"In Boston, for example, more than 60 percent of the exclusively formula-fed babies exceed the safe dose of fluoride on any given day," the group said in a recent press release.
This is based on fluoride data compiled from municipal drinking water systems from 1998 to 2002 that showed that, of the 28 largest cities in the United States, Boston had the highest fluoride level -- 1.30 milligrams per liter -- exceeding the recommended range of 0.7-1.2 milligrams per liter.
So is it safe for infants to drink formula reconstituted with tap water?
"Yes, I think that's safe, quite frankly, because that's what infants have been doing across this country for many decades," said Dr. John Stamm, a professor at the University of North Carolina School of Dentistry and spokesman for the ADA. "The public health safety data has been accumulating, and none of those infants have developed moderate or severe fluorosis, which is the criterion that the NRC report is using to evaluate the safety of fluoride."
But that doesn't mean people shouldn't be cautious, he said.
"All consumers should be aware of the fluoride level in their drinking water," Stamm said. "This is a matter of personal health interest. If you live in a fluoridated community, that information is available from a telephone call to the water company. If you live in a rural community, you may not know how much fluoride is in your well water; it then behooves you to ask your dentist to refer you to the state agency that can determine your fluoride concentration."
Experts said that switching from tap water to bottled water is probably an unnecessary step because bottled water usually has too little fluoride to protect against cavities, although there is wide variability among brands and most do not state how much fluoride they contain.
"Bottled water has to meet the same drinking water standards as tap water," Kemery said.
And for people who are considering home filtering systems, look carefully at their specifications, too.
"Home filtering systems vary widely in their ability to filter out fluoride, from 15 to 90 percent," said Poole.
What can parents do to protect their kids? The most important thing is to teach them not to swallow their toothpaste, Stamm said.
"Toothpaste is designed to have a lot of fluoride -- 1,000 milligrams per liter. Young children should use only a pea-size quantity of toothpaste when they brush," Stamm said.