Tris(2,6-xylenyl)phosphate

Using a structure estimation method based on molecular connectivity indices(1), the Koc for tris(2,6-xylenyl)phosphate can be estimated to be 1.1X10+5(SRC). According to a classification scheme(2), this estimated Koc value suggests that tris(2,6-xylenyl)phosphate is expected to be immobile in soil.

Specific use information for tris(2,6-xylenyl)phosphate was not located. However, trixylenyl phosphates are produced and used as flame retardants and plasticizers(1) and hydraulic fluids(2) and tris(2,6-xylenyl)phosphate may be released to the environment through various waste streams during such production and/or use(SRC).

No specific biodegradation data were located for tris(2,6-xylenyl)phosphate in either soil or aquatic systems. TXP (trixylenyl phosphate) added at 3 mg/L/day was biodegraded by 65% over 14 weeks in the SCAS test using activated sludge as an inoculum; at an initial concentration of 13 mg/L/day, using the same test method, only 13% biodegradation was reported over a 25-week period(1). Kronitex TXP is a commercial product primarily consisting of the 2,5-, 3,4-, 3,5- and/or the 2,4-isomers of trixylylphosphates along with mixes of xylenyl phosphates or xylenyl/ethylphenyl phosphates(2). The degradation of specific isomers within the mixture was not quantified(1). In general the biodegradability of triaryl phosphates decreases with increasing number and size of substituent groups on the phenolic ring(1,3). Therefore based on the evidence pertaining to TXP(1), tris(2,6-xylenyl)phosphate may be susceptible to biodegradation(1).

An estimated BCF value of 720 was calculated for tris(2,6-xylenyl)phosphate(SRC) using a log Kow of 5.63(2) measured for Kronitex TXP, a commercial product primarily consisting of the trixylylphosphates along with mixes of xylenyl phosphates or xylenyl/ethylphenyl phosphates(1), and a regression-derived equation(3). The actual BCF of tris(2,6-xylenyl)phosphate would be expected to be slightly higher, for a greater Kow value would be anticipated for tris(2,6-xylenyl)phosphate due to the presence of lower molecular weight constituents among the TXP mixture. This is in keeping with this class of chemicals as analogous tri-p-cresyl phosphate has measured BCFs of 1,420 and 928 in rainbow trout and fathead minnows, respectively(4). According to a classification scheme(5), this BCF value suggests the potential for bioconcentration of tris(2,6-xylenyl)phosphate in aquatic organisms is high(SRC).

The Henry's Law constant for tris(2,6-xylenyl)phosphate is estimated as 7.2X10-8 atm-cu m/mole(SRC) using a fragment constant estimation method(1). This Henry's Law constant indicates that tris(2,6-xylenyl)phosphate is expected to be essentially nonvolatile from water surfaces(2). Tris(2,6- xylenyl)phosphate's Henry's Law constant(1) indicates that volatilization from moist soil surfaces is not expected to occur(SRC). Tris(2,6-xylenyl)phosphate is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 6.4X10-9 mm Hg(SRC), determined from a fragment constant method(3).

Triaryl phosphates are generally stable to hydrolysis at neutral pH values and undergo moderate hydrolysis in acidic solutions(1). Triaryl phosphates will degrade at appreciable rates in natural waters under alkaline conditions to apparently stable, water soluble, anionic diesters such as diaryl phosphates(1). No persistence data specific to tris(2,6-xylenyl)phosphate were available; however, based on data pertaining to triphenyl- and tricresyl- phosphates(1), tris(2,6-xylenyl)phosphate is expected to hydrolyze in natural alkaline waters. Tris(2,6-xylenyl)phosphate is not expected to directly photolyze due to the lack of absorption in the environmental UV spectrum (>290 nm)(SRC).

Specific use information pertaining to tris(2,6-xylenyl)phosphate was not available, although triaryl phosphates are generally employed as flame-retardants and plasticizers(1) and in hydraulic fluids(2). Occupational exposure to tris(2,6-xylenyl)phosphate may occur through inhalation of dust particles and dermal contact with this compound at workplaces where tris(2,6-xylenyl)phosphate is produced or used(SRC).

Tris(2,6-xylenyl)phosphate's production and use as a flame-retardant, plasticizer, or hydraulic fluid may result in its release to the environment through various waste streams. If released to air, an estimated vapor pressure of 6.4X10-9 mm Hg at 25 °C indicates tris(2,6-xylenyl)phosphate will exist solely in the particulate phase in the ambient atmosphere. Particulate-phase tris(2,6-xylenyl)phosphate will be removed from the atmosphere by wet and dry deposition. If released to soil, tris(2,6-xylenyl)phosphate is expected to be immobile based upon an estimated Koc of 1.1X10+5. Volatilization from moist soil surfaces is not expected to be an important fate process based upon an estimated Henry's Law constant of 7.2X10-8 atm-cu m/mole. Tris(2,6-xylenyl)phosphate is not expected to volatilize from dry soil surfaces based upon its vapor pressure. Biodegradation of aryl phosphates may occur slowly in the environment based on activated sludge tests showing 13 to 65% biodegradation of trixylenyl phosphate over 14 and 25 weeks, respectively. Under alkaline conditions in soil and water environments, appreciable abiotic degradation may occur via hydrolysis. If released into water, tris(2,6-xylenyl)phosphate is expected to adsorb to suspended solids and sediment based upon the estimated Koc. Volatilization from water surfaces is not expected to be an important fate process based upon this compound's estimated Henry's Law constant. An estimated BCF of 720 suggests the potential for bioconcentration in aquatic organisms is high. Occupational exposure to tris(2,6-xylenyl)phosphate may occur through inhalation of dust particles and dermal contact with this compound at workplaces where tris(2,6-xylenyl)phosphate is produced or used. (SRC)

Basic treatment: Establish a patent airway. Suction if necessary. Watch for signs of respiratory insufficiency and assist ventilations if needed. 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 ... . Anticipate seizures 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 ... . Cover skin burns with dry sterile dressings after decontamination ... . /Poison A and B/

Advanced treatment: Consider orotracheal or nasotracheal intubation for airway control in the patient who is unconscious, has severe pulmonary edema, or is in respiratory arrest. Positive pressure ventilation techniques with a bag valve mask device may be beneficial. Monitor cardiac rhythm and treat arrhythmias as 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. Consider drug therapy for pulmonary edema ... . For hypotension with signs of hypovolemia, administer fluid cautiously. Watch for signs of fluid overload ... . Treat seizures with diazepam (Valium) ... . Use proparacaine hydrochloride to assist eye irrigation ... . /Poison A and B/