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PubMed1999

Comparative evaluation of the genotoxic properties of potassium bromate and potassium superoxide in V79 Chinese hamster cells.

The genotoxic potential of two oxidizing compounds, potassium bromate and potassium superoxide, was comparatively tested in various genotoxicity tests with V79 Chinese hamster cells. Both substances clearly induced cytotoxicity, chromosome aberrations and increased DNA migration in the alkaline comet assay. Using a modified comet assay protocol with FPG protein, a DNA repair enzyme which specifically nicks DNA at sites of 8-oxoguanines and formamidopyrimidines, we detected oxidative DNA base damage only after potassium bromate treatment. HPLC analysis also revealed significantly increased levels of 8-oxodeoxyguanosine after potassium bromate treatment but not after potassium superoxide treatment. Furthermore, potassium bromate clearly induced gene mutations at the HPRT locus while potassium superoxide only had a small effect on HPRT mutant frequencies. Molecular analysis of potassium bromate-induced mutations indicated a high portion of deletion mutations. Three out of four point mutations were G to T transversions which typically arise after replication of 8-oxoguanine. Our results suggest that the two oxidizing compounds induce specific patterns of genotoxic effects that reflect the types of DNA alterations induced by different reactive oxygen species (ROS).

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2004

Enhanced bromate control during ozonation: the chlorine-ammonia process.

Potentially carcinogenic bromate forms during the ozonation of bromide-containing waters. Some water treatment facilities have had to use ammonia addition and pH depression to minimize bromate formation, but these processes may prove to be insufficient to comply with upcoming regulations. The chlorine-ammonia process (Cl2-NH3), consisting of prechlorination followed by ammonia addition priorto ozonation is shown to cause a 4-fold decrease in bromate formed when compared to the ammonia-only process. Experiments revealed three key mechanisms: (i) oxidation by HOCl of Br- to HOBr and its subsequent masking by NH3 as NH2Br; (ii) decrease of HO- exposure through halogenation of Dissolved Natural Organic Matter (DNOM) by HOCI and scavenging of HO by NH2Cl; and (iii) DNOM acting as a bromine sink after oxidation of Br- to HOBr. At an ozone exposure of 6 mg/L x min and pH 8, conventional ozonation of Lake Zurich water spiked with 560 microg/L Br- formed 35 microg/L BrO3-, whereas the application of the Cl2-NH3 process resulted in 5 microg/L BrO3-. Additional pH depression to pH 6 further decreased bromate formation by a factor of 4. Trihalomethanes (THM) and cyanogen chloride (CNCl), that mayform during prechlorination and monochloramination, respectively, were well below regulatory limits. The chlorine-ammonia process holds strong promise for water treatment facilities struggling with a bromate formation problem during ozonation.

Ammonia↗
PubMed2005

Evaluation of bromate ions level introduced by sodium hypochlorite during post-disinfection of drinking water.

During the last ten years, interest concerning the occurrence of bromate in drinking water has grown due to its potential carcinogenicity and the new regulations. One source of bromate in finished water is due to its presence in the sodium hypochlorite solutions used for the disinfection of water. In fact, the brine solutions used for the production of sodium hypochlorite contain bromide ions in varying degrees that subsequently generate a certain quantity of bromate ions. Bromate concentrations ranging from 82 to 857 mg l(-1) (0.5-7.4 mg BrO3-/ g Cl2) have been found in commercial solutions of sodium hypochlorite used by Société Anonyme Gestion des Eaux de Paris (SAGEP), a company that produces drinking water for Paris, France. In addition, the chlorine concentration of the hypochlorite solution can decrease during storage, consequently the added amount of bromate increases for a given applied dose of chlorine.

Bromates↗
PubMed2002

[Improved sensitive determination method for bromate in bread].

An effective clean-up procedure was developed to determine trace levels of bromate in bread by high-performance liquid chromatography with post-column flow reactor detection. Bromate was extracted from bread with deionized pure water. After centrifugation, the supernatant was filtered through a paper filter. The filtrate was filtered through a 0.2 micron nylon filter and chloride ion was removed by an IC-SP M Ag cartridge column or On-Guard Ag cartridge column. The eluate was applied to an Oasis MAX anion exchange cartridge column. The column was washed with 20% acetic acid and water. Bromate was then eluted with 0.5% sodium nitrate solution. The eluate was determined by HPLC with post column flow reactor detection. The method had a quantitation limit of 2 ng/g in bread products. Recoveries of bromate from bread ranged from 68 to 72% at a spiked bromate level of 2-10 ng/g.

Bread↗
PubMed2002

Specific determination of bromate in bread by ion chromatography with ICP-MS.

A sensitive method for detecting bromate in bread by ion chromatography with inductively-coupled plasma mass spectrometry (IC/ICP-MS) was developed. Bromate was extracted from bread with water. The clean-up procedure included a 0.2 micron filter, a C18 cartridge for defatting, a silver cartridge to remove halogen anions, a centrifugal ultrafiltration unit to remove proteins, and a cation-exchange cartridge to remove silver ions. A 500 microL sample solution was applied to IC/ICP-MS. The detection limit and the quantitation limit of bromate in the solution were 0.3 ng/mL and 1.0 ng/mL, expressed as HBrO3, respectively, which corresponded to 2 ng/g and 5 ng/g, respectively, in bread. Recovery of bromate was about 90%, and the CV was about 2%. Based on the detection limit in solution and recovery from bread, the detection limit of bromate in bread was estimated to be 2 ng/g.

Bread↗
PubMed1976

[Peripheral nerve disease associated with acute renal failure due to bromate poisoning].

A case of 21 year old male with neuropathy caused by renal insufficiency was present. He had taken bromate (mixed powder of potassium bromate and sodium bromate) for the purpose of suicide and suffered from acute renal insufficiency and hard of hearing. Renal dysfunction improved gradually by peritoneal dialysis and hemodialysis. However, on the 32th day after the onset, burning pain appeared in the bilateral feets. Following this, he began to complain of the disturbances of superficial and deep sensory below the ankle jerks and the weakness of his toes. Considering the clinical features, we supposed that the disturbance of the peripheral nerve was caused by uremia due to taking bromate. N. suralis was biopsied on the 80th day after the onset and examined electron microscopically. Electroscopical findings was as follows. Degeneration of the Schwann cells and irregularity or destruction of the myelin sheaths were observed. The axoplasm of the myelinated nerve fiber were relatively preserved as compared with the changes of the myelin sheaths. In the unmyelinated nerve fibers, cavity formations were observed. The findings of regeneration were not observed. From the electron microscopical findings, we speculate that the changes of the Schwann cells and the myelin sheaths are primary resulting from the disturbance of the metabolism of the Schwann cells. We speculate that anemia and hypoproteinemia caused by bromate disturbed regeneration.

Acute Kidney Injury↗
PubMed2001

Ammoniacal bromamines: a review of their influence on bromate formation during ozonation.

Ammonia can inhibit the formation of bromate in ozonated drinking water by reacting with free bromine (HOBr/OBr-), an intermediate in bromate formation, to form bromamines. Bromamines do not participate in bromate formation, however, they will decay due to autonomous decomposition and through reaction with ozone and hydroxyl radicals. The reaction with ozone controls the overall decay rate. This reaction also results in a net loss of ammonia from the system, leading to the possibility that all ammonia may be oxidized before the ozone residual in the water is eliminated, allowing bromate formation to resume. This paper presents a review of our understanding of bromamine chemistry and identifies areas that are not adequately understood, which may prevent an accurate estimation of ammonia's impact on bromate formation.

Ammonia↗
PubMed2004

Determination of ranitidine hydrochloride in pharmaceutical preparations by titrimetry and visible spectrophotometry using bromate and acid dyes.

Four new methods using titrimetry and spectrophotometry are described for the determination of ranitidine hydrochloride (RNH) with potassium bromate as the oxidimetric reagent and acid dyes, methyl orange, indigo carmine and metanil yellow. In direct titrimetry (method A), the drug is titrated directly with bromate in acid medium and in the presence of excess of bromide using methyl orange indicator. In back titrimetry (method B), the drug is treated with a measured excess of bromate in the presence of bromide and acid, and the unreacted bromine is determined iodometrically. Both spectrophotometric methods are based on the oxidation of RNH by a known excess of bromate in acid medium and in the presence of excess of bromide followed by estimation of surplus oxidant by reacting with either indigo carmine (method C) or metanil yellow (method D), and measuring the absorbance at 610 or 530 nm. In methods B, C and D, reacted oxidant corresponds to the drug content. The experimental conditions are optimized. Titrimetric procedures are applicable over the ranges 1-10 mg (A) and 1-17 mg (B), and the reaction stoichiometry is found to be 1:1 (BrO(-)(3): RNH). In spectrophotometric methods, the absorbance is found to increase linearly with increasing concentration of RNH, which is corroborated by the calculated correlation coefficient (r) of 0.9984 (C) and 0.9976 (D). The systems obey Beer's law for 2-12 and 1-7 microg ml(-1), for methods C and D, respectively. Method D with a molar absorptivity of 9.82 x 10(4) l mol(-l) cm(-1) is found to be more sensitive than method C ( epsilon = 2.06 x l0(4) l mol(-1) cm(-1)). The limits of detection and quantification are reported for both the spectrophotometric methods. The proposed methods were applied successfully to the determination of RNH in tablets and injections. The reliability of the assay was established by parallel determination by the official method and by recovery studies.

Acids↗
PubMed2004

Lack of genotoxicity of potassium iodate in the alkaline comet assay and in the cytokinesis-block micronucleus test. Comparison to potassium bromate.

Iodine could be added to the diet of human population in the form of iodide or iodate but iodate had not been adequately tested for genotoxicity and carcinogenicity. In the present study, genotoxic effects of potassium iodate were evaluated in vitro using the alkaline comet assay and the cytokinesis-block micronucleus assay on CHO cells and compared to halogenate salt analogues potassium bromate and chlorate and also to their respective reduced forms (potassium iodide, bromide and chloride). The results showed that the comet assay failed to detect the presence of DNA damage after a treatment of cells by potassium iodate for concentrations up to 10 mM. This absence of primary DNA damage was confirmed in the cytokinesis-block micronucleus assay. In the same way, results showed that potassium chlorate as well as potassium iodide, bromide and chloride did not induced DNA damage in the alkaline comet assay for doses up to 10 mM. By contrast, potassium bromate exposure led to an increase in both DNA damage and frequency of micronucleated cells. The repair of bromate-induced DNA damage was incomplete 24 h after the end of treatment. These results seem to indicate that potassium bromate would induce DNA damage by several mechanisms besides oxidative stress.

Animals↗
PubMed2006

DNA damage by bromate: mechanism and consequences.

Exposure of mammalian cells to bromate (BrO3-) generates oxidative DNA modifications, in particular 7,8-dihydro-8-oxo-guanine (8-oxoG). The damaging mechanism is quite unique, since glutathione, which is protective against most oxidants and alkylating agents, mediates a metabolic activation, while bromate itself does not react directly with DNA. Neither enzymes nor transition metals are required as catalysts in the activation. The ultimate DNA damaging species has not yet been established, but experiments under cell-free conditions suggest that neither molecular bromine nor reactive oxygen species such as superoxide, hydrogen peroxide or singlet oxygen are involved. Rather bromine radicals (Br*) or oxides (BrO*, BrO2*) might be responsible. Compared to hypochlorite (ClO-), bromate is much less cytotoxic, probably because the former halite efficiently reacts with proteins and other vitally important cellular constituents. In consequence, oxidative DNA damage and the induction of mutations and micronuclei is easily detectable at non-cytotoxic concentrations of bromate, while DNA damage by hypochlorite is observed only at cytotoxic concentrations and follows a non-linear (hockey-stick-like) dose response.

Animals↗
PubMed2006

Impact of H2O2 and (bi)carbonate alkalinity on ammonia's inhibition of bromate formation.

Ammonia can be used to minimize bromate concentrations by blocking two of three potential bromate formation pathways. It was theorized that (bi)carbonate alkalinity in the presence of ammonia would inhibit bromate formation since the pathway that ammonia does not block requires hydroxyl radicals (OH()), and (bi)carbonate alkalinity is an OH() scavenger. Experiments where (bi)carbonate alkalinity was increased from 50 to 119 mg/L (as CaCO(3)) in the presence of excess ammonia resulted in up to 50% reduction in bromate formation, providing evidence in support of the theory. While OH() is scavenged by (bi)carbonate alkalinity, it is promoted by hydrogen peroxide (H(2)O(2)). When ozone reacts with natural organic matter the H(2)O(2) that is formed may therefore render ammonia less effective. Experiments conducted in this study demonstrated this principle.

Ammonia↗
PubMed2001

Comparison of three post-column reaction methods for the analysis of bromate and nitrite in drinking water.

Three post-column ion chromatographic methods (i.e., a sodium bromide-sodium nitrite method, an o-dianisidine method, and a potassium iodide-ammonium heptamolybdate method) were compared for bromate and nitrite analysis. Also, the effect of direct mixing of the reagents without ion suppressors for the sodium bromide-sodium nitrite method and the potassium iodide-ammonium heptamolybdate method was investigated. For the analysis of bromate, the three methods showed similar method detection limits (0.17-0.24 microg/l) with pneumatic reagent delivery systems. Direct reagent mixing achieved comparable detection limits to the suppressor configuration. The three methods are also compatible with conductivity detection. When used in combination with conductivity detection, this compatibility allows simultaneous analysis of bromate, nitrite, and other common ions in drinking water, such as bromide. It was found that the o-dianisidine method achieves microg/l-level detection of nitrite and bromate with a simpler configuration than the potassium iodide-ammonium heptamolybdate method, while the sodium bromide-sodium nitrite method was not sufficiently sensitive for nitrite analysis at the microg/l level.

Bromates↗
PubMed2002

Determination of trace level bromate and perchlorate in drinking water by ion chromatography with an evaporative preconcentration technique.

A simple sample preconcentration technique employing microwave-based evaporation for the determination of trace level bromate and perchlorate in drinking water with ion chromatography is presented. With a hydrophilic anion-exchange column and a sodium hydroxide eluent in linear gradient, bromate and perchlorate can be determined in one injection within 35 min. Prior to ion chromatographic analysis, the drinking water sample was treated with an OnGuard-Ag cartridge to remove the superfluous chloride and concentrated 20-fold using a PTFE beaker in a domestic microwave oven for 15 min. The recoveries of the anions ranged from 94.6% for NO2- to 105.2% for F-. The detection limits for bromate, perchlorate, iodate and chlorate were 0.1, 0.2, 0.1 and 0.2 microg/l, respectively. The developed method is applicable for the quantitation of bromate and perchlorate in drinking water samples.

Bromates↗
PubMed1999

Ion chromatography determination of trace level bromate by large volume injection with conductivity and spectrophotometric detection after post column derivatisation.

Bromate is a well known by-product produced by the ozonisation of drinking water; the allowed concentration for human consumption has to be regulated to the low microg l(-1) range. A direct injection, ion chromatographic method was developed using a tetraborate eluent with serially connected conductivity and spectrophotometric detection. Bromate was detected after post-column reaction with fuchsin at 520 nm. Sample capacity was investigated by injecting large volumes (up to 6 ml) using a high total hardness and chloride tap water. Linear correlation of bromate response with volumes from 1 ml to 6 ml was demonstrated, the main limitation being the overlapping of the chloride peak with bromate. Up to 1.5 ml sample can be injected without any pre-treatment. With more than 1.5 ml injection volume, a sample pre-treatment with a cartridge in Ag and H form, followed by a 10 min degassing in an ultrasonic bath, was needed. This method was validated by analysing secondary reference materials and real samples from a drinking water treatment plant. The method was linear from the limit of quantification to 20 microg l(-1). Reproducibilities in tap water were 18% (5 microg l(-1), n=12) and 21% (1 microg l(-1), n=4) respectively for 1.5 and 6 ml injection volumes with conductivity detection, and 17% at 0.5 microg l(-1) (n=9) with spectrophotometric detection. Calculated detection limits were 0.5 microg l(-1) (6 ml) ahd 2 microg l(-1) (1.5 ml) for conductivity detection and 0.3 microg l(-1) (1.5 ml) for spectrophotometric detection.

Bromates↗
PubMed2000

Performance evaluation of a method for the determination of bromate in drinking water by ion chromatography (EPA method 317.0) and validation of EPA method 324.0.

The potential carcinogenic nature of bromate has prompted global regulatory agencies, and industrial and academic institutions to publish several methods for the analysis of bromate in both drinking and bottled waters. The United States Environmental Protection Agency (EPA) has reported two methods capable of detecting bromate at or below the promulgated maximum contaminant level of 10.0 microg/l. These methods are EPA Method 300.1 and 317.0. Method 300.1 has been promulgated by EPA for compliance monitoring of bromate under Stage 1 of the Disinfectants/Disinfection By-Products Rule. Due to its sensitivity, selectivity and simplicity, Method 317.0 has been drafted and evaluated for potential use as a future compliance monitoring method. This manuscript describes the performance evaluation work with Method 317.0 and efforts completed at EPA's Technical Support Center that improved the sensitivity of Method 317.0, leading to the development of EPA Method 324.0

Bromates↗
PubMed2005

Modeling Cryptosporidium parvum oocyst inactivation and bromate formation in a full-scale ozone contactor.

The inactivation of Cryptosporidium parvum oocysts and the formation of bromate were assessed simultaneously by performing experiments with a full-scale ozone bubble-diffuser contactor used for drinking water disinfection. Fluorescence-dyed polystyrene microspheres were used as surrogates for C. parvum oocysts. Semi-batch ozonation experiments were performed to determine the fluorescence-intensity decay of individual microspheres, which was measured by flow cytometry. The results obtained with the microspheres were correlated to the inactivation kinetics of C. parvum oocysts by choosing an appropriate threshold fluorescence intensity below which microspheres were considered to be equivalent to nonviable oocysts. A mathematical model was then used to predict the inactivation efficiency and bromate formation. The contactor hydrodynamics were characterized by running tracer tests, and the kinetic parameters for ozone decomposition and bromate formation were obtained by performing batch experiments. Model predictions were in good agreement with full-scale experimental results. Additional model simulations revealed that ozone contactors should be designed with the lowest possible backmixing so that the target inactivation efficiency can be achieved with the lowest possible formation of bromate.

Animals↗
PubMed2000

Interlaboratory trial to determine the analytical state-of-the-art of bromate determination in drinking water.

The new European Directive for water intended for human consumption has established a regulatory level for bromate at 10 microg L(-1). This Maximum Admissible Concentration requires analytical methods with detection limits of a least 2.5 microg L(-1). A project funded by the Standards, Measurements and Testing Programme of the European Commission has enabled the improvement and/or development of methods for the determination of bromate at such concentration levels. This collaborative work was concluded by the organisation of an interlaboratory trial involving 26 European laboratories, which enabled the testing of both a draft ISO Standard method and alternative methods. This paper presents the results of this interlaboratory trial, along with results of a bromate stability study. The progress made with respect to the analytical state-of-the-art for bromate will greatly benefit the quality of measurements carried out in water quality monitoring.

Bromates↗
PubMedDate not supplied

Screening method for the gas chromatographic/mass spectrometric determination of microgram/litre levels of bromate in bottled water.

Bromate can be formed as a by-product of ozone treatment that is sometimes used for the disinfection of municipal water supplies and bottled waters. The US Environmental Protection Agency has proposed a maximum contaminant level (MCL) of 10 micrograms/l for bromate in public drinking water. Should the proposed MCL for bromate become final, it may then be considered for adoption as a bottled water quality standard by the US Food and Drug Administration. This paper reports the development of a gas chromatographic/ mass spectrometric (GC/MS) method for the determination of parts-per-billion (microgram/l) levels of bromate (BrO3-) in bottled water. The GC/MS method was validated by using distilled and deionized Milli-Q water; detection limits, quantitation limits, and recoveries were determined and identities were confirmed by MS on the basis of analyses of test portions fortified with BrO3- at 0.8, 3.8, 7.7, 15, and 46 micrograms/l. The method also was evaluated on the basis of recoveries determined for two commercial brands of bottled water fortified with BrO3- at 3.8 and 7.7 micrograms/l and two commercial brands fortified at 0.8, 3.8, and 7.7 micrograms/l. For the Milli-Q water, recoveries ranged from 100 to 121%; for the fortified commercial products, recoveries ranged from 87 to 115%. The limits of detection and quantitation were determined to be 0.4 and 0.7 microgram/l, respectively. Several commercial brands of bottled water were analysed, and BrO3- was found in these products at levels ranging from none to 38 micrograms/l.

Bromates↗