## Ecosystems Research Division 

# What is in Our Drinking Water? Identification of New Chemical Disinfection By-products (DBPs)

What is a DBP? A drinking water disinfection by-product (DBP) is formed when the chemical used for disinfecting the drinking water reacts with natural organic matter and/or bromide/iodide in the source water. Popular disinfectants include chlorine, ozone, c hlorine dioxide, and chloramine. Source waters include rivers, lakes, streams, groundwater, and sometimes seawater. We have only known about DBPs since 1974, when chloroform was identified by Rook as a DBP resulting from the chlorination of tap water. Sinc e then, hundreds of DBPs have been identified in drinking water.

So what? Millions of people in the U.S. are exposed to these drinking wate r DBPs every day. While it is vitally important to disinfect drinking water, as thousands of people died from waterborne ill nesses before we started disinfection practices in the early 190 0s, it is also important to minimize the chemical DBPs formed. Seve ral DBPs have been linked to cancer in laboratory animals, and as a result, the U.S. EPA has some of these DBPs regulated. However, there are many more DBPs that have still not been identified a nd tested for toxicity or cancer effects. Currently, we have only identified about 50% of the total organic halide (TOX) that is measured in chlorinated drinking water. There is much less known about DBPs from the newer alternative disinfectants, such as ozone, chlorine dioxide, and chloramine, which are gaining in popularity in the U.S. Are these alternative disinfectants safer than c hlorine? What kinds of by-products are formed? And, what about the unidentified chlorine DBPs that people are exposed to through their drinking water--both from drinking and showering/bathing? The objective of our research is to find out what these DBPs are--to thoroughly characterize the chemicals f ormed in drinking water treatment--and to ultimately minimize any harmful ones that are formed. Our research approach

z Gas chromatography/mass spectrometry (GC/MS), liquid chromatogr aphy/mass spectrometry (LC/MS), and gas chromatography/infrared spectroscopy (GC/IR)

techniques are used to identify the unknown by-products

z NIST and Wiley mass spectral databases are used first to iden tify any DBPs that happen to be present in these databases

z Because many DBPs are not in these databases, most of our work involves unconventional MS and IR techniques, as well as a great deal of scientific interpretation of the

spectra

z High resolution MS provides empirical formula information for th e unknown chemical (e.g., how many carbons, hydrogens, oxygens, nitrogens, etc. are in the chemical’s

structure)

z Chemical ionization MS provides molecular weight information wh en this is not provided in conventional electron ionization mass spectra

z IR spectroscopy provides functional group information (e.g., whether the oxygens are due to a carboxylic acid group, a ketone, an alcohol, or an aldehyde)

z LC/MS is used to identify compounds that cannot be extracted fr om water (the highly polar, hydrophilic ones), as well as the hi gh molecular weight, nonvolatile DBPs. This

is a major missing gap in our knowledge about DBPs--so far, most DBPs identified have been those that are easily extracted from water and are volatile enough to analyze by GC/MS

z Novel derivatization techniques are also applied to aid in the identification of highly polar DBPs

z Formation and fate & transport studies are conducted to better understand how certain priority DBPs are formed and transformed in treatment and distribution systems 

### Currently We recently completed an iodo-DBP occurrence study (published in the Nov. 15, 2008 issue of Environmental Science & Technology; ES&T 2008, 42 (22), 8330-8338) that involved the measurement of iodo-acid DBPs and iodo-THMs in drin king waters from 23 cities across the U.S. and Canada, and the study of their genotoxicity and cytotoxicity. We identified the iodo-acids for the first time as part of a large nationwide occurrence study of priority DBPs (mentioned belo w), and they are important because iodoacetic acid was found to be highly genotoxic (to mammalian cells), and it is more genotoxic than the regulated chloro/bromo-haloacetic acid s (ES&T 2004, 38 (18): 4713-4722). This study helped to underscore the increased formation of iodo-DBPs with chloramination, which is an increasingly popular disinfectant us ed in the U.S. The first phase of the Four Lab Study was also published recently (see special issue of Journal of Toxicology and Environmental Health, Part A, October 22, 2008 issue), where we combined chemical and toxicological characterization (with an emphasis on newer reproductive and developmental effects) of c omplex DBP mixtures. This study is called the Four Lab Study because it involves the collaboration of scienti sts from the four national laboratories/centers of the U.S. EPA: The National Health and Environmental Effects Research Laboratory, the National Exposure Research Laboratory, the National Risk Management Research Laboratory, and the Natio nal Center for Environmental Assessment. The Four Lab Study serves to address potential heal th concerns that cannot be addressed directly by the toxicologi cal study of individual DBPs or defined DBP mixtures, and in essence, provides toxicological information for the complete drinking water mixture: both the known DBPs, as well as the unidentified fraction of DBPs. Drinking water treated with chlorine or ozone-chlorine was concentrated by reverse osmosis to maintain a water matrix suitable for the a nimal studies. The next phase of this work is also nearing completion and included a larger battery of toxicological endpoints and focused on chlorinated drinking water. Our earlier nationwide DBP occurrence study was published in ES&T in the Dec. 1, 2006 issue (ES&T, 2006, 40, 7175-7185), and ca n also be found in its full 400+ page report at EPA/600/R

- 02/068 . This large study involved the sampling of drinking waters across the U.S. (disinfected with the different disinfectants and with different water quality, including elevated levels of bromide in the source water). A group of >50 DBPs that resulted from a prioritization of >500 DBPs in the l iterature for predicted adverse health effects was quantified in these drinking waters. Fate and transport studies were also conducted in the drinking water distribution systems to determine whether these DBPs changed in You are here: EPA Home Athens Research Process Drinking Wate r file:///C:/Documents%20and%20Settings/efleisig/My%20Documents/FL% 20rule%202009-2010/DOCKET/Preamble%20and%20Rule%20References/D rinking%20Water%20%20Ecosystems% 20Research%20Division%20%20US%20EPA.mht 

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...concentration or were transformed in the distribution systems. In addition to obtain ing important quantitative information on t hese new DBPs (to help in prioritizing health effects testing), important new discoveries were made regarding the use of alternative disinfectants. While the use of alternative dis infectants lowered the levels of the four regulated trihalomethanes and five haloacetic acids (as compared to chlorine), many of the other prioritized DBPs were formed at higher l evels with these alternative disinfectants. For example, the highest levels of iodinated DBPs were found in chloraminated drinking water, the highest levels of halonitromethan es were found in pre-ozonated drinking water, and dihaloaldehydes were highest at a plant using chloramines and ozone. Our new work includes investigating other potential sources of iodine in the formation of iodo-DBPs and investigating the influ ence of the length of free chlorine contact time (before ammonia addition to form chloramines) on their formation. In other research, a toxicity-based identification approach (using mammalian cell and medaka fish assays) is being used to focus identification efforts on the most toxic drinking water fractions, with an emphasis on obtaining new inform ation on high molecular weight DBPs (which are believed to make up approximately 50% of the halogenated DBPs produced). 

### Recent results

z A recent iodo-DBP occurrence study (ES&T 2008, 42 (22), 8330-8338 ) has provided the first quantit ative occurrence data for high ly genotoxic iodo-acid DBPs and

information on their formation (along with iodo-THMs) in chloraminated drinking water, along with the first toxicity data for i odo-THMs and iodo-acids (beyond the first work on iodoacetic acid)

z The first phase of the Four Lab Study (Environ. Toxicol. Health, Pt. A, 2008, 71, 1125-1132 and following papers in this issue) reports results from an integrated

chemical/toxicological research study to investigate the toxicological effects of complex DBP mixtures

z A Nationwide DBP Occurrence Study (ES&T, 2006, 40, 7175-7185) pr ovided important new quantitative information on unregulated DB Ps that have the potential to cause

adverse health effects based on a structure-activity analysis (Woo et al., 2002); several of these DBPs have concentrations sim ilar to some that are already regulated

z The use of alternative disinfectants can produce higher levels of these DBPs, as compared to chlorine

z Collaborations are ongoing with health effects researchers to study selected DBPs for potential adverse health effects

Gordon Research Conference on DBPs The second Gordon Research Conference on drinking water DBPs will be held August 9-14, 2009, at Mount Holyoke College in South Hadley, Massachusetts. Like the first one initiated in 2006 (where scientists from 22 countries came), this conference will bring together scientists from different disc iplines: chemists, toxicologists, epidemiologists, engineers, clinicians, human exposure scientists, risk assessors, and regulators to address the issues with drinking water DBPs . Ben Blount from the Centers for Disease Control and Prevention (CDC) will be the Chair of the 2009 conference. Contact Ben Blount ( bkb3@cdc.gov ) or Susan Richardson ( richardson.susan@epa.gov ) for more information. 

### Useful publications Weinberg, H. S., S. W. Krasner, S. D. Richardson, and A. D. Th ruston, Jr. The Occurrence of Disinfection By-Products (DBPs) of Health Concern in Drinking Water: Results of a Nationwide DBP Occurrence Study. EPA/600/R02/068 . U.S. Environmental Protection Agency, National Exposure Research Laboratory, Athens, GA. 2002. Richardson, S. D., F. Fasano, J. J. Ellington, F. G. Crumley, K. M. Buettner, J. J. Evans, B. C. Blount, L. K. Silva, T. J. Wai te, G. W. Luther, A. B. McKague, R. J. Miltner, E. D. Wagner, and M. J. Plewa. 2008. Occurrence and Mammalian Cell Toxicity of Iodinated Disinfection Byproducts in Drinking Water. Environ. Sci. Technol., 42 (22): 8330-8338. Plewa, M. J., M. G. Muellner, S. D. Richardson, F. Fasano, K. M. Buettner, Y.-T. Woo, A. B. McKague, and E. D. Wagner. 2008. Occurrence, Synthesis, and Genotoxicity of Haloacetamides: An Emerging Class of Nitrogenous Drinking Water Disinfection Byproducts. Environ. Sci. Technol. , 42 (3), 955-961. Richardson, S. D., A. D. Thruston, Jr., S. W. Krasner, H. S. We inberg, R. J. Miltner, M. G. Narotsky, and J. E. Simmons. 2008. Integrated Disinfection Byproducts Mixtures Research: Comprehensive Characterization of Water Concentrates Prepared from Chlorinated and Ozonated/Postchlorinated Drinking Water. J. Toxicol. Environ. Health , Pt. A, 71: 1165-1186. Simmons, J. E., S. D. Richardson, T. F. Speth, R. J. Miltner, G. Rice, K. M. Schenck, E. S. Hunter, III, and L. K. Teuschler. 2008. Research Issues Underlying the Four-Lab Study: Integrated Disinfection Byproducts Mixtures Research. J. Toxicol. Environ. Health , Pt. A, 71: 1125-1132. Miltner, R. J., T. F. Speth, S. D. Richardson, S. W. Krasner, H. S. Weinberg, and J. E. Simmons. 2008. Integrated Disinfectio n Byproducts Mixtures Research: Disinfection of Drinking Waters by Chlorination and Ozonation/Postchlorination Treatment Scenarios. J. Toxicol. Environ. Health , Pt. A, 71: 1133-1148. Speth, T. F., R. J. Miltner, S. D. Richardson, and J. E. Simmons . 2008. Integrated Disinfection Byproducts Mixtures Research: Concentration by Reverse Osmosis Membrane Techniques of Disinfection Byproducts from Water Disinfected by Chlorination and Ozonation/Postchlorination. J. Toxicol. Environ. Health , Pt. A, 71: 1149-1164. Rice, G., L. K. Teuschler, S. D. Richardson, T. F. Speth, and J. E. Simmons. 2008. Integrated Disinfection Byproducts Mixture s Research: Assessing Reproductive and Developmental Risks Posed by Complex Disinfection Byproduct Mixtures. J. Toxicol. Environ. Health , Pt. A, 71: 1222-1234. Weisel, C. P., S. D. Richardson, B. Nemery, G. Aggazzotti, E. Barald i, E. R. Blatchley, III, B. C. Blount, K-H. Carlsen, P. A. Eggleston, F. H. Frimmel, M. Goodman, G. Gordon, S. A. Grinshpun, D. Heederik, M. Kogenvinas, J. S. LaKind, M. J. Nieuwenhuijsen, F. C. Piper, S. A. Sattar. 2008. Childhood Asth ma and Environmental Exposures at Swimming Pools: State of the Science and Research Recommendations. Environ. Health Perspect. , in press. Muellner, M. G., E. D. Wagner, K. McCalla, S. D. Richardson, Y. -T. Wood, and M. J. Plewa. 2007. Haloacetonitriles vs. Regulate d Haloacetic Acids: Are Nitrogen Containing DBPs More Toxic? Environ. Sci. Technol., 41 (2): 645-651. Zwiener, C., S. D. Richardson, D. M. DeMarini, T. Grummt, T. Glauner, and F. H. Frimmel. 2007. Drowining in Disinfection By-P roducts? Swimming Pool Water Quality Reconsidered. Environ. Sci. Technol., 41 (2): 363-372. 

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...Plewa, M. J., M. G. Muellner, S. D. Richardson, F. Fasano, K. M. Buettner, Y.-T. Woo, A. B. McK ague, and E. D. Wagner. 2007. Occurrence, Synthesis, and Mammalian Cell Cytotoxicity and Genotoxicity of Haloacetamides: An Emergi ng Class of Nitrogenous Drinking Water Disinfection By-Product. Environ. Sci. Technol. , 42 (3): 955-961. Richardson. S. D. 2008. Environmental Mass Spectr ometry: Emerging Contaminants and Current Issues. Anal. Chem ., 80(12): 4373-4402. Richardson, S. D., C. Rav-Acha, and G. D. Simpson. 2009. Chlorine Dioxide Chemistry, Reactions, and Disinfection By-Products. In Chlorine Dioxide in Drinking Water Treatment, American Water Works Association Research Foundation, in press. Richardson, S. D., M. J. Plewa, E. D. Wagner, R. Schoeny, and D. M. DeMarini. Occurrence, Genotoxicity, and Carcinogenicity of Emerging Disinfection By-Products in Drinking Water: A Review and Roadmap for Research. 2007. Mutat. Res ., 636: 178-242. Richardson, S. D. Water Analysis: Emerging Contaminants and Current Issues. 2007. Anal. Chem ., 79(12): 4295-4324. Krasner, S. W., H. S. Weinberg, S. D. Richardson, S. Pastor, R. Chinn, M. J. Sclimenti, G. Onstad, and A. D. Thruston, Jr. 200 6. The Occurrence of a New Generation of Disinfection Byproducts. Environmental Science & Technology, 40 (23): 7175-7185. Richardson. S. D. Environmental Mass Spectrometry: Emerging C ontaminants and Current Issues. 2006. Analytical Chemistry, 78 (12): 4021-4046. Richardson, S. D., and T. Ternes. 2005. Water Analysis: Emer ging Contaminants and Current Issues. Analytical Chemistry, 77 (12): 3807-3838. Cemeli, E., E. D. Wagner, D. Anderson, S. D. Richardson, and M. J. Plewa. 2006. Modulation of the Cytotoxicity and Genotoxici ty of the Drinking Water DBP Iodoacetic Acid by Suppressors of Oxidative Stress. Environmental Science & Technology, 40 (6): 1878-1883. Vincenti, M., S. Biazzi, N. Ghiglione, M. C. Valsania, and S. D. Richardson. 2005. Comparison of Highly- Fluorinated Chlorofo rmates as Direct Aqueous Sample Derivatizing Agents for Hydrophilic Analytes and Drinking Water Disinfection By-Products. Journal of the American Society for Mass Spectrom etry, 16 (6): 803-813. Plewa, M. J., E. D. Wagner, S. D. Richardson, A. D. Thruston, Jr ., Y.-T. Woo, and A. B. McKague. 2004. Chemical and Biologica l Characterization of Newly Discovered Iodoacid Drinking Water Disinfection Byproducts. Environm ental Science & Technology, 38(18): 4713-4722. Zwiener, C., and S. D. Richardson. 2005. Drinking Water Disinfection By-Product Analysis by LC/MS and LC/MS/MS. Trends in An alytical Chemistry, 24(7): 613-621. (Invited review article for special thematic issue on Liquid Chromatography-Tandem Mass Spectrometry). Plewa, M. J., E. D. Wagner, P. Jazwierska, S. D. Richardson, P. H. Chen, and A. B. McKague. 2004. Halonitromethane Drinking W ater Disinfection Byproducts: Chemical Characterization and Mammalian Cell Cytotoxicity and Genotoxicity. Environmental Science & Technology, 38(1): 62-68. Kundu, B., S. D. Richardson, P. D. Swartz, P. P. Matthews, A. M. Richard, and D. M. DeMarini. 2004. Mutagenicity in Salmonell a of Halonitrometanes: A Recently Recognized Class of Disinfection By-Product in Drinking Water. Mutation Research, 562: 39-65. Kundu, B., S. D. Richardson, C. A. Granville, D. T. Shaughnessy, N. M. Hanley, P. D. Swartz, A. M. Richard, and D. M. DeMarini. 2004. Comparative Mutagenicity of Halomethanes and Halonitromethanes in Salmonella TA100: Structure-Activity Analysis and Mutation Spectra. Mutation Research, 5 54: 335-350. Richardson, S. D. 2004. Environmental Mass Spectrometry: Em erging Contaminants and Current Issues. Analytical Chemistry, 76 (12): 3337-3364. Simmons, J. E., L. K. Teuschler, C. Gennings, T. F. Speth, S. D. Richardson, R. J. Milt ner, M. G. Narotsky, K. D. Schenck, E. S . Hunter, III, R. C. Hertzberg, III, and G. Rice. 2004. Component-Based and Whole-Mixture Techniques for Addressing the Toxicity of Drinking Water Disinfection Byproducts Mixt ures. Journal of Toxicology & Environmental Health, 67: 741-754. Richardson, S.D., J. E. Simmons, and G. Rice. 2002. DBPs: The Next Generation. Environmental Science & Technology, 36(9): 19 8A-205A. Woo, Y.-T., D. Lai, J. L. McLain, M. K. Manibusan, and V. Della rco. 2002. Environmental Health Perspectives, 110 (Suppl. 1): 75-87. Richardson, S. D., A. D. Thruston, Jr., C. Rav-Acha, L. Groisman, I. Popilevsky, V. Glezer, A. B. McKague, M. J. Plewa, and E. D. Wagner. 2003. Tribromopyrrole and Other DBPs Produced by the Disinfection of Drinking Water Rich in Bromide. Environmental Science & Technology, 37(17): 3782-3793. Richardson, S. D. 2003. Water Analysis: Emerging Contaminants and Current Issues. Analytical Chemistry, 75(12): 2831-2857. Richardson, S. D. 2003. Disinfection By-Products and Other Emerging Contaminants in Drinking Water. Trends in Analytical Che mistry, 22(10):666-684. Chen, P. H., S. D. Richardson, S. W. Krasner, G. Majetich, and G. L. Glish. 2002. Hydrogen Abstraction and Decomposition of T ribromonitromethane and Other Trihalo Compounds by GC/MS. Environmental Science & Technology, 36(15): 3362-3371. Simmons, J. E., S. D. Richardson, T. F. Speth, R. J. Miltner, G. Rice, K. M. Schenck, E. S. Hunter, III, and L. K. Teuschler. 2002. Development of a Research Strategy for Integrated Technology-Based Toxicological and Chemical Evaluation of Complex Mixtures of Drinking Water Disinfection Byproducts . Environmental Health Perspectives, 110 (Supp. 6): 1013-1024. Arbuckle, T. E., S. E. Hrudey, S. W. Krasner, J. R. Nuckols, S. D. Richardson, P. Singer, P. Mendola, L. Dodds, C. Weisel, D. L . Ashley, K. L. Froese, R. A. Pegram, I. R. Schultz, J. Reif, A. M. Bachand, F. M. Benoit, M. Lynberg, C. Poole, and K. Waller. 2002. Assessing Exposure in Epidemiologic Studies to Disinfection By-products in Drinking Water: Report from an International Workshop. Environmental Health Perspectives, 110 (Supp. 1): 53-60. Richardson, S. D., T. V. Caughran, T. Poiger, Y. Guo, and F. G. Crumley. 2000. Application of DNPH Derivatization with LC/MS to the Identification of Polar Carbonyl Disinfection By-products in Drinking Water. Ozone: Science & Engineering, 22: 653-675. 

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...Last updated on Thursday, December 17th, 2009. WCMS

Richardson, S. D., A. D. Thruston, Jr., T. V. Caughran, P. H. Chen, T. W. Collette, T. L. Floyd, K. M. Schenck, B. W. Lykins, J r., G.-R. Sun, and G. Majetich. 1999. Identification of New Ozone Disinfection By-products in Drinking Water. Environmental Science & Technology, 33: 3368-3377. Richardson, S. D., A. D. Thruston, Jr., T. V. Caughran, P. H. Chen, T. W. Collette, T. L. Floyd, K. M. Schenck, B. W. Lykins, J r., G.-R. Sun, and G. Majetich. 1999. Identification of New Drinking Water Disinfection By-products Formed in the Pr esence of Bromide. Environmental Science & Technology, 33: 3378 -3383. Richardson, S. D., A. D. Thruston, Jr., T. V. Caughran, P. H. Chen, T. W. Collette, K. M. Schenck, B. W. Lykins, Jr., C. Rav-A cha, and V. Glezer. 2000. Identification of New Drinking Water Disinfection By-products from Ozone, Chlorine Dioxide, Chloramine, and Chlorine. Water, Air, and Soil Pollution , 123: 95-102.

*For more information, contact Susan Richardson at richardson.susan@epa.gov

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