Telomere shortening in workers occupationally exposed to a wide range of mostly low benzene levels: a multicenter study

Telomere length (TL) is a biomarker of biological aging, with shorter telomeres linked to age-related diseases and cancers. Benzene, a known carcinogen, may contribute to telomere shortening through oxidative DNA damage and other mechanisms. Previous studies gave conflicting results. The aim of this study is to investigate the association between benzene and TL in a study population characterized by a wide range of mostly low exposure levels. We enrolled 423 workers occupationally exposed to benzene and 190 non-occupationally exposed referents from three cities in Italy and one in Bulgaria. Participants wore passive and active samplers for an entire work shift to measure time-weighted average benzene exposure. TL was measured through real-time PCR. We applied multivariable mixed-effects models with a random intercept on the city, adjusted for sex, age, smoking, cigarettes/day, and alcohol consumption to evaluate the association between benzene and changes in TL. Exposure to environmental benzene ranged from 0.0013 to 21.14 ppm (min-max). For every ten-fold increase in benzene concentrations, TL decreased by 7.4% (95% confidence interval [CI]: -9.9; -4.7). A similar pattern was observed in never-smokers (-10.2%, 95%CI: -14.9; -5.3) and after additional adjustment for toluene (-6.5%, 95%CI: -9.7; -3.2). When data were available, we observed a negative association also between TL and urinary benzene (-5.8%, 95%CI: -8.7; -2.8 for each twofold increase in urinary benzene concentration). Our findings suggest that even low levels of benzene exposure may cause telomere shortening and accelerate biological aging.