As a retired dentist, I can state that the amount of fluoride in this product, and in other consumer product, is not, in any way harmful. Numerous studies over decades have shown not the slightest evidence that there is there is any link whatsoever to illness, or any harmful health condition. Any connection to thyroid disease has been thoroughly disproven. I do agree that fluoride can be harmful IF used indiscriminately or given in OVERDOSE. This would not occur, if used according to directions. A dentist would have nothing to gain by promoting the use of a fluoride containing product.