Abstract:

Objective To determine whether daily sun exposure impacts epidermal permeability barrier function, stratum corneum integrity and stratum corneum hydration. Materials and Methods Total 325 volunteers aged 15-59 years (160 males and 165 females; mean age 28.6 + 0.62) were enrolled in this study. According to their daily direct sun exposure time in last five days, subjects were divided into a).control group whose daily direct sun exposure time was less than 1 hour and without direct sun exposure between 11:00am to 1:00pm; b). lower dosage sun exposed group whose daily direct sun exposure time was 1-2 hours and without direct sun exposure between 11:00am to 1:00pm; c). medium dosage sun exposed group whose daily direct sun exposure time was more than 2 hours, but less than 4 hours with direct sun exposure between 11:00am to 1:00pm; and d). higher dosage sun exposed group whose daily direct sun exposure time was 4-6 hours and with direct sun exposure between 11:00am to 1:00pm. Transepidermal water loss and stratum corneum capacitance were measured with a TM300 and CM825 probes, respectively, connected to MPA5 skin physiology monitor. Results In comparison with control group, lower dosage sun exposure decreases stratum corneum integrity. Moreover, stratum corneum integrity in lower dosage sun exposed group is inferior to those in medium and higher dosage sun exposed groups. However, barrier recovery rate is significantly delayed in both medium and higher dosage sun exposed groups. Additionally, there is no change in stratum corneum hydration in comparison with control. Conclusions daily sun exposure impacts epidermal permeability barrier function and stratum corneum integrity.

Key words: UV, Stratum Corneum, Permeability Barrier Function, Integrity, stratum corneum hydration