(With added comment clarifying the relationship between PFOA and Teflon, at bottom.) Scientists knew the danger, but the bosses kept it quiet: "Concerns about the safety of Teflon, C8 (perflouroctanoic acid/PFOA), and other long-chain perfluorinated chemicals first came to wide public attention more than a decade ago, but the story of DuPont's long involvement with C8 has never been fully told," before company documents were made public in a long-running court case, writes Sharon Lerner at The Intercept here.

"Over the past 15 years, as lawyers have been waging an epic legal battle — culminating as the first of approximately 3,500 personal injury claims comes to trial in September — a long trail of documents has emerged that casts new light on C8, DuPont, and the fitful attempts of the Environmental Protection Agency to deal with a threat to public health.

"This story is based on many of those documents, which until they were entered into evidence for these trials had been hidden away in DuPont's files. Among them are write-ups of experiments on rats, dogs, and rabbits showing that C8 was associated with a wide range of health problems that sometimes killed the lab animals.

"Many thousands of pages of expert testimony and depositions have been prepared by attorneys for the plaintiffs. And through the process of legal discovery they have uncovered hundreds of internal communications revealing that DuPont employees for many years suspected that C8 was harmful and yet continued to use it, putting the company's workers and the people who lived near its plants at risk." 

As I wrote here, and here, DuPont plant sites with large known (and often unmeasured) contamination problems were spun off by DuPont into a new company, Chemours, last month, leaving activists to worry whether Chemours will have the resources to pay damages for decades-old DuPont contamination. 

UPDATE: A scientist (who used to live near DuPont's Edge Moor works) writes to clarify the relationship between PFOA and Teflon: "PFOA is a polymerization emulsifier used in the manufacture of Teflon, or polytetrafluoroethylene (PTFE) and related fluoropolymers. The reason that's a problem is that it is not a part of the polymer and is water soluble, unlike the polymer. The fact that it is water soluble leads to its being bioconcentrated in the food chain. It becomes a problem in the food chain because it is also fat soluble (the perfluorination leads to that) and that's why it bioconcentrates and stays in the human body. Once inside, it exerts its toxic effect. Simply put, it's a processing aid, not a part of the Teflon polymer."