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Wong JYY, Fischer AH, Baris D, Beane Freeman LE, Karagas MR, Schwenn M, Johnson A, Matthews PP, Swank AE, Hosain GM, Koutros S, Silverman DT, DeMarini DM, Rothman N. Urinary mutagenicity and bladder cancer risk in northern New England. Environ Mol Mutagen 2024; 65:47-54. [PMID: 38465801 DOI: 10.1002/em.22588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 01/23/2024] [Accepted: 02/21/2024] [Indexed: 03/12/2024]
Abstract
The etiology of bladder cancer among never smokers without occupational or environmental exposure to established urothelial carcinogens remains unclear. Urinary mutagenicity is an integrative measure that reflects recent exposure to genotoxic agents. Here, we investigated its potential association with bladder cancer in rural northern New England. We analyzed 156 bladder cancer cases and 247 cancer-free controls from a large population-based case-control study conducted in Maine, New Hampshire, and Vermont. Overnight urine samples were deconjugated enzymatically and the extracted organics were assessed for mutagenicity using the plate-incorporation Ames assay with the Salmonella frameshift strain YG1041 + S9. Logistic regression was used to estimate the odds ratios (OR) and 95% confidence intervals (CI) of bladder cancer in relation to having mutagenic versus nonmutagenic urine, adjusted for age, sex, and state, and stratified by smoking status (never, former, and current). We found evidence for an association between having mutagenic urine and increased bladder cancer risk among never smokers (OR = 3.8, 95% CI: 1.3-11.2) but not among former or current smokers. Risk could not be estimated among current smokers because nearly all cases and controls had mutagenic urine. Urinary mutagenicity among never-smoking controls could not be explained by recent exposure to established occupational and environmental mutagenic bladder carcinogens evaluated in our study. Our findings suggest that among never smokers, urinary mutagenicity potentially reflects genotoxic exposure profiles relevant to bladder carcinogenesis. Future studies are needed to replicate our findings and identify compounds and their sources that influence bladder cancer risk.
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Affiliation(s)
- Jason Y Y Wong
- Epidemiology and Community Health Branch, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
- Occupational and Environmental Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, Maryland, USA
| | - Alexander H Fischer
- Occupational and Environmental Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, Maryland, USA
| | - Dalsu Baris
- Occupational and Environmental Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, Maryland, USA
| | - Laura E Beane Freeman
- Occupational and Environmental Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, Maryland, USA
| | - Margaret R Karagas
- Department of Epidemiology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, USA
| | | | | | - Peggy P Matthews
- Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, USA
| | - Adam E Swank
- Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, USA
| | - G Monawar Hosain
- Division of Public Health Services, New Hampshire Department of Health and Human Services, Concord, New Hampshire, USA
| | - Stella Koutros
- Occupational and Environmental Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, Maryland, USA
| | - Debra T Silverman
- Occupational and Environmental Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, Maryland, USA
| | - David M DeMarini
- Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, USA
| | - Nathaniel Rothman
- Occupational and Environmental Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Rockville, Maryland, USA
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Mutlu E, Warren SH, Matthews PP, Schmid JE, Kooter IM, Linak WP, Ian Gilmour M, DeMarini DM. Health effects of soy-biodiesel emissions: bioassay-directed fractionation for mutagenicity. Inhal Toxicol 2015; 27:597-612. [PMID: 26514787 DOI: 10.3109/08958378.2015.1091054] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Revised: 08/18/2015] [Accepted: 09/02/2015] [Indexed: 11/13/2022]
Abstract
CONTEXT Soy biodiesel is the predominant biodiesel in the USA, but there is little understanding of the classes of chemicals responsible for the mutagenicity of its emissions. OBJECTIVE We determined some of the chemical classes responsible for the mutagenicity of the particulate matter (PM) of the emissions from petroleum diesel (B0) and biodiesel containing increasing concentrations of soy methyl esters (B20, B50, and B100). MATERIALS AND METHODS We subjected organic extracts of the PM to bioassay-directed fractionation by sequential elution on silica gel with solvents of increasing polarity to produce four fractions per fuel. We injected these onto high performance liquid chromatography to produce 62 sub-fractions per fraction based on chemical polarity and evaluated all fractions and sub-fractions for mutagenicity in Salmonella. We correlated the results with the concentrations of 32 polycyclic aromatic hydrocarbons (PAHs) in the fractions. RESULTS The mutagenicity-emission factors of the fractions generally decreased with increasing concentrations of soy in the fuel. Despite the different chemical compositions of the fuels, the extractable organics of all four emissions had similar features: ∼60% of the mass was nonpolar, non-mutagenic compounds; most of the PAHs were polar; and most of the mutagenicity was due to weakly polar and polar compounds. Some of the mutagenicity of B20 was due to highly polar compounds. CONCLUSIONS The PM from soy biodiesel emissions was less mutagenic than that from petroleum diesel, and this reduction was associated with reduced concentrations of various weakly polar, polar, and highly polar mutagens, including PAHs, aromatic amines, nitroarenes, and oxy-PAHs.
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Affiliation(s)
- Esra Mutlu
- a National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park , NC , USA
- b Center for Environmental Medicine, Asthma and Lung Biology, University of North Carolina , Chapel Hill , NC , USA
| | - Sarah H Warren
- a National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park , NC , USA
| | - Peggy P Matthews
- a National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park , NC , USA
| | - Judith E Schmid
- a National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park , NC , USA
| | - Ingeborg M Kooter
- c Department of Applied Environmental Chemistry , TNO , Utrecht , The Netherlands , and
| | - William P Linak
- d National Risk Management Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park , NC , USA
| | - M Ian Gilmour
- a National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park , NC , USA
| | - David M DeMarini
- a National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park , NC , USA
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Mutlu E, Warren SH, Matthews PP, King C, Walsh L, Kligerman AD, Schmid JE, Janek D, Kooter IM, Linak WP, Gilmour MI, DeMarini DM. Health effects of soy-biodiesel emissions: mutagenicity-emission factors. Inhal Toxicol 2015; 27:585-96. [PMID: 26514786 DOI: 10.3109/08958378.2015.1080771] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Revised: 07/20/2015] [Accepted: 08/04/2015] [Indexed: 01/18/2023]
Abstract
CONTEXT Soy biodiesel is the predominant biodiesel fuel used in the USA, but only a few, frequently conflicting studies have examined the potential health effects of its emissions. OBJECTIVE We combusted petroleum diesel (B0) and fuels with increasing percentages of soy methyl esters (B20, B50 and B100) and determined the mutagenicity-emission factors expressed as revertants/megajoule of thermal energy consumed (rev/MJ(th)). MATERIALS AND METHODS We combusted each fuel in replicate in a small (4.3-kW) diesel engine without emission controls at a constant load, extracted organics from the particles with dichloromethane, determined the percentage of extractable organic material (EOM), and evaluated these extracts for mutagenicity in 16 strains/S9 combinations of Salmonella. RESULTS Mutagenic potencies of the EOM did not differ significantly between replicate experiments for B0 and B100 but did for B20 and B50. B0 had the highest rev/MJ(th), and those of B20 and B100 were 50% and ∼85% lower, respectively, in strains that detect mutagenicity due to polycyclic aromatic hydrocarbons (PAHs), nitroarenes, aromatic amines or oxidative mutagens. For all strains, the rev/MJ(th) decreased with increasing biodiesel in the fuel. The emission factor for the 16 EPA Priority PAHs correlated strongly (r(2 )= 0.69) with the mutagenicity-emission factor in strain TA100 + S9, which detects PAHs. CONCLUSIONS Under a constant load, soy-biodiesel emissions were 50-85% less mutagenic than those of petroleum diesel. Without additional emission controls, petroleum and biodiesel fuels had mutagenicity-emission factors between those of large utility-scale combustors (e.g. natural gas, coal, or oil) and inefficient open-burning (e.g. residential wood fireplaces).
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Affiliation(s)
- Esra Mutlu
- a National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency , Research Triangle Park , NC , USA
- b Center for Environmental Medicine, Asthma and Lung Biology, University of North Carolina , Chapel Hill , NC , USA
| | - Sarah H Warren
- a National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency , Research Triangle Park , NC , USA
| | - Peggy P Matthews
- a National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency , Research Triangle Park , NC , USA
| | - Charly King
- a National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency , Research Triangle Park , NC , USA
| | - Leon Walsh
- a National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency , Research Triangle Park , NC , USA
| | - Andrew D Kligerman
- a National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency , Research Triangle Park , NC , USA
| | - Judith E Schmid
- a National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency , Research Triangle Park , NC , USA
| | - Daniel Janek
- c National Risk Management Research Laboratory, U.S. Environmental Protection Agency , Research Triangle Park , NC , USA , and
| | - Ingeborg M Kooter
- d Department of Applied Environmental Chemistry , TNO , Utrecht , The Netherlands
| | - William P Linak
- c National Risk Management Research Laboratory, U.S. Environmental Protection Agency , Research Triangle Park , NC , USA , and
| | - M Ian Gilmour
- a National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency , Research Triangle Park , NC , USA
| | - David M DeMarini
- a National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency , Research Triangle Park , NC , USA
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Mutlu E, Warren SH, Matthews PP, King C, Linak WP, Kooter IM, Schmid JE, Ross JA, Gilmour MI, Demarini DM. Bioassay-directed fractionation and sub-fractionation for mutagenicity and chemical analysis of diesel exhaust particles. Environ Mol Mutagen 2013; 54:719-36. [PMID: 24105890 DOI: 10.1002/em.21812] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Revised: 07/31/2013] [Accepted: 07/31/2013] [Indexed: 05/07/2023]
Abstract
Several types of diesel exhaust particles (DEPs) have been used for toxicology studies, including a high-organic automobile DEP (A-DEP) from Japan, and a low-organic forklift DEP developed by the National Institute of Standards and Technology (N-DEP). However, these DEPs were not characterized extensively for chemical composition or sub-fractionated and tested extensively for mutagenicity. We collected a compressor-generated DEP (C-DEP) and characterized it by conducting bioassay-directed fractionation of the extractable organics in Salmonella and correlating the results by hierarchical clustering with the concentrations of 32 polycyclic aromatic hydrocarbons (PAHs). Relative to A- and N-DEP, the mutagenic potency of C-DEP was intermediate in TA100 +S9 (PAH mutagenicity) but was lowest in TA98 -S9 (nitroarene mutagenicity). More than 50% of the mass of the extractable organics of C-DEP eluted in the nonpolar Fraction 1, and only ∼20% eluted in the moderately polar Fractions 2 and 3. However, most of the mutagenicity eluted in Fractions 2 and 3, similar to A-DEP but different from N-DEP. HPLC-derived mutagrams of 62 sub-fractions per fraction confirmed that most of the mutagenicity was due to moderately polar compounds. The diagnostic strains identified a strong role for PAHs, nitroarenes, aromatic amines, and oxy-PAHs in the mutagenicity of C-DEP. Hierarchical clustering confirmed the importance of oxy-PAHs but not that of nitroarenes. To our knowledge this is the first use of hierarchical clustering to correlate chemical composition with the mutagenicity of a complex mixture. The chemical analysis and mutagenicity of C-DEP described here makes C-DEP suitable for additional toxicological studies.
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Affiliation(s)
- Esra Mutlu
- National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina; Center for Environmental Medicine, Asthma and Lung Biology, University of North Carolina, Chapel Hill, North Carolina
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Shaughnessy DT, Gangarosa LM, Schliebe B, Umbach DM, Xu Z, MacIntosh B, Knize MG, Matthews PP, Swank AE, Sandler RS, DeMarini DM, Taylor JA. Inhibition of fried meat-induced colorectal DNA damage and altered systemic genotoxicity in humans by crucifera, chlorophyllin, and yogurt. PLoS One 2011; 6:e18707. [PMID: 21541030 PMCID: PMC3081825 DOI: 10.1371/journal.pone.0018707] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2010] [Accepted: 03/16/2011] [Indexed: 02/03/2023] Open
Abstract
Dietary exposures implicated as reducing or causing risk for colorectal
cancer may reduce or cause DNA damage in colon tissue; however, no one has
assessed this hypothesis directly in humans. Thus, we enrolled 16 healthy
volunteers in a 4-week controlled feeding study where 8 subjects were
randomly assigned to dietary regimens containing meat cooked at either low
(100°C) or high temperature (250°C), each for 2 weeks in a crossover
design. The other 8 subjects were randomly assigned to dietary regimens
containing the high-temperature meat diet alone or in combination with 3
putative mutagen inhibitors: cruciferous vegetables, yogurt, and
chlorophyllin tablets, also in a crossover design. Subjects were nonsmokers,
at least 18 years old, and not currently taking prescription drugs or
antibiotics. We used the Salmonella assay to analyze the
meat, urine, and feces for mutagenicity, and the comet assay to analyze
rectal biopsies and peripheral blood lymphocytes for DNA damage.
Low-temperature meat had undetectable levels of heterocyclic amines (HCAs)
and was not mutagenic, whereas high-temperature meat had high HCA levels and
was highly mutagenic. The high-temperature meat diet increased the
mutagenicity of hydrolyzed urine and feces compared to the low-temperature
meat diet. The mutagenicity of hydrolyzed urine was increased nearly twofold
by the inhibitor diet, indicating that the inhibitors enhanced conjugation.
Inhibitors decreased significantly the mutagenicity of un-hydrolyzed and
hydrolyzed feces. The diets did not alter the levels of DNA damage in
non-target white blood cells, but the inhibitor diet decreased nearly
twofold the DNA damage in target colorectal cells. To our knowledge, this is
the first demonstration that dietary factors can reduce DNA damage in the
target tissue of fried-meat associated carcinogenesis. Trial Registration ClinicalTrials.gov NCT00340743.
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Affiliation(s)
- Daniel T. Shaughnessy
- Laboratory of Molecular Carcinogenesis, National Institute of
Environmental Health Sciences, National Institutes of Health (NIH), Department
of Health and Human Services (DHHS), Research Triangle Park, North Carolina,
United States of America
| | - Lisa M. Gangarosa
- Department of Medicine, School of Medicine, University of North Carolina,
Chapel Hill, North Carolina, United States of America
| | - Barbara Schliebe
- Department of Medicine, School of Medicine, University of North Carolina,
Chapel Hill, North Carolina, United States of America
| | - David M. Umbach
- Biostatistics Branch, National Institute of Environmental Health
Sciences, National Institutes of Health (NIH), Department of Health and Human
Services (DHHS), Research Triangle Park, North Carolina, United States of
America
| | - Zongli Xu
- Epidemiology Branch, National Institute of Environmental Health Sciences,
National Institutes of Health (NIH), Department of Health and Human Services
(DHHS), Research Triangle Park, North Carolina, United States of
America
| | - Beth MacIntosh
- Clinical and Translational Research Center, University of North Carolina,
Chapel Hill, North Carolina, United States of America
| | - Mark G. Knize
- Chemistry, Materials, and Life Sciences Division, Lawrence Livermore
National Laboratory, Livermore, California, United States of America
| | - Peggy P. Matthews
- National Health and Environmental Effects Research Laboratory, U.S.
Environmental Protection Agency, Research Triangle Park, North Carolina, United
States of America
| | - Adam E. Swank
- National Health and Environmental Effects Research Laboratory, U.S.
Environmental Protection Agency, Research Triangle Park, North Carolina, United
States of America
| | - Robert S. Sandler
- Department of Medicine, School of Medicine, University of North Carolina,
Chapel Hill, North Carolina, United States of America
| | - David M. DeMarini
- National Health and Environmental Effects Research Laboratory, U.S.
Environmental Protection Agency, Research Triangle Park, North Carolina, United
States of America
| | - Jack A. Taylor
- Laboratory of Molecular Carcinogenesis, National Institute of
Environmental Health Sciences, National Institutes of Health (NIH), Department
of Health and Human Services (DHHS), Research Triangle Park, North Carolina,
United States of America
- Epidemiology Branch, National Institute of Environmental Health Sciences,
National Institutes of Health (NIH), Department of Health and Human Services
(DHHS), Research Triangle Park, North Carolina, United States of
America
- * E-mail:
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Claxton LD, Matthews PP, Warren SH. The genotoxicity of ambient outdoor air, a review: Salmonella mutagenicity. Mutation Research/Reviews in Mutation Research 2004; 567:347-99. [PMID: 15572287 DOI: 10.1016/j.mrrev.2004.08.002] [Citation(s) in RCA: 126] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2004] [Revised: 08/25/2004] [Accepted: 08/25/2004] [Indexed: 10/26/2022]
Abstract
Mutagens in urban air pollution come from anthropogenic sources (especially combustion sources) and are products of airborne chemical reactions. Bacterial mutation tests have been used for large, multi-site, and/or time series studies, for bioassay-directed fractionation studies, for identifying the presence of specific classes of mutagens, and for doing site- or source-comparisons for relative levels of airborne mutagens. Early research recognized that although carcinogenic PAHs were present in air samples they could not account for the majority of the mutagenic activity detected. The mutagenicity of airborne particulate organics is due to at least 500 identified compounds from varying chemical classes. Bioassay-directed fractionation studies for identifying toxicants are difficult to compare because they do not identify all of the mutagens present, and both the analytical and bioassay protocols vary from study to study. However, these studies show that the majority of mutagenicity is usually associated with moderately polar/highly polar classes of compounds that tend to contain nitroaromatic compounds, aromatic amines, and aromatic ketones. Smog chamber studies have shown that mutagenic aliphatic and aromatic nitrogen-containing compounds are produced in the atmosphere when organic compounds (even non-mutagenic compounds) are exposed to nitrogen oxides and sunlight. Reactions that occur in the atmosphere, therefore, can have a profound effect on the genotoxic burden of ambient air. This review illustrates that the mutagenesis protocol and tester strains should be selected based on the design and purpose of the study and that the correlation with animal cancer bioassay results depends upon chemical class. Future emphasis needs to be placed on volatile and semi-volatile genotoxicants, and on multi-national studies that identify, quantify, and apportion mutagenicity. Initial efforts at replacing the Salmonella assay for ambient air studies with some emerging technology should be initiated.
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Affiliation(s)
- Larry D Claxton
- Cellular Toxicology Branch, Environmental Carcinogenesis Division, US Environmental Protection Agency, Research Triangle Park, NC 27709, USA.
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Kundu B, Richardson SD, Swartz PD, Matthews PP, Richard AM, DeMarini DM. Mutagenicity in Salmonella of halonitromethanes: a recently recognized class of disinfection by-products in drinking water. Mutat Res 2004; 562:39-65. [PMID: 15279829 DOI: 10.1016/j.mrgentox.2004.05.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2004] [Revised: 05/12/2004] [Accepted: 05/13/2004] [Indexed: 10/26/2022]
Abstract
Halonitromethanes (HNMs) are a recently identified class of disinfection by-products (DBPs) in drinking water. They include chloronitromethane (CHN), dichloronitromethane (DCNM), trichloronitromethane (TCNM), bromonitromethane (BNM), dibromonitromethane (DBNM), tribromonitromethane (TBNM), bromochloronitromethane (BCNM),dibromochloronitromethane (DBCNM), and bromodichloronitromethane (BDCNM). Previous studies of TCNM, DCNM, CNM, and TBNM found that all four were mutagenic in bacteria, and a recent study showed that all nine induced DNA damage in CHO cells. Here, all nine HNMs were evaluated in the Salmonella plate-incorporation assay +/- S9 using strains TA98, TA100, TA104, TPT100, and the glutathione transferase theta (GSTT1-1)-expressing strain RSJ100. All were mutagenic, most with and without S9. In the absence of S9, six were mutagenic in TA98, six in TA100, and three in TA104; in the presence of S9, these numbers were five, seven, and three, respectively. Thus, the HNMs-induced base substitutions primarily at GC sites as well as frameshifts. Although five HNMs were activated to mutagens in RSJ100 -S9, they produced < or =2-fold increases in revertants and potencies <506 rev/micromol. The rank order of the HNMs by mutagenic potency in TA100 +S9 was (BCNM DBNM) > (TBNM CNM > BNM DCNM BDCNM) > (TCNM = DBCNM). The mean rev/micromol for the three groupings, respectively, were 1423, 498, and 0, which classifies the HNMs as weak mutagens in Salmonella. Reaction of the dihalo and monohalo HNMs with GSH, possibly GSTT1-1, is a possible mechanism for formation of ultimate mutagenic products. Because the HNMs are mutagenic in Salmonella (present study) and potent clastogens in mammalian cells [Environ. Sci. Technol. 38 (2004) 62], their presence in drinking water warrants further research on their potential health effects.
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Affiliation(s)
- Bijit Kundu
- Department of Environmental Science and Engineering, University of North Carolina, Chapel Hill, NC 27599, USA
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