[efirman]

Here is the CDC take on the products used in fluoridation. https://www.cdc.gov/fluoridation/engineering/wfadditives.htm... They are all subject to NSF Standard 60 requirements for purity. "Some have suggested that pharmaceutical grade fluoride additives should be used for water fluoridation. Pharmaceutical grading standards used in formulating prescription drugs are not appropriate for water fluoridation additives. If applied, those standards could actually exceed the amount of impurities allowed by AWWA and NSF/ANSI in drinking water."