Dental fluorosis is an irreversible condition caused by excessive ingestion of fluoride during the tooth forming years. It is the first visible sign of overexposure to fluoride.
Fluorides are slightly more toxic than lead, and slightly less toxic than arsenic. - Clinical Toxicology of Commercial Products
The California Code of Reglations, title 22 lists 791 chemicals as "Hazardous Waste." 39 of these are fluoride compounds. Two are used for drinking water fluridation in Sacramento CA. #384 Hydrofluosilicic Acid (X,C) and #674 Sodium Fluoride (X)