Verified by 
I recently attended a comprehensive review course on medical toxicology. The topics covered went from soup to nuts, assuming that the soup was made from hemlock and the nuts were actually pellets of rat poison. Among other things, the meeting included a session on chemical warfare agents. This covered poisons that had their heyday in World War One and others that, unfortunately, have continued to see use. It was a well established litany of toxicants. There was one substance, however, that I was unfamiliar with. Called “perfluoroisbutylene” but also going by the header PFIB, I thought I had misheard something when the lecturer mentioned it was also a potential byproduct of the common no-stick surface agent, Teflon.®
When I got a chance, I did a bit more research on PFIB. Indeed, PFIB can be released by Teflon® if it is heated to the right breakdown temperature, but the documentation for this is not so easy to find. Teflon® is a polymer whose long chain carbon backbone is studded with fluorine atoms, making it quite different from plastics that lack this component. Fluorine is in the halogen group of elements. This also includes chlorine, a far more common player in polymers, for example PVC. Teflon® has been on the market since the 1940s when it was introduced by DuPont; in Britain, Imperial Chemical Industries Ltd. followed suit with its own fluoropolymer, Fluon® soon after. By 1951, the first reports began to appear of a flu-like illness when fumes from these fluoropolymers were inhaled. The authors of these reports emphasized that this was a benign condition. This became a more sensitive issue in the early 1960s when fluoropolymer-coated no-stick pans first began to be marketed to the general consumer public.
DuPont, the U.S. manufacturer of the fluoropolymer, is aware of consumer angst on the subject of its product. Its website, under the header of “Key Safety Questions About Teflon® Nonstick Coatings” enumerates a number of reassurances, including “5. Are fumes from overheated nonstick coated cookware harmful to people? The fumes that are released by overheated polymer can produce symptoms referred to as ‘polymer fume fever’ — flu-like symptoms that are relatively quickly reversed in humans. Over the past 40 years, there have been only a few reported accounts of polymer fume fever as a result of severely overheating nonstick cookware.” (http://www2.dupont.com/Teflon/en_US/products/safety/key_questions.html). There’s no mention there of PFIB, although a full search of the DuPont web site does lead to a 2008 DuPont workplace environmental monitoring report in Dutch that mentions the chemical (http://www2.dupont.com/Dordrecht_Plant_Site/nl_NL/assets/downloads/milieuverslag.pdf).
If there wasn’t much on the corporate web site, I wondered what I might find on the National Library of Medicine (Medline) data base. It showed 26 entries for PFIB, but it was only the very last one on the list, from back in 1965, that seemed to touch on human illness: “Clinical aspects of acute poisoning with perfluoroisobutylene” (http://www.ncbi.nlm.nih.gov/pubmed/5870682). Unfortunately, the original article was in Russian and the journal issue it appeared in was not in my university’s library.
Luckily, I came across an English language synopsis of that Russian report. It turns out that it describes five patients (2 men and 3 women) accidently exposed to PFIB at work in a chemical factory. They each had been exposed briefly – most for only a few breaths. Yes all suffered severe lung injury, with two to eight week hospital stays among the survivors – one death occurred after two days. This summary was contained in a 2010 U.S. Environmental Protection Agency (EPA) report of PFIB trying to determine what a safe exposure level for the poison would be were it to be released to the public (http://www.epa.gov/oppt/aegl/pubs/perfluoroisobutylene_interim_sept_2010.pdf).
In 1964, the year before the Russian report, a letter to the New England Journal of Medicine described a case of a worker who also developed lung injury, albeit not as severe, when he spot welded too close to Teflon® blocks that were part of the item he was fabricating. The authors of the report did not have technical measurements but suggested that “octafluorisobutylene,” which is another synonym for PFIB, might have been released (http://www.nejm.org/doi/pdf/10.1056/NEJM196408132710708).
The 2010 EPA document does not mention this case. Nor does it allude to a 1997 report of another death in factory worker in Taiwan when a Teflon® extruding machine overheated. In fact, other than the Russian paper from the following year, the EPA refers to only one other human outbreak. It seems that in the mid-1970s, five other workers were briefly exposed to PFIB with resultant lung damage which was fatal for two of them. This experience has never been documented in the open medical literature as far as I am aware. The source of the EPA data was “a personal communication” from the DuPont Company dating back to 1976. The EPA safety recommendation from 2010 remains "interim."
