An independent scientific panel weighing a possible link between autism and the mercury preservative in childhood vaccines heard suggestions on Monday that the source of the heavy metal could be fish.
The Institute of Medicine panel heard the results from more than a dozen studies on thimerosal, the preservative found in some vaccines. When it last met in 2001, it decided there was no evidence that vaccines caused autism but it also noted little research had been done.
“Clearly, there’s far more information addressing this issue,” said panel chair Dr. Marie McCormick, a professor of maternal and child health at the Harvard School of Public Health.
Autism is a mysterious disorder whose symptoms range from a lack of social skills to a profound and crippling inability to relate to others.
Because it is usually diagnosed during the toddler years when children receive many of the 18 or so early childhood shots, some advocacy groups believe vaccines are to blame.
Many parents told the panel they were anti-thimerosal, not anti-vaccine.
“Its use should be considered historic,” said Lyn Redwood, president of the advocacy group Safe Minds whose youngest son is autistic. “Why take the risk when you don’t have to?”
Potential brain damage?
Scientists say it is possible that if it got into the brain, thimerosal could cause brain damage. Although it is no longer found in childhood vaccines in the United States, it remains in the influenza vaccine and in vaccines in other countries.
Several researchers on Monday pointed to recent studies highlighting the harmful levels of mercury found in fish and the potential brain damage caused by eating it.
Last week, an international group of researchers reported in the Journal of Pediatrics that children can suffer irreparable brain damage if their mothers eat seafood high in mercury while pregnant.
Dr. Mady Hornig, a professor at Columbia University, told the panel future studies should address exposure to mercury through food. “This is a continued concern ... if we are not going to remove fish from our diet,” she said.
Researcher H. Vasken Aposhian said studies needed to look at the impact of a mother’s mercury levels on her children.
“That mercury load is transferred to some extent... to the child,” said Aposhian, a toxicologist and biology professor at the University of Arizona.
But Amy Carson, co-founder of Moms Against Mercury, said the government and others were trying to “shift the blame” from thimerosal to other sources.
“I think they want to be able to say those children were already damaged in utero and that it didn’t have anything to do with vaccines,” said Carson, whose 7-year-old son has autism.
The panel said it plans to publish its report later this spring.