reusing test strips
 

Watching a clerk at ATL right now.
He is standing by the document checker and swabbing hands as people pass by.
He has 2 test strips - and he alternates between them. He swabs hands and puts the test strip in the machine. When the test strip exits the machine, he puts it on top of it and reuses it on the next traveler as the other strip is in the machine.
He is also not wearing gloves...

His buddy just took over and is following the same procedures.
Third clerk in a row now doing the same thing.
And so is the fourth one. However, we have now upgraded to rotating 3 test strips.

Further proof, not that we need it, that TSA-provided security is a farce.

Who is the FSD at ATL? I'd send him a copy of your post.

Which reminds me: is there a list of all FSDs that can be accessed by the public?

You're probably on your flight by the time I post this, but if not - ask a passing TSO if he can call the TSM for you. Be all happy-smiley-politey about it, and when the TSM gets there, ask why his TSOs are failing to follow proper SOP by not wearing gloves and by re-using test strips.

It will also be good to record some of this silliness with your phone, but I recommend being unobtrusive about it. You know how TSOs get when they are recorded screwing up or breaking rules.

I've tried to find one a few times, and there is definitely not one on the TSA web site - though there are numerous press releases any time somebody gets a promotion to FSD. Finding the name of any current FSD is difficult, and finding their actual contact information is darn near impossible, unless you have some direct connection to the airport.

Now you've got me thinking - what would a TSM say if you asked for he name and contact info of the FSD's office at their airport?

Acting ATL FSD as of Sept 2013: Paul Armes (Old News)
 

As you might expect, he's a piece of work. I have no idea if he is still there. You can try "[email protected]" and see what happens.

Upon further review, it turns out the TSA sent him to SLC. Makes you proud to know that there are completely dedicated and mobile TSA SESs out there. :p

Never mind the FSD, don't we have someone from the TSA who has joined us here on FT officially? Granted, if there was a picture or video of the screeners in action, it would be even better (& harder to discount!).

I have taken some pictures on my cell phone. I'm not sure how to post them but I will look it up.

Might get better results with a tweet.

I dont use twitter... yet :)

Yes, but he's public relation, not management, so the best he can do is say he'll pass the report on to management for potential investigation. Internal TSA disciplinary action is not cleared for release to the public, so even in the unlikely event that the report goes anywhere and does anything, he wouldn't be able to tell us about it.

Much like a public complaint, however, I'd expect such a report to GNDN at warp speed.

TSA certainly does - did you see the list of accounts Ross posted?

I have not... Never really looked into twitter.

Ross posted the TSA twitter accounts elsewhere on this forum as another way to post questions and get answers.

It's not going to cause a false positive--if it didn't detect once it won't detect the next time.

It could pass other contamination, though.

Reusing a test strip, just like re-using hand and shoe swabs, can cause a false positive.

Let's say item one is swabbed with a swab and does not alarm. Then the same swab is used for swabbing a different item from another pax and it also does not alarm but when using the same swab for a third item from third pax, the combination of the residue from both the first and second swabs with the residue of the third item sets off the alarm. It's basic chemistry where A is good, B is good and C is good along with combining A & B but when you combine A, B AND C, you have a problem

Agreed on both counts. I thought that SOP was to re-use test strips, but to spray them with alcohol between uses. At least, that was my impression of the SOP last time I got my hand swabbed in the PreCheck lane.

Those random checks are infrequent enough that misting with IPA between swabs actually has time to sterilize the swab. Alcohols at 70% concentration will kill most germs in 10-15 seconds. But if they are swabbing everyone as they pass through the TDC, and depending on how thoroughly they douse the test strip, an alcohol protocol may not be sufficient to prevent the spread of germs.

I tend not to get too fussed about germs, and I think that people overuse hand sanitizers. The handles on your luggage are probably just as filthy as your average passenger's palm. So even if the swabs are not sterilized, it's near-zero risk compared to other risks you regularly take. (Like touching the filthy tray tables and seat-back pockets in your airplane seat...)

If they are swabbing personal medical equipment, I would insist on watching them sterilize the swab first if I had a compromised immune system.

Disagree. These detectors work by detecting molecules and portions of molecules, based on their weight and charge. A and B and C are separated by weight and electronic charge in the analysis chamber, so they are detected individually. The physical mixture of components cannot cause a false positive, because the detection technology functions by separation of different molecules.

The only way what you're saying could be true was if there was a chemical reaction between A and B that produced C, where C was explosive but A and B were not. And I assure you, those reactions are MUCH too difficlut to occur between trace levels of reagents in the open air on a cloth swab. To make an explosive out of ingredients that would not be detected as explosives themselves, you need to convert less energetic molecules into high-energy molecules, and that usually requires high temperature, high pressure, catalysts, appropriate solvents, etc.

Agreed. However, substances not present in sufficient quantity in a single swipe can build up to detectable levels over several swipes.

This.

And, there is an additional concern. I have been told that alarms are generated on quantities of specific chemicals. In addition, there is an alarm for a lower level of two chemicals that may be found in combination in certain explosives. Crude example: Nitrates alone may alarm at a 10. Toluene my alarm alone at 8. However, nitrates and toluene together may alarm at lower levels, 6/4. (All numbers are made up just to create a scenario for example.)

Let's suppose a series of passengers using clean swabs would have the following:

Passenger A: Nitrate 7, Toluene 0
Passenger B: Nitrate 1, Toluene 0
Passenger C: Nitrate 1, Toluene 5

None of these would alarm. However, if consecutive swabs are used:

Passenger A: Nitrate 7, Toluene 0
Passenger B: Nitrate 8, Toluene 0
Passenger C: Nitrate 9, Toluene 5

Absolute levels are under alarm for individual chemicals. Put the two together and an alarm is generated.

I often am around toluene in my work. It is a primary component of TNT, Trinitrotoluene.

I alarm periodically on the ETD and was once told that it was the combination that was the problem. So, I scrub well before going through the CP after being around toluene. It may or may not help. I also noticed a customer using a 35% hydrogen peroxide solution. Oh well. I cleared fine that time.

Finally, I do industrial testing. The multiple use of sterile, calibrated swabs is stupid on top of being prohibited practice for this type of testing. I would not want to be in a line of a sobriety checkpoint in which the blood alcohol level was added from test to test and then I hit the .08. Same thing. Just as stupid.

Heck, all you need is two guys in a row who fertilized their lawns before heading to the airport.

look straight ahead and keep walking
 

Be careful spending too much time watching TSA clerks do their jobs. They get suspicious! :D


http://http://www.flyertalk.com/forum/checkpoints-borders-policy-debate/1405341-tsa-caused-me-miss-my-flight.html

I do a fair amount of Industrial Hygiene sampling as well. The fact that TSA clerks are reusing sampling media proves that there is no scientific point to what they're doing, and it's merely for appearance. When being swabbed, I usually ask what their qualifications are to perform this test (ie, are you a Certified Industrial Hygienist, do you have any educational background in chemistry or toxicology, what chemical are you testing for and what is the PEL/TLV for that substance, when was the machine last calibrated, etc). I just get blank stares.

Note that the liquid bomb plot that the American and British governments fabricated to start the war on liquids involved concentrated hydrogen peroxide as an explosive. The ETDs do not test for this at all.

Add to that two facts: (1) You need lab conditions for a time longer than any flight to manufacture TATP. (2) It is too unstable to transport to the airport -- slam a car door too hard and you disappear into a fine red mist.

If you are doing trace detection, say ppb or ppt levels, whatever method you are using to ionize or vaporize the molecules has to remove virtually everything ionizable or vaporizable from the swab.

Yes, I understand that they look for certain components in combination, but you are assuming that there is anything left on the swab after the ionization step, and I'm not sure that's a valid assumption.
There is a huge difference between measuring precise and accurate concentrations versus simply detecting the presence of a substance. I can't say for certain that you're correct or incorrect, I will do some more research and see if I can intelligently agree or disagree with you.

Just to stir the pot, it looks like TSA claims they do not reuse swabs when they are used to test hands:
http://blog.tsa.gov/2010/02/what-hap...rm-during.html
So we can at least agree that there is a discrepancy there. :D

http://onlinepubs.trb.org/onlinepubs...p_rpt_86v6.pdf

Interesting facts:
--huge numbers of false negatives (e.g. 30%). However, they were testing at or below the advertised detection limit for many of the samples.
--the manufacturer states that swabs can be used up to 10 times unless they are dirty or contaminated. It was unclear whether swabs were re-used in the test protocol.
--warmup time for the machines is 10-15 minutes, but it can take up to 25 or 30 minutes to stop registering false positives for NO3. (a useful factoid if they turn on a machine and immediately run your swab and get a false positive, which happened to me once...)
--inexpensive nitrile gloves are a known contamination source, and are NOT recommended for use with this system
--False positives run about 1.7%. The sites where the tests were conducted included bus depots and other locations expected to have higher levels of environmental contamination that an airport checkpoint

This patent application suggests that the swabs used by the most common manufacturer are baked Nomex fabric:
http://www.google.com/patents/EP1844189A2?cl=en

Based on the manufacturer's guidelines that swabs can be reused 10 times, based on the fact that an extremely heat-resistant fabric (400 C / 750 F) is used to make the swabs, and based on the description of the analysis process, I have to conclude that the swabs are heated far past the vaporization temperature for any explosive material during the testing process. That would mean that virtually all of the vaporizable residues are removed from the swab during the sampling process.

It would also mean that any swab run through the machine is probably sterile... at least the part that got heated.

Thanks for the correction. My error has been noted and I appreciate the accurate info.

You missed the "unless they are dirty or contaminated" part. None of us just walked out of a clean room. We are all dirty and contaminated. Wiping the swab on a person's hands, clothing, luggage, computer, etc exposes them to dirt and contamination. The first time they are used. Even common sense should tell you that you don't reuse sampling media.


"probably sterile" is not a scientific term. It either is sterile (which can be verified) or it isn't. If you don't have the documentation via testing that it's sterile, then it isn't.

Walked through security in DEN yesterday and saw something similar. The clerk who was staffing the line where selectees get pushed ino pre-check was alternating between 2 test strips.

After I went through security, I asked the three-striper at the desk and his answer was as follows: "The manufacturer told us we can keep using the same strips as long as we want to. Typically, we would swap them out when they get dirty."

Sigh. Different applications and different analysis techniques frequently re-use sampling media. "Dirty" generally refers to gross (i.e. large) particulates that are not vaporizable (i.e. visible soil) and 'contaminated' generally refers to a previous positive test result.

These swabs are DESIGNED to be re-used. Period. I'm sorry you've never dealt with an instrument or analytical technique where that is true.
I did not say 'almost sterile', I said 'probably sterile'.

When our lab has done work to design surgical prototypes, and they are being tested on animals, one process we have used on parts that cannot be autoclaved is to soak them in 70% alcohol for 10 minutes. We don't verify sterility of the prototypes, but we assess that they are 'probably sterile' after we use a process that is likely to sterilize them. Would we use the instruments on humans under those conditions without validation? No. Are they 'probably sterile'? Yes.

These swabs undergo brief, intense temperature spikes that are likely to sterilize them. It's analogous to running a needle through a flame before you extract a splinter.

That's all well and good in the case of preventing living things, i.e. bacteria and viruses, from being retransmitted and causing disease outbreak. Heat and alcohol kill dangerous biological organisms, but they don't always destroy or alter or remove the chemicals that the ETD machines are looking for.

There is also the issue of cumulative contamination, and while I don't think it's a terribly pressing issue, I can't completely discount it.

Let's also consider the possibility of cross-contamination through repeated handling by TSOs who fail to change gloves more than once a shift. Swab is used multiple times, swab is left on the table in between uses, swab is handled by multiple TSOs with filthy, unchanged, possibly contaminated gloves...

Then, of course, there is the possibility of a contaminated swab transmitting chemicals to a clean test subject on the first pass, and all subsequent tests using clean swabs picking up the contaminants that were deposited by a tainted swab in the first place.

Cross-contamination is the real issue, and the only way to prevent cross-contamination is to exercise proper testing procedures which include environmental controls around the test equipment, consumables, operators, and test subjects. I.E., make sure that gloves and swabs never come into contact with anything other than one single test subject, ever.

I don't know why this is so hard an issue for TSOs to grasp. They obviously understand it when they scream at cleared pax for touching uncleared pax ("They could have passed something off when the parent hugged the 3yo! We have to grope them both again from scratch! 9/11! 9/11! 9/11!")

Your proposed process (pulling a swab straight out of the box and using it only for one thing, then discarding) would actually tend to have more false positives, due to manufacturing anomalies / residues. For sampling media designed for re-use and used correctly, a track record of no positive signals is a much better predictor for no false positives than something being 'new'.

My heart rate actually goes up when I see a clerk opening a new box of gloves, putting them on and commenting that they got clean gloves. Huge recipe for a false positive. I want them to pull a new pair of gloves out of a box that is 90% gone. That means that they have had 45 tests where no one suspected the gloves were causing a false positive. @:-)

To put it another way... given the current equipment and procedures, and given my knowledge of the analysis technique, if I was in the ETD line and the TSO asked me, "This swab has been used 9 times and they were all negative, would you like me to use a fresh swab?" my answer would be "No, use the old swab."

Could a better process be designed? Probably. There are often compromises in a 'production' or 'real-life' environment that do not live up to the standards of peer-reviewed, publishable science. Would a process that meets laboratory-level scrutiny be cost- or time-effective? Almost certainly not.

That's all I can say on the subject. <shrug>

Thank you so much for that information, janetdoe!
I have a very serious question: Would it behoove you to insist that they first tested the new gloves that they pulled out of the newly opened box before they touched you or anything else at the checkpoint? (I am aware that that question might put you in jeopardy of the "That's not the way we do things at this airport!" retort, and possibly the "Do you want to fly today?" question.)

Do I smell a quality control engineer?

Well, that makes a lot of sense... IF instances of testing materials and gloves which are contaminated from the factory are greater than instances of cross-contamination from multiple uses in an uncontrolled environment where thousands of people per day walk by and the testers are careless untrained louts who wear their gloves to the food court, the bathroom, on smoke breaks, everywhere else.

Then yeah, I'd say used testing materials would be a better option than new testing materials.

You should always ask them to swab their gloves and get a negative test before they touch you. It is the appropriate protocol, and I have had a false positive once when they failed to do it; later they figured out it was the box of gloves. You can use that as your story if they argue.
Materials Science, but definitely some exposure to the topic. :D