The former OSHA limit for sulfuryl fluoride was 5 ppm as an 8-hour TWA. The ACGIH has a limit of 5 ppm as a TWA and adds a STEL of 10 ppm. The proposal retained the 8-hour TWA PEL of 5 ppm for sulfuryl fluoride and added a STEL of 10 ppm. NIOSH (Ex. 8-47, Table N1) concurred that these limits are appropriate, and they are established in the final rule. Sulfuryl fluoride is a colorless gas with a sulfide odor.
When selecting this limit, the ACGIH took into consideration the fact that, compared with hydrogen fluoride (TLV-TWA ceiling of 3 ppm), only a small portion of the inhaled gas is retained and converted to inorganic fluorides. In extensive animal studies conducted by the Dow Chemical Company (1962 and 1970, as cited in ACGIH 1986/Ex. 1-3, p. 546), sulfuryl fluoride was determined to exhibit one-half to one-third the acute inhalation toxicity of methyl bromide. Acute exposures of animals resulted in tremors that later developed into severe convulsions. Pulmonary edema was seen in laboratory animals after a single severe exposure. Repeated exposures of rats, guinea pigs, and mice to 20 ppm sulfuryl fluoride for seven hours per day produced both kidney and lung injury after six months. Some evidence of fluorosis was observed in the incisors of mice, but not in the teeth of the rats or guinea pigs (Dow Chemical Company 1962 and 1970, as cited in ACGIH 1986/Ex. 1-3, p. 546).
A report by Taxay (1966/Ex. 1-577) that examined an incident of workplace exposure to sulfuryl fluoride noted that abdominal pain, nausea, vomiting, and itching were the major symptoms. On the day following exposure, the serum of the affected worker tested positive for fluoride. No comment, other than NIOSH's, was submitted on this substance.
In the final rule, OSHA is retaining the 8-hour TWA limit of 5 ppm and adding a STEL of 10 ppm for sulfuryl fluoride; these limits are based on this substance's fluorine content. The Agency concludes that these limits will protect workers against the significant risks of kidney and lung injury and of fluorosis, which together constitute material health impairments that are associated with exposure to this substance at levels above the 8-hour TWA limit.