ABSTRACT
The skin is exposed to environmental and applied nanoparticles. This continual exposure to natural and man-made nanomaterials is usually harmless because the skin is an excellent barrier to these materials. The skin is remarkably good at protecting against the penetration of virtually all nanomaterials that we come in contact with. This is primarily because of the physical properties of the skin as a strati-ed epithelium. The skin is composed of an outer layer of stratum corneum, viable epithelium, and dermis (Figure 12.1a). These layers can expand (Figure 12.1b) or contract dramatically due to pathological processes.
