PITTSBURGH -- Both the seasonal flu and the H1N1 vaccines contain something called thimerosal, a mercury-based preservative that's long been a source of controversy.
Now a University of Pittsburgh researcher has found a possible link between thimerosal and developmental delays.
Team 4's Paul Van Osdol reported that the scientific establishment says all the evidence shows no link between thimerosal in vaccines and developmental delays like autism.
But researcher Laura Hewitson said her study shows something caused the monkeys in her experiment to have problems, either thimerosal or another ingredient in the vaccine they received.
The study compared the reflexes of baby monkeys that got Hepatitis B vaccine containing thimerosal with those that got no vaccine.
"The ones that received the vaccine, they were significantly delayed in acquiring three out of the four essential reflexes that are essential for survival in the wild. The control animals developed these reflexes normally," said Dr. Laura Hewitson of the University of Pittsburgh.
Hewitson said she suspects thimerosal, which contains mercury, caused the delays in the monkeys.
"Actually the brain stem is highly susceptible to the effects of mercury. So it is possible the thimerosal in these vaccines was causing functional brain damage in these infants so they were then delayed in being able to acquire these reflexes," said Hewitson.
The overwhelming majority of scientific studies have found no link between thimerosal and autism. However, the federal government has still removed thimerosal from most vaccines, including Hepatitis B. Hewitson says more research is needed.
"There just isn't enough research and there haven't been enough safety studies in order for us to conclusively say that vaccines containing thimerosal do not have any long term effects on children," Hewitson said.
Hewitson said she will continue studying the monkeys to see if there are long-term developmental delays.
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