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To summarize recent literature relating to health effects of fluoridation of community water supplies for people with chronic kidney disease (CKD) in order to develop the position statement of the Kidney Health Australia organization.

• OVID platform (Medline, Pre-Medline, PsycInfo)
• Cochrane Library
• National Research Registers (United Kingdom and United States)
• Google Internet search engine and Grey Literature Directory
• Databases searched from inception to July 1, 2006.

 

• Articles published in any language other than English
• Articles that were deemed by the reviewers to be not relevant to the research questions.

Research Questions

• Does consumption of fluoridated drinking water increase the risk of developing CKD?
• Are there negative health effects for people with kidney disease who consume fluoridated drinking water?
• Are there particular risks for people using fluoridated water for dialysis?

Other 

• Literature review using search terms common to both American and English spelling
• When possible, studies were divided by the concentration of fluoride in the drinking water: Optimal (less than 1.5ppm) and higher than optimal (more than 1.5ppm).

Reference markers indicate 32 articles were included in the cited review of literature.

The articles reviewed presented conflicting information in some cases and were also noted to have study flaws that would confound results.

There is a lack of high-level evidence in the form of randomized controlled trials, with the majority of studies consisting of case series, case reports or comparative studies with historical controls.  No definitive conclusions can be made.

Relating to the questions posed:

• Does consumption of fluoridated drinking water increase the risk of developing CKD?
  • People exposed to optimally fluoridated water will consume 1.5mg of fluoride per day. Available studies found no difference in kidney function between people drinking optimally fluoridated and non-fluoridated water. There is discrepant information in studies relating to the potential negative effects of consuming water with greater than 2.0ppm of fluoride.
• Are there negative health effects for people with CKD who consume fluoridated drinking water?
  • Available literature indicated that impaired kidney function results in changes in fluoride retention and distribution in the body. People with kidney impairment showed a decreased urine fluoride and increased serum and bone fluoride correlated with degree of impairment; however, there was no consistent evidence that the retention of fluoride in people with stage four or stage five CKD, consuming optimally fluoridated water, resulted in negative health consequences.
• Are there particular risks of fluorosis for people using fluoridated water for dialysis
  • Compared with the average gastrointestinal uptake, fluoride absorption increases by 20-fold to 30-fold during a single pass of dialysis.

Based on the available evidence, the Kidney Health Australia developed the following position statement:

• There is no evidence than consumption of optimally fluoridated drinking water increases the risk of developing CKD
• There is consistent evidence that impairment of kidney function results in changes to the way in which fluoride is metabolized and eliminated from the body
• There is no evidence that consumption of optimally fluoridated drinking water poses any health risks for people with CKD
• There is limited evidence that people with stage four or stage five CKD who ingest substances with a high concentration of fluoride may be at risk of fluorosis
• Monitoring of fluoride intake and avoidance of fluoride-rich substances would be prudent for people with stage four or stage five CKD, in addition to regular investigations for possible signs of fluorosis
• Fluoride concentrations in the final feed water to the dialysis machine must comply with established water quality guidelines.

 

The poor evidence quality and deficient methodologies of the identified studies means that no definitive conclusions regarding the association between consumption of optimally fluoridated community water and CKD can be made.

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Kidney Health Australia Other non-profit:

Additional study would be beneficial. Available literature appears to be minimal relating to kidney function; it is therefore surprising that they would create the position statement as they did.