Evaluating Solvent Safety in Chromosome Aberration Assays for Genetic Toxicology

The chromosome aberration test (CAT) is a widely used in vitro assay for detecting structural chromosomal damage induced by clastogenic chemicals. It plays a crucial role in genetic toxicology, helping assess the potential genotoxic effects of pharmaceutical compounds, environmental contaminants, and industrial chemicals. This test is particularly valuable in regulatory studies, as chromosomal aberrations are linked to mutagenicity, carcinogenicity, and hereditary diseases. The test evaluates their occurrence in cultured human peripheral blood lymphocytes (HPBL) or other mammalian cells after exposure to test chemicals. Accurate solubility of test compounds is critical for determining the highest feasible concentration in CAT without compromising cell viability or assay integrity. However, selecting an appropriate solvent remains a challenge in genetic toxicology, as the solvent must ensure chemical stability, support cell growth and metabolic activation, comprise ≤ 1% of the final treatment medium, and be compatible with human blood cells. In this study, we systematically evaluated the cytotoxic effects of various solvents on HPBL at 0.5% and 1% concentrations over a 22-h exposure period, replicating approximately 1.5 normal cell cycle durations without the inclusion of a metabolic activation system. The solvents tested included dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), acetone, acetonitrile, ethyl acetate, ethanol, methanol, p-dioxane, tetrahydrofuran (THF), and dimethylacetamide. Our findings revealed that N,N-dimethylformamide and acetone were noncytotoxic at 0.5%, while ethanol, methanol, acetonitrile, and dimethyl sulfoxide were noncytotoxic at both 0.5% and 1% concentrations, whereas other solvents exhibited cytotoxic effects at both concentrations. These findings provide valuable insights for genetic toxicologists, enabling better selection of optimal solvents for CAT-based genotoxicity assessments. By refining solvent choices, researchers can improve chromosome aberration analysis accuracy, facilitating more reliable regulatory decision-making in genetic toxicology and pharmaceutical safety evaluations.