We know that people worry about calamities that they see on TV way out of proportion to the real risks of those things happening. The oft-cited examples are plane crashes, child abduction, and shark attacks, when the bigger dangers are the car crashes, child abuse, and heart attacks that don’t make the news because they are more common. But people are afraid of a large range of things, which is the subject of a new book by Lise Johnson and Eric Chudler, called Worried? Science Investigates Some of Life’s Common Concerns. An excerpt from the book looks at five substances and one cosmic event, detailing why we worry and what science tells us about the actual risk. One example is fluoride in drinking water. Conspiracy theorists will tell you fluoridated water is a government plot to control the population, while others just think adding chemicals to our water supply is a bad idea. Fluoride can be dangerous …if you ingest too much of it.
Debilitating disease and acute toxicity are clearly undesirable, which is why the Environmental Protection Agency (EPA) has set the upper limit for how much fluoride can be in drinking water at 4 parts per million (ppm). But the existence of an upper limit is not in itself cause for alarm. Dosage is an important factor. Many things that are good for us in small doses are bad for us in large doses. Iron is a good example of this. If you don’t get enough iron, you will be anemic; if you take too much, it will kill you. The same is true of vitamins A, D, E, C, and K. Even too much water is lethal. The fact that fluoride has negative consequences in large doses is not unusual and shouldn’t disqualify its use in any form.
One notable difference between fluoride and the vitamins and minerals listed above is that fluoride is not known to be necessary for human health. It is, however, helpful (again, like a lot of things). Low doses of fluoride reduce the incidence of tooth decay without causing fluorosis. Artificial fluoridation of water is targeted at the sweet spot where there is an observable benefit but minimal (ideally zero) side effects (slight cosmetic fluorosis is considered acceptable).
Read the science behind all six things you might worry about at Lithub. -via Digg