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Procházka E, Melvin SD, Escher BI, Plewa MJ, Leusch FD. Global Transcriptional Analysis of Nontransformed Human Intestinal Epithelial Cells (FHs 74 Int) after Exposure to Selected Drinking Water Disinfection By-Products. ENVIRONMENTAL HEALTH PERSPECTIVES 2019; 127:117006. [PMID: 31755747 PMCID: PMC6927499 DOI: 10.1289/ehp4945] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
BACKGROUND Drinking water disinfection inadvertently leads to the formation of numerous disinfection by-products (DBPs), some of which are cytotoxic, mutagenic, genotoxic, teratogenic, and potential carcinogens both in vitro and in vivo. OBJECTIVES We investigated alterations to global gene expression (GE) in nontransformed human small intestine epithelial cells (FHs 74 Int) after exposure to six brominated and two chlorinated DBPs: bromoacetic acid (BAA), bromoacetonitrile (BAN), 2,6-dibromo-p-benzoquinone (DBBQ), bromoacetamide (BAM), tribromoacetaldehyde (TBAL), bromate (BrO3-), trichloroacetic acid (TCAA), and trichloroacetaldehyde (TCAL). METHODS Using whole-genome cDNA microarray technology (Illumina), we examined GE in nontransformed human cells after 4h exposure to DBPs at predetermined equipotent concentrations, identified significant changes in gene expression (p≤0.01), and investigated the relevance of these genes to specific toxicity pathways via gene and pathway enrichment analysis. RESULTS Genes related to activation of oxidative stress-responsive pathways exhibited fewer alterations than expected based on prior work, whereas all DBPs induced notable effects on transcription of genes related to immunity and inflammation. DISCUSSION Our results suggest that alterations to genes associated with immune and inflammatory pathways play an important role in the potential adverse health effects of exposure to DBPs. The interrelationship between these pathways and the production of reactive oxygen species (ROS) may explain the common occurrence of oxidative stress in other studies exploring DBP toxicity. Finally, transcriptional changes and shared induction of toxicity pathways observed for all DBPs caution of additive effects of mixtures and suggest further assessment of adverse health effects of mixtures is warranted. https://doi.org/10.1289/EHP4945.
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Affiliation(s)
- Erik Procházka
- Australian Rivers Institute, School of Environment and Science, Griffith University, Gold Coast, Queensland, Australia
| | - Steven D. Melvin
- Australian Rivers Institute, School of Environment and Science, Griffith University, Gold Coast, Queensland, Australia
| | - Beate I. Escher
- Australian Rivers Institute, School of Environment and Science, Griffith University, Gold Coast, Queensland, Australia
- Department of Cell Toxicology, Helmholtz Centre for Environmental Research – UFZ, Leipzig, Germany
- Environmental Toxicology, Centre for Applied Geoscience, Eberhard Karls University, Tübingen, Germany
| | - Michael J. Plewa
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Safe Global Water Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Frederic D.L. Leusch
- Australian Rivers Institute, School of Environment and Science, Griffith University, Gold Coast, Queensland, Australia
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Kolb C, Francis RA, VanBriesen JM. Disinfection byproduct regulatory compliance surrogates and bromide-associated risk. J Environ Sci (China) 2017; 58:191-207. [PMID: 28774609 DOI: 10.1016/j.jes.2017.05.043] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 05/15/2017] [Accepted: 05/31/2017] [Indexed: 06/07/2023]
Abstract
Natural and anthropogenic factors can alter bromide concentrations in drinking water sources. Increasing source water bromide concentrations increases the formation and alters the speciation of disinfection byproducts (DBPs) formed during drinking water treatment. Brominated DBPs are more toxic than their chlorinated analogs, and thus have a greater impact on human health. However, DBPs are regulated based on the mass sum of DBPs within a given class (e.g., trihalomethanes and haloacetic acids), not based on species-specific risk or extent of bromine incorporation. The regulated surrogate measures are intended to protect against not only the species they directly represent, but also against unregulated DBPs that are not routinely measured. Surrogates that do not incorporate effects of increasing bromide may not adequately capture human health risk associated with drinking water when source water bromide is elevated. The present study analyzes trihalomethanes (THMs), measured as TTHM, with varying source water bromide concentrations, and assesses its correlation with brominated THM, TTHM risk and species-specific THM concentrations and associated risk. Alternative potential surrogates are evaluated to assess their ability to capture THM risk under different source water bromide concentration conditions. The results of the present study indicate that TTHM does not adequately capture risk of the regulated species when source water bromide concentrations are elevated, and thus would also likely be an inadequate surrogate for many unregulated brominated species. Alternative surrogate measures, including THM3 and the bromodichloromethane concentration, are more robust surrogates for species-specific THM risk at varying source water bromide concentrations.
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Affiliation(s)
- Chelsea Kolb
- Department of Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
| | - Royce A Francis
- Department of Engineering Management and Systems Engineering, The George Washington University, Washington, DC 20052, USA
| | - Jeanne M VanBriesen
- Department of Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, USA; Department of Engineering and Public Policy, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
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3
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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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Pressman JG, McCurry DL, Parvez S, Rice GE, Teuschler LK, Miltner RJ, Speth TF. Disinfection byproduct formation in reverse-osmosis concentrated and lyophilized natural organic matter from a drinking water source. WATER RESEARCH 2012; 46:5343-5354. [PMID: 22846256 DOI: 10.1016/j.watres.2012.07.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Revised: 04/10/2012] [Accepted: 07/11/2012] [Indexed: 06/01/2023]
Abstract
Drinking water treatment and disinfection byproduct (DBP) research can be complicated by natural organic matter (NOM) temporal variability. NOM preservation by lyophilization (freeze-drying) has been long practiced to address this issue; however, its applicability for drinking water research has been limited because the selected NOM sources are atypical of most drinking water sources. The purpose of this research was to demonstrate that reconstituted NOM from a lyophilized reverse-osmosis (RO) concentrate of a typical drinking water source closely represents DBP formation in the original NOM. A preliminary experiment assessed DBP formation kinetics and yields in concentrated NOM, which demonstrated that chlorine decays faster in concentrate, in some cases leading to altered DBP speciation. Potential changes in NOM reactivity caused by lyophilization were evaluated by chlorination of lyophilized and reconstituted NOM, its parent RO concentrate, and the source water. Bromide lost during RO concentration was replaced by adding potassium bromide prior to chlorination. Although total measured DBP formation tended to decrease slightly and unidentified halogenated organic formation tended to increase slightly as a result of RO concentration, the changes associated with lyophilization were minor. In lyophilized NOM reconstituted back to source water TOC levels and then chlorinated, the concentrations of 19 of 21 measured DBPs, constituting 96% of the total identified DBP mass, were statistically indistinguishable from those in the chlorinated source water. Furthermore, the concentrations of 16 of 21 DBPs in lyophilized NOM reconstituted back to the RO concentrate TOC levels, constituting 86% DBP mass, were statistically indistinguishable from those in the RO concentrate. This study suggests that lyophilization can be used to preserve concentrated NOM without substantially altering the precursors to DBP formation.
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Affiliation(s)
- Jonathan G Pressman
- National Risk Management Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Cincinnati, OH 45268, USA.
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Toccalino PL, Norman JE, Scott JC. Chemical mixtures in untreated water from public-supply wells in the U.S.--occurrence, composition, and potential toxicity. THE SCIENCE OF THE TOTAL ENVIRONMENT 2012; 431:262-70. [PMID: 22687436 DOI: 10.1016/j.scitotenv.2012.05.044] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2011] [Revised: 02/23/2012] [Accepted: 05/14/2012] [Indexed: 05/18/2023]
Abstract
Chemical mixtures are prevalent in groundwater used for public water supply, but little is known about their potential health effects. As part of a large-scale ambient groundwater study, we evaluated chemical mixtures across multiple chemical classes, and included more chemical contaminants than in previous studies of mixtures in public-supply wells. We (1) assessed the occurrence of chemical mixtures in untreated source-water samples from public-supply wells, (2) determined the composition of the most frequently occurring mixtures, and (3) characterized the potential toxicity of mixtures using a new screening approach. The U.S. Geological Survey collected one untreated water sample from each of 383 public wells distributed across 35 states, and analyzed the samples for as many as 91 chemical contaminants. Concentrations of mixture components were compared to individual human-health benchmarks; the potential toxicity of mixtures was characterized by addition of benchmark-normalized component concentrations. Most samples (84%) contained mixtures of two or more contaminants, each at concentrations greater than one-tenth of individual benchmarks. The chemical mixtures that most frequently occurred and had the greatest potential toxicity primarily were composed of trace elements (including arsenic, strontium, or uranium), radon, or nitrate. Herbicides, disinfection by-products, and solvents were the most common organic contaminants in mixtures. The sum of benchmark-normalized concentrations was greater than 1 for 58% of samples, suggesting that there could be potential for mixtures toxicity in more than half of the public-well samples. Our findings can be used to help set priorities for groundwater monitoring and suggest future research directions for drinking-water treatment studies and for toxicity assessments of chemical mixtures in water resources.
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Affiliation(s)
- Patricia L Toccalino
- U.S. Geological Survey (USGS), 6000 J Street, Placer Hall, Sacramento, California 95819, USA.
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6
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Narotsky MG, Pressman JG, Miltner RJ, Speth TF, Teuschler LK, Rice GE, Richardson SD, Best DS, McDonald A, Hunter ES, Simmons JE. Developmental Toxicity Evaluations of Whole Mixtures of Disinfection By-products using Concentrated Drinking Water in Rats: Gestational and Lactational Effects of Sulfate and Sodium. ACTA ACUST UNITED AC 2012; 95:202-12. [DOI: 10.1002/bdrb.21004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Accepted: 12/19/2011] [Indexed: 11/11/2022]
Affiliation(s)
- Michael G. Narotsky
- National Health and Environmental Effects Research Laboratory; Office of Research and Development; U.S. Environmental Protection Agency; Research Triangle Park; North Carolina
| | - Jonathan G. Pressman
- National Risk Management Research Laboratory; Office of Research and Development; U.S. Environmental Protection Agency; Cincinnati; Ohio
| | - Richard J. Miltner
- National Risk Management Research Laboratory; Office of Research and Development; U.S. Environmental Protection Agency; Cincinnati; Ohio
| | - Thomas F. Speth
- National Risk Management Research Laboratory; Office of Research and Development; U.S. Environmental Protection Agency; Cincinnati; Ohio
| | - Linda K. Teuschler
- National Center for Environmental Assessment; Office of Research and Development; U.S. Environmental Protection Agency; Cincinnati; Ohio
| | - Glenn E. Rice
- National Center for Environmental Assessment; Office of Research and Development; U.S. Environmental Protection Agency; Cincinnati; Ohio
| | - Susan D. Richardson
- National Exposure Research Laboratory; Office of Research and Development; U.S. Environmental Protection Agency; Athens; Georgia
| | - Deborah S. Best
- National Health and Environmental Effects Research Laboratory; Office of Research and Development; U.S. Environmental Protection Agency; Research Triangle Park; North Carolina
| | - Anthony McDonald
- National Health and Environmental Effects Research Laboratory; Office of Research and Development; U.S. Environmental Protection Agency; Research Triangle Park; North Carolina
| | - E. Sidney Hunter
- National Health and Environmental Effects Research Laboratory; Office of Research and Development; U.S. Environmental Protection Agency; Research Triangle Park; North Carolina
| | - Jane Ellen Simmons
- National Health and Environmental Effects Research Laboratory; Office of Research and Development; U.S. Environmental Protection Agency; Research Triangle Park; North Carolina
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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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Colman J, Rice GE, Wright JM, Hunter ES, Teuschler LK, Lipscomb JC, Hertzberg RC, Simmons JE, Fransen M, Osier M, Narotsky MG. Identification of developmentally toxic drinking water disinfection byproducts and evaluation of data relevant to mode of action. Toxicol Appl Pharmacol 2011; 254:100-26. [DOI: 10.1016/j.taap.2011.02.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2008] [Revised: 04/22/2010] [Accepted: 04/22/2010] [Indexed: 12/26/2022]
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9
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Pressman JG, Richardson SD, Speth TF, Miltner RJ, Narotsky MG, Hunter ES, Rice GE, Teuschler LK, McDonald A, Parvez S, Krasner SW, Weinberg HS, McKague AB, Parrett CJ, Bodin N, Chinn R, Lee CFT, Simmons JE. Concentration, chlorination, and chemical analysis of drinking water for disinfection byproduct mixtures health effects research: U.S. EPA's Four Lab Study. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2010; 44:7184-92. [PMID: 20496936 DOI: 10.1021/es9039314] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
The U.S. Environmental Protection Agency's "Four Lab Study" involved participation of researchers from four national Laboratories and Centers of the Office of Research and Development along with collaborators from the water industry and academia. The study evaluated toxicological effects of complex disinfection byproduct (DBP) mixtures, with an emphasis on reproductive and developmental effects that have been associated with DBP exposures in some human epidemiologic studies. This paper describes a new procedure for producing chlorinated drinking water concentrate for animal toxicology experiments, comprehensive identification of >100 DBPs, and quantification of 75 priority and regulated DBPs. In the research reported herein, complex mixtures of DBPs were produced by concentrating a natural source water with reverse osmosis membranes, followed by addition of bromide and treatment with chlorine. By concentrating natural organic matter in the source water first and disinfecting with chlorine afterward, DBPs (including volatiles and semivolatiles) were formed and maintained in a water matrix suitable for animal studies. DBP levels in the chlorinated concentrate compared well to those from EPA's Information Collection Rule (ICR) and a nationwide study of priority unregulated DBPs when normalized by total organic carbon (TOC). DBPs were relatively stable over the course of the animal studies (125 days) with multiple chlorination events (every 5-14 days), and a significant portion of total organic halogen was accounted for through a comprehensive identification approach. DBPs quantified included regulated DBPs, priority unregulated DBPs, and additional DBPs targeted by the ICR. Many DBPs are reported for the first time, including previously undetected and unreported haloacids and haloamides. The new concentration procedure not only produced a concentrated drinking water suitable for animal experiments, but also provided a greater TOC concentration factor (136×), enhancing the detection of trace DBPs that are often below detection using conventional approaches.
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Affiliation(s)
- Jonathan G Pressman
- National Risk Management Research Laboratory, US EPA, Cincinnati, Ohio 45268, USA
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Lou JC, Huang CE, Han JY, Huang YJ. Generation of disinfection by-products (DBPs) at two advanced water treatment plants. ENVIRONMENTAL MONITORING AND ASSESSMENT 2010; 162:365-375. [PMID: 19238566 DOI: 10.1007/s10661-009-0802-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2008] [Accepted: 01/27/2009] [Indexed: 05/27/2023]
Abstract
A sampling program was conducted to investigate the formation of disinfection by-products (DBPs) and dissolved organic carbon (DOC) at two advanced water treatment plants in Kaohsiung City, Taiwan. The results in this study can be used as a reference for the operational control of water treatment plants and the setting of regulations in Taiwan. Samples of drinking water were collected from two advanced water treatment plants from June 2007 to April 2008. Changes in the concentration of dissolved organic carbon, the trihalomethane formation potential, and the haloacetic acids formation potential were measured in raw water samples. Variations in the concentrations of trihalomethanes (THMs) and haloacetic acids (HAA(5)) in finished drinking water were evaluated. The major species of HAA(5) were in the order of dichloroacetic acid and trichloroacetic acid and the THM was of trichloromethane. DOC was strongly related to DBPs in raw water. In this investigation, the removal efficiency of DBPs in Plant A (ultrafiltration/reverse osmosis system) exceeded that in Plant B (ozonation/biological activated carbon system). Both advanced water treatment plants greatly improved the quality of drinking water.
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Affiliation(s)
- Jie-Chung Lou
- Institute of Environmental Engineering, National Sun Yat-Sen University, Kaohsiung City, Taiwan.
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Francis RA, Vanbriesen JM, Small MJ. Bayesian statistical modeling of disinfection byproduct (DBP) bromine incorporation in the ICR database. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2010; 44:1232-1239. [PMID: 20095529 DOI: 10.1021/es9028606] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Statistical models are developed for bromine incorporation in the trihalomethane (THM), trihaloacetic acids (THAA), dihaloacetic acid (DHAA), and dihaloacetonitrile (DHAN) subclasses of disinfection byproducts (DBPs) using distribution system samples from plants applying only free chlorine as a primary or residual disinfectant in the Information Collection Rule (ICR) database. The objective of this study is to characterize the effect of water quality conditions before, during, and post-treatment on distribution system bromine incorporation into DBP mixtures. Bayesian Markov Chain Monte Carlo (MCMC) methods are used to model individual DBP concentrations and estimate the coefficients of the linear models used to predict the bromine incorporation fraction for distribution system DBP mixtures in each of the four priority DBP classes. The bromine incorporation models achieve good agreement with the data. The most important predictors of bromine incorporation fraction across DBP classes are alkalinity, specific UV absorption (SUVA), and the bromide to total organic carbon ratio (Br:TOC) at the first point of chlorine addition. Free chlorine residual in the distribution system, distribution system residence time, distribution system pH, turbidity, and temperature only slightly influence bromine incorporation. The bromide to applied chlorine (Br:Cl) ratio is not a significant predictor of the bromine incorporation fraction (BIF) in any of the four classes studied. These results indicate that removal of natural organic matter and the location of chlorine addition are important treatment decisions that have substantial implications for bromine incorporation into disinfection byproduct in drinking waters.
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Affiliation(s)
- Royce A Francis
- Department of Geography and Environmental Engineering, Johns Hopkins University, Baltimore, Maryland 21218, 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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Rice G, Teuschler LK, Speth TF, Richardson SD, Miltner RJ, Schenck KM, Gennings C, Hunter ES, Narotsky MG, Simmons JE. Integrated disinfection by-products research: assessing reproductive and developmental risks posed by complex disinfection by-product mixtures. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2008; 71:1222-1234. [PMID: 18636394 DOI: 10.1080/15287390802182649] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
This article presents a toxicologically-based risk assessment strategy for identifying the individual components or fractions of a complex mixture that are associated with its toxicity. The strategy relies on conventional component-based mixtures risk approaches such as dose addition, response addition, and analyses of interactions. Developmental toxicity data from two drinking-water concentrates containing disinfection by-products (DBP) mixtures were used to illustrate the strategy. The results of this study showed that future studies of DBP concentrates using the Chernoff-Kavlock bioassay need to consider evaluating DBP that are concentrated more than 130-fold and using a rat strain that is more sensitive to chemically-induced pregnancy loss than Sprague-Dawley rats. The results support the planned experimental design of a multigeneration reproductive and developmental study of DBP concentrates. Finally, this article discusses the need for a systematic evaluation of DBP concentrates obtained from multiple source waters and treatment types. The development of such a database could be useful in evaluating whether a specific DBP concentrate is sufficiently similar to tested combinations of source waters and treatment alternatives so that health risks for the former may be estimated using data on the latter.
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Affiliation(s)
- Glenn Rice
- U.S. Environmental Protection Agency, Cincinnati, Ohio 45268, USA.
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Simmons JE, Teuschler LK, Gennings C, Speth TF, Richardson SD, Miltner RJ, Narotsky MG, Schenck KD, Hunter ES, Hertzberg RC, Rice G. Component-based and whole-mixture techniques for addressing the toxicity of drinking-water disinfection by-product mixtures. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2004; 67:741-754. [PMID: 15192866 DOI: 10.1080/15287390490428215] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Chemical disinfection of water is of direct public health benefit as it results in decreased water-borne illness. The chemicals used to disinfect water react with naturally occurring organic matter, bromide, and iodide in the source water, resulting in the formation of disinfection by-products (DBPs). Despite the identification of several hundred DBPs, more than 50% of the mass of total organic halide formed during chlorination remains unidentified. The toxic contribution of the DBPs that are formed and present but not yet chemically identified, the unidentified fraction, has been largely unexplored. A better understanding of the potential for adverse human health consequences associated with exposure to the DBPs present in drinking water will be gained by integration of knowledge on the toxicity of individual DBPs; simple, defined DBP mixtures; complex, environmentally realistic DBP mixtures with partial chemical characterization; and the unidentified fraction.
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Affiliation(s)
- Jane Ellen Simmons
- National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711, USA.
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