Full-body scanners pose 'exceedingly small' radiation risk, says new study

As Japan brings radiation into daily headlines, a new report from biomedical researchers finds that full-body scanners emit 'extremely small' doses of radiation, posing very little health risk to fliers.

Mark Lambie / The El Paso Times / AP / File
An unidentified passenger participates in a full-body scan at the El Paso International Airport in this November 2010 file photo. A report released Monday says that radiation exposure from the X-ray full-body scanners poses very little health risk.

Airport full-body scanners pose little risk to human health, according to an analysis by medical experts published Monday.

But the report, published in the Archives of Internal Medicine, appears unlikely to end all debate over the controversial devices. For one thing, the report didn't rate the health risks as zero. Also, easing concern about radiation levels doesn't assuage another worry: that the detailed full-body scans are an invasion of traveler privacy.

"The radiation doses emitted by the scans are extremely small; the scans deliver an amount of radiation equivalent to 3 to 9 minutes of the radiation received through normal daily living," wrote Pratik Mehta of the University of California, Berkeley and Rebecca Smith-Bindman, a medical doctor at the University of California, San Francisco in the new report.

Still, the researchers say, their models showed that even such small doses of radiation can be expected to result in some additional instances of cancer –perhaps 6 instances over the lifetimes of 100 million people who travel. For context, that's far fewer than the cancers they expect linked to excess radiation caused by flying at high altitudes, and an almost imperceptible fraction of cancers expected in that population overall, from any causes.

"In medicine, we try to balance risks and benefits of everything we do, and thus while the risks are indeed exceedingly small, the scanners should not be deployed unless they provide benefitimproved national security and safety," Dr. Mehta and Dr. Smith-Bindman write. That question "is outside the scope of our expertise."

They said passengers should not fear to go through the scanners for health reasons.

The analysis comes as radiation is in the news for several reasons:

The radiation questions regarding body scanners focus on one type of machines the TSA uses, so-called backscatter X-ray scanners.

The other type, which also generates a detailed outline of the body for the purpose of identifying potential contraband items, are called millimeter-wave scanners. These emit low-energy waves with a fraction of the energy of a cell phone. Medical scientists do not consider the millimeter-wave machines a health risk.

Some researchers, even while acknowledging that the backscatter machines have few health risks, recommend greater use of the millimeter-wave scanners instead.

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