Toxicity of Ionic Liquids Towards Mammalian Cell Lines

This review aims at summarizing the state of the art knowledge on the effects different ionic liquids and their substructural elements cationic head group, side chain attached to the head group and the anion species can exert in mammalian cell cultures. Special emphasis is given on the following questions when analyzing the available data: (i) What are ionic liquids, which species are we dealing with and which features make them unique from a technological but - even more important - from a toxicological point of view? (ii) which and how much information do we need aiming at a sound hazard and risk assessment of ionic liquids and at a sustainable design of these substances? (iii) what can we learn from the existing cytotoxicity studies with respect to the latter question and what we cannot? and finally (iv) what needs to be done in the field of ionic liquids' toxicology? Analyzing the existing cytotoxicity data guiding principles for a sustainable design of inherently safer ionic liquids are derived and the advantages and limitations of mammalian cell lines in deriving them are presented. Furthermore, modes of toxic action as well as mixture effects and the prediction of these effects using quantitative structure-activity relationships (QSAR) approaches are discussed. Finally, the future needs in ionic liquids' toxicology are discussed with respect to regulatory frameworks and the general hazard assessment of these substances.