BOSTON — Massachusetts has sued more than a dozen companies involved in the manufacture or marketing of so-called forever chemicals, alleging they knowingly polluted the environment and endangered public health, state Attorney General Maura Healey said Wednesday. The companies have known about the dangers of PFAS chemicals — found in firefighting foam and consumer products — for years and violated both federal and state environmental laws, she said at a news conference. “For decades, these manufacturers knew about the serious risks highly toxic PFAS chemicals pose to public health, the environment, and our drinking water — yet they did nothing about it,” Healey said. The chemicals have polluted more than 126 public drinking water systems in 86 Massachusetts communities, the state says.