Neurodevelopmental toxicity – an ongoing discussion

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In March 2014, Dr Philippe Grandjean and Dr Philip Landrigan published Neurobehavioural effects of developmental toxicity in The Lancet Neurology, where fluoride was cited as a developmental neurotoxicant. The anti-fluoridation movement swiftly picked up on the potential significance of the paper, and, as per usual, the pro-fluoridation lobby largely ignored or dismissed the research. In July 2014, Grandjean & Landrigan responded to critiques of the March paper, stating the following:

“We agree with Feldman that fluoride is important for children’s oral health. However, the fact that a trace element has beneficial effects at low doses in specific tissues does not negate the possibility that neurotoxicity might also be occurring, especially at increased levels of exposure. Indeed, concerns about fluoride toxicity were already raised by a National Research Council expert committee. Feldman describes the recent meta-analysis as selective and based on old, confounder-ridden studies. In support of her claims, she refers to two previous reports that reviewed some of the same studies, although without access to important background information. Feldman makes other serious errors—eg, by linking, without justification, a rise in population mean intelligent quotient (IQ) to the introduction of water fluoridation. Similarly, Gelinas and Allukian dispute the validity of previous studies on fluoride exposure and neurobehavioural deficits. We do not deny the importance of a dose-response relation, which has been a unifying concept in toxicology since the time of Paracelsus. However, as we emphasised in our Review, emerging evidence on developmental neurotoxicity makes it clear that the timing of exposure is also of great importance, especially during highly vulnerable windows of brain development. Due to the growing evidence on adverse effects, US authorities now recommend that fluoridation of community water should not exceed 0·7 mg/L.”

Perrot (2014) believes this reply to be “brief and rather flippant,” however, we here at AFAM – rarely seeing eye to eye with Perrot – disagree. The National Research Council expert committee did indeed say, in 2006, that “the possibility has been raised by the studies conducted in China that fluoride can lower intellectual abilities” and recommended further studies be conducted to clarify the matter. In fact, the committee made many more recommendations to clarify fluoride’s potential negative health effects; and regarding the new 0·7 mg/L concentration threshold – as noted by Grandjean & Landrigan (ibid) – this has been criticised by at least one NRC committee expert as being inadequate to protect against known or anticipated adverse effects of fluoride.

In light of Grandjean & Landrigan’s comment that, “the fact that a trace element has beneficial effects at low doses in specific tissues does not negate the possibility that neurotoxicity might also be occurring,” it would be wise to consider the following point made by Barbiera, Arreola-Mendozab & Del Razothat (2010):

“Until the 1990s, the toxicity of fluoride was largely ignored due to its “good reputation” for preventing caries via topical application and in dental toothpastes. However, in the last decade, interest in its undesirable effects has resurfaced due to the awareness that this element interacts with cellular systems even at low doses. In recent years, several investigations demonstrated that fluoride can induce oxidative stress and modulate intracellular redox homeostasis, lipid peroxidation and protein carbonyl content, as well as alter gene expression and cause apoptosis. Genes modulated by fluoride include those related to the stress response, metabolic enzymes, the cell cycle, cell–cell communications and signal transduction.”

Connett (2012) also makes the point that, “today, we know that fluoride interferes with many other biochemical molecules and processes in addition to interfering with enzymes.” He elaborates on the matter of potential developmental toxicity in this lecture.

In summary, the questions regarding fluoride’s potential negative effects are legion, whilst the evidence for the supposed benefits of artificial water fluoridation is weak at best. It is telling that the York Review (2000) concluded, “we were unable to discover any reliable good-quality evidence in the fluoridation literature world-wide”. Therefore, no matter how religiously Perrot and his ilk attempt to wank off the promoters of fluoridation, the combination of poor evidence, fundamental toxicity questions, and, ultimately, serious queries regarding margin of safety, reveals the water fluoridation program to be nothing more than a scientific and ethical joke.

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Author: AFA Mildura

Administrator, Anti-Fluoridation Association of Mildura

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