While low levels of fluoride prevent tooth decay and promote oral hygiene, high fluoride levels, if unaddressed, have been found to cause pitted teeth and brittle bones. A 2012 review article examined some two dozen relevant studies performed outside the U.S.—mostly in China but also a couple in Iran—and found that high fluoride exposures reduce children’s IQs by an average of about seven points. The survey, in which about 25 percent of all Maine towns participated, was reported by Scientific American magazine Wednesday. The results showed that Dedham in northern Hancock County had the highest percentage of wells that tested above state guidelines, at 37.8 percent. The U.S. Centers for Disease Control and Prevention recognizes water fluoridation as one of the top 10 greatest public health achievements of the 20th century. Yet newly available data, released in recent months, indicates that in some 10 communities in the state wells harbor dangerously high levels of fluoride. According to the magazine, the tests were done for homeowners who voluntarily submitted samples to the state for testing, and were not a random or complete sampling of private wells in Maine. The dangerously high levels were found to exceed levels recommended by the U.S. Environmental Protection Agency, and were similar to levels referenced in studies done in communities in China and Iran that linked high fluoride exposure to decreased IQ levels. “The sort of levels we’re talking about that are high in China are the sort of levels we see in some private wells,” Andrew Smith, Maine state toxicologist, told the magazine. The U.S. Department of Health and Human Services has proposed adding fluoride to water in concentrations no greater than 0.7 milligram per liter to avoid any unwanted health effects. Many Maine communities have been adding fluoride to their public water since the 1950s and 1960s, although recent federal guidelines have prompted some water districts to reduce their levels. The potential health concerns around arsenic are so much better publicized than fluoride, suggesting that fewer people will protect themselves from excessive fluoride concentrations. Researchers recently surveyed residents of central Maine whose well water contains high levels of arsenic—an odorless, tasteless element that can cause maladies including cancer, blindness and numbness in hands and feet. As for mitigation, commercially available filters, such as Brita, do not remove fluoride, according to Gelberg, who said the only effective solution is to install a reverse osmosis system, at a cost of $1,000 to $2,000.
– 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.)