Collaborative development of a sun protection factor test method: a proposed European Standard. COLIPA Task Force 'Sun Protection Measurement', Europe.

Synopsis Standardization of the method to determine sun protection factors (SPF) is fundamental to uniform labelling of SPF values on sun products. The COLIPA Task Force 'Sun Protection Measurement'(SPM), including representatives of major European sun-product manufacturers and contract testing laboratories, was established in 1990 to define methods for sun products testing. The process involved in developing the COLlPA SPF Test Method started with a critical appraisal of previously existing methods, and identification of areas for improvement. Experiments were performed by the participating laboratories to establish the new recommended test protocol which was then confirmed in two multicentred ring tests. Improvements to test methodology included the number and selection of volunteers and skin types, the application of the product, the definition of W output from solar simulators, and the method for assessing erythemal response (MED) including an option to use colorimetry to define objectively the 'erythemal threshold' of skin and to predetermine MED prior to exposure. Four cosmetic formulations and neutral density physical filters (SPF from 4 to 20) were tested in two ring tests. Results showed that variations in SPF of the cosmetic products were, on average, directly proportional to SPF value. An excellent correlation was found between visual and colorimetric SPF assessments (r = 0.99). An acceptable range of values for low and high SPF standard products was also established. The COLIPA SPF test method is now fully defined and supported by experimental data. Its use will harmonize SPF testing throughout Europe and help in the quest for global harmonization in testing sun products.