SURBER CHRISTIAN¹*, OSTERWALDER ULI²
*Corresponding author
1. Prof. Dr. phil. nat., Department of Dermatology, University Clinics, Basel and Zurich
2. Sun Protection Facilitator GmbH, Basel, Switzerland

Abstract

Sun protection products with nano-particulate UV-filters (NP-UVF) repeatedly lead to controversial contributions in the scientific literature as well as in the media. In this article here, the authors present a view of NP-UVF that has hardly ever been presented in its kind.  It is well known from drug development that one can reduce (bio-)availability by creating molecular glomerates.  The same concept can be applied to UV-filters to reduce their (bio-) availability and thus increase their safety.  In relation to dimension, one may certainly conclude that NP-UVFs are bigger than all non-nanoparticulate (soluble) UVFs making their penetration into or permeation through skin much less likely.

BACKGROUND

Preparations containing pigments have been used since ancient times to protect against negative effects of solar radiation.  In the 1950s, first sunscreens containing particulate ZnO and TiO₂ appeared.  Particle sizes in these products were such that light was scattered and reflected rendering preparations highly visible on skin.  They were soon considered cosmetically unattractive.  By reducing size of the particles to the range of less than 100 nm, sunscreen products appear transparent on skin because the particles no longer primarily reflect radiation but absorb it, predominantly over a large range of the UVB-UVA spectrum (Figure 1).  After 1990, ZnO and TiO₂ and after 2010 Tris-Biphenyl Triazine (TBPT) and Methylene Bis-Benzotriazolyl Tetramethylbutylphenol (MBBT) were marketed as inorganic and organic nanoparticulate UV-filters (NP-UVF), respectively.

Well-known science fiction ...