National Primary Drinking Water Regulation for PFOA and PFOS

On March 14th at 10 AM ET, EPA released the proposed National Primary Drinking Water Regulation (NPDWR) for PFOA and PFOS, along with four additional PFAS. EPA is proposing to set a Maximum Contaminant Level (MCL) of 4 parts per trillion (ppt) for PFOA and 4 ppt for PFOS. In addition to these two MCLs, EPA is proposing to address four additional PFAS (GenX, PFBS, PFNA, and PFHxS) as a mixture using a Hazard Index. The Hazard Index is a tool typically used to evaluate potential health risks from exposure to chemical mixtures. This approach has been used in other EPA programs, such as the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), but this is the first time it has been used for a drinking water standard. Additionally, EPA is proposing Maximum Contaminant Level Goals (MCLGs) for each of the six PFAS. A breakdown of the MCLs and MCLGs is shown on the table below. 
 
PFAS Compound 
Proposed MCLG 
Proposed MCL 
PFOA 
0 ppt 
4.0 ppt 
PFOS 
0 ppt 
4.0 ppt 
PFNA 
 
1.0 (unitless Hazard Index) 
 
1.0 (unitless Hazard Index) 
PFHxS 
PFBS 
HFPO-DA (GenX) 
 
Click Read More for the rest of the announcment... 
 
 
For the Hazard Index, the rule proposes a ratio for each of the four PFAS to be used to calculate a compliance value based on detected levels of the four PFAS. If the combination of those four ratios is at or above 1.0, then water systems will be expected to reduce the levels of these PFAS. Depending on the level of contamination found, water systems may need to take action even if only one of the four PFAS is present. EPA will be creating a webpage with a calculator tool for water systems to determine their Hazard Index. 
 
The proposal has not yet been published in the Federal Register. The public will be given 60 days to provide comments after final publication, expected in the coming weeks. EPA will be holding two informational webinars about the proposed PFAS NDPWR on March 16, 2023, and March 29, 2023. The webinars will be similar, with each intended for specific audiences. Registration is required to attend. The webinar recordings and presentation materials will be made available following the webinars. 
EPA will also be holding a public hearing on May 4, 2023, where members of the public can provide verbal comments to EPA on the rule proposal. Registration is required to attend and the last day to register to speak at the hearing is April 28, 2023.  
EPA has provided facts sheets for the public and FAQs specifically for primacy agencies to help with the rollout of this proposal. See the links below: 
 
Published with permission from Virginia Department of Health, Office of Drinking Water
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