and the findings reported here further reinforce this. Because of the limited availability of human SCE membranes, pig SCE membranes may be considered a suitable alternative for photostability testing. However, since the results obtained from sunscreens spread onto skin membranes, akin to the more realistic conditions of use in vivo, do not substantially differ from those obtained on glass plates, these latter may be used for rapid, inexpensive, efficacy screening of photostability of sunscreen products. We believe that photostability testing should be a mandatory requirement for safer sunscreen protection products, since our results, in agreement with those of others, clearly show that some are still far from perfect.