The CDC applauds the adding of fluoride to our water supply as one of the biggest public health triumphs of the 20th century. But it seems too much fluoride can do a lot of damage. Not only can it actually damage our teeth and weaken our bones—studies in China and Iran appear to link excessive fluoride to a seven-point reduction in children's IQs, Scientific American reports. Those studies may not control for other health risks, but they could signal a problem—one which is particularly worrying in states like Maine. Much of the state gets its drinking water from private wells, and that water isn't held to federal or state standards.
In a voluntary study that included about a quarter of Maine's towns, wells in about 10 communities were shown to contain risky amounts of fluoride—sometimes more than twice the EPA's limit. Fluoride's presence is boosted by the granite under the state, which is packed with the chemical; there's plenty of granite in other New England states as well. An expert tells the Portland Press-Herald that residents should have their water tested, but people only do it "when they buy a house or if they get sick." If there's too much fluoride, reverse osmosis systems can help, but they cost between $1,000 and $2,000. (In better tooth-related news, our cavities could eventually take care of themselves.)