An article published earlier this week in the New York Times once again raises safety concerns about backscatter X-ray scanners at airports.
As I reported here in 2011, an analysis published in the Archives of Internal Medicine found that the radiation doses produced by these security-screening devises are too small to pose any significant health risk, even to frequent flyers.
However, the authors of that analysis also made it clear that they based their calculations on the assumption that the machines would operate as designed. Human error or machine malfunctions, they stressed, could alter the radiation doses — and the health risk. Yet, the researchers had no way of evaluating if such errors and malfunctions were occurring because the U.S. Transportation Security Administration (TSA) does not permit independent scientists access to the machines.
That’s exactly the main issue raised in the Times article by reporter Roni Caryn Rabin:
Most experts agree that as long as the X-ray backscatter machines are functioning properly, they expose passengers to only extremely low doses of ionizing radiation.
But some experts are less sanguine, and questions persist about the safety of using X-ray machines on such a large scale. A recent study reported that radiation from the machines can reach organs through the skin. In another report, researchers estimated that one billion X-ray backscatter scans per year would lead to perhaps 100 radiation-induced cancers in the future. The European Union has banned body scanners that use radiation; it is again the law in several European countries to X-ray people without a medical reason.
Not given full access
Rabin also points out that although the TSA says that the scanners have been assessed by the Food and Drug Administration, the United States Army Public Health Command and the Johns Hopkins University Applied Physicians Laboratory, researchers at those institutions “have not always had direct access to the scanner in use, and some of the published reports about them have been heavily redacted, with the authors’ names removed.”
One radiation expert is quoted by Rabin as saying the effective dose could be 45 times higher than the TSA estimates — or about the same as 10 percent of a single chest X-ray.
Another expert tells Rabin that “he worries about mechanical malfunctions that could cause the beam to stop in one place for even a few seconds, resulting in greater radiation exposure.”
And mechanical problems are occurring with these machines, as Rabin notes:
A recent T.S.A. report said that between May 2010 and May 2011, there were 3,778 service calls concerning mechanical problems in backscatter X-ray machines. Radiation safety surveys were conducted after only 2 percent of the calls.
Less stringent regulation
As a joint investigative report by ProPublica and “PBS NewsHour” explained last fall, airport scanners are regulated differently — and less stringently — than X-ray machines used in hospitals and clinics. In fact, annual safety inspections of airport scanners are conducted primarily by the manufacturer of the machines, not by independent inspectors.
“[In 2010], in reaction to public anger from members of Congress, passengers and advocates, the TSA contracted with the Army Public Health Command to do independent radiation surveys,” wrote ProPublica reporter Michael Gabrall. “But email messages obtained in a lawsuit brought by the Electronic Privacy Information Center, a civil liberties group, raise questions about the independence of the Army surveys. One email sent by TSA health and safety director Jill Segraves shows that local TSA officials were given advance notice and allowed to ‘pick and choose’ which systems the Army could check.”
Then there’s the curious matter of the TSA’s continued refusal to permit baggage screeners to wear film badges to monitor how much radiation they’re being exposed to — the same badges that many hospital and lab employees routinely wear.
Until these matters are resolved and there’s more transparency about the machines and their upkeep, airplane passengers — particularly pregnant women and young children — may want to get to the airport early and ask for a pat-down, Rabin concludes.
Footnote: The Minneapolis-St. Paul International Airport (MSP) does not have backscatter X-ray scanners. Its machines are millimeter-wave scanners, which use radio frequency waves rather than low levels of ionizing radiation and are permitted in European airports. TSA made the decision about which type of machine would go into MSP, said Patrick Hogan, the airport’s director of public affairs and marketing, in a phone interview Wednesday. He also said that the TSA has not announced any plans to bring backscatter X-ray scanners to MPS.
