Breast cancer has been on the rise for over half a century. Only 5-10% of breast cancer is genetic, leaving up to 90% from the environment and lifestyle.  Studies indicate that deodorants / antiperspirants play a major role in the increase of breast cancer cases. This article will talk about the parabens that occur in deodorants / antiperspirants and the role it plays in the growth of breast cancer tumors.
I recommend you read the previous article in this series before continuing. A few concepts that are used in this article are explained in ‘Antiperspirants – Aluminum & Breast Cancer‘.
What are Parabens?
Parabens are used as preservatives in many thousands of cosmetic, food and pharmaceutical products to which we are exposed. Parabens are permitted as preservatives in food up to 0.1%. In cosmetics, parabens are permitted in concentrations of up to 1%. A 1995 survey of 215 cosmetic products found that parabens were used in 99% of leave-on products and in 77% of rinse-off cosmetics. 
It is safe to say that if you use cosmetic products, you are using products that contain parabens.
Parabens have been considered as safe for many years, however this has changed in the last few decades. Currently, there is evidence of the endocrine (hormonal system), reproductive and developmental effects of parabens. 
Parabens are absorbed through the skin and can then be stored in the body. Once parabens are in the body it affects the hormonal system by mimicking oestrogen, the hormone that promotes cell growth. The promotion of cell growth link parabens with cancer, and in the context of this article, breast cancer. Parabens have actually been detected in human breast cancer tumors, as Darbre stated in 2004:
[The] detection [of parabens] in human breast tumours is of concern since parabens have been shown to be able to mimic the action of the female hormone oestrogen 
oestrogen can drive the growth of human breast tumours. It would therefore seem especially prudent to consider whether parabens should continue to be used in such a wide range of cosmetics applied to the breast area including deodorants. 
The link between parabens and breast cancer might seem outlandish to you: After all, parabens are used in so many cosmetic products, it has to be safe. The FDA would never allow that to happen – right?
The FDA uses the Cosmetic Ingredient Review (CIR) for its safety assessment of parabens (isobutylparaben and isopropylparaben). The safety assessment of the CIR Expert Panel was published in 1995, before evidence of the endocrine (hormonal system), reproductive and developmental effects of parabens had been reported. 
Furthermore, due to the lack of available data on parabens (isobutylparaben and isopropylparaben), the CIR used data from related compounds (methyl-, ethyl-, propyl- and butylparaben) instead. 
This article will delve deeper into the relationship between parabens, deodorants / antiperspirants and breast cancer. However, first a short section on what to look for on the product labels, and then a dive into parabens and deodorants / antiperspirants.
What to Look for on the Label
All items listed below are parabens, check your product labels for these terms:
- Methylparaben (E218)
- Ethylparaben (E214)
- Propylparaben (E216)
- Benzyl-parahydroxybenzoic acid
- Methyl-parahydroxybenzoic acid
- Ethyl-parahydroxybenzoic acid
- Propyl-parahydroxybenzoic acid
- Butyl-parahydroxybenzoic acid
- Parahydroxybenzoic acid
Do not assume that products that are labeled ‘natural’ or ‘organic’ do not contain parabens. Always check the label, you’ll often find the parabens on small print at the bottom of the back label. 
As mentioned, the great concern with parabens is that it mimics oestogens. The next section will explain what this means to your body.
What is ‘Oestrogenic’?
‘Oestrogenic’ means ‘Having an action similar to that of an oestrogen’.
So what are the actions of oestrogen? A highly recommended resource on the subject of oestrogen / estrogen is the late Dr. John R. Lee.
Dr Lee describes oestrogen as follows:
Oestrogen is the hormone that is responsible for the changes that take place in a girl as she reaches puberty. Under the influence of oestrogen her sexual organs mature and she grows breasts, female curves and pubic hair. From then on, for the first half of every month, oestrogen stimulates and builds up the lining of the womb in anticipation of a fertilised egg. It also encourages the growth and lubrication of the lining of the vagina.
This stimulating effect of oestrogen helps to explain why, in excess, it is toxic. Oestrogen stimulates breast tissue: it can encourage the development of fibrocystic breasts, and supplementing with oestrogen is known to increase a woman’s risk of breast cancer. It also stimulates the lining of the womb, the endometrium, increasing the risk of endometrial cancer, and encouraging the growth of fibroids.
This quote talks about supplementing estrogen in the context of Hormone Replacement Therapy (HRT). However, the results are the same when the oestrogen levels rise due to parabens:
Breast cancer is a multifactoral disease but one area of clear agreement is the role of oestrogen in the growth and development of the cancer, and clinical treatments continue to use oestrogen blockade and suppression 
It is important to understand that women need the oestrogen that is naturally produced by the body. Women also produces another hormone call progesterone. The body tries to maintain a delicate balance between oestrogen and progesterone. The oestrogen produced by your body is not dangerous, as long as there is a hormonal balance between the oestrogen and the progesterone. An excess of oestrogen causes hormonal imbalance. Hormonal imbalance can cause many health issues, this article will focus on the growth promoting properties of excess oestrogen.
In our industrialized world, we are exposed to environmental oestrogen, or ‘xenoestrogens’. Xenoestrogens are man-made compounds, that are different from naturally occurring oestrogens, but mimic the effects of oestrogens. 
Parabens are xenoestrogens, and so are many other compounds we are exposed to on a daily basis. Consequently, parabens are not the only environmental oestrogens we are exposed to, but the big difference with other xenoestrogens is that we apply parabens to the skin through deodorants / antiperspirants and other cosmetic products.
In short: in the context of this article, Oestrogenic means the growth promoting activity of oestrogen. The growth promoting behavior of excess oestrogen is a well known and accepted as a contributor in forming breast cancer.
Parabens in Deodorants and Antiperspirants
Parabens can be ingested through food, absorbed through the skin and inhaled. This article will focus on absorption through the skin, and more specifically, absorption through the underarm.
Parabens have been considered to be safe due to the limited effects it has on the human body when it is ingested through foods. When you ingest parabens, it does not seem to have the oestrogenic activity that parabens have when absorbed through the skin. The oral route takes care of parabens, which is reassuring for their food use. 
However, parabens do have estrogenic effects when applied to the skin. There are two scenario’s when applying a substance that contains parabens to you skin: the rinse off applications and the stay-on applications.
When your face wash or soap contains parabens, you are exposed for a short period of time. I try to avoid parabens altogether, but it seems logical to me that the rinse off scenario is safer than the stay-on scenario.
When you apply deodorant / antiperspirant, it stays on your skin throughout the day. Any harmful substance that can be absorbed through the skin, has ample time to get absorbed. Most of us apply deodorants / antiperspirants at least once per day. As a result, many of us are exposed to parabens continually, 24/7, every day.
Parabens ingested through food have a limited effect on the human body partly due to the ingestion system. However, parabens absorbed through the skin are able to stay intact and accumulate in the body.
Parabens and Breast Cancer
In an article titled ‘Underarm Cosmetics and Breast Cancer’  Darbre explains that two steps are needed to cause cancer:
1 – DNA has to be damaged, resulting in damaged cells.
2 – Growth promotion of these damaged cells.
The aluminum in antiperspirants is one of the substances that takes care of the first step.
Parabens promote the growth of damaged cells: as stated, parabens mimic the action of the female hormone oestrogen.  And the role of oestrogen in the growth of breast cancer has been well established.
The relationship between parabens in deodorants / antiperspirants and breast cancer has been established in several studies, in these studies several arguments have been put forward that all point in the same direction. This section will give a quick overview of the following four points:
- The location of breast cancer
- The relationship between deodorant / antiperspirant sales and the incidence of breast cancer
- Parabens found in breast tumors
- Oestrogenic activity of parabens
The Location of Breast Cancer
The location where we apply deodorants / antiperspirants is especially sensitive for women: the armpit, right next to the breast.
As explained in more detail in ‘Antiperspirants – Aluminum & Breast Cancer‘, the majority of breast cancers occur in the part of the breast that is the closest to the armpit, where we apply antiperspirants and deodorants. This location is referred to as the Upper Outer Quadrant (UOQ).  Furthermore, the percentage of breast cancers that occur in the UOQ has been increasing from 31% in 1926, to 60.7% in 1994. 
The Relationship Between Sales and the Incidence of Breast Cancer
Below you can see that there seems to be a relationship between the increase in deodorant / antiperspirant sales, and the increased occurrence of breast cancer. This sales increase also corresponds with the increased percentage of breast cancers that occur in the UOQ.
USA breast cancer incidence and antiperspirant/deodorant sales (Roush et al., 1987; SEER Cancer Incidence Public-Use Database, 2001; US Cosmetic and Toiletries Market, 2001).
Parabens Found in Breast Tumors
A study by Dr Darbre has show that parabens occur in breast tumor tissue. In this study, 18 out of the 20 tested breast tumor samples contained parabens.  This indicates that parabens stay intact in the human body, and that parabens are also stored in breast tissue. Consequently, parabens absorbed through the skin can be expected to accumulate in the body.
Oestrogenic activity of parabens
Furthermore, it has been established that parabens can increase the growth of MCF7 human breast cancer cells.  In the same article, Darbe et al state:
the recent discovery that parabens possess oestrogenic activity has challenged the concepts of their toxicity in new ways. Because parabens can bind to oestrogen receptors, they may be able to mediate unwanted effects at much lower concentrations and more specifically than through nonreceptor mediated mechanisms. 
With this information available, one would expect the government to fund research and take preventive and protective measures. So what does the FDA have to say about parabens?
The FDA and the National Cancer Institute about Parabens
The FDA uses the Cosmetic Ingredient Review (CIR) to review the health effects of parabens. A fact that is worth mentioning, is the not-so-independent position of the CIR. Like the FDA, the CIR is funded by the industry that it is supposed to monitor. The SIR prominently shows the following on its website:
The Cosmetic Ingredient Review (CIR) was established in 1976 by the Cosmetic, Toiletry & Fragrance Association (CTFA) with support of the U.S. Food & Drug Administration and the Consumer Federation of America. Although funded by CTFA, CIR and the review process are independent from CTFA and the cosmetics industry. 
The U.S. Food and Drug Administration (FDA) tells on its website:
The [CIR] reviewed the safety of [parabens] in 1984 and concluded they were safe for use in cosmetic products at levels up to 25%. …In December 2005, …the Panel determined that there was no need to change its original conclusion that parabens are safe as used in cosmetics. 
The FDA’s opinion on the subject:
[The] FDA believes that at the present time there is no reason for consumers to be concerned about the use of cosmetics containing parabens. 
The National Cancer Institute (NCI) states:
More research is needed to specifically examine whether the use of deodorants or antiperspirants can cause the buildup of parabens and aluminum-based compounds in breast tissue. Additional research is also necessary to determine whether these chemicals can either alter the DNA in some cells or cause other breast cell changes that may lead to the development of breast cancer. 
Note how both the FDA and the NCI do not state that parabens are safe to use.
The continues low-level exposure to parabens is relatively new to our lifestyle, and the long term effects have not been researched. Similarly, the effects of exposure to preteens and the effects on babies in the womb and babies being nursed have not been studied and are therefore unknown. 
Not nearly enough research has been done on the harmful effects of parabens, this is mainly due to a lack of funding. There does not seem to be any interest to fund more research from the cosmetics industry, from governments or from so called ‘health organizations’.
However, the researchers that have dedicated their time to this subject have shown a clear relationship between deodorants / antiperspirants and breast cancer.
As stated by Darbre et al:
Without clear evidence that using weakly oestrogenic compounds in underarm cosmetics is safe, it would be prudent to apply a precautionary principle and replace known oestrogenic formulation excipients and also, in the case of preservative removal, accept shorter shelf-lives. 
Again: do not believe this article, but do your own research and come to your own conclusion. Please do not blindly follow the advice form the FDA or any other organization.
This article is the third part in a series titled ‘Deodorants, Antiperspirants and Your Health’. Please click here to read the first part, ‘Deodorants, Antiperspirants and Your Health’. Click here to read the second part ‘Antiperspirants – Aluminum & Alzheimer’s Disease’. And click here to read the third installment ‘Antiperspirants – Aluminum & Breast Cancer’.
The next and final part in this series will provide you with alternatives to the traditional deodorants / antiperspirants.
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McGrath, Kris G. “Why Breast Cancer is Spreading Around the World.” ControlYourImpact.Com. 12 Feb. 2008. 13 Feb. 2008 <http://www.controlyourimpact.com/2008/02/breast-cancer-prevention-deodorant-antiperspirant/>
Darbre, P D., A Aljarrah, W R. Miller, N G. Coldham, M J. Sauer4, and G S. Pope. “Concentrations of Parabens in Human Breast Tumours.” Journal of Applied Toxicology 24 (2004): 5-13. 10 Feb. 2008 <www.interscience.wiley.com>
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“Concern Over Deodorant Chemicals.” BBC News 11 Jan. 2004. 12 Feb. 2008 <http://news.bbc.co.uk/2/hi/health/3383393.stm>
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“Oestrogenic.” Def. 2. Biology Online. 11 Feb. 2008 <http://www.biology-online.org/dictionary/Oestrogenic>
Lee, John R. “The Oestrogen Myth.” Well Woman’S Information Service. 12 May 1996. 10 Feb. 2008 <http://johnleemd.org/the_oestrogen_myth.html>
“Xenoestrogen.” Wikipedia. 10 Feb. 2008 <http://en.wikipedia.org/wiki/Xenoestrogen>
Darbre, P D. “Underarm Cosmetics and Breast Cancer.” Journal of Applied Toxicology 23 (2003): 89-95. 3 Feb. 2008 <www.interscience.wiley.com>
Darbre, P D. “Underarm Cosmetics are a Cause of Breast Cancer.” European Journal of Cancer Prevention 10 (2001): 389-393. 24 Jan. 2008
Darbre, P D. “Aluminium, Antiperspirants and Breast Cancer.” Journal of Inorganic Biochemistry 99 (2005): 1912-1919. 24 Jan. 2008.
McGrath, K G. “An Earlier Age of Breast Cancer Diagnosis Related to More Frequent Use of Antiperspirants/Deodorants and Underarm Shaving.” European Journal of Cancer Prevention 12 (2003): 479-485. 24 Jan. 2008.
Also Available at: http://www.cbsnews.com/htdocs/pdf/KGM_paper.pdf
Cosmetic Ingredient Review. U.S. Food & Drug Administration. 12 Feb. 2008 <http://www.cir-safety.org/>
United States. U.S. Food and Drug Administration. CFSAN/Office of Cosmetics and Colors. Parabens. 20 Mar. 2006. 13 Feb. 2008 <http://www.cfsan.fda.gov/~dms/cos-para.html>
United States. National Cancer Institute. U.S. National Institutes of Health. Antiperspirants/Deodorants and Breast Cancer: Questions and Answers. 10 Feb. 2008 <http://www.cancer.gov/cancertopics/factsheet/Risk/AP-Deo>