Radiation too low to worry about? What If I breathe in that one particle?

We keep hearing about how any radiation coming from Japan is at too low a level to worry about. But this radiation is not just some nebulous cloud, as far as I can tell it is made up of particles of radioactive material. I also have been given to understand that if you breathe in a small particle of radioactive material, it will lodge in your lung and after some interval will give you teh cancer.

So, why are we being told that “radiation levels are so low that it can’t hurt you”, as if it is like an x-ray where you get some small dose, that you are only subjected to for the time of exposure, but in fact the mechanism that by which the radiation travels thousands of miles across the ocean is on particulate matter, and if you are the unlucky sap that breathes that one in, and it lodges in the mucus in your lungs, :eek: you are going to be done for.

Or am I misunderstanding the process?

The main point that you are missing is that you are exposed to low dosage radiation all the time. Everything in he world is radioactive. Your own body is radioactive. We evolved to deal with this constant exposure to low level radiation. It’s harmless because we can repair any damage it causes.

So a single radioactive nucleus from Japan isn’t going to cause lung cancer, or at least it’s no more likely than the thousands of identical radioactive particles that you have been breathing in every day since you were born. Even if it did lodge in your lung and decay, your body would automatically repair the damage.

So for all intents and purposes “radiation levels are so low that it can’t hurt you”. It isn’t any higher than what you have been exposed to your whole life, How can it hurt you?

There’s no firm line on exactly when radiation levels become too high. We know that we can deal with “background” levels just fine, and we know that we can deal with levels orders of magnitude higher than background just fine, particularly in the short term. At some point obviously it becomes dangerous even in the short term, but what happens is that the incidences of lifetime cancer rise very gradually in populations, not in individuals.

IIRC the legal “safe levels” are essentially based on the point where an additional one person in 100, 000 will develop a cancer at some point in their lives if they are exposed for a prolonged period. So even if you were exposed to the levels found in the air in Japan for a month or so, it’s not like it “will lodge in your lung and after some interval will give you teh cancer”. More realistically it increases the odds of you getting cancer by about one in a million. Sucks if you are the one who dies, but to put that in perspective, it’s about the same as the risk from smoking a single cigarette or eating 5 grams of pepper (about an average annual dose).

My understanding is that the body’s reaction to extremely small amounts of radioactivity is still a matter of debate, with some arguing that the body is able to tolerate a low amount without suffering damage. If that’s true then the particle doesn’t matter.

Putting that argument aside and accepting the “linear no-threshold” model which argues that any exposure to radiation brings with it a chance of cancer, chances are that you’ll still be fine if that one particle is all you’ve inhaled. Breathing in that radioactive particle increases your chances of cancer by some non-zero amount but doesn’t make it a certainty. Internal exposure is not good because it’s constant (until the particle’s radioactivity decays) and because it has directly access to the internal organs. But the radiation you’d be exposed to by that single particle is nothing compared to the radiation that you’ll be exposed to from other sources in your day to day life. If people are concerned by a 1 billionth increase in their chance of cancer, they have much bigger problems.

Just about everything is slightly radioactive. Including your body. In particular, a small but significant fraction of all carbon and potassium is composed of radioactive isotopes. And there are plenty of other slightly radioactive elements wherever you go, including trace amounts of things like uranium. All of this adds up to the background radiation, and there’s no way to avoid it.

But that’s ok. Your body can handle small quantities of radiation. When a radioactive particle interacts with a bit of biological matter, it ionises it and thus causes some random unwanted chemical reaction. Much of the time that doesn’t matter, but occasionally a radioactive particle will hit your DNA and cause some sort of damage. Again, most of the time that isn’t a problem, because your cells have all sorts of repair mechanisms which can identify and fix the errors. (DNA damage is primarily caused by metabolic by-products, and background radiation is a relatively insignificant cause anyways.) But occasionally the repair mechanisms don’t work, so you end up with a mutation in the DNA. And most mutations are harmless. But some small fraction of mutations will cause a cell to divide out of control. Again your body has defense mechanisms, particularly a cellular “self destruct” which is triggered when cells are heavily damaged or mutated, or otherwise out of control. But sometimes that mechanism fails, and the mutated cell starts growing a tumor. The tumor is likely benign, but several more mutations could make it malignant. And there are other defense too – your immune system kills off lots of abnormal cells before they grow into a tumor.

As a sort of WAG of the proportions we’re talking about, say that 1 in 1000 radioactive particles within the body cause DNA damage. Of those, 1 in 1000 aren’t correctly repaired. Of those, 1 in 1,000,000 cause mutations that contribute to cancer. And 1 in 1000 become an actual tumor, of which 1 in 1000 might actually be cancerous. (These numbers are pulled off the top of my head, but if anything I’m probably grossly overestimating the risk at each step).

So there’s a low-level of background radiation that really isn’t harmful. There are lots of places with much higher background radiation; one of the common examples is Denver (or any high-altitude city) which has twice the background radiation compared to a city at sea level. But there’s no measurable cancer risk at even double or higher levels of background radiation (and with a population the size of Denver, epidemiologists can easily measure small differences in cancer rates).

One thing to keep in mind is that scientists can measure ridiculously minute quantities of radiation – many orders of magnitude smaller than the quantities of radiation that have clear health risks.

Here’s a nice chart comparing the magnitude levels of radiation from various sources:

Helps put some of this in perspective.

You should be more concerned about Xray scans and MRI scans of your body.

I think the OP might also have been confused by the different ways that the word “particle” may be used.

For example, if news reports say “ash particles” they don’t mean individual atoms or molecules.
Theoretically, if you had a “particle” (tiny piece) of ash which was rapidly emitting alpha-particles (helium nuclei), and you inhaled it, sure, it could be a significant health risk.

But in this situation there is nothing that is that strongly-emitting or is in large enough concentrations to be a significant risk.
Not outside of the direct area anyway.

Bah… I mean CT scans and Xray scans

This isn’t really correct. A single particle of plutonium, which is a ferocious emitter of fast neutrons and alpha particles, is different from other, lower-energy emitters which are much more common in nature. It is the potential for such energetic (but man-made and rare) particles getting into lungs that is the cause of all those warnings about only a tiny amount of plutonium being capable of killing a huge number of people. The radiation you encounter daily from radioactive granite and radiation you pick up on airline flights are whole-body effects and low-dose. It’s different to have a steady source of ionizing radiation lodged in a single spot in your lungs.
It’s easy to get hysterical about this, but the point is that the odds are pretty low about something like this happening – there hasn’t been, to my knowledge, a mass release of plutonium particles into the atmosphere from events in Japan. Most radioactive materials don’t cause this sort of threat.
And the “What if you’re that one?” issue is one of those things that shows up in any discussion of any sort of risk. Read Paulos’ book Innumeracy for a discussion of it. Low probability of injury doesn’t mean that everybody, everywhere always has the same low probability of injury that persists no matter what. If you happen to be in the wrong place at the wrong time, the meteorite falls on you.

A single plutonium nucleus can only decay once. Even if the decay products are themselves radioactive, you are still only talking about 3 or 4 radioactive decay products at most. It’s not a" ferocious emitter". You’re talking about less than 6 particles.

A single dust speck contains a lot more than a single atom.

That said, I’m not alarmist – just noting that there is a potential hazard. But , as websites point out, there hasn’t been a single death attributed to plutonium poisoning.*

from this site:http://www.3rd1000.com/elements/Plutonium.htm

*although there have been deaths due to high radiation flux from near-critical assemblies. But that’s another story.

This tableis also useful (not so detailed but maybe clearer). The UK Health Protection Agency site (where this comes from) has a lot of good stuff about the effects of radiation.


Did you even bother to *read *the post that you quoted?

Of course – duid you even read my comments? I’ve said that the risk overall of danger to most folks from exposure is overblown, but I dispute the claims that danger from irradition is itself negligible. One needs a proper sense of balance, and that includes not duismissing the situation of exposure. It has been well-established that deposition of plutonium dioxide in lungs not only can, but will certainly cause cancer at sufficiently high levels, and those levels are disturbingly low. But we should gain confidence from the fact that we haven’t seen any such cancers in humans, despite exposures yo plutonium.
The original work on plutonium dust in lungs goes back to Donald Geesaman, whose work continues to be cited, although people rarely seem to mention that it goes back to 1968-70:



The whole thing about radiation poisoning is this, to my layperson’s understanding: it is harmful because it introduces enough errors into the current structure of your DNA, and that error gets magnified every time your DNA reproduces, and that’s why you die. One little particle of radioactive substance is not going to do any noticeable kind of damage on any noticeable kind of scale.

IANANuclear Scientist.

The use of the word “particle” is confusing here. Everyone needs to be very precise about what they’re talking about - a dust particle is a very different thing from an atom slash particle.

Yes, and they are factually incorrect and ignorant. A single plutonium nucleus can not be describes as “a ferocious emitter” of anything.

Nonetheless you described it that way.

No, that’s not what he said. CalMeacham wasn’t being precise, but he specifically did not say that a single plutonium nucleus would continuously emit radiation. He specifically said “particle”, and presumably was referring to micron-sized bits of plutonium.

Again, everyone here (including me) is being sloppy with the word particle. It can refer to a single nucleus, a single decay particle, or a dust-sized lump of something radioactive. A single nucleus or decay particle isn’t something to worry about. A single dust-sized lump of something like plutonium is absolutely something to worry about, because it does constantly emit large quantites of decay particles (but those are heavy and won’t spread far, particularly not across an ocean).

Dude, the section of my post he quoted was specifically and solely referring to a single nucleus. He responded to that specific quote by saying that “A single particle of plutonium, which is a ferocious emitter of fast neutrons and alpha particles”

I was only ever talking about a single nucleus. When I asked him if he was sure and had read the post that he quoted, he assured me he had and so he was also referring to only a single nucleus of plutonium.

In short he specifically did say that a single plutonium nucleus would continuously emit radiation. That claim is bullshit. When we are discussing a single nucleus of plutonium it is nonsense to describe it as " a ferocious emitter" of anything.