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How Dangerous Is Atomic Radiation?

YOU don’t see them or feel them, but right now your body is in a relentless crossfire of subatomic particles. Like tiny machine-gun bullets, these particles score enormous numbers of direct hits on your body cells every day. Although they come in different sizes and shapes, hitting you at different speeds and with different effects, they are collectively known as atomic radiation. What is that radiation doing to you?

A simple question, is it not? Perhaps you would like a simple answer. Sad to say, no simple answer is available. The issue of what radiation is doing to people today is one of the most hotly debated subjects in modern science, medicine and even politics.

Perhaps you recall the American nuclear reactor that broke down at Three Mile Island in Pennsylvania back in 1979. No one was directly hurt when the accident took place, but some radioactivity was released in the following days as a result of it. Some scientists estimated that the radioactivity might ultimately cause thousands of deaths to local people from cancer. On the other hand, the official report of the President’s Commission on the Accident at Three Mile Island stated: “There will either be no case of cancer or the number of cases will be so small that it will never be possible to detect them.”

Who is right? Nobody knows for sure. This is largely because people near Three Mile Island received relatively low doses of radiation from the accident. Scientists generally agree on what happens when you get a very large dose of radiation. High-level radiation will quickly make you very sick, and if you survive, you will have a significantly increased chance of getting cancer in the future. It is the effect of low-level radiation that is not so well understood.

What Is Radiation, Anyway?

Not all radiation is alike. Atomic radiation is basically made up either of tiny pieces of atoms, such as electrons, or of little energy packets called photons. The nuclei of some atoms are unstable and break apart, giving off radiation in the process. These unstable nuclei are said to be radioactive. When atomic particles strike a cell, they give up some energy, just as a speeding bullet gives up some energy when it hits a target.

The cell is usually not prepared to handle this sudden collision. Cells are made of many different kinds of very complicated molecules that must work together in perfect harmony. A particle of atomic radiation will often knock an electron off one of those complicated molecules, turning the molecule into an ion. Ions can be very dangerous to a cell because they tend to get violently involved in reactions with other molecules as they desperately seek to replace the electrons they have lost. These molecular “muggings” can be disastrous for the cell. Unless the cell’s repair systems restore matters, the cellular harmony is disrupted, dangerous combinations of molecules can result and the cell can even die.

Radiation capable of causing these dangerous ions is called, as you may have guessed, ionizing radiation. Lower-energy radiation, such as microwaves, is nonionizing.

Some atomic radiation is made up of particles that are weightless and travel very fast, such as high-energy photons or gamma rays. Similar high-energy photons can be generated by man, without using a radioactive source, and these are usually called X rays. Perhaps your doctor or dentist has taken an X ray of you. Both X rays and gamma rays could be compared to high-velocity rifle bullets. Interestingly, those same photons that are sometimes dangerous as gamma rays are harmless at certain lower energies. Light, for example, is also made up of photons, but we don’t mind a little light! At still lower energies, the photons are called microwaves and these can be dangerous, even though they are nonionizing.

A very different type of atomic radiation comes in the form of beta particles. These particles are heavier than photons and they travel more slowly. In fact, beta particles are just electrons, like the electrons that run down wires to make your toaster work. The only difference is that these high-energy electrons have been violently expelled from a radioactive nucleus. Beta particles and gamma rays tend to produce similar effects when striking one of your cells.

Still different is the alpha particle. Alpha particles are thousands of times heavier than beta particles; so they generally don’t travel as fast or as far. But when your cell is hit by an alpha particle, watch out! If gamma-ray photons and beta particles are like rifle bullets, then alpha particles are like cannonballs, and they can do a great deal of damage inside a cell. While the cell can often repair damage from beta particles or gamma rays, alpha-particle damage is much harder for the cell to repair. Alpha particles are formed when a radioactive atom throws off two protons and two neutrons, all stuck together.

Sometimes radiation can consist of protons and neutrons by themselves. Cosmic rays that bombard the earth from space are mostly caused by high-energy protons, and neutron bombs have been designed that would use high-energy neutrons to penetrate buildings or tanks and kill people.

Since different types of atomic radiation have different effects on people’s cells, scientists do not all agree on just how doses of low-level radiation compare with one another. Are neutrons (which can cause ordinary atoms to become radioactive), twice as bad for your cells as gamma rays, or are they eight times as bad? Are alpha particles eight times or twenty times as bad as gamma rays? Scientists are not sure.

This is significant because different people are exposed to different types of atomic radiation. People who have X rays receive mostly one type, while uranium miners might get heavy doses of another type, and nuclear-fallout victims still another.

Background Radiation

There is one type of radiation to which we are all exposed. That is natural “background” radiation. It comes from the soil we walk on, and from the bricks in our houses, which contain small amounts of radioactive atoms. A little more comes from cosmic rays striking earth’s atmosphere. Another dose is from our own bodies! People contain lots of carbon and potassium, and a tiny fraction of it is radioactive.

The average North American gets about one fourth as much background radiation as do people living in parts of Brazil or India, where there is more radioactive material in the local soil. Is the extra radiation found in Brazil or India dangerous? It might be. On the other hand, background radiation is higher in Colorado than in New York, but cancer rates are lower.

It is very hard to measure the effects of small amounts of radiation. A small dose of radiation does not make you feel bad or make your hair fall out, but it might increase your chances of getting cancer someday. However, suppose you do get cancer. How would you know it was caused by the radiation? It might have been caused by several things. As Dr. Karl Morgan, a nuclear engineer, points out: “A given type of leukaemia may require as many as three successive events (like throwing three electrical switches connected in series). Some of these switches may be thrown by viruses, bacteria, chemicals, mechanical damage or radiation.”

A small dose of radiation might be much more dangerous to one person than to another. A child with severe allergies might be three or four times as likely to get cancer as would a normal child. Perhaps a third child was exposed to radiation when his mother was x-rayed while pregnant with him. This child’s risk of getting leukemia would be 50 percent higher than that of the normal child. But what would happen if the child with allergies had been exposed to those X rays in the womb? His cancer risk would now be, not three or four times, or even six or eight times as high, but fifty times as high as that of the normal child!

“Extra” Radiation

Most people today receive “extra” radiation in addition to what they get from the normal radioactive background. In the United States the average yearly dose of radiation is nearly doubled because of these extra sources, mostly in the form of medical X rays. Could that chest X ray you got last month give you leukemia five years from now? Possibly, but before you panic, remember that all medical procedures​—even taking an aspirin—​entail some risk. If the benefits of an X ray outweigh the slightly increased cancer risk, then your doctor may advise an X ray with good reason.

Another increasingly common source of extra radiation is energy conservation in the form of home insulation! How can that be? Well, most common building materials contain a few radioactive atoms of radium. These atoms gradually decay into lead, passing through several stages in the process. At one point the radium atoms have turned into radon, which is a radioactive gas. As long as the radium atoms remained radium, they were trapped inside crystals in the bricks or stones of your house. But when they turn into radon they get loose, and some of them diffuse into the air in your home.

When you breathe air with radon atoms in it, some of those atoms may get trapped in your lungs, where they will quickly decay into lead, giving off alpha particles in the process. Remember the alpha particles? These are the subatomic “cannonballs” that can do so much damage to your cells. If a radium atom decays into lead while it is trapped in your wall, the alpha particles it gives off will never get to you. Alpha particles have a hard time traveling very far even through the air. But once you have breathed in a former radium atom (in the form of radon) and those alpha particles are fired right inside your body, they can be very harmful.

The dangers of radon gas have been established by generations of uranium miners who have suffered high levels of lung cancer. No one would be too surprised to learn that uranium miners have high levels of cancer, but why lung cancer? Because uranium mines contain high concentrations of radon gas (modern mines are now much better ventilated) and the alpha radiation from the gas contributes to lung cancer.

So radiation is not just something you get from your local nuclear power plant. You get it from your own slightly radioactive bones, from medical X rays, from your color TV (which gives off a few X rays), from your airplane flight (cosmic rays are more intense at high altitudes) and from your well-insulated, energy-efficient home.

How dangerous is low-level radiation? Nobody knows for sure, but taking reasonable precautions against needless exposure cannot be a bad idea!

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If X rays and gamma rays are like high-velocity rifle bullets inside the cell, then alpha particles are like cannonballs

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If the benefits of an X ray outweigh the slightly increased cancer risk, then your doctor may advise an X ray with good reason

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Precautions You Can Take

Avoid watches and clocks with glowing radium paint. Radium emits alpha particles and gives off radon gas. Discard such items if the crystal is cracked.

Keep radioactive identification cards or driving licenses in a proper protective cover.

Keep track of your X rays and don’t ask your doctor for X rays he doesn’t think you need. When given an X ray, ask for proper shielding.

If you have a color TV, keep it in good repair and watch it from a distance.

If you have to work around radiation, follow safety precautions strictly.

Make sure your house is properly ventilated to guard against radon-gas buildup. This can be done without sacrificing energy efficiency by using heat exchangers.

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Three Mile Island