Determination of Sun Protection Factor (SPF) of various commonly used sunblock cosmetics

Abstract

Solar radiations especially UV-A and UV-B are responsible for developing skin cancer and sun burn respectively. To prevent the occurrence of such harmful effects, various sunblock products principally sunscreens are used. Sun Protection Factor (SPF) is a measure of protection from solar radiation that sunblock cosmetics provide and is labeled in the packaging of such product. Present study was performed to verify whether the manufacturers are providing the labeled amount of SPF or not and to compare various sunblock products claiming to provide protection from UV-B radiation using an in vitro method. Absorbance of ultraviolet radiation of these products were measured using an UV-vis spectrophotometer and then SPF was calculated by using the absorbance values. Sunblock cosmetics selected for the study were based on a pilot scale survey involving 130 participants (87 female and 43 male). All the respondents were students of BRAC University and the selection was random. Based on the survey total twenty commonly used sunblock cosmetics were purchased from various locations to determine the SPF values. Out of the 20 products, 1 gave SPF value higher than the claimed amount, 7 were close, 5 were lower and 7 had zero SPF value. Then the found values were used to verify and compare the effectiveness of the products based on purchasing place. The study concluded that the found SPF of sunblock products purchased from pharmacy and abroad were very close to the labeled amount and the SPF of products purchased from other locations including shopping mall, chain shop were either zero or very lower than the labeled amount.