Fluoridation began in 1945 with four trials which did not show that fluoridation prevents cavities.
Since then no credible study of fluoridation as a preventive of cavities has indicated that it is effective.
As shown in data collected by the World Health Organization from the early 1960s to 2004 the prevalence of cavities in children steadily decreased equally in eighteen industrialized countries.
Fourteen of those countries did not have fluoridation. So the decrease was not due to fluoride in drinking water.
Furthermore many studies have shown that after stopping fluoridation the prevalence of cavities either remained the same or decreased. All of these studies have been published in reputable journals.
Fortunately cavities can be prevented in other ways.
Safety of fluoridation is a more important issue. The chemicals used to fluoridate dissociate almost completely, releasing the fluoride ion in the treated water.
That fluoride combines in the stomach with hydrogen ions to form hydrofluoric acid (HF). HF crosses the walls of the stomach and intestines and enters the blood which distributes it to all the tissues of the body.
Fluoride makes many enzymes, the natural chemicals that govern the chemical reactions of all tissues, less effective.
Also fluoride effects cell walls in a way that disrupts the normal effects of hormones and other chemicals inside the cells.
Consequently we should expect to find negative effects on many different tissues and organs and we do find such effects.
It should be recognized that substantially numerous groups in the population of a city are particularly sensitive to the possible harms of fluoridation.
These groups include infants, diabetics, people with kidney disease, the elderly.
Besides effectiveness and safety, there is the ethical question. In medicine and in governance it is unethical to force on a person a drug without their informed consent.
James S. Beck, MD, PhD
Professor Emeritus of Medical Biophysics
University of Calgary