Some of the solar creams contain titanium oxide nanoparticles due to their ultraviolet light absorption capacity. In fact, titanium oxide particles do not pose a health hazard, but nanoparticles can. In fact, in mouse cell cultures they have seen that they promote adverse reactions in brain cells. Of course, this does not mean that it has the same effect on humans, much less that nanoparticles rubbed on the skin reach the brain and damage it. But at least it questions the safety of these nanoparticles.