Isolated digestive gland epithelium from a model invertebrate organism was used in an ex vivo system to assess the potential of nanoparticulate TiO(2) to disrupt cell membranes. Primary particle size, surface area, concentration of particles in a suspension, and duration of exposure to TiO(2) particles were all found to have effects, which are observed at concentrations of nano-TiO(2) as low as 1 μg mL(-1). The test system employed here can be used as a fast screening tool to assess biological potential of nanoparticles with similar chemical composition but different size, concentration, or duration of exposure. We discuss the potential of ex vivo tests to avoid some of the limitations of conventional in vitro tests.