While there haven't been extensive studies done on DHA and human cells, there have been several studies done on bacteria, animal, and other cells. Here's a breakdown of what they found:

• DHA can penetrate the skin and be absorbed into living skin cells. It was previously believed that it didn't get past the dead skin cells on top of your skin, says Rigel.
• Studies have found that DHA can alter the genes of cells. This hasn't been proven to happen with human cells yet, but Rigel says typically if these results are found with bacteria or animal cells, human cell testing is next.
• In addition to cancer risk, Lynn Goldman, MD, MPH, dean of the School of Public Health and Health Services at George Washington University, says there may also be risks for birth defects if a pregnant woman gets spray tans. However, this is only based on the initial studies done, since there have not been any studies on spray tanning and pregnant women.

Many spray tanning salons reassure customers by telling them that DHA is a food grade ingredient and safe to eat. And that's technically true -- but not when it comes to the DHA in spray tans.

There are actually two chemicals that are abbreviated DHA: One is Docosahexaenoic acid, an essential fatty acid that's often added to infant formula, but never to self-tanner. The other is Dihydroxyacetone, the active ingredient in spray tans, which is a colorless sugar that literally stains your dead skin cells brown, giving you your tan. "These two DHAs are not the same thing," says Rigel. "When someone says you can eat the DHA solution, they're talking about the food-grade DHA."

When ABC news did their initial report, they found Norvell Skin Solutions, one of the largest manufacturers of spray tan products, was telling its customers that they used food-grade DHA in their products. Norvell has since promised to correct its product descriptions.

The biggest concern with spray tans is that you could easily inhale the solution, which means DHA is getting into your lungs and then into your bloodstream. Rey Panettieri, MD, a toxicologist and lung specialist at the University of Pennsylvania's Perelman School of Medicine, says if DHA gets into your bloodstream there is a chance "these compounds in some cells could actually promote the development of cancers or malignancies, and if that's the case then we need to be wary of them."

Obviously, it's hard to inhale a lotion, so Rigel says this form of self-tanner is a somewhat safer bet. "I would say lotions are safer than spray tanning guns because you're not going to breathe in the lotion," he says. "But there's still some risk since your skin can absorb the DHA in lotions," he says.

Rigel and other dermatologists familiar with spray tanning studies are still hesitant to recommend self-tanner lotions. That's because a 1999 study by the FDA found that 11 percent of DHA applied to the skin is going beyond the dead skin cells sitting on top of your skin and getting absorbed into living skin cells in the epidermis and dermis. Further studies are necessary to see if the DHA is actually harming these skin cells, but the fact that it's there at all worries many experts.

"The concern here is we never thought DHA was getting absorbed," Rigel said in his ABC interview. "We thought it's binding to the surface of the skin and that's where the stain is." But this study changes that belief, he says.

If you don't want to stop spray tanning, there are ways to at least minimize the amount of DHA that gets in your system. Rigel recommends covering your eyes with goggles and using nose plugs. But he warns there may still be some absorption, since the particles can stay in the air and goggles and nose plugs don't block everything.

If you decide to get a spray tan, you might want to bring your own eye covers and nose plug, though: ABC News found that nine out of 12 salons they visited didn't have these in stock.

If you're opting to use self-tanner (spray or lotion), there is something else you need to keep in mind: Not only does this faux-bronze not give you any sun protection, it can actually make you more susceptible to sun damage.

A study done at the Gematria Test Lab in Berlin found that DHA-treated skin had 180 percent more free radicals when exposed to the sun than untreated skin. The reason why isn't known, but it does mean you need to be extra careful with your sunscreen when you've got self-tanner on. "I'm not sure how DHA could up the free radicals," Rigel says. "But that may be something we need to address, possibly by adding antioxidants to the formulas." Again, it looks like more research needs to be done.