http://articles.mercola.com/sites/articles/archive/2001/06/06/sunscreen-part-two.aspxSome sunscreens are not stable when irradiated with simulated sunlight. The photostability differs is very different for different products. Two chemical sun filters have been tested for their dark toxicity and possible toxicity to mouse cells in a cellenCommunityServer 2008.5 SP1 (Build: 31106.3070)