Issues relating to the use of Micro and Nanoparticle Zinc Oxide in Personal Care Products based on Skin Penetration Studies

摘要

Many aspects of current data on bulk materials is inadequate (and possibly irrelevant) for extrapolation to their nanoparticulate counterparts especially in relation to the stated applications. Receiving particular attention is the use of nanoparticles such as titania and zinc oxide in personal care products. The current study assessed and compared the in vivo penetration behaviour of nano and micro sized ZnO particulates into human stratum corneum (SC) after topical sunscreen application using a method of sequential removal of layers of stratum corneum by adhesive tapes known as tape stripping. The study revealed that a large proportion of the ZnO applied remained on the surface or at least in the uppermost layers of the SC and the mean percentage of recovery of ZnO after 18 tape strips varied between ～ 70 and 100%. Although the study suggested that there was little apparent difference in the penetration behaviour of either particle size into the stratum corneum, it raised several potentially significant issues relating to the efficacy of using nanosized additives in personal care applications.