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Pandian AMK, Rajamehala M, Singh MVP, Sarojini G, Rajamohan N. Potential risks and approaches to reduce the toxicity of disinfection by-product - A review. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 822:153323. [PMID: 35066044 DOI: 10.1016/j.scitotenv.2022.153323] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 01/08/2022] [Accepted: 01/18/2022] [Indexed: 06/14/2023]
Abstract
Water contamination through anthropogenic and industrial activities has led to the emergence and necessity of disinfection methods. Chlorine and bromine gases, often used to disinfect water, resulted in the by-product formation by reacting with organic matter. The Disinfectant by-products (DBP) led to the formation of Trihaloaceticacid (TAA), Trihalomethane (THM), and other minor components. The release of chemicals has also led to the outbreak of diseases like infertility, asthma, stillbirth, and types of cancer. There are new approaches that are found to be useful to compensate for the generation of toxic by-products and involve membrane technologies, namely reverse osmosis, ultrafiltration, and nanofiltration. This review mainly focuses on the toxicology effects of DBPs and various approaches to mitigate the same. The health hazards caused by different DBPs and the various treatment techniques available for the removal are discussed. In addition, a critical comparison of the different removal techniques was discussed.
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Affiliation(s)
- A Muthu Kumara Pandian
- Department of Biotechnology, Vivekanandha College of Engineering for Women (Autonomous), Tiruchengode, Namakkal 637205, India.
| | - M Rajamehala
- Department of Biotechnology, Vivekanandha College of Engineering for Women (Autonomous), Tiruchengode, Namakkal 637205, India
| | - M Vijay Pradhap Singh
- Department of Biotechnology, Vivekanandha College of Engineering for Women (Autonomous), Tiruchengode, Namakkal 637205, India
| | - G Sarojini
- Department of Petrochemical Engineering, SVS College of Engineering, Coimbatore, India
| | - N Rajamohan
- Chemical Engineering Section, Sohar University, Sohar, Oman
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Wang W, Qian Y, Li J, Aljuhani N, Siraki AG, Le XC, Li XF. Characterization of Mechanisms of Glutathione Conjugation with Halobenzoquinones in Solution and HepG2 Cells. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:2898-2908. [PMID: 29420883 DOI: 10.1021/acs.est.7b05945] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Halobenzoquinones (HBQs) are a class of emerging disinfection byproducts. Chronic exposure to chlorinated drinking water is potentially associated with an increased risk of human bladder cancer. HBQ-induced cytotoxicity involves depletion of cellular glutathione (GSH), but the underlying mechanism remains unclear. Here we used ultrahigh performance liquid chromatography-high resolution mass spectrometry and electron paramagnetic resonance spectroscopy to study interactions between HBQs and GSH and found that HBQs can directly react with GSH, forming various glutathionyl conjugates (HBQ-SG) in both aqueous solution and HepG2 cells. We found that the formation of HBQ-SG varies with the initial molar ratio of GSH to HBQ in reaction mixtures. Higher molar ratios of GSH to HBQ facilitate the conjugation of more GSH molecules to an HBQ molecule. We deduced the reaction mechanism between GSH and HBQs, which involves redox cycling-induced formation of halosemiquinone (HSQ) free radicals and glutathione disulfide, Michael addition, as well as nucleophilic substitution. The proposed reaction rates are in the following order: formation of HSQ radicals > substitution of bromine by GSH > Michael addition of GSH on the benzoquinone ring > substitution of chlorine by GSH > substitution of the methyl group by GSH. The conjugates identified in HBQ-treated HepG2 cells were the same as those found in aqueous solution containing a 5:1 ratio of GSH:HBQs.
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Affiliation(s)
- Wei Wang
- Department of Environmental Science , Zhejiang University , Hangzhou , Zhejiang 310058 , China
- Division of Analytical and Environmental Toxicology, Department of Laboratory Medicine and Pathology, Faculty of Medicine and Dentistry , University of Alberta , Edmonton , Alberta T6G 2G3 , Canada
| | - Yichao Qian
- Division of Analytical and Environmental Toxicology, Department of Laboratory Medicine and Pathology, Faculty of Medicine and Dentistry , University of Alberta , Edmonton , Alberta T6G 2G3 , Canada
| | - Jinhua Li
- Division of Analytical and Environmental Toxicology, Department of Laboratory Medicine and Pathology, Faculty of Medicine and Dentistry , University of Alberta , Edmonton , Alberta T6G 2G3 , Canada
| | - Naif Aljuhani
- Faculty of Pharmacy and Pharmaceutical Sciences , University of Alberta , Edmonton , Alberta T6G 2H7 , Canada
| | - Arno G Siraki
- Faculty of Pharmacy and Pharmaceutical Sciences , University of Alberta , Edmonton , Alberta T6G 2H7 , Canada
| | - X Chris Le
- Division of Analytical and Environmental Toxicology, Department of Laboratory Medicine and Pathology, Faculty of Medicine and Dentistry , University of Alberta , Edmonton , Alberta T6G 2G3 , Canada
- Department of Chemistry, Faculty of Science , University of Alberta , Edmonton , Alberta T6G 2G2 , Canada
| | - Xing-Fang Li
- Division of Analytical and Environmental Toxicology, Department of Laboratory Medicine and Pathology, Faculty of Medicine and Dentistry , University of Alberta , Edmonton , Alberta T6G 2G3 , Canada
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Du Y, Lv XT, Wu QY, Zhang DY, Zhou YT, Peng L, Hu HY. Formation and control of disinfection byproducts and toxicity during reclaimed water chlorination: A review. J Environ Sci (China) 2017; 58:51-63. [PMID: 28774626 DOI: 10.1016/j.jes.2017.01.013] [Citation(s) in RCA: 109] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Revised: 01/26/2017] [Accepted: 01/30/2017] [Indexed: 06/07/2023]
Abstract
Chlorination is essential to the safety of reclaimed water; however, this process leads to concern regarding the formation of disinfection byproducts (DBPs) and toxicity. This study reviewed the formation and control strategies for DBPs and toxicity in reclaimed water during chlorination. Both regulated and emerging DBPs have been frequently detected in reclaimed water during chlorination at a higher level than those in drinking water, indicating they pose a greater risk to humans. Luminescent bacteria and Daphnia magna acute toxicity, anti-estrogenic activity and cytotoxicity generally increased after chlorination because of the formation of DBPs. Genotoxicity by umu-test and estrogenic activity were decreased after chlorination because of destruction of toxic chemicals. During chlorination, water quality significantly impacted changes in toxicity. Ammonium tended to attenuate toxicity changes by reacting with chlorine to form chloramine, while bromide tended to aggravate toxicity changes by forming hypobromous acid. During pretreatment by ozonation and coagulation, disinfection byproduct formation potential (DBPFP) and toxicity formation potential (TFP) occasionally increase, which is accompanied by DOC removal; thus, the decrease of DOC was limited to indicate the decrease of DBPFP and TFP. It is more important to eliminate the key fraction of precursors such as hydrophobic acid and hydrophilic neutrals. During chlorination, toxicities can increase with the increasing chlorine dose and contact time. To control the excessive toxicity formation, a relatively low chlorine dose and short contact time were required. Quenching chlorine residual with reductive reagents also effectively abated the formation of toxic compounds.
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Affiliation(s)
- Ye Du
- Environmental Simulation and Pollution Control State Key Joint Laboratory, State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), School of Environment, Tsinghua University, Beijing 100084, China; Key Laboratory of Microorganism Application and Risk Control of Shenzhen, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China
| | - Xiao-Tong Lv
- Environmental Simulation and Pollution Control State Key Joint Laboratory, State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), School of Environment, Tsinghua University, Beijing 100084, China; Key Laboratory of Microorganism Application and Risk Control of Shenzhen, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China
| | - Qian-Yuan Wu
- Key Laboratory of Microorganism Application and Risk Control of Shenzhen, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China.
| | - Da-Yin Zhang
- Environmental Simulation and Pollution Control State Key Joint Laboratory, State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), School of Environment, Tsinghua University, Beijing 100084, China; Key Laboratory of Microorganism Application and Risk Control of Shenzhen, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China
| | - Yu-Ting Zhou
- Environmental Simulation and Pollution Control State Key Joint Laboratory, State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), School of Environment, Tsinghua University, Beijing 100084, China; Key Laboratory of Microorganism Application and Risk Control of Shenzhen, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China
| | - Lu Peng
- Environmental Simulation and Pollution Control State Key Joint Laboratory, State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), School of Environment, Tsinghua University, Beijing 100084, China; Key Laboratory of Microorganism Application and Risk Control of Shenzhen, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, China
| | - Hong-Ying Hu
- Environmental Simulation and Pollution Control State Key Joint Laboratory, State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), School of Environment, Tsinghua University, Beijing 100084, China; Shenzhen Environmental Science and New Energy Technology Engineering Laboratory, Tsinghua-Berkeley Shenzhen Institute, Shenzhen 518055, China.
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Parvez S, Rice GE, Teuschler LK, Simmons JE, Speth TF, Richardson SD, Miltner RJ, Hunter ES, Pressman JG, Strader LF, Klinefelter GR, Goldman JM, Narotsky MG. Method to assess component contribution to toxicity of complex mixtures: Assessment of puberty acquisition in rats exposed to disinfection byproducts. J Environ Sci (China) 2017; 58:311-321. [PMID: 28774622 PMCID: PMC8343928 DOI: 10.1016/j.jes.2017.05.042] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 05/19/2017] [Accepted: 05/31/2017] [Indexed: 05/04/2023]
Abstract
A method based on regression modeling was developed to discern the contribution of component chemicals to the toxicity of highly complex, environmentally realistic mixtures of disinfection byproducts (DBPs). Chemical disinfection of drinking water forms DBP mixtures. Because of concerns about possible reproductive and developmental toxicity, a whole mixture (WM) of DBPs produced by chlorination of a water concentrate was administered as drinking water to Sprague-Dawley (S-D) rats in a multigenerational study. Age of puberty acquisition, i.e., preputial separation (PPS) and vaginal opening (VO), was examined in male and female offspring, respectively. When compared to controls, a slight, but statistically significant delay in puberty acquisition was observed in females but not in males. WM-induced differences in the age at puberty acquisition were compared to those reported in S-D rats administered either a defined mixture (DM) of nine regulated DBPs or individual DBPs. Regression models were developed using individual animal data on age at PPS or VO from the DM study. Puberty acquisition data reported in the WM and individual DBP studies were then compared with the DM models. The delay in puberty acquisition observed in the WM-treated female rats could not be distinguished from delays predicted by the DM regression model, suggesting that the nine regulated DBPs in the DM might account for much of the delay observed in the WM. This method is applicable to mixtures of other types of chemicals and other endpoints.
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Affiliation(s)
- Shahid Parvez
- Indiana University Richard M. Fairbanks School of Public Health, Department of Environmental Health Sciences, IUPUI Campus, Indianapolis, IN 46202, USA
| | - Glenn E Rice
- National Center for Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, Cincinnati, OH 45268, USA.
| | | | - Jane Ellen Simmons
- National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, USA
| | - Thomas F Speth
- National Risk Management Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Cincinnati, OH 45268, USA
| | - Susan D Richardson
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208, USA
| | - Richard J Miltner
- National Risk Management Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Cincinnati, OH 45268, USA
| | - E Sidney Hunter
- National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, USA
| | - Jonathan G Pressman
- National Risk Management Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Cincinnati, OH 45268, USA
| | - Lillian F Strader
- National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, USA
| | - Gary R Klinefelter
- National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, USA
| | - Jerome M Goldman
- National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, USA
| | - Michael G Narotsky
- National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, USA
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Benson R, Conerly OD, Sander W, Batt AL, Boone JS, Furlong ET, Glassmeyer ST, Kolpin DW, Mash HE, Schenck KM, Simmons JE. Human health screening and public health significance of contaminants of emerging concern detected in public water supplies. THE SCIENCE OF THE TOTAL ENVIRONMENT 2017; 579:1643-1648. [PMID: 28040195 PMCID: PMC6277017 DOI: 10.1016/j.scitotenv.2016.03.146] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Revised: 03/09/2016] [Accepted: 03/20/2016] [Indexed: 05/20/2023]
Abstract
The source water and treated drinking water from twenty five drinking water treatment plants (DWTPs) across the United States were sampled in 2010-2012. Samples were analyzed for 247 contaminants using 15 chemical and microbiological methods. Most of these contaminants are not regulated currently either in drinking water or in discharges to ambient water by the U. S. Environmental Protection Agency (USEPA) or other U.S. regulatory agencies. This analysis shows that there is little public health concern for most of the contaminants detected in treated water from the 25 DWTPs participating in this study. For vanadium, the calculated Margin of Exposure (MOE) was less than the screening MOE in two DWTPs. For silicon, the calculated MOE was less than the screening MOE in one DWTP. Additional study, for example a national survey may be needed to determine the number of people ingesting vanadium and silicon above a level of concern. In addition, the concentrations of lithium found in treated water from several DWTPs are within the range previous research has suggested to have a human health effect. Additional investigation of this issue is necessary. Finally, new toxicological data suggest that exposure to manganese at levels in public water supplies may present a public health concern which will require a robust assessment of this information.
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Affiliation(s)
- Robert Benson
- USEPA Region 8, 1595 Wynkoop, Denver, CO 80202, United States.
| | - Octavia D Conerly
- USEPA, Office of Water, Office of Science and Technology, William Jefferson Clinton Building, 1200 Pennsylvania Ave, NW, Washington, DC 20460, United States.
| | - William Sander
- American Association for the Advancement of Science (AAAS) and Technology Policy Fellow hosted, USEPA, Office of Water, Office of Science and Technology, William Jefferson Clinton Building, 1200 Pennsylvania Ave, NW, Washington, DC 20460, United States.
| | - Angela L Batt
- USEPA, Office of Research and Development, National Exposure Research Laboratory, 26 W Martin Luther King Dr., Cincinnati, OH 45268, United States.
| | - J Scott Boone
- USEPA, Office of Chemical Safety and Pollution Prevention, Stennis Space Port, MS, United States.
| | - Edward T Furlong
- USGS, National Water Quality Laboratory, PO Box 25585, Building 95, Denver Federal Center, Denver, CO 80225, United States.
| | - Susan T Glassmeyer
- USEPA, Office of Research and Development, National Exposure Research Laboratory, 26 W Martin Luther King Dr., Cincinnati, OH 45268, United States.
| | - Dana W Kolpin
- USGS, Iowa Water Science Center, PO Box 1230, Iowa City, IA 52244, United States.
| | - Heath E Mash
- USEPA, Office of Research and Development, National Risk Management Research Laboratory, 26 W Martin Luther King Dr., Cincinnati, OH 45268, United States.
| | - Kathleen M Schenck
- USEPA, Office of Research and Development, National Risk Management Research Laboratory, 26 W Martin Luther King Dr., Cincinnati, OH 45268, United States.
| | - Jane Ellen Simmons
- USEPA, Office of Research and Development, National Health and Environmental Effects Research Division, 109 T.W. Alexander Dr., Research Triangle Park, NC 27709, United States.
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Ceko MJ, Hummitzsch K, Hatzirodos N, Bonner W, James SA, Kirby JK, Rodgers RJ, Harris HH. Distribution and speciation of bromine in mammalian tissue and fluids by X-ray fluorescence imaging and X-ray absorption spectroscopy. Metallomics 2015; 7:756-65. [PMID: 25675086 DOI: 10.1039/c4mt00338a] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Bromine is one of the most abundant and ubiquitous trace elements in the biosphere and until recently had not been shown to perform any essential biological function in animals. A recent study demonstrated that bromine is required as a cofactor for peroxidasin-catalysed formation of sulfilimine crosslinks in Drosophila. In addition, bromine dietary deficiency is lethal in Drosophila, whereas bromine replenishment restores viability. The aim of this study was to examine the distribution and speciation of bromine in mammalian tissues and fluids to provide further insights into the role and function of this element in biological systems. In this study we used X-ray fluorescence (XRF) imaging and inductively coupled plasma-mass spectrometry (ICP-MS) to examine the distribution of bromine in bovine ovarian tissue samples, follicular fluid and aortic serum, as well as human whole blood and serum and X-ray absorption spectroscopy (XAS) to identify the chemical species of bromine in a range of mammalian tissue (bovine, ovine, porcine and murine), whole blood and serum samples (bovine, ovine, porcine, murine and human), and marine samples (salmon (Salmo salar), kingfish (Seriola lalandi) and Scleractinian coral). Bromine was found to be widely distributed across all tissues and fluids examined. In the bovine ovary in particular it was more concentrated in the sub-endothelial regions of arterioles. Statistical comparison of the near-edge region of the X-ray absorption spectra with a library of bromine standards led to the conclusion that the major form of bromine in all samples analysed was bromide.
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Affiliation(s)
- Melanie J Ceko
- Department of Chemistry, The University of Adelaide, SA 5005, Australia.
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Zheng W, Wang X, Tian D, Zhang H, Tian W, Andersen ME, Zheng Y, Sun X, Jiang S, Cao Z, He G, Qu W. Pollution trees: identifying similarities among complex pollutant mixtures in water and correlating them to mutagenicity. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2012; 46:7274-7282. [PMID: 22680987 DOI: 10.1021/es300728q] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
There are relatively few tools available for computing and visualizing similarities among complex mixtures and in correlating the chemical composition clusters with toxicological clusters of mixtures. Using the "intersection and union ratio (IUR)" and other traditional distance matrices on contaminant profiles of 33 specific water samples, we used "pollution trees" to compare these mixtures. The "pollution trees" constructed by neighbor-joining (NJ), maximum parsimony (MP), and maximum likelihood (ML) methods allowed comparison of similarities among these samples. The mutagenicity of each sample was then mapped to the "pollution tree". The IUR-distance-based measure proved effective in comparing chemical composition and compound level differences between mixtures. We found a robust "pollution tree" containing seven major lineages with certain broad characteristics: treated municipal water samples were different from raw water samples and untreated rural drinking water samples were similar with local water sources. The IUR-distance-based tree was more highly correlated to mutagenicity than were other distance matrices, i.e., MP/ML methods, sampling group, region, or water type. IUR-distance-based "pollution trees" may become important tools for identifying similarities among real mixtures and examining chemical composition clusters in a toxicological context.
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Affiliation(s)
- Weiwei Zheng
- Key Laboratory of Public Health Safety, Ministry of Education, Department of Environmental Health, School of Public Health, Fudan University, Shanghai 200032, China
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Mallela MK, Werre SR, Hrubec TC. Neural tube defects in mice exposed to tap water. ENVIRONMENTAL TOXICOLOGY 2011; 26:633-640. [PMID: 20549630 PMCID: PMC3042037 DOI: 10.1002/tox.20600] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2009] [Accepted: 02/20/2010] [Indexed: 05/29/2023]
Abstract
In May of 2006 we suddenly began to observe neural tube defects (NTDs) in embryos of untreated control mice. We hypothesized the mice were being exposed unknowingly to a teratogenic agent and investigated the cause. Our results suggested that NTDs were not resulting from bedding material, feed, strain, or source of the mice. Additionally, mice were negative for routine and comprehensive screens of pathogens. To further test whether the NTDs resulted from infectious or genetic cause localized to our facility, we obtained three strains of timed pregnant mice from commercial suppliers located in four different states. All strains and sources of mice arrived in our laboratory with NTDs, implying that commercially available mice were possibly exposed to a teratogen prior to purchase. Our investigation eventually concluded that exposure to tap water was causing the NTDs. The incidence of NTDs was greatest in purchased mice provided tap water and lowest in purchased mice provided distilled deionized water (DDI). Providing mice DDI water for two generations (F2-DDI) eliminated the NTDs. When F2-DDI mice were provided tap water from three different urban areas prior to breeding, their offspring again developed NTDs. Increased length of exposure to tap water significantly increased the incidence of NTDs. These results indicate that a contaminant in municipal tap water is likely causing NTDs in mice. The unknown teratogen appears to have a wide geographic distribution but has not yet been identified. Water analysis is currently underway to identify candidate contaminants that might be responsible for the malformations.
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Affiliation(s)
- Murali K Mallela
- Department of Biomedical Sciences and Pathobiology, VA-MD Regional College of Veterinary Medicine, Virginia Tech, Blacksburg, VA 24061
| | - Stephen R Werre
- Laboratory for Study Design and Statistical Service, VA-MD Regional College of Veterinary Medicine, Virginia Tech, Blacksburg, VA 24061
| | - Terry C Hrubec
- Department of Biomedical Sciences and Pathobiology, VA-MD Regional College of Veterinary Medicine, Virginia Tech, Blacksburg, VA 24061
- Department of Biomedical Sciences, E. Via Virginia College of Osteopathic Medicine, Blacksburg, VA 24060
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Prospective power calculations for the Four Lab study of a multigenerational reproductive/developmental toxicity rodent bioassay using a complex mixture of disinfection by-products in the low-response region. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2011; 8:4082-101. [PMID: 22073030 PMCID: PMC3210599 DOI: 10.3390/ijerph8104082] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/25/2011] [Revised: 09/21/2011] [Accepted: 09/30/2011] [Indexed: 11/17/2022]
Abstract
In complex mixture toxicology, there is growing emphasis on testing environmentally representative doses that improve the relevance of results for health risk assessment, but are typically much lower than those used in traditional toxicology studies. Traditional experimental designs with typical sample sizes may have insufficient statistical power to detect effects caused by environmentally relevant doses. Proper study design, with adequate statistical power, is critical to ensuring that experimental results are useful for environmental health risk assessment. Studies with environmentally realistic complex mixtures have practical constraints on sample concentration factor and sample volume as well as the number of animals that can be accommodated. This article describes methodology for calculation of statistical power for non-independent observations for a multigenerational rodent reproductive/developmental bioassay. The use of the methodology is illustrated using the U.S. EPA's Four Lab study in which rodents were exposed to chlorinated water concentrates containing complex mixtures of drinking water disinfection by-products. Possible experimental designs included two single-block designs and a two-block design. Considering the possible study designs and constraints, a design of two blocks of 100 females with a 40:60 ratio of control:treated animals and a significance level of 0.05 yielded maximum prospective power (~90%) to detect pup weight decreases, while providing the most power to detect increased prenatal loss.
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Plewa MJ, Wagner ED, Mitch WA. Comparative Mammalian cell cytotoxicity of water concentrates from disinfected recreational pools. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2011; 45:4159-4165. [PMID: 21466188 DOI: 10.1021/es104284h] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Disinfection of recreational pools is essential to prevent outbreaks of infectious disease. Despite the health benefits of swimming, recent research demonstrated an association between the application of disinfectants to recreational pools and adverse health outcomes. Pool waters are extreme cases of disinfection that differ in important respects from disinfected drinking waters. Pool waters are continuously exposed to disinfectants over average residence times extending to months. Disinfection byproduct (DBP) precursors in pools include natural humic substances deriving from the tap water source plus inputs from bathers through urine, sweat, hair, skin, and consumer products including sunscreens and cosmetics. This study presents a systematic, chronic in vitro mammalian cell cytotoxicity analysis of different recreational waters with varied environmental conditions that were derived from a common tap water source. Recreational waters were significantly more toxic than their tap water source. Because trihalomethane concentrations are similar between tap waters and pool waters, using trihalomethanes to monitor exposure in epidemiological studies may not be the best metric. Of primary importance for cytotoxicity were illumination conditions. Pools subjected to a combination of ultraviolet light and free chlorine disinfection indoors, or outdoor sunlight exposure exhibited lower cytotoxicity than their indoor counterparts disinfected with free chlorine. Temperature and total organic carbon content, as an indirect measure of DBP precursors, were less important. Previous research on the same samples demonstrated the genotoxicity of an indoor pool disinfected with bromochlorodimethylhydantoin; the cytotoxicity of this sample was confirmed in the present study. While the association of reduced toxicity with illumination indicates that the agents responsible are photolabile, their identity is unclear. As a broad measure of adverse biological responses, cytotoxicity may be a useful metric to gauge the health impacts of alterations in pool operating conditions.
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Affiliation(s)
- Michael J Plewa
- Department of Crop Sciences and the Center of Advanced Materials for the Purification of Water with Systems, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
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Rice GE, Teuschler LK, Bull RJ, Simmons JE, Feder PI. Evaluating the similarity of complex drinking-water disinfection by-product mixtures: overview of the issues. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2009; 72:429-436. [PMID: 19267305 DOI: 10.1080/15287390802608890] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Humans are exposed daily to complex mixtures of environmental chemical contaminants, which arise as releases from sources such as engineering procedures, degradation processes, and emissions from mobile or stationary sources. When dose-response data are available for the actual environmental mixture to which individuals are exposed (i.e., the mixture of concern), these data provide the best information for dose-response assessment of the mixture. When suitable data on the mixture itself are not available, surrogate data might be used from a sufficiently similar mixture or a group of similar mixtures. Consequently, the determination of whether the mixture of concern is "sufficiently similar" to a tested mixture or a group of tested mixtures is central to the use of whole mixture methods. This article provides an overview for a series of companion articles whose purpose is to develop a set of biostatistical, chemical, and toxicological criteria and approaches for evaluating the similarity of drinking-water disinfection by-product (DBPs) complex mixtures. Together, the five articles in this series serve as a case study whose techniques will be relevant to assessing similarity for other classes of complex mixtures of environmental chemicals. Schenck et al. (2009) describe the chemistry and mutagenicity of a set of DBP mixtures concentrated from five different drinking-water treatment plants. Bull et al. (2009a, 2009b) describe how the variables that impact the formation of DBP affect the chemical composition and, subsequently, the expected toxicity of the mixture. Feder et al. (2009a, 2009b) evaluate the similarity of DBP mixture concentrates by applying two biostatistical approaches, principal components analysis, and a nonparametric "bootstrap" analysis. Important factors for determining sufficient similarity of DBP mixtures found in this research include disinfectant used; source water characteristics, including the concentrations of bromide and total organic carbon; concentrations and proportions of individual DBPs with known toxicity data on the same endpoint; magnitude of the unidentified fraction of total organic halides; similar toxicity outcomes for whole mixture testing (e.g., mutagenicity); and summary chemical measures such as total trihalomethanes, total haloacetic acids, total haloacetonitriles, and the levels of bromide incorporation in the DBP classes.
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Affiliation(s)
- Glenn E Rice
- U.S. Environmental Protection Agency, Cincinnati, Ohio 45268, USA.
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