Fluoride exposure from drinking water during pregnancy could be making children less intelligent

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Fluoride exposure from drinking water during pregnancy could be making children less intelligent, a new Canadian study argues.

Expectant moms with higher levels of fluoride in their urine tended to have kids with lower average IQs, based on a study of 601 mother-child pairs from six cities in Canada.

On average, a 1 milligram-per-liter increase in maternal urinary fluoride was associated with a 4.5-point lower IQ score in boys by the time they reached ages 3 to 4, researchers report.

“Four and a half IQ points is of substantial societal and economic concern,” said senior researcher Christine Till, an associate professor of psychology at York University in Toronto.

“We’re talking a magnitude that’s comparable to what we’re talking about when we talk about lead exposure.

“You would have millions of more children falling into the range of intellectual disability with IQ scores of less than 70, and that many fewer kids in the gifted range,” Till concluded.

However, the researchers only found an association, due to the observational nature of the study.

It was published Aug. 19 in JAMA Pediatrics.

Debate over fluoridation has simmered since cities began adding the mineral to public water supplies in the 1950s, Till said.

Two out of every three U.S. residents now live in an area with fluoridated water, compared with 38% of Canadians and 3% of Europeans, the researchers said in background notes.

Despite these findings, more studies with similar results will be needed to prompt a tough reconsideration of fluoride’s safety, said pediatric neuropsychologist David Bellinger, a professor of neurology at Harvard Medical School and a professor of environmental health at the Harvard T.H. Chan School of Public Health.

“In my view, a strong case for a hypothesis is present when multiple studies conducted independently produce consistent results.

I don’t think we are there yet in terms of fluoride neurotoxicity, but the results of this study move the needle in that direction,” said Bellinger, who wrote an editorial accompanying the report.

“When it comes to epidemiology, it is unwise to place too much emphasis on the results of any one study,” Bellinger concluded, although he noted that Till and her colleagues produced a “very good environmental epidemiology study.”

The American Dental Association released a statement saying it “remains committed to fluoridation of public water supplies as the single most effective public health measure to help prevent tooth decay.

“Throughout more than 70 years of research and practical experience, the overwhelming weight of credible scientific evidence has consistently indicated that fluoridation of community water supplies is safe,” the ADA said.

“The evidence-based research shows the recommended concentrations of fluoride (0.7 mg/L) used in community water fluoridation is beneficial and safe for the public.

“We welcome this and further scientific study of the issue to see if the findings can be replicated with methods that demonstrate more conclusive evidence,” the ADA said.

For the Canadian study, the researchers gathered urine samples from pregnant women during each trimester and tested their fluoride levels.

They also tracked the women’s potential exposure to fluoride by asking them to fill out a questionnaire regarding how much water, tea, coffee and other water-based beverages they drank.

Their children’s IQ scores were then assessed once they reached ages 3 to 4, and those scores were compared against the fluoride in mom’s urine during pregnancy.

Fluoride crosses the placenta, and lab studies have shown that the mineral accumulates in brain regions involved in memory and learning, researchers said in background notes.

Fluoride also has been shown to alter proteins and neurotransmitters in the central nervous system.

The researchers found that urinary fluoride levels during pregnancy were associated with lower IQ scores in boys, but no statistically significant association was found in girls.

“We found that fluoride exposure in pregnancy was associated with lower IQ scores in these preschool-age children,” Till said, though the study could not prove that fluoride exposure actually caused IQ levels to drop.

The study follows on the heels of a 2017 study in Mexico City that associated maternal urinary fluoride levels with a 6.3-point decrease in IQ levels among boys and girls, Till said.

“I definitely think emerging research is making the science evolve,” Till said.

Pregnant women should consider reducing their exposure to fluoride, Till said.

That might include avoiding public water sources that are fluoridated, since those account for 70% of fluoride exposure in adults.

“There’s absolutely no benefit of fluoride to a fetus or a baby without teeth,” Till said.

“You’re not doing any harm to your baby by reducing your fluoride intake. You can reduce it and your baby will be fine.”


Fluoridation of drinking water supply is an established top 10 public health achievements of the 20th century.[1]

Fluoridation can be defined as the upward or downward adjustment of the level of fluoride content in drinking water to an optimal level just enough to prevent caries but not to cause fluorosis.[2]

An optimum level of fluoride according to the climate varies and is universally calculated by applying the equation of Galagan and Vermillion.[3]

Fluoride levels of 0.5 ppm are recommended in warm climates because more water is consumed and levels as high as 1.5 ppm are regarded as optimum in cold climate where less water is consumed.

However, on an average, the optimum fluoride level in drinking water is calibrated at 1.0 ppm worldwide (0.7–1.2 ppm).[2]

Fluoride is a mineral that occurs naturally in most water supplies and is of geological origin.

Known fluoride belts on land include one that stretches from Syria through Jordan, Egypt, Libya, Algeria, Sudan, and Kenya and another that stretches from Turkey through Iraq, Iran, Afghanistan, India, northern Thailand, and China.

There are similar belts in the Americas and Japan.[4]

According to the US Center of Disease Control and Prevention, fluoridation of community drinking water is a safe, cost-effective, and efficient strategy of reducing dental decay among Americans of all ages and from all social strata.[5] It forms the foundation for sound community caries-prevention programs.

The water fluoridation controversy arises from political, moral, ethical, economic, and safety concerns regarding the fluoridation of public water supplies.

Public health authorities throughout the world find a medical consensus that water fluoridation at appropriate levels is a safe and effective means to prevent dental caries.[6]

Authorities’ views on the most effective fluoride therapy for community prevention of tooth decay are mixed; some state water fluoridation is most effective, whereas others see no special advantage and prefer topical application strategies.[7,8]

Those opposed argue that water fluoridation has no or little cariostatic benefits, may cause serious health problems, is not effective enough to justify the costs, and is pharmacologically obsolete.[9]Go to:

History of Fluoridation

It started as an observation and soon took the shape of an idea.

It ended, five decades later, as a scientific revolution that shot dentistry into the forefront of preventive medicine.

This is the story of how dental science discovered – and ultimately proved to the world – that fluoride, a mineral found in rocks and soil, prevents tooth decay.

Although dental caries remains a public health worry, it is no longer the unbridled problem it once was, thanks to fluoride.

Fluoride research had its beginnings in 1901, when Frederick McKay was astounded to find scores of Colorado Springs natives with grotesque brown stains on their teeth known as Colorado Brown Stain.

McKay in 1909 along with Dr. G. V. Black conducted a study showing that almost 90% of the city’s locally born children had signs of the brown stains.

Black investigated fluorosis for 6 years, until his death in 1915.

During that period, he and McKay made two crucial discoveries.

First, they showed that mottled enamel (as Black referred to the condition) resulted from developmental imperfections in children’s teeth.

This finding meant that city residents whose permanent teeth had calcified without developing the stains did not risk having their teeth turn brown; young children waiting for their secondary set of teeth to erupt, however, were at high risk.

Second, they found that teeth afflicted by Colorado Brown Stain were surprisingly and inexplicably resistant to decay.[2]

McKay and Kempf published a report on their findings that reached the desk of the chief chemist, H. V. Churchill, at company headquarters in Pennsylvania who decided to conduct his own test of the water in Bauxite – but this time using photospectrographic analysis, a more sophisticated technology than that used by McKay. H. V. Churchill concluded that high levels of water-borne fluoride caused discoloration of tooth enamel.

Later, Dr. Treadley H. Dean began investigating the epidemiology of fluorosis in 1931.

One of his primary research concerns was determining how high fluoride levels could be in drinking water before fluorosis occurred.

For this purpose, a state-of-the-art method to measure fluoride levels in water with an accuracy of 0.1 parts per million (ppm) was developed.

Dean and his staff set out across the country to compare fluoride levels in drinking water.

By the late 1930s, he and his staff had made a critical discovery.

Namely, fluoride levels of up to 1.0 ppm in drinking water did not cause enamel fluorosis in most people and only mild enamel fluorosis in a small percentage of people.

Dean wondered whether adding fluoride to drinking water at physically and cosmetically safe levels would help fight tooth decay.

The City Commission of Grand Rapids, Michigan – after numerous discussions with researchers from the PHS, the Michigan Department of Health, and other public health organizations – voted to add fluoride to its public water supply the following year.

In 1945, Grand Rapids became the first city in the world to fluoridate its drinking water.

During the 15-year project, researchers monitored the rate of tooth decay among Grand Rapids almost 30,000 schoolchildren.

After just 11 years, Dean concluded that the caries rate among Grand Rapids children born after fluoride was added to the water supply dropped more than 60%.

This finding, considering the thousands of participants in the study, amounted to a giant scientific breakthrough that promised to revolutionize dental care, making tooth decay for the first time in history a preventable disease for most people.[2]

As of 2012, 25 countries have artificial water fluoridation to varying degrees, 11 of them have more than 50% of their population drinking fluoridated water.

A further 28 countries have water that is naturally fluoridated, though in many of them the fluoride is above the recommended safe level.

As of 2012, about 435 million people worldwide (around 5.4% of the global population) received water fluoridated at the recommended level, nearly half of them living in the United States.

Various Fluoride Conspiracy Theories

Organized political opposition has come from libertarians, the John Birch Society,[10] and from groups like the Green parties in the United Kingdom and New Zealand. Water fluoridation has frequently been the subject of conspiracy theories. During the “Red Scare” in the United States during the late 1940s and 1950s, and to a lesser extent in the 1960s, activists on the far right of American politics routinely asserted that fluoridation was part of a far-reaching plot to impose a socialist or communist regime.[10] Dr. Charles Bett, a prominent antifluoridationist, charged that fluoridation was “better than using the atom bomb” because the atom bomb has to be made and transported to the place it is to be set off while poisonous fluorine has been placed right beside the water supplies which we consume as a daily necessity.

In 1987, Ian E. Stephens claimed that he was told by “Charles Elliot Perkins” that “repeated doses of infinitesimal amounts of fluoride will in time reduce an individual’s power to resist domination by slowly poisoning and narcotizing a certain area of the brain and will thus make him submissive to the will of those who wish to govern him”.

All these claims back then had a political and ethical basis and rarely any scientific basis was found.

The Fluoride Controversy and the Antifluoride Claims

The controversy over fluoridation of drinking water supply began as early as the 1960s, approximately a decade after the American Public Health Service officially launched the National Fluoridation Program.

The controversy has gained momentum over the years as more research is released to support the stance of the antifluoride lobby.

Several factors have spurred the present-day controversy.

The irreversible, debilitating effects of fluoride toxicity, the transient effects, and hence the continuous need of exposure to fluoride to maintain caries resistance and the fact that benefits of topical use of fluoride are as good as ingested fluoride are some of the leading contributing factors.

Antifluoride Claims

Antifluoride lobbyists start with the fact that fluoride is not an essential nutrient and no disease has ever been linked to a fluoride deficiency.[11]

In fact, fluoride is claimed to be a cumulative poison and biologically very active even at low concentrations because it interferes with hydrogen bonding and inhibits numerous enzymes.[12]

Only 50% of the daily ingested fluoride is excreted through the kidneys.

The remainder accumulates in bones, the pineal gland, and other tissues.

Initial studies on animals showed that fluoride accumulation in the pineal gland led to reduced melatonin production and an earlier onset of puberty.

The same researcher then showed in later studies that fluoride can also accumulate to very high levels in the human pineal gland.[13]

Fluoride toxicity can lead to renal damage in children.

Researchers studied 210 children living in areas of China with varying levels of fluoride in water (0.61–5.69 ppm).

Among this group, the children drinking water with more than 2 ppm fluoride – particularly those with dental fluorosis – were found to have increased levels of NAG and y-GT in their urine, both of which are markers of kidney damage.

The children’s urine also contains increased levels of lactic dehydrogenase – a possible indicator of liver damage.

A diseased kidney is unable to effectively excrete fluoride, so individuals with compromised kidneys are at risk of developing fluorosis even at normal recommended limit of 0.7–1.2 ppm.

Fluoride has been shown to be mutagenic by causing chromosome damage and interference with the enzymes involved with DNA repair in a variety of cell and tissue studies carried out in animals.[14]

Recent studies have also found a correlation between fluoride exposure and chromosome damage in humans.[15,16]

The only government-sanctioned animal study to investigate whether fluoride causes cancer, in 1990, found a dose-dependent increase in cancer in the target organ (bone) of fluoride-treated, male rats.[17]

This led to a 14-year research carried out by Harvard University that showed a significant link between fluoridation and a rare form of bone cancer called osteosarcoma in young boys, consistent with the results of the 1990 animal study.[18]

Fluoride as a neurotoxin has been proven in several animal studies.

A 2006 National Research Council report stated that it is apparent that fluorides have the ability to interfere with the functions of the brain and the body by direct and indirect means.[19,20]

This finding was confirmed by a study where groups of children exposed to 8 ppm fluoride in water were found to have lower average IQs, less children attaining high IQ, and more children affected by low IQ.[21]

While 8 ppm is much higher than the fluoride level added to water in fluoridation programs (0.7–1.2 ppm), these results are in congruence with previous studies[22] from China that indicate that fluoride may affect IQ at lower levels.[23]

If fluoride is added to water which contains aluminum, then aluminum fluoride complexes will form.

Aluminum fluoride complexes have the potential to interfere with many hormonal and some neurochemical signals.[24]

Aluminum fluoride was recently nominated by the Environmental Protection Agency (EPA) and National Institute of Environmental Health Sciences as a “high health research priority” due to its “known neurotoxicity.”

Dental fluorosis is not only a cosmetic defect.

Its psychological impact on the child has been established by the US National Institute of Mental Health.

A study found that children with severe dental fluorosis are more likely to be perceived by their peers as less intelligent, less attractive, less social, less happy, less careful, less hygienic, and less reliable – characteristics which could have major effects on a child’s self-esteem.[25]

The US Center of Disease Control and Prevention declared that in the second half of the 20thcentury, the steep decline dental decay in the United States can be attributed to fluoridation.

However, antifluoride lobbyists show that a similar decline in dental decay has been observed worldwide in countries that do not fluoridate their drinking water supplies.

To overcome selection bias, the criteria of the countries selected for this comparison study were tri-pronged, countries with a mean annual per capita income of US$10,000 or more in the year 2000, a population in the year 2000 of greater than 3 million, and finally those countries that had WHO caries data available.

The most common explanation for the worldwide declining trend was the wide distribution of fluoridate toothpastes but serious research later attributed, at best, 40%–50% of the caries reduction to fluoride products.[26]

Once fluoride is put in the water, it is impossible to control the dose each individual receives.

This is because some people, for example, manual laborers, athletes, diabetics, and peoples with kidney disease, drink more water than others.

In addition, the average person receives fluoride from sources other than the water supply such as fluoridated oral hygiene products, food, and beverages processed with fluoridated water, mechanically deboned meat, and teas.[27]

Some individuals appear to be highly sensitive to fluoride as shown by case studies and double-blind studies.

In one study, which lasted 13 years, the results showed that about 1% of patients given 1.0 mg of fluoride each day developed negative reactions.

According to the Agency for Toxic Substances and Disease Registry (1993), certain subsets of the population may be particularly vulnerable to fluoride’s toxic effects.

These include the elderly, the diabetics, and people with poor kidney function.

Also vulnerable are those who suffer from malnutrition, for example, calcium, magnesium, vitamin C, vitamin D, iodine deficiencies, and protein-poor diets.

Those most likely to suffer from poor nutrition are the poor, who are precisely the people being targeted by new fluoridation programs.

While being at a heightened risk, poor families are less able to afford avoidance measures, for example, bottled water or fluoride removal equipment.

Fluoridation of community drinking water is considered unethical because individuals are not being asked for their informed consent prior to medication.

It is standard practice to obtain consent for all medication, and this is one of the key reasons why most of Western Europe has ruled against fluoridation.

It is a violation of human rights, a direct violation of the Nuremberg code that states that research or even routine medical procedures must be done with the voluntary cooperation of the subjects who must be fully informed of the risks or benefits of the procedure in which they are involved.[9]

Studies have shown an association between the use of fluorosilicic acid and its sodium salt to fluoridate water and increased uptake of lead into children’s blood.

Lead is acknowledged as a neurotoxin that damages the child’s developing brain, and lead toxicity is unaddressed especially in developing countries. Sodium fluoride is an extremely toxic substance, just 200 mg of fluoride ion is enough to kill a young child, and just 3–5 g (e.g., a teaspoon) is enough to kill an adult.[28]

The US Food and Drug Administration (FDA) has never approved of any fluoride product designed for ingestion as safe or effective is a popular claim by the antifluoride lobby but according to the EPA-FDA Memorandum of Agreement, the FDA’s regulatory purview is limited to the safety and efficacy of food, drugs, or cosmetic-related products, as well as bottled water which is marketed as a consumer beverage.

Thus, if bottled water has fluoride additives and is approved by FDA, then this comes under the category of fluoride product meant for ingestion.

The American Dental Association (ADA) recommends that water with added fluoride, bottled or otherwise, should not be used to mix concentrated formula or foods intended for babies age 1 year and younger to prevent tooth damage. Fluoridated bottled water comes with special instruction for infant consumption.

The ADA stance is in congruence with the antifluoride lobby who report that the level of fluoride put into water (1 ppm) is up to nearly 50 times higher than normally found in mothers’ milk (0.019 ± 0.004 ppm).[29] Therefore, there are no benefits, only risks, for infants ingesting this heightened level of fluoride at such an early age.


More information: The American Dental Association has more about fluoride.

Journal information: JAMA Pediatrics

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