Security of nation not at health’s cost

Tags: Op-ed
Security of nation not at health’s cost
These days one hears from the police on US airports: “Put your palms forward, please.” The transportation security administration (TSA) has begun randomly swabbing passengers’ hands at checkpoints and airport gates to test them for traces of explosives. The swabbing of passengers’ hands started soon after the Christmas Day attempted bombing of Northwest Flight 253 over Detroit, Michigan.

In order to adopt a comprehensive swabbing strategy, the TSA has purchased more than 7,000 explosive trace detection (ETD) machines and has purchased 400 additional units with $16 million in federal stimulus money.

Security experts believe that swabbing hands is a good move, and privacy advocates support this testing method so long the agency tests only for security-related objects and does not discriminate when it selects people to be tested. Such tests are believed to not significantly increase wait times at airport checkpoints.

TSA says the swabbing machines test only for explosives and not for drugs and other substances. However, because some legal substances — such as fertilisers and heart medicines — can result in “false positives”, it needs to be ensured that people who test positive be treated respectfully. If one refuses the ETD swab, then that person will likely to be subjected to additional screening, which depending on the results may result in a referral to a law enforcement officer. Another question is whether a potential bomber could scrub explosive residue off his or her hands to remove traces of a bomb after handling one.

A variant of the hand swabbing scanner is the puffer machine, an explosives trace-detection portal machine. It is a security device that seeks to detect explosives and illegal drugs at airports and other sensitive facilities as a part of airport security screening.The machine operates by releasing multiple puffs of air at a passenger standing upright within the machine. This will flush out any particles on the person inside the machine then analyse and identify them in seconds. According to an article in New York Times dated June 16, 2005, this machine is capable of screening up to 180 passengers an hour. This sample is then analysed using IMS or MS technology to search for specific explosive or narcotic compounds. If a substance of concern is detected, the security personnel are notified by a visible and/or audible alarm.

Perhaps, the most problematic of the scanning technologies that are currently used is the full-body scanner. A full-body scanner is a device that detects objects on a person’s body, without physically removing clothes or making physical contact.Depending on the specific technology, the operator may see an alternate-wavelength image of the person’s naked body, or merely a cartoon-like representation of the person with an indicator showing where any suspicious items were detected. For privacy and security reasons, the display is generally not visible to other passengers, and in some cases is located in a separate room where the operator cannot see the face of the person being screened. Unlike metal detectors, full-body scanners can detect non-metal objects, which became an increasing concern after various airliner bombing attempts in the 2000s.

The Federal officials claim radiation risks from the TSA’s new full-body scanners are low, but several scientists are calling on the administration to rethink whether the numbers really add up. The TSA says the radiation from its security scans amounts to about a thousandth of the amount a patient receives from a standard chest X-ray, or an amount “equivalent to two minutes of flying on an airplane”.

But, most recently, a physics professor at Arizona State University in Tempe not only conducted his own study, finding the radiation exposure 10 times what the TSA estimates, but also argues that the health risks aren’t mathematically worth taking. Prof Peter Rez explains that while the risk of getting a fatal cancer from the screening is minuscule, it’s about the same as the probability an airplane will get blown up by a terrorist.

Similarly, a team of scientists from the University of California San Francisco (UCSF) has written a letter to the White House warning that the scanners present — above and beyond the risks to the general population — “potential serious health risks” to certain segments of society, such as the elderly and the pregnant.

The backscatter x-ray technology used in airport security scanners penetrates the skin only about 1/4 inch before the rays are scattered, whereas medical x-rays transmit completely through the body. The TSA has determined, therefore, that the amount of radiation emitted from the airport scanners is significantly less than at the doctor’s office.

However, according to the UCSF team, the x-ray dose from these devices has often been compared in the media to the cosmic ray exposure inherent to airplane travel or that of a chest x-ray. This comparison is misleading: both the air travel cosmic ray exposure and chest x-rays have much higher x-ray energies, and the health consequences are appropriately understood in terms of the whole body volume dose. In contrast, these new airport scanners are largely depositing their energy into the skin and immediately adjacent tissue, and since this is such a small fraction of body weight/volume, possibly by one to two orders of magnitude, the real dose to the skin is now high.

In addition, another problem is when the machine fails. “Because this device can scan a human in a few seconds, the x-ray beam is intense,” the UCSF letter states. “Any glitch in power at any point in the hardware (or more importantly in software) that stops the device could cause an intense radiation dose to a single spot on the skin.”

While it’s true that with the increase in terror threats airport security has to rely on newer technology, more research that helps understand the effects of the security technologies on health is also needed. A better understanding of the risks and benefits would ensure both the health of people and security of our airspace.

(The writer is on the faculty of Indian Institute of

Technology, Mandi, India and knowledge editor of Financial Chronicle)


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