How dangerous in the radiation coused from explosion at Japanese nuclear plant?

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The Japanese government warned its citizens from increased radioactivity. What dose is harmful to health? At what value of the ionizing radiation kills instantly?

Radioactive substances are found in soil, rocks, the atmosphere, but also in the human body. Medicine, research and technology use natural radioactive substances targeted or create it artificially. The unit Sievert measures the radiation exposure of people and takes into account the different biological effectiveness of different types of radiation. 1 Sievert is already a relatively high dose, usually occurring values ??are in the mSv range. For information,  radiation average citizen is exposed to per year, average is 4 mSv. This is where the values ??of natural radiation exposure, which can vary regionally strong, and medicinal values ??together. Also, some occupations with higher doses of ionizing radiation will be charged.

“According to current knowledge there is no lower limit at which a health risk can be ruled out,” say medicinal experts. The health risk depends on many factors: the type of exposure (external over the air or incorporated through diet), but also the age of the person concerned. For children, the exposure is more risky than for adults because they are growing and their cells divide much more frequently. “What you can say for sure is that the health risk increases with increasing dose,” says the scientist.

Damage to body cells
Very high doses of ionizing radiation cause first of all to symptoms such as headache, nausea or vomiting. Acute radiation sickness occurs at a dose equal to about 500 mSv for adults. Children show the symptoms already much earlier, from about half of that value.

After a nuclear accident are subjected to high doses of ionizing rays on the body’s cells. They destroy cell components and bring the body’s cells to die. The radiation sickness is the result of massive cell death in an organ or tissue system that is dependent on a constant supply from the stem cell reservoir of the body. This includes in particular the hematopoietic system (bone marrow), the skin and the mucous membrane of the gastrointestinal tract.

But even lower doses of damaging the genetic material (DNA). Provoke changes in the genetic information that are passed on to the next cell division to daughter cells. The greater the damage to DNA, the higher long term risk for cancer

Lethal dose of ionizing radiation
The symptoms of acute radiation injury include redness and combustion-related phenomena of the skin (erythema), alopecia, impaired fertility and anemia (anemia). A general treatment exists for these problems, it’s only possible to replace the destroyed skin transplants or with stem cell therapy, bone marrow function, and thereby restore the hematopoietic system.

Exceeds the extent of cell death in a tissue or organ of a certain level, it is destroyed. A value of about 4 to 5 Sievert is as LD-50 for ionizing radiation. The value is the lethal dose, with the death of half the people who were exposed to. The absolute lethal dose of ionizing radiation is about 8 Sievert. (Atomic bomb victims died after they had already received a higher dose than 6 Sievert, there were already some radiological accidents that some victims have survived a certain time.

If the radiation dose is below the threshold of about 500 mSv, then victims shall have  no acute injury. Experts suspect that later health problems including cancer, leukemia, as well as cardiovascular, gastrointestinal and eye disorders. After the meltdown at Chernobyl, for example, received significantly more child thyroid cancer. Typically, a child suffering from a million to it. In the most contaminated regions of Belarus and Ukraine after it hit 100-150 children of one million.
Have the radioactive clouds dispersed and is the external action of the rays on the body over, often followed by a further health risk. It consists in the incorporation of the radioactive elements, so that people eat for a long time repeatedly contaminated food and drinking contaminated water. This happened for example after the nuclear disaster at Chernobyl the case. The residents of the affected areas continue drinking the milk of cows that ate contaminated grass, hunted and gathered wild mushrooms loaded. They had no choice, because other foods were not. Here, people in Japan an advantage: If there should come to the meltdown, probably sufficient financial resources to switch to imported food.

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