Instant tea, one of the most popular drinks in the United States, may be a source of harmful levels of fluoride, researchers at Washington University School of Medicine in St. Louis report.
The researchers found that some regular strength preparations contain as much as 6.5 parts per million (ppm) of fluoride, well over the 4 ppm maximum allowed in drinking water by the Environmental Protection Agency and 2.4 ppm permitted in bottled water and beverages by the Food and Drug Administration.
The discovery stemmed from the diagnostic investigation of a middle-aged woman suffering from spine pain attributed to hyper-dense bones. Testing for the cause of her symptoms revealed the patient had high levels of fluoride in her urine. She then disclosed a high consumption of iced tea--claiming to drink one to two gallons of double-strength instant tea throughout the day--which led the researchers to test for fluoride content in several brands of instant tea available on grocery store shelves.
Each of the teas was tested as a regular-strength preparation in fluoride-free water, and each contained fluoride, with amounts ranging from 1.0 to 6.5 parts per million. The study is reported in the January issue of The American Journal of Medicine.
"The tea plant is known to accumulate fluoride from the soil and water. Our study points to the need for further investigation of the fluoride content of teas," says Michael Whyte, M.D., professor of medicine, pediatrics and genetics. "We don't know how much variation there is from brand to brand and year to year."
In many communities in the United States, fluoride is added to drinking water to help prevent tooth decay. However, the Public Health Service indicates that the fluoride concentration should not exceed 1.2 ppm.