Trasplacental exposure to tobacco smoke and its genotoxic effect

Abstract

Exposure to pollutants continues to be a hot topic as the introduction and use of chemicals is continuously increasing with society modernization. Although this affects the entire human population, increased vulnerability towards in utero carcinogenic exposures has been proposed due to a high rate of cell proliferation, relatively high numbers of target cells at risk, altered ability to repair DNA damage, immaturity of metabolism, endocrine immunological systems and longer life span ahead in which to develop chronic disease as compared with adults. In this context, the analysis of transplacental exposure to different chemicals using either cord blood or placenta has captured the attention of researchers in the last decade culminating in the study of the possible effects of environmental pollutants on infants and mothers’ health using DNA adducts micronuclei, DNA damage and epigenetic alterations. The main goal of this study was to analyze the effect of exposure to tobacco smoke during pregnancy in the levels of DNA damage evaluated in cord blood samples using the alkaline comet assay. The influence of other environmental pollutants, namely, mercury was also considered as the population enrolled in the study was resident in Aveiro district (previously studied for its mercury levels). A total of 53 women were enrolled in the study at the time of hospital admission for delivery. Smoking status was established on the basis of cotinine concentrations analyzed in maternal plasma by ELISA. Exposure to Hg was assessed by analysis of umbilical cord samples using atomic absorption after thermal decomposition (direct combustion). Results obtained showed that there was no statistically significant association between observed DNA damage and tobacco smoke exposure or Hg levels. However, the median cotinine value was below 1 ng/mL indicating low exposure to this environmental pollutant. After data discretization, an increase in DNA damage levels was associated to cotinine increases but as the number of individuals included in each class is very low, further studies on this matter are needed. To the public health sector, these data constitutes a significant contribution to improve knowledge on the effects of tobacco smoke exposure and to support the implementation of measures that may reduce the negative health impact of tobacco smoke, particularly during pregnancy.