EXCLUSIVE: Water firm finds high levels of toxic chemicals in rivers and wastewater

High concentrations of toxic PFAS chemicals linked to a wide range of diseases, including two cancers, have been found in treated wastewater which is discharged into rivers in Scotland, but Scottish Water has yet to reveal the locations of the problem hotspots.

Some rivers and treated wastewater discharges in Scotland were found to contain high levels of PFAS. Photograph: David Cation Photography/Getty Images

Known collectively as PFAS (per- and polyfluoroalkyl substances) - a family of around 4,700 manmade ‘forever chemicals’ that do not break down in the environment - they have been associated with high cholesterol, ulcerative colitis, thyroid disease, testicular cancer, kidney cancer, pregnancy-induced hypertension, miscarriage, endocrine disruption, reduced birthweight, reduced sperm quality, delayed puberty, early menopause, and reduced immune response to tetanus vaccination.

As part of a multi-year, UK-wide Chemicals Investigation Programme (CIP), Scottish Water sampled the crude sewage, treated effluent and the water in the rivers that received the effluent discharge at 20 wastewater treatment plants for 24 months between 2015 and 2017 for a range of chemicals, including two restricted PFAS substances - PFOS and PFOA.

According to Scottish Water data, obtained by ENDS, the firm found concentrations of perfluorooctane sulfonic acid (PFOS) as high as 394 nanograms per litre in the effluent of one treatment works and 97.5ng/l at another. River water sampled downstream from one of the works showed concentrations of PFOS at 20.2ng/l. Perfluorooctanoic acid (PFOA) was found at 21.6ng/l at its highest in effluent. 

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In drinking water, which was not tested as part of the CIP, a reading of 10ng/l should trigger consultation with health professionals, according to the Drinking Water Inspectorate for England and Wales. The Scottish Drinking Water Quality Regulator (DWQR) has set health-based guidance action values for PFOS at 1000ng/l and PFOA at 5000ng/l in drinking water and has advised water companies to monitor PFOS and PFOA in supply zones where their concentrations exceed 300ng/l.

A revised Drinking Water Directive, adopted in December by the European Parliament, has gone further still, putting the maximum acceptable level at 100ng/l for the sum of 20 PFAS of concern and 500ng/l for PFAS Total, which covers all PFAS substances. The directive entered into force in January and member states have two years to transpose it. Having left the bloc, DEFRA said it “would consider the effect of the changes made to the directive” but made no commitment to adopt it. Instead, it said it would address the issue as part of its Chemicals Strategy, which has been repeatedly delayed. A call for evidence is due this year.

Scottish Water anonymised the locations of the sampling site data provided to ENDS almost a month after the information was requested. It declined to provide the locations when requested again, instead inviting ENDS to submit a fresh request under Environmental Information Regulations, which will take at least another 20 working days.

Dr Cecilia Macleod from the University of Greenwich who is researching PFAS contamination in the UK said the firm was anonymising the data “in order to try to prevent causing concern among communities” but that in doing so it would “cause concern that they are hiding something”. 

The sentiment is shared by Dr Kerry Dinsmore from environmental charity FIDRA who said it was not acceptable to keep the data hidden. “The data should all be visible,” she said, so that other research projects could benefit from the knowledge. “It’s collected with public money and should be publicly available.”

Similar research data collected from the CIP in England and Wales was made available by water sector research body UKWIR last year, which showed PFAS spikes in a range of locations which were not anonymised.  

Scottish Water says it monitors its water sources and reviews the summary of test results and risk assessments. It said its “view is that if there is no PFOA in our source waters then there is going to be nothing in our supplied potable water as all the risk would come at the front end raw water and not from the treatment process,” but it did not mention PFOS.

“There are ongoing projects in raw water and catchment assessments for PFOA, but there is no regulatory requirement for testing to be carried out,” it noted.

It added: “Scottish Water has a duty to determine the risk of PFOA at each of their systems as part of Scottish Water Drinking Water Safety Plans. If the risk assessment shows that there is reasonable grounds to believe that there may be PFOA in the drinking water supply, Scottish Water will carry out sampling in accordance with regulation 10 of the Public Water Supplies (Scotland) Regulations  2014.”