[Skip to Navigation]
Special Article
June 27, 2011

Airport Full-Body Screening: What Is the Risk?

Author Affiliations

Author Affiliations: Department of Public Health, University of California, Berkeley (Mr Mehta); and Departments of Radiology and Biomedical Imaging, Epidemiology and Biostatistics, and Obstetrics, Gynecology, and Reproductive Sciences, University of California, San Francisco (Dr Smith-Bindman).

Arch Intern Med. 2011;171(12):1112-1115. doi:10.1001/archinternmed.2011.105

In response to a passenger smuggling plastic explosives hidden in his underwear onto a Detroit-bound airliner on Christmas Day, 2009, the Transportation Security Administration (TSA), a department of the US Department of Homeland Security, began pushing forward with its plan to place full-body scanners in all American airports. Thus far, the TSA has deployed 486 scanners in 78 airports in the United States, with an estimated 1000 scanners to be deployed by the end of 2011.

There are 2 types of full-body scanners in use. Each generates a detailed outline of the human body for the purpose of identifying contraband hidden under clothing. The millimeter-wave scanners emit extremely low-energy waves—each scan delivers a small fraction of the energy of a cell phone—and the scanners capture the reflected energy. The backscatter x-ray scanner, the type used more commonly in the United States, uses very low dose x-rays, similar to those used in medical imaging. In contrast to x-rays used for medical imaging in which variation in the transmission of x-rays through the body is used to generate an image, backscatter scanners detect radiation that reflects off of the person imaged. When radiation passes through air, it deposits energy into the tissue that absorbs it, and with the backscatter technology, all of the energy of the scan is absorbed by the most superficial tissues of the body, such as the skin.

Add or change institution
3 Comments for this article
Clinical Professor
Zachary T. Bloomgarden, MD | Mount Sinai School of Medicine
There have been a number of well-publicized incidents of radiation- emitting equipment malfunctioning, causing inadvertent but excessive irradiation of patients from both diagnostic and therapeutic equipment. Inasmuch as equipment in medical centers might be expected to undergo checking with higher frequency than that in airports, have measures been taken to assure the regular testing of radiation output of such scanners to avoid any potential for radiation in excess of the minimal amounts you cite?

Conflict of Interest: None declared
Atmosphere Provides Radiation Shielding
Michael S Rogers, MD | School of Medicine
The statement within the article "Naturally occurring radiation is higher at the altitudes of commercial air flights because of the greater proximity to the sun" is incorrect. The Sun is 150x10E6 Km away from the earth and commercial airliners cruise at altitudes of around 10 Km, where "closer" in this context only applies for airliners cruising within daylit areas of the earth, and for non-sunlit areas the airliners are in fact slightly further away from the sun than observers on the ground beneath them. In either case, the extra distance created by the airliner's cruising altitude is infinitesimal compared to the average Sun-Earth distance. The reason for the higher background ionizing radiation at higher altitudes is due to the increasingly rarefied atmosphere, which provides less scattering and absorption of incoming radiation from astronomical sources (including but not limited to the Sun).

Conflict of Interest: None declared
Why not collect data?
Thanos Halazonetis, DDS, PhD | University of Geneva
Let me first thank the authors for initiating a discussion of this issue in the peer-reviewed scientific literature. However, it seems that the authors did not collect any data of their own or do any experiments. It is very easy to measure the effects of the radiation of these scanners on cells using methodology that my laboratory and other laboratories have developed (for example, Schultz et al., Journal of Cell Biology 151: 1381- 90, 2000). The amount of DNA damage induced by these scanners could then be accurately determined. Why not do these studies?
Conflict of Interest: None declared