Sun Tanning | Base Tan

Nature's Sunscreen

The primary goal of every trained tanning professional is to teach sunburn prevention to every client. Building a gradual suntan actually creates two different forms of natural protection against sunburn:

  • Melanin pigment is produced in outer skin cells after being exposed to sunlight. Melanin literally enshrouds and shields skin cells in the epidermis, protecting each cell from getting too much UV exposure.
  • After sun exposure, Extra keratin migrates to the surface of the skin, thickening it, which makes the skin naturally more resistant to sunburn.

These two steps combine to create a powerful natural sunscreen that doesn’t wash off quickly. One benefit of indoor tanning is that trained operators can give a tanner controlled UV exposure to gradually develop this sunscreen – often called a “base tan” – while minimizing the risk of sunburn.

The value of a base tan, as millions of sunbed users know, is that it adds another layer to your sunburn protection arsenal – making chemical sunscreen worn outdoors for outings on sunny days even more effective at preventing sunburn. Here’s how that works:

  • The effectiveness of chemical sunscreen products are measured in what is called “Sun Protection Factor” (or SPF). An SPF 15 product means a user can spend 15 times longer in the sun while wearing sunscreen before they would sunburn if applied correctly.
  • Say, for example, a sunbed user begins tanning under the direction of a trained salon operator following the exposure schedule of that piece of equipment (average start time 2 to 3 minutes). After about a month that tanner may gradually develop a tan and works her/his way up to the maximum session time. At this point, she/he becomes naturally up to SIX TIMES more resilient to sunburn than when she first started tanning. So that tan has an SPF 6 value (BC Health Ministry Report 2012).
  • When someone with a base tan uses sunscreen outdoors, they essentially multiply the sunburn-prevention effectiveness of the sunscreen. In other words, an SPF 15 product applied to the skin correctly of a person whose base tan has already made her six times more resilient to sunburn creates a net SPF of 60. (SPF 15 x 6 = SPF 90).

That’s the reason so many indoor tanning clients come to salons in the winter and spring prior to sunny vacations. In sunny environments many fair-skinned people can sunburn during normal outdoor activities even while wearing chemical sunscreen. But with a base tan their chemical sunscreen becomes more effective and they are much less likely to sunburn.

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WHO IARC 2012 Monograph

First, outdoor workers are not at a substantially increased risk of melanoma (IARC, 1992; Armstrong & Kricker, 2001); second, outdoor workers tend to have a higher than- average ability to develop a tan (Green et al., 1996; Chang et al., 2009).

Outdoor workers tend to be constitutionally protected from solar skin damage and at a lower risk of skin cancer than workers in other occupations because of self-selection based on skin pigmentation. Indeed, such self-selection has been observed in a non-Hispanic white study population from Philadelphia and San Francisco, USA, whereby the average number of hours outdoors in general increases with an increasing ability to tan (Fears et al., 2002). The role of baseline sun sensitivity (Skin Type) in influencing sun exposure in the etiology of melanoma has long been recognized (Holman et al., 1986; Nelemans et al., 1995).

Photoprotection by 1,25-dihydroxyvitamin D and analogs: Further studies on mechanisms and implications for UV-damage R.S. Masona, V.B. Sequeiraa, K.M. Dixona, C. Gordon-Thomsona, K. Pobrea, A. Dilley b, M.T. Mizwickic, A.W. Normanc, D. Feldmand, G.M. Hallidaye, V.E. Reevef (2010)

The two well known mechanisms of endogenous photoprotection are increased pigmentation and increased cornification[2,3,12]. The increased depth of the stratum corneum attenuates UV penetration (Fig. 1). Melanin, which absorbs UV and thus protects DNA, is produced in greater amounts by melanocytes after UV and is transferred to adjacent keratinocytes,…

It also means that like increased cornification and increased pigmentation, increased concentrations of D (vitamin D) compounds in skin act to protect against the next, rather than the initial UV exposure.

De Winter S, Vink AA, Roza L, Pavel S. Solar-Simulated Skin Adaptation and its Effect on Subsequent UV-Induced DNA Damage. J Invest Dermatol. 2001 Sep;117(3):678-82.

Repeated skin exposure to ultraviolet radiation leads to increased tolerance for erythema. Repeated solar irradiation of the skin not only results in increased pigmentation but also in skin thickening. Skin adaptation provides measurable protection against UV-mediated DNA injury. This study reported: “We here demonstrate that our irradiation regimen provides protection against erythema and DNA damage formation: a 4-fold higher dose was required to cause erythema, and 60% less cyclobutane pyrimidine dimers (CPD) formation was the result after a fixed dose of three times the initial MED.”  A tan ie skin adaptation, resulted in two-thirds less CPD formation or damage. The study concluded: “Indoor tanning is not safer than the sun but the use of timers and the possibility of easily regulating the exposure frequency could make it safer than the attitude of millions of people who want to get a tan during the first days of their sunny holidays.”

Agar N, Young AR. Melanogenesis: a photoprotective response to DNA damage? Mutation Research Fundamental and Molecular mechanisms of Mutagenesis 571 (2005) 121-132

Photoprotection – Protection was thought to be due to both pigmentation and epidermal thickening. The importance of hyperplasia in photoprotection was validated in studies looking at vitiligo skin, which is characterized by a lack of melanocytes. Repeated exposure to this skin was shown to elicit a protection factor of 15 in the absence of melanocytes. In contrast, selective activation of melanocytes by UVA (that does not induce stratum corneum thickening) only gave a protection of 2-3. The authors suggested that the stratum corneum accounted for over two-thirds of photoprotection observed in normal skin and hence was far more significant in this role than induced tanning.

Greaves M. Was skin cancer a selective force for black pigmentation in early hominin evolution? Proc. R. Soc. B 281:2013.2955

Darker skin gives individuals much greater protection from UV light-induced skin cancer. Pale-skinned people are roughly 1,000 times more likely than individuals with dark skin to suffer from the three most common skin cancers. “Melanin provides a crucial filter for solar UV radiation and its genetically determined variation influences both skin pigmentation and risk of cancer.”

Gilchrest et al. The Pathogenesis of melanoma induced by ultraviolet radiation. N Engl J Med. 1999 Apr 29;340(17):1341-8

“That melanin provides effective photoprotection is suggested by the fact that poorly melanized skin is far more vulnerable than melanized skin to acute and chronic injury caused by ultraviolet radiation (sunburn and photoaging or photocarcinogenesis, respectively). The photoprotective role of melanin is further evident in the phenomenon of tanning, or the darkening of the skin that occurs within several days after exposure to ultraviolet radiation. This response to injury in the skin serves as a long-lasting endogenous “sunscreen” with a measured sun protection factor of approximately 3 to 5.”

Guido Bens. Sunscreens. Chapter 25 – Sunlight, Vitamin D and Skin Cancer, Second Edition, edited by Jorg Reichrath 2014 Landes Bioscience

“The suppression of natural photoprotection mechanisms by the currently marketed sunscreens: Melanine synthesis, release of melanosomes, and thickening of stratum corneum are mainly triggered by UVBR that is effectively blocked by modern sunscreens. The sunscreen user is thus more submitted to the harmful epidermal and dermal effects of UVAR than an unprotected individual who will undergo natural adaptation that protects against both UVBR and UVAR. This is consistent with the observation that people with important chronic UV exposure by occupational outdoor activity, e.g., agricultural workers, who typically have tan and skin thickening in sun-exposed sites, are at a significantly reduced risk of melanoma compared with indoor workers with intermittent UV exposure.”

Weinstock MA, Colditz GA, Willett WC, Stampfer MJ, Bronstein BR, Mihm MC, Speizer FE. Melanoma and the sun: The effect of Swimsuits and a “Healthy” Tan on the Risk of Nonfamilial Malignant melanoma in Women. Am J Epidemiol. 1991 Sep 1;134(5):462-70

A study examining the effects of swimsuits and a “healthy” tan found that sun sensitivity played a primary role for the development of melanoma. “We suggest that this is of particular importance because during the summer, sun-resistant individuals who expose themselves frequently to the sun develop a significant tan, which appears to protect them from melanoma relative to sun-sensitive women. We speculate that the risk associated with intermittent exposure may be closely related to the fading of a photoprotective tan.” Researchers found that swimsuit wearing among sun-resistant phenotypes was statistically significantly protective for the risk of melanoma RR 0.3, whereas among sun-sensitive phenotype risk was statistically elevated RR 3.5. The study concluded “For sun-resistant individuals, who tan readily and are not susceptible to sunburn, frequent sun exposure appears not to increase melanoma risk and may in fact decrease that risk. ”

Holly EA, Aston DA, Cress RD, Ahn DK, Kristiansen JJ. Cutaneous melanoma in women. I. Exposure to sunlight, ability to tan, and other risk factors related to ultraviolet light. Am J Epidemiol. 1995 May 15;141(10):923-33.

An all-year-tan is protective against melanoma. A research study by Holly (USA) published in 1995 found that women who maintain a tan year-round are at a 50% reduced risk for developing melanoma (OR 0.49).