April 22, 2019

Archives for February 24, 2015

Water Fluoridation May Increase Risk of Underactive Thyroid Disorder

COF-COF Special News FindBy: Douglas Main, Newsweek.com, United States 24-Feb-2015 –A large study that looked at data from nearly every general medical practice in England suggests that water fluoridation may increase the risk of developing hypothyroidism, or underactive thyroid. This condition, in which the thyroid gland doesn’t produce enough hormones, is associated with symptoms such as fatigue, obesity and depression.

The study found that locations with fluoridated water supplies were more than 30 percent more likely to have high levels of hypothyroidism, compared to areas with low levels of the chemical in the water. Overall, there were 9 percent more cases of underactive thyroid in fluoridated places.

Fluoride is added to the water of about 10 percent of England’s population—and to the taps of about two-thirds of Americans—for the purpose of preventing cavities. It has proved controversial ever since being adopted by American public health authorities in the 1950s, and then spreading to some other countries; supporters say it is a boon for dental health, while critics say it may lead to a variety of health problems.

The paper, published today in the Journal of Epidemiology & Community Health, also directly compared the fluoridated city of Birmingham with the city of Manchester, which doesn’t add the substance to the water. After controlling for factors such as sex and age (women are more likely than men to have the condition, and the elderly more likely than the young), the researchers concluded that doctor’s offices in Birmingham were nearly twice as likely to report high levels hypothyroidism, says study co-author Stephen Peckham, a researcher at the University of Kent.

“It raises a red flag,” says Dr. Philippe Grandjean, an environmental health researcher and physician at Harvard University, “that possible interference with thyroid function needs serious consideration when regulating fluoride levels in drinking water.”

The findings are all the more important since this is the “largest population ever studied in regard to adverse effects of elevated fluoride exposure,” says Grandjean, who wasn’t involved in the study. Data was collected from 99 percent of England’s 8,020 general medical practices, and the study found that a total of 3.2 percent of the population had hypothyroidism, a 14 percent increase from 2008.

“The study is an important one because it is large enough to detect differences of potential significance to the health of the population,” says Trevor Sheldon, a medical researcher and dean of the Hull York Medical School. Sheldon, who has authored numerous studies in this field, no longer thinks (as he once did) that the “case for general water fluoridation” is clear.

Considering the comprehensiveness of this study—it covered nearly the whole of England—regional differences in fluoride intake or other confounding factors are unlikely to have played a role in the striking results, says Kathleen Thiessen, a senior scientist at the Oak Ridge Center for Risk Analysis, a company that does human health risk assessments for a variety of environmental contaminants.

But John Warren, a professor and researcher in the department of dentistry at the University of Iowa, disagrees. He points out that the study merely shows correlation, not causation. It also “assumes that since one group lives in a fluoridated community, they have higher exposure to [the substance] than those in the non-fluoridated area,” he says. This is significant flaw, he says—to draw a valid connection between fluoride and hypothyroidism, you’d have to measure individual exposure to the chemical and show that those with the condition had higher levels of exposure.

But other researchers interviewed for this story disagreed with this point, saying that such group studies are a valid way to begin to assess health effects of chemical exposure and make up the bulk of the scientific basis for fluoridation; this paper uses a much larger sample size than the vast majority of studies showing positive effects of fluoride, Thiessen says. Collecting individual data from tens of thousands of people is also not very feasible, they say.

“It’s unlikely that other sources of fluoride exposure—from tea, swallowed toothpaste, a few types of foods—would be distributed amongst the population of England in a way that would bias the results in one direction or another,” says Chris Neurath, senior scientist with the Fluoride Action Network, which opposes adding the substance to water.

Moreover, several other studies have suggested that fluoride in water accounts for a majority of an individual’s exposure to the chemical in the United States, and Peckham says this is also probably true in the United Kingdom. Thus it stands to reason that people in areas with higher levels in the water are generally exposed to more of it, Peckham says.

The connection between fluoridation and thyroid problems has not been widely studied, says Thiessen, who wasn’t involved in the paper. But the research that does exist shows that at a certain dose fluoride does indeed impair the activity of the thyroid gland, through an as-yet-unclear mechanism, she says.

In fact, fluoride was used to to treat hyperthyroidism (or an overactive thyroid) in the 1950s. It may put a damper on the gland’s activities by suppressing the activity of various enzymes, causing physical damage or interfering with the absorption and use of iodine, a substance that is critical for thyroid health, Thiessen says.

In 2006, the U.S. Environmental Protection Agency convened a panel that recommended lowering the maximum allowable level of fluoride in water; Thiessen was amongst that group and helped write sections of the report regarding health effects on the thyroid. Nine years later, the EPA is still considering whether or not to revise its fluoride standards.

Grandjean’s work has shown that high levels of fluoride—above the concentrations found in most fluoridated water—are associated with reduced IQ measures in children in China and India. Based on that work, he and a co-author listed fluoride as a developmental neurotoxin in a 2014 study in The Lancet.

“We don’t know how fluoride may cause the decreases in IQs in children, but this new study suggests that thyroid toxicity could be a very relevant mechanism,” Grandjean says. The thyroid produces hormones that are vital for proper metabolism, growth and brain function, and children of mothers with thyroid problems can suffer deficits in these areas, he adds.

The Centers for Disease Control and Prevention, which lists fluoridation as one of the top 10 public health initiatives of the 20th century, declined to comment on the study. The Food and Drug Administration referred questions about the study to the EPA, which didn’t respond by publication time. Public Health England maintains that fluoridation is “ a safe and effective public health measure.”

But some researchers aren’t so sure. “This study illustrates that there are potential harms [with fluoridation] that need large scale studies to explore; at the same time it is not a reason for panic,” Sheldon says.



Trouvailles Médiatiques 300 x 300Par: Charles Côté, La Presse, 24-février-2015 La fluoration augmenterait le risque de contracter une maladie de la glande thyroïde.

L’ajout de fluorure dans l’eau du robinet augmente les risques de contracter une maladie de la glande thyroïde, selon une recherche parue hier dans le Journal of Epidemiology and Community Health. L’ajout de fluorure dans l’eau du robinet est lié à un taux significativement plus élevé d’une maladie de la glande thyroïde. C’est la conclusion d’une recherche parue hier dans le Journal of Epidemiology and Community Health, publié par le British Medical Journal. Cela donnera des arguments supplémentaires à ceux qui s’opposent à la fluoration de l’eau, une mesure pourtant jugée efficace et peu coûteuse pour combattre la carie dentaire.

Les chercheurs de l’Université du Kent ont étudié la clientèle de 7935 médecins de famille d’Angleterre. Les médecins de famille anglais qui participent au régime de santé public sont incités financièrement à vérifier le fonctionnement de la glande thyroïde.

Environ 10% de la population britannique est desservie par un réseau d’aqueduc dans lequel du fluor a été ajouté à l’eau potable. Il y a donc une masse de données propice à l’analyse de type épidémiologique. Résultat: la probabilité que la clientèle d’un médecin souffre d’un taux élevé d’hypothyroïdie augmente de 40% à 60% selon la teneur en fluorure de l’eau.

Une plus grande proportion de la population est alimentée par de l’eau fluorée au Canada et aux États-Unis, où cette pratique à grande échelle a commencé dans les années 50.

Au pays, 42% de la population est alimentée par de l’eau fluorée. En Ontario, c’est 76%, autant qu’aux États-Unis (75%). Mais au Québec, c’est seulement 3%.

En 2006, le gouvernement du Québec se donnait l’objectif que d’ici 2012, 50% de la population de la province ait accès à de l’eau potable dont la concentration en fluorure est optimale. L’objectif est loin d’être atteint. En fait, on s’en éloigne, avec l’abandon de la fluoration à Québec en 2008 et, plus récemment, à Bécancour.


Alors qu’est-ce donc que l’hypothyroïdie? Tout part de la glande thyroïde, qui sécrète des hormones qui contrôlent le niveau du métabolisme des cellules du corps. Selon Passeport Santé, quand cette glande sécrète moins d’hormones, les personnes peuvent prendre du poids et ressentir de la faiblesse, de la fatigue, de la confusion, des crampes musculaires, de la frilosité et une foule d’autres symptômes diffus.

Les femmes sont de deux à huit fois plus susceptibles d’en souffrir. La prévalence augmente avec l’âge. La maladie touche 1% des adultes au Canada, mais 10% des 60 ans et plus.

Selon les chercheurs, c’est la première fois que la corrélation entre l’exposition au fluor et les effets sur la glande thyroïde est étudiée à l’échelle de la population.

Cependant, ils mentionnent que l’on connaissait l’effet du fluor sur la thyroïde depuis longtemps: dans les années 50, on traitait le goitre – l’hyperthyroïdie – avec une dose de fluor semblable à celle à laquelle on est exposé si on boit 1,5 litre d’eau fluorée par jour. Les symptômes du goitre sont souvent à l’opposé de ceux de l’hypothyroïdie: nervosité, tremblements, rythme cardiaque rapide, perte de poids, etc.

Toujours recommandé au Québec

Les chercheurs affirment que leurs «résultats de recherche ont des implications importantes pour les politiques de santé publique au Royaume-Uni et dans d’autres pays où le fluorure est ajouté à l’eau».

Mais pour sa part, la Direction de la santé publique (DSP) du Québec continue de prôner la fluoration, y compris dans un avis de 2012 sur cette question.

On y affirme que les enfants québécois ont 40% à 50% plus de caries que les Nord-Américains du même âge. Et il y a plus d’«édentés» au Québec qu’ailleurs au Canada. Dans ce même avis, la DSP affirme qu’«aucune donnée scientifique ne démontre de lien entre la fluoration de l’eau de consommation et un problème de santé particulier».

Une affirmation qui devra peut-être être nuancée.

À l’instar de la DSP, la plupart des autorités de santé publique et des associations dentaires continuent de prôner la fluoration de l’eau, sur la base de centaines d’études qui n’ont pas mis au jour d’impact négatif.

Mais ses bienfaits pour la santé dentaire sont de plus en plus difficiles à discerner, selon un rapport publié l’an dernier par le Centre de collaboration nationale en santé environnementale (CCNSE).

«Il y a de multiples sources de fluor, les soins dentaires s’améliorent ainsi que l’hygiène dentaire individuelle», affirme-t-on.


The addition of fluoride in tap water increases the risk of contracting a disease of the thyroid gland, according to research published yesterday in the Journal of Epidemiology and Community Health. The addition of fluoride in tap water is connected to a significantly higher rate of a disease of the thyroid gland. This is the conclusion of research published yesterday in the Journal of Epidemiology and Community Health, published by the British Medical Journal. This will give additional arguments to those who oppose water fluoridation, a measure nevertheless deemed effective and inexpensive to fight tooth decay.

Researchers at the University of Kent studied customer 7935 Family Physicians of England. The English family physicians participating in the public health system are financial incentive to check the functioning of the thyroid gland.

About 10% of the UK population is served by a water system in which fluorine was added to drinking water. So there is a mass of data conducive to the type of epidemiological analysis. Result: the likelihood that the customer of a doctor suffers from a high rate of hypothyroidism increases from 40% to 60% depending on the fluoride content of the water.

A greater proportion of the population is supplied by fluoridated water in Canada and the United States, where the widespread practice began in the 50s.

Nationally, 42% of the population is supplied with fluoridated water. In Ontario, it is 76%, as the United States (75%). But in Quebec, only 3%.

In 2006, the Quebec government gave itself the goal that by 2012, 50% of the provincial population has access to safe drinking water with fluoride concentration is optimal. The objective is far from being achieved. In fact, one walks away with the abandonment of fluoridation in Quebec in 2008 and more recently in Bécancour.


So what is it that hypothyroidism? Any part of the thyroid gland, which secretes hormones that control the metabolism of the body cells. According to Passport Health when this gland secretes less hormones, people can gain weight and feel weak, fatigue, confusion, muscle cramps, nervousness, and a host of other diffuse symptoms.

Women are two to eight times more likely to suffer. The prevalence increases with age. The disease affects 1% of adults in Canada, 10% of 60 and over.

According to the researchers, this is the first time that the correlation between fluoride exposure and effects on the thyroid gland is studied across the population.

However, they mention that we knew the effect of fluoride on thyroid long time: in the 50s, was treated goiter – hyperthyroidism – with a dose of fluoride similar to that to which one is exposed if you drink 1.5 liters of fluoridated water per day. The symptoms of goiter are often the opposite of those of hypothyroidism: nervousness, tremors, rapid heart rate, weight loss, etc.

Always recommended in Quebec

The researchers say that their “research results have important implications for public health policy in the UK and in other countries where fluoride is added to water.”

But for his part, the Public Health Department (PHD) in Quebec continues to advocate fluoridation, including a notice of 2012 on this issue.

It states that Quebec children have 40% to 50% more cavities than North Americans of the same age. And there’s more “toothless” in Quebec and across Canada. In this opinion, the DSP asserts that “no scientific evidence demonstrating a link between the consumption of water fluoridation and a particular health problem.”

A statement which may have to be qualified.

Like DSP, most public health authorities and dental associations continue to advocate fluoridation of water, based on hundreds of studies that have not revealed any negative impact.

But its benefits for dental health are becoming more difficult to discern, according to a report last year by the National Collaborating Centre for Environmental Health (NCCEH).

“There are multiple sources of fluoride, dental care and improved individual hygiene,” it is said.