Association between blood lead levels (<5 μg/dL) and inattention-hyperactivity and neurocognitive profiles in school-aged Korean children.

OBJECTIVES: The association between low blood lead levels (<5 μg/dL) and the inattention-hyperactivity symptoms and neurocognitive profiles of school-aged Korean children was investigated.
METHODS: We measured blood lead levels in 256 Korean children aged 8-10 years. Teachers completed the Attention-Deficit Hyperactivity Disorder Rating Scale (T-ARS)-IV to assess inattentive and hyperactive symptoms. Parents completed the Korean version of the Learning Disability Evaluation Scale (K-LDES). Children performed neurocognitive tests [The Continuous Performance Test (CPT), the Children's Color Trails Test, and the Stroop Color and Word Test (SCWT)].
RESULTS: A linear regression analysis indicated that the blood lead concentrations were associated with the inattention scores [B=4.8, S.E.=1.6, 95% confidence interval (CI): 1.5-8.0], the hyperactivity subscores (3.1, 1.4, 0.3-5.9), and the total score (7.9, 2.9, 2.1-13.6) on the T-ARS; the number of omission errors on the CPT (20.6, 7.1, 6.5-34.6); the listening (-1.4, 0.7, -2.8 to -0.1), reading (-2.1, 0.7, -3.4 to -0.7), writing (-2.0, 0.7, -3.4 to -0.6), spelling (-2.2, 0.7, -3.7 to -0.7), and calculating (-1.8, 0.7, -3.1 to -0.4) scores on the K-LDES; and the color-word score on the SCWT (-6.7, 3.4, -13.3 to -0.1). A logistic regression analysis indicated that the probability of inattentive and hyperactive symptoms was increased with higher blood lead levels in boys with an odds ratio of 2.768 [B=1.018, S.E.=0.487, p=0.036, 95% CI: 1.066-7.187].
CONCLUSION: This study suggests that even low blood lead levels (<5 μg/dL) are associated with inattentive and hyperactivity symptoms and learning difficulties in school-aged children.