PFAS in Biosolids

Per- and Polyfluoroalkyl Substances (PFAS) do not occur in nature, they are an entirely synthetic substance. Yet, most people in the United States have been exposed to PFAS, and have PFAS in their blood, especially perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA). 

There are thousands of PFAS chemicals, and they are found in many different consumer, commercial, and industrial products. Various PFAS chemicals have been widely used for over 80 years mainly for their ability to repel oil, grease, water, and heat. PFOS and PFOA found in Scotch Guard and in Teflon and traditional Aqueous Film-Forming Foam (AFFF) - the foam used to fight aviation and other chemical fires -were the first to become widely commercially successful.

But PFAS use has continued to grow. It is widely used in consumer products. Spray coatings to cans and food packaging, flame retardants, waterproof coatings and on and on. PFAS are resistant to degradation and because they are so soluble in water simply flow through the wastewater treatment plant or septic leach field. In this way PFAS ends up in the sewage sludge also called biosolids and effluent returned in rivers.

Though the terms “biosolids” and “sewage sludge” are often used interchangeably by the public, the U.S. Environmental Protection Agency (EPA) typically uses the term “biosolids” to mean sewage sludge that has been treated to meet the requirements in Part 503 and is intended to be applied to land as a soil amendment or fertilizer. Biosolids may contain PFAS (and other contaminants) that wastewater treatment plants receive from industrial facilities and homes.

Biosolids were used as a cheap fertilizer and PFAS entered the food supply picked up by crops and grazing animals. The reach and spread of PFAS was increased because effluent from wastewater treatment is released to rivers and used as source water for drinking water. Out it went to rivers and streams ultimately to the oceans. Fish and seafood were also exposed to PFAS through the wastewater effluent as were we. According to Fairfax Water diet is responsible for 66 %-72 % of exposures to PFOA and PFOS (the two chemicals that have been most widely studied) in people. 

On April 10th 2024 the Environmental Protection Agency (EPA) finalized the national primary drinking water standards for six types of PFAS. Also in April 2024 EPA finalized a rule to designate perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) as hazardous substances under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), also known as Superfund. 

This is a huge problem. Under Superfund all parties are jointly and severally liable for contamination. For decades, encouraged the land application of biosolids. Sludge intended for land application generated by water treatment plants is regulated under the Biosolids Rule (part of the Clean Water Act Amendments of 1987. That rule used a sample extraction method for chemical analysis to look for contaminants listed in the Land Disposal Restrictions of RCRA. If those contaminants were not present the biosolid was classified as non-hazardous and can be disposed at a municipal landfill or land applied, but it only looked for a limited number of potential contaminants.

U.S. EPA regulations limit metals and pathogens in biosolids intended for land applications, but no organic contaminants are currently regulated under 40 CFR Part 503 Rule created in 1989 and still in effect today. It categorizes Biosolids as Class A or B, depending on the level of fecal coliform and salmonella bacteria in the material and restricts the use based on classification. There turns out to be many more contaminants in sewage sludge. Over the years controversy associated with potential impacts of Biosolids and the land disposal or reuse of Class B and even Class A Biosolids have grown.

The presence of other emerging contaminants in the Biosolids has not been tracked, but has become an emerging area of concern. Previously, research at the University of Virginia found that organic chemicals persist in Biosolids and can be introduced into the food chain. Land application of biosolids is a widespread practice across the US and remains an approved method by the US EPA.

In Maine they had been spreading biosolids on its farms and fields since it was first allowed. Its application on farms had been seen as an inexpensive way to fertilize. Unfortunately, the biosolids became contaminated with PFAS from both residential and industrial wastewater sent to the wastewater treatment plants. Biosolids were land applied and buried in landfills. Animals grazed on the land, food grown on the land picked up some of the PFAS and passed traces into food. PFAS also leached from the land and landfills into groundwater. People passed it onto other wastewater treatment plants and the circle widened.

At last report the Maine Department of Environmental Protection (DEP) had found more than 70 PFAS-contaminated farms, a handful of which have had to cease all food production. In 2022, Maine became the first state to ban land application of biosolids and the sale of compost containing biosolids, but not before the farms had to stop producing food. The EPA is currently engaged in characterizing the biosolids. (EPA does not actually do any scientific work, it funds it). PFAS do not easily degrade and can bioaccumulate – or build up – in the environment and the human body over time resulting in potential adverse health impacts. Given their persistence and potential health impacts, it is important to understand how PFAS may impact our food system and people living in agricultural areas so EPA can develop strategies to reduce and prevent these exposures

Using EPA’s funding, research teams will investigate topics including how PFAS accumulates in crops and livestock; the effects of biosolids, compost and irrigation water on PFAS plant uptake and accumulation; and strategies to reduce the risks of PFAS contamination in the food supply. The following institutions have received grant awards for research:

• Michigan State University, East Lansing, Michigan - Comprehensive Evaluation of Fate, Transport, Bioaccumulation and Management Solution of PFAS on a Crop and Livestock Farm that Received Biosolids.

• Passamaquoddy Tribe, Sipayik Environmental Department, Pleasant Point, Maine - PFAS Accumulation in Finfish and Shellfish Species within the Coastal and Inland Waters of the Peskotomuhkati (Passamaquoddy) Homelands.

• Temple University, Philadelphia, Pennsylvania - Investigating the Effects of Irrigation Water, Compost and Biosolid Qualities on PFAS Uptake by Edible Crops in Urban Gardens and Farms.
• Texas A&M University, College Station, Texas - PFAS-MAPS: PFAS Mitigation and Monitoring in Amended Plant Systems.

• Texas Tech University, Lubbock, Texas - Evaluating and Mitigating Bioaccumulation of PFAS in Plant, Mammalian and Aquaculture Systems.

• University at Albany, State University of New York Albany, New York - Practical Management of PFAS Contaminated Agricultural Soil Using an Innovative Platform Integrating Experimental Research and Machine Learning Approaches.

• University of Illinois, Urbana, Illinois - Plant Uptake and Mitigation of PFAS Associated with Sewage Effluent and Biosolids Application in Tile-Drained Field.

• University of Maine, Orono, Maine - Developing Integrated Mitigation Strategies to Help Farmers Reduce PFAS Risks in Forage and Livestock Systems.

• University of Utah, Salt Lake City, Utah - PFAS in Land-applied Biosolids in Agricultural Settings: A Mechanistic Understanding on Fate and Mitigation.

• University of Virginia, Charlottesville, Virginia - Novel, Bio-enabled Strategies to Prevent Per- and Polyfluoroalkyl Substances Accumulation in Crops and Food Webs.

 It is estimated that the United States generates almost 6 million metric tons of biosolids each year slightly more than half is land applied for agriculture as a soil amendment and the rest is land filled. The United States has been land applying these biosolids for decades.