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What is radiation?
Radiation is energy in transit in the form of high speed particles and electromagnetic waves.
So.. what do you mean, high speed particles and electromagnetic waves?
Well, the high speed particles are parts of atoms that have been given extra energy, so that they are traveling away from where they were, giving them a chance to interact with things, like shielding and people. The particles are pretty much one of three types:
Electromagnetic (EM) waves are the fancy name for energy that we encounter every day. They make visible light, radio and television waves, ultra violet (UV) light, microwaves and the more energetic gamma and X rays. One of the main things about EM waves are that they really are pure energy and contain no mass as we normally think of it.
And... what does radiation do to people then?
Well, realize that radiation is energy in motion. So, what it will do, like anything in motion, is try to slow down. Sorta like when your hand gets hot from friction, radiation gives up energy to surrounding atoms as it travels through some material. It doesn't matter if the material is lead, air or you. Radiation can be classed by how much energy it gives up to the surrounding material.
Ionizing radiation has enough energy that during an interaction with an atom, it can remove tightly bound negative electrons from it, causing the atom to become charged or ionized. Examples of radiations that are ionizing are gamma rays and neutrons
Non-ionizing radiation does not have enough energy to remove tightly bound electrons from their orbits around atoms. Examples of radiations that are non-ionizing are microwaves and visible light
If radiation is passing through your cells, which are primarily made of water, it will causes electrons to leave some of the atoms in the cell. These atoms then will have a charge (an ion) and can go on to react with other atoms in the cell, causing damage. An example of this would be if a gamma ray passes through a cell, the water molecules near the DNA might be ionized, then the ions might react with the DNA causing a break in it.
With enough damage, the cell might die. Your body though has trillions of cells and repairs most of the damage quickly. Radiation amounts which this cell death might cause a physical problem like radiation sickness can only happen during major accidents and so are extremely rare.
So, we don't get radiation unless we have nuclear reactors, right?
Nope! Humans have been exposed to radiation from natural sources since the dawn of time. The sources include the ground we walk on, the air we breath, the food we eat and the solar system on the whole. Everything in our world contains small amounts of radioactive atoms like Potassium 40, Radium 226 and Radon 222. These are either left over from the creation of the world (like Uranium and Radium) or made by interactions with cosmic radiation (like Carbon 14 and Tritium). Also, the Earth is constantly receiving cosmic radiation from outer space. These natural sources of radiation make up approximately 82 percent of the average annual dose to the US public. Nuclear Power makes up much less than 1%.
OH YA, what about that radon?
Everyone by now has probably heard of radon. Radon comes from the decay of Uranium, a natural element. Uranium decays through a long chain of radionuclides (radioactive elements) that includes radon. Radon is a noble gas, not chemically active so it migrates through porous materials like the ground and your house's foundation. The radon itself has small chance of decaying as you breath it in and out being a gas. Most of our actual dose comes from the decay products of radon, sometimes called radon daughters or, radon progeny. These radon daughters are particles not gases, and can bedeposited in your lungs as you breath. There they have some chance ofdecaying before your body can get rid of them, giving you a dose.
And then... radon kills people?
Radon seems to be able to cause lung cancer, but the link between radon and cancer is not as clear as you would think. Studies of Uranium miners showed an increase in lung cancer for the miners. But the studies also showed that the risk of lung cancer was complicated by smoking and other actions that not only add to the risk, but in combination with radon, actually multiply the risk. Once again, the fact that we have always been exposed to small amount of radon would probably mean that our body can effectively repair that damage. It is when additional factors that our bodies have not been exposed to for millions of years (like smoking, pollution and stress) are taking into account, it would be a good idea to limit the radon exposure to reasonable levels near background.
But, what about mutations like the incredible hulk and spider man?
So, you watch too much TV, huh. OK, mutations. Mutations are another name for changes in the genes that are passed on to offspring. In our world, there is a natural incidence of mutations, and that is near 10%. Out of that 10% though, most of the mutations are harmless and have no bearing on he health of the individual. In studies that have been following the survivors of the atomic bombs in Japan have found no increase in the natural incidence of harmful mutations. Some laboratory studies have shown that mutations are possible in rats. So, don't over expose your rats! Only kidding. What this probably means is that there is some chance of harmful mutations in humans, but have not been seen due to being so rare. The mass media version of mutations are fantasy, sorry no spidy or hulk, no godzilla either.
This will be a monthly feature where I will place facts concerning radition, radiation exposure or radiation safety.
Answer -
There are four fundamental forces in nature. They are the strong nucler and weak nuclear, electro-magnetic, and gravity forces. These all work with and against each other as the universe tries to gain a stable, low ordered state (lowest energy-most random). Also looking at this question, we need to realize that matter is another form of energy and that energy is the ability to do work. The center of an atom, the nucleus, is held together (work) by converting a little of the mass of the particles of the nucleus into a binding energy. This is needed to keep all those positively charged protons so close to each other. For light elements, if the number of protons and the number of neutrons are the same, all the forces acting in the nucleus are well matched and the nucleus is stable. But if there are too many neutrons or protons, then the nucleus has too much energy and will normally transfer energy around until the 1:1 neutron to protron ratio is achieved. This frequently is seen as the emission of the energy, or what is called radiation. At higher atomic numbers, there are so many protons, that you need more than 1 neutron per proton to hold the nucleus together. But there still may be stable configurations for the atoms, and the atoms may try to reach those states by emitting the larger alpha particle. Sometimes, following the initial release of energy, there still may be extra energy in the nucleus, and this can be emitted as a photon, or by transferring the energy to the orbital electrons.
Answer -
The forms of radioactive decay and other associated processes are as follows:
Decays -
Other processes related to decay -
Answer -
Natural radiation takes the same forms as "human-caused" radiations. All the same decays discussed above happen naturally. Radiation we are exposed to from our environment include Cosmic (high energy particles and EM from outside of our galaxy), Cosmic induced (C-14, Tritium made in the atmosphere by interation with cosmic radiation), Solar (UV from the sun mostly, but in space can be particles), and terrestrial (Uranium, Thorium, Radon contained in the Earth itself). Life forms have incorporated all of these into their biomasses, so all life on Earth has some amount of radioactivity in it. That includes the food and water we ingest, and humans in general.
Answer -
Because ionizing radiation does just that, ionizes, it is easy to see that using a medium like a gas, and a voltage, you can measure the amount of charge liberated in that medium. And that is the most common method of measuring radiation. The infamous Gieger Counter is in reality a small volume of gas, with a voltage applied across it. As the radiation enters the gas, it causes electrons to be formed which are collected and measured to determine the amount of intial radiation present. Another common detection device uses a process similar to the Glow-In-The-Dark plastics, paints, and watches that can be found in every store. While a little more complicated than that, the processes used with radiation detection is called scintillation. Scintillation is the giving off of visible light after interaction with radiation. The light can be collected then and used as another measure of the radiation intensity and energy. But, there are many different ways of measuring radiation, using semiconductors, liquids, superheated bubbles, crystals and plastics.
Answer -
The applications of radiation are numerous. I have listed some below:
MEDICAL
INDUSTRIAL
HOUSEHOLD
SCIENCE
There are many, many more...
Answer -
The effect depends on the amount (dose), ranging from no effect (low) to death (high). For the most part, what radiation does is create ions in our cells, and these ions cause problems in the cell. damage may lead to cancer.
The radiation may interact directly with biologically significant molecules, like DNA and proteins. Radiation may also interact indirectly to cause damage, by interacting with chemicals in our bodies, such as water, and form very active chemicals like free radicals that can cause damage to the biologically significant molecules. The damage can be repaired, or the cell may die, or it might even actually affect the tissue/organ if there is enough damage. It is felt that the damage to the DNA is of the most importance, and could lead to increase risk of cancer. The damage can be to a single base pair on the DNA, or could cause the DNA to bind to itself or cause an actually break the DNA on one stand or more rarely, to both DNA strands. If the damage is not repaired (or is repaired wrong) and the cell escapes apotosis (programmed cell death) it might have one of the several needed steps that results in the cell becoming a cancerous. But the chain of events that leads from DNA damage to cancer is a long, multi-step process with many check points along the way where things must go wrong in order to cause cancer.
One of the reasons cancer is not more common is that your body's repair mechanisms are continuely working to fix damage to your DNA. Your DNA is subject to many types of stresses that cause damage. This happens often and it is surprising to see how many times each hour each cell's DNA is damaged:
| Damage | Events per hour |
|---|---|
| Depurination | 580 |
| Depyrimidation | 29 |
| Deamination of Cytosine | 8 |
| Single-Stranded Breaks | 2300 |
| Single-Stranded breaks after depurination | 580 |
| Methylation of Guanine | 130 |
| Pyrimidine (thymine) dimers in skin (noon day sun) | 5 x 104 |
| Single-stranded Breaks from Background Radiation | 1 x 10-4 |
| Double-stranded Breaks from Background Radiation | 4 x 10-6 |
But, our repair mechanisms fix these damages at very high rates and efficiencies. This is an evolved mechanism, and protects our complicated and large DNA from unwanted changes.
| Damage | Repairs per hour |
|---|---|
| Single-stranded breaks | 2 x 105 |
| Pyrimidine dimers | 5 x 104 |
| Guanine methylation | 104-105 |
If the damage is in the sex cells, there would be some risk of a DNA change, a mutation, being passed on to the next generation. The physical effects of these radiation induced mutations have never been seen in humans though. Humans have about a one in ten chance of passing along a natural (non-radiation induced) mutation to their offspring. This natural rate normally is of little consequence, either being recessive or not health threatening, but some do cause significant health problems. Many studies have looked for the physical manifestations of the radiation damage in the children, grand children and great grandchildren of the Atomic Bomb survivors, and have not shown an increase above this natural rate in these populations.
Information on related fields:
OK... so I didn't know where to put this stuff...
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This HomePage is maintained Bruce Busby and all written material is the opinion of the author and should be taken, as should all information, with 0.0649 grams of NaCl (grain of salt). Updated 11/14/98
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