I wore a dosimeter in my 20's on a nuclear submarine and received some radiation exposure working on the reactor, but the Navy explained to me that it was balanced out because I was underwater and not receiving radiation exposure from the sun. 40 years later, and still cancer free, knock on wood.
In a related note, I know someone who keeps bees and harvests honey. I recently visited the spot way out in the mountains where he does this and I asked why he chose a spot so far out. He explained that to get the organic label, the honey must contain no pesticides and if you keep bees around the property of other people they will ingest pesticides from flowers on those property, since pesticides are so commonly used.
I would take anything the US mil claimed with a large grain of sodium chloride. There has been an extensive history of them and their affiliated contractors lying to personnel and civilians: agent orange, ddt, pcbs, gulf war syndrome/pesticides/sarin/mustard gas, radium, and so on.
You have to know your actual average, peak, and total dosages to be able to compare it with everyday civie life.
Regarding pesticides: the US has a major problem with gross under-regulation of chemicals in nearly every context. This stems from TSCA 1964 grandfathering-in 10k's of chemicals without evidence of safety, a guiding principle of "assume safe until proven otherwise because profits", and ignoring safety data and conservative exposure standards set in the rest of the industrialized world.
Edit: My father worked on the flight line of a US military base in Vietnam. He was exposed to agent orange, unburnt napalm, and jet fuel many times. He suffered from the rare adult-onset type I diabetes for most of his life and experienced several kinds of cancers.
> Regarding pesticides: the US has a major problem with gross under-regulation of chemicals in nearly every context.
There’s other weird corners to pesticides. I found myself helping somebody with a .gov contract that required computing equipment to be sanitized and cleaned with a manufacturer recommended method that is a listed pesticide.
Problem: most manufacturers recommend isopropyl alcohol for this purpose, and it’s one of those grandfathered in chemicals, and isn’t “listed” as a pesticide.
Solution: We found a company that made cleaning supplies for industrial processes, and they had a specific formulation of isopropyl alcohol wipes listed as a pesticide. (For a price nearly 20x more than normal products)
It’s a silly story but illustrates how nuts this stuff is. Just with something silly like sanitizing wipes, people are using proprietary “quats” with serious potential health impacts where something as simple as alcohol could easily do the job.
Honestly, I don’t know, but the MSDS sheets all call for users of wipes that use quats to wear gloves or wash hands immediately.
Also, they are not to be used on food surfaces.
When I was stuck researching this topic, I spoke to a few academics… their recommendations were always cautious around quat products, and usually peroxide was the “wipe of choice” if it was ok for the use case. (Ie you cannot use peroxide on computers, keyboards, etc.)
Not smart. It says right on the bottle that it's not made for skin contact. Check the ingredients (if they're all listed) and see if there's safety data for them all.
> the honey must contain no pesticides and if you keep bees around the property of other people they will ingest pesticides from flowers on those property, since pesticides are so commonly used.
I think this is a very common misunderstanding. The bees are allowed to forage on organically-cultivated crops, and farmers can use a whole range of 'natural' but also 'certified' synthetic pesticides on them.
Producers of organic food don't seem to mind too much that people assume organic food growing doesn't involve the use of pesticides.
The synthetics that are allowed in certified organic farming are pretty limited (when it comes to pesticide use) and pretty innocuous. Anyone can read about them specifically here: https://www.ecfr.gov/current/title-7/part-205/subpart-g
Which is a funny group of people. Their rules sound kooky, but their results aren't at all what I would expect from kooks. The best strawberry jam I can get here comes from from a farm where they (I learned when I asked about why it's so good) turns their compost according to the phases of the moon. Weird. The same farm was also raided by the police. 130 police officers searched the place at dawn one morning, and apparently the only reason for suspicion was that those weirdos had money to spare for a succession of new greenhouses even in years when all their conventional neighbours had no money to spare for anything.
>turns their compost according to the phases of the moon. Weird.
It might not be so weird.
While not as noticeable as ocean tides, aquifer tides[1] cause the soil to "breathe" twice per day. Spring tide vs. neap tide (which is a function of Moon phase) would change the magnitude and diurnal timing of this "breathing" pattern, which could have a significant effect on soil biology.
As you learn more about Earth Science, it's interesting to discover that (some of) these "crazy" ideas start to look not-so-crazy.
One of my favorite examples: how do you stop vermin in your garden? Make a small pile of rocks off in the corner, of course! Sounds like superstitious gobbledygook, right? And it is, right up until the moment you realize that all you really did was make a happy undisturbed snake habitat.
All that suggests that turning the compost once per moon cycle makes sense. I've no problem with that. But turning the compost at specific points in the cycle… and yet, these are the farmers with the best produce.
Aquifer tides sound like a fascinating concept that didn't occur to me before, but tides require a lot of fast lateral mass transfer thats usually not possible in most aquifers.
In this case, the effect is largely due to the overburden itself expanding and contracting with varying tidal attraction. These mechanisms force atmospheric gases into and out of the soil, like a piston.
It sounds like doing that might encourage the snakes to reproduce and you’ll just end up with more snakes. Even if you’re fine building a few new habitats every year, at a certain point would you encounter some sort of snake breeding law/regulation?
The Oxford Companion to Wine has a long article about it. It "remained little known in the wine world until an increasing number of top-quality producers" adopted it, many of whom learned about it from someone who "makes no claim to understanding how biodynamics works". I, uh, find it difficult to believe … but these actually are top-quality producers.
The Companion also notes that many of them do it but prefer discretion. I can see why.
Maybe what matters isn't exactly when they turn their compost, but that they turn it at all. Like, caring about the details even in a "whacky" way (according to most non-biodynamicists) is a lot better than not caring about the details at all -- and maybe to people who aren't into biodynamics, turning the compost is a weird detail that only "whacky" people would care about.
Maybe the phase of the moon is important. Maybe it's not, but if you're bothered enough to do things according to the phase of the moon you're probably paying attention to other stuff that matters.
"In this groundbreaking study of organic farming, Julie Guthman challenges accepted wisdom about organic food and agriculture in the Golden State. Many continue to believe that small-scale organic farming is the answer to our environmental and health problems, but Guthman refutes popular portrayals that pit “small organic” against “big organic” and offers an alternative analysis that underscores the limits of an organic label as a pathway to transforming agriculture.
This second edition includes a thorough investigation of the federal organic program, a discussion of how the certification arena has continued to grow and change since its implementation, and an up-to-date guide to the structure of the organic farming sector. Agrarian Dreams delivers an indispensable examination of organic farming in California and will appeal to readers in a variety of areas, including food studies, agriculture, environmental studies, anthropology, sociology, geography, and history."
I just confirmed for those so inclined, you can quickly download a PDF of the book for free on Library Genesis.
Oregon Tilth was a certification for sustainable farming when I was growing up in PNW, though I can’t attest it’s “strictly” enough or not on the topic.
Biodynamic is an unregulated label that is often meant to imply this, but of course offers zero guarantees. Usually it comes with a “tour the farm” level of visibility into processes, which is a nice upside. Often coincides with “dry-farmed” and/or “trap cropping” practices, two labels that indicate material benefits to crop quality independent of the biodynamic label.
At least save whatever documentation you have. I have some letter from the military about various nasty organic solvents they had us use squirreled away somewhere.
It might have been because of the insecticides really. I have a donation subscription to an organisation which keeps bees in the dead center of a 1.7mln city.
Turns out the bees thrive in this environment, because they're still better off there than in the countryside.
You’re breathing the same recycled air for weeks at a time. The radiation is continuously creating isotopes in the gases in that air. That means a continuously increasing radiation exposure the longer you stay underwater.
On the surface any radioactive gases get dispersed in the atmosphere.
No, this is not the case. We often surfaced at night to recirculate with fresh air. In fact, this is done so often that the first thing we do is turn the clocks 12 hour forward so our day shift when everyone was working occurred at night. We need to surface to recharge the lead acid battery off the diesel engine as well, which was done to make sure that kept working well. I did this when newly qualified as an electric plant operator and it was difficult for me to do correctly.
> On the surface any radioactive gases get dispersed in the atmosphere.
The relevant radiation exposure when you're outdoors is not from radioactive gases in the air, it's from radiation hitting atoms in your body. (The relevant radiation to compare with what a nuclear reactor produces is actually not from the Sun, it's from cosmic rays.)
Cosmic rays come from the sun, as well as other sources, but mostly from the sun. Cosmic rays are highly charged particles, not a particular type or class of radiation, and are energetic enough to produce ionizing cascades in the atmosphere.
> Cosmic rays are highly charged particles, not a particular type or class of radiation
Highly charged particles are a type of radiation, at least as that term is used in the context of this discussion. (Yes, in some physics contexts "radiation" only refers to massless particles like photons, but in such a context no "radiation" to speak of comes from nuclear reactors either, since the potentially hazardous radiation from nuclear reactors is neutrons and some alphas and betas.)
> The radiation is continuously creating isotopes in the gases in that air.
What radiation? Note that he didn't say he received radiation exposure throughout the submarine, only "working on the reactor". That's an isolated space that doesn't continuously exchange air with the rest of the submarine and has an extra layer of shielding between it and the rest of the submarine (in addition to the shielding around the reactor itself that separates that from the space where people working on the reactor go--nobody ever goes inside the reactor itself).
Reactors on Navy vessels, since at least the 70s, are very safe. They are closed systems and are completely sealed in compartments surrounded by feet of shielding. While some negligible amount of radiation does get through, it's half life is very short. Radioactive isotopes don't escape, nor do they get created by proximity to a radiation source and start floating around the crew compartment. In addition, each crew member carries a dosimeter which tracks their exposure. As others pointed out, walking around outside exposes us to more radiation (from the sun, earth, ceramic tiles...) than spending months next to to one of these reactors.
> the Navy explained to me that it was balanced out because I was underwater and not receiving radiation exposure from the sun
With the greatest respect to the Navy, I smell more fish than in the seas that submarine travelled through.
My non-scientific understanding is that sun exposure is UV radiation exposure which causes skin melanoma. Meanwhile with nuclear reactors, UV is not the problem and the problem with exposure goes deeper than skin melanoma.
My feeling is you received a standardised "policy explanation" rather than an entirely scientific one. Happy to be proven wrong with links to scientific fact though !
Cosmic background radiation is a thing and water is really good at blocking it, so it's not complete bullshit. Of course, without knowing what dose the GP received, it's impossible to say whether it's a comparable dose to what they would have received on the surface - but it's plausible.
There is some good information about the relative exposure levels to cosmic radiation that one can expect to encounter on this site. They have been doing balloon launches and measuring in-flight levels for quite a while now.
Indeed. But isn't it really only "a thing" for airline pilots, cabin crew and a few unfortunate people at ground level who happen to live/work high-altitude on mountains or somewhere lower down with the wrong kind of rocks ?
Depends how you look at it. Cosmic radiation might not be extremely high level on the sea level, but it is a thing. So the total radiation dosis in a nuclear submarine might equal or even be less than on the surface.
Fun story: as part of my physics education we did an experiment on the cosmic radiation with a "radiation" telescope. That were 2 Geiger counters with a logic that only registered events which basically occured in both counters at the same time. That made the observation reasonably detectable and you could "see" the sun with this. This experiment was conducted indoors, just on the top floor of the building. We had about 1 event/second, our bodies would be getting a similar dosis all the time.
No, it is a gradient, with more exposure happening higher up. Radiation damage is considered “additive” over your lifetime. So if you are somewhere with less background radiation, you can receive more radiation from other sources and still be considered within “safe” limits. This is the basis for the policy mentioned.
I think they just poorly explained that his exposure in the sub was lower than background radiation levels on the sea surface. You get more rads living in Colorado for a year than anyone would get working in a nuclear power plant for a year at sea level.
Humans receive about 3-4 mSv per year of background radiation on average. Some of this is from radioactive decay, and some from cosmic radiation. Being underwater much of the year might shave 1-2 mSv off this.
Civilian radiation workers can receive, by regulation, doses up to 50 mSv per year. Typical reactor workers in the civilian energy sector get a couple mSv per year of dose. It is plausible that he was close to breakeven.
100mSv/year is the lowest dose that has shown a clear link to increased cancer risk.
The dose-dependent risk of cancer is in textbooks as an example of linearity. While it is hard to shown for low values of exposure because any measurements/estimates would drown in noise and errors, there is little doubt that the relation shown for higher values is just as valid at the lower end. That also conforms with the stochastic model of how radiation causes cancers and the mutagenic effects of low-dose radiation seen in vitro.
We're not absolutely confident that there's not some threshold dose. LNT is a decent conservative assumption for calculating the harms from low doses and reasonable to use for regulatory purposes.
Even so, radiation hormesis has been noted in lab models, etc (slight benefits from low doses).
We accept occupational risks all the time. Here, the threshold for radiation workers allows a dose half of what has been ever linked to any amount of cancer.
The overall average, across all industries, fatal work injury risk is something like 35 per 1,000,000 worker-years. Compare to this, where the risk to radiation workers from radiation, if they receive the highest allowed dose (and basically no one does) can be confidently bounded to be well under 1 per 1,000,000 worker-years. (And, if it should ever happen, is likely to be far in the future and cost less life expectancy as a result).
Why? 1 Sv (over a year) equates to a 5.5% increase chance of fatal cancer within a lifetime. Assuming the dosage is linear (it isn't but we use a Linear _no threshold_ model because it over estimates risk) 100mSv is a 0.55% increase in risk. So 50mSv is a 0.055% increase risk (note the parent is slightly wrong. Most countries and workers have a 20mSv maximum).
You're getting caught up in _detectable_ but not thinking enough about the actual level of risk. The danger/risk from 100mSv is far less of a risk than very common activities we do. Remember that that fatal cancer risk is over a lifetime (so let's say 40 years, or 0.01%/year if you receive that dose once). Smoking a cigarette a day (singular, not a pack) is a 30+% chance increase in stroke and heart disease. I'd argue that this is far more dangerous but something we don't worry about as much.
"The NRC requires its licensees to limit occupational exposure to 5,000 mrem (50 mSv) per year. Occupational dose does not include the dose received from natural background sources, doses received as a medical patient or participant in medical research programs, or "second-hand doses" received through exposure to individuals treated with radioactive materials."
I'm not sure what you're trying to say here. NRC is a US government. I said _most countries_ which in fact includes countries other than America. The EU standard is 20mSv. You'll also notice that this NRC listing specifies which workers. For DOE 50 mSv is regulatory limit and 20mSv is administrative control level. Of course, all this also changes based on occupation. I mean astronauts are allowed higher levels and pilots lower. But most countries and (radiation) workers have a 20mSv limit.
> I'm not sure what you're trying to say here. NRC is a US government.
I thought it was perhaps appropriate, if we're quantifying US Navy occupational exposure to a US citizen, to compare to US civilian reactor exposure limits. It doesn't seem appropriate to call me "wrong" in this context.
> For DOE 50 mSv is regulatory limit and 20mSv is administrative control level.
Sure: one needs controls well short of the regulatory limit to keep pretty much everyone short of the limit. Most nuclear medicine workers and reactor workers are well under 2mSv/year in the US. A few outliers end up with lifetime doses of a few hundred mSv.
P.S. Something went wrong here:
> 100mSv is a 0.55% increase in risk. So 50mSv is a 0.055% increase risk
In that you halved the dosage but divided the risk by 10, when saying you were evaluating it under LNT.
There are any number of substances where there’s little doubt that they can cause cancer even at minuscule doses, just at similarly low rates. Get enough data and you will find that a single whiff of tobacco smoke (or any other smoke) can cause cancer. The “lowest dose linked to cancer” is the result of our ability to measure such effects, not anything intrinsic to the harm these substances do.
That’s specific for cancer. For other forms of toxicity, the concept of “maximum safe dosage” does make sense when the dose/effect relationship is not linear. Pharmaceuticals, for example, can be entirely benign at small dosages yet lethal if you overdose.
But we can still set a significance threshold. Your point applies equally to radiation exposure flying on an airplane but we don't worry about the cancer odds from a single flight since it's lower than the (already miniscule) odds of crashing.
Would you say more? What that suggests to me is the authority responsible for setting the max allowed said “Well let’s keep it below the threshold linked to cancer, reduce it by half for safety factor, and call it a day”. IE they chose one of the simplest possible approaches- doesn’t seem surprising, but I am probably missing your point.
You're probably right. I thought the same thing, but since I didn't care I didn't pursue it. I would have cared if the scuttlebutt was that people were getting sick and dying, but that was not the case. Sub sailors were not dying in an detectable numbers.
A large chunk of that average dose, 4 mSv, is from radon, where the dose varies a lot depending on where you live, and if you live in such a radon-prone location, whether you have sufficient ventilation in your house.
Yes, you're correct. The page I linked to has this to say:
"For example, the health risk caused by radon is estimated on the basis of epidemiologic examinations, not the effective dose. Every year, an average of 280 Finns die from lung cancer caused by radon. Of these cases, 240 deaths are induced by smoking in addition to radon."
So they're not actually measuring an average 4 mSv/y dose from radon, but rather going the other way, that is that 280 yearly deaths from radon would be consistent with an average dose of 4 mSv/y (assuming LNT, presumably).
The math sounds nonsensical. The risk adjusted exposure from a reactor should definitely be higher as you would be closer to the threshold of DNA bond breaking. Being stabbed once a year isn't necessary better than getting hundred paper cuts. Any actuaries here care to comment?
There are mountains of literature and regulations on this and the math just kind of works that way (up to some limit, beyond which acute radiation effects will begin to dominate)
There is now some thought that very low doses of ionizing radiation are better than no radiation at all (so called 'radiation hormesis'), but I don't believe that has been adopted as part of any specific standard.
FWIW an individual person may be experiencing up to a trillion DNA mutations per day from both external and internal mechanisms of action. We just have a bunch of systems built in to prevent them from getting out of control (most of the time).
> The risk adjusted exposure from a reactor should definitely be higher as you would be closer to the threshold of DNA bond breaking.
How are you so certain? You don't know the specifics of the situation. If he worked underwater for a year and spent half a day working on a reactor in protective gear it could easily even out.
He is not saying the overall exposure may not be same (it could be) he is saying risk of cancer or other bad side effects may not be equal in both scenarios.
In a related note, I know someone who keeps bees and harvests honey. I recently visited the spot way out in the mountains where he does this and I asked why he chose a spot so far out. He explained that to get the organic label, the honey must contain no pesticides and if you keep bees around the property of other people they will ingest pesticides from flowers on those property, since pesticides are so commonly used.