OSHA comments from the January 19, 1989 Final Rule on Air Contaminants Project extracted from 54FR2332 et. seq. This rule was remanded by the U.S. Circuit Court of Appeals and the limits are not currently in force.
CAS: 78-92-2; Chemical Formula: CH3CH2CHOHCH3
OSHA's former limit for sec-butyl alcohol was 150 ppm as an 8-hour TWA. The proposed PELs were 100 ppm as an 8-hour TWA and 150 ppm as a 15-minute STEL, and NIOSH (Ex. 8-47) concurred with these limits. In the final rule, OSHA is establishing an 8-hour TWA of 100 ppm but is not adding a STEL (see the discussion of the Agency's policy on STELs for this rulemaking in Section VI.C.17). sec-Butyl alcohol is a colorless liquid with a strong, wine-like odor.
The acute toxicity of sec-butyl alcohol is reported to be lower than that of n-butanol, for which OSHA is establishing a ceiling of 50 ppm. The oral LD(50)s in rats for these two substances are 6.5 g/kg for sec-butyl alcohol and 4.4 g/kg for n-butanol, respectively (Smyth, Carpenter, and Weil 1951/Ex. 1-439). Liquid sec-butyl alcohol is less injurious to the eyes than liquid n-butanol (ACGIH 1986/Ex. 1-3, p. 77). Occupational exposures to sec-butyl alcohol at levels of about 100 ppm were reported not to be associated with difficulties (Banks 1966, as cited in ACGIH 1986/Ex. 1-3, p. 77).
OSHA received a comment on this substance from the American Industrial Hygiene Association (AIHA) (Ex. 8-16). The AIHA noted that there was no evidence to support a STEL for this substance and reported that the ACGIH intends to delete this STEL. OSHA has arrived at the same conclusion, and the final rule thus has no STEL for sec-butyl alcohol.
OSHA is reducing the permissible exposure limit for sec-butyl alcohol to 100 ppm TWA to afford protection against the significant risks of narcosis and irritation, which are material health impairments that are caused by exposures to sec-butyl alcohol at concentrations above the revised PEL. The Agency concludes that this limit will substantially reduce this risk.
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