Fluorotrichloromethane (trichlorofluoromethane), also known as FC-11, is a member of a large family of chemicals, the chlorofluorocarbons. The former OSHA PEL was an 8-hour TWA of 1000 ppm. The proposed PEL was a ceiling of 1000 ppm and NIOSH (Ex. 8-47, Table N1) supported the proposal. The final rule establishes this limit. At ordinary temperatures, FC-11 is a noncombustible, colorless liquid or gas.
Inhalation of large doses of FC-11 has caused cardiac sensitization and death in humans. Experimental mice that inhaled aerosol containing 10 percent FC-11 exhibited cardiac arrhythmias. In the same study, dogs that inhaled aerosol containing 2.5 percent FC-11 had decreased myocardial function; monkeys that inhaled an aerosol containing 5 percent FC-11 developed tachycardia and hypotension (Drinking Water and Health, National Research Council 1977).
Exposure to 5000 ppm FC-11 has induced cardiac sensitization and arrhythmia in dogs that were intravenously injected with epinephrine (Reinhardt, Azar, Maxfield, Smith, and Mullin 1971/Ex. 1-78). Jenkins, Jones, Coon, and Siegel (1970/Ex. 1-95) found that four species of animals (monkeys, dogs, rats, and guinea pigs) suffered no ill effects after 90 days of continuous exposure to 1000 ppm of FC-11. Other than those submitted by NIOSH, OSHA received no comments on FC-11.
The cardiac sensitization exhibited by FC-11-exposed animals is an acute effect. OSHA's former 1000-ppm TWA PEL would permit workers to be exposed to short-term concentrations of FC-11 that are sufficiently high to sensitize the heart to sympathomimetic amines; OSHA considers this effect to be a material impairment of health. Accordingly, OSHA concludes that, at the former limit, workers are at significant risk of experiencing arrhythmia. Revising this limit to a 1000-ppm ceiling limit will substantially reduce this significant risk of cardiac sensitization.