Cytotoxicity study of 32 MEIC chemicals by colony formation and ATP assays.

The cytotoxicity of the first 32 of the 50 chemicals listed in the Multicentre Evaluation of In Vitro Cytotoxicity (MEIC) programme was evaluated by colony formation (BALB 3T3 cells) and adenosine triphosphate (ATP) assays (HL-60 cells and mouse erythrocytes). Significant correlations (r = 0.9-0.95) were obtained with ID(50) values (50% inhibition dose in comparison with the control) of the 23-30 chemicals from which such values could be obtained, in erythrocytes v. HL-60 cells, BALB 3T3 v. HL-60 cells and BALB 3T3 cells v. erythrocytes, respectively. When ID(50) values from colony formation and ATP assays of nine or 10 chemicals were compared with human acute oral lethal dose, human acute lethal blood concentration and mouse oral LD(50), close correlations (r = 0.80-0.97) were seen between data from in vitro and in vivo tests. These results suggest that colony formation and ATP assays are useful for screening chemicals.