alpha- and beta-Hydroxy acids have been used extensively in cosmetic and dermatological formulations. At present, there is an inadequate amount of information with which to assess the safety of topical applications of alpha- and beta-hydroxy acids in conjunction with exposure to ultraviolet light. In the present study, we examined changes in the epidermal basal cell proliferation and the edemal response using skin thickness measurements elicited in SKH-1 mice following exposure to simulated solar light (SSL) with or without topical treatment with creams containing alpha- (glycolic) and beta-hydroxy (salicylic) acids. The dose of SSL light required to induce measurable edema (MED(BIOL)) in nai;ve, free-moving SKH-1 mice was determined to be 90 mJ. CIE/cm(2). Pretreating the mice with daily (5 days/week) exposures of 14 mJ. CIE/cm(2) for 6 weeks resulted in a doubling of the MED(BIOL) to 180 mJ. CIE/cm(2). Topical application of control cream (pH 3.5), or creams containing glycolic acid (10%, pH 3.5) or salicylic acid (4%, pH 3.5) for 6 weeks (5 days/week) increased the MED(BIOL) to 137 mJ. CIE/cm(2). Daily treatments with SSL (14 mJ. CIE/cm(2)) and control cream (pH 3.5), glycolic (10%, pH 3.5) or salicylic (4%, pH 3.5) acid-containing creams for 6 weeks (5 days/week) resulted in an MED(BIOL) value of 180 mJ. CIE/cm(2), which was the same as treatment with light alone for 6 weeks. These data indicate that a 6-week treatment of mouse skin with a representative skin cream, with or without representative alpha- and beta-hydroxy acids (glycolic and salicylic acid, respectively), changes the UV light sensitivity; however, treatment with the cream, with or without the acids, does not contribute to the UV sensitivity of mice cotreated with low doses of UV light.