Yesterday, Dr. Julie Horvath introduced you to our Armpit Microbe Pilot Study, known as #PitStart to those of you following along in real time on Twitter. Before we start asking thousands of you to send in smelly Q-tip’s that you’ve twirled around in your armpit, we need to work out a few methods. Namely, we’re concerned that some deodorants and antiperspirants inhibit bacterial growth – this was Julie’s personal experience when she tried to plate out her armpit microbes a few months ago.

So Dr. Julie H. and Dr. Jul Urban, the Assistant Director of the Genomics & Microbiology Research Lab at the Nature Research Center (NRC) at the NC Museum of Natural Sciences, and their trusty lab interns recruited 18 people, 9 men and 9 women, to go without deodorant or antiperspirant for a week. Full disclosure: I’m a participant.

On Sunday, participants went about their normal personal hygiene routines, applying deodorant or antiperspirant as per usual. Yesterday, we started the ‘Au Naturel’ treatment and will continue to go without deodorant/antiperspirant for the rest of the week. Every day between 11a and 1p, we have to sample each armpit with a sterile swab. Protocol calls for you to twirl the dual-tipped swabs in the deepest, wettest part of the armpit for 45 seconds. That’s longer than you think – Ok, at the risk of sharing too much information, here’s another disclosure: I take my phone in the bathroom with me and use the stopwatch app to time myself while swabbing. 45 seconds is an unbelievably long time.

Each day participants then deliver the day’s swabs directly to the Genomics & Microbio Lab at the NRC. There, members of Team Armpit dip and vigorously twirl a tip from each swab in a vial of liquid buffer to shake off the microbes. They then use a pipette to suck up a small volume of that microbe-laden liquid and spread it across a plate filled with nutrient-rich agar. The plates are plopped into a 37 degrees Celsius (or 99 degrees Fahrenheit, aka body temperature) incubator for about 24 hours, and we wait for the bacterial colonies to grow (or not).

Today, when I delivered my samples to the NRC, I had a chance to take a peek at the armpit microbes I collected on Day 0 of the experiment (the last day I wore antiperspirant).

Lucky for you, I brought my audio recorder with me. Here I am talking with Dr. Jul Urban:

Did you catch that? For Day 0, the plate from my right armpit barely had any bacterial colonies growing. Yet for the same day, the plate from my left armpit was FULL of bacteria!  I took some pictures so you can see for yourself.

Clearly there is more microbial action going on in my left armpit than in my right!

As you heard in the audio, Julie hypothesized that the difference may be due to sampling effort. Perhaps because I am right-handed I swabbed my left pit more vigorously as I was using my dominant hand to do so. Yet, I think I’m meticulously and vigorously sampling both pits with equal effort (Hello? I use a stopwatch to time myself).

I checked back in with Julie later this afternoon, and she reported that I am not the only one showing this differential growth in each pit. Apparently there were quite a few other folks whose plates from Day 0 (Normal Habits) showed a similar pattern.

Chatting these findings over with a few friends and colleagues, I learned that many people have observed one pit regularly being more sweaty and smelly than the other. Is this the case with me? Does that explain the freak-show growth of microbes in the left armpit and not in the right? I must admit that I’ve not really noticed this about my body before, but perhaps now I’ll start paying more careful attention, particularly since I’m going without antiperspirant all week and will be extra smelly.

As #PitStart is an experiment in real-time, we’d love to hear your thoughts, hypotheses and observations about your own armpits. Drop a comment on the blog or participate in the conversation on Twitter (#PitStart).

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