 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.Of Africa's 1.1 billion people, about 400,000 get artificially-fluoridated water (in Libya, data pre-2003).