2,4,6-Tribromoanisole

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 400(SRC), determined from a structure estimation method(2), indicates that 2,4,6-tribromoanisole is expected to have moderate mobility in soil(SRC). Volatilization of 2,4,6-tribromoanisole from moist soil surfaces is expected to be an important fate process(SRC) given an estimated Henry's Law constant of 3.15X10-4 atm-cu m/mole(SRC), using a fragment constant estimation method(3). 2,4,6-Tribromoanisole is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 5.38X10-4 mm Hg at 25 °C(SRC), determined from a fragment constant method(4). Biodegradation data were not available(SRC, 2010).

AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 400(SRC), determined from a structure estimation method(2), indicates that 2,4,6-tribromoanisole is expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is expected(3) based upon an estimated Henry's Law constant of 3.15X10-4 atm-cu m/mole(SRC), developed using a fragment constant estimation method(4). Using this Henry's Law constant and an estimation method(3), volatilization half-lives for a model river and model lake are 5.3 hours and 8.9 days, respectively(SRC). According to a classification scheme(5), a measured BCF of 865 in fathead minnows(6) suggests bioconcentration in aquatic organisms is high, provided the compound is not metabolized by the organism(SRC). Biodegradation data were not available(SRC, 2010).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), 2,4,6-tribromoanisole, which has an estimated vapor pressure of 5.38X10-4 mm Hg at 25 °C(SRC), determined from a fragment constant method(2), is expected to exist in both the vapor and particulate phases in the ambient atmosphere. Vapor-phase 2,4,6-tribromoanisole 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 13 days(SRC), calculated from its rate constant of 1.25X10-12 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(3). Particulate-phase 2,4,6-tribromoanisole may be removed from the air by wet or dry deposition(SRC). 2,4,6-Tribromoanisole 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).

The concentration of 2,4,6-tribromoanisole in sultanas packaged in polyethylene film storage porches were 23 and 26 ng/g, after 7 days of storage at temperatures of 22 °C and 30 °C, respectively; concentrations were 37 and 41 ng/g, after 14 days of storage at temperatures of 22 °C and 30 °C, respectively. The compound was absorbed into the pouches after 1 week of storage in the presence of fiberboard sheets treated with 150 ng of 2,4,6-tribromoanisole. Concentrations in the storage pouches were 53 and 55 ng/g after 7 days and 71 and 77 ng/g after 14 days of storage at temperatures of 22 °C and 30 °C, respectively.(1). 2,4,6-Tribromoanisole was detected in 30 samples of various red wines suspected of musty, corky off-flavors, at concentrations ranging from not detected (detection limit 0.9 ng/L) to 37.9 ng/L(2). Wines containing a high level of 2,4,6-tribromoanisole (>20 ng/L) had a "phenolic" or "iodized" character of varying intensity, as well as an intense musty odor(2).

/AQUATIC SPECIES/ Skeletonema costatum, Thalassiosira pseudonana, Glenodinium halli, and Isochrysis galbana were used to study the effects of chlorinated and brominated compounds on cell division. In each case the four species of algae were similarly affected by each chemical. Of the compounds tested the most inhibitory to all four species was monochloramine. Halogenated phenols caused various responses, some of the compounds being stimulatory and others inhibiting cell division. No toxic effects were noted at tested levels of p-chlorophenol or 2,4,6-tribromoanisole.

Using a structure estimation method based on molecular connectivity indices(1), the Koc of 2,4,6-tribromoanisole can be estimated to be 400(SRC). According to a classification scheme(2), this estimated Koc value suggests that 2,4,6-tribromoanisole is expected to have moderate mobility in soil.

RURAL/REMOTE: Forty-nine ambient air samples were taken weekly throughout 2003 at Lista, a rural coastal site at the southern tip of Norway; 2,4,6-tribromoanisole was detected at concentrations ranging from 0.1 to 37 pg/cu m(1). The average concentration of 2,4,6-tribromoanisole detected in marine air in 13 samples from Ninety-Mile Beach, New Zealand (collected July-August 1985) was 18 pg/cu m; concentration in 5 samples from American Samoa (collected August 1981) was 19 pg/cu m; concentration in 10 samples from Mustang Island, Gulf of Mexico, Texas (collected August 1981) was 55 pg/cu m(2). 2,4,6-Tribromoanisole was detected in air samples collected in March 1986 at Reunion Island in the Southern India Ocean at concentrations ranging from 8-30 pg/cu m, with a mean of 15 pg/cu m(3).

RURAL/REMOTE: In 1994, 2,4,6-tribromoanisole was detected in air samples collected in the Eastern Atlantic Ocean in the Northern Hemisphere, at 39 deg N, 26 deg N and 13 deg N latitude at concentrations of 30, 4.3 and 42 pg/cu m, respectively; concentrations collected in the Southern Hemisphere at 3 deg S, 15 deg S, 24 deg S, 37 deg S, 46 deg S and 56 deg S latitude were 28, 4.9, 11, 4.0, 0.5 and 3.4 pg/cu m, respectively(1). Samples collected in the Northern Hemisphere may represent the pollution of the densely populated and industrialized countries due to sample sites located in the north-east tradewind region(1).

/ALTERNATIVE and IN VITRO TESTS/ ... /This/ study assessed the potential effects of nineteen brominated diphenyl ethers (BDEs), five hydroxylated BDEs (OH-BDEs), one methoxylated BDE (CH(3)O-BDE), tetrabromobisphenol-A (TBBPA), its dibromopropane ether derivative (TBBPA-DBPE), and the brominated phenols/anisols 2,4,6-tribromophenol (TBP), 4-bromophenol (4BP) and 2,4,6-tribromoanisole (TBA) on the catalytic activity of the steroidogenic enzyme aromatase (CYP19) in H295R human adrenocortical carcinoma cells. Effects were studied in the concentration range from 0.5 to 7.5 uM; exposures were for 24 hr. Both 6-OH-BDE47 and 6-OH-BDE99 showed an inhibitory effect on aromatase activity at concentrations > 2.5 uM and > 5 uM, respectively. However, 6-OH-BDE47 also caused a statistically significant increase in cytotoxicity (based on mitochondrial MTT reduction and lactate dehydrogenase-leakage [LDH]) at concentrations > 2.5 uM that could explain in part the apparent inhibitory effect on aromatase activity. Compared to 6-OH-BDE47, the methoxy analog (6-CH(3)O-BDE47) did not elicit a cytotoxic effect, whereas significant inhibition of aromatase remained. TBP caused a concentration-dependent induction of aromatase activity between 0.5 and 7.5 uM (with a maximum of 3.8-fold induction at 7.5 uM). This induction was not observed when a OH- group replaced the CH(3)O- group or when bromine atoms adjacent to this OH- group were absent ...

/OTHER TOXICITY INFORMATION/ ... Synthetic 2,3,3',4,4',5,5'-heptachloro-1'-methyl-1,2'-bipyrrole (Q1) and 2,4,6-tribromoanisole (TBA) were available in pure form ... Q1 was negative by established test systems for the determination of ethoxyresorufin-O-deethylase (EROD) induction and by sulforhodamine B assay. EROD induction potency was at least 10-7 times lower than that of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). At a relatively high concentration (20 uM), Q1 inhibited specific binding of 2 nM (3H)TCDD to the in vitro-expressed human aryl hydrocarbon receptor (AHR) by 18%; lower concentrations showed no effect. Molecular modeling showed that Q1 is nonplanar, consistent with its relatively modest affinity as an AHR ligand. When tested for cell-growth inhibitory/cytocidal activity in human tumor cells, Q1 was only marginally, if at all, active with an IC(50) value > 50 uM compared with five to ten times lower IC(50) values for potent cytotoxins tested in the test system used. Furthermore, standard pesticide tests on insecticidal, herbicidal, and fungicidal activity did not provide any significant activity at highest concentrations. For TBA, the results in all tests were comparable with Q1 ...

In 2006, 2,4,6-tribromoanisole was detected in the liver of hollowsnout grenadier (Coelorhynchus coelorhynchus), a deep-sea fish from the Mediterranean Sea, at mean (range) concentrations in 6 samples of 0.3 (0.2-0.5) ng/g lipid weight; it was detected at concentrations of <0.2 in 9 samples of the roughsnout grenadier (Trachyrinchus trachyrinchus)(1). 2,4,6-Tribromoanisole was detected in common carp (Cyprinus carpio) collected in the summer of 1984 from the Genesse River, along Lake Ontario in New York, at mean concentrations of 600 ng/g fish fat; 2,4,6-tribromoanisole was not detected in fish collected from 14 other sites in the area around Lake Ontario(2). 2,4,6-Tribromoanisole was found in 14 of 24 fish and shellfish samples collected from seashore locations in Japan in October 1981, at concentrations ranging from 0.1 to 5.4 ug/kg, on a wet weight basis(3).

2,4,6-Tribromoanisole's production and use as a lab reagent(1) may result in its release to the environment through various waste streams(SRC). 2,4,6-Tribromoanisole occurs as a biodegradation metabolite of 2,4,6-tribromophenol, a fungicide; strains of the fungus Paecilomyces variotti were found to convert 2,4,6-tribromophenol to 2,4,6-tribromoanisole after 6 weeks(2).

SEDIMENT: 2,4,6-Tribromoanisole was not detected (detection limit not specified) in marine sediments collected in 1981 from 6 sampling sites in Japan(1). 2,4,6-Tribromoanisole was detected in 2 of 12 upper river and marine sediment layer samples collected in Osaka Prefecture, Japan, from 1981 through 1983, at a mean concentration of 0.7 ug/kg, dry weight (detection limit of 0.5 ppb)(2).

A BCF of 865 was measured in fish for 2,4,6-tribromoanisole, using fathead minnows (Pimephales promelas) which were exposed to a mean concentration of 4.8 ug/L over a 32-day period(1). According to a classification scheme(2), this BCF suggests bioconcentration in aquatic organisms is high, provided the compound is not metabolized by the organism(SRC).

The Henry's Law constant for 2,4,6-tribromoanisole is estimated as 3.15X10-4 atm-cu m/mole(SRC) using a fragment constant estimation method(1). This Henry's Law constant indicates that 2,4,6-tribromoanisole 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 5.3 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 8.9 days(SRC). 2,4,6-Tribromoanisole's Henry's Law constant indicates that volatilization from moist soil surfaces may occur(SRC). 2,4,6-Tribromoanisole is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 5.38X10-4 mm Hg(SRC), determined from a fragment constant method(3).

The rate constant for the vapor-phase reaction of 2,4,6-tribromoanisole with photochemically-produced hydroxyl radicals has been estimated as 1.25X10-12 cu cm/molecule-sec at 25 °C(SRC) using a structure estimation method(1). This corresponds to an atmospheric half-life of about 13 days at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1). 2,4,6-Tribromoanisole is not expected to undergo hydrolysis in the environment due to the lack of functional groups that hydrolyze under environmental conditions(2). 2,4,6-Tribromoanisole does not contain chromophores that absorb at wavelengths >290 nm(2), and therefore is not expected to be susceptible to direct photolysis by sunlight(SRC).