 In 1999, the U.S. Centers for Disease Control commemorated the end of the 20th century by publishing a list of the top 10 great public health achievements. They noted that the 20th century saw an increase in life expectancy, 25 years of which can be attributed to advances in public health. Here's their list. 1. Vaccination. 2. Motor Vehicle Safety. 3. Safer Workplaces. 4. Full of Infectious Diseases. 5. Decline in Deaths from Coronary Heart Disease and Stroke. 6. Safer and Healthier Foods. 7. Healthier Mothers and Babies. 8. Family Planning. 9. Fluoridation of Drinking Water. 10. Recognition of Tobacco Use as a Health Hazard. I think we can all see that changes in our attitudes about smoking, childbirth, and family planning, safe workplaces, seatbelts, and control of infectious disease by vaccination are adding years to our lives and life to our years. Many of these achievements are under attack by ALTMAD and other groups. Consider the anti-vaccine groups, the groups opposed to helmet laws, groups opposed to mosquito spraying, religious groups opposed to certain types of family planning and sexually transmitted disease prevention, people who deny the health risks of smoking and, of course, people who oppose water fluoridation. Why is water fluoridation even on a list of the greatest public health achievements? Because in the last 65 years it has dramatically reduced tooth decay across all income levels, improving dental health for everyone in the community. As of 2008, roughly 70% of the tap water in the U.S. is fluoridated to a level of about 1 part fluoride for every 1 million parts water, compared to calcium, which is present at between 40 and 80 parts per million, and magnesium present at between 20 and 30 parts per million. While fluoride is not an essential nutrient, the right amount can greatly reduce risk of dental caries, a.k.a. cavities. It works by three mechanisms, one, promoting remineralization of eroded enamel, joining with calcium in bones and teeth or attracting it to the tooth's surface, two, replacing the hydroxyapatite in enamel with fluoroapatite, which is more resistant to acids, three, inhibiting bacterial sugar metabolism. It works most effectively when the fluoride is found at a specific level in the saliva. This means that fluoridated toothpaste does not work in the same manner as fluoridated drinking water. Fluoride treatments can promote enamel strengthening, but they are ineffective at inhibiting bacterial acids and aren't as effective as fluoride in the saliva at remineralization. Did everyone catch that because it's something that I frequently see ignored? Fluoridated toothpaste and fluoridated drinking water are not substitutes for each other. Fluoridated in your saliva has multiple actions, whereas a brief fluoride exposure from tooth brushing only has one. The best analogy I could think of is the difference between brushing and washing your hair and having it cut or styled. Both are important for keeping your hair looking good, but they aren't substitutes for each other. Also crazy hippies sometimes skip both. Heck, I'm going to say this a third time. Fluoride in water and fluoride in toothpaste do not serve the exact same purpose, although they do have some functional overlap in that they both promote dental health. Why would anyone possibly oppose such a benevolent effort? It's not necessarily because they're stupid or crazy. There's a reasonable case to be made against water fluoridation. I think the arguments about mass medication and possible health risks are worth considering. However, I want to establish what the research supports. Is fluoridation effective? The overwhelming evidence from the research literature supports a very strong yes. In studies from around the world, the introduction of 0.5 to 1 part per million of fluoride reduces the rate of dental caries by 40 to 60 percent. This is not a small effect and passes the level of correlation to the well-supported causation. In certain areas of Europe where the water is naturally fluoridated, the dental disease rates are similar to community fluoridated areas. Here's an example paper from Australia. The dental health of over 100,000 Australian children from fluoridated and unfluoridated areas was compared and normalized for age, income and housing status. The low fluoride area children had about 30 percent more cavities than the matched children in optimally fluoridated areas. This matches results from around the world where the effect is usually between 30 and 60 percent. This translates to 1.5 to 4.4 decade missing or filled teeth per child. In these studies, notice that both populations of children have equal access to fluoridated toothpaste and dental care. The argument that modern toothpaste has eliminated the need for drinking water fluoridation is not well supported by these studies. Is fluoridation cost effective? Unquestionably, it costs less than a dollar per person per year. There are two primary forms of fluoride that can be used. Some fluoride is a natural mineral that can be mined or refined from underground water reservoirs. Fluorosilic acid is a byproduct of fertilizer manufacturing. However, once they're in solution, a fluoride ion is a fluoride ion. There's no chemical way to distinguish fluoride from the two forms. The other chemicals present in the solution may be different, but I'm not convinced that just because something is a byproduct of chemical manufacture, that necessarily makes it toxic. A common tactic of opponents of fluoridation is the fear and paranoia over chemical processing, but scientists respond to specific threats, not vague and yuendo. Is fluoridation safe? At the right level, it's about as safe as we can measure. One of the challenges of treating people through drinking water is that we can't control how much they drink. We also can't pick and choose which people to exclude from treatment. Is the fertilizer byproduct more or less toxic? The 50% lethal dose, or LD50, the usual marker for relative toxicity for the two chemicals, shows that it actually takes more of the sodium hexafluorosilicate to kill 50% of a population of rats, making it slightly less toxic. The form of use is an ACS certified pure chemical, so there is no carryover of other chemicals associated with fertilizer synthesis. These LD50s put both forms of fluoride, somewhere between nicotine and caffeine, or aspirin, in toxicity. For a typical 150 pound or 70 kilogram person, the lethal dose would be around 3 to 10 grams. How much does a person get with 8 glasses of water? About 2 milligrams. There are other sources of fluoride, but the typical person probably never gets above 1,000th of a lethal dose. Compare that to the relative dose of caffeine, where every cup of coffee contains about 1% of a lethal dose. Toxicity is never an easy thing to measure, especially with repeated exposure. I share some concern about the possible effects of fluoride on bone density over a lifetime. I'd also like to see more studies on the impact of fluoride on heavy metal absorption, if only to quiet the public's concern. However, those studies that have been done don't seem to support any cause for alarm. Is fluoridation good public health policy? Science can certainly inform our policy choices, but it can't dictate the best choice for the public. There are some alternatives. In some places, milk or salt are fluoridated. In the past, some communities used fluoride pills that are taken daily. Compliance tends to be low, people forget the pills, and there's more of a risk of accidental overdose. On the whole, I think drinking water is probably the safest, easiest, and most egalitarian solution. I think it's worth having some public discussion about the issue of mass medication. It's a reasonable argument that a treatment administered through drinking water puts limits on personal choice. If we as a society deem those limitations too restrictive for the demonstrated benefits, I think a good case can be made. There is a counter argument to this, and it's that naturally optimally fluoridated water already exists and provides health benefits, and we're simply compensating in low fluoride water areas, correcting a deficiency found in nature. Most of the opponents of fluoridation I've run into on the internet are reacting out of paranoia or fear, but not all of them. Some reasonable people have valid concerns, and I can't dismiss their perspectives out of hand. The best I can do is to correct the misinformation where it appears, and hope people are smart enough to apply critical thinking to what they read. Let me briefly address some of the most flagrant myths about fluoridation. Fluoridation was used by the Nazis or Soviets in camps. This is a simple fabrication. A 1996 sociological study attempted to trace the source of this rumor, and found it in a self-printed newsletter at a small conspiracy theory press. So far as I can tell, there are no scholarly accounts of fluoride being used on prisoners. Myth two, fluoridation is a deadly substance, the primary ingredient in rat poison, and if a child swallows just a little toothpaste, you have to call poison control. Actually, as a highly reactive halogen, fluorine is found in lots of poisons, acids, and useful chemicals. However, fluoride is not by itself a very effective poison. As previously stated, nicotine is more toxic. I could just as easily say the primary ingredient in most poisons is carbon or oxygen or hydrogen. So why should you contact poison control if a child swallows a dull toothpaste? Well, fluoride can be toxic, but toothpaste also contains scouring agents, bleaches, and detergents. Not good for a child's delicate tummy. And a good guide to calling poison control, overcaution is always better than regret. Myth three, fluoride causes arthritis, cancer, allergies, autism, lupus, blindness, madness, or whatever. There are so many myths about fluoride's health effects, often confusing a vague correlation in time with causation. Since water fluoridation was introduced in the 50s and 60s in most areas, any positive trend since then is linked to fluoridation in the minds of some opponents. This is the post-hoc ergo-propter-hoc fallacy. After this, therefore, because of this. In fact, the life expectancy has been increasing steadily since the 50s. And people are much more likely to die of cancer or have diseases of old age than they were in the 30s or 40s. Likewise, certain diseases of childhood have become much more survivable or easy to diagnose. So their recorded rates are much higher. To date, so far as I know, the only conditions associated with optimal fluoridation are the potential for increased bone density problems and increased susceptibility to heavy metal absorption, both of which are somewhat tenuous links, but worth noting. In summary, I support water fluoridation because I think it's positively affected the quality of life for millions of people. You're welcome to disagree, but be prepared to bring cold, hard facts, or well-published papers in support of your view. It'll take a very strong case to overturn what many public health professionals call one of the top 10 public health achievements of modern times. Thanks for watching. Every cell of each plant and animal contains genetic information coded onto the DNA monocular cells.