title: Association between mitochondrial DNA copy number, blood cell counts, and occupational benzene exposure.
abstract: Benzene is a recognized hematotoxicant and carcinogen that produces genotoxic damage. Benzene metabolites can produce reactive oxidative species. Mitochondrial DNA (mtDNA) copy number may be increased in response to oxidative stress to compensate for damaged mitochondria. We carried out a cross-sectional study of 40 benzene-exposed workers and 40 controls to evaluate the association between benzene exposure and mtDNA copy number. Copy number of mtDNA in leukocyte DNA was determined by real-time PCR. Compared with controls, the copy number of mtDNA increased by 4% and by 15% in workers exposed to < or =10 ppm (n = 20) and >10 ppm (n = 20) benzene, respectively. After adjusting for recent infection, the factor that was significantly correlated with mtDNA, the increase of mtDNA was statistically significant in the high exposed group (P = 0.016) with a significant linear trend (P = 0.024). To our best knowledge, this is the first report that benzene exposure was associated with increased mitochondria DNA copy number. Benzene exposure may induce mtDNA amplification, possibly in response to oxidative stress caused by benzene. The finding needs to be replicated by other studies.
authors.affiliation: Division of Cancer Epidemiology and Genetics, NCI, NIH, DHHS, Bethesda, Maryland 20892-7240, USA. shenmi@mail.nih.gov
authors.forename: Min
authors.initials: M
authors.lastname: Shen
authors.forename: Luoping
authors.initials: L
authors.lastname: Zhang
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Bonner
authors.forename: Chin-San
authors.initials: CS
authors.lastname: Liu
authors.forename: Guilan
authors.initials: G
authors.lastname: Li
authors.forename: Roel
authors.initials: R
authors.lastname: Vermeulen
authors.forename: Mustafa
authors.initials: M
authors.lastname: Dosemeci
authors.forename: Songnian
authors.initials: S
authors.lastname: Yin
authors.forename: Qing
authors.initials: Q
authors.lastname: Lan
mesh_terms: D000328:Adult; D001554:Benzene / Q000506:poisoning*; D001772:Blood Cell Count / Q000379:methods*; D003430:Cross-Sectional Studies; D004272:DNA, Mitochondrial / Q000187:drug effects* / Q000235:genetics; D004785:Environmental Pollutants / Q000506:poisoning; D005260:Female; D018628:Gene Dosage; D006801:Humans; D016014:Linear Models; D008297:Male; D009245:NADH Dehydrogenase / Q000235:genetics; D016273:Occupational Exposure / Q000032:analysis*; D016133:Polymerase Chain Reaction
chemical_list: D004272:DNA, Mitochondrial; D004785:Environmental Pollutants; D009245:NADH Dehydrogenase; C515075:NADH dehydrogenase subunit 1, human; D001554:Benzene