Originally published in May-June 2004 icon
Living in a sea of Oestrogen
By Dr. Philippa D. Darbre
Breast cancer is the major cancer of women in the Western world and incidence is rising. However, although epidemiological studies have shown that 90% of breast cancers are environmental in origin and linked to a "Western lifestyle", the specific causes have never been identified. Yet identification of the causes must be a primary research objective if prevention is ever to become a reality.
Oestrogen and Breast Cancer
Of all the risk factors identified for breast cancer, exposure to oestrogen remains the longest standing, having stood the test of a century of research. Oestrogen is known to drive the growth of human breast cancer cells in the laboratory and about one half of breast cancers in the body. Indeed for those tumours responsive to oestrogen, stopping oestrogen action (by stopping it being made in the body or by antagonising its action in the cells) remains the one clue today to providing a therapy not based solely on radiation and chemotherapy.
Oestrogen-Mimicking Chemicals: Living In A Sea Of Oestrogens
So if oestrogen is linked to breast cancer development, shouldnt we be concerned by finding that many chemicals in our environment can accumulate in human breast fat and can mimic oestrogen action? Oestrogen-mimicking compounds are found widely distributed in the environment. Some are found in plants (phytoestrogens) and are eaten in the form of edible plant material. Others are present in the environment from widespread use of pharmacological oestrogens such as the contraceptive pill and hormone replacement therapy.
Oestrogen-mimicking compounds are found widely distributed in the environment
Finally there are many man-made chemicals (xenoestrogens) which can also mimic oestrogen action. Some of these chemicals have been released from agricultural spraying, from industrial processes and from water disposal and have found their way into our diet through the food chain and water supplies. Other oestrogen-mimicking chemicals are found in household products in daily use such as plastics, cleaning agents, pesticides, herbicides and cosmetics.
Living In A Sea Of Oestrogens: Does It Matter?
Although we live in a world surrounded by oestrogen-mimicking compounds, the unresolved scientific question is: does it matter? Since the female body has physiological oestrogens, does an additional overload of oestrogenic chemicals matter? In trying to answer this question, it is important to remember that physiological oestrogen levels vary during a lifetime, being low before puberty and after menopause, and even rising and falling during the normal monthly cycle. However, these other compounds do not follow physiological patterns, they are simply there all the time.
Another important issue is whether these compounds can find their way into the breast at sufficient levels to have any effect. Natural physiological oestrogens are short-lived and continually broken down by the body and the same holds true for the plant oestrogens. However, the man-made chemicals are not easily broken down by the body and tend to accumulate in fatty tissues of the body with age. Although there are well recognised consequences to fertility of wildlife from exposure to such oestrogenic chemicals, investigations into related human health problems have stalled over the issue of exposure. Aquatic wildlife can be continuously exposed to these chemicals by virtue of the water in which they live. Such a near continuous exposure has not been identified for the human population. However, application of bodycare cosmetics with oestrogenic chemicals to the underarm and breast area may be able to satisfy the exposure issues.
Underarm Cosmetics and Breast Cancer
I have recently put forward the hypothesis that chemical overload from cosmetics applied to the underarm and breast area could be a cause of breast cancer. This centres on antiperspirant and deodorant products, but also includes a variety of body lotions, body creams, suncare creams, tanning creams, shaving creams, breast firming and enhancing creams as applied to the underarm and breast area.
Chemical overload from cosmetics applied to the underarm and breast area could be a cause of breast cancer
These cosmetics contain a cocktail of diverse chemicals, many of which are known to exert toxic effects, yet they are applied with ever increasing frequency without question. They are not rinsed off, as are shampoos and soaps, but the entire application is left on the skin each time, allowing for accumulation and a situation of chemical overload in the underarm and breast area.
Chemical Overload From Underarm Cosmetics
If these cosmetics are involved in breast cancer, then quantity may be as important as the identity of specific chemicals. Owing to the nature of the active ingredients, antiperspirants are regulated as over-the-counter drugs, yet there are no indications of safe level of usage as for other pharmaceuticals. Advice is given not to apply to broken skin, but women continue to apply them after shaving, a procedure which causes nicks and abrasions in the skin following hair removal. These cosmetics are being used by ever younger children before puberty and even on babies, and there are no recommendations as to whether such usage is prudent. There is evidence that the origin of breast cancer can be many years before symptoms become visible and it is thought that the breast may be especially susceptible to carcinogenesis before puberty.
How Could Such Chemicals Cause Breast Cancers?
These cosmetics contain a wide range of chemicals, many of which are already known to exert a variety of toxic effects and some of these have been detailed in icon. Of specific issue to the breast are those chemicals which can mimic oestrogen action. Parabens are added to these cosmetics as preservatives, and research has shown that they can mimic oestrogen action and that they can be detected in human breast tumours. Triclosan is added as a preservative or deodorant to cosmetics and has been shown to act as an endocrine disrupter in wildlife and has been detected in human milk. (It has been banned in the USA from 2017)
Cyclosiloxanes are present in high proportions in personal care products and they have also been reported to have an "affinity for the oestrogen receptor". Clearly the oestrogenic action of such compounds and their detection in the human breast does not provide evidence for a causal link to cancer, but such an association warrants some research.
Parabens can mimic oestrogen action and can be detected in human breast tumours Whether an oestrogenic stimulus is sufficient to cause breast cancer is debatable. At its root, carcinogenesis requires damage to the DNA of a breast cell, as well as the enabling of that damaged cell to grow. So the question then arises as to the identity of potential DNA binding chemicals which could damage DNA. In this respect, the antiperspirant agents are aluminium salts, and aluminium has been shown able to bind to the DNA of a cell. The general toxicity of aluminium is recognised in the context of Alzheimers disease, but the implications remain unknown of regular application to the underarm and breast area of antiperspirants which contain aluminium salts at levels of up to 25% by weight (that is 25gm in every lOOml).
Is There Any Supporting Clinical Evidence?
The strongest supporting evidence comes from unexplained clinical observations dating back decades and showing a disproportionately high incidence (up to 60%) of breast cancer in the upper outer quadrant of the breast. A simple explanation may relate to this being the local area to which underarm cosmetics are applied. Another set of clinical observations without adequate explanation are those showing the left breast to be more prone to cancer than the right breast, and this may also simply relate to greater application on the left side by a population which in majority is right-handed.
More recently, two epidemiological studies have been carried out with the specific aim of identifying any association between underarm cosmetic use and development of breast cancer. A study in 2002 reported no difference in use of antiperspirants or deodorants between patients with breast cancer and those without breast cancer at the time of the study. In stark contrast, a study in 2003 showed an earlier age of diagnosis of breast cancer (by up to 22 years) in those who had used more antiperspirant/deodorant products.
Chemical Overload From Antiperspirants and Breast Cysts:
Breast cancer represents only about 5% of clinical abnormalities of the breast, with other problems including fibroadenomas and breast cysts. Strangely, the upper outer quadrant of the breast is not only the most common site of cancer but also of other benign breast conditions. It is interesting to note that breast cysts are caused by blockage of breast ducts which subsequently fill with fluid to cause a lump. Antiperspirant cosmetics act by blocking the sweat ducts under the arm and so prevent escape of sweat onto the skin surface.
Breast cancer represents only about 5% of clinical abnormalities of the breast It would be surprising if application of antiperspirant cosmetics were so precise that none were ever mistakenly applied to the adjacent breast area, and if such cosmetics were mistakenly applied then they could be expected to block local breast ducts also. I have had seven independent people tell me of their experience of how breast cysts have disappeared upon cessation of use of antiperspirant.
Prevention of Breast Cancer: Could It Ever Become a Reality?
The breast has had a special place throughout history, not only as a sensual organ with sexual attraction, but also as the essential first source of comfort, immune protection and food for babies as they enter the world. It is a regrettable fact that, in the world of today, the breast has become contaminated with a variety of chemicals. So far science has failed to prove any causal link between breast cancer and diffuse exposure to such chemicals through diet or environment, and indeed we all have to live in the world and can only do so much towards reducing exposure to such chemicals. However, if a real issue of continuous exposure is through use of underarm cosmetics, then at long last there might be a route to prevention of breast cancer. Use of these cosmetics can be altered, reduced or stopped without any life-threatening consequences. Although the peer pressure may now be as strong to use these cosmetics as the social pressures to smoke, there would at least not be the addictive barriers to overcome on cessation of use as for smoking. Studies into prevention of breast cancer have been hampered for lack of clues as to where to begin. Study of chemical overload from underarm cosmetics should at least be an area amenable to research and could provide an avenue into searching for ways of preventing breast cancer. For those concerned, my personal recommendation is to reduce or eliminate use of these cosmetics. I no longer use antiperspirant/deodorant products. I wash with soap and water twice a day, and I wonder now why it was that I once needed to apply all these chemicals under my arm.
Dr. Philippa D. Darbre
Dr. Philippa Darbre graduated in Biochemistry at Birmingham and gained a PhD at Cambridge. Her first 5 years of research were at Oxford where she held the first Nuffield Medical Research Fellowship.
In 1981 she moved to the Imperial Cancer Research Fund (now Cancer Research UK) where she began her research into oestrogen and breast cancer. Since 1991, she has been continuing this research at the University of Reading’s School of Animal and Microbial Sciences where she is a senior lecturer in Oncology. Philippa is now Professor in Biological Sciences.