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Reynoso-Noverón N, Santibáñez-Andrade M, Torres J, Bautista-Ocampo Y, Sánchez-Pérez Y, García-Cuellar CM. Benzene exposure and pediatric leukemia: From molecular clues to epidemiological insights. Toxicol Lett 2024:S0378-4274(24)01099-3. [PMID: 39181343 DOI: 10.1016/j.toxlet.2024.08.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 08/09/2024] [Accepted: 08/21/2024] [Indexed: 08/27/2024]
Abstract
According to the International Agency for Research on Cancer, leukemia ranks 14th in incidence and 11th in mortality and has a 5-year prevalence of approximately 1,300,000 cases. Acute lymphoblastic leukemia is the most common hematopoietic syndrome in children during the first 5 years of life and represents approximately 75% of all neoplasms among the pediatric population. The development of leukemia is strongly governed by DNA alterations that accelerate the growth of bone marrow cells. Currently, the most examined factor in pediatric leukemia is exposure to multiple compounds, such as hydrocarbons. Benzene, an aromatic hydrocarbon, can cause health challenges and is categorized as a carcinogen. Benzene toxicity has been widely associated with occupational exposure. Importantly, studies are underway to generate evidence that can provide clues regarding the risk of environmental benzene exposure and hematological problems in children. In this review, we summarize the existing evidence regarding the effects of benzene on pediatric leukemia, the associations between the effect of benzene on carcinogenesis, and the presence of certain molecular signatures in benzene-associated pediatric leukemia. Although there is sufficient evidence regarding the effects of benzene on carcinogenesis and leukemia, epidemiological research has primarily focused on occupational risk. Moreover, most benzene-induced molecular and cytogenetic alterations have been widely described in adults but not in the pediatric population. Thus, epidemiological efforts are crucial in the pediatric population in terms of epidemiological, clinical, and biomedical research.
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Affiliation(s)
- Nancy Reynoso-Noverón
- Dirección de Investigación, Instituto Nacional de Cancerología, Ciudad de México, Mexico.
| | - Miguel Santibáñez-Andrade
- Instituto Nacional de Cancerología (INCan), Subdirección de Investigación Básica, San Fernando No. 22, Ciudad de México 14080, Mexico
| | - Juan Torres
- Dirección de Investigación, Instituto Nacional de Cancerología, Ciudad de México, Mexico
| | - Yanueh Bautista-Ocampo
- Instituto Nacional de Cancerología (INCan), Subdirección de Investigación Básica, San Fernando No. 22, Ciudad de México 14080, Mexico
| | - Yesennia Sánchez-Pérez
- Instituto Nacional de Cancerología (INCan), Subdirección de Investigación Básica, San Fernando No. 22, Ciudad de México 14080, Mexico
| | - Claudia M García-Cuellar
- Instituto Nacional de Cancerología (INCan), Subdirección de Investigación Básica, San Fernando No. 22, Ciudad de México 14080, Mexico.
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2
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Babigumira R, Veierød MB, Hosgood HD, Samuelsen SO, Bråtveit M, Kirkeleit J, Rothman N, Lan Q, Silverman DT, Friesen MC, Shala NK, Grimsrud TK, Stenehjem JS. Benzene exposure and risk of lung cancer in the Norwegian Offshore Petroleum Worker cohort: a prospective case-cohort study. Occup Environ Med 2023:oemed-2023-109139. [PMID: 38154914 DOI: 10.1136/oemed-2023-109139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 12/11/2023] [Indexed: 12/30/2023]
Abstract
OBJECTIVE The objective of our study was to examine whether occupational exposure to benzene is associated with lung cancer among males in the Norwegian Offshore Petroleum Workers cohort. METHODS Among 25 347 male offshore workers employed during 1965-1998, we conducted a case-cohort study with 399 lung cancer cases diagnosed between 1999 and 2021, and 2035 non-cases sampled randomly by 5-year birth cohorts. Individual work histories were coupled to study-specific job-exposure matrices for benzene and other known lung carcinogens. Weighted Cox regression was used to estimate HRs and 95% CIs for the associations between benzene exposure and lung cancer, by major histological subtypes, adjusted for age, smoking and occupational exposure to welding fumes, asbestos and crystalline silica. Missing data were imputed. RESULTS For lung cancer (all subtypes combined), HRs (95% CIs) for the highest quartiles of benzene exposure versus unexposed were 1.15 (0.61 to 2.35) for cumulative exposure, 1.43 (0.76 to 2.69) for duration, and 1.22 (0.68 to 2.18) for average intensity (0.280≤P-trend≤0.741). For 152 adenocarcinoma cases, a positive trend was observed for exposure duration (P-trend=0.044). CONCLUSIONS In this cohort of offshore petroleum workers generally exposed to low average levels of benzene, we did not find an overall clear support for an association with lung cancer (all subtypes combined), although an association was suggested for duration of benzene exposure and adenocarcinoma. The limited evidence might be due to restricted statistical power.
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Affiliation(s)
- Ronnie Babigumira
- Department of Research, Cancer Registry of Norway, Oslo, Norway
- Oslo Centre for Biostatistics and Epidemiology, Department of Biostatistics, Institute of Basic Medical Sciences, University of Oslo Faculty of Medicine, Oslo, Norway
| | - Marit B Veierød
- Oslo Centre for Biostatistics and Epidemiology, Department of Biostatistics, Institute of Basic Medical Sciences, University of Oslo Faculty of Medicine, Oslo, Norway
| | - H Dean Hosgood
- Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx, New York, USA
| | | | - Magne Bråtveit
- Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway
| | - Jorunn Kirkeleit
- Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway
- Department of Occupational Medicine and Epidemiology, National Institute of Occupational Health (NIOH), Oslo, Norway
| | - Nathaniel Rothman
- Occupational and Environmental Epidemiology, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland, USA
| | - Qing Lan
- Occupational and Environmental Epidemiology, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland, USA
| | - Debra T Silverman
- Occupational and Environmental Epidemiology, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland, USA
| | - Melissa C Friesen
- Occupational and Environmental Epidemiology, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland, USA
| | - Nita Kaupang Shala
- Department of Research, Cancer Registry of Norway, Oslo, Norway
- Oslo Centre for Biostatistics and Epidemiology, Department of Biostatistics, Institute of Basic Medical Sciences, University of Oslo Faculty of Medicine, Oslo, Norway
| | - Tom K Grimsrud
- Department of Research, Cancer Registry of Norway, Oslo, Norway
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Luo H, Chen L, Cui Z, Du J, Yang H, Qiu W, Zhai L, Liang H, Tang H. Poly(ADP-ribose)polymerase-1 affects hydroquinone-induced aberrant cell cycle and apoptosis through activation of p16/pRb signaling pathway in TK6 cells. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2022; 232:113259. [PMID: 35121258 DOI: 10.1016/j.ecoenv.2022.113259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Revised: 01/14/2022] [Accepted: 01/26/2022] [Indexed: 06/14/2023]
Abstract
Hydroquinone (HQ), a key metabolite of benzene, affects cell cycle and apoptosis. Poly (ADP-ribose) polymerase-1 (PARP-1) plays an important role in DNA damage repair. To explore whether PARP-1 is involved in HQ-induced cell cycle and apoptosis, we assessed the effect of PARP-1 suppression and overexpression on induction of cell cycle and apoptosis analyzed by flow cytometry analysis. We observed that HQ induced aberrant cell cycle progression and apoptosis. We further confirmed that PARP-1 suppression accelerated the cell cycle progression and inhibited cell apoptosis via inhibiting p16/pRb signal pathway after acute HQ exposure, while overexpression of PARP-1 displayed the opposite results. Therefore, we concluded that HQ-induced cell cycle and apoptosis were regulated by PARP-1 through activation of p16/pRb signaling pathway.
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Affiliation(s)
- Hao Luo
- Institute of Environmental Health, Dongguan Key Laboratory of Environmental Medicine, School of Public Health, Guangdong Medical University, Dongguan, China
| | - Lin Chen
- Institute of Environmental Health, Dongguan Key Laboratory of Environmental Medicine, School of Public Health, Guangdong Medical University, Dongguan, China
| | - Zheming Cui
- Institute of Environmental Health, Dongguan Key Laboratory of Environmental Medicine, School of Public Health, Guangdong Medical University, Dongguan, China
| | - Jinlin Du
- Institute of Environmental Health, Dongguan Key Laboratory of Environmental Medicine, School of Public Health, Guangdong Medical University, Dongguan, China
| | - Hui Yang
- Institute of Environmental Health, Dongguan Key Laboratory of Environmental Medicine, School of Public Health, Guangdong Medical University, Dongguan, China
| | - Weifeng Qiu
- Institute of Environmental Health, Dongguan Key Laboratory of Environmental Medicine, School of Public Health, Guangdong Medical University, Dongguan, China
| | - Lu Zhai
- Institute of Environmental Health, Dongguan Key Laboratory of Environmental Medicine, School of Public Health, Guangdong Medical University, Dongguan, China
| | - Hairong Liang
- Institute of Environmental Health, Dongguan Key Laboratory of Environmental Medicine, School of Public Health, Guangdong Medical University, Dongguan, China
| | - Huanwen Tang
- Institute of Environmental Health, Dongguan Key Laboratory of Environmental Medicine, School of Public Health, Guangdong Medical University, Dongguan, China.
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Raj A, Nachiappan V. Hydroquinone exposure accumulates neutral lipid by the activation of CDP-DAG pathway in Saccharomyces cerevisiae. Toxicol Res (Camb) 2021; 10:354-367. [PMID: 33884185 DOI: 10.1093/toxres/tfab005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 01/09/2021] [Accepted: 01/17/2021] [Indexed: 11/13/2022] Open
Abstract
Benzene metabolites (HQ and BQ) are toxic compounds and their presence in human cause alteration in cellular respiration and kidney damage. In the current study, Saccharomyces cerevisiae has been used as a model organism and acute exposure of hydroquinone (HQ) decreased cell growth and increased reactive oxygen species (ROS). The expression of apoptosis regulatory genes (YCA1, NUC1, YSP1 and AIF1) were increased with HQ exposure in the wild-type cells. HQ exposure in the wild-type cells altered both the phospholipid and neutral lipid levels. Phosphatidylcholine is a vital membrane lipid that has a vital role in membrane biogenesis and was increased significantly with HQ. The neutral lipid results were supported with lipid droplets data and mRNA expression study. The phospholipid knockouts (Kennedy pathway) accumulated neutral lipids via the CDP-DAG (cytidine-diphosphate-diacylglycerol) pathway genes both in the presence and absence of HQ.
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Affiliation(s)
- Abhishek Raj
- Biomembrane Lab, Department of Biochemistry, School of Life Sciences, Bharathidasan University, Tiruchirappalli 620024, Tamil Nadu, India
| | - Vasanthi Nachiappan
- Biomembrane Lab, Department of Biochemistry, School of Life Sciences, Bharathidasan University, Tiruchirappalli 620024, Tamil Nadu, India
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5
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Key event-informed risk models for benzene-induced acute myeloid leukaemia. Toxicol Lett 2021; 340:141-152. [PMID: 33429013 DOI: 10.1016/j.toxlet.2021.01.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 12/10/2020] [Accepted: 01/04/2021] [Indexed: 11/20/2022]
Abstract
Occupational exposure to benzene at levels of 10 ppm or more has been associated with increased risk of acute myeloid leukaemia (AML). The mode of action (MOA) for AML development leading to mortality is anticipated to include multiple earlier key events, which can be observed in hematotoxicity and genetic toxicity in peripheral blood of exposed workers. Prevention of these early events would lead to prevention of the apical, adverse outcomes, the morbidity and mortality caused by the myelodysplastic syndromes (MDS) and AML. Incorporation of key event information should modify the risk model, but few modification approaches have been suggested. To that end, two approaches to risk model modification are described that use sub-linear and segmented linear increases in risk below key events, while maintaining a linear increase in AML mortality risk beginning at 2 ppm, the lowest observed adverse effect concentration (LOAEC) identified for hemato- and geno- toxicity in high quality studies of human occupational exposure. Below 2 ppm two different modification approaches to quantitative risk models were applied: a continuously decreasing slope model and a segmented modification in slope. These two approaches provide greater flexibility to incorporate MOA information in risk model development and selection.
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Awada H, Thapa B, Visconte V. The Genomics of Myelodysplastic Syndromes: Origins of Disease Evolution, Biological Pathways, and Prognostic Implications. Cells 2020; 9:E2512. [PMID: 33233642 PMCID: PMC7699752 DOI: 10.3390/cells9112512] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 11/16/2020] [Accepted: 11/17/2020] [Indexed: 12/11/2022] Open
Abstract
The molecular pathogenesis of myelodysplastic syndrome (MDS) is complex due to the high rate of genomic heterogeneity. Significant advances have been made in the last decade which elucidated the landscape of molecular alterations (cytogenetic abnormalities, gene mutations) in MDS. Seminal experimental studies have clarified the role of diverse gene mutations in the context of disease phenotypes, but the lack of faithful murine models and/or cell lines spontaneously carrying certain gene mutations have hampered the knowledge on how and why specific pathways are associated with MDS pathogenesis. Here, we summarize the genomics of MDS and provide an overview on the deregulation of pathways and the latest molecular targeted therapeutics.
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Affiliation(s)
- Hassan Awada
- Department of Translational Hematology and Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH 44106, USA;
| | - Bicky Thapa
- Division of Hematology and Oncology, Medical College of Wisconsin, Milwaukee, WI 53226, USA;
| | - Valeria Visconte
- Department of Translational Hematology and Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH 44106, USA;
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7
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Modes of action considerations in threshold expectations for health effects of benzene. Toxicol Lett 2020; 334:78-86. [DOI: 10.1016/j.toxlet.2020.09.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 09/05/2020] [Accepted: 09/10/2020] [Indexed: 01/21/2023]
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8
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Schnatter AR, Rooseboom M, Kocabas NA, North CM, Dalzell A, Twisk J, Faulhammer F, Rushton E, Boogaard PJ, Ostapenkaite V, Williams SD. Derivation of an occupational exposure limit for benzene using epidemiological study quality assessment tools. Toxicol Lett 2020; 334:117-144. [PMID: 32497562 DOI: 10.1016/j.toxlet.2020.05.036] [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: 02/28/2020] [Revised: 05/20/2020] [Accepted: 05/28/2020] [Indexed: 02/04/2023]
Abstract
This paper derives an occupational exposure limit for benzene using quality assessed data. Seventy-seven genotoxicity and 36 haematotoxicity studies in workers were scored for study quality with an adapted tool based on that of Vlaanderen et al., 2008 (Environ Health. Perspect. 116 1700-5). These endpoints were selected as they are the most sensitive and relevant to the proposed mode of action (MOA) and protecting against these will protect against benzene carcinogenicity. Lowest and No- Adverse Effect Concentrations (LOAECs and NOAECs) were derived from the highest quality studies (i.e. those ranked in the top tertile or top half) and further assessed as being "more certain" or "less certain". Several sensitivity analyses were conducted to assess whether alternative "high quality" constructs affected conclusions. The lowest haematotoxicity LOAECs showed effects near 2 ppm (8 h TWA), and no effects at 0.59 ppm. For genotoxicity, studies also showed effects near 2 ppm and showed no effects at about 0.69 ppm. Several sensitivity analyses supported these observations. These data define a benzene LOAEC of 2 ppm (8 h TWA) and a NOAEC of 0.5 ppm (8 h TWA). Allowing for possible subclinical effects in bone marrow not apparent in studies of peripheral blood endpoints, an OEL of 0.25 ppm (8 h TWA) is proposed.
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Affiliation(s)
| | | | | | - Colin M North
- ExxonMobil Biomedical Sciences, Inc, Annandale, NJ, USA
| | | | - Johannes Twisk
- Dow Chemical International Pvt. Ltd, Terneuzen, the Netherlands
| | | | - Erik Rushton
- Basell Service Company B.V., Rotterdam, the Netherlands
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9
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Albertini RJ, Kaden DA. Mutagenicity monitoring in humans: Global versus specific origin of mutations. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2020; 786:108341. [PMID: 33339577 DOI: 10.1016/j.mrrev.2020.108341] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 10/08/2020] [Accepted: 10/14/2020] [Indexed: 01/19/2023]
Abstract
An underappreciated aspect of human mutagenicity biomonitoring is tissue specificity reflected in different assays, especially those that measure events that can only occur in developing bone marrow (BM) cells. Reviewed here are 9 currently-employed human mutagenicity biomonitoring assays. Several assays measure chromosome-level events in circulating T-lymphocytes (T-cells), i.e., traditional analyses of aberrations, translocation studies involving chromosome painting and fluorescence in situ hybridization (FISH) and determinations of micronuclei (MN). Other T-cell assays measure gene mutations. i.e., hypoxanthine-guanine phosphoriboslytransferase (HPRT) and phosphoribosylinositol glycan class A (PIGA). In addition to the T-cell assays, also reviewed are those assays that measure events in peripheral blood cells that necessarily arose in BM cells, i.e., MN in reticulocytes; glycophorin A (GPA) gene mutations in red blood cells (RBCs), and PIGA gene mutations in RBC or granulocytes. This review considers only cell culture- or cytometry-based assays to describe endpoints measured, methods, optimal sampling times, and sample summaries of typical quantitative and qualitative results. However, to achieve its intended focus on the target cells where events occur, kinetics of the cells of peripheral blood that derive at some point from precursor cells are reviewed to identify body sites and tissues where the genotoxic events originate. Kinetics indicate that in normal adults, measured events in T-cells afford global assessments of in vivo mutagenicity but are not specific for BM effects. Therefore, an agent's capacity for inducing mutations in BM cells cannot be reliably inferred from T-cell assays as the magnitude of effect in BM, if any, is unknown. By contrast, chromosome or gene level mutations measured in RBCs/reticulocytes or granulocytes must originate in BM cells, i.e. in RBC or granulocyte precursors, thereby making them specific indicators for effects in BM. Assays of mutations arising directly in BM cells may quantitatively reflect the mutagenicity of potential leukemogenic agents.
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Affiliation(s)
- Richard J Albertini
- University of Vermont, 111 Colchester Avenue, Burlington, VT 05401, United States
| | - Debra A Kaden
- Ramboll US Consulting, Inc., 101 Federal Street, Suite 1900, Boston, MA 02110, United States.
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10
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Yang X, Lu Y, He F, Hou F, Xing C, Xu P, Wang QF. Benzene metabolite hydroquinone promotes DNA homologous recombination repair via the NF-κB pathway. Carcinogenesis 2019; 40:1021-1030. [PMID: 30770924 DOI: 10.1093/carcin/bgy157] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 10/11/2018] [Indexed: 12/29/2022] Open
Abstract
Abstract
Benzene, a widespread environmental pollutant, induces DNA double-strand breaks (DSBs) and DNA repair, which may further lead to oncogenic mutations, chromosomal rearrangements and leukemogenesis. However, the molecular mechanisms underlying benzene-induced DNA repair and carcinogenesis remain unclear. The human osteosarcoma cell line (U2OS/DR-GFP), which carries a GFP-based homologous recombination (HR) repair reporter, was treated with hydroquinone, one of the major benzene metabolites, to identify the potential effects of benzene on DSB HR repair. RNA-sequencing was further employed to identify the potential key pathway that contributed to benzene-initiated HR repair. We found that treatment with hydroquinone induced a significant increase in HR. NF-κB pathway, which plays a critical role in carcinogenesis in multiple tumors, was significantly activated in cells recovered from hydroquinone treatment. Furthermore, the upregulation of NF-κB by hydroquinone was also found in human hematopoietic stem and progenitor cells. Notably, the inhibition of NF-κB activity by small molecule inhibitors (QNZ and JSH-23) significantly reduced the frequency of hydroquinone-initiated HR (−1.36- and −1.77-fold, respectively, P < 0.01). Our results demonstrate an important role of NF-κB activity in promoting HR repair induced by hydroquinone. This finding sheds light on the underlying mechanisms involved in benzene-induced genomic instability and leukemogenesis and may contribute to the larger exploration of the influence of other environmental pollutants on carcinogenesis.
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Affiliation(s)
- Xuejing Yang
- CAS Key Laboratory of Genomic and Precision Medicine, Collaborative Innovation Center of Genetics and Development, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, China
- Key Laboratory of Chemical Safety and Health, National Institute for Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yedan Lu
- Key Laboratory of Chemical Safety and Health, National Institute for Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing, China
- Department of Nutrition, Food Safety and Toxicology, West China School of Public Health, Sichuan University, Chengdu, Sichuan, China
| | - Fuhong He
- CAS Key Laboratory of Genomic and Precision Medicine, Collaborative Innovation Center of Genetics and Development, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, China
| | - Fenxia Hou
- Key Laboratory of Chemical Safety and Health, National Institute for Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Caihong Xing
- Key Laboratory of Chemical Safety and Health, National Institute for Occupational Health and Poison Control, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Peiyu Xu
- Department of Nutrition, Food Safety and Toxicology, West China School of Public Health, Sichuan University, Chengdu, Sichuan, China
| | - Qian-Fei Wang
- CAS Key Laboratory of Genomic and Precision Medicine, Collaborative Innovation Center of Genetics and Development, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
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Gross SA, Paustenbach DJ. Shanghai Health Study (2001-2009): What was learned about benzene health effects? Crit Rev Toxicol 2017; 48:217-251. [PMID: 29243948 DOI: 10.1080/10408444.2017.1401581] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The Shanghai Health Study (SHS) was a large epidemiology study conducted as a joint effort between the University of Colorado and Fudan University in Shanghai, China. The study was funded by members of the American Petroleum Institute between 2001 and 2009 and was designed to evaluate the human health effects associated with benzene exposure. Two arms of the SHS included: an occupational-based molecular epidemiology study and several hospital-based case control studies. Consistent with historical literature, following sufficient exposure to relatively high airborne concentrations and years of exposure, the SHS concluded that exposure to benzene resulted in an increased risk of various blood and bone marrow abnormalities such as benzene poisoning, aplastic anemia (AA), myelodysplastic syndrome (MDS), and acute myeloid leukemia (AML). Non-Hodgkin lymphoma (NHL) was not significantly increased for the exposures examined in this study. Perhaps the most important contribution of the SHS was furthering our understanding of the mechanism of benzene-induced bone marrow toxicity and the importance of identifying the proper subset of MDS relevant to benzene. Investigators found that benzene-exposed workers exhibited bone marrow morphology consistent with an immune-mediated inflammatory response. Contrary to historic reports, no consistent pattern of cytogenetic abnormalities was identified in these workers. Taken together, findings from SHS provided evidence that the mechanism for benzene-induced bone marrow damage was not initiated by chromosome abnormalities. Instead, chronic inflammation, followed by an immune-mediated response, is likely to play a more significant role in benzene-induced disease initiation and progression than previously thought.
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12
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Piper JD, Piper PW. Benzoate and Sorbate Salts: A Systematic Review of the Potential Hazards of These Invaluable Preservatives and the Expanding Spectrum of Clinical Uses for Sodium Benzoate. Compr Rev Food Sci Food Saf 2017; 16:868-880. [PMID: 33371618 DOI: 10.1111/1541-4337.12284] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Revised: 06/08/2017] [Accepted: 06/10/2017] [Indexed: 12/30/2022]
Abstract
Sodium benzoate and potassium sorbate are extremely useful agents for food and beverage preservation, yet concerns remain over their complete safety. Benzoate can react with the ascorbic acid in drinks to produce the carcinogen benzene. A few children develop allergy to this additive while, as a competitive inhibitor of D-amino acid oxidase, benzoate can also influence neurotransmission and cognitive functioning. Model organism and cell culture studies have raised some issues. Benzoate has been found to exert teratogenic and neurotoxic effects on zebrafish embryos. In addition, benzoate and sorbate are reported to cause chromosome aberrations in cultured human lymphocytes; also to be potently mutagenic toward the mitochondrial DNA in aerobic yeast cells. Whether the substantial human consumption of these compounds could significantly increase levels of such damages in man is still unclear. There is no firm evidence that it is a risk factor in type 2 diabetes. The clinical administration of sodium benzoate is of proven benefit for many patients with urea cycle disorders, while recent studies indicate it may also be advantageous in the treatment of multiple sclerosis, schizophrenia, early-stage Alzheimer's disease and Parkinson's disease. Nevertheless, exposure to high amounts of this agent should be approached with caution, especially since it has the potential to generate a shortage of glycine which, in turn, can negatively influence brain neurochemistry. We discuss here how a small fraction of the population might be rendered-either through their genes or a chronic medical condition-particularly susceptible to any adverse effects of sodium benzoate.
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Affiliation(s)
- Joseph D Piper
- Centre for Genomics and Child Health, Blizard Inst., Queen Mary Univ. of London, London, E1 2AT, United Kingdom
| | - Peter W Piper
- Dept. of Molecular Biology and Biotechnology, Univ. of Sheffield, Sheffield, S10 2TN, United Kingdom
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13
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Rangan U, Hedli C, Gallo M, Lioy P, Snyder R. Exposure and Risk Assessment with Respect to Contaminated Soil: Significance of Biomarkers and Bioavailability. Int J Toxicol 2016. [DOI: 10.1080/109158197227044] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
The evaluation of health risk from chemical exposure is evolving in concept and practice. The ability to sensitively detect levels of chemicals in the environment has served as the traditional foundation for determining exposure levels and consequent health risks. More recently, however, other parameters have been constructed to probe the pathway between environmental levels of a chemical and the biological effects of subsequent exposure. Among these, two that are discussed in this paper are bioavailability and biomarker determinations. Chemicals in the environment often are associated with a medium such as airborne particulate, water, or soil. The interaction between the chemical and its medium is dependent on the physicochemical properties of the system. In some cases, such as 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD) in soil, the chemical becomes partially and irreversibly bound to the medium. Animalingestion studies of TCDD-contaminated soil suggest that some of the TCDD remains bound to the soil and does not cross the gastrointestinal barrier during digestion, and therefore only a fraction of the TCDD enters the blood and becomes bioavailable. The characterization of bioavailability provides for more accurate exposure assessment. Biomarker information potentially can validate exposure assessment information from bioavailability studies, elucidate specific biological effects from chemical exposure, and investigate genetic susceptibility issues that may increase the likelihood that an individual or population will experience increased health risks. Benzene-induced chromosome damage is discussed as an example of a significant biomarker that has demonstrated the potential for providing information useful for accurately prediction health risk.
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Affiliation(s)
- Urvashi Rangan
- Department of Pharmacology and Toxicology, 414 EOHSI, 681 Frelinghuysen Road, Piscataway, NJ 08855, USA
| | - Christine Hedli
- Department of Pharmacology and Toxicology, 414 EOHSI, 681 Frelinghuysen Road, Piscataway, NJ 08855, USA
| | - Michael Gallo
- Department of Pharmacology and Toxicology, 414 EOHSI, 681 Frelinghuysen Road, Piscataway, NJ 08855, USA
| | - Paul Lioy
- Department of Pharmacology and Toxicology, 414 EOHSI, 681 Frelinghuysen Road, Piscataway, NJ 08855, USA
| | - Robert Snyder
- Department of Pharmacology and Toxicology, 414 EOHSI, 681 Frelinghuysen Road, Piscataway, NJ 08855, USA
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Gross SA, Fedak KM. Applying a Weight-of-Evidence Approach to Evaluate Relevance of Molecular Landscapes in the Exposure-Disease Paradigm. BIOMED RESEARCH INTERNATIONAL 2015; 2015:515798. [PMID: 26339619 PMCID: PMC4538402 DOI: 10.1155/2015/515798] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2014] [Accepted: 03/16/2015] [Indexed: 12/04/2022]
Abstract
Information on polymorphisms, mutations, and epigenetic events has become increasingly important in our understanding of molecular mechanisms associated with exposures-disease outcomes. Molecular landscapes can be developed to illustrate the molecular characteristics for environmental carcinogens as well as associated disease outcomes, although comparison of these molecular landscapes can often be difficult to navigate. We developed a method to organize these molecular data that uses a weight-of-evidence approach to rank overlapping molecular events by relative importance for susceptibility to an exposure-disease paradigm. To illustrate the usefulness of this approach, we discuss the example of benzene as an environmental carcinogen and myelodysplastic syndrome (MDS) as a causative disease endpoint. Using this weight-of-evidence method, we found overlapping polymorphisms in the genes for the metabolic enzymes GST and NQO1, both of which may infer risk of benzene-induced MDS. Polymorphisms in the tumor suppressor gene, TP53, and the inflammatory cytokine gene, TNF-α, were also noted, albeit inferring opposing outcomes. The alleles identified in the DNA repair gene RAD51 indicated an increased risk for MDS in MDS patients and low blood cell counts in benzene-exposed workers. We propose the weight-of-evidence approach as a tool to assist in organizing the sea of emerging molecular data in exposure-disease paradigms.
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Affiliation(s)
- Sherilyn A. Gross
- Cardno ChemRisk, 4840 Pearl East Circle 300 W., Boulder, CO 80304, USA
| | - Kristen M. Fedak
- Department of Environmental & Radiological Health Sciences, Colorado State University, Fort Collins, CO 80523, USA
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15
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Lymphohematopoietic cancers induced by chemicals and other agents and their implications for risk evaluation: An overview. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2014; 761:40-64. [PMID: 24731989 DOI: 10.1016/j.mrrev.2014.04.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 04/02/2014] [Accepted: 04/03/2014] [Indexed: 12/13/2022]
Abstract
Lymphohematopoietic neoplasia are one of the most common types of cancer induced by therapeutic and environmental agents. Of the more than 100 human carcinogens identified by the International Agency for Research on Cancer, approximately 25% induce leukemias or lymphomas. The objective of this review is to provide an introduction into the origins and mechanisms underlying lymphohematopoietic cancers induced by xenobiotics in humans with an emphasis on acute myeloid leukemia, and discuss the implications of this information for risk assessment. Among the agents causing lymphohematopoietic cancers, a number of patterns were observed. Most physical and chemical leukemia-inducing agents such as the therapeutic alkylating agents, topoisomerase II inhibitors, and ionizing radiation induce mainly acute myeloid leukemia through DNA-damaging mechanisms that result in either gene or chromosomal mutations. In contrast, biological agents and a few immunosuppressive chemicals induce primarily lymphoid neoplasms through mechanisms that involve alterations in immune response. Among the environmental agents examined, benzene was clearly associated with acute myeloid leukemia in humans, with increasing but still limited evidence for an association with lymphoid neoplasms. Ethylene oxide and 1,3-butadiene were linked primarily to lymphoid cancers. Although the association between formaldehyde and leukemia remains controversial, several recent evaluations have indicated a potential link between formaldehyde and acute myeloid leukemia. The four environmental agents examined in detail were all genotoxic, inducing gene mutations, chromosomal alterations, and/or micronuclei in vivo. Although it is clear that rapid progress has been made in recent years in our understanding of leukemogenesis, many questions remain for future research regarding chemically induced leukemias and lymphomas, including the mechanisms by which the environmental agents reviewed here induce these diseases and the risks associated with exposures to such agents.
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16
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Myers NT, Grant SG. The blood-based glycophorin A (GPA) human in vivo somatic mutation assay. Methods Mol Biol 2014; 1105:223-244. [PMID: 24623232 DOI: 10.1007/978-1-62703-739-6_18] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The glycophorin A assay concurrently detects and quantifies erythrocytes with allele-loss phenotypes at the autosomal locus responsible for the polymorphic MN blood group. It uses a pair of allele-specific monoclonal antibodies and flow cytometry to efficiently analyze a standard population of five million cells. Two distinct variant phenotypes are detected: simple allele loss and allele loss followed by reduplication of the remaining allele; both are consistent with the mechanisms underlying "loss of heterozygosity" at tumor-suppressor genes. The assay is an intermediate biomarker of biological effect in the somatic mutational model of human cancer and has been applied to populations with a known or suspected genotoxic exposure, to patients with hereditary syndromes causing predisposition to cancer (where the assay has been applied diagnostically), and to patients manifesting cancer as a disease endpoint.
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Affiliation(s)
- Nicole T Myers
- Department of Pharmaceutical Sciences, Nova Southeastern University, Fort Lauderdale, FL, USA
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17
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Radiation-dose response of glycophorin A somatic mutation in erythrocytes associated with gene polymorphisms of p53 binding protein 1. Mutat Res 2013; 755:49-54. [PMID: 23680719 DOI: 10.1016/j.mrgentox.2013.05.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 05/04/2013] [Accepted: 05/06/2013] [Indexed: 02/07/2023]
Abstract
Information on individual variations in response to ionizing radiation is still quite limited. Previous studies of atomic-bomb survivors revealed that somatic mutations at the glycophorin A (GPA) gene locus in erythrocytes were significantly elevated with radiation exposure dose, and that the dose response was significantly higher in survivors with subsequent cancer development compared to those without cancer development. Noteworthy in these studies were great inter-individual differences in GPA mutant fraction even in persons with similar radiation doses. It is hypothesized that persistent GPA mutations in erythrocytes of atomic-bomb survivors are derived from those in long-lived hematopoietic stem cell (HSC) populations, and that individual genetic backgrounds, specifically related to DNA double-strand break repair, contribute to individual differences in HSC mutability following radiation exposure. Thus, we examined the relationship between radiation exposure, GPA mutant fraction in erythrocytes, and single nucleotide polymorphisms (SNPs) of the key gene involved in DNA double-strand break repair, p53 binding protein 1 (53BP1). 53BP1 SNPs and inferred haplotypes demonstrated a significant interaction with radiation dose, suggesting that radiation-dose response of GPA somatic mutation is partly dependent on 53BP1 genotype. It is also possible that 53BP1 plays a significant role in DNA double-strand break repair in HSCs following radiation exposure.
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18
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Arnold SM, Angerer J, Boogaard PJ, Hughes MF, O'Lone RB, Robison SH, Schnatter AR. The use of biomonitoring data in exposure and human health risk assessment: benzene case study. Crit Rev Toxicol 2013; 43:119-53. [PMID: 23346981 PMCID: PMC3585443 DOI: 10.3109/10408444.2012.756455] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Revised: 11/30/2012] [Accepted: 12/04/2012] [Indexed: 01/08/2023]
Abstract
Abstract A framework of "Common Criteria" (i.e. a series of questions) has been developed to inform the use and evaluation of biomonitoring data in the context of human exposure and risk assessment. The data-rich chemical benzene was selected for use in a case study to assess whether refinement of the Common Criteria framework was necessary, and to gain additional perspective on approaches for integrating biomonitoring data into a risk-based context. The available data for benzene satisfied most of the Common Criteria and allowed for a risk-based evaluation of the benzene biomonitoring data. In general, biomarker (blood benzene, urinary benzene and urinary S-phenylmercapturic acid) central tendency (i.e. mean, median and geometric mean) concentrations for non-smokers are at or below the predicted blood or urine concentrations that would correspond to exposure at the US Environmental Protection Agency reference concentration (30 µg/m(3)), but greater than blood or urine concentrations relating to the air concentration at the 1 × 10(-5) excess cancer risk (2.9 µg/m(3)). Smokers clearly have higher levels of benzene exposure, and biomarker levels of benzene for non-smokers are generally consistent with ambient air monitoring results. While some biomarkers of benzene are specific indicators of exposure, the interpretation of benzene biomonitoring levels in a health-risk context are complicated by issues associated with short half-lives and gaps in knowledge regarding the relationship between the biomarkers and subsequent toxic effects.
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19
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Wang L, He X, Bi Y, Ma Q. Stem Cell and Benzene-Induced Malignancy and Hematotoxicity. Chem Res Toxicol 2012; 25:1303-15. [PMID: 22540379 DOI: 10.1021/tx3001169] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Liping Wang
- Department of Occupational and
Environmental Toxicology, School of Public Health, Wuhan University, Wuhan, China
- Department of Basic Pharmaceutical
Sciences, School of Pharmacy, West Virginia University, Morgantown, West Virginia, United States
| | - Xiaoqing He
- Receptor Biology Laboratory, Toxicology
and Molecular Biology Branch, Health Effects Laboratory Division,
National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown,
West Virginia, United States
| | - Yongyi Bi
- Department of Occupational and
Environmental Toxicology, School of Public Health, Wuhan University, Wuhan, China
| | - Qiang Ma
- Receptor Biology Laboratory, Toxicology
and Molecular Biology Branch, Health Effects Laboratory Division,
National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown,
West Virginia, United States
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20
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McHale CM, Zhang L, Smith MT. Current understanding of the mechanism of benzene-induced leukemia in humans: implications for risk assessment. Carcinogenesis 2012; 33:240-52. [PMID: 22166497 PMCID: PMC3271273 DOI: 10.1093/carcin/bgr297] [Citation(s) in RCA: 207] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Revised: 11/21/2011] [Accepted: 12/07/2011] [Indexed: 01/01/2023] Open
Abstract
Benzene causes acute myeloid leukemia and probably other hematological malignancies. As benzene also causes hematotoxicity even in workers exposed to levels below the US permissible occupational exposure limit of 1 part per million, further assessment of the health risks associated with its exposure, particularly at low levels, is needed. Here, we describe the probable mechanism by which benzene induces leukemia involving the targeting of critical genes and pathways through the induction of genetic, chromosomal or epigenetic abnormalities and genomic instability, in a hematopoietic stem cell (HSC); stromal cell dysregulation; apoptosis of HSCs and stromal cells and altered proliferation and differentiation of HSCs. These effects modulated by benzene-induced oxidative stress, aryl hydrocarbon receptor dysregulation and reduced immunosurveillance, lead to the generation of leukemic stem cells and subsequent clonal evolution to leukemia. A mode of action (MOA) approach to the risk assessment of benzene was recently proposed. This approach is limited, however, by the challenges of defining a simple stochastic MOA of benzene-induced leukemogenesis and of identifying relevant and quantifiable parameters associated with potential key events. An alternative risk assessment approach is the application of toxicogenomics and systems biology in human populations, animals and in vitro models of the HSC stem cell niche, exposed to a range of levels of benzene. These approaches will inform our understanding of the mechanisms of benzene toxicity and identify additional biomarkers of exposure, early effect and susceptibility useful for risk assessment.
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Affiliation(s)
| | | | - Martyn T. Smith
- Division of Environmental Health Sciences, Genes and Environment Laboratory, School of Public Health, University of California, Berkeley, CA 94720-7356, USA
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21
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Hack CE, Haber LT, Maier A, Shulte P, Fowler B, Lotz WG, Savage RE. A Bayesian network model for biomarker-based dose response. RISK ANALYSIS : AN OFFICIAL PUBLICATION OF THE SOCIETY FOR RISK ANALYSIS 2010; 30:1037-51. [PMID: 20412521 DOI: 10.1111/j.1539-6924.2010.01413.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
A Bayesian network model was developed to integrate diverse types of data to conduct an exposure-dose-response assessment for benzene-induced acute myeloid leukemia (AML). The network approach was used to evaluate and compare individual biomarkers and quantitatively link the biomarkers along the exposure-disease continuum. The network was used to perform the biomarker-based dose-response analysis, and various other approaches to the dose-response analysis were conducted for comparison. The network-derived benchmark concentration was approximately an order of magnitude lower than that from the usual exposure concentration versus response approach, which suggests that the presence of more information in the low-dose region (where changes in biomarkers are detectable but effects on AML mortality are not) helps inform the description of the AML response at lower exposures. This work provides a quantitative approach for linking changes in biomarkers of effect both to exposure information and to changes in disease response. Such linkage can provide a scientifically valid point of departure that incorporates precursor dose-response information without being dependent on the difficult issue of a definition of adversity for precursors.
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Affiliation(s)
- C Eric Hack
- Toxicology Excellence for Risk Assessment (TERA), Cincinnati, OH, USA.
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22
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Shiga T, Suzuki H, Yamamoto A, Yamamoto H, Yamamoto K. Hydroquinone, a benzene metabolite, induces Hog1-dependent stress response signaling and causes aneuploidy in Saccharomyces cerevisiae. JOURNAL OF RADIATION RESEARCH 2010; 51:405-415. [PMID: 20467201 DOI: 10.1269/jrr.10014] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Previously, we have shown that phenyl hydroquinone, a hepatic metabolite of the Ames test-negative carcinogen o-phenylphenol, efficiently induced aneuploidy in Saccharomyces cerevisiae by arresting the cell cycle at the G2/M transition as a result of the activation of the Hog1 (p38 MAPK homolog)-Swe1 (Wee1 homolog) pathway. In this experiment, we examined the aneuploidy forming effects of hydroquinone, a benzene metabolite, since both phenyl hydroquinone and hydroquinone are Ames-test negative carcinogens and share similar molecular structures. As was seen in phenyl hydroquinone, hydroquinone induced aneuploidy in yeast by delaying the cell cycle at the G2/M transition. Deficiencies in SWE1 and HOG1 abolished the hydroquinone-induced delay at the G2/M transition and aneuploidy formation. Furthermore, Hog1 was phosphorylated by hydroquinone, which may stabilize Swe1. These data indicate that the hydroquinone-induced G2/M transition checkpoint, which is activated by the Hog1-Swe1 pathway, plays a role in the formation of aneuploidy.
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Affiliation(s)
- Takeki Shiga
- Graduate School of Life Sciences, Tohoku University, Sendai, Japan
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23
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Lau A, Belanger CL, Winn LM. In utero and acute exposure to benzene: Investigation of DNA double-strand breaks and DNA recombination in mice. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2009; 676:74-82. [DOI: 10.1016/j.mrgentox.2009.04.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2008] [Revised: 03/27/2009] [Accepted: 04/01/2009] [Indexed: 11/26/2022]
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24
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Wilbur S, Wohlers D, Paikoff S, Keith LS, Faroon O. ATSDR evaluation of health effects of benzene and relevance to public health. Toxicol Ind Health 2009; 24:263-398. [PMID: 19022880 DOI: 10.1177/0748233708090910] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
As part of its mandate, the Agency for Toxic Substances and Disease Registry (ATSDR) prepares toxicological profiles on hazardous chemicals found at Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) National Priorities List (NPL) sites that have the greatest public health impact. These profiles comprehensively summarize toxicological and environmental information. This article constitutes the release of portions of the Toxicological Profile for Benzene. The primary purpose of this article is to provide public health officials, physicians, toxicologists, and other interested individuals and groups with an overall perspective on the toxicology of benzene. It contains descriptions and evaluations of toxicological studies and epidemiological investigations and provides conclusions, where possible, on the relevance of toxicity and toxicokinetic data to public health.
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Affiliation(s)
- S Wilbur
- Agency for Toxic Substances and Disease Registry (ATSDR), U.S. Department of Health and Human Services, Atlanta, Georgia 30333, USA.
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25
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Westphal GA, Bünger J, Lichey N, Taeger D, Mönnich A, Hallier E. The benzene metabolite para-benzoquinone is genotoxic in human, phorbol-12-acetate-13-myristate induced, peripheral blood mononuclear cells at low concentrations. Arch Toxicol 2009; 83:721-9. [PMID: 19212761 PMCID: PMC3085764 DOI: 10.1007/s00204-009-0402-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2008] [Accepted: 01/15/2009] [Indexed: 10/28/2022]
Abstract
Benzene is one of the most prominent occupational and environmental pollutants. The substance is a proven human carcinogen that induces hematologic malignancies in humans, probably at even low doses. Yet knowledge of the mechanisms leading to benzene-induced carcinogenesis is still incomplete. Benzene itself is not genotoxic. The generation of carcinogenic metabolites involves the production of oxidized intermediates such as catechol, hydroquinone and para-benzoquinone (p-BQ) in the liver. Further activation to the ultimate carcinogenic intermediates is most probably catalyzed by myeloperoxidase (MPO). Yet the products of the MPO pathway have not been identified. If an oxidized benzene metabolite such as p-BQ was actually the precursor for the ultimate carcinogenic benzene metabolite and further activation proceeds via MPO mediated reactions, it should be possible to activate p-BQ to a genotoxic compound in vitro. We tested this hypothesis with phorbol-12-acetate-13-myristate (PMA) activated peripheral blood cells exposed to p-BQ, using the cytokinesis-block micronucleus test. Addition of 20-28 ng/ml PMA caused a significant increase of micronuclei at low and non-cytotoxic p-BQ concentrations between 0.04 and 0.2 microg/ml (0.37-1.85 microM). Thus with PMA or p-BQ alone no reproducible elevation of micronuclei was seen up to toxic concentrations. PMA and p-BQ induce micronuclei when administered jointly. Our results add further support to the hypothesis that MPO is a key enzyme in the activation of benzene.
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Affiliation(s)
- Götz Alexander Westphal
- BGFA, Research Institute of Occupational Medicine, German Social Accident Insurance, Ruhr-University Bochum, 44789 Bochum, Germany.
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26
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Abstract
A large population of humans is exposed to benzene from various occupational and environmental sources. Benzene is an established human and animal carcinogen. Exposure to benzene has been associated with leukaemia in humans and several types of malignancies in animals. The exact mechanism of benzene-induced toxicity is poorly understood. It is believed that benzene exerts its adverse effects by metabolic activation to toxic metabolites. Certain benzene metabolites are genotoxic and mutagenic. This consolidated short-review is composed of human and animal studies to summarize the adverse effects of benzene with special reference to molecular mechanisms involved in benzene-induced toxicity.
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Affiliation(s)
- Haseeb Ahmad Khan
- Department of Biochemistry, College of Science, King Saud University, Riyadh, Saudi Arabia.
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27
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Li G, Yin S. Progress of Epidemiological and Molecular Epidemiological Studies on Benzene in China. Ann N Y Acad Sci 2006; 1076:800-9. [PMID: 17119257 DOI: 10.1196/annals.1371.035] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Benzene is an organic solvent that has been used in industry for about 100 years throughout the world. Since 1973, a series of toxicological and molecular epidemiological studies on benzene were conducted by researchers at the Chinese Academy of Preventive Medicine (CAPM) (1973-1986) and subsequently by a collaboration between the CAPM and the National Cancer Institute (NCI) in the United States that began in 1986, which was joined by investigators from the University of California at Berkeley, the University of North Carolina at Chapel Hill, and New York University. The findings demonstrated that the risk of leukemia and lymphoma among benzene-exposed workers was significantly increased, with elevated risks for leukemia present not only at higher exposure but also among workers exposed to under 10 ppm. Therefore, the benzene permissible level was decreased to 1.8 ppm (6 mg/m(3)) and benzene-induced leukemia is treated as an occupational cancer in China. The benzene permissible level is 1.0 in the United States and in several other developed countries and it has been suggested to be decreased to 0.5 ppm (ACGIH). A number of potential biomarkers are related to benzene exposure and poisoning. Some of these are benzene oxide-protein adducts, chromosome aberration of lymphocytes, and GPA mutations in erythrocytes, a decrease in B cell and CD4(-)T cell counts in peripheral blood, and altered expression of CXCL16, ZNF331, JUN, and PF4 in lymphocytes. Variation in multiple benzene metabolizing genes may be associated with risk of benzene hematotoxicity, including CYP2E1, MPO, NQO1, and GSTT1.
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Affiliation(s)
- Guilan Li
- Institute of Occupational Health and Poison Control, China CDC.
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28
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Nukui T, Day RD, Gordish-Dressman HA, Harger G, Bigbee WL, Ness RB, Romkes M. The absence of interaction between drug metabolizing enzyme genotypes and maternal lifestyle factors on glycophorin A somatic mutation frequency levels in newborns. Pharmacogenet Genomics 2006; 16:129-38. [PMID: 16424825 DOI: 10.1097/01.fpc.0000184954.08453.e1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Prenatal exposure to carcinogens results in newborn DNA damage which in turn is associated with impaired health conditions in both childhood and adulthood. The present study aimed to evaluate whether phase I and II biotransformation enzyme genetic polymorphisms in combination with environmental exposures during pregnancy result in elevated levels of newborn DNA damage. Maternal peripheral and umbilical cord blood samples from 406 mother/newborn pairs were genotyped for a panel of phase I/II metabolic enzymes (CYP1A1, CYP2E1, GSTM1, GSTT1 and NAT2) responsible for the metabolism of tobacco and lifestyle-related mutagens and carcinogens. DNA damage was measured by somatic cell mutation frequency at the glycophorin A (GPA) locus in newborns. No association with elevated somatic cell mutation frequency was observed between the combination of maternal/newborn genotypes and cigarette smoke or lifestyle exposures. The observed variation in newborn GPA frequency might be due to either environmental factors not assessed in this study or inter-individual differences in alternative metabolic or DNA repair pathways.
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Affiliation(s)
- Tomoko Nukui
- Center for Clinical Pharmacology, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15219, USA
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29
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Sommers CH, Schiestl RH. Effect of benzene and its closed ring metabolites on intrachromosomal recombination in Saccharomyces cerevisiae. Mutat Res 2006; 593:1-8. [PMID: 16154601 DOI: 10.1016/j.mrfmmm.2005.06.026] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2005] [Revised: 06/06/2005] [Accepted: 06/06/2005] [Indexed: 05/04/2023]
Abstract
Genome rearrangements, such as DNA deletions, translocations and duplications, are associated with cancer in rodents and humans, and clastogens are capable of inducing such genomic rearrangements. The clastogen benzene and several of its toxic metabolites have been shown to cause cancer in animals. Benzene is associated with leukemia and other blood related disorders in humans. Benzene and metabolites tested negative in short-term bacterial mutation assays such as the Salmonella Mutagenicity Test and the Escherichia coli Tryptophan Reversion Assay. These assays, while reliable for the detection of point-mutagenic carcinogens, are incapable of detecting DNA strand break inducing xenobiotics. The yeast DEL assay is based on intrachromosomal recombination events resulting in deletions and is very sensitive in detecting DNA strand breaks. In previous results the DEL assay detected 17 Salmonella positive as well as 25 Salmonella negative carcinogens [Bishop, Schiestl, Hum. Mol. Genet. 9 (2000) 2427-2434]. The carcinogen benzene and its metabolites including phenol, catechol, p-benzoquinone and hydroquinone induced DEL recombination. The benzene metabolite 1,2,4-benzenetriol was negative. Interestingly, p-benzoquinone induced DEL recombination at a dose 300-fold lower than any of the other metabolites, suggesting that it might be responsible for much of benzene's genotoxicity. In addition, an excision repair deficient strain was used, but no difference was detected compared to the wildtype, indicating that DNA adducts subject to excision repair were not formed by benzene or its metabolites.
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Affiliation(s)
- Christopher H Sommers
- Radiation Biology Unit, Division of Food Safety, USDA, ARS, ERRC, 600 E, Mermaid Lane, Wyndmoor, PA 19038, USA
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30
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Eastmond DA, Mondrala ST, Hasegawa L. Topoisomerase II inhibition by myeloperoxidase-activated hydroquinone: A potential mechanism underlying the genotoxic and carcinogenic effects of benzene. Chem Biol Interact 2005; 153-154:207-16. [PMID: 15935818 DOI: 10.1016/j.cbi.2005.03.024] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Benzene is an established human and animal carcinogen. While many of the key mechanisms underlying its carcinogenic effects remain unknown, there is increasing evidence that chromosomal alterations play an important role in the development of the induced leukemias. Inhibition of enzymes involved in DNA replication and maintenance such as topoisomerases by benzene metabolites represents a potential mechanism by which benzene may induce its chromosome-altering effects. Previous work from our laboratory and others has demonstrated that bioactivated benzene metabolites are capable of inhibiting topoisomerase II (topo II) in isolated enzyme and cell systems as well as in mice administered benzene in vivo. The current studies were designed to build upon this hypothesis, and show that in the presence of human myeloperoxidase and H2O2, hydroquinone can be activated to a potent topo II inhibitor. In the absence of dithiothreitol, partial inhibition can be seen at hydroquinone concentrations as low as 50 nM. The potential role of topo II inhibition in the development of benzene-induced leukemia is also discussed in the context of other known leukemia-inducing agents. Current evidence indicates that multiple mechanisms are likely to contribute to benzene-induced leukemias, and that inhibition of topo II could represent an important step in the development of certain leukemia subtypes.
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Affiliation(s)
- David A Eastmond
- Environmental Toxicology Graduate Program, 5429 Boyce Hall, University of California, Riverside, CA 92521, USA.
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31
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Takaro TK, Engel LS, Keifer M, Bigbee WL, Kavanagh TJ, Checkoway H. Glycophorin A is a potential biomarker for the mutagenic effects of pesticides. INTERNATIONAL JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL HEALTH 2004; 10:256-61. [PMID: 15473078 DOI: 10.1179/oeh.2004.10.3.256] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
For individuals with multiple exposures to bone marrow mutagens the glycophorin A (GPA) assay appears to detect the cumulative genotoxic effects of these nonspecific exposures. To determine whether workers exposed to organophosphates and/or carbamate pesticides have more GPA variants compared with controls, this cross-sectional cohort study examined 67 Latino farm workers, most of whom were exposed to organophosphate or carbamate pesticides, and 68 age-, gender-, ethnicity-, and education-matched reference subjects. Of the 27 participants who completed the questionnaire and had the M/N alleleotype required for the GPA assay, the N/N variant frequency was 9.1 x 10(-6) in the ten subjects with more than 1,500 cumulative hours of exposure vs 3.8 x 10(-6) in the six referent subjects with no known pesticide exposure (p = 0.097). A consistent trend with increasing cumulative exposure was found for N/N and O/N allele-loss frequencies when exposures were stratified into three groups. Despite the small sample size due to the alleleotype restriction, these findings support the hypothesis that some pesticides are mutagenic to hematopoietic stem cells.
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Affiliation(s)
- Tim K Takaro
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, Washington 98105, USA.
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Gaskell M, McLuckie KIE, Farmer PB. Comparison of the mutagenic activity of the benzene metabolites, hydroquinone and para-benzoquinone in the supF forward mutation assay: a role for minor DNA adducts formed from hydroquinone in benzene mutagenicity. Mutat Res 2004; 554:387-98. [PMID: 15450434 DOI: 10.1016/j.mrfmmm.2004.06.032] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2004] [Revised: 05/28/2004] [Accepted: 06/09/2004] [Indexed: 11/16/2022]
Abstract
Benzene, a ubiquitous environmental pollutant and occupational hazardous chemical, is a recognised human leukaemogen and rodent carcinogen. The mechanism by which benzene exerts its carcinogenic effects is to date unknown but it is considered that mutations induced by benzene-DNA adducts may play a role. The benzene metabolite, para-benzoquinone (p-BQ) following reaction in vitro with DNA, forms four major adducts, which include two adducts on 2'-deoxyguanosine 3'-monophosphate (dGp). Reaction of DNA with the benzene metabolite hydroquinone (HQ) results in only one major DNA adduct, which corresponds to one of the dGp adducts formed following reaction with p-BQ. The mutagenicity of the adducts formed from these two benzene metabolites was investigated using the supF forward mutation assay. Metabolite-treated plasmid (pSP189) containing the supF gene was replicated in human Ad293 cells before being screened in indicator bacteria. Treatment with 5-20 mM p-BQ gave a 12 to 40-fold increase in mutation rate compared to 5-20 mM HQ treatment, a result reflected in the level of DNA modification observed (8 to 26-fold increase compared to HQ treatment). Treatment with p-BQ gave equal numbers of GC --> TA transversions and GC --> AT transitions, whereas treatment with HQ gave predominantly GC-->AT transitions. The spectra of mutations achieved for the two individual treatments were shown to be significantly different (P = 0.004). A combination of both treatments also resulted in a high level of GC --> AT transitions and a synergistic increase in the number of multiple mutations, which again predominated as GC --> AT transitions. Sites of mutational hotspots were observed for both individual treatments and one mutational hotspot was observed in the multiple mutations for the combined treatment. These results suggest that the dGp adducts formed from benzene metabolite treatment may play an important role in the mutagenicity and myelotoxicity of benzene.
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Affiliation(s)
- Margaret Gaskell
- Cancer Biomarkers and Prevention Group, The Biocentre, University Road, Leicester LE17RH, UK.
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33
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Abstract
The potential role of genotoxicity in human leukemias associated with benzene (BZ) exposures was investigated by a systematic review of over 1400 genotoxicity test results for BZ and its metabolites. Studies of rodents exposed to radiolabeled BZ found a low level of radiolabel in isolated DNA with no preferential binding in target tissues of neoplasia. Adducts were not identified by 32P-postlabeling (equivalent to a covalent binding index <0.002) under the dosage conditions producing neoplasia in the rodent bioassays, and this method would have detected adducts at 1/10,000th the levels reported in the DNA-binding studies. Adducts were detected by 32P-postlabeling in vitro and following high acute BZ doses in vivo, but levels were about 100-fold less than those found by DNA binding. These findings suggest that DNA-adduct formation may not be a significant mechanism for BZ-induced neoplasia in rodents. The evaluation of other genotoxicity test results revealed that BZ and its metabolites did not produce reverse mutations in Salmonella typhimurium but were clastogenic and aneugenic, producing micronuclei, chromosomal aberrations, sister chromatid exchanges and DNA strand breaks. Rodent and human data were compared, and BZ genotoxicity results in both were similar for the available tests. Also, the biotransformation of BZ was qualitatively similar in rodents, humans and non-human primates, further indicating that rodent and human genotoxicity data were compatible. The genotoxicity test results for BZ and its metabolites were the most similar to those of topoisomerase II inhibitors and provided less support for proposed mechanisms involving DNA reactivity, mitotic spindle poisoning or oxidative DNA damage as genotoxic mechanisms; all of which have been demonstrated experimentally for BZ or its metabolites. Studies of the chromosomal translocations found in BZ-exposed persons and secondary human leukemias produced by topoisomerase II inhibitors provide some additional support for this mechanism being potentially operative in BZ-induced leukemia.
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Affiliation(s)
- John Whysner
- Division of Pathology and Toxicology, American Heath Foundation, 1 Dana Road, Valhalla, NY 10595, USA.
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34
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Albertini R, Clewell H, Himmelstein MW, Morinello E, Olin S, Preston J, Scarano L, Smith MT, Swenberg J, Tice R, Travis C. The use of non-tumor data in cancer risk assessment: reflections on butadiene, vinyl chloride, and benzene. Regul Toxicol Pharmacol 2003; 37:105-32. [PMID: 12662914 DOI: 10.1016/s0273-2300(02)00019-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The estimation and characterization of a cancer risk is grounded in the observation of tumors in humans and/or experimental animals. Increasingly, however, other kinds of data (non-tumor data) are finding application in cancer risk assessment. Metabolism and kinetics, adduct formation, genetic damage, mode of action, and biomarkers of exposure, susceptibility, and effects are examples. While these and other parameters have been studied for many important chemicals over the past 30-40 years, their use in risk assessments is more recent, and new insights and opportunities are continuing to unfold. To provide some perspective on this field, the ILSI Risk Science Institute asked a select working group to characterize the pertinent non-tumor data available for 1,3-butadiene, benzene, and vinyl chloride and to comment on the utility of these data in characterizing cancer risks. This paper presents the findings of that working group and concludes with 15 simple principles for the use of non-tumor data in cancer risk assessment.
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Abstract
Carcinogenesis is a multi-stage and prolonged process. At the present time, our knowledge of biological activities along the process is incomplete, therefore, a variety of experimental data are used to assess health risk from exposure to environmental chemicals. However, experimental approaches may not be adequate unless human data are available to support the assessment. In this brief review, benzene (CAS No. 71-43-2), a well-established human leukemogen, will be used as an example to illustrate the challenge in assessing toxicological mechanisms and cancer risk. Benzene has been shown to form DNA-adducts in experimental animals but the adducts have proved elusive of detection in human. Several toxic metabolites of benzene have been identified but the metabolite(s) responsible for the carcinogenic activities is unknown. Furthermore, the significant differences between rodents and human in response to benzene exposure are not understood. Therefore, the bone marrow specificity for the induction of leukemia in human by benzene remains to be elucidated. These complications illustrate the complexity of the assessment process and identify serious information gaps. These information gaps can be viewed as research opportunities to provide more precise data for assessment of toxicological effects and health risk.
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Affiliation(s)
- William W Au
- Department of Preventive Medicine and Community Health, The University of Texas Medical Branch, 700 Harborside Drive, Galveston, TX 77555-1110, USA.
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36
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Venkatachalam S, Tyner SD, Pickering CR, Boley S, Recio L, French JE, Donehower LA. Is p53 haploinsufficient for tumor suppression? Implications for the p53+/- mouse model in carcinogenicity testing. Toxicol Pathol 2002; 29 Suppl:147-54. [PMID: 11695551 DOI: 10.1080/019262301753178555] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The p53 tumor suppressor gene has been shown to be critical in preventing cancer in humans and mice. We have generated and extensively characterized p53-deficient mice lacking one (p53+/-) or both (p53-/-) p53 alleles. The p53-deficient mice are much more susceptible to an array of different tumor types than their wild-type (p53+/+) littermates. The enhanced tumor susceptibility of the p53+/- mice has made them one of several transgenic mouse models that are being considered as substitutes for standard 2-year rodent carcinogenicity assays. In order to fully exploit this model, it will be important to understand some of the basic biological and molecular mechanisms that underlie its enhanced tumor susceptibility. With this in mind, we have explored the fate of the remaining wild-type p53 allele in spontaneously arising p53+/- tumors and have shown that over half of these tumors retain an intact, functional wild-type p53 allele. This suggests that p53 is haploinsufficient for tumor suppression and that mere reduction in p53 dosage is sufficient to promote cancer formation. To support the idea that p53 is indeed a haploinsufficient tumor suppressor, we show here that normal p53+/- cells exhibit reduced parameters of growth control and stress response compared to their p53+/- counterparts. We hypothesize that the reduced p53 dosage in the p53+/- cells provides an environment more conducive to the development of further oncogenic lesions and the initiation of a tumor. Finally, we have assessed p53 loss of heterozygosity (LOH) in carcinogen-induced p53+/- tumors and have found that some agents induce tumors that almost invariably exhibit p53 LOH, whereas other agents induce tumors that often retain the wild-type p53 allele. Our preliminary data suggest that LOH is dependent on both the mechanism of genotoxicity of the agent utilized and the tissue type targeted.
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Affiliation(s)
- S Venkatachalam
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030, USA
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37
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Hayes RB, Songnian Y, Dosemeci M, Linet M. Benzene and lymphohematopoietic malignancies in humans. Am J Ind Med 2001; 40:117-26. [PMID: 11494338 DOI: 10.1002/ajim.1078] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND Quantitative evaluations of benzene-associated risk for cancer have relied primarily on findings from a cohort study of highly exposed U.S. rubber workers. An epidemiologic investigation in China (NCI/CAPM study) extended quantitative evaluations of cancer risk to a broader range of benzene exposures, particularly at lower levels. METHODS We review the evidence implicating benzene in the etiology of hematopoietic disorders, clarify methodologic aspects of the NCI/CAPM study, and examine the study in the context of the broader literature on health effects associated with occupational benzene exposure. RESULTS Quantitative relationships for cancer risk from China and the U.S. show a relatively smooth increase in risk for acute myeloid leukemia and related conditions over a broad dose range of benzene exposure (below 200 ppm-years mostly from the China study and above 200 ppm-years mostly from the U.S. study). CONCLUSIONS Risks of acute myeloid leukemia and other malignant and nonmalignant hematopoietic disorders associated with benzene exposure in China are consistent with other information about benzene exposure, hematotoxicity, and cancer risk, extending evidence for hematopoietic cancer risks to levels substantially lower than had previously been established. Published 2001 Wiley-Liss, Inc.
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Affiliation(s)
- R B Hayes
- Division of Cancer Epidemiology and Genetics, U.S. National Cancer Institute, Bethesda, Maryland 20892, USA.
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38
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Daniel CP, Fisher A, Parker L, Burn J, Tawn EJ. Individual variation in somatic mutations of the glycophorin-A gene in neonates in relation to pre-natal factors. Mutat Res 2000; 467:153-9. [PMID: 10838202 DOI: 10.1016/s1383-5718(00)00031-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The frequency of somatic mutations of the glycophorin-A (GPA) gene was measured in red blood cells from a series of newborn babies and related to various epidemiological and lifestyle factors in order to identify those factors that might influence the mutation rate before birth. Although there was substantial variation in the mutation frequencies between individual babies, no specific associations were found with any of the factors explored including smoking, age and social class of the parents, and gender and birth weight of the babies. It is concluded that these factors do not have a substantial effect on the mutational endpoint measured, although this does not necessarily mean that they have no effect on health risk to the offspring. The observed variation in GPA gene mutation frequency must, therefore, be due either to exposure to less obvious external influences or to intrinsic factors.
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Affiliation(s)
- C P Daniel
- Genetics Unit, Westlakes Research Institute, Moor Row Cumbria CA24 3JY, UK.
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39
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Cytogenetic abnormalities in the myelodysplastic syndromes and occupational or environmental exposure. Blood 2000. [DOI: 10.1182/blood.v95.6.2093] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Abstract
Patients with myelodysplastic syndromes (MDS) have high frequencies of cytogenetic abnormalities and evidence is accumulating of associations between exposure history and primary MDS. The objective of this article is to examine the relationship between histories of occupational or environmental exposure and presence of cytogenetic abnormalities. A case control study of MDS patients estimated lifetime exposure to more than 90 potential hazards in 400 age, sex, and area of residence matched patient and control pairs. A parallel cytogenetics study undertaken at time of diagnosis, independently of any knowledge of exposure history, identified 75 cytogenetically abnormal and 139 normal (186 not studied). Odds ratios of MDS patients and their matched controls were compared for 3 groups: cytogenetically abnormal, normal, and not known. The odds ratios for all exposures combined were possibly higher among cytogenetically abnormal 2.0 (95% confidence interval 0.8-5.9) than among normal 1.0 (0.6-1.8). This pattern was observed for exposure to semimetals, abnormal 4.0 (0.4-195.1) and normal 0.5 (0.1-1.0) and inorganic dusts, 1.6 (0. 6-3.8) and 0.4 (0.1-1.4) respectively. The pattern was principally in abnormalities in chromosomes 5 and 7. For organic chemicals and radiation, the odds ratios for both cytogenetically abnormal and normal were marginally raised: organic 1.8 (0.6-6.0) and 1.3 (0.6-2.9), respectively, and radiation 1.7 (0.5-5.6) and 1.3 (0.4-4.7) respectively. For radiation, abnormalities were mostly in chromosome 8. This study of association between exposures and cytogenetics in primary MDS complements those previously reported in secondary MDS and may provide some insight into pathogenetic mechanisms that lead to development of MDS.
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40
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Goldman R, Claycamp GH, Sweetland MA, Sedlov AV, Tyurin VA, Kisin ER, Tyurina YY, Ritov VB, Wenger SL, Grant SG, Kagan VE. Myeloperoxidase-catalyzed redox-cycling of phenol promotes lipid peroxidation and thiol oxidation in HL-60 cells. Free Radic Biol Med 1999; 27:1050-63. [PMID: 10569638 DOI: 10.1016/s0891-5849(99)00140-9] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Various types of cancer occur in peroxidase-rich target tissues of animals exposed to aryl alcohols and amines. Unlike biotransformation by cytochrome P450 enzymes, peroxidases activate most substrates by one-electron oxidation via radical intermediates. This work analyzed the peroxidase-dependent formation of phenoxyl radicals in HL-60 cells and its contribution to cytotoxicity and genotoxicity. The results showed that myeloperoxidase-catalyzed redox cycling of phenol in HL-60 cells led to intracellular formation of glutathionyl radicals detected as GS-DMPO nitrone. Formation of thiyl radicals was accompanied by rapid oxidation of glutathione and protein-thiols. Analysis of protein sulfhydryls by SDS-PAGE revealed a significant oxidation of protein SH-groups in HL-60 cells incubated in the presence of phenol/H2O2 that was inhibited by cyanide and azide. Additionally, cyanide- and azide-sensitive generation of EPR-detectable ascorbate radicals was observed during incubation of HL-60 cell homogenates in the presence of ascorbate and H2O2. Oxidation of thiols required addition of H2O2 and was inhibited by pretreatment of cells with the inhibitor of heme synthesis, succinylacetone. Radical-driven oxidation of thiols was accompanied by a trend toward increased content of 8-oxo-7,8-dihydro-2'-deoxyguanosine in the DNA of HL-60 cells. Membrane phospholipids were also sensitive to radical-driven oxidation as evidenced by a sensitive fluorescence HPLC-assay based on metabolic labeling of phospholipids with oxidation-sensitive cis-parinaric acid. Phenol enhanced H2O2-dependent oxidation of all classes of phospholipids including cardiolipin, but did not oxidize parinaric acid-labeled lipids without addition of H2O2. Induction of a significant hypodiploid cell population, an indication of apoptosis, was detected after exposure to H2O2 and was slightly but consistently and significantly higher after exposure to H2O2/phenol. The clonogenicity of HL-60 cells decreased to the same extent after exposure to H2O2 or H2O2/phenol. Treatment of HL-60 cells with either H2O2 or H2O2/phenol at concentrations adequate for lipid peroxidation did not cause a detectable increase in chromosomal breaks. Detection of thiyl radicals as well as rapid oxidation of thiols and phospholipids in viable HL-60 cells provide strong evidence for redox cycling of phenol in this bone marrow-derived cell line.
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Affiliation(s)
- R Goldman
- Department of Environmental & Occupational Health, University of Pittsburgh, PA 15238, USA
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41
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Schoket B, Poirier MC, Mayer G, Török G, Kolozsi-Ringelhann A, Bognár G, Bigbee WL, Vincze I. Biomonitoring of human genotoxicity induced by complex occupational exposures. Mutat Res 1999; 445:193-203. [PMID: 10575430 DOI: 10.1016/s1383-5718(99)00126-6] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Sensitivity, specificity and correlations among several biomarkers for monitoring occupational exposure to complex mixtures of genotoxic agents were assessed in occupational environments in Hungarian study populations. The studies have been focused on DNA adduct formation, urinary metabolites, mutations and micronuclei induced by exposures to complex organic mixtures. In two Hungarian aluminium plants, increased DNA adduct and 1-hydroxypyrene (1-OH-PY) levels were observed in workers as compared to controls. However, no association between the biomarker levels was evident on an individual basis. In Hungarian garage mechanics, DNA adduct determinations did not show increased genotoxic exposure as compared to the controls. However, ambient air measurements, significantly enhanced 1-OH-PY levels, and slightly enhanced frequency of micronuclei indicated increased polycyclic aromatic hydrocarbon (PAH) exposure in the garages, as compared to the general environment. In a Hungarian vulcanizing plant, DNA adduct determinations and 1-OH-PY did not show significantly elevated exposure levels as compared to controls. The glycophorin A (GPA) somatic mutation assay was also negative for this occupational exposure. The results support previous observations of a lack of correlation between DNA adducts detectable by 32P-postlabelling and those measured by the PAH-DNA immunoassay in the same DNA sample. These studies also demonstrate a lack of close correlation between levels of DNA adducts and urinary 1-OH-PY in the same individual.
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Affiliation(s)
- B Schoket
- József Fodor National Center for Public Health, National Institute of Environmental Health, Budapest, Hungary.
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42
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Rothman N, Bechtold WE, Yin SN, Dosemeci M, Li GL, Wang YZ, Griffith WC, Smith MT, Hayes RB. Urinary excretion of phenol, catechol, hydroquinone, and muconic acid by workers occupationally exposed to benzene. Occup Environ Med 1998; 55:705-11. [PMID: 9930093 PMCID: PMC1757513 DOI: 10.1136/oem.55.10.705] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
OBJECTIVES Animal inhalation studies and theoretical models suggest that the pattern of formation of benzene metabolites changes as exposure to benzene increases. To determine if this occurs in humans, benzene metabolites in urine samples collected as part of a cross sectional study of occupationally exposed workers in Shanghai, China were measured. METHODS With organic vapour monitoring badges, 38 subjects were monitored during their full workshift for inhalation exposure to benzene. The benzene urinary metabolites phenol, catechol, hydroquinone, and muconic acid were measured with an isotope dilution gas chromatography mass spectroscopy assay and strongly correlated with concentrations of benzene air. For the subgroup of workers (n = 27) with urinary phenol > 50 ng/g creatinine (above which phenol is considered to be a specific indicator of exposure to benzene), concentrations of each of the four metabolites were calculated as a ratio of the sum of the concentrations of all four metabolites (total metabolites) and were compared in workers exposed to > 25 ppm v < or = 25 ppm. RESULTS The median, 8 hour time weighted average exposure to benzene was 25 ppm. Relative to the lower exposed workers, the ratio of phenol and catechol to total metabolites increased by 6.0% (p = 0.04) and 22.2% (p = 0.007), respectively, in the more highly exposed workers. By contrast, the ratio of hydroquinone and muconic acid to total metabolites decreased by 18.8% (p = 0.04) and 26.7% (p = 0.006), respectively. Similar patterns were found when metabolite ratios were analysed as a function of internal benzene dose (defined as total urinary benzene metabolites), although catechol showed a more complex, quadratic relation with increasing dose. CONCLUSIONS These results, which are consistent with previous animal studies, show that the relative production of benzene metabolites is a function of exposure level. If the toxic benzene metabolites are assumed to be derived from hydroquinone, ring opened products, or both, these results suggests that the risk for adverse health outcomes due to exposure to benzene may have a supralinear relation with external dose, and that linear extrapolation of the toxic effects of benzene in highly exposed workers to lower levels of exposure may underestimate risk.
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Affiliation(s)
- N Rothman
- Occupational Studies Branch, National Cancer Institute, Bethesda, MD, USA.
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43
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van Delft JH, Baan RA, Roza L. Biological effect markers for exposure to carcinogenic compound and their relevance for risk assessment. Crit Rev Toxicol 1998; 28:477-510. [PMID: 9793748 DOI: 10.1080/10408449891344254] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
In this review data are summarized on biomarkers that are used for biological effect monitoring of human populations exposed to genotoxic carcinogens. The biomarkers are DNA and protein adducts and cytogenetic effects. Most of these biomarkers are relevant for the process of carcinogenesis. Emphasis is on providing information on the properties of the biomarkers and on their relevance for predicting cancer risk. Overviews are presented of: (1) studies on effects of exposure in target tissues of human origin obtained by surgical biopsies or autopsies, (2) epidemiological studies on healthy (cancer-free) individuals, correlating the putative occupational, lifestyle or environmental exposure with increased levels of biomarkers in blood cells, and (3) studies with animal models on the relation between biomarkers and cancer. Finally, on the basis of epidemiological data the possibilities were explored to use biomarker data to estimate the risk of death due to cancer. For several biomarkers the increment of the cancer mortality risk was calculated on the basis of a lifetime doubling of the biomarker level.
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Affiliation(s)
- J H van Delft
- TNO Nutrition and Food Research Institute, Toxicology Division, ZEIST, The Netherlands
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44
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Smith MT, Zhang L. Biomarkers of leukemia risk: benzene as a model. ENVIRONMENTAL HEALTH PERSPECTIVES 1998; 106 Suppl 4:937-46. [PMID: 9703476 PMCID: PMC1533331 DOI: 10.1289/ehp.98106s4937] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Although relatively rare, leukemias place a considerable financial burden on society and cause psychologic trauma to many families. Leukemia is the most common cancer in children. The causes of leukemia in adults and children are largely unknown, but occupational and environmental factors are strongly suspected. Genetic predisposition may also play a major role. Our aim is to use molecular epidemiology and toxicology to find the cause of leukemia and develop biomarkers of leukemia risk. We have studied benzene as a model chemical leukemogen, and we have identified risk factors for susceptibility to benzene toxicity. Numerous studies have associated exposure to benzene with increased levels of chromosome aberrations in circulating lymphocytes of exposed workers. Increased levels of chromosome aberrations have, in turn, been correlated with a heightened risk of cancer, especially for hematologic malignancy, in two recent cohort studies in Europe. Conventional chromosome analysis is laborious, however, and requires highly trained personnel. Further, it lacks statistical power, as only a small number of cells can be examined. The recently developed fluorescence in situ hybridization (FISH) and polymerase chain reaction (PCR)-based technologies have allowed the detection of specific chromosome aberrations. These techniques are far less time consuming and are more sensitive than classical chromosomal analysis. Because leukemias commonly show a variety of specific chromosome aberrations, detection of these aberrations by FISH and PCR in peripheral blood may provide improved biomarkers of leukemia risk.
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Affiliation(s)
- M T Smith
- School of Public Health, Division of Environmental Health Sciences, University of California, Berkeley 94720-7360, USA.
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45
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Abstract
A literature review of the impact on human health of exposure to benzene was conducted. Special emphasis in this report is given to the health effects reported in excess of national norms by participants in the Benzene Subregistry of the National Exposure Registry--people having documented exposure to benzene through the use of benzene-contaminated water for domestic purposes. The health effects reported in excess (p < or = .01) by some or all of the sex and age groups studied were diabetes, kidney disease, respiratory allergies, skin rashes, and urinary tract disorders; anemia was also increased for females, but not significantly so.
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Affiliation(s)
- G L Gist
- Exposure and Disease Registry Branch, Agency for Toxic Substances and Disease Registry, U.S. Department of Health and Human Services, Atlanta, GA 30333, USA.
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46
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Schiestl RH, Aubrecht J, Khogali F, Carls N. Carcinogens induce reversion of the mouse pink-eyed unstable mutation. Proc Natl Acad Sci U S A 1997; 94:4576-81. [PMID: 9114032 PMCID: PMC20765 DOI: 10.1073/pnas.94.9.4576] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Deletions and other genome rearrangements are associated with carcinogenesis and inheritable diseases. The pink-eyed unstable (pun) mutation in the mouse is caused by duplication of a 70-kb internal fragment of the p gene. Spontaneous reversion events in homozygous pun/pun mice occur through deletion of a duplicated sequence. Reversion events in premelanocytes in the mouse embryo detected as black spots on the gray fur of the offspring were inducible by the carcinogen x-rays, ethyl methanesulfonate, methyl methanesulfonate, ethyl nitrosourea, benzo[a]pyrene, trichloroethylene, benzene, and sodium arsenate. The latter three carcinogens are not detectable with several in vitro or in vivo mutagenesis assays. We studied the molecular mechanism of the carcinogen-induced reversion events by cDNA analysis using reverse transcriptase-PCR method and identified the induced reversion events as deletions. DNA deletion assays may be sensitive indicators for carcinogen exposure.
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Affiliation(s)
- R H Schiestl
- Department of Molecular and Cellular Toxicology, Harvard School of Public Health, 665 Huntington Avenue, Boston, MA 02115, USA.
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47
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Liu M, Grant SG, Macina OT, Klopman G, Rosenkranz HS. Structural and mechanistic bases for the induction of mitotic chromosomal loss and duplication ('malsegregation') in the yeast Saccharomyces cerevisiae: relevance to human carcinogenesis and developmental toxicology. Mutat Res 1997; 374:209-31. [PMID: 9100845 DOI: 10.1016/s0027-5107(96)00236-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
MultiCASE has the ability to automatically determine the structural features responsible for the biological activity of chemicals. In the present study, 93 chemicals tested for their ability to induce chromosomal 'malsegregation' in the yeast Saccharomyces cerevisiae were analyzed. This 'malsegregation' mimics molecular events that occur during human development and carcinogenesis resulting in an effective loss of one chromosome of an autosomal pair and duplication of the homologue. Structural features associated with the ability to induce such chromosome loss and duplication were identified and compared with those obtained from examination of other toxicological data bases. The most significant structural similarities were identified between the induction of chromosomal malsegregation and several toxicological phenomena such as cellular toxicity, induction of sister chromatid exchanges in vitro and rodent developmental toxicity. Very significant structural similarities were also found with systemic toxicity, induction of micronuclei in vivo and human developmental toxicity. Less significant structural overlaps were found between yeast malsegregation and rodent carcinogenicity, DNA reactivity and mutagenicity, and the induction of chromosome aberrations in vitro and sister chromatid exchanges in vivo. These overlaps may indicate mechanistic similarities between the induction of chromosomal malsegregation and other toxicological phenomena. The predictivity of the SAR model derived from the present data base is relatively low, however. This may be merely a reflection of the small size and composition of the data base, however, further analyses suggest that it reflects primarily the multiple mechanisms responsible for the induction of chromosomal malsegregation in yeast and the complexity of the phenomenon.
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Affiliation(s)
- M Liu
- Department of Environmental and Occupational Health, University of Pittsburgh, PA 15238, USA
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48
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Tsutsui T, Hayashi N, Maizumi H, Huff J, Barrett JC. Benzene-, catechol-, hydroquinone- and phenol-induced cell transformation, gene mutations, chromosome aberrations, aneuploidy, sister chromatid exchanges and unscheduled DNA synthesis in Syrian hamster embryo cells. Mutat Res 1997; 373:113-23. [PMID: 9015160 DOI: 10.1016/s0027-5107(96)00196-0] [Citation(s) in RCA: 104] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Benzene is a human carcinogen present naturally in petroleum and gasoline. For the simultaneous assessment of benzene-induced carcinogenicity and mutagenicity, benzene and its principal metabolites, phenol, catechol and hydroquinone were examined for their ability to induce cell transformation and genotoxic effects using the same mammalian cells in culture. Each of the four compounds induced morphological transformation of Syrian hamster embryo (SHE) cells. Catechol was the most potent, inducing transformation at concentrations of 1-30 microM, followed by hydroquinone (3-30 microM), phenol (10-100 microM) and benzene (only at 100 microM). Gene mutations at two loci in SHE cells were induced by all four compounds, with catechol being the most potent; both ouabain-resistant and 6-thioguanine-resistant mutant frequencies were increased. Chromosomal aberrations in SHE cells were especially induced by catechol, lesser by hydroquinone, and to a marginal extent by phenol at only the 100 microM concentration, whereas sister chromatid exchanges in SHE cells occurred with hydroquinone (1-30 microM), catechol (10-30 microM) and phenol (1000-3000 microM). Aneuploidy in the near diploid range of SHE cells was significantly induced by benzene and catechol. All three metabolites induced unscheduled DNA synthesis in SHE cells, whereas benzene did not. This is the first report that the cell transforming activity and mutagenicity of benzene and its metabolites were assessed with the same mammalian cells in culture. The results provide evidence that benzene and several of its metabolites are cell transforming and genotoxic to cultured mammalian cells.
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Affiliation(s)
- T Tsutsui
- Department of Pharmacology, School of Dentistry at Tokyo, Nippon Dental University, Japan
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Rothman N, Smith MT, Hayes RB, Li GL, Irons RD, Dosemeci M, Haas R, Stillman WS, Linet M, Xi LQ, Bechtold WE, Wiemels J, Campleman S, Zhang L, Quintana PJ, Titenko-Holland N, Wang YZ, Lu W, Kolachana P, Meyer KB, Yin S. An epidemiologic study of early biologic effects of benzene in Chinese workers. ENVIRONMENTAL HEALTH PERSPECTIVES 1996; 104 Suppl 6:1365-1370. [PMID: 9118921 PMCID: PMC1469765 DOI: 10.1289/ehp.961041365] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Benzene is a recognized hematotoxin and leukemogen, but its mechanisms of action in humans are still uncertain. To provide insight into these processes, we carried out a cross-sectional study of 44 healthy workers currently exposed to benzene (median 8-hr time-weighted average; 31 ppm), and unexposed controls in Shanghai, China. Here we provide an overview of the study results on peripheral blood cells levels and somatic cell mutation frequency measured by the glycophorin A (GPA) gene loss assay and report on peripheral cytokine levels. All peripheral blood cells levels (i.e., total white blood cells, absolute lymphocyte count, platelets, red blood cells, and hemoglobin) were decreased among exposed workers compared to controls, with the exception of the red blood cell mean corpuscular volume, which was higher among exposed subjects. In contrast, peripheral cytokine levels (interleukin-3, interleukin-6, erythropoietin, granulocyte colony-stimulating factor, tissue necrosis factor-alpha) in a subset of the most highly exposed workers (n = 11) were similar to values in controls (n = 11), suggesting that benzene does not affect these growth factor levels in peripheral blood. The GPA assay measures stem cell or precursor erythroid cell mutations expressed in peripheral red blood cells of MN heterozygous subjects, identifying NN variants, which result from loss of the GPA M allele and duplication of the N allele, and N phi variants, which arise from gene inactivation. The NN (but not N phi) GPA variant cell frequency was elevated in the exposed workers compared with controls (mean +/- SD, 13.9 +/- 8.4 mutants per million cells versus 7.4 +/- 5.2 per million cells, (respectively; p = 0.0002), suggesting that benzene produces gene-duplicating but not gene-inactivating mutations at the GPA locus in bone marrow cells of exposed humans. These findings, combined with ongoing analyses of benzene macromolecular adducts and chromosomal aberrations, will provide an opportunity to comprehensively evaluate a wide range of early biologic effects associated with benzene exposure in humans.
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Affiliation(s)
- N Rothman
- Division of Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland, USA.
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Smith MT. The mechanism of benzene-induced leukemia: a hypothesis and speculations on the causes of leukemia. ENVIRONMENTAL HEALTH PERSPECTIVES 1996; 104 Suppl 6:1219-25. [PMID: 9118896 PMCID: PMC1469721 DOI: 10.1289/ehp.961041219] [Citation(s) in RCA: 99] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
An overall hypothesis for benzene-induced leukemia is proposed. Key components of the hypothesis include a) activation of benzene in the liver to phenolic metabolites; b) transport of these metabolites to the bone marrow and conversion to semiquinone radicals and quinones via peroxidase enzymes; c) generation of active oxygen species via redox cycling; d) damage to tubulin, histone proteins, topoisomerase II, other DNA associated proteins, and DNA itself; and e) consequent damage including DNA strand breakage, mitotic recombination, chromosome translocations, and aneuploidy. If these effects take place in stem or early progenitor cells a leukemic clone with selective advantage to grow may arise, as a result of protooncogene activation, gene fusion, and suppressor gene inactivation. Epigenetic effects of benzene metabolites on the bone marrow stroma, and perhaps the stem cell itself, may then foster development and survival of the leukemic clone. Evidence for this hypothesis is mounting with the recent demonstration that benzene induces gene-duplicating mutations in human bone marrow and chromosome-specific aneuploidy and translocations in peripheral blood cells. If this hypothesis is correct, it also potentially implicates phenolic and quinonoid compounds in the induction of "spontaneous" leukemia in man.
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Affiliation(s)
- M T Smith
- School of Public Health, University of California, Berkeley 94720-7360, USA.
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