The present invention provides methods of determining a level of toxicity of a given compound based on in vitro assays. The present invention provides particular methods of determining organ-specific toxicity and species-specific toxicity of a given compound based on in vitro assays. In addition, the present invention provides methods of determining a level of toxicity in normal tissue for an anti-tumor compound. The methods include providing at least one cell type and culturing the cell type in the presence of at least one concentration of the chemical compound, measuring at least one indicator of cell health at the at least one concentration of compound for the at least one cell type, and performing a concentration response analysis, from which a toxic concentration can be determined.