One successfully demonstrated application of ionic liquids (ILs) is to produce flexible polymeric materials, i.e., as plasticizers. However, the use of ILs as plasticizers, especially in medical plastics and children's toys, requires a thorough toxicological investigation. This is particularly important considering the safety concerns associated with leaching of many traditional plasticizers. This paper encompasses cellular biology and engineering aspects of the application of ILs as novel plasticizers by analyzing the cytotoxic effects of a variety of ILs on Drosophila melanogaster (fruit fly) S2 cell culture. While the effects observed have been correlated with previous observations, the cytotoxicity of ILs was found to depend on the selection of specific cations, anions, exposure time, concentration and solubility of the ILs in the culture media, and the toxicity of the parent chemicals used to synthesize the ILs.