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Vermeulen R, Lan Q, Qu Q, Linet MS, Zhang L, Li G, Portengen L, Vlaanderen J, Sungkyoon K, Hayes RB, Yin S, Smith MT, Rappaport SM, Rothman N. Nonlinear low dose hematotoxicity of benzene; a pooled analyses of two studies among Chinese exposed workers. Environ Int 2023; 177:108007. [PMID: 37290291 DOI: 10.1016/j.envint.2023.108007] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2022] [Revised: 05/23/2023] [Accepted: 05/29/2023] [Indexed: 06/10/2023]
Abstract
BACKGROUND Impairment of the hematopoietic system is one of the primary adverse health effects from exposure to benzene. We previously have shown that exposure to benzene at low levels (<1 ppm) affects the blood forming system and that these effects were proportionally stronger at lower versus higher levels of benzene exposure. This observation is potentially explained by saturation of enzymatic systems. METHODS Here we extend these analyses by detailed modeling of the exposure response association of benzene and its major metabolites (i.e. catechol, muconic acid, phenol, and hydroquinone) on peripheral white blood cell (WBC) counts and its major cell-subtypes (i.e. granulocytes, lymphocytes, and monocytes) using two previously published cross-sectional studies among occupationally exposed Chinese workers. RESULTS Supra-linear exposure response associations were observed between air benzene concentrations (range ∼ 0.1 - 100 ppm) and WBC counts and its cell-subtypes, with a larger than proportional decrease in cell counts at lower than at higher levels of benzene exposure. The hematotoxicity associations were largely similar in shape when the analyses were repeated with benzene urinary metabolites suggesting that enzymatic saturation is not a full explanation of the observed non-linearity with WBC endpoints. DISCUSSION We hypothesize that the flattening of the exposure response curve especially at higher benzene exposure levels may reflect a response by the bone marrow to maintain hematopoietic homeostasis. Toxicity to the bone marrow and an induced hyper-proliferative response could both contribute to risk of subsequently developing a hematopoietic malignancy. Additional work is needed to explore this hypothesis.
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Affiliation(s)
- Roel Vermeulen
- Institute for Risk Assessment Sciences, Utrecht University, Utrecht, the Netherlands
| | - Qing Lan
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, DHHS, Bethesda, MD 20892, United States
| | - Qingshan Qu
- Nelson Institute of Environmental Medicine, New York University School of Medicine, Tuxedo, NY, United States
| | - Martha S Linet
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, DHHS, Bethesda, MD 20892, United States
| | - Luoping Zhang
- School of Public Health, University of California, Berkeley, CA 94720, United States
| | - Guilan Li
- Chinese Center for Disease Control and Prevention, Beijing, China
| | - Lutzen Portengen
- Institute for Risk Assessment Sciences, Utrecht University, Utrecht, the Netherlands
| | - Jelle Vlaanderen
- Institute for Risk Assessment Sciences, Utrecht University, Utrecht, the Netherlands
| | - Kim Sungkyoon
- School of Public Health, Seoul National University, Seoul, Republic of Korea
| | | | - Songnian Yin
- Chinese Center for Disease Control and Prevention, Beijing, China
| | - Martyn T Smith
- School of Public Health, University of California, Berkeley, CA 94720, United States
| | - Stephen M Rappaport
- School of Public Health, University of California, Berkeley, CA 94720, United States
| | - Nathaniel Rothman
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, DHHS, Bethesda, MD 20892, United States
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