AN INTRODUCTION AND STUDY DESIGN

Under the sponsorship of the International Programme on Chemical Safet y (IPCS), 17 laboratories from diverse regions of the world participat ed in evaluating the utility of four plant bioassays for detecting gen etic hazards of environmental chemicals. The bioassays included in thi s collaborative study were: Arabidopsis thaliana embryo and chlorophyl l assay and Tradescantia stamen hair assay, Tradescantia paludosa micr onucleus assay and Vicia faba root tip assay. Four to six laboratories participated in the performance of each of the bioassays. All laborat ories participating in a particular bioassay were supplied with unifor m plant material as well as a standardized protocol. Five direct actin g water soluble test chemicals, i.e. maleic hydrazide, methyl nitrosou rea, ethyl methanesulfonate, sodium azide and azidoglycerol, were sele cted for this study. The study was designed to be completed in three p hases. Ethyl methanesulfonate was used as a positive control and has a lready been reported earlier (Sandhu et al., 1991). The data from the remaining four chemicals used for the evaluation of four plant test sy stems in the first phase of the collaborative study are reported in th is issue.