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After we had our daughter, I started looking into the fluoride issue and was surprised at the lack of evidence regarding its safety, and the evidence suggesting

After we had our daughter, I started looking into the fluoride issue and was surprised at the lack of evidence regarding its safety, and the evidence suggesting potential problems. I do think it's a good example of how people with reasonable, rational concerns can be dismissed as loonies of the tin-foil-hat variety; there's probably lots of lessons from it for other issues today. At the same time, the evidence works both ways. I was worried about a lot of the evidence suggesting neurodevelopmental problems, until I came a cross a reasonably large-scale study, somewhat of a quasi-experiment, from New Zealand that seemed to definitively suggest fluoride is safe. The problem with the JAMA study and others like it is that it's fundamentally observational, with lots of potential residual confounders. The conclusion that fluoride has neurodevelopmental effects in boys, but not girls, isn't in itself implausible, but it does raise questions about the generalizability of its conclusions. Clearly an experiment is probably not possible, but I don't think anything is going to get resolved in the absence of something even more rigorous. I'm not sure exactly what that would be but a simple observational, even predictive, study, probably isn't enough. Even that NZ study I was compelled by probably isn't quite right.

adrian_b 5y ago
Regardless which is the true threshold for toxicity of fluoride in humans, which probably will never be known precisely, as experiments are too dangerous, adding fluoride to drinking water is unbelievably stupid. A human needs to drink various quantities of water per day, depending on ambient temperature and humidity, on what kind of activities are done and on what kind of food is eaten. The required quantity of water may vary from almost nothing when the water is provided by the food, to several liters. So the quantity of fluoride ingested per day may easily vary by ten times. Because it is unpredictable how much fluoride will be ingested and there is a high uncertainty about the distance between an optimal dose for teeth and a dose with toxic effects, it should be obvious that this is not the right way to use fluoride. The right way is to use toothpaste with fluoride, which gives all the benefits and none of the disadvantages, because only a very small quantity of fluoride is ingested. The only argument in favor of dumping fluoride in the drinking water is that "most people are poor and stupid and they will not wash their teeth". I do not know how true is this argument in USA, but if it were true, the solution would be to better educate all people instead of choosing actions with unpredictable health effects, which punish the people who know to wash their teeth by supposingly aiding those who are ignorant.

adrian_b 5y ago

Regardless which is the true threshold for toxicity of fluoride in humans, which probably will never be known precisely, as experiments are too dangerous, adding fluoride to drinking water is unbelievably stupid. A human needs to drink various quantities of water per day, depending on ambient temperature and humidity, on what kind of activities are done and on what kind of food is eaten. The required quantity of water may vary from almost nothing when the water is provided by the food, to several liters. So the quantity of fluoride ingested per day may easily vary by ten times. Because it is unpredictable how much fluoride will be ingested and there is a high uncertainty about the distance between an optimal dose for teeth and a dose with toxic effects, it should be obvious that this is not the right way to use fluoride. The right way is to use toothpaste with fluoride, which gives all the benefits and none of the disadvantages, because only a very small quantity of fluoride is ingested. The only argument in favor of dumping fluoride in the drinking water is that "most people are poor and stupid and they will not wash their teeth". I do not know how true is this argument in USA, but if it were true, the solution would be to better educate all people instead of choosing actions with unpredictable health effects, which punish the people who know to wash their teeth by supposingly aiding those who are ignorant.