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Luben TJ, Shaffer RM, Kenyon E, Nembhard WN, Weber KA, Nuckols J, Wright JM. Comparison of Trihalomethane exposure assessment metrics in epidemiologic analyses of reproductive and developmental outcomes. JOURNAL OF EXPOSURE SCIENCE & ENVIRONMENTAL EPIDEMIOLOGY 2024; 34:115-125. [PMID: 37316533 DOI: 10.1038/s41370-023-00559-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 05/12/2023] [Accepted: 05/31/2023] [Indexed: 06/16/2023]
Abstract
BACKGROUND Researchers have developed exposure assessment metrics for disinfection by-products (DBPs) utilizing drinking water monitoring data and accounting for spatial and temporal variability, water consumption, and showering and bathing time with an expectation of decreasing exposure misclassification compared to the use of measured concentrations at public water supply (PWS) monitoring locations alone. OBJECTIVE We used exposure data collected for a previous study of DBPs to evaluate how different sources of information impact trihalomethane (THM) exposure estimates. METHODS We compared gestational exposure estimates to THMs based on water utility monitoring data alone, statistical imputation of daily concentrations to incorporate temporal variability, and personal water consumption and use (bathing and showering). We used Spearman correlation coefficients and ranked kappa statistics to compare exposure classifications. RESULTS Exposure estimates based on measured or imputed daily THM concentrations, self-reported consumption, or bathing and showering differed substantially from estimates based solely on concentrations from PWS quarterly monitoring reports. Ranked exposure classifications, high to low quartiles or deciles, were generally consistent across each exposure metric (i.e., a subject with "high" exposure based on measured or imputed THM concentrations generally remained in the "high" category across exposure metrics.) The measured concentrations and imputed daily (i.e., spline regression) concentrations were highly correlated (r = 0.98). The weighted kappa statistics comparing exposure estimates using different exposure metrics ranged from 0.27 to 0.89, with the highest values for the ingestion + bathing/showering metrics compared to metrics for bathing/showering only (0.76 and 0.89). Bathing and showering contributed the most to "total" THM exposure estimates. IMPACT STATEMENT We compare exposure metrics capturing temporal variability and multiple estimates of personal THM exposure with THM concentrations from PWS monitoring data. Our results show exposure estimates based on imputed daily concentrations accounting for temporal variability were very similar to the measured THM concentrations. We observed low agreement between imputed daily concentrations and ingestion-based estimates. Considering additional routes of exposure (e.g., inhalation and dermal) slightly increased agreement with the measured PWS exposure estimate in this population. Overall, the comparison of exposure assessment metrics allows researchers to understand the added value of additional data collection for future epidemiologic analyses of DBPs.
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Affiliation(s)
- Thomas J Luben
- Center for Public Health and Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency. RTP, NC, Washington, DC, Cincinnati, OH, USA.
| | - Rachel M Shaffer
- Center for Public Health and Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency. RTP, NC, Washington, DC, Cincinnati, OH, USA
| | - Elaina Kenyon
- Center for Computational Toxicology and Exposure, Office of Research and Development, U.S. Environmental Protection Agency, RTP, RTP, NC, USA
| | - Wendy N Nembhard
- Arkansas Center for Birth Defects Research and Prevention and the Department of Epidemiology, Fay. W. Boozman College of Public Health, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Kari A Weber
- Arkansas Center for Birth Defects Research and Prevention and the Department of Epidemiology, Fay. W. Boozman College of Public Health, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - John Nuckols
- Colorado State University, Fort Collins, CO, USA; JRN Environmental Health Sciences, LTD, North Bethesda, MD, USA
| | - J Michael Wright
- Center for Public Health and Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency. RTP, NC, Washington, DC, Cincinnati, OH, USA
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Weisman RJ, Heinrich A, Letkiewicz F, Messner M, Studer K, Wang L, Regli S. Estimating National Exposures and Potential Bladder Cancer Cases Associated with Chlorination DBPs in U.S. Drinking Water. ENVIRONMENTAL HEALTH PERSPECTIVES 2022; 130:87002. [PMID: 35913906 PMCID: PMC9342685 DOI: 10.1289/ehp9985] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 06/21/2022] [Accepted: 06/27/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND Disinfection byproducts (DBPs) in public water systems (PWS) are an unintended consequence resulting from reactions between mostly chlorine-based disinfectants and organic and inorganic compounds in source waters. Epidemiology studies have shown that exposure to DBP (specifically trihalomethanes) was associated with an increased risk of bladder cancer. OBJECTIVE Our goal was to characterize the relative differences in exposures and estimated potential bladder cancer risks for people served by different strata of PWS in the United States and to evaluate uncertainties associated with these estimates. METHODS We stratified PWS by source water type (surface vs. groundwater) and population served (large, medium, and small) and calculated population-weighted mean trihalomethane-4 (THM4) concentrations for each stratum. For each stratum, we calculated a population attributable risk (PAR) for bladder cancer using odds ratios derived from published pooled epidemiology estimates as a function of the mean THM4 concentration and the fraction of the total U.S. population served by each stratum of systems. We then applied the stratum-specific PARs to the total annual number of new bladder cancer cases in the U.S. population to estimate bladder cancer incidence in each stratum. RESULTS Our results show that approximately 8,000 of the 79,000 annual bladder cancer cases in the United States were potentially attributable to DBPs in drinking water systems. The estimated attributable cases vary based on source water type and system size. Approximately 74% of the estimated attributable cases were from surface water systems serving populations of > 10,000 people. We also identified several uncertainties that may affect the results from this study, primarily related to the use of THM4 as a surrogate measure for DBPs relevant to bladder cancer. DISCUSSION Despite significant reductions in exposure over the past several decades, our study suggests that ∼ 10 % of the bladder cancer cases in the United States may still be attributed to exposure to DBPs found in drinking water systems. https://doi.org/10.1289/EHP9985.
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Affiliation(s)
- Richard J Weisman
- U.S. Environmental Protection Agency (U.S. EPA), Washington, DC, USA
| | - Austin Heinrich
- U.S. Environmental Protection Agency (U.S. EPA), Washington, DC, USA
| | | | - Michael Messner
- U.S. Environmental Protection Agency (U.S. EPA), Washington, DC, USA
| | - Kirsten Studer
- U.S. Environmental Protection Agency (U.S. EPA), Washington, DC, USA
| | - Lili Wang
- U.S. Environmental Protection Agency (U.S. EPA), Washington, DC, USA
| | - Stig Regli
- U.S. Environmental Protection Agency (U.S. EPA), Washington, DC, USA
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Kenyon EM, Eklund C, Pegram RA, Lipscomb JC. Comparison of in vivo derived and scaled in vitro metabolic rate constants for several volatile organic compounds (VOCs). Toxicol In Vitro 2020; 69:105002. [PMID: 32946980 DOI: 10.1016/j.tiv.2020.105002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 08/26/2020] [Accepted: 09/13/2020] [Indexed: 10/23/2022]
Abstract
Metabolic rate parameters estimation using in vitro data is necessary due to numbers of chemicals for which data are needed, trend towards minimizing laboratory animal use, and limited opportunity to collect data in human subjects. We evaluated how well metabolic rate parameters derived from in vitro data predict overall in vivo metabolism for a set of environmental chemicals for which well validated and established methods exist. We compared values of VmaxC derived from in vivo vapor uptake studies with estimates of VmaxC scaled up from in vitro hepatic microsomal metabolism studies for VOCs for which data were available in male F344 rats. For 6 of 7 VOCs, differences between the in vivo and scaled up in vitro VmaxC estimates were less than 2.6-fold. For bromodichloromethane (BDCM), the in vivo derived VmaxC was approximately 4.4-fold higher than the in vitro derived and scaled up VmaxC. The more rapid rate of BDCM metabolism estimated based in vivo studies suggests other factors such as extrahepatic metabolism, binding or other non-specific losses making a significant contribution to overall clearance. Systematic and reliable utilization of scaled up in vitro biotransformation rate parameters in PBPK models will require development of methods to predict cases in which extrahepatic metabolism and binding as well as other factors are likely to be significant contributors.
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Affiliation(s)
- Elaina M Kenyon
- Center for Computational Toxicology and Exposure, U.S. EPA, Office of Research and Development, Research Triangle Park, NC, United States.
| | - Christopher Eklund
- Center for Computational Toxicology and Exposure, U.S. EPA, Office of Research and Development, Research Triangle Park, NC, United States
| | - Rex A Pegram
- Center for Computational Toxicology and Exposure, U.S. EPA, Office of Research and Development, Research Triangle Park, NC, United States
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DeMarini DM. A review on the 40th anniversary of the first regulation of drinking water disinfection by-products. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2020; 61:588-601. [PMID: 32374889 PMCID: PMC7640377 DOI: 10.1002/em.22378] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 04/07/2020] [Accepted: 04/11/2020] [Indexed: 05/05/2023]
Abstract
Water disinfection, primarily by chlorination, is one of the greatest achievements of public health. However, more than half a century after its introduction, studies in the 1970s reported that (a) chlorine interacted with organic matter in the water to form disinfection by-products (DBPs); (b) two DBPs, chloroform and bromoform, both trihalomethanes (THMs), were rodent carcinogens; (c) three brominated THMs were mutagenic; in six studies chlorinated drinking waters in the United States and Canada were mutagenic; and (d) in one epidemiological study there was an association between bladder cancer mortality and THM exposure. This led the U.S. Environmental Protection Agency to issue its first DBP regulation in 1979. Forty years later, >600 DBPs have been characterized, 20/22 have been shown to be rodent carcinogens, >100 have been shown to be genotoxic, and 1000s of water samples have been found to be mutagenic. Data support a hypothesis that long-term dermal/inhalation exposure to certain levels of the three brominated THMs, as well as oral exposure to the haloacetic acids, combined with a specific genotype may increase the risk for bladder cancer for a small but significant population group. Improved water-treatment methods and stricter regulations have likely reduced such risks over the years, and further reductions in potential risk are anticipated with the application of advanced water-treatment methods and wider application of drinking water regulations. This 40-year research effort is a remarkable example of sustained cooperation between academic and government scientists, along with public/private water companies, to find answers to a pressing public health question.
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Affiliation(s)
- David M. DeMarini
- Biomolecular and Computational Toxicology Division, Center for Computational Toxicology and Exposure, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina
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Tan YM, Chan M, Chukwudebe A, Domoradzki J, Fisher J, Hack CE, Hinderliter P, Hirasawa K, Leonard J, Lumen A, Paini A, Qian H, Ruiz P, Wambaugh J, Zhang F, Embry M. PBPK model reporting template for chemical risk assessment applications. Regul Toxicol Pharmacol 2020; 115:104691. [PMID: 32502513 PMCID: PMC8188465 DOI: 10.1016/j.yrtph.2020.104691] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 05/18/2020] [Accepted: 05/28/2020] [Indexed: 12/04/2022]
Abstract
Physiologically-based pharmacokinetic (PBPK) modeling analysis does not stand on its own for regulatory purposes but is a robust tool to support drug/chemical safety assessment. While the development of PBPK models have grown steadily since their emergence, only a handful of models have been accepted to support regulatory purposes due to obstacles such as the lack of a standardized template for reporting PBPK analysis. Here, we expand the existing guidances designed for pharmaceutical applications by recommending additional elements that are relevant to environmental chemicals. This harmonized reporting template can be adopted and customized by public health agencies receiving PBPK model submission, and it can also serve as general guidance for submitting PBPK-related studies for publication in journals or other modeling sharing purposes. The current effort represents one of several ongoing collaborations among the PBPK modeling and risk assessment communities to promote, when appropriate, incorporating PBPK modeling to characterize the influence of pharmacokinetics on safety decisions made by regulatory agencies.
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Affiliation(s)
- Yu-Mei Tan
- U.S. Environmental Protection Agency, Office of Pesticide Programs, Health Effects Division, 109 TW Alexander Dr, Research Triangle Park, NC, 27709, USA.
| | - Melissa Chan
- Corteva Agriscience, Haskell R&D Center, 1090 Elkton Road, Newark, DE, 19714, USA.
| | - Amechi Chukwudebe
- BASF Corporation, 26 Davis Drive, Research Triangle Park, NC, 27709, USA.
| | - Jeanne Domoradzki
- Corteva Agriscience, Haskell R&D Center, 1090 Elkton Road, Newark, DE, 19714, USA
| | - Jeffrey Fisher
- National Center for Toxicological Research, US Food and Drug Administration, 3900 NCTR Rd, Jefferson, AR, 72079, USA.
| | - C Eric Hack
- ScitoVation, 100 Capitola Drive, Durham, NC, 27713, USA.
| | - Paul Hinderliter
- Syngenta Crop Protection, LLC, 410 Swing Rd, Greensboro, NC, 27409, USA.
| | - Kota Hirasawa
- Sumitomo Chemical Co, Ltd, 1-98, Kasugadenaka 3-chome, Konohana-ku, Osaka, 554-8558, Japan.
| | - Jeremy Leonard
- Oak Ridge Institute for Science and Education, 100 ORAU Way, Oak Ridge, TN, 37830, USA.
| | - Annie Lumen
- National Center for Toxicological Research, US Food and Drug Administration, 3900 NCTR Rd, Jefferson, AR, 72079, USA.
| | - Alicia Paini
- European Commission Joint Research Centre, Via E. Fermi 2749, Ispra I, 21027, Italy.
| | - Hua Qian
- ExxonMobil Biomedical Sciences, Inc, 1545 US Hwy 22 East, Annandale, NJ, 08801, USA.
| | - Patricia Ruiz
- CDC-ATSDR, 4770 Buford Hwy, Mailstop S102-1, Chamblee, GA, 3034, USA.
| | - John Wambaugh
- US Environmental Protection Agency, Center for Computational Toxicology and Exposure, 109 TW Alexander Dr, Research Triangle Park, NC, 27711, USA.
| | - Fagen Zhang
- The Dow Chemical Company, 1803 Building, Midland, MI, 48674, USA.
| | - Michelle Embry
- Health and Environmental Sciences Institute, 740 15th Street, NW, Suite 600, Washington, DC, 20005, USA.
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Tan YM, Worley RR, Leonard JA, Fisher JW. Challenges Associated With Applying Physiologically Based Pharmacokinetic Modeling for Public Health Decision-Making. Toxicol Sci 2019; 162:341-348. [PMID: 29385573 DOI: 10.1093/toxsci/kfy010] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The development and application of physiologically based pharmacokinetic (PBPK) models in chemical toxicology have grown steadily since their emergence in the 1980s. However, critical evaluation of PBPK models to support public health decision-making across federal agencies has thus far occurred for only a few environmental chemicals. In order to encourage decision-makers to embrace the critical role of PBPK modeling in risk assessment, several important challenges require immediate attention from the modeling community. The objective of this contemporary review is to highlight 3 of these challenges, including: (1) difficulties in recruiting peer reviewers with appropriate modeling expertise and experience; (2) lack of confidence in PBPK models for which no tissue/plasma concentration data exist for model evaluation; and (3) lack of transferability across modeling platforms. Several recommendations for addressing these 3 issues are provided to initiate dialog among members of the PBPK modeling community, as these issues must be overcome for the field of PBPK modeling to advance and for PBPK models to be more routinely applied in support of public health decision-making.
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Affiliation(s)
- Yu-Mei Tan
- National Exposure Research Laboratory, United States Environmental Protection Agency, Research Triangle Park, North Carolina 27709
| | - Rachel R Worley
- Agency for Toxic Substances and Disease Registry, Atlanta, Georgia 30341
| | - Jeremy A Leonard
- Oak Ridge Institute for Science and Education, Oak Ridge, Tennessee 37830
| | - Jeffrey W Fisher
- National Center for Toxicological Research, United States Food and Drug Administration, Jefferson, Arizona 72079
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Kenyon EM, Lipscomb JC, Pegram RA, George BJ, Hines RN. The Impact of Scaling Factor Variability on Risk-Relevant Pharmacokinetic Outcomes in Children: A Case Study Using Bromodichloromethane (BDCM). Toxicol Sci 2019; 167:347-359. [PMID: 30252107 PMCID: PMC10448349 DOI: 10.1093/toxsci/kfy236] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Biotransformation rates extrapolated from in vitro data are used increasingly in human physiologically based pharmacokinetic (PBPK) models. This practice requires use of scaling factors, including microsomal content (mg of microsomal protein/g liver, MPPGL), enzyme specific content, and liver mass as a fraction of body weight (FVL). Previous analyses indicated that scaling factor variability impacts pharmacokinetic (PK) outcomes used in adult population dose-response studies. This analysis was extended to pediatric populations because large inter-individual differences in enzyme ontogeny likely would further contribute to scaling factor variability. An adult bromodichloromethane (BDCM) model (Kenyon, E. M., Eklund, C., Leavens, T. L., and Pegram, R. A. (2016a). Development and application of a human PBPK model for bromodichloromethane (BDCM) to investigate impacts of multi-route exposure. J. Appl. Toxicol. 36, 1095-1111) was re-parameterized for neonates, infants, and toddlers. Monte Carlo analysis was used to assess the impact of pediatric scaling factor variation on model-derived PK outcomes compared with adult findings. BDCM dose metrics were estimated following a single 0.05-liter drink of water or a 20-min bath, under typical (5 µg/l) and plausible higher (20 µg/l) BDCM concentrations. MPPGL, CYP2E1, and FVL values reflected the distribution of reported pediatric population values. The impact of scaling factor variability on PK outcome variation was different for each exposure scenario, but similar for each BDCM water concentration. The higher CYP2E1 expression variability during early childhood was reflected in greater variability in predicted PK outcomes in younger age groups, particularly for the oral exposure route. Sensitivity analysis confirmed the most influential parameter for this variability was CYP2E1, particularly in neonates. These findings demonstrate the importance of age-dependent scaling factor variation used for in vitro to in vivo extrapolation of biotransformation rates.
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Zhang Y, Han X, Niu Z. Health risk assessment of haloacetonitriles in drinking water based on internal dose. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2018; 236:899-906. [PMID: 29157971 DOI: 10.1016/j.envpol.2017.10.049] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 10/10/2017] [Accepted: 10/12/2017] [Indexed: 06/07/2023]
Abstract
To estimate the health risk of haloacetonitriles in different kinds of drinking water, the concentrations of haloacetonitriles in tap water, boiled water and direct drinking water were detected. The physiologically based pharmacokinetic (PBPK) model was used to calculate internal dose in the human body for haloacetonitriles through ingestion, and the probability distributions of the non-carcinogenic risk of haloacetonitriles for human via drinking water were assessed. This study found that the mean concentrations of dichloroacetonitrile (DCAN) in tap water, boiled water and direct drinking water were 0.955 μg/L, 0.207 μg/L and 0.127 μg/L, and those of dibromoacetonitrile (DBAN) were 0.221 μg/L, 0.104 μg/L, 0.089 μg/L, respectively. In China, direct drinking water is used most frequently, so the concentrations of haloacetonitriles in direct drinking water were used to obtain data on the internal dose of haloacetonitriles. In addition, the simulation results for the PBPK model showed that the highest and lowest concentrations of DCAN occurred in the liver and venous blood, respectively. The peak concentrations of DBAN in each tissue were in the decreasing order liver > rapidly perfused tissue > kidney > slowly perfused tissues > fat > arterial blood (venous blood). In addition, the highest 95th percentile hazard quotients (HQ) value of haloacetonitriles via drinking water for humans was 8.89 × 10-3, much lower than 1. The 95th percentile hazard index (HI) was 0.046, which was also lower than 1, suggesting that there was no obvious non-carcinogenic risk.
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Affiliation(s)
- Ying Zhang
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China.
| | - Xuemei Han
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China.
| | - Zhiguang Niu
- School of Marine Science and Technology, Tianjin University, Tianjin 300072, China.
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Li XF, Mitch WA. Drinking Water Disinfection Byproducts (DBPs) and Human Health Effects: Multidisciplinary Challenges and Opportunities. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:1681-1689. [PMID: 29283253 DOI: 10.1021/acs.est.7b05440] [Citation(s) in RCA: 382] [Impact Index Per Article: 63.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
While drinking water disinfection has effectively prevented waterborne diseases, an unintended consequence is the generation of disinfection byproducts (DBPs). Epidemiological studies have consistently observed an association between consumption of chlorinated drinking water with an increased risk of bladder cancer. Out of the >600 DBPs identified, regulations focus on a few classes, such as trihalomethanes (THMs), whose concentrations were hypothesized to correlate with the DBPs driving the toxicity of disinfected waters. However, the DBPs responsible for the bladder cancer association remain unclear. Utilities are switching away from a reliance on chlorination of pristine drinking water supplies to the application of new disinfectant combinations to waters impaired by wastewater effluents and algal blooms. In light of these changes in disinfection practice, this article discusses new approaches being taken by analytical chemists, engineers, toxicologists and epidemiologists to characterize the DBP classes driving disinfected water toxicity, and suggests that DBP exposure should be measured using other DBP classes in addition to THMs.
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Affiliation(s)
- Xing-Fang Li
- Division of Analytical and Environmental Toxicology, Department of Laboratory Medicine and Pathology, Faculty of Medicine and Dentistry, University of Alberta , Edmonton, AB T6G 2G3 Canada
| | - William A Mitch
- Department of Civil and Environmental Engineering, Stanford University , 473 Via Ortega, Stanford, California 94305, United States
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Kenyon EM, Eklund C, Lipscomb JC, Pegram RA. The impact of variation in scaling factors on the estimation of internal dose metrics: a case study using bromodichloromethane (BDCM). Toxicol Mech Methods 2016; 26:620-626. [DOI: 10.1080/15376516.2016.1225141] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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