What to Know About ‘Forever Chemicals’ in Sludge Fertilizer

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Societies have used nutrient-rich human waste as fertilizer for centuries. But sewage today is different. That’s because we’ve flooded the environment with complex chemicals that can end up in our sewage and wastewater and can’t be easily removed.

The contaminated waste is at the root of recent concerns over the “forever chemicals” that have been found in fertilizer made from sewage sludge, which is a byproduct of wastewater treatment.

The Environmental Protection Agency has long promoted reusing that sludge on the nation’s farmland, a practice that has several benefits. Sewage sludge is rich in nutrients, and using it on farms keeps it away from landfills or from being incinerated. Using sludge also means farmers need to use less synthetic fertilizer made from fossil fuel.

But for the first time, the E.P.A. said on Tuesday that the “forever chemicals” in sewage sludge can pose human health risks.

Its extensive draft risk assessment found that, while the general food supply isn’t threatened, the risk from contaminated fertilizer could in some cases exceed the E.P.A.’s safety thresholds “sometimes by several orders of magnitude.”

The dangers of PFAS

The E.P.A.’s report follows a growing body of research that has found that sludge can be contaminated with human-made “forever chemicals” known as per- and polyfluoroalkyl substances, or PFAS, which are used in a wide range of household items such as nonstick cookware, waterproof clothing and stain-resistant carpets.

The chemicals, which are linked to a range of illnesses and an increased risk of cancer, do not break down in the environment. When tainted sludge is used as fertilizer on farmland, it can contaminate the soil, groundwater, crops and livestock.

Last year, I reported that as early as 2000, the chemicals giant 3M, which for decades has manufactured PFAS, found that forever chemicals were turning up in sludge samples from municipal wastewater plants across the country. In 2003, 3M told the E.P.A. of its findings.

Yet the E.P.A. has continued to encourage the use of sludge from treated wastewater as inexpensive fertilizer with no limit on how much PFAS it can contain, and farmers across the country have been discovering PFAS on their land. The agency’s new risk assessment could change that. If finalized, it could mark what would be the first step toward regulating PFAS in sludge.

The risks to consumers

In the meantime, what are the risks? The E.P.A. said its analysis did not suggest there was danger to the general food supply.

Instead, the most at risk are households that live near, or rely on, products from a contaminated source — for example, I reported last year about a family that experienced health issues after eating milk and beef from a family farm contaminated with PFAS from sewage sludge.

The general public, which is more likely to buy milk from a grocery store that buys its products from many farms, faced fewer risks, the agency said.

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 of food and said a vast majority were free of the types of PFAS the agency is able to screen for.

Some public health experts and advocacy groups have questioned the testing 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.” Consumer Reports said last year that it had detected PFAS in some milk, including milk from organic brands. Packaging is another potential source of PFAS in food.

Some states have started to take their own measures. Maine, in particular, banned the use of sewage sludge on agricultural fields in 2022 and remains the only state to have done so.

Still, an outright ban on the use of sludge as fertilizer would bring its own problems. Wastewater sludge still needs somewhere to go. Since Maine’s ban, some wastewater treatment plants have said they have been forced to ship sewage sludge out of state.

“We can’t stop the production of sewage sludge. But we can stop PFAS from getting in that sewage sludge,” said Kyla Bennett, director of science policy at the Public Employees for Environmental Responsibility, an advocacy group that is working with Texas ranchers affected by contaminated sludge. “That’s going to be a herculean task.”

More climate news:

• Global sales of electric vehicles, including plug-in hybrids, rose 25 percent last year, Reuters reports.

• An advocacy group that has promoted the benefits of natural gas for communities of color has ties to the natural gas industry, The Washington Post reports.

• “Landman,” the TV series set in Texas oil fields co-created by Taylor Sheridan, is full of misinformation about fossil fuels renewable energy, a columnist for The Los Angeles Times argues.

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