A friend who’s a photographer has recently had a persistent problem at TSA. A while back something spilled on his carry-on bag while traveling and the only thing he had to clean it was some hand washing soap.

Ever since then, whenever TSA uses their “explosive trace detection” (ETD) unit to test his bag, it comes up positive. He is subject to intensified screening, including a full enhanced patdown, ETD testing on his photography equipment and much of the clothing and other items in his carry-on bag. His hands have come up “positive” at times, as well.

He contacted me to ask if I had any ideas about what was happening, and if there was something he could do. He flies a great deal and it has been making his flights extremely difficult.

He thought about purchasing a new carry-on bag, but he likes its design. Replacing it would be expensive. Moreover, his hands were coming up positive for explosives before some flights.

It turns out, the explanation for his ETD false positive and the reason he’s had to endure being treated as if he’s a criminal or terrorist by TSA personnel is the bottle of hand washing soap he uses while traveling. It contains a common ingredient found in many hand soaps and sanitizers — glycerine.

Trace amounts of glycerine residue on your hands or belongings can be easily picked up on a swab by a TSA agent checking you for explosives as explosives evidence in their ETD scanner.

Hand lotion, soap or sanitizers aren’t the only things people contact which can cause a false positive in TSA’s ETD equipment. Anyone with a heart condition who uses nitroglycerine can cause a false positive. Farmers who handle fertilizer and law enforcement officers or hunters who handle ammunition can cause false positives too.

Things people touch with “contaminated” hands can become “contaminated” themselves. It’s likely that happened in 2011 when 7 month old Bruce Ankenbrand was flying with his parents. A Transportation Security Officer (TSO) swabbed Bruce’s baby food and declared it suspicious when its containers tested positive for explosives. The TSA agent tested it several times, but refused to open any container and test the food itself. TSA allowed Bruce and his parents to fly, but confiscated the baby food.

TSA later admitted the ETD might have given a false positive.

TSA states,

“When traveling with an infant or toddler, passengers are also allowed to bring into the screening checkpoint more than 3.4 ounces of pre-mixed baby formula (in a powder, liquid, or frozen state); … and canned, jarred, processed baby food and essential non-prescription liquid medications. These items also must be declared to a TSO prior to entering the screening area, and the items must be separated from other property. These items will be subject to additional screening, and passengers may be asked to open a container if required by a TSO.”

Then why didn’t TSA test some of Bruce’s food to determine it wasn’t an explosive, and allow the Ankenbrands to keep Bruce’s food for the flight? There is no evidence I can find that indicates TSA no longer stands by this decision.

What’s more, TSA agent’s own poor ETD test methods and conduct can cause false positives too.

I’ve had to request a TSA TSOs change their gloves more than once to prevent their contamination when using an ETD test on my belongings.

Late last year, for example, when my carry-on was swabbed, the TSO was wearing the same gloves she wore when she got a positive scan from the man in the line before me. That alone could have caused a false positive for me. Then she took off one of the gloves by handling its fingers with her hand. I asked the supervisor for someone else to do the test. He professionally agreed and my test was negative.

TSA must review their procedures for ETD testing.

If common household products can easily cause TSA to get a false positive ETD result, then the test is inherently poor and must be refined to eliminate such mistakes which unnecessarily cause air travelers angst, delay, and that maddening enhanced patdown they do, when TSA makes ordinary citizens feel like criminals.

They also have to significantly tighten their test procedures and training to ensure their personnel don’t cause ETD false positives, themselves.

Passengers can reduce their chances of a false positive. Don’t use a product containing glycerine on hands and body shortly before flying. If passengers realize they’ve used such a product, trying using isopropyl alcohol to clean it off.

If pasengers encounter a spill on their bags like my friend the photographer, don’t use a hand cleaner or similar product to clean off the bag. Don’t use baby wipes as they too, often contain glycerin. Use water until arriving home or the next hotel. If passengers accidentally contaminate their bag with a glycerin compound, use alcohol or a cleaner free of glycerine or other potential contaminates to clean the glycerine from the bag.