In vivo persistent pigment darkening method: a demonstration of the reproducibility of the UVA protection factors results at several testing laboratories

• Published in: Photodermatology, photoimmunology & photomedicine Vol. 22; no. 3; pp. 124 - 128
• Main Authors: Moyal, Dominique, Wichrowski, Karine, Tricaud, Caroline
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.06.2006; Blackwell
• Subjects: Biological and medical sciences; Dermatology; Diseases of the skin. Cosmetics; Medical sciences; Observer Variation; persistent pigment darkening method; Radiotherapy. Instrumental treatment. Physiotherapy. Reeducation. Rehabilitation, orthophony, crenotherapy. Diet therapy and various other treatments (general aspects); reproducibility; Reproducibility of Results; Research Design; Skin - drug effects; Skin - radiation effects; Skin Pigmentation - drug effects; Skin Pigmentation - radiation effects; Sunscreening Agents; Ultraviolet Rays; In vivo; UVA radiation; Sun protection factor; Dermatology; Reproducibility; Pigments; persistent pigment darkening method; Sunscreen product; Laboratory; Method; Medical screening; Protection factor
• ISSN: 0905-4383; 1600-0781
• DOI: 10.1111/j.1600-0781.2006.00223.x

Background/Purpose: The aims of the present studies were to check that persistent pigment darkening (PPD) method can produce accurate and reproducible results for high UVA protection factors (UVAPF) and to provide data on the variability between laboratories and on the influence of skin types. Methods: The Japanese Cosmetic Industry Association (JCIA) PPD method was used to determine the UVAPF in different laboratories of different sunscreen formulations with increasing UVAPF. Two formulations were tested at seven independent laboratories and five products within two laboratories. The influence of skin types on the UVAPF of two products was tested within one laboratory on two panels of volunteers. All laboratories complied with the JCIA method specifications. Results: Reproducible results have been obtained between the different labs and a low and satisfactory variability was achieved with a panel size of 10 subjects. Furthermore, skin type was demonstrated to have no influence within the defined selection criteria. Conclusions: From this multiple center testing, the PPD method has been shown to be appropriate for testing sunscreen formulations with UVAPFs above 20. It is reasonable to expect that test results will be consistent if an identical protocol is used between laboratories.