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January 02, 2010

Full body scans, x-rays, and cancer

There's been a lot of talk about full body scans the wake the abortive Christmas Day crotch bombing. Naturally, any of the biggest scanning proponents also sell full body scanners.

A lot of people are nervous about technology that allows TSA screeners to see them naked.

But nobody seems to be asking about the potential health risks of bombarding passengers with x-rays. Not all full body scanners use x-rays, but the TSA has already ordered some that do.

The thing is, X-rays are carcinogenic. That's why your hygienist gives you a lead apron leaves the room when you get dental x-rays.

(Correction: Nevermind about the mammogram example. Thanks to commenters Kittywampus and Butdoctorihatepink for setting me strait.)

No doubt the risks associated with airport screenings are very low, but the relevant question is about the cost/benefit ratio. We shouldn't have to put up with any additional risk unless there's a significant marginal benefit. Even under the status quo, deaths from airplane terrorism are exceedingly rare.

Nate Silver estimates that odds of an air traveler being involved in a terrorist event on any given flight at less than 1 in 10 million. So, if scans caused even a tiny increase in cancer risk among the millions of people who fly every year, the technology could end up killing more people than it saved.

Presumably, it takes a lower dose of x-ray radiation to penetrate clothing than it does to visualize structures deep inside the body. On the other hand, the risks from x-ray exposure are cumulative. Safety guidelines must take into account the risks for frequent fliers. Maybe it's perfectly safe to get scanned once a year, but what if you fly every week? Full-body scans could become an occupational health and safety issue, since so many frequent fliers are traveling for work. 

Maybe scanners are perfectly safe. However, these devices should be subject to the same rigorous safety testing as a medical device. We shouldn't just take the word of the high priced hucksters who are touting them on CNN.


Modest proposal: seal flyers in a container made of the same material as the black boxes they use to contain the aircraft's flight recorders, before loading the flyers onto the airplane. Granted, most of the flyers will suffocate to death by the time they get to where they're going, but the important thing is that they'll get there in one piece.

The full-body scans don't show explosive containers in body cavities.

The Detroit bomber would have hidden explosive material in his body if he were expecting a full-body scan.

It isn't clear how using scanners which terrorists would be willing-and-able to defeat makes us safer.

I'm not sure I want the same people who approve unsafe drugs and MRIs with disposable parts deciding whether an X-ray scanner is safe.

Personally, I'm pretty sure the cancer risk I get from living in Manhattan is much higher than the cancer risk I'd get from body scans.

I share your concerns about the safety of these scanners. But just to be clear on the risks of mammograms: The panel weighed all sorts of "harms," including those of unnecessary biopsy, overtreatment (including radiation for treating cancers that might never have become invasive), and severe anxiety. However, we don't have very good data on the extent to which mammograms may themselves cause cancers. So it's not true that the panel "decided that the radiation exposure from a yearly mammogram (a kind of x-ray) would kill more women in the 40-50 age bracket than early breast cancer detection would save."

These scanners pose another risk, as well, which has been well described at the epidemiology blog, Effect Measure. Basically, if you want to catch 100% of the potential terrorists (or close to it), the scanner has to be highly sensitive. But high sensitivity leads to a high number of "false positives." Thus, it won't take long until TSA personnel start waving people through secondary screening, since the scanners will typically be crying wolf.

I'm glad you're bringing some attention to these issues.


A nit, but the mammogram furor had absolutely nothing to do with the carcinogen effect of the x-rays used, which are low-dose and now often digital.

It had to do with cost vs benefit. The number of false positives in younger women undergoing mammography is relatively high in comparison with the number who end up with cancer, and the government advisory panel decided that the small number of lives saved weren't worth the expense. They justified this using the excuse that the idea of a biopsy is stressful for a woman. Sadly, there are now many programs following this government advisory and women are not getting needed mammograms.

As a woman undergoing cancer treatment now, I would urge people to get that mammogram anyway. The government may not think your life is worth the costs but I'm sure you do. Any "stress" caused by an unnecessary biopsy (which is a simple and easy procedure) is nothing compared to the stress of mastectomy and chemotherapy.

If the government had done its job and kept this known terrorist off airplanes, we wouldn't even need to be considering the idea of radiation exposure at the airport.

"The arguments are so fierce because the stakes are so small."

This is such an incredible distraction. The risk of flying, even with terrorism, is low. The risk of cancer induced by body scans is low. Compared to the risks of stuff we put up with every day, it's insane that we are even having this discussion. Diseases of the fast and/or unfit (heart attack, stroke, diabetes, and to some extent cancer) dwarf the risks from cars, guns, terrorists, medical X-rays, etc.

A rational person, waiting in a security line at an airport, would pass the minutes doing jumping jacks. I'm sure the TSA would be very understanding, especially after you explained this to them :-).

Even a slight risk from a full-body scan is unacceptable, considering that the marginal benefit of these scans is approximately nil.

Are there any full-body-scanner images on the web of someone carrying a plastic bag with PETN?

I'd like to be able to judge for myself how easy-or-difficult it is spot a-bag-of-PETN with the scanners.

Guns are obvious in full-body-scanner images, but since guns are heavier than plastic-bags-with-PETN, that doesn't answer the question.

If you have a link to a full-body-scanner image of someone carrying a plastic bag with PETN, please post in the Comments.

I'd prefer to take the " risk " of the scanner rather than deal with the rather greater danger of a bomb brought on board by a Muslim bent on mass murder

as we try to point out: the danger isn't "rather greater", this is, well, "rather smaller".
nevermind the strange reference to "a Muslim"


Lets say it like it is.

Those trying to commit these murders in the skies aren't Lutherans from St. Paul, Minnesota. There is a common thread.

Atlanta-Hartsfield/Jackson Airport has a handful of the new full body scanners. They don't send everyone through them, only a percentage and those that raise a flag.

Last week I apparently raised a flag; I set off the chemical sniffer. Given a guess, it was because my carryon bag was once used to transport a large quantity of old-fashioned photographic materials. They did, however, put me through the full body scanner. It only takes a second and it might prevent an attack, BULLSHIT.

Airport security, full body scanners, what a joke.

I can think of nowhere else in the country, baring a prison, where a person has less freedom than in airport security, especially considering how skittish the TSA has been lately. What would have happened if I'd refused to step through the scanner? What if I had a pacemaker? What if I had a plate in my head or pins in my spine and was afraid of what would happen? What if I'm already undergoing radiation therapy and an elevated dose of concentrated X-rays could kill me? Is the nine dollar an hour, high school dropout in the blue uniform prepared to deal with my issues, with the myriad of possibilities that a quarter million daily travelers might encompass, certainly not.

There's so much here that I could go into but I'm not going to take up the space. The point being, this country has developed a habit of trading just about anything for the most incremental feeling of increased safety. There is no cost/benefit comparison going on here. On the rare occasion that such comparisons happen, no one is happy with the conclusion.

Despite the recent incident, and others, you have to admit that the US skies have been a lot safer since September 2001 than any of us had a right to expect. This, despite a jihadist movement aiming at terrorist airplane bombings in many places- London, NY / USA, the Philippines, lots of places.

Thomas, I am critical of some of what goes on, but your incoherent comment indicates that you don't know where you stand or where the world stands today.

Have you read any newspapers since 2001? Or since Christmas Day 2009?

In the next days, I'm flying Newark-Belfast, Belfast-London, and then Heathrow - New York. If the guys at any one of these three airports put me through enhanced security procedures, or if they put me through a secondary check, you won't catch me sniveling on the internet. I know why they do this.

I thank them every time.

From the information presented below, 'the government' was not trying to just save money, (and that would be insurance co. money, not taxpayer money, anyway), by reconsidering the risk/benefit ratio of mammogram recommendations for young women. And regarding airport scanning, looks like not only the unborn and young children will be at risk from non-medical usage of body scans, but also women with genetic vulnerability to breast cancer and a lot of others that have other genetic vulnerabilities that will be triggered by these scans.

American Academy of Radiology:

Mayo Clinic neuroradiologist Peter Kalina, M.D., FACR questions the use of even small doses of ionizing radiation in nonmedical applications. “The amount of radiation may be extremely small and safe, but parents have to grasp that their four-year-old child is being subjected to radiation. Some parents will be concerned,” he says.

Columbia University professor of radiation oncology and public health David J. Brenner, Ph.D., is uncomfortable with the mandatory scanning of untold thousands of pregnant women and children at airports every year. Brenner, an expert in low-dose radiation risk, embraces the ALARA principle that advocates use of radiation “As Low as Realistically Achievable.” Brenner notes that about 5 percent of the general population is radiosensitive, among them women who carry the BRCA1 and BRCA2 breast cancer genes, and individuals prone to ataxia telangiectasia, an inherited neurodegenerative disease that causes severe disability.

Kalina is concerned about a potential scenario in which a less-developed nation might adopt backscatter scanning technology, but fail to keep its scanners calibrated. “As a traveler,” he says, “I don't know who's checked that machine or equipment. Can I be sure there won't be a larger dose of radiation coming from it?”

That concern should not be just reserved for third world airports since our western medical community is just beginning to grasp how exposure from medical scanning has been underestimated.

Safety Investigation of CT Brain Perfusion Scans: Update 12/8/2009

Date Issued: December 8, 2009

Audience: CT facilities, Emergency Medicine Physicians, Radiologists, Neurologists, Neurosurgeons, Radiologic Technologists, Medical Physicists, Radiation Safety Officers

Medical Specialties: Emergency Medicine, Radiology


Device: Multi-slice CT machines.
Summary of Problem and Scope:

On October 8, FDA issued an Initial Communication about excess radiation during perfusion CT imaging to aid in the diagnosis and treatment of stroke. At that time, we knew of 206 patients who had been exposed to excess radiation at one facility.

Together with state and local health authorities, FDA has identified at least 50 additional patients who were exposed to excess radiation during CT perfusion scans. These cases involved more than one manufacturer of CT scanners. FDA has also received reports of possible excess exposures at facilities in other states. Some patients reported hair loss or skin redness following their scans.

If patient doses are higher than the expected level, but not high enough to produce obvious signs of radiation injury, the problem may go undetected and unreported, putting patients at increased risk for long-term radiation effects....

Every so often you hear about a conventional X-ray machine that malfunctioned or was miscalibrated and delivered a radiation dose orders of magnitude higher than intended, seriously injuring the unlucky patient or even delivering a lethal dose.

When that happens it's only one person or at worst a handful of people affected. What happens when one of these scanners similarly malfunctions in a busy security line at DFW or Hartsfield or LAX?

Despite the recent incident, and others, you have to admit that the US skies have been a lot safer since September 2001 than any of us had a right to expect.

US skies have been about as safe since 9/11 than they were in the years before 9/11. The real improvements in air safety happened decades ago, cutting the number of hijackings between the 1970s and the 90s.

It seems that the full-body scanners are only being used for international flights, which on average are considerably longer than domestic flights.

I'm pretty sure that the increased radiation dose that you get from cosmic-rays all those hours at 40,000 feet dominates whatever you'd get from the scanners. Sure, dose is cumulative, etc., but if that's your big concern, stay off the planes (and get out of Denver, too).

Air travel is safer now, but not because of terrorism or security. It's from improvements in aircraft and their operation. Remember TWA840? Blew up in the sky out of JFK. Not terrorism, bad wiring.

The improved safety is not from TSA, but from the NTSB. TSA is just "feel good" security theater. Might as well be wearing your lucky underwear that protects you from tiger attacks.

Snarki, it's not just accidents that are down; terrorism incidents are down as well. In fact, the total number of deaths from violent causes on airplanes was lower in the 1990s than in the 1960s, despite the explosive growth in airplane travel in the interim. The total number of deaths in the 2000s was barely higher, and was much lower excluding 9/11.


It's not just the safety rate that you look at.

Prior to 9/11 the procedure was to reason with a hijacker and to allow him certain latitude as to where the hijacked plane would go.

One day's bad experience demonstrated that this procedure was simply insane - and since it was ended, we're safer on that front.

Future threats from missiles, plastic guns, undetectable chemicals can quickly reverse whatever progress has been made.

And panicking over necessary body scans is completely unhelpful and ridiculous.

Give me an X Ray over a bomb anyday

Phantom, you're talking about two different things. One is how to deal with a hijacked plane; the procedures have changed since 2001 and that's a good thing, in principle, though in practice attempted attacks have not been hijackings. The other issue is airport security, which does not seem to have produced better results.

Just to clarify, the scanners currently in use are not limited to international flights. Atlanta-Hartsfield/Jackson, for instance, does not differentiate between domestic and international passengers as they pass through security.

Full body scanner is not X-ray. It's the new T-ray (terra hertz ray) it's somewhere between radio wave and infra red.

What it can see: it can go through anything soft and thin, non metal. (fabric, plastics, bags, etc)

It cannot penetrate water and metal (body tissue obviously)

Muslims are good people, but Islam is a danger. Muslims are good people despite Islam. However, there never will be a time or place where Islam is not a danger. Islam commands Muslims to subdue and overwhelm the infidel. Terroism, as a tactic, is acceptable to achieve this aim. Islam's god commands this. An irreducible number of Muslims will always believe in this injunction. This will never change. Islam will never change. Muslims are the vector for Islam, therefore Muslims should be excluded from the United States and other western countries. Muslims should not be allowed to emigrate to the United States.

So it'll still show up if I spell out "Fuck the TSA" in tinfoil on my belly?

that will definitely work. But it doesn't have to be tinfoil. A nail polish with different metal or nitrogen compound (aka glitter) will show up brightly too.

each material sort of give different "reflection", different sparkle of color if you will. kinda like if you wear thin orange silk, or colorful shower curtain in visible ray to your eyes. You can see the silk and shower curtain are different material.

The biggest problem with T ray, as you point out. we dont know much about it.

I am sure a terrorist will come up with clever idea, like wrapping bomb with piece of steak (that will pretty much conceal the bomb in the middle) or inserting bomb in body cavity pretty much defeat the whole thing.

there is also privacy concern... we gonna know every movie stars with breast implants in the planet for sure.

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