ABSTRACT
Once appropriate environmental samples have been collected and prepared for genotoxicity bioassay, we recommend a tier/battery structure for evaluating their potential genotoxicity. Tier one is composed of well validated, well established in vitro genotoxicity assays. The assay systems included are: Bacterial Mutation, Mammalian Cell Gene-Point Mutation, Mammalian Cell Cytogenetic Assays and Hepatocyte DNA Repair. Tier two which is intended for confirmation is composed primarily of in vivo bioassays excepting in vitro cellular transformation. The in vivo bioassays in tier two are: Drosophilia Recessive Lethal, Micronucleus Test, Dominant Lethal Assay, Bone Marrow Sister Chromatid Exchange, Chromosome Aberration and In Vivo/In Vitro Hepatocyte DNA Repair. Due to expected limited sample size, we recommend a "priority" in vitro genotoxicity testing scheme. The priority bioassays are the Ames/Salmonella Mutation Assay, the Chinese Hamster Ovary Sister Chromatid Exchange (CHO/SCE) and Aberration Test and the Primary Hepatocyte DNA Repair Test. Depending upon the outcome of testing in the "priority" genotoxicity assays, additional tests from tiers one and two are recommended.
