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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
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 recent, large-scale studies have found that fluoridated water
provides only a minor benefit to teeth, or no demonstrable benefit at all.
Although there is some controversy surrounding the research about the health
effects of fluoride, an increasing number of animal and human studies are
indicating problems due to its use. These risks include exposure to heavy metals
such as lead, arsenic and radium that contaminate the industrial-grade fluoride
that municipal water systems use. 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
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.
Also worrisome are studies from China, Mexico, India and Iran that have found a
strong association between water with high fluoride levels and sharply reduced
IQs in children.
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,
ironically, to the need for extensive restorative dental work. According to a
2005 report from the U.S. Centers for Disease Control, thirty-two percent of
American children now have some form of dental fluorosis, with two to four
percent of children having moderate to severe fluorosis.
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 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.
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
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.
Fluoride is a byproduct of the phosphate fertilizer industry that
has been added to many municipal water supplies for decades, although it is not
an essential nutrient.
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.
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.
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
The risks and the lack of efficacy of fluoridating water have led an
increasing number of professionals to speak out against it. As of mid-April,
2009, 2,400 doctors, nurses, dentists, dental hygienists, pharmacists, and other
professionals, including some Nobel laureates, have signed a Professionals
Statement to End Fluoridation, which is posted at
One of these experts is Dr. Hardy Limeback, 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. The City of Toronto’s drinking water now contains half the fluoride it
did before 1999 and the province of Quebec cut the recommended amount by
forty-two per cent in 2004.
Wendy Priesnitz is Natural Life's editor,
as well as a
journalist and author with over 35 years of experience.