Biosolid applications are among the potential culprits that contaminated the drinking water at Robinson Elementary School and a total of 34 wells tested in the area.
According to the DEQ, firefighting foam, undocumented dump sites and materials from the M-231 highway construction project are other possible sources.
Biosolids are treated sewage sludge containing organic and inorganic material. Produced as a byproduct at sewage treatment plants, they are commonly used as fertilizer on crop-producing farms, and have been around since the early 1990s.
While biosolids have not been linked to any of the 36 sites of PFAS contamination currently under investigation by the DEQ in Michigan, the applications could contain the “forever chemicals” linked to numerous health hazards and found throughout the environment.
According to the DEQ’s MiWaters database, there is a biosolid application site located north of Buchanan Street, just west of M-231, in Robinson Township. Another site is located near the corner of Buchanan and 104th Avenue, where PFAS has been detected in dozens of wells.
There are several biosolid sites located throughout Ottawa County.
Last month, Michigan’s Science Advisory Panel recommended the DEQ conduct research to find out where the chemicals go when a biosolid is applied to land.
There is a potential for PFAS to enter groundwater near biosolid applications, according to Courtney Carignan, an environmental health scientist at Michigan State University who studies PFAS contamination.
While biosolids provide nutrients to the soil, Carignan explained, some chemicals do not break down during the treatment process. There are standards set for biosolids that account for various heavy metals and chemicals, but not for PFAS.
“Most pollutants like to be bound to soils and don’t easily enter drinking water,” she said. “Because of their unique chemistry, PFAS migrate very easily from soil to groundwater.”
Carignan helped publish a study that showed proximity to a wastewater treatment plant is among the top predictors for PFAS contamination in water supplies. Other predictors are proximity to military fire training areas and industrial sites.
Michigan has not established standards for PFAS in drinking water, but outgoing Gov. Rick Snyder signed a law last month that requires the state set a standard not lower than the U.S. Environmental Protection Agency’s health advisory limit of 70 parts per trillion (ppt) for the two chemicals PFOA and PFOS.
Several states have set limits lower than the EPA limit, Carignan noted.
Michigan lacks standards for PFAS and food products, but Carignan said researchers are looking at the potential for the substances transferring to plants and animals.
“When a ‘forever chemical’ like PFAS is in the water, it can also get into our food,” she said.
Michigan is among the first states to investigate the contaminants statewide. Products with PFAS were commonly produced in numerous industries, and are present in water-repellent materials, nonstick cookware, fast-food wrappers and firefighting foam. The chemicals have been used worldwide.