Blood lead, bone lead and child attention-deficit-hyperactivity-disorder-like behavior.

Abstract

BACKGROUND AND OBJECTIVE\nMounting evidence showed that lead exposure increased the risk of child attention-deficit-hyperactivity disorder (ADHD). Epidemiologic studies have typically used the blood-lead as a biomarker of lead exposure; blood-lead levels mostly reflect recent lead exposure. However, few studies have examined the relationship between bone-lead, a biomarker of cumulative exposure, and ADHD. Therefore, we aimed to compare the associations of bone-lead vs blood-lead levels with child ADHD symptoms and comorbidities.\n\n\nMETHODS\nA total of 164 children aged 3-15\u202fyears were enrolled during 2014-2015. The Vanderbilt-ADHD-Diagnostic-Parent-Rating Scale (VADPRS) was used to evaluate the children s ADHD symptoms and comorbidities. Children s blood and bone lead concentrations were assessed, the latter using a non-invasive K-X-ray-fluorescence technique. According to blood-lead levels, children were classified into high (blood-lead\u202f≥\u202f10.0\u202fμg/dL) and low (blood-lead\u202f<\u202f10.0\u202fμg/dL) blood-lead groups. According to bone-lead levels, children were classified into high (bone-lead\u202f≥\u202f2.66\u202fμg/g) and low (bone-lead\u202f<\u202f2.66\u202fμg/g) bone-lead groups. We associated blood/bone lead with VADPRS data using multi-variable binary logistic regression models.\n\n\nRESULTS\nChildren in the high blood-lead group had higher hyperactivity/impulsivity (P\u202f=\u202f0.02) scores than the corresponding low blood-lead group. Children in the high bone-lead group had higher hyperactivity/impulsivity (P\u202f=\u202f0.02) and oppositional-defiant-disorder (ODD) (P\u202f=\u202f0.03) scores than the corresponding low bone-lead group. After adjusting for relevant confounders, children in the high bone-lead group were more likely to have ODD-behavior than the low group (OR\u202f=\u202f6.7, 95%CI: 1.2-36.5). However, no adjusted association was observed between blood-lead and any ADHD-domain score.\n\n\nCONCLUSION\nHigh levels of cumulative lead exposure in children may be an independent risk factor of ODD-behavior.