n-BUTYL ACETATE

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: 123-86-4; Chemical Formula: CH₃COO(CH₂)₃CH₃

The previous OSHA exposure limit for n-butyl acetate was 150 ppm, measured as an 8-hour TWA. OSHA proposed the adoption of a 15-minute STEL of 200 ppm to supplement the TWA limit. NIOSH (Ex. 8-47, Table N1) concurred with this proposal. The final rule establishes limits of 150 ppm as an 8-hour TWA and 200 ppm as a 15-minute STEL for this substance; these are the same limits as those recommended by the ACGIH (1986/Ex. 1-3). n-Butyl acetate is a colorless liquid with a fruity odor.

n-Butyl acetate is an irritant to the eyes, skin, and respiratory system. In a study involving cats exposed for six hours to 6100 ppm, slight narcotic effects were noted (Flury and Wirth 1933, as cited in ACGIH 1986/Ex. 1-3, p. 72). When exposed to 4200 ppm n-butyl acetate for six days at six hours per day, cats experienced slight irritation of the respiratory passage; at 3100 ppm, changes in blood cell morphology were recorded. At exposures of 1600 ppm, these cats exhibited slight irritation of the eyes and increased salivation (Flury and Wirth 1933, as cited in ACGIH 1986/ Ex. 1-3, p. 72). Air concentrations of 10,000 ppm n-butyl acetate proved fatal to rats after eight hours; four hours of exposure at the same level produced no deaths (Smyth 1956/Ex. 1-759). A paper by Sayers, Schrenk, and Patty (1936/Ex. 1-802) reported that guinea pigs demonstrated eye irritation effects at 3300 ppm, became unconscious after nine hours of exposure to 7000 ppm, and died after four hours of exposure to 14,000 ppm.

Human volunteers complained that throat irritation, which began at an exposure level of 200 ppm n-butyl acetate, worsened and became quite severe at 300 ppm (Nelson, Enge, Ross et al. 1943/Ex. 1-66). NIOSH was the only commenter to the record in response to OSHA’s proposed STEL for n-butyl acetate.

OSHA finds that workers are at significant risk of experiencing the severe eye, skin, and respiratory irritation, in addition to narcotic effects, that are associated with short-term exposures to this substance at levels above the 8-hour limit. The Agency considers the irritant and narcotic effects resulting from exposure to n-butyl acetate to be material impairments of health and functional capacity. OSHA concludes that a STEL is necessary to reduce this risk, and the Agency is therefore revising its limit for n-butyl acetate to 150 ppm as an 8-hour TWA and 200 ppm as a 15-minute STEL.