You may not think of them as an essential part of your
skin care and cosmetics, but without question skin-care
and cosmetics products need preservatives. This is especially
true for products that contain plant extracts—just think
about how long a head of lettuce lasts in your refrigerator.
Whether it is a cleanser, lotion, toner, blush, foundation,
or mascara, without preservatives these everyday items
would become overloaded with bacteria, mold, and fungus,
making them harmful to skin, eyes, and mucous membranes.
However, as necessary as preservatives are to the safety
of cosmetics, they've had their share of woes over the
years. For example, back in the early '90s, it was discovered
that when formaldehyde-releasing preservatives (such as
2-bromo-2-nitropane 1-3 diol or DMDM hydantoin) are combined
with amines (such as triethanolamine), something called
nitrosamine forms, and nitrosamine (in its various forms)
is, in fact, carcinogenic. This problem was viewed as
inconsequential for cosmetics, however, because the amount
of preservatives used in cosmetics is minute. No test
has shown it to cause problems for people applying makeup
or using skin care. Studies relating to carcinogenic properties
of nitrosamine were done feeding it orally to laboratory
rats. Still, it is not a pleasant thought to associate
a "carcinogen" with your cosmetics in any way,
shape, or form. As a result, and despite their effectiveness,
formaldehyde-based preservatives are not as popular as
they once were.
Another group of preservatives (parabens) is now in a
predicament similar to that of formaldehyde, and this
has become a common subject for questions from my readers.
These parabens may come in the form of butylparaben, ethylparaben,
isobutylparaben, methylparaben, or propylparaben, and
have been linked distantly (meaning in limited studies
and with only a handful of subjects) to breast cancer
due to their weak estrogenic activity and their presence
in breast-cancer tumors. But even from a distance that
has some people worried, especially considering that,
by some estimates, more than 90% of all cosmetics products
contain one or more parabens. In fact, parabens are the
most widely used group of cosmetics preservatives in the
world because of their efficacy, low risk of irritation,
and stability.
What started the concern about parabens was a study published
in the Journal of Steroid Biochemistry and Molecular Biology
(January 2002, pages 49–60) that evaluated the estrogenic
activity of parabens in human breast-cancer cells. The
very technical findings of the study, which involved both
oral administration and injection into rat skin, did show
evidence of a weak estrogenic effect on cells in a way
that could be problematic for binding to receptor sites
that may cause proliferation of MCF-7 breast-cancer cells.
Subsequent research identified parabens in human breast-tumor
samples supplied by 20 patients. This study was concerned
primarily with the use of deodorants that contained parabens
rather than with cosmetics in general, but it has been
extrapolated to the cosmetics industry as a whole, prompting
many consumers to check the ingredient lists of the products
they're using. What all the researchers who are studying
this issue agree on is that the information to date is
hardly conclusive and at best vague; parabens require
more study. For example, the presence of parabens in human
breast tumors doesn't mean they caused the tumors in the
first place. It is also unclear whether cosmetics are
a problem, or just underarm deodorants, as some researchers
have hypothesized (Sources: Journal of Applied Toxicology,
January–February 2004, pages 1–4, September–October 2003,
pages 285–288, and March–April 2003, pages 89–59; and
Journal of the National Cancer Institute, August 2003,
pages 1106–1118).
It is also important to realize that parabens are used
in food products as well (Source: Food Chemistry and Toxicology,
October 2002, pages 1335–1373), which could very well
be the source. As yet, no one has any idea (or has evaluated)
whether it is the consumption of parabens or their application
to the skin that is responsible for their presence in
human tissue. And no one knows what the presence of parabens
in human tissue means.
Does this mean you should stop buying products that contain
parabens? That's a good question, but the answer isn't
simple or conclusive at this time, even by the standards
of the study itself. Clearly it is a serious issue, and
the FDA is conducting its own research to determine what
this means for human health (Source: The Endocrine Disruptor
Knowledge Base (EDKB), http://edkb.fda.gov/index.html).
As a point of reference, and just to keep the concern
over parabens in perspective, it is important to realize
that parabens are hardly the only substances that have
estrogenic effects on the body.
The issue is that any source of estrogen, including the
estrogen our bodies produce or the types associated with
plant extracts, may bind to receptor sites on cells, either
strongly or weakly. This can either stimulate the receptor
to imitate the effect of our own estrogen in a positive
way, or it can generate an abnormal estrogen response.
It is possible that a weak plant estrogen can help the
body, but it is also possible for a strong plant estrogen
to make matters worse. For example, there is research
showing that coffee is a problem for fibrocystic breast
disease, possibly because coffee exerts estrogenic effects
on breast cells (Sources: Journal of the American Medical
Women's Association, Spring 2002, pages 85–90; American
Journal of Epidemiology, October 1996, pages 642–644;
and Annals of the New York Academy of Science, March 2002,
pages 11–22).
A study conducted at the Department of Obstetrics and
Gynecology at Baylor College of Medicine in Houston, Texas,
investigated the estrogenic effects of licorice root,
black cohosh, dong quai, and ginseng "on cell proliferation
of MCF-7 cells, a human breast cancer cell line... ."
The results showed that "Dong quai and ginseng both
significantly induced the growth of MCF-7 cells by 16-
and 27-fold, respectively, over that of untreated control
cells, while black cohosh and licorice root did not"
(Source: Menopause, March–April, 2002, pages 145–150).
A more recent study concluded that “Commercially available
products containing soy, red clover, and herbal combinations
induced an increase in the MCF-7 [breast cancer] proliferation
rates, indicating an estrogen-antagonistic activity. ..."
(Source: Menopause, May–June 2004, pages 281–289).
I wish there were an easy answer to this question, but
there isn't. I can't even tell you to avoid products that
contain parabens because there would almost be no products
to recommend. Even product lines that make claims (albeit
exaggerated) about their "natural" content often
use parabens as the preservative system because they are
"food-grade" substances. It's interesting to
note that parabens actually do have a "natural"
origin. Parabens are formed from an acid (p-hydroxy-benzoic
acid) found in raspberries and blackberries (Source: Cosmetics
& Toiletries, January 2005, page 22). So much for
the widely held belief that natural ingredients are the
only answer for skin-care products!
One more point, about the risk of breast cancer related
to underarm deodorant. In October 2002, a study conducted
at the Seattle-based Fred Hutchinson Cancer Research Center,
published in the Journal of the National Cancer Institute,
looked at the issue of underarm deodorant use and breast
cancer. The study compared the use of underarm deodorant
in 810 women who had been diagnosed with breast cancer,
and 793 women who were not affected by the disease. When
the two groups were compared, researchers found no evidence
of an increased risk of breast cancer linked to using
antiperspirant or deodorant, or using antiperspirant or
deodorant after shaving with a traditional razor blade.
In short, the researchers believed their study proved
there was no link between underarm deodorants and breast
cancer risk.