Originally published on Chemical of the Day October 2015.
I recently caught a panel discussion on satellite radio about breast cancer (presumably for Breast Cancer Awareness Month). A number of doctors were answering questions and debunking some myths about breast cancer, treatments, and causes. In this discussion they addressed the question of whether antiperspirants cause breast cancer. The doctor's answer was unequivocally "No. That's just an internet myth." He went on to describe that the myth started as a result of women being asked to wipe off your deodorant because the aluminum particles can interfere with the imaging. The doctor stated that people got confused and started thinking that antiperspirants were bad and then spread rumors via the internet.
Is the antiperspirant and breast cancer link just an internet myth created by confused people?
The potential link between breast cancer and aluminum antiperspirant may have started out as one of those "pass it along" emails in the late 90s, but the aluminum-breast cancer link has actually been studied for a number of years now. The first published study regarding antiperspirant use and breast cancer risk was in 2002, a population-based study that actually found no correlation between breast cancer and antiperspirant use. (Source) However, the next year, a researchers found that earlier and more frequent antiperspirant use did correlate with earlier breast cancer diagnoses, suggesting that aluminum may have been to blame. (Source) One thing they did not apparently discuss, however, was that perhaps women who used deodorants earlier in life had been exposed to estrogen for a longer period of their lifespan. The earlier the need for deodorant arose, the earlier puberty and its resulting hormones would have been, and thus higher risk for reproductive cancers. So, that study wasn't able to show direct causation.
In 2004 a case study was published in The American Journal of Medicine detailing a case of a woman who had experienced aluminum poisoning. Once she stopped using aluminum-based antiperspirants, her aluminum levels went back to normal levels. (Source) Researchers strongly suggested that the antiperspirant was to blame. Other studies (and widespread use of antiperspirants) however, have shown very low absorption rates on intact skin. Higher rates have been found for abraided skin. (Source)(Source) It is hypothesized that some people may absorb aluminum more than others. In a follow-up article in The American Journal of Medicine, Christpher Exley, PhD states
"We now know that transdermal uptake of aluminum is not only possible, but may also be important. I am now concerned that we are guilty of being complacent about exposure to aluminum."
In 2009 researchers studied antiperspirants' blocking mechanisms and suggested antiperspirant use could lead to higher exposure of certain hormones. Many of the compounds released in our sweat are androgens (a type of hormone) or androgen metabolites, and pheremones. Researchers proposed that when the sweat is not released, these hormones end up back in the body and can disrupt the body's hormone function.
Antiperspirants intended action, obstruction of axillary apocrine sweat glands, could create a reservoir of hormones in an optimal environment for transdermal absorption. Long term inadvertent and unintended systemic hormonal exposure to developing breast and prostate tissue may occur. (Source)
In 2011, increased concentrations of nickel, cadmium and aluminum were found to accumulate in breast cancer tissue (source) however, later studies weren't able to reproduce the findings (Source) but different extraction methods were used. In 2013, however, researchers collected nipple aspirate fluids, comparing those of breast cancer patients vs. healthy subjects. The samples found increased levels of oxidative markers and aluminum in the fluids from women with breast cancer.
"In addition to emerging evidence, our results support the possible involvement of aluminium ions in oxidative and inflammatory status perturbations of breast cancer microenvironment, suggesting aluminium accumulation in breast microenvironment as a possible risk factor for oxidative/inflammatory phenotype of breast cells." (Source)
A 2014 review published in the Journal of Trace Elements and Medical Biology states the following:
Recent work in cells in culture has lent credence to the hypothesis that this metal could accumulate in the mammary gland and selectively interfere with the biological properties of breast epithelial cells, thereby promoting a cascade of alterations reminiscent of the early phases of malignant transformation. In addition, several studies suggest that the presence of Al in human breast could influence metastatic process. As a consequence, given that the toxicity of Al has been widely recognized and that it is not a physiological component in human tissues, reducing the concentration of this metal in antiperspirants is a matter of urgency.
The Bottom Line
There is still a lot we don't know about the antiperspirant and breast cancer link, but the body of research should not be written off as "just an internet myth." This is an emerging field of science. While there has been no population-based study showing correlation/causation between antiperspirant use and risk of breast cancer, there are a few things that we do know:
- Aluminum is absorbed to some degree through antiperspirant (and crystal deodorant) use; rates vary depending on an individual's skin and predisposition.
- Aluminum has no biological role in life function and is a pro-oxidant that damages cells and DNA and displays estrogenic activity.
- Aluminum has been found to accumulate in breast tissue and is especially concentrated in fluids such as breast milk.