In vitro cytotoxicity assays. Potential alternatives to the Draize ocular allergy test

A short-term cytotoxicity assay carried out in multiwell test plates and a supplementary colony forming assay are both useful for screening and range finding of toxic concentrations of test agents. The highest tolerated dose (HTD), a concentration at which only minimal morphological changes were observed, was designated as endpoint in the assay. Epithelial rabbit cornea cells, murine fibroblasts, Chinese hamster lung cells, human hepatoma cells and mouse macrophage cultures were used as targets. Several of the alcohols tested at HTD in the colony forming assay were found to inhibit colony formation. An ID50 of colony formation was used as a quantitative corroborating test. The ranking of 34 toxicants was found to be virtually the same with all cell types examined. This easily reproducible, rapid in vitro test is cost-effective and can be used for preliminary large scale screening of potential toxicants.