McMichael A J, Baghurst P A, Wigg N R, Vimpani G V, Robertson E F, Roberts R J
Department of Community Medicine, University of Adelaide, South Australia.
N Engl J Med. 1988 Aug 25;319(8):468-75. doi: 10.1056/NEJM198808253190803.
We studied the effect of environmental exposure to lead on children's abilities at the age of four years in a cohort of 537 children born during 1979 to 1982 to women living in a community situated near a lead smelter. Samples for measuring blood lead levels were obtained from the mothers antenatally, at delivery from the mothers and umbilical cords, and at the ages of 6, 15, and 24 months and then annually from the children. Concurrently, the mothers were interviewed about personal, family, medical, and environmental factors. Maternal intelligence, the home environment, and the children's mental development (as evaluated with use of the McCarthy Scales of Children's Abilities) were formally assessed. The mean blood lead concentration varied from 0.44 mumol per liter in midpregnancy to a peak of 1.03 mumol per liter at the age of two years. The blood lead concentration at each age, particularly at two and three years, and the integrated postnatal average concentration were inversely related to development at the age of four. Multivariate analysis incorporating many factors in the children's lives indicated that the subjects with an average postnatal blood lead concentration of 1.50 mumol per liter had a general cognitive score 7.2 points lower (95 percent confidence interval, 0.3 to 13.2; mean score, 107.1) than those with an average concentration of 0.50 mumol per liter. Similar deficits occurred in the perceptual-performance and memory scores. Within the range of exposure studied, no threshold dose for an effect of lead was evident. We conclude that postnatal blood lead concentration is inversely related to cognitive development in children, although one must be circumspect in making causal inferences from studies of this relation, because of the difficulties in defining and controlling confounding effects.
我们对537名1979年至1982年出生于居住在铅冶炼厂附近社区的女性的孩子进行了研究，以探讨环境铅暴露对4岁儿童能力的影响。测量血铅水平的样本取自母亲产前、分娩时的母亲和脐带血，以及孩子6个月、15个月和24个月时，之后每年都采集。同时，对母亲进行了关于个人、家庭、医疗和环境因素的访谈。对母亲的智力、家庭环境以及孩子的智力发育（使用麦卡锡儿童能力量表进行评估）进行了正式评估。血铅平均浓度从中孕期的每升0.44微摩尔变化到2岁时的峰值每升1.03微摩尔。每个年龄段的血铅浓度，尤其是2岁和3岁时的，以及产后综合平均浓度与4岁时的发育呈负相关。纳入孩子生活中许多因素的多变量分析表明，产后血铅平均浓度为每升1.50微摩尔的受试者的总体认知得分比平均浓度为每升0.50微摩尔的受试者低7.2分（95%置信区间，0.3至13.2；平均得分，107.1）。感知 - 操作和记忆得分也出现了类似的缺陷。在所研究的暴露范围内，没有明显的铅效应阈值剂量。我们得出结论，产后血铅浓度与儿童认知发育呈负相关，尽管由于难以定义和控制混杂效应，在从这种关系的研究中进行因果推断时必须谨慎。
