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How Terahertz Waves Tear Apart DNA
KentuckyFC writes "Great things are expected of terahertz waves, the radiation in the electromagnetic spectrum between microwaves and the infrared. Terahertz waves pass through non-conducting materials such as clothes, paper, wood and brick and so cameras sensitive to them can peer inside envelopes, into living rooms and 'frisk' people at distance. That's not to mention the great potential they have in medical imaging. Because terahertz photons are not energetic enough to break chemical bonds or ionize electrons, it's easy to dismiss fears over their health effects. And yet the evidence is mixed: some studies have reported significant genetic damage while others, although similar, have reported none. Now a team led by Los Alamos National Labs thinks it knows why. They say that although the forces that terahertz waves exert on double-stranded DNA are tiny, in certain circumstances resonant effects can unzip the DNA strands, tearing them apart. This creates bubbles in the strands that can significantly interfere with processes such as gene expression and DNA replication. With terahertz scanners already appearing in airports and hospitals, the question that now urgently needs answering is what level of exposure is safe."
Although store clerks were frequently exposed to the radiation from the machines, the radiation was more dangerous to children who placed their feet directly into the radiation. The exposure rate is thought to have been approximately 0.005 Gy to 0.058 Gy per second. If children tried on several pairs of shoes per visit it was posited that they could be exposed to as much as 0.1 Gy to 1.16 Gy. In fact, experiments indicated that radiation could exceed 1 microGy per hour as far as 10 feet away from the machine.
This device should be a warning (and I think it has been if you look at how cautious people are of new technologies like cell phones). Hopefully my sperm aren't being fried when I walk through a scanner in an airport--at least the parents of the 30s were using X-rays for their convenience and not the invasion of their privacy!
My work here is dung.
So if there's a hysterical OMGCancer panic amongst the scientific illiterate, is it ethical to take advantage of that to protect ourselves against the privacy abuses of these things at train stations and airports and on the street?
Aide-toi, le Ciel t'aidera - Jeanne D'Arc.
I was at LAX with my family several months ago and there was a huge line to go through the metal detectors. Tempers were up, to say the least.
Ahead of me there was a group of Arabs, kaffiyeh, long beard, the works. Behind them was a little white haired lady apparently on her way back to "Mizzurah" after seeing her grandkids in LA. Sweet as can be old lady, the kind that talks to much to strangers on the airplane. Single serving friend, you know.
Guess who gets stopped by the TSA.
Needless to say, everyone in line was a bit pissed that the TSA was giving extra screening to the old lady when they just waved the Arab guys through without a second glance. That's when the guy behind me yelled out, "What the fuck are you morons searching her for? The towelheads are the ones flying shit into buildings!"
Turns out we were all on the same flight to Chicago. Real American guy boarded last, about 15 minutes late. TSA had a word with him, I suppose. Maybe scanned him a few extra times to make sure his DNA was totally fucked up.
If you read the story this conjecture is the results of a computer model ...NOT real measurements of actual damage to DNA - since no previous actual experiments have turned up any damage then I'd say the model is not quite right - at any rate its all theoretical and not proven with experiment
Actually, the article states that "THz-radiation can affect biological function, but only under specific conditions, viz. high power, or/and extended exposure, or/and specific THz frequency". At any rate resonant absorbance does not, as a common property, "build up from very small amplitudes" outside of Star Trek. It's a way of getting energy into particular modes of the system, which can ensure you put the energy in the place where it'll do the most good (or bad), not a way of boosting that energy.
No kidding!!! What do you say at this point?
Yeah exactly, so what if I have to have my arm amputated because of an agressive cancer caused by these scanners, at least it means I wont have to lose my arm to a terrorist!
Actually, when I decline, they've always walked me to the front of the line for the other detectors. It's saved me time in the end, strangely enough.
A few other times, when it was my turn, I simply walked to the standard detector myself, and had no issues.
(they have two normal lanes and one terahertz scanner lane at my departure airport, but I've run into them in many other places recently too)
I used to have a sig, but I set it free and it never came back.
But what if Terahertz waves can also be used to kill a cancerous tumor? Think about this ... take to sources of focused EM energy beams, neither in the Terahertz range, and aim both energy beams at a cancerous tumor. When the two energy beams coincide at the tumor, through constructive interference, localized Terahertz waves are generated that disrupt the DNA of the cancer cells to the extent that those cells can no longer replicate. Since the energy is localized, damage to the surrounding body tissue is minimal and can be repaired by the body in a short time. As a result though, the cancer is gone.
We agree. I'm not trying to go all tin-foil hat, but there are gigawatts in major cities floating around, nudging things in your body. You tell me which ones are ok [add your own citations, and I'll add mine] and everything will be fine. They'll stop the ones that have a higher statistical possibility of blowing apart DNA, RNA, or otherwise wreaking havoc, right? And everyone will follow the rule, right?
My citation is admittedly anecdotal. But her surgeries weren't. They were damn painful.
---- Teach Peace. It's Cheaper Than War.
> Better scanning, less violation of privacy, no active emitter. If true, this sounds like a
> trifecta to me. I'd much rather pass through one of these than a milliwave unit.
I would rather pass though none at all. It all looks like one big barrel of privacy invading pork to me. A costly solution to an imaginary problem. That leaves us all with less privacy, to absolutely no benefit to anyone except the people with cushy TSA jobs.
-Steve
"I opened my eyes, and everything went dark again"
It sounds like this is probably far safer and more controllable then X-Rays or Gamma Rays for the treatment of Cancer.
A big part of the idea with radiation treatments for cancer is to break the DNA of the cells such that they do not die instantly leaving a big hole, but instead are just prevented from successful reproduction. So as these cancer cells try to reproduce they die off instead. This happens slowly over time so that normal cells from healthy surrounding tissue can migrate over and fill in the treated cells as they die off.
These THz waves could target just the DNA, killing those cells in a region and unlike X-Rays may have a lower chance of creating a new cancer from the radiation itself or damaging surrounding tissues.
I am always doing that which I can not do, in order that I may learn how to do it. - Pablo Picasso
While the case for cellphone damage is looking fairly weak, EM being non-ionizing isn't why.
Yes, ionizing radiation has a lot more potential to cause damage, but non-ionizing radiation can also cause damage. Were that not the case, microwave ovens would do nothing.
Different wavelengths have different potential to cause harm. In this case, the idea is that terahertz waves may be able to do more damage than shorter wavelength infrared as well as doing more than the same powered microwaves and certainly more than medium wave AM. Even in the latter case, there are well recognized exposure limits that must be considered when doing an antenna site survey or performing maintenance.
The problem with the terahertz scanners is multiple. First and foremost, they got approved as 'obviously' safe with no evidence to back that up at all. Next, unlike incidental exposures, the scanners deliberately irradiate human beings in the performance of their primary function. Unlike my rabbit ears or my wifi, we have very little accumulated data on human exposure to THz waves. We didn't REALLY have enough on cellphones either, but have since done the studies and gotten a fortunate answer.
Disclaimer: This is the parent AC who DOES know a thing or two about RF. So here we go.
Apparently you haven't used a millimeter-wave/terahertz heterodyne receiver lately.
The most common systems have a W-band local oscillator with output power in the 10-100 mW range. Mixers these days have approximately 100 dB isolation between the LO and RF port. Since a millimeter-wave/terahertz heterodyne receiver is comprised of several stages (let's be realistic and say 3, for the 340 GHz system), we now have 300 dB reduction from (I'll give you the max) 100 mW.
While you are technically correct that nothing is perfect, if you can detect this amount of power, you will walk away with the Nobel prize in physics. The reason is simple - there are no detectors or systems that have that kind of sensitivity.
Just so we're clear on the math, that's 10^-31 W at approximately 100 GHz. The NEP of a "good" room-temperature detector is around 10^-12 W*Hz^-.5, and a "good" cryogenic detector perhaps 10^-18 W*Hz^-.5. We can beat down noise, but only as the square root of integration time. NEP is referenced to 30 ms, usually, so let's see - we need 13 orders of magnitude for a cryogenic system, and 19 for a room-temp system. Let's figure out how long we need to integrate... sqrt(BitZtream_integration_time)/sqrt(30 ms). 1 year of integration time will get you just over 4 orders of magnitude, which sounds great. The crappy part is, like I said, that noise only goes down as the square root of integration time. Thus, for even the cryogenic system where you only need 13 orders of magnitude in sensitivity, we'd have to integrate for something like 10^17 years, which is a factor of 7*10^6 greater than the age of the universe. I'm definitely not going to be doing that experiment tomorrow in the lab!
So sure, you're right, nothing's perfect. Oscillators DO leak through mixers. But if we can't detect it with systems on earth, then it's really just a figment of your imagination, or my calculations, or something like that.