(Health.com) -- When Alexandra Spunt went for a keratin hair treatment at a Los Angeles salon two years ago, she hoped to walk out with two months' worth of silky-straight locks.

What she didn't expect: two hours of burning eyes and a sore throat.

"The stylist offered me goggles because my eyes stung and I couldn't stop coughing," says Spunt, 32.

She was shocked to learn that the treatment likely contained formaldehyde -- deemed a possible human carcinogen by the Environmental Protection Agency (EPA).

You've heard that pedicure tubs are teeming with fungus. And you probably know that your waxer shouldn't double-dip. But new dangers have been popping up at salons, and it's hard for clients, regulators, and even salon owners to keep up.

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The U.S. Food and Drug Administration (FDA) has a limited ability to regulate cosmetic ingredients, says Claudia Polsky, a deputy attorney general in California's Environment Law section. For instance, "the FDA cannot require ingredient labeling on products intended for salon use only," she says.

And there's no federal body overseeing the safety of salons, or how well-trained employees are. That means it's up to you to get informed. Here's what you need to know to stay safe.

Great hair can be dangerous

Walk into a salon offering a keratin treatment, and you may see stylists in masks with fans pointed their way. And with good reason: Formaldehyde has been ID'd as the key active ingredient in many hair-straightening treatments currently offered in salons.

Recently, Oregon's Occupational Health and Safety Administration found the chemical in samples of nine different products -- one of which was actually labeled "formaldehyde-free." Some epidemiological studies have linked exposure to formaldehyde over several months with certain forms of cancer, such as leukemia.

In the short term, it can cause scalp rashes when it comes into contact with the head; when inhaled (whether you're receiving the treatment or sitting next to someone who is), it can lead to burning eyes, nose, and throat, and even asthma attacks if you're prone to them, says Julia Quint, PhD, a retired toxicologist from the California Department of Public Health.

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While it may be possible to get a safe keratin treatment if the salon is properly ventilated, "we're advising that consumers steer clear altogether," says environmental scientist Alexandra Gorman Scranton, who directs science and research for Women's Voices for the Earth, a nonprofit organization that works to eliminate toxic chemicals that have an impact on women's health.

"Formaldehyde sensitivity can vary from person to person, but you won't know you have a problem with it until you get sick."

Some side effects can be as tough as nails

Manicures and pedicures are perhaps the most common salon treatments, but they're not necessarily the safest. A University of Texas study published in the Archives of Dermatology in 2009 reported on two women who'd developed skin cancers on the backs of their hands.

Both frequently used nail dryers that emit UV light. It's unclear how much the dryers might increase your cancer risk, since lesions take years to develop. What we do know is that they've become a fixture in salons everywhere. So until more research is conducted, many dermatologists advise that you slather on sunscreen before your nail tech applies polish, or stick to fan-based dryers, especially if you get your nails done weekly or monthly.

"I will never use a UV light again," says Carolyn Jacob, MD, a spokeswoman for the American Academy of Dermatology and dermatologist in private practice in Chicago. "Yes, this report was only on two patients. But the UV lights drying your nails are primarily made from UVA light, which means there is potential for cell damage, wrinkling, and skin cancer. Go with the fan dryers instead."

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Peels aren't always so appealing

There's no denying that they work: Chemical peels can brighten and lighten skin to dramatic effect, and help reduce the appearance of fine lines, wrinkles, and age spots.

But some of these formulas are so powerful that they can cause burns and even scarring if handled incorrectly -- and since they're being used more frequently these days, and in more casual settings (like spas rather than a dermatologist's office), the potential for danger is multiplied.

Nia Terezakis, MD, a clinical professor of dermatology at Tulane University Medical Center and dermatologist in private practice in New Orleans, has seen patients come in with white doughnut shapes around their mouths after getting peels from inexperienced salon technicians who left the solution on for too long, permanently damaging the pigment there.

"There's nothing in the world that will put the color back in your skin after that," Dr. Terezakis says.

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So if you're at the salon or spa, stick to "light" peels (such as glycolic peels), which have an alpha-hydroxy acid content under 10 percent and pH level above 3.5, per FDA rules.

"Medium or deep peels should only be performed by a dermatologist with experience in giving them," Dr. Terezakis says.

But know that even a light peel can cause a bad reaction if it isn't done properly.

"Glycolic acid peels have to be neutralized after several minutes with a neutralizing solution or water," Dr. Jacob says. "If they're left on too long, they can burn the skin, leaving blisters, scabs, and sometimes permanent redness."

And even beta-hydroxy peels, which self-neutralize -- eliminating the risk of keeping them on too long -- can burn you if the acidic content is higher than it should be, she adds.

Consider the price of beauty

While the experts we spoke with agreed that it's worth minimizing your exposure to salon hazards, nobody recommended going cold turkey on every spa service you love.

But to stay safe, you must do your homework first. Before you try any new treatment -- even if it's just new to you -- "look for any clinical studies on the active ingredients," Dr. Jacob says.

Not comfortable combing through scientific research? Skin Deep has compiled thousands of reports on ingredient safety, and the FDA issues readable consumer warnings on ingredients.

Ask your doctor if she's heard any reports about the dangers of a device or product, or has any specific concerns about its safety or its effects on you. When in doubt, it can't hurt to wait it out until more has been learned about the service in question.

"Don't be a guinea pig!" Dr. Jacob says.

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And if you have made the educated decision to go in for a treatment, investigate the place you're getting it just as carefully.

"Find out if you know anyone who's been to the salon you're planning to visit" and can report on safety precautions it takes, Dr. Terezakis says. "Check with the Better Business Bureau to see if there have been any complaints. If you're going to a place with a good reputation, they are going to want to conduct business in a way that's safe."

For facial treatments, "trust your dermatologist over anyone else," Dr. Jacob says. Yes, you may have to pay a few bucks more -- but you'll be glad to have someone on hand with years of medical training and experience if something does go wrong.

Copyright Health Magazine 2011