Omaha, Lincoln, Ogallala and Council Bluffs do.

North Platte, Lexington and Hastings do not.

Alliance and Imperial in Nebraska and dozens of Iowa towns don’t have to.

Fluoridate, that is.

The debate over whether to add fluoride to drinking water to help prevent cavities in teeth has raged for 60 years.

Now, new rules could add another chapter to the story.

The U.S. Department of Health and Human Services and the U.S. Environmental Protection Agency proposed Friday that the recommended level of fluoride in drinking water be set at the lowest end of the current optimal range to prevent tooth decay.

The standard, since 1962, has been a range of 0.7 of a milligram to 1.2 milligrams per liter of water. The new proposal will recommend a specific level of 0.7 milligram.

Omaha and Council Bluffs water systems slightly exceed 0.7 milligram. Both will reduce levels to meet the new standard if they get official notice to do so.

A lower level is being suggested because of something called fluorosis. The federal Centers for Disease Control and Prevention report that fluorosis — tooth streaking or spottiness caused by too much fluoride in the diet — has become unexpectedly common in teens.

Nearly 23 percent of children ages 12 to 15 had fluorosis in a study done in 1986 and 1987. That rose to 41 percent in the more recent study, covering the years 1999 through 2004.

The CDC has listed water fluoridation as one of the 10 great public health achievements of the 20th century. Tooth decay is painful and unsightly and can lead to other problems.

Health officials have hesitated to call fluorosis a problem. In most children, it’s barely noticeable, they say. Except in the most severe cases, the discoloration is considered an acceptable trade-off for the protection fluoride provides against cavities.

Fluoride is a mineral that exists naturally in water and soil. About 70 years ago, scientists found that people who lived where water naturally had more fluoride had fewer cavities.

Federal officials estimate that about 64 percent of Americans now drink fluoridated water.

The Iowa Department of Public Health said that 92 percent of communities in that state have fluoride in their water, much of its occurring naturally.

Of 595 community water systems in Nebraska, 71 add fluoride to their water, said Jack Daniel of the Nebraska Department of Health and Human Services’ Office of Drinking Water and Environmental Health.

That’s only 11.9 percent. But Daniel noted that those 71 systems cover nearly 65 percent of the state’s population. (Among the 71 is the Metropolitan Utilities District, which serves Omaha, Bellevue, La Vista, Fort Calhoun, Ralston, Bennington and Waterloo, as well as Columbus, Nebraska City, Kearney, Papillion, Plattsmouth, Seward and Valley.)

Forty other Nebraska towns, including Oakland, Alliance, McCook, Imperial and Winnebago, have naturally fluoridated community water systems, so they don’t add anything.

Nebraska law requires communities of more than 1,000 people to fluoridate their water. However, from 2008 through 2010, towns were authorized to opt out with a vote of citizens.

Many did. North Platte, Hastings, York, Grand Island, Chadron and Cozad were among those voting to opt out.

Critics of fluoridated water seized on the proposed change Friday to renew their attacks on it — a battle that dates back to at least the Cold War 1950s, when it was denounced by some as a step toward Communism. Organizations such as Fluoride Action Network say fluoride increases the risk of cancer [FAN has said that it is biologically plausible, especially for osteosarcoma] and even has contributed to blindness [FAN has not said this] and crippling diseases. Critics also say it’s too expensive.

Many supporters no longer think adding fluoride is essential, including dental and medical groups that applauded Friday’s announcement. They note that fluoride these days can be found in a number of products, such as toothpaste, mouthwash, fluoride supplements and fluoride applied by dentists.

In Nebraska, fluoridation long has been a hot-button topic, leading to heated exchanges in the Legislature over the years and recently triggering a recall attempt of officials who voted to fluoridate the local water supply.

After Burwell Mayor Charles Cone and the City Council voted for fluoridation, a petition drive successfully forced a recall election. But Cone and council members Terry Cone and Carolyn DeBaetes survived the November vote and remain in office.

Daniel, of the state health department, said if the EPA mandates a specific lower level of fluoride in water, Nebraska will comply and all state communities with fluoridation will follow suit.

In Omaha, voters approved fluoridation in 1968. A MUD spokeswoman said about 0.5 milligram per liter of fluoride naturally occurs in MUD’s water and the district adds another half-milligram, for a total of 1 milligram.

“We are in the process of lowering the level to 0.8 parts per million, the lowest allowed by current State of Nebraska Health and Human Services regulations,” said Mari Matulka. MUD will consult with the health department on any further adjustments to fluoride in its treatment process, she said.

Council Bluffs Water Works currently adds fluoride to its water, with a level of 1.1 milligrams per liter of fluoride.

Officials in Iowa, too, said changes would be made if the standard is revised.

Federal officials expect to publish final guidance for changes in community water fluoridation by spring.

This report includes material from the Associated Press.