You may have seen this sign before—maybe in a hospital. The sign means there is danger of radiation in the area. Radiation consists of particles and energy that are given off by radioactive isotopes, which have unstable nuclei. But you don’t have to go to a hospital to be exposed to radiation. There is radiation in the world all around you.
Radiation in the Environment
A low level of radiation occurs naturally in the environment. This is called background radiation. One source of background radiation is rocks, which may contain small amounts of radioactive elements such as uranium. Another source is cosmic rays. These are charged particles that arrive on Earth from outer space. Background radiation is generally considered to be safe for living things. You can learn more about background radiation with the animation at this URL: http://www.pbs.org/wgbh/nova/dirtybomb/sources.html
Dangers of Radiation
Long-term or high-dose exposure to radiation can harm both living and nonliving things. Radiation knocks electrons out of atoms and changes them to ions. It also breaks bonds in DNA and other compounds in living things. One source of radiation that is especially dangerous to people is radon. Radon is a radioactive gas that forms in rocks underground. It can seep into basements and get trapped inside buildings. Then it may build up and become harmful to people who breathe it. Long-term exposure to radon can cause lung cancer.
Exposure to higher levels of radiation can be very dangerous, even if the exposure is short-term. A single large dose of radiation can burn the skin and cause radiation sickness. Symptoms of this illness include extreme fatigue, destruction of blood cells, and loss of hair. To learn more about the harmful health effects of radiation, go to this URL: http://www.cbsnews.com/video/watch/?id=7359819n .
Nonliving things can also be damaged by radiation. For example, high levels of radiation can weaken metals by removing electrons. This is a problem in nuclear power plants and space vehicles because they are exposed to very high levels of radiation.
Q: Can you tell when you are being exposed to radiation? For example, can you sense radon in the air?
A: Radiation can’t be detected with the senses. This adds to its danger. However, there are other ways to detect it.
You generally can’t see, smell, taste, hear, or feel radiation. Fortunately, there are devices such as Geiger counters that can detect radiation. A Geiger counter, like the one pictured in the Figure below , contains atoms of a gas that is ionized if it encounters radiation. When this happens, the gas atoms change to ions that can carry an electric current. The current causes the Geiger counter to click. The faster the clicks occur, the higher the level of radiation. You can see a video about the Geiger counter and how it was invented at the URL below.
Despite its dangers, radioactivity has several uses. For example, it can be used to determine the ages of ancient rocks and fossils. It can also be used as a source of power to generate electricity. Radioactivity can even be used to diagnose and treat diseases, including cancer. Cancer cells grow rapidly and take up a lot of glucose for energy. Glucose containing radioactive elements can be given to patients. Cancer cells take up more of the glucose than normal cells do and give off radiation. The radiation can be detected with special machines like the one in the Figure below . The radiation may also kill cancer cells. You can learn more about medical uses of radiation at this URL: http://www.youtube.com/watch?v=v_8xM-mLxJ8
This machine scans a patient’s body and detects radiation.
- A low level of radiation occurs naturally in the environment. This background radiation is generally assumed to be safe for living things.
- Long-term or high-dose exposure to radiation can harm living things and damage nonliving materials such as metals.
- One reason radiation is dangerous is that it generally can’t be detected with the senses. It can be detected only with devices such as Geiger counters.
- Radiation has several important uses, including diagnosing and treating cancer.
Watch the video about uses of radiation at the following URL, and then answer the questions below. http://www.youtube.com/watch?v=TdbzShLU30w
- Alpha radiation is used in smoke alarms. Explain how a smoke alarm uses this form of radiation.
- Identify a use of beta radiation, and explain how it works.
- List three uses of gamma radiation, and describe one of them in detail.
- What are two sources of background radiation?
- How can radiation harm living things?
- What is radon, and why is it harmful to people?
- How does a Geiger counter detect radiation?
- What are some uses of radiation?