It is difficult to think of a worse example with which to illustrate the state of the art of quantitative risk assessment than the possible risks posed by power frequency electric and magnetic fields. Nothing seems to work. We don't know how to measure dose. We don't know whether "more is worse," let alone the shape of any effects functions. The limits that one can set with bounding analysis are too broad to be of much use. Yet despite all these problems, the science is far better than that available for such widely regulated risks as sulfur air pollution. This paper briefly reviews the subject and summarizes some of the problems and lessons.