Nitromethane

CAS RN:75-52-5

Exposure Summary

Nitromethane's production and use as a corrosion inhibitor, solvent, chemical intermediate, explosive in shaped-charges and fuel for professional drag racers and hobbyists may result in its release to the environment through various waste streams. Nitromethane occurs in cigarette smoke. If released to air, a vapor pressure of 35.8 mm Hg at 25 deg C indicates nitromethane will exist solely as a vapor in the atmosphere. Vapor-phase nitromethane will be degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals; the half-life for this reaction in air is estimated to be 123 days. Nitromethane is expected to undergo direct photolysis in the atmosphere based on 83% degradation within 24 hours, and a half-life of 4.3 hours measured during tests for photodegradation. If released to soil, nitromethane is expected to have very high mobility based upon an estimated Koc of 10. Volatilization from moist soil surfaces is expected to be an important fate process based upon a Henry's Law constant of 2.86X10-5 atm-cu m/mole. Nitromethane is expected volatilize from dry soil surfaces based upon its vapor pressure. Utilizing a soil microcosm test, 5.1 and 2.3% conversion to CO2 in aerobic and anerobic soil, respectively, after 35 days indicates that biodegradation may be important environmental fate process in soil. Direct photolysis is expected to occur on soil surfaces exposed to sunlight. If released into water, nitromethane is not expected to adsorb to suspended solids and sediment based upon the estimated Koc. Biodegradation studies utilizing aqueous media give conflicting results. Volatilization from water surfaces is expected to be an important fate process based upon this compound's Henry's Law constant. Estimated volatilization half-lives for a model river and model lake are 27 hours and 10 days, respectively. A BCF of 1.4 suggests bioconcentration in aquatic organisms is low. Direct photolysis may be an important fate process on water surfaces exposed to sunlight. Hydrolysis is not an important environmental.Occupational exposure to nitromethane may occur through inhalation and dermal contact with this compound at workplaces where nitromethane is produced or used. Monitoring data indicate that the general population may be exposed to nitromethane via inhalation of ambient air and cigarette smoke. (SRC)
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