For the first time, the Environmental Protection Agency on Tuesday warned that “forever chemicals” present in sewage sludge that is used as fertilizer can pose human health risks.

In an extensive study the agency said that, while the general food supply isn’t threatened, the risk from contaminated fertilizer could in some cases exceed the EPA’s safety thresholds “sometimes by several orders of magnitude.”

A growing body of research has shown that the sludge can be contaminated with synthetic chemicals known as per- and polyfluoroalkyl substances, or PFAS, which are used widely in everyday items like nonstick cookware and stain-resistant carpets. The chemicals, which are linked to a range of illnesses including an increased risk of cancer, do not break down in the environment, and, when tainted sludge is used as fertilizer on farmland, it can contaminate the soil, groundwater, crops and livestock.

Last year, the New York Times reported that Maplewood-based 3M, which for decades has manufactured PFAS, found as early as 2000 that the chemicals were turning up in sludge samples from municipal wastewater plants across the country. In 2003, 3M told the EPA of its findings.

The EPA has for decades encouraged the use of sludge from treated wastewater as inexpensive fertilizer with no limits on how much PFAS it can contain. But the agency’s new draft risk assessment sets a potential new course. If finalized, it could mark what could be the first step toward regulating PFAS in the sludge used as fertilizer, which the industry calls biosolids. The agency currently regulates certain heavy metals and pathogens in sewage sludge used as fertilizer, but not PFAS.

The Biden administration has tackled PFAS contamination elsewhere, setting limits on PFAS in drinking water for the first time and designating two kinds of PFAS as hazardous under the nation’s Superfund cleanup law. Those rules came after the agency said in 2023 that there is no safe level of exposure to those two PFAS.

Regulations ahead?

The new EPA assessment “provides important information to help inform future actions by federal and state agencies,” as well as sewage treatment plants and farmers, “to protect people from PFAS exposure,” Jane Nishida, the EPA acting administrator, said in a statement.

It’s unclear what further steps the incoming Trump administration might take. President-elect Donald Trump has been hostile to regulations. However, he spoke on the campaign trail of “getting dangerous chemicals out of our environment,” and concerns about PFAS contamination in fertilizer have reached some deeply red states.

The EPA’s risk study comes as farmers have been discovering PFAS on their land.

The EPA said its analysis did not suggest the general food supply was at risk. Sewage sludge is applied to less than 1% of the fertilized acreage of agricultural land a year, it said, a number that roughly aligns with industry data. And, not all farms where sewage fertilizer was used would present a risk.

Still, studies have found that, because PFAS are so persistent in the environment, tainted sludge applied years or even decades ago can continue to be a source of contamination. More than 2 million dry tons were used on 4.6 million acres of farmland in 2018, according to the biosolids industry. Farmers have obtained permits to use sewage sludge on nearly 70 million acres, or about a fifth of all U.S. agricultural land, the industry said.

Christopher Higgins, a professor of civil and environmental engineering at the Colorado School of Mines who has researched biosolids, said it was notable the EPA had concluded concentrations in sludge fertilizer posed risks at relatively low levels. Historically, he said, sludge had been applied at concentrations greater than the levels now deemed risky by the EPA. “That implies there’s going be a lot of places where there might be an unacceptable risk,” he said.

The EPA hasn’t changed its policy of promoting sludge fertilizer, which has benefits along with the risks. It is rich in nutrients, and spreading it on fields cuts down on the need to incinerate it or put it in landfills, which would have other environmental costs. Using sludge fertilizer also reduces the use of synthetic fertilizers that are based on fossil fuels.

The EPA said that at farms that used contaminated sludge, the highest human risks involved drinking milk from pasture-raised cows raised on a contaminated farm, from drinking contaminated water, from eating eggs from pasture-raised hens or beef from cattle raised on contaminated land, or from eating fish from lakes and ponds contaminated with runoff.

Particularly at risk were households that live near or relied on products from a contaminated source, for example milk or beef from a family farm contaminated with PFAS from sewage sludge, the agency said. It said in certain conditions, risks exceeded the EPA’s acceptable thresholds by several orders of magnitude.

The general public, which is more likely to buy milk from a grocery store that sources its produce from many farms, was at less risk, the agency said. For its assessment, the EPA focused on the two most commonly detected types of forever chemicals, called PFOA and PFOS, though many others exist.

The Food and Drug Administration does not set limits on PFAS levels in food. Since 2019, however, the agency has tested nearly 1,300 samples and said the vast majority were free of the types of PFAS the agency is able to test for.

Some public health experts and advocacy groups have questioned the methodology, and the agency itself says that “PFAS exposure from food is an emerging area of science and there remains much we do not yet know.” Last year, Consumer Reports said it had detected PFAS in some milk, including organic brands. Packaging is another source of PFAS in food.