IQ

Research has generally shown that fluoridated water at recommended levels is safe. But many experts and a judge say more research is needed to better understand whether and when risks kick in.

Adding low levels of fluoride to water has long been considered one of the greatest health achievements. Now comes an analysis of previously published research that concludes a link with intelligence.

A Canadian study suggests that fluoride consumed by pregnant women can affect the IQ of their children. No single study provides definitive answers, but the findings will no doubt stir debate.

In a 5-4 decision, the Supreme Court struck down a Florida rule requiring a defendant's IQ to be 70 or below before that defendant could avoid the death penalty for reasons of mental retardation.