The scientific understanding of cancer and degenerative disease is being aided by new methodologies which are now used to approach the problem of environmental and occupational carcinogens and anticarcinogens. This paper reviews these powerful new tools and relates them to “;natural” mutagens and carcinogens in food. It also discusses the use of oxygen radicals as a cause of degenerative disease associated with aging. Since no human diet can be totally free of carcinogens or mutagens, it is necessary to consider the risks of alternative courses of actions and to quantitate the magnitude of the risks through the “;quantification” of these risks. Since carcinogens and anticarcinogens differ in their potency in animals over one million fold, the extrapolation of risks from rodents to humans is difficult but it is a first step. Despite better understanding of all of these risks, it is important to realize that the overall trend in life expectancy in the United States is continuing steadily to improve.