Hexabromobenzene

Log Kow= 6.07

6.51

Insoluble (NTP, 1992)

SOL IN ACETIC ACID; SLIGHTLY SOL IN ALC, ETHER

> 10% in benzene

> 10% in chloroform

> 10% in petroleum ether

In water = 0.16X10-3 mg/l at 25 °C

621 °F (NTP, 1992)

327 °C

Monoclinic needles or white powder. Insoluble in water. (NTP, 1992)

Solid; [HSDB] Powder; [MSDSonline]

Warning

H302+H312+H332 (88.6%): Harmful if swallowed, in contact with skin or if inhaled [Warning Acute toxicity, oral; acute toxicity, dermal; acute toxicity, inhalation]

P261, P264, P264+P265, P270, P271, P273, P280, P301+P317, P302+P352, P304+P340, P305+P351+P338, P317, P319, P321, P330, P332+P317, P337+P317, P362+P364, P403+P233, P405, and P501 (click each P-code to see the statement)

Aggregated GHS information provided per 44 reports by companies from 4 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.

Changes in various enzyme activities were observed in high-dose animal studies; No evidence of hepatotoxicity, hepatic porphyria, fetotoxicity, or teratogenicity; [HSDB] Causes other changes in liver in animal experiments; [RTECS] A skin, eye, and mucous membrane irritant; [CAMEO] See Hexachlorobenzene.

Simple aromatic halogenated organic compounds, such as HEXABROMOBENZENE, are very unreactive. Halogenated organics generally become less reactive as more of their hydrogen atoms are replaced with halogen atoms. Materials in this group may be incompatible with strong oxidizing and reducing agents. Also, they may be incompatible with many amines, nitrides, azo/diazo compounds, alkali metals, and epoxides.

EYES: First check the victim for contact lenses and remove if present. Flush victim's eyes with water or normal saline solution for 20 to 30 minutes while simultaneously calling a hospital or poison control center. Do not put any ointments, oils, or medication in the victim's eyes without specific instructions from a physician. IMMEDIATELY transport the victim after flushing eyes to a hospital even if no symptoms (such as redness or irritation) develop.

SMALL SPILLS AND LEAKAGE: If you spill this chemical, FIRST REMOVE ALL SOURCES OF IGNITION, then dampen the solid spill material with toluene, then transfer the dampened material to a suitable container. Use absorbent paper dampened with toluene to pick up any remaining material. Your contaminated clothing and absorbent paper should be sealed in a vapor-tight plastic bag for eventual disposal. Solvent-wash all contaminated surfaces with toluene followed by washing with a soap and water solution. Do not reenter the contaminated area until the Safety Officer (or other responsible person) has verified that the area has been properly cleaned.

SRP: At the time of review, criteria for land treatment or burial (sanitary landfill) disposal practices are subject to significant revision. Prior to implementing land disposal of waste residue (including waste sludge), consult with environmental regulatory agencies for guidance on acceptable disposal practices.

RECOMMENDED RESPIRATOR: Where the neat test chemical is weighed and diluted, wear a NIOSH-approved half face respirator equipped with an organic vapor/acid gas cartridge (specific for organic vapors, HCl, acid gas and SO2) with a dust/mist filter. (NTP, 1992)

The halogenated benzenes, inducers of xenobiotic metabolism, were studied for their effects on the metabolism of malathion, malaoxon (lindane), and paraoxon and on the toxicity and lethality of these organophosphorus insecticides and parathion. One mmol/kg of 1,4-dichlorobenzene (p-dichlorobenzene), 1,2,4-trichlorobenzene, 1,4-dibromobenzene, 1,2,4-tribromobenzene, or hexabromobenzene or 0.1 mmol/kg hexachlorobenzene was administered po to male mice daily for 7 days. In general, the trihalogenated benzenes increased the LD50 of all 4 insecticides 2- to 6-fold. These increases were larger than those observed with the di- or hexahalogenated isomers. The bromide-substituted benzenes were usually more active than the chlorinated ones with the exception being hexabromobenzene. There was a good correlation between their effects on lethality and increases in in vitro carboxylesterase activity with either-malathion or malaoxon as the substrate. The trihalogenated benzenes decreased the inhibitory effect of malathion on cholinesterase activity in the brain and to a lesser degree in the red blood cells, but not in 1iver or plasma.

TERRESTRIAL FATE: Based on a recommended classification scheme(1), an estimated Koc value of 48,000(SRC), determined from a measured log Kow(2) and a recommended regression-derived equation(3), indicates that hexabromobenzene will be immobile in soil(SRC). Volatilization of hexabromobenzene may be important from moist soil surfaces(SRC) given an estimated Henry's Law constant of 2.8X10-5 atm-cu m/mole(SRC), using a fragment constant estimation method(4). Volatilization from dry soil surfaces(SRC) is not expected based on an estimated vapor pressure of 1.6X10-8 mm Hg(SRC), determined from a fragment constant method(5). Based on limited data, this compound is expected to be resistant to biodegradation(6); 8 and 10% biodegradation was reported for river water and seawater inocula, respectively, after a 3 day incubation(7).

AQUATIC FATE: Based on a recommended classification scheme(1), an estimated Koc value of 48,000(SRC), determined from a measured log Kow(2) and a recommended regression-derived equation(1), indicates that hexabromobenzene should adsorb to suspended solids and sediment in water(SRC). Hexabromobenzene may volatilize from water surfaces(1,SRC) based on an estimated Henry's Law constant of 2.8X10-5 atm-cu m/mole(SRC), developed using a fragment constant estimation method(3). Estimated half-lives for a model river and model lake are 3 and 32 days, respectively(1,SRC), although adsorption to sediment and particulate matter may attenuate this process(SRC). The volatilization half-life from a model pond, taking into account adsorptive processes, is 114 months(8). Conflicting data are available on the bioconcentration of hexabromobenzene in fish and aquatic organisms. In short-term studies (4-16 days), hexabromobenzene was found to be non-accumulative in fish(4,5); however, in a 96 day study using rainbow trout, a mean bioconcentration factor of 1,100 was obtained(6). It was suggested that non-accumulation of this compound in guppies was due to the size of hexabromobenzene, resulting in a lack of membrane permeation(4). Based on limited data, this compound is expected to be resistant to biodegradation(7); 8 and 10% biodegradation was reported for river water and seawater inocula, respectively, after a 3 day incubation(9).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), hexabromobenzene, which has an estimated vapor pressure of 1.6X10-8 mm Hg at 25 °C(2,SRC), will exist solely as a particulate in the ambient atmosphere. Particulate-phase hexabromobenzene may be physically removed from the air by dry deposition(SRC). Degradation by direct photolysis(4) is not expected to occur.

Hexabromobenzene

Hepatic

2 x 10 ^-3 mg/kg-day

The Koc of hexabromobenzene is estimated as approximately 48,000(SRC), using a measured log Kow of 6.07(1) and a regression-derived equation(2,SRC). According to a recommended classification scheme(3), this estimated Koc value suggests that hexabromobenzene is immobile in soil(SRC).

Acute inhalation toxicity was evaluated in groups of 10 male Manor Farms rats and 10 male ChR-CD rats exposed to hexabromobenzene at a concentration that was not reported for a period of 4 hours. Mortality and the LC50 were not reported. Clinical observations for both strains of rats included salivation, irregular respiration, lacrimation, exophthalmos, a reddish nasal discharge, and tremors. Gross necropsy revealed necrotic tracheitis and slight testicular degeneration accompanied by suppressed spermatogenesis in the Manor Farms rats and necrotic and diphtheritic tracheitis, bronchiolitis, bronchitis, and murine pneumonia in the ChR-CD rats.

Hexabromobenzene's possible production and use as a flame retardant(1) may result in its release to the environment through various waste streams(SRC). Hexabromobenzene may enter the environment as a fugitive emission from its use as a flame retardant(SRC). In Japan, hexabromobenzene is used as a flame retardant in items such as plastics, paper, and electric manufactured goods(2). Hexabromobenzene may also enter the environment as a result of the high temperature breakdown of octabromodiphenyl ether, decabromodiphenyl ether, pentabromophenol, and hexabromobiphenyl, all which are used as flame retardants(3). Hexabromobenzene was formed during the pyrolysis of decabromodiphenyl oxide(4). Accidental fire residues in private residences contained 1,3,5-tribromobenzene, 1,2,4,5-tetrabromobenzene, and hexabromobenzene as an unquantitated mixture(5). Hexabromobenzene may be formed during the natural debromination of decabromobiphenyl ether during photolysis(6).

Hexabromobenzene was listed as non-biodegradable in a Japanese MITI screening BOD test(1). The biodegradability of hexabromobenzene, at 0.5 ppm, was measured using the cultivation method; 8 and 10% biodegradation was reported for river water and seawater inocula, respectively, after a 3 day incubation(2).

Sediment samples collected from 17 sites in Japan during 1981-1983 contained hexabromobenzene at concentrations ranging from 5.6 to 60.1 ug/kg for river samples to <0.5 (below detection) to 6.2 ug/kg for estuary samples(1). A sediment sample collected from the Second Neya River in Osaka, Japan in 1983 contained hexabromobenzene at 0.017 mg/l(2).

Conflicting data on the bioconcentration of hexabromobenzene has appeared in the literature. Juvenile Atlantic salmon (Salmo salar) did not take up hexabromobenzene from either water or contaminated food over a 4 day period(1). This compound did not bioconcentrate in 1 year old male guppies (Poecilia reticulat) following a 16 day exposure period(2); the lack of bioconcentration was thought to be due to the size of this molecule resulting in a lack of membrane permeation(2). Hexabromobenzene was listed as a chemical compound confirmed to be non-accumulative in screening studies(3), and hexabromobenzene has been reported to have a bioconcentration factor (BCF) of approximately 10(4). In a 96 day experiment in a flow-through tank, hexabromobenzene had a mean BCF in rainbow trout (Salmo gairdneri) of 1,100(5); in the first 7 days of this experiment, no hexabromobenzene was detected in whole fish samples(5). According to a classification scheme(6), these BCF values suggest that bioconcentration in aquatic organisms can range from low in short term studies to very high in long term studies(SRC).

To study the metabolic fate of hexabromobenzene (HBB) in female rats, 16.6 mg/kg body wt was given orally every other day for 2 wk and the animals' excreta were examined for metabolites. Unchanged hexabromobenzene pentabromobenzene, O- and S-containing metabolites were detected in feces and urine. The S-containing substances contained free mercapto groups except for the presence in feces of a methylmercapto derivative. The amt of S-containing metabolites was 15-fold greater than that of O-containing cmpd.

Pregnant Wistar rats were given hexabromobenzene (>99% pure) at 25-200 mg/kg by oral intubation on days 6-15 of gestation. The rats were killed on day 22. The concn of hexabromobenzene was highest in the fat. The compound was present in the maternal liver, brain, heart, kidney, and spleen, as well as in fetal tissue. ... Reported that fat was the only tissue in which the concentration showed a dose response relationship.

A study of the occurrence of hexabromobenzene and its debrominated compounds in human adipose tissue was conducted. Human adipose tissues were obtained from Shikoku Center Hospital, Matsuyama, Japan. The extracts were analyzed by gas chromatography/mass spectrometry. Hexabromobenzene, pentabromobenzene, and 1,2,4,5-tetrabromobenzene were detected at concentrations of 2.1 to 4.1 ng/g. 1,2,4,5-Tetrabromobenzene was found in largest amount, followed by hexabromobenzene and pentabromobenzene in that order. The samples also contained 350 to 1400 ng/g polychlorinated-biphenyls, 1100 to 1800 ng/g total DDT, and 20 to 92 ng/g hexachlorobenzene. Pentabromobenzene and 1,2,4,5-tetrabromobenzene found in human adipose tissue may be metabolism products of hexabromobenzene.

Movement of brominated benzenes in rat and mice was investigated. The concentration of hexabromobenzene following continuous ip administration reached the highest value 16.3 (liver) to 28.8 days (brain) after administration. The biological half life of hexabromobenzene ranged from 2.0 (kidney) to 4.1 days (brain) in the 1st phase of excretion, and from 5.2 (kidney) to 7.3 days (adipose tissue) in the 2nd phase of excretion.

The distribution and excretion of hexabromobenzene and hexachlorobenzene were studied in male Wistar-rats fed 0.2 mg of hexabromobenzene or hexachlorobenzene orally in 1 ml of corn oil. On the first day, 10% of the hexabromobenzene dose and 5% of the hexachlorobenzene dose was detected in the feces; very minimal excretion of hexabromobenzene in feces was found subsequently. By day four, cumulative excretion of hexabromobenzene and hexachlorobenzene plateaued at about 10% of the given dose, indicating a similar course of intestinal absorption for both chemicals. Urinary excretion did not appear to be a significant route of excretion for either compound. Concentrations of hexabromobenzene and hexachlorobenzene in blood were nearly the same during the first 8 hours but diverged after day one and indicated a faster metabolism of hexabromobenzene. Rapid metabolism of hexabromobenzene was also shown by the concentration curve in liver; the highest liver concentrations were found within 1 hour of administration. Maximum hexachlorobenzene concentrations appeared 4 to 24 hours after administration. The hexabromobenzene concentration curve in the kidney was similar to that of the liver, thus hexabromobenzene might be carried from the liver to kidney directly, indicating that kidney has no, or very little, metabolic capacity for hexabromobenzene. In adipose tissue, the course patterns of concentration of hexabromobenzene and hexachlorobenzene were similar but the concentration of hexachlorobenzene was much higher. The elimination of hexabromobenzene from the rat body was clearly biphasic, while that of hexachlorobenzene was not. The half lives for hexachlorobenzene were 0.7 for phase-I and 48 days for phase-II and the half life for hexachlorobenzene was 20 days.

Used as a flame retardant for polymers; [HSDB]

As flame retardant (on a developmental basis)

As a flame retardant used in polymers

(1972) PROBABLY GREATER THAN 9.08X10+5 G

(1975) PROBABLY GREATER THAN 4.54X10+5 G