July 24, 2012
Tanning Beds Worse Than Exposure To Sun
Connie K. Ho for redOrbit.com — Your Universe Online
While pale can be described as “pasty” and “sickly,” tan can be described as “glowing” and “lively.” In the past, pale skin was cherished and associated with wealth. These days, people seek tan skin and tanning has had resurgence in recent years. A study by the George Washington School of Medicine and Health Sciences (SMHS) looked at how skin melanoma was affected by UV and melanin.The findings of the project were recently published in Nature Communications.
“This is the first time that UV-induced melanin formation (tanning), traditionally thought to protect against skin cancer, is shown to be directly involved in melanoma formation in mammals,” explained researcher Edward C. De Fabo, professor emeritus at SMHS, in a prepared statement. “Skin melanoma is the most lethal of the skin cancers. Our study shows that we were able to discover this new role for melanin by cleanly separating UVA from UVB and exposing our experimental melanoma animal model with these separated wavebands using our unique UV light system designed and set up at GW. Dermatologists have been warning for years there is no such thing as a safe tan and this new data appears to confirm this.”
The researchers utilized a mammalian model to test how melanoma formed in regards to precise spectrally defined ultraviolet wavelengths and biologically relevant doses. They found that two ultraviolet wavelength-dependent pathways can initiate malignant melanoma of the skin. They also discovered that melanin had an important effect in producing melanoma genesis.
“Also new is our discovery that UV induction of melanin, as a melanoma-causing agent, works when skin is exposed only to UVA and not UVB radiation. This is especially important since melanoma formation has been correlated with sunbed use as many epidemiological studies have shown. One possible reason for this is that tanning lamps are capable of emitting UVA radiation up to 12 times, or higher, the UVA intensity of sunlight at high noon. Melanin plus UVA is known to cause photo-oxidation, a suspected, but still to be proved, mechanism for the formation of melanoma as we describe in our study,” De Fabo commented in the statement.
As such, the scientists believe that having a tan is harmful and makes the skin vulnerable.
“Skin responds to ultraviolet exposure with protective responses, which include facultative pigmentation (or tanning). In contrast to constitutive pigmentation, however, a tan is a relatively poor protector against subsequent ultraviolet damage and tanning in response to ultraviolet A conferred no protection,” wrote the researchers. “Our studies suggest, therefore, that minimally protected melanocytes in fair skin are vulnerable not only to ultraviolet B but, if stimulated to carry out melanin synthesis, are also vulnerable to ultraviolet A-induced melanoma.”
The teams of investigators believe that more studies will be needed to be done on the topic for further understanding.
“In summary, the demonstration of pigment-independent ultraviolet B and pigment-dependent ultraviolet A pathways in mammalian melanoma is novel and is expected to lead to deeper insights into the mechanisms of melanoma formation by solar ultraviolet radiation,” concluded the authors in their report.