DuPont and 3M had evidence of PFAS toxicity as early as the 1960s. In 1980, two of eight pregnant employees exposed to C8 gave birth to children with birth defects — neither company disclosed this. 3M conducted toxicity studies in the 1970s but didn't share results with the EPA for over 20 years. By the 1990s, DuPont knew PFOA caused multiple types of cancerous tumors. The chemical industry used tobacco-style tactics to delay public awareness. 3M settled for $10.3 billion.