Opposition to fluoridation has existed since its initiation in the 1940s.[12] During the 1950s and 1960s, conspiracy theorists claimed that fluoridation was a communist plot to undermine American public health.[13] In recent years water fluoridation has become a prevalent health and political issue in many countries, resulting in some countries and communities discontinuing its use while others have expanded it.[14][15] The controversy is propelled by a significant public opposition supported by a minority of professionals,[16] which include researchers, dental and medical professionals, alternative medical practitioners, health food enthusiasts, a few religious groups (mostly Christian Scientists in the U.S.), and occasionally consumer groups and environmentalists.[17] Organized political opposition has come from libertarians,[18] the John Birch Society,[19] and from groups like the Green parties in the UK and New Zealand.[20]