PFAS in Drinking Water: The Science Behind Minimum Risk Levels

Drinking water has been identified as a substantial source of PFAS Definition exposure for many populations, particularly those living near contaminated sites, including Newtown Township (read “Perfluorinated Compounds Detected in Newtown Township's Water Supply”).

The United States Environmental Protection Agency (U.S. EPA) proposed a lifetime health advisory level for PFOS+PFOA Definition of 70 ng/L* in drinking water in 2016.

In 2018, the Agency for Toxic Substances and Disease Registry (ATSDR) in the United States further lowered the Minimum Risk Levels (MRLs) for PFOS and PFOA by approximately an order of magnitude compared to the reference dose (RfD) used by the U.S. EPA to develop the 2016 lifetime advisory.(Ref 1) Drinking water advisory levels corresponding to the MRLs used by ATSDR would be 11 ng/L for PFOA and 7 ng/L for PFOS.

Some lifetime drinking water advisories proposed by other state and international agencies include up to 11 or 12 PFASs (Sweden and Denmark) and range from less than 10 ng/L up to hundreds to thousands of ng/L for different PFASs in Canada.(Ref 2)

Notably, Grandjean and Burdz-Jorgensen(Ref 3) estimated the lifetime drinking water advisory level should be less than 1 ng/L based on the benchmark dose for immunotoxicity associated with PFAS exposure for children in the Faroe Islands.

* X ng/L (nanograms per liter) is equivalent to X ppt (parts per trillion)

References

1. ATSDR. Toxicological Profile for Perfluoroalkyls: Draft for Public Comment, June 2018 Agency for Toxic Substances and Disease Registry, U.S. Department of Health and Human Services, Atlanta, GA: Available: https://www.atsdr.cdc.gov/toxprofiles/tp200.pdf [Accessed: 31 August, 2018], 2018.

2. Health Canada. Health Canada’s Drinking Water Screening Values for Perfluoroalkylated Substances (PFASs). February 2016, Ottawa, ON. Available: http://scottreid.ca/wp-content/uploads/2016/03/Health-Canada-PFAS-Screening-Values-Fact-Sheet-EN.pdf [Accessed: 20 August, 2018]. 2016.

3. Grandjean P, Budtz-Jorgensen E Immunotoxicity of perfluorinated alkylates: calculation of benchmark doses based on serum concentrations in children. Environmental Health 2013; 12: 35.

4. EWG. “The Science on PFAS: Rebuttal to 3M’s Claims” Available: https://www.ewg.org/news-and-analysis/2019/09/science-pfas-rebuttal-3m-s-claims [Accessed: 14 September, 2019]

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Posted on 11 Oct 2019, 01:50 - Category: Environment