LOW-LEVEL LEAD-EXPOSURE AND CHILDRENS IQ - A METAANALYSIS AND SEARCH FOR A THRESHOLD
LOW-LEVEL LEAD-EXPOSURE AND CHILDRENS IQ - A METAANALYSIS AND SEARCH FOR A THRESHOLD
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DOI：
10.1006/enrs.1994.1020
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发表时间：
1994-04-01
影响因子：
8.3
通讯作者：
SCHWARTZ, J
中科院分区：
文献类型：
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作者：
SCHWARTZ, J
为了评估血铅和儿童智商之间的关联强度，对学龄儿童的关系进行了荟萃分析。重点是效应的大小，因为这允许比较提供有关潜在混杂因素和效应修饰因子的信息。还进行了敏感性分析。铅暴露与儿童智商有高度显著性相关（P < 0.001）。在荟萃分析中，血铅从10 μ g/dl增加到20 μ g/dl与智商下降2.6分相关。这一结果对于纳入或排除最强的个体研究以及放宽荟萃分析的年龄要求（学龄儿童）是稳健的。增加8项效应估计值为0的研究仍与血铅存在显着相关性（P < 0.01）。没有证据表明这种影响仅限于处境不利的儿童，有人提出相反的建议。平均血铅水平为15 μ g/dl或更低的研究样本中估计的血铅斜率更高，表明10 μ g/dl的阈值是不可信的。使用非参数平滑法检查平均血铅水平最低的研究。没有证据表明血铅浓度低于1微克/分升的阈值。铅干扰GABA能和多巴胺能神经传递。已显示其与NMDA受体结合并抑制脑海马区的长时程增强。此外，实验研究表明，血液中10微克/分升的水平会干扰灵长类动物的广泛认知功能。鉴于这种支持，人类的这些关联应该被认为是因果关系。(C)1994年出版社出版。
To assess the strength of the association between blood lead and children's IQ, a metaanalysis of the studies examining the relationship in school age children was performed. Emphasis was given to the size of the effect, since that allows comparisons that are informative about potential confounding and effect modifiers. Sensitivity analyses were also performed. A highly significant association was found between lead exposure and children's IQ (P < 0.001). An increase in blood lead from 10 to 20 mu g/dl was associated with a decrease of 2.6 IQ points in the meta-analysis. This result was robust to inclusion or exclusion of the strongest individual studies and to relaxing the age requirements (school age children) of the meta-analysis. Adding eight studies with effect estimates of 0 would still leave a significant association with blood lead (P < 0.01). There was no evidence that the effect was limited to disadvantaged children and there was a suggestion of the opposite. The studies with mean blood lead levels of 15 mu g/dl or lower in their sample had higher estimated blood lead slopes, suggesting that a threshold at 10 mu g/dl is implausible. The study with the lowest mean blood lead level was examined using nonparametric smoothing. It showed no evidence of a threshold down to blood lead concentrations of 1 mu g/dl. Lead interferes with GABAergic and dopaminergic neurotransmission. It has been shown to bind to the NMDA receptor and inhibit long-term potentiation in the hippocampal region of the brain. Moreover, experimental studies have demonstrated that blood levels of 10 mu g/dl interfere with a broad range of cognitive function in primates. Given this support, these associations in humans should be considered causal. (C) 1994 Academic Press, Inc.