The best protection against environmental mutagens is to identify them
before they ever come into general use. But it is always possible that
some substance will escape detection and affect a large number of
persons without this being realized until later generations. This
article considers ways in which such a genetic emergency might be
promptly detected. A mutation-detecting system should be relevant in
that it tests for effects that are as closely related as possible to
those that are feared. It should be sensitive enough to detect a
moderate increase in mutation rate, able to discover the increase
promptly before more damage is done, responsive to various kinds of
mutational events, and designed in such a way as to maxi- mize the
probability that the Gause of an increase can be found. Methods based on
germinal mutation necessarily involve enormous numbers of persons and
tests. On the other hand, with somatic mutations the individual cell
becomes the unit of measurement rather than the in- dividual person. For
this reason, I think that somatic tests are preferable to germinal
tests, despite the fact that it is germinal mutations which are feared.