 Websites, which are increasingly used by the public for health information, contain a wide range of material about fluoridation ranging from factual to fraudulent, with a disproportionate percentage opposed to fluoridation.Antifluoridationist literature links fluoride exposure to a wide variety of effects, including AIDS, allergy, Alzheimer's disease, arthritis, cancer, and low IQ, along with diseases of the gastrointestinal tract, kidney, pineal gland, and thyroid.Many people do not know that fluoridation is meant to prevent tooth decay, or that natural or bottled water can contain fluoride.