Why sunshine poses a greater cancer risk to redheads

[Guest guest]

As a redhead, what I found below is of particular interest to me.

 

Courtesy of timesonline

 

REDHEADS run a greater risk of skin cancer from exposure to the sun than people

with darker hair.

 

The reason, according to a talk given yesterday at the American Chemical

Society's meeting in Washington, is that small differences in the chemistry of

the skin pigments in people with different coloured hair affects the production

of cancer-causing agents when the skin is exposed to ultra-violet light.

 

The risk of skin cancer is about two to four times higher for redheads and

blonds than for those with dark hair. In 1995 there were 5,626 new cases of

melanoma — the most dangerous form of skin cancer — in Britain, but by 2000 this

had risen to 6,967. Each year about 1,700 people die from melanoma, the third

most common cancer among people aged 15 to 39.

 

A group led by Professor John Simon of Duke University, North Carolina, isolated

the melanin-containing structures, called melanosomes, from human hair and then

measured the oxidation potentials of the different melanins. Oxidation

potentials are a measure of how likely chemicals are to create highly active

oxygen radicals by taking up electrons. Oxygen radicals, in turn, are known to

be damaging to DNA, and DNA damage is the trigger for cancer. So if the team

could find differences in the oxidation potentials of the melanins, it could

explain differences in skin cancer risk.

 

To measure the potentials the team subjected the melanins to precisely tuned

laser light in the right region of the ultraviolet spectrum. The results

reported yesterday showed that black pigments were indeed less likely to produce

oxygen radicals, and red pigments more likely to.

 

While the finding may explain the higher risk of redheads, it does not offer

them any way to reduce it. They will simply have to take greater care not to

become sunburnt.

 

If the red-haired gene carries this risk, why has it not died out? The answer is

that it is indeed much more common in northerly climes, where it may also offer

an advantage. One theory is that the red-haired melanins help the skin to create

vitamin D in colder climates, thus reducing the risk of diseases such as

rickets.