Significance of various type chromosome aberrations for man.

A goal of mutagenicity testing is to develop a test that detects genetic damage and mutations with great sensitivity, and to have this test relevant to man. No test available at the present time completely fulfills this goal, and a variety of compromises have been and continue to be made in test systems. In considering cytogenetic techniques it is quite clear that these are excellent methods for detecting chromosomal abnormalities. Changes in chromosome number and translocations that can be heritable can be detected and are significant to the human population. This is clear enough that it does not require further discussion. This does not mean that all details of this methodology are established, but there is no disagreement in the principle that cytogenetic tests can supply this information. In the present paper I would like to present three questions relating to the significance of cytogenetic abnormalities in which there is not uniform agreement. The first of these questions is whether or not chromosome abnormalities in the form of chromosome breaks or clastogenic events can serve as an indicator or test system for gene mutations. The basis of this possibility is the high correlation between the ability of an agent to produce gene mutations, and its ability to produce chromosome breakage. These correlations are seen with both x-