Like many Americans my age, I grew up with a positive association to fluoride. Toothpaste commercials told me that fluoride helped prevent tooth decay and that I should brush my teeth with fluoride toothpaste, so I used it every day. The dentist gave me fluoride treatments for my teeth. Fluoride was also added to municipal water supplies, so drinking tap water (and anything made with it) gave me a daily dose of fluoride too. Like most other people, I assumed it must be healthy. Otherwise, why would people add it to toothpaste and water?

Many years ago though, I started hearing rumors about fluoride being potentially unhealthy. I realized I