Aviation securityRadiation concerns dog full-body scanners

By the end of 2014, the Transportation Security Administration (TSA) will complete replacing the old airport magnetometer metal detectors with electronic body scanner machines. The exact numbers are yet to be worked out, but we should expect between 1,950 and 2,200 of these scanners at checkpoints in all 450 commercial airports in the United States.

The New York Times’s Joe Sharkey writes that the presence of all these scanners should a discussion about radiation. The concern about radiation has to do with one kind of body scanner that is being installed at airports, the so-called backscatter machines. As of last week, TSA had bought 250 backscatter units, which scan body surfaces using an “ultra low dose” of X-ray radiation, according to the manufacturer, Rapiscan Systems.

TSA says it had also bought 242 other body scan machines that use millimeter wave technology, which does not emit radiation but uses “harmless radio waves,” according to its manufacturer, L-3 Security and Detection Systems.

Sharkey notes that as of last week, TSA said, there were 99 backscatter units and 43 millimeter wave units at 41 airports. The machines cost about $150,000 each.

TSA says that the backscatter technology has been evaluated by the Food and Drug Administration’s Center for Devices and Radiological Health, the National Institute for Standards and Technology, and the Johns Hopkins University Applied Physics Laboratory. The results, the agency said, confirmed that radiation doses for individuals “were well below the dose limits specified by the American National Standards Institute.”

According to the agency, “a single scan using backscatter technology produces exposure equivalent to two minutes of flying on an airplane,” where slightly higher levels of radiation are routine. These safety issues are discussed at the agency’s Web site.

Sharkey writes that others who have studied the technology argue that repeated low-dose exposure to radiation at airport checkpoints is a cumulative risk, and that the safety of the backscatter technology has not yet been adequately demonstrated by impartial research.

In a letter on 28 May, several organizations and individuals, including the American Civil Liberties Union and Ralph Nader, asked Congress to stop deployment of the devices pending “an independent review of the devices’ health effects.”

In April, three Republican Senators, Susan Collins (Maine), Jon Kyl (Arizona), and Saxby Chambliss (Georgia), wrote to the secretary of homeland security, Janet Napolitano, urging the department to evaluate a type of body imaging called auto-detection technology used at Schiphol Airport in Amsterdam.

That technology identifies potentially threatening objects on a person without actually showing naked body images and also “avoids exposing passengers to radiation,” the senators said.

For now, Sharkey writes, the agency is committed to the backscatters and millimeter wave machines. “To me, the obvious question is: Given that the two types of machines are both deemed effective by the T.S.A., why doesn’t the agency just abandon backscatters and use the millimeter wave machines, which don’t pose radiation issues?” he asks.

“I’ll tell you what the T.S.A. told us when we asked,” Nader told Sharkey. “They said, ‘We want to stimulate competition in order to get the best price.’”

The agency does not entirely dispute that. “TSA competitively bids technologies and makes selections through a comprehensive research, testing and deployment process,” said Kristin Lee, a spokeswoman. “Technologies must meet detection standards, and T.S.A. tests these technologies in both laboratory and field environments.”