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Nonvolatile Mutagens in Drinking Water: Production by Chlorination and Destruction by Sulfite
Abstract
In concentrates of water produced in a laboratory simulation of a drinking water treatment process, direct-acting, nonvolatile
mutagens were readily detected by means of the Ames Salmonella test. The mutagens were shown to be produced by the chlorination
process. Treatment of the water with chloramine resulted in less mutagenic activity than treatment with free chlorine. Dechlorination
of drinking water with sulfite sharply reduced the mutagenic activity. Treatment with sulfur dioxide is proposed as an effective,
inexpensive method of reducing the direct-acting mutagenic activity of drinking water and of aqueous industrial effluents.
... For example, Kawanishi et al. [268] reported the reactivities of sulfite (SO 3 2− ) with DNA in the presence of metal ions and attributed the site-specific DNA damage to ·SO 4 − radical generated from sulfite autoxidized in the presence of Co 2+ . Recently, the oxidative degradation of organic compounds conjugated with sulfite oxidation has been investigated [279][280][281][282][283][284] and is proposed as a new type of advanced oxidation process (AOP) [285][286][287][288][289][290][291][292][293][294][295][296][297][298][299]. In this context, autoxidation of sulfite catalyzed by heavy metals is postulated. ...
... For example, Kawanishi et al. [268] reported the reactivities of sulfite (SO3 2− ) with DNA in the presence of metal ions and attributed the site-specific DNA damage to SO4 − radical generated from sulfite autoxidized in the presence of Co 2+ . Recently, the oxidative degradation of organic compounds conjugated with sulfite oxidation has been investigated [279][280][281][282][283][284] and is proposed as a new type of advanced oxidation process (AOP) [285][286][287][288][289][290][291][292][293][294][295][296][297][298][299]. In this context, autoxidation of sulfite catalyzed by heavy metals is postulated. ...
More than 60 years have passed since UCLA first announced the development of an innovative asymmetric cellulose acetate reverse osmosis (RO) membrane in 1960. This innovation opened a gate to use RO for commercial use. RO is now ubiquitous in water treatment and has been used for various applications, including seawater desalination, municipal water treatment, wastewater reuse, ultra-pure water (UPW) production, and industrial process waters, etc. RO is a highly integrated system consisting of a series of unit processes: (1) intake system, (2) pretreatment, (3) RO system, (4) post-treatment, and (5) effluent treatment and discharge system. In each step, a variety of chemicals are used. Among those, sulfites (sodium bisulfite and sodium metabisulfite) have played significant roles in RO, such as dechlorination, preservatives, shock treatment, and sanitization, etc. Sulfites especially became necessary as dechlorinating agents because polyamide hollow-fiber and aromatic thin-film composite RO membranes developed in the late 1960s and 1970s were less tolerable with residual chlorine. In this review, key applications of sulfites are explained in detail. Furthermore, as it is reported that sulfites have some adverse effects on RO membranes and processes, such phenomena will be clarified. In particular, the following two are significant concerns using sulfites: RO membrane oxidation catalyzed by heavy metals and a trigger of biofouling. This review sheds light on the mechanism of membrane oxidation and triggering biofouling by sulfites. Some countermeasures are also introduced to alleviate such problems.
... 34,41,42,49 It should be noted that in certain bioassays, the dechlorinating agent (sulfite, thiosulfate, or ascorbic acid) was used to control the contact time, which consumes residual chlorine and may destroy certain of the formed DBPs such as organic chloramines. 86,87 The resulting reduction in toxicity has already been observed in vitro 27,88 and in vivo. 81 Therefore, further studies should carefully consider the potential deviation of this undesirable part to toxicity bioassays and explore alternative dechlorination strategies. ...
Wastewater disinfection has attracted attention out of concern about fecal-oral transmission during the Coronavirus-19 (COVID-19) outbreak in China. Disinfection reduces risk posed by waterborne pathogens, however, it threatens ecological safety. Containing residual disinfectant, disinfection by-products (DBPs) and other contaminants, disinfected wastewater effluent has a negative influence on aquatic organisms and the balance of aquatic ecosystem of the recipient water body. Here we reviewed in vivo toxicity bioassays of disinfected wastewater effluent to aquatic organisms in different trophic levels including freshwater organisms and marine organisms. Associated variables, i.e. total suspended solid (TSS), ammonia nitrogen (NH3-N), residual disinfectant and features of effluent (water temperature and sampling season), can significantly affect the results of these in vivo toxicity bioassays. Each typical test organism has its own pros and cons, where species, life stages and test endpoints have crucial influences on bioassays thus they should be taken into account before and during ecotoxicological effect studies. More efforts should be made on more practical bioassays involving scenarios of recipient water in order to better simulate real ecotoxicological effects of disinfected wastewater effluent; extended exposure time should be considered to provide additional insight to long-term or pass-generation ecotoxicological effects approaching true levels in recipient water body.
... Overdependence on chlorine for water treatment might introduce new strains of bacteria that are chlorineresistant [16]. It was suggested that chlorine stimulates mutagens' production in the distribution system as time goes by [17]. ...
Chlorination is a chemical method for water disinfection that has been proved to be highly effective in controlling waterborne diarrheal diseases. Most studies have focused on wells' chlorination or later at household level, whereas there have been relatively few researches evaluating the treatment of reservoirs water. Our study followed a mixed design with a before-and-after comparison. It was conducted in a refugee settlement, Um-Baddah Nevachah, which is located in the western outskirts of Khartoum, Sudan. Baseline total coliform test findings have paired areas of four wells that were labeled as sample or control based on fair coin-tossing. A centrally administered water treatment that contains chlorine was added to intervention wells, whereas the other set was considered as chlorine-free placebo. Data were collected 15 days later from the following four main sources: total coliform count, questionnaire-based experimental data trackers, health center records, and face-to-face interviews. The calculated sample size was 341 with corresponding controls selected by systematic random sampling. We found that both groups' prevalences of waterborne diseases were significantly different before the intervention and they shifted later (p = 0.043 vs. p = 0.496, 95% CI). These findings suggest that reservoir chlorination provides prompt disinfection of well-tank-faucet systems water. Highly credible gastroenteritis is a useful tool to detect cases of gastroenteritis in resources limit settings.
... An early bench-scale treatment simulation study suggested that dechlorination of drinking water with sulfite significantly reduced mutagenic activity (Cheh, Skochdopole, Koski, & Cole, 1980). Thus DBPs were tested for decomposition in the presence of sodium sulfite in subsequent research (Croue & Reckhow, 1989). ...
Haloacetaldehydes (HALs) are considered the third largest group of identified disinfection by-products (DBPs) by weight in drinking water. Toxicological studies demonstrated that HALs are highly cytotoxic compared to other DBPs. This paper reviews and updates the current information on the analysis, occurrence, formation and control of HALs in source water, drinking water, and recreational waters based upon the last 20 years of peer-reviewed research. An update of the analysis of HALs and a comprehensive overview of HAL occurrence in various water types are followed by a series of discussions on its formation and precursors, as well as the control and removal of HALs in water. The manuscript concludes by identifying research needs that should be addressed in future research.
... The Ames test detects mutagens and has been employed for water quality testing since early after its publication in 1975 (Ames et al., 1975). Already then, various water matrices were tested in the assay, including surface water (Pelon et al., 1977;Vankreijl et al., 1980), ozonated recycled water (Gruener, 1978), coal gasification process water (Epler et al., 1978), drinking water (Simmon and Tardiff, 1976;Nestmann et al., 1979;Cheh et al., 1980), marine water (Kurelec et al., 1979), pulp and paper mill effluents (Bjorseth et al., 1979;Carlberg et al., 1980) and different wastewaters (Rappaport et al., 1979;Saxena and Schwartz, 1979). The Ames test is still applied for water quality monitoring, and, according to Claxton et al. (2010), will play an "indispensable role in the foreseeable future of 21st century toxicology". ...
... The first applications of the Ames test in water quality monitoring were conducted as early as in the 1970s, when the assay was applied for mutagenicity screening of various water types including surface water (Pelon et al., 1977;Vankreijl et al., 1980), ozonated recycled water (Gruener, 1978), coal gasification process water (Epler et al., 1978), drinking water (Simmon and Tardiff, 1976;Nestmann et al., 1979;Cheh et al., 1980), marine water (Kurelec et al., 1979), pulp and paper mill effluents (Bjorseth et al., 1979;Carlberg et al., 1980) and different wastewaters (Rappaport et al., 1979;Saxena and Schwartz, 1979). The SOS Chromo (Quillardet et al., 1982) and SOS umu/umuC (Oda et al., 1985) assays were developed in the following decade and are popular screening tools for genotoxicity in environmental waters. ...
The Urban Water Security Research Alliance (UWSRA) is a $50 million partnership over five years between the Queensland Government, CSIRO's Water for a Healthy Country Flagship, Griffith University and The University of Queensland. The Alliance has been formed to address South East Queensland's emerging urban water issues with a focus on water security and recycling. The program will bring new research capacity to South East Queensland tailored to tackling existing and anticipated future issues to inform the implementation of the Water Strategy.
... For genotoxicity testing, post-treatment treatment after AOP is usually done to remove reactive oxygen species (ROS) and other free radicals stemming from treatment. Some researchers showed that post treatment methods such as use of the de-chlorination agents sodium sulfite or sodium thiosulfate mask the mutagenic effect after the sample is concentrated [80,81]. However, at the same time Schneck et al. [82] and Gartiser et al. [83] noted that also the generation of mutagenic artifacts is possible during concentration from the interaction of disinfectants with resins if no post treatment is done. ...
Anti-cancer drugs are chemotherapeutic agents that are designed to kill or reduce proliferating cells. Often times, they interfere directly or indirectly with the cell's deoxyribonucleic acid (DNA). Some of these drugs can be detected in the ng/L concentration range in the aquatic environment and have the potential to be very persistent. Environmental risk assessment is available for few anti-cancer drugs only, relying on predicted data and excluding information on their metabolites and transformation products (TPs). Notably, there is no defined strategy for genotoxicity risk assessment of anti-cancer drugs, their metabolites and TPs in the environment. In fact, the presence of anti-cancer drugs in hospital and municipal wastewaters has not been clearly related to the genotoxic nature of these wastewaters. The few available studies that have sought to investigate the genotoxicity of mixtures derived from treating anti-cancer drugs prior to disposal seem to share the commonality of coupling analytical methods to measure concentration and genotoxic bioassays, namely the Ames test to monitor inactivation. Such limited studies on the environmental fate and effects of these drugs presents an area for further research work. Most importantly, there is a need to characterize their genotoxic effects towards aquatic organisms. Given current environmental risk assessment strategies, genotoxicity risk assessment of these drugs and their TPs would have to include a combination of appropriate analytical methods, genotoxicity bioassays, (bio) degradability and computer based prediction methods such as QSAR studies.
... Dechlorination of drinking water with sulfite drastically reduces the mutagenic activity. Treatment with sulfur dioxide is proposed as an effective, inexpensive method of reducing the mutagenic activity of drinking water [25]. ...
Water is the basic constituent of all living beings; it is, therefore, an essential dietary element and a primary resource. The International standard references concerning drinking-water are various and, based on WHO guidelines (WHO 2004), are diversified in relation to local problems. Disinfection of water for human consumption could be considered the most significant public health measure taken during the last century; destroying pathogens in drinking water has drastically reduced the incidence of waterborne diseases in all industrialized countries. Chlorination is currently used as water treatment due to its action; it is preferred to ozonization because is less expensive and leads to residual action. The use of hypochlorite ion (ClO⁻) is preferred to chlorination by chlorine dioxide (ClO2) and chlorine gas (Cl2); however, it does not guarantee the absolute absence of risks. The addition of those chemicals to water leads to the formation of other compounds, many of which are toxic, as they can cause, among other things, chronic diseases and cancer. This review will primarily highlight the risks that chlorination, as a water purifying treatment, may pose to the population health, as it causes the formation of various by-products, many of which are known to be carcinogenic. Epidemiological studies have been carried out in order to highlight the possible excess of cancer in populations drinking water treated with chlorine or ozone. Trihalomethanes, Haloacetic acid, Haloacetonitriles, 3-chloro-4-dichloromethyl-5-hydroxy-2(5H)-furanone or MX and bromate are all identified as Disinfection/ Disinfection By-Products. The EU directive does not include chlorites as undesirable, while the Italian norm, inspired by the precautionary principle, considers 200 g/l the acceptable threshold. This value was taken from the WHO Provisional Guideline Value, although the latter is just a "guide" and "provisional". Although disinfection brings about carcinogenic molecules, we cannot do without it if we want to prevent the much more severe risks due to the presence of pathogens in water used for human consumption. It is, therefore, necessary to know well the molecules that are formed during the processes of drinking water in order to properly set the necessary treatments for their removal from water resources.
... Similar results that dechlorination decrease the bio-toxicity were also reported. Cheh et al. (1980) and Wu et al. (2012) explicated that dechlorination decreased the genotoxicity of the chlorinated drinking water and secondary effluent. ...
Chlorination was reported to increase the anti-estrogenic activity in reclaimed water from domestic wastewater treatment plants, which may add to the risk of reclaimed water reuse. In order to assess the anti-estrogenic disinfection by-product (DBP) precursors, the anti-estrogenic activity formation potential (AEAFP) during chlorination was studied. Firstly, the conditions for the experimental measurement of AEAFP were determined. A 24-h chlorination experiment was applied for AEAFP measurement. After chlorination, dechlorination using reductive reagents led to significant loss of anti-estrogenic activity formation. In addition, as the presence of ammonia nitrogen and other major chlorine consumers would result in lower anti-estrogenic activity formation, a basic chlorine dose of 3× DOC (mg-Cl2 L(-1)) was adequate for completely transforming the anti-estrogenic DBP precursors while an extra chlorine dose of 8× ammonia-nitrogen + 5× nitrite-nitrogen (mg-Cl2 L(-1)) should be added when there was a high level of ammonia nitrogen and nitrite nitrogen in the reclaimed water. Therefore, 24-h chlorination without dechlorination or using only non-reductive quenching reagents (e.g. ammonium) for dechlorination and a total chlorine dose of 3× DOC + 8× ammonia nitrogen + 5× nitrite nitrogen (mg-Cl2 L(-1)) should be fulfilled for the AEAFP measurement. Moreover, the AEAFP (0.2-2.1 mg-TAM L(-1)) of the reclaimed water samples (n = 20) were further analyzed. The AEAFP was highly correlated to UV254 and the fluorescence volume in excitation emission matrix fluorescence spectrum which can be used as surrogates to indicate the level of the AEAFP and assess the precursors in reclaimed water.
... Concern with potential human health risks associated n.ith drinking water has been heighkned by the widespread recognition in recent years of mutagenic activity exhibited by nonvolatile products (Simmon .and Tardiff 1976;Glatz et al. 1978;Loper 1980;Cheh et al. 1980;Foster 1984;van der Gaag et al. 1982;Grabow et al. 198 1;Kool et al. 1982;Nestrnann et al. 1979;Athanasiou and Kyrtopoulos 1983;Dolara et al. 1981). In addition. ...
Sulfur dioxide derivatives (HSO3⁻ and SO3²⁻) play an important role in food preservative, antibacterial, antioxidant and other aspects, so it is urgent for us to develop more efficient detection methods to broaden their application in biochemical research and related disease diagnosis. Fluorescent probes are of particular interest because of their simplicity and high temporal and spatial resolution. Herein, we constructed a new near-infrared (NIR) fluorescence probe, CQC, composed of coumarin fluorophore and quinoline fluorophore, for detecting SO2 derivatives. The near-infrared emission probe CQC with a large Stokes shift (260 nm) not only kept the distance between the two emission peaks large enough (165 nm), but also had a particularly high energy transfer efficiency (99.5%), and was particularly sensitive to the detection of HSO3⁻/SO3²⁻ (LOD: 0.1 μM). The powerful probe CQC succeeded in real-time visualizing endogenous HSO3⁻/SO3²⁻ in living cells.
The first edition of Bioanalytical Tools in Water Quality Assessment was released in 2012. The field has exploded since and the second edition updates and reviews the application of bioanalytical tools for water quality assessment including surveillance monitoring. The book focuses on applications to water quality assessment ranging from wastewater to drinking water, including recycled water, as well as treatment processes and advanced water treatment. Emerging applications for other environmental matrices are also included. Bioanalytical Tools in Water Quality Assessment, Second Edition, not only demonstrates applications but also fills in the background knowledge in toxicology/ecotoxicology needed to appreciate these applications. Each chapter summarises fundamental material in a targeted way so that information can be applied to better understand the use of bioanalytical tools in water quality assessment.
The book can be used by lecturers teaching academic and professional courses and also by risk assessors, regulators, experts, consultants, researchers and managers working in the water sector. It can also be a reference manual for environmental engineers, analytical chemists and toxicologists.
ISBN: 9781789061970 (Paperback)
ISBN: 9781789061987 (eBook)
Four species of alien parasites, Dactylogyrus skrjabini Achmerow, 1954, D. hypophthalmichthys Achmerow, 1952, D. wuhuensis Lee, 1960 (Platyhelminthes: Monogenea: Dactylogyridae), and Sinergasilus lieni Yin, 1949 (Crustacea: Copepoda: Ergasilidae), were collected from the gills of the alien cyprinid, the silver carp Hypophthalmichthys molitrix (Valenciennes, 1844) in the Watarase River flowing into the Watarase Retarding Basin, Tochigi Prefecture, central Japan. These alien parasites represent new geographical records from Japan. The generic position of D. skrjabini has been doubted because its dorsal anchor shape is similar to those of Pellucidhaptor spp. (Dactylogyridae), but the species should be assigned to Dactylogyrus based on the phylogenetic analysis of 28S rDNA made in this study. The scientific name “Pseudergasilus polycolpus Markewitsch, 1939” is an incorrect subsequent spelling of P. undulatus Markewitsch, 1940, and S. lieni is the oldest available name that can be applied to the ergasilid found in this study.
Sulfur dioxide (SO2) had been recognized as an environmental pollutant produced from industrial processes. SO2 is water soluble and forms hydrated SO2 (SO2·H2O), bisulfite ion (HSO3-), and sulfite ion (SO32-) upon dissolution in water. SO2 could be also produced endogenously from sulfur-containing amino acids l-cysteine in mammals. Endogenous SO2 can maintain the balance of biological sulfur and redox equilibrium in vivo, regulate blood insulin levels and reduce blood pressure. Excess intake of exogenous SO2 can result in respiratory diseases, cardiovascular diseases and neurological disorders. As a result, fluorescent probes to detect HSO3-/SO32- have attracted great attention in recent years. Herein, a general overview was provided with the aim to highlight the typical examples of the HSO3-/SO32- fluorescent probes reported since 2010, especially those in the past five years. We have classified HSO3-/SO32- fluorescent probes through different chemical reaction mechanisms and wish this review will give some help to the researchers in this field.
A rapid cell-permeating probe NJUXJ-1 was introduced for sensitive and selective detection of sulfite in living cells. It generate a turn-on response to sulfite with high sensitivity (detection limit 13.0 nM), selectivity (in physiological level) and low toxicity. The fluorescence of detecting system was steady for wide pH range (5-8) and long period (over 12 h). The most attractive point, its rapid cell-permeating ability, made it ready for bioimaging with a 2-min incubation and shortened the whole detecting period (cell-permeating and reaction), thus could decrease background interference. It offered a convenient approach for determining exogenous or endogenous sulfite level in living cells and further applications.
The potent bacterial mutagen Z-2-chloro-3-(dichloromethyl)-4-oxobutenoic acid (“MX”, acyclic form) was reacted with structurally simple nucleophiles (amines, thiol, hydroxide) and the reaction products were studied by chromatographic and spectroscopic methods. MX reacted rapidly with all the nucleophiles used. The initial reaction in organic solvents was ring opening via an acid-base reaction, followed by a nucleophilic attack on the aldehydic carbon atom. The possibility of ring opening (generation of an aldehydic function) seemed to be an important factor for the electrophilicity of MX.
The stabilities of MX, its E-isomer (E-2-chloro-3-(dichloromethyl)-4-oxo-butenoic acid, “E-MX”), and its methyl ether (3-chloro-4-(dichloromethyl)-5-methoxy-2(5H)-furanone, “Me-MX”), were studied under simulated Ames test conditions. Me-MX was hydrolysed to MX within five hours of incubation. Simultaneously, the MX formed was partly isomerized to E-MX, and further hydrolysed to a highly hydrophilic product. These results, together with mutagenicity data obtained for Me-MX and MX, strongly indicate that the extremely high mutagenic activity previously reported in the literature for Me-MX, at least partly might have been generated by MX formed during the incubation time of 48 hours used in the Ames test.
The primary purpose for disinfection of drinking water is to destroy and eliminate pathogenic organisms responsible for waterborne diseases. Commonly used disinfectants are chlorine, chlorine dioxide, chloramine, and ozone. The most widely used disinfectant is chlorine. Chlorine has many advantages as it is toxic to many microorganisms, is cheaper than most other disinfectants, can be prepared in situ, and is not critically sensitive to pH and temperature variations (3). However, the very reactivity of chlorine produces problems. Especially harmful are the reactions with organic compounds present in water resulting in halogenated organics (4,14).
The halogens—fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At)—make up group 17 (VIIA) of the elements. Because of their propensity to form salts [the standard potentials (E
0, volts) for the oxidation of halides (2X−→X2 + 2e
−) are −3.06, −1.36, −1.07, and −0.54 for fluorine, chlorine, bromine, and iodine, respectively], Berzelius designated these elements as “halogens” (Greek hals, sea salt; gennao, I beget). The halogens make up a particularly well defined family, having the most regular gradation of physical properties of all the families of elements. Thus, an almost perfect doubling of atomic weights on going from one halogen to the next down the periodic table is accompanied by an increase in specific gravity, melting points, and boiling points, and a decrease in water solubility and chemical reactivity (Table 1–1) (Stokinger, 1981). The concentrations of the halogens found in seawater and in the lithosphere are given in Table 1–2.
In our previous presentation in this Symposium series, we described the development of a coupled Salmonella mutagenesis/reverse-phase high performance liquid chromatography (HPLC) procedure for the subfractionation of mutagens from complex mixtures of drinking water organics. Using the 20-year-old drinking water residue mixture available to us at that time, we demonstrated the reproducibility of this system. A group of potent, microsomal-activation-dependent, strain TA100 mutagens was detected and partially purified. For one of the repeat HPLC subfractions, further purification by gas chromatography (GC) of multiple aliquots on an SE 30 column yielded 10-μg amounts of purified compound (Tabor and Loper, 1980; Loper and Tabor, 1981). This substance is the “something old” alluded to in our title. Part of the “something new” is that we have determined this substance to be a previously unrecognized mutagen; we will have more to say about it later (see Discussion).
Myeloperoxidase (MPO) is a heme-containing enzyme that, in the presence of peroxide and halide ions, is effective in killing various microorganisms; in addition, it exerts a wide variety of extracellular functions. Polymorphonuclear leukocytes (PMN) are the main source of this enzyme. MPO is a myeloid cell-specific enzyme whose synthesis is tightly regulated at the promyelocyte stage of differentiation of myeloid cells. This review will consider recent developments concerning the biochemical and molecular structure, biosynthesis and processing, and various possible functions of MPO.
The feasibility of using a battery of short-term bioassays for the detection of mutagens and potential carcinogens released into the environment as a result of land treatment of hazardous waste is being investigated. Land treatment is the incorporation of a waste into the upper layer of soil resulting in the degradation or attenuation of hazardous waste constituents. EPA (1980) regulations state that a waste cannot be applied to the soil unless the waste is rendered less hazardous or nonhazardous by chemical or biological reactions in the soil. Biological analysis provides the only means of demonstrating a reduction in hazardous characteristics since chemical analysis fails to account for the Interactions of the components of a complex mixture, the production of mutagenic metabolites via degradative pathways, and the chemical combination of nontoxic precursors to form mutagenic compounds.
Drinking water contains a range of natural and anthropogenic contaminants which vary between water sources and with time. Toxicity tests based on bacteria, cells in tissue culture, plants and even vertebrates in vivo have been used to screen drinking water or concentrates from drinking water. These tests use a variety of endpoints from basal cytoxicity to effects on DNA. Although they cannot be used to directly estimate risk to man, they are valuable tools and have been used successfully, particularly in research on drinking water treatment.
The respiratory burst of neutrophilic granulocytes is a metabolic response of these cells to signals of infection. This metabolic pathway starts with markedly increased oxygen uptake,1,2 resulting in production of primary and secondary products, harmful to invaders.3,4
An RPLC-postcolumn detection method has been developed for the fluorimetric determination of dichloroacetamide (DCAD) in water. After ammonia and DCAD were separated on a C18 nonpolar stationary phase with 2.5% methanol-0.02 M phosphate buffer at pH 3, the column eluant was reacted with post column reagents, o-phthaldialdehyde (OPA) and sulfite ion at pH 11.5, to produce a highly fluorescent isoindole fluorophore, which was measured with a fluorescence detector (λex = 363 nm, λem = 425 nm). With the optimized conditions for RPLC and the postcolumn derivatization, the calibration curve was found to be linear in the concentration ranges of 0.5 and 20 μM for DCAD, and the detection limit for DCAD was 0.18 μM (23 μg/L). This corresponded to 18 μmol per 100 μL injection volume for a signal-to-noise ratio of 3, and the repeatability and reproducibility of this method were 1.0% and 2.5% for five replicate analyzes of 2 μM DCAD, respectively. The degradation yields DCAD to ammonia were 94 and 99%, and the percent recoveries of DCAD from 4 and 6 μM DCAD-spiked tap water were shown mean more than 97%.
Drinking water has to be disinfected before it is distributed from the water treatment plant. The disinfectant in widest use, chlorine, suffers the major drawback that it reacts with the organic material not removed during purification and the chlorinated organic compounds that are produced constitute a health risk. The major organochlorine compounds found in chlorine disinfected drinking water are trihalomethanes, haloacetic acids and haloacetonitriles. Chlorine disinfected drinking water also contains compounds that induce mutagenicity in the Ames assay. The mutagenicity is mainly due to the chlorohydroxyfuranones and especially to the very potent mutagen MX (3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone). Over the last 20 years, water treatment plants have vastly improved their methods for disinfection and the removal of organic material. This is reflected in a drastic decrease in the concentrations of disinfection products. Some treatment plants are using alternative disinfectants, such as a combination of chlorine and chlorine dioxide, or ozone and chloramine. Although these disinfectants also produce by-products, they seem to be less harmful than those produced by chlorination.
The mutagenicity assessment for samples collected from a lab-scale water reclamation system, which included the influent, samples after microfiltration (MF) and reverse osmosis (RO) were carried out. Influent water was found to be mutagenic to TA98 (±S9) and non-mutagenic to TA100 (±S9). Samples after MF and RO were mutagenic to both the bacteria strains (±S9), with much higher mutagenic ratio (MR) values observed got MF filtrates. Comparing the specific mutagenic activities of the samples, it was found that there was an overall reduction, approximately 10-fold in mutagenicity from the influent to the treated water. Reduction in mutagenicity was also seen after the RO process but increase after the MF process. This was attributed mainly to the chlorination process before and after MF process, which could have contributed to DBPs' formation. However, due to the dissolved organics removal by RO process, the specific mutagenicity was largely reduced. RO was found to be very efficient at reducing mutagenicity of treated water. © 2005 American Water Works Association WQTC Conference All Rights Reserved.
The National Water Research Institute 2014 Clarke Prize consists of a medallion and $50,000 to the winner. David Sedlak was selected as the 2014 recipient because of his pioneering research on advancing the way water resources and urban water infrastructure are managed, including implementing water reuse and reducing the discharge of emerging contaminants. His work has served as the foundation for major policy and technical initiatives to reduce the effects of these contaminants and protect public health. Visit www.water4pointo.com for more on the book. Listen to the author on Moncrieff of NewsTalk, Irish news radio (skip to 7:00 for David Sedlak's interview). Read a Q & A with the author on the Yale Press Log Turn on the faucet, and water pours out. Pull out the drain plug, and the dirty water disappears. Most of us give little thought to the hidden systems that bring us water and take it away when we're done with it. But these underappreciated marvels of engineering face an array of challenges that cannot be solved without a fundamental change to our relationship with water, David Sedlak explains in this enlightening book. To make informed decisions about the future, we need to understand the three revolutions in urban water systems that have occurred over the past 2,500 years and the technologies that will remake the system. The author starts by describing Water 1.0, the early Roman aqueducts, fountains, and sewers that made dense urban living feasible. He then details the development of drinking water and sewage treatment systems-the second and third revolutions in urban water. He offers an insider's look at current systems that rely on reservoirs, underground pipe networks, treatment plants, and storm sewers to provide water that is safe to drink, before addressing how these water systems will have to be reinvented. For everyone who cares about reliable, clean, abundant water, this book is essential reading.
The application of bacterial mutagenicity tests to drinking water has shown the presence of mutagens. Invariably, mutagens generated during water treatment chlorination account for much of the mutagenicity detected in most surface-water-derived drinking waters. These mutagens are formed from widespread, naturally occurring precursors, such as humic substances, although other substances, especially amino acids may be involved. Most of the chlorination-derived mutagens identified account for little of the mutagenicity of drinking water. However, one mutagen, MX, is highly potent and may have a significant contribution. Its occurrence and toxicity need full evaluation. Other oxidants/disinfectants, such as ozone and chlorine dioxide, can also generate mutagens but these are likely to differ from those produced by chlorination. Granular activated carbon is effective in removing chlorination-derived mutagens but less effective for precursors. Dechlorinating agents, such as sulphur dioxide, can eliminate some of the mutagens produced by chlorination. The bacterial mutagenicity test cannot give information on the actual risks to health posed by the mutagens. Such information could arise from follow up work on identified major mutagens and from application of other bioassays more indicative of effects in man. Consequently, at the present time it is difficult to justify major changes to treatment practice aimed solely at controlling mutagenicity.
In a review of research results available since a previous review in 1980, the author discusses the toxicological hazards associated with alternative means of disinfecting drinking water. These hazards can be associated with the disinfectants themselves as well as with the products formed when disinfectants react with organic material present in the water. Effects of disinfectants - chlorine, chlorine dioxide, and monochloramine - and by-products - chlorite, chlorate, trihalomethanes, and haloacetonitriles - are considered.
Recent epidemiological studies conducted in Finland have reported a positive correlation between the mutagenicity of chlorinated drinking waters and certain human cancers. In these studies, past exposure to drinking water mutagenicity was assessed using a model developed by Vartiainen et al. [1] based on data collected in Finland. In this model, mutagenicity, as determined in the Ames assay, is a function of the total organic carbon (TOC) concentration of the water, chlorine dose, and to a minor extent, the concentration of ammonia. A study has been initiated to assess the applicability of this model to source waters and water treatment practices in the United States. Water samples were collected from three full-scale treatment plants and one pilot-scale plant. All the plants used chlorine exclusively for disinfection. One full-scale plant used ground water. Surface water sources were used by the other plants. TOC and ammonia concentrations were determined analytically and chlorine doses were obtained from the treatment plants. The water samples were concentrated by XAD resin adsorption for testing in the Ames assay. The observed levels of mutagenicity in the finished waters were 1.5 to 2-fold higher than those predicted using the model as specified in Vartiainen et al. [1]. Consequently, further validation is needed prior to widespread use of the Finnish model to assess exposure to mutagenicity in chlorinated drinking waters in the United States.
The Ames Salmonella/ microsomal assay has found extensive application in evaluations of the mutagenic activity of a variety of environmental sample types. A number of investigators have successfully utilized this test system with municipal (Rappaport, 1979; Ellis et al., 1982) and industrial wastewaters. Many of the industrial effluent studies have concentrated on specific manufacturing process types. Separate investigations have demonstrated that wastewaters from pulp mills (Douglas et al., 1980) and coal gasification processes (Epler, 1980) were mutagenic, while numerous textile mill effluents were reported to be nonmutagenic (Rawlings and Samfield, 1979). Two published projects have examined the mutagenicity of effluents discharged from a limited number of industrial process types. Stinett et al. (1981) utilized the Ames assay to evaluate the mutagenicity of 12 unconcentrated effluent samples from a number of types of organic chemical industries. These investigators reported two positive effluent results from organics and plastics facilities, although both of these results did not meet the conventional positive mutagenicity evaluation criterion of a dose response (Chu et al., 1981; Maron and Ames, 1983). The need for concentration of treated wastewater samples prior to mutagenicity testing is generally accepted (Epler, 1980). Somani and co-workers (1980) analyzed concentrates from 12 industrial effluents collected from 9 different process types. Only one sample, a foundry effluent, was found to be mutagenic.
This article reviews the use of the Ames Salmonella assay for assessing the mutagenicity of water produced by various treatment processes. Although chlorination is the most common means of disinfection in North America, chloramines, chlorine dioxide, and ozone have been shown to produce water that is less mutagenically active. Granular activated carbon (GAC) removes mutagens preferentially compared with parameters such as total organic carbon. In the absence of GAC, postchlorination typically increases mutagenicity. Inconsistent interstudy results with respect to the effects of ozone and metabolic activation (S9) and the capacity of GAC point to the role of raw water characteristics in the determination of treated water mutagenicity. In the case of ozone, dosage and contact time may also be important.
Aqueous phenol solutions, as humic model compounds, were treated with chlorine under various experimental conditions. These chlorinated waters after dechlorination and diethyl ether extracts from the waters were tested for their mutagenic effects on TA98 and TA100 strains with and without S9 mix. The diethyl ether extracts were also tested for their product distributions. Aqueous chlorination under an acidic condition generated direct-acting mutagens on TA100 strain from non-mutagenic compounds. These mutagens formed from phenol and its chlorinated derivatives were shown to be both polar and non-polar compounds, while, these produced from cresols, di- and trihydric phenols were polar ones. Higher mutagenic potential formation during aqueous chlorination were observed for simple phenol and p-cresol. The parent compounds were shown to produce a variety of chlorination products, including chlorine-substituted, oxygenated, and hydroxylated compounds. The formation of chlorination products and mutagenic substances was dependent on the reaction pH and chlorine dose. The significance of these findings for water chlorination systems is discussed.
Previously we reported the mutagenicity of drinking water using Salmonella typhimurium TA100 and TA98 with and without S9 mix, and suggested that mutagens might be produced by the chlorination process. It is quite important to determine factors present in our environment affecting the mutagenicity of drinking water. Therefore, as a further study, modifiers of the mutagenicity of drinking water were investigated including dismutagens in order to invent means of the prevention of producing mutagens in drinking water. The mutagenicity of drinking water decreased as the treatment temperature of drinking water samples increased. Freezing and melting treatment of drinking water did not affect the mutagenicity of these samples. The UV irradiations of the samples reduced mutagenicity levels significantly. On the other hand the sunlight did not affect the mutagenicity of drinking water. The mutagenicity of drinking water samples decreased when the samples were treated by reducing agents such as ascorbic acid and glutathion. Especially, glutathion contained in most human tissues, reduced the mutagenicity of drinking water with 100%. It was suggested that the mutagenic compounds in drinking water are electrophilic and the conjugation of electrophiles with glutathion may represent a dismutagenic mechanism.
A simultaneous analytical method has been developed for the fluorimetric determination of haloacetonitriles (HANs) [dichloroacetonitrile (DCAN), trichloroacetonitrile (TCAN), dibromoacetonitrile (DBAN), haloacetamides [dichloroacetamide (DCAD), and trichloroacetamde (TCAD)] in drinking water by using the combined on-line perconcentration/reversed phase liquid chromatography (RPLC)-postcolumn detection system. This on-line perconcentration system was achieved by employing a precolumn packed with a commercial solid phase extraction (SPE) sorbent for the enrichment and purification of the target analytes. The haloacetonitriles and haloacetamides were separated on CN analytical column in a 7.5% methanol-0.02 M phosphate buffered mobile phase at pH 3. The column effluents were reacted with postcolumn reagents of ophthaldialdehyde (OPA) and sulfite ion at pH 11.5, to produce a highly fluorescent isoindole fluorophore, which were measured with a fluorescence detector. Under the optimized conditions for RPLC and the postcolumn derivatization system all of the coefficient of determination of the standard calibration curves for the target analytes were over 0.99 and had a linear range from 5 to 100 . The detection limits showed 1.6 for DCAD, 0.1 for TCAD, 0.6 for DCAN, 1.6 for TCAN and 1 for DBAN, and the recoveries were ranged from 64 to 99% except for DCAD with precisions less than 4.9% in distilled water, and from 72() to 116%() in tap water.
Pilot scale experiments were performed to evaluate the ability of ozonation, ozone/hydrogen peroxide treatment and nanofiltration to reduce levels of organic matter, mutagenicity, total adsorbable halogens, color and turbidity from purified and bank-filtered surface water rich with humic material.Ozonation and ozone/hydrogen peroxide decreased the amount of organic material from drinking water by about 20 percent measured as TOC and CODMn. Color and turbidity level reductions were 49 and 11 percent, respectively. Ozonation reduced the AOX concentrations formed during postchlorination from 150 μgL−1 to 75 μgL−1. The addition of hydrogen peroxide further improved the removal to 37 and 26 μgL−1 depending on the ratio of H2O2/O3. The mutagenicity reduction followed the same pattern: without ozonation the chlorination-derived mutagenicity was 1,450 net revertant L−1 after the ozonation 700 and after the H2O2/O3 treatment from <100 to 400 net revertant L−1 depending on the H2O2/O3 ratio. Nanofiltration appeared to be the most effective way to remove organic material. The removal of TOC was 68%, CODM 72%, color 90%, turbidity 68%, AOX 88%, and mutagenicity 85%.
Water is the basic constituent of all living beings; it is, therefore, an essential dietary element and a primary resource. The International standard references concerning drinking-water are various and, based on WHO guidelines (WHO 2004), are diversified in relation to local problems. Disinfection of water for human consumption could be considered the most significant public health measure taken during the last century; destroying pathogens in drinking water has drastically reduced the incidence of waterborne diseases in all industrialized countries. Chlorination is currently used as water treatment due to its action; it is preferred to ozonization because is less expensive and leads to residual action. The use of hypochlorite ion (ClO-) is preferred to chlorination by chlorine dioxide (ClO2) and chlorine gas (Cl2); however, it does not guarantee the absolute absence of risks. The addition of those chemicals to water leads to the formation of other compounds, many of which are toxic, as they can cause, among other things, chronic diseases and cancer. This review will primarily highlight the risks that chlorination, as a water purifying treatment, may pose to the population health, as it causes the formation of various by-products, many of which are known to be carcinogenic. Epidemiological studies have been carried out in order to highlight the possible excess of cancer in populations drinking water treated with chlorine or ozone. Trihalomethanes, Haloacetic acid, Haloacetonitriles, 3-chloro-4-dichloromethyl-5-hydroxy-2(5H)-furanone or MX and bromate are all identified as Disinfection/ Disinfection By-Products. The EU directive does not include chlorites as undesirable, while the Italian norm, inspired by the precautionary principle, considers 200 g/l the acceptable threshold. This value was taken from the WHO Provisional Guideline Value, although the latter is just a "guide" and "provisional". Although disinfection brings about carcinogenic molecules, we cannot do without it if we want to prevent the much more severe risks due to the presence of pathogens in water used for human consumption. It is, therefore, necessary to know well the molecules that are formed during the processes of drinking water in order to properly set the necessary treatments for their removal from water resources.
Chlorination of lignin and humic material in water produces the strong bacterical mutagen 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-fura-none or its acyclic form Z-2-chloro-3-(dichloromethyl)-4-oxo-butenoic acid (“MX”), and its geometric E-isomer (“E-MX”). Although MX is a trace component in the mixture of chlorination products, it is the main single contributor to the Ames mutagenicity in wood pulp chlorination liquors as well as in chlorinated drinking waters. Higher mutagenicity and higher amounts of MX and E-MX are produced during chlorination under acidic conditions than under neutral conditions. Substitution of chlorine by chlorine dioxide decreases the formation of mutagens. Although E-MX has a much lower mutagenicity than MX the compound is of concern since it can be isomerised to MX. This conversion occurs particularly under acidic conditions. MX reacts with sulfite and sulfide. Sulfite treatment may be a feasible process to remove chlorinated mutagens from both bleaching waters and drinking waters.
To investigate the influence of flanking nucleic acid base pairs on the stability of the guanine-cytosine radical cation (GC+), ab initio Hartree–Fock calculations on 16 DNA base pair triplets were carried out using cc-pVDZ and cc-pVTZ basis sets. Furthermore, second order Møller–Plesset (MP2) correlation energy correction were computed using the cc-pVDZ basis set. The results from homodesmotic reactions suggest that GC+ is energetically most favored when being embedded by two neighboring GC base pairs, while the strongest destabilization of around 39 kJ mol−1 (9.2 kcal mol−1) occurs in the TGC triplet. The destabilization was also found to be dependent on the actual sequence where the nucleotide in 5′ position has a weaker influence than that in 3′ position. As effects from the DNA backbone and further environment are excluded, the results indicates that the strong localization of the positive charge on the middle GC base pair is dominated by electrostatic interactions. Consequences for the DNA in terms of susceptibility to mutations by oxidative damage and charge hopping are discussed.
Removal of a highly potent Ames mutagen, 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) with decrease of its mutagenic potency from an aqueous solution by oxidative (ozonation and addition of H2O2 with or without ferrous ion), reductive (addition of Na2SO3, Na2S2O4 and ascorbic acid), thermal (heating in a boiling water bath) and photochemical (UV irradiation) treatments were investigated. More than 97% of removal of MX (initial amount of 1 mM) and its mutagenicy was achieved by the treatments with and . Hydroxyl radical was an important reactant in these treatments, since the removal of MX was strongly inhibited by the addition of typical hydroxyl radical scavengers, mannitol and L-tryptophan methyl ester. The removal of 1 mole of MX required 2 moles of hydroxyl radical accompanied by the release of 2 moles of chloride ion. In the thermal and photochemical treatments, 59% and 76% of MX and the same portions of its mutagenic potency were removed during 60 min, respectively. The release of 2 moles of chloride ion from 1 mole of MX were also observed in these treatments, but hydroxyl radical did not participitate in the decomposition. In the reductive treatments, 68% of MX was removed by the addition of Na2SO3 during 60 min. However, the decrease of mutagenic potency was 48%. It was strongly suggested that the lack of regularity between the amount of removed MX and the decrease of its mutagenic potency is due to weak addition of SO32− to MX rather than reduction of MX.
A sensitive short-term mutagenicity test, the microscale fluctuation test has been coupled with a concentration method based on adsorption on Sep-PakR C18 cartridges as a method for screening drinking water mutagens. Comparison with XAD-2 concentration method showed that Sep-Pak adsorbed 5 times higher quantity of organics but was slightly less efficient for adsorbing TOX.Microscale fluctuation test was found to be more sensitive than Ames test by testing known direct-acting mutagens and concentrates of drinking water. Samples derived from conventional treatment including chlorination from eight surface water supplies in Norway were concentrated at pH 2 by adsorption on the disposable columns. The adsorbates were tested at different doses by the microscale fluctuation assay. The mutagenic properties of drinking water samples were also related to total organic carbon (TOC), total organic halogen (TOX) and trihalomethanes (THM) concentrations. Dose-related mutagenic responses were found for all the samples with S. typhimurium TA 100 and TA98 strains without metabolic activation. Good relationship was found between mutagenicity data and TOX and THM results. The method showed to be simple, rapid and suitable for routine screening of mutagens in drinking water.
The diethyl ether extract from an aqueous solution of 4-methylphenol after treatment with chlorine was mutagenic to the Ames Salmonella test strain TA100 in the absence of liver homogenate. Gas chromatography-mass spectrometry (GC-MS) showed the occurrence of chlorinated products in the extract: chloro-4-methylphenols, chloro-4-methylquinones and chlorinated 4-methylphenol dimers. The diethyl ether extract was fractionated into several fractions by polyamide thin-layer chromatography (TLC). The fractionated components were examined for mutagenicity by means of Ames assays, and were identified by GC-MS. TLC fractionation of the extract revealed that two components present in the extract are mutagenic. GC-MS analysis indicated the presence of 2,6-dichloro-4-hydroxy-4-methylcyclohexa-2,5-dien-1-one as the major mutagen and chlorinated 4-methylphenol dimers as minor mutagenic compounds in the chlorinated 4-methylphenol solution.
The influence of preozonization, coagulation and double layer filtration on formation and removal of mutagenic activity was studied using XAD-8 extracts collected from neutral and acidic solutions and assaying them in the Salmonella typhimurium microsomal assay. Preozonization of surface water produced direct acting frame shift mutagens which were adsorbed on XAD-8 from neutral solutions. This phenomenon was shown to be dependent on the ozone dose applied. Coagulation with different chemicals and subsequent direct filtration partially reduced the mutagenic activity.
A simple pouring out of “baby‐bottles” after disinfection with hypochlorite solution results in an average residual volume of about 2 ml per bottle. Subsequent preparation of baby food in the contaminated bottles leads to the generation of halogenated organic compounds. The volatile fraction of these compounds was analyzed by gas chromatography in various baby foods after the disinfection procedure. The generated volatile halogenated organic compounds mainly consisted of trihalomethanes. An estimate of the dose ingested by infants is given and the resulting health risk is discussed. Alternatives to chemical disinfection are proposed.
This research utilized the Ames test to determine the mutagenicity of water treated by advanced processes, including ozonation and granular activated carbon (GAC). Raw water samples for this research included those obtained from the Pan Hsin waterworks as well as samples containing humic acids. Treated samples were collected from the pilot‐scale advanced treatment plant. The Ames test was used to measure the mutagenicity of the water after each treatment process. For the Pan Hsin raw water samples treated with ozone or GAC, it was indicated that, regardless of whether samples were preozonated or not, they all showed a mutagenic potency less than 2 once the S9 enzyme was added. This level of mutagenicity is insignificant. The prepared humic acid samples, on the other hand, demonstrated a significant reduction in mutagenicity after the pre‐ozonation process, indicating that preozonation can lower the degree of mutagenicity. Furthermore, the mutagenicity of the prepared humic acid samples gradually decreased after the advanced treatment process. However, when chlorine was added later to these samples, the mutagenicity increased again. This research shows that the use of O3/GAC processes to treat water can successfully lower mutagenicity, indicating a great potential for applications in the treatment of drinking water.
Recent concern has been expressed about health risks due to water consumption, since many mutagenic/carcinogenic substances have been reported to be produced during water purification treatment.Laboratory test with humic acid solutions and field test in the Aqueduct of Turin, were carried out to study the power of some oxidants (NaClO, ClO2 and O3) to produce mutagenicity in drinking water. Direct‐acting non‐volatile mutagens were detected by “Ames Test”;. Both studies showed that chemical oxidants, employed during drinking water treatment, can generate mutagenic load. Water chlorination has been shown to produce more mutagenic activity (NaClO ≫ ClO2) than ozonization treatment.
In order to examine the potential association between chlorinated drinking water and the incidence of pancreatic cancer, a population-based case-control study was performed on data obtained from the Turku area in Finland. The study base was approximately 220,000 persons. All 183 pancreatic cancer cases, diagnosed during 1989–1991, were included in the study. Each case had 2 randomly selected controls. The criterion for the exposure to chlorination by-products (CBPs) was that the subject had had chlorinated drinking water from a surface source available at home. Residential addresses with chlorinated or non-chlorinated water were obtained for up to the previous 20 years prior to diagnosis. The odds ratios (OR) varied between 0.20 and 0.66 depending on the length of the cumulative exposure time. This indicates that those exposed to chlorinated drinking water had a lower risk of contracting pancreatic cancer than the unexposed. The result is in gross agreement with earlier investigations which have mainly shown negative or inadequate associations. The side-effects of drinking water disinfection are unproven, because the published research results are inconsistent. The benefits of chlorination, however, are undeniable. Continuous water disinfection is needed in order to avoid waterborne epidemics and chlorination is the only available method in many countries.
The effects of ozonation, granular (GAC) and biological activated carbon (BAC) in the removal of natural organic matter and precursors of disinfection byproducts from drinking water were studied on pilot scale. Ozonation was determined to be the best method to reduce concentrations of the precursors of AOX, chloroform and mutagenicity, whereas BAC removed organic matter the most effectively. Reductions in TA100 mutagenicity were an average 40%, 4%, 26% in ozonated, GAC and BAC filtered water, respectively. Average reductions of AOX levels were similar at 48%, 7% and 35%, respectively. The chloroform formation potential always increased after GAC filtration.
Pilot plant studies demonstrated that pre-ozonation coupled with controlled use of post-chlorination led to significant reductions in both THM and nonpurgeable organo-halogen (NPOX) compounds. It was also demonstrated that the use of chloramine to provide a residual following pre-ozonation virtually eliminated the formation of THM and NPOX. Batch tests confirmed these conclusions for another high DOC water supply, although the THM and NPOX production per unit of DOC varied between water supplies. The results have significant practical implications for the control of THM and NPOX in drinking water disinfection.
Indications of possible health effects of residue organics in drinking water have been sought using short-term tests of mutagenic and transforming activity. Ten percent or less of the total organic material in drinking water has been identified; the remainder is believed to include thousands of unknown nonvolatile compounds. Residual organics were concentrated from drinking water from representative U.S. cities by reverse osmosis followed by liquid-liquid extraction [yielding the reverse osmosis concentrate-organic extract (ROC-OE) fraction] and sorption-desorption on XAD-2 resin. Samples of these residue organics were provided by the Environmental Protection Agency for bioassay. They were examined for mutagenic activity by using Salmonella tester strains (primarily TA98 and TA100) and for transforming activity by using mouse fibroblasts (BALB/3T3 clone 1-13). City-specific patterns of dose-dependent bacterial mutagenesis and of bacterial toxicity were observed for these samples and for subfractions generated by sequential extractions with hexane, ethyl ether, and acetone. Mutagenic effects were essentially independent of a microsome activation system prepared from liver of Aroclor 1254-induced rats. On the basis of strain-specific effects in mutagenesis and differential distributions of mutagenic activity during liquid-liquid extraction, at least some of the active compounds are thought to be acidic, frameshift mutagens. The ROC-OE fraction of a New Orleans sample transformed BALB/3T3 cells in replicate experiments. By comparison with the bacterial mutagenesis data, cell transformation is a relatively sensitive method for detecting possible mutagenic and carcinogenic activity in this sample. The appropriateness of these systems for the assay of complex mixtures and the degree to which reverse osmosis concentrates contain the unaltered organic compounds in the original samples are discussed.
The paper reports on a study to test the applicability of reverse osmosis in the concentration of drinking water organics. Sequential samples have been prepared from drinking water of cities representative of United States municipal water sources. This paper reports studies on such residues using two in vitro assays, the Salmonella/microsome system, and mammalian cell transformation.
Chlorination of both drinking waters and wastewaters leads to the generation of various chlorinated degradation products of natural fulvic acids. Fulvic acids constitute the bulk of the organic matter in colored surface or ground waters. Meta dihydroxybenzene structures are proposed as main reactive sites of the molecule. Experimental evidence is presented for possible reaction pathways leading to haloforms and other chlorinated by-products.
The recovery efficiencies of XAD resins −2, −4, −7, and −8 and of resin mixtures were measured using distilled water samples containing 13 organic pollutants. An equal-weight mixture of XAD-4 and XAD-8 was most efficient. XAD-2 and XAD-4/8 were further terted and found effective using tapwater. Carbon was tested as a sorbent for materials not well retained by the resins. In-column solvent washing before sample sorption was found to be as effective as Soxhlet extraction for removing background impurities. Some compounds can be desorbed from carbon by in-column solvent elution; others require Soxhlet extraction. An XAD-4/8 column in series with a carbon column was used to sample 1000 1 of tapwater. Halomethanes, n-hydrocarbons, polynuclear aromatic compounds and dibenzofuran in the order of ng/l were identified using a gas chromatograph-mass spectrometer-computer system.
After EPA disclosed its findings of organic chemicals in New Orleans water, it was decided to conduct another, more inclusive study, with specific sites throughout the US designated as test areas. The following details the procedures of the testing and the findings of EPA's research team.
Preliminary results of a study sponsored in part by the AWWA Research Foundation outline an easy, quick, and inexpensive test for screening organic material for carcinogenic potential.
This conference emphasizes the latest research in the field, stresses risks and benefits of water chlorination to public health and the environment, analyzes its use in wastewater treatment, and summarizes the latest government regulations on chlorination of drinking water. (PCS)
Fifty-three unconcentrated samples of Mississippi River water, collected at six different sites over a nine-month period, were examined with histidine-dependent mutant strains of Salmonella typhimurium for the presence of mutagens and potential carcinogens. Twenty-seven samples (51%) induced reversion to histidine independence with one or more of the mutant strains. Fifteen of the 27 samples (56%) first required metabolic activation before reversion was observed. Maximum numbers of samples producing reversion were collected during the late summer and autumn months. A correlation between increased river flow and the reduction in the number of samples producing genetic changes was noted.
Water Chlorination: Environmental Impact and Health Effects
- J C Loper
Water Chlorination, Environmental Impact and Health Effects
- R M Bean