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(Corrects radiation measurements in ninth and 10th paragraphs in story published March 28.)

March 28 (Bloomberg) -- Airport body scanners pose little radiation risk to travelers, emitting less than 1 percent of the dose a person would get from cosmic rays while flying at high altitudes, according to a report.

Researchers from the University of California said fliers would have to undergo 50 airport body scans to equal the amount of radiation received from a single dental X-ray, 4,000 scans to match the radiation exposure from a mammogram or 200,000 scans to equal that from an abdominal CT scan. Their report is published today online in the Archives of Internal Medicine.

Full-body scanners, which generate detailed and personally revealing images of those screened, have become a controversial feature at U.S. airports because of health and privacy concerns. Passengers should no longer be concerned about the radiation risk from these scanners, author Rebecca Smith-Bindman said.

“I’m convinced that the radiation dose is so low that I go through and I bring my children through,” said Smith-Bindman, a professor of radiology and biomedical imaging at the University of California, San Francisco, in a March 25 telephone interview. “There are lots and lots of things to worry about. The radiation from these scanners is not on the list any longer.”

The Transportation Security Administration has deployed 486 scanners at 78 airports, according to the paper. By the end of this year, about 1,000 scanners will be deployed, depending on budget approval. Body scanners in U.S. airports are made by New York-based L-3 Communications Holdings Inc. and Hawthorne, California-based OSI Systems Inc.’s Rapiscan.

Safety Systems

The TSA said on its Web site that the machines have safety systems in place, similar to a circuit breaker in homes, to prevent the production of radiation levels higher than the established limits. Manufacturers must perform radiation tests on each scanner before it leaves the factory and once it’s installed in the airport. After installation, periodic radiation tests, at least every 12 months, are done either by the manufacturers or maintenance contractors. TSA employees can also request a radiation test, according to the Web site.

“There really should be no concern,” Ella Kazerooni, director of Cardiothoracic Radiology at the University of Michigan Health System in Ann Arbor, said in an interview. “I would hope a piece like this would eliminate people’s concerns.”

Kazerooni, who was not an author of today’s paper, said the government needs to do additional testing to make sure the devices are being used right and calibrated correctly so that the lowest levels of radiation are being used.

Radiation Estimates

Smith-Bindman estimated the potential radiation of airport scanners at 0.1 microsievert. The population is exposed to about 6.2 millisieverts of radiation each year, half from natural sources like the sun and the rest from other encounters such as medical imaging, Smith-Bindman said.

A six-hour flight, for example, would expose a passenger to 14.3 microsieverts of radiation, the study found. Flying exposes passengers to more radiation than the scanners because they get closer to the sun.

The researchers also estimated the cancer risk to be nominal. To calculate that risk, the researchers assumed that 100 million people will take 750 million flights a year and undergo a full-body scan each trip.

For all flyers, or 100 million passengers, six cancers over their lifetime could result from airport scanners, the researchers wrote. However, 40 million cancers overall will develop over their lifetime separate from exposure to body scanners, they said. For frequent fliers, who fly 60 hours a week, four additional cancers could occur because of the scanners.


Richard Morin, chairman of the American College of Radiology’s Safety Committee and a professor at Mayo Clinic in Jacksonville, Florida, said radiation isn’t well understood.

“The levels we’re talking about are lower than actual background radiation,” said Morin, who wasn’t involved in today’s report. “I would certainly not worry about the radiation. I would be reassured that it’s good to check for bombs. I’d like to make sure that there isn’t a terrorist on board.”

To contact the reporter on this story: Nicole Ostrow in New York at

To contact the editor responsible for this story: Reg Gale at

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