Natural Life Magazine

Ask Natural Life:
What Are the Dangers of Fluoride?

by Wendy Priesnitz

Photo © Shutterstock

Q: We’ve just moved to a new city and I have discovered that they add fluoride to the water. Is this a good thing or a bad thing?

A: Fluoride is a byproduct of the phosphate fertilizer industry that has been added to municipal water supplies in North America for decades, although it is not an essential nutrient and the body does not need it. In fact, most large-scale studies have found that fluoridated water provides only a minor benefit to teeth, or no demonstrable benefit at all.

At one time, there was controversy surrounding the research about the health effects of fluoride. However, the volume of studies shows overwhelmingly that there are serious problems due to its use in municipal water supplies. In a 2005 report, the Environmental Working Group stated, “Over the past ten years a large body of peer-reviewed science has raised concerns that fluoride may present unreasonable health risks, particularly among children, at levels routinely added to tap water in American cities.”

Many of these risks include exposure to heavy metals such as lead, arsenic, and radium that contaminate the industrial-grade fluoride that municipal water systems use. Osteosarcoma (bone cancer) has been shown to be associated with radium in drinking water, largely as a result of the addition of fluoride. A paper outlining the finding was published in 2006 in the journal Cancer Causes & Control. Harvard University researchers found that boys aged six to eight who were exposed to higher levels of fluoridated water were about four times more likely to develop the cancer than those exposed to lower levels.

But an increasing number of studies from many countries have found something that, to me, is even more worrisome. There is a strong association between fluoride in water and sharply reduced IQs in children.

In 2012, Phillipe Grandjean of the Harvard T.H. Chan School of Public Health, and his colleagues, conducted a review of published studies on fluoride. They found that the body of evidence supports the possibility that high fluoride exposures can harm the development of children's brains and nervous systems.

A primary research study released in 2017 found that exposure to fluoride during pregnancy can harm IQ and cognitive development in children. The collaboration among researchers in the U.S., Mexico, and Canada examined 299 pairs of Mexican mothers and children. It found that higher prenatal fluoride exposure was associated with lower scores on tests of cognitive function in the children at age four, and again between the ages of six and 12.

The U.S. National Research Council, with taxpayer funding, reviewed fluoride toxicology and concluded in 2006 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.” The 500-page report also asserts that, “Not only do fluorides [adversely] affect transmitter concentrations and functions but also are involved in the regulation of glucagon, prostaglandins, and a number of central nervous system peptides including vasopressin… and other hypothalamic peptides.”

More recent research funded by both the National Institute of Environmental Health Sciences in the USA and Health Canada have shown a loss of IQ and increased symptoms of ADHD in children when pregnant women are exposed to fluoride at doses commonly experienced in fluoridated communities in Canada. And a new organization Fluoride-Free Canada has reported a number of other similar disturbing studies. For instance, a 2020 study in the journal Environment International found a large reduction in IQ when children were bottle-fed as babies in communities with fluoridated water, compared with babies who were bottle-fed in non-fluoridated communities.

The report also noted that, “Fluorides also increase the production of free radicals in the brain through several different biological pathways. These changes have a bearing on the possibility that fluorides act to increase the risk of developing Alzheimer’s disease.”

Fluoride is now classified alongside lead, mercury, and PCBs as one of the “developmental neurotoxicants” according to the journal, Lancet Neurology.

Overexposure to fluoride due to its prevalence in both toothpaste and drinking water can lead to severe dental fluorosis (or mottling of teeth), which can, in some children – especially those fed formula made with tap water – lead, perhaps not ironically, to the need for extensive restorative dental work. According to a 2005 report from the U.S. Centers for Disease Control, 32 percent of American children had some form of dental fluorosis, with two to four percent of children having moderate to severe fluorosis. According to research presented at the April 2017 National Oral Health Conference in Albuquerque, New Mexico, that number has increased to fifty-seven percent of youth between the ages of six and 19.

Fluoride can poison kidney function at high doses over a short time period. And it is a particular problem for people who already have kidney disease. Among healthy individuals, the kidneys excrete approximately half of the daily fluoride intake. However, among those with kidney disease, fluoride accumulates within the body with toxic results.

Since one of the places where fluoride accumulates is the skeletal system, it can cause or exacerbate a bone disease common to people with kidney disease. The impact of low doses of fluoride given over long periods of time has not been inadequately studied, but a few studies have suggested there might be an adverse effect. A 1998 animal study, conducted by scientists at the U.S. Environmental Protection Agency, reported that exposure to just one ppm fluoride caused kidney damage in rats if they drank the water for an extended period of time, while a 2005 Chinese study found an increased rate of kidney disease among humans consuming more than two ppm over a long period of time.

A study by researchers at Mount Sinai Hospital in Toronto, Canada and published in Environment International in 2019 found that exposure to fluoride in drinking water may lead to a reduction in kidney and liver function among adolescents. The findings also suggest that adolescents with poorer kidney or liver function may absorb more fluoride in their bodies.

Also related to fluoride's impace on bones is a well-conducted study from Sweden, published in 2021 in Environmental Health Perspectives. Researchers found an increased prevalence of hip fracture in post-menopausal women associated with long term exposure to fluoride at levels in water in the same range as countries like Canada fluoridates water.

In the 1990s, it was also discovered that the pineal gland can accumulate fluoride at a higher rate than either teeth or bone. And animal studies suggest that the accumulation of fluoride in the pineal gland can reduce its synthesis of melatonin, a hormone that helps regulate the onset of puberty, among other functions.

The thyroid is another gland that seems to be affected by fluoride, particularly among those with an iodine deficiency, according to the U.S. National Research Council. In fact, until the 1970s, fluoride was used by doctors – in doses as low as two mg per day – as a thyroid-suppressing medication for patients with hyperthyroidism (over-active thyroid). Exposure in some communities with fluoridated water have been found to be in that range, which has led some to speculate a connection with the widespread problem of hypothyroidism (under-active thyroid) in the U.S.

In addition, the Physicians’ Desk Reference cautions that some people are allergic or hypersensitive to fluoride. A large, U.S. government-funded clinical trial found that one percent of individuals exposed to one mg per day of fluoride exhibited allergic/hypersensitive reactions, including skin rashes, gastric distress, and headache.

One of the most under-reported issues with a variety of toxins is the effect resulting from exposure to many of them at the same time. A study published in 2009 (Kaur T, et al. Drug Chem Toxicol.) concluded that the neurotoxic hazards caused by fluoride are enhanced by exposure to aluminum found in most vaccines.

This seems like a major set of risks, given that the main protective action from fluoride does not come from ingesting it, but from direct absorption through topical application to teeth, as in treatment by dentists or via toothpaste that contains fluoride. Interestingly, a warning was made mandatory for fluoride-containing dental products by the U.S. Food and Drug Administration in 1997: “If you accidentally swallow more than used for brushing, seek professional help or contact a poison control center immediately.”

At any rate, tooth decay rates have declined similarly in all western countries at least since the 1970s, irrespective of whether the water is fluoridated or not. In the United States, despite living without fluoridated water, rural children’s cavity rates equal those of urban children, who are more likely to drink fluoridated water, according to a large national government study of over 24,000 U.S. children published in 2003 in the Journal of Rural Health.

The risks and the lack of efficacy of fluoridating water have led an increasing number of professionals to speak out against it. For instance, thousands of doctors, nurses, dentists, dental hygienists, pharmacists, and other professionals, including some Nobel laureates, signed a Professionals Statement to End Fluoridation, which is posted at

One of these experts was Dr. Hardy Limeback, retired head of protective dentistry at the University of Toronto and a former advocate of fluoridation. In a public letter dated April, 2000, Dr. Limeback cited a large amount of research, which he said shows that the minimal benefit of fluoridation of water supplies does not outweigh the risks of long-term fluoride ingestion. He wrote, “A lifetime of excessive fluoride ingestion will undoubtedly have detrimental effects on a number of biological systems in the body and it is illogical to assume that tooth enamel is the only tissue affected by low daily doses of fluoride ingestion.” He also pointed out that the issue of mass medication of an unapproved drug without the expressed informed consent of each individual must also be addressed, and said it creates a medico-legal and ethical dilemma.

Some federal and local governments have been reconsidering the addition of fluoride to water. An expert panel commissioned by Health Canada to study the risks of fluoride exposure suggested in 2007 that the government should cut the recommended amount in drinking water, encourage the use of low-fluoride toothpaste by children, and have makers of infant formula reduce levels in their products.

In 2011, responding to a lawsuit by the Environmental Working Group (EWG) and other advocacy groups, the U.S. Department of Health and Human Services recommended that water utilities reduce the amount of fluoride added to tap water by more than 40 percent. This recommendation took effect in the U.S, although many municipalities ignored it and continue to add fluoride for their water supplies due to perceived dental health benefits.

The addition of fluoride to drinking water is banned entirely throughout most of Europe and in several other developed nations across the world.

So my conclusion is that both the research evidence and government actions indicate that fluoride in drinking water is not only unnecessary but harmful.

Wendy Priesnitz is Natural Life's co-founder and editor, as well as a journalist and author with over 40 years of experience. This article was first published in 2009, and updated in 2012, 2017, 2018, 2019, and 2022. 


Copyright © Life Media

Privacy Policy 

Life Learning BookBeyond SchoolChallenging Assumptions in Education

Natural Life's Green and Healthy Homes book

Life Learning Magazine

Natural Life Books

Childs Play Magazine

Natural Child Magazine

Natural Life Magazine