Congressman/Scientist questions safety, effectiveness of scanners
Nov 23, 2010, 5:42 am
#16
Join Date: Apr 2007
Location: here and there
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Rush Holt (D-NJ) isn't just a congressman, he's also a physicist. And for a while he has been questioning both the effectiveness and the safety of x-ray backscatter scanners. He just sent a letter to the TSA about it.
twitter @RushHolt
contact (doesn't seem to block on zip, but local office zip is 08550-1031)
Phone: (202) 225-5801 • Fax: (202) 225-6025
1214 Longworth HOB • Washington DC 20515
In other NJ news, NJ State Senators MikeDoherty R=Hunterdon, Warren (@mikedohertynj, contact, [email protected], 908-835-0552) and James Beach D-Camden, CherryHill(contact, 856) 429-1572) have introduced legislation opposing nude scanning in NJ airports.
Sen. Dotherty also has an online petition.
If you live in NJ, you can find your legisators.
Last edited by neko; Nov 23, 2010 at 6:23 am Reason: many smart people in NJ
Nov 23, 2010, 7:37 am
#17
Join Date: Mar 2007
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People seem to be accepting MMW scanners as safe because they don't have the dreaded 'x-ray' term associated with them. I posted this on another thread to raise the awareness of MMW risks. The FCC doesn't know whether MMW technology is safe or not according to their website.
This is from the FCC's web site about microwave risks (millimeter wave).
At relatively low levels of exposure to RF radiation, i.e., levels lower than those that would produce significant heating; the evidence for production of harmful biological effects is ambiguous and unproven. Such effects, if they exist, have been referred to as "non-thermal" effects. A number of reports have appeared in the scientific literature describing the observation of a range of biological effects resulting from exposure to low-levels of RF energy. However, in most cases, further experimental research has been unable to reproduce these effects. Furthermore, since much of the research is not done on whole bodies (in vivo), there has been no determination that such effects constitute a human health hazard. It is generally agreed that further research is needed to determine the generality of such effects and their possible relevance, if any, to human health. In the meantime, standards-setting organizations and government agencies continue to monitor the latest experimental findings to confirm their validity and determine whether changes in safety limits are needed to protect human health.
It is well known in the microwave engineering world that microwave energy(high power) is harmful and can produce cancer or sterilization in men since the testicles are particularly susceptible. The information above shows that they don't really know about lower level millimeter wave energy health effects.
This is from the FCC's web site about microwave risks (millimeter wave).
At relatively low levels of exposure to RF radiation, i.e., levels lower than those that would produce significant heating; the evidence for production of harmful biological effects is ambiguous and unproven. Such effects, if they exist, have been referred to as "non-thermal" effects. A number of reports have appeared in the scientific literature describing the observation of a range of biological effects resulting from exposure to low-levels of RF energy. However, in most cases, further experimental research has been unable to reproduce these effects. Furthermore, since much of the research is not done on whole bodies (in vivo), there has been no determination that such effects constitute a human health hazard. It is generally agreed that further research is needed to determine the generality of such effects and their possible relevance, if any, to human health. In the meantime, standards-setting organizations and government agencies continue to monitor the latest experimental findings to confirm their validity and determine whether changes in safety limits are needed to protect human health.
It is well known in the microwave engineering world that microwave energy(high power) is harmful and can produce cancer or sterilization in men since the testicles are particularly susceptible. The information above shows that they don't really know about lower level millimeter wave energy health effects.
Nov 23, 2010, 7:58 am
#18
Join Date: Nov 2006
Location: Hell's Kitchen, NYC
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Yesterday at LAX I did the new scanner for the first time. Agents were polite, it was quick and easy, and I have no complaints except...
a physician radiologist warns that the radiation dose is extremely minimal only if the machine is working properly. How many times a day are dosages checked, or will the manufacturer explain how overdosing is avoided?
I won't join in on the bashing of the TSA agents -- like dentists everybody hates them but most are just people trying to earn a living and provide a service. Of course there are a few "I am in charge of you" power-mongers.
However, the whole concept of screening millions of people, including small children, should not be acceptable when we all know where the threat is coming from but are too PC to admit it. El Al knows what they're doing profiling each passenger. Don't worry about granny from Kansas and her two-year-old great-granddaughter, but when there's a lone traveller who has no history with you or who looks suspicious and is acting strangely, then focus your attention there.
It just annoys me that we all accept this method of screening everybody as a reasonable way to catch/deter the few who are really dangerous. Like most things about government, it defies common sense.
a physician radiologist warns that the radiation dose is extremely minimal only if the machine is working properly. How many times a day are dosages checked, or will the manufacturer explain how overdosing is avoided?
I won't join in on the bashing of the TSA agents -- like dentists everybody hates them but most are just people trying to earn a living and provide a service. Of course there are a few "I am in charge of you" power-mongers.
However, the whole concept of screening millions of people, including small children, should not be acceptable when we all know where the threat is coming from but are too PC to admit it. El Al knows what they're doing profiling each passenger. Don't worry about granny from Kansas and her two-year-old great-granddaughter, but when there's a lone traveller who has no history with you or who looks suspicious and is acting strangely, then focus your attention there.
It just annoys me that we all accept this method of screening everybody as a reasonable way to catch/deter the few who are really dangerous. Like most things about government, it defies common sense.
Nov 23, 2010, 8:01 am
#19
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Nov 23, 2010, 8:17 am
#20
Join Date: Mar 2007
Programs: AA Plat, CO Gold, Marriott Silver
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My experience is that the level of professionalism is dictated by the airport culture rather than the individual screener. When I opted out in BWI you would have thought I committed a horrible crime given their reaction (literally yelling, including at me and my family). Yet, in SAN they were very calm and professional when I opted out and treated me with respect. I thanked the gentleman for the way he treated me since he didn't make the stupid policies and was simply trying to stay employed without harassing travelers.
Nov 23, 2010, 8:46 am
#21
Join Date: Oct 2010
Posts: 449
My experience is that the level of professionalism is dictated by the airport culture rather than the individual screener. When I opted out in BWI you would have thought I committed a horrible crime given their reaction (literally yelling, including at me and my family). Yet, in SAN they were very calm and professional when I opted out and treated me with respect. I thanked the gentleman for the way he treated me since he didn't make the stupid policies and was simply trying to stay employed without harassing travelers.
Nov 23, 2010, 8:52 am
#22
Join Date: Dec 2009
Posts: 72
Also - where/how did you get 1/10 of an inch? I wasn't sure if you were throwing that out as an example or saying it was published. My back-of-the-envelope calculations (based on a NIST model for soft tissue) say it's more like 1 inch - the vast majority of the energy penetrates the skin. But I would like to check my scribbling against an expert's real data.
In your scribbling have you accounted for the fact that this is not normal incidence? It sounds like we have similar background in this area but I admit I have not done the math like you have (yet). Maybe when I get back to my office and have my library at hand. As I understand it the radiation source is over the head. The rays then reflect at glancing incidence from the skin and are collected by detectors. Since we know xrays reflect better at glancing incidence I think that makes for a logical design of the system and is consistent with other things I've heard lately. But it also means surfaces receiving normal incidence like the top of the head or the tops of the arms would absorb a much larger dose.
This could be one of those situations where the scientists and engineers built a decent system but the security goons have decided to abuse it by making people stand with arms out. That would significantly increase the dose.
But really, there are far more experts out there like you that don't work for the TSA. Let's get some facts and hard numbers out there and let that be reviewed.
Nov 23, 2010, 8:59 am
#23
Join Date: Nov 2010
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People seem to be accepting MMW scanners as safe because they don't have the dreaded 'x-ray' term associated with them. I posted this on another thread to raise the awareness of MMW risks. The FCC doesn't know whether MMW technology is safe or not according to their website.
This is from the FCC's web site about microwave risks (millimeter wave).
At relatively low levels of exposure to RF radiation, i.e., levels lower than those that would produce significant heating; the evidence for production of harmful biological effects is ambiguous and unproven. Such effects, if they exist, have been referred to as "non-thermal" effects. A number of reports have appeared in the scientific literature describing the observation of a range of biological effects resulting from exposure to low-levels of RF energy. However, in most cases, further experimental research has been unable to reproduce these effects. Furthermore, since much of the research is not done on whole bodies (in vivo), there has been no determination that such effects constitute a human health hazard. It is generally agreed that further research is needed to determine the generality of such effects and their possible relevance, if any, to human health. In the meantime, standards-setting organizations and government agencies continue to monitor the latest experimental findings to confirm their validity and determine whether changes in safety limits are needed to protect human health.
It is well known in the microwave engineering world that microwave energy(high power) is harmful and can produce cancer or sterilization in men since the testicles are particularly susceptible. The information above shows that they don't really know about lower level millimeter wave energy health effects.
This is from the FCC's web site about microwave risks (millimeter wave).
At relatively low levels of exposure to RF radiation, i.e., levels lower than those that would produce significant heating; the evidence for production of harmful biological effects is ambiguous and unproven. Such effects, if they exist, have been referred to as "non-thermal" effects. A number of reports have appeared in the scientific literature describing the observation of a range of biological effects resulting from exposure to low-levels of RF energy. However, in most cases, further experimental research has been unable to reproduce these effects. Furthermore, since much of the research is not done on whole bodies (in vivo), there has been no determination that such effects constitute a human health hazard. It is generally agreed that further research is needed to determine the generality of such effects and their possible relevance, if any, to human health. In the meantime, standards-setting organizations and government agencies continue to monitor the latest experimental findings to confirm their validity and determine whether changes in safety limits are needed to protect human health.
It is well known in the microwave engineering world that microwave energy(high power) is harmful and can produce cancer or sterilization in men since the testicles are particularly susceptible. The information above shows that they don't really know about lower level millimeter wave energy health effects.
The FCC most certainly is saying the MMWs are safe. They state that published reports of "non thermal effects" from MMW (non-ionizing) radiation cannot be reproduced. This places these "events" in the same category as cold fusion, ghost sightings, telepathy, and other such nonsense. While as scientists we invariably conclude our reports with "further study is needed", in this case the underlying physics dictate that further study would be a waste of resources.
Regarding the other "well known" stuff (I'm curious about your source, if you have a link), yes, a high intensity of microwave photons can be harmful, just as a high intensity of infrared or visible photons can be harmful. If your body absorbs too many of them too quickly, you over heat and you literally cook. These are thermal effects. At low levels your skin simply absorbs the energy and gets warmer, and your body compensates for the increased warmth just as it would from any other heat source. As such, a millimeter wave machine is no more physically harmful than a light-bulb of equal wattage.
The harm to our privacy, our civil rights and our pocketbooks however is very real.
Nov 23, 2010, 9:11 am
#24
Join Date: Mar 2007
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This article, http://www.nytimes.com/2010/11/23/us...d.html?_r=1&hp, explains why BWI TSOs treated you like a criminal.
Perhaps someone should tell Mr. Burdette that he is no longer in the military (no disrepect implied to the military) and that travelers are not recruits that are to be yelled at for every move. I have great respect for the military and the incredible job they perform heroically every day but an airport is not a military facility(as he seems to think). I would say the same for the head of TSA, Mr. Pistole, and his desire to assume every traveler is a criminal and implement these stupid procedures that don't make any of us any safer. A big step forward would be to interrogate every traveler as the Israelis do. The TSA already stops every passenger for an ID check anyway. When I was flying to/from Europe during the terrorist activities of the late 80s that was the routine in European airports.
Nov 23, 2010, 9:41 am
#25
Join Date: Dec 2007
Posts: 629
@ DoingHomework:
That design sounds like it could be described as an x-ray shower of sorts. I have read that the wavelengths of the x-rays used in the backscatter machines are significantly shorter than standard medical x-rays, but I haven't seen any firm numbers. I haven't seen the shorter wavelength issue mentioned in the press at all. I would assume that shorter wavelength x-rays would benefit a security scanner in two ways:
1) The higher frequency EM waves would be more likely to bounce off the subject without penetrating below the skin than lower frequency x-rays.
2) Shorter wavelengths result in a higher resolution (in the sense of resolving smaller details).
Of course the downside of using higher frequencies than are typically used in medicine is that higher frequency equates to higher energies and tends to cause more damage in living tissue as a result. From what I have read, the traditional "x-ray spectrum" was defined as having a wavelength between .01 and 1 nanometers. Or a factor of 100x difference in wavelength. X-rays have since been redefined to well under .01 nanometers into territory that used to be thought of as gamma rays. So without any specific numbers it is really hard to say how short a wavelength of x-ray the machine emits, but it could even be thought of as a "gamma ray scanner" (based on the older definitions) if the wavelength were short enough. Now that sounds scary.
Do you think that a very low power Compton scattering gamma ray imaging device could be analogous here? If it were possible to create one could the cell damage be limited by just reducing the transmission power a lot or are gamma rays so inherently damaging that there would be no way to make it as safe as an x-ray imager? IOW, perhaps these higher frequencies are more dangerous even if the total energy in electron volts is the same.
The point I am trying to make is that even if backscatter x-rays have 100x less power output than medical x-rays, depending on their wavelength they could have 100x more energy and be 100x more damaging (if you assume a linear relationship) resulting in radiation that is just as dangerous even though the power output is much lower. The wavelength that these devices operate on should be published so that we can decide for ourselves how they compare to medical x-rays. OTOH, maybe the higher frequencies are already accounted for by measuring output in electron volts instead of power/frequency/wavelength.
Note that I am not a physicist. I took some physics courses for my Electrical Engineering degree but that was quite a few years ago at this point. So please feel free to correct any inaccurate assumptions here.
That design sounds like it could be described as an x-ray shower of sorts. I have read that the wavelengths of the x-rays used in the backscatter machines are significantly shorter than standard medical x-rays, but I haven't seen any firm numbers. I haven't seen the shorter wavelength issue mentioned in the press at all. I would assume that shorter wavelength x-rays would benefit a security scanner in two ways:
1) The higher frequency EM waves would be more likely to bounce off the subject without penetrating below the skin than lower frequency x-rays.
2) Shorter wavelengths result in a higher resolution (in the sense of resolving smaller details).
Of course the downside of using higher frequencies than are typically used in medicine is that higher frequency equates to higher energies and tends to cause more damage in living tissue as a result. From what I have read, the traditional "x-ray spectrum" was defined as having a wavelength between .01 and 1 nanometers. Or a factor of 100x difference in wavelength. X-rays have since been redefined to well under .01 nanometers into territory that used to be thought of as gamma rays. So without any specific numbers it is really hard to say how short a wavelength of x-ray the machine emits, but it could even be thought of as a "gamma ray scanner" (based on the older definitions) if the wavelength were short enough. Now that sounds scary.
Do you think that a very low power Compton scattering gamma ray imaging device could be analogous here? If it were possible to create one could the cell damage be limited by just reducing the transmission power a lot or are gamma rays so inherently damaging that there would be no way to make it as safe as an x-ray imager? IOW, perhaps these higher frequencies are more dangerous even if the total energy in electron volts is the same.
The point I am trying to make is that even if backscatter x-rays have 100x less power output than medical x-rays, depending on their wavelength they could have 100x more energy and be 100x more damaging (if you assume a linear relationship) resulting in radiation that is just as dangerous even though the power output is much lower. The wavelength that these devices operate on should be published so that we can decide for ourselves how they compare to medical x-rays. OTOH, maybe the higher frequencies are already accounted for by measuring output in electron volts instead of power/frequency/wavelength.
Note that I am not a physicist. I took some physics courses for my Electrical Engineering degree but that was quite a few years ago at this point. So please feel free to correct any inaccurate assumptions here.
Nov 23, 2010, 9:49 am
#26
Join Date: Aug 2010
Location: USA
Posts: 549
These really make me feel warm and tingly:
“I want them to think Abdulmutallab with every pat-down,” Mr. Burdette said.
Four years ago, Ms. Wade was working as a waitress and a bartender. Now, she said, “I just try to stay alert and mitigate any threats that I see.”
Jennifer Adams, 33, who assessed each traveler with a smile and a subtlety that suggested she was merely an official greeter. She joined the T.S.A. eight years ago, after earning a college degree in communications management, and has risen to become a supervisory behavior detection officer.
“I’m entrusted to report here and protect the homeland,” she said.
Nov 23, 2010, 10:03 am
#27
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It's really laughable that these former bartenders and the like believe that they are protecting "the homeland." Good grief. Even George Orwell couldn't have imagined how far we have fallen.
Bruce
Bruce
Nov 23, 2010, 10:16 am
#28
Join Date: Mar 2007
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The higher EM waves aren't likely to bounce off but will penetrate to a lesser depth into the body. They will be absorbed (and generate heat) by the skin which is still problematic for those that are susceptible to skin cancer.
Nov 23, 2010, 10:43 am
#29
Join Date: Dec 2009
Posts: 72
Without knowing the complete details we can't really say what the danger level is. But the details are being hid in a cloak of "security" that prevents any of this from the scrutiny it should have.
Nov 23, 2010, 11:00 am
#30
Join Date: Mar 2007
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It's actually not that simple. The incidence angle and the dielectric constant of the various skin layers makes all the difference between reflection and absorption as does the specific frequency. In optical wavelengths we can make surfaces that reflect very nearly 100% of one wavelength and transmit almost 100% of a wavelength a few nanometers away. Nature has done the same thing with various structures in animals and humans.
Without knowing the complete details we can't really say what the danger level is. But the details are being hid in a cloak of "security" that prevents any of this from the scrutiny it should have.
Without knowing the complete details we can't really say what the danger level is. But the details are being hid in a cloak of "security" that prevents any of this from the scrutiny it should have.
What you and I do agree on is the simplicity and accuracy of your last statement above (bolded).
All respect to your viewpoint. ^