Fluoride Action Network

National Research Council (2006)

An overview of the NRC's groundbreaking report on fluoride toxicity, including excerpts of its key findings and recommendations, statements from the panelists, and a discussion of its relevance to water fluoridation and sulfuryl fluoride.

NRC’s Recommendations

One of the conclusions to be drawn from the NRC’s 400+ page report is that a staggering number of fundamental questions still exist about fluoride’s safety, including its effects on the brain, thyroid, and glucose metabolism, and how these effects might differ based on the health status of the individual and the presence or absence of other chemicals and nutrients, including aluminum and iodine. As noted by the Panel’s Chairman, Dr. John Doull, “when we looked at the studies that have been done, we found that many of these questions are unsettled and we have much less information than we should, considering how long this [fluoridation] has been going on. I think that’s why fluoridation is still being challenged so many years after it began. In the face of ignorance, controversy is rampant.”

To better clarify the extent to which current fluoride exposures may be contributing to neurological disorders, endocrine problems, and other chronic health ailments, the NRC panel made the following recommendations:

“Carefully conducted studies of exposure to fluoride and emerging health parameters of interest (e.g., endocrine effects and brain function) should be performed in populations in the United States exposed to various concentrations of fluoride.” p.12

“More research is needed to clarify fluoride’s biochemical effects on the brain.” p.222

“The possibility has been raised by the studies conducted in China that fluoride can lower intellectual abilities. Thus, studies of populations exposed to different concentrations of fluoride in drinking water should include measurements of reasoning ability, problem solving, IQ, and short- and long-term memory. p.223

“Studies of populations exposed to different concentrations of fluoride should be undertaken to evaluate neurochemical changes that may be associated with dementia. Consideration should be given to assessing effects from chronic exposure, effects that might be delayed or occur late-in-life, and individual susceptibility.” p.223

“The effects of fluoride on various aspects of endocrine function should be examined particularly with respect to a possible role in the development of several diseases or mental states in the United States. Major areas for investigation include the following: * thyroid disease (especially in light of decreasing iodine intake by the U.S. population); * nutritional (calcium-deficiency) rickets; * calcium metabolism (including measurements of both calcitonin and PTH); * pineal function (including, but not limited to, melatonin production); and * development of glucose intolerance and diabetes.” p.267

“Fluoride should be included in nationwide biomonitoring surveys and nutritional studies; in particular, analysis of fluoride in blood and urine samples taken in these surveys would be valuable.” p.11

“To assist in estimating individual fluoride exposure from ingestion, manufacturers and producers should provide information on the fluoride content of commercial foods and beverages.“ p.87

“The concentrations of fluoride in human bone as a function of exposure concentration, exposure duration, age, sex, and health status should be studied.” p.11

“Better characterization of exposure to fluoride is needed in epidemiology studies investigating potential effects. Important exposure aspects of such studies would include the following: collecting data on general dietary status and dietary factors that could influence exposure or effects, such as calcium, iodine, and aluminum intakes.” p.88

“Information is particularly needed on fluoride plasma and bone concentrations in people with small-to-moderate changes in renal function as well as in those with serious renal deficiency.” p.11

“More research is needed on bone concentrations of fluoride in people with altered renal function, as well as other potentially sensitive populations (e.g., the elderly, post-menopausal women, people with altered acid-balance), to better understand the risks of musculoskeletal effects in these populations.” p.180

“A systematic study of clinical stage II and stage III skeletal fluorosis should be conducted to clarify the relationship between fluoride ingestion, fluoride concentration in bone, and clinical symptoms. “ p.12

“More studies of communities with drinking water containing fluoride at 2 mg/L or more are needed to assess potential bone fracture risk at these higher concentrations.” p.12

“The biological effects of aluminofluoride complexes should be researched further, including the conditions (exposure conditions and physiological conditions) under which the complexes can be expected to occur and to have biological effects.” p.88

“Thus, more studies are needed on fluoride concentrations in soft tissues (e.g., brain, thyroid, kidney) following chronic exposure.” p.102

“More work is needed on the potential for release of fluoride by the metabolism of organofluorines.” p.102

“the relationship between fertility and fluoride requires additional study.” p.193

“Further effort is necessary to characterize the direct and indirect mechanisms of fluoride’s action on the endocrine system and the factors that determine the response, if any, in a given individual. Such studies would address the following.. * identification of those factors, endogenous (e.g., age, sex, genetic factors, or preexisting disease) or exogenous (e.g., dietary calcium or iodine concentrations, malnutrition), associated with increased likelihood of effects of fluoride exposures in individuals. * consideration of the impact of multiple contaminants (e.g., fluoride and perchlorate) that affect the same endocrine system or mechanism.” p.266

“Studies are needed to evaluate gastric responses to fluoride from natural sources at concentrations up to 4 mg/L and from artificial sources.” p.302

“Additional studies should be carried out to determine the incidence, prevalence, and severity of renal osteodystrophy in patients with renal impairments in areas where there is fluoride at up to 4 mg/L in the drinking water.” p.302

“The effect of low doses of fluoride on kidney and liver enzyme functions in humans needs to be carefully documented in communities exposed to different concentrations of fluoride in drinking water.” p.303

“In addition, studies could be conducted to determine what percentage of immunocompromised subjects have adverse reactions when exposed to fluoride in the range of 1-4 mg/L in drinking water.” p.303

“It is paramount that careful biochemical studies be conducted to determine what fluoride concentrations occur in the bone and surrounding interstitial fluids from exposure to fluoride in drinking water at up to 4 mg/L, because bone marrow is the source of the progenitors that produce the immune system cells.” p.303

“Further research on a possible effect of fluoride on bladder cancer risk should be conducted.” p.338

“in vivo human genotoxicity studies in U.S. populations or other populations with nutritional and sociodemographic variables similar to those in the United States should be conducted.” p.338-9

“The possibility of biological effects of SiF6 , as opposed to free fluoride ion, should be examined.” p.88

“More research is needed on the relation between fluoride exposure and dentin fluorosis and delayed tooth eruption patterns.” p.12

“To permit better characterization of current exposures from airborne fluorides, ambient concentrations of airborne hydrogen fluoride and particulates should be reported on national aregional scales, especially for areas of known air pollution or known sources of airborne fluorides. Additional information on fluoride concentrations in soils in residential and recreational areas near industrial fluoride sources also should be obtained” p.87

“Two small studies have raised the possibility of an increased incidence of spina bifida occulta in fluorosis-prone areas in India; larger, well-controlled studies are needed to evaluate that possibility further.” p.196

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