Taking into account the latest toxicological research, the USEPA proposes provisional health advisories for PFOA and PFOS of 0.4 and 0.2 micrograms per litre respectively. The figures are designed to protect the population against short-term exposure, taking as a worst case scenario a 10 kilogram child consuming a litre of water a day.
The Drinking Water Inspectorate set tiered action levels for the chemicals in UK supplies in June 2007 (ENDS Report 389, pp 25 ). Tier 1 levels were effectively just reporting limits, but levels in excess of tier 2 were judged likely to be unwholesome and constitute a potential danger to health. Tier 2 limits for the PFOA and PFOS were 10µg/l and 1µg/l respectively.
The EPA figures suggest the UK levels need to be reviewed. The DWI’s levels were based on provisional tolerable daily intakes (TDIs) set by the government’s Committee on Toxicity (CoT) in 2006 (ENDS Report 383, p 23 ). In July last year the European Food Safety Authority set TDIs for the two compounds at half the levels set by the CoT (ENDS Report 403, p 20 ).