3-Bromphenol

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 640(SRC), determined from a log Kow of 2.63(2) and a regression-derived equation(3), indicates that 3-bromophenol is expected to have low mobility in soil(SRC). The pKa of 3-bromophenol is 9.03(4), indicating that this compound will partially exist in the anion form in the environment and anions generally do not adsorb more strongly to soils containing organic carbon and clay than their neutral counterparts(5). Volatilization of 3-bromophenol from moist soil surfaces is not expected to be an important fate process(SRC) given an estimated Henry's Law constant of 2.2X10-7 atm-cu m/mole(SRC), using a fragment constant estimation method(6). 3-Bromophenol is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 2.0X10-2 mm Hg(SRC), determined from a fragment constant method(7). A theoretical BOD of 0% using activated sludge in the Japanese MITI test(8) suggests that biodegradation is not an important environmental fate process in soil(SRC).

AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 640(SRC), determined from a log Kow of 2.63(2) and a regression-derived equation(3), indicates that 3-bromophenol 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 2.2X10-7 atm-cu m/mole(SRC), developed using a fragment constant estimation method(4). According to a classification scheme(5), an experimental BCF of 4.1 to 10(6) suggests the potential for bioconcentration in aquatic organisms is low(SRC). A theoretical BOD of 0% using activated sludge in the Japanese MITI test(6) suggests that biodegradation is not an important environmental fate process in water(SRC).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), 3-bromophenol, which has an estimated vapor pressure of 2.0X10-2 mm Hg at 25 °C(SRC), determined from a fragment constant method(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase 3-bromophenol 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 0.76 days(SRC), calculated from its rate constant of 2.1X10-11 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(3). The pseudo-first order rate constant for direct photolysis of 3-bromophenol in aqueous solution was reported as 0.104 1/min, corresponding to a calculated half life of 6.7 min(4). This suggests that 3-bromophenol is susceptible to direct photolysis(SRC).

The raw flue gas from a Swedish hazardous waste incinerator, located at Norrtorp, and fed chlorinated (mainly solvents) and brominated waste (tetrabutylammonium bromide) contained 3-/4-bromophenol at 24, 230, and 31 ng/cu m over three tests, respectively; bromides were present initially at 32, 1100, and 530 mg/cu m, respectively(1).

The Koc of 3-bromophenol is estimated as 640(SRC), using a log Kow of 2.63(1) and a regression-derived equation(2). According to a classification scheme(3), this estimated Koc value suggests that 3-bromophenol is expected to have low mobility in soil. The pKa of 3-bromophenol is 9.03(4), indicating that this compound will exist partially in the anion form in the environment and anions generally do not adsorb more strongly to soils containing organic carbon and clay than their neutral counterparts(4).

AEROBIC: 3-Bromophenol, present at 100 mg/L, reached 0% of its theoretical BOD in 2 weeks using an activated sludge inoculum at 30 mg/L in the Japanese MITI test(1). A 25% ring degradation was reported for 3-bromophenol, present at 100 mg/L, over a 4-day incubation period measured with UV absorption in sludge from aerated soil where glucose and peptone were added in mineral salts(2). A first order rate constant of 1.95X10-4 1/hour, corresponding to a half life of 147 days, was determined for 3-bromophenol in unacclimated activated sludge(3). A first order rate constant of 1.48X10-3 was calculated for 3-bromophenol, present at 50 ppm, in cresol acclimated sludge at a pH of 7.2 in a 5-day period. This corresponds to a half life of 19.5 days(4). 3-Bromophenol, present at 50 ppm, reached 100% UV disappearance in >72 days using a Dunkirk soil inoculum with a microbial population of 4 g soil/1 L mineral salts media(5).

ANAEROBIC: 3-Bromophenol, present at 100 uM, degraded in various sediments under anaerobic conditions, as reported in several studies. Under methanogenic and sulfidogenic conditions, degradation was observed within 20-150 days. Activity was maintained by refeeding, and substrate oxidation was coupled to reduction of respective electron acceptors. Under iron-reducing and denitrifying conditions, there was no loss of substrate above sterile controls(1).

An experimental BCF of 4.1 to 10 was calculated in fish for 3-bromophenol using carp (Cyprinus carpio) which were exposed over a 6-week period(1). According to a classification scheme(2), this BCF suggests the potential for bioconcentration in aquatic organisms is low(SRC).

The Henry's Law constant for 3-bromophenol is estimated as 2.2X10-7 atm-cu m/mole(SRC) using a fragment constant estimation method(1). This Henry's Law constant indicates that 3-bromophenol is expected to be essentially nonvolatile from water surfaces(2). 3-Bromophenol is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 2.0X10-2 mm Hg(SRC), determined from a fragment constant method(3).

/ALTERNATIVE and IN VITRO TESTS/ 4-Bromocatechol and the /o-, m- and p-/ bromophenol isomers were nephrotoxicants (measured as increased blood urea nitrogen and decreased accumulation of organic anions by renal cortical slices) but not hepatotoxicants (measured as serum glutamic pyruvate transaminase) in vivo at 0.56 mmol/kg (iv). Preincubation of renal cortical slices with each of these bromobenzene metabolites for 90 min resulted in dose-dependent decreases in the accumulation of p-aminohippurate and tetraethylammonium. At 10 umol/preincubation (2.4 mM), organic ion accumulation was decreased maximally by all bromobenzene metabolites examined while equimolar amounts of bromobenzene were without effect. 4-Bromocatechol was the most potent nephrotoxicant in vitro. Administration of 0.53-2.12 mmol/kg (iv) 4-bromocatechol to mice resulted in a dose-dependent decrease in renal function while hepatic function was altered only slightly at the higher doses. The renal cortical necrosis produced by in vivo administration of 4-bromocatechol could not be distinguished histologically from that induced by bromobenzene. These results demonstrate that 4-bromocatechol and the 3 bromophenol isomers are nephrotoxicants that can be generated from bromobenzene in mice.

/ALTERNATIVE and IN VITRO TESTS/ An in vitro model using a suspension of rabbit renal proximal tubules was developed to investigate the mechanism of nephrotoxicity of bromobenzene. Using oxygen consumption, glutathione concentrations and retention of lactate dehydrogenase activity as markers of toxicity, the rank order of potency was bromobenzene (5 mM) less than 2-bromophenol (2 mM) less than 3-, 4-bromophenol (1 mM) less than 2-bromohydroquinone (0.1 mM). These data support in vivo results and are consistent with the hypothesis that 2-bromohydroquinone or a metabolite thereof is responsible for bromobenzene-induced nephrotoxicity...

/ALTERNATIVE and IN VITRO TESTS/ An in vitro model using a suspension of rabbit renal proximal tubules was developed to investigate the mechanism of nephrotoxicity of bromobenzene. Using oxygen consumption, glutathione concentrations and retention of lactate dehydrogenase activity as markers of toxicity, the rank order of potency was bromobenzene (5 mM) less than 2-bromophenol (2 mM) less than 3-, 4-bromophenol (1 mM) less than 2-bromohydroquinone (0.1 mM). These data support in vivo results and are consistent with the hypothesis that 2-bromohydroquinone or a metabolite thereof is responsible for bromobenzene-induced nephrotoxicity...

/ALTERNATIVE and IN VITRO TESTS/ 4-Bromocatechol and the /o-, m- and p-/ bromophenol isomers were nephrotoxicants (measured as increased blood urea nitrogen and decreased accumulation of organic anions by renal cortical slices) but not hepatotoxicants (measured as serum glutamic pyruvate transaminase) in vivo at 0.56 mmol/kg (iv). Preincubation of renal cortical slices with each of these bromobenzene metabolites for 90 min resulted in dose-dependent decreases in the accumulation of p-aminohippurate and tetraethylammonium. At 10 umol/preincubation (2.4 mM), organic ion accumulation was decreased maximally by all bromobenzene metabolites examined while equimolar amounts of bromobenzene were without effect. 4-Bromocatechol was the most potent nephrotoxicant in vitro. Administration of 0.53-2.12 mmol/kg (iv) 4-bromocatechol to mice resulted in a dose-dependent decrease in renal function while hepatic function was altered only slightly at the higher doses. The renal cortical necrosis produced by in vivo administration of 4-bromocatechol could not be distinguished histologically from that induced by bromobenzene. These results demonstrate that 4-bromocatechol and the 3 bromophenol isomers are nephrotoxicants that can be generated from bromobenzene in mice.

The rate constant for the vapor-phase reaction of 3-bromophenol with photochemically-produced hydroxyl radicals has been estimated as 2.1X10-11 cu cm/molecule-sec at 25 °C(SRC) using a structure estimation method(1). This corresponds to an atmospheric half-life of about 0.76 days at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1). The pseudo-first order rate constant for direct photolysis of 3-bromophenol in aqueous solution was reported as 0.104 1/min. This corresponds to a calculated half life of 6.7 min(2). Continuous exposure to light in a water medium resulted in the formation of the degradation products resorcinol and 3,3'-dihydroxybiphenol(3). 3-Bromophenol is not expected to undergo hydrolysis in the environment due to the lack of functional groups that hydrolyze under environmental conditions(4).

NIOSH (NOES Survey 1981-1983) has statistically estimated that 452 workers (355 of these were female) were potentially exposed to 3-bromophenol in the US(1). Occupational exposure to 3-bromophenol may occur through inhalation and dermal contact with this compound at workplaces where 3-bromophenol is produced or used. Limited monitoring data indicate that the general population may be exposed to 3-bromophenol via inhalation due to the release of this substance from waste incineration(SRC).