| Background & ObjectiveChina is the country comsuming the largest amount of mercury in the world,and also is one of the most serious regions suffering from atmospheric mercury pollution.The annual settlement value in the atmosphere was greater than the average 70ug/m3.In certain inshore water monitoring points,mercury had become the most serious index of pollutants. Mercury is a kind of heavy metal pollutants.It deposites to the soil and gradually transformes into methylmercury,which could be accumulated through the food chain,so the mercury content in aquatic organisms are more than that in the water.Therefore,the residents eating fish living in the water with mercury pollution are vulnerable to the hazards of mercury pollution,the pregnant women and fetuses are more likely to be hazardous.After pregnant women took the food with mercury and methylmercury,the mercury would be transformed into methylmercury that could be absorbed by the fetus. Methylmercury could penetrate red cell membrane and attach to hemoglobin,and then it would be oxidized to Hg2+and widely distributed in the body,but more enriched in the brain.The concentration of mercury in the brain could be more than about six times higher in the blood.As the fat-soluble and short-chain alkyl structure,methylmercury can go through the placenta and become a ion-complex.Because of the ion-complex has high affinity with fetal hemoglobin,it no longer return to the mother's blood circulation,the mercury content in fetal is always higher than that of the mother,so the fetus is very sensitive to methylmercury toxicity.Therefore,after taken a small amount of methylmercury,the mother may have no symptoms,but the fetus probablily has a significant injury.Methylmercury mainly harms the body's central nervous system,hearing and optic nerve,and the damage to the central nervous system is the most serious one.More and more attention has been paid to the relations between pregnant women eating fish and children' neurobehavioral development up to now.In addition,as the mercury in the environment continue to increase,the children are more likely to subject health hazard. But there is no unified conclusion about the neurobehavioral development of child,and the normal daily levels of mercury intake when the mother is under the mercury exposure during pregnancy.So this study is intended to detect the mercury content in major economic fish,urine,hair,blood of pregnant women and neonatal cord blood in Zhoushan city,and assess the association between the internal and external environmental mercury exposure and neurobehavioral development.Materials & MethodsDuring 1997 to 2003,some kinds of fish incluing Baigu Fish,Chang Fish,Nuota,Mei Fish,Dai Fish,Man Fish,Mo Fish,Majiao Fish,Xiaohuang Fish,were captureed in Zhoushan sea area,Which located in latitude 27°00′～33°00′,longitude 121°30′～125°30.The mercury content and quality of health evaluation index were also detected.The different types,different years,different specifications,and different areas of fish mercury levels were compared.The maternity hospital in Zhoushan maternal and child health Zhoushan local accounts and their newborns in March 2006 and July 2007 were selected as this object of study.The urine,hair and blood of pregnant women in late pregnancy were collected,and the neonatal cord blood was sampled when she/he was born.The DMA-80 automatic mercury analyzer was used for mercury content analysis.The association among the value of pregnant urine, hair,blood and neonatal cord blood were analyzed.In the basis of the mercury content analysis,the pregnant women agring to participate in the investigation of study and their newborns would be collected.The questionnaire "The economic social environment and health of neonatal family in Zhoushan island," were excuted.The contents of questionnaire included family situation,pregnancy history,and newborn personal circumstances.In 3-5 days after birth,neonatal behavioral neurological assessment would be assessed by neurobehavioral development score.First,all of newborns and their families pregnancy basic socio-economic situation and NBNA (Neonatal Behavioral Neurological Assessment)scores would be done by a descriptive statistical analysis.Then,the NBNA score would be selected as the dependent variable,the general situation in Newborn,the urine of pregnant women of mercury,the mercury value of blood mercury and other variables of umbilical cord blood were analyzed by Logistic regression.ResultsThe evaluation healthy quality index of nine kinds of economic fish was less than one. The levels of mercury in fish are different,and differences were significant(F=387.396,p＜0.000).Among nine kinds of fish,the highest one was Mo Fish,containing 0.163 mg/kg (95%CI:0.152-0.163mg/kg)mercury,followed by Man Fish,Nuota,Majiao Fish,Chang Fish,Dai Fish,Baigu Fish,Mei Fish,Xiaohuang Fish.The mercury contents of Baigu Fish, Mei Fish,Dai Fish and Xiaohuang Fish showed a increasing trend from 1997 to 2003. There were no significant difference among different specification(P＞0.05).Coastal areas fish mercury levels were higher than the offshore area,but there was no significant difference(P＞0.05).DMA-80 automatic mercury standards for the detection of the curve in the linear relationship was good,and quality control testing for compliance requirements,quality control products and test samples to repeat the RSD%were in an acceptable range(the detection limit was 0.02ng).The total pregnant women took part in the urine testing of mercury was 2,190.The mean,median,minimum,maximum,95%CI were 2.58ug/kg, 1.66ug/kg,0.01ug/kg,62.07ug/kg,2.42-2.74ug/kg respectively,and the quarte range was 1.79ug/kg.The total valid sample of pregnant women was 3,109.The mean,geometric mean,median, minimum,maximum,95%CI were 1.27mg/kg,1.04 mg/kg,1.09 mg/kg,0.04mg/kg, 17.19mg/kg,and 1.23-1.30mg/kg respectively.The effective samples of mercury content of maternal blood were 3,337.The mean, median,minimum,maximum,95%CI and quarter range were 5.40ug/kg,4.70ug/kg, 0.01ug/kg,34.28ug/kg,5.27-5.53ug/kg,4.54ug/kg respectively.The effective samples of mercury content of neonatal cord blood were 2,998.The mean median,minimum, maximum,95%CI,and quarter range were 7.71ug/kg,7.33ug/kg,0.01ug/kg,40.42ug/kg, 7.54-7.88 ug/kg,and 5.71 ug/kg,respectively.In the neonatal neurological behavioral assessment,the total sample of cases was 4180. There was no significant difference between newborn boys and girls in physical development situation,including weight,head circumference and height,which was similar to the result of nine Chinese city of neonatal medical researches.NBNA score showed that score 40 points accounted for 25.36 percent.This study found that the income of family, the frequency of mother eating fish affect the NBNA score.The more of the family income, NBNA may not be out of the probability on the rise.Similarly,the frequency of mother's fish intake will also affect NBNA scores.Neonatal cord blood mercury was correlated with NBNA value.The higher the value of blood mercury,the less NBNA score would be reached.The remaining factors were not associated with NBNA scores.ConclusionsIn recent years,the index of healthy quality of economic fish in Zhoushan area is accordant with the standard,but some level of mercury content in fish showed the increasing trend with year,suggesting that mercury should be prevented to become one of marine pollution in future.Pregnant women in Zhoushan and their newborn umbilical cord blood mercury levels are higher than those in other regions.Some preventing strategy should be carried out.The results suggest that the family income,frequency of mothers eating fish,high cord blood levels of mercury exposure may affect the neurobehavioral development of fetus.However,it is necessary to carry out a long-term follow-up of these newborns to ascertain the findings.
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