Visualization of sun protect factor (SPF): a new method to assess the performance of sunscreen using photochromic film

Sunscreen efficacy assessment is crucial for ensuring effective protection against harmful ultraviolet (UV) radiation. In this study, we employed a novel approach using photochromic ionizing radiation dosimetry films to evaluate sunscreen performance. The action spectrum analysis of the photochromic film revealed heightened sensitivity to UVB radiation, diminishing with increasing wavelength. Using VITRO-SKIN^® as a substrate, we tested sunscreen samples and quantified color changes in the photochromic film after exposure to UVA + UVB and UVA radiations. The results demonstrated the film's ability to discern varying levels of UV protection in sunscreen formulations, with a notable correlation between colorimetric measurements (ΔE and ΔL^*) and in-vitro SPF/UVA-PF values. Our findings suggest the potential of photochromic dosimetry films as a valuable tool for screening sunscreen efficacy, particularly in UVB protection evaluation and its correlation with UVA-PF. This research can help consumers visualize protection, application quantity, and evenness. Further research is warranted to refine assessment metrics for comprehensive sunscreen evaluation, especially regarding UVA radiation protection.