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| １．What's radiation? ２．Human effect of radiation ３．History of radiation |
２．Human effect of radiation
Why does radiation affect human?／Effect of background radiation
／Internal exposure and external exposure
／Have your opinion about effect of radiation／Risk of radiation exposure
| ◆Why does radiation affect human? |
It is needed why radiation affects human for understanding human effect of radiation.
adiation hurts mainly DNA of the cell. Then, the cells repair themselves but a part of cells sometimes become cancer cells. This is usually avoided by destroying themselves. Overexposure to radiation makes the cells become the cancer cells because of impossible to repair them and to destroy themselves perfectly.
Because of this, if you exposure radiation, exposure a small amount of radiation for long time may be safer than that of same amount of radiation for a moment.
| ◆Effect of background radiation |
Radiation affects human. But, you don’t have to worry.
We are exposed about 1.5 mSv radiation every year. If you are exposed 100 mSv, cancer incidence would grow. There is standard value for foods. So, you needn’t worry.
| The dose which causes increasing the number of people killed by cancer | 100mSv |
| The dose of background radiation that we’re exposed for a year (in Brazil) | 10mSv |
| The dose that we’re exposed in one CT | 6.9mSv |
| The dose that we’re exposed for a year (the global) | 2.4mSv |
| The dose that we’re exposed for a year (in Japan) | 1.5mSv |
| The dose that we’re exposed in one X-ray examination | 0.05mSv |
| ◆Internal exposure and external exposure |
External exposure is radiation exposure of outside of our body. For example, it is caused by radiation from the cosmos or earth. Internal exposure is radiation exposure of inside of our body. For example, it is caused by radiation from air or food. Two kinds of exposure show different influence.
External exposure
Alpha-ray and beta-ray are screened out by our skin because they have little penetrability. So, our skin is harmed and our internal organs aren’t harmed. Human effect is small.
Gamma-ray injures our viscera through our skin because it has a strong penetrability.Human effect is great.
Internal exposure
Alpha-ray and beta-ray have bad human effect because they often harm some organs. Gamma-ray has little human effect because it pass through our body and get out.
| ◆Have your opinion about effect of radiation |
We don’t know how radiation causes damage to us. In case of low level radiation, the opinions about cancer incidence are difference between some nations and some institutions.
nternational Commission on Radiological Protection;ICRP
They think cancer risk is in proportion to exposure dose.Academy of medical science in France
They think cancer risk grow from exposure over 100mSv (threshold).There is the idea which cancer risk reduce in case of low level exposure. It is called hormesis.
Have you ever heard that it is good for our health to take the radioactive spring?
This is because of radiation from radium.
provider：井尻憲一
| ◆Risk of radiation exposure |
If cancer risk is in proportion to exposure dose, our usual actions are expressed as follow.
Many people think that they don’t want to be exposed to radiation because they wouldn’t like to have a cancer.
The idea is right. But, some don’t care cancer risk, others worries about cancer risk.
We are always be exposed to radiation. We must get along with radiation.
| The action that one in 100 thousand people is killed in | |
| radiation exposure | 2mSv (it is the dose of background radiation about for 10 months) |
| driving car | 1000km |
| smoking | 30 times in your life |
| drinking | in case of drinking five wines |
| rock-climbing | for fifteen minutes |
| leaving of 60 years old | for 3 hours 20minutes |
provider：井尻憲一