Department of Environmental Science and Epidemiology, National Institute for Minamata Disease, Minamata, Japan.
Environ Int. 2013 Oct;60:106-11. doi: 10.1016/j.envint.2013.08.007. Epub 2013 Sep 10.
The role of the placenta was assessed by comparing the profiles of methylmercury (MeHg), inorganic mercury (I-Hg), lead (Pb), cadmium (Cd), selenium (Se), zinc (Zn), and copper (Cu) in freeze-dried chorionic tissue of the placenta and umbilical cord tissue. The significance of the placenta and cord tissue as predictors of prenatal exposure to these trace elements in pregnant women and newborns was also examined by comparing the element profiles among placenta and cord tissue, and maternal and cord blood red blood cells (RBCs). The samples were collected from 48 mother-child pairs at birth in the general population of Japanese. The concentrations of all elements, except for MeHg, were significantly higher in placenta than in cord tissue. In particular, the Cd showed the highest placenta vs. cord tissue ratio (59:1), followed by I-Hg (2.4:1), indicating that the placental barrier works most strongly against Cd among the examined toxic elements. Contrary to the other elements, the MeHg concentration in cord tissue was significantly higher (1.6 times) than that in placenta, indicating its exceptionally high placental transfer. The MeHg in placenta showed significant correlations with total mercury (T-Hg) in maternal and cord RBCs (rs=0.80 and 0.91, respectively). The MeHg in cord tissue also showed significant correlations with T-Hg in maternal and cord RBCs (rs=0.75 and 0.85, respectively). Therefore, both placenta and cord tissue are useful for predicting maternal and fetal exposure to MeHg. The Se concentration in placenta showed significant but moderate correlations with that in maternal and cord RBCs (rs=0.38 and 0.57, respectively). The Pb, Zn, and Cu concentrations in placenta and cord tissue showed no significant correlations with those in maternal and cord RBCs. As an exception, the Cd concentration in placenta showed a moderate but significant correlation (rs=0.41) with that in maternal RBCs, suggesting that the placenta is useful for predicting maternal exposure to Cd during gestation.
胎盘的作用是通过比较冷冻干燥的胎盘绒毛组织和脐带组织中甲基汞（MeHg）、无机汞（I-Hg）、铅（Pb）、镉（Cd）、硒（Se）、锌（Zn）和铜（Cu）的含量来评估的。还通过比较胎盘和脐带组织以及产妇和脐带血红细胞（RBC）中的元素谱来检查胎盘和脐带组织作为预测孕妇和新生儿产前暴露于这些微量元素的指标的意义。这些样本来自日本普通人群中的 48 对母婴。除了 MeHg 之外，所有元素的浓度在胎盘组织中都显著高于脐带组织。特别是，Cd 显示出最高的胎盘与脐带组织比值（59:1），其次是 I-Hg（2.4:1），表明在研究的有毒元素中，胎盘屏障对 Cd 的作用最强。与其他元素相反，脐带组织中的 MeHg 浓度（高 1.6 倍）显著高于胎盘组织，表明其胎盘转移率异常高。胎盘组织中的 MeHg 与产妇和脐带 RBC 中的总汞（T-Hg）呈显著相关（rs=0.80 和 0.91）。脐带组织中的 MeHg 与产妇和脐带 RBC 中的 T-Hg 也呈显著相关（rs=0.75 和 0.85）。因此，胎盘和脐带组织都可用于预测母体和胎儿对 MeHg 的暴露。胎盘组织中的 Se 浓度与产妇和脐带 RBC 中的 Se 浓度呈显著但中度相关（rs=0.38 和 0.57）。胎盘和脐带组织中的 Pb、Zn 和 Cu 浓度与产妇和脐带 RBC 中的浓度无显著相关性。作为例外，胎盘组织中的 Cd 浓度与产妇 RBC 中的 Cd 浓度呈中度但显著相关（rs=0.41），表明胎盘组织可用于预测妊娠期间母体对 Cd 的暴露。
