--- Ronn!Blankenship <[EMAIL PROTECTED]> wrote: > Deborah Harrell wrote: > >--- The Fool <[EMAIL PROTECTED]> wrote:
> > > http://www.ewg.org/reports/toxicteflon/es.php > > > >"In two to five minutes on a conventional stovetop, > >cookware coated with Teflon and other non-stick > >surfaces can exceed temperatures at which the > coating breaks apart > > > My thought when I read that in the article was that > the only way one could > achieve the temperatures they cite would be to put > an _empty_ pot or pan on > the stovetop and turn the control up to "high". > Water, whether present as > a liquid or as moisture in the food, has such a high > specific heat capacity > that most of the heat energy will go into heating > the food, and since the > cookware cannot be at a substantially higher > temperature than its contents, > there is no way in a real cooking situation that the > cookware could reach > such a high temperature within "two to five minutes > on a conventional > stovetop." About the only way such temperatures are > likely to be reached > in an actual kitchen is if someone starts cooking > something and then goes > off and forgets about it and it boils dry (and > shortly afterwards the > shriek of the smoke alarm will probably refresh > their memory). But when you stir-fry things (which was what I used my pan for), you *do* heat it before you add the oil -- and for searing meat, the oil was near-smoking temperature (I have *no* idea what that is, but I think it's a lot more than water boiling!). And what about Teflon-coated grilling surfaces? Again, the surface is heated before food is put on. > > and emits toxic particles and gases > >linked to hundreds, perhaps thousands, of pet bird > >deaths > > > Documented, as in the example below? I didn't look on any veterinary sites, specifically, but did find these while looking for human illness [pans usually overheated]: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1119084&dopt=Abstract "Five cockatiels (Nymphicus hollandicus) died within 30 minutes following exposure to fumes from a frying pan coated with the "non-stick" plastic polytetrafluoroethylene (PTFE) that had accidentally overheated. Within an hour the owner developed symptoms of "polymer fume fever" but recovered in the next 24 hours. Clinical signs and post mortem lesions of the cockatiels are described and reference is made to the unusual susceptibility of parakeets to the pyrolysis products of frying pans coated with PTFE." This is a list of veterinary articles [but no linkage available :( ]: http://www.parrotparrot.com/birdhealth/teflon.htm > >and an unknown number of human illnesses each > >year, > > Which "unknown number" _could_ be zero: we don't > know without documentation. I found a few articles in PubMed, but no hard numbers. "Polymer-fume fever" is mentioned beginning in the '70s, but few abstracts were available, and those were more about industrial exposure. This Material Safety Data Sheet lists the toxic gases produced when PFTE (teflon) is heated over 290oC, but this is for an industrial lubricant: http://www.hp.com/hpinfo/community/environment/pdf/6040-1322.pdf Another: http://www.pcbfilm.com/msds/DF_9000_MSDS.pdf http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8272977&dopt=Abstract "Polymer fume fever and other fluorocarbon pyrolysis-related syndromes. Shusterman DJ. Division of Occupational and Environmental Medicine, University of California, San Francisco. Polymer fume fever usually occurs as a self-limited systemic illness with only minor pulmonary symptoms. Like metal fume fever, constitutional signs and symptoms typically present several hours after initial exposure, often giving rise to a misdiagnosis of viral "flu." ... When higher temperatures and/or longer durations of exposure are involved, significant pulmonary involvement, including radiographic consolidation, is a potential complication. Although a number of industrial outbreaks have implicated the smoking of contaminated cigarettes as a vehicle of exposure, any industrial or household activity in which PTFE is heated above 350-400 degrees C puts nearby workers or residents at risk of illness and is to be avoided without strict industrial hygiene controls." eMedicine has an interesting article on several types of smoke inhalation, including red phosphorus: http://www.emedicine.com/emerg/topic908.htm "...Pyrolysis of Teflon occurs at approximately 450�C. The mixture of particles that is produced contains a substance called perfluoroisobutylene (PFIB), which appears to be the main cause of toxicity in polymer fume fever. The ultrafine particles initiate a severe inflammatory response at low inhaled particle mass concentrations, which suggests an oxidative injury. PMNs may regulate the inflammatory process with cytokine and antioxidant expression. "PFIB particles cause an extremely rapid toxic effect on pulmonary tissues. Evidence of microscopic perivascular edema is observed within 5 minutes. Less intense exposures are followed by a latent period during which normal physiologic compensatory measures to control developing pulmonary edema ensue. Once these mechanisms are overcome, the time frame of which depends upon the degree of exposure, the clinical syndrome of fume fever follows. More intense exposures also may produce a chemical conjunctivitis. Hemorrhagic inflammation of the lungs also can occur." There seems to be quite a range of temperature at which breakdown is said to occur. > >From the 'offgas' page: > >"...The lowest temperature at which nonstick > coatings > >have been reported to kill birds in a peer-reviewed > >study is 396�F (202�C) [3]. In May 1998, poultry > >researchers at the University of Missouri recorded > 52 percent mortality in 2400 chicks within three days > >of the birds being placed into floor pens with new > >PTFE-coated heat lamp bulbs... All of the chicks > >examined after death had lung > >lesions and moderate to severe pulmonary edema > >consistent with �PTFE toxicosis.�..." > > > Completely different situation from cooking. > > Also, the above study specified that the bulbs used > were "new". I'd > suspect that the highest rate of offgasing would > occur when the bulbs were > brand new and drop off significantly after the more > volatile components > were exhausted. I wonder if they checked the rate > of offgasing as a > function of the number of hours the bulbs had been > used, and if they > repeated the study using bulbs which had been > "burned-in" for various > periods before being used in proximity to live > chicks? That would be a good thing to study. > >The list of offgas chemicals is quite a nasty cast > of characters. > > In what quantities, and what concentrations are > likely to occur in the air > in a typical kitchen at various distances from the > stove? No study has been done. The MDSSs I linked above are for industrial agents, so the concentrations listed may be nothing like what would happen in a kitchen. >From what I skimmed, with the range of Teflon products in automobile additives and military equipment, crashes/fires seem to be better-documented hazards. Debbi __________________________________ Do you Yahoo!? Yahoo! Calendar - Free online calendar with sync to Outlook(TM). http://calendar.yahoo.com _______________________________________________ http://www.mccmedia.com/mailman/listinfo/brin-l
