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Use of placental metal and steroid hormone concentrations to assess exposure and effects of tobacco smoking

Introduction: Both first-hand and second-hand tobacco smoke can cause adverse effects on female reproductive integrity and disturbances in the maternal-embryo/foetal-placental functional unit (1). Tobacco smoke contains thousands of harmful chemicals, including 30 metal ions. Women of childbearing age and growing infants are prone to essential element (iron, zinc, copper and/or calcium) deficiencies, and are especially sensitive to toxic-essential metal interactions. Toxic metals can interfere with the maintenance of pregnancy and foetal viability by affecting placental steroid hormones. Smoking is the chief environmental source of cadmium, a toxic metal that has recently been shown to have the potential of an endocrine disrupting chemical (2). Subjects: Healthy urban women (so far analyses have been completed in two cohorts: N=56 and N=208, non-smokers, smokers and previous smokers, average age 28 years) with normal pregnancies and deliveries at term. A physician interviewed the participants after delivery and answers were recorded in a questionnaire form. Methods: Representative pairs of tissue samples (central and peripheral sampling sites) were dissected from each placenta for metal and steroid hormone analyses in relation to exposure to tobacco smoke. Cadmium, lead, iron, zinc, and copper concentrations were analysed using atomic absorption spectrometry, and placental tissue progesterone and oestradiol were assessed using specific imunnoassays (RIA and CLA). Results and Discussion: The increase in placental cadmium is commensurate with the decrease in placental progesterone concentrations in women exposed to tobacco smoke before and/or during pregnancy (3). Cadmium ions accumulate in human placental (trophoblast) cells where they suppress progesterone release without apparent inhibition of syncytial development (4). During pregnancy, toxic metals can compromise foetal health directly in utero by passing the placental barrier, and indirectly, by accumulation in the placenta and by inhibition of nutrient transfer to the foetus. Animal studies support the findings of cadmium-induced placental steroid disruption during pregnancy (3). Conclusion: Assessment of placental function using steroid disruption as an indicator of foetal distress in utero may serve as a useful non-invasive test for evaluating the health risk for the infant posed by prenatal exposure to toxic metals in environmental tobacco smoke. References: 1] Piasek M et al Chapter VI (Ed Fong CB) Smoking and Health Research Frontiers, NY: Nova Publishers 2007: 119-61. 2] Chedrese PJ, Piasek M, Henson MC. Immun Endoc Metab Agents Med Chem 2006 ; 1: 27-35. 3] Piasek M et al Int Arch Occup Environ Health 2002 ; 75: S36-40. 4] Henson MC, Chedrese PJ. Exp Biol Med 2004 ; 29:383-92.

cadmium; human placenta; steroid disruption; tobacco smoking

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