INTRODUCTION 60 Solvent (CHF-33-148) was evaluated for mutagenic potential and germinal cell risk in a three tier testing approach. The first tier consisted fo in vitro microbial assays in which the test chemical was screened for mutagenic and recombinogenic activity using bacteria (Salmonella typhimurium) and yeast (Saccharomyces cerevisiae) in both plate and suspension techniques. The second tier consisted of screening the compound for mutation induction in cultured mammalian cells (L5178Y@ TK+/-) in vitro. Assays in the third tier were in vivo and consisted of a cytogenetic analysis of bone marrow cells and a dominant lethal assay on rats treated with 60 Solvent.