Heavy metals and trace elements in hair samples of autistic children in central Saudi Arabia

Objectives: Autism a childhood neurodevelopmentaldisorder, with onset prior to 36 months old. The etiologyof autism is complex, and usually, the underlyingpathologic mechanisms are unknown. Recently, alterationin heavy metals and trace elements had some interest.The aim of the present study is to examine levels of traceelements and heavy metals in hair samples, of autismspectrum disorders in the Riyadh area.Methods: The study was conducted in Riyadh area,Kingdom of Saudi Arabia between September 2003 andApril 2004. Seventy-seven autistic children participatedin the study, all with confirmed diagnosis according toE-2 diagnostic criteria for autistic spectrum disorders.Hair samples were analyzed by atomic absorptionspectrophotometer. The measurements of 9 heavy metals(lead, mercury, aluminum, arsenic, barium, cadmium,nickel, antimony and strontium), and 11 trace elements(sodium, calcium, chromium, copper, iron, magnesium,manganese, zinc, cobalt, selenium and molybdenum) wascarried out.Results: The current study showed significantly higherlevels of toxic heavy metals mercury, lead, arsenic,antimony and cadmium in autistic spectrum disorders ascompared to the control children. Moreover, hair samplesfrom children with autistic spectrum disorders containedsignificantly lower concentrations of calcium, copper,chromium, manganese, iron and cobalt, as compared tonormal children. In addition, we found a significantlyhigher incidence of social withdrawal, sleeping andeating disorders, speech and language disorders amongautism spectrum disorders as compared to controls.Conclusions: The present study demonstratedalteration in levels of toxic heavy metals and essentialtrace elements in children with autistic spectrumdisorders as compared to normal children. This suggests apossible pathophysiological role of heavy metals andtrace elements in the genesis of symptoms of autismspectrum disorders, such as social withdrawal, eating andsleeping disorders. In turn, those children with autisticspectrum disorders might benefit from chelating therapyfor heavy metal poisoning and supplementation ofessential trace elements.