The Effects Of Low-Level Lead Exposure During Pregnancy On Visual And Auditory Development In Early Infants

Lead is a heavy metal with neurotoxicity, environmental lead pollution has been an important public hygienic problem. That lead can do harm to children's somatic growth and intelligence has been proven in many studies. The studies of the influence of low-level lead exposure of women during pregnancy on children mostly focus on cognitive function, rarely on sensory function. Objective: 1. By the investigation of the level of blood lead (Pb-B) among pregnant women and their children, and milk lead level, the purpose to recognize the dynamic tendency of Pb-B level of pregnancy women, and the relationship between the levels of Pb-B and milk lead, we also investigated the levels of blood zinc and calcium to study the association between blood lead and zinc and calcium. 2. By the measure of visual evoked potentials(VEP) and brainstem auditory evoked potentials(BAEP) of early infants, the purpose to investigate the probable effects of lead exposure during pregnancy on visual and auditory functions in infants. Methods: 1. The specimens of blood were collected form women at the second three months of gestation and delivery and from umbilical cord, and Pb-B levels were determined with graphite stove atom absorption spectrophotometry. The concentration of blood zinc and calcium were also measured. The specimens of milk were also collected to determine the concentration of lead and zinc. 2. VEP was recorded in infants at 35 days of age and 3 months of age. BAEP was recorded in infants at 6 months of age, and the concentration of Pb-B and hemoglobin were determined at the same day. 3. Give out the questionnaire and refer to the case history to get the condition of women and infants. 4. All the data were dealt with Excel 7.0 and Spss 8.0 for Windows. Results: 1. The Pb-B levels were (0.289 0.050) j.imol/L at the second three months of gestation , (0.242 0.049) p.mol/L at delivery, (0.197 0.05 1) imol/L from umbilical cord. The Pb-B level at the second three months of gestation is higher than it at delivery, and the Pb-B level at delivery is higher than it in umbilical cord. The Pb-B level in umbilical cord is equal to 81% of that at delivery. 2. There were significant association between the levels of Pb-B of the second three months of gestation and delivery(R=0.208, P0.037), Pb-B levels of delivery and umbilical cord (R=0.407, P=0.00 1). Pb-B level was not significantly associated with milk lead level. Pb-B levels of pregnant women and umbilical cord were not significantly associated with the concentrations of blood zinc and calcium. There was a significant negative association between milk lead level and zinc level(R=-0.263, P=0.002). 3. There was no significant association between the Pb-B levels of pregnant women and umbilical cord and the indices of peak P100 of VEP in early infants. 4. There was a significant association between the Pb-B level of umbilical cord and the latencies of waves F.. III and V at right ear (R=0.624, P=0.013; R=0.592, P=0.020; R=0.602, P=0.018 respectively) . linear regression analysis revealed that contribution of Pb-B level of umbilical cord to the latencies of waves I. III and V at right ear was still statistically significant after adjusting other confounding factors. Conclusion: 1. There...