Epidemiological Study On Association Of Lead, Mercury And Other Elements Exposure During Pregnancy With Congenital Malformations And Early Spontaneous Abortion

Objective Investigating the effects of environmental factors on congenital malformations and early spontaneous abortion,and probing the associations of lead(Pb),mercury(Hg),arsenic(As),cadmium(Cd), manganese(Mn) and zinc(Zn) exposure during pregnancy with congenital malformations and early spontaneous abortion.Methods In partⅠ,the whole blood and serum were collected from 200 pregnant women with congenital malformed fetuses and 204 pregnant women with normal live birth in Shanghai First Maternal and Infant Hospital between September,2006 and April,2OO7.In partⅡ,the specimens from 78 patients including 16 spontaneous miscarriage cases and 62 early artificial abortion cases were collected in this hospital between May,2007 and July,2007.All of these women were questioned about their living environments,life style,diet habits,educational background, income and physical condition.The whole blood concentrations of Pb,As,Cd and the serum concentrations of Mn,Zn,as well as the levels of these five elements in villus,were determined by microwave digestion method and inductively coupled plasma emission mass spectroscopy method (ICP-MS).And the whole blood Hg was detected by cold vapour atomic absorption spectrophotometer(CV-AAS).In partⅠ,we investigated the influences of those elements on the fetal congenital malformations, especially the teratogenesis of nervous system and urinary system.In partⅡ,we analyzed the effects of those elements on early spontaneous abortion.Results(1) The median(μg/L) of blood Pb,Hg,As,Cd levels and serum Mn,Zn levels in normal group of 204 women at second and third trimester were 36.48,2.02,2.33,1.35,22.39,1018,respectively.And the median(μg/L) of those elements in 62 cases with normal early pregnancies were 45.2, 2.1,2.37,1.44,33.63,965.75,respectively.The median(μg/Kg) of villus Pb,AS,Cd,Mn,Zn levels in 62 first trimester cases were 15.66,3.06, 1.84,203.8,8364,respectively.(2) The correlation of fetal congenital malformations with their mother' s educational background,the factories around living house,fuel used in kitchen,the habit of pickled food as well as folate supplementation,was significant.The odds ratio(OR) values were 2.589, 6.189,1.769,2.54,6.742,respectively.The concentrations of blood Pb,Hg and serum Mn in the trial group were significantly higher than those in control group,while serum Zn level in trial group was lower than that in control group(P＜0.05).The differences of blood As and Cd levels in the two groups were not apparent.After adjustment for environmental variations,Logistic regression analysis showed that Pb exposure was a risk factor for congenital malformations,while Zn was a protective factor.The OR values were 1.016(95%confidence interval(CI) 1.003-1.029) and 0.998(95%CI 0.997-0.999),respectively.(3) The environmental factors associated with neural teratogenesis were occupational exposure,culture background,factories around living house, passive smoking and folate supplementation.The OR values were 31.685, 3.761,20.561,2.023,10.021,respectively.The blood concentrations of Pb and Hg in these 52 gravidas with neural deformity were significantly higher than those in control group,and meanwhile the level of serum Zn in these women was much lower than that in control group(P＜0.05).The differences of blood As,Cd,serum Mn levels in the two groups were of no significance.After adjustment for environmental variations,Logistic regression analysis showed that Pb exposure was a risk factor for neural deformations,but Zn was a protective factor.The OR values were 1.039 (95%CI 1.015-1.065) and 0.998(95%CI 0.996-0.999),respectively.(4) The environmental factors associated with urological abnormalities were factories around living house,maternal smoking,the habit of pickled food and folate supplementation.The OR values were 30.701,7.694, 9.999,14.335,respectively.The blood Pb level in these 44 pregnancies with urological malformations was significantly higher than that in control group.On contrary,the serum Zn level in these women was much lower than that in control group(P＜0.05).The differences of blood Hg,As,Cd and serum Mn levels in these two groups were not signficant.After adjustment for environmental variations,Logistic regression analysis showed that Zn was the only trace element which might protect from urologic teratogeny that been kept in the final model(OR=0.997,95%CI 0.995-0.999).(5)The environmental factors associated with early spontaneous abortion covered maternal occupational exposure,educational background,anaemia and passive smoking.There was a strong correlation for the levels of Pb,As,Cd and Zn between blood and villus(r=0.411,0.606,0.691,0.506 respectively).Both levels of Zn in blood and villus in women with early pregnancy loss were significantly lower than those in control group (P＜0.05).The blood Pb level and the villus Cd,Mn levels were higher in trial group than those in control group(P＜0.05).There was no significant difference in the concentrations of blood Hg,As,Cd and serum Mn,as well as in villus Pb,As for these two groups.After adjusted other risk factors, Logistic regression analysis showed that both blood Zn and villus Zn were protective factors from early spontaneous abortion(OR=0.994,0.999 respectively).And passive smoking was the only risk environmental factor which been kept in the two final model.Conclusion(1)The findings suggested that the concentrations of heavy metal elements in blood of pregnant women were higher than those reported by developed coutries.We should focus on the possible influence of the heavy metal elements on teratogenesis,though the levels of blood Pb,Hg,As,Cd,Mn levels in pregnant women in Shanghai generally were below those considered hazardous.(2)Maternal blood Zn level and folate supplementation had some prophylactic influences on the congenital malformations especially the teratogenesis of nervous system and urinary system.Maternal Pb exposure might serveasa risk factor for the general congenital malformations and neural teratogenesis,but its relationship with urinary teratogenesis was not apparent.No significant association between is,Cd,Hg,Mn exposure and congenital malformations was observed in this study.Maternal occupational exposure,educational background,smoking or passive smoking,habit of pickled food,fuel in kitchen and factories around living house had some impacts on fetal abnormalities.(3)The environmental factors associated with early spontaneous abortion were maternal occupational exposure,educational background,anaemia and passive smoking.The relationship between passive smoking and early pregnancy loss was the most significant one among these four environmental factors.No significant link of Pb,As,Cd,Hg,Mn exposure with early spontaneous abortion was observed in this study.Both Zn level in blood and villus were protective factors from early spontaneous abortion.This reminded us that maternal deficiency of Zn might serve as a risk factor for human early spontaneous abortion.