The Department of Defense found PFAS chemicals in drinking water wells near military installations in Duluth and Little Falls, Minnesota. The Defense Department is now investigating six sites in the state for PFAS contamination. PFAS is a class of industrial chemicals that do not break down in the environment and can build up in humans over time. They are associated with reproductive problems and some cancers. The Defense Department is testing water supplies near military sites that have used firefighting foams containing PFAS chemicals.