Beyond sun protection factor testing

Lesley Rhodes, L. E. Rhodes, T. M. Callaghan

    Research output: Contribution to journalArticlepeer-review


    Ultraviolet radiation in sunlight produces a range of acute and chronic adverse effects on the skin including sunburn, photosensitivity rashes, immunosuppression, photoageing and carcinogenesis. Sunscreens aim to provide protection, but standard testing procedures primarily involve assessment of ability to protect against acute erythema, as evidenced by the sun protection factor (SPF). The SPF may correlate poorly with other aspects of protection, particularly since ultraviolet A is weakly erythemogenic compared with ultraviolet B, yet may make a greater contribution to certain other skin effects of sunlight. Nevertheless, there is an increasing tendency for the sunscreen industry to make claims for their products beyond the SPF data. There is a need to develop systems for clinical testing of sunscreens against other endpoints caused by ultraviolet exposure of skin, including immunosuppression and photosensitivity rashes. In particular, there is a largely unrecognized need for testing of sunscreens against the condition known as polymorphic light eruption, a photosensitivity disorder estimated to affect a staggering 10-20% of the population in the northern hemisphere. Ultimately, protection of the skin by sunscreens can only be as effective as their adequacy of application to the skin surface in the everyday setting permits. Optimal sunscreen formulation, and public and patient education in appropriate application technique, both make vital contributions to efficacy of sunscreen protection. This article focuses on the need for extended clinical testing of sunscreens, with particular reference to the photosensitivity disorders, and for improvements in sunscreen formulation and in the adequacy of sunscreen application to the skin surface.
    Original languageEnglish
    Pages (from-to)207-214
    Number of pages7
    JournalInternational Journal of Cosmetic Science
    Issue number4
    Publication statusPublished - Aug 2004


    • Application technique
    • Polymorphic light eruption
    • Sun protection factor
    • Sunscreens
    • UVA protection


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