Yesterday, ENDS reported that data obtained from Scottish Water showed that high concentrations of toxic per- and polyfluoroalkyl substances (PFAS) chemicals, which have been linked to a wide range of diseases, including two cancers, had been found in treated wastewater which is discharged into rivers.
Following a 24-month period of monitoring 20 treatment works between 2015 and 2017, 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.
Scottish Water initially withheld the locations of the wastewater treatment works but later released them to ENDS, revealing that a plant in Livingston in West Lothian had the highest concentrations of PFAS in its effluent, followed by a works in Newbridge near Edinburgh and one in Dalmarnock in Glasgow.
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The sampling formed part of a multi-year, nationwide Chemicals Investigation Programme (CIP2). In England the sampling was undertaken by water sector research body, UKWIR.
Last year, ENDS revealed that UKWIR had recorded levels of PFOS as high as 53,000ng/l in effluent discharged from a wastewater treatment works in Duxford, South Cambridgeshire. Samples downstream of the works showed lower concentrations of the chemical as it would have had time to disperse in the river, but these levels still reached up to 130ng/L. The environmental quality standard for PFOS in surface water is 650ng/l.
Drinking water standards are tougher but vary wildly depending on the regulator. A reading of 10ng/l should trigger consultation with health professionals, according to the Drinking Water Inspectorate for England and Wales, but 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. The revised EU Drinking Water Directive is the strictest, 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.
Scottish Water told ENDS that there are “ongoing projects in raw water and catchment assessments for PFOA” but there is no regulatory requirement for testing to be carried out”. The same is true for England’s water firms. In both nations, water firms must risk-assess their catchments to deduce whether there might be a risk to drinking water and if a risk presents itself then only at that point would a water firm test drinking water.
Scottish Water 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.