text: H.T. Dean's "21-city Study" helped start this policy, which was partly inspired when Frederick McKay noted a community in Pikes Peak that exhibited what was called "Colorado Brown Stain".
full_question: H.T. Dean's "21-city Study" helped start this policy, which was partly inspired when Frederick McKay noted a community in Pikes Peak that exhibited what was called "Colorado Brown Stain". Charles Bett claimed this policy was "better than using the atom bomb" at achieving Communist goals, a conspiracy theory satirized as an attempt to "sap and impurify" the "precious bodily fluids" of Americans in Dr. Strangelove. Grand Rapids was the first (*) city to implement this policy. Recently, Health and Human Services recommended this supplementation be reduced to 0.7 milligrams per liter since Americans already receive the additive used through toothpaste. For 10 points, name this process in which a namesake ion is added to the water supply to help prevent tooth decay.
first_sentence: H.T. Dean's "21-city Study" helped start this policy, which was partly inspired when Frederick McKay noted a community in Pikes Peak that exhibited what was called "Colorado Brown Stain".
raw_answer: fluoridation [or obvious equivalents such as adding fluoride to water]