For over half a century now, community water systems have been adding fluoride to drinking water to help reduce the risk of tooth decay. Numerous long-term studies have demonstrated the soundness of this practice, prompting the U.S. Centers for Disease Control to call water fluoridation one of the ten most effective public health measures of the 20th Century.
In the 1960s, after years of study into the teeth-strengthening effects of fluoride, the U.S. Public Health Service recommended that drinking water utilities add fluoride at a rate of between 0.7 and 1.20 milligrams per liter (mg/L) or parts per million (ppm) of water. This recommendation held fast until 2015 when the service changed the recommendation to no more than 0.7 mg/L.
Why the change to guidelines that had been in place for over fifty years? The revision was in response to an increasing occurrence of dental fluorosis. This condition happens when the teeth absorb more fluoride than necessary, leading to discoloration of the surface enamel, creating effects like small white spots or brownish “mottling.”
Dental fluorosis is the only known health condition caused by fluoride. As such, it doesn't damage the tooth itself, and is mainly a cosmetic problem. But it can still be avoided if fluoride intake is kept at moderate levels.
The original recommendation was sound science when first introduced. Since then, though, the prevalence of fluoride in everyday life has grown, with the chemical commonly found in dental care products like toothpastes or mouthrinses, as well as many processed foods and beverages and even infant formula. Our society's overall intake of fluoride has been growing as a result.
The new recommendation came after several years of research to verify water fluoridation levels of 0.7 mg/L would still be effective in the fight against tooth decay while lowering the risk of dental fluorosis. With this adjustment, this important and safe measure for keeping your family's teeth protected against disease is safer than ever.