Final answer:
Community water fluoridation adjusts fluoride in drinking water to prevent tooth decay, with a typical concentration less than 4 ppm. It is considered the most cost-effective method to reduce tooth decay population-wide, contrasting with toothpaste, which often has higher concentrations.
Step-by-step explanation:
Community water fluoridation is the practice of adjusting the fluoride concentration in water to an optimal level that helps prevent tooth decay. The concentration used in community water fluoridation typically maintains fluoride levels that are less than the maximum recommended by the U.S. Environmental Protection Agency (EPA), which is 4 parts per million (ppm). An average person consuming water with the maximum recommended fluoride concentration of 1.0 ppm, as proposed by the World Health Organization, would ingest about 1.92 milligrams of fluoride daily if they drink 1,920 mL of water. Any excess over optimal levels can lead to dental and skeletal fluorosis, but these issues are most frequent in areas with high natural fluoride concentrations in the groundwater.
Despite the availability of fluoride in products like toothpaste and mouth rinses, community water fluoridation remains the most cost-effective method for reducing tooth decay across the population. Fluoride levels vary globally, and the effectiveness of fluoride in preventing tooth decay often requires concentrations above 1,000 ppm in toothpaste, which is higher than the levels typically found in drinking water.