This study investigates the interaction between exposure to environmental polycyclic aromatic hydrocarbons (PAHs) and polymorphisms in DNA repair genes on bulky DNA adducts in human sperm. The researchers measured PAH-DNA adducts in 465 infertile adults using immunofluorescent assay and flow cytometry. They also determined polymorphisms in XPA, XPD, ERCC1, XPF, and XRCC1 genes by PCR and RFLP techniques. Urinary 1-hydroxypyrene (1-OHP) levels were used to assess PAH exposure. Multivariate models adjusted for potential confounders showed that XRCC1 5′pUTR -T/C, Arg194Trp, and Arg399Gln polymorphisms were associated with increased sperm adduct levels. Stratified analysis indicated that the adverse effects of XRCC1 Arg194Trp and Arg399Gln polymorphisms on PAH-DNA adducts were only observed in the high PAH exposure group. These findings suggest that XRCC1 polymorphisms may modify sperm PAH-DNA adduct levels and could serve as biomarkers for identifying individuals susceptible to DNA damage from PAH exposure.This study investigates the interaction between exposure to environmental polycyclic aromatic hydrocarbons (PAHs) and polymorphisms in DNA repair genes on bulky DNA adducts in human sperm. The researchers measured PAH-DNA adducts in 465 infertile adults using immunofluorescent assay and flow cytometry. They also determined polymorphisms in XPA, XPD, ERCC1, XPF, and XRCC1 genes by PCR and RFLP techniques. Urinary 1-hydroxypyrene (1-OHP) levels were used to assess PAH exposure. Multivariate models adjusted for potential confounders showed that XRCC1 5′pUTR -T/C, Arg194Trp, and Arg399Gln polymorphisms were associated with increased sperm adduct levels. Stratified analysis indicated that the adverse effects of XRCC1 Arg194Trp and Arg399Gln polymorphisms on PAH-DNA adducts were only observed in the high PAH exposure group. These findings suggest that XRCC1 polymorphisms may modify sperm PAH-DNA adduct levels and could serve as biomarkers for identifying individuals susceptible to DNA damage from PAH exposure.