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The color of melanin determines whether it is helpful or harmful in the filtering of ultraviolet rays that can cause skin cancer, according to a study reported October 13 in the Proceedings of the National Academy of Sciences.
Melanin is the source of people’s skin and hair pigmentation.
The study found that blondes and redheads not only are more susceptible to skin cancer, but that their melanin actually magnifies the damaging effects of ultraviolet rays.
"What this tells us is that melanin is not only good for you, it also can be bad. It depends on the color of your particular melanin," said lead researcher Douglas Brash, professor of therapeutic radiology, genetics and dermatology at Yale School of Medicine.
Brash said he had been curious why people with dark hair and fair skin were not as vulnerable to skin cancer as fair skinned blondes and redheads and wondered whether it was related to the melanin.
Using mice engineered with pigmentation for yellow or black hair, as well as albino mice with no pigment at all, the researchers irradiated the mice with ultraviolet rays at a level that is about the same as what humans experience every day.
The researchers found that cell death was concentrated around the hair follicles, which are the only location of melanin in mice. Dying cells were particularly pronounced in the yellow-haired mice and was absent in albinos.
Source: Medical Week staff, week of October 16, 2004
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