Introduction: Utilization of higher plant systems as monitors of environmental mutagens

Research over the past 10 years has clearly demonstrated the presence of mutagens among the numerous man-made and naturally occurring chemicals in our environment. These mutagens occur in all classes of chemicals, including foods, drugs, cosmetics, pesticides, household and industrial chemicals as well as in pollutants of both air and water. More recently, a high correlation has been found between carcinogenic and mutagenic activity; at least 90–95% of chemical carcinogens are mutagens. There is a widespread expectation that the discovery of mutagenic activity in chemical screening programs may alert us not only to mutagenic potential in man, but carcinogenic potential as well. The types of genetic damage which can be produced are numerous and the specificity of chemical mutagens makes it possible for one type of effect to be produced predominantly or exclusively. Thus, any screening program must consist of a battery of tests capable of detecting nondisjunction, chromosome aberrations, gene mutations (point mutations as well as interstitial deletion), in addition to more subtle effects of DNA repair. In addition, since innocuous chemicals can be converted by mammalian metabolism to potent mutagens and carcinogens, these metabolites must be evaluated as well as the parent compounds. Chemicals such as air pollutants present particular problems for mutagenicity testing using conventional microbial assays. Some of these problems can be overcome by using various higher plant systems. The general utility of these systems needs to be evaluated in terms of the types of genetic damage which can be detected, relative sensitivity, and general utility for use in mutagen screening and monitoring.