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: 75-65-0; Chemical Formula:(CH3)3COH
OSHA formerly had a limit of 100 ppm for tert-butyl alcohol. The ACGIH has a TLV-TWA of 100 ppm, with a TLV-STEL of 150 ppm. OSHA proposed to retain the 8-hour TWA limit of 100 ppm and to add a STEL of 150 ppm for tert-butyl alcohol, and NIOSH (Ex. 8-47, Table N1) concurs. These limits are established by the final rule. At ordinary temperatures and pressures, tert-butyl alcohol exists in the form of colorless, hygroscopic crystals (ACGIH 1986/Ex. 1-3).
Although similar to the other butyl alcohols in many respects, tert-butyl alcohol is more volatile and has a greater potential for narcotic effects than other butyl alcohols (Weese 1928/Ex. 1-1073). Mice exposed to tert-butyl alcohol exhibit a stronger narcotic response than they show when exposed to normal or isobutyl alcohol (Weese 1928/Ex. 1-1073). Repeated daily doses of tert-butyl alcohol that produced narcosis were not fatal in animals (Schaffarzick and Brown 1952/Ex. 1-868). In humans, contact with t-butyl alcohol produces erythema and hyperemia (Oettel 1936/Ex. 1-921). Except for NIOSH's submittal, OSHA received no comments on tert-butyl alcohol.
In the final rule, OSHA is retaining the 8-hour TWA PEL of 100 ppm and adding a 15-minute STEL of 150 ppm for tert-butyl alcohol. The Agency concludes that this combination of limits will protect against the significant risk of narcosis, which constitutes a material health impairment that potentially occurs at levels above the 8-hour TWA PEL.
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