AMMONIUM CHLORIDE FUME

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: 12125-02-9 Chemical Formula: NH₄Cl

No previous OSHA PEL had been established for ammonium chloride fume. Based on the ACGIH recommendation, OSHA proposed a TWA limit of 10 mg/m³ and a 20-mg/m³ STEL, and NIOSH (Ex. 8-47, Table N1) concurred with these proposed limits, and they are established in the final rule. Ammonium chloride is a white crystalline solid, somewhat hygroscopic, with a cool, saline taste.

Ammonium chloride fume is an irritant to the skin and respiratory passages when inhaled and produces mild systemic toxicity when ingested (Sax 1968a/Ex. 1-867). Although exposure-response data are lacking for this substance, the ACGIH (1986/Ex. 1-3) judged that these workplace limits would be sufficient to prevent workers from experiencing respiratory irritation.

OSHA received no comments on the proposed addition of exposure limits for ammonium chloride fume to the Z tables, other than those submitted by NIOSH. OSHA finds that, in the absence of any limit on airborne exposure, employees are at significant risk of respiratory irritation caused by exposure to high concentrations of ammonium chloride fume. OSHA concludes that the respiratory irritation caused by exposure to ammonium chloride fume constitutes a material impairment of health. To substantially reduce this risk, OSHA is establishing an 8-hour TWA limit of 10 mg/m³ and a 15-minute STEL of 20 mg/m³ in the final rule.