Tooth decay remains a major public health concern in most industrialized countries, affecting 60–90% of schoolchildren and the vast majority of adults. Water fluoridation reduces cavities in children, while efficacy in adults is less clear. A Cochrane review estimates a reduction in cavities when water fluoridation was used by children who had no access to other sources of fluoride to be 35% in baby teeth and 26% in permanent teeth. However this was based on older studies which failed to control for numerous variables, such as increasing sugar consumption as well as other dental strategies. Most European countries have experienced substantial declines in tooth decay, though milk and salt fluoridation is widespread in lieu of water fluoridation. Recent studies suggest that water fluoridation, particularly in industrialized nations, may be unnecessary because topical fluorides (such as in toothpaste) are widely used, and caries rates have become low.