Metallic Burden of Deciduous Teeth and Childhood Behavioral Deficits.

Attention Deficit/Hyperactivity Disorder (ADHD) affects 5%-8% of children in the U.S. (10% of males and 4% of females). The contributions of multiple metal exposures to the childhood behavioral deficits are unclear, although particular metals have been implicated through their neurotoxicity. The objective of this study was to test the hypothesis that the body burden of Mn is positively correlated with ADHD symptoms. We also investigated the putative roles of Ca, Fe, Pb, and Hg. We collected shed molars from 266 children (138 boys and 128 girls) who lost a tooth between 11 and 13 years of age. The molars were analyzed for metals using ICP-OES. The third grade teacher of each child completed the Teacher's Disruptive Behavior Disorders Rating Scale (DBD) to produce a score for "Total Disruptive Behavior" and subscale scores for "Attention Deficit Hyperactivity Disorder", Hyperactivity/Impulsivity, Inattention, and Oppositional/Defiant. The mean Mn, Fe, Pb and Ca concentrations found in teeth was 6.1 ± 5.7 µg/g, 22.7 ± 24.1 µg/g, 0.9 ± 1.4 µg/g, and 6.0 × 105 ± 1.6 × 105 µg/g, respectively. Hg was not detected. No significant association was found between Mn and behavioral deficits. Ca was significantly negatively associated, and Pb showed a significant positive association with Hyperactivity/Impulsivity, Inattention, and Oppositional/Defiant Disorders. These findings call into question the putative independent association of manganese exposure and behavioral deficits in children, when the balance of other metallic burden, particularly Ca and Pb burdens play significant roles.

Heavy metal in children's tooth enamel: related to autism and disruptive behaviors?

To examine possible links between neurotoxicant exposure and neuropsychological disorders and child behavior, relative concentrations of lead, mercury, and manganese were examined in prenatal and postnatal enamel regions of deciduous teeth from children with Autism Spectrum Disorders (ASDs), high levels of disruptive behavior (HDB), and typically developing (TD) children. Using laser ablation inductively coupled plasma mass spectrometry, we found no significant differences in levels of these neurotoxicants for children with ASDs compared with TD children, but there was marginal significance indicating that children with ASDs have lower manganese levels. No significant differences emerged between children with HDB and TD children. The current findings challenge the notion that perinatal heavy metal exposure is a major contributor to the development of ASDs and HDB.