The City of La Crosse claims products containing PFAS chemicals caused contamination of public and private wells in a lawsuit filed against nearly two dozen chemical companies on Thursday. The suit filed by Milwaukee-based law firm Crueger Dickinson and firm Napoli Shkolnik in La Crosse County Circuit Court alleges that cities like La Crosse used aqueous firefighting foams (AFFF) that contained perfluoroalkyl and polyfluoroalkyl substances (PFAS) for decades without any knowledge of the harmful effects the chemicals pose to public health. They say chemical manufacturers like 3M, DuPont and Tyco Fire Products knew of the risks associated with PFAS. The lawsuit targets 23 companies that include 3M, DuPont and Chemours, as well as eight manufacturers of firefighting foams known to contain PFAS. PFAS chemicals have raised concerns because they don't break down easily in the environment.