Are sodium lauryl sulfate (SLS) and sodium laureth sulfate (SLES) serious problems in cosmetics? I have received more e-mails and letters than I care to count about this concern.
I believe that this entire mania was generated by several Neways members’ web sites, and has been carried over as if it were fact into other so-called “all natural” cosmetics lines.
It seems that most of this issue is based on the incorrect reporting about a study at the Medical College of Georgia. As a reminder, here is what is being quoted: “A study from the Medical College of Georgia indicates that SLS is a systemic, and can penetrate and be retained in the eye, brain, heart, liver, etc., with potentially harmful long-term effects. It could retard healing and cause cataracts in adults, and can keep children’s eyes from developing properly.” This is supposedly quoted from a report given to a Research to Prevent Blindness conference. While the report on animal models extrapolates concerns about the use of SLS, it draws no hard conclusions, stating the amount of SLS used was 10% greater than that used in shampoos and that the research was done on animals, not people. The doctor who conducted the study and delivered the final report is Dr. Keith Green, Regents Professor of Ophthalmology at the Medical College of Georgia, who received his doctorate of science from St. Andrews University in Scotland. I had an opportunity to talk with Dr. Green, who stated that he was completely embarrassed by all this. He told me in a telephone interview back in 1997 that his “work was completely misquoted. There is no part of my study that indicated any [eye] development or cataract problems from SLS or SLES and the body does not retain those ingredients at all. We did not even look at the issue of children, so that conclusion is completely false because it never existed. The Neways people took my research completely out of context and probably never read the study at all.” He continued in a perturbed voice, saying, “The statement like ‘SLS is a systemic’ has no meaning. No ingredient can be a systemic unless you drink the stuff and that’s not what we did with it. Another incredible comment was that my study was ‘clinical,’ meaning I tested the substance on people, [but] these were strictly animal tests. Furthermore, the eyes showed no irritation with the 10-dilution substance used! If anything, the animal studies indicated no risk of irritation whatsoever!” That lack of outcome is in fact why, as of 1987, Green no longer pursued this research. When I asked if anyone has done any follow-up studies looking at SLS and SLES in this regard, Dr. Green said, “No one has done this because the findings were so insignificant.”
Yet the resulting mass e-mails continued for some time, carrying on the SLS and SLES myth with a slightly different bent. According to Health Canada, in a press release dated February 12, 1999 (www. hc-sc. gc. ca/), “A letter has been circulating [on] the Internet which claims that there is a link between cancer and sodium laureth (or lauryl) sulfate (SLS), an ingredient used in [cosmetics]. Health Canada has looked into the matter and has found no scientific evidence to suggest that SLS causes cancer. It has a history of safe use in Canada. Upon further investigation, it was discovered that this e-mail warning is a hoax. The letter is signed by a person at the University of Pennsylvania Health System and includes a phone number. Health Canada contacted the University of Pennsylvania Health System and found that it is not the author of the sodium laureth sulfate warning and does not endorse any link between SLS and cancer. Health Canada considers SLS safe for use in cosmetics. Therefore, you can continue to use cosmetics containing SLS without worry.”
Further, according to the American Cancer Society’s Web site, “Contrary to popular rumors on the Internet, Sodium Lauryl Sulfate (SLS) and Sodium Laureth Sulfate (SLES) do not cause cancer. E-mails have been flying through cyberspace claiming SLS [and SLES] causes cancer… and is proven to cause cancer. … [Yet] A search of recognized medical journals yielded no published articles relating this substance to cancer in humans.”
That’s not to say that sodium lauryl sulfate isn’t a potent skin irritant, because it is. That’s why it’s considered a standard comparison substance for measuring skin irritancy of other ingredients. Thus in scientific studies, when they want to establish whether or not an ingredient is problematic for skin, they compare its effect to the results of SLS. In amounts of 2% to 5% it can cause allergic or sensitizing reactions in lots of people (Sources: European Journal of Dermatology, September-October 2001, pages 416-419; American Journal of Contact Dermatitis, March 2001, pages 28-32). But irritancy is not the same as the other dire, erroneous warnings floating around the Web about this ingredient!