It is a fact, as confirmed by Workplace Health and Safety Queensland, that sodium fluoride has been used as pesticide, insecticide, fungicide, and rodenticide. So, when opponents of fluoridation state that the government is putting rat poison into public drinking water to treat people, they are correct, and that very same government agrees with them.
Sodium fluoride is one of the water fluoridation chemicals recommended by the National Health and Medical Research Council, and it is expressly added to drinking water to treat or prevent the disease of dental caries.
However, proponents of fluoridation make the counter-argument that warfarin is also used both as a rat poison and a medical treatment for humans. They are correct. Warfarin is indeed used both as a rat poison and a medical treatment for lowering the risk of blood clots.