Neways Non Toxic Products:
Sodium Lauryl Sulfate in Shampoos: The Real Story
By David Steinman
Talk to many health-conscious consumers today about personal care products and one of their main topics of concern is use of the allegedly dangerous shampoo ingredient, sodium lauryl sulfate. But is sodium lauryl sulfate truly dangerous or has it received a bad rap? Or does the answer lay somewhere between these two extremes?
This is not an inconsequential question, since our recent marketplace review of more than 100 leading brands of shampoos indicates that most contain this ingredient. The reason sodium lauryl sulfate is used, we believe, is because it is an inexpensive detergent and makes mixtures foam well.
All shampoos are irritating. Shampoos rank among the products most often reported to the Food and Drug Administration for association with scalp irritation, stinging eyes, and tangled, split, and fuzzy hair. Most shampoos contain synthetic detergents for washing hair. But is sodium lauryl sulfate the culprit when it comes to irritation?
Could be.
What Science Says About Sodium Lauryl Sulfate
In its final report on the safety of sodium lauryl sulfate, the Journal of the American College of Toxicology notes that this ingredient has a "degenerative effect on the cell membranes because of its protein denaturing properties." What's more, the journal adds, "high levels of skin penetration may occur at even low use concentration."
Interestingly, sodium lauryl sulfate "is used around the world in clinical studies as a skin irritant," notes the journal. The publication expressed additional concerns:
- Carcinogenic nitrosamines can form in the manufacturing of sodium lauryl sulfate or by its inter-reaction with other nitrogen-bearing ingredients within a formulation utilizing this ingredient.
- Other studies have indicated that sodium lauryl sulfate enters and maintains residual levels in the heart, liver, lungs and brain from skin contact. This poses the question whether it could be a serious potential health threat from its use in shampoos, cleansers, and toothpastes.
- Still other research has indicated sodium lauryl sulfate may be damaging to the immune system, especially within the skin. Skin layers may separate and inflame due to its protein denaturing properties.
- Although sodium lauryl sulfate is not carcinogenic in experimental studies, it has been shown that it causes severe epidermal changes in the area it is applied, indicating a need for tumor-enhancing assays.
- Additional studies have found that sodium lauryl sulfate is heavily deposited on the skin surface and in the hair follicles. Damage to the hair follicle could result from such deposition.
Threat to Eye Health
Damaging effects of sodium lauryl sulfate on eye health are also of concern. In experimental, acute eye tests, a solution of 10 percent sodium lauryl sulfate "caused corneal damage to the . . . eyes if not irrigated or irrigation was delayed."
A solution of 5.1 percent "caused mild irritation."
There may be another more insidious problem with use of sodium lauryl sulfate. Bear with us if we use a little scientific lingo in this section of the report. Your reward will be a better appreciation for whether sodium lauryl sulfate poses undesirable health effects. Often, in order to make a shampoo gentle to the eyes, the manufacturer will utilize a combination of anionic surfactants (i.e., detergents) with nonionic detergents. An anionic detergent contains a negatively charged polar group. A nonionic detergent has no polar end. Anionic detergents "display remarkable detergent, emulsifying, and foaming properties." Nonionics are "generally considered as the mildest of all surfactants" whose use "has been restricted because of poor foaming potential. They serve more often as auxiliary detergents."
However, while anionic detergents such as sodium lauryl sulfate are the most irritating to the eye, nonionic detergents are less irritating. What's more, according to Tom Conry, author of Consumer's Guide to Cosmetics, "Some of the nonionic surfactants are believed to anesthetize the eyeball. Although we have not been able to track down all of these anesthetizing surfactants, the most common ones are cocamide MEA and DEA, and lauramide MEA and DEA." This is why anionic detergents are frequently combined with nonionic detergents to make shampoos gentle to the eye. In essence, while more aggressive anionic detergents like sodium lauryl sulfate are irritating the eye, the eyeball has been anesthetized by nonionic detergents also in the formulation. Look at shampoo labels and such combinations will be apparent.
Further, according to the Journal of the American College of Toxicology, "Tests show permanent eye damage in young animals from skin contact in non-eye areas. Studies indicated sodium lauryl sulfate kept young eyes from developing properly by possibly denaturing the proteins and not allowing for proper structural formation. This damage was permanent."
Substitution of Gentler Detergents Poses Additional Risks
Unfortunately, many of the gentler detergents that may be substituted for sodium lauryl sulfate pose their own health hazards. For example, many companies have begun to use ethoxylated detergents such as sodium laureth sulfate, cocamide DEA or lauramide DEA because they tend to be less irritating.
Consumers can recognize shampoo ingredients containing ethoxylated detergents and related ingredients by looking for the prefix, word, or syllable PEG, polyethylene, polyethylene glycol, polyoxyethylene, eth (as in sodium laureth sulfate), or oxynol.
Both our own commissioned independent laboratory testing and that of the federal government have documented ethoxylated alcohol compounds are frequently contaminated with 1,4-dioxane, which is carcinogenic and is listed by the federal government as a probable human carcinogen.
Also, according to a 1998 report from the federal National Toxicology Program, two DEA-based compounds;cocamide DEA and lauramide DEA have been demonstrated to be cancer-causing in at least in one species of animal.
The Doctors' Prescription for Healthy Living/ Safe Shopper's Bible Recommendation
According experts on the Cosmetic Ingredient Review (CIR) panel (established by the Cosmetic Toiletry, and Fragrance Association, a cosmetic industry trade association), both sodium lauryl sulfate and its close chemical cousin ammonium lauryl sulfate "appear to be safe in formulations designed for discontinuous, brief use followed by thorough rinsing from the surface of the skin."
It should be recognized that shampoos represent such brief, discontinuous use products that are thoroughly rinsed, thus clearly minimizing the risk from sodium lauryl sulfate. It should also be recognized that many people shampoo daily, and we really do not know whether a lot of little exposures to sodium lauryl sulfate are dangerous or not.
Given the lack of adequate research and suggestive evidence, however, we believe it might be wise for health-conscious consumers to seek products without sodium lauryl sulfate, especially with regard to young children. Indeed, consumers have the power to choose safe and perhaps even better products without sodium lauryl sulfate.
This may be a very wise choice for another reason. We have found very often the presence of sodium lauryl sulfate in a shampoo formulation is a "marker" for the use of other undesirable ingredients, including formaldehyde-containing preservatives (e.g., imidazolidinyl urea); possible cancer-causing wetting agents (e.g., cocamide DEA); and nitrosamine-forming agents (e.g., triethanolamine). Also, it should be mentioned that in Germany, where there is a concerted effort underway now to label cosmetics and personal care products as certified natural, formulations containing sodium lauryl sulfate, ammonium lauryl sulfate or sodium laureth sulfate cannot be so certified, reports Michael Wrightson, president of Logona Kosmetik.
References
"Bioassay of 1,4-Dioxane for possible carcinogenicity (CAS No. 123-91-1)." National Toxicology Program, TR-80.
Bouillon, C. "Shampoos and hair conditioners." Clinics in Dermatology, 1988; 6(3): 83-92.
Conry, T. Consumer's Guide to Cosmetics. Garden City, NY: Ancor Press / Doubleday, 1980, p. 74.
"Final report on the safety assessment of sodium lauryl sulfate." Journal of the American College of Toxicology; 1983; 2(7).
Sixth Annual Report on Carcinogens, 1991. Summary. U.S. Department of Health and Human Services, Public Health Service. National Institute of Environmental Health Sciences, Research Triangle Park, NC, 1991, pp. 192-195.
"Sodium lauryl sulfate ammonium lauryl sulfate."1996 CIR Compendium. Washington, D.C.: Cosmetic Ingredient Review, 1996, pp. 134-135.
"Toxicology and carcinogenesis studies of coconut oil acid diethanolamine condensate (CAS NO. 68603-42-9) in F344/N rats and B6C3F1 mice (dermal studies)." National Toxicology Program, TR-479.
"Toxicology and carcinogenesis studies of lauric acid diethanolamine condensate (CAS NO. 120-40-1) in F344/N rats and B6C3F1 mice (dermal studies)." National Toxicology Program, TR-480.