One of the controversies raging across Australia right now is the use of fluoride in drinking water to prevent oral decay. Proponents of this technique, including the Australian Dental Association (ADA) point out that it has been shown to significantly reduce incidence of cavities, especially in children, and promote, strong, healthy, and beautiful teeth. Opponents of this practice say that fluoride is a poison and putting it in our drinking water is equivalent to poisoning the entire population, something that they often imply is intentional, part of a conspiracy to make the people docile and subservient.

Although it’s true that fluoride can be poisonous, people who object to the use of fluoride seem to have a basic misunderstanding of how poison works.

The Dose Makes the Poison

It is, frankly, inaccurate to say that fluoride “is a poison.” The essential concept that fluoridation opponents seem to miss is that almost everything is poisonous in high doses, and almost nothing is so toxic that even the tiniest trace is dangerous. Most compounds found in our world have tolerable levels, and levels at which they become poisonous. Many essential nutrients are also toxic at the wrong levels. For example oxygen (and by extension love) can be deadly when the levels are too high, though, of course if we’re deprived of it we will die.

It may be hard for fluoridation opponents to imagine this for fluoride, so let’s start by considering a toxic heavy metal: copper. People exposed to high levels of copper experience gastrointestinal distress (including bloody vomit), low blood pressure, and jaundice in the short term. Long-term exposure to high levels of copper lead to liver and kidney damage.

However, people with copper deficiencies experience anemia and degeneration of their nervous system.

Is copper a poison? Of course not, it’s a vital nutrient that can become poisonous at high levels.

Misunderstanding Poisonous Doses of Fluoride

If you look at the literature against fluoridation, it’s full of citations for papers showing that fluoride does, indeed, have toxic effects. The problem is that the people citing these papers don’t seem to have read or understood them, because in every case the situation described is not domestic water fluoridation, but contaminated water supplies with levels greatly in excess of that used by municipal water supplies.

For example, opponents of fluoridation in Gladstone, where fluoridation was recently bolstered by the outcome of the Queensland Child Oral Health Survey, said fluoride “causes thyroid problems, and causes ADHD and other brain problems in children.”

Yes, fluoride can cause thyroid problems, according to this recently published study. But if you look at the areas where this is occurring, the population is drinking naturally-contaminated water that is either 2.6 ppm (parts per million) or 5.1 ppm. The level at which water is fluoridated in municipal water is 0.7 ppm. In other words, thyroid problems are experienced in regions where people are exposed to 4-7 times the recommended dose of fluoride.

A similar story is found for “brain problems in children.” This study shows that people who consume high levels of fluoride experience a decrease in IQ. However, in some cases the populations were exposed to drinking water with fluoride levels as high as 11.5 ppm, 16 times the recommended dose and nearly three times what is considered a toxic dose! Even so, researchers in this article noted, “The estimated decrease in average IQ associated with fluoride exposure based on our analysis may seem small and may be within the measurement error of IQ testing.” In other words, even in this population the purported decrease in IQ is less than the error range of IQ testing.

Nonetheless, it seems that anti-fluoridation forces are growing stronger across the country (and around the world).

Every cloud has a silver lining, though, as this will likely mean more paying work for dentists and cosmetic dentists.