Sodium lauryl Sulfate
Sodium lauryl sulfate (SLS) is the sodium salt of lauryl sulfate, and it’s sometimes called sodium laurilsulfate or sodium dodecyl sulfate. It’s obtained from a reaction between lauryl alcohol and sulfur trioxide, producing hydrogen lauryl sulfate which is then neutralized to produce SLS using sodium bicarbonate. In spite of the neutralization, the resulting SLS product is harsh. For this reason, products containing SLS should be used discontinuously and briefly, and thoroughly rinsed from the skin.
SLS is inexpensive yet a very effective chemical. For these reasons, it’s included in a many household and industrial cleansing agents, including engine degreasers, industrial strength detergents, dishwashing and laundry detergents, and spray cleaners. It’s used as an anionic surfactant, emulsifier, and a foaming and denaturing agent in antiperspirants, shampoos, mouthwashes, body washes, detergents, toothpastes, and several cosmetic and personal care products.
There’s little evidence to suggest SLS causes cancer. As such, it hasn’t been classified as carcinogenic by relevant agencies such as the International Agency for Research on Cancer (IARC), American Cancer Council, US Occupational Health and Safety Administration, US Environmental Protection Agency (EPA), US National Toxicology Program, and the European Union. The only worrying issue, however, is that during preparation, SLS can be contaminated by 1,4-dioxane, a proven carcinogen, which can in turn contaminate the product you’re using (see steareths, polysorbates, phenoxyethanol, PEG, and ammonium laureth sulfate for more information about 1,4-dioxane).
Even though SLS isn’t considered carcinogenic, different concentrations have been found to pose danger to human health. Prominent health and wellbeing physicians, including Dr. Mercola, advise us to be wary of using SLS because it:
- causes irritation of the skin, scalp, and gums even at exposure to just 1% concentration
- markedly increases acnes and blackheads
- can increase moisture loss from our skin, causing inflammation
- can corrode the protein and fat constituents of our skin and muscle
- irritates the eyes, impairs the proper formation of eyes in children, damages the cornea, and causes cataracts in adults
- is a penetrating enhancer, i.e. it facilitates the absorption of harmful chemicals into our body
- mimics the activity of estrogen which can result in health risks related to PMS, menopause, and cancer
- promotes the degeneration of cell membranes
- has the ability to penetrate our skin and accumulate and damage the heart, liver, brain, lungs and other vital organs
- promotes hair loss
- has pesticidal and herbicidal properties
- can lead to breathing difficulties, diarrhea, depression, and death
- has been linked with nitrosamines, a group of toxic chemicals that induces tumor growth and causes several cancers in humans and a variety of animals, e.g. esophageal, bladder, and gastric cancer. The IARC and US EPA classify nitrosamines as carcinogenic. Nitrosamines promote the body’s uptake of carcinogenic nitrites and nitrates, and have been linked with Parkinson’s, type 2 diabetes, and Alzheimer’s
- is toxic to aquatic environments, and may accumulate in the bodies of inhabiting organisms.
If you find ammonium lauryl sulfate, potassium dodecyl sulfate, and potassium lauryl sulfate listed on the product you’re using, just be aware that they perform similar functions as SLS. They can just be as harmful.