Are sodium lauryl sulfate (SLS) and sodium laureth sulfate
(SLES) serious problems in cosmetics? I have received
more emails and letters than I care to count about this
concern. I believe that this entire mania was generated
by several Neways 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 the Research to Prevent Blindness conference.
While the report on animal models extrapolates concerns
about the use SLS, it draws no hard conclusions stating
that the amount of SLS used was 10% greater than that
used in shampoos and 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."
Resulting mass emails continued for some time, carrying
on the SLS and SLES myth with a slightly different bent.
Yet, according to Health Canada, in a press release, February
12, 1999 (http://www.hc-sc.gc.ca/), "A letter has
been circulating the Internet which claims that there
is a link between cancer and sodium laureth (or lauryl)
sulphate (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 email 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
sulphate 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. Emails 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 (but sodium laureth
sulfate is not because it has a different chemical structure
that results in a gentler cleansing agent), and it's considered
a standing comparison substance for measuring skin irritancy
of other ingredients. 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 irritating 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!