Cadillac residents had been on edge for months about the discovery of toxic “forever chemicals” in dozens of private drinking water wells, when state officials recently delivered some unexpected news.

The most logical culprit, many had believed, was a local industrial park with a troubled history. After all, metal platers and automotive manufacturers had already polluted the park with volatile organic compounds and hexavalent chromium. Those same industries have been linked to PFAS contamination in other Michigan communities. And Cadillac’s first PFAS-positive well test had come from a home within the industrial park. 

But a state analysis of water from 70 neighboring wells told another story: Some residents, schools and businesses may have unwittingly tainted their own drinking water, through years of flushing common household products down the drain and into septic systems that allowed tainted sewage to quietly infiltrate the aquifer.

Chemicals found in sewage sludge that some farmers use to fertilize fields and pastures can pose a threat to human and animal health, the US Environmental Protection Agency said Tuesday.

Exposure to food from farms that use the sewage sludge can raise a person’s risk of developing cancer or other health conditions, it said. Under certain conditions, the human health risks from sludge used on farms are “several orders of magnitude” above what the EPA considers acceptable, the agency said.

While the EPA said Tuesday that the general food supply is not at risk, these “forever chemicals,” as they are sometimes called, can pose a threat to the health of people who drink a lot of milk or eat beef from farms that use the sludge.

The specific chemicals, perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), belong to a larger class of per- and polyfluoroalkyl compounds (PFAS) and are considered “forever chemicals” because they take such a long time to break down in the environment and in the human body.

Since the passage of the Clean Water Act in 1972, many wastewater treatment plants have operated with a simple environmental trade-off — they treat water from population centers, industrial sources, landfills and elsewhere, and the leftover solids can be sent to farms to use as fertilizer.

But that arrangement has neared a breaking point in recent years, strained by new understanding of pollutants like PFAS, or per- and polyfluoroalkyl substances. In communities around the U.S., the chemicals are exiting the plants via its sludge, known as biosolids, and in some cases contaminating farmland. 


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