EPA Extends Comment Period on Draft Risk Assessment for PFOA and PFOS in Biosolids

Update: EPA will now accept public comments on its Draft Sewage Sludge Risk Assessment for Perfluoroctanoic Acid (PFOA) and Perfluorooctane Sulfonic Acid (PFOS) until August 15, 2025. Interested parties may submit comments at regulations.gov (Docket ID EPA-HQ-OW-2024-0504).

• What Happened? The U.S. Environmental Protection Agency (EPA) issued its long-promised Draft Risk Assessment for PFOA and PFOS in Sewage Sludge (Draft Risk Assessment) on January 14, 2025, just before the change in administration. The Draft Risk Assessment aims to characterize potential human health and environmental risks associated with land application as a fertilizer of sewage sludge (biosolids) that contain PFOA or PFOS. Recycling biosolids to farmland is one of the largest recycling practices in the world and has been practiced across the U.S. for over 50 years pursuant to federal regulation under the Clean Water Act. In the January Draft Risk Assessment, EPA concluded that biosolids containing PFOA and PFOS at even low concentrations (1 ppb of PFOA or PFOS) may exceed its very conservative criteria for possible health risks under unusual long-term exposure scenarios.
• Who is Affected? The Draft Risk Assessment, by its own terms, is neither a regulation nor EPA guidance. However, it is influential and is a foundation for potential future modifications to the federal regulations that provide the standards for biosolids management, including the land application of biosolids as fertilizer. 40 C.F.R. Part 503. The Draft Risk Assessment is designed to assist EPA in determining whether it should regulate PFAS in biosolids in the future, which would be a separate agency action through notice and comment rulemaking. Municipalities, biosolids contractors, and farm users of biosolids will have to adapt to any EPA decision to regulate PFAS in biosolids. Additionally, mixed messaging from EPA in the Draft Risk Assessment has caused some confusion and uncertainty in state and local governments across the country, which is already affecting the options for managing biosolids and other wastewater residuals.
• Next Steps? Many stakeholders are preparing public comments or have already filed comments. To date, 70 comments have been filed, including robust submissions from stakeholders, including the California Association of Sanitation Agencies (CASA), the American Water Works Association, the U.S. Composting Council, and the Mid-Atlantic Biosolids Association. After comments close in August, EPA will ultimately publish a final risk assessment that will inform its subsequent risk management decisions, including potential revisions to the Part 503 Regulations governing the beneficial use of biosolids. Stakeholders, including municipalities, biosolids contractors, and organic fertilizer producers (including compost) should consider commenting to ensure the final risk assessment considers all relevant factors, including the benefits of biosolids, and uses the best science and risk assessment methodology.

The Biosolids Risk Assessment in a Nutshell

EPA’s highly conservative risk assessment has drawn criticism from many stakeholders. Questions include EPA’s unusual decision to not include a risk management analysis in the draft assessment, the reliance on an atypical farm family as an exposure model, and poor study selection that overlooked research from sites where municipal, non-industrial biosolids have been land applied on a long-term basis. For example, CASA assembled a team of scientists who studied the Draft Risk Assessment and detailed their conclusions that EPA’s work was flawed and needed extensive revisions. The Draft Risk Assessment evaluated narrow scenarios that are inapplicable to the general public and to biosolids land application as practiced in the U.S. EPA modeled potential health risks associated with exposure from four different uses of biosolids containing 1 ppb of PFOA or PFOS: two types of agricultural land application, land application at a reclamation site, and surface disposal (i.e., placing biosolids in a sewage sludge monofill). EPA did not attempt to—nor did it—assess risks to the general public or the general food supply. Instead, the Draft Risk Assessment evaluates risks to hypothetical “highly exposed individuals”: An imaginary “farm family” that EPA defines as people “living near a use or disposal site who use contaminated groundwater as a source of drinking water or people who primarily consume produce, dairy, or meat from a farm that has applied contaminated sewage sludge” under the conditions EPA models for ten years. EPA acknowledged that choosing to focus on the “farm family” renders EPA’s conclusions largely inapplicable to the general public, because the “draft risk assessment does not model risks for the general public.” 

EPA evaluated the risks associated with land application at a pasture farm—a farm with a majority of pasture-raised dairy cows, beef cattle, or chickens—and at a crop farm growing fruits or vegetables. For both types of farms, EPA assumed 40 annual applications of 10 dry metric tons of biosolids per hectare containing 1 ppb PFOA or PFOS for a period of 40 years, a scenario not found in biosolids practice. Under these conditions, EPA found that cancer risks from heavy consumption of farm products from biosolids fertilized fields (i.e., milk consumption from the pasture farm, consumption of beef and eggs from the pasture farm, eating produce from the crop farm) ranges from one in 1,000 to one in 100,000. EPA also found elevated risks associated with drinking water and eating fish from a waterbody in the same watershed as the farm. 

EPA contends that the models used in the draft result in a linear relationship between the starting concentration of PFOA or PFOS in biosolids and the resulting risks—meaning that biosolids containing 10 ppb of PFOA or PFOS—which is ten times the amount modeled by EPA—would have a risk ten times greater than what EPA found. CASA’s team pointed out that linear assumptions regarding bioaccumulation factors, plant uptake, and other risk calculations are “highly unlikely to be linear” when biosolids with lower levels of PFOA and PFOS are land applied.

The Draft Risk Assessment has also been criticized for omitting recent research on typical biosolids—as opposed to biosolids sourced from industrially impacted wastewater—and for failing to account for other potential exposures to PFOA and PFOS. As CASA noted, more current research findings “rely on long-term application sites . . . generally demonstrate that there is limited migration of PFAS to groundwater and negligible crop uptake due in large part to low soil concentrations of PFAS, high organic carbon content, use of agronomic loading rates, and reduce mobility/bioavailability due to interactions with the solid-water and air-water interfaces.” CASA’s panel also observed that the assessment does not answer questions about whether restricting land application of biosolids will measurably reduce the exposure risk for the majority of the population.” Commenters have pointed out that these omissions also undermine the utility and accuracy of the Draft Risk Assessment’s conclusions. 

Public comments will play a critical role in ensuring that the agency’s final risk assessment presents a realistic picture of any risks from PFOA and PFOS in land application of biosolids, a vital and longstanding recycling practice for wastewater residuals worldwide.

Principal Hilary Jacobs (Washington, DC) will review the Draft Risk Assessment and speak about other legal issues surrounding PFAS in biosolids at the Water Environment Federation's 2025 Residuals & Biosolids and Innovations in Treatment Technology Conference, on May 7. 

Beveridge & Diamond’s robust Chemicals, Water, and Litigation practices have represented municipalities, contractors, trade associations, and farmers regarding biosolids issues since the firm’s founding in 1974. B&D helps companies and trade associations navigate the increasing regulation of PFAS and other chemicals. Our lawyers frequently assist in commenting on, and bringing legal challenges to, EPA rulemakings and risk assessments. For more information, please contact the authors.