The effects of air pollution and smoking on placental cadmium, zinc concentration and metallothionein expression

This study is designed to determine the placental zinc (Zn) and cadmium (Cd) levels in mothers who were smokers, mothers who were thought to be exposed to air pollution, and mothers who were non-smokers and to investigate the relationship between the expression of placental metallothionein (MT) binding these metals and blood progesterone level. Placental Zn and Cd levels were measured by atomic absorption spectrometry. Presence of placental MT was determined immunohistochemically. Placental changes were examined by light microscope after H&E and PAS staining. Immunohistochernical MT staining of syncytiotrophoblastic and villous interstitial cells were scored as positive or negative. Among the 92 mothers included in the study, 33 were smokers (Group 1), 29 had been exposed to air pollution (Group 11) and 30 were non-smoker rural residents who had never been exposed to air pollution (Group 111). Mean off-spring birth weight of 3198.62 +/- 380.01 g and mean placenta weight of 561.38 +/- 111.55 g of Group 11 were lower when compared with those of other two groups. In Group 1, mean placental Cd and Zn were 0.063 +/- 0.022 mu g/g and 39.84 +/- 15.5 mu g/g, respectively, being higher than in other groups. In Group 11, mean placental Cd and Zn levels were higher than those of Group III. Blood progesterone levels of subjects in Group 1 (121 ng/ml) were the lowest of all groups. While the mean count of villi was the highest in Group 111; the highest mean count of syncytial knots was in Group 11. Thickening of vasculo-syncytial membrane was most prominent in Group 1. Similarly, MT staining was positive and very dense in 72.7% (24/33) of cases in Group I (p <= 0.05). MT staining was positive in 69.0% (29/20) and denser in Group 11 cases compared to 36% (11/30) in Group III (P:5 0.05). This study showed that smoking increased Cd levels in placenta and accompanied an increase in placental NIT expression immunohistochemically. The effects of exposure to air pollution are equally harmful as smoking related effects. (c) 2007 Elsevier Ireland Ltd. All rights reserved.