About Sodium Lauryl Sulfate, or SLS


Many common everyday products contain a controversial ingredient called Sodium Lauryl Sulfate, or SLS. These products range from soaps to stain removers to suntan lotion. We at Capital Cleaning feel it's important to stay informed and so we are providing the following article for your information. Do not believe that just because a product is allowed on a store shelf that it is safe, or because it is labeled as "natural" that it is free of potentially harmful ingredients. Many products labeled as "natural" use SLS.

So what's the truth about SLS?
SLS is derived from coconut oil. However, it is made by adding sulfuric acid (from petroleum) followed by neutralization with sodium carbonate (a natural mineral). Perhaps most worrisome is the ethoxylation process which is what makes SLS less abrasive and creates enhanced foaming properties. When SLS is ethoxylated, it forms Sodium Laureth Sulphate (aka sodium lauryl ether sulfate, or SLES). The problem is, the extremely harmful compound 1,4-dioxane may be created during the ethoxylation process, contaminating the product. 1,4-dioxane was one of the principal components of the chemical defoliant Agent Orange, used by the Americans during the Vietnam War to strip off the jungle canopy to reveal the enemy. 1,4-dioxane is a hormonal disrupter believed to be the chief agent implicated in the host of cancers suffered by Vietnam military personnel after the war. It is also an oestrogen mimic thought to increase the chances of breast cancer.  It also lowers male sperm counts.

Products commonly found to contain SLS:
Soaps  -  Shampoos  -  Bubble-baths  -  Toothpaste  -  Mascara
Liquid Hand soap  -  Dish soap  -  Laundry detergent  -  Body wash
Children's soaps  -  Shampoos  -  Stain Remover  -  Carpet Cleaner
Fabric glue  -  Shave cream  -  Mouthwash  -  Skin cleanser
Moisture lotion  -  Moisturizer  -  Sun Lotion

Reasons to Avoid SLS

  • It emits toxic fumes when heated. Toxic sodium oxides and sulfur oxides are released when SLS is heated.
  • It helps other chemicals get into your body. SLS is a penetration enhancer, meaning that its molecules are so small they're able to cross the membranes of your body's cells. Once cells are compromised, they become more vulnerable.
  • One of the main effects of SLS is to mimic the activity of the hormone oestrogen. This has many health implications and may be responsible for a variety of health problems from PMS and menopausal symptoms to increasing cancers where oestrogen levels are known to be involved, including breast cancer.
  • It's an eye irritant. It was shown to cause cataracts in adults, and is proven to inhibit the proper formation of eyes in small children.
  • Long-term permeation of the body's tissues. A study from the University of Georgia Medicine showed that SLS had the power to permeate the eyes, brain, heart, and liver.
  • It pollutes our groundwater. It is toxic to fish and other aquatic animals (at 7ppm) and has the potential for bioaccumulation - meaning it accumulates in the bodies of the fish. It also is undetected in many municipal water filters, getting into the tap water that you drink.
  • It is actually a pesticide and herbicide. It is commonly used to kill plants and insects. Makers of SLS petitioned to have SLS listed as an approved pesticide for organic farming. The application was denied because of its polluting properties and environmental damage.
  • It has corrosive properties. According to the American College of Toxicity, this includes corrosion of the fats and proteins that make up skin and muscle.
  • The manufacturing process is highly polluting, emitting cancer-causing volatile organic compounds, sulfur compounds, and air particulates.
  • It is a known skin irritant. When cosmetic companies need to test the healing properties of a lotion, they need to irritate the skin first. What do they use to do this? SLS. If you have dandruff, dermatitis, canker sores, or other irritated tissues or skin, it could be due to SLS.
  • SLS is not a recognized carcinogen itself, but when mixed with triethanolamine (or T.E.A), carcinogenic substances called nitrosames can form and be released.

Final Report on the Safety Assessment of Sodium Lauryl Sulfate

Volume 2. Number 7, 1983

Sodium Lauryl Sulfate is an anionic surfactant used in cosmetics and industrial chemicals as a cleansing agent. In absorption, metabolism and excretion studies Sodium Lauryl Sulfate had a degenerative effect on the cell membranes because of its protein denaturing properties. High levels of skin penetration may occur at even low use concentration.

Sodium Lauryl Sulfate had an LD 50 (Lethal Dose for 50% of the animals tested) of 0.8 to 110 g/kg in rats. A formulation containing 15% caused depression, labored breathing, diarrhea and death in 4 out of 20 animals.

In acute ocular tests, 10% Sodium Lauryl Sulfate caused corneal damage to the rabbits’ eyes if not irrigated or irrigation was delayed. A Draize test of a product containing 5.1% Sodium Lauryl Sulfate caused mild irritation and products containing 21% were severely irritated with no rinse and mildly irritated when rinsed. Acute animal skin irritation studies of 0.5% to 10% Sodium Lauryl Sulfate cause slight to moderate irritation. Applications of 10% to 30% caused skin corrosion and severe irritation. Solutions above 20% were highly irritating and dangerous. One percent and 5% Sodium Lauryl Sulfate produced a significant number of comedones when applied to the pinna of albino rabbits.

A chronic oral feeding study in rats of 0.25%, 0.5% and 1.0% Sodium Lauryl Sulfate in the diet for two years produced no observable abnormalities except for moderate to severe dermal effects. In mutagenesis studies, rats fed 1.13% and 0.56% Sodium Lauryl Sulfate in the diet for 90 days produced no more chromosomal aberrations or clastogenic effects than did a normal diet.

Sodium Lauryl Sulfate was tested for human skin irritation in concentrations ranging from 0.1% to 10%. Open patches were less irritating than closed patches, and irritation increased directly with concentration. For prolonged contact with skin, concentration should not exceed 1%.


Sodium Lauryl Sulfate, an anionic surfactant, is prepared by the sulfation of commercially available lauryl alcohol form coconut our, with either sulfur trioxide or chlorosulfonic acid. The product of the reaction is then neutralized with aqueous sodium hydroxide (lye). The abbreviated symbol for Sodium Lauryl Sulfate is used around the world in clinical studies as a skin irritant. SLS is the universal standard, by which a measured percentage is evaluated to promote a given level of irritation and reaction. By this SLS standard level or irritation, it is then possible to evaluate the healing or modifying characteristics of any ingredient or formula used on the SLS irritated skin.

Carcinogenic nitrates 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. Tests show permanent eye damage in young animals from skin contact in non eye areas. Studies at Georgia Medical College 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.

Other studies have indicated that Sodium Lauryl Sulfate enters and maintains residual levels in the heart, the liver, the lungs and the brain from skin contact. This poses question of it being a serious potential health threat to its use in shampoos, cleansers, and tooth pastes.

Still other research has indicated SLS may be damaging to the immune system, especially within the skin. Skin layers may separate and inflame due to its protein denaturing properties.
A higher foaming and slightly less irritating modification of Sodium Lauryl Sulfate can he manufactured by ethoxylation of the surfactant. The modified compound becomes know as Sodium Lauryl Ether Sulfate. The cosmetic name is Sodium Laureth Sulfate with an abbreviated symbol of SLES.