Exposure to Environmental Tobacco Smoke in Pregnancy and Lead Level in Maternal Blood at Delivery
International Journal of Occupational Medicine and Environmental Health
Objectives: The particular purpose of our study was to assess the impact of environmental tobacco smoke (ETS) on the individual variability of blood lead levels in pregnant women as earlier publications demonstrated the increased blood lead in smokers. Materials and Methods: The material consisted of 240 pregnant women who participated in a prospective cohort study on vulnerability of the fetus and infant to environmental hazards. The enrolment included only non-smoking women with singleton
... nancies between the ages of 18-35 years. Whole blood lead concentrations were determined using inductively coupled plasma mass spectrometry. Results: On average, blood-lead measured in pregnant women at delivery was low (GM = 1.7 mg/dL; 95% CI:1.6-1.8 mg/dL) and none of them showed levels above 4.0 mg/dL, but persons reporting exposure to ETS had significantly higher blood lead level (GM = 1.9 mg/dL; 95%CI:1.8-2.1 mg/dL) than those free from this exposure (GM = 1.6 mg/dL; 95%CI:1.5-1.7 mg/dL). In order to single out the effect of the ETS exposure from the confounding variables, we used the stepwise multivariate linear regression for log blood-lead in maternal blood as dependent variable and a set of independent variables, such as age, weight of women before pregnancy and their education level. The results of the analysis showed that all the independent variables included in the model explained 11% of total blood-lead variability among the study women. The strongest component of variance was attributed to ETS exposure (5%), age (3%), education level (2%) and weight (1%). Inclusion into the model of other variables, e.g., residence area and traffic intensity did not improve the proportion of explained variability. Conclusions: The reason for higher levels of blood-lead in the ETS-exposed women may result from the fact that tobacco smoke contains lead. However, it is possible that inhaled tobacco smoke also increases the absorption of lead from particulate matter deposited in the bronchial tree.