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.