US EPA

16073 

Journal Article 

Pulmonary effects induced by ultrafine PTFE particles 

Johnston, CJ; Finkelstein, JN; Mercer, P; Corson, N; Gelein, R; Oberdorster, G 

2000 

1 

Toxicology and Applied Pharmacology
ISSN: 0041-008X
EISSN: 1096-0333 

168 

3 

208-215 

English 

11042093 

10.1006/taap.2000.9037 

WOS:000166893700005 

PTFE (polytetrafluoroethylene) fumes consisting of large numbers of ultrafine (iii) particles arid low concentrations of gas-phase compounds can cause severe acute lung Injury. Our studies were designed to test three hypotheses: (I) uf PTFE fume particles are causally involved in the Induction of acute lung injury, (ii) uf PTFE elicit greater pulmonary effects than larger sized PTFE accumulation mode particles, and (111) preexposure to the uf PTFE fume particles will Induce tolerance. We used uf Teflon (PTFE) fumes (count median particle size ~ 16 nm) generated by heating PTFE in a tube furnace to 4860C to evaluate principles of ultrafine particle toxicity. Teflon fumes at ultrafine particle concentrations of 50 "mu"g/m3 were extremely toxic to rats when inhaled for only 15 min. We found that when generated in argon, the ultrafine Teflon particles alone are not toxic at these exposure conditions; neither were Teflon fume gas-phase constituents when generated in air. Only the combination of both phases when generated in air caused high toxicity, suggesting either the existence of radicals on the surface or a carrier mechanism of the ultrafine particles for adsorbed gas compounds. Aging of the fresh Teflon fumes for 3.5 mm led to a predicted coagulation to >100 nm particles which no longer caused toxicity in exposed animals. This result is consistent with a greater toxicity of ultrafine particles compared to accumulation mode particles, although changes in particle surface chemistry during the aging process may have contributed to the diminished toxicity. Furthermore, the pulmonary toxicity of the ultrafine Teflon fumes could be prevented by adapting the animals with short 5-mm exposures on 3 days prior to a 15-mm exposure. Messages encoding antioxidants and chemokines were increased substantially in nonadapted animals, yet were unaltered in adapted animals. This study shows the importance of preexposure history for the susceptibility to acute ultrafine particle effects.