Even
if X-ray body scanners would prevent terrorists from smuggling explosives onto
planes, nearly half of Americans still oppose using them because they could
cause a few people to eventually develop cancer, according to a new Harris Interactive
poll conducted online for ProPublica.
Slightly more than third of
Americans supported using the scanners, while almost a fifth were unsure.
The Transportation Security
Administration plans to install body scanners, which can detect explosives and
other objects hidden under clothing, at nearly every airport security lane in
the country by the end of 2014. It’s the biggest change to airport security
since metal detectors were introduced more than 35 years ago.
The scanners have long faced vocal
opposition. Privacy advocates have decried them as a “virtual strip search”
because the raw images show genitalia, breasts and buttocks – a concern
the TSA addressed by requiring software that makes the images less
graphic. But in addition to privacy objections, scientists and some
lawmakers oppose one type of scanner because it uses X-rays, which damage DNA
and could potentially lead to a few additional cancer cases among the 100
million travelers who fly every year. They say an alternative technology, which
uses radio frequency waves, is safer.
Some travelers like Kathy Blomker, a breast cancer survivor from Madison, Wis., have
decided to forgo the machines altogether and opt for a physical pat-down
instead. “I’ve had so much radiation that I don’t want to subject myself to
radiation that I can avoid,” she said. “I decided I’m just not ever going to go
through one of those machines again. It’s just too risky.”
After ProPublica published an investigation,
reported in conjunction with PBS
NewsHour, showing that the X-ray scanners had
evaded rigorous safety evaluations, the head of the TSA told Senator Susan Collins
that his agency would conduct a new independent safety study. He subsequently
backed
off that promise, prompting the senator to write
the TSA pressing the agency to go ahead with the study and asking it to post
larger signs alerting pregnant women that they have the option to have a
physical pat-down instead of going through the X-ray scanners.
The
TSA has repeatedly touted a series of polls
showing strong public support for the scanners. But those polls and surveys
– conducted by Gallup,
The
Wall Street Journal and various travel sites – largely dealt with the
privacy issue.
Only one of those polls –
by CBS
News – asked specifically about X-ray body scanners, finding that 81
percent of Americans thought that such X-ray scanners should be used in
airports. But that poll – like all the others – did not mention the
risk of cancer.
When
confronted with the cancer-terrorism trade-off, however, Americans took a much
more negative view of the scanners.
Harris Interactive surveyed 2,198
Americans between Dec. 2 and Dec. 6. (Full survey methodology can be found here.) The international polling firm asked,
“If a security scanner existed
which would significantly help in preventing terrorists from boarding a plane
with powder, plastic, or liquid
explosives, do you think the TSA should still use it even if it could cause perhaps
six of the 100 million passengers who fly each year to eventually develop
cancer”
Forty-six percent said the TSA
shouldn’t use it, 36 percent said it should, and 18 percent weren’t sure.
Asked to comment, TSA spokesman Michael McCarthy said in a statement that the X-Ray scanners are “well within national standards.”
“TSA’s top priority is the safety of the traveling public and the use of advanced imaging technology is critical to the detection of both metallic and non-metallic threats,” he said. “All results from independent evaluations confirm that these machines are safe for all passengers.”
The
number of potential cancer cases used in the poll comes from a peer-reviewed research
paper written by a radiology and epidemiology professor at the University
of California, San Francisco, and posted on the TSA’s website.
The professor, Rebecca Smith-Bindman, concluded that ‘there is no significant threat of
radiation from the scans.’ But she estimated that among the 750 million
security checks of 100 million airline passengers per year, six cancers could result
from the X-ray scans. She cautioned that the increase was small considering
that the same 100 million people would develop 40 million cancers over the
course of their lifetimes.
Another study
by David Brenner, director of Columbia University’s Center for Radiological
Research, estimated that as airlines approach a billion boardings
per year in the United States, 100 additional cancers per year could result
from the scanners.
The
TSA uses two
types of body scanners to screen travelers for nonmetallic explosives. In
the X-ray machine, known as a backscatter, a passenger stands between two large
blue boxes and is scanned with an extremely low level of ionizing radiation, a
form of energy which strips electrons from atoms and can damage DNA, leading to
cancer. In the millimeter-wave machine, a passenger stands inside a round glass
booth and is scanned with low-energy electromagnetic waves which don’t strip
electrons from atoms and have not been linked to cancer.
There is a great deal of
uncertainty when performing cancer risk assessments from the very low levels of
radiation that the backscatters emit. The U.S. Food and Drug Administration put
the risk of a fatal cancer from the machines at one
in 400 million. The U.K. Health Protection Agency has put it at one
in 166 million.
Some experts say such estimates
of population risk create a distorted picture of the danger because humans are
constantly exposed to background radiation and already accept risks that
increase exposure, such as flying on a plane at cruising altitude.
In the authoritative study on
the health risks of low levels of radiation, the National Academy of Sciences concluded
that the risk of cancer increases with radiation exposure and that there is no
level of radiation at which the risk is zero.
Given
that risk, Brenner and some in Congress have argued that the TSA should forgo
in the X-ray scanners in favor of the millimeter-wave machine.
European officials have gone so far as to
prohibit
the X-ray body scanners, leaving the millimeter-wave scanner as the only option.
But some countries, including Germany, have reported a high rate of false
alarms with the millimeter-wave machines.
The
TSA has said that keeping two technologies in play creates competition,
encouraging the manufacturers of both technologies to improve the detection
capabilities, efficiency and cost of the scanners.
