X Rays

[NHAKHOA]

[NHAKHOA]

Radiation Exposure from Airport Body Scanners

By Simeon Margolis, M.D., Ph.D.

Stimulated by the recent failed bombing attempt on a plane landing in Detroit, the U.S. Transportation Safety Administration (TSA) plans to subject airline travelers to whole body scanners to detect hidden explosives. The public has mostly responded favorably to these plans to improve the safety of airline travel. While the most common objection has centered on privacy issues, there are also concerns about exposure to radiation from the x-rays used in the scanners. Internet comments on this issue have ranged from alarmist statements about "frying" flying passengers to reassuring remarks by experts knowledgeable about radiation dangers who believe that the radiation doses from airport scanners are inconsequential.

How much radiation is too much?

The opinion of experts on this topic is supported by information from the maker of a type of airport scanner called a back-scattering x-ray machine. The manufacturer says that these machines emit only three microRems (ƒÊRms)--a standard measure of radiation--for each scan. According to the The American Nuclear Society and the U.S. Environmental Protection Agency, radiation exposure is much greater to passengers once the plane leaves the ground, amounting to about 1000 ƒÊRms for each 1000 miles of jet travel. In addition, the average annual radiation exposure from natural sources of 360,000 ƒÊRms is many-fold greater than that from an airport scanner.

Examples of other radiation exposures include:

¡1000 ƒÊRms from a dental x-ray
¡6000 ƒÊRms from a chest x-ray
¡400,000 ƒÊRms from a barium enema to look for colon cancer
¡The NIH Cancer Institute states that mammography procedures "use very small doses of radiation" and "the risk is slight". However, according to one calculation annual mammograms beginning at age 40 and continuing for 50 years would expose each breast to 1000 to 2000 millirems or 1 to 2 million ƒÊRms.
Risks are minimal, but...

These figures convince me that even numerous airport scans are associated with minimal risk compared with our exposures to other sources of radiation. Nonetheless, it is well-recognized that biological ill effects of radiation are cumulative over time, and one could argue that every additional bit of radiation poses a potential danger for cancer and other medical problems. Given this, I think the public would be well-served by an official statement from the TSA concerning the safety of airport scanners based on their own tests of radiation rather than data provided by manufacturers. In addition, the scanners should be checked periodically for possible scattered radiation.

Whole body scanners now in place throughout the U.S.

According to the TSA, 40 scanning machines are now in place across the country, about an additional 150 have been purchased, and funding is in place to purchase 300 more units at approximately $170,000 per unit. I would be more assured that these costs and the inconvenience to travelers are justified if the TSA would provide some information on how effectively these scanners would detect and thwart bombing attempts by dedicated terrorists--who are neither stupid nor lacking in innovative ways to get explosives onto an airplane.