He says groups like the CDC have determined safe levels, but, like anything, you don't want too much.
"Any chemical is going to be toxic at a high enough concentration," Eichhorn told us, "A good example is sodium we think we need to stay away from sodium is in fact important to have in our body just not at too high of concentration."
We also talked with chemist and former KU professor Albert Burgstahler. While many health organizations endorse fluoride, Burghstahler says he drank five to six quarts of fluoridated water daily...and got sick.
"I know for a fact, it was verified within me," Burgstahler said. "I had a low thyroid function that was reversed from getting away from fluoridated water."
The CDC says the most common side effect from higher-than-recommended fluoride intake in the US is Dental Fluorosis. It causes spots, streaks - or in the worst cases - pits in tooth enamel.