Phosgene

CAS RN: 75-44-5

Exposure Summary

Phosgene's production and use as an intermediate in organic synthesis, especially of isocyanates, polyurethane and polycarbonate resins, carbamates, organic carbonates, and chloroformates may result in its release to the environment through various waste streams. Its additional uses in dye manufacture, plastics, acid chlorination processes, as a phosgenation reagent, its uses in metallurgy to separate ores by chlorination of metal oxides, and its use as a chemical warfare gas may also result in its release to the environment through various waste streams. Phosgene is produced in the earth's atmosphere from the degradation of a variety of chlorinated compounds including tetrachloroethylene, trichloroethylene, chloroform, methylchloroform, and carbon tetrachloride. If released to air, a vapor pressure of 1420 mm Hg at 25 deg C indicates phosgene will exist solely in the gas phase in the atmosphere. Gas-phase phosgene will be slowly degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals; the half-life for this reaction in air is estimated to be 44 years. Phosgene does not absorb at wavelengths >290 nm and therefore is not expected to be susceptible to direct photolysis by sunlight. If released to soil, phosgene is expected to have very high mobility based upon an estimated Koc of 2.2. Volatilization from moist soil surfaces is expected to be an important fate process based upon a Henry's Law constant of 1.7X10-2 atm-cu m/mole. Phosgene may volatilize from dry soil surfaces based upon its vapor pressure. Biodegradation data were not available. If released into water, phosgene is not expected to adsorb to suspended solids and sediment based upon the estimated Koc. Volatilization from water surfaces is expected to be an important fate process based upon this compound's Henry's Law constant. Rapid hydrolysis suggests that bioconcentration will not be an important environmental fate process. Hydrolysis of a 1% solution of phosgene in water is complete within 20 seconds at 0 deg C. Occupational exposure to phosgene may occur through inhalation and dermal contact with this compound at workplaces where phosgene is produced or used. Monitoring data indicate that the general population may be exposed to phosgene via inhalation of ambient air. Its use as a chemical war gas makes military personnel susceptible to exposure via inhalation. (SRC)
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