For more than 20 years, the eastern Michigan town of Lapeer sent leftover sludge from its sewage treatment plant to area farms, supplying them with high-quality, free fertilizer while avoiding the expense of disposal elsewhere.
But state inspectors ordered a halt to the practice in 2017 after learning the material was laced with one of the potentially harmful chemicals known collectively as PFAS, which are turning up in drinking water and some foods across the U.S.
Now, the city of 8,800 expects to pay about $3 million to have the waste treated at another facility and the leftover solids shipped to a landfill. Testing has found elevated PFAS levels in just one field where the sludge was spread, but farmers have lost an economical fertilizer source and hope more contamination doesn’t turn up.
“I feel bad for them,” said Michael Wurts, superintendent of the waste treatment plant, who ruefully recalls promoting sludge as an agricultural soil additive to growers in the community. “The city didn’t do anything malicious. We had no clue this was going on.”
Lapeer isn’t alone. For decades, sewage sludge from thousands of wastewater treatment plants has been used nationwide as cropland fertilizer. It’s also applied to sports fields, golf courses and backyard gardens.
About half of the 7 million tons generated annually in the U.S. is applied to farm fields and other lands, the Environmental Protection Agency says. While the sludge offers farmers a cheap source of fertilizer, there long have been concerns about contaminants in the material — and attention of late has turned to perfluoroalkyl and polyfluoroalkyl substances, or PFAS.
The city of Marinette, Wisconsin, has stopped distributing sewage waste, also called “biosolids,” to farms after getting high PFAS readings. In Maine, a dairy farm was forced to shut down after sludge spread on the land was linked to high levels of PFAS in the milk.
“It’s been devastating. We kind of get treated like we are criminals,” said Stoneridge Farm’s Fred Stone, whose blood has also tested high for PFAS from what he believes was drinking contaminated water and milk over the years.
The concern is that certain PFAS chemicals, which studies have associated with increased risk of cancer and damage to organs such as the liver and thyroid, could be absorbed by crops grown in soils treated with polluted sludge and wind up in foods. The Food and Drug Administration this year reported finding substantial levels of the chemicals in random samples of grocery store meats, dairy products, seafood and even off-the-shelf chocolate cake, although the study did not mention any connection to sewage waste.