ASHEVILLE — National concerns over teeth discoloration, and in some rare cases bone problems, have led officials to lower fluoride levels in Asheville’s regional water system.

In extreme cases, teeth can even be pitted by the mineral — though many cases are so mild only dentists notice it. The problem is generally considered cosmetic.

“When questions about the acceptable fluoride concentration hit the press around the first of the year, I instructed our water production division to adjust our fluoride feed rate,” Asheville Water Resources director Steve Shoaf said.

Shoaf noted a U.S. Centers for Disease Control study that found 2 out of every 5 adolescents have tooth streaking or spottiness because of too much fluoride.

The water resources director said he lowered the fluoride from 1 milligram per liter to 0.7 milligrams per liter, a new proposed recommendation by the U.S. Department of Health and Human Services.

One milligram per liter is equivalent to less than a gallon of water in an Olympic-size swimming pool, he said.

Officials did not announce the change Jan. 10. It affects about 125,000 city and noncity residents.

Asheville-area dentists said the adjustment made sense considering the recent studies. They also emphasized the role of fluoride in preventing tooth decay, particularly in young people.

But the change also has emboldened local fluoride opponents, who said it’s not right to force any kind of treatment on people and that the additive is dangerous at even low levels.

Occurs naturally

Fluoride occurs naturally at varying levels in well water and springs. In the mid-20th century, public health experts pushed for its addition to municipal water after noticing low cavity rates in people whose water sources were high in fluoride.

Health experts have called it one of the greatest public health victories last century, particularly for its reach among poor, who often have less access to dental care.

The latest research shows the fluoride’s effect is largely topical and is most effective when it comes in contact frequently with the mouth, said Dr. Kevin Buchholtz, the west regional dentist supervisor for the N.C. Department of Health and Human Services.

And while that can be helpful to older adults, “I would say that children benefit the most from water fluoridation,” Buchholtz said, pointing to early tooth development.

Asheville voters asked in a 1965 referendum that fluoride be added to the city system and reaffirmed that decision in a 1967 referendum.

Systems that add fluoride must comply with government standards, which since 1962 has been a range of 0.7-1.2 milligrams per liter.

But following the recent study in adolescents, health and human services said it would propose that be lowered to 0.7. And the Environmental Protection Agency will review whether the maximum cutoff of 4 milligrams per liter is too high.

A scientific report five years ago said that people who consume a lifetime of too much fluoride — an amount over EPA’s limit of 4 milligrams — can lead to crippling bone abnormalities and brittleness.

Opponents tried in 2008

Since its early addition to water systems, small but vocal groups have opposed fluoride, citing reasons ranging from its supposed danger to government plots to pacify the populace.

In 2007, such critics convinced Brevard City Council members to have the additive removed.

In Asheville, opponents tried unsuccessfully in 2008 to get fluoride removed.

To do so, they were told, voters would have to approve it in a referendum. But council members swayed by a crowd of area dentists speaking against removal, voted 6-1 not to set a referendum.

Dr. John Wilson, an internist with Asheville Alternative Medicine and one of the three who asked to take fluoride out of the water, said council members were overwhelmed by “the preponderance of opinion,” not by good science.

Wilson said there is no good study that shows fluoride is behind reduced national cavity rates over the last few decades. Instead, he said fluoride acts as a neurotoxin and causes thyroid problems.

“The other point I would make is, it’s medicating people against their will,” he said.

Regarding the recent reports of unusually high incidents of fluorosis in kids ages 12-15, Wilson disagreed that it was only cosmetic. Instead, the splotchy tooth condition is an indication of severe underlying health problems, he said.

Fluorosis: not usually bad

But most dentists say fluorosis is usually hard to notice and is normally a sign of strength. Some have described patients with very visible fluorosis as having “bullet-proof” teeth.

“Those teeth are actually stronger. They are resistant to decay,” said Dr. Jenny Jackson, who has practiced pediatric dentistry in Asheville since 2007.

Of the more than 1,000 patients she sees, Jackson says it’s not uncommon to encounter the mild form of fluorosis, appearing as “white striations” that are sometimes noticeable only to a dentist.

Four or five of her patients have a more pronounced form with brown patches. She said she has not encountered the most extreme form in which teeth are very pitted and actually weakened.

Jackson said the key is finding a balance, especially considering the many sources of fluoride today.

When the standards were set, health experts thought less fluoride should be added in warmer climates since people drank more water. But air conditioning has changed that.

Now fluoride can be gotten through toothpaste, beer and even some food.

Still, the need for cavity prevention remains important, she said, noting that in the past year she had to perform two emergency surgeries on children with severe tooth decay. Left untreated, they could have suffered from infections, brain swelling and possibly even death, she said.

“I’ve actually had more children in my practice in the past year that have almost lost their lives from severe cavities, where the cavities have gone systemic,” she said.

The Associated Press contributed to this report.