to a solution of certain other analogous pollution problems, especially those we have now with pesticides, which appear to be the world's most dangerous pollutants. First, the attitudes that allowed worldwide contamination of the earth with radioactivity and which now allow other even more serious pollutions are important and still dominant, although weakening. The most important assumption that led to the problems with radioactivity is the assumption of dilution. Toxic materials released into the environment are widely assumed to be diluted to innocuousness. If there are local effects from the toxicity, they are transient; an abundant and vigorous nature repairing any dam