Link to the AS&E "ZBV" mobile X-Ray van in question [0], sourced from the linked Fox News article. From the AS&E website:
"Dose to Cargo: Less than 0.1 microSievert (μSv) per scan (equivalent to 10 microRem (μrem)), at an average speed of 5 km/h (3 mph) at a scan distance of 1.5 m (5 ft). Should a stowaway accidentally be scanned, the effective dose is well below the ANSI specified limit for accidental exposure and is equivalent to flying two minutes at altitude."
I don't consent to any form of non-necessary irradiation, regardless of the quantity.
Not sure why the NYPD gets to irradiate me without consequences (which constitutes a search of my person, without a warrant or consent, not to mention having a potential medical impact on people not suspected of any crime) when we can hardly point cameras at them despite it being explicitly legal.
Your consent is not needed even for unnecessary radiation. If I shine my high beams on your car, or have a cellular phone call next to well - too bad. I'm entitled to bombard you with radiation if I want to.
But for the sake of argument Ill assume you just care about ionizing radiation (UV, Xray, Gamma, Neutron, etc). In that case I agree consent should be needed for medium to high dose. It's unfeasible to get the consent of everyone for low doses (x-ray machine x-rays can travel for miles and theoretically infinitely far).
In this case it appears the dose is only about that of eating a banana. Hard to argue you need to consent to that for radiation concerns unless you also agree that everyone should consent to every xray scan that every hospital executes, or every time your colleague brings in bananas to work. Privacy concern is valid though. Radiation one is just fear mongering if OP is correct.
That's PER SCAN. Do you think the Police roll up, do a scan, and then take off? No. They're sitting there scanning constantly (most likely), so to use your analogy, that's a lot of banana eating.
And are we assuming that the person is inside a metal vehicle? What if someone is outdoors?
How much radiation does this scanner actually emit? The numbers are meaninglessness without more information. Why doesn't the manufacturer just publish the hard numbers?
Can be, yes. How often will it be? How often will it be operated remotely, and there's no other police in the immediate vicinity doing traffic control or some such?
[Edit: the article also talks about scanning the inside of a house in 15 seconds. That's not going to happen if they drive up the van, park it, get out, walk 1500 feet away, scan the house, walk back... (Yes, I know, they can drive away and back in another vehicle. It's still not likely to be operated remotely in that usage - all the activity makes it too conspicuous.)]
> They are not hard to spot. Watch the media entrances of events, where the on-location vans drive through. Look for where traffic is routed through a single lane. Inevitably they will route traffic past an unmarked van. Or, look for an unmarked van trolling any parking lots within any security cordon.
That "look for where traffic is routed through a single lane" makes me strongly suspect there's going to be traffic officers in the very near vicinity.
>That "look for where traffic is routed through a single lane" makes me strongly suspect there's going to be traffic officers in the very near vicinity.
In that case those "traffic officers" will be further down directing traffic to the van, not in the van's target.
> If I shine my high beams on your car, or have a cellular phone call next to well - too bad. I'm entitled to bombard you with radiation if I want to.
I think this is a really good point, actually. Do all these electronic devices need to be FCC approved? And if so, how do these vans' dosage gybe with any FCC regulations?
That's equivocation at its best. Candles do not emit ionizing radiation in measurable quantities. X-Ray machines do. There's a huge distinction, similar to the distinction we make between shining an incandescent bulb up at a helicopter or passenger plane, and shining a laser pointer.
So we regulate X-Ray machines keep the radiation leak below the level that would oblige to ask people in the area for consent. GP has a point. The concern in this thread is based entirely on the notion that "radiation" is a scary-sounding thing.
No, the concern in this thread is based entirely on the notion that innocent people are potentially being exposed to X-rays, without their knowledge or consent.
You're arguing against a strawman. HN commenters aren't idiots. The technology in question is using ionizing X-rays, which can have harmful health effects.
I never assume HN commenters are idiots. That's the very reason I hang out here - I learn a lot from what people say in this place.
Having said that, this thread is dominated by commenters who refuse to do the math. X-rays sound scary but they aren't death rays; if you add up the numbers you'll see that it's not even worth to talk about them here. There's higher probability they'll harm someone by introducing more cars onto streets.
What if there is a machine malfunction? Lack of proper maintenance? Operator error? Sure there should be fail-safes, but accidents happen.
Bouncing around in the back of a van, something goes wrong. Instead of a rapidly moving beam of x-rays that doesn't stay in one location long enough to cause problems, you get a focused beam.
Those are fair concerns. I haven't seen the estimate for maximum amount of radiation the X-ray machine could generate when malfunctioning. We need those to see whether or not there is something to worry about.
If it works anything like the backscatter machines the TSA was using (rapidly moving beam), a failure mode like what I mentioned is definitely enough to be dangerous. There was a physics professor from Arizona state who said that the TSA machines could even cause radiation burns if the fail-safes failed and the beam kept going while stuck in one position.
It many not work that way though. Who knows? That's the problem with being secretive about the whole thing. They don't publicly release data on potential malfunctions.
One of my biggest concerns is the amount of training the operators receive on recognizing and reporting potential malfunctions. I suspect it's not sufficient, but again who knows? They won't talk about it because terrorists.
I agree, those are causes for concern. It doesn't matter if they're using radiation - whether they'd be using chemicals, biological agents or voodoo, as the issues of proper training and secrecy around a device that fails dangerously is a serious matter. They should be opposed as everything from waste of tax money to being a public safety issue, just not because of the radiation per se.
I disagree. I think it is worth it to talk about them, for three main reasons:
1. Even if this machine only gives off radiation equivalent to, say, a dental X-ray, I still did not give my consent for it, whereas I did give my consent for the dental X-ray. Consent is important. There are a lot of things that are OK with someone's consent, but not OK otherwise, and we don't have the right to make these decisions for someone.
2. Medical X-rays have positive expected trade-offs for receiving the dose of radiation. Compare this to an X-ray police van than I happen to walk past; there's not really any argument that can be made for why my exposure to this X-ray radiation is worth it for me.
3. The machine can malfunction, or be used improperly, and give off substantially more X-ray radiation than expected or designed. Safeguards are in place for other uses of X-ray to protect against this, e.g. you wear a lead apron to protect the rest of your body during a dental X-ray, and the assistant taking the X-ray leaves the room entirely. Safeguards of these sort aren't possible with the presence of an unknowing public.
There's also of course the entire privacy aspect that we haven't even delved into yet, but the health issues alone are concerning.
So, in any case, the FCC has set limits for acceptable amounts of radiation exposure from certain classes of the electronics that we find all around us every day, and I guess I was just wondering how those limits would compare to the radiation dosage of these vans.
It might not be approved by the FCC, but if it's equivalent to something that the FCC would allow you to carry around in your pocket anyway, it's hard to justify being upset these vans driving around from the perspective of being exposed unawares to their radiation.
There are a number of other reasons to be upset about such vans, though.
So why don't you try the laser experiment. Use a 1 milliwatt laser. That's _less_ energy than the light bouncing from your skin. That's nothing. And it's non ionizing radiation. So it's totally safe. Point it right in your eye. See what happens. By the completely over simplified thinking that you are undertaking here you will be fine. Right?
I meant that light bouncing from skin to eye is a proper analogy for banana dose.
But since you challenge me - I shined the usual ~5mW red laser pointers many times straight into the eye, and had strangers shine them at me as well. It's annoying, but it doesn't hurt. My vision is ok. I'm totally fine.
The quantities of radiation quoted by the manufacturer are extremely low. The actual effective absorbed dose might be different from what they actually say, of course.
I am anticipating that someone will come forth to defend this illegal searching by claiming that the radiation dose is negligible or irrelevant. I want to counter this defense by posing the matter as philosophical rather than an empirical question of whether the irradiation is harmful or not.
EDIT: Ah, in the time that it took me to write this, I have been proven correct.
The quantities of radiation quoted by the manufacturer are extremely low.... when the machines are in proper working order, and maintained and operated as intended by the manufacturer.
My dentist had to take a course in health physics before being allowed to use an X-ray machine on humans. So did my doctor. What makes TSA agents and New York cops so special?
Again, i was simply quoting the manufacturer. Adding information to the conversation. You dont have to believe it or agree with it, but it's a side that should be heard rather than downvoted.
it's only objective in the context of people who understand the magnitude of the numbers being quoted. No data is provided as to alternate sources of radiation. An analogy is made by the manufacturer, but they have incentive to claim that level is as low as possible.
And, without any other information, the specific quotation being presented appears to imply you think it's no big deal (since you didn't offer any interpretation or make a statement relating to your opinion on the matter).
(though to note, I didn't downvote you, I'm just explaining how the information could be seen as "subjective" and not "objective").
I don't think you should be downvoted, but realize that people might be responding negatively because the citation you provided is exactly the citation that defenders of the vans and backscatter scanners at airports provide to dismiss safety concerns. So, without context around your citation, it might seem that you're trying to provide an opinionated defense of the safety of the vans.
As others have mentioned, there are also issues regarding whether those numbers can really be interpreted to mean that they are relatively safe. The manufacturers of backscatter tech claim that's true, but others suggest that because of the concentration in the skin, it's not a good estimate of safety. To interpret your cited numbers, the discussion also needs that side of the story, which other commenters have provided, but your original post did not.
> there are also issues regarding whether those numbers can really be interpreted to mean that they are relatively safe.
And contributing the manufacturer's stated specifications ADDS to that conversation, which meets the criteria for 'goodness'.
Not directing this at you, as you've already acknowledged that the OP should not have been downvoted, but additive facts should, probably as a rule, never be downvoted on account of knee-jerk reactions.
Philosophically, the government should not be irradiating people without their consent under any circumstance. Empirically, there is no* health risk from doing so with these vans.
* By any reasonable measure of increased incidence of cancer from small doses of radiation.
Except there's nothing to support the latter statements. The statement made by the manufacturer 1) could be totally false, 2) refers to a specific single-use of the technology.
They're claiming a specific output per-scan. What if the police are using this van with 10-second scan intervals, pointed at the same building, with people inside, for several hours? That's a fairly plausible scenario which could result in several ORDERS OF MAGNITUDE more irradiation.
> That's a fairly plausible scenario which could result in several ORDERS OF MAGNITUDE more irradiation.
"Orders of magnitude" is not a magic phrase you get to throw around to scare people.
Assuming 10 seconds intervals and instantaneous scans going on for 8-12 hours you've gone up just about 3 orders of magnitude. That is, from banana-equivalent dose to about the background radiation dose, per this handy radiation reference[0]. In other words, people in that building receive twice the amount of radiation that they would naturally do.
That is assuming a hell and a lot of scans while also ignoring the protection offered by distance and the building itself.
It wasn't thrown around to scare people, it was used because it's accurate. I fail to see how my statement is inaccurate considering by your own admission there are indeed several (3) orders of magnitude difference.
The point I was trying to make was saying that it's some negligible number is wrong. By your own handy reference, it's the equivalent of 2 Dentist x-rays.
The dentist at least has the decency to put a lead bib over you.
> I fail to see how my statement is inaccurate considering by your own admission there are indeed several (3) orders of magnitude difference.
"Three orders of magnitude" is a meaningless thing without context, and I just pointed out that in this context it still doesn't change the conclusion that the exposure is neglible and not worth considering.
> The dentist at least has the decency to put a lead bib over you.
That's because people are irrational and you need to dance around them for their own sake.
> What I'm saying is: That's not entirely relevant if we don't know how many doses people actually get.
True. But then if we count up the reasonable upper bound of possible doses you could get, like "several thousands times a day times amount X", and it still adds up to "not harmful", should we keep being distressed about it?
Assuming 100nSv per scan (first comment in this post). 10s per scan. ~4000 scans in 12h.
-> 400uSv = 0.4mSv.
Background where I live: 2mSv per year. So this is a fifth of the yearly background dose at my place. But in a single day.
For example, scan the entrance/exit of a parking garage (such as one under supervision) regularly, and you have a realistic chance of severely harming the guy at the ticket booth.
I skipped an order of magnitude here. Your calculation seems correct, so we're up to about a mamogram / day (still ignoring the distance and shielding effects of the building, but we're computing the reasonable upper bound on exposure).
Over the year this 0.4 mSv adds up to about 146 mSv. Per the Handy Chart, it's between EPA dose limits for emergency workers protecting valuable property and for those in lifesaving operations. It's about 1.5 times the "lowest dose clearly linked to increased cancer risk".
So in the worst reasonable case, this seems to be indeed causing an unnecessary increase of cancer risk. Personally I think the conditions for that upper bound are very extreme so the real dose in actual use would not be nowhere near the amount calculated above, but at this point I have to agree there's a reason to be concerned and demand more information about the deployment and capabilities (especially radiation output in failure modes) of those machines.
In short: most likely still not in any way dangerous, but the revised margins are much slimmer, therefore there is a reason for concern.
I apologize for misleading anyone by accidentally skipping a zero.
> Philosophically, the government should not be irradiating people without their consent under any circumstance.
So you are against public broadcasting systems? You also don't think that a government should have a moral duty to operate an emergency broadcast system for helping people deal with natural disasters? X-rays and radio waves are both EM radiation.
To be even more pedantic, this stance also means that a government building would not be able to have any lights or heaters (amongst other things). Or a cop searching for a suspect at night wouldn't be able to use a torch.
I think it's a bad, absolutist philosophical point to make.
I think the poster was referring only to ionizing radiation (the kind proven to increase cancer risk). Light fixtures and heaters (infrared) don't fall into that category.
You are correct - I was mostly speaking for effect. But the absolutism is still a problem. For example, if you get into a car accident and are taken to an emergency department in a state where your life is in jeopardy but you are unable to provide consent - should the medical staff have the moral right to do x-rays, which greatly aid their diagnoses?
Also, the medical staff are irradiating you for the direct purpose of aiding you specifically. The police are irradiating you because they've decided you are by default a suspect worthy of search simply by virtue of passing by - the benefit you receive in return for any health risk is debatable at best.
Was it supposed to imply anything? Or it was just an information dump for information's sake, leaving it to the readers to make their own conclusions?
Because regardless of what your post's purpose was, people are obviously gonna read that extract as "hey, it's inside safety limits, so it's ok".
When we post something without further comment it's quite safe to assume that people will think we agree with it, and we're using it to pass a message (especially the most obvious reading it has). The only other interpretation that's (a little less) common, is for people to think we've quoted it sarcastically.
"I don't consent to any form of non-necessary irradiation, regardless of the quantity."
Standing in front of the US capitol building for about an hour is also about 0.1 uSv. Granite is quite radioactive, you know. Some kitchen countertops are much worse.
0.1 uSv is also the generally accepted as the "banana equivalent dose". Bananas are a decent source of potassium, which aside from being an essential element is also somewhat radioactive.
There is no fixed accepted dose rate for flying. More than a couple and less than a dozen uSv/hr is about as accurate as you're gonna get. Depends on flight path and altitude and who knows what all else. The claim that its a couple minutes of flight is not all that far from the truth, more or less.
People who don't really understand what they're afraid of can't rationally minimize risks anyway. Perhaps the granite in a kitchen countertop or architectural decorative feature would increase cancer death rate by 0.0001% but cancer due to chemical catalyst contamination in a replacement laminate countertop MIGHT be ten times the cancer death rate of radioactive granite. Or maybe not.
Assuming they're telling the truth about the dose, I wouldn't worry about the radiation dose. Its small enough to be measured but biologically irrelevant.
What is highly suspicious is a police state violating constitutional amendments probably isn't very concerned with citizen health and probably feels no need to tell the truth. I could see some PR guy claiming its only 1 banana-equivalent-dose or an hour sitting at a granite countertop or whatever because he knows its irrelevant, even if the actual dose is so high that passersby hair is falling out and they're getting radiation burns because its an enormously higher dose. I mean, the government would never lie to us, would they?
An analogy of your argument: gravity exerts harmless levels of physical force on your body, therefore the government has the right to exert harmless levels of physical force on your body.
By the way, radiation exposure is cumulative throughout your lifetime. There is no safe minimum level of radiation exposure. How much radiation you get on a flight is irrelevant to the topic at hand.
By the way, radiation exposure is cumulative throughout your lifetime. There is no safe minimum level of radiation exposure. How much radiation you get on a flight is irrelevant to the topic at hand.
> By the way, radiation exposure is cumulative throughout your lifetime. There is no safe minimum level of radiation exposure. How much radiation you get on a flight is irrelevant to the topic at hand.
It still doesn't matter; assuming the official values are correct within two orders of magnitude, those scans still get dwarfed by the natural background radiation you are exposed to every day.
Complaining about this, or expecting someone to get consent for such levels of radiation, is ridiculous (yes, there are very important reasons for which one should oppose those scans, but radiation is not one of them). It's just failure of thinking by refusing to do the math. By the same token, why should we allow you to increase risk of heart attack of everyone here by using scary-sounding words like "radiation exposure" in the comments? Stress adds up too.
I think most of us here are aware of the basic nature of radiation exposure and have also seen this popular XKCD chart. I personally had to learn a lot about radiation exposure due to a bout with thyroid cancer and radiation treatment and scans. But that is not the point. It's not about the dangers of radiation. It's about the right to expose people to radiation at all, regardless of the danger level.
By your reasoning, it would be OK for the police to take a few pennies here and there from large bank accounts.
> By your reasoning, it would be OK for the police to take a few pennies here and there from large bank accounts.
By my reasoning it's ok for the police to drive around in their cars even though they add up to traffic, which costs a lot of people some pennies lost in gasoline and opportunity cost.
The only reason we're talking about it is because "radiation" sound scary while other things, like "time lost in increased traffic" do not. At the levels of danger we're talking about here we should not be bringing concept of people's rights, lest we want to also regulate disagreeing in Internet comments because of increased heart attack risk from stress.
> The only reason we're talking about it is because "radiation" sound scary
Radiation doesn't "sound" scary, it is scary. And for very good reason: because at the hands of people who don't understand the dangers, it can be absolutely devastatingly lethal.
Take for instance the irradiation accident in Goiania (Brazil) where a radioactive source was removed from a trashed teletherapy machine by people scavenging for scrap.
This is from the IAEA report on the case:
After the source capsule was ruptured, the remnants of the source assembly were sold for scrap to a junkyard owner. He noticed that the source material glowed blue in the dark. Several persons were fascinated by this and over a period of days friends and relatives came and saw the phenomenon. Fragments of the source the size of rice grains were distributed to several families. Theis proceeded for five days, by which time a number of people were showing gastrointestinal symptoms arising from their exposure to radiation from the source.
Result, 249 people contaminated, 4 of which died and 28 suffeed radiation burns, plus environmental contamination kilometers away.
That's why people are scared of radiation. Because it can seriously mess you up.
And I fear that going around and saying "it's totally harmless, like eating a banana" is really not helping the people who use it to be really, really careful how they use it. And they should- because if they don't then it's not at all harmless.
Basically, a backscatter van like the ones we discuss here, if left at the hands of people who do not have any training as radiologists (and possibly even then) is, indeed, for all intends and purposes, a chariot of death with an invisible death ray gun.
Tell me what keeps the operators of this sort of van from forgetting the scanner to "ON" pointing at a crowded building and going for a wee, or a coffee, or taking a nap or whatever. People have done much, much more stupid things than that. See above- glow-in-the-dark powder. They thought it was magical fairy dust and daubed it on their babies [edit: actually that was in a very similar accident, in Ciudad Juarez]. 'Nuff said?
"those scans still get dwarfed by the natural background radiation you are exposed to every day."
As others have said, the effects of radiation are additive, therefore those scans are not "dwarfed" by the natural background radiation etc, they increase it.
Take heat as an analogy. If the background level is at your body temperature and seventy different processes raise it by 1 degree C, you'll boil in your own skin. The background level is safe, each raise is safe, but added up they kill you.
The question is: is this possible with those vans? Is it conceivable that, in some cases, for some people, they may cause a lethal increase in their daily dose of radiation? Is it possible to know this for sure? Uncertain death is even scarier than certain death and for very good reason.
A far better gravitational analogy, assuming I did the numbers right in my head, when a cop stands a normal distance away from me while talking to me, the gravitational force he exerts on my body is assaulting me with about ten billionths of a newton. Depending on how many donuts he's eaten in his career the force might be higher but it would be in the "dozens of billionths of a newton" for sure. And no means no, and no level of assault is acceptable.
Having a cop stand to either side of me superficially would balance the gravitational force, but unfortunately I'd still be getting violently physically assaulted by tidal forces as my flesh stretches out ever so microscopically toward them both.
The government already entitles itself to do far worse things than bounce a few photons off me now and then -- eg every year they pry open my wallet and entitle themselves to a very large fraction of my income.
You should also be wary to chose the new place carefully, there are many areas on Earth where the background radiation is higher than in NY with a scan-van on every corner working constantly.
So, by that argument, we should just let the government do anything then? I once had a similar argument with a friend who insisted there should be stricter gun laws "because the government already has tanks and planes, so the second amendment doesn't make any sense anymore; they could always bomb the shit out of the public if they wanted."
I think the opposite is truth: we need to act now while we still have some power, rather than assume a defeatist attitude and let our children and their children at the mercy of a fully omnipotent government.
No, my actual argument is that all arguments of the form "If the government is allowed to do X then they have to be allowed to do Y, Z and Z' " are a bit silly.
The problem is that x-rays use ionizing radiation which is more dangerous. Some people could be more sensitive or in a more likely scenario they get a lot of x-rays and/or ct scans due to medical issues which requires them being very careful about spacing out scans and exposure to other sources.
Then there is the possibility someone walks in between the van and target. At some point you have to stop the argument that this and that does x and y so z is ok. People are afraid of excessive radiation and the government isn't listening to people.
One thing that infuriates me is that people making these arguments don't even know that x-rays (and cats) use ionizing radiation which is what carries real risks. Incidentally, MRIs do not use ionizing radiation so you can stay in there a "while". Thats how they can do so many cool studies using MRIs.
The problem is people refuse to do the math, or to listen to people who did the math. All they hear is "that scary r-thing".
At this point I think this link will beat Meditations on Moloch in the "most often posted in comments by this user" statistic, but once again I'm pointing to this helpful chart: https://xkcd.com/radiation/.
> People are afraid of excessive radiation and the government isn't listening to people.
People are afraid of a lot of things, and at this point I'm not sure how we should deal with it on a social level anymore. They are scared of radiation, therefore allow for lots of unnecessary deaths, destruction of the environment and even more radiation by refusing to replace coal plants with nuclear ones. They're also afraid of vaccines, microwaves and cell-phone EM radiation (how they were never afraid of radio waves in pre-cellphone era is beyond me, but maybe they initially were but got over it).
That people are afraid of things that aren't dangerous doesn't mean we should stop doing that things. As for how to make people not afraid, I don't know anymore. Maybe we should just pay the advertising industry to fix that with propaganda?
Interestingly, due to the altitude it flew at Concorde included a radiation detector that triggered a cockpit warning light when the incident ionizing radiation exceeded a preset limit. The standard operating procedure if the warning was triggered was to descend to a lower altitude.
(Presumably this was more about the aircrew's cumulative dose than the passengers).
The information look to be carefully selected to paint a very biased picture. It assume a certain amount of metal is between the scanner and the human being, and the air flight comparison is there to minimize the emotional response to risk.
Let assume that this van and flying two minutes at altitude gives around 0.00something risk to cancer and thus death. If someone shoot a gun into the air, do they expose innocent people to the same risk as this mobile X-Ray van? What about a factory that dumps mercury into the water supply, and then compare that to the average increase in heavy metal from eating a single banana?
Objective information is easily shaped to change public opinion, and I for one will be very careful when it is about unnecessary exposure to risk (and I can guarantee that the operators of the van uses protective gear against radiation).
Interestingly, it's nearly the same radiation dose as is living within 50 miles from a nuclear power plant for 1 year. Which is only interesting since the Indian Point nuclear power plant is ~35 miles from Manhattan.
The top layers of your skin is ~5% of your body weight and your only getting that on one side of your body so ~2% of your body weight.
Thus, even if the average is 1 banana equivalent dose, your skin is getting ~50 times that which may or may not be safe, but it sounds worse.
PS: Of course this also assumes nothing breaks and it stays in motion, if the vehicle stops without turning off you might get hundreds or thousands of times that.
You're presumably thinking alpha particles if you're thinking of radiation which is stopped by, and therefore concentrates measured exposure at, your skin. I rather strongly doubt this machine uses alpha particles. Considerations which make me doubt this: they would get blocked by insulating materials such as e.g. the side of the surveillance van, the side of your vehicle, 3 cm of open air, etc.
No, X-rays have different penetrating power based on frequency. There using a back-scatter approach as it's just one van which means very low penetrating power. https://en.wikipedia.org/wiki/Backscatter_X-ray
Bananas throw out beta radiation. It's not as penetrating as alpha - attenuation depth in water on the order of centimeters rather than millimeters? - but I think a banana-equivalent dose will be pretty solidly concentrated in your digestive tract.
No, the banana is radioactive from potassium-40, which your absorbing and spreading throughout your body.
However, you also excrete potassium making the Banana equivalent meaningless as it's calculated by assuming you kept that potassium for 50 years which simply does not happen. AKA you would end up with less than 365 Banana equivalent doses by eating 1 banana a day for 1 year. (https://en.wikipedia.org/wiki/Banana_equivalent_dose)
Its mostly the fault of one isotope of potassium and many hiker types eat bananas specifically to boost their blood K levels because otherwise they get really annoying muscle cramps. Its a moderately strong beta emitter and the range in water (close to human body) is about 2 cm or so. There are probably no parts of your innards more than 2 cm from the nearest bodily fluid (blood or whatever).
Humans are surprisingly radioactive BTW. We each have about a hundred grams of potassium happily radiating away. An interesting technological challenge for a startup might be using purely passive radiation monitoring to detect humans. For security sensing or something. Maybe in a 100 years automatic supermarket style doors will sense humans radioactively rather than current microwave doppler and infrared systems. Maybe.
> An interesting technological challenge for a startup might be using purely passive radiation monitoring to detect humans.
Beta is super-easily stopped. A piece of cardboard or tinfoil reduces it dramatically, or stops it completely, depending on energy per particle, total flux, etc.
I've a Luminox watch, the dial is visible in darkness all the time, you don't have to "recharge" it. It works by having small amounts of tritium decay within luminescent tubes. The radiation produced is beta - but the levels of radiation outside the watch are essentially zero. The body of the watch is enough to contain it.
Again, and as others pointed out in other contexts here, it depends on the energy. Tritium has 20keV betas AFAIR. Some elements produce multi-MeV beta decay. That is not stopped by thin cardboard.
Isn't all x-ray exposure one sided based on the radiation source? Doesn't all radiation exposure start with the skin? X-ray penetrate so not all energy is deposited on the skin's surface.
> The radiation doses emitted by the scans are extremely small; the scans deliver an amount of radiation equivalent to 3 to 9 minutes of the radiation received through normal daily living. Furthermore, since flying itself increases exposure to ionizing radiation, the scan will contribute less than 1% of the dose a flyer will receive from exposure to cosmic rays at elevated altitudes.
Backscatter deposits that radiation disproportionately in areas of the body that are prone to cancer - skin, testes, breast tissue, etc.
So those areas that are particularly sensitive take a disproportional hit with this technology.
This [1] is a letter from a group of prominent scientists and oncologists at UCSF who wrote a letter to the White House about the uncertainties of the technology when it was used by the TSA at airports.
I was lucky enough to ride on the Concorde from Heathrow to JFK when I was about 12 (the 747 (seats ~400) we were supposed to take broke down, and they only had a 737 (seats ~300) and a concorde (seats 100) available; my dad, having many tens of thousands of airline miles and super double platinum status on basically every airline, including british airways, was able to get our family of four as part of the hundred that got on the concorde for that flight).
The cruising altitude of the concorde at mach ~2 is between 60 and 65k feet, basically double a normal airplane (wikipedia says 60k, but I distinctly remember the monochrome LCD in the plane that said we were traveling 1350 mph at 64k feet)
I'm curious, now, what my cosmic radiation dosage was at that altitude. Surely, given the nature of atmosphere and radiation, the dosage at twice the normal altitude is considerably more than twice what it is at 30k feet. I wonder what that did to my chances of getting a radiation induced cancer now ;)
As an aside, that happened well before 9/11, so I was actually able (/invited by the flight attendants) to go to the cockpit and talk to the pilots while were cruising along at mach 2. I remember asking the pilot what the actual takeoff speed was (he said about 175 mph, if I recall correctly. Given the glued-to-the-seat acceleration we experienced on take off, sounds about right), and all sorts of other nerdy questions about the technology.
I'm gonna pour one out for the pre 9/11 days when curious kids could visit the cockpit of an airplane and be a nerd with the pilots.
I'll pour another one out for the Concorde.
I still remember it pretty vividly (though memories can of course be deceiving ;), but we made it from heathrow to jfk in 3.5 hours. I believe, also, that with the time change, we landed about 15 minutes before we took off.
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I've now been living in NYC for ~15 years (moved here about 3 weeks before 9/11), and have watched the NYPD develop it's various anti-terrorism tactics. From the weird aluminum devices I've seen in penn station next to the armed-with-assault-rifles national guard folk on major travel days, to the stickers on the street food carts citing their affiliation with some NYPD anti-terrorism program, I've been concerned for years about the NYPD overstepping reasonable bounds on their behavior.
Where does this end? How do we encourage the police to actually be reasonable? I do have an acquaintance in the NYPD (we went to college together), but conversation on this topic is more or less not possible. The thin blue line is very much a thing, and it appears to be impenetrable for us 'civilians' (the general attitude I got from said acquaintance is "you wouldn't understand").
After reading caf's comment about Concorde's radiation detector, I came across this: "To protect passengers and crew from unnecessary radiation exposure, airworthiness authorities of Britain and France require that civilian aircraft, which fly above 50,000 ft, have a solar cosmic ray warning device. If the radiation level reachs 100 millirem/hr, the pilot is to descend to a lower altitude." - https://www.faa.gov/data_research/research/med_humanfacs/oam...
Guessing there aren't a whole lot of civilian planes affected by this rule :-D
Another benefit of the Concorde is that you were exposed to that radiation for a much shorter time than the passengers flying at 40k feet for hours longer.. I'd like to see the comparison but am too busy to do it myself tonight.
On it's face, this may seem completely harmless, but what about when you consider how the device is going to actually be used?
I imagine constant-scanning over a period of several hours would be on the order of several hundreds/thousands of bananas. Would that be banana-boarding?
Several thousands bananas a day add up to about the background radiation level. Most people won't be spending all day sitting next to this van, and even if, there are some other radiation sources one is exposed to daily that just dwarf the emissions from the scan-van, per this handy chart[0] that I'll soon get banned for constantly posting in this thread.
TL;DR: it's harmless, please focus on the actual problem - i.e. police taking nudes of you without your knowledge or consent.
I'm sorry, but if someone were being forced to eat thousands of bananas a day, people would be pretty outraged.
I'm all for keeping this about privacy, but don't dismiss the health stuff. Dentists still give you a lead bib to protect against x-rays (2doses worth according to XKCD), so yeah, don't dismiss it.
> I'm sorry, but if someone were being forced to eat thousands of bananas a day, people would be pretty outraged.
Yes, but not because radiation. There's a difference between scanning someone and force-feeding them.
X-rays are emitted by many processes, including playing with an office tape. If, say, relays in traffic lights emitted equivalent amounts of X-rays in the course of their normal operation (don't they? did anyone check?), nobody would be talking about it. The reason we're talking about vans is because police is taking nudes without consent; radiation is only used as an additional, powerful argument, because it sounds scary.
> I'm all for keeping this about privacy, but don't dismiss the health stuff. Dentists still give you a lead bib to protect against x-rays (2doses worth according to XKCD), so yeah, don't dismiss it.
I think those are 2 doses afer taking into account the shielding you get. I wouldn't expect it to be much higher without shielding though, but medical profession is both extremely sensitive about legal issues and not beyond doing weird things to cater for irrational fears of people. For instance, the reason you get "a MRI" and not NMR - for Nucler Magnetic Resonance, as it is called everywhere else in science - is because patients were afraid of the word "nuclear".
I think the reason we're talking about the vans (at least the reason I am) is because it's directed radiation, not just an electric field that extends symmetrically in all directions.
The dentist I went to (who was really great) explained that there was actually a pretty big difference in the radiation levels between hardware from 10 years ago and today. IDK when the reference date for that xkcd chart is. f
But either way, why should we let someone subject us to even slightly just a tad potentially harmful in a directed manner? I'm not cool with that.
> IDK when the reference date for that xkcd chart is.
From what I can tell it was last updated in 2011[0].
> But either way, why should we let someone subject us to even slightly just a tad potentially harmful in a directed manner? I'm not cool with that.
We're talking about so very slightly very much just a tad harmfulness that if we were to be consistent about it we'd have to take issue with every single thing in our lives. This is beyond "I'll stay at home, external world is dangerous" levels of harm. So why are we suddenly singling out radiation, and not say risk of getting driven over by scan-vans? Or risk of accidentally angering a cop and getting shot to death, as it happens in the US from time to time? In my opinion, we're privileging the radiation issue way, way too much.
So the FAQ of the company that sells sketchy (until recently) secret X-Ray vans to the NYPD asserts that they're completely safe. Have these dosage levels been independently tested?
Great. So what happens when the police get to love these things and there's 7500 of them in a city and you get scanned by 5 at once continuously wherever you go?
If somebody only takes a penny from my wallet, they still stole it without my consent. Even if x rays were 100% completely harmless, it still amounts to being searched without my consent.
"Dose to Cargo: Less than 0.1 microSievert (μSv) per scan (equivalent to 10 microRem (μrem)), at an average speed of 5 km/h (3 mph) at a scan distance of 1.5 m (5 ft). Should a stowaway accidentally be scanned, the effective dose is well below the ANSI specified limit for accidental exposure and is equivalent to flying two minutes at altitude."
[0]http://as-e.com/products-solutions/cargo-vehicle-inspection/...
Edit: Why the downvotes? Pretty objective information...