Toluene

CAS RN:108-88-3

Exposure Summary

Toluene's production and use as an intermediate in the production of benzoic acid, benzaldehyde, explosives and many other organic compounds may result in toluene's release to the environment through various waste streams. Toluene is released into the atmosphere principally from the volatilization of petroleum fuels and toluene-based solvents and thinners and from motor vehicle exhaust. Toluene has been detected in emissions from volcanos, forest fires and crude oil and naturally occurs in some flora. If released to air, a vapor pressure of 28.4 mm Hg at 25 deg C indicates toluene will exist solely as a vapor in the atmosphere. Vapor-phase toluene 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 2 days. Toluene may also be degraded in the atmosphere by reaction with nitrate radicals and ozone molecules, but these reactions are too slow to be environmentally important. Toluene does not absorb light at wavelengths >290 nm and, therefore, is not expected to be susceptible to direct photolysis by sunlight. If released to soil, toluene is expected to have high to moderate mobility based upon Koc values in the range of 37-178. Volatilization from moist soil surfaces is expected to be an important fate process based upon a Henry's Law constant of 6.64X10-3 atm-cu m/mole. Toluene may volatilize from dry soil surfaces based upon its vapor pressure. Biodegradation is expected to occur rapidly in soil surfaces, with half-lives in the range of several hours to 71 days. If released into water, toluene is not expected to adsorb to suspended solids and sediment based upon a Koc of 166 measured in lake sediment. Half-lives of 4 and 56 days in aerobic and anaerobic water, respectively, indicate that biodegradation is an important environmental fate process in water. 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 1 hour and 4 days, respectively. Measured BCF values of 13 and 90 in fish suggest bioconcentration in aquatic organisms is low to moderate. Hydrolysis is not expected to be an important environmental fate process since this compound lacks functional groups that hydrolyze under environmental conditions (pH 5 to 9). Occupational exposure to toluene may occur through inhalation and dermal contact with this compound at workplaces where toluene is produced or used, particularly as a solvent or in gasoline. Monitoring data indicate that the general population may be exposed to toluene via inhalation of ambient air, cigarette smoke,ingestion of food and drinking water, and dermal contact with consumer products, such as gasoline, containing toluene. (SRC)
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