miercuri, 7 septembrie 2011

Red hair and cancer linked

Red hair and cancer linked

With the incidence of melanoma on a constant upswing (it has increased 2000 percent since 1930 in the United States) scientists are eager to learn everything they can about solar radiation and its effect on the skin.

More time spent in the sun, the oft-mentioned depleted ozone filter in the atmosphere and better detection are all blamed for the general increase – but why are redheads and blonds two to four times more likely than others to develop the disease?

A Duke University chemist may have identified one reason that redheads develop more skin cancers. In studies with a highly precise laser, John D. Simon found that skin pigments common to people with red hair and black hair react differently to ultraviolet light. Pigments from the redhead group in particular were more likely to create free radicals – molecules that harm DNA and might cause cancer.

Using a specialized microscope and the help of N.C. State University physicist Robert Nemanich, Simon documented this process, when photons of ultraviolet light are absorbed by microscopic pigment particles, during which process electrons might be knocked loose.
Simon presented his findings Sunday at the national meeting of the American Chemical Society in Washington, noting excitedly that “No one has been able to observe this before!”

Though not yet a definitive cause of cancer, these findings do fit with previous studies on human skin cells and laboratory mice that have shown that pigment common to redheads – and fair skin in general – reacts more readily to the invisible radiation that leads to sunburn and wrinkles.

“There are a zillion steps to this process,” said Lowell Goldsmith, a dermatologist who researches genetic causes of skin disease and edits the journal Investigative Dermatology. “Maybe it can be interfered with at many points.”

To obtain samples for the study, Simon and his team contacted wig manufacturers for black hair, but found the much rarer red hair more difficult and expensive to obtain. Instead, the team financed free haircuts for redheads on Duke’s campus.

The team studied the pigments, called melanin, obtained from the hairs. Those samples are thought to be chemically similar to the pigments embedded in skin cells, which are very difficult to remove.

In Duke’s Free-Electron Laser Lab, they found that it took high-energy ultraviolet light (that which is normally filtered out by the atmosphere) to loosen electrons from the pigment isolated from black hair. Pigment from red hair, however, also changed after exposure to lower-energy ultraviolet light, which does penetrate the atmosphere to reach Earth.

Simon speculates this vulnerability may be shared by all fair-skinned people, because they and redheads tend to have ample supplies of the same type of pigments embedded in their skin cells.

Interest in this study spreads far beyond scientists’ research labs, to the homes and lives of ordinary people. Shannon Klappenbach of North Raleigh is all too familiar with the dangers of the sun on fair skin.

Herself a redhead with three fair-skinned sons (two also redheads), Klappenbach keeps stashes of sunscreen – preferably 45 or 50 SPF – around the house, in her car and in her purse. No one goes outside until back, front, face, arms and legs have been fully slathered.

She’s rooting for scientists to find better ways to protect her children. “Whatever they have,” she said, “I would want to hear about it.”

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