What is an engineer working for a cellphone company or some other company making products that emit rf radiation to do went confronted with the ongoing concerns about the health effects of rf fields? Cell phones can certainly be redesigned to reduce or eliminate this problem, but, of course, any design that will lead to reduced emission will probably cost more. We won’t know for many years what the final answer is regarding cell phones are probably safe to use. What is the prudent and ethical thing to do in designing such products in an atmosphere where some doubt about safety exists? This case illustrates the problems that engineers have in dealing with and managing the unknown.