The other day, I was discussing a recent vacation to San Diego with a friend. This guy – let's call him Don – is afraid that everything is going to give him cancer – he uses the lowest radiation cell phone on the market, for example, even though it is woefully out-of-date. His most recent crusade is against the x-ray scanners at the airport, which, he insists, cause cancer. He instead opts for the pat-down option over walking through the full-body scan when he flies.
I've known Don for 10 years, so I know he can be a bit of an alarmist. But he did get me thinking: what effect do airport x-ray scanners have on your body? I don't fly that often, but what does this mean to business travelers? There are 244 full-body scanners in use at 36 airports in the United States - are these machines safe?
The case against body scanners
According to one report from PBS/ProPublica, anywhere from six to 100 passengers each year could get cancer from the machines. The study said that any exposure to ionizing radiation – the kind emitted by the x-ray scanners – increases risk of cancer. Though the machines emit fewer than 10 microrems of radiation - which is roughly one-thousandth of the exposure of a chest x-ray-- the National Academy of Sciences has found no evidence that exposure to radiation – even in the smallest amounts – has a zero risk of cancer.
In other words: it's possible that these machines cause cancer.
A 2011 report from the University of Columbia Center for Radiological Research said that one billion x-ray scans per year could lead to 100 radiation-induced cancers. These one billion scans would be accumulated by a pool of 100 million frequent flyers.
In 1999, the Conference of Radiation Control Program Directors, a nongovernmental organization, passed a resolution recommending that the full-body scanners now used in airports be stopped immediately.
In November 2011, the European Union banned use of the body scanners in its airports due to safety concerns. Only England's Manchester Airport continues to use the machinery.
In defense of body scanners
In a 2011 study from the University of California, San Francisco, airport scanners were found to potentially cause up to six cases of cancer over the course of a lifetime in those people exposed to the scanners – which totals over 100 million people. So the risk is tiny, according to this study.
The Transportation Safety Administration swears that the machines are safe, stating that the amount of radiation to which people are exposed is minute and worth the risk – as small as it may be – for the increase in security. The Food and Drug Administration says that the risk of cancer is one in 400 million, citing the National Council on Radiation Protection and Measurements.
The PBS/ProPublica report claimed that the scanners emit under 10 microrems of radiation per scan, while the TSA claims that each scan exposes a person to 3 microrems of radiation. Regardless, the MIT Radiation Protection Office says that up to 5 million microrems of annual exposure is considered safe; 3 or 10 microrems is still a very small amount.
In an article for CBS News, a Mayo Clinic health physicist and spokesperson for the Health Physics Society was quoted that the radiation produced by the machines was "inconsequential."
In response to the claim that with 100 million flyers, 100 cases of cancer will develop when this group is exposed to one billion scans per year, the Harvard Medical School responded that this same group of people will get tens of millions of cases of cancer even before being exposed to the scans. This report found that six additional cases of cancer caused by the scanners are miniscule when added to the estimated 40 million all-cause cancers this group will experience. This report concluded that, "the exposure is so minimal most people will decide that they have more important things to worry about."
Which set of information do you believe? Do you think these machines are safe?** Sources:**
Brenner, DJ. (April 2011). "Are x-ray backscatter scanners safe for airport passenger screening? For most individuals, probably yes, but a billion scans per year raises long-term public health concerns." Radiology. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/21436091.
Grabell, Michael. (November 1, 2011). "U.S. government glossed over concerns as it rolled out airport x-ray scanners." ProPublica.org. Retrieved from https://www.propublica.org/article/u.s.-government-glossed-over-cancer-concerns-as-it-rolled-out-airport-x-ray.
Harvard Medical School. (July 2011). "Are full-body airport scanners safe?" Harvard Health Publications. Retrieved from http://www.health.harvard.edu/family-health-guide/updates/are-full-body-airport-scanners-safe.
Jaslow, Ryan. (November 17, 2011). "Europe bans airport scanners over cancer fears: how about U.S.?" CBS News. Retrieved from http://www.cbsnews.com/8301-504763_162-57326822-10391704/europe-bans-airport-scanners-over-cancer-fears-how-about-u.s./.
Jefferson, Erica V. (November 11, 2011). "FDA responds to ProPublica story on x-ray body scanners." ProPublica.org. Retrieved from http://www.propublica.org/article/fda-responds-to-propublica-story-on-x-ray-body-scanners.
Mehta, P., Smith-Bindman, R. (June 27, 2011). "Airport full-body screening: what is the risk?" Archives of Internal Medicine. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/21444831.
MIT News. (January 5, 1994). "Radiation, how much is considered safe for humans?" MIT Tech Talk. Retrieved from http://web.mit.edu/newsoffice/1994/safe-0105.html.
Rabin, R.C. (August 6, 2012). "X-ray scans at airports leave lingering worries." The New York Times. Retrieved from http://well.blogs.nytimes.com/2012/08/06/x-ray-scans-at-airports-leave-lingering-worries/.