Sure, the United States has had a bit of an adjustment when it comes to fluoridated drinking water. But don't get too excited if you're a fluoridation foe, because it's more of a teeny shift of weight than a full about-face.
In January 2011, the United States Department of Health and Human Services (HHS), along with the Environmental Protection Agency (EPA), announced the range of fluoride in water should move from 0.7 to 1.2 milligrams per liter of water to .7 milligrams per liter. The EPA decided to review their evaluation of fluoride after the National Academies of Science did a comprehensive review of the effects of fluoride on dental and skeletal structure, which also addressed the wider range and use of fluoridated products in the United States.
Now here's where things get a little tricky: while HHS recommends .7 mg per liter, the EPA has an "enforceable" standard of 4.0 mg per liter, and a "secondary standard" of 2.0 mg per liter. Why the confusion? The EPA is in charge of making sure that no one is exposed to excessive fluoride, while HHS is tasked with providing optimal public health recommendations that give the most benefit with the least harm [source: EPA].
So while HHS recommends the lower .7 mg standard, the EPA is still reviewing whether they need to lower their enforceable or secondary (ie: recommended but not required) standards. In the next section, we'll see how exactly we can add or remove fluoride should we need to.