For years, the scientific evidence has been accumulating. The latest, published this week, once again showed that thimerosal, a mercury-based preservative long used in childhood vaccines, does not cause the neurological disorders associated with the U.S. autism epidemic.
In fact, scientists at the California Department of Public Health demonstrated that in the years since nearly all thimerosal was removed from vaccines in 2001, the rate of autism has continued to rise there. Had thimerosal been the culprit, those numbers should have decreased.
Case closed?
FOR THE RECORD - An article in yesterday's A section incorrectly characterized a threat to autism researchers. Dr. Gary Goldstein, president and CEO of the Kennedy Krieger Institute, was not the personal recipient of threats.
THE SUN REGRETS THE ERROR
Not in the world of autism, an emotionally charged place where Web sites, blogs and parent advocacy groups have spent a decade promoting the theory that the thimerosal injected into babies beginning when they were just weeks old has left as many as one in 150 children disabled by autism. These advocates have lobbied Congress, screamed about coverups and filed financial claims against the government.
"I know the people who want to believe it's thimerosal will find fault with this [study]," said Dr. Gary Goldstein, president & CEO of the Kennedy Krieger Institute in Baltimore. "The scientists, they're saying, `Why are we still talking about this?' "
Thimerosal, which is almost 50 percent mercury, has been a preservative in vaccines since the 1930. The first case of autism was identified at Johns Hopkins University in the 1940s.
Before 1991, only one vaccine - the one for diphtheria, tetanus and pertussis - contained thimerosal. Starting in 1991, two more were added to the schedule for infants - sharply increasing the quantity of mercury given to young children. Most other vaccines have remained mercury-free.
By 1999, some government scientists were concerned that infants might be getting too much mercury. As a precautionary measure, the federal Centers for Disease Control and Prevention and the American Academy of Pediatrics asked pharmaceutical companies to remove thimerosal from vaccines.
Still, according to Dr. Paul A. Offit, the infectious diseases chief at Children's Hospital of Philadelphia, doctors kept insisting that parents not worry about the safety of vaccines.
But the firestorm came. "Many parents, frightened by a sudden change in policy, reasoned that thimerosal was targeted because it was harmful - and their faith in the vaccine infrastructure was shaken," Offit wrote in a September issue of The New England Journal of Medicine.
