PROJECT SUMMARYHypochlorous acid (HOCl) is the active oxidizing principle released by standard swimming pool disinfectantsused on a global scale but the health consequences of human exposure inflicted by HOCl remain largelyunknown posing a major public health concern relevant to populations around the world. Environmentalexposure to solar ultraviolet (UV) radiation is a causative factor in skin photocarcinogenesis and immunesuppression is a key mechanism underlying detrimental effects of acute and chronic UV exposure. Based on ourprototype experiments the proposed research will explore the molecular potentiation of UV-induced cutaneousand systemic damage by co-exposure to HOCl-based swimming pool disinfectants examined in cell culture skintissue models and mouse models of UV-induced skin damage and cancer. First we will define the specificmolecular mechanisms underlying HOCl-potentiation of solar UV-induced oxidative insult and genotoxic stressexamined in cultured skin cells and human epidermal tissue reconstructs (aim #1). Next we will explore thepotentiating role of HOCl co-exposure in established murine models of UV-induced acute photodamage(sunburn) systemic photoimmunosuppression and photocarcinogenesis (aim #2). The