Intrinsic and Extrinsic Factors Affecting Skin Surface pH.

The body skin pH can usually vary from 4.0 to 7.0 depending on location. The presence of natural acidic compounds on the skin surface helps maintain the skin's physicochemical properties as well as its protective functions. Since the slightly acidic pH of the skin is extremely important for the skin's protective function, the skin is widely known as "acid mantel." Factors such as age, race, gender, body sites, biochemical differences, and even washing affect the pH of the stratum corneum. Recent clinical studies using an emollient-base finish product using the traditional way of measuring skin pH produced results that indicated an apparent increase in skin pH. The apparent pH increase with these products is most probably an artifact of the skin pH measurement technique. Our findings show that certain petrolatum-based emollients and components could create a protective barrier and help maintain the healthy acidity of the skin. Our work provides new evidence of emollients helping to stabilize skin pH in its natural balanced state rather than affecting it. This new learning should be taken into consideration by other researchers in the area of skin pH as well as in clinical studies to avoid misleading results.