Last week EPA released its proposal for the first set of Maximum Contaminant Levels (MCLs) under the Clean Water Act for per- and polyfluoroalkyl substances (PFAS).  In contrast to non-enforceable health advisory levels introduced in 2016 and revised in 2022, MCLs constitute enforceable drinking water standards that will impact drinking water utilities and industry nationwide.  The proposal for enforceable drinking water standards marks the latest step in the evolution of PFAS from an emerging contaminant to a contaminant subject to enforceable regulations. 

The proposed rule sets standards for six PFAS compounds as follows:

*More information on how the Hazard Index will be calculated is available in an EPA fact sheet.

The proposed MCLs follow lifetime health advisory levels for PFOA, PFOS, GenX and PFBS issued by EPA in the summer of 2022.  The health advisory levels for PFOA and PFOS are 0.004 parts per trillion, which is a level that cannot yet be reliably detected in laboratories.  While the 4 ppt proposed MCL for PFOA and PFOS is low relative to the levels in place for other constituents, it is at least detectable using current technology.

In the preamble to the proposed rule, EPA indicated that no safe level for PFOA and PFOS has been identified.  Therefore, EPA is setting the non-enforceable, health-based Maximum Contaminant Level Goal (MCGL) at zero for both PFOA and PFOS.  Given that EPA requires the MCLs to be set “as close as feasible” to the MGCLs, the regulated community should be aware that EPA may move to further lower the limits for PFOA and PFOS as technology improves.   

We are also tracking a number of other PFAS-related developments, including that in August 2022, EPA released a proposed rule that would designate PFOA and PFOS as CERCLA hazardous substances.  A number of states (including California and Maine) have passed laws banning the use of PFAS in certain applications.