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Gradation of Skin Color: Biological Considerations During Treatment

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Laser hair removal procedures in 2010 totaled to 936, 121, which reflected a -26.9% decrease from 2009 – most likely as a result of a flexing economy.1 It is a procedure, however, that continues to be popular.
Lasers (including the CO2 laser) were introduced in dermatology and surgery as early as the 1960s.2 The CO2 laser became more popular during the 1990s for skin resurfacing to improve wrinkles, dischromias, scars, atrophic scars, pitted acne scars and others.3 These pioneering procedures also meant longer recovery periods.

Newer generations of thermal lasers, including fractional lasers and controlled non-ablative pulsed lasers helped influence a new field of aesthetic medicine during the past 15 years. Many laser services are now considered lunchtime procedures unlike the earlier CO2 skin resurfacing procedure that required several days to weeks for recovery. Modern services include hair reduction, skin rejuvenation, pigmentation, vascular lesions (port wine stains, telangiectasia, superficial veins) and tattoo removal. Manufacturers for contemporary thermal devices for cosmetic treatments (laser, intense pulse light (IPL), and radio frequency) have perfected their machines through incorporating more contemporary smart features that support ease of calibration and use, safety and more controlled outcome of a procedure. Moreover, the passing of time during the past 20 years has allowed for additional research including a greater understanding of thermal effects on tissue, refinement of techniques, writing of peer-reviewed studies, and witnessing the transition into a medical spa environment.

A growing concern involves the inconsistency of statewide variants as to who is allowed to operate a non-ablative laser, i.e., hair removal lasers in particular. Additionally, one must be mindful that lasers/IPL devices can be dangerous in the hands of an unskilled operator.
Reviewing the evolution of laser technology (including radio frequency and any device that perpetrates a thermal response in tissue) and its place in aesthetic medicine brings with it many challenges when it comes to consistent and adequate education in the use of non-ablative technology. Both medical and aesthetic personnel, each of whom will vary in education level, should be trained and certified in safe operation of these machines. Additionally, they must also work within the scope of their licensing. A few hours of manufacturer training in an office is not always adequate. Furthermore, learning laser theory without sufficient hours of hands-on practicum under the guidance of an experienced tutor again is not recommended. It takes practice to perfect the understanding of laser operation, tissue response and how to remedy any unexpected result. Moreover, this knowledge and precaution should not be limited to procedures that solely create heat shock to the skin (laser/IPL/radio frequency). Rather it should pertain to all other treatment procedures (chemical peels, microdermabrasion, ultrasound, dermal needling) that may pose a risk for tissue injury (controlled or unexpected) including interference with the normal biological functioning of the skin – acid mantle, immune cells, keratinocytes, melanocytes, nerve cells, fibroblasts, Natural Moisturizing Factors(NMF), enzyme processes and more.
An in-depth understanding in the dermal sciences should be mandated for all aesthetic professionals. Study should include skin histology, cells and systems, skin disorders and diseases, melanogenesis (pigment), angiogenesis (vascular and circulatory system), the immune response during a procedure, successful wound healing during the use of a device that creates a thermal response in the skin, or even a chemical or mechanical wound. Included in this list is the importance of understanding the procedural effects of thermal technology on all skin colors and cultural variation. Most important is to develop one's ability to fully grasp the degree of possible risks for global skin types that are becoming more prevalent within our North American society. Cultural (race) diversity includes Caucasian, non-Caucasian and mixed population groups found in many parts of the world and here. The outcome and rate of healing may vary within each category. Furthermore, product choices should be carefully studied so that we apply ingredients that are non-toxic and bio-identical to skin components.

Prior to performing any procedure, a detailed systematic pathway of skin analysis is required that encompasses the client's health history, life style profile, visual and verbal interview, and client expectations. The accuracy of this assessment is also dependent upon the education level of the practitioner who should be savvy enough to recognize indicators for potential tissue reaction and risk, healing potential and final outcome and success of a procedure. Without mastery of these underlying concepts, mistakes can be made with potential irreversible consequences.
The next section of this article will discuss an important aspect of skin histology beginning with a review of human origins and the melanogenesis story. We will travel back in time because it reveals valuable insight in supporting our decisions when performing laser/IPL treatments. Moreover, this information is relevant for ALL aesthetic services including chemical peels, enzymes, microdermabrasion and other skin-rejuvenating services.

When we first meet another person, we immediately notice the color of their skin, their hair, and other anatomical features that subtly provides indicators to their racial and geographical origin. Physical appearance (anatomical features) also influences the propensity for sexual attraction resulting in proliferation of a species. What differentiates the gradation or degree of color in human beings is based on several observations. Regardless of skin color, the purpose, function and biological requirements of cells remain consistent in all individuals no matter what their geographical location.4 What encourages body health and human survival are balanced nutrients, light and darkness, optimum immune response, healthy cell membranes and skin barrier, the ability to adapt into an environment, and healthy social structures. Cells have receptors and sensors that are responsive to external and internal stimuli that collectively become part of a greater communication network within the body. Synchronicity of ALL systems is based on genetic adaptation that leads to optimum human health and survival.5 There may be, however, some differences between race groups based on origins and genetic adaptive characteristics. This is a key observation.
The closer one originates from locations in proximity to the equator, the darker the skin with the biochemistry, including skin color, adapting accordingly. Populations originating in colder latitudes north and south of the equator are lighter in skin color.5 Anthropology studies substantiate that through a process called Natural Selection and Biodiversity, humans have a remarkable innate ability to adapt to their natural surroundings. This may be at sea level, to mountain regions, rain forest and hot desert. Body structures, height, and the amount of body fat are all adaptive mechanisms that reveal clues as to one's origin. For example, long, linear bodies tend to be correlated with hot, dry climates. Short, stocky body builds with shorter fingers and toes are found in colder, wet climates.6,7 What about individuals who tend to have larger lungs and chest cavities and whose ancestors originated at higher elevations with lower oxygen supply? At first you may ask why these differences exist. My answer to you is to explore the biological requirements of the cells and systems that promote healthy body functioning based on climatic and environmental adaptivity.
Here is another observation: It took thousands of years for humans to evolve and create features and biological responses that safeguarded survival in their native location. Genetic adaptations occur due to phenomena called environmental stresses(or evolutionary pressure) that include temperature, humidity, various altitudes, bacterial and viral infection, air quality, and dietary imbalance.7 When these conditions become persistent over several generations, survival requires a biological evolution for genetic adaptation.7 A good example is when populations lived during times of disease. They began to acquire genetic traits that helped them build immunity to those microorganisms. Genetic traits, as a result, are passed to subsequent generations. It also provides clues as to why individuals may experience health challenges including various skin conditions. For the price of a plane ticket, modern humans can relocate in a day to another part of the world. It certainly could promote a bit of biological and psychological havoc!
Considering that it took humans 25,000 to 50,000 years of adaptation, what biological and anatomical changes occurred when humans relocated from the core of Africa into northern or southern latitudes? Movement into these colder regions eventually caused darker skin to lighten proportionally to the distance to which they migrated. This resulted in a gradation (or range) of skin colors.9 What is the underlying reason for color adaptation in humans? We will move on to discuss melanin and body health.

MELANOCYTES – A Dendritic UV Filter System
There is a strong correlation between UV radiation and the biological requirements for health, specifically for vitamin D synthesis. Melanocyte function is primarily under genetic and hormonal controls that continuously strive to keep our natural level of skin color in check in order to regulate UV absorption. Both light and dark skin have variable sized melanin particles. The density and size of pigment particles become greater in darker skin types. An exception is with red heads that possess what is known as red gene MC1R factor resulting in fair skin, freckles, and red hair. Unlike their neighbors, the keratinocytes, melanocytes are slow cycling and long lived. After the age of 16 the regeneration cycle of melanocytes become limited. Beginning in our 30s and 40s the density of active melanocytes is reduced by 10 to 20 percent every ten years.10, 11
One in 10 cells in the basal area are melanocytes and serve to protect germinating nuclei of epidermal cells. They manufacture and package pigment granules (melanosomes) that are injected via dendrites into the keratinocytes. They are considered a photoprotective filter that becomes part of the natural skin barrier. These pigment cells reduce and control the penetration of all wavelengths of light to dermal tissues.10 This is a key function of the melanocyte and should not be overlooked. Melanin function includes not only UV filtering but also acts as a free radical scavenger due to its bipolymer complex structures as well as being a cation trap for toxic metals.8 We also have melanin receptors in the cones of our eyes; however, we will focus on the skin in this article.
It is well understood that over-absorption of UV radiation can result in cell destruction and suppression of thermoregulation and other biological processes.9 A controlled amount of UVB must, however, enter the skin cell receptors in order for the body to catalyze vitamin D, a group of fat-soluble secosteroids. Approximately 90 percent is this vitamin is normally synthesized in the basal and spinosum layers of the skin. The other 10 percent can come from our nutrition (fatty fish, egg yolks).

  • Vitamin D3 (cholecalciferol) is required for the intestines to absorb calcium and phosphorus from food for bone growth and repair as well as regulate heart rhythm. Rickets is a prime example due to calcium deficiency.
  • Vitamin D is required for our immune system as well as helps control inflammation and influences gene regulation, differentiation, and apoptosis of cells. 8
  • Vitamin D deficiencies during pregnancy can result in pelvic deformities in women preventing normal delivery of babies.11
  • The activity of melanocytes in controlling and filtering is important to protecting UV photolysis (light-stimulated chemical decomposition) of folic acid (foliate, a B vitamin). Deficiencies in this nutrient can lead to anemia and creates risk for poor fetal development, resulting in miscarriage and poor reproductive success. 8

The control and rate of melanin production is essential for Vitamin D synthesis. The duration of UVB exposure must be sufficient to catalyze provitamin D3. What is important, however, that this regulation is genetically controlled through the adaptive traits inherited from our ancestors and region of origin. There are reasons for gradation of color based on these genetic traits. An increase of melanin in the skin increases the length of exposure to UV that is required for synthesis of the provitamin D3. For example, the formation of provitamin D3 takes more than five times as long in a very dark skin (Type VI) versus a light skin (Type III).8 Lighter skin types who originate further away from the equator require variable exposure times depending upon their location.

The correct choice of wavelength, correct treatment settings, and technique in hair reduction or another aesthetic laser treatment are indeed important considerations. Whether in laser hair reduction or reducing the appearance of pigment on the skin, and skin rejuvenation, the propensity for adverse reactions increases with darker skin types. Moreover, when there is racial blending, this becomes a red flag for hidden potential risks. Do not be fooled by visual observation. A skin may appear dark but possess an ability to burn (and/or react) due to mixed ancestor traits including undisclosed health issues. Lighter skin types also become susceptible to cellular oxidation and damage when they are living in an area not native to their origins that also increases their risk for cancer. A key is to assess whether a condition is actually treatable. Is the client a good candidate for the service?
And finally, when considering treatment for correcting melasma and other pigmentation disorders one must determine the significance of the initial underlying causes. Do you understand the concepts of the melanogenesis story and the biological implications when melanocytes are damaged, including the mitochondria and possible shortening of the dendrites from oxidative stress, damage, and aging? Is there damage to the keratinocytes? Moreover, considering that pigment is deposited into the cells at the spinosum layer in the newly formed keratinocytes, what if there is a weak spinosum layer or the presence of an imbalanced enzyme or lack of a key chemical substance during this transitional process? Moving further into the dermis structures, the degradation of collagen and elastin, and ground substance (caused from numerous factors including aging and oxidative stress) poses another clue into a larger picture.

FAST FORWARD – 21st Century
How is all of this information relevant to our skin care practice or laser center? It is not enough to look at someone and visually determine their Fitzpatrick type or treatment outcome. Rather there is a subtler underlying story when it comes to successful result of any treatment.


  1. Cosmetic Surgery National Data Bank Statistics, 2010 Report. (Click Here to Retrieve)
  2. Laser hair removal history and current issues. (Click Here to Retrieve)
  3. Sandhu, N., Elston, D. (2010) Cutaneous Laser Resurfacing, Carbon Dioxide. Medscape Reference. (Click Here to Retrieve)
  4. Rawlings, A.V. (2005) Ethnic Skin Types: Are there Differences in Skin Structure and Function? Presented as a keynote lecture at the IFSCC International Conference, Florence, Italy. (Click Here to Retrieve)
  5. Jablonski, N. (2006) Skin: A Natural History. University of California Press. Berkley, California
  6. Black History: Modern scientific explanation of human biological variation – Race. (Click Here to Retrieve)
  7. O'Neil, D. (2011) Human Biological Adaptability. An introduction to Human Responses to Common Environmental Stresses. Behavioral Sciences Dept. Palomar College, San Marcos, California. (Click Here to Retrieve)
  8. Jablonski, N., Chaplin, G. (2000) The evolution of human skin coloration. Journal of Human Evolution; 39, 57-106. (Click Here to Retrieve)
  9. Barrett-Hill, F. (2005) Advanced Skin Analysis. Virtual Beauty, New Zealand.
  10. Alam, M. Ashish, B. et al (2004) Cosmetic Dermatology for Skin of Color. McGraw-Hill Medical, NY. P1-8
  11. Holick, M.F. (1995). Environmental factors that influence the cutaneous production of vitamin D 1-3. Am J ClinNutr 1995:61 (supple): 638S










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