Tag Archives: National Toxicology Program

Fluoride and IQ – another study coming up

Well, eventually.

It’s basically a systematic review of published scientific literature on fluoride-IQ effects in humans. It’s just at the planning stages and don’t expect anything for a few years – peer review and public consultation of the findings are not planned until 2018.

NTP

The review is planned by National Toxicology Program (NTP) which is part of the US National Institute of Environmental Health Sciences. It’s a special project developed in response to requests from the public (guess who?).

Some might question whether such a review will add anything – after all this question has been included in several reviews of possible health effects of community water fluoridation (eg NRC and NZ review), although it has just been one component of most of these reviews. An exception is the review by the Bazian Company

Bazian. (2009). Independent critical appraisal of selected studies reporting an association between fluoride in drinking water and IQ (Vol. 44).

This considered in detail the specific publications used by campaigners against CWF to argue there is a problem (the reviewers found there wasn’t).

But, on the positive side, this will most likely be one more review by a reputable body showing how poor the evidence used by anti-fluoride campaigners is. On the negative side the process and findings will be misrepresented again and again by anti-fluoride campaigners. That has already started – see the press release by Fluoride Free NZ –  Fluoride-Brain Studies Set to Expose Fluoridation Damage. Talk about counting chickens before they hatch!

Here is an extract from the Summary of the NTP proposal (Proposed NTP Evaluation on Fluoride Exposure and Potential for Developmental Neurobehavioral Effects):

“The National Toxicology Program (NTP) proposes to conduct an evaluation of the published literature to determine whether exposure to fluoride is associated with effects on neurodevelopment, specifically learning, memory, and cognition. This evaluation will use systematic review methods and include an examination of data from human (epidemiological), experimental animal, and mechanistic studies. Previous evaluations have found support for an association between fluoride exposure and impaired cognition; however, many of the studies included exposure to high levels of fluoride. Most of the human evidence was from fluoride-endemic regions having high background levels of fluoride, and the animal studies typically included exposure during development to relatively high concentrations of fluoride (>10 mg/L) in drinking water. Thus, the existing literature is limited in its ability to evaluate potential neurocognitive effects of fluoride in people associated with the current U.S. Public Health Service drinking water guidance (0.7 mg/L).” [My emphasis].

The proposal also says:

“A 2015 systematic analysis of the human literature conducted for the Republic of Ireland’s Department of Health (Sutton et al. 2015) concluded that there was no evidence of an association with lowered IQ in studies of community water fluoridation areas based primarily on an analysis of a prospective cohort study in New Zealand (Broadbent et al. 2015). For fluoride-endemic areas, there was a strong suggestion that high levels of naturally occurring fluoride in water (> 1.5 ppm) may be associated with negative health effects, including lowering of IQ. In general, these studies were considered of low quality because they did not fully account for other factors that could also cause a lowering of IQ e.g., nutritional status, socioeconomic status, iodine deficiency, other chemicals in the ground water (arsenic or lead). The conclusions of Sutton et al. (2015) are consistent with findings of a 2012 meta-analysis of 27 epidemiology studies that “supported the possibility of an adverse effect of “high” fluoride exposure on children’s neurodevelopment, specifically for lowered IQ; although the 2012 meta-analysis also identified study quality limitations, mostly related to reporting quality, that limited the strength of conclusions that could be reached (Choi et al. 2012).

The anti-fluoride spin

You wouldn’t think the anti-fluoride crowd would welcome such a careful analysis of the poor-quality articles they promote – but you can get some idea of how they will spin this study over the next few years from the comments in the above press release:

“Results could mean the end to fluoridation world-wide, and definitely should put a halt to any plans to start fluoridation in places not currently fluoridated.

Because it is now well established that fluoride affects the brain, the NTP plans to conduct new animal studies to determine the lowest dose at which this damage occurs. They also plan to do a systematic review of all the existing scientific literature. To date, there have been 314 studies that have investigated fluoride’s effects on the brain and nervous system. These include 181 animal studies, 112 human studies, and 21 cell studies.”

The confirmation bias and dogmatic agenda stick out like a sore thumb – don’t expect these people to accurately report this study’s findings.

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