On January 15th, the Federal Register published notice of the U.S. Environmental Protection Agency (EPA)’s Draft Sewage Sludge Risk Assessment for Perfluorooctanoic Acid (PFOA) and Perfluorooctane Sulfonic Acid (PFOS) in biosolids. This risk assessment had been promised under EPA's PFAS Strategic Roadmap by the Winter of 2024. Comments were originally due on March 17th but have been extended until April 16th.  EPA is specifically seeking comments on various aspects of its risk assessment model, including scenarios used, concentration levels, and toxicity factors, among other aspects.

EPA’s draft assessment is limited as it looks at only four scenarios and does not model risk for the general public. It does not consider cumulative exposure from multiple pathways or other sources of PFAS exposures. The draft model uses the “Central Tendency” method to model risk for two kinds of farm families (pasture-raised livestock and food crops), land reclamation sites, and sewage sludge surface disposal sites, commonly referred to as monofills. The draft model finds elevated risk for the farm families at concentrations of PFOA or PFOS in the biosolids of 1 part per billion. EPA found the risk from placement in unlined monofills equal to or greater than land application. The assessment did not look at sewage sludge incinerators (SSIs) due to the lack of data on emissions and ongoing research into the fate and transport of PFAS through SSIs. That part of the assessment was qualitative as was the look at lawn and home/community garden products impacts. 

NEBRA and other stakeholders were sent a pre-publication notice and information about an EPA webinar that was held on January 15th to present the findings from the draft risk assessment (Public Webinar: Draft Sewage Sludge Risk Assessment for PFOA and PFOS). Since then, NEBRA and its collaborators have been digging into the 270+ page document and beginning to craft comments on behalf of its members. NEBRA and the other biosolids associations co-sponsored a Lunch & Learn back in November about EPA's Risk Assessment for Biosolids and Risk Communications in general. On February 10th there was a members-only webinar with risk assessment and toxicology experts to examine the draft assessment in more detail (available on the Reg-Leg Committee webpage). The National Association of Clean Water Agencies (NACWA) has some great resources for utilities managers that they are sharing with everyone, not just their members.

It is important to note that the draft risk assessment is not a regulation, although the media and some state legislatures (Maryland) are looking to adopt it as the EPA’s recommended limit on PFAS in biosolids. However, EPA will need to address comments on the draft model and will probably make some adjustments to the model before moving ahead with the risk management work that would result in limits and/or best management practices.

For more information, go to EPA’s main page for the Draft Sewage Sludge Risk Assessment for Perfluorooctanoic Acid (PFOA) and Perfluorooctane Sulfonic Acid (PFOS) | US EPA