Airport scanners pose no significant radiation threat to air travelers, according to a study published the March 28 online issue of Archives of Internal Medicine.
"Based on what is known about the scanners, passengers should not fear going through the scans for health reasons, as the risks are truly trivial," write authors Pratik Mehta, of the University of California, Berkeley, and Rebecca Smith-Bindman , MD, of the University of California, San Francisco. The researchers add that radiation received during a typical airport full-body scan is equivalent to the background radiation of about nine minutes of flying time.
In the study, Mehta and Smith-Bindman estimated the risk of radiation exposure among three groups of air travelers: all flyers, frequent fliers, and five-year-old girls who frequently travel on airplanes. The latter hypothetical group was selected because children are more sensitive than adults to the effects of radiation, and existing breast cancer prediction models were available. For every two million girls who travel one round trip per week, one additional breast cancer could occur from these scans over their lifetime, compared with 250,000 cancers that would be expected to develop otherwise, given a 12% lifetime incidence of breast cancer.
The researchers assumed that all passengers undergo a full-body scan for each trip, that 100 million unique passengers will take 750 million flights in a year, and that the exposure of the scans is 0.1 µSv. They write that among the 750 million trips per year taken by 100 million airline passengers, an estimated six cancers over the lifetime of these individuals could result from the backscatter scans, compared with 40 million cancers that would normally be expected in the population, the authors wrote. They add that among the 1onemillion frequent fliers who take 10 trips per week for a year (each trip lasting six hours), four additional cancers could occur from the backscatter scans, compared with 400 000 cancers that would normally occur.
The U.S. Transportation Security Administration (TSA) moved forward with its plan to install full-body scanners in airports following an attempted bombing by a passenger smuggling explosives concealed in his underwear onto a Detroit-bound jet on Christmas Day 2009. To date, the agency has installed 486 scanners in 78 U.S. airports, with 1,000 deployments planned by the end of 2011.
."If individuals feel vulnerable and are worried about the radiation emitted by the scans, they might reconsider flying altogether,” Mehta and Smith-Bindman conclude. “Most of the small, but real, radiation risk they will receive” in the course of airplane travel “will come from the flight and not from the exceedingly small exposures from the scans.”