| Summary: | 碩士 === 國立成功大學 === 環境醫學研究所 === 93 === In 2004, many international institutes released a warning that pregnant women and those who might become pregnant should avoid eating some kinds of fishes because certain fish steaks could contain enough mercury to harm the nervous system of an unborn child. Heavy exposure to mercury in Minamata disease was known to cause severe damage to the nervous system in fetus. In some studies, in utero exposure to background levels of mercury was associated with effects on neurocognitive functioning. Mercury levels in placenta were highly associated with maternal blood and cord blood concentrations, and placental tissue can be regarded as a dual biomarker to assess maternal and fetal exposure. Presently data is lacking on the background exposure in pregnant mothers and fetus, nor the association between mercury exposure and child neurocognitive development. We conducted a study to determine fetal mercury exposure level, and whether such exposure affected child neurocognitive development.
This is a prospective cohort study. A total of 155 mother-and-child pairs were recruited from designated obstetric hospitals from four areas in from July 2001 to January 2003. After mothers’ informed consent, placental tissue was obtained and stored in liquid nitrogen. Placental level of mercury was assayed by cold vapor atomic absorption spectrophotometer (CVAAS). We followed up the children and evaluated their neurocognitive development with Bayley Scales of Infant Development, Second Edition (BSID-II) and Chinese Child Development Inventory (CCDI.) at 12 months to 24 months of age.
The geometric mean of mercury levels in placenta was 17.6 ng/g (geometric standard deviation, GSD=2.4 ng/g). The mercury levels in placenta of male babies were 5.0 ng/g lower than those of female babies. Approximately 71% of mothers reported consuming fish at least a meal in a week, and higher prenatal mercury level was associated with the frequency of mothers’ fish intake. Placental mercury level was not related to that of selenium. BSID-II and CCDI were highly correlated in corresponding items (all r>0.60, p<0.0001). However, BSID-II and CCDI were not associated with prenatal mercury exposure before and after adjusting for potential confounders.
We conclude that in utero exposure to mercury in Taiwan was higher than other developed countries. Fish intake was related to increase placental mercury level. Under the background level we observed, fetal neurocognitive development was not affected.
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