July 20, 2001.
Dear All,
We received this important response to our piece on Teflon (IFIN #227) from FAN member Dr. Vyvyan Howard. Also George Glasser points out that Taves discovered the presence of PFOS/PFOA in the blood in 1976 and it was Venkatswarlu who was monitoring PFOS (Scotchguard) in the blood of workers at 3M, and it was his work which was published in 1990, JADA International Symposium on Fluoride. Paul Connett.
Dear Paul,
It seems that it may be worse than you have portrayed. When you heat PTFE up to the sort of temperatures that you get in "state of the art" municipal waste incinerators (eg 800C) you get the formation of CFCs, the major greenhouse gas that has been banned as a refrigerant. When one considers the amount of clothing and fabric that is coated with PTFE (most artificial fibres described as 'breathable') this could have major implications for waste incineration. Another aspect of heating PTFE in cooking utensils is the following: A standard method of producing an aerosol of ultrafine particles is to heat PTFE up to 480C. This produces some gas-phase products, mainly HF. If PTFE is further heated up to 500C other gas-phase products are produced, including perfluoroisobutylene and others, which are highly toxic. This is described in a paper by Obersdorster G, 'Toxicology of ultrafine particles: in vivo studies'. Trans. Phil. R. Soc. Lond. A (2000) 358: 2719-2740. The rest of that issue of Trans Phil is dedicated to ultrafine particles. Ultrafine particles are defined as those below 0.1 microns (100nm) and it is being demostrated that these have a toxicity all of their own, which seems to be associated with their high chemical reactivity (that after all is how we make heterogeneous catalysts!). I have recently edited a book on this (Particulate Matter: properties and effects upon health. Eds R L Maynard and C V Howard. Bios, Oxford (1999). ISBN 185996172X (Sorry about the self advertising)). However it is appearing that the majority of the toxicity of particulate aerosols may be attributable to the ultra-fine fraction. This could have major implications for the use of PTFE coated cookware in the home and industry. I am not aware that the tie up between the routine use of these materials, ultrafine particle production and possible health effects has yet been made. Best wishes, Vyvyan
Dr C. Vyvyan Howard. MB. ChB. PhD. FRCPath. Developmental Toxico-Pathology Group, Mulberry Street, University of Liverpool, Liverpool L69 7ZA Tel: + 44 (0)151 794 3854 Fax: + 44 (0)151 794 3855