Study Finds Brain Problems, Vaccines Not Linked
Thursday, September 27, 2007
LOS ANGELES, Sept. 26 -- A mercury-based preservative once used in many vaccines does not raise the risk of neurological problems in children, concludes a large federal study that researchers say should reassure parents.
The study did not examine autism, however. A separate study due out in a year will look at that issue, said scientists at the U.S. Centers for Disease Control and Prevention, who published the results in Thursday's New England Journal of Medicine.
They found no clear link between early exposure to the preservative thimerosal and problems with brain function and behavior in children ages 7 to 10. The results are in line with past research.
Thimerosal has not been used in childhood vaccines since 2001, although it is still found in some flu vaccine.
The study involved 1,047 children who were exposed to varying levels of thimerosal while in the womb or after birth in the 1990s.
Researchers did not find a consistent pattern between increasing thimerosal exposure and the risk of neurological problems, but they said one finding merited further study: Boys exposed to higher mercury levels seemed to have more tic problems. The panel included one vaccine opponent: Sallie Bernard, executive director of the advocacy group SafeMinds. She had a role in planning the study but disagreed with the conclusions.