The public comment period recently closed on the Environmental Protection Agency (EPA) January 2025 draft assessment evaluating potential human health and environmental risks associated with the disposal and land application of sewage sludge containing perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS). These compounds belong to the broader class of per- and polyfluoroalkyl substances (PFAS) often referred to as “forever chemicals” due to their environmental persistence and resistance to degradation.
The public comment period generated a spectrum of responses ranging from endorsements to critiques. As with EPA’s proposed rulemaking to classify PFOA, PFOS and other PFAS as “hazardous constituents” under the Resource Conservation and Recovery Act (see EPA Proposes Rules for Regulating PFAS under RCRA), the EPA acknowledged limitations and uncertainties in its evaluation of potential health effects, particularly with respect to exposure modeling and endpoint selection.
The draft assessment may become a point of contention in ongoing PFAS litigation. Given the assessment’s narrow scope, PFAS defendants should consider seeking its exclusion as irrelevant and prejudicial. They may also challenge expert reliance on the assessment as unreliable or, where appropriate, counter that it supports alternative exposure defenses.
Draft Risk Assessment
Sewage sludge, a semi-solid byproduct from wastewater treatment, is typically incinerated, landfilled or reused as fertilizer if it meets safety regulatory standards permitting classification as “biosolid.” Elevated PFOA and PFOS in sewage sludge, originating from industrial, commercial and household sources, have been detected in soil, groundwater, livestock, crops and surface water. This prompted the EPA to conduct a risk assessment to evaluate potential human health and environmental risks associated with disposing or applying this sludge to land.
The draft assessment does not model risks for the general public, but instead focuses on specific populations living near, or on, impacted lands used for livestock raising (pasture farms), fruit and vegetable cultivation (crop farms), surface disposals (disposal scenarios) or soil restoration projects involving overgrazed pastures (reclamation scenarios). The assessment considers individuals relying on products from these lands: farm families, those drinking impacted water, people eating freshwater fish, individuals eating food from home or community gardens and participants in community-supported agriculture. Key risk pathways include drinking milk from pasture-raised cows consuming contaminated forage, soil, and water; drinking water from contaminated sources; eating fish from lakes affected by runoff; and consuming beef or eggs from pasture-raised animals on treated lands.
The EPA concludes that risks from land-applied sewage sludge can exceed EPA safety thresholds in pasture farms, crop farms, and reclamation scenarios, when the sludge contains 1 part per billion (ppb) of PFOA or PFOS. Researchers also determined there may be risks from drinking contaminated groundwater sourced near disposal sites where sludge contains 1 ppb of PFOA or 4-5 ppb of PFOS in unlined or clay-lined units.
The public comment period closed on August 14, 2025, yielding a range of responses. Among the submissions was a detailed critique from six research scientists affiliated with the U.S. Department of Agriculture (USDA) who challenged the reliability of data across several exposure pathways and called for additional research to strengthen the scientific foundation.
The EPA may revise, finalize or defer finalizing the assessment. If adopted in its current or modified form, the assessment could lay the groundwork for future regulation of PFAS in sewage sludge. However, further actions, such as a feasibility analysis and rulemaking, would be necessary before any enforceable standards are implemented.
It remains uncertain whether current EPA leadership will move forward with finalizing the draft assessment. Following its publication, the EPA outlined a broader agency agenda to address PFAS contamination. The plan includes implementing a PFAS testing strategy under the Toxic Substances Control Act (TSCA) and expanding the Toxic Release Inventory to include additional PFAS compounds. At the same time, the EPA has signaled a more flexible regulatory posture in certain areas. For instance, the agency announced its intent to extend compliance deadlines and introduce exemptions for PFOA and PFOS drinking water standards. It also proposed rescinding water regulations for other PFAS substances, raising questions about the scope and consistency of future enforcement.
Assessment Limitations
Sewage sludge is reportedly applied to less than 1% of productive, fertilized agriculture land annually, underscoring the assessment’s narrow focus on those residing on or near impacted properties or primarily relying on their products. Importantly, not all farms or disposal sites using sewage fertilizer are expected to pose human health risks. There are reasons to doubt that PFOA and PFOS pose any of the alleged risks cited by the EPA and by plaintiff firms in personal injury litigation. The presence and magnitude of any risk would depend on various factors, such as human behavioral patterns like ingestion rates, PFOA and PFOS concentrations, geological conditions, geological and environmental conditions such as soil composition and climate, and other site-specific factors.
The modeled populations engage in higher-exposure behaviors, such as consuming a high portion of food products from a single potentially contaminated land. The EPA acknowledges that the assessment is hypothetical, and that uncertainty, variability and sensitivity may lead to outcomes different than those modeled.
While the draft assessment broadly refers to cancer and noncancer risks, the EPA cites studies of PFOA and PFOS and specific health effects. For PFOA, these are kidney and testicular cancer, human breast cancer in susceptible populations, and hepatic, immunological, cardiovascular and developmental effects. For PFOS, these are bladder, prostate, liver, kidney and breast cancer, and hepatic, immunological, cardiovascular and developmental effects. The EPA’s models apply exposure levels for a limited set of specific endpoints: renal cell carcinoma and reduced antibody response to vaccinations in children (PFOA), hepatocellular adenomas and carcinomas in female rats (PFOS) and decreased birth weight and increased cholesterol (PFOA and PFOS). There is good reason to doubt that any or all of the foregoing conditions have any association with PFOS and PFOA.
Defenses Against Assessment in Litigation
Plaintiffs in the expansive PFAS litigation landscape may seek to rely on the EPA’s draft risk assessment as evidence that PFAS compounds pose human health risks. However, PFAS defendants have several avenues to challenge the relevance and admissibility of the assessment. They may argue the assessment is irrelevant due to its limited scope, targeted populations and specific exposure pathways. Further, the assessment is premised on studies of specific health effects and exposure levels for a limited set of endpoints, which may be unrelated to the alleged injuries or causation theories advanced by plaintiffs.
If the assessment remains in draft form and is not finalized, defendants can emphasize its nonbinding and preliminary nature, potentially undermining its probative value. If the assessment is not finalized, PFAS defendants could highlight that it is a nonfinal draft. PFAS defendants may also consider challenging experts who cite the nonfinal assessment as unreliable.
Affirmatively, PFAS defendants should consider preemptive motions in limine or other evidentiary strategies to exclude reference to the draft assessment. Where exclusion is not feasible, defendants may alternatively argue that, to the extent the assessment is deemed relevant, it supports alternative exposure scenarios or causation defenses, particularly where plaintiffs’ alleged exposure differs materially from the modeled pathways.
