A funny thing happened to me on the way to visit my boyfriend last weekend. And by funny I mean terrifying.
In a nutshell: I'd been chosen for a random screen by the metal detector at the airport. A TSA agent was called over, who had me step aside and put my palms up. She swiped both down with a medical-grade swab that she then stuck into a machine.
No big deal, right?
Except that the machine then beeped a few times, flashing an angry red screen that read, in all caps, "EXPLOSIVES DETECTED."
I'm telling this story now, so you can see I'm still gainfully employed, not in prison, and wasn't carrying any explosives.
So what set the detector off?
As soon as the agent saw my panicked expression she rolled her eyes, and asked, as if this was a regular occurrence, "Did you just put on lotion or something?"
Really? My lotion?
Apparently so, and here's why: The explosives detectors look for a compound called ammonium nitrate. And according to Randy Schueller, a cosmetic scientist who runs the site The Beauty Brain, ammonium nitrate is "commonly used in fertilizers and occasionally used in cosmetics as a buffering agent."
Still, my problem wasn't one Schueller had encountered much before.
"We've only seen two products that actually use ammonium nitrate and they were both muscle rub creams," Schueller said. He says you could check the ingredient lists of all your products to see if they include either the "ammonium" or "nitrate" components, but then you'd be screening out products like body washes and shampoos that contain ammonium lauryl sulfate, which he doesn't believe would be detected by the screening machines.
And while I handn't used a muscle rub cream, Schueller offered this: "My guess (and this is just a guess) is that the nitrates are more commonly used in products that are in the form of creams and lotions. If that's true, products like powdered makeup, body wash and perfume would be less likely to cause a false positive."
And those nitrate-containing salts stay on your skin until they're removed, so no chance of them dissipating before you get to the airport if they are present in your products. Plus, according to Schueller, chemicals picked up by those explosives detectors aren't typically added directly into cosmetics. Instead, they're present in trace amounts in "rare materials" making them "very difficult to identify," but nonetheless can end up in your lotion.
The takeaway here seems to be that, unless the TSA can put out a comprehensive list of products that might cause a false positive (which does seem unlikely, since a potential terrorist could just blame a positive result on a product on that list), you might want to avoid putting on any product right before you travel that could potentially test positive OR thoroughly wash your hands just before going through airport security.
Or you could just say #YOLO, slather up, and hope for the best.