 20,000 firefighters who've developed cancer are suing the makers of chemical foam, including DuPont, 3M, and Honeywell. Sarah Lee Kessler reports. Twelve companies that make firefighting foam and heavy pants worn to fight fires are being sued. The Environmental Litigation Group says that equipment contains high levels of PFAS, or so-called forever chemicals. New Jersey firefighters say they repeatedly sprayed PFAS.