More than 200 million people in the United States live in areas where fluoride is added to tap water. According to the most recent data available, 24 other countries around the world — including the United Kingdom, Brazil and Canada — add fluoride to their drinking water supplies, and many other jurisdictions end up ingesting fluoride via naturally occurring deposits in their water sources.
Water fluoridation has been lauded as one of the top public health achievements of the 20th century by the U.S. Centers for Disease Control and Prevention (CDC). But the practice has long been controversial, with vocal opponents arguing that the water fluoridation has adverse health or cognitive impacts.
