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For decades, water agencies have added fluorides to drinking water supplies as a means to help prevent cavities with only minor questions being asked. But in the past ten years the questions have grown stronger. Just what is fluoride? Why do we need it? What is the side effects? Recently, major cities such as Juneau, Alaska and Quebec have voted to halt fluoridation amid increased public concern and growing evidence of fluoride's serious unwanted side effects on kidneys, bones, teeth, and perhaps even other organs such as the thyroid.

Fluoride is a low-molecular-weight anion that is absorbed in the gastrointestinal tract, diffuses from plasma into interstitial fluid, is rapidly concentrated in bone, and is eliminated primarily by renal excretion. Like other low-molecular-weight solutes, fluoride diffuses readily across dialyzer membranes. Based on evidence that fluoride reduces tooth decay, fluoride routinely is added to municipal drinking water to achieve a concentration of about 50 µmol/L. Persons with normal renal function generally have a serum concentration of fluoride of less than 2 µmol/L; the concentration may be several times greater in persons with chronic renal failure taking kidney dialysis or in those taking supplemental sodium fluoride orally.

The danger of fluoride for a kidney dialysis patient comes in the uptake of large amounts of fluoride into blood, usually from ingestion or from skin burns with hydrofluoric acid, can cause acute fluoride intoxication, a life-threatening illness in which peak fluoride concentrations in serum have reached or exceeded 500 µmol/L. The only outbreak of acute fluoride intoxication previously reported in patients receiving hemodialysis was caused by accidental overfluoridation of municipal water that was not treated by a deionization system or reverse osmosis before use in dialysis. In essence, too much fluoride was put into the drinking water system than could be processed out before it reached the bodies of the dialysis patients.

Of even more concern is the growing debate of the effect of fluoride on those people not yet on kidney dialysis, but under-going renal strain. The National Kidney Foundation's alleged failure to warn kidney patients that they are particularly susceptible to harm from ingested fluoride from drinking water and other sources is the subject of a precedent-setting letter to the Foundation from a legal firm. Coming at a time of increased public suspicions over the operations of large national nonprofit organizations, the letter is sure to draw the attention of many of the 20 million American adults that the Foundation says have chronic kidney disease.

Daniel Stockin, a public health professional with The Lillie Center, Inc., a firm working to educate Americans about harm from fluorides, questions why there are redundant filtration systems for water used in kidney dialysis machines, to remove fluoride and other harmful substances, but kidney patients are allowed to drink fluoridated water. "It makes no sense. How many people with renal disease who did not need dialysis and were hoping to avoid it, were kicked over into needing a lifetime of dialysis by fluoride ingestion?" He points out that dialysis center patients have died or become fluoride-poisoned due to accidental overfeed of fluoride at a water plant or failure of filters on dialysis machines.

"Overfeeds of fluoride happen a lot more often than most people know, but fortunately poisonings at dialysis centers are very rare, and dialysis centers provide an extremely valuable service," he says. "But kidney patients' lives and quality of life are at stake on and off dialysis machines, and even before their condition worsens to the point of needing dialysis. What could justify not telling kidney patients they are particularly susceptible to harm from fluoride intake? Is it fear of lawsuits? I would hope not."

The debate over the addition of fluoride into the water system and its affects upon the general populace will only grow stronger over the coming decades. But coming more clearly into focus is the effects of fluoride upon those suffering from renal impairment. If you are a dialysis patient or one suffering from renal impairments that may make your kidneys weaker you should check with their water supplier or dialysis center about their water source.

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