For the first time in more than a half-century, a new standard for how much fluoride should be put in communities' drinking water supply as an aid in preventing tooth decay was proposed Monday by the Obama administration.

The new recommended standard of 0.7 milligrams per liter of water replaces the recommendation of between 0.7 and 1.2 milligrams per liter, which had been in effect since fluoridation started becoming widespread in 1962. Read More Two states' surprising Obamacare success

Water fluoridation has been credited with dramatically reducing the incidence of tooth decay, which in the first part of the 20th century led to many older adults losing most of their teeth, and requiring dentures. The target is being lowered to one, standard level to reduce the amount of fluorosis, a usually mild cosmetic condition of "barely visible, lacy, white markings or spots on the tooth enamel," which children are particularly susceptible to, said Rear Adm. Boris Lushniak, deputy U.S. surgeon general.

The Jacqueline Kennedy Onassis Reservoir in New York's Central Park. Stan Honda | AFP | Getty Images

Fluorosis has become more common in part because of an increase in the use of products, such as toothpaste, mouthwash and teeth strips, that contain fluoride, officials said. Lushniak noted that in some communities, upward of 40 percent of the adolescents have fluorosis. Lushniak called the new standard "the correct measure to help prevent tooth decay and reduce the prevalence of fluorosis." The previous recommended standard was a range because at the time it went into effect there were significant differences in the consumption of drinking water regionally. Consumption of water was higher in the South in the mid-century because of the lack of widespread air conditioning, which in turn led children to drinking more water than their Northern counterparts in summer months. Although the new standard is only a recommendation, it is likely to be taken seriously by the approximately 75 percent of community health systems nationwide that currently put fluoride in their water to lower the rate of tooth decay in the populations. Those systems serve about 210 million people.

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The new level of 0.7 milligrams was first suggested by the Obama administration in 2011. Since then, several panels have reviewed the proposed standard, and considered more than 19,000 public comments that were received in reaction to the suggested change. Some of the comments focused on claims that higher levels of fluoridation had been linked to lowered IQs or increases in cases of attention deficit disorder. Officials said that an extensive scientific review had reviewed no connection between higher levels of fluoridation and those conditions.