Grand Rapids, Michigan has become the most recent city to question the practice of fluoridating public water. It joins a growing number of local governments that have questioned the use of many chemicals that had formerly been taken for granted.

Grand Rapids was actually the first city in the world to add fluoride to its public water supply, based on assurances from the government that the chemical reduces the risk of tooth decay while posing no serious risks.

However, based on a number of studies linking fluoride to problems with the thyroid, kidneys, central nervous system and skeletal system, the city's director of environmental sustainability has ordered a new review of the risks and benefits of the chemical.

Fluoridation opponents have cheered the news, confident that the scientific evidence is clear. "If Grand Rapids falls, that could be the beginning of the end of fluoride," said Paul Connett, director of the Fluoride Action Network.