Will deodorants give you cancer?

We all know of someone who have or have had breast cancer. It is a nasty illness and a hard and difficult struggle, both mentally and physically. Luckily, treatments and diagnostic tools have gotten better, saving many women’s lives.

Due to breast cancer being such a common form(s) of cancer, it has become subject to a lot of fear mongering by media. Many quacks have also seen an opportunity to make money off the unfortunate. I think that this is despicable!

The pink ribbon. https://upload.wikimedia.org/wikipedia/commons/c/c4/Pink_ribbon.jpg

The pink ribbon (image credit: azzara.it)

I have stopped counting the items that will give me cancer according to mainstream media. I have grown complacent. However, as I yesterday had to spend the day in bed (I still have the man-flu) alone with my thoughts of doom and gloom and a fair dose of hypochondria, I started to ponder about the link between breast cancer and deodorants. These thoughts were partly fueled by the light perspiration odor that stemmed from being in bed a whole day. I have completely ignored these cancer warnings so far as I want to smell good (“good” here defined within the cultural construct I live in) and not like a sweaty hippie.

Why could deodorants be dangerous?

Deodorants, or antiperspirants, contain preservatives called parabens and they are known to have estrogen properties. This means that they can mimic the effects of estrogen in the body. They can attach to certain components of the cell and encourage growth.  If some special genes that are involved in the control of cell-growth have mutated in that particular cell, the added effect of an estrogen-like compound may cause uncontrolled growth and division of that cell: cancer.

There have been studies done in vitro on the carcinogen effects of parabens. “In vitro” means that you experiment on cells in a lab and not on a living human, and though these studies can be helpful, the results do not necessarily and always directly translate into the human system.

Breast anatomy.  Mehdi at Persian Wikipedia [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

Breast anatomy.
(image credit: Mehdi at Persian Wikipedia)

These particular in vitro studies were well carried out, good studies, but be very aware of idiots and quacks who claims that something has anti-cancer properties just because some cancer-cells on a plate died when they poured some miracle medication over them. Well, try to pour hydrochloric acid on cancer cells in the lab… does that mean that hydrochloric acid is the all-time-cure for cancer? I actually even think that if I poured urine on some cancer-cell culture plates in the lab, the cells would die. I can see a lucrative business here selling my own urine for $100 per milliliter as a cure for cancer. Just kidding, but seriously, be very careful of such claims!

Aluminum is another component in deodorants that have been suggested to cause illness in humans, namely Alzheimer’s disease. Most of the studies I have read concluded that aluminum, in the concentrations found in cosmetics, does not cause Alzheimer’s disease.

The studies

When starting to read through the literature I was once again struck by the inconsistency of the results and small sample sizes (see my post on vitamin C). The former may be a statistical problem of the latter. There were studies that showed that there is a positive correlation between deodorant use and breast cancer (deodorants case breast cancer) and some that actually showed that the use of deodorants provided protection against cancer (!).

Many of the studies lacked internal controls and many included very small number of participants; the standard issues encountered in human biology and medicine.

One line of argument that were found in several papers is that breast cancer is most likely to be found in the upper, outer quadrant of the breast, which is close to one’s armpit where one would apply deodorant. However, critics comment that a high proportion of the breast located at this position, which would explain the higher incidence of tumors found.  The more breast tissue, the likelier the appearance of breast tumors – duh.

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“The breast: its anomalies, its diseases, and their treatment” (1917). Image from page 628.

Do deodorants cause cancer?

A meta-study by Hartenfeldt et al. (***) collected data from studies published between 1950 and 2012 and found no correlation between breast cancer and the use of deodorants. They suggest that the paraben concentrations in the deodorants are simply not high enough to become dangerous. Yes, here we go again: “THE DOSE MAKES THE POISON!” However, they did express some concerns of the small number of studies they could include in their meta-analysis and expressed a wish for further studies to be conducted.

One thing that I reacted very badly to when reading some of these articles were statistical arguments like:

The global rise in breast cancer correlates with increased use of deodorants over the past 30 years.

Well, if you take a look at global data from the past 30 years, I think you can find quite a few things that correlate well with the rise in breast cancer: number of cats owned by single women perhaps? Also, more people are diagnosed correctly.

I am not saying that there is proof that there is no real correlation (nor the opposite) between breast cancer and deodorants, only that one should be very careful when making large sweeping generalizations regarding global correlation patterns. This you learn as an ecologist. Trust me! For some reason people are inclined to believe any old crappy correlation in medicine, but have a hard time accepting correlations such as between CO2 concentrations and a warmer climate, despite the data being much more solid. The human psyche: a mystery.

By Smithsonian Institute [Public domain], via Wikimedia Commons

“Within the curve of a woman’s arm” (image credit: Smithsonian Institute)

Well, in the end I cannot really say if deodorants cause cancer. Despite there being solid arguments explaining why they would, I really lack statistical proof. Even if you logically can explain why an event would be likely to occur in theory, does not mean that it happens: the dose might be too low and the meta-studies found no correlation. The evidence is in my opinion inconclusive.

I have made the personal decision to continue to use my deodorant. Maybe changing deodorant type every so often would be a good thing?

I hope that this post helped high-lightening some of the problems in medical research even though I failed in my attempt to give you a clear answer to the question I had set out to answer.

Science Safely!

Dr. Anna of The Imaginarium

...is a statistics-nerd.

…is a statistics-nerd.

References:

***Hardefeldt, Prue J., Senarath Edirimanne, and Guy D. Eslick. “Deodorant use and breast cancer risk.” Epidemiology 24.1 (2013): 172.

Willhite, Calvin C.; Karyakina, Nataliya A.; Yokel, Robert A.; et al. Systematic review of potential health risks posed by pharmaceutical, occupational and consumer exposures to metallic and nanoscale aluminum, aluminum oxides, aluminum hydroxide and its soluble salts. CRITICAL REVIEWS IN TOXICOLOGY  Volume: 44   Special Issue: SI   Supplement: 4   Pages: 1-80   Published: OCT 2014

Graves AB, Rosner D, Echeverria D, Mortimer JA, Larson EB. (1998).Occupational exposures to solvents and aluminium and estimated risk of Alzheimer’s disease. Occup Environ Med, 55, 627–33.

Graves AB, White E, Koepsell TD, Reifler BV, van Belle G, Larson EB. (1990). The association between aluminum-containing products and Alzheimer’s disease. J Clin Epidemiol, 43, 35–44.

Darbre, PD Underarm cosmetics and breast cancer. JOURNAL OF APPLIED TOXICOLOGY  Volume: 23   Issue: 2   Pages: 89-95   Published: MAR-APR 2003

 

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