The practice of adding fluorides to drinking water is widespread and long-standing. Most baby boomers probably never questioned this practice or the assertion that fluoridated drinking water helps to prevent the formation of dental cavities. Today, however, a growing number of people are protesting the recommendation of the World Health Organization, the US Public Health Service, and other groups to fluoridate water. This disagreement is grounded in a belief that fluorides are harmful to human safety and health. Read on to learn more about this controversial issue.
Fluorides are naturally-occurring and can be found in many drinking water sources and in foods. They are used in certain industrial processes and are also found in certain supplements, pharmaceuticals, and pesticides. Finally, fluorides are a common ingredient in many toothpastes and dental rinses.
Fluorides are associated with both beneficial and harmful health effects. While individuals who ingest fluorides in the 0.7 - 1.5 milligram per liter range have a significantly lower risk of developing dental cavities than those who ingest lower concentrations, we know that ingestion of higher concentrations causes dental and skeletal fluorosis, conditions characterized by stained, pitted teeth and inflamed, painful joints, respectively.
The phenomenon of something causing both positive and negative health effects has been recognized since at least the late 1400's when Paracelsus, the founder of toxicology, proclaimed that "all things are poison and nothing is without poison; only the dose makes a thing not a poison." There are countless examples of this principle in everyday life.
For example, while consuming limited amounts of alcohol may decrease your risk of cardiovascular disease, excessive drinking can lead to cirrhosis of the liver and liver cancer. People who take aspirin every day decrease their risk of clot-related strokes but increase their risk of hemorrhagic strokes and gastrointestinal bleeding.
The beneficial and harmful health effects of fluorides described above are based on multiple epidemiological studies that have generally been accepted for decades. The fluoride controversy centers on other studies that suggest that fluorides can disrupt the endocrine system and increase the risk of osteosarcoma, a type of bone cancer that targets young people between the ages of 10 and 30 and adults who are over 60 years of age.
The studies that implicate fluorides as a possible carcinogen are inconclusive. None of the legacy groups* that study and classify carcinogens have seen enough evidence to classify fluorides as confirmed human carcinogens. Rather, they have given these compounds the designation of "not classifiable" (or equivalent).
There are a number of reasons for this less-than-satisfying finding. For example, the epidemiological studies are not able to determine the actual fluoride doses that various populations are exposed to. Animal studies often involve high doses of fluorides that are unrealistic when normalized to human doses. Finally, the various study results often contradict each other - while some results suggest that fluorides cause negative health effects, others do not.
Inconclusive toxicological findings are unfortunately very common. They highlight the complex nature of toxicology and scientific research - and the need for additional research. We believe that more studies on the harmful effects of fluorides, including carcinogencity, will help us to understand this controversial group of compounds. What do you think? Feel free to share your thoughts with us.
* National Toxicology Program
International Agency for Research on Cancer
American Conference of Governmental Industrial Hygienists