Occurrence of perfluorinated compounds (PFCs) in drinking water of North Rhine-Westphalia, Germany and new approach to assess drinking water contamination by shorter-chained C4-C7 PFCs.

After detection of perfluorooctanoate (PFOA) in drinking water at concentrations up to 0.64 microg/l in Arnsberg, Sauerland, Germany, the German Drinking Water Commission (TWK) assessed perfluorinated compounds (PFCs) in drinking water and set for the first time worldwide in June 2006 a health-based guide value for safe lifelong exposure at 0.3 microg/l (sum of PFOA and perfluorooctanesulfonate, PFOS). PFOA and PFOS can be effectively removed from drinking water by percolation over granular activated carbon. Additionally, recent EU-regulations require phasing out use of PFOS and ask to voluntarily reduce the one of PFOA. New and shorter-chained PFCs (C4-C7) and their mixtures are being introduced as replacements. We assume that some of these "new" compounds could be main contributors to total PFC levels in drinking water in future, especially since short-chained PFCs are difficult to remove from drinking water by common treatment techniques and also by filtration over activated carbon. The aims of the study were to summarize the data from the regularly measured PFC levels in drinking water and in the drinking water resources in North Rhine-Westphalia (NRW) for the sampling period 2008-2009, to give an overview on the general approach to assess PFC mixtures and to assess short-chained PFCs by using toxicokinetic instead of (sub)chronic data. No general increase of substitutes for PFOS and PFOA in wastewater and surface water was detected. Present findings of short-chained PFC in drinking waters in NRW were due to extended analysis and caused by other impacts. Additionally, several PFC contamination incidents in drinking water resources (groundwater and rivers) have been reported in NRW. The new approach to assess short-chained PFCs is based on a ranking of their estimated half-lives for elimination from the human body. Accordingly, we consider the following provisional health-related indication values (HRIV) as safe in drinking water for lifelong exposure: perfluorobutanoate (PFBA) 7 microg/l, perfluoropentanoate (PFPA) 3 microg/l, perfluorohexanoate (PFHxA) 1 microg/l, perfluoroheptanoate (PFHpA) 0.3 microg/l, perfluorobutanesulfonate (PFBS) 3 microg/l, perfluoropentanesulfonate (PFPS) 1 microg/l, perfluorohexanesulfonate (PFHxS) 0.3 microg/l and perfluoroheptanesulfonate (PFHpS) 0.3 microg/l. For all PFCs the long-term lowest maximal quality goal (general precautionary value, PVg) in drinking water is set to -0.1 microg/l.