March 29, 2023. The proposed MCLs for PFOA and PFOS, and the proposed Hazard Index MCL for four additional PFAS were published in today’s Federal Register (copy here: Federal Reg_Proposed PFAS MCLs_2023-03-29) for public review and comment. Public comments are due by May 30, 2023. EPA held one public webinar on March 16, 2023. A second webinar will be held today. See the Regulatory Update below for registration for the (virtual) May 4, 2023 public hearing.
For your information.
From: Dan Askenaizer
Sent: Tuesday, March 14, 2023 8:52 AM
To: ‘Dan Askenaizer’
Subject: WQTS Regulatory Update: EPA Proposed PFAS MCLs, and Hazard Index for Four PFAS
Good morning to all,
Proposed MCLs for PFOA and PFOS
The Environmental Protection Agency (EPA) has released a pre-publication Federal Register notice of the proposed Maximum Contaminant Levels (MCLs) for PFOA and PFOS. The proposed MCLs are 4 parts per trillion (ppt) for each compound. A copy of the pre-publication version of the Federal Register notice is enclosed. Once the proposed MCLs are published in the Federal Register there will be a 60-day public comment period. Also enclosed are an EPA Fact Sheet and FAQ document. EPA is also proposing a “Hazard Index” for four PFAS (described below).
EPA will hold two webinars on the proposal on March 16, 2023 (2:00 to 3:00 pm, ET), and March 29, 2023 (2:00 to 3:00 pm, ET). EPA describes the March 16th webinar as a general overview of the proposal and the March 29th webinar as a technical overview of the proposal.
EPA will hold a public hearing on May 4, 2023 (11:00 am to 7:00 pm, ET).
Registration for March 16th webinar:
Registration for March 29th webinar:
Registration for May 4th public hearing:
Link to EPA Press Release
EPA Proposing Hazard Index for Four Other PFAS
In the enclosed pre-publication version, EPA is also proposing “….to use a Hazard Index (HI) approach to protecting public health from mixtures of PFHxS, HFPO-DA and its ammonium salt, PFNA, and PFBS because of their known and additive toxic effects and occurrence and likely co-occurrence in drinking water.”
Proposed Definition of Hazard Index
“Hazard index (HI) is the sum of component hazard quotients (HQs), which are calculated by dividing the measured regulated PFAS component contaminant concentration in water (e.g., expressed as ppt) by the associated Health-Based Water Concentration (e.g., HBWC expressed as ppt). For PFAS, a mixture HI greater than 1.0 is an exceedance of the MCL.” [emphasis added]
How To Calculate the Hazard Index
Steps to calculate the HI: “….a ratio called a hazard quotient (HQ) is calculated for each of the four PFAS (PFHxS, HFPO-DA and its ammonium salt (also known as GenX chemicals), PFNA, and PFBS) by dividing….the measured level of each of the four PFAS in drinking water, by a health reference value for that particular PFAS. For health reference values, in this proposal, EPA is using Health Based Water Concentration (HBWCs) as follows: 9.0 ppt for PFHxS, 10.0 ppt for HFPO-DA; 10.0 ppt for PFNA; and 2000 ppt for PFBS. The individual PFAS ratios (HQs) are then summed….to yield the HI. If the resulting HI is greater than one (1.0), then the exposure metric is greater than the health metric and potential risk is indicated.”