Nearly 70 percent of U.S. residents who get water from community water systems now receive fluoridated water, according to a report published Thursday by the U.S. Centers for Disease Control and Prevention (CDC).

The proportion of the U.S. population receiving fluoridated water, about 184 million people, increased from 65.8 percent in 1992 to 69.2 percent in 2006, said the report.

The percentage of people served by community water systems with optimal levels (which are defined by the state and vary based on such things as the climate) of fluoridated water ranged from 8.4 percent in Hawaii to 100 percent in the District of Columbia, according to the report.

"Community water fluoridation is an equitable, cost-effective, and cost-saving method of delivering fluoride to most people," said William Maas, director of CDC's Division of Oral Health. "We've seen some marked improvements; however, there are still too many states that have not met the national goal. The national goal is that 75 percent of U.S. residents who are on community water systems be receiving fluoridated water by 2010."

Fluoride, a naturally occurring compound in the environment, can reduce or prevent tooth decay. Adding or maintaining tiny levels of fluoride in drinking water is a safe and effective public health measure to prevent and control tooth decay (dental caries). The second half of the 20th century saw a major decline in the prevalence and severity of dental caries, attributed in part to the increasing use of fluoride.

Based upon studies and a systematic review, the new report suggests that fluoridation resulted in a median 29.1 percent relative decrease in tooth decay in the United States.

(Xinhua News Agency July 11, 2008)