Hydrogen Chloride

CAS RN: 7647-01-0

Toxicity Summary

IDENTIFICATION AND USE: Hydrogen chloride is a colorless gas with pungent, irritating odor. it is used as tuberculocide, disinfectant (bactericide/germicide/purifier, limited, general or broad-spectrum, hospital or medical), sanitizer, virucide, fungicide/fungistat, and microbicide/microbiostat (slime-forming bacteria). It is also used in the manufacture of pharmaceutical hydrochlorides, vinyl chloride from acetylene, alkyl chlorides from olefins, and arsenious chlorides from arsenious oxide. In the chlorination of rubber. In organic reactions involving isomerization, polymerization, and alkylation. For making chlorine where economical. Hydrochloric acid has been identified as being used in hydraulic fracturing as a pH adjuster. HUMAN EXPOSURE AND TOXICITY: Hydrogen chloride will rapidly dissociate and its effects are thought to be a result of pH change (local deposition of H+) rather than effects of hydrogen chloride/hydrochloric acid. Hydrogen chloride is corrosive to the skin and severe effects can be expected from exposure to the eyes. No skin sensitization has been reported. The irritation of hydrogen chloride to mucous is so severe that workers evacuate from the work place shortly after detecting its odor. In humans, no association between hydrogen chloride exposure and tumor incidence was observed. In one of eight asthmatic volunteers exposed to an aerosol of unbuffered hydrochloric acid at pH 2 for 3 min during tidal breathing, airway resistance was increased by 50%. Short term exposures have been reported to induce transitory obstruction in the respiratory tract, which diminishes with repeated exposure, suggesting adaption. Acclimatized workers can work undisturbed with a hydrogen chloride level of 15 mg/cu m (10 ppm). Exposure to hydrochloric acid can produce burns on the skin and mucous membranes, the severity of which is related to the concentration of the solution. Subsequently, ulceration may occur, followed by keloid and retractile scarring. Contact with the eyes may produce reduced vision or blindness. Frequent contact with aqueous solutions of hydrochloric acid may lead to dermatitis. Dental decay, with changes in tooth structure, yellowing, softening and breaking of teeth, and related digestive diseases are frequent after exposures to hydrochloric acid. ANIMAL STUDIES: For repeated dose toxicity, local irritation effects were observed in the groups of 10 ppm and above in a 90-day inhalation study. For genetic toxicity, a negative result has been shown in the Ames test. A positive result, which is considered to be an artifact due to the low pH, has been obtained in a chromosome aberration test using Hamster ovary cells. For carcinogenicity, no pre-neoplastic or neoplastic nasal lesions were observed in a 128-week inhalation study with male rats at 10 ppm hydrogen chloride gas. No evidence of treatment related carcinogenicity was observed either in other animal studies performed by inhalation, oral or dermal administration. Hydrogen chloride is not expected to have developmental toxicity. In addition, no effects on the gonads were observed in a good 90- day inhalation study up to 50 ppm. ECOTOXICITY STUDIES: The hazard of hydrochloric acid for the environment is caused by the proton (pH effect). For this reason the effect of hydrochloric acid on the organisms depends on the buffer capacity of the aquatic ecosystem. Also the variation in acute toxicity for aquatic organisms can be explained for a significant extent by the variation in buffer capacity of the test medium. For example, LC50 values of acute fish toxicity tests varied from 4.92 to 282 mg/L
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