Water fluoridation
Currently about 372 million people (around 5.7% of the world population) receive artificially-fluoridated water in about 24 countries, including Australia, Brazil, Canada, Chile, Republic of Ireland, Malaysia, the U.S., and Vietnam. 57.4 million people receive naturally occurring fluoridated water at or above optimal levels in countries such as Sweden, China, Sri Lanka, Finland, Zimbabwe and Gabon. Community water fluoridation is rare in Continental Europe, with 97–98% choosing not to fluoridate drinking water. Fluoridated salt and milk is promoted in some European countries instead. Water fluoridation has been replaced by other modes in many countries where water supplies are too decentralized for it to be a practical choice, or existing natural fluoride levels were already ample, including Germany, Finland, Japan, Netherlands, Sweden, Switzerland, Denmark and at a time Israel. Cessation of water fluoridation has been demonstrated in scientific studies such as a recent one in Calgary, Alberta, to result in increased rates of dental decay. While fluoridation can result in mild dental fluorosis, this effect is barely detectable and causes no concerns with the appearance or health of teeth. Countries practicing artificial water fluoridation vary in their recommended fluoride levels according to what health authorities in each have determined to be most effective for its citizens. The US recently reset the recommended optimal level of fluoride in drinking water, lowering it slightly, because of observed increased Fluorosis levels, likely due to additional fluoride sources like toothpaste and mouthwash which were not present when this level was originally set.