ZINC 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: 7646-85-7; Chemical Formula: ZnCl₂

OSHA’s former PEL for zinc chloride was 1 mg/m³ as an 8-hour TWA. The Agency proposed a TWA of 1 mg/m³, with a STEL of 2 mg/m³, for this substance, based on the ACGIH recommendation. NIOSH (Ex. 8-47, Table N1) concurred with this proposal, and these limits are established in the final rule. Zinc chloride fume is white and has an acrid odor.

Zinc chloride fume is highly caustic and damages the mucous membranes of the nasopharynx and respiratory tract. Exposure to the fumes of zinc chloride may result in a severe pneumonitis that is caused by irritation of the respiratory tract (Gafafer 1964/Ex. 1-1149). One instance in which a worker inhaled zinc chloride fumes resulted in advanced pulmonary fibrosis that ended in death (Milliken, Waugh, and Kadish 1963/Ex. 1-751), and 10 deaths and 25 nonfatal cases of pneumonitis occurred in workers caught in a tunnel when 79 smoke generators caught fire and generated zinc chloride fumes (Hunter 1955/Ex. 1-853). Other studies have shown that zinc chloride exposures cause skin ulceration (Sax 1957/ Ex. 1-1095). It has also been suggested that zinc chloride exposure may have chronic effects (Hamilton and Hardy 1974b/Ex. 1-958). In an investigation of the adverse effects of zinc chloride fume exposures, Ferry (1966, as cited in ACGIH 1986/Ex. 1-3, p. 643) reported that no sensory effects occurred when 30-minute exposures were limited to 0.07 and 0.4 mg/m³; however, this researcher noted that these levels did corrode metal. Other than NIOSH’s submission, no comments were received by OSHA on the proposed limits for zinc chloride fume.

OSHA concludes that the risk of damage to the eyes, skin, and respiratory tract associated with short-term exposure to zinc chloride fume, which are considered by OSHA to be material impairments of health, should be substantially reduced by establishing both a STEL and a TWA. Therefore, in the final rule, OSHA is promulgating a 1-mg/m³ TWA limit and 2-mg/m³ STEL for this substance.