Maybe I'm missing something, but it seems like this study only examined mixtures of organic UV absorbers +/- Zn/Ti and did not examine the inorganic UV absorber

Maybe I'm missing something, but it seems like this study only examined mixtures of organic UV absorbers +/- Zn/Ti and did not examine the inorganic UV absorbers alone. But my understanding was that most sunscreens are exclusively organic or inorganic, so such mixtures don't happen unless one mixes different sunscreens. Does this study actually have much real world relevance? Also I would hope that nobody makes combined sunscreens - metal catalyzed photodegradation is well known and anyway cosmetic/drug products should be getting photostability studies as part of routine development. Naively one would think organic UV absorbers would be especially liable to interactions because they're all huge conjugated systems hanging around in excited states, but maybe fragrances / unsaturated fatty acids do it too. In any case studying mineral-only formulations would have been nice to see.