Older PFAS decline in English rivers as replacement chemicals emerge
Concentrations of two long-used PFAS chemicals have fallen in English rivers, alongside detection of substances used to replace them. PFOS fell by about 30 per cent and PFOA by about 29 per cent over the monitoring period. The wider chemical group remains under investigation as European policymakers consider broader restrictions.
Science··Morning
Two long-used chemicals fall in river monitoring
Concentrations of two long-used per- and polyfluoroalkyl substances, known as PFAS, have declined in English rivers. England’s Environment Agency reports falls of roughly 30 per cent for perfluorooctanesulfonic acid, or PFOS, and about 29 per cent for perfluorooctanoic acid, or PFOA. Monitoring at long-running locations covers 2016 to 2025. These persistent substances were used in non-stick coatings, industrial processes and firefighting foams.[1], [2]
Under the Stockholm Convention, PFOS restrictions began in 2009 and PFOA restrictions in 2019. Country-specific qualifications applied. The UK ban on PFOA in firefighting foam took effect in 2025. Agency chief scientist Rob Bradburne views international restrictions positively, while warning that the number and variety of PFAS complicate the problem.[2]
Replacement compounds appear in water
Short-chain PFAS and fluorotelomer compounds used as replacements are now detectable in England’s environment. The wider group contains around 10,000 chemicals, used in products ranging from cosmetics to industrial lubricants. Many remain comparatively understudied. Trifluoroacetic acid, or TFA, can arise as pesticides, refrigerants and medicines break down; the agency found it widely distributed in England.[2]
Agency monitoring extends to more than 60 PFAS in rivers, lakes, estuaries, coastal water, groundwater, fish and shellfish. Short-chain substances can dominate water samples, whereas longer-chain compounds more readily accumulate in wildlife. River levels tend to peak in summer. Histories for many newly monitored compounds are still too short to determine a lasting upward trend. TFA requires a separate, specialised measurement method.[1]
Broader restrictions remain under consideration
The European Union is considering a ban covering the PFAS group, aiming to avoid replacement of a prohibited chemical by another persistent member. The UK government says it is following the process but has set no timetable for a similar policy. PFOS concentrations still often exceed the UK and EU environmental quality threshold. England currently has an individual PFAS standard for PFOS alone; additional standards are being developed.[2]
