What is it? Sodium Lauryl Sulfate (SLS) is a foaming agent made from coconut oil, which is commonly used in personal care products. Its ability to form lather makes it a key ingredient in toothpastes, shampoos and face wash.

SLS has plenty of uses outside of your beauty bag, too. It’s found in household cleaners and pesticides, and when used at industrial-strength levels, SLS acts as a degreaser in car wash detergent and concrete floor cleaners.

It’s also used as a food additive in egg whites and marshmallows, because it works as a wetting agent and an emulsifier.

On a side note, don’t confuse SLS with its similar-sounding cousin, Sodium Lauryl Ether Sulfate (SLES); their chemical structures is different. In fact, SLES is considered a milder agent.

You’ll find it in: In addition to soap and shampoo, SLS is used in self tanner, shaving cream and liquid foundation.

The detergent is also a registered flea and tick repellent used in pet shampoos and can be found in soap scum remover and carpet cleaner.

Concerns over SLS: How is it possible that the main ingredient in industrial cleaners is also used in skincare products? The debate has waged on for years, but experts agree that when used in minimal amounts, SLS is safe for your skin.

Research shows that the only real danger is eye irritation and dry skin. In a study published in the Journal of the American Academy of Dermatology, researchers applied SLS to the forearm and upper back of 10 women for 24 hours.

Results revealed that the amount of water that normally evaporated from the skin’s surface increased, leaving the SLS-treated areas drier than the surrounding skin. This study suggests that those with sensitive or dry skin should avoid products with SLS, since it can aggravate the condition. You can also consult with a dermatologist about using these products.

On the other hand, those with normal or oily skin don’t need to worry about using SLS on a daily basis. According to the Cosmetic Ingredient Review, the cleansing agent is safe in products used for a short time if they’re immediately rinsed from the skin, such as soap and shampoo.

In addition, some claims charge that SLS is a carcinogen. At one point, chain e-mails circulated the Web warning people to stay away from the detergent, asserting prolonged use would cause cancer.

According to the American Cancer Society, it’s merely a myth. Its Web site clearly states that SLS and its compounds aren’t known carcinogens.

Beauty Brains — a highly reputable blog written by cosmetic chemists — agrees, noting, "Don’t believe all the urban legends about SLS causing cancer or being bad for you because it’s used in garage cleaners." In fact, sulfates enhance the cleansing abilities of shampoos and body wash, they add.

Also, according to the blog, though most people can use SLS products, for some, shampoos with SLS can dry their scalp. Consequently, they suggest switching to a shampoo that uses the milder SLES or one that’s sulfate-free.

What about children? Because SLS is an irritant, it's too harsh on baby’s skin and scalp (recall it can be overly drying for some adults, especially those with sensitive skin). Some sources have suggested SLS products are even dangerous for children’s eyes, though this hasn’t been substantiated.

What we do know is that SLS can cause eye and skin irritation in children, so watch out for this ingredient on product labels. Also, even if a product states it’s safe for kids, parents should still study the label. According to Baby Center, ingredients like cocamidopropyl betaine or cocamidopropyl hydroxysultaine cause the least irritation.

SLS-free product picks: If you find SLS products do irritate your skin, you’ve got plenty of options. Try Juice Beauty Cleansing Gel, which contains organic ingredients like lemon juice and sage leaf to gently cleanse your skin without irritating it.

If you’re looking for a toner, consider Caudalie Grape Water Harvest, a great way to hydrate and refresh the skin.

Known for its high concentrations of natural ingredients, L’Occitane also offers a number of SLS-free products. If you have limp hair, try L'Occitane Aromachologie Volumizing Shampoo, a volumizing cleanser you can use every day.

Bottom line: SLS is neither dangerous nor a carcinogen. It is, however, considered an irritant, known to dry out skin. If you’re using a product with SLS and it&rquo;s working well, then it’s fine to stick with it. For children, however, it’s best to go with other, less irritating ingredients. And when in doubt, talk with your doctor.