The Centers for Disease Control and Prevention (CDC) recently released a study suggesting that the childhood vaccine mercury-containing preservative thimerosal—which the FDA banned in 1999—does not cause neurological issues such as learning difficulties or development delays. Lead author William W. Thompson admitted that his team did, however, find that boys given high doses of thimerosal were twice as likely to develop minor tics than boys given lower levels. The much-hyped autism link–which the CDC claims does not exist–was absent from the analysis.