1,1-Difluoroethene

CAS RN:75-38-7

Exposure Summary

1,1-Difluoroethene's production and use as a monomer in the synthesis of poly(vinylidene fluoride) may result in its release to the environment through various waste streams. If released to air, a vapor pressure of 3X10+4 mm Hg at 25 deg C indicates 1,1-difluoroethene will exist solely as a gas in the atmosphere. Gas-phase 1,1-difluoroethene will be degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals and with ozone; the half-life for these reactions in air are estimated to be 8 and 60 days, respectively. 1,1-Difluoroethene 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, 1,1-difluoroethene is expected to have very high mobility based upon an estimated Koc of 32. Volatilization from moist soil surfaces is expected to be an important fate process based upon an estimated Henry's Law constant of 0.4 atm-cu m/mole. 1,1-Difluoroethene may volatilize from dry soil surfaces based upon its vapor pressure. Insufficient data are available to predict the relative importance or rate of biodegradation in soil or water. If released into water, 1,1-difluoroethene 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 estimated Henry's Law constant. Estimated volatilization half-lives for a model river and model lake are 2.3 hours and 3.2 days, respectively. An estimated BCF of 3 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. Occupational exposure to 1,1-difluoroethene may occur through inhalation and dermal contact with this compound at workplaces where 1,1-difluoroethene is produced or used. (SRC)
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