Some chemical-based sunscreens can cross the blood-brain barrier and cause endocrine disruption and nervous system dysregulation.

“what are some if any of the concerns that some of the components in chemical-based sunscreens can cross the bloodb brain barrier it's not um unjustified to think that they are organic phenolic compounds they are Hydro phobic they're lipophilic meaning they can cross membranes very easily which is why they run into this endocrine disruption and some nervous uh system disregulation whether that's been validated to be problematic in humans has yet to be seen But at least in vitro studies in certain animal models we see this”