The main concern with nanoparticles is that they are so tiny that they are absorbed into the skin more than we want them (ideally sunscreen should remain on the surface of the skin). The itsy-bitsy Nano-sized particles improve both spreadability and reduce the whitish tint a lot, but unfortunately, it also introduces new health concerns. The cosmetic industry is, of course, really trying to solve this problem and the best solution so far is using nanoparticles. Sunscreens containing Titanium Dioxide are often hard to spread on the skin and they leave a disturbing whitish tint.
The disadvantage of Titanium Dioxide is that it's not cosmetically elegant, meaning it's a white, 'unspreadable' mess. Regular sized Titanium Dioxide also has a great safety profile, it's non-irritating and is pretty much free from any health concerns (like estrogenic effect worries with some chemical filters).
Its protection is very good between 290 - 350 nm (UVB and UVA II range), and less good at 350-400 nm (UVA I) range. Iron Oxides (Ci 77491, Ci 77492, Ci 77499)Īnyway, it doesn't matter if it reflects or absorbs, Titanium Dioxide is a pretty awesome sunscreen agent for two main reasons: it gives a nice broad spectrum coverage and it's highly stable. Pentaerythrityl Tetra-Di-T-Butyl Hydroxyhydrocinnamate
