Little is known about residues of perfluorinated chemicals in the UK environment. The compounds have been widely used in applications such as fire fighting foams, non-stick coatings and stain proofing treatments. Their residues are extremely persistent, potentially toxic and take years to be eliminated from the body.
The most common residues are perfluorooctane sulphonate (PFOS) and perfluorooctanoic acid (PFOA). Concerns about human exposure to PFOS via food emerged recently following a Food Standards Agency survey (ENDS Report 380, pp 5-6 ).
University of Bonn researchers recently reported a cocktail of perfluorinated chemicals in the river Ruhr, close to western Germany’s industrial heartland.1 The river is used as a source of drinking water by 23 water works serving 5 million people. Significant contamination was found in water supplies for 13 towns.
The contamination was tracked to the river’s headwaters and its tributary the Moehne. Surprisingly, the source was agricultural land near the town of Arnsberg, 50 kilometres west of Dortmund.
The land had been used for the authorised spreading of mixed organic and inorganic wastes. Up to 0.7 milligrams per kilogram of perfluorinated compounds were found in the soil. A nearby stream contained up to 43 micrograms per litre, including 34µg/l of PFOA and 3µg/l of PFOS. Five other perfluorinated compounds were detected.
Levels in drinking water were lower. The highest was 0.6µg/l, most of which was PFOA. Levels in Dortmund were over 0.2µg/l.
In the UK, there have been few surveys of perfluorinated compounds in waters. Potential sources include industrial discharges and waste activities.
There were also fears that drinking water might have been contaminated with PFOS following the Buncefield fuel storage fire in December 2005 (ENDS Report 375, pp 6-7 ). Levels of 1µg/l were reported in groundwater, but the Agency has not detected PFOS contamination off-site.
Provisional tolerable intakes for PFOS and PFOA were recently set at 0.3µg and 3µg per kilogram bodyweight per day respectively by the government’s expert advisory body the Committee on Toxicity (ENDS Report 383, p 23 ). This suggests drinking water limits of 0.9µg/l for PFOS and 9µg/l for PFOA, allowing for 10% of intakes to come from drinking water and consumption of 2l per head per day.
The German pollution incident did not breach these limits but few water suppliers or their customers are likely to be happy with these contamination levels.
The researchers concluded that drinking water treatment processes did not remove perfluorinated compounds effectively. Even activated carbon filtration, which is effective against most trace organic compounds, appeared to have had no effect.
The Drinking Water Inspectorate said it was not aware that perfluorinated compounds had contaminated drinking water but had commissioned a WRC study to be completed before the end of 2007.
The DWI admitted it had received one formal notification of PFOS in untreated water but drinking water was not affected.
"Any comments on potential [PFOS or PFOA] contamination would be purely speculative at this time," it concluded.