Amalgam Causes Genetic Behavior Defects in Boys: Study

Chronic exposure to mercury in dental amalgam causes adverse neurobehavioral effects (e.g., diminished attention, diminished ability to place pegs in holes) among boys with the CPOX4 genetic variant of the heme pathway enzyme coproporphyrinogen oxidase, according to a University of Washington study published in the September-October issue of Neurotoxicology and Teratology.

Led by research professor emeritus James S. Woods, the seven-year study among 330 Portuguese children aged 8–12 at baseline is “the first to demonstrate genetic susceptibility to the adverse neurobehavioral effects of Hg exposure in children,” its abstract says.

In a controversial HHS decision last December, FDA was prevented from answering a petition seeking reversal of an earlier CDRH finding that dental amalgam is safe in children of that age.

The authors say the children in the study were “initially randomized to Hg amalgam (treatment) or composite resin (control) dental treatment groups. Subjects were evaluated at baseline and at seven subsequent annual intervals following initial dental treatment using an extensive battery of neurobehavioral assessments.”

They say that the concentration of adverse effects in boys over girls with the CPOX4 variant “provides evidence of sexual dimorphism in genetic susceptibility to the adverse neurobehavioral effects of Hg in children and adolescents,” and speculate that girls may excrete more mercury than boys and thus have a “lesser likelihood of mercury retention and accumulation.”