U. S. EPA has established a Health Advisory Level for PFOA and PFOS in drinking water of 70 parts per trillion (“ppt”). Several states are regulating PFAS at the low parts per trillion level. For example, on June 1, 2020, the New Jersey Department of Environmental Protection adopted maximum contaminant levels (“MCLs”) in drinking water for PFOA and PFOS of 14 ppt and 13 ppt, respectively. See, NJDEP Issues Final Rule Regulating PFOA and PFOS. Try to imagine measuring a single second in 32,000 years, or finding and then removing one grain of sand from an Olympic-size swimming pool, each of which represent one part per trillion.
Other contaminants such as TCE, lead and benzene are regulated to the parts per billion (“ppb”) level, which is a thousand times more than one part per trillion. There are various challenges to obtaining reliable and accurate laboratory results in the low parts per trillion range, particularly for PFAS, since PFAS are found in a wide range of products and materials and the media likely will contain other substances. Sampling equipment that contains any of the following could lead to cross contamination: Teflon, polytetrafluoroethylene (PTFE); waterproof coatings containing PFAS; fluorinated ethylene-propylene (FEP); ethylene tetrafluoroethylene (ETFE); low-density polyethylene (LDPE); polyvinylidene fluoride (PVDF) and pipe thread compounds and tape. See ITRC. As discussed in our recent blog, there are U.S. EPA approved methods for sample preparation and analysis of finished drinking water samples only. There are no EPA-approved methods for analyzing other media such as non-potable water, groundwater, soil, sediment, air, and biota, which can result in variations from laboratory to laboratory and potentially inconsistent data. In addition, once detected above applicable standards, efforts to remove PFAS to achieve low ppt standards in large volumes of groundwater may compete with other substances present.
Due to the ubiquitous nature of PFAS and the lack of approved sampling and analysis methodologies, the applicability of parts per trillion standards and screening levels for PFAS poses unique challenges. Stay tuned for further updates in this evolving area.