A mercury-containing vaccine preservative is not associated with problems in speech, intelligence, memory, coordination, attention, or other measures of childhood development, a large new study finds.
Child-health experts say that the results should allay concerns that thimerosal, a preservative first added to vaccines in the 1930s, affects children's brains.
"The study was enough to convince me that this small amount of mercury ... was not harmful to the children," says Michael Goldstein, vice president of the St. Paul, Minn.–based American Academy of Neurology.
"I think it's one more piece of evidence that thimerosal doesn't have any negative association with health outcomes," says Penelope Dennehy, professor of pediatrics at the Brown University School of Medicine in Providence, R.I.
The study, funded by the Centers for Disease Control and Prevention (CDC) in At