There is no sunscreen proven to reduce the risk of skin cancer, only to reduce sun burn and age-related sun damage. As my skin man tells me, only a hat offers proper protection. If your sunscreen is made in any country with a decent regulatory body it will talk all about stopping sunburn, sun-related skin damage and at best have a wishy-washy statement on the label saying it "may reduce the risk of skin cancer". They aren't allowed to claim anything better than "maybe this works, maybe it doesn't".
The sunscreens you need to be careful of are those claiming to be "Clear Zinc" or "Clear Titanium" which contain micronised or nano-particles of zinc or titanium. It has been suggested by researchers that they can be absorbed into the skin and concentrate there, with unknown long term effects. Now don't rush to throw them away, as this is theory only. There's actually no evidence of this yet, but... it hasn't really been studied enough.
