Murata Katsuyuki, Dakeishi Miwako, Shimada Miyuki, Satoh Hiroshi
Department of Environmental Health Sciences, Akita University School of Medicine, Japan.
Nihon Eiseigaku Zasshi. 2007 Sep;62(4):949-59. doi: 10.1265/jjh.62.949.
In epidemiological studies on the health effect of methylmercury (MeHg) exposure, maternal-hair mercury concentration has been used as an exposure biomarker because of its ease of collection and capability to recapture the exposure history. However, artificial hair-waving reduces the mercury concentration and there is little agreement about which part of the hair strand properly represents fetal exposure. We presented an overview of the studies addressing umbilical cord and mercury in PubMed and evaluated the usefulness of umbilical cord mercury concentrations as biomarkers of fetal exposure to MeHg. The mean total mercury (T-Hg) concentration in cord blood was between 0.5 and 35.6microg/l, and the cord blood-to-maternal blood ratio of T-Hg concentrations was estimated to be approximately 1.5. MeHg concentrations in dried cord tissue did not exceed 0.4 microg/g in Japanese populations without particular exposure to MeHg. Dried cord tissue appeared to be better than wet tissue because the definition of wet weight of the umbilical cord is ambiguous. Both cord-blood and cord-tissue mercury concentrations seemed to correlate closely with maternal-hair and maternal-blood ones. Since cord mercury concentrations are a direct exposure biomarker of the fetus and the cord blood-to-maternal blood ratio of mercury differed markedly among mother-child pairs, mercury concentration in cord blood or dried cord tissue should therefore be used in assessing the possible effects of fetal exposure to MeHg on the susceptible brain. Further studies are required to clarify at which period of exposure during gestation the cord mercury concentration represents in relation to mercury concentrations in maternal segmental hair.
在关于甲基汞（MeHg）暴露对健康影响的流行病学研究中，由于母体头发汞浓度易于采集且能够反映暴露历史，因此一直被用作暴露生物标志物。然而，人工烫发来降低汞浓度，并且对于头发的哪一部分能正确代表胎儿暴露情况，人们的意见很少一致。我们在PubMed上概述了有关脐带和汞的研究，并评估了脐带汞浓度作为胎儿暴露于MeHg的生物标志物的有用性。脐血中的平均总汞（T-Hg）浓度在0.5至35.6微克/升之间，T-Hg浓度的脐血与母体血液比率估计约为1.5。在没有特别暴露于MeHg的日本人群中，干燥脐带组织中的MeHg浓度不超过0.4微克/克。干燥脐带组织似乎比湿组织更好，因为脐带湿重的定义不明确。脐带血和脐带组织中的汞浓度似乎都与母体头发和母体血液中的汞浓度密切相关。由于脐带汞浓度是胎儿的直接暴露生物标志物，并且汞的脐血与母体血液比率在母婴对之间差异显著，因此在评估胎儿暴露于MeHg对易感大脑的可能影响时，应使用脐血或干燥脐带组织中的汞浓度。需要进一步研究以阐明在妊娠期间的哪个暴露期，脐带汞浓度与母体分段头发中的汞浓度相关。
