photodamaged

Photodamaged is an adjective describing damage that results from exposure to light, especially ultraviolet radiation. The term is used across fields to describe the state of living tissues, such as skin or eyes, as well as materials like polymers, coatings, plastics, and photographic media that have undergone light-induced degradation. In medicine and dermatology it often refers to photoaging or photo-induced changes in tissue; in materials science it denotes light-driven deterioration of properties.

Photodamage arises when photons are absorbed by chromophores, triggering chemical reactions. In biological systems, UV and visible light can generate reactive oxygen species that damage DNA, lipids, and proteins, contributing to aging, cataracts, and cancer risk. In polymers and coatings, photochemical reactions cause chain scission and crosslinking, oxidation, discoloration, embrittlement, and loss of gloss or mechanical strength. The extent of damage depends on wavelength, exposure duration, presence of photosensitizers, and protective factors such as oxygen availability and temperature.

Signs of photodamage vary by context. In skin, visible wrinkles, dyspigmentation, reduced elasticity, and increased cancer risk may appear after prolonged sun exposure. In materials, faded coloration, chalking, cracking, surface roughening, and decreased tensile strength are common. Photodamage can be progressive with continued exposure, though some materials exhibit partial reversibility if stabilization measures are applied early.

Prevention and mitigation involve limiting light exposure and enhancing resistance to light. For living tissue, sunscreens with UV filters, protective clothing, and timing outdoor activity reduce risk. In materials, UV absorbers, hindered amine light stabilizers, antioxidants, and protective coatings slow degradation. Regular monitoring helps determine when replacement or refurbishment is needed to maintain performance or health outcomes.