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Sewage sludge and wastewater treatment plants are major sources of Pfas water pollution, new research finds, raising questions about whether the US is safely managing its waste.
A first-of-its-kind study tested rivers bordering 32 sewage sludge sites, including wastewater treatment plants and fields where the substance is spread as fertilizer – it found concerning levels of Pfas around all but one.
The study is the first to sample water up- and downstream from sites, and to test around the country. It found the levels downstream were higher for at least one Pfas compound 95% of the time, suggesting that the sludge sites are behind the increased pollution levels.
“We have an indication of very widespread problems and significant exposures that people are going to be facing,” said Kelly Hunter Foster, an environmental attorney with the Waterkeeper Alliance, which conducted the study.
Pfas are a class of about 15,000 compounds that are dubbed “forever chemicals” because they do not naturally break down, and accumulate in the human body and environment. The chemicals are linked to a range of serious health problems like cancer, liver disease, kidney issues, high cholesterol, birth defects and decreased immunity.
Sludge is a mix of human and industrial waste that is a byproduct of the wastewater treatment process. Its disposal is expensive, and the Environmental Protection Agency (EPA) allows it to be spread on cropland as “biosolid” fertilizer because it is also rich in plant nutrients.
But public health advocates have blasted the practice because the nation spends billions of dollars annually treating water only to take the toxic byproduct, insert it into the food supply and re-pollute water.
Wastewater treatment plants’ effluent, or allegedly clean water that they spit back into water systems, often contain high levels of Pfas.
Most of the levels far exceeded the EPA’s draft guidance for Pfas in surface waters, which is as low as 0.0009 parts per trillion for PFOA, one of the most common and dangerous types of compounds.
The authors looked at water in 19 states, and found the highest levels in Detroit’s Rouge River, which showed 44ppt of PFOA; North Carolina’s Haw River; South Carolina’s Pocotaligo River and Maryland’s Potomac River.
The largest increase around a wastewater plant was found in the Rouge River, where Detroit’s mammoth facility spits Pfas-tainted effluent. The chemicals’ levels jumped by 146% to about 80ppt for all Pfas. The Pocotaligo, Haw, and Santa Ana River in southern California saw similar spikes.
The largest increase around a field on which sewage sludge was spread was found in the Dragoon Creek near Spokane, Washington, where total Pfas levels jumped from about 0.63 ppt to about 33ppt, an increase of over 5,100%.
The EPA has long resisted calls to ban the spreading of sewage sludge on agricultural fields, though a 2024 lawsuit that alleges Clean Water Act violations could force some regulatory action. The Trump administration has scrapped the rulemaking process for industrial discharges of Pfas that Joe Biden’s EPA began. That would have forced treatment plants to rein in their pollution.
