Toxicity of Ethanol in Low Concentrations

Purpose: To define the threshold ethanol concentration that is toxic to cultured cells. Methods: Three malignant cell lines and freshly isolated normal rat hepatocytes were exposed to 0–50% (vol.) ethanol (concentrations used were 0, 5, 10, 15, 20, 25, 30, 40 and 50%) on tissue culture plates for 0.25–60 min (exposure times used were 0.25, 5, 10, 20, 30, 40, 50 and 60 min). Cytotoxicity was estimated by trypan blue exclusion test and from 3H-thymidine incorporation. Results: All cells were killed by a 15-s exposure to 30–40% ethanol while a concentration as low as 15–20% gave a total response after 5–10-min exposures. After a one-hour exposure of F9 carcinoma cells and hepatocytes, a total or nearly total response was achieved with 10% ethanol. The cytotoxic effect was thus dependent both on the exposure time and on the concentration of ethanol. There were no significant differences in ethanol tolerance among the cell types. Conclusion: Ethanol seemed to kill cells in the cell culture effectively in much lower concentrations than those currently used in tumour ablation.