XYLIDINE

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: 1300-73-8; Chemical Formula: (CH₃)₂C₆H₃NH₂

OSHA’s former Z tables included an exposure limit of 5 ppm as an 8-hour TWA for xylidine, with a skin notation. In 1982, the ACGIH reduced its TLV to 2 ppm as an 8-hour TWA and retained the skin notation. The proposed PEL was 2 ppm as an 8-hour TWA, and the skin notation was retained. NIOSH (Ex. 8-47, Table N1) concurs with these limits, and they are established by the final rule. Xylidine is a pale yellow to brown liquid. Commercial xylidine is a mixture of isomers.

Several studies indicate that the former OSHA PEL for xylidine is insufficient to protect workers against hepatotoxic and other adverse effects. A paper by von Oettingen, Neal, Sievers et al. (1947, as cited in ACGIH 1986/Ex. 1-3, p. 639) reported liver damage in dogs, rats, cats, and mice repeatedly exposed to 45 ppm xylidine for seven hours per day for a period of 20 to 40 weeks; these exposures also caused death in dogs, cats, and mice. Treon, Sigmon, Wright et al. (1950/Ex. 1-533) noted cardiac, liver, and kidney damage in animals fatally exposed at the following doses: cats, 17 ppm; guinea pigs, 50 ppm; and rabbits, 60 ppm; cyanosis was also observed in these animals. Only NIOSH commented on xylidine.

In the final rule, OSHA is reducing the existing 8-hour TWA to 2 ppm and retaining the skin notation for xylidene. The Agency concludes that these limits will protect workers from the significant risk of exposure-related cardiac, kidney, and liver damage, all of which constitute material health impairments.