While on the one hand it is certainly true that if say the word “nuclear” or “radiation” to some people and they go running around in a complete tizzy, the media in particular. The recent discovery of radioactive iodine (which may have come from Fukushima) in Scotland is an excellent example of this Chicken Little reaction to the issue.
However, it’s also important to acknowledge that radiation is potentially quite dangerous to human health. The nuclear industry often seriously downplay the risks, by using inappropriate comparisons, such as comparing them to chest x-rays or eating bananas (which contains small quantities potassium a small portion of which will be radioactive isotopes of potassium). All such comparisons demonstrate is the lack of knowledge evident in most nuclear cheerleaders as to the very basic principles of radiation and its effects on health….which leads one to question whether such individuals are suitably qualified to be giving us advice on nuclear energy.
The human body can absorb a certain level of radiation with minimum harm, as we are regularly exposed to radiation from natural sources, radon gas, small quantities of radioactive materials which wind up in our foods. We’ve evolved a limited level of resistance to radiation effects…but again its the limited part of this has to be emphasised. Going over this limited resistance, even by a small amount can potentially have very serious consequences.
As the links above show there is no set established theory to determine the damaging effects radiation has on the human body, but we can use what we know about radiation to categorise the risk at least in some way. In simple terms, there are four important factors in determining the relevant danger related to radiation exposure, the type of radiation, the intensity, the duration of said exposure, and the frequency at which it occurs. On the first point, there are many different types of radiation, all with very different characteristics and effects. Alpha particles for example tend to be less of a worry (alpha particles are generally blocked by the skin) unless the substance emitting them gets inside the body (by inhalation or eating contaminated food) at which point exposure could potentially get quite serious (if its an intense source of the stuff).
At the other end of the scale, x-rays are highly penetrating, capable of going straight through the body almost without stopping. Now, there is little to fear from a medical x-ray (or MRI scan) as you are only exposed in this case to the radiation for a few seconds (i.e the intensity is high but the duration is extremely short) and one is unlikely to be exposed to x-rays an anything like a regular basis (the frequency is low, this is also why you’re doctor or dentists ducks behind a shield when he administers the x-rays). Of course if you were to be exposed to longer duration pulses on a more regular basis, even if those pulses were less intensive, the biological effects of this would be far more severe.
While you might get exposed to small quantities of radon, for example over your life, the intensity is low, the durations should be low as should the frequency of exposures (if you ventilate you’re house well that is). So while the overall exposure levels might look high when you add it up over a lifetime, the actual effects are generally low (for most people) as you’re getting it in lots of small doses spread over a long period of time now and again (giving the body time to heal from the previous exposure). This tends to be the pattern with most natural sources of radiation.
The problem with the artificial radiation sources is that they often combine the above factors in a way the body can’t cope with for very long. The intensity of the radiation from the sources produced by nuclear energy/weapons usage is often much higher, the duration can potentially be longer (depending on the nature of the fallout) especially if radioactive substances get into the body. While the body has the means to process and reject naturally occurring radioactive isotopes, there’s a limit to what it can cope with (remember its busy enough coping with those naturally occurring sources anyway!). The body is also not very good at dealing with artificial sources, such as polonium, plutonium or caesium isotopes. These can thus linger in the body for prolonged periods (upping our duration and frequency of exposure to dangerous levels) and worse still some radioactive isotopes can accumulate in the very parts of the body where they can do the most damage (such as the Thyroid gland).
Thus describing radiation exposure in terms of “Y number of chest x-rays” isn’t accurate, unless they are proposing you stood in front of the machine and took the x-rays one after the other at full intensity (which would likely kill you or give you cancer!). They can also deliberately skew the numbers, for example spreading the effects of say TMI over the entire population of the US East Coast, when the vast bulk of the fallout of this accident (which wasn’t very large anyway) affected a relatively small number of plant workers as well as a few residents down wind of the reactor.
Again, yes, many people’s reaction to radiation is often somewhat irrational and out of proportion to the danger (as compared to similar dangers which we routinely ignore, such as car accidents) but it’s also entirely human. Put yourself in the shoes of a parent in Tokyo right now, there maybe a problem with the tap water due to Fukushima. Do you (A) give it to you’re kid anyway as you trust the government officials when they tell you its alright or (B) go buy some bottled water and give the wee-ins that instead. I think you could count on one hand those who’d choose (A). Also, the reason for people’s irrational response to radiation is at least in part driven by the nuclear industry habit of lying to people during the cold war about the negative effects of radiation, so there is an element of the boy who cried wolf at play here.
So when you hear nuclear cheerleaders talking about how a particular radioactive substance isn’t as toxic as say, a similar quantity of Cyanide (at least initially anyway, it would take awhile for the radiation to do the damage), they’re ignoring one crucial fact – no sane individual would ever voluntarily consume any quantity of either. Unless the nuclear industry can produce a signed letter of consent from everyone within a 100km radius of any nuclear facility (or strictly speaking the entire continent given how far radioactive fallout can travel after an accident) then any exposure of the public to radiation constitutes involuntary exposure to risk, which brings about all sorts of legal and democratic implications.
So while yes, it’s important to be rational about radiation and put its risk in the proper context, to simply go ay fiddly-dee! Its only a little old radiation, sure it won’t do ya any harm! Don’t you worry you’re pretty little unwashed working class heads about anything, we went to Eton you know! is neither accurate nor entirely sane.