TRICHLOROACETIC ACID

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: 76-03-9; Chemical Formula: CCl₃COOH

OSHA formerly had no exposure limits for trichloroacetic acid. The ACGIH has an 8-hour TWA of 1 ppm to protect against the corrosive effects of this substance. Trichloroacetic acid is a relatively strong acid that forms deliquescent crystals. The proposed PEL was 1 ppm as an 8-hour TWA, and NIOSH (Ex. 8-47, Table N1) concurs that this limit is appropriate. The final rule established a 1-ppm 8-hour TWA for trichloracetic acid.

The Dow Chemical Company (1977p, as cited by the ACGIH 1986/Ex. 1-3, p. 592) reported that the oral LD(50) for trichloroacetic acid in rats is 3.33 g/kg. Studies on mice conducted by NIOSH (1984, as cited in ACGIH 1986/Ex. 1-3, p. 592) established that the oral LD(50) for this species is 4.97 g/kg, and that a 500-mg/kg dose was fatal when administered intraperitoneally.

Medical reports show mild to moderate skin and eye burns in workers exposed to unspecified levels of trichloroacetic acid; although corrosive, however, trichloroacetic acid is not readily absorbed by the skin (ACGIH 1986/Ex. 1-3, p. 592). Only NIOSH commented on this substance.

In the final rule, OSHA is establishing an 8-hour TWA limit for trichloroacetic acid of 1 ppm. This limit is based on analogy to the toxicity of 2,2-dichloropropionic acid. The Agency concludes that this limit will protect exposed workers from the significant risk of skin and eye irritation, which are material impairments of health that are associated with exposure to this substance at levels above the new PEL.