Part 1:
Are They Constitutional?Part 2:
Are They Safe?
Part 3: Do They Work? March 8
John Sedat, a biochemistry and biophysics professor, says he’s not going to get on an airplane again — at least not until the TSA rethinks its deployment of hundreds of body scanners that hit travelers with a tiny amount of radiation.
“I’m not going to go through these machines. And I’m not going to be groped either,” the 68-year-old University of California, San Francisco, scientist said in a recent telephone interview. “Us older people are probably only one mutation away from melanoma. I’m not going to go through these machines and basically ask for the problem. We all know the older you get the more sensitive you are to sunlight and X-rays.”
Sedat is the most outspoken member of a small community of scientists raising health alarms over a type of ”advancedimagingtechnology” scanner installed at U.S. airports. Already controversial on privacy grounds, the AIT scanners allow airport screeners to see through apassenger’sclothing to check for concealed explosives and weapons. They’re the subject of a high-profile lawsuit by theElectronic Privacy Information Center set to be heard by the U.S. Court of Appeals for the District of Columbia Circuit on March 10.
The EPIC lawsuit argues that the machines are invasive, ineffective and unsafe. “I view this as an uncontrolled radiological experiment,” said John Verdi, an EPIC attorney on the case.
For Sedat, the alleged safety issue is the important one. Of concern to him and other health critics are thebackscatterX-ray body scanners produced by Rapiscan Systems, which the TSA began rolling out last year. They constitute about half of the AIT machines deployed.
Unlike the competing millimeter-wave technology produced byL-3 Communications, the $180,000 Rapiscan machines expose travelers to a small X-ray dose.The TSA and Rapiscan say the machines are safe. But in an April letter to the White House, Sedat and fellow UCSF academics argued the government did not adequately study the backscatter X-ray devices.TheTSA has ordered 500 of the Rapiscan devices at about $180,000 each. About 250 of them are already in use across the country.
“As longstanding UCSF scientists and physicians, we have witnessed critical errors in decisions that have seriously affected the health of thousands of people in the United States” (.pdf), they wrote, noting the failure of the Centers for Disease Control to recognize the risks of blood transfusions at the outset of the AIDS epidemic. “These unfortunate errors were made because of the failure to recognize potential adverse outcomes of decisions made at the federal level.”
Rapiscan provides these radiation dose comparisons. The scale is in
The TSA declined to be interviewed for this story. But in court documents and on its website, the administration refers to a host of studies suggesting the machines are safe.”The potential health risks from a full-body screening with a general-use X-ray security system are minuscule,” John McCrohan, the FDA’s deputy director for radiological initiatives, wrote the White House in October in response to the San Francisco scientists’ concerns.
The Johns Hopkins University Applied Physics Laboratory, which analyzed the Rapiscan 1000 at the company’s Los Angeles office, published the leading and most often-cited study (.pdf) in October.The 49-pagereport,released in a redacted form,concludes that the machines leak virtually no radiation to TSA staff and nearby passengers, and expose the traveler being scanned to only a fraction of the maximum exposure level deemed medically safe.
“You would have to go through the scanner 1,000 times to equate to one medical X-ray,” said Peter Kant, Rapiscan’s executive vice president, summarizing the study. “You get twice as much radiation when eating a banana than when going through the scanner.”
Sedat counters that the mechanical beam’s intensity level has not been published, making it impossible to evaluate the safety claims. “I want a real hard number in terms of photons per some unit of area,” he said. “The one physical quantity that is crucial for determining what dose a person is getting, that data is missing.”
Moreover, standard medical X-ray machines disperse radiation throughout the body, whereas the airport scanners penetrate to about skin level. That means there is a high concentration of radiation on a single organ — the skin — which was not accounted for in the Johns Hopkins report, Sedat said.
The “correct way” to test any such technology, he said, is to use mice “and appropriate tissue-culture cells and see if there is a biological response.”
“That kind of stuff has never been done,” he said.
Arizona State University physicist Peter Rez, a leading authority on X-ray technology, agrees on that point: More studies should be conducted before the machines become even more widely deployed to U.S. airports.
It’s a debate that plays out in the statistical hinterlands. Many critics of the technology agree that the increased cancer risk to any individual traveler is infinitesimal. But U.S. airports handle 700 million passengers annually — a large enough number that a small uptick in overall cancer risk can scale to a real-life concern.
Left: Backscatter X-ray scan. Right: millimeter-wave scan.
If the scientist critics are right, then it boils down to the cold calculus of whether more lives are saved by the marginal increase in security than are put to risk by the marginal dangers of the technology.
“Your probability of getting blown up by a terrorist is probably lower than getting cancer from these,” Rez said.
David Brenner, who heads the Center for Radiological Research at Columbia University, said he might favor the X-ray scanners if the government used a safer alternative that performs the same function: namely, the millimeter wave scanners, which “as far as we know, have no known safety issues associated with them.”
“I have argued that it is reasonable to suggest that X-ray backscatter scanners are ’safe’ for an average individual, and probably so even for a child, a radiosensitive individual, or a very frequent flier,” he said in an e-mail interview. “So I would agree with Hopkins and the FDA. But I have also argued here that the move from using these scanners as a secondary screening measure to their use as a primary screening measure, with the potential for up to one billion whole-body X-ray scans per year in the U.S., may profoundly change the likely … long-term population cancer risk.”
“As I said before, if there were no alternatives, X-ray backscatter systems might still be reasonable, in terms of balancing benefits and risks,” he wrote.
Rapiscan and its parent OSI Systems, and their subcontractors have donated a combined $1.75 million to federal politicians in the past decade, according to data provided by the MapLight Foundation, of Berkeley, California. Rapiscan and OSI also spent $2.2 million in lobbying from 1998 to 2010, MapLight found. (Here is spreadsheet forpolitical and lobbying expenditures (.xls)for L-3 Communications and for Rapiscan-OSI.)
The company even retained former Department of Homeland Security chief Michael Chertoff as a lobbyist. Chertoff has emerged as a huge proponent of airport body scanners. He wrote in a Washington Post editorial last year that the government should “fund a large-scale deployment” of the devices. His opinion piece, which touted that the devices detect explosives and plastics, did not mention Chertoff’s previous work for the company.
Kant, Rapiscan’s executive vice president, stands behind the scanners.
“I feel completely safe,” he said, “with my family going through these.”
