The objective of this study is quantification of singlet oxygen species in the skin after exposure to Ultraviolet A (UVA) light
Ultraviolet (UV) radiation can lead to skin damage and cancer. Ultraviolet A (UVA) irradiation is 10 to 100 times more abundant in natural sunlight than ultraviolet B (UVB), thus human skin is exposed to more UVA irradiation daily.UVA irradiation is not completely filtered by clothing and it penetrates deeper into the dermis than UVB, potentially causing more damage. It is believed that skin cancer, photo aging, and skin immunomodulation are mediated by the reactive oxygen species (ROS) that are generated in response to UV radiation. Singlet oxygen (1O2) is one type of ROS. The aim of this study is to quantify the level of singlet oxygen generated in the skin after exposure to UVA radiation. Previous studies have used low dose ultraviolet A1(UVA1) irradiation of 20 J/cm2, which mimics exposure to strong sunlight of approximately two hours. This study will use UVA doses equivalent to or less than what humans are exposed to in daily life. Additionally, the aim is to quantify singlet oxygen produced in individuals of various skin types before and after application of sunscreens containing zinc oxide and avobenzone (sun protection factor 30). To our knowledge, there is no method for quantifying singlet oxygen in human skin after exposure to UVA light. This is a novel method that may help the investigators understand further the protective effects of various skin types, as well as sunscreens.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
PREVENTION
Masking
NONE
Enrollment
17
Zinc Oxide is applied to one area of the forearm, Avobenzone is applied to another area of the forearm.
University of California, Davis
Sacramento, California, United States
Amount of singlet oxygen generated by the left forearm skin (2 cm^2) after exposure to UVA radiation dose of 0.33 J/cm2
Time frame: 5 minutes at first visit
Amount of singlet oxygen generated by the left forearm skin (2 cm^2) after exposure to UVA radiation dose of 8.25 J/cm2
Time frame: 5 minutes at first visit
Amount of singlet oxygen generated by the left forearm skin (2 cm^2) after exposure to UVA radiation dose of 16.5 J/cm2
Time frame: 5 minutes at first visit
Difference in singlet oxygen (as measured by singlet oxygen molecule numbers) generated between individuals of different skin Fitzpatrick skin types
Time frame: Within 24 hours
Difference in singlet oxygen (as measured by thymidine dimer %) generated between individuals of different skin Fitzpatrick skin types
Time frame: Within 24 hours
Difference in singlet oxygen generation with avobenzone and zinc oxide sunscreens (sun protection factor 30 and 2mg/cm^2 applied for each) vs control (no sunscreen) after exposure to 444.1millijoules (mJ) /cm2 UVA exposure
Difference in singlet oxygen generation (as measured by thymidine dimer %) with two different sunscreens (zinc oxide and avobenzone, each sun protection factor 30 and 2mg/cm\^2 applied) vs control (no sunscreen) after exposure to 444.1mJ/cm2 UVA exposure
Time frame: Within 24 hours
Difference in singlet oxygen generation with avobenzone and zinc oxide sunscreens (sun protection factor 30 and 2mg/cm^2 applied for each) vs control (no sunscreen) after exposure to 444.1millijoules (mJ) /cm2 UVA exposure
Difference in singlet oxygen generation (as measured by singlet oxygen molecule numbers) with two different sunscreens (zinc oxide and avobenzone, each sun protection factor 30 and 2mg/cm\^2 applied) vs control (no sunscreen) after exposure to 444.1mJ/cm2 UVA exposure
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Time frame: Within 24 hours
Change in appearance of skin pigmentation as measured by colorimetry after UVA exposure
Time frame: Within 24 hours