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

Abstract

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.