Abstract
Manganese (Mn), chromium (Cr) and copper (Cu) are essential elements. However, excessive ingestion of or exposure to these metals may lead to Parkinsonism-like symptoms (Mn), allergic dermatitis, nasal septal perforation and lung cancer (Cr), and Wilson's disease (Cu). Based on the results of studies on time-lapse changes in heavy metal levels in human organs and tissues, changes in metal accumulation have been found to vary with each metal and organ. It is known from measurements of heavy metals in neonates that high levels of heavy metals are transported through the placenta and accumulated in fetuses. Since the occurrence of Minamata disease, attention has been focused on mercury transported through the placenta, mercury levels mainly in the placenta, maternal and umbilical cord blood, and hair. In contrast, only a few reports have concerned the accumulation of heavy metals other than mercury in the umbilical cord. Measurements of heavy metals in maternal and umbilical blood may provide useful information regarding short-term (several days to weeks) or chronic contamination. The umbilical cord, a fetal tissue, is the route through which life-maintaining substances are trans ported from the maternal body. Although contaminants such as heavy metals are directly Measurements of heavy metals in maternal and umbilical blood may provide useful information regarding short-term (several days to weeks) or chronic contamination. The umbilical cord, a fetal tissue, is the route through which life-maintaining substances are trans ported from the maternal body. Although contaminants such as heavy metals are directlyMeasurements of heavy metals in maternal and umbilical blood may provide useful information regarding short-term (several days to weeks) or chronic contamination. The umbilical cord, a fetal tissue, is the route through which life-maintaining substances are trans ported from the maternal body. Although contaminants such as heavy metals are directly accumulated in fetuses through the umbilical cord, they are in part accumulated in the umbilical cord before reaching the fetuses. In Japan, we have the tradition of retaining the dried umbilical cord over a long period of time, and therefore, it is convenient to investigate retro spectively the level of contamination in the umbilical cord. It is also easy to compare different contamination levels over many years. We compared the results of the present study with those obtained previously to investigate the changes over ten years.
