This month's issue of Experimental Dermatology features a publication of the results of the NANODERM Project, an EU Fifth Framework Program Project (‘Quality of skin as a barrier to ultrafine particles’, QLK4-CT-2002-02678). The paper, entitled 'Investigation of micronized titanium dioxide penetration in human skin xenografts and its effect on cellular functions of human skin-derived cells', describes the in vivo investigation of penetration of TiO₂ via human skin transplanted to immunodeficient mice and the in vitro measurement of effects of nanoparticles on various functional properties of numerous epidermal and dermal cells in culture.

The study reports the ‘first evidence that TiO₂ nanoparticles in vivo do not penetrate through the intact epidermal barrier.’ 

The paper concludes that the data unambiguously argue for that, in the case of intact epidermal barrier, TiO₂ nanoparticles in vivo do not penetrate the stratum corneum and hence do not reach the deeper, ‘living’ cell layers of the human skin. However, in the cases of impaired barrier function, damaged stratum corneum or putative penetration via the appendages of the skin, it can be assumed that TiO₂ nanoparticles may be internalized by some skin cells; they may dysregulate the complex mechanism of epidermal differentiation and ⁄ or they may exert toxic effects.

The authors recommend the conduct of clinically oriented trials whether there is indeed a risk from micronized TiO₂-containing products on skin with an impaired stratum corneum barrier function.

Follow these links to find out more about the NANODERM project, to download the NANODERM Final Report, or to access the research paper in Experimental Dermatology (abstract only).