Who do you call when you need someone to rail against something that the U.S. Department of Agriculture, World Health Organization, and American Dietetic Association say is not only safe, but is a potential lifesaver? In their campaign against food irradiation, Ralph Nader’s Public Citizen turns to Dr. Samuel Epstein, who was ranked last among a group of scientists in terms of confidence in level of expertise on environmental cancer by the American Association for Cancer Research. Sounds like desperation time…