The EDEN-IDEA Congress: 3rd International Meeting on Epidemiology and Prevention of Skin Diseases and the 6th Annual Scientific Meeting of the International DermatoEpidemiology Association

Abstract

Objectives: Both ultraviolet-A (UVA) and ultraviolet-B (UVB) radiation have been implicated in skin photoageing, a multifaceted phenomenon of clinical, cellular, histological, and immunological changes. Much of the in vivo evidence of the relationship between wavelength-dependent ultraviolet radiation exposure and photoageing has been based on animal models. This study considered the relative contributions of UVA and UVB radiation exposure to the hallmark feature of photoageing, degree of dermal elastosis, in an unselected human population. Methods: An age-strati®ed random sample of 338 adults aged over 17 years was chosen from the electoral roll of the community of Nambour, Australia. Subjects were recruited between May 1994 and May 1995, and asked to provide a 2-mm punch biopsy of the skin of the back of the left hand, and to complete a one-page sun exposure questionnaire from which several indices of ultraviolet radiation exposures were de®ned. Haematoxylin±and-eosin stained sections were assessed for degree of dermal elastosis on a scale from 0 (no evidence of elastotic ®bres) to 6 (severe elastosis). Multiple linear regression models considered the association between ultraviolet radiation exposure indices and dermal elastosis grade. Results: Lifetime sun exposure hours and actinic UVA exposure were both associated with degree of dermal elastosis in a log-linear relationship (p<0.001). These associations persisted after strati®cation for skin color. No consistent trends were demonstrated for either, total hours of sun exposure between 10am and 2 pm, or actinic UVB exposure. Conclusions: UVA exposure is more clearly implicated in the accumulation of dermal elastosis than is UVB exposure. Since the majority of ultraviolet radiation is composed of UVA, and given the association between photoageing and skin cancer, this effectively suggests that public health messages should emphasize equal avoidance of all sun exposure.