What makes radioactivity dangerous for people

The question of the week: Why is radioactive radiation dangerous?


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The question of the week: Why is radioactive radiation dangerous?

Every week we answer your questions on all kinds of topics. Today Jonas W. from Liers asks us: Why is radioactive radiation dangerous? Here's the answer ...

On Saturday, March 11th, 2011 there was a severe earthquake in the sea off Japan. This triggered a huge tidal wave, a so-called tsunami.

The tsunami washed over large areas in the northeast of the Japanese main island of Honshu, known as Fukushima ("island of happiness"). The Fukushima-Daiichi nuclear power plant was also hit by the masses of water. The power station was badly damaged and radioactivity escaped.

Why is radioactivity so dangerous?

Radioactive radiation is a form of electromagnetic radiation, just like radio waves that your radio makes audible, microwave radiation from the microwave oven, warming infrared radiation or visible light. However, radioactive radiation is particularly high-frequency and short-wave. It can cause serious damage.

The so-called "electromagnetic spectrum" is shown here. On the far right it begins with the long-wave radio waves, goes to the left over the microwaves to the visible light, which is particularly emphasized. This is followed by ultraviolet radiation, X-rays and finally gamma radiation. With our eyes we can only perceive a tiny section of the dangerous and harmless types of radiation that surround us.

The longest wavelengths have radio waves. Their wavelength can be up to 10 kilometers. Medium, short and ultra-short waves range up to a wavelength of around one meter - radio and television broadcasts are transmitted with them.

This is followed by the microwaves. Their wavelength is in the centimeter and millimeter range. A certain wavelength goes well with the water molecule and makes it vibrate. It heats up in the process, which is how the microwave oven works.

Infrared radiation follows the microwave range. It is the infrared radiation from the sun that you feel as warmth outside in the sunshine. Then that part of the electromagnetic spectrum begins that we can perceive with our eyes - the visible light. It goes through red, yellow, green to blue. Then comes the ultraviolet, which is invisible to us again.

Always more energetic

Now we have already reached the particularly high-energy and short-wave range of the electromagnetic spectrum. Ultraviolet radiation is also contained in sunlight. It is responsible for tanning the skin and for the formation of vitamin D. However, too much sun and therefore too much ultraviolet radiation leads to sunburn - the skin reddens and hurts like a burn.

Beyond the ultraviolet comes the X-rays, which can penetrate your body and which are used in medicine for fluoroscopy - this is how you can detect broken bones and some other internal injuries.

Now comes the area of ​​deadly gamma radiation. It is particularly rich in energy and can quickly lead to death, depending on how intense the radiation is and how long you are exposed to it. But what makes it so dangerous?

Radio waves at the lower end of the spectrum have wavelengths of up to ten kilometers and more. Microwaves have moved in the centimeter range, visible light oscillates in the range of less than a millionth of a meter.

The gamma radiation now has wavelengths in the range of a trillionth of a meter or a picometer - one trillion (1000 billion) oscillations fit into one meter. Gamma rays vibrate very quickly and have great energy.

Wavelength and energy

Do the test yourself: Take a piece of rope or a longer, not too light string. If you swing it back and forth slowly, you will see long waves and it will not be very strenuous. The faster you swing the string from left to right, the shorter the waves become and the more energy you have to put into it.

Ultraviolet radiation, X-rays and gamma rays vibrate extremely quickly. They have so much energy that they can damage the building blocks of your body. Because your body consists of many cells, which in turn are composed of small chemical building blocks, the molecules.

The above-mentioned types of radiation can now throw the molecules out of their composite and thereby damage the cells and thus your body. It is as if stones were knocked out of a wall - if too many stones are gone, the wall collapses.

One can imagine that the molecules would be small tuning forks. Radio waves have a wavelength that is far too long to excite the tiny molecules - so no energy from the radio wave is transferred to the molecule, they are not in resonance. Now the wavelength is getting smaller and smaller, and from the range of UV radiation (followed by X-ray and gamma radiation) the wavelengths are small enough to excite the molecule and transfer energy - if too much energy is used, the molecule breaks.

Light, UV radiation and radioactivity

Visible light doesn't harm us, but ultraviolet radiation does. It already has a lot of energy, but cannot yet penetrate deeply into the body. However, it can damage the top layers of the skin and lead to sunburn. Too much sun or solarium also leads to skin cancer!

X-rays and gamma rays, on the other hand, penetrate the body and your cells. In the case of an X-ray, a small dose is only used very briefly, which does not break anything straight away.

However, if you are in a contaminated environment or if you ingest radioactive substances, for example through food, then the gamma radiation leads to the genetic information in the cell being destroyed. The genetic information (also called "DNA molecule") is necessary for the body to grow and develop. If this is damaged, cells will not divide properly and it can lead to serious and deadly diseases such as cancer.

By the way:

* Some animal species (such as insects and snakes) can still perceive infrared and ultraviolet. Many flowers have patterns that glow in the sun's ultraviolet light.

* Radioactive radiation is also divided into three areas: alpha, beta, and the particularly dangerous gamma radiation.

* Up to visible light one speaks of "non-ionizing radiation". Radiation with more energy (ultraviolet, X-ray and gamma radiation) is also called "ionizing radiation" because of its ability to throw particles out of their composite. This radiation not only affects living tissue, but also electrical circuits in computers and robots - that's why you can't just use robots in power plants in Japan!

* There is also what is known as background radiation. This describes the natural radioactivity of the environment. For example, granite and other natural substances also radiate naturally. But they only send out very small doses that are harmless. Your body also naturally contains a certain radioactive form of the element potassium, for example. It is absorbed through food, among other things - but that is quite natural and that was there long before humans made atomic energy usable!

* Even today, among other things, some types of mushrooms from the forest or the meat of wild animals in Bavaria are heavily radioactive due to Chernobyl.

additional Information

If you are a bit older and can speak English, then there is a very interesting documentary from the BBC on the history of nuclear power: "A is for Atom".

Text: -jj- 5.5.2011 // Images: Fukushima cc-by-sa 3.0; Spectrum Horst Frank / Phrood / Anony cc-by-sa 3.0; Warning sign PD

Note: All images and links have been removed from the archive