the environment, through emissions during production, use, and disposal. As a result, PFAS contamination is now globally widespread and persistent across ecosystems.
Current monitoring and regulation (Q2, 6, 9)
Current monitoring and regulatory frameworks in the UK are insufficient to capture the full scope of PFAS environmental contamination.
Environmental Quality Standards
- Environmental Quality Standards (EQS) are specific quantifiable limits set for pollutants in air, water, or soil. They are designed with the aim of preventing harm to ecosystems and human health, and were established under the Water Framework Directive (WFD)
- PFOS is the only PFAS with Environmental Quality Standards (EQS) for surface water and biota.
- No EQSs exist for the thousands of other PFAS compounds in use, many of which continue to enter the environment through poorly controlled pathways.
Routine monitoring by government agencies typically focuses on a small number of legacy compounds (typically PFOS and PFOA) measured in water, with more limited monitoring in fish (to satisfy WFD requirements for EQS in biota). It is likely that the lack of breadth in regulation directly impacts resource allocation to monitoring. Monitoring of PFASs in water, and in fish, presents significant limitations. Otters, which eat fish and can accumulate pollutants from that food chain, present a valuable alternative which is increasingly being recognised but is not part of routine monitoring.
Monitoring in water
- PFASs are hydrophobic, i.e. they tend to repel water (and instead may be adsorbed onto sediments or other suspended solids in water). This makes it difficult to extract and analyse them in water samples.
- Variable flow rates in rivers means that dilution is highly variable. Typically, PFASs are present at very low concentrations, which can vary substantially over time due both to episodic inputs, and variable river flow. This makes meaningful comparison of concentrations (e.g. between locations, or time points) difficult, and necessitates a very large number of samples to smooth variation.
- Laboratory methods all have thresholds below which chemicals cannot be detected (LOD, limit of detection) or accurately measured (LOQ, limit of quantification). Many PFASs are typically below these thresholds in water samples, which are therefore erroneously considered ‘clean’ unless comparisons are made with co-located biota samples (in which PFAS become concentrated, and are more readily detected).
- Monitoring in water focuses on PFOS and PFOA, which are found at the highest concentrations in the environment, and are thus more readily detectable than other PFASs. However, differing usage patterns, environmental pathways and toxicities between PFASs means that concentrations of PFOS and PFOA in water may not be accurate predictors of the presence, concentration or risks from other PFASs.
Monitoring using fish
- Because PFASs bioaccumulate, concentrations in fish are higher than those in water. This means that concentrations are more likely to exceed measurement thresholds (LOD and LOQ) and therefore allow quantification.
- Monitoring using biota provides more information on PFASs that are bioavailable (i.e. can be absorbed by the body and potentially have an effect), which is of greater relevance to health risks than water monitoring.
- Monitoring using fish is constrained by the need for destructive sampling of populations. Where required species are absent, or populations are vulnerable, this brings significant practical and ethical considerations which restrict the potential for fish sampling in the UK. For example in Wales, fish sampling (which in the past focused on trout) is no longer routinely possible.
- Differences in species distributions mean that it is not possible to use the same fish species everywhere, making direct comparisons difficult.
Monitoring using otters: approach
Otters offer a powerful complementary tool for PFAS monitoring1,2,3. As top predators in freshwater ecosystems, they bioaccumulate a wide range of PFASs over time, making them effective sentinels for assessing environmental exposure.
- Otters can be collected non-invasively, for example following road deaths, enabling ethically sound access to tissue samples such as liver, where PFASs accumulate. At present, ca. 250 otters are found dead each year in England and Wales, thus avoiding ethical issues associated with destructive biota sampling.
- By analysing archived otter tissues from a 30+ year biobank, collected by the Cardiff University Otter Project (CUOP), we track chemical presence, temporal trends, and spatial variation across the UK. Collaborative partnerships across Europe support similar research elsewhere (e.g.2).
- Chemicals that bioaccumulate are at higher concentration in otters than in either fish or water (because they are at the top of the food chain) therefore PFASs present at very low concentrations (undetectable in other samples) can be detected in otter tissues.
- Otters range over many kilometres, acting as ‘repeat samplers’ within aquatic ecosystems. This smooths short term variation (e.g. with river flow) and therefore far fewer samples are required to detect pollution trends and differences between catchments.
- Comparative analysis with water and fish sampling can provide information on the bioavailability, bioaccumulation, and potential biomagnification of PFASs, helping to link environmental contamination to potential ecological effects.
- Comparative analysis with health indices recorded during post mortem provides a potential mechanism to monitor impacts in mammals, although the nature of sample collection limits the utility of this.
Monitoring using otters: key findings
- We have quantified widespread PFAS contamination in otters from across England, Wales1 and Northern Europe2, with PFAS detected in every otter analysed.
- Analyses have quantified 33 different PFAS compounds3 including both legacy substances like PFOS and PFOA, and replacement compounds such as F53-B and PFECHS1,2,3.
- Comparison with samples from other taxa suggests highest concentrations in freshwater ecosystems, with levels in otters exceeding those observed in marine and terrestrial species2. This reflects the dominant pathway for PFAS entry into the environment – via contaminated water.
- Despite being phased out of use, and listed on the Stockholm Convention in 2009, PFOS still dominates the PFAS profile of top predators due to its extreme persistence2,3.
- Spatial analysis of PFAS concentrations in otters has linked elevated levels to specific sources. Wastewater treatment effluent and sewage sludge application have been identified as key sources of PFAS to freshwaters1. These findings highlight the limitations of existing water treatment infrastructure in removing modern synthetic chemicals, and the contamination issues around using sewage sludge as a fertiliser.
- Concentrations in otters also identified elevated PFOA concentrations downwind of a factory producing PTFE1, which was shown to persist long after the factory ceased using PFOA3. Elevated concentrations were measured hundreds of kilometres downwind, across several river catchments, highlighting that PFAS pollution is not only reflective of wastewater.
Our findings confirm that PFASs are not only widespread but continue to persist long after regulatory action has been taken. Continued biomonitoring is essential, to understand spatial and temporal variation associations with historic sources.
Limitations
- Top predator monitoring is not mandated by legislation, making it particularly vulnerable to omission during funding cuts or policy changes.
- Continuation of collection and post mortem, and maintenance of the biobank of samples is reliant on research leads at Cardiff University maintaining grant income, which is typically short-term (one or three year funding cycles are typical).
- Chemical analysis is also reliant on grant funding, and subject to the same challenges. Short term research projects can result in fragmented datasets.
- Analysis at different laboratories or with differing sample selection criteria can impact comparability of datasets. Where funding for monitoring is focused within the devolved nations, this can hamper broader, UK-level interpretation.
- Chemical analysis is currently restricted to ~40 compounds, representing only a tiny fraction of the thousands in circulation. Expanding this suite is hindered by limited funding and difficulties obtaining analytical standards due to industry confidentiality.
Is a precautionary approach needed? (Q.10)
The continued environmental presence of PFOS in predator samples decades after its ban, alongside growing detection of unregulated replacement PFASs (e.g. F53-B and PFECHS in otter tissues from England3), underscores the regulatory lag, and highlights the urgent need for precautionary, group-based regulatory approaches rather than compound-by-compound assessments.
Divergence in monitoring approaches in the UK (Q.11)
England
- In England, a broader approach to PFAS surveillance was initiated as part of the H4 Indicator programme4.
- The H4 indicator aimed to measure priority chemicals (persistent, bioaccumulative and toxic (PBT) substances, heavy metals and pesticides/biocides), in samples from different compartments of terrestrial, freshwater and marine systems, as outcome indicators supporting the 25 Year Environment Plan.
- Freshwater monitoring included water, fish and otters. Access to biobanked otter tissue samples allowed retrospective analysis, to determine trends.
- Initial reporting (in 20215) was restricted to PFOS, but this was subsequently expanded to encompass a wide range of forty PFASs in biota samples in 20246.
- Unfortunately, funding for the H4 Indicator programme has not been renewed in 2025 (although otter sampling has been funded for 2025-2026).
Wales, Scotland
- Neither Wales or Scotland have a programme for monitoring PFAS in predator samples.
- In Wales, Natural Resources Wales have been working to develop methods using passive samplers (which have membranes which chemicals can adhere to, and are deployed in water for several weeks). So far, passive sampling methods have not detected PFAS in water samples. Much more research is needed to illustrate their efficacy for monitoring.
- Reliance on water sampling (and therefore a focus on PFOS only) severely limits understanding.
- As far as we are aware, there is no information about the wider range of PFASs present, the concentrations at which they are found, or their ubiquity in ecosystems in either Wales or Scotland.
Inconsistencies in approach lead to inconsistent and fragmented national monitoring coverage within the UK.
- Understanding spatial patterns in PFAS pollution are hampered by arbitrary national boundaries, which are of no environmental relevance to air-borne pollutants, or water-borne pollutants where river catchments span national boundaries.
- Prevailing west to east air movements mean that Wales may contribute to downwind pollution in England – but although data are available to describe a range of PFAS in England, no equivalent data exist for Wales.
- Analysis funded by and for devolved agencies typically uses different laboratories, which have differing methods and analytical standards, further hampering comparison and interpretation of this cross-border pollution issue.
Learning from other countries (Q13)
International examples provide valuable insights into how PFAS monitoring could be improved in the UK.
Biobanking
- Environmental specimen banks (ESBs) are organisations or facilities that collect, preserve and store environmental specimens7.
- Samples are securely stored, and can be retrospectively tested for contaminants when, for example, new methods are developed, new threats perceived, or funding becomes available. Such infrastructure allows rapid assessment of new contaminants, and evaluation of policy effectiveness, as need arises.
- The German Environmental Specimen Bank was established in the late 1970s, and routinely collects environmental and human samples which provide a scientific basic for the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU) to protect the environment, and monitor the efficacy of action8.
- In the UK, a variety of specimens are collected, by a wide range of organisations including universities, museums, and environmental organisations. Some work collaboratively to share resources and expertise where possible, e.g. Cardiff University Otter Project is part of the WILDCOMS network9. However, we lack of a centrally coordinated environmental specimen bank.
Analytical methods
- Several European countries are advancing non-target screening methods using high-resolution mass spectrometry, which can detect a broader array of known and unknown PFASs without needing specific standards for each compound. This is particularly important given the thousands of PFAS in circulation, and the limitations imposed on monitoring by industry confidentiality.
- UK Research and Innovation (UKRI) funding via NERC (Natural Environment Research Council) identified the threat of PFASs in the environment as one of five key environmental challenges in 202410, and highlighted the need for more advanced analytical capability as part of the call for applications. Funding decisions are pending (June 2025) and successful applicants are expected to optimise and combine methods to detect PFAS sources, precursors and degradation products in the environment. It is hoped that this will lead to a significant advance in capabilities.
Regulation
- The EU is taking a more proactive regulatory approach by pursuing a group-wide PFAS restriction under REACH, and updating the Surface Water and Groundwater Watch Lists to include 20 priority PFASs.
- The UK does not currently operate an equivalent Watch List mechanism, nor has it matched the EU’s ambition in regulating PFASs as a class.
- Greater alignment with European initiatives could improve the UK’s ability to track emerging threats and respond to scientific evidence more effectively.
May 2025
References
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