Summary and Perspectives

Abstract

The job of attempting any sort of summary of so much material of such diversity is a formidable one, certainly when the task allocated includes sketching some perspectives. I shall attempt to tackle it in three stages, first mentioning some of the highlights from the various contributions, then offering a few general comments on characteristics of higher plants as test subjects for mutagen monitoring, and concluding with a brief-indeed very briefconsideration of perspectives. My comments are from one whose interests lie in plant physiology and cytogenetics; I am not myself active in the field of mutagenesis, so I hope you will bear with my deficiencies should anything I say sound erroneous or tendentious. The workshop opened with the paper from Dr. de Serres, who offered us some targets for the meeting. He reminded us of the range of purposes for which we may wish to monitor the environment for mutagenic agents, noting that we are not only concerned with the well-being of man, but with his plants and animals-and one might hope also the biome at large, not only those elements of it of direct human concern. He mentioned the impressive figure of 63,000 man-made chemicals now littered about the earth, with a growth rate of some 3000 new ones per year: indeed an intimidating screening task. As for the screening systems, he stressed the need for specificity; the requirement that the data gathered should be relevant to the problem, a consideration of great importance when it is proposed to extrapolate from results obtained with one class of organism to another, different, class. Dr. Heath followed with a sobering talk in which he gave us a glimpse of cancer epidemiology in the U. S. Among the many significant points he made I recall especially his comment on the long latent period between first exposure to a causal agent and the ultimate effect. He referred to the case histories of