Not long after she had a black crucifix tattooed onto her lower back, Leslie Wagner began asking herself the kind of question you might expect from a curious chemistry major.
What’s in the ink?
Surprised to find almost nothing in the scientific literature — and no comprehensive ingredient lists on the bottles — the Northern Arizona University senior enlisted a classmate and her chemistry professor and then set out to solve the mystery.
In a handful of laboratories around the world, researchers are starting to put tattoos under the microscope — literally, in some cases — to better understand the science behind one of the world’s oldest art forms.
Their interest is more than academic. Long associated with biker gangs and convicts, tattoos have become the de rigueur body decoration for a clientele that ranges from sorority girls to Hollywood celebrities. A 2004 Harris Interactive survey found as many as one in six Americans — and nearly half of 18- to 29-year-olds — are inked.
Although generally considered safe, tattooing and laser tattoo removal are not without risks. Inadequately sterilized needles can transmit hepatitis C and other infectious diseases. Tattoos themselves can trigger severe allergic reactions and other skin problems.
As a result, much of the scientific work is focusing on inks, products whose formulas are often closely held secrets and that traditionally have not been closely scrutinized by U.S. and European regulators.
In a preliminary analysis of 17 tattoo inks from five different manufacturers, the Northern Arizona University team found lead, copper and other potentially harmful heavy metals in the pigments.
The researchers, who announced their findings last month at a meeting of the American Chemical Society in San Diego, caution that the health effects of these metals have yet to be determined. That will require an understanding of just how inks behave in the body, a process investigators are only now beginning to grasp.
CREEPING COLOR
Despite outward appearances, tattoos don’t totally stay put.
Scavenging macrophages — immune-system cells that rid the body of dead or foreign matter — can gobble up and cart away pigment particles. Pigment also can wind up in the skin’s lympahtic vessels, where they flow to the nearest lymph nodes and perhaps beyond.
“We have seen a lot of colored lymph nodes,” says Wolfgang Baumler, a physicist at the University of Regensburg in Germany who studies tattoo inks and their behavior in the body. “If you have a green tattoo on your arm, your axillary [armpit] lymph nodes are probably also green.”
This makes knowing what’s inside the ink bottles all the more important, Baumler says.
In his own recent chemical analysis of 41 commercial tattoo inks sold in the United States and Europe, Baumler and his colleagues found chemical evidence of industrial pigments. These pigments, he says, are typically used in printing, auto paints and plastic dyes. Full of impurities, they aren’t designed for human consumption, he notes.
Tattoo inks exhibit other potentially problematic behavior in the body.
Scientists at the Food and Drug Administration’s National Center for Toxicological Research have found that pigments chemically break down in the presence of sunlight.
The research may help explain why tattoos fade over time and why some people’s tattoos begin to itch when they go outdoors.
EFFECTS OF LASER
Knowing what’s in a tattoo may be useful for reasons beyond health: It could make body art easier to erase.
“Tattoos are far more difficult to remove than they are to acquire,” notes R. Rox Anderson, a dermatologist at the Massachusetts General Hospital who has conducted pioneering research on laser treatment of tattoos.
Although dermatologists have been removing tattoos with lasers since the 1960s, there are many mysteries about why the technology works and why it sometimes doesn’t.
Laser light may have other unexpected consequences. Last fall, Baumler and his team published the first evidence that lasers can cause tattoo pigments to break down into known cancer-causing compounds.
“Whether this is enough to get skin cancer, we don’t know,” Baumler stresses.
Although state and local health departments have traditionally monitored tattoo artists to prevent disease transmission, regulation of ink is another story.
The pigments used to color tattoo inks technically require premarket approval by the FDA, which monitors color additives in foods, medicines and other products intended for human consumption.
In practice, however, inks rarely receive close scrutiny unless a problem comes to light, says Linda Katz, director of the agency’s office of cosmetics and colors.
Katz says that continuing studies of the chemical properties and biological behavior of tattoo ink may ultimately prompt the agency to step up its surveillance of the industry. For now, she says, it’s too soon to tell.
