Journalism in the Public Interest

New Army Study Says Radiation From Airport Body Scanners Is Minor

The backscatter X-ray scanners, which the Transportation Security Administration uses to check for objects hidden under clothing, have been the subject of controversy about how safe they are and whether they create a cancer risk for the traveling public.


TSA officers give a demonstration of the first backscatter X-ray full-body scanner at John F. Kennedy International Airport's Terminal 8 passenger security checkpoint on Oct. 22, 2010. (Michael Nagle/Getty Images)

A new study of airport body scanners by U.S. Army scientists shows that the machines produce a low dose of radiation, supporting Transportation Security Administration claims that a screening is equivalent to the radiation a passenger gets in two minutes of flying.

The scanners, which use X-rays to check for objects hidden under clothing, have been the subject of controversy about how safe they are and whether they create a cancer risk for the traveling public. Although the study is unlikely to douse those concerns, one critic of the machines called it the most reliable test to date.

"These are the best measurements that have been done," said Peter Rez, an Arizona State University physicist who in April signed a letter to the White House science adviser questioning previous tests. "Things have to be filled in, but it's a step in the right direction."

The study results obtained by ProPublica were presented at a Health Physics Society conference in late June.

The TSA rolled out plans to put full-body scanners at nearly every security lane by 2014 in response to the attempted bombing of a Detroit-bound plane by a man who had explosives hidden in his underwear.

The agency uses two kinds of imagers. In the backscatter machine, a passenger stands between two large blue boxes and is scanned with a narrow X-ray beam that rapidly moves left to right and up and down the body. In the millimeter-wave machine, a passenger enters a chamber that looks like a round phone booth and is scanned with radio-frequency waves.

Although the safety of both machines has been questioned, most of the attention has centered on the backscatter machine because it uses ionizing radiation, which can damage cells and cause cancer.

To reassure travelers, the TSA asked the Army Public Health Command to conduct radiation surveys at airports around the country. The new study, paid for by the TSA and done at a TSA lab, was part of that work.

There is much debate in the field about how little—or whether any—radiation is safe.

According to the Army presentation, the average dose to the body was 3.8 microrems per screening, meaning that a person would have to go through the machine more than 5,000 times to exceed the annual dose limit recommended by the American National Standards Institute. By comparison, a chest X-ray produces about 10,000 microrems of radiation.

The test also provides new information about the dose to the skin and eyes, which has been a concern because low energy X-rays deliver a large portion of the radiation to shallow tissues. The Army testers measured the average dose to the lens of the eye at 6.7 microrems and the average skin dose at 11.3 microrems, both of which were extremely low compared to the accepted guidelines.

The study, however, does not make a conclusion about whether the machines are safe.

Some scientists have estimated that the routine use of the machines planned by the TSA could result in anywhere from a handful to a hundred additional cases of cancer over a lifetime. But even with long-term tests, it would be difficult to separate the scanner effects from other common sources of exposure, such as medical X-rays and cosmic radiation from flying at high altitudes.

The test is different from others that have been done because the Army used "optically stimulated luminescent" dosimeters—similar to the badges worn by nuclear workers—to measure the radiation.

In the past, the TSA has relied on tests conducted by the Food and Drug Administration and Johns Hopkins University that used a radiation detector known as an ionization chamber. Rez and a group of scientists at the University of California, San Francisco, argue that ion chambers are inadequate for the fast-moving, low-energy beam emitted by the backscatter machines.

An ion chamber is a device that measures radiation exposure by generating an electrical current. In contrast, an OSL dosimeter is a new type of badge that uses a crystal, which is then read with a light.

Usually, dosimeter badges aren't adequate for a single scan because they need a high dose of radiation or an exposure over a long period of time to register a reading. Walking through a body scanner on the way to catch a plane would probably not produce a reading.

To overcome that problem, the Army used robots to run 93,000 screenings over two weeks. They simulated a 190-pound person by building a dummy out of water jugs arranged on a wooden frame.

Testers then placed 181 dosimeters in and around the system, according to an email ProPublica obtained from the Electronic Privacy Information Center, a civil liberties group in Washington, D.C., that sued the government to get scanner records under the Freedom of Information Act.

Rez said the study doesn't address his concern about how much radiation a person would be exposed to if the machine breaks down and the beam stops on one spot on the body. It also didn't stanch the calls from Rez and others to allow testing by outside scientists.

"From a public relations point of view," Rez said, "it would have more clout if it was done by someone who can be seen as being independent of government."

I’ll have to show that PPT file to my son…the Army used a Lego robot in their test!  Very cool!

This news comes from the same Defense Department that said floride is safe…

... and created “Operation Bronze Anvil” to blame experimental vaccine injuries on “Gulf War Syndrome…”

Good parts of all the governments of the world, especially, firstly the ones under indirect or direct control of our North-American power should just become aware of the public servants with terroristically re-acting mindset and then, despite inevtably occurring few accidents (should be taken easy like natural disasters which are cosmic activities beyond human conrtol), civilians world-wide would feel more naturally happy and secured than these tough, expensive but unhealthy securities can provide.
Good and bad, the powers of both sides of errorists are also like bacterias, similar to many creatures and creations.
We need to be wise and relax, because the more powerful antibiotics we try to administer, the more stronger they become against controllers and that’s how the creator of cosmos (outside the reach of any of the religions-manmaid old form of politics by making each human individual blind inside the head by it’s vulnerable by default belief-system) programmed things on which we human very temporary control for a limited time-being.

Oh…well then.  If the Army says it’s safe.  Wasn’t there another Army proclamation regarding safety and the levies around New Orleans just before Katrina hit?  Maybe they are right this time.  Wanna bet?

You are right! Majority of the public reps. are unable to recognize the root cause of this managable simple issue.

Either way we do not know the long-term effects of these body scanners.  What about pregnant women who go through these machines?  Or are harassed by TSA because they refuse to go through them? No one touches on this issue at all!

I went through Oakland last week when they “selected” me to walk through the scanner.

When I refused, the functionary called out loudly, “WE HAVE AN OPT-OUT!” the same way I once told partners that a cornered suspect flashed a firearm.

There was a sudden flurry of activity and I was ordered to stand still.

After about two minutes, the designated OPT-OUT! responder arrived to walk me to a SPECIAL AREA where I was subjected to a complete pat down.

It was clear that the carefully choreographed theatrics were designed to make an example of any other REFUSNIKS who were standing in line.  It took about twice as long as a normal “random search” and the BLUE SHIRT who searched me made a concerted effort to delay my progress and leave no pocket unturned.  He reminded me of the uniformed teenagers I’ve seen in countries like El Salvadior and Kenya.

This is what happens when incompetent politicians legislate procedures for telemarketers and dog-catchers to blindly obey.  Nothing is more offensive to experienced street cops who recognize “behavioral anomalies” that lead to the initial development of “probable cause.”

TSA is to safety what teacher unions are to public education.  It is a problem of political incompetence, not money, which probably had a lot to do with why Janet Napolitano heads Homeland Security.

Clark Baker LAPD (ret)

Vince Reardon

July 15, 2011, 3:38 p.m.

Oh joy! My First Amendment rights are being eroded terror threat by terror threat but not to worry—no radiation.

Yeah these things are safe, just like cell phones, cell towers, wifi, cat scans and MRI’s…. right!  The reporter should look into who is making all the money selling these machines to the airports… I bet Haliburton has their hand in there somewhere…

How long between calibrations?  How many machines were tested?  Are all the scanners made the same way, same manufacturing techniques?Some questions.

The ionizing radiation used penetrates far more shallow than any radiation exposure in flight, or that of medical uses. Hence the effective dose density in the near surface of the body is unusually high.

Ionizing radiation causes direct breaks in DNA when an event X ray collision with DNA occurs.

Non ionizing radiation is erroneously described by simpletons (or corrupt liars ) as not being capable of damaging DNA. This is incorrect, and subtly so. The absorption depth of Nonionizing radiation is approximately inversely proportional to Frequency of the radio waves.

Long wavelength AM Khz frequencies will at low doses (away from the transmitter antenna by long distances ) have ZERO impact on health since the wavelength of the radio wave is many meters, and the depth of absorption is comparable in fact greater.

But with both microwaves Ghz (cell phones) and the terrahertz Thz used in the non backscatter scanners, the depth of absorption is less than cm for Ghz and far shorter for Thz radio waves.

When a radio event (photon / particle) collides or is absorbed by near surface tissue, there is a probability that the absorption will in fact be absorbed by DNA ( it has antenna like properties for short Ghz and Thz ).

When that occurs, if in a scanner, it will likely cause the DNA to locally be cooked to death. And whether DNA is cut by ionizing radiation, or cooked by nonionizing radiation, does not matter - in the end if DNA is cooked in too many cells, you will likely get cancer.

I am a physicist, and laugh at the folks saying you could not get cancer from non-ionizing radio waves. Some physicists, some if not many engineers like to repeat the purported safety of non ionizing radiation, as if they understand what they are talking about. Hah!, and not in a good way.

The safety for non ionizing radiation is largely true only for low frequency radio waves, where the depth of absorption is very long / deep.

But not true for microwaves / 700+Mhz and Thz Terrahertz ever, when the skin depth (for absorption ) is very shallow, and the peak energy density in near surface and surface tissues is high.

Even for long wave radio energy, very high power at short distance can result in DNA damage via thermal means, but at a far far lower rate than high frequency radio waves.

walter lindstrom

July 16, 2011, 12:15 p.m.

I can’t print your excellent articles on my epson printer.
What am I doing wrong?

Good points, Mark.

Non-ionizing radiation is the type associated with cell phones.  Although cell phone salesmen (and industry physicists) rarely mention the dangers, a careful reading of the instruction guides do.

For example, the Safety and Product Information for the BlackBerry Bold 9650 discusses “Exposure to radio frequency signals” on pages 16-21.  If non-ionizing radiation is safe, why do we need five pages of warnings?

BlackBerry warns HEALTHY users to keep devices at least an inch “from your body when the Blackberry device is transmitting,” but doesn’t explain how we accomplish this while holding cell phones to our ears.

Additional warnings are provided for pregnant women and teens.  If you wear a pacemaker or other medical devices, you’ll need another seven inches of distance.  I’ve heard of cell phones that require a six inch minimum distance for healthy people, a fact that many phone salesmen are surprised to hear.

The most important line appears on page 21:


As former military and retired LAPD officer who is currently involved in more than 50 criminal, civil and military cases around the US, I have learned not to trust ANYTHING that the government says is safe. 

The standard practice is to NOT investigate “XYZ” so that when asked about the dangers they can honestly reply that “There is no evidence that XYZ is unsafe.”  And by the time that consumers start to die, companies have usually generated sufficient profits to hire lawyers and pay off the consumers they’ve harmed.

If you’re still confused, you can ask the highly trained TSA “blue shirts” - but be sure to wait until they’re done searching your pre-teen for explosives.


Despite the disconnect between common scientific wisdom and actual mechanisms ( of say non ionizing), the government partly does not intercede since this is yet (default) common wisdom even among many scientists, sadly. It is more complicated…. but you make good points.

I do think there is a dose dependence, with a far larger onset in non-ionizing radiation ( and higher frequency dependence ), but the unusual dynamic here is Terahertz - it is near all surface absorbed, which is an unusual risk - novel extent of exposure, and the backscatter is of comparable novelty for shallow absorption, for new public widespread use. The vendors do not care about public health that is a given.

I think TSA backscatter (ionizing) operators are the first line, having unusual cancer clusters recently counted, if I am not mistaken. Even Rumsfeld recently was photographed going through a TSA pat down. Telling, even if quietly so.

Cellphones are fundamentally microwaves ( like your oven ) and held close to any body part continually is not really safe, especially long term. And 10-15 year onset… clinical cancers if develops, just rolling the dice of DNA damage statistics.

On your belt holster, the phone if on, is regularly pinging to locate the cell tower ( power emitted ) and next to your ear, is near continually transmitting. Neither are good. Notably there are very fragile tissues in the ear susceptible, and there is documented evidence in higher emission call use, salivary glands are noticeably susceptible to cancers.

Re testing MIA, I think I agree with you as to $ dynamics. The government is not doing the responsible proactive role it should ( when products go to large scale - ie at onset, safety testing should be done, even if to guide use, regulate or make a call it is not suitable for safe use, even child restrictions as with cells, or hence barred )

I think a potential solution is to completely forever bar any revolving door directly related conflict of interests across all public servant positions - civilian and defense ( to serve the public now and without conflict in future ), and to eliminate any and all commercial lobbying completely, and same for baring any political contributions except by individuals ( limited to ?~$500->?$2K per election ) applicable to both candidates and political parties.  Tough medicine, but possibly warranted?

Then individual folks money & influence will matter to candidates and parties, then elections might focus on ideas, less wedge issues. Then policy dialog is public centered, rather than bouncing from conflict of interest to another for time immemorial. Then one might confer honor to public service, with fewer hidden conflicts of interest?

If no organization could donate disproportionate “influence”, government might return to, by and for the people. Presently it is sadly quite a mess, not just this topic. Quite a tragedy at present.

Read about Dr. John Sedat & colleagues of UCSF and elsewhere

Terahertz is poorly covered re safety in the wiki below. As typical most theory ignores an antenna effect with DNA, bubbles cited here are just one of many nonionizing effects, more generally called (structural) denaturing, more commonly typically thermal, but here DNA is selective as an RF antenna here ( ie athermal).

There have been so many armchair theorists claiming this and that, and few experimentalists doing substantive experimental analysis, granted non trivial to do, but certain experimental aspects might simplify examining actual effects if some thought beyond wild speculative calculations was applied. If I read another half baked math modelling theory I will gag.

Jason, the makers and sellers of these machines are same profeeters who make money from the public fund by selling a $1000 costing Trafic light camera on our North-American street for one million dollars a piece.

Walter, Your Epson printer does not work probably for an elusive intervention by a faceless monitoring third party for which some words disappeared and a word ‘terrorists’ became ‘errorists’ in my first article in this page dated: July 14, 2011.

Baker, Thanks for your inputs. The main issues ‘the standard of practice’, the wisdom of standard setters and how improvements may take place without any bloodshed are solvable by an unprecedented honest approach by all of us to the root cause. Of course it is (50%) dependant on our honesty and possible through non-violent political means that must be free of mundane greed and also any religious dogma. The Other 50% or unbiased, truly mysterious cosmic thing is non-manipulable by humans or beyond collective human controls.

Yes Mark – a real tragedy.

The blurring of the legislative, executive and judicial (i.e. “vaccine court”) branches of government has effectively dissolved the checks and balances that were designed to keep government straight.

I sometimes wonder if Putin will re-establish the Soviet Union before our elected officials do.

Since there seems to be some real experts on here, I read recently how dangerous cell towers are and have noticed they are located in cities on roofs of buildings and sides of buildings only inches from people’s apartments and offices.  I heard these things are extremely powerful and put out a strong signal that travels for miles, yet placing multitudes of them inches from habitable spaces must be extremely dangerous.  How is this possible?  Why is there no regulation over their placement?  How many people are getting cancer and all sorts of other ailments and no one is doing anything about this?  This looks like a modern day menace and I understand the cell companies are adding many more towers to the same sites and securing new sites in similar locations right next to where people work and live.


I am not an expert, but I do understand some things less comprehended.

Nevertheless, cancers take 10-15yrs to occur, and yes being as close to as cell tower - on roof, next to the transmitters is not a good idea.

Not everyone will contract cancer, some scientists might have been hinting that microwaves mostly accelerate tumor growth, but this is merely a vague memory of mine.

Regulating location / positions / distances of tower antenna from folks, is a good idea, and not done, largely for reasons no regulations of microwave power density is done ( nor wifi either ). complicated science, little adequate experiments, and even among scientists there is disagreement, some implicit by conflicts of interest not described, some by lack of data…that it is sensible to not jump the gun

BTW folks who throw politics and the like into the mix, muddy the waters unproductively, too often. Similarly Army scientists have the matter of radar safety, never properly addressed for obvious reasons.

In the case of backscatter and Terahertz airport scanner safety
( read the section referring to UCSF professor’s correct technical objections to premature incorrect claims of safety )

Check the wiki on Backscatter_X-ray under the Health Effects section

and similarly wiki on Millimeter_wave_scanner under “possible health effects”

( which is less accurately written re the technical underpinnings of the health risks )

The politically correct societ is doing a step-by-step movement toward total control over its citizens. In fear of being accused of profiling, we are now exposing our naked bodies to strangers, young children are being fondled, and the elderly are being traumatized. This sort of policy is no accident. Shadow Truth: The Ultimate Deception exposes the movement that is terminating our freedoms.

Sure and the spent uranium that we use in the middle east in our ammunition isn’t causing birth defects to the extent that women over there are afraid to have babies. 
Get in line, no talking move along nothing to see here, good little sheeple

This article is part of an ongoing investigation:
Body Scanners

Body Scanners: Risking Health to Secure Airports

In an effort to detect explosives hidden under clothing, is the TSA jeopardizing passenger safety?

The Story So Far

The Transportation Security Administration is planning to roll out body scanners at nearly every airport security lane in the country by 2014. Right now, it has deployed more than 500, split about evenly between two technologies—one using X-rays and another using radio frequency waves.

Several prominent radiation safety experts have raised concerns about exposing millions of airline passengers to X-rays.

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