Sunscreen recommendation?

Zinc oxide content and sunscreen?

• The questino is about sunscreen and the chemical ingredients in it. A lot of times I am always confused when I see active ingredients and SPF(sun protection factor) relation on sunscreens. For example, I'lls ee a sunscreen(let's call this sunscree, sunscreen "A") that states that it only has SPF25 but has 25% zinc oxide content, which seems like a lot. Then I'll see another sunscreen, let's call this "sunscreen B" that states it has SPF50 but only has 21% zinc oxide and 4% titanium dioxide. While sunscreen B has more titanium dioxide content than sunscreen A, it also has less zinc oxide content, yet its SPF strength is advertised SPF50? Or here is another one, A SPF15 sunscreen advertises itself as having 5% zinc oxide content as its active ingredient, while another SPF15 sunscreen advertises itself as having 15% zinc oxide content! If the former sunscreen is SPF15 with only 5% zinc oxide content, shouldn't the other sunscreen be much more than SPF15, seeing as though it has over 3x the amount of zinc oxide content? How do you know which sunscreens are the toughest? Aren't the highest percentages an indicator of the strongest sunscreens, since essentially, the higher the active ingredient(zinc oxide or titanium dioxide), the more "concentrated" it is?

• Answer:

  I think as a general rule you are correct, but I don't think it is an exact science from what I have read. I think that the brands that say their products have a lower SPF with the same content are being conservative and trying to make sure that people do not put too much dependence on the effectiveness of sunscreen to protect them from sunburn, and possibly from cancer. It could have something to do with fear of being sued. http://dermatology.about.com/cs/skincareproducts/a/spf.htm