respectively. Transmission electron microscopy and particle-induced radiographic emission tech- niques localized the TiO2 in skin sections. Greater than 90% of TiO2 was recovered in the first 15 tape strippings. The remaining 10% did not pen- etrate the viable tissue, but was localized in the furrows and in the opened infundibulum. No TiO2 was detected in the follicle, viable epidermis, or dermis. Similar to the conclusions of the above- reviewed studies, the in vivo and in vitro studies
showed an absence of TiO2 penetration into the viable skin layers through either transcorneal or transfollicular pathways.