Ethyl N-phenylcarbamate

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 420(SRC), determined from a log Kow of 2.30 and a regression-derived equation(3), indicates that ethyl N-phenylcarbamate is expected to have moderate mobility in soil(SRC). Volatilization of ethyl N-phenylcarbamate from moist soil surfaces is not expected to be an important fate process(SRC) given an estimated Henry's Law constant of 2.9X10-8 atm-cu m/mole(SRC), using a fragment constant estimation method(4). Ethyl N-phenylcarbamate is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 0.027 mm Hg(SRC), determined from a fragment constant method(5). No biodegradation data were available(SRC, 2005).

AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 420(SRC), determined from a log Kow of 2.30(2) and a regression-derived equation(3), indicates that ethyl N-phenylcarbamate is expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is not expected(3) based upon an estimated Henry's Law constant of 2.9X10-8 atm-cu m/mole(SRC), developed using a fragment constant estimation method(4). According to a classification scheme(5), an estimated BCF of 12(SRC), from its log Kow(2) and a regression-derived equation(6), suggests the potential for bioconcentration in aquatic organisms is low(SRC). Hydrolysis is not expected to be an important fate process since carbamates tend to hydrolyze slowly under environmental conditions. A base-catalyzed second-order hydrolysis rate constant of 2.6X10-4 L/mole-sec(SRC) was estimated using a structure estimation method; this corresponds to half-lives of 840 and 84 years at pH values of 7 and 8, respectively(7). No biodegradation data were available(SRC, 2005).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), ethyl N-phenylcarbamate, which has an estimated vapor pressure of 0.027 mm Hg at 25 °C(SRC), determined from a fragment constant method(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase ethyl N-phenylcarbamate 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 2.7 hours(SRC), calculated from its rate constant of 4.7X10-11 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(3). The photooxidation products of ethyl N-phenylcarbamate in benzene solution were identified as ethyl o-aminobenzoate, ethyl p-aminobenzoate, aniline, water, carbon dioxide, azo compounds, and other colored material(4). Ethyl N-phenylcarbamate does not contain chromophores that absorb at wavelengths <290 nm and therefore is not expected to be susceptible to direct photolysis by sunlight(SRC).

The Koc of ethyl N-phenylcarbamate is estimated as 420(SRC), using a log Kow of 2.30 and a regression-derived equation(2). According to a classification scheme(3), this estimated Koc value suggests that ethyl N-phenylcarbamate is expected to have moderate mobility in soil.

Ethyl N-phenylcarbamate's production and use as a chemical intermediate(1) may have resulted in its release to the environment through various waste streams(SRC). Its former use as a plant growth regulator(2) resulted in its direct release to the environment(SRC).

An estimated BCF of 12 was calculated for ethyl N-phenylcarbamate(SRC), using a log Kow of 2.30(1) and a regression-derived equation(2). According to a classification scheme(3), this BCF suggests the potential for bioconcentration in aquatic organisms is low(SRC).

The Henry's Law constant for ethyl N-phenylcarbamate is estimated as 2.9X10-8 atm-cu m/mole(SRC) using a fragment constant estimation method(1). This Henry's Law constant indicates that ethyl N-phenylcarbamate is expected to be essentially nonvolatile from water surfaces(2). Ethyl N-phenylcarbamate's Henry's Law constant indicates that volatilization from moist soil surfaces will not occur(SRC). Ethyl N-phenylcarbamate is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 0.027 mm Hg(SRC), determined from a fragment constant method(3).

The rate constant for the vapor-phase reaction of ethyl N-phenylcarbamate with photochemically-produced hydroxyl radicals has been estimated as 4.7X10-11 cu cm/molecule-sec at 25 °C(SRC) using a structure estimation method(1). This corresponds to an atmospheric half-life of about 2.7 hours at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1). Hydrolysis is not expected to be an important fate process since carbamates tend to hydrolyze slowly under environmental conditions. A base-catalyzed second-order hydrolysis rate constant of 2.6X10-4 L/mole-sec(SRC) was estimated using a structure estimation method; this corresponds to half-lives of 840 and 84 years at pH values of 7 and 8, respectively(2). In general, most carbamates made with aliphatic alcohols would not hydrolyze under environmental conditions(3). The compound may undergo sensitized photolysis. Using a high-pressure quartz mercury vapor lamp with Pyrex glass filter, the photooxidation products of ethyl N-phenylcarbamate in benzene solution were identified as ethyl o-aminobenzoate, ethyl p-aminobenzoate, aniline, water, carbon dioxide, azo compounds, and other colored material(4). The photodegradation rate is dependent on the solvent, with a rate 7 to 10 times slower in a polar solvent (ethanol) than in a nonpolar solvent (cyclohexane)(4). Using the cyclohexane solvent, ethyl N-phenylcarbamate was mostly degraded after 3 hrs(4). Ethyl N-phenylcarbamate does not contain chromophores that absorb at wavelengths <290 nm and therefore is not expected to be susceptible to direct photolysis by sunlight(SRC).

Occupational exposure to ethyl N-phenylcarbamate occured through inhalation and dermal contact with this compound at workplaces where ethyl N-phenylcarbamate was produced or used. General population exposure should be low or non-existent since ethyl N-phenylcarbamate is no longer used in the US (May, 2005). (SRC)

Ethyl N-phenylcarbamate's production and use as a chemical intermediate may have resulted in its release to the environment through various waste streams; its former use as a plant growth regulator resulted in its direct release to the environment. If released to air, an estimated vapor pressure of 0.027 mm Hg at 25 °C indicates ethyl N-phenylcarbamate will exist solely as a vapor in the atmosphere. Vapor-phase ethyl N-phenylcarbamate 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 2.7 hours. Ethyl N-phenylcarbamate 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, ethyl N-phenylcarbamate is expected to have moderate mobility based upon an estimated Koc of 420. No biodegradation data were available. Volatilization from moist soil and water surfaces is not expected to be an important fate process based upon an estimated Henry's Law constant of 2.9X10-8 atm-cu m/mole. Ethyl N-phenylcarbamate will not volatilize from dry soil surfaces based upon its estimated vapor pressure. If released into water, ethyl N-phenylcarbamate is expected to adsorb moderately to suspended solids and sediment based upon the estimated Koc. An estimated BCF of 12 suggests the potential for bioconcentration in aquatic organisms is low. Hydrolysis is not expected to be an important fate process since carbamates tend to hydrolyze slowly under environmental conditions. A base-catalyzed second-order hydrolysis rate constant of 2.6X10-4 L/mole-sec was estimated using a structure estimation method; this corresponds to half-lives of 840 and 84 years at pH values of 7 and 8, respectively. Occupational exposure to ethyl N-phenylcarbamate occured through inhalation and dermal contact with this compound at workplaces where ethyl N-phenylcarbamate was produced or used. General population exposure should be low or non-existent since ethyl N-phenylcarbamate is no longer used in the US (May, 2005). (SRC)

Skin contamination should be treated promptly by washing with soap and water. Contamination of the eyes should be treated immediately by prolonged flushing of the eyes with large amounts of clean water. If dermal or ocular irritation persists, medical attention should be obtained without delay. /Other Herbicides/

If serious dehydration and electrolyte depletion have occurred as a result of vomiting and diarrhea, monitor blood electrolytes and and fluid balance and administer intravenous infusions of glucose, normal saline ringer's solution, or ringer's lactate to restore extracellular fluid volume and electrolytes. Follow this with oral nutrients as soon as fluids can be retained. Fluids serve to support excretion of the toxicants. Supportive measures are ordinarily sufficient for successful management of excessive exposures to these herbicides. /Other Herbicides/

LD50 Mouse ip 350 mg/kg

LD50 Mouse iv 400 mg/kg