It has been known since the 1930s that ingesting too much fluoride can cause stiff and painful joints. According to scientists who have studied this condition (commonly referred to as skeletal fluorosis), the joint damage caused by fluoride may mimic other, more common, forms of “arthritis,” making it easy to misdiagnose -- especially by doctors who are not trained in detecting fluorosis.

According to the Centers for Disease Control, 1 in 3 adults in the US now suffer from some form of arthritis. Could fluoride be a contributing factor in some of these cases? It is probable, however, as detailed in the the NRC’s 2006 review, there has never been an adequate study to determine the prevalence of earlier stages of skeletal fluorosis in the US. The problem with this “research gap” was underscored this year by three studies, one from India and two from the US.

According to the Indian study by Gupta et al, a 35-year old woman who drank water with 1.9 ppm fluoride developed a subtle form of fluorosis that doctors initially suspected to be a form of “seronegative arthritis” (2a). Seronegative arthritis refers to a form of arthritis which mimics the symptoms of rheumatoid arthritis (RA), but lacks the autoantibodies diagnostic of RA. In this case study, the woman “presented with joint pain involving the lower back, both heels, and the knee for the past 3 years.” In addition to these joint pains, the patient suffered from “gastrointestinal disturbance” prompting the doctors to suspect “the possibility of enteropathic arthritis.” Enteropathic arthritis is a form of arthritis associated with inflammatory bowel diseases.

The doctors finally began to suspect the role of fluoride after x-rays revealed increased bone density in the pelvic area and calcification of some ligaments. After follow-up tests revealed elevated levels of fluoride in the patient’s drinking water (1.9 ppm), and slightly elevated levels of fluoride in the blood (0.05 ppm), the doctors diagnosed the patient as suffering from fluorosis.

Another study, published in the summer by doctors at the Mayo Clinic, suggests that similar cases of fluorosis may be occurring in the US among habitual tea drinkers (tea often contains high levels of fluoride), especially those with weak kidney function (2b). In the study, the Mayo doctors detail the cases of 4 patients who developed bone pains, and in some cases gastrointestinal problems, from drinking too much tea. As with the Indian study, at least one of these patients had previously been misdiagnosed as having “arthritis.” The woman, who “developed chronic pain and stiffness in her lower back that progressed to include bilateral hip and knee pain”, had been treated for 7 years with various drugs “but with no improvement in symptoms.” It wasn’t until the Mayo Clinic doctors identified fluorosis as the cause of her pain, that the woman took steps to reduce her tea intake which led, at last, to an improvement in symptoms.

According to the Mayo doctors:

“Fluoride toxicity can present in an insidious manner, and clinicians may overlook its signs and symptoms. Unless recognized and the source of excessive fluoride identified and discontinued, fluoride toxicity can be both progressive and crippling.”

In yet another study, presented at the annual conference of the American Society for Bone and Mineral Research, doctors reported a similar scenario (2c). A 49-year old woman (without kidney disease) developed skeletal fluorosis by drinking too much instant tea made with fluoridated water. As with the above cases, the woman “developed widespread musculoskeletal pains” and was misdiagnosed for years as having fibromylagia and osteoarthritis.  According to the authors: