I’m starting a shorter series on Girls Love Evidence, where I investigate common health claims and debate their merits. Today, I’m starting with one that I’ve heard time and time again- there is a link between deodorant and breast cancer.
I remember the first time I heard this as a high schooler. I was in the locker room, rubbing a glittery-cucumber-scented stick on my armpits while changing out for cross country practice. A teammate looked on in horror, stating affirmatively, “That kind of deodorant gives you cancer!”. After affirmatively stating my pro-glitter position, she informed me it was because unnatural deodorant causes breast cancer and that the glitter, while abominable, was not the culprit, but some unnamed “toxin”.
That weekend, I made my mom buy me natural deodorant. I remember proudly showing it off on Monday, feeling like I had made an excellent decision for my future health. After practice, I realized I had made a grave mistake. My t-shirt was soaked in sweat, and I smelled horrible. I began to reckon with the “maybe” of getting cancer and the “definitely” of smelling gross. 15-year-old me was not ready to chance scaring off potential cross country hotties in the name of my future health. Fortunately for me and my lack of foresight at age 15, there isn’t a lot to prove a link between deodorant and breast cancer.
Cause and Effect Relationships
The most important thing to keep in mind when looking at these types of health claims is that it is incredibly difficult to determine a cause and effect relationship for illness, especially illnesses that have a myriad of environmental and genetic factors like cancer. There’s room for “contributes”, but “causes” is challenging. People come into contact with known carcinogens regularly, and never develop cancer, while others have the misfortune of it springing up despite a remarkably healthy life. To prove or disprove a claim like “deodorant causes breast cancer” is incredibly difficult.
The problem with health and wellness journalism is that it isn’t too sexy to print headlines like “Maybe These Things Are Related But We Can’t Really Do a Well-Controlled Long-Term Double-Blinded Study To Prove Cause and Effect”.
This is part of a bigger, overarching problem with inaccurate scientific information. It is often impossible to completely prove or disprove things. Even with the best application of the scientific method, there is always room for doubt.
While getting my master’s in cancer biology, I learned about the main schools of thought in cancer science. The first is that there are many ways to avoid carcinogens, so we can, and should, do what is possible as individuals/societies/governments to avoid them. The other is that cancer is mainly just bad luck and that if your genes decide to act up, whether it be due to age or misfortune, cancer is unavoidable.
First, I want to address a common point of confusion here: the difference between antiperspirant and deodorant.
Deodorant keeps you from smelling. Usually, you stink because bacteria on your skin mixes with sweat and makes an unpleasant odor. Deodorant works by killing this bacteria, so when you sweat, it just smells like, well, nothing.
Fun hack: if you realize that you have forgotten deodorant (we’ve all been there), you can rub a bit of hand sanitizer into your armpits. This isn’t a great everyday solution but it works to kill some of the bacteria responsible for stink. You’re welcome.
Antiperspirant keeps you from sweating. This usually happens when aluminum salts block the pore your sweat comes out of. These salts form a kind of “gel” over the pore and this works to stop sweat from getting out. Most “deodorants” have both ingredients that act as deodorants (kill bacteria) and ingredients that act as antiperspirants.
A lot of what we consider “natural” deodorants just don’t contain antiperspirant. The deodorizing properties are still there, but the aluminum salts are not.
Knowing that antiperspirants just “trap” the sweat inside, isn’t it bad for our bodies to reduce sweat? Don’t we risk overheating?
We definitely need sweat to thermoregulate (keep our bodies at a happy temp). However, since your armpit is only responsible for about 1% of your whole body’s sweat, antiperspirants don’t do much at all to inhibit the body’s ability to maintain temperature. Again, I wouldn’t recommend wiping your entire body down with Secret, but the sweat is probably the least of your concerns there. (Have you ever tried getting that white deodorant stain off of clothing?)
“It’s Illegal in Europe”
I see this all the time, usually used as an American justification of why something is bad/toxic/not great. While it is true that there are different regulations in the EU regarding food/drugs that don’t always align with those of the FDA, the fact that something is illegal/not illegal doesn’t always have much to do with human health (see: lots of illicit drug laws), and Europeans are not immune to fostering non-evidence-based beliefs on health (see: common perceptions of the IUD/hormonal birth control)
Some of this likely comes from A European study from 2003 which showed that among 437 women diagnosed with breast cancer, those who reported more frequent use of deodorant and earlier onset of underarm shaving also reported being diagnosed earlier with breast cancer.
While this is certainly an interesting look into the multiple factors that could cause cancer, this is most definitely not an instance of a cause-and-effect relationship. Those who shave earlier in life may have hit puberty earlier, and those who use deodorant more often could be those with undiagnosed hyperhidrosis. These are only two potential options among the many, many, other aspects that would need to be controlled to establish a cause and effect relationship. When it comes to cancer, it’s just not that simple.
Fortunately, as of March 2020, topical aluminum salts (like those in antiperspirants) are not illegal in Europe. The EU’s Committee on Consumer Safety approved aluminum-containing cosmetics, admittedly in lower concentrations than are available in the United States. For comparison, non-spray deodorants are available with 6.25 percent aluminum in the EU, vs. 20 percent in “clinical-strength” stick deodorant available in the U.S.
In the EU’s report, this conclusion was reached after evaluating oral, dermal, and inhalation toxicity. What’s important is that the calculated safety margin was 2000 times lower than the minimal dose identified as not causing any toxicological effects. This means that you could increase the concentration of aluminum allowed by 2000 and you still wouldn’t see any toxic impact on human health (having this high of a threshold is a good thing!)
Girls Love Evidence’s Take
In short, am I worried about the link between deodorant and breast cancer? Kind of, but that’s probably because I’m just generally worried about everything we put in/on our bodies that may or may not influence our propensity to get cancer. Occupational hazard, I guess.
I am not, however, worried enough to stop wearing my regular old antiperspirant and deodorant. I run a lot, I work out a lot, and I love wearing sweaters in 60-degree weather. Unless I want to destroy all of my clothing and close interpersonal relationships, I need the antiperspirant and deodorant combo.
From my review of the evidence out there (and in the opinion of professionals at cancer.org), the science isn’t there to prove a link between deodorant and breast cancer. Use the deodorant that works best for you. Simple as that.