Dimethyl Sulfoxide

CAS RN:67-68-5

Exposure Summary

Dimethyl sulfoxide's production and use as a reagent in organic synthesis, as an industrial solvent, in industrial cleaners and paint strippers and in medicine may result in its release to the environment through various waste streams. Dimethyl sulfoxide is part of the global atmospheric sulfur cycle and is produced when dimethyl sulfide is photooxidized. It has been isolated from many plants, is a common constituent of natural waters, and it occurs in seawater in the zone of light penetration where it may represent a product of algal metabolism. If released to air, a vapor pressure of 0.60 mm Hg at 25 deg C indicates dimethyl sulfoxide will exist solely as a vapor in the atmosphere. Vapor-phase dimethyl sulfoxide 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 4.3 hours. Vapor-phase dimethyl sulfoxide will also be degraded in the night-time atmosphere by reaction with nitrate radicals; the half-life for this reaction in air is estimated to be 1.4 hours. Dimethyl sulfoxide does not absorb light at wavelengths >290 nm and, therefore, is not expected to be susceptible to direct photolysis by sunlight. Dimethyl sulfoxide has been detected in rainwater indicating that it may be removed from the air by wet deposition. If released to soil, dimethyl sulfoxide is expected to have very high mobility based upon an estimated Koc of 2. Volatilization from moist soil surfaces is not expected to be an important fate process based upon a Henry's Law constant of 1.03X10-8 atm-cu m/mole. Dimethyl sulfoxide is expected to slowly volatilize from dry soil surfaces based upon its vapor pressure. The available biodegradation screening tests have conflicting results, but based on available data and weight-of-evidence approach, dimethyl sulfoxide is expected to be inherently biodegradable in soil and water. If released into water, dimethyl sulfoxide is not expected to adsorb to suspended solids and sediment based upon the Koc. Volatilization from water surfaces is not expected to be an important fate process based upon this compound's Henry's Law constant. An experimental BCF of <4 suggests that bioconcentration in aquatic organisms is low. Dimethyl sulfoxide is stable to hydrolysis in water. Occupational exposure to dimethyl sulfoxide may occur through inhalation and dermal contact with this compound at workplaces where dimethyl sulfoxide is produced or used. Monitoring data indicate that the general population may be exposed to dimethyl sulfoxide via inhalation of ambient air and ingestion of food and drinking water. Exposure through dermal contact with a small number of consumer products containing dimethyl sulfoxide is also a possibility. Dimethyl sulfoxide's use as a prescription medicine and dietary supplement may expose the general population via ingestion and dermal contact. (SRC)
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