New articles examine safety of airport security scanners

Mar 16, 2011

The Transportation Security Administration (TSA) has begun to use whole-body imaging scanners as a primary screening measure on travelers passing through airport security checkpoints. One type of scanner employs millimeter wave technology, which delivers no ionizing radiation. However, the second type of scanner currently deployed at airports uses backscatter X-rays that expose the individual being screened to very low levels of ionizing radiation. In the April issue of Radiology, two articles address the question of what potential long-term public health threats, if any, these backscatter X-ray systems pose.

In the first article, David J. Brenner, Ph.D., D.Sc., director of the Center for Radiological Research at Columbia University Medical Center in New York, N.Y., proposes that from a public health policy perspective, given that up to one billion such scans per year are now possible in the U.S, we should have concerns about the long-term consequences of an extremely large number of people being exposed to a potential radiation-induced cancer risk, no matter how slight.

"The risks for any individual going through the X-ray backscatter scanners are exceedingly small," Dr. Brenner said. "However, if all air travelers are going to be screened this way, then we need to be concerned that some of these billion people may eventually develop cancer as a result of the radiation exposure from the X-ray scanners."

In the second article, David A. Schauer, Sc.D., C.H.P., executive director of the National Council on Radiation Protection and Measurements (NCRP), argues that the summation of negligible average risks over large populations or time periods into a single value produces a distorted image of risk that is out of perspective with risks accepted every day, both voluntarily and involuntarily.

"There is no scientific basis to support the notion that a small risk to an individual changes in any way for that individual as others around him are also exposed to the same source of radiation," he said. "Critics of security screening acknowledge that doses from backscatter X-ray systems are very low and safe for an individual."

Dr. Schauer advocates strict regulatory control of the backscatter scanners in order to ensure that their use is consistent with the goals and objectives of radiation protection, which include justification (benefits exceed cost or harm), optimization (exposures are kept as low as reasonably achievable) and limitation (individual doses are limited).

"Any decision that alters the radiation exposure situation should do more good than harm," Dr. Schauer said. "In other words, people should only be exposed to ionizing radiation for security screening purposes when a threat exists that can be detected and for which appropriate actions can be taken. In addition, exposures must be justified and optimized."

Both Dr. Brenner and Dr. Schauer agree that the scanners using millimeter wave technology should be considered as a first option, since they are similar in cost and functionality to the backscatter machines, but do not expose the passenger to ionizing radiation. However, they also say that the average traveler should not be overly concerned about being screened with the backscatter scanners.

"As someone who travels just occasionally, I would have no hesitation in going through the X-ray backscatter scanner," Dr. Brenner said. "Super frequent fliers or airline personnel, who might go through the machine several hundred times each year, might wish to opt for pat-downs. The more scans you have, the more your risks may go up—but the individual risks are always going to be very, very small."

NCRP has recommended that backscatter X-ray systems adhere to an effective dose of 0.1 microsieverts (µSv) or less of per scan, which roughly equates to the each passenger receives in under two minutes on the plane while flying at 30,000 feet. The average person in the U.S. receives an effective dose of about 3 millisieverts (3,000 µSv) per year from naturally occurring radioactive materials and cosmic radiation from outer space.

Explore further: Oil-swishing craze: Snake oil or all-purpose remedy?

More information: "Are X-ray Backscatter Scanners Safe for Airport Passenger Screening? For Most Individuals, Probably Yes, but a Billion Scans per Year Raises Long-Term Public Health Concerns." David J. Brenner, Ph.D., D.Sc.

"Does Security Screening with Backscatter X-rays Do More Good than Harm?" David A. Schauer, Sc.D., C.H.P.

radiology.rsna.org/

add to favorites email to friend print save as pdf

Related Stories

Gov't says full-body scanners at airports are safe

Nov 18, 2010

(AP) -- They look a little like giant refrigerators and pack a radiation dose big enough to peer through clothing for bombs or weapons, yet too minuscule to be harmful, federal officials insist. As the government ...

Hazards of CT scans overstated

Dec 01, 2007

Concerns over possible radiation effects of CT scans detailed in a report yesterday in the New England Journal of Medicine should not scare people away from getting medically needed CT scans, as the scans play a critical role i ...

Recommended for you

Suddenly health insurance is not for sale

Apr 18, 2014

(HealthDay)— Darlene Tucker, an independent insurance broker in Scotts Hill, Tenn., says health insurers in her area aren't selling policies year-round anymore.

Study: Half of jailed NYC youths have brain injury (Update)

Apr 18, 2014

About half of all 16- to 18-year-olds coming into New York City's jails say they had a traumatic brain injury before being incarcerated, most caused by assaults, according to a new study that's the latest in a growing body ...

Autonomy and relationships among 'good life' goals

Apr 18, 2014

Young adults with Down syndrome have a strong desire to be self-sufficient by living independently and having a job, according to a study into the meaning of wellbeing among young people affected by the disorder.

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

dogbert
not rated yet Mar 16, 2011
The TSA regularly violates the fourth amendment rights of U.S. citizens in both the intrusive pat downs and in the scanners.

The individual cost of backscatter scanners is currently unknown and may be considerably larger than estimates. Consider that exposure to even sunlight is known to greatly increase personal risk of skin cancer including melanoma.

Radiation exposure cost is usually computed on the basis of whole body exposure. For X-Rays, cosmic radiation, etc. this is a correct model. For backscatter radiation, however, the radiation is not whole body, it is confined to the skin and portions [how deep?] of the eye.

Has the risk that the scanning beam might might overexpose a particular region, particularly during the start and stop activities been properly assessed? Is there some type of fail safe mechanism to prevent spot overexposure? If so, how reliable is it?

Many questions have not been properly expressed, much less answered.

More news stories

Filipino tests negative for Middle East virus

A Filipino nurse who tested positive for the Middle East virus has been found free of infection in a subsequent examination after he returned home, Philippine health officials said Saturday.

Study says we're over the hill at 24

(Medical Xpress)—It's a hard pill to swallow, but if you're over 24 years of age you've already reached your peak in terms of your cognitive motor performance, according to a new Simon Fraser University study.

NASA's space station Robonaut finally getting legs

Robonaut, the first out-of-this-world humanoid, is finally getting its space legs. For three years, Robonaut has had to manage from the waist up. This new pair of legs means the experimental robot—now stuck ...

Ex-Apple chief plans mobile phone for India

Former Apple chief executive John Sculley, whose marketing skills helped bring the personal computer to desktops worldwide, says he plans to launch a mobile phone in India to exploit its still largely untapped ...

Egypt archaeologists find ancient writer's tomb

Egypt's minister of antiquities says a team of Spanish archaeologists has discovered two tombs in the southern part of the country, one of them belonging to a writer and containing a trove of artifacts including reed pens ...

Airbnb rental site raises $450 mn

Online lodging listings website Airbnb inked a $450 million funding deal with investors led by TPG, a source close to the matter said Friday.