One of the 'hottest' issues in worldwide air travel security is the use of the so-called full body scanners. Are airport scanners safe or not?

There are currently two types of scanning systems. Millimeter wave technology which uses low-level radio waves (RF) with two rotating antennae scanning passengers from head to toe and backscatter technology which uses extremely weak X-rays (ionizing radiation) that penetrate only about 1/10 (0.1) inch of the skin. Travelers walk between two large boxes, and with hands overhead are scanned for about 8 seconds. ^1,2

Not surprisingly, because of the ionizing radiation dose from the more prevalent backscatter machines, most of the health concerns have focused on this technology. Although millimeter wave scanners emit EMF, which in itself is also controversial – look at the wireless mobile phone industry, FDA scientist Abiy Desta says  “millimeter wave security systems that comply with the limits set by the Institute of Electrical and Electronics Engineers in the applicable non-ionizing radiation safety standard cause no known adverse health effects." ^3,4

The following sources, albeit they are from the burgeoning industry itself, contend that the scanners pose no significant radiation hazard and represent only a small fraction of one's annual exposure to background radiation. ⁵

According to Rapiscan, one of the largest purveyors of airport security equipment,  “a full body scan of the Secure 1000 produces approximately 3 microREMs of emission. This is equivalent to the exposure every person receives each five minutes from naturally occurring background environmental radioactivity.” This is also equivalent to the radiation one receives flying in an aircraft for two minutes at 30,000 feet. ⁶

To put this into further perspective “one receives an effective dose of about 3 mSv (3 milliSv) per year from naturally occurring radioactive materials and cosmic radiation from outer space” which is about 30 chest X-rays (One chest X-ray=0.1mSv) and ‘the added dose from cosmic rays during a coast-to-coast round trip flight in a commercial airplane is about 0.03 mSv,” 1/3 the radiation from a chest X-ray.  It appears one would have to undergo about 1000 full body scans to equal the radiation dose from just one chest X-ray, provided the ‘scanners’ are working properly!

The American College of Radiology (ACR) comments are similar to Rapiscan’s official statement. “Backscatter technology uses extremely weak X-rays delivering less than 10 microREM of radiation per scan – the radiation equivalent one receives inside an airplane flying for two minutes at 30,000 feet. An airline passenger flying cross-country is exposed to more radiation from the flight than from screening by one of these devices.” ⁷

The TSA has stated that the ‘advanced imaging technology is safe and meets national health and safety standards’ and that ‘all results confirmed that the radiation doses for the individuals being screened, operators, and bystanders were well below the dose limits specified by the American National Standards Institute (ANSI)’. ⁸

The National Council on Radiation Protection and Measurements (NCRP) conducted a study on “radiation-producing devices that are being evaluated for various uses in screening of humans for the purpose of security”, including the full body scanners and has reported that a traveler would need to experience 100 backscatter scans per year to reach what they classify as a Negligible Individual Dose. The study results were published in a Presidential Report which provides some guidelines and recommendations on the allowable radiation doses for the backscatter technology. ⁹

An effective dose of 0.1 uSv (microSievert) or less per scan is the basic criterion that would distinguish between general-use and limited use scanning systems. Again to put this into perspective one would have to have 1000 body scans to equal the radiation dose of one chest X-ray (0.1 milliSv). In addition, the report also addressed limits on radiation exposure, not only of passengers but also of the security personnel operating the machines.

The UK Health Protection Agency, Centre for Radiation, Chemical and Environmental Hazards in early 2010 states “The effective dose from one scan from an x-ray backscatter unit (single or double scan) is 0.02 micro Sv or less (worst case scenario). Effective dose is a quantity that integrates radiation dose across the whole body. This dose is a small fraction of the annual background radiation.” ¹⁰

In lockstep with the scanner industry, Dr. Francis Marre, former director of radiation safety evidence at the Massachusetts Institute of Technology, stated “in terms of radiation exposure, airport scans cannot be as more harmful than the radiation we are exposed to every day, including from radiation from our drinking water, buildings, and even from other people”. ¹¹

If the evidence indicates that airport scanners do not pose any significant health risks, what are people all worked up about?

First of all, the supporting data primarily comes from the industry itself – we all know too well what that can entail – aka the tobacco industry. Overall radiation exposure is increased, no matter how negligible, adding already to our background and diagnostic radiation exposure which could increase our risk for developing cancer. No one needs more radiation, no matter how small. ^12-14

Current monitoring and regulation of this new industry is still evolving, to say the least. The ‘radiation dose’ assumes that the machines are working properly. What’s disconcerting is there still has been no public disclosure of TSA monitoring despite several requests including the U.S. Congress. One can’t forget the recent publicity engendered when a major U.S. hospital disclosed that their routine scanning machines emitted more than the recommended radiation dose. Even the TSA employees are concerned about their radiation hazards and they are not even being scanned. ^15,16

And, questions remain especially about its safety for use especially in pregnant women, children, the sick and those with disabilities as pointed out by several professors from the University of California, San Francisco. And lastly, it may increase our skin cancer risk. ^17,18

The foremost barrier is privacy. In general, the majority of air passengers are willing to undergo full body scanning but there are some who are not so happy about the technology. Here are some of the objections: ^19,20

A 35-year old woman to USA Today: "To use these scanners, I would feel rather violated. Just hearing that doesn't really make me comfortable."

Others call it the virtual strip search. And some people complain that full body scanners are inefficient, causing unnecessary delays at airports. One passenger complained the system takes three to five times as long as walking through a metal detector. Others object that the technology is not compatible with some cultural and religious beliefs.

The TSA is quick to assure that public that strict privacy safeguards are in place. And in July 2011 the TSA announced it will adopt less invasive technology known as "automated target recognition" otherwise known as ‘stick’ technology. ²¹

Yet, there have been reported cases of misuse and abuse that makes the public a bit wary. In a recent scandal, the U.S. Marshal Service apparently stored some scanner images taken at a section checkpoint at a Florida courthouse. Some of these pictures apparently found their way to the Internet, posted online by Gizmodo. ²²

OK, what are the upsides?

Better security? - The main purpose of full body scanners is to increase security and mitigate terrorism risk. Each of these scanners, regardless of the technology used, generates images of the scanned human body which are anatomically accurate. In doing so, it can detect hidden objects such as weapons and bombs as well as illegal substances (e.g. drugs) concealed underneath people’s clothes. The scanners are especially effective in detecting non-metal objects that conventional metal detectors are bound to miss.

According to the U.S. Transportation Security Administration (TSA), the technology can “detect a wide range of threats to transportation security in a matter of seconds to protect passengers and crews. Imaging technology is an integral part of TSA's effort to continually look for new technologies that help ensure travel remains safe and secure by staying ahead of evolving threats.” As an aside, current airport scanners do not detect objects inside the body cavity. But there is another X-ray using scanner – the transmission scanning system. This latter system is used by customs to check for swallowed contraband goods such as drugs and is also utilized at diamond mines to screen exiting workers. However its effective dose is significantly higher – up to 10- 100x more than the current airport scanners. ²³

Less invasive than a pat down - There are passengers who are not eligible for metal detector tests due to their having medical devices and implants. These passengers are subjected to a “pat down”, a body search manually performed by a security personnel. Many of these people think that a full body scanner is less invasive compared to a pat down.

Faster airport screening - There are also claims that full body scanners might increase the speed and efficiency of the airport security checks. However, there is little data to support or negate these claims. TSA estimates a scan to last for about 20 seconds. However, the International Air Transportation Association (IATA) says it’s more than double and can take at least 45 seconds. ²⁴

Acceptance - A poll conducted by the USA Today in January 2010 indicated that 78% of air passengers support the use of full body scans, mainly for security purposes. A more recent CBS poll in November 2010 showed that 81% (4 out 5) of travelers are amenable to full body scanning at airports. ²⁵

The Bottom Line

The controversy is far from over. And it sure doesn’t help when there is no public disclosure of how the machines are monitored. ^26,27 So for those who believe that we receive enough radiation already from background, cosmic and diagnostic X-rays, here are some tips.

First of all, if you go thru the metal detector don’t set it off! But if you do, opt for a pat-down search as opposed to the scanner. This is actually very important because most passengers think they do not have a choice. You do and the TSA prominently displays this option. However, some airports are not even using the metal detectors anymore and have switched to the scanners, usually the backscatters. Again, opt for a pat-down search.

But, if you are opposed to a pat down, know what type of scanners your airport is using and choose the full body scanner that utilizes millimetre wave technology, if available,  such as the ProVision. Better yet, use an airport without scanners or use a form of transport other than flying.

Maybe it’s time to quit ‘trading one hazard for another’. Bring out the laser screening devices – the technology must be out there somewhere. Where’s George Lucas when you need him?

Published December 30, 2010, updated July 16, 2012

References

1. L-3 Communications, the ProVision™ Whole Body Imager   
2. Backscatter/Rapiscan Secure 1000 single pose, Rapiscan Systems
3. Full Body Scanner, Wikipedia
4. Very Low Health Risks from Full-Body X-ray Scanners, FDA Consumer Updates 4 Nov 2010
5. Radiation exposure in X-ray and CT examinations, RadiologyInfo.org
6. FAQ's Backscatter Rapiscan Secure 1000, Rapiscan Systems
7. ACR Statement on Airport Full-Body Scanners and Radiation, American College of Radiology, 10 Jan 2010
8. Privacy, Advanced Imaging Technology, Transportation Security Administration (TSA)
9. Presidential Report on Radiation Protection Advice: Screening of Humans for Security Purposes Using Ionizing Radiation Scanning Systems, National Council on Radiation Protection and Measurements
10. Facts and figures concerning the use of Full body scanners using X-Rays for security reason, HERCA, June 30 2010
11. How much radiation are we getting at airports? CBS, 30 Nov 2010
12. Airport Body Scanner Truth
13. Whitehead J, Are Body scanners dangerous to your health? The Rutherford Institute, 22 Nov 2010
14. Scientists question safety of new airport scanners, NPR, 17 May 2010
15. The New York Times, Radiation overdoses point up dangers of CT scans, The New York Times, October 16, 2010
16. Lawmakers call on TSA to release X-ray inspection records, USA Today, 7 Dec 2010
17. Letter to the assistant to the President of Science and Technology, University of California, San Francisco, 6 April 2010   
18. Radiation from airport scanners may increase cancer risk, Digital Journal, 23 May 2010
19. Most OK with full-body scanners, USA Today, 11 Jan 2010
20. Backlash grows against full body scanners at airports, USA Today,13 July 2010
21. TSA Takes Next Steps to Further Enhance Passenger Privacy, Press release, TSA, July 20, 2011
22. One hundred naked citizens: One hundred leaked body scans, Gizmodo 16 Nov 2010
23. Adani Systems
24. Guarino M, Airport security: two alternatives to full-body scanners, The Christian Science Monitor, December 31, 2009
25. Poll: 4 in 5 support full-body airport scanners, CBS News, 15 Nov 2010
26. Is radiation from the new airport security scanners endangering my health, The Straight Dope, 5 Nov 2010
27. What the TSA is not telling you about full body scans, NAFWA