Twenty years ago, parents in the little town of Oakley, Idaho began to complain that their children were growing up with dark brown, pitted teeth. After long investigation, curious dentists found that the mottling was caused by fluorine (a relative of iodine, chlorine, bromine) in the town's new water supply. At considerable expense, Oakley parents dug another set of wells. Ten years later they proudly reported that children drinking "pure" water from the new wells had teeth white and glistening.
Taking a lesson from Oakley, the U. S. Public Health Service for years sent warnings to 300 other "mottled enamel areas" from...