The Role of Lead Exposure on Attention-Deficit/ Hyperactivity Disorder ‎in Children: A Systematic Review

OBJECTIVE Attention-Deficit/Hyperactivity Disorder (ADHD) is one of the most common behavioral ‎disorders in children effecting the families and society. This systematic review examined ‎the literature on the role of lead exposure in children with ADHD‏ ‏symptoms. Articles were ‎analytically compared, focusing on the methodology used to assess exposure and‏ ‏adverse ‎effects‏ ‏on children with ADHD. ‎ METHOD Using the search strategy from six databases (Pub Med, PsycINFO, Web of Science, SID, ‎IRAN Medex, IRAN DOC), hand searching in key journals, list of references of selected ‎articles and gray literature, without time and language limitation, articles up to May 2014 ‎were entered into this review. In this review, 1,387 articles were acquired at the primary ‎search. Study selection and quality assessment processes were done based on Cochrane ‎library guidelines. After assessing the quality and inclusion and exclusion criteria, 18 articles ‎were selected and entered into the data synthesis.‎ RESULTS Blood Lead level (BLL) of less than 10µg/dL in children has been attributed to at least one ‎type of ADHD i.e., Combined / Inattentive / Hyperactive-Impulsive. The results of this ‎study revealed that in 16 out of the 18 studies, a significant association was found between ‎BLL and one of the types of ADHD.‎ CONCLUSION Based on the findings of this study, even the BLL of less than the action level of 10µg/dL, ‎chosen by Centers for Disease Control and Prevention (CDC), may affect children with ‎ADHD.‎.