This is a tale of a Missouri woman, a mysterious bone disease, and too much of a good thing.

The year was 1998. The 52-year-old suburban St. Louis woman with a stiff spine and aching back had already been to several doctors. Most told her she had disc disease. But Dr. Michael P. Whyte, a bone specialist at Shriners Hospital for Children and at Washington University, discovered the real problem.

She had a disease that afflicts people in remote regions of Tibet, Mongolia and China. Skeletal fluorosis, it was called.

Skeletal fluorosis happens when people are exposed to high levels of fluoride for long periods, causing the chemical to creep into bones and replace calcium. The bones become dense, weak and brittle. Sometimes the disease causes ligaments to harden and changes bone structure, causing pain and crippling.

In countries where the disease is endemic, water drawn from wells is often contaminated with fluoride from surrounding rocks. In the United States, where drinking water is filtered, low levels of fluoride is added to prevent tooth decay. But that’s not enough fluoride to produce disease.

Whyte set out to find the source of the fluoride in his patient’s painful bones. He reported a study of her case in the January issue of the American Journal of Medicine.

The woman, who declined to be interviewed, used toothpaste and mouthwash with added fluoride, but didn’t swallow the substances. Whyte ruled them out. She rarely used Teflon-coated pans. That ruled out another potential source of fluoride exposure. Pesticides, chewing tobacco, wine and some sparkling mineral waters also may contain fluoride, but the woman didn’t have much exposure to those either.

The unfiltered well water at the woman’s suburban home contained 2.8 parts of fluoride per million parts of water, higher than recommended, and probably enough to cause mild disease over decades. But the level was not high enough to account for the excessive amount of fluoride in the woman’s urine, Whyte said.

And then the woman mentioned an unusual habit. She drank one to two gallons of double-strength instant tea every day of her adult life, she told the doctor.

Studies of people in Tibet and other areas where people drink large amounts of “brick tea” have shown that the beverage can be a significant source of fluoride, even leading to skeletal fluorosis. Brick tea contains mature leaves, berries and twigs of the tea plant, Camellia sinensis. Those parts of the plant often contain high levels of fluoride that tea plants absorb from the soil, Whyte said. Instant tea is often made from brick tea.

Whyte tested the woman’s tea and found that her beverage of choice added 26 milligrams to 52 milligrams of fluoride to her diet each day. She drank a total of 37 milligrams to 74 milligrams of fluoride every day by Whyte’s calculations.

The Environmental Protection Agency allows up to 4 parts of fluoride per million parts of drinking water, based on the calculation that it takes at least 20 milligrams of fluoride per day every day for 20 years to produce crippling skeletal fluorosis. The Food and Drug Administration permits only 2.4 parts of fluoride per million parts of bottled water.

The World Health Organization sets the optimal level of fluoride in drinking water at 1 part of fluoride per million parts of drinking water (equal to 1 milligram per liter of water), to 1.2 parts of fluoride per million parts of water. It sanctions an upper limit of 1.5 parts of fluoride per million parts of water. The U.S. Public Health Service says the concentration of fluoride in drinking water should not exceed 1.2 parts of fluoride per million parts of water.

Whyte and his colleagues bought several jars of instant tea from a local supermarket and sent them to two independent laboratories in St. Louis for testing. The teas contained between 1 part of fluoride per million parts of water and 6.5 parts of fluoride per million parts of water, some that exceed levels considered safe by government agencies.

Consumers shouldn’t be alarmed by the results of the study, Whyte said. The amount of fluoride in tea fluctuates from batch to batch even from the same manufacturer, he said. The fluoride levels reported in the study are a snapshot of the range of concentrations that may be found on a grocery shelf and should not be generalized, he cautioned.

“This is one look in one city at one shelf at one time,” Whyte said.

The woman’s symptoms improved over a five-year period once she switched to lemonade, Whyte said.

Most tea drinkers have nothing to fear, said Dr. Michael Kleerekoper, a professor of medicine at Wayne State University in Detroit. Drinking tea within normal limits will probably not cause any health problems, he said.

“Excess of anything is no good for you,” Kleerekoper said.

(St. Loui