2,2-DICHLOROPRO

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: 75-99-0; Chemical Formula: CH₃CCl₂COOH

OSHA previously had no limit for 2,2-dichloropropionic acid; however, the Agency proposed a 1-ppm 8-hour TWA limit for this liquid, based on the ACGIH (1986/Ex. 1-3) recommendation. NIOSH (Ex. 8-47, Table N1) concurred with the proposed 1-ppm TWA limit, and the final rule establishes it.

In a communication to the ACGIH, the Dow Chemical Company (1977b, as cited in ACGIH 1986/Ex. 1-3, p. 190) reported that 2,2-dichloropropionic acid is corrosive to the skin and can cause permanent injury to the eye. The oral LD(50) in rats is between 0.7 and 1 g/kg. Seven-hour exposures to a saturated atmosphere of the acid vapor caused no ill effects in rats, and a 120-day study of dietary exposure in rats showed a no-effect level of 15 mg/kg/day (Dow Chemical Company 1977b, as cited in ACGIH 1986/Ex. 1-3, p. 190). Dr. Grace Ziem, an independent occupational physician (Ex. 46), commented that Dow’s material safety data sheet on 2,2-dichloropropionic acid reports that the liver and kidneys are target organs in rats fed higher dietary levels.

Acute human exposures have been reported to cause mild to moderate skin, eye, respiratory, and gastrointestinal irritation. Minimal respiratory irritation was observed in workers exposed at concentrations of between 2 and 7 ppm (ACGIH 1986/Ex. 1-3, p. 190).

The Agency concludes that a 1 ppm TWA limit for 2,2-dichloropropionic acid will protect workers from the significant risk of eye, respiratory, and gastrointestinal irritation, and possible liver or kidney injury, at exposure levels permitted in the absence of any OSHA limit. The Agency considers the irritant and adverse organ effects associated with exposure to this substance to be material impairments of health and functional capacity. Therefore, OSHA is establishing a 1-ppm 8-hour TWA limit for 2,2-dichloropropionic acid.