Inhalation toxicity of sulfuryl fluoride in rats and rabbits

The inhalation toxicity of the structural fumigant sulfuryl fluoride (SO2F2) was evaluated in rats and rabbits. Exposures for a preliminary 2-week study were 6 hr/day, 5 days/week, to 0, 100, 300, or 600 ppm SO2F2. Nine of ten rats at 600 ppm died or were moribund between the second and sixth exposures. Extensive kidney lesions were present in all rats exposed to 600 ppm, whereas only minimal renal changes were noted in rats at 300 ppm. Upper and lower respiratory tissues were inflamed in the single rat that survived the 2-week exposure to 600 ppm. Rabbits exposed to 600 ppm SO2F2 were hyperactive and one animal had a convulsion. Exposure to 300 or 600 ppm for 2 weeks resulted in vacuolation and/or malacia in the cerebrum of all rabbits and most of these rabbits also had moderate inflammation of nasal tissues; a few rabbits at 600 ppm had inflammation of the trachea or bronchi. A subsequent 13-week study evaluated rats and rabbits exposed to 0, 30, 100, or 300 ppm SO2F2 (337 ppm TWA for rabbits). Rabbits initially were exposed to a high concentration of 600 ppm; however, convulsions were noted in two animals after nine exposures and the concentration subsequently was reduced to 300 ppm. Vacuolation and/or malacia were observed in the cerebrum of all rabbits at the highest concentration; one rabbit exposed to 100 ppm also had cerebral vacuolation. Rabbits at the highest concentration, as well as one rabbit exposed to 100 ppm, had inflammation of the nasal tissues. Rats exposed to 300 ppm SO2F2 for 13 weeks had mottled incisor teeth, minimal renal effects, pulmonary histiocytosis, inflammation of nasal tissues, and cerebral vacuolation. Also, rats exposed to 100 ppm SO2F2 for 13 weeks had mottled teeth. Fluoride toxicity was suggested by mottled teeth in rats as well as elevation of serum fluoride levels in rats and rabbits exposed to SO2F2 for 13 weeks. Although repeated exposure of rats and rabbits to 100-600 ppm SO2F2 resulted in toxicity of the kidneys (rats only), brain, and respiratory system, no effects were detected in animals exposed to 30 ppm for 13 weeks.