JEFFERSON CITY, Mo. – Oral surgeon Jonathan Hanson was reading a routine water quality report produced annually by the local water district when he noticed the fluoride level seemed unusually low.

So Hanson, who helped persuade officials to start fluoridating the water in the 1980s, began calling around. What he learned shocked some dentists, doctors and parents.

Cole County Public Water Supply District No. 1, which serves a fair portion of Missouri’s capital city, had quietly quit fluoridating its water in 2003 – and neither the state nor many of its customers had noticed.

Based on Department of Natural Resources data analyzed by The Associated Press, the water district appears to be the only one statewide in recent years to have stopped adding the chemical compound that medical professionals acclaim as a vital cavity preventer.

“Hopefully, they’re going to realize that this is an important public health measure, and it can be corrected without too much problem,” said Hanson, who plans to attend an Aug. 9 water board meeting where the fluoride policy will be reconsidered.

Since the Jefferson City News-Tribune first reported the fluoride abandonment a little over a week ago, water district manager David Kempf has taken more calls about fluoride than he normally receives in an entire year. Kempf is getting the sense he may have made a mistake.

“We’re probably going to rethink our decision,” Kempf said Tuesday. “It’s pretty well been lopsided: People want the fluoride.”

Fluoride was first added to a public water supply, in Grand Rapids, Mich., 60 years ago. Now, about two-thirds of Americans drink tap water with one part of fluoride for every one million parts of water – the ideal amount, according to the U.S. Public Health Service.

In Missouri, optimally fluoridated water is available to 78 percent of the 4.8 million people served by municipal, subdivision or public water districts, according to DNR figures. The state has about 5.6 million people.

Although some remain skeptical about its health benefits, the American Dental Association cites studies showing that water fluoridation can reduce tooth decay by 20 percent to 40 percent. The best source is tap water, because bottled water generally does not contain fluoride.

In retrospect, Kempf said, he probably should have surveyed his customers before discontinuing fluoride. But at the time, he said, it seemed like a practical step.

In November 1989, the state spent about $3,500 on fluoridation equipment for the Cole County water district, according to records at the Department of Health and Senior Services. But the department discontinued that grant program after 2003 – about the same time the Cole County equipment was in need of replacement.

Kempf said he also learned in 2003 that his four-person water district crew was supposed to conduct daily checks of the fluoride levels at each well.

That state requirement had been in place for more than a decade, said Keenan Patterson, an environmental engineer at the Department of Natural Resources. But to comply would have meant working weekends and holidays for Kempf’s staff – something Kempf said would have cost overtime pay or forced people to take off weekdays.

Instead, Kempf decided to drop the fluoridation.

Patterson was heading to the dentist with a cavity about the same time he learned that the Cole County water district where he lives had quit fluoridating its water two years ago. He adjusted the state-maintained list accordingly.

While the Cole County district quit doing so, department records show that more than a dozen other public water systems began adding fluoride in the past five years, including Joplin, which is beginning this week.

“The trend is toward doing fluoride, but it’s something that all our large systems have been doing for a long time already,” Patterson said.

Officials at the state health department also were unaware until recently of the Cole County fluoridation decision. Following staff reductions and budget cuts, the agency is trying to rebuild its program that encourages public water fluoridation, said Harold Kirbey, chief of the department’s Primary Care and Rural Health Unit, which oversees oral health.

The idea of the old grant program was that communities would continue fluoridating after the state helped with startup costs, Kirbey said.

Now, “one of the things we’re really trying to do is get a better handle on the status of the supplies out there – who’s fluoridating, who’s not, and who’s fluoridating properly,” he said.