Most regulation on toxic PFAS chemicals is focused on drinking water, but PFAS can also get into the food supply through contaminated fertilizer.
Biosolids are a nutrient-rich and affordable fertilizer made with essentially recycled sewage. But if that sewage is contaminated by PFAS and is then used as fertilizer, it can end up contaminating farms, crops, and livestock.
At least one farm in Michigan has already been shut down because of contaminated biosolids, but the state said it’s an isolated incident.
Jennifer Bush is with the biosolids program at the Michigan Department of Environment, Great Lakes, and Energy. She said the state requires all wastewater treatment plants to test for 28 PFAS compounds and reduce levels of one compound, PFOS.
“We've seen that PFOS was tending to stick to solids, and PFOS in surface water has typically been the regulatory driver," Bush said. "So that is how we selected that for this interim strategy, but this is just what we're doing right now. It could be updated in the future.”
Bush said the state’s strategy has reduced PFOS levels by more than 90% in 4 of the 5 wastewater treatment plants that exceeded the state's levels of PFAS in their biosolids.
Plants with high levels of PFAS are not allowed to make biosolid fertilizers and are required to implement additional treatments for PFAS, targeting the source of PFOS.
