Declining blood lead levels and changes in cognitive function during childhood - The Port Pirie Cohort Study
Declining blood lead levels and changes in cognitive function during childhood - The Port Pirie Cohort Study
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DOI：
10.1001/jama.280.22.1915
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发表时间：
1998-12-09
影响因子：
120.7
通讯作者：
McMichael, AJ
中科院分区：
文献类型：
--
作者：
Tong, S;Baghurst, PA;McMichael, AJ
背景。-许多研究发现，儿童早期环境铅暴露与认知功能之间存在显著的负相关。当接触减少时，这些影响是否可逆尚不清楚。为了评估铅对儿童早期认知能力的明显影响的可逆性，通过测试2岁以上血铅浓度的下降是否与认知能力的改善有关。城市和农村社区周围的一个大型铅冶炼厂在皮里港，南澳大利亚州。共有375名儿童从出生到11至13岁进行了随访。长期前瞻性队列研究。主要结果测量。2岁时的Bayley精神发育指数，4岁时的McCarthy一般认知指数，以及7岁和11至13岁时的Wechsler智力量表（修订版）的智商。儿童的平均血铅浓度从2岁时的1.02 μ mol/L（21.2 μ g/dL）下降到11至13岁时的0.38 μ mol/L（7.9 μ g/dl），但血铅浓度下降最多的儿童的认知评分通常不会相对于血铅水平下降最少的儿童的评分有所改善。在7岁和11至13岁之间发生的智商变化和血铅水平下降（r = 0.12，P = 0.09）表明，血铅水平下降最多的儿童的认知能力稍好。与儿童早期环境铅暴露相关的认知缺陷似乎只能通过随后的血铅水平下降而部分逆转。
Context.-Many studies have found a significant inverse association between early exposure to environmental lead and cognitive function in childhood. Whether these effects are reversible when exposure is reduced is not clear.Objective.-To assess the reversibility of the apparent effects of lead on cognitive abilities in early childhood by testing whether declines in blood lead concentrations beyond the age of 2 years are associated with improvements in cognition.Setting.-Urban and rural communities surrounding a large lead smelter in Port Pirie, South Australia.Participants.-A total of 375 children followed up from birth to the age of 11 to 13 years.Design.-Long-term prospective cohort study.Main Outcome Measures.-The Bayley Mental Development Index at age 2 years, the McCarthy General Cognitive Index at age 4 years, and IQs from the Wechsler Intelligence Scale (revised version) at ages 7 and 11 to 13 years.Results.-Mean blood lead concentrations in the children decreased from 1.02 mu mol/L (21.2 mu g/dL) at age 2 years to 0.38 mu mol/L (7.9 mu g/dl) at age 11 to 13 years, but cognitive scores in children whose blood lead concentration declined most were generally not improved relative to the scores of children whose blood lead levels declined least. Changes in IQ and declines in blood lead levels that occurred between the ages of 7 and 11 to 13 years (r = 0.12, P = .09) suggested slightly better cognition among children whose blood lead levels declined most.Conclusion.-The cognitive deficits associated with exposure to environmental lead in early childhood appear to be only partially reversed by a subsequent decline in blood lead level.