Study raises questions about fluoride and children’s IQ

Dozens of cities in the United States and Canada, such as Portland, Ore., and Vancouver, do not add fluoride to city water. Elsewhere in the United States, fluoridation is the norm. As of 2014, per CDC data, two-thirds of people in the United States had fluoride in their drinking water. In 2015, to reduce the risk of mild fluorosis, the Department of Health and Human Services cut its fluoride recommendations almost in half, from 1.2 milligrams per liter to 0.7 milligrams per liter.