Sodium lauryl sulfate, or SLS, is a detergent that has an emulsifying action: it is able to remove oil and dirt from surfaces like hair and skin. It is often included in soaps, shampoos, and other foaming cleaners; however, you may have heard that it can be toxic. Now, many organic and natural products are advertising that their ingredients do not include SLS. You may wonder if it's all just hype, or if it might be worth spending a little more money to buy a product that is SLS-free.
Sodium Lauryl Sulfate
Sodium lauryl sulfate has several other names, according to the Australian government's Department of Aging: Sodium dodecyl sulfate, SDS, Sulfuric acid, monododecyl ester, sodium salt, Lauryl sodium sulfate, Sodium N-dodecyl sulfate, and Lauryl sulfate sodium salt. Known for its ability to break up grease deposits, it is found in many cleaners, from hair care products to engine degreasers. This substance has also been used as a skin irritant in laboratory testing, states healthy-communications.com.
Skin Irritant
SLS is used in experiments as a skin irritant; researchers often look at the effects of various treatment options on irritated skin. In August of 2010, "Contact Dermatitis" published a study that investigated the effects of occlusion, or covering or blocking, on skin that had been irritated by tape removal or sodium lauryl sulfate. Another study published in that journal in the same month, entitled "Influence of tumour necrosis factor-alpha polymorphism -308 and atopy on irritant contact dermatitis in healthcare workers," discovered that exposure to water and sodium lauryl sulfate concentrations of 0.5 and 1.0 percent increased atopic dermatitis in patients with a certain genotype.
Toxicity
General concern over the potential toxicity of SLS reaches back to 1983. The Cosmetic Ingredient Review performed a series of third-party experiments to determine the health risks associated with SLS and its other forms. Published in the "American Journal of Toxicology" volume two in 1983, a panel of researchers found that sodium and ammonium laureth sulfate are eye and skin irritants, and that SLS is not safe when used in cosmetic products at a concentration greater than two percent. Unfortunately, many cosmetic products list SLS as one of the main ingredients; meaning it can be present in concentrations of 20 percent. However, the publication stated that no other toxicity was found.
Mouth Ulcers
SLS and its other forms can often be found in toothpastes. The "Compendium of Continuing Education in Dentistry" featured a study in December 1997 that looked into the correlation between recurrant apthous ulcers, which are blisters that form on the lips, in the mouth, or in the digestive tract. SLS increased irritations, and researchers concluded that products without SLS "should be considered for individuals suffering from recurrent aphthous ulcers."
Conclusions
According to a July 2010 article entitled "Final report of the amended safety assessment of sodium laureth sulfate and related salts of sulfated ethoxylated alcohols" and published in the "International Journal of Toxicology," SLS can be considered an eye and skin irritant at certain concentrations. The study states that SLS should only be used in concentrations that are non-irritating. Based on the evidence in the articles mentioned earlier, concentrations of less than two percent is typically considered non-irritating. No other known concerns or toxicity has been found at present.
References
- Australian government's Department of Aging
- Healthy-Communications.com: Sodium Lauryl Sulfate
- "Contact Dermatitis"; Skin barrier response to occlusion of healthy and irritated skin: Differences in trans-epidermal water loss, erythema and stratum corneum lipids; Jungersted J.M. et al; August 2010
- "Contact Dermatitis"; Influence of tumour necrosis factor-alpha polymorphism -308 and atopy on irritant contact dermatitis in healthcare workers; Davis J.A. et al; August 2010
- Cosmetic Ingredient Review: SLS Alert
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