27th September 2026
Reports of contamination by so-called "forever chemicals" in parts of England are raising questions about how much is known about these persistent substances in Scotland.
The issue has become particularly prominent in parts of Lancashire and Cumbria, where investigations have found PFAS contamination in rivers, groundwater and land.
PFAS, or per- and polyfluoroalkyl substances, are a large family of chemicals that have been used for decades because they are highly resistant to water, grease, stains and heat. They have found their way into many everyday and industrial products, including textiles, food packaging, paints, plastics and firefighting foams.
Their persistence is the reason they have become known as "forever chemicals". Some can remain in the environment for very long periods and can accumulate in living organisms.
Recent investigations in Cumbria and Lancashire have found elevated concentrations of PFOS, one of the best-known PFAS chemicals, at a number of locations. Environment Agency sampling has identified particularly high concentrations in some rivers and groundwater, while investigations have also raised concerns about private water supplies.
In Lancashire, historic industrial contamination around Thornton-Cleveleys has also brought attention to PFOA, another PFAS chemical. Environmental investigations have included testing soil and locally grown food, with restrictions placed on some allotment sites while the situation is investigated.
These cases do not mean that every place where PFAS are detected is dangerous. Concentration, the particular chemical involved and the length and route of exposure all matter.
But they demonstrate why environmental agencies are increasingly looking for PFAS rather than waiting for contamination to become obvious.
Scotland begins a much wider search
SEPA significantly expanded its PFAS monitoring programme in 2025.
The first Scottish scoping exercise examined 97 surface-water locations and 37 groundwater locations, testing for 29 different PFAS substances.
At least one PFAS was detected at 86 of the 97 surface-water sites, or 89 per cent. PFAS were also detected at 21 of the 37 groundwater sites, or 57 per cent.
At first sight those figures sound alarming.
However, detection does not mean that the water is unsafe.
SEPA found that concentrations in Scotland were generally lower than those reported by the Environment Agency in England. None of the PFOS results exceeded the maximum allowable concentration environmental standard used in the assessment, and no groundwater site exceeded the 100 nanograms per litre standard based on the combined concentration of 20 PFAS substances.
The Scottish results therefore do not show widespread contamination at levels exceeding the relevant standards.
But the survey was never intended to be the final word.
SEPA describes it as an initial scoping study designed to establish where PFAS occur and where further monitoring should be concentrated.
Where were the higher levels found?
One of the most interesting findings is that the higher PFOS concentrations were generally associated with watercourses close to activities where PFAS may historically have been used.
SEPA's monitoring strategy specifically considered airports, military sites, fire stations and fire-training facilities, wastewater treatment works, landfills and several industrial sectors.
The results broadly supported that approach.
The highest PFOS concentration recorded in surface water was 542 nanograms per litre in the Mains of Dyce Burn downstream of the Aberdeen Airport fire-training ground.
Other relatively high readings were found at the Covesea Burn near Lossiemouth and at watercourses associated with landfill sites.
These results do not mean that airports or landfill sites are automatically contaminated. Rather, they demonstrate why locations with particular histories or potential sources of PFAS deserve closer investigation.
What about Caithness?
This is where the Scottish results become particularly relevant to the far north.
Caithness has a mixture of rural land, rivers, groundwater, airports, historic industrial activity, waste facilities and a long coastline.
Some of those characteristics are similar to the types of locations being investigated elsewhere in Britain.
However, the published 2025 SEPA report does not provide a simple list of all 97 surface-water and 37 groundwater sampling locations.
Consequently, the report alone does not establish whether particular Caithness locations such as the River Wick, River Thurso or other local watercourses were included in the 2025 PFAS programme.
Nor does the report provide evidence that Caithness has a PFAS contamination problem.
That distinction is important.
A location not appearing in the published list is not evidence that PFAS are present there, just as it is not evidence that they are absent.
It simply means that the available report does not provide enough information to draw that conclusion.
And there is an important coastal gap
There is another limitation which is particularly significant for a coastal area such as Caithness.
SEPA states that marine waters were not sampled as part of the 2025 programme.
The agency says it was not possible to sample marine waters during this stage of the work and that sites with emissions to marine waters were therefore excluded.
That leaves an obvious area for future investigation.
Caithness has a substantial coastline, fishing activity, shellfish and other marine life, as well as numerous rivers flowing towards the sea.
The first Scottish PFAS survey therefore provides useful information about parts of the freshwater environment and groundwater, but it does not answer questions about PFAS concentrations in the surrounding marine environment.
It also does not, by itself, establish what levels might occur in locally produced fish, shellfish, livestock or home-grown food.
Again, this should not be interpreted as evidence that such contamination exists.
It is simply an important gap in the first round of monitoring.
Dounreay and historic industrial activity
Dounreay is inevitably relevant whenever environmental monitoring in Caithness is discussed because of its long industrial history.
SEPA's PFAS methodology specifically included historic use of PFAS-based firefighting foams as one factor when selecting sites for investigation.
However, the 2025 PFAS report does not identify Dounreay as one of the locations producing the highest PFOS results.
There is therefore no evidence in this report that Dounreay has a PFAS problem.
The wider lesson is that historic industrial sites can require different types of environmental monitoring over many decades. PFAS are only one of a large number of substances that can potentially be relevant.
Detection does not mean danger
There is a useful distinction in all this which can easily get lost when the term "forever chemicals" is used.
Modern laboratory techniques can detect extraordinarily small quantities of chemicals.
SEPA's new monitoring programme is sensitive enough to detect PFAS at concentrations measured in fractions of a nanogram per litre for some substances.
Finding a chemical at a very low concentration does not automatically mean that drinking the water, eating locally produced food or catching fish from the area represents a health risk.
That requires an assessment of the particular chemical, its concentration, the route and duration of exposure and the relevant health or environmental standards.
At the same time, the absence of a test result does not prove that a substance is absent.
That is why monitoring programmes matter.
The Scottish investigation is only beginning
SEPA's 2025 work is best understood as the beginning of a much wider investigation rather than a final assessment of Scotland's PFAS problem.
The agency says the monitoring programme is being expanded, with around 500 samples planned for 2026 compared with 283 in 2025.
The intention is to build a much better picture of where PFAS occur and to identify locations where more detailed investigation may be necessary.
For Caithness, the interesting question is therefore not whether the area should be alarmed about "forever chemicals".
It is whether the next stage of Scottish monitoring will provide enough information to establish what is happening in the rivers, groundwater and coastal environment of the far north.
There is no evidence from SEPA's first Scottish survey to suggest a widespread PFAS crisis in Caithness.
But there is also a clear case for continuing to build the evidence.
The experience in England shows why.
Once persistent chemicals have entered the environment, finding out where they came from and how widely they have spread can become considerably more difficult than preventing or detecting the problem in the first place.
For a region with a long industrial history, a large rural area, private water supplies and an important marine environment, knowing what is in the water is likely to become an increasingly important part of environmental protection.
SEPA PFAS 2025 water quality monitoring