Hong Soon-Beom, Im Mee-Hyang, Kim Jae-Won, Park Eun-Jin, Shin Min-Sup, Kim Boong-Nyun, Yoo Hee-Jeong, Cho In-Hee, Bhang Soo-Young, Hong Yun-Chul, Cho Soo-Churl
Division of Child and Adolescent Psychiatry, Department of Psychiatry, Seoul National University College of Medicine, Seoul, Republic of Korea.
Environ Health Perspect. 2015 Mar;123(3):271-6. doi: 10.1289/ehp.1307420. Epub 2014 Oct 3.
Low-level environmental exposure to lead has been associated with both reduced intelligence and symptoms of attention deficit/hyperactivity disorder (ADHD). However, few studies have estimated the association of lead and intelligence independent of ADHD, and it is not clear from previous studies whether lead is associated with both inattention and impulsivity ADHD symptoms.
We estimated mutually adjusted associations of environmental lead exposure with both intelligence and ADHD symptoms, and associations between lead and specific ADHD-related domains.
Blood lead concentrations were measured in a general population of 1,001 children 8-11 years of age. We used multivariable linear regression models to estimate associations of blood lead concentrations with IQ scores, teacher and parent ratings of ADHD symptoms, and measures of inattention and impulsivity. Models were adjusted for demographic variables and other environmental exposures (blood levels of mercury and manganese, urinary concentrations of cotinine, phthalate metabolites, and bisphenol A).
Associations of blood lead with lower IQ and higher impulsivity were robust to adjustment for a variety of covariates. When adjusted for demographic characteristics, other environmental exposures, and ADHD symptoms or IQ, a 10-fold increase in blood lead concentration was associated with lower Full-Scale IQ (-7.23; 95% CI: -13.39, -1.07) and higher parent- and teacher-rated hyperactivity/impulsivity scores (ADHD Rating Scale, 1.99; 95% CI: 0.17, 3.81 and 3.66; 95% CI: 1.18, 6.13, respectively) and commission errors (Continuous Performance Test, 12.27; 95% CI: -0.08, 24.62). Blood lead was not significantly associated with inattention in adjusted models.
Low-level lead exposure was adversely associated with intelligence in school-age children independent of ADHD, and environmental lead exposure was selectively associated with impulsivity among the clinical features of ADHD.
低水平环境铅暴露与智力下降以及注意力缺陷多动障碍（ADHD）症状均有关联。然而，很少有研究估计铅与智力之间独立于ADHD的关联，并且从先前的研究中尚不清楚铅是否与ADHD的注意力不集中和冲动症状均有关联。
我们估计了环境铅暴露与智力及ADHD症状之间的相互调整关联，以及铅与特定ADHD相关领域之间的关联。
对1001名8至11岁儿童的普通人群测量了血铅浓度。我们使用多变量线性回归模型来估计血铅浓度与智商得分、教师和家长对ADHD症状的评分以及注意力不集中和冲动测量指标之间的关联。模型针对人口统计学变量和其他环境暴露因素（汞和锰的血水平、可替宁、邻苯二甲酸酯代谢物和双酚A的尿浓度）进行了调整。
血铅与较低智商和较高冲动性之间的关联在对各种协变量进行调整后依然稳健。在对人口统计学特征、其他环境暴露因素以及ADHD症状或智商进行调整后，血铅浓度增加10倍与较低的全量表智商（-7.23；95%置信区间：-13.39，-1.07）以及较高的家长和教师评定的多动/冲动得分（ADHD评定量表，分别为1.99；95%置信区间：0.17，3.81和3.66；95%置信区间：1.18，6.13）和执行错误（连续操作测试，12.27；95%置信区间：-0.08，24.62）相关。在调整后的模型中，血铅与注意力不集中无显著关联。
低水平铅暴露在独立于ADHD的情况下与学龄儿童的智力呈负相关，并且环境铅暴露在ADHD的临床特征中与冲动性存在选择性关联。
