Radiation occurs when unstable nuclei of atoms decay and release particles. There are many different types of radiation. When these particles touch various organic material such as tissue, damage may, and probably will, be done. Radiation can cause burns, cancers, and death.
Units of Measurement
The unit used to measure radiation dosage is the rem, which standsfor roentgen equivalent in man. It represents the amount of radiation needed to produce a particular amount of damage to living tissue. The total dose of rems determines how much harm a person suffers. At Hiroshima and Nagasaki, people received a dose of rems at the instant of the explosions, then more from the surroundings and, in limited areas, from fallout. Fallout is composed of radioactiveparticles that are carried into the upper atmosphere by a nuclear explosion and that eventually fall back to the earth's surface.
Effects of Radiation Exposure on Human Health
Although a dose of just 25 rems causes some detectable changes in blood, doses to near 100 rems usually have no immediate harmful effects. Doses above 100 rems cause the first signs of radiation sickness including:
some loss of white blood cells
Doses of 300 rems or more cause temporary hair loss, but also more significant internal harm, including damage to nerve cells and the cells that line the digestive tract. Severe loss of white blood cells, which are the body's main defense against infection, makes radiation victims highly vulnerable to disease. Radiation also reduces productionof blood platelets, which aid blood clotting, so victims of radiation sickness are also vulnerable to hemorrhaging. Half of all people exposed to 450 rems die, and doses of 800 rems or more are always fatal. Besides the symptoms mentioned above, these people also suffer from fever and diarrhea. As of yet, there is no effective treatment--so death occurs within two to fourteen days.
In time, forsurvivors, diseases such as leukemia (cancer of the blood), lung cancer, thyroid cancer, breast cancer, and cancers of other organs can appear due to the radiation received.
Major Radiation Exposure in Real Life Events
Hiroshima and Nagasaki
For more information on what happened at Hiroshima and Nagasaki, consult the nuclear past page and the nuclear warfare page.
Many people at Hiroshima andNagasaki died not directly from the actual explosion, but from the radiation released as a result of the explosion. For example, a fourteen-year-old boy was admitted to a Hiroshima hospital two days after the explosion, suffering from a high fever and nausea. Nine days later his hair began to fall out. His supply of white blood cells dropped lower and lower. On the seventeenth day he began tobleed from his nose, and on the twenty-first day he died.
At Hiroshima and Nagasaki, the few surviving doctors observed symptoms of radiation sickness for the first time. In his book Nagasaki 1945, Dr. Tatsuichiro Akizuki wrote of the puzzling, unknown disease, of symptoms that "suddenly appeared in certain patients with no apparent injuries." Several days after the bombs exploded, doctors learnedthat they were treating the effects of radiation exposure. "We were now able to label our unknown adversary 'atomic disease' or 'radioactive contamination' among other names. But they were only labels: we knew nothing about its cause or cure... Within seven to ten days after the A-bomb explosion, people began to die in swift succession. They died of the burns that covered their bodies and of acuteatomic disease. Innumerable people who had been burnt turned a mulberry color, like worms, and died... The disease," wrote Dr. Akizuki, "destroyed them little by little. As a doctor, I was forced to face the slow and certain deaths of my patients."
Doctors and nurses had no idea of how their own bodies had been affected by radioactivity. Dr. Akizuki wrote, "All of us suffered from diarrhea and...