Do tattoos stop sunburn?

Thanks to Julia Newton Bishop, professor of dermatology at the University of Leeds.

Julia - The top scaly layer of our skin is called the epidermis, which protects us from many different harmful things and is renewed constantly so that the tissue remains healthy. The epidermal stem cells are special cells within that skin, and they're replaced every four to six weeks. And the dead cells are shed as scale.

James - The stem cells themselves do self renew, but protecting these cells from damage is crucial in part to prevent them from becoming cancer cells.

Julia - In order to protect these special stem cells from sun damage, the epidermis may thicken up, for example, in people who work outside. But most of the protection results from pigment or melanin, which reduces the sunlight that gets through to the stem cells, which I found at the bottom layer of the epidermis.

James - In people with pale skin, there is less melanin and often a different type of melanin, red or brown in colour rather than black. And this means that there is more damaging energy from the sun reaching the stem cells in the bottom layer of the epidermis, and these cells are then more likely to get damaged and over time become cancerous. The other layer of our skin we have to note is the dermis.

Julia - The dermis lies below the epidermis and has many fewer cells, but is very important for the strength of the skin, is also the structure in which hair follicles, blood vessels, and essential stretches, such as nerves lie.

James - In this layer, you'll find the small muscles which make your hair stand on end in goose pimples and glands, which produce grease and sweat. Below the dermis is fat, fibrous tissue, and larger muscles.

Julia - Tattoo pigment lies in the dermis. That is the tattoo pigment lies below those critical stem cells of the epidermis, and therefore cannot protect them from sun damage, which is why tattoos cannot reduce the risk of skin cancer.

James - Thanks, Julia, and thanks to Cecilio for that thought provoking question. Next time we'll be tackling this question from listener Simon. He says, 'regularly on my car wing mirrors spider's webs form because of their tiny size, I'm wondering if they're able to cope with my car doing 70 miles per hour or do some get blown away? Is the force of the wind pulling them off the web easily overcome by their ability to stay attached to their webs?' Well, what an interesting question.