In 1953, a paper developed for cigarette maker RJ Reynolds detailed possible cancer-causing agents in tobacco, but the document would remain hidden from public view for decades. In the interim, the industry told the public: "We don't accept the idea that there are harmful agents in tobacco." The chemical industry, it seemed, took note. Just a few years later, DuPont scientists found PFAS enlarged lab rats' livers and likely caused birth defects in workers. Still, the company told its employees the cancer-linked compounds are "about as toxic as table salt". Like the tobacco industry before it, the chemical industry managed to keep PFAS's health risks hidden from the public for decades. A new peer-reviewed study dissecting PFAS producers' public relations strategies provides a smoking gun timeline composed of industry studies and comments from DuPont and 3M officials showing they knew the dangers, but publicly insisted the chemicals were safe. Between 1961 and 2006, the authors identified dozens of instances where DuPont or 3M scientists discovered or acknowledged PFAS toxicity internally, but did not publish the findings or report them to the EPA, as required under federal law. DuPont's chief toxicologist in 1961 found rats' livers enlarged at very low doses of exposure, a health impact recognized as "the most sensitive sign of toxicity." The report recommended PFAS be handled "with extreme care" and that "contact with the skin should be strictly avoided."