WEDNESDAY, March 22 (HealthDay News) — The current maximum level of fluoride allowed in U.S. drinking water is too high, and may cause health problems such as bone fractures and, ironically, erosion of tooth enamel.

That’s the conclusion of a panel from the National Academy of Sciences commissioned by the U.S. Environmental Protection Agency (EPA) to assess the safety of fluoride levels in drinking water.

“Our committee unanimously concluded that EPA should lower the maximum contaminant level goal (MCLG) for fluoride in drinking water,” said the committee’s chairman, Dr. John Doull, a professor emeritus in the department of pharmacology, toxicology and therapeutics at the University of Kansas Medical Center.

However, the committee didn’t recommend a specific level to the EPA, but instead urged the agency to conduct risk assessments before devising new regulations.

For some, the panel’s conclusions, coupled with the lack of solid recommendations, amounted to too little, too late.

“They say the EPA should lower the standard, but they don’t say to what,” said former EPA scientist and anti-fluoride advocate Bob Carton. Since the committee concluded that fluoride can cause health problems, he said, the bigger question is, “Why are we still pushing to put fluoride in water?”

Fluoride has been added to many community water supplies since 1945, with the goal being the prevention of cavities. According to the American Dental Association’s Web site, the fluoridation of water reduces the amount of dental cavities by 20 percent to 40 percent.

The amount of fluoridation considered optimal to achieve this reduction in cavities is 0.7 to 1.2 milligrams per liter of water (mg/l). Most communities don’t add artificial fluoride above these levels, although some small communities in Indiana, Kentucky, Minnesota, North Carolina, Vermont, Virginia and West Virginia do, according to the report. However, fluoride also occurs naturally, and in some parts of the country is present in much higher amounts than is considered safe.

The current maximum allowed by the EPA is 4 mg/l. According to the report, more than 200,000 people in the United States live in areas where natural fluoridation in water exceeds the EPA maximum.

While drinking water is the largest source of fluoride exposure, fluoride can also come from foods, toothpaste, certain mouthwashes and dental procedures.

In a statement released Wednesday, the American Dental Association noted that the new report “only addresses the levels of naturally occurring fluoride in drinking water that exceeds the EPA’s current recommendations. The report in no way examines or calls into question the safety of community water fluoridation, which is the process of adding fluoride to public water supplies to reach an optimum level of 0.7 – 1.2 ppm in order to protect people against tooth decay.”

The ADA said it remains a “strong supporter of community water fluoridation.”

Too much fluoride can have adverse effects, however. In children under 8 who are exposed to levels higher than 4 mg/l when their teeth are developing, severe enamel fluorosis can occur. Besides being cosmetically unattractive, severe enamel fluorosis strips the teeth of enamel and makes dental decay more likely, the report said.

Severe enamel fluorosis occurs in 10 percent of children who live in communities where the water fluoride levels are 4 mg/l or higher. In those same communities, 15 percent of the children will develop mild-to-moderate fluorosis, which isn’t as destructive to the teeth, but is cosmetically unappealing, according to the report.

“It causes pitting and cracking of the teeth. You end up with horrible-looking, dysfunctional teeth,” said Carton.

Of more concern, however, is the possibility that fluoride may contribute to bone fractures, skeletal fluorosis and possibly bone cancer. The committee concluded that high levels of fluoride are likely to increase the risk of bone fractures.

“Overall, there was a consensus that under certain conditions, fluoride can weaken bone and increase the risk of fracture,” said Doull. Because fluoride accumulates in bone over a lifetime, he said those who are exposed to 4 mg/l in their water would be more likely to have bone fractures than people whose water only contains 1 mg/l.

The committee felt that the evidence wasn’t sufficient to make conclusions regarding the risk of skeletal fluorosis or bone cancer. The committee also examined fluoride’s effect on the reproductive, neurological, endocrine, gastrointestinal, kidney, liver and immune systems. Again, it found the evidence insufficient to make conclusions as to possible health threats to these systems. The panel did note, however, that people with kidney disease might be more susceptible to high levels of fluoride because they often drink more water.

The panel also recommended that the EPA look at the amount of water people drink, currently assumed to be 2 liters or less per day. But, the committee suggested that some people may be consuming more than that amount, such as people who work outdoors, athletes and people with certain medical conditions. Additionally, infants and children may be at a higher risk because their exposure is greater due to their small size.

Carton said he believes that skeletal fluorosis may be more prevalent than is realized. In its earlier stages, it causes calcifications in the ligaments and tendons, which would cause pain but wouldn’t interfere with functioning until it advanced further, he said.

If you’re concerned about fluoride levels in your water, you can contact your local water department and ask what the levels are. If they’re above 4 mg/l, they’re definitely too high, according to the panel’s report. The potential risk of levels between 2 mg/l and 4 mg/l is still in question, and this particular committee wasn’t asked to look at those levels.

Committee member Charles Poole, an associate professor of epidemiology at the University of North Carolina, Chapel Hill, stressed that once fluoride levels drop to under 2 mg/l, extreme enamel fluorosis is virtually non-existent.

He added, however, that even those levels might not be low enough to protect against all adverse health effects.

Poole said home filtering systems are available, but their ability to filter fluoride varies widely.

If you have children, it’s a good idea to supervise them while they’re brushing their teeth to ensure they don’t swallow toothpaste and with it extra fluoride.