Thalidomide-like malformations caused by Tween surfactant in mice.

The nonionic surfactant Tween 20 [polyoxyethylene(20)sorbitan monolaurate] is one of the more frequently encountered xenobiotics. Surface-active agents of the Tween type are used as constituents of cleaning agents, as food additives and as vehicles in the drug and cosmetic industry [1], Because of its good solubilizing properties Tween 20 has been used in teratological experiments as a solubilizer of poorly soluble substances, e.g. thalidomide [2], its hydrolytic metabolites [3] and structurally related compounds [4]. In these investigations, performed with Swiss mice, Tween 20 was found to have no effect on developing embryos when given alone in doses of 10 ml/kg (diluted with physiological saline). However, observations made some years ago casted doubt on the assumption that Tween 20 can be regarded as an inert vehicle in teratological experiments. In an attempt to apply a thalidomide metabolite to CBAand C57BL-mice we found that Tween 20, given intraperitoneally in a dose of 2.5 ml/kg (diluted with physiological saline) killed more than 50% of the animals. Similar results were described by Scott et al. for another mouse strain [5]. Another nonionic surfactant, Triton W. R. 1339, had proved to be teratogenic in Swiss mice [6]. Further investigations on the effect of several Tween types on developing sea urchins showed serious developmental defects in the embryos [7], In