Which of the following is NOT listed as a factor affecting skin absorption?

• A. Condition of Stratum Corneum
• B. Hydration Level
• C. Occlusion
• D. Exposure to ultraviolet light

Answer: (D)

Skin absorption hinges on the outer skin barrier, especially the condition of the stratum corneum. A healthy, intact barrier slows penetration, while a damaged or compromised barrier increases absorption. Hydration level matters because water in the stratum corneum swells the cells and loosens lipid packing, making it easier for substances to pass through. Occlusion boosts absorption by trapping moisture, further hydrating the skin and enhancing permeability. Exposure to ultraviolet light, while it can affect skin health over time, is not typically cited as a direct factor that controls the rate or extent of topical absorption. Therefore, UV exposure is not listed as a factor affecting skin absorption.