Phencyclidine

CAS RN: 77-10-1

Environmental Fate

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 340(SRC), determined from a log Kow of 3.63(2) and a regression-derived equation(3), indicates that phencyclidine is expected to have moderate mobility in soil(SRC). The pKa of phencyclidine is 8.29(2), indicating that this compound will exist partially in the cation form in the environment and cations generally adsorb more strongly to soils containing organic carbon and clay than their neutral counterparts(4). Volatilization of the neutral species from moist soil surfaces is expected to be an important fate process(SRC) given an estimated Henry's Law constant of 5.5X10-6 atm-cu m/mole(SRC), using a fragment constant estimation method(5) . Phencyclidine is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 1.9X10-4 mm Hg at 25 deg C(SRC), determined from a fragment constant method(6). Biodegradation data in soil were not available(SRC, 2012).
AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 340(SRC), determined from a log Kow of 3.63(2) and a regression-derived equation(3), indicates that phencyclidine is expected to adsorb to suspended solids and sediment(SRC). Volatilization of the neutral species from water surfaces is expected(4) based upon an estimated Henry's Law constant of 5.5X10-6 atm-cu m/mole(SRC), developed using a fragment constant estimation method(5). Using this Henry's Law constant and an estimation method(4), volatilization half-lives for a model river and model lake are 11 and 81 days, respectively(SRC). According to a classification scheme(6), an estimated BCF of 580(SRC), from its log Kow(2) and a regression-derived equation(3), suggests the potential for bioconcentration in aquatic organisms is high(SRC), provided the compound is not metabolized by the organism. Biodegradation data in water were not available(SRC, 2012).
ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), phencyclidine, which has an estimated vapor pressure of 2.5X10-2 mm Hg at 25 deg C(SRC), determined from a fragment constant method(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase phencyclidine 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 1.2 hours(SRC), calculated from its rate constant of 1.0X10-10 cu cm/molecule-sec at 25 deg C(SRC) that was derived using a structure estimation method(3). Phencyclidine absorbs light at wavelengths up to 269 nm(4) and, therefore, is not expected to be susceptible to direct photolysis by sunlight(SRC).
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