[Begin edu-metaphors] Imagine that you are on a small boat. There are a huge number of well-cared for sandcastles on a nearby beach, symbolizing living cells. In the boat, you have moderately heavy bowling balls (a metaphor for alpha particles), standard baseballs (symbolic beta particles), and a loaded rifle (mock gamma particles). The distance between the boat and the sandcastles on the beach represents human skin. To mimic an external source of radiation, wear a blindfold and earplugs to simulate the random action of nuclear reactions. When you fling alpha particles/bowling balls off the boat, you are extremely unlikely to hit a sandcastle, or even the beach, unless you are very lucky and very strong. If you throw the beta particle\baseball, you might hit the beach or even a sandcastle, but you are more likely to throw the ball in the wrong direction or not far enough. If you shoot the rifle, the gamma ray/bullet is more likely to hit a sandcastle because the distance is less important, but any blindfolded human randomly shooting a rifle on a rocking boat isn’t likely to hit any distant targets. This is a metaphor for external radiation exposure.
If you imagine that you are standing on the sandcastle beach with your implements of destruction, internal radiation exposure is symbolized. The bowling balls will likely demolish a sandcastle if they hit one, but they won’t roll far. Damage will be localized around you but severe. The baseballs are likely to hit many more sandcastles, but each hit will likely do less damage than the bowling balls. The rifle can damage many sandcastles, and since you are standing on the beach, you can aim it more or less parallel to the sand (to make up for a weakness in the metaphor–living cells are 3D and thus surround internal radiation sources, unlike a roughly two-dimensional array of sandcastles on a beach). The blindfold does not matter much anymore–only the supply of bowling balls, baseballs, and bullets, as well as sandcastle repair personnel (who can also be damaged). Some of the sandcastles may quickly come to resemble the Tower of Barad-dûr… and damaged living cells can cer tainly be much more effective spreading evil than sandcastles could ever be.
The take-home lesson: internal radiation exposure is far far far more damaging than external radiation exposure, and do not trust those who pretend otherwise.
Obviously, it is important to keep radiation doses to a minimum and internal radio-dosing should be scrupulously avoided, especially by children. However, the world is becoming increasingly dirty and radioactive, so some exposure to man-made toxins and radioactive substances is unavoidable. You can avoid the heaviest contamination by eating low on the food chain–eat plants, rather than the animals that eat plants. Each step away from primary producers is a potential step towards bio-magification–for example, eagles that eat fish that eat plants were found to have damaging levels of DDT metabolites in their bodies, so much so that their eggs did not hatch. This could have destroyed this species (and others) if DDT was still in use as much as it was previously. You are an omnivore, able to survive on a wide range of foods, and selecting plant foods is probably safest. Examples of fraudulently-labeled plant foods (like rice bearing a label that conceals its Fuku-origin) complicate this process, but no6ody puts labels upon meat and fish and dairy products that state what the animals ate.
As long as you are reading this… let’s do a thought experiment. I’ll be an evil overlord, and you can be my prisoner. Here’s your dinner, which consists of four delicious-looking cookies. Since I (half-)baked them in this thought experiment, they have magical properties.
The first cookie emits alpha particles. The others emit solely beta particles, or just gamma rays, or only neutrons (all possible only in thought experiments). All of these cookies emit the same total energy in their particular way, and you must choose one cookie to eat, one cookie to put in your pocket, one cookie to hold in your hand, and one cookie to toss to the imaginary but nasty orc turnkey–what should you do?
Alpha particles are big and heavy, as particles go. They also have a positive charge, which means they attract/are attracted to all nearby electrons that they encounter as they travel. Because of this, alphas do not travel far, and at point blank range, an alpha particle can do great damage. This cookie is a bad one to eat because, once inside you, some of your DNA would be in point blank range. However, the fabric of your pocket and your skin should be protection enough.
Beta particles are basically electrons in a straight-line hurry, and these also interact with other electrons. They are fast enough to penetrate skin a little bit, but they are only about 1/8000 the mass of an alpha particle. If they hit an atom directly, the atom doesn’t move very much and can stay in position, even if it does create an unstable chemical situation. Plus, the event is effectively over for the beta particle… unless it hits a really massive atom. Then the energy of this collision can be expressed as a gamma ray. (Throw the gamma ray cookie to the orc immediately. Even in a thought experiment, don’t delay!) The beta-emitting cookie can be held in your hand (unless your hand is made out of massive metal atoms}.
The neutron cookie is probably the best one to eat. Free neutrons have a half-life of about fifteen minutes and do not have an electric charge, so other atoms ignore them. Even if a neutron impacts an atomic nucleus directly and doesn’t bounce off, the lightweight atoms humans are made of probably won’t fission (like uranium does with the addition of a neutron), and may not even be radioactive. Boron is a commonly used neutron absorber, as the isotopes it changes into aren’t nasty and it captures stray neutrons better than average. If you agree with me and decide this cookie is the safest one to eat, perhaps you’d like a boric acid topping on the cookie? As an evil overlord, it is my duty to try to sell you Roach-Death Bio-cide (which contains boric acid), even though there’s pure boric acid in my imaginary lab. Should you? Boric acid is so cheap, safe, and effective at roach killing that adding adulterants to it might raise the costs of producing Roach-Death Bio-cide, even if produced and sold by my money-whore minions.
This website is brought to you primarily by WordPress, who probably isn’t making any money off of it. Therefore, I’m not going to complain that I can’t upload text files, insert page breaks, or control the ads here. The following PDF file is more my style, such as it is.