Posting in Cancer
A comparison of the two airport security body scanners in the U.S. shows that maybe one might be significantly safer than the other.
I was in Canada this week and on my way back to New York through the Ottawa airport I chose to be body scanned. Something had triggered the metal detector. Maybe the underwire in my bra they guessed. So security offered, “Pat down or scan?” I chose scan because I was in a rush and pat downs take a lot of time. Up to 15 minutes sometimes. It's easy to be scanned. But every time I’ve been scanned (three times) I feel uneasy.
ProPublica’s ongoing investigation of scanners in the U.S. provides some answers to common worries.
The Transportation Security Administration (TSA) plans to install body scanners at every security check lane by 2014. And the TSA confirms that the scanners pose “no health or safety risk for any passenger.” They’ve apparently been cleared by the Food and Drug Administration and they’ve been used for years in airports around the world. (I went through my first in Canada in 2009.)
But there have been cancer concerns with the scanner that uses X-rays.
In independent, peer-reviewed studies, radiation experts concluded that the X-ray scanner could cause six to 100 airline passengers each year to develop cancer. Outside the United States, few countries use X-ray imaging machines, also known as backscatters, in their airports. And the FDA has no authority to approve body scanners before they are sold because they are electronic products, not medical devices.
Just this past November the European Union decided to prohibit X-ray body scanners in all European airports. Now members of Congress are asking the TSA to do an independent safety review.
Right now the TSA uses two types of scanners, the millimeter-wave machine and the backscatter X-ray machine. ProPublica dissects the two here.
The millimeter wave machine, below, sends radio frequency waves over your body and the energy reflected back is analyzed for suspicious items.
To address the controversy of the "virtual strip search" the TSA only uses a generic unisex image that looks like a cartoon outline of a human, see image at left below.
There are no known health risks with a millimeter wave machine. Currently, there are about 300 of them in U.S. airports, including major hubs like Atlanta, Dallas-Fort Worth and San Francisco. The U.S. uses the L-3 Communications’ ProVision scanner that runs about $170,000 to $180,000.
The backscatter machine (below) emits a low intensity X-ray beam over the body. Now these rays do not go through the body like your typical medical X-rays, but rather the rays are reflected back to detectors that then create a low resolution, whitish 2D image (also below.)
After being cleared the images are deleted. According to the TSA each scan gives off less than 10 microREM of radiation, equivalent to the radiation we are subjected to when we fly at 30,000 feet for three minutes. This appears to contradict the statement above regarding studies that found six to 100 people could develop cancer from these machines. I imagine there are a lot of variables (existing health of the passenger for one) that need to be accounted for in performing accurate studies. Just living in New York City, for instance, increases my chances of getting breast cancer. These machines need to be compared to other sources of radiation that we are all exposed to daily in cities.
But rightly so, people have asked why the TSA chooses to use the backscatter as opposed to just the millimeter wave machines. From ProPublica:
The TSA has said that keeping both technologies in play encourages the manufacturers to improve detection capability while lowering the cost for the taxpayer. The agency says the X-ray machine is safe because the radiation is equivalent to the amount passengers receive in two minutes of flying at altitude.
But ProPublica found some potential problems with the millimeter-wave scanner. Several other countries have reported a high rate of false alarms caused by innocuous things, such as folds in clothing, buttons and even sweat.
There are about 250 X-ray scanners (Rapiscan’s Secure 1000 scanner) in U.S. airports. It’s in hubs like Los Angeles, Chicago O'Hare and New York’s John F. Kennedy. It costs about $170,000 to $180,000.
In terms of effectiveness, well that has yet to be seen. Apparently studies have suggested that scanners could miss plastic explosives similar to the one used by the “Underwear Bomber” in 2009. The Department of Homeland Security is evaluating how accurately the TSA is monitoring the radiation of the backscatters and the Government Accountability Office is investigating the detection accuracy of both machines.
By the way, the security officers in the Ottawa airport never did confirm what set off the initial trigger that led me to be scanned.
Related on Smart Planet:
- Dishonesty detectors: a criminally flawed technology
- Next? Body scanners could be on trains, subways and boats
- Why the leaked body scanner photos matter
Dec 29, 2011
is welcome. I was radiation trained 20+ years ago and even though things have changed I dion't think the laws of physics (radiation) have. An analogy would be shining a flashlight at a friend a mile away. They could see the light easily. Whereas if you wished to see your friend a mile away you'd need an aircraft landing light to get enough light on him/her to see them (ie. light bounce back). The x-ray machines I maintained had a piece of metal where the x-rays came out of the machine. This caused soft (less penetrating) x-rays to be stopped leaving only hard x-rays. These hard x-rays when through the material easily and therefor less radiation was used as all the soft, non-penetrating rays were stopped. These soft x-rays would be absorbed by a human body thus increasing the overall doseage with no return in value. The media seems to telling the story of the radiation dose delivered is calculated on the whole body rather than just the surface of the body that receives most of the radiation. The other question is has an x-ray badge never been allowed on a person when they go through the back scatted x-ray machine? Women who are cancer survivors that have had radiation should never get into a back scatter x-ray machine. X-rays are a trade off of damage verses benefit. The small amount of cell damage is minor verses the risk of leaving a bullet in a person.