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Objective Telomere length (TL) is a biomarker of biological aging, with shorter telomeres linked to age-related diseases and cancers. The aim of this study is to investigate the association between benzene and TL in a large study population, characterized by a wide range of mostly low exposures.Methods We enrolled 423 workers exposed to benzene and 190 non-exposed referents from three cities of Italy (Genoa, Milan, Cagliari) and one of Bulgaria (Burgas). Exposure to benzene was measured through passive (Italy) and active (Bulgaria) samplers the participants wore near the breathing zone during their work shift. TL was measured through real-time PCR. We applied multivariable mixed-effects models with a random intercept on the city, adjusted by sex, age, smoking, cigarettes/day, and alcohol consumption to evaluate the association between benzene and changes in TL.Results Exposed subjects were selected from occupational categories exposed to low levels of benzene: 144 bus drivers (Genoa), 77 traffic police officers and 76 gas station attendants (Milan), 18 and 180 petrochemical workers (Cagliari and Burgas, respectively). In each city, exposed workers showed higher benzene values than referents, with the highest exposure levels measured among Bulgarian petrochemical workers (median: 0.17 ppm, IQR: 0.44; 1.44). We estimated a 6.9% reduction (95% confidence interval [CI]: -9.5; -4.3) in TL for each 10-fold increase in environmental benzene concentration. A similar pattern was observed in never smokers (-9.48%, 95%CI: -14.10; -4.60) and in the subgroup where urinary benzene was available (-8.27%, 95%CI: -12.34; -4.02).Conclusions Our findings align with existing literature, suggesting that low levels of benzene exposure may accelerate biological aging, and underline the importance of monitoring occupational benzene exposure, even at concentrations below current regulatory limits.