Wehby George L
Department of Health Management and Policy, University of Iowa, Iowa City.
Department of Economics, University of Iowa, Iowa City.
JAMA Netw Open. 2025 May 1;8(5):e2512796. doi: 10.1001/jamanetworkopen.2025.12796.
In 2021, the Centers for Disease Control and Prevention lowered the blood lead reference values to 3.5 μg/dL or higher. More evidence is needed on the association between lead changes below 3.5 μg/dL and academic achievement.
To examine the association of a 1-unit change in early childhood blood lead levels below 3.5 μg/dL vs at 3.5 μg/dL or higher with academic achievement.
DESIGN, SETTING, AND PARTICIPANTS: This cohort study linked birth certificates of children born in Iowa from 1989 to 2010 to their math and reading test scores for grades 2 through 11 and to their early childhood blood lead testing data. Analyses were completed between May 2024 and March 2025.
Early life blood lead levels below 3.5 μg/dL and at 3.5 μg/dL or higher.
The primary outcome was national percentile rank (NPR) scores on math and reading school tests. Regression models estimated the association between lead levels and math and reading scores, controlling for sociodemographic, child and maternal health, and school characteristics.
The analytical sample included up to 305 256 children and 1 782 873 child-grade observations. Within the analytical sample, 51.0% were male, 41.1% were first-born children, and 43.9% were born to mothers with an educational level of high school or less. Sociodemographic and child and maternal health characteristics were similar between the analytical sample and the birth population. The mean (SD) child age at lead testing was 1.9 (1.5) years. Among these children, 37.7% had lead values below 3.5 μg/dL. A 1-unit increase in lead levels below 3.5 μg/dL was associated with lower NPR scores in math by -0.47 (95% CI, -0.65 to -0.30) and in reading by -0.38 (95% CI, -0.56 to -0.20). For lead levels at 3.5 μg/dL or higher, a 1-unit increase in lead levels was associated with lower NPR scores in math by -0.52 (95% CI, -0.58 to -0.47) and in reading by -0.56 (95% CI, -0.62 to -0.51). These score declines were persistent across grades 2 through 11.
In this cohort study assessing early life low lead level and children's and adolescents' academic achievement, a 1-unit increase in lead levels in the range currently considered low for further interventions was associated with worse academic performance throughout school grades comparable to that for lead levels in the range recommended for additional interventions. These findings support the need to reconsider and potentially lower current blood lead reference values for recommending further interventions.
2021年，美国疾病控制与预防中心将血铅参考值降至3.5μg/dL及以上。低于3.5μg/dL的血铅变化与学业成绩之间的关联需要更多证据。
研究3.5μg/dL以下与3.5μg/dL及以上的幼儿血铅水平每变化1个单位与学业成绩之间的关联。
设计、背景和参与者：这项队列研究将1989年至2010年在爱荷华州出生的儿童的出生证明与其2至11年级的数学和阅读测试成绩以及幼儿血铅检测数据相联系。分析于2024年5月至2025年3月完成。
生命早期血铅水平低于3.5μg/dL以及3.5μg/dL及以上。
主要结局是学校数学和阅读测试的全国百分位排名（NPR）分数。回归模型估计了血铅水平与数学和阅读分数之间的关联，并对社会人口统计学、儿童和母亲健康以及学校特征进行了控制。
分析样本包括多达305256名儿童和1782873个儿童年级观察值。在分析样本中，51.0%为男性，41.1%为头胎子女，43.9%的母亲教育水平为高中或以下。分析样本与出生人群的社会人口统计学、儿童和母亲健康特征相似。血铅检测时儿童的平均（标准差）年龄为1.9（1.5）岁。在这些儿童中，37.7%的血铅值低于3.5μg/dL。血铅水平低于3.5μg/dL时，血铅水平每增加1个单位，数学NPR分数降低-0.47（95%CI，-0.65至-0.30），阅读NPR分数降低-0.38（95%CI，-0.56至-0.20）。对于血铅水平在3.5μg/dL及以上的情况，血铅水平每增加1个单位，数学NPR分数降低-0.52（95%CI，-0.58至-0.47），阅读NPR分数降低-0.56（95%CI，-0.62至-0.51）。这些分数下降在2至11年级持续存在。
在这项评估生命早期低血铅水平与儿童和青少年学业成绩的队列研究中，目前被认为低到无需进一步干预范围内的血铅水平每增加1个单位，与整个学校年级学业成绩较差相关，这与建议进行进一步干预范围内的血铅水平相当。这些发现支持重新考虑并可能降低当前血铅参考值以建议进一步干预的必要性。
