Placental cadmium as an additional noninvasive bioindicator of active maternal tobacco smoking

Tobacco smoke (TS) is a mixture of chemicals that is known to exert carcinogenic and endocrine-disrupting effects, as well as adverse effects on various systems. In TS nicotine is the major alkaloid and cadmium (Cd) the most abundant metal ion. The aim of this investigation was to assess exposure to Cd attributed to TS in healthy postpartum subjects (mean age 28 years) after term vaginal delivery in a clinical hospital by determining metal levels in maternal blood, placenta, and cord blood in relation to nicotine in maternal hair (12-cm-long samples). Two study groups were compared based upon self-reporting data: smokers (n = 32; continual cigarette smoking 3 months before and 9 months during pregnancy) and nonsmokers (n = 54; including passive smokers whose parameters did not differ from unexposed nonsmokers). In smokers compared to nonsmokers maternal hair nicotine concentrations increased approximately sevenfold, while Cd levels rose fourfold in maternal blood and up to twofold in placenta. Significant positive correlations were noted between maternal hair nicotine and placental Cd, maternal hair nicotine and maternal blood Cd, and placental Cd and maternal blood Cd. Levels of cord blood Cd were low in both study groups (<0.1 ng/ml). Data indicate that Cd in placenta may serve as a noninvasive bioindicator in addition to commonly used noninvasive hair nicotine in maternal TS assessment, especially in cases where unavailable or inappropriate (short or chemically treated) hair samples occur.