Where does this all leave us? It leaves us able to develop rather good animal data at dose levels that do not really interest us. That is a first-class highway that takes us where we do not want to go. It leaves us unlikely to be able to develop good data at "realistic" doses. To extrapolate animal results to man exposed at these "realistic" doses today requires assuming a mathematical model of dose-response in the animal and conservative use of this model. Then we have to jump from one species to another in ignorance of the terrain of the landing site, i.e., the many species differences. However, we will have knowledge of some important species similarities and that makes the jump a lot less dangerous. With respect to costs and benefits we are just beginning to understand some of the implications of the arithmetic. We have begun to see that there are few, if any, good ways of totaling the costs or computing the benefits. Cost-benefit may be another blind alley. Tomorrow and the next day we must do the appropriate research on species differences in metabolism and in the mathematics of the modeling and extrapolation--as a minimum. The socially related issues, such as what is an acceptable risk, what are the costs, what are the benefits, must be discussed in the open, freely. This implies recognizing that someone's costs may be someone else's benefits. (Our medical costs are our physician's source of living.) The inputs to the cost-benefit algebra are not well worked out. Our ways of working must include the adversary approach as well as the pleasanter way of cooperation. And today, we must get to precautionary decisions for man's safety and health based on the road maps from animal data--inadequate as they are. We have gotten to the neighborhood of Park Avenue and 59th Street and we can probably one day get to a lot of other places.