In Vitro Cytotoxicity Tests on Cultured Human Skin Fibroblasts to Predict the Irritation Potential of Surfactants

A comparative study of the cytotoxicity of 17 surfactants was performed in vitro on cultured human skin fibroblasts to predict their irritation potential under different experimental conditions: test media, presence of proteins, various times of exposure (2–72 hours), and evaluation methods. For cytotoxicity, the tetrazolium MTT assay after exposure for 2 hours in Hank's medium (HBSS) seemed to be more sensitive than protein and LDH leakage tests. Cytotoxicities in HBSS and in minimum Eagle's medium (MEM) were very similar. Addition of 10% fetal calf serum (FCS) to MEM decreased the cytotoxicity of surfactants; however, their order of cytotoxicity was generally the same in MEM with or without FCS. Cytotoxicity increased with incubation time, but the overall ranking remained identical. Non-ionic polyoxyethylene 20 ethers (Brij 35, 58, 78 and 99) surfactants, although considered to be non-irritant in vivo, revealed a high cytotoxic effect in our cell culture system. A good correlation with the results of in vivo Draize rabbit eye irritancy was found only when they were excluded.