News that the Environmental Protection Agency pressured the federal Agency for Toxic Substances and Disease Registry to suppress a study showing PFAS chemicals to be even more dangerous than previously thought drew outrage this spring. The EPA pressure delayed the studys publication for several months. But the dangers presented by these industrial chemicals have been known for decades, not just a few months or years. A lawsuit filed by Minnesota against 3M, the company that first developed and sold PFOS and PFOA, the two best-known PFAS compounds, has revealed that the company knew that these chemicals were accumulating in peoples blood for more than 40 years. 3M researchers documented the chemicals in fish, just as the Michigan scientist did, but they did so back in the 1970s. The suit, which the Minnesota attorney general filed in 2010, charges that 3M polluted groundwater with PFAS compounds and knew or should have known that these chemicals harm human health and the environment, and result in injury, destruction, and loss of natural resources of the State. The complaint argues that 3M acted with a deliberate disregard for the high risk of injury to the citizens and wildlife of Minnesota. 3M settled the suit for $850 million in February, and the Minnesota Attorney Generals Office released a large set of documents including internal studies, memos, emails, and research reports detailing what 3M knew about the chemicals harms.