Full-body scanners pose little radiation risk--study

Providing a sigh of relief to flyers, the analysis showed that the controversial devices pose little risk, even to frequent flyers, who are exposed to far more radiation during travel at high altitudes.

The analysis may help ease anxiety of travelers already spooked by reports of radiation leaking from the crippled nuclear plants in Japan.

Radiation panic is in the air
The United States is gripped by the intense fear of deadly nuclear radiation from earthquake-torn Japan. Despite the expert assurances that the radioactive material is not dangerous for the country, the radiation leakage in Japan is creating confusion and panic among the Americans.

The analysis may help ease anxiety of travelers already spooked by reports of radiation leaking from the crippled nuclear plants in Japan.

Recently reports emerged claiming that low levels of radiation have been detected on planes arriving at U.S. airports from Japan, with two American Airlines planes arriving from Tokyo testing positive for low-level radiation--one in Dallas, Texas, and another in Chicago, Illinois.

The authorities then soon started conducting radiation tests at the airports. Although the experts claimed no harmful levels of radiation have reached the United States, radiation had been detected on several passengers at airports in the country.

Few months back, scientists warned that radiation from the controversial full-body airport scanners could lead to an increase in skin cancer, particularly in children.

Scanners pose little radiation threat
But the latest analysis finds that full-body airport scanners don't pose a significant health risk to passengers.

"There is such a vast difference between super-low doses of radiation and the really high doses that happen if you are in the middle of a nuclear accident," said Dr. Rebecca Smith-Bindman, a radiology professor at the University of California, San Francisco, the lead author of the study.

"Because they are all called radiation, we are tempted to put them all in the same category. That is a mistake."

According to the analysis, the scanners expose people to less than one percent of the radiation associated with cosmic rays at typical flight altitudes.

Exposure from X-ray scanner is equivalent to daily exposure
The analysis estimated a single exposure to the radiation emitted from a so-called backscatter X-ray scanner, the more common type of machine being used in the United State, is equivalent to three to nine minutes of radiation encountered in normal daily living.

"The radiation doses emitted by the scans are extremely small; the scans deliver an amount of radiation equivalent to 3 to 9 minutes of the radiation received through normal daily living," Pratik Mehta of the University of California, Berkeley and Rebecca Smith-Bindman, a medical doctor at the University of California, San Francisco, wrote in the new report.

"In medicine, we try to balance risks and benefits of everything we do, and thus while the risks are indeed exceedingly small, the scanners should not be deployed unless they provide benefit-improved national security and safety -- and consideration of these issues is outside the scope of our expertise," added Smith-Bindman.

"Issues have been raised regarding the efficacy of scanners, and if the scanners are not deemed efficacious, they should not be used."

Study details
To estimate the risk from these devices, the research team divided passengers into three groups: all flyers, frequent flyers and five-year-old girls who are frequent flyers.

They said of the total 750 million flights taken per year by 100 million passengers, there would be an additional six cancers due to the radiation exposure from airport scanners over the course of their lifetimes, out of the 40 million cancers that would normally develop among people in all age group.

For frequent flyers, Smith-Bindman and colleagues estimated that radiation exposure from airport scanners would cause four excess cancers for people who fly 60 hours a week. This would be in addition to the 600 extra cancers just from flying, which exposes people to more solar radiation and 400,000 cancers that normally would occur over their lifetime.

And for every two million five-year-old girls who are frequent flyers, traveling one round-trip a week, going through the scanners would cause one additional cancer out of the 250,000 breast cancers that are set to occur in this group over their lifetimes.

"Based on what is known about the scanners, passengers should not fear going through the scans for health reasons, as the risks are truly trivial," concluded the authors.

"If individuals feel vulnerable and are worried about the radiation emitted by the scans, they might reconsider flying altogether since most of the small, but real, radiation risk they will receive will come from the flight and not from the exceedingly small exposures from the scans."