CAS RN: 463-82-1

Exposure Summary

2,2-Dimethylpropane's production and use as a research chemical may result in its release to the environment through various waste streams. It's presence in gasoline may result in it's direct release to the environment. 2,2-Dimethylpropane is present at 0.07 vol % in naphtha. If released to air, a vapor pressure of 1290 mm Hg at 25 deg C indicates 2,2-dimethylpropane will exist solely as a gas in the atmosphere. Gas-phase 2,2-dimethylpropane 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 19 days. 2,2-Dimethylpropane does not contain chromophores that absorb at wavelengths >290 nm and, therefore, is not expected to be susceptible to direct photolysis by sunlight. If released to soil, 2,2-dimethylpropane is expected to have moderate mobility based upon an estimated Koc of 500. Volatilization from moist soil surfaces is expected to be an important fate process based upon an estimated Henry's Law constant of 2.2 atm-cu m/mole. 2,2-Dimethylpropane may volatilize from dry soil surfaces based upon its vapor pressure. The highly branched structure of 2,2-dimethylpropane suggests that biodegradation in water will be slow. If released into water, 2,2-dimethylpropane is 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 estimated Henry's Law constant. Estimated volatilization half-lives for a model river and model lake are 2.5 hours and 3.4 days, respectively. An estimated BCF of 52 suggests the potential for bioconcentration in aquatic organisms is 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 2,2-dimethylpropane may occur through inhalation and dermal contact with this compound at workplaces where 2,2-dimethylpropane is produced or used. Monitoring data indicate that the general population may be exposed to 2,2-dimethylpropane via inhalation of ambient air and possibly from cooked food. (SRC)
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