Both sodium lauryl sulphate (SLS) and its close relative sodium laureth sulphate (SLES) are commonly used in many soaps, shampoos, detergents, toothpastes and other products that we expect to ‘foam up’. Both chemicals are very effective foaming agents, chemically known as surfactants.
SLS and SLES are esters of sulphuric acid - SLS is also known as ‘sulphuric acid monododecyl ester sodium salt’ however there are over 150 different names by which it is known. In fact, SLES is commonly contaminated with dioxane, a known carcinogen.
Although SLES is somewhat less irritating than sodium laurel sulphate, it cannot be metabolised by the liver and its effects are therefore much longer-lasting. A report published in the Journal of the American College of Toxicology in 1983 showed that concentrations as low as 0.5% could cause irritation and concentrations of 10-30% cause skin corrosion and severe irritation. National Institutes of Health ‘household products directory’ of chemical ingredients lists over 80 products that contain sodium lauryl sulphate. Some soaps have concentrations of up to 30%, which the ACT report called ‘highly irritating and dangerous’.
Shampoos are among the most frequently reported products to the FDA. Reports include eye irritation, scalp irritation, tangled hair, swelling of the hands, face and arms and split, fuzzy hair. The main cause of these problems is sodium lauryl sulphate. So why is a dangerous chemical like sodium lauryl sulphate used in our soaps and shampoos? The answer is simple – it is cheap!
The sodium lauryl sulphate found in our soaps is exactly the same as you would find in a car wash or even a garage, where it is used to degrease car engines! In the same way as it dissolves the grease on car engines, sodium lauryl sulphate also dissolves the oils in your skin which can cause a drying effect. It is also well documented that it denatures skin proteins, which causes not only irritation, but also allows environmental contaminants easier access to the lower, sensitive layers of the skin.
Perhaps most worryingly, SLS is also absorbed into the body from skin application. Once it has been absorbed, one of the main effects of sodium lauryl sulphate 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 dropping male fertility and increasing female cancers such as breast cancer, where oestrogen levels are known to be involved.
Both SLS and SLES are known to have many effects that can potentially be detrimental to health. Among the possible dangers are skin irritation, skin corrosion, hormone imbalance, eye irritation, eye deformities in children, protein denaturing and carcinogenicity.