Spin adducts are observed when the unfiltered smoke produced during the aerobic pyrolysis of perfluoro polymers (PFP) is bubbled through a solution of the ESR spin trap alpha-phenyl-N-tert-butylnitrone (PBN). The spin adducts include those from an oxy radical and the fluorine atom, and in addition the spin trap is oxidized to PBNOx. The spin adduct of a chlorine atom also is observed, presumably because of chlorine-containing impurities in the polymers. Tetrafluoroethylene is produced during the pyrolysis of PFP; therefore, we subjected tetrafluoroethylene to the same pyrolysis as was used for PFP, and we observe the same series of spin adducts. We suggest that the spin adducts formed from the whole, unfiltered smoke from PFP smoke may result both from free radicals that form during the pyrolysis of PFP and from the oligomerization of the tetrafluoroethylene produced during the pyrolysis. These spin-trapping results support the theory that reactive free radicals are present in PFP smoke and may contribute to PFP smoke toxicity.

Electron spin resonance (ESR) analysis at room temperature of the particles produced during the aerobic pyrolysis of perfluoro polymers (PFP) shows the presence of end-chain peroxyl radicals. These radicals, which would normally have lifetimes of several seconds at most, are stabilized by being immobilized in the particles and decay at a rate of about 20%/day. Normally, radicals with this stability would not be expected to be reactive; however, these peroxyl radicals react with 3-chloropropene, with iodine in benzene, with methyl linoleate in methanol, and with aqueous liposomes from soy phosphatidylcholine. Also, stable radicals of this sort would not be expected to give spin adducts; however, when the particles are suspended in a benzene solution containing alpha-phenyl-N-tert-butylnitrone (PBN), they react to give the same series of spin adducts that are detected when the unfiltered smoke from the oxidative pyrolysis of perfluoro polymers is bubbled directly into PBN solutions. This appears to be the first report of the reaction of radicals entrapped in a solid with a spin trap. The nitroxide species produced by the PBN-particle reaction include a fluorine atom spin adduct, an oxy radical adduct, and benzoyl tert-butyl nitroxide (PBNOx), the oxidation product of the spin trap; all of these appear to arise from reaction of the particle-bound peroxyl radicals with the spin trap. Because the particles are in the highly respirable range (down to 0.01 micron), these entrapped peroxyl radicals may be carried deep within the lung when fumes from PFP pyrolysis are inhaled and would be expected to place an oxidative burden on the lung.(ABSTRACT TRUNCATED AT 250 WORDS)

Submicrometer solid-particle (fume) aerosols with up to about 10(8) particles/cm3 are formed when dilute vapors of low molecular weight (MW) (ca. 5000-10,000) perfluoro polymers condense in air. The aerosol (e.g., 0.2 mg/m3) formed from these vapors is highly toxic to laboratory rats by inhalation (30-min exposure) when fresh but loses toxicity in minutes, apparently owing to coagulation. These fumes may result from (a) pyrolysis of tetrafluoroethene homopolymer or tetrafluoroethene-hexafluoropropene copolymer or (b) evaporation, at 200-320 degrees C, of isolated low MW polymer or low MW polymer present in perfluoro polymer resins. Some perfluoro polymer fume aerosols contain reactive functional groups, but others without detectable reactive groups are at least as toxic.