Water fluoridation is declining, not just from changes in the scientific understanding of its effects, but also as a result of financial pressure on cities. Among the dozen or so U.S. cities that have ended water fluoridation since summer, most have cited the cost of fluoridation as the main factor in the decision.
That cost can be substantial — around $2 a year per resident in a small city. When a city is under pressure and having to decide which employees to lay off, suddenly expenses that were previously taken for granted, like fluoridation, come under closer scrutiny.
Fluoride in water strengthens teeth in children between the ages of 6 and 11, but it can be toxic to children under the age of 6 and is more harmful than helpful in adults. Reference levels of fluoride in U.S. drinking water were lowered from 1 part per million to 700 parts per billion because of concerns about the adverse health effects, which include various forms of damage to teeth and bones. Probably the ideal level that balance out the benefits and risks is still lower, around 125 parts per billion. Nearly half of large U.S. drinking water systems add fluoride.