Tea drinking remains popular in the United States and increasingly is suggested to promote health. We caution that skeletal fluorosis can result from consumption of excessive amounts of instant tea because of substantial fluoride levels in some commercial preparations.
A 52-year-old white woman consulted in 1998 for dense lumbar vertebras discovered after twisting her back. Spinal discomfort and stiffness for 5 years reflected “disc disease.” She had never had a fracture. Chest radiographs after exposure to chlorine while manufacturing soap and bleach were unremarkable 16 years previously. She recounted no other chemical or heavy metal exposure. Onset of menopause was at age 46 years, after which she had estrogen injections, and then took oral estrogen-methyltestosterone for 3 years. She also took 600 mg of calcium twice daily for 4 years and a multivitamin daily for 6 months. Review of family history revealed no skeletal problems. Only intake of unfiltered well water suggested fluorosis.
The patient appeared well. Spine percussion and rib compression were painless. There was no hepatosplenomegaly. Neurologic examination was intact.
Radiographs from 1993 and 1998 documented the appearance of marked osteosclerosis and cortical thickening throughout the entire spine (especially the lumbar region) and pelvis during this 5-year period (Figure 1). The ribs were similarly affected. Radiographs of the calvarium, hands, proximal femora, and knees were unremarkable. Magnetic resonance imaging showed an L5-S1 herniated nucleus pulposus but no marrow changes. Dual-energy Xray absorptiometry documented markedly elevated bone mineral density in the lumbar spine but normal density in the hip (Table 2).
Hemogram values; serum calcium, phosphate, parathyroid hormone, alkaline phosphatase, 25-hydroxyvitamin D, and creatinine levels; and results of protein electrophoresis were unremarkable. The erythrocyte sedimentation rate was 18 mm/h (reference, 30 mm/h). Test results for antibodies to hepatitis C virus were negative.
Skeletal discomfort intensified during the subsequent year, and included new neck and scapular pain and elbow and knee arthralgias. Bone and joint pains, acquired axial osteosclerosis, well water, soap manufacturing, and periodontal disease suggested skeletal fluorosis. Results of iliac crest marrow aspiration and biopsy were consistent with this disorder, and showed normocellular marrow, markedly thickened cortical and trabecular bone, and increased osteoid seam wall thickness. A 24-hour urine collection contained substantial amounts of fluoride at 14 mg/g creatinine, verified at 19 mg/g creatinine (reference, 3 mg/g creatinine) (Figure 2).
The patient had begun use of unfiltered well water in 1989. The 2.8 ppm (mg/L) fluoride level reported for water from her tap did not exceed the Environmental Protection Agency (EPA) limit of 4.0 ppm. She had always brushed with fluoridated toothpaste, and for 6 months she had used fluoride-containing mouthwash, but neither dentifrice was intentionally swallowed. There was no exposure to pesticides or fertilizers. She did not drink mineral water or wine, live near a mine, and rarely used Teflon-coated pots. However, 3 months after relocating to where well filtration produced 0.24 ppm of fluoride at the tap (World Health Organization guideline limit, 1.5 ppm), urinary fluoride levels decreased little to 13 mg/g creatinine (Figure 2).
Then, the patient reported drinking 1 to 2 gallons of double-strength instant tea (Lipton; Unilever Bestfoods North America, Englewood Cliffs, New Jersey) throughout the day during her entire adult life. Her husband consumed none. In 1991, she switched to the decaffeinated form of the product. We verified the recipe (1 full measuring cup for each gallon of water). The first well’s unfiltered water provided approximately 11 to 22 mg of fluoride daily, which was sufficient to cause mild skeletal fluorosis. However, analysis of a regular-strength preparation of the instant tea in distilled water using ion chromatography (St. Louis Testing Laboratories, Inc.; St. Louis, Missouri) showed a fluoride concentration of 3.3 ppm. Hence, her beverage contained an additional 26 to 52 mg of fluoride each day from tea. Total fluoride exposure was 37 to 74 mg per day.
In 1999, her spine and hip density had increased slightly (Table 2). She then switched to lemonade. Soon after, urine fluoride levels nearly corrected at 3.3 mg/g creatinine (Figure 2).
In 2000, her urine fluoride level was 2.4 mg/g creatinine, but she still reported generalized aches accompanied by worse stiffness, especially in the shoulders, neck, back, and knees. Spine and hip density remained unchanged over the next 3 years (Table 2). However, by 2003 she felt completely well and urine fluoride level was 2.2 mg/g creatinine (Figure 2).
To better assess the fluoride levels in instant teas, we commissioned two independent testing laboratories (St. Louis Testing Laboratories, Inc., St. Louis, Missouri; and Kiesel Environmental Laboratories, St. Louis, Missouri), each using ion-specific electrodes with known additions methodology,15 to assay 10 brand-name products purchased at a local supermarket. The teas were made on separate occasions at regular strength per label directions and using distilled water.
Mean fluoride concentrations in the tea solutions (Table 3) ranged from 1.0 to 6.5 ppm. One preparation exceeded the EPA safety limit of 4.0 ppm for drinking water, and several surpassed the Food and Drug Administration (FDA) limit of 1.4 to 2.4 ppm for bottled beverages.
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There are few reports of skeletal fluorosis in the United States. However, screening for osteoporosis with dual-energy X-ray absorptiometry has increased the detection of hyperdense skeletons. Our patient manifested the aches and joint stiffness associated with skeletal fluorosis. Nonetheless, the little calcification of ligaments or tendons and few exostoses despite marked axial osteosclerosis were atypical. The region where she lived—Missouri—is not endemic for fluorosis, and the fluoride level (2.8 ppm) in the water from the first well did not exceed safety limits. Therefore, the elevated level of fluoride in her urine was at first puzzling. When water filtration was not the remedy, the discovery of her excessive consumption of instant tea and the substantial amount of fluoride in some commercial formulations led us to suspect involvement of these two factors. Indeed, the high urinary fluoride levels were corrected upon stopping the intake of instant tea, and skeletal symptoms resolved several years later.
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Our concern is that skeletal fluorosis might result from drinking instant teas, especially when excessive volumes in hot environments or extra-strength preparations are consumed, or when fluoridated or fluoride-contaminated water is used. FDA requirements for bottled beverages or water packaged in the United States stipulate against fluoride levels in excess of 1.4 to 2.4 ppm, depending on the annual average maximum daily air temperature where the products are sold. The catechins (antioxidant flavonoids), phytoestrogens, and other components found in tea are reported to have beneficial effects. Our encounter
with this patient calls for better understanding of the amounts and systemic effects of fluoride in various teas.