Diphenyl carbonate

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 3,900(SRC), determined from a structure estimation method(2), indicates that diphenyl carbonate is expected to have slight mobility in soil(SRC). Volatilization of diphenyl carbonate from moist soil surfaces is expected to be an important fate process(SRC) given an estimated Henry's Law constant of 8.5X10-5 atm-cu m/mole(SRC), using a fragment constant estimation method(3). However, volatilization from moist soil surfaces is expected to be attenuated by adsorption(SRC). Diphenyl carbonate is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 4X10-4 mm Hg(SRC), determined from a fragment constant method(4).

AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 3,900(SRC), determined from a structure estimation method(2), indicates that diphenyl carbonate is expected to adsorb to suspended solids and sediment in water(SRC). Volatilization from water surfaces is expected(3) based upon an estimated Henry's Law constant of 8.5X10-5 atm-cu m/mole(4), developed using a fragment constant estimation method(4). Using this Henry's Law constant and an estimation method(3), estimated volatilization half-lives for a model river and model lake are 12 hours and 10 days, respectively. However, volatilization from water surfaces is expected to be attenuated by adsorption to suspended solids and sediment in the water column(SRC). The estimated volatilization half-life from a model pond is 126 days if adsorption is considered(8). Diphenyl carbonate is expected to undergo hydrolysis due to the presence of hydrolyzable functional groups(3). According to a classification scheme(5), an estimated BCF of 67(SRC), from its log Kow of 3.28(7) and a regression-derived equation(6), suggests the potential for bioconcentration in aquatic organisms is moderate.

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), diphenyl carbonate, which has an estimated vapor pressure of 4X10-4 mm Hg at 25 °C(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase diphenyl carbonate 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 96 hours(SRC), calculated from its rate constant of 4X10-12 cu cm/molecule-sec at 25 °C(SRC) determined using a structure estimation method(3). Diphenyl carbonate may also undergo direct photolysis in the environment, since this compound contains a functional group that can absorb light greater than 290 nm(4).

Using a structure estimation method based on molecular connectivity indices(1), the Koc for diphenyl carbonate can be estimated to be 3,900(SRC). According to a classification scheme(2), this estimated Koc value suggests that diphenyl carbonate is expected to have slight mobility in soil.

Diphenyl carbonate (CAS # 102-09-0) was evaluated for acute oral toxicity in Sprague-Dawley albino rats (5/sex/group) administered doses of 0, 0.75, 1.5, and 3.0 g/kg by oral gavage, based on an initial range-finding study. All mortality occurred from 4 hours to 24 hours post-gavage and was consistent with an oral LD50 of 1.5 g/kg. During 14-day post-gavage observation, clinical signs of toxicity included clonic convulsions (1.5, 3.0 g/kg) and weight loss in 1 and 3 rats, respectively, dying by Day 1 of 3.0 and 1.5 g/kg groups; all surviving rats, including 5/10 mid-dose rats, gained weight. Among the solitary rats of 0.5, 1.0, 1.5, 2.0, and 4.0 gavaged doses in the range-finding study, pharmacotoxic signs observed during 14-day recovery included tremors, tachypnea, clonic convulsions, dyspnea, fasciculation, and hyperactivity. All lethalities in the range-finding study demonstrated distinct lesions upon necropsy with enlarged mandibular lymph nodes, pale renal medullae and spleen, blood accumulations in the brain, and mottled lungs. No gross lesions were identified on terminal necropsy of either survivors or lethalities in the LD50 study.

An estimated BCF of 67 was calculated for diphenyl carbonate(SRC), using a log Kow of 3.28(3) and a regression-derived equation(1). According to a classification scheme(2), this BCF suggests the potential for bioconcentration in aquatic organisms is moderate.

The Henry's Law constant for diphenyl carbonate is estimated as 8.5X10-5 atm-cu m/mole(SRC) using a fragment constant estimation method(1). This Henry's Law constant indicates that diphenyl carbonate is expected to volatilize from water surfaces(2). Based on this Henry's Law constant, the volatilization half-life from a model river (1 m deep, flowing 1 m/sec, wind velocity of 3 m/sec)(2) is estimated as 12 hours(SRC). The volatilization half-life from a model lake (1 m deep, flowing 0.05 m/sec, wind velocity of 0.5 m/sec)(2) is estimated as 10 days(SRC). However, volatilization from water surfaces is expected to be attenuated by adsorption to suspended solids and sediment in the water column(SRC). The estimated volatilization half-life from a model pond is 126 days if adsorption is considered(4). Diphenyl carbonate's Henry's Law constant(1) indicates that volatilization from moist soil surfaces is expected to occur(SRC), however this process is expected to be attenuated by adsorption. Diphenyl carbonate is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 4X10-4 mm Hg(SRC), determined from a fragment constant method(3).

The rate constant for the vapor-phase reaction of diphenyl carbonate with photochemically-produced hydroxyl radicals has been estimated as 4X10-12 cu cm/molecule-sec at 25 °C(SRC) using a structure estimation method(1). This corresponds to an atmospheric half-life of about 96 hours at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1). Diphenyl carbonate is expected to undergo hydrolysis due to the presence of hydrolyzable functional groups(2). Diphenyl carbonate may also undergo direct photolysis in the environment since this compound contains a functional group that can absorb light greater than 290 nm(2).

Occupational exposure to diphenyl carbonate may occur through inhalation and dermal contact with this compound at workplaces where plastics are exposed to thermal stress(SRC). Diphenyl carbonate comprised 81% of the total emissions content resulting from pyrolysis (at 250 °C) of Lexan, which is a polycarbonate used for injection molding(1).

Diphenyl carbonate's production and use as a solvent for nitrocellulose may result in its release to the environment through various waste streams. If released to air, an estimated vapor pressure of 4X10-4 mm Hg at 25 °C indicates diphenyl carbonate will exist solely as a vapor. Vapor-phase diphenyl carbonate 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 96 hours. Diphenyl carbonate may also undergo direct photolysis in the environment since this compound contains a functional group that can absorb light greater than 290 nm. If released to soil, diphenyl carbonate is expected to be slightly mobile based upon an estimated Koc of 3,900. Volatilization from moist soil surfaces is expected to be an important fate process based upon an estimated Henry's Law constant of 8.5X10-5 atm-cu m/mole; however, this process is expected to be attenuated by adsorption. If released into water, diphenyl carbonate is expected to adsorb to suspended solids and sediment based upon its 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 10 days and 12 hours, respectively. However, volatilization from water surfaces is expected to be attenuated by adsorption to suspended solids and sediment in the water column. The estimated volatilization half-life from a model pond is 126 days if adsorption is considered. Diphenyl carbonate is expected to undergo hydrolysis due to the presence of hydrolyzable functional groups. An estimated BCF of 67 suggests the potential for bioconcentration in aquatic organisms is moderate. Occupational exposure to diphenyl carbonate may occur through inhalation and dermal contact with this compound at workplaces where it is produced or used. (SRC)

/SRP:/ Basic Treatment: Establish a patent airway. Suction if necessary. Watch for signs of respiratory insufficiency and assist ventilations if necessary. Administer oxygen by nonrebreather mask at 10 to 15 L/min. Monitor for pulmonary edema and treat if necessary ... . Monitor for shock and treat if necessary ... . For eye contamination, flush eyes immediately with water. Irrigate each eye continuously with normal saline during transport ... . Do not use emetics. For ingestion, rinse mouth and administer 5 ml/kg up to 200 ml of water for dilution if the patient can swallow, has a strong gag reflex, and does not drool. Administer activated charcoal ... . /Esters and related compounds/

/SRP:/ Advanced Treatment: Consider orotracheal or nasotracheal intubation for airway control in the patient who is unconscious. Positive pressure ventilation techniques with a bag valve mask device may be beneficial. Monitor cardiac rhythm and treat arrhythmias if necessary ... . Start an IV with D5W /SRP: "To keep open", minimal flow rate/. Use lactated Ringer's if signs of hypovolemia are present. Watch for signs of fluid overload. For hypotension with signs of hypovolemia, administer fluid cautiously. Consider vasopressors if patient is hypotensive with a normal fluid volume. Watch for signs of fluid overload ... . Consider drug therapy for pulmonary edema ... . Use propaparacaine hydrochloride to assist eye irrigation ... . /Esters and related compounds/