Acrylonitrile

CAS RN:107-13-1

Environmental Fate

TERRESTRIAL FATE: Based on a classification scheme(1), estimated Koc values of 9 and 29(SRC), determined respectively from a structure estimation method(2) and using a log Kow of 0.25(3) and a regression-derived equation(2), indicates that acrylonitrile is expected to have very high to high mobility in soil(SRC). Volatilization of acrylonitrile from moist soil surfaces is expected to be an important fate process(SRC) given a Henry's Law constant of 1.38X10-4 atm-cu m/mole(4). The potential for volatilization of acrylonitrile from dry soil surfaces may exist(SRC) based upon a vapor pressure of 109 mm Hg(5). At concentrations up to 100 ppm, complete degradation of 14C-acrylonitrile occurred in <2 days in a Londo soil(6). Greater than 50% of the radioactivity was recovered as 14C-carbon dioxide following 6 days of incubation. Transient formation of acrylamide and acrylic acid as intermediates of degradation were observed(6). Similar results were obtained in studies conducted with Tappan loam and sand(6). Acclimation of the microorganisms was required before degradation of 100 ppm acrylonitrile in sand(6). Degradation of higher concentrations (500 and 1,000 ppm in Londo soil) was relatively slow and may be due to inhibitory effects of the parent compound(6).

AQUATIC FATE: Based on a classification scheme(1), estimated Koc values of 9 and 29(SRC), determined respectively from a structure estimation method(2) and using a log Kow of 0.25(3) and a regression-derived equation(2), indicates that acrylonitrile is not expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is expected(4) based upon a Henry's Law constant of 1.38X10-4 atm-cu m/mole(5). Using this Henry's Law constant and an estimation method(4), volatilization half-lives for a model river and model lake are 7 hours and 4 days, respectively(SRC). According to a classification scheme(6), a BCF of 48 determined for bluegill fish(7) suggests the potential for bioconcentration in aquatic organisms is moderate(SRC). Biodegradation of acrylonitrile has been demonstrated in wastewater, activated sludge, and various microbial cultures free from other living organisms(8). Acrylonitrile completely degraded in Mississippi river water in 6 days(9) and degraded completely in 20 days in another study using river water, requiring less time for degradation with acclimation(10). Acrylonitrile was stable to aqueous hydrolysis over a pH range of 4-10 over a 10-day observation period(11).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), acrylonitrile, which has a vapor pressure of 109 mm Hg at 25 deg C(2), is expected to exist solely as a vapor in the ambient atmosphere(SRC). Vapor-phase acrylonitrile is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals and ozone(SRC); the half-life for reaction with hydroxyl radicals in air is estimated to be 4 days(SRC), calculated from its rate constant of 4.10X10-12 cu cm/molecule-sec at 25 deg C(3); the half-life for reaction with ozone in air is estimated to be 83 days(SRC), calculated from its rate constant of 1.38X10-19 cu cm/molecule-sec at 25 deg C(4). Acrylonitrile does not absorb light >290 nm and is therefore not susceptible to direct photolysis in sunlight(5).

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