Pathologic findings in rats following inhalation of combustion products of polytetrafluoroethylene (PTFE).

Adult male Fischer 344 rats received single 30-min exposures to the aerosolized products of polytetrafluoroethylene (PTFE) heated to 595 degrees C. The concentrations of thermal degradation products of PTFE were at the LC50 dose of 0.045 mg/l for most rats, but some rats received doses ranging from 0.005 to 5.025 mg/l. Serial measurements of cardiopulmonary function were obtained and will be published subsequently. Necropsies were performed at 0, 2, 12, 24 and 36 h post-exposure, and a few rats were killed between 2 and 17 days. Signs of respiratory impairment were followed by death in some rats. Pathologic findings included focal hemorrhages, edema and fibrin deposition in the lungs. With time focal interstitial thickenings developed due to hypertrophy and hyperplasia of alveolar cells, and macrophages accumulated in alveoli. Thrombosis of pulmonary capillaries was common. Disseminated intravascular coagulation (DIC) occurred in 53% of test rats; its incidence and severity were positively related to the degree of pulmonary damage. Renal infarcts were common due to DIC. No lesions were seen in kidneys or other tissue (except lung and thymus) unless they were affected with DIC. Thymic lymphocytes underwent necrosis in many test and some vehical (warm air) control rats, possibly due to stress. The finding of DIC in PTFE combustion product exposure has not been reported to our knowledge. The toxicity of the thermal degradation products of PTFE requires further study, especially relative to induction of DIC.