CYANOGEN CHLORIDE

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: 506-77-4; Chemical Formula: ClCN

OSHA previously had no limit for cyanogen chloride; however, a ceiling limit of 0.3 ppm was proposed for this colorless liquid or gas, which has a pungent odor. NIOSH (Ex. 8-47, Table N1) concurred with this proposal. In the final rule, OSHA is establishing a 0.3-ppm ceiling limit, which is the same as that recommended by the ACGIH.

The chronic effects of exposure to cyanogen chloride, which include hoarseness, conjunctivitis, and edema of the eyelid, have long been recognized (Reed 1920/Ex. 1-355). Flury and Zernik (1931d, as cited in ACGIH 1986/Ex. 1-3, p. 155) observed the effects of exposure to cyanogen chloride in five animal species. In mice, a concentration of approximately 500 ppm was fatal within three minutes; in cats, 120 ppm was fatal in 3.5 minutes; 48 ppm was fatal to dogs in six hours; in goats, a 1000-ppm exposure for three minutes caused death after 70 hours; and 1200 ppm was fatal to the rabbit. Several other studies have demonstrated that animals exposed to cyanogen chloride exhibit pulmonary edema and interference with cellular metabolism (Jandorf and Bodansky 1946/Ex. 1-334; Aldridge and Evans 1946/Ex. 1-708).

Human data indicate that 1 ppm is the lowest irritant concentration that can be tolerated for a 10-minute exposure; 2 ppm was intolerable for this time period, and 48 ppm was fatal in 30 minutes (Prentiss 1937/Ex. 1-1164). The Michigan Department of Health (1977, as cited by ACGIH 1986/Ex. 1-3, p. 155) reported that a concentration of about 0.7 ppm caused severe eye and nasal irritation, forcing workers to evacuate the area. NIOSH submitted the only comment received by OSHA on its proposed ceiling limit of 0.3 ppm for cyanogen chloride.

OSHA is establishing this 0.3-ppm ceiling limit for cyanogen chloride in the final rule. The Agency concludes that a ceiling limit is necessary to protect workers from the significant risks of severe irritation, metabolic effects, and pulmonary edema associated with short-term exposures to this substance at levels above the former PEL. The Agency considers the irritant, metabolic, and respiratory effects associated with exposure to cyanogen chloride to be material impairments of health and functional capacity.