What effect does radiation have on human body?

Influence of radiation on human body 1 Ionizing radiation acting on human body Ionizing radiation acting on human body can be divided into two categories: natural radiation and artificial radiation. Ionizing radiation from natural radiation sources is called natural radiation; Ionizing radiation produced by artificial radiation sources or processed natural radiation sources is called artificial radiation 1. 1. Natural radiation can be divided into two categories: normal background radiation from natural radiation sources (natural background radiation) and natural radiation changed due to the development of industrial technology. It is the biggest radiation source of mankind. 1. 1. 1 natural background irradiation Natural background irradiation is divided into internal irradiation and external irradiation according to the irradiation of internal irradiation source and external irradiation source. External irradiation comes from cosmic rays outside the earth and natural radionuclides of the earth itself, that is, the earth radiation caused by α, β and γ rays released by the decay of natural radionuclides existing in the crust, buildings and air. Internal irradiation is caused by radioactive nuclides in the environment entering the human body through ingestion and inhalation. Radionuclides irradiated internally include cosmogenic radionuclides (generated by the interaction of cosmic rays with the nuclei of the atmosphere and the earth's surface), such as 3 H, 7 Be, 14 C and 22 Na, and primary radionuclides (long-lived radionuclides inherent in the earth itself), such as 40 K, 87 Rb, 238 U and 232 Th. According to the estimation of the United Nations Scientific Committee on the Effects of Atomic Radiation, the annual effective dose equivalent of natural radiation sources in the normal background radiation area is about 2.4mSv, of which the effective dose equivalent caused by internal irradiation is about twice that caused by external irradiation, of which 222 Rn is the most important, about 1.3 msv, and 40 K is about 0.2 msv In external irradiation, cosmic rays are about 0.4 msv., The ground radiation is about 0.5mSv. 1. 1.2 natural radiation with the development of industrial technology, today's human beings will be exposed to more and more natural radiation, which can be increased or decreased. With the development of industrial technology, the natural radiation increases, which refers to the exposure of natural radiation sources caused by activities of industrial technology that are not specially designed to produce radiation, such as traveling by plane and the exposure of emissions from coal-fired power plants to surrounding residents. Some industrial activities can also reduce natural exposure. For example, drinking surface water purified to reduce the concentration of radium and other natural radionuclides. The natural radiation caused by the above-mentioned industrial technology development and changes is very small, which has no obvious influence on the global collective effective dose, but the dose of exposed personnel can be increased in local areas or abnormal circumstances. 1.2 artificial radiation In addition to natural radiation, human beings are often exposed to various artificial radiation. At present, the main artificial radiation sources in the world include nuclear explosion, artificial radiation sources produced in nuclear energy production or processed natural radiation sources, as well as radiation sources used for medical irradiation and consumer goods. 1.2. 1 nuclear explosion Atmospheric nuclear explosion has the greatest impact on residents. The radiation caused by radioactive fallout from nuclear explosion can be caused by inhaling radionuclides in the surface air and eating radioactive contaminated food, or by external irradiation caused by radionuclides in the surface air or radionuclides deposited on the ground. However, the main way for nuclear explosion products to enter the human body is ingestion. The main nuclides are 14 C, 137 Cs and 90 Sr, followed by external irradiation. The main nuclides are 137 Cs and some short-lived radionuclides. 1.2.2 nuclear energy production nuclear energy production includes uranium mining, ore processing, uranium fuel production, reactor power generation, fuel reprocessing, transportation of radioactive materials between production departments and final disposal of radioactive waste. Up to now, the total collective effective dose equivalent burden of nuclear energy production on workers and residents is equivalent to 1 day natural background radiation. By 2500, the per capita annual effective dose equivalent caused by nuclear power production is estimated to be equivalent to 1% of natural background radiation. 1.2.3 medical irradiation various ionizing radiation and radionuclides have been widely used in medical diagnosis and treatment, mainly including radiotherapy, nuclear medicine and medical X-ray diagnosis. At present, medical radiation is the largest artificial radiation source for human beings. 1.2.4 other artificial radiation here mainly refers to artificial radiation in consumer goods, which is doped with radionuclides or can emit x-rays. These radioactive consumer goods include radioactive products containing radionuclides such as 226 Ra, 147 Pm, 3 H, such as watches and clocks, electrons and electronic devices containing radioactive substances or emitting X-rays due to electron deceleration, electrostatic eliminators containing radioactive substances, smoke detectors, etc. 2 The influence of radiation on human body The radiation exposure to human body can be divided into two categories: internal exposure and external exposure. The radiation from the radiation source that enters the human body is called internal irradiation, while the radiation from the external radiation source is called external irradiation. Both internal and external irradiation may have a certain impact on human health. 2. 1 Classification of radiation effects After the human body is irradiated by ionizing radiation, the effects of radiation on the human body can appear on the irradiated person or their descendants. What appears on the subject itself is called the body effect; What happens to the offspring of people who are exposed to radiation is called genetic effect. In the publication No.26 of the National Radiation Protection Committee, these effects are divided into random effects and non-random effects (now called deterministic effects). Random effect refers to the effect whose occurrence probability (rather than severity) has nothing to do with dose, and this effect has no dose threshold. Deterministic effect refers to the effect whose severity changes with dose. This effect has a dose threshold below which no harmful effect will occur. The genetic and physical effects of cancer are random. For the purpose of protection, it is assumed that there is a linear relationship between the incidence of random effect and dose under low level irradiation. That is, the incidence rate is proportional to the dose, which means that even a small dose may cause damage to the human body, but the probability of occurrence is very small. Deterministic somatic effects are manifested as changes in body functions, such as cataract formation, benign skin injury, cytopenia in bone marrow, decreased fertility, vascular or connective tissue injury, etc. These effects will not be shown in future generations, so they are not genetic effects. The severity of the deterministic effect (the severity of the disease) depends on the dose, that is, it will only happen when the dose received by the body exceeds a certain threshold. For example, the threshold dose equivalent of lens opacity will not be lower than 1.5 msv( 1.500 ram), and the threshold dose of skin injury cosmetic is 20gy(2000 rad) received locally within several weeks or months. 2.2 Mechanism of radiation damage The mechanism of ionizing radiation causing these effects is complex and has not been fully studied. Some people think that human cells contain a lot of water, and ionizing radiation can ionize water molecules and form harmful substances such as free radicals (H, OH) and hydrogen peroxide. The chemical properties of free radicals are very active, and hydrogen peroxide is a strong oxidant. They react with sulfhydryl groups and other important compounds in cells, causing cell damage. A large number of studies have also proved that ionizing radiation can directly break chromosomes or other important components in cells, thus causing abnormal cells to appear. If the injured cell is a somatic cell, it shows a somatic effect; If the germ cells are damaged, the radiation effect will be manifested in the offspring of the irradiated people, and the relationship between genetic effect 2.3 and effect. Deterministic somatic effects have a threshold dose. When the exposure dose exceeds a certain threshold, it will cause some effects of acute injury, and the exposed person will have corresponding symptoms. Table 1 gives the possible symptoms caused by high-dose whole body irradiation. Table 1 symptoms caused by high-dose whole body irradiation ~ 25 symptoms can be treated without obvious conscious symptoms, 25 ~ 50 people feel mild nausea and fatigue as appropriate, and hematological examination changes increase nutrition. It needs to be observed that 50 ~ 100 people have mild and temporary nausea, fatigue and vomiting. Reduce working energy, increase nutrition, pay attention to rest, and you can recover yourself. 100 ~ 150 Some people have nausea, vomiting, loss of appetite, dizziness and fatigue, and a few people have obvious symptoms of temporary loss of work ability. Should be given 150 ~ 200 symptomatic treatment. Half of them have nausea, vomiting, loss of appetite, dizziness and fatigue, and a few people have serious symptoms. Half of the staff lost their ability to work within a period of time, most of them needed symptomatic treatment, some needed hospitalization, most of them had the above symptoms, many of them were serious, and a few of them might die and need hospitalization. All of them have the above symptoms, and the mortality rate is about 50%, which requires hospitalization. The mortality rate depends on the enthusiasm for treatment. Generally, 65,438+0,000% of deaths will be rescued as much as possible, which may be effective for individuals. Dosage in Table 65,438+0 refers to the effect produced when the whole body is irradiated once (for example, within one day), and the effect should be completely different when it is irradiated in batches or locally. Practice tells us that many factors, such as the type of radiation, total dose, dose rate, irradiation mode (irradiation area and location), physiological state of the body (age and health status) and so on. ) and medical conditions after irradiation can directly affect the severity and incidence of injury. But the main factors are total dose, dose rate and irradiation mode.