Ethylene Oxide

CAS RN: 75-21-8

Exposure Summary

Ethylene oxide's production and use as a chemical intermediate and medical and foodstuff sterilizing agent may result in its release to the environment through various waste streams. Its use as an agricultural fumigant will result in its direct release to the environment. If released to air, a vapor pressure of 1,310 mm Hg at 25 deg C indicates ethylene oxide will exist solely as a gas in the atmosphere. Gas-phase ethylene oxide 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 57 days. Ethylene oxide 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, ethylene oxide is expected to have very high mobility based upon a Koc of 2.2. Volatilization from moist soil surfaces is expected to be an important fate process based upon a Henry's Law constant of 1.48X10-4 atm-cu m/mole. Since ethylene oxide hydrolyzes to ethylene glycol which is readily biodegraded, the importance of biodegradation of ethylene oxide in aquatic environments is not able to be accurately assessed. If released into water, ethylene oxide is not expected to adsorb to suspended solids and sediment 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 6 hours and 4 days, respectively. An estimated BCF of 3 suggests the potential for bioconcentration in aquatic organisms is low. Hydrolysis half-lives of 12-14 days for pH's between 5-7 in fresh water and 9-11 days in salt water indicate that hydrolysis may be an important environmental fate process. Occupational exposure to ethylene oxide may occur through inhalation and dermal contact with this compound at workplaces where ethylene oxide is produced or used. (SRC)
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