CAS RN:74-95-3

Exposure Summary

Dibromomethane's production and use in chemical synthesis, as a fire suppressant, a solvent and a gage fluid may result in its release to the environment through various waste streams. Natural production by marine algae also adds to its environmental input. If released to air, a vapor pressure of 44.4 mm Hg at 25 deg C indicates dibromomethane will exist solely as a vapor in the ambient atmosphere. Vapor-phase dibromomethane 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 142 days. If released to soil, dibromomethane is expected to have very high mobility based upon an estimated Koc of 24. Volatilization from moist soil surfaces is expected to be an important fate process based upon a Henry's Law constant of 8.22X10-4 atm-cu m/mole. Dibromomethane may volatilize from dry soil surfaces based upon its vapor pressure. No significant biotic or abiotic degradative processes have been reported in natural waters or soil. However, catalyzed photolysis may occur in surface layers of some natural waters or soil. If released into water, dibromomethane is not expected to adsorb to suspended solids and sediment in water based upon the Koc. 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 2 hours and 6 days, respectively. An estimated BCF of 4 suggests the potential for bioconcentration in aquatic organisms is low. Hydrolysis is estimated to be an extremely slow process. Occupational exposure to dibromomethane may occur through inhalation and dermal contact with this compound at workplaces where dibromomethane is produced or used. The general population will be exposed to low levels of dibromomethane in the atmosphere from both natural and anthropogenic sources. (SRC)
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