Sunscreen effects on UV-induced immune suppression.

In order to protect the public against the adverse effects of sunlight, the scientific, medical, and particularly the dermatologic community has promoted "safe sun exposure." This strategy includes sun avoidance whenever possible, wearing hats and other protective clothing and/or devices, such as sunglasses, and extensive use of sunscreens. Sunscreen efficacy is determined by measuring the ability of the sunscreen to block ultraviolet (UV)-induced erythema (sun protection factor or SPF), and most sunscreen formulations on the market, if used properly, are very good at preventing erythema and sunburn. How well sunscreens protect against the other adverse effects of sunlight, such as immune suppression, is not as clear. The purpose of this paper is to review and discuss the literature in this area, concentrating on some of the complications of determining how well sunscreens protect against UV-induced immune suppression.