Marked for life: the science of tattoos may make you think before you ink - tattooist inject ink through into the dermis with a tattoo gun which is a set of electrically-powered needles - includes laser removal pictures, and also Q&A on legalizing teen tattoos

Science World, March 9, 1998 by Anne Lederberg

After I took my last exam of eleventh grade, I felt like I could do anything," says Jennifer Chowdhury, 20. In a burst of bravado Jennifer stepped into a New York City tattoo parlor, where a tattooist pumped needles into her skin up to 3,000 times per minute.

"I was coming to terms with my heritage, which is mixed," she says. Her father, whose ancestors were from India, cried when she was young. Now her family name is inscribed on her ankle. But Jennifer bled and trembled from pain as the tattoo "gun" needled her flesh, skewing the letters on her skin.

Will she come to regret her impulse? A 1996 study of more than 2,000 U.S. high-school students shows that 10 percent of teens now sport tattoos--even though tattooing is illegal for teens in 18 states. But some experts think that for every teen who considers getting inked, another comes to lament the choice and wants his or her tattoo blotted out forever.

Debates rage over tattoos. Are they a celebration of the body or personal defacement--the result of not accepting one's body as it is? Do they express individual uniqueness or signal bowing to peer pressure? One thing seems clear: Branding a tattoo on your body is a lifelong decision- often a painful, potentially dangerous, and illegal one.

INKED INSIDE

Jennifer's tattoo is a permanent emblem because the ink is injected inside her skin. A drawing on the skin's surface layer, the epidermis (see diagram below), would vanish in a few days. That's because the surface layer of the epidermis consists of dead skin cells that constantly flake off. (Think dandruff) In fact, the epidermis sheds one million cells every 40 minutes, or nine pounds worth a year! New cells under this layer constantly replace the lost flakes. A temporary tattoo on the epidermis would just flake off, too.

Instead, a tattooist uses a tattoo gun--a cluster of electrically-powered needles--to inject ink into the skin's middle layer, the dermis. The dermis is a network of blood vessels, hair and nerve cells, sweat glands, and a mesh of protein fibers called collagen, which lends skin its strength. These cells stick with you for life--and so does the tattoo.

PINS AND NEEDLES

Tattoo ink, or pigment, starts as a solid powder. The tattooist combines the tiny clumps of pigment with liquid to form a mixture called a suspension. After dipping the needles into the mixture, the tattooist glides the gun along the skin. With every in- and-out motion, the needles shoot tiny pigment clumps into the dermis. After the pigment lodges in the dermis' cells, the tattoo leaves scars so small they're invisible to the eye.

At least that is what's supposed to happen. Tattooist Denise de la Cerda of Brooklyn, New York, warns that the tattoo gun can be a dangerous instrument when the wrong hand wields it. If a tattooist presses the gun against the skin, the needles can easily pierce fat or muscle beneath the dermis. "That can cause bad scarring or excessive bleeding," she says. When ink penetrates fat, it can spread to appear like a permanent bruise, warns de la Cerda.

Tattooists are also supposed to sterilize their equipment with an autoclave (like a giant pressure-cooker) and use ink poured only for each client. If they don't, any disease carried by bacteria or viruses in the blood--like hepatitis, a liver disease, or HIV, the virus that causes AIDS-- can be transferred from an infected person into the client's bloodstream.

Some people also develop an allergic reaction to tattoo ink that can result in a severe rash, which often must be surgically cut out of the skin. Finally, infection can set in if you don't keep the tattooed skin clean. "My tattooist didn't talk to me about safety--he just wanted to get the job done," Jennifer says.

SCARS AND SURGERY

What can you do if you want to get rid of a tattoo? Fourteen-year-old Michael Dietrich from Dundalk, Maryland, had a fist-sized bulldog branded on his chest when he was 13. "I look up to the Marine Corps, and the bulldog is their symbol," he says. But when Michael's mom saw it, she ordered him to have his tattoo removed--and fast.

Michael could have traded his tattoo for a scar. Dr. Rox Anderson, a dermatologist (skin doctor) from Massachusetts General Hospital, has removed unwanted tattoos by cutting out the skin with a scalpel or "sanding" them off with a wire brush. Both methods remove the dermis, which heals, but leave scars as a grim reminder.

Instead, Michael opted for costly (often $2,000-$3,000), painful, but more effective laser therapy that blasts the tattoo ink yet spares the skin.

How? A laser is an intense beam of concentrated light energy. The dark colors of tattoo pigments absorb this energy--much like a black parking lot absorbs heat and light from the sun. Because skin doesn't absorb the light energy as much as the tattoo does, the skin remains unharmed.

When a laser beam strikes a clump of tattoo pigment, the light energy is converted to heat. Heat sizzles the pigment clumps to 300 [degrees] C (572 [degrees] F), breaking them up into tiny particles.