FC-113 has very low acute oral toxicity, with an LD50 in rats of 43 g/kg (Michaelson and Huntsman, 1964). Its lethal dose after application to the skin of rabbits is greater than 11 g/kg, the largest feasible dose. Mild irritation results from contact with the skin and eyes (Haskell Laboratory, 1963; Reinke, 1962).
Exposure to FC-113 at 50,000–60,000 ppm has proved lethal to rats after 4 h. Signs of toxicity indicative of CNS involvement were incoordination, tremors, irregular respiration, and convulsions (Bodganowicz, 1973; Dashiell, 1971; Sarver, 1971).
Rats were exposed at an average concentration of 2,520 ppm, 7 h/d, 5 d/wk, for 6 wk (Limperos, 1954). No signs of toxicity were seen throughout the experiment.
Other groups of laboratory animals were similarly exposed at up to 5,100 ppm without effect (Carter et al., 1970; Philadelphia Naval Shipyard, 1952; Steinberg et al., 1969). In a limited study involving six rats exposed at 12,000 ppm for up to 24 mo, a slight sleepiness was observed and disappeared immediately after daily exposure stopped (Desoille et al., 1968). Rats were exposed by inhalation for 6 hr a day, 5 d/wk, for 104 wk. Exposures were at 0, 2,000, 10,000, and 20,000 ppm (v/v). No significant toxic effects were observed, and no evidence of carcinogenicity was seen (C.F.Reinhardt, personal communication).
FC-113, like other chlorofluorocarbons and hydrocarbons, is capable of sensitizing the beagle heart to exogenous epinephrine in standard 5-min cardiac-sensitization screening studies. A concentration of 5,000 ppm can sensitize 25–35% of exposed dogs; 2,500 ppm is ineffective (Clark and Tinston, 1973; Reinhardt et al., 1973). However, dogs exposed while running on a treadmill (to increase their own epinephrine concentration) were not sensitized at concentrations up to 20,000 ppm (Mullin et al., 1971; Trochimowicz et al., 1974).
FC-113 is analogous to FC-11 with regard to its pharmacokinetics and metabolism. It has a short half-life in the body, is not metabolized to any significant extent, and is rapidly expelled through the lungs upon removal from exposure (C.F.Reinhardt, personal communication).
The ACGIH TLV-TWA and the OSHA federal standard (ACGIH, 1983; OSHA, 1983) for FC-113 are both 1,000 ppm. ACGIH recommended a TLV-STEL for 15-min excursions of 1,250 ppm (ACGIH, 1980). The TLV-TWA was recommended on the basis of a belief that it would provide a margin of safety for systemic effects and an adequate margin against cardiac sensitization.
The previous EELs and CEL were established by the Committee in 1969. On the basis of 5-min cardiac-sensitization screening tests with dogs (which showed no effects at 2,500 ppm and positive findings at 5,000 ppm), an absence of effects in unexcited humans exposed at 1,500 ppm for 1.5 h, but changes in manual dexterity at 2,500 ppm for 1.5 h, the