防晒类化妆品的日光防晒系数和长波紫外线防护指数与使用浓度及时间的相关性研究

The sun protection factor and protection factor of ultraviolet A of the sunscreen and relationship between doses and duration of the use

目的：研究防晒化妆品日光防晒系数（ SPF）和长波紫外线防护指数（ PFA）与使用浓度及时间的关系，并探讨正确使用防晒类化妆品的方法。方法将几种的防晒化妆品分别按不同的浓度涂抹于受试者皮肤表面，隔15分钟后给予以出现最小红斑量（ MED）为度的中波紫外线和最小持续黑化量（ MPPD）为度的长波紫外线照射，进而分别算出SPF值和PFA值。将几种的防晒化妆品分别按标识浓度涂抹于受试者皮肤表面，间隔不同时间后给予以出现MED为度的中波紫外线和最小持续黑化量为度的长波紫外线照射，分别算出不同时间所对应的SPF值和PFA值。结果防晒化妆品的使用浓度和SPF以及PFA都具有相关性。防晒化妆品的SPF值在使用时间70～100分钟下降最为明显。 PFA值在时间为80～110分钟下降最为明显。结论使用防晒化妆品的标识浓度才可起到合适的防晒效果。在日常使用防晒化妆品时应每80分钟左右涂抹一次，以保证防晒化妆品的防晒效果。

Objective To investigate the sun protection factor （ SPF） values and protection factor of ultraviolet A （ PFA） val-ues of the sun screen and the relationship between doses and duration of use in order to explore the proper use approach of sunscreen cosmetics.Methods Different concentrations of several brands of sunscreen were applied to the skin surface of the subjects.After 15 minutes,minimal erythema dose （ MED） and minimal persistent pigment darkening （ MPPD） were used to calculate the SPF and PFA, respectively.At the same time,the sunscreens were applied to the skin for different durations and MED and MPPD were used to calcu-late the SPF and PFA of different times.Results Concentration and sunscreen cosmetics SPF and PFA were relevant.The SPF and PFA of sunscreen were decreased after 70~100 min of the use and after 80~110 min of the use,respectively.Conclusion The proper use of instructed concentration of sunscreen may have a suitable sunscreen effect.Commercial sunscreens should be used once per 80 minutes in daily life to ensure its effectiveness.