According to ProPublica:

Oneafter another, the experts convened by the Food and Drug Administration raisedquestions about the machine because it violated a longstanding principle inradiation safety — that humans shouldn’t be X-rayed unless there is amedical benefit.
“Ithink this is really a slippery slope,” said Jill Lipoti,who was the director of New Jersey’s radiation protection program. The devicewas already deployed in prisons; what was next, she and others asked —courthouses, schools, airports? “I am concerned … with expanding this type ofproduct for the traveling public,” said another panelist, Stanley Savic, the vice president for safety at a large electronicscompany. “I think that would take this thing to an entirely different level ofpublic health risk.”
Themachine’s inventor, Steven W. Smith, assured the panelists that it was highlyunlikely that the device would see widespread use in the near future. At thetime, only 20 machines were in operation in the entire country.
“Theplaces I think you are not going to see these in the next five years islower-security facilities, particularly power plants, embassies, courthouses,airports and governments,” Smith said. “I would be extremely surprised in thenext five to 10 years if the Secure 1000 is sold to any of these.”
Today,the United States has begun marching millions of airline passengers through theX-ray body scanners, parting ways with countries in Europe and elsewhere thathave concluded that such widespread use of even low-level radiation poses anunacceptable health risk. The government is rolling out the X-ray scannersdespite having a safer alternative that the Transportation SecurityAdministration says is also highly effective.
AProPublica/PBS NewsHour investigation of how this decisionwas made shows that in post-9/11 America, security issues can trump evenlong-established medical conventions. The final call to deploy the X-raymachines was made not by the FDA, which regulates drugs and medical devices,but by the TSA, an agency whose primary mission is to prevent terroristattacks.
Research suggests that anywherefrom six to 100 U.S. airline passengers each year could get cancer from themachines. Still, the TSA has repeatedly defined the scanners as “safe,”glossing over the accepted scientific view that even low doses of ionizingradiation — the kind beamed directly at the body by the X-ray scanners— increase the risk of cancer.
“Even though it’s a very smallrisk, when you expose that number of people, there’s a potential for some ofthem to get cancer,” said Kathleen Kaufman, the former radiation managementdirector in Los Angeles County, who brought the prison X-rays to the FDApanel’s attention.
About 250 X-ray scanners are currently inU.S. airports, along with 264 body scanners that use a different technology, a form of low-energy radio waves knownas millimeter waves.
Robin Kane, the TSA’s assistantadministrator for security technology, said that no one would get cancerbecause the amount of radiation the X-ray scanners emit is minute. Having bothtechnologies is important to create competition, he added.
“It’sa really, really small amount relative to the security benefit you’re going toget,” Kane said. “Keeping multiple technologies in play is very worthwhile forthe U.S. in getting that cost-effective solution — and being able toincrease the capabilities of technology because you keep everyone trying to getthe better mousetrap.”
Determined to fill a critical holein its ability to detect explosives, the TSA plans to have one or the otheroperating at nearly every security lane in America by 2014. The TSA hasdesignated the scanners for “primary” screening: Officers will direct everypassenger, including children, to go through either a metal detector or a bodyscanner, and the passenger’s only alternative will be to request a physicalpat-down.
How did the United States swingfrom considering such X-rays taboo to deeming them safe enough to scan millionsof people a year?
Anew wave of terrorist attacks using explosives concealed on the body, coupledwith the scanners’ low dose of radiation, certainly convinced many radiationexperts that the risk was justified.
But other factors helped themachines gain acceptance.
Because of a regulatory Catch-22,the airport X-ray scanners have escaped the oversight required for X-raymachines used in doctors’ offices and hospitals. The reason is that thescanners do not have a medical purpose, so the FDA cannot subject them to therigorous evaluation it applies to medical devices.
Still, the FDA has limitedauthority to oversee some non-medical products and can set mandatory safetyregulations. But the agency let the scanners fall under voluntary standards setby a nonprofit group heavily influenced by industry.
As for the TSA, it skipped a publiccomment period required before deploying the scanners. Then, in defending them,it relied on a small body of unpublished research to insist the machines weresafe, and ignored contrary opinions from U.S. and European authorities that recommendedprecautions, especially for pregnant women. Finally, the manufacturer, Rapiscan Systems, unleashed an intense and sophisticatedlobbying campaign, ultimately winning large contracts.
Both the FDA and TSA say duediligence has been done to assure the scanners’ safety. Rapiscansays it won the contract because its technology is superior at detectingthreats. While the TSA says X-ray and millimeter-wave scanners are botheffective, Germany decided earlier this year not to roll out millimeter-wave machinesafter finding they produced too many false positives.
Mostof the news coverage on body scanners has focused on privacy, because themachines can produce images showing breasts and buttocks. But the TSA has sinceinstalled software to make the images less graphic. While some accounts haveraised the specter of radiation, this is the first report to trace the historyof the scanners and document the gaps in regulation that allowed them to avoidrigorous safety evaluation.
Little research oncancer risk of body scanners
Humansare constantly exposed to ionizing radiation, a form of energy that has beenshown to strip electrons from atoms, damage DNA and mutate genes, potentiallyleading to cancer. Most radiation comes from radon, a gas produced fromnaturally decaying elements in the ground. Another major source is cosmicradiation from outer space. Many common items, such as smoke detectors, containtiny amounts of radioactive material, as do exit signs in schools and officebuildings.
As a result, the cancer risk fromany one source of radiation is often small. Outside of nuclear accidents, suchas that at Japan’s Fukushima plant, and medical errors, the health risk comesfrom cumulative exposure.
In Rapiscan’sSecure 1000 scanner, which uses ionizing radiation, a passenger stands betweentwo large blue boxes and is scanned with a pencil X-ray beam that rapidly movesleft to right and up and down the body. In the other machine, ProVision, made by defense contractor L-3 Communications, apassenger enters a chamber that looks like a round phone booth and is scannedwith millimeter waves, a form of low-energy radio waves, which have not beenshown to strip electrons from atoms or cause cancer.
Only a decade ago, many statesprohibited X-raying a person for anything other than a medical exam. Even after9/11, such non-medical X-raying remains taboo in most of the industrializedworld. In July, the European Parliament passed a resolution that security“scanners using ionizing radiation should be prohibited” because of healthrisks. Although the United Kingdom uses the X-ray machine for limited purposes,such as when passengers trigger the metal detector, most developed countrieshave decided to forgo body scanners
altogether or use only the millimeter-wavemachines.
While the research on medicalX-rays could fill many bookcases, the studies that have been done on theairport X-ray scanners, known as backscatters, fill a file no more than a fewinches thick. None of the main studies cited by the TSA has been published in apeer-reviewed journal, the gold standard for scientific research.
Those tests show that the Secure1000 delivers an extremely low dose of radiation, less than 10 microrems. The dose is roughly one-thousandth of a chestX-ray and equivalent to the cosmic radiation received in a few minutes offlying at typical cruising altitude. The TSA has used those measurements to saythe machines are “safe.”
Most of what researchers know aboutthe long-term health effects of low levels of radiation comes from studies ofatomic bomb survivors in Hiroshima and Nagasaki. By charting exposure levelsand cancer cases, researchers established a linear link that shows the higherthe exposure, the greater risk of cancer.
Some scientists argue the danger isexaggerated. They claim low levels stimulate the repair mechanism in cells,meaning that a little radiation might actually be good for the body.
But in the authoritative report onlow doses of ionizing radiation, published in 2006, the National Academy ofSciences reviewed the research and concluded that the preponderance of researchsupported the linear link. It found “no compelling evidence” that there is anylevel of radiation at which the risk of cancer is zero.
Radiationexperts say the dose from the backscatter is negligible when compared tonaturally occurring background radiation. Speaking to the 1998 FDA panel,Smith, the inventor, compared the increased risk to choosing to visit Denverinstead of San Diego or the decision to wear a sweater versus a sport coat.
Usingthe linear model, even such trivial amounts increase the number of cancercases. Rebecca Smith-Bindman, a radiologist at theUniversity of California, San Francisco, estimated that the backscatters wouldlead to only six cancers over the course of a lifetime among the approximately100 million people who fly every year. David Brenner, director of ColumbiaUniversity’s Center for Radiological Research, reached a higher number —potentially 100 additional cancers every year.
“Whywould we want to put ourselves in this uncertain situation where potentiallywe’re going to have some cancer cases?” Brenner asked. “It makes me think,really, why don’t we use millimeter waves when we don’t have so muchuncertainty?”
But even without the machines, Smith-Bindman said, the same 100 million people would develop 40million cancers over the course of their lifetimes. In this sea of cancercases, it would be impossible to identify the patients whose cancer is linkedto the backscatter machines.
How the scannersavoided strict oversight
Althoughthey deliberately expose humans to radiation, the airport X-ray scanners arenot medical devices, so they are not subject to the stringent regulationsrequired for diagnostic X-ray machines. 
If they were, the manufacturerwould have to submit clinical data showing safety and effectiveness and beapproved through a rigorous process by the FDA. If the machines containedradioactive material, they would have to report to the Nuclear RegulatoryCommission.
But because it didn’t fit intoeither category, the Secure 1000 was classified as an electronic product. TheFDA does not review or approve the safety of such products. However,manufacturers must provide a brief radiation safety report explaining the doseand notify the agency if any overexposure is discovered. According to the FDA,no such incidents have been reported.
Under its limited oversight ofelectronic products, the FDA could issue mandatory safety regulations. But itdidn’t do so, a decision that flows from its history of supervisingelectronics. 
Regulation of electronic productsin the United States began after a series of scandals. From the 1930s to the1950s, it was common for a child to go to a shoe store and stand underneath anX-ray machine known as a fluoroscope to check whether a shoe was the right fit.But after cases arose of a shoe model’s leg being amputated and store clerksdeveloping dermatitis from putting their hands in the beam to adjust the shoe,the practice ended.
In1967, General Electric recalled 90,000 color televisions that had been soldwithout the proper shielding, potentially exposing viewers to dangerous levelsof radiation. The scandal prompted the creation of the federal Bureau ofRadiological Health.
“Thatultimately led to a lot more aggressive program,” said John Villforth,who was the director of the bureau. Over the next decade, the bureau createdfederal safety standards for televisions, medical X-rays, microwaves, tanningbeds, even laser light shows.
Butin 1982, the FDA merged the radiological health bureau into its medical-deviceunit.
“I was concerned that if they wereto combine the two centers into one, it would probably mean the ending of theradiation program because the demands for medical-device regulation were becomingincreasingly great,” said Villforth, who was put incharge of the new Center for Devices and Radiological Health. “As I sort ofguessed, the radiation program took a big hit.”
The new unit became stretched forscarce resources as it tried to deal with everything from tongue depressors toindustrial lasers. The government used to have 500 people examining the safetyof electronic products emitting radiation. It now has about 20 people. In fact,the FDA has not set a mandatory safety standard for an electronic product since1985.
As a result, there is an FDA safetyregulation for X-rays scanning baggage — but none for X-rays scanningpeople at airports.
Meanwhile, scientists begandeveloping backscatter X-rays, in which the waves are reflected off an objectto a detector, for the security industry.
TheSecure 1000 people scanner was invented by Smith in 1991 and later sold to Rapiscan, then a small security firm based in southernCalifornia. The first major customer was the California prison system, whichbegan scanning visitors to prevent drugs and weapons from getting in. But thestate pulled the devices in 2001 after a group of inmates’ wives filed aclass-action lawsuit accusing the prisons of violating their civil liberties.
TheU.S. Customs Service deployed backscatter machines for several years but inlimited fashion and with strict supervision. Travelers suspected of carryingcontraband had to sign a consent form, and Customs policy prohibited thescanning of pregnant women. The agency abandoned them in 2006, not for safetyreasons but because smugglers had learned where the machines were installed andadapted their methods to avoid them, said Rick Whitman, the radiation safetyofficer for Customs until 2008.
Yet,even this limited application of X-ray scanning for security dismayed radiationsafety experts. In 1999, the Conference of Radiation Control Program Directors,a nongovernmental organization, passed a resolution recommending that suchscreening be stopped immediately.
Thebackscatter machines had also caught the attention of the 1998 FDA advisorypanel, which recommended that the FDA establish government safety regulationsfor people scanners. Instead, the FDA decided to go with a voluntary standardset by a trade group largely comprising manufacturers and government agenciesthat wanted to use the machines.
“Establishing a mandatory standardtakes an enormous amount of resources and could take a decade to publish,” saidDan Kassiday, a longtime radiation safety engineer atthe FDA.
In addition, since the mid-1990s,Congress has directed federal safety agencies to use industry standardswherever possible instead of creating their own.
The FDA delegated the task ofestablishing the voluntary standards to the American National StandardsInstitute. A private nonprofit that sets standards for many industries, ANSIconvened a committee of the Health Physics Societ
y, a trade group of radiationsafety specialists. It was made up of 15 people, including six representativesof manufacturers of X-ray body scanners and five from U.S. Customs and theCalifornia prison system. There were few government regulators and noindependent scientists.
Incontrast, the FDA advisory panel was also made up of 15 people — fiverepresentatives from government regulatory agencies, four outside medicalexperts, one labor representative and five experts from the electronic productsindustry, but none from the scanner manufacturers themselves.
“Iam more comfortable with having a regulatory agency — either federal orthe states — develop the standards and enforce them,” Kaufman said. Suchregulators, she added, “have only one priority, and that’s public health.”
A representative of the HealthPhysics Society committee said that was its main priority as well. Most of thecommittee’s evaluation was completed before 9/11. The standard was published in2002 and updated with minor changes in 2009.
Ed Bailey, chief of California’sradiological health branch at the time, said he was the lone voice opposing theuse of the machines. But after 9/11, his views changed about what wasacceptable in pursuit of security.
“Thewhole climate of their use has changed,” Bailey said. “The consequence ofsomething being smuggled on an airplane is far more serious than somebodygetting drugs into a prison.”
Are InspectionsIndependent?
While the TSA doesn’t regulate themachines, it must seek public input before making major changes to securityprocedures. In July, a federal appeals court ruled that the agency failed tofollow rule-making procedures and solicit public comment before installing bodyscanners at airports across the country. TSA spokesman Michael McCarthy saidthe agency couldn’t comment on ongoing litigation.
TheTSA asserts there is no need to take additional precautions for sensitivepopulations, even pregnant women, following the guidance of the congressionallychartered National Council on Radiation Protection & Measurements.
But other authorities have come tothe opposite conclusion. A report by France’s radiation safety agencyspecifically warned against screening pregnant women with the X-ray devices. Inaddition, the Federal Aviation Administration’s medical institute has advisedpregnant pilots and flight attendants that the machine, coupled with their timein the air, could put them over their occupational limit for radiation exposureand that they might want to adjust their work schedules accordingly.
No similar warning has been issuedfor pregnant frequent fliers.
Even as people scanners became morewidespread, government oversight actually weakened in some cases.
Inspectionsof X-ray equipment in hospitals and industry are the responsibility of stateregulators — and before 9/11, many states also had the authority torandomly inspect machines in airports. But that ended when the TSA took oversecurity checkpoints from the airlines.
Instead,annual inspections are done by Rapiscan, thescanners’ manufacturer.
“Asa regulator, I think there’s a conflict of interest in having the manufacturerand the facility inspect themselves,” Kaufman said.
Lastyear, in reaction to public anger from members of Congress, passengers andadvocates, the TSA contracted with the Army Public Health Command to doindependent radiation surveys. But email messages obtained in a lawsuit broughtby the Electronic Privacy Information Center, a civil liberties group, raisequestions about the independence of the Army surveys.
One email sent by TSA health andsafety director Jill Segraves shows that local TSAofficials were given advance notice and allowed to “pick and choose” whichsystems the Army could check.
Thatemail also suggests that Segraves considered the Army inspectors a valuable public-relations asset:“They are our radiation myth busters,” she wrote to a local security director.
Some TSA screeners are concernedabout their own radiation exposure from the backscatters, but the TSA has notallowed them to wear badges that could measure it, said Milly Rodriguez, healthand safety specialist for the American Federation of Government Employees,which represents TSA officers.
“Wehave heard from members that sometimes the technicians tell them that themachines are emitting more radiation than is allowed,” she said.
McCarthy,the TSA spokesman, said the machines are physically incapable of producingradiation above the industry standard. In the email, he said, the inspectionsallow screeners to ask questions about radiation and address concerns aboutspecific machines.

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