WASHINGTON, Dec. 13 (UPI) -- A new study suggests a metabolic flaw in some children could trigger autism after exposure to mercury in vaccines.
The study, led by Dr. Jill James of the University of Arkansas, found 20 autistic children had less glutathione, an antioxidant that helps rid the body of toxic metals, when compared to a sample of healthy children.
A glutathione deficit could leave children vulnerable to toxic substances, including mercury, and "may contribute to the development and clinical manifestation of autism," concluded the report, published in the December issue of the American Journal of Clinical Nutrition.
The researchers proposed a biological mechanism consistent with the argument that mercury used in a vaccine preservative could have caused the startling rise autism in the 1990s.
That theory -- discounted in a report earlier this year by the prestigious Institute of Medicine -- holds that the increasing number of childhood vaccinations during the 1990s exposed children to toxic amounts of mercury in the preservative, called thimerosal. The substance has since been removed from most vaccines given to children in the United States.
The IOM report said the evidence "favors rejection of a causal relationship between thimerosal-containing vaccines and autism." It also recommended against further funding of research into that possibility.
Proponents of the autism-thimerosal theory, however, said the new study shows a need for more research.
"I think this is an extremely useful study and provides evidence supportive of a link between the autism epidemic and thimerosal exposure," said Mark Blaxill, a published researcher and board member of Safe Minds, a group that advocates exploration of a vaccine-thimerosal link.
"These findings raise serious concerns about the studies that have allegedly proven the safety of mercury in vaccines," said a statement by the Environmental Working Group, which studies toxic substances.
Pediatrician Dr. Elizabeth Mumper, of Lynchburg, Va., is putting the study results to the test. Mumper, who is on the University of Virginia medical faculty, said treating autistic children with large doses of B vitamins and folinic acid is triggering increases in glutathione levels and "spontaneous reports of improvement" in mental and social functioning.
She acknowledged the reports are "anecdotal evidence" but told UPI, "We are trying to study it scientifically. Somebody, somewhere, has to see how all this fits together."
Mumper said in the mid-1990s, she began noticing children seemed "sicker" in general. She said she asked herself, "Something is happening here. What is it?"