With the development of human civilization and the advancement of science, the issue of radiation is receiving more and more attention. What cosmic rays, nuclear power plant radiation, electrical radiation, cell phone radiation, as well as from the soil, water, food within the radioactive material, and even the human body of potassium will produce radiation, and so on. Radiation from many sources seems to weave an invisible "giant network of radiation", tightly encircling human beings. However, people can not eat, drink, use or enjoy life because they are afraid of radiation. Therefore, how much radiation dose will cause harm to human health, this is the people want to know urgently, but also scientists from all over the world dream to want to solve the problem.
At the mention of radiation, people may be the first thought of nuclear radiation, Hiroshima, Nagasaki atomic bombings have caused hundreds of thousands of deaths; Chernobyl nuclear leakage accident has also become a shocking tragedy in the world. In daily life, people are most worried about the radiation of electrical appliances, such as: computers, photocopiers, telephones, TVs, cell phones, etc. will not be harmful to the user?
In fact, the biggest radiation hazard facing mankind is from nature, that is, from the sky, the ground and the surrounding environment of people's daily lives. According to U.S. scientists, the average person in the U.S. receives 350 millirems of radiation from nature each year, including 40 millirems from cosmic rays alone.
John Boyce, director of the International Epidemiologic Institute in Maryland, said, "What we eat, drink and breathe is low in radiation." Fred Manteler, chairman of the Department of Radiology at the University of New Mexico School of Medicine, also said that when you examine the population exposed to radiation, you find that about two-thirds of the people victimized by radiation from natural backgrounds, and 15 percent due to medical equipment used by doctors. The impact of other factors is very small, and the proportion of radiation coming from nuclear reactors and research institutions is not even a few percent.