The AJT report states that "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."

Both Sodium Laureth Sulfate (SLES) and its close relative Sodium Lauryl Sulfate (SLS) 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.

Unfortunately, both sodium laureth sulfate and its cousin are also very dangerous, highly irritating chemicals. Far from giving "healthy shining hair" and "beautiful skin", soaps and shampoos containing sodium laureth sulfate can lead to direct damage to the hair follicle, skin damage, permanent eye damage in children and even liver toxicity.

Although sodium laureth sulfate is somewhat less irritating than SLS, it cannot be metabolized by the liver and its effects are therefore much longer-lasting. This not only means it stays in the body tissues for longer, but much more precious energy is used getting rid of it.
A report published in the Journal of The American College of Toxicology in 1983 showed that concentrations of SLS as low as 0.5% could cause irritation and concentrations of 10-30% caused skin corrosion and severe irritation. National Institutes of Health "Household Products Directory" of chemical ingredients lists over 80 products that contain SLS and SLES. 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 and fuzzy hair. This is highly characteristic of sodium laureth sulfate and almost definitely directly related to its use.

Skin Irritation

SLS is used routinely in clinical studies. This may suggest a level of comfort, however, the way in which it is used is disturbing. Despite being the number one active ingredient in virtually all soaps, shampoos and cleansers, the sole purpose of using SLS in clinical studies is to cause skin irritation that can then be used to identify the properties of other chemicals!

Amazing isn't it? For years, we have been applying known irritants to our skin on a daily basis. To quote the ACT report "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 of irritation, it is then possible to evaluate the healing or modifying characteristics of any ingredient or formula used on the SLS irritated skin."

Most worryingly, irritation has been shown to occur at concentrations of 0.5%, which is 1/60th the concentration found in some hand soaps. Caveat emptor!

Hormone Imbalance

In the last 100 years or so, many new health problems have come to light. These include PMS / PMT, the so-called "menopausal symptoms" which never used to exist, and more recently a massive drop in male fertility which threatens our continued existence in many western countries. SLS is most likely a major contributor to all of these problems due to its oestrogen mimicking activity.

Oestrogen is a hormone found quite normally in both men and women. Like all other hormones, it's circulating levels are rigidly controlled by the glands of the body due to the potent effect of its presence on virtually all cells. Not only does SLS irritate the skin, it is also absorbed through the skin (high levels of skin penetration may occur at even low concentration). Once in the body, the SLS molecule attaches to oestrogen receptors, mimicking the effects of the hormone in various body systems.

The result is hormonal chaos. The body can no longer control it's own oestrogen levels (or at least, what it sees as it's own oestrogen levels - it can't tell the difference between endogenous oestrogen and SLS) and therefore loses control of many normal endocrine (hormonal) functions.

In men, whose oestrogen levels are normally extremely low, this massive increase causes breast enlargement, reduction of male hormone levels and a massive drop in both sperm count and sperm motility (ability of the sperm to fertilize an ovum). Gender confusion may also be related to SLS levels, either in the male himself or in his mother during pregnancy.

In women, the reproductive system, which is totally controlled by oestrogen and progesterone, goes haywire. Rapidly shifting oestrogen levels and their effect on progesterone levels mean that the body is totally confused, leading to menstrual problems, menopausal symptoms and potentially infertility. Because this subject is so important, we have devoted a whole section of this site to women’s health.

Eye Irritation / eye deformities in children

Have you ever got shampoo in your eyes? Yes, so have I - not pleasant is it? However, the potential effects of SLS on the eye are much more worrying. In animal studies, 10% SLS caused acute corneal damage. However, it is not just direct eye contact that is the problem. According to the American College of Toxicology, "tests show permanent eye damage in young animals from skin contact in non-eye areas".

In other words, because SLS is absorbed through the skin, it can cause PERMANENT eye damage WITHOUT ever directly coming into contact with your eyes. As a result, you would expect that children’s products would be SLS-free. Unfortunately not, most children’s shampoos contain just as much SLS as those for adults.

Thankfully, alternatives DO exist, though you would be hard-pressed to find them in your local chemist or supermarket.

Protein Denaturing

Our cells are made from protein. The development of those cells is strictly regulated by the reproductive processes that are continually at work removing damaged and old cells and replacing them with healthy new ones. Virtually every cell in the body is replaced at least every 7 years.

SLS exerts its effects on proteins by forming a chemical bridge between the fat-soluble and water-soluble parts of the protein molecule. This disrupts the hydrophobic forces needed to maintain the protein structure and the molecule collapses, rendering it useless. This effect is usually irreversible.

The result of this is two-fold. Firstly, existing proteins are damaged, leading to an increase in the amount of healing required by the body. Secondly, new proteins can be damaged and cells disrupted while they are under construction. It is exactly this type of activity that can lead to the early stages of skin cancer.

In the skin, this process can be so severe, that skin layers may separate and inflame due to its (SLS's) protein denaturing properties.

Carcenogenicity

Quite apart from it's potential to cause pre-cancerous conditions by denaturing proteins, the oestrogen mimicking effects of SLS also offers massive potential to cause cancer. It is known that many cancers, not least breast and ovarian cancer are directly related to oestrogen levels, in fact some cancer cells actually secrete their own oestrogen, which contributes to the growth of the tumor.

Clearly, by disrupting normal oestrogen levels AND by causing similar effects at a cellular level as endogenous oestrogen, SLS exhibits MASSIVE potential to both cause and worsen cancerous states. The incidence of breast cancer has increased several-fold in the last 50 years, both in women and in men. Currently, according to the American Cancer Society, men account for approximately 1% of all breast cancer cases. This subject is discussed in more detail in our women’s health section.

There is also a third way by which SLS can potentially cause cancer. 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 (many shampoos contain nitrate compounds). A single shampooing can produce more cancer-causing nitrates in the body than eating a pound of bacon, which is VERY high in nitrates!

Whether it is by these means or not, SLS in a known mutagen - it is capable of damaging the genetic material found every cell in your body. As mutagenicity has been strongly linked to cancer, this is a major concern.