What you need to know about the EPA PFAS biosolids risk assessment

Biosolids are treated sewage sludge that meet the U.S. Environmental Protection Agency (EPA) Standards for the Use or Disposal of Sewage Sludge. They are commonly applied to land as a soil conditioner or fertilizer and can be used on agricultural land, forests and rangeland. Biosolids are also suitable for nonagricultural use, such as golf courses, parks, gardens and home lawns.

While land application of biosolids offers environmental benefits, the presence of toxic per- and poly-fluoroalkyl substances (PFAS) chemicals in sewage sludge has raised concerns about potential impacts on soil and groundwater. In January 2025, the U.S. EPA released a draft risk assessment to understand human health risks associated with PFAS exposure from land-applied biosolids.

This blog post outlines key takeaways from the EPA's PFAS biosolids risk assessment and explains how the draft, when finalized, will guide the EPA and its partners in reducing exposure to these "forever chemicals." 

EPA PFAS biosolids risk assessment: Key takeaways

Risk assessment is a scientific process used to determine potential health risks to people, livestock or wildlife. The EPA uses sewage sludge risk assessments to evaluate actions needed to protect those who may face risks from sewage sludge disposal or use. In the PFAS biosolids risk assessment, the agency modeled scenarios to estimate human exposure and risks when sewage sludge is land-applied or disposed.

The EPA prioritized perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) in this assessment for several reasons:

• These chemicals are nonvolatile and nonbiodegradable, making them difficult to remove in standard wastewater treatment.
• PFOA and PFOS bioaccumulate in humans, plants, fish and livestock.
• The EPA classifies PFOA and PFOS as likely human carcinogens.

Conventional wastewater treatment technologies do not remove or destroy PFOA or PFOS. The draft risk assessment shows potential health risks associated with exposure to PFOA and PFOS through the common ways of disposing of or reusing sewage sludge, including landfill disposal, land application and incineration. 

How Fehr Graham can help improve biosolids quality at your wastewater treatment plant

Fehr Graham helps communities manage PFAS contamination in wastewater and biosolids. Our engineers and environmental experts develop cost-effective, innovative treatment solutions and help secure funding for system upgrades. We are committed to protecting public health and the environment.