This article reviews research and information about the effects of Sodium Lauryl Sulfate (SLS) and Sodium Laureth Sulfate (SLES) on people.
More names for SLS
There are additional materials that are similar to SLS in their influence on the skin such as Amonium Lauryl Sulfate (ALS) and Amonium Laureth Sulfate (ALES) which are also used to produce soaps and shampoos. Any reference to SLS in this article is relevant to all the other materials mentioned above and their effects on the skin.
For Soap without SLS click here, For Facial Care without SLS click here Natural Soap bar, SLS Free Shampoo
This article will examine the effects of these substances on the skin from my experience as an engineer in the chemical industry, dealing with employee safety and hazardous materials, and from my years of reading, studying, and treating with homeopathy.
The SLS debate
SLS and SLES are the main ingredient in most soaps and shampoos sold in the world; they are detergents from the petrochemical industry (oil-derived materials). These detergents are manufactured by the reaction of parts of the crude-oil with sulfur. These materials foam even in very hard water. (12)
In recent years, a big debate has developed on the effects of these substances on people. People against SLS use blame it for causing many ailments including cancer and other diseases. Many sites and mails exist on this topic; see for instance footnotes 1 and 2.
On the other hand, there are sites and articles, part of them sponsored by the cosmetic companies, that reject the subject entirely.(3)
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SLS as a skin irritant
In fact, both sides agree that SLS, and the mentioned similar materials, act as an irritant on the skin and that daily exposure can cause skin diseases like dermatitis, asthma of the skin and more. This can be seen in numerous studies and surveys on the subject of SLS / SLES, some from governmental institutes. For example:
SLS is used by cosmetic companies throughout the world as a skin irritating factor. This irritated state of skin enables companies to test the impact of creams and ointments to cure skin irritation (4).
Studies in the 80‘s found that SLS concentrations of 0.5% to 10% cause skin irritation from gentle to moderate and that concentrations from 10% to 30% cause skin burns and acute irritation. Concentrations above 20% were irritating and dangerous. A large part of U.S. soaps examined contained between 10%-30% SLS (see 4,5).
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SLS as dermatitis causing agent
Safety information on SLS, provided by companies marketing the material, state its ability to cause dermatitis following long exposure, even at a low concentration (3%) (6).
If so, how is it that the great majority of the population using soaps, shampoos, toothpastes, creams, ointments and shaving foam based on SLS or SLES, suffer from no skin irritation or other skin problems?
Deviation or differences between various people in the population is the main explanation for this, along with the short exposure time (though daily) to these materials. For an article on the different reaction of different people to different materials, see related article.
Because of the different response of each individual to different materials, the impact of SLS and SLES on people may differ:
1. For part of the population, because of short exposure to these materials, even daily, there is no noticeable effect.
2. Another part of the population may suffer side effects such as a light itch on the head and face, redness of the face and other skin areas after showering, and more.
3. Another part of the population can suffer considerably including skin asthma, skin dermatitis or other severe skin problems.
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Scientific studies on sensitivities to SLS and SLES bring up some central issues:
Skin exposure to SLS, at 1% concentration, for 24 hours caused irritation to skin. Return to normal skin condition resulted only after 4 weeks from exposure. (8)
The skin of younger people (children) is more vulnerable to irritation from exposure to SLS compared with older people (9)
Contact dermatitis due to skin contact with SLS was investigated with concentrations of 0.5%, 1%, and 2% with exposure of one hour (9). Skin irritation and damage to the skin formed including changes in permeability.
Comparison of skin damage from SLS / SLES and natural oil soaps shows significantly more severe injury when soaps based on SLS are used (10).
SLS has been linked to problems of drying the salivary glands in the mouth and damaging them so should be avoided in people with similar problems (11).
From my own experience, I hear and see the changes, on a daily basis, experienced by people who switched to the natural soaps we produce. Examples:
Children with skin asthma or atopic dermatitis reduced phenomenon to a negligible level or entirely through regular use of liquid soaps manufactured by us.
An elderly woman who suffered from itching skin for many years following radiation, ceased to suffer from the problem after use of liquid soaps manufactured by us.
Older women who suffered from scalp itching ceased to suffer from this phenomenon after switching over to the virgin olive oil natural shampoo bar manufactured by us. And many more examples of dandruff prevention and hair loss reduction.
SLS and SLES are substances that can irritate skin and cause other problems for part of the population.
Soaps, shampoos, toothpastes, and other products that contain these substances can cause skin problems or worsen existing skin problems.
People with skin injuries, itching, sensitivities and other phenomenon should check the impact of natural soaps on these problems for a period of several weeks.
Ido Mashal BA in biology. B. Sc – Chem. Eng, M.Sc. – Mater. Eng. (Technion)
3. Legends components – Http://www.melaleuca.com/wc/pdf/Ingredient_Myths.pdf
4. Report of the Government of Australia (2007) – Report of the Government of Australia
5. Reference to Israel‘s Ministry of Health (pharmaceutical division) – Http://www.health.gov.il/pages/default.asp?pageid=977&parentid=160&catid=38&maincat=11
6. MSDS Safety Information for – SLS concentration of 3% — MSDS SLS.pdf
8. Lee JY, et al. Acute Irritant contact dermatitis: recovery time in man, contact dermatitis. 1997 jun 36 (6): 285-90, —
9. Marrakchi S, Maibach HI, Sodium Lauryl sulfate-induced irritation in the human face: regional and age-related differences Skin Pharmacol Physiol. 2006; 19 (3) :177-80 —
10. Wilhelm KP, Freitag G, Wolff HH, Surfactant-i Nduced skin irritation and skin repair: evaluation of a Cumulative human irritation model by Noninvasive techniques, J Am Acad Dermatol. 1994 Dec; 31 (6) :981-7
11. Jensen JL, Barkvoll P. Clinical Implications of the dry mouth. Oral Mucosal diseases. Ann NY Acad Sci. 1998 Apr 15; 842:156-62
12. Encyclopedia Britannica (value detergents)