Sludge is a byproduct of the wastewater treatment process that’s a mix of human excrement and industrial waste, like PFAS, that’s discharged from industry’s pipes. Sludge disposal can be expensive so the waste management industry is increasingly repackaging it as fertilizer because excrement is rich in plant nutrients.
EWG found Ohio keeps the most precise records of any state, and sludge has been applied to 5% of its farmland since 2011. Extrapolating that across the rest of the country would mean about 20m acres are contaminated with at least some level of PFAS. Faber called the estimate “conservative”.
EPA records show over 19bn pounds of sludge has been used as fertilizer since 2016 in the 41 states where the agency tracks the amount of sludge that’s spread, but not the location. It’s estimated that 60% of the nation’s sludge is spread on cropland or other fields annually.
The consequences are evident in the only two states to consistently check sludge and farms for PFAS contamination. In Maine, PFAS-tainted fields have already forced several farms to shut down. The chemicals end up in crops and cattle, and the public health toll exacted by contaminated food in Maine is unknown. Meanwhile, the state is investigating about 700 more fields for PFAS pollution.