All medical advances involve risks. Nothing ventured, nothing gained, as the saying goes. But that does not mean all risks are worth taking, or that we would all make the same choices. In at least two of the four case studies, DES and swine flu (and some might add the artificial heart), the risks were definitely not worth running, a judgment some observers made at the time. The periodic public controversies over genetic engineering also underscore the wide differences in people's responses to, and even definitions of, risks.

This chapter looks at how we view risks in general and the risks of medical innovation in particular. What makes some risks “acceptable” and others not? Why are patients, like most of those who took DES, often not told about the uncertainties and hazards of treatments? More broadly, what is or reasonably could be done to protect individuals and society against the potential dangers of new medical and scientific technologies? In the picture that emerges, the central problem appears to be the lack of concern about possible hazards on the part of those making decisions on the one hand, and the lack of communication of either dangers or doubts to those at risk on the other. These failures explain much about why the warnings of scientific and lay critics in the four cases had so little impact and why even predicted problems were not avoided.