Ever since fluoridation became widespread in the 1950s, cavities in kids have fallen drastically. The effort is considered one of the ten greatest public health achievements of the 20th century. But it’s also one of the most controversial.  At really high doses, fluoride is toxic – it can calcify your ligaments and joints and even fuse your spine. It also potentially has impacts on our brains. There’s a small but growing body of research suggesting that fluoride can inhibit intelligence in children.  This is still unsettled and hotly debated science but, as host Nate Hegyi finds out, in our polarized and increasingly digital world… unsettled science can quickly become doctrine.  Featuring Rene Najera, Philippe Grandjean and Mark Hartzler For a transcript and full list of credits, go to outsideinradio.org.  SUPPORT Outside/In is made possible with listener support. Click here to become a sustaining member of Outside/In.  Follow Outside/In on Instagram or join our private discussion group on Facebook. LINKS The CDC has a website that tells you how much fluoride is in your drinking water.  Here’s the reasoning behind the U.S. Public Health Service’s recommended limit for artificially fluoridating water.  The National Toxicology Program suggests that a child’s IQ could be impacted if they or their pregnant mother ingests more than 1.5 ppm of fluoride in their water.  Philippe Grandjean’s peer-reviewed study suggests that the safe level of fluoride in water for pregnant women is much lower than what the U.S. Public Health Service recommends. The American Academy of Pediatrics and the American Dental Association have cast doubt on the National Toxicology Program’s conclusions and say that the fluoride levels in U.S. waters are safe.  A U.S. district court judge ordered the Environmental Protection Agency to take a second look at its limits for fluoride in the water, citing the National Toxicology Program’s monograph.  Learn more about your ad choices. Visit megaphone.fm/adchoices