Acrylamide

CAS RN:79-06-1

Environmental Fate

TERRESTRIAL FATE: Based on a classification scheme(1), an experimental Koc value of 50(2) indicates that acrylamide is expected to have very high to high mobility in soil(SRC). In an experiment evaluating leaching using soil TLC, Rf values ranging from 0.64 to 0.88, measured on four soils, indicated acrylamide is mobile in soil with higher mobility in sandy soils than in clay soils(3). Volatilization of acrylamide from moist soil surfaces is not expected to be an important fate process(SRC) given an estimated Henry's Law constant of 1.7X10-9 atm-cu m/mole(SRC), derived from its vapor pressure, 0.00675 mm Hg at 25 deg C(4), and water solubility, 3.711X10+5 mg/L(5). Acrylamide is not expected to volatilize from dry soil surfaces(SRC) based upon its vapor pressure(4). Acrylamide is susceptible to biodegradation in soil(6). Utilizing the Japanese MITI(7) and OECD 301D Closed Bottle tests(8), 70 and 98.1% of the Theoretical BOD was reached in 4 weeks, respectively, indicating that acrylamide is readily biodegradable. The nitrogen in acrylamide was recovered as inorganic nitrogen with recoveries after 3 and 14 days at 30 deg C ranging from 11-71% in Clarion soil and 74-95% in Canisteo soil, respectively(9). Results from these studies suggested that acrylamide is hydrolyzed in soil under aerobic conditions to produce ammonium ion, which is then oxidized to nitrite ion and nitrate ion(9). In another study using 4 central New York soils at 70% of their moisture capacity, half-lives ranging from 18 to 45 hr were observed(10).
AQUATIC FATE: Based on a classification scheme(1), an experimental Koc value of 50(2) indicates that acrylamide is not expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is not expected(3) based upon an estiamted Henry's Law constant of 1.7X10-9 atm-cu m/mole(SRC), derived from acrylamide's vapor pressure, 0.00675 mm Hg(4), and water solubility, 3.711X10+5 mg/L(5). According to a classification(6), a BCF of 1 for fingerling rainbow trout(7) suggests bioconcentration in aquatic organisms is low(SRC). Acrylamide is susceptible to biodegradation in water(8). Utilizing the Japanese MITI(9) and OECD 301D Closed Bottle tests(10), 70 and 98.1% of the Theoretical BOD was reached in 4 weeks, respectively, indicating that acrylamide is readily biodegradable. In two river die-away tests using aerated Thames River water, the lag time for biodegradation to begin was 220 and 50 hr(11). In the latter case, 90% of the acrylamide disappeared in approximately 150 hr(11). The hydrolysis half-life of acrylamide is >38 years at a pH 7(12).
ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), acrylamide, which has a vapor pressure of 0.00675 mm Hg at 25 deg C(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase acrylamide is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC); the half-life for this reaction in air is estimated to be 1.4 days(SRC), calculated from its rate constant of 1.1X10-11 cu cm/molecule-sec at 25 deg C(SRC) that was derived using a structure estimation method(3). Vapor-phase acrylamide is also degraded in the atmosphere by reaction with ozone(SRC); the half-life for this reaction in air is estimated to be 6.5 days(SRC), calculated from its rate constant of 1.8X10-18 cu cm/molecule-sec at 25 deg C(SRC) that was derived using a structure estimation method(3). Acrylamide does not absorb at wavelengths >290 nm(4) and, therefore, is not expected to be susceptible to direct photolysis by sunlight(SRC).
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