The explosion and fire at the Japanese Nuclear Plant in NorthEast of Japan has led to the release of a small nuclear plume above the reactors.The southern winds have caused this radiation to spread in many of the prefectures in Japan and cesium and other radioactivity has been detected in the capital of Tokyo.Note Radiation does not affect the human body in small doses as radiation is present in our everyday lives at well.However the increase in radiation concentration can lead to severe health hazards and in extreme cases even death.It is almost impossible to escape radiation effects unless one has special nuclear,biological warfare protective equipment.Note Radiation in Japan is still at quite mild levels and seems unlikely to cause any major health hazard.Radiation will need to increase about 1000 times from the current level for the situation to become serious as of now
Radiation levels shot up in Tokyo and its vicinity Tuesday following the nuclear accident at the Fukushima No. 1 nuclear power plant in northeastern Japan that was triggered by last week’s massive earthquake and subsequent tsunami, local governments said.
But those levels did not pose immediate danger to human health, the Ministry of Education, Culture, Sports, Science and Technology said.
In Tokyo, small amounts of radioactive substances, such as iodine and cesium, were detected, the metropolitan government said.
In Ibaraki Prefecture, adjacent to Fukushima Prefecture where the troubled Fukushima No. 1 nuclear power plant is located, the amount of radiation at one stage reached 5 microsievert per hour, 100 times higher than usual, the Ibaraki prefectural government said.
In Kanagawa Prefecture, the radiation level shot up 10 times higher than usual.
In Saitama, capital of Saitama Prefecture, the amount of radiation reached 1,222 nanosievert per hour — a figure about 40 times higher than usual.
In Ichihara, Chiba Prefecture, the amount of radiation showed a two- to four-fold increase, the Chiba prefectural government said.
The amount of radiation rose to 1.318 micro sievert per hour — a figure 33 times bigger than usual — in Tochigi Prefecture’s capital of Utsunomiya, the Tochigi prefectural government said.
The science ministry said it had asked prefectural governments to observe radiation levels as frequently as possible.
Meanwhile, Chief Cabinet Secretary Yukio Edano said the radiation level reached 400 millisievert per hour near the No. 3 reactor at the Fukushima No. 1 plant Tuesday morning. The amount is 400 times higher than the allowable limit for citizens in a year.
On Monday, the radiation level near the No. 3 reactor peaked at 3,130 microsievert or about 3 millisievert per hour.
Radiation Levels and Effect on Human Health at Different Levels
Radioactivity is measured in rads where a rad is a hundredth of a joule per kilogram of tissue. A gray, a hundred times this value.By multiplying the intensity by two variables, Q and N, a more accurate “damage done” unit is derived, the sievert(Sv), which is a hundred times the rem.
In radiation exposures ranging from about one sievert to two sieverts, permanent effects, or mild radiation poisoning, begin. A feeling of general illness persists for a week or two.t six sieverts, the death rate is 90%, which increases quickly to 100%. The primary causes of death are internal bleeding or immune system failure that rapidly gives way to lethal infection. Hair is lost, people are rendered sterile, bone marrow is destroyed, and recovery can take years and may never be complete.
High doses of more than 100 gray affect the central nervous system, resulting in loss of coordination (including breathing problems), with death occurring within 1 or 2 days. Doses from 9 to 100 grays damage the gastrointestinal tract, causing nausea, vomiting, and diarrhea. Progressive dehydration can result in death within several weeks. Lower doses (from 3 to 9 grays) damage the bone marrow and other haematopoietic tissues. This can lead to loss of appetite and hair, hemorrhaging, inflammation, and secondary infections such as pneumonia. These effects are also found in patients undergoing radiation therapy. Doses of less than 3 grays are rarely lethal, but cause symptoms that include loss of appetite and hair, hemorrhaging, and diarrhea.
Long-term risks of radiation exposure center on the incidence of cancer and genetic mutations. Both effects have proven difficult to determine since cigarette smoking, diet, and sunlight exposure are also known to cause cancer and possibly to promote genetic mutations. Analysis of approximately 100,000 survivors of Hiroshima and Nagasaki shows a slight increase in genetic mutations over what would be expected for a normal population, but this increase is so small that it may not be statistically significant. Hiroshima survivors who received more than 2 gray showed a slight increase in the instances of cancer over a normal population. There is a good deal of controversy over the contribution of natural background radiation and man-made radiation to the incidence of cancer in humans. The dosage threshold below which radiation has no effect is also controversial.
Background radiation comes from three sources: cosmic rays, naturally occurring radioactive elements such as radon-222, and solar radiation. The amount of exposure to this natural radiation depends on a number of factors, such as geographic location, house construction materials, medical treatments, and occupation. The average exposure for a U.S. resident is 0.36 rem per year.