Original sentence: ”  Many communities need to reduce fluoride exposure
Edited sentence: Dental fluorosis may pose a public health problem at high fluoride levels, and some communities need to reduce fluoride exposure.For both, the optimal fluoride concentration of drinking water was found to be 0.7-1.2 mg/litre, depending on climate, though supplementation of table salt or milk was also effective, as were fluoride tablets.However, at CDC- and WHO-recommended fluoride levels in drinking water, fluorosis affects only a small proportion of the population, and for those to an extent that is not a health risk and is "rarely considered aesthetically objectionable".The United Nations and World Health Organization found that reduction of tooth decay depends on the incorporation of fluoride both in developing teeth and on the exposure of tooth enamel to fluoride in the mouth.The overall benefit of these methods depended on the initial incidence of cavities, the amount of fluoride in the diet, and the quality of dental care in the community.Topical fluoride, as from toothpaste, provided additional benefit, but was not a substitute for consumption