Comparative Study on Function and Stability of Sunscreening Products

Kang, Nam Gyu; Kim, Tae Heung

Abstract

BACKGROUND
A lot of protective tools such as sunshades (sun-cap), sun-shielding tints and various sunscreens are widely used to protect solar ultraviolet (UV) radiation. Although dermatologists are aware of these products, they do not know the exact protective efficacy or their stability after strong UV irradiation. OBJECTIVE: We tried to measure the spectal absorbance and transmittance of various sunscreening products. In addition, we measured change of sunscreens's absorbance or transmittance after strong UV irradiation for 30, 60 and 90 minutes. METHODS: We purchased five commercially available sunshades (product A-E), five sun-tinting films (product A-E), and eight sunsceens (product A-H) with similar sun-protection factor (SPF) around 30, and measured spectral absorbance and transmittance of those agents. For the sunscreens, they were irradiated with 250 watt Xenon-Arc lamp and change of spectral responses were evaluated. RESULTS: In absorption and transmission spectra of five different sun-caps, sun-cap C showed very good protection in entire UV range whereas all others protected UV only partially. Absorption and transmission spectra of six different sun-shielding tints showed all of them protected UV fairly well and tint C showed the best protection. Eight different sunscreens showed profound differences in spectal absorbances or transmittances. Sunscreen-A showed the best protection and there was no relationship between price and spectral-protection of sunscreens. In the photo-stability of eight sunscreens after UV-irradiation, there were big differences. Only sunscreen-A showed the least change after UV irradiation, and all other sunscreens showed a change of specta by increased UV-irradiation time. CONCLUSION: Protection efficacies of sunscreening products were variable, and most sunscreens were unstable to strong UV irradiation. Further studies would be necessary to give proper information for protecting UV effectively to dermatologists and consumers.