In this study, we attempted to relate the variation of heavy metals in the maternal blood and placental tissues of our participants to a number of demographic, socioeconomic and environmental factors. It should be noted here that the final multiple regression models did not explain most of the variations in blood or placental tissues of lead, cadmium or mercury. This suggests that there were other important sources of exposure for these women that were not included in the study. Furthermore, a number of variables were important predictors in the final models of lead, cadmium and mercury in either blood or placental tissues, which we cannot adequately explain. It is possible that examination of a large number of variables created spurious chance. Therefore, in the subsequent section, we shall; therefore, discuss significant findings only.
Cord lead levels, maternal cadmium levels, smoking status and living in the central area of Al-Kharj were the main predictors in the final maternal blood lead regression model. Cord blood lead levels confirm that lead can easily pass through the placenta barrier as discussed before and maternal lead levels provide a reliable measure of fetal lead exposure. To reduce lead exposure and avoid its health consequences on fetus, it might be feasible to measure women blood lead levels before pregnancy occurs or/and within the first three months of pregnancy. Another observation was maternal cadmium in the blood seems to be influenced by blood lead levels in mothers environmentally exposed to lead. Similar observation was seen in animal studies conducted by Patra et al. (2006) and Gyõri et al. (2005). Concurrent exposure to lead, cadmium or other heavy metals may produce additive or synergistic intera...
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...etention. Metallothioein plays a critical role in protecting human health from cadmium toxicity though with large individual variations in its expression (Klaassen et al., 2009). Without metallothionein, normal levels of cadmium exposure would be nephrotoxic to humans (Klaassen et al., 1999). It seems that placental mercury exposure was also affected negatively by other factors such mother’s education levels and the application of henna on hands during pregnancy.
In summary, this first study provides informative baseline biomonitoring data and reveals a substantial exposure to heavy metals in Saudi non-occupationally exposed mothers and their newborns that might jeopardize the health of both. Preventative measures based on maternal risk assessment program are needed to eliminate or minimize unnecessary risk of fetus exposure to heavy metals or other pollutants.