Skin care professionals use many tools to analyze clients’ skin. The most common is the Fitzpatrick scale. Developed in 1975 by Harvard dermatologist Thomas Fitzpatrick, MD, the Fitzpatrick scale was created to classify a client’s reaction to the sun based on skin color, featuring a range of types from I–VI, with I being the lightest and VI being the darkest. (See Fitzpatrick Scale and Correlating Sensitivity.) The original Fitzpatrick scale stated that Fitzpatrick type VI never burned; however, it is now known that this is not the case and, regardless of color, everyone will burn at some point. Another tool is the Global Heritage Model, which differs from the Fitzpatrick scale in that it classifies how clients’ skin will respond to topical activity and UV exposure based on their hereditary background, and not simply the color of their skin.
Because numerous people are of mixed hereditary backgrounds and many color their hair, wear colored contacts and may tan, either via topical products or UV exposure, it is increasingly difficult to determine a client’s heritage based solely on appearance. This is where the Global Heritage Model comes in. (See Global Heritage Model.) This tool helps determine the skin’s response to topical stimuli based upon inherited melanocyte activity. Once you are able to determine how each client’s melanocytes are likely to react, you will be better able to choose the best treatments and ingredients to suit each and every client.
Skin is designed to protect from a variety of daily environmental insults. One is DNA damage within the nuclei of the keratinocytes due to UV exposure—the end result of which is likely skin cancer. With that in mind, if you look at the environment of the polar regions of the world, it is cold and dry with very little UV exposure. Because of this, clients whose ancestors come from these regions tend to have lighter skin, hair and eyes. This has to do with both the density of the melanin produced by the melanocytes, as well as how quickly those melanocytes respond to external stimuli. Because UV exposure is less intense in these regions, the inherited melanocyte response is often slow for these individuals, meaning they are less prone to produce pigment within the skin. It is because of their less-responsive melanocytes that clients of polar-region ancestry are able to tolerate more active topical treatments—they are less likely to produce pigment due to surface stimulation. As a result, they are not as likely to develop post-inflammatory hyperpigmentation (PIH) from treatments, but are more prone to developing skin cancer.