n-BUTYL ACRYLATE

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: 141-32-2; Chemical Formula: C₇H₁₂O₂

OSHA had no former limit for n-butyl acrylate. The ACGIH’s Threshold Limit Value is a 10-ppm TWA. The proposed PEL, with which NIOSH (Ex. 8-47, Table N1) concurs, was 10 ppm as an 8-hour TWA, and this limit is promulgated by the final rule. n-Butyl acrylate is a colorless, flammable liquid.

n-Butyl acrylate is a skin and eye irritant and is toxic to animals. The LC(50) for a 4-hour exposure was 1000 ppm (Carpenter, Weil, and Smith 1974/Ex. 1-304). In rabbits, the dermal LD(50) for n-butyl acrylate is approximately 1800 mg/kg, compared with 1235 mg/kg for methyl acrylate (Smyth, Carpenter, and Weil 1951/Ex. 1-439). n-Butyl acrylate has also been found to be mildly irritating to the skin and to produce corneal necrosis in the unwashed eyes of rabbits (Holland 1974, as cited in ACGIH 1986/Ex. 1-3, p. 75).

At the rulemaking hearing, Dr. Isadore Rosenthal from Rohm and Haas was asked to submit to the docket any information on butyl acrylate that Rohm and Haas had in its possession and had not previously transmitted either to the ACGIH or to OSHA. In response, Dr. Rosenthal (Ex. 112) submitted a 1974 internal memo reporting on butyl acrylate’s overall toxicity. These data report, among other things, that the dermal LD(50) in rabbits for this substance is about 1800 mg/kg (Ex. 112).

In the final rule, OSHA is establishing an 8-hour TWA PEL of 10 ppm for n-butyl acrylate, based on the similarity of the toxicological response of n-butyl acrylate to methyl acrylate, for which OSHA also has a 10-ppm TWA limit. The Agency concludes that this limit is necessary to reduce the significant risk of skin irritation and corneal necrosis, which constitute material health impairments.