Sun screen | Science News for Students

Sun screen

Too much sun can damage your skin and may lead to skin cancer later in life
Jun 26, 2006 — 12:00 am EST
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Merlas/istockphoto

When summer comes, I get sun crazy. I like to eat on the patio and lie on the beach. I walk and bike everywhere. I even bring my work outside. Soaking up the sun feels so good—as long as I'm wearing sunscreen and a hat.

Putting on sunscreen and wearing a hat helps prevent sunburn on a sunny day.

Putting on sunscreen and wearing a hat helps prevent sunburn on a sunny day.

Katie Wiley

When I was younger, I played in the sun without worry. Now that I'm 30, I realize how important it is to protect myself. That's because the same ultraviolet (UV) rays that make us warm and tan also harm the cells in our skin. You can't see the damage when you're young, but its effects often show up decades later.

After years of tanning, the skin gets wrinkled, leathery, and, worst of all, prone to skin cancer. The disease is directly linked to UV exposure, says Mandeep Kaur. She's a dermatologist at Wake Forest University School of Medicine in Winston-Salem, N.C.

As young people flock to beaches and tanning salons, skin cancer is becoming more common and appearing at younger ages, Kaur says.

"We used to see only older and middle-aged people with skin cancer," she says. "These days, we see people in their 20s or 30s."

Tanning dangers

Kaur and her colleagues reviewed a large number of studies about skin cancer and UV light. The disease, they found, is the most rapidly growing cause of cancer deaths in the United States.

Even so, doctors rarely warn their young patients about the dangers of tanning.

What your doctor should tell you is that your skin is the largest organ in your body. It keeps your stomach and other organs from spilling out. And it keeps germs from getting in. Skin allows you to feel pain, heat, cold, and other sensations. And through sweat, it rids your body of extra water and salt. Can you imagine life without it?

A desert isn't the only place where it's essential to put on sunscreen for protection against the sun's ultraviolet rays. Even on a cloudy day, ultraviolet rays can still cause sunburn.

A desert isn't the only place where it's essential to put on sunscreen for protection against the sun's ultraviolet rays. Even on a cloudy day, ultraviolet rays can still cause sunburn.

Annie Feidt

Although our skin works hard to protect us, few people work to protect it. The sun's UV rays are the biggest threat because they damage the genetic material DNA in the cells of your skin. Damaged, or mutated, cells are supposed to kill themselves, but sun-damaged skin cells eventually become cancerous and multiply out of control. They produce abnormal growths called tumors.

The tricky thing is that this process can take 30 or more years to become evident.

"It's surprising how long it takes," says Meenhard Herlyn, a tumor biologist at the Wistar Institute in Philadelphia. "Even if kids have big, blistering sunburns every summer, they're fine while they're kids."

Skin cancer

There are two categories of skin cancer. Nonmelanoma tumors develop in the outermost layer of skin. They usually appear on the head, neck, and other exposed areas. There are about 1 million new cases of nonmelanoma in the United States each year, according to the American Cancer Society. Doctors can easily remove most of these cancers if they catch them early.

The second type of skin cancer is melanoma. It is less common than nonmelanoma cancer. There are only 60,000 new cases a year in this country. However, melanoma is far more likely to spread to other organs and become deadly. Melanoma affects the cells in your skin that produce pigment, or color, that makes you tan. These cells are most active when you're young, so getting sunburns during childhood puts you at especially high risk.

Melanoma is a cancer of the skin's pigment cells. It appears as a new spot or an existing spot that changes color, size, or shape. It usually has an uneven, smudgy outline and appears as an irregular mix of colors.

Melanoma is a cancer of the skin's pigment cells. It appears as a new spot or an existing spot that changes color, size, or shape. It usually has an uneven, smudgy outline and appears as an irregular mix of colors.

Department of Dermatology, Uniformed Services University of the Health Sciences

"If you have more than five blistering sunburns while you're under 15," Herlyn says, "it increases your risk for getting melanoma three- to fivefold."

All types of skin cancer occur most often in people who have red or blonde hair, freckles, or pale skin that burns easily. People with naturally dark skin rarely get skin cancer.

Skin cancer treatment usually involves surgery to remove damaged cells, but new approaches are in the works. The most promising leads come from studies of internal signals that cancer cells use to stay alive.

"We're slowly getting to know what makes melanoma cells tick," Herlyn says. If researchers can block the important signals with drugs, the bad cells might die.

Herlyn's coworkers, for example, are working on a melanoma vaccine that would help a patient's immune system recognize and attack skin cancer cells. Other scientists are creating lotions that could help cells repair themselves.

Sunning safely

The best way by far to fight skin cancer is to not get it in the first place. That doesn't mean you have to stay inside all the time. You just have to learn how to be sun savvy.

Putting on sunscreen is essential before surfing and other outdoor activities.

Putting on sunscreen is essential before surfing and other outdoor activities.

E. Sohn

The American Academy of Dermatology recommends wearing sunscreen (SPF 15 or higher), sunglasses, wide-brimmed hats, long-sleeved shirts, and long pants whenever possible. Avoid direct sunlight when it's at its strongest—between 10 a.m. and 4 p.m. Be careful near snow, sand, and water, which create strong reflections. And avoid tanning beds.

These steps may seem extreme if you live in a place where tanned skin is considered attractive. But if you want a wrinklefree, cancerfree future, it may be time to think about the cost of "beauty" that doesn't last.

"If you want to be healthy," Kaur says, "you have to have good skin."


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Comments:

I'm very good with sunscreen and all that, but if people don't want us to get skin cancer then why do they price it so high?—Stephanie, 12

Power Words

(for more about Power Words, click here)

biologist     See biology.

cancer     Any of more than 100 different diseases, each characterized by the rapid, uncontrolled growth of abnormal cells. The development and growth of cancers, also known as malignancies, can lead to tumors, pain and death.

cell     The smallest structural and functional unit of an organism. Typically too small to see with the unaided eye, it consists of a watery fluid surrounded by a membrane or wall. Depending on their size, animals are made of anywhere from thousands to trillions of cells. 

colleague     Someone who works with another; a co-worker or team member.

dermatology     The branch of medicine concerned with skin disorders and their treatments. Doctors who treat these disorders are called dermatologists.

develop     (in biology) To grow as an organism from conception through adulthood, often undergoing changes in chemistry, size and sometimes even shape. (as with towns) The conversion of wildland to host communities of people. This development can include the building of roads, homes, stores, schools and more. Usually, trees and grasslands are cut down and replaced with structures or landscaped yards and parks.

DNA     (short for deoxyribonucleic acid) A long, double-stranded and spiral-shaped molecule inside most living cells that carries genetic instructions. It is built on a backbone of phosphorus, oxygen, and carbon atoms. In all living things, from plants and animals to microbes, these instructions tell cells which molecules to make.

genetic     Having to do with chromosomes, DNA and the genes contained within DNA. The field of science dealing with these biological instructions is known as genetics. People who work in this field are geneticists.

germ     Any one-celled microorganism, such as a bacterium or fungal species, or a virus particle. Some germs cause disease. Others can promote the health of more complex organisms, including birds and mammals. The health effects of most germs, however, remain unknown.

immune     (adj.) Having to do with the immunity. (v.) Able to ward off a particular infection. Alternatively, this term can be used to mean an organism shows no impacts from exposure to a particular poison or process. More generally, the term may signal that something cannot be hurt by a particular drug, disease or chemical.

immune system     The collection of cells and their responses that help the body fight off infections and deal with foreign substances that may provoke allergies.

melanoma     A type of cancer that starts in pigment-making cells called melanocytes, usually in the skin.

organ     (in biology) Various parts of an organism that perform one or more particular functions. For instance, an ovary is an organ that makes eggs, the brain is an organ that makes sense of nerve signals and a plant’s roots are organs that take in nutrients and moisture.

pigment     A material, like the natural colorings in skin, that alter the light reflected off of an object or transmitted through it. The overall color of a pigment typically depends on which wavelengths of visible light it absorbs and which ones it reflects. For example, a red pigment tends to reflect red wavelengths of light very well and typically absorbs other colors. Pigment also is the term for chemicals that manufacturers use to tint paint.

risk     The chance or mathematical likelihood that some bad thing might happen. For instance, exposure to radiation poses a risk of cancer. Or the hazard — or peril — itself. (For instance: Among cancer risks that the people faced were radiation and drinking water tainted with arsenic.)

salt     A compound made by combining an acid with a base (in a reaction that also creates water). The ocean contains many different salts — collectively called “sea salt.” Common table salt is a made of sodium and chlorine.

savvy     The quality of possessing useful and clever knowledge.

sun     The star at the center of Earth’s solar system. It’s an average size star about 26,000 light-years from the center of the Milky Way galaxy. Also a term for any sunlike star.

tick     A small eight-legged blood-sucking arthropod, related to spiders and mites. Although they look like bugs, these are not insects. They attach themselves to the skin of their host and feed on their blood. But in the process, they may spread any germs that could have been present in the blood of an earlier host.

tumor     A mass of cells characterized by atypical and often uncontrolled growth. Benign tumors will not spread; they just grow and cause problems if they press against or tighten around healthy tissue. Malignant tumors will ultimately shed cells that can seed the body with new tumors. Malignant tumors are also known as cancers.

ultraviolet     A portion of the light spectrum that is close to violet but invisible to the human eye.

vaccine     (v. vaccinate) A biological mixture that resembles a disease-causing agent. It is given to help the body create immunity to a particular disease. The injections used to administer most vaccines are known as vaccinations.

wake     An area of disturbed air or water left behind an object (such as a boat or animal) moving through it.