About 40 percent of American teens have dental fluorosis,4 a condition referring to changes in the appearance of tooth enamel—from chalky-looking lines and splotches to dark staining and pitting—caused by long-term ingestion of fluoride during the time teeth are forming.
In some areas, fluorosis rates are as high as 70-80 percent, with some children suffering from advanced forms.
The former recommendation called for a fluoride level of 0.7 to 1.2 milligrams per liter (mg/L) of water. The new upper limit set by the US Department of Health and Human Services (HHS) is 0.7 mg/L, to prevent these visible signs of toxic overexposure.
Read more http://www.wakingtimes.com/2015/05/12/us-government-admits-americans-have-been-overdosed-on-fluoride/