EPA Proposes the First National Primary Drinking Water Regulations for any PFAS Chemical
By Miranda Henning, BCES, Managing Principal
Avram Frankel, P.E., Managing Principal
On March 14, 2023, the U.S. Environmental Protection Agency (EPA) proposed National Primary Drinking Water Regulations (NPDWRs) for perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), regulated as individual compounds, and perfluorohexane sulfonic acid (PFHxS), hexafluoropropylene oxide dimer acid (HFPO-DA) and its ammonium salt (also known as GenX chemicals), perfluorononanoic acid (PFNA), perfluorobutane sulfonic acid (PFBS), regulated as a mixture.
Maximum Contaminant Levels
EPA has proposed a Maximum Contaminant Level (MCL) of 4 parts per trillion (ppt) both for PFOA and for PFOS. MCLs are enforceable drinking water regulations and represent the maximum amount of chemical that is permitted in the public drinking water supply.
MCLs are developed by EPA under the Safe Drinking Water Act, based on consideration of potential health effects, treatment feasibility, and cost. The proposed MCLs for PFOA and PFOS are based on “the lowest concentration at which PFOA and PFOS can reliably be measured in finished drinking water.”
For PFHxS, GenX, PFNA, and PFBS, EPA proposes a Hazard Index MCL, which is an enforceable limit on mixtures of these chemicals. Under the regulation, the compliance statistic for these four substances is calculated as the sum of the ratios of the measured concentration compared to allowable concentration (i.e., health-based water concentration). The calculated hazard index must be less than 1.0 to comply with the proposed Hazard Index MCL.
Maximum Contaminant Level Goals
EPA also has proposed Maximum Contaminant Level Goals (MCLGs) for PFOA and PFOS. An MCLG is a chemical-specific guidance value and represents the maximum concentration of a chemical in drinking water at which no adverse health effects are expected to occur. MCLGs are non-enforceable health-based values that do not consider treatment feasibility or cost. For both PFOA and PFOS, the proposed MCLG is 0 ppt based on EPA’s determination that “PFOA and PFOS are likely to cause cancer.”
The proposed MCLGs are considerably lower than EPA’s 2016 lifetime health advisories of 70 ppt and are below EPA’s interim lifetime health advisories for PFOA and PFOS of 0.004 ppt and 0.02 ppt, respectively, issued in June 2022. The new lower values result from EPA’s conclusion that potential health effects from exposure to PFOA and PFOS occurring at lower concentrations than previously indicated.
For PFHxS, GenX, PFNA, and PFBS, EPA proposes a Hazard Index MCLG identical to the Hazard Index MCL.
Comparison to Other Criteria
The proposed MCLGs contrast with the World Health Organization’s recently announced draft provisional guideline values of 100 ppt for PFOA and PFOS individually and combined. Similarly, the proposed MCLs are lower than the European Union drinking water limit for the sum of PFAS compounds of concern of 100 ppt, and Health Canada’s maximum acceptable drinking water concentrations of 200 and 600 ppt for PFOA and PFOS, respectively.
Implications and Challenges Ahead
EPA’s proposed PFAS MCLGs and MCLs have come after the proposal or promulgation of drinking water criteria by 20 states. And the PFOS and PFOA MCLs are lower than any state’s current promulgated drinking water regulations.
Once the regulations are promulgated, drinking water systems across the country will be required to comply with the new MCLs. The NPDWRs are expected to be finalized by the end of 2023 following a 60-day public comment period on the proposed regulations, according to EPA’s announcement. Typically, once finalized, drinking water regulations take effect 3 years after promulgation. In some cases, however, the deadline can be extended for up to an additional 2 years.
These new regulations will present challenges to many drinking water providers, regulators, and industries who are navigating increasing costs of compliance, monitoring, and treatment. These new values also may be used by states to revise or promulgate new PFAS criteria for drinking water supplies and to guide site remediation.
Expert PFAS Regulatory and Scientific Support
Integral’s team is at the forefront of technical and regulatory PFAS developments. Our multidisciplinary experts can guide you through the evolving PFAS regulatory landscape and evaluate associated risks. Please reach out to us for support in navigating upcoming regulatory actions including implications for water treatment and site remediation. To speak with one of our experts, please contact Miranda Henning, BCES or Avram Frankel, P.E. For more information, check out Integral’s PFAS page.