June 20, 2023

PFAS National Primary Drinking Water Regulation Rulemaking

One of the first steps in regulating polyfluoroalkyl substances (PFAS) is to establish health-based standards. Accordingly, on March 29, 2023, EPA issued a final regulatory determination regulating perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) as contaminants under the Safe Drinking Water Act (SDWA). [88 FR 18638] The agency also made a preliminary regulatory determination to regulate perfluorohexane sulfonic acid (PFHxS), hexafluoropropylene oxide dimer acid (HFPO-DA), perfluorononanoic acid (PFNA), perfluorobutane sulfonic acid (PFBS), and mixtures of these PFAS as contaminants under the SWDA.

The proposed rule includes national primary drinking water regulations (NPDWRs) and health-based maximum contaminant levels (MCLs) and maximum contaminant level goals (MCLGs) for these six PFAS chemicals and their mixtures. NPDWRs are legally enforceable standards and treatment techniques applicable to public water systems. MCLs are also legally enforceable and establish the maximum allowable levels of contaminants in drinking water. MCLGs are non-enforceable public health goals. They are set at the maximum level of a contaminant in drinking water where no known or expected effects on human health will occur. Generally, EPA tries to set MCLs at the same level as MCLGs unless it is infeasible (e.g., analytical, cost, or treatment issues).

The proposal would establish MCLs and MCLGs as follows:

Substance

Proposed MCLG

Proposed MCL

PFOA

0

4.0 ppt

PFAS

0

4.0 ppt

PFHxS

HI ≤ 1.0

HI ≤ 1.0

HFPO-DA (a.k.a. GenX)

HI ≤ 1.0

HI ≤ 1.0

PFNA

HI ≤ 1.0

HI ≤ 1.0

PFBS

HI ≤ 1.0

HI ≤ 1.0

Combinations of PFHxS, HFPO-DA, PFNA, and PFBS

HI ≤ 1.0

HI ≤ 1.0

HI = hazard index, which is determined via calculation, as prescribed in the proposed regulations.

Notably, the proposed rule uses a hazard index (HI) approach to establish MCLGs for four of the chemicals. The agency chose this approach because these chemicals are often found together in drinking water, and the effects are cumulative. The HI approach provides a means to establish the risk when multiple PFAS are present.

An FAQ on the proposed rule is available and includes example HI calculations. Comments were due by May 30, 2023, but you can review the proposal via Docket ID: EPA-HQ-OW-2022-0114. EPA’s website has some additional information on the proposed rule.

 


©2023-2024 McCoy and Associates, Inc. All rights reserved.

McCoy and Associates has provided in-depth information to assist environmental professionals with complex compliance issues since 1982. Our seminars and publications are widely trusted by environmental professionals for their consistent quality, clarity, and comprehensiveness.

 

Disclaimer

Considerable care has been exercised in preparing this document; however, McCoy and Associates, Inc. makes no representation, warranty, or guarantee in connection with the publication of this information. McCoy and Associates, Inc. expressly disclaims any liability or responsibility for loss or damage resulting from its use or for the violation of any federal, state, or municipal law or regulation with which this information may conflict. McCoy and Associates, Inc. does not undertake any duty to ensure the continued accuracy of this information.

This document addresses issues of a general nature related to the federal RCRA regulations. Persons evaluating specific circumstances dealing with the RCRA regulations should review state and local laws and regulations, which may be more stringent than federal requirements. In addition, the assistance of a qualified professional should be enlisted to address any site-specific circumstances.