The former OSHA PEL for allyl chloride was a 1-ppm (3-mg/m3) 8-hour TWA; the proposed PEL was also 1 ppm, with a 15-minute STEL of 2 ppm. NIOSH (Ex. 8-47, Table N1) concurred with the proposed limits. In the final rule, OSHA is establishing an 8-hour TWA limit of 1 ppm and a STEL of 2 ppm for this substance; these limits are consistent with those of the ACGIH. Allyl chloride is a colorless liquid with an unpleasant, pungent odor.
Studies of animal exposures to allyl chloride indicate that this chemical is among the most toxic of the halogenated aliphatic hydrocarbons, producing mucous membrane irritation, mild narcosis, and, at higher concentrations, histologic lesions of the lungs and kidneys (Adams, Spencer, and Irish 1940/Ex. 1-584). Even single exposures lasting only a few minutes at concentrations between 1 and 100 mg/liter (332 to 32,000 ppm) caused mucous membrane irritation in various laboratory animals; at 8-ppm concentrations for five weeks, kidney and liver damage were observed (Adams, Spencer, and Irish 1940/Ex. 1-584). Further animal studies have confirmed liver and kidney pathology in many species (Torkelson, Wolf, Oyen, and Rowe 1959/Ex. 1-691), and female rats exhibited kidney pathology after exposure to 3 ppm for six months.
Exposures of 50 to 100 ppm for five minutes in humans caused eye and nose irritation, and five-minute exposures below 25 ppm have been associated with pulmonary irritation (Shell Chemical Corp. 1974, as cited in Ex. 150). Humans exposed to concentrations of 1 to 113 ppm showed abnormal liver test results (Hausler and Lenich 1968/Ex. 1-1035).
In a posthearing comment (Ex. 150, Comments on Allyl Chloride), NIOSH reported the results of a recent National Cancer Institute monograph (Santodonato et al. 1985, as cited in Ex. 150) showing that allyl chloride is a tumor initiator in mice and a mutagen in bacterial test systems. NIOSH (Ex. 150) and Drs. Grace Ziem and Barry Castleman (Ex. 114A) discussed recent epidemiological and clinical studies from the People's Republic of China (He et al. 1985, as cited in Exs. 114A and 150), which also found toxic polyneuropathy in workers exposed to between 2.6 and 6650 mg/m3 allyl chloride for durations ranging from 2.5 months to 6 years; in contrast, workers at another facility with allyl chloride exposures below 25 mg/m3 for 1 to 4.5 years had few neurological disorders, but 50 percent showed abnormal electroneuromyographic results. Animal studies confirm this substance's neuropathic potential (Ex. 114A and Ex. 150, Comments on Allyl Chloride).
The final rule establishes an 8-hour TWA limit of 1 ppm and a STEL of 2 ppm for allyl chloride. The Agency concludes that both TWA and STEL limits are necessary to protect workers from the significant risk of kidney and liver damage and neuropathic effects which constitute material health impairments and are potentially associated with the elevated short-term exposures to allyl chloride currently permitted by the 8-hour TWA alone.