In this July 31, 2019 photo, Michael Wurts, superintendent of the Lapeer Wastewater Treatment Plant, stands in an adjacent cornfield where sludge from the plant was used as fertilizer, in Lapeer, Mich. State officials ordered a halt to the practice after toxic PFAS chemicals were detected in the sludge. Experts are raising concerns that sludge spread on agricultural fields around the U.S. could contaminate crops. About half of the 7 million tons of sludge generated each year is applied to farm fields and other lands. (AP Photo/John Flesher)