Oxybenzone

Oxybenzone is a chemical sunscreen filter, and the case against it is not a single issue but several that point the same way. It absorbs through skin more than any other approved filter: in a randomized FDA trial, a single beach-day application pushed blood levels well past the agency's safety-review threshold within a day, and biomonitoring finds it in roughly 97% of the US population. In cell and animal studies it acts on estrogen receptors, which is why Europe's safety committee has moved to cut the allowed amount in leave-on products. The FDA has not called it unsafe, but it has said the opposite of reassuring: there is not enough data to confirm it is safe at these exposure levels. It is also toxic to coral at low concentrations, which is why Hawaii and Key West banned it. What keeps this at better-to-avoid rather than a settled verdict is that no clear human harm has been shown at real-world use, and skin doctors rightly stress that sun protection matters more than the filter debate. The resolution is simple: mineral sunscreens using zinc oxide or titanium dioxide protect just as well and carry none of these open questions, so there is little reason to accept them.