Tris(2,3-dichloropropyl) phosphate

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 9700(SRC), determined from a structure estimation method(2), indicates that tris(2,3-dichloropropyl) phosphate is expected to be immobile in soil(SRC). Volatilization of tris(2,3-dichloropropyl) phosphate from moist soil surfaces is not expected to be an important fate process(SRC) given an estimated Henry's Law constant of 2.6X10-9 atm-cu m/mole(SRC), using a fragment constant estimation method(3). Tris(2,3-dichloropropyl) phosphate is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 2.3X10-7 mm Hg at 25 °C(SRC), determined from a fragment constant method(4). Biodegradation is not expected to be an important environmental fate process based on resistance to degradation by activated sludge(5).

AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 9700(SRC), determined from a structure estimation method(2), indicates that tris(2,3-dichloropropyl) phosphate 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 2.6X10-9 atm-cu m/mole(SRC), developed using a fragment constant estimation method(4). According to a classification scheme(5), an estimated BCF of 18(SRC), from an estimated log Kow of 3.65(6) and a regression-derived equation(2), suggests the potential for bioconcentration in aquatic organisms is low. Tris(haloalkyl) phosphates are generally stable to hydrolysis at neutral pH and undergo moderate hydrolysis in acidic or basic solutions(7). Biodegradation is not expected to be an important environmental fate process based on resistance to degradation by activated sludge(8).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), tris(2,3-dichloropropyl) phosphate, which has an estimated vapor pressure of 2.3X10-7 mm Hg at 25 °C(SRC), determined from a fragment constant method(2), will exist in both the vapor and particulate phases in the ambient atmosphere. Vapor-phase tris(2,3-dichloropropyl) phosphate 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 16 hours(SRC), calculated from its rate constant of 2.2X10-11 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(3). Particulate-phase tris(2,3-dichloropropyl) phosphate may be removed from the air by wet or dry deposition(SRC). Tris(2,3-dichloropropyl) phosphate does not contain chromophores that absorb at wavelengths >290 nm(4) and, therefore, is not expected to be susceptible to direct photolysis by sunlight(SRC).

Tris(2,3-dichloropropyl) phosphate was detected in samples from four waste water treatment plants in Orange County, CA at 0-75 ng/L, samples were collected Feb to Dec 2002(1). Sewage sludge in Japan was found to contain small amounts of tris(2,3-dichloropropyl) phosphate(2). Tris(2,3-dichloropropyl) phosphate was detected in the wastewater effluents of 3 food, 9 chemical, 2 ironworks, 3 metal processing, and 8 other industrial sites (Japan) at concentrations not very much higher than the surrounding environmental waters(3).

Using a structure estimation method based on molecular connectivity indices(1), the Koc of tris(2,3-dichloropropyl) phosphate can be estimated to be 9700(SRC). According to a classification scheme(2), this estimated Koc value suggests that tris(2,3-dichloropropyl) phosphate is expected to be immobile in soil.

/OTHER TOXICITY INFORMATION/ Moderately toxic by ingestion.

/OTHER TOXICITY INFORMATION/ Negative-chemical-ionization mass spectral screening of extracts of human seminal plasma has revealed a presence of a Cl7 ion cluster at a mass-to-charge ratio (m/z) of 463 in a significant number of the samples examined (34 out of 123). Experiments with different gases used to generate the negative-chemical-ionization plasma indicated that the ion at m/z 463 was a chloride adduca of a Cl6 molecule with a mass of 428 daltons. Negative-chemical-ionization mass measurement with ions from the iodoform mass spectrum used as reference peaks gave a mass of 427.882 daltons; C9H15PCl6 has a molecular weight of 427.883. Extraction of polyurethane foam with toluene produced an extract that consistently gave a negative-chemical-ionization spectrum containing an intense Cl7ion at m/z463. The component producing ion was isolated, and its proton nuclear magnetic resonance spectrum confirmed that it was tris (1,3-dichloro-2-propyl)phosphate, a mutagenic flame retardant. The negative-chemical-ionization screening evidence suggests that this flame retardant or its isomer tris(2,3-dichloro-l-propyl)phosphate, or both, are absorbed into the body from formulations in which they are used as flame retardants. Remedial action seems indicated to reduce human exposure to these compounds.

No data regarding the biodegradation of tris(2,3-dichloropropyl) phosphate in either soil or aquatic systems was available(SRC, 2013). In general the biodegradability of haloalkyl phosphates is not well understood. Limited evidence suggest that tris(2,3-dibromo-1-propyl) phosphate may be susceptible to biodegradation(1). However tris(2,3-dichloropropyl) phosphate was moderately resistant to biodegradation by activated sludge(2).

An estimated BCF of 18 was calculated in fish for tris(2,3-dichloropropyl) phosphate(SRC), using an estimated log Kow of 3.65(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 tris(2,3-dichloropropyl) phosphate is estimated as 2.6X10-9 atm-cu m/mole(SRC) using a fragment constant estimation method(1). This Henry's Law constant indicates that tris(2,3-dichloropropyl) phosphate is expected to be essentially nonvolatile from water and moist soil surfaces(2). Tris(2,3-dichloropropyl) phosphate is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 2.3X10-7 mm Hg(SRC), determined from a fragment constant method(3).

/GENOTOXICITY/ 9 halogenated alkanols, 9 corresponding tris (haloalkyl)phosphates, and 2 bis-(2,3-dibromopropyl)phosphate salts were evaluated for mutagenicity against Salmonella typhimurium TA98, TA100, TA1535, TA1537 and TA1538, with and without rat liver in vitro metabolic activation system (S9 mix). Most of the test samples showed mutagenic activity in the strains TA100 and TA1535, but not in the strains TA98, TA1537 and TA1538. In general, the mutagenic activities of the phosphates obtained with S9 mix were greater than the activities obtained without S9 mix. Among the phosphates, several structure--activity relationships were found; i.e., (i) the bromoalkyl derivatives were more mutagenic than the corresponding chloroalkyl derivatives, (ii) the beta-haloethyl derivatives were more mutagenic than the gamma-halopropyl derivatives, (iii) the phosphates having adjacent beta and gamma halogen atoms in the alkyl moiety, e.g., tris-(2,3-dibromopropyl)phosphate, were particularly potent mutagens, (iv) the branched carbon chain reduced the mutagenic activities in spite of the presence of beta-halogen atoms, e.g., tris(1-bromomethyl-2-bromoethyl)phosphate. However, such relations did not necessarily apply to the halogenated alkanols. It is concluded that the metabolic activation pathway via haloalkanols to mutagens must not be in common with all tris-BP-like phosphates.

The rate constant for the vapor-phase reaction of tris(2,3-dichloropropyl) phosphate with photochemically-produced hydroxyl radicals has been estimated as 2.2X10-11 cu cm/molecule-sec at 25 °C(SRC) using a structure estimation method(1). This corresponds to an atmospheric half-life of about 16 hours at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1). Tris(haloalkyl) phosphates are generally stable to hydrolysis at neutral pH and undergo moderate hydrolysis in acidic or basic solutions(2). Tris(2,3-dichloropropyl) phosphate does not contain chromophores that absorb at wavelengths >290 nm(3) and, therefore, is not expected to be susceptible to direct photolysis by sunlight(SRC).