Exposure to polycyclic aromatic hydrocarbons and nicotine, and associations with sperm DNA fragmentation

Background: Tobacco smoking has been reported to cause DNA fragmentation and has been suggested to cause mutations in spermatozoa. These effects have been ascribed to the action of polycyclic aromatic hydrocarbons (PAH) present in the smoke. Simultaneously, DNA fragmentation has been associated with mutagenesis. Objective: The aim of this study was to investigate whether levels of urinary biomarkers of PAH and nicotine exposure were associated with sperm DNA fragmentation. Methods: In the urine of 381 men recruited from two cohorts of young men (17–21 years old) from the general Swedish population, the PAH metabolites 1-hydroxypyrene and 2-hydroxyphenanthrene, as well as the nicotine metabolite cotinine, were measured. The sperm DNA fragmentation index (DFI) was analysed using the sperm chromatin structure assay. Associations between the DFI, and PAH metabolite levels as continuous variables as well as in quartiles, were studied by general linear models adjusted for abstinence time. A similar analysis was carried out for cotinine levels, according to which the men were categorised as “non-smoking” (n = 216) and “smoking” (n = 165). Results: No association was found between levels of any of the three biomarkers and DFI, either as a continuous variable (p = 0.87–0.99), or when comparing the lowest and the highest quartiles (p = 0.11–0.61). The same was true for comparison of men categorised as non-smoking or smoking (DFI 11.1% vs. 11.8%, p = 0.31). Discussion: We found no evidence of PAH or nicotine exposure to be associated with DFI, which does not exclude that these exposures may have other effects on sperm DNA. Conclusion: In these young men, levels of biomarkers of nicotine and PAH exposure were not associated with DFI.