How much fluoride is enough? The American Dental Association, American Academy of Pediatrics and American Academy of Pediatric Dentistry have developed this table as a guide for when children should be given fluoride supplements.

For reference:
1 ppm = 1 milligram per liter of water
1 ppm = 0.5 milligram per pint (16 ounces) of water
1 ppm = 0.25 milligram per cup (8 ounces) of water
1 gram of fluoridated toothpaste contains about 1 milligram of fluoride

If you drink well water, contact your state or county health department for a list of approved laboratories that will test a water sample. You may need to pay a small fee ($20 to $40).

Your home's water isn't the only thing to think about, however. Many children drink water from other places, such as a child care provider, school or grandparents' house. In addition, other beverages and many foods contain fluoride as well.

Most bottled water doesn't contain fluoride. But some bottled, fluoridated water is marketed specifically to children.

Like any prescription, fluoride supplements should be used as directed and kept out of reach of children. However, fluoride is toxic only at very high doses. For example, the toxic dose for a 22-pound child is 320 milligrams, and for a 45-pound child, it's 655 milligrams. In comparison, an 8-ounce glass of water fluoridated to 1.0 ppm contains about 0.25 milligram of fluoride.