Radioactive Fallout
The term "radioactive fallout" refers to the contamination caused by nuclear events that have taken place in the atmosphere. Some of these events have been deliberate, such as the scientific testing of nuclear weapons, while others have been accidental, like the nuclear power station meltdowns that have occurred in various parts of the world. The radioactive dust and debris from these nuclear events are transported by the wind and contaminate the land, water, and food chain wherever they settle.
Radioactive materials emit several kinds of radiation. One type of radiation is the spontaneous emission of sub atomic particles such as protons, neutrons and electrons. Another type is gamma radiation, which is similar to X radiation. Both forms of radiation are known to be toxic, and exposure to large doses of such radiation cause death and mutation of offspring due to DNA damage. Smaller doses may cause late onset cancer, sometimes years after the exposure to the radiation.
Background radiation has always been present, originating from outer space and minerals in the earth. However, in the 1950s and 1960s it was discovered that the background radiation level was increasing. The increase was caused by the detonation of nuclear bombs in the upper atmosphere as part of the weapons testing programs being conducted by the United States, Union of Soviet Socialist Republics, Britain, France, and China. The winds were scattering the radioactive materials, such as strontium-90, potassium-40, carbon-14, caesium-137, and iodine-131, all around the world. While heavier particles tended to fall to the earth just downwind of the explosion, the lighter particles stayed in the atmosphere for years.
Studies showed that these radioactive materials become more concentrated at each step of the food chain, and in some cases, food animals were destroyed because of the high level of radioactivity contained within their bodies. Radioactive fallout became a worldwide concern and, in an effort to halt the rising levels of background radiation, the nuclear powers negotiated a test ban treaty in 1963. Since that time the background radiation count has fallen.
In 1982, the United States Congress required the National Cancer Institute to investigate the effects of the iodine-131 component of the radioactive fallout from the nuclear bomb testing program of the 1950s and 1960s. The report, released in 1997, indicated that some children in the western states downwind of the Nevada tests had higher than normal doses of the radioactive component from drinking contaminated milk, which has resulted in an increased number of thyroid cancer cases.
With the halt of nuclear bomb testing, accidental release of radioactive fallout by nuclear meltdowns became a growing concern, especially for those living downwind of nuclear facilities. In Britain the accidental releases of radioactive fallout made it necessary to dispose of milk and destroy herds of sheep on several occasions. The Three Mile Island accident, in Pennsylvania, released relatively small amounts of fallout, but nevertheless caused major public concern about the nuclear energy program in the U.S. The Chernobyl disaster (1986) caused a plume of radioactive fallout to cover northern Europe. Research is being done to measure the effect of this fallout on the reindeer population of northern Sweden.
Radioactive fallout is a controversial issue where extreme positions are often taken. It will continue to be an issue as long as nations continue to test nuclear weapons, build more nuclear power stations, and try to dispose of the accumulating nuclear waste.
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