Re: Setting Public Drinking Water and Groundwater Standards for PFOA, PFOS, PFNA, & PFHxS (Env-Dw 700-800; Env-Or 603.03)

Based on our analysis of the Summary Report and incorporation of new exposure models, we suggest the following MCLs be adopted by NHDES:

  • PFOA: <1 ppt (and no more than 3 ppt) based on application of the new transgenerational toxicokinetic model for PFOA exposure proposed by MN Department of Health (MN DH), and either selecting the effects on the mammary gland as the critical endpoint or applying additional uncertainty factors to account for these effects (See Appendix 1).

  • PFOS: 13 ppt based on application of the new transgenerational toxicokinetic model for PFOS exposure proposed by MN DH and selecting the immunotoxic effects as the critical endpoint (See Appendix 2).

  • PFNA: 1 ppt based on the application of exposure estimates specific for infants, the application of additional uncertainty factors to account for the short duration of exposure in the selected critical study, and use of a more representative half- life (See Appendix 3).

  • PFHxS: 30 ppt based on application of the new transgenerational toxicokinetic model for PFOS exposure proposed by MN DH and a more representative value for the volume of distribution (See Appendix 4).

Mindi Messmer