The U.S. government recently announced it would lower its recommended level of fluoride for public drinking water after learning that some kids are getting too much, causing white splotches to appear on their teeth.

According to ABC News, this is the first change to the recommended fluoride level in more than 50 years, since the government first advised water systems to add fluoride.

Since 1962, the government has recommended that cities fluoridate their water at a level between 0.7 milligrams per liter for warmer regions, where people drink more water, to 1.2 milligrams in cooler areas. The revised standard recommends 0.7 milligrams per liter everywhere.

The government’s decision comes after one study found that approximately two out of five adolescents have tooth streaks or white splotches. These streaks and spots don’t indicate any dental health problems — it’s primarily a cosmetic concern, according to Deputy Surgeon General Boris Lushniak. It’s no coincidence that demand for teeth whitening procedures has skyrocketed by more than 300% over the last five years.

Additionally, unpublished federal research found that there is no regional difference in the amount of water people drink.

Fluoride is a mineral naturally found in soil and groundwater. More than 70 years ago, scientists first discovered that people who drank naturally fluoridated water had fewer cavities, as well. Since then, public water fluoridation has become widespread; nearly 75% of Americans drink fluoridated water.

Because fluoride is now added to toothpaste, mouthwash and other dental hygiene products, however, some people are now getting too much fluoride.

Fluoridated public water has been repeatedly linked to dramatically reduced rates of tooth decay, and is completely safe to drink. Kathleen O’Loughlin, executive director of the American Dental Association, called water fluoridation a public health success, and recommended that communities continue to add fluoride to their water.

The government’s change comes after four years of research and listening to public opinion, according to the Chicago Tribune.