Transplacental exposure to tobacco smoke in human-adduct formation in placenta and umbilical cord blood vessels.

Smokers are exposed to a large number of genotoxic compounds that react with DNA to form covalently bound carcinogen-DNA adducts after metabolic conversion to their biological active form. Using the P32-postlabeling techniques, tobacco smoke related carcinogen--DNA adducts have been demonstrated in DNA isolated from human placenta and umbilical cord vein and artery obtained from 11 nonsmoking and 8 smoking normal healthy women and foetuses. The adduct level was significantly higher in tissues from smokers than from nonsmokers (P = 0.021), when all tissues were combined. Furthermore, the total adduct level was higher in maternal tissue than the level in fetal tissues (P = 0.030). The adduct level in umbilical cord vein DNA was significantly lower than in placenta, and marginally lower than in umbilical cord artery from the same donor. This suggests that the foetus can metabolise some of the genotoxic compounds found in tobacco smoke to DNA-binding metabolites. The presence of DNA adducts in foetal tissues is indicative of potential genomic damage, that may result in an increased risk for the development of serious diseases, like cancer in childhood or later during the life span of the individual.