CAS RN: 115-07-1

Exposure Summary

Propylene's production and use as a chemical intermediate in the manufacture of fine chemicals, plastics and carpet fibers may result in its release to the environment through various waste streams. In addition, propylene is produced by the combustion of fossil fuels and biomass and the burning of cigarettes. Natural sources of propylene are the volatile components of garlic oil, Scotch firs, European firs, and germinating seeds such as beans, corn, cotton, and pea seeds. If released to air, a vapor pressure of 8590 mm Hg at 25 deg C indicates propylene will exist solely as a gas in the atmosphere. Gas-phase propylene 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 15 hrs. Propylene 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, propylene is expected to have very high mobility based upon an estimated Koc of 22. Volatilization from moist soil surfaces is expected to be an important fate process based upon a Henry's Law constant of 0.196 atm-cu m/mole. Propylene may volatilize from dry soil surfaces based upon its vapor pressure. Biodegradation data in soil of water were not available. However, propylene was biodegraded to propylene oxide using acclimated cell free extracts. If released into water, propylene is not 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 Henry's Law constant. Estimated volatilization half-lives for a model river and model lake are 2 hrs and 3 days, respectively. An estimated BCF of 7 suggests the potential for bioconcentration in aquatic organisms is low. 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 propylene may occur through inhalation and dermal contact with this compound at workplaces where propylene is produced or used. Monitoring data indicate that the general population may be exposed to propylene via inhalation of ambient air, since propylene is widely found in air samples along roadways, city streets, and restaurants. (SRC)
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