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.