Confused

Ok, I just read something in a womens magazine (dubious source of information to say the least) that said that chemical sunscreens are inherently unstable. Thus, one should reapply them at least every two hours. The sunscreen you put on under your makeup before work won't even last until lunch, according to the article. However, the sun-BLOCKS, which use physical blocks, either zinc oxide or titanium dioxide, will last until they wash or sweat off.

So how is it that the chemical sunscreens cause problems on the reefs, and don't wash off? I suppose the key issue is that they are not biodegradable, and thus, even when they wash off bodies, their chemical structure is still intact, so that wherever they land--nestled down in the micoscopic filaments of coral polyps, for example-- they continue to block sun, therefore starting the whole algae/virus thing.

So, once again, wear a rashguard in the ocean, and look for a biodegradable sunscreen with physical blocks, not chemical blocks. For every day, you can skip the rashguard (they are not shirts and should not be worn as shirts, ok?) but be sure to use a sunblock that has either zinc or titanium to protect your face, neck, chest (this was where my skin cancer ended up), hands, and anything else that you regularly expose to the sun. Reapply if you sweat a lot or it gets washed off. And floss every day. And eat your vegetables. And exercise and drink plenty of water. That should about cover it.