Professor addresses airport security health concerns

ASU students flying home for the holidays might receive a small gift from airport security — radiation.

An ASU professor is concerned that a new type of X-ray scanner at airports could be dangerous to passengers’ health.

The Transportation Security Administration, the organization responsible for airport security across the nation, currently employs 206 body-scanning machines at 38 different airports that are potentially harmful, according to physics professor Peter Rez.

Rez co-wrote a paper on the topic with ASU health physics professor Ken Mossman that was published Nov. 9 in Radiation Protection and Dosimetry, a peer-reviewed scientific journal.

In the paper, Rez expressed his concern over the safety of the “backscatter” X-ray technology airports use to screen passengers.

The machines are called “backscatter” devices because they create images of people by bouncing X-rays off of them and detecting the radiation that reflects back from the target, with the goal of detecting any banned items under their clothing.

These machines have been widely criticized on violation of privacy grounds; the images produced are of the subjects’ naked bodies, Rez said.

But left unexposed are the health issues surrounding the machines.

The machine picks up only 5 percent of the waves, Rez said. The other 95 percent are retained in the skin.

The dosage of radiation, which according to TSA estimates is one ten-thousandth the amount of a chest X-ray, is too low to harm passengers, according to a TSA statement.

“We are confident that full-body X-ray security products and practices do not pose a significant risk to the public health,” TSA officials said in the statement.

But Rez isn’t so sure.

“The doses are probably higher than they say they are,” he said.

The TSA uses a method called effective dose, which averages the radiation throughout the entire body, Rez said.

He explained that the method is misleading because the skin absorbs almost all of the radiation.

The odds of contracting fatal skin cancer from just one trip through a backscatter machine, Rez said, are one in 30 million.

The chances of dying in a terrorist attack, Rez said, are also one in 30 million.

“The probability is about the same as the thing you are trying to prevent,” Rez said.

With frequent flyers, such as pilots and airline attendants, the risk of cancer is greatly multiplied if they are subject to the radiation on a regular basis.

Independent of Rez’s paper, four professors from the University of California, San Francisco wrote a letter to the TSA outlining their concerns over the safety of the backscatter devices.

The point of the letter was to urge the TSA to conduct additional testing through an independent body, said co-author David Agard in an e-mail.

“While the risks for an individual from a single flight are undoubtedly low, cumulative effects for frequent fliers, or potential effects at a population level are a serious concern,” he said.

Dave Bates is president of the Allied Pilots Association, a collective bargaining agency based in Fort Worth, Texas, for American Airlines pilots.

He wrote to his members on Nov. 4, urging them to refuse being subject to the X-ray machines.

“Airline pilots in the United States already receive higher doses of radiation in their on-the-job environment than nearly every other category of worker in the United States,” he said in the letter.

Rez said he also believes that additional, more thorough research needs to be done by an independent party.

“The real danger is not what happens when it works normally, but what happens if there is a malfunction,” he said.

In the event of a failure, the device could deliver a much higher, more concentrated dose of radiation, he said.

There is an alternative to backscatter devices, Rez added.

Some machines use high frequency radio transmissions, called millimeter waves, to scan passengers.

A total of 167 of the millimeter wave devices are currently in use at 30 different airports.

“Millimeter wave [technology] does not have any known health effects,” Rez said.

For students to better recognize the devices, Rez described the potentially harmful backscatter devices as a pair of “big blue boxes” at airport security.

Nutrition junior Claudia Thompson was not pleased when she heard of the new X-ray machines.

“I don’t understand why they are necessary,” she said. “Going to the airport has gotten to be the worst experience in the entire world.”

Reach the reporter at alex.ferri@asu.edu