No previous limit existed for methyl 2-cyanoacrylate. OSHA proposed establishing a limit of 2 ppm as an 8-hour TWA and 4 ppm as a STEL, based on the ACGIH recommendation, and the final rule establishes these limits. NIOSH (Ex. 8-47, Table N1) concurred with the selection of these limits. Methyl 2-cyanoacrylate is a colorless, viscous liquid.
In a personal communication to the ACGIH TLV Committee in 1985, Eastman Kodak reported on the toxicity of methyl 2-cyanoacrylate in experimental animals. The oral LD(50) in rats is reported to be 1.6 to 3.2 g/kg, and the dermal LD(50) in guinea pigs is 10 ml/kg. The adverse effects reported in laboratory animals are slight irritation of the skin and corneal damage. An inhalation LC(50) of 101 ppm has been reported in rats exposed for six hours to methyl 2-cyanoacrylate. Repeated exposures (six hours/day for five days/week) to 31.3 ppm for a total of 12 exposures caused only a slight decrease in the rate of weight gain in rats and no nasal or tracheal lesions or systemic toxicity. No changes were observed in rats similarly exposed to 3.1 ppm (Eastman Kodak 1985, as cited in ACGIH 1986/Ex. 1-3, p. 383).
In a simulated workbench exposure, McGee and co-workers reported nasal irritation in humans at 3 ppm and eye irritation at 5 ppm (McGee, Oglesby, Raleigh, and Fassett 1968/Ex. 1-424). There are no reports of occupational poisonings. No comments, other than NIOSH's, were received on OSHA's proposed PELs for this substance.
The report by McGee et al. (1968/Ex. 1-424) clearly establishes that employees are at risk of nasal irritation on exposure to 3 ppm or above and of eye irritation at 5 ppm or above. The Agency has determined that these adverse effects constitute material impairment of health and should be avoided in the workplace. Therefore, to substantially reduce these significant risks, OSHA is establishing a 2-ppm 8-hour TWA limit and a 4-ppm STEL for methyl 2-cyanoacrylate in the final rule.