Ultraviolet A Radiation: Testing and Labeling for Sunscreen Products

Update on photoprotection

“…The challenge to finding a consensus on UVA testing is that no single modality is ideal. The preferred method would be clinically relevant, noninvasive, and reproducible in different laboratory and geographic settings (34). However, in reality, no single method of testing UVA protection satisfies all of these criteria.…”

“…The PPD method, currently used in Austria and Japan, evaluates sunscreen effectiveness against UVA by measuring melanin photo-oxidation postexposure (34). Unlike IPD, PPD is measured between 2 and 24 hours following irradiation and has the added benefit of simultaneously evaluating sunscreen photostability.…”

Sunscreen tests: Correspondence between in vitro data and values reported by the manufacturers

“…The in vivo method is expensive and time consuming, factors that make it difficult to adopt in routine quality control. Moreover, in vivo tests to assess UVA protection, such as PPD or IPD [2], often result in not reproducible and controversial results. As a consequence, a lot of efforts have been devoted to the development of in vitro techniques for assessing the photo-protection ability of sunscreen products.…”

Update on photoprotection

“…[50] PPD is measured between 2 and 24 hours following irradiation and has the added benefit of simultaneously evaluating sunscreen photostability. However, PPD requires subjects be exposed to high-intensity lamps for long periods of time (up to 1 hour).…”