Mechanisms of Phototoxic and Photoallergic Reactions

Abstract

Solar radiation represents the most important environmental stress human beings are exposed to. Within the spectrum of solar radiation that is reaching the Earth's surface, the ultraviolet and visible portion of the electromagnetic radiation are of particular importance to human cutaneous biology because this is the radiation that enters the skin and blood, much of this radiation being absorbed by molecules within the skin, and photon energy being sufficient to cause electronic excitation that may lead to unimolecular and bimolecular chemical reactions. The ultraviolet (UV) portion of the electromagnetic spectrum is divided into three regions: UVC, 200--290 nm, UVB, 290--320 nm, and UVA, 320--400 nm.