What Is Radioactive Contamination?

Some of the elements in nature and artificial production can decay automatically and emit rays invisible to the naked eye. These elements are collectively referred to as radioactive elements or radioactive materials. In the natural state, the rays from the universe and the radioactive elements of the earth's environment generally do not cause harm to living things. Since the 1950s, human activities have greatly increased artificial radiation and artificial radioactive materials, and the intensity of radiation in the environment has increased accordingly. The survival of crisis organisms has resulted in radioactive pollution. Radioactive pollution is difficult to eliminate, and the intensity of radiation can only weaken over time.

There are trace amounts of radioactive materials in natural foods, which are generally harmless or have little effect on people. Under special circumstances, radioactive elements may be contaminated by food through animal or plant enrichment, which is harmful to human health. Radioactive materials are widely distributed in nature and exist in ore, soil, natural water, the atmosphere, and animal and plant tissues. Since nuclides can participate in the process of transfer and absorption between the environment and organisms, they can enter the biosphere by sudden transfer to plants and become one of the components of animal and plant tissues ^[1] .

Introduction to radioactive pollution

Radioactive material or radiation that exceeds the national standards on the surface or inside of materials, human bodies, places, and environmental media due to human activities.

The harm of radioactivity to living things is very serious. Radiation injury has acute injury and chronic injury. If a person is exposed to large doses of whole body X-rays, gamma rays and neutrons in a short period of time, acute injuries will occur. Mild persons have symptoms such as hair loss and infection. When the dose is larger, gastrointestinal damage such as diarrhea and vomiting occurs. Under extremely high doses of radiation, CNS damage occurs until death.

For the central nervous system, symptoms include weakness, lethargy, anorexia, collapse, and lethargy. In severe cases, systemic muscle tremors cause epilepsy-like spasms. The small intestine with a strong cell division is highly sensitive to ionizing radiation. If it is irradiated, epithelial cell division is inhibited and it will quickly cause lymphoid tissue destruction.

"Beware of Ionizing Radiation" sign Radiation can cause changes in the chromosomes of lymphocytes. In chromosomal abnormalities, dicentrics and centromeres are used to estimate the radiation dose. Chronic injury after radiation exposure can increase the incidence of leukemia and various cancers in the population.

The phenomenon that the nucleus of a radioactive element emits , , and rays during the decay process is commonly called radioactivity. The pollution caused by radioactive materials is called radioactive pollution. The sources of radioactive pollution are: radioactive waste discharged from the atomic energy industry, sediments from nuclear weapon tests, and waste water, waste gas, and waste residues containing radioactive materials discharged from medical and scientific research.

Radioactive materials in the environment can enter the human body through a variety of ways. The radiation they emit can destroy the macromolecular structure in the body, and even directly damage the cell and tissue structures, causing damage to the human body. High-intensity radiation can burn the skin, cause leukemia and various cancers, destroy human reproductive skills, and severely cause death in a short time. A small amount of cumulative exposure can cause chronic radiation sickness, which damages the hematopoietic organs, the cardiovascular system, the endocrine system, and the nervous system. The onset process often lasts for decades. ^[2]

Radioactive pollution source

Waste from radioactively polluting atomic energy industry

In the atomic energy industry, the refining and refining of nuclear fuels and the manufacture of nuclear fuel components all have radioactive waste and waste water and exhaust emissions. These radioactive "three wastes" may cause pollution, and the corresponding safety protection measures have been adopted due to the operation of the atomic energy industrial production process. "Three wastes" emissions are also strictly controlled, so the pollution to the environment is not very serious. However, when an accident occurs in an atomic power plant, its pollution is quite serious. There are examples abroad where a nuclear power plant has been forced to close due to a breakdown.

Radioactive contaminated sediment from nuclear weapons tests

When conducting atmospheric, ground or underground nuclear tests, the radioactive materials discharged into the atmosphere are combined with airborne dust and settle on the earth's surface due to gravity or the erosion of rain and snow. These materials are called radioactive sediments or radioactive dust . The spread of radioactive sediments is very large, it can often settle to the entire earth's surface, and the settlement is very slow. It usually takes months or even years to fall to the atmospheric troposphere or the ground, and the decay takes hundreds or even tens of thousands of years. In 1945, the United States dropped two atomic bombs in Hiroshima and Nagasaki, Japan, killing hundreds of thousands of people, and a large number of survivors were tortured by radiation sickness.

Radioactive contamination

During the medical examination and diagnosis, the patient's body is exposed to a certain dose of radiation. For example, a lung x-ray is performed and a dose of (4-20) × 0.0001Sv is received (1sv is equivalent to 0.001J per gram of substance absorbed) Energy), a stomach fluoroscopy was performed, and a dose of about 0.015-0.03 SV was received.

Radioactive pollution

Radioactive materials are widely used in scientific research. In addition to the research units using atomic energy, research departments such as metal smelting, automatic control, biological engineering, and metrology have almost all involved radiological issues and tests. Radioactive contamination is possible in these research efforts.

The characteristics of radioactive pollution: 1. The toxicity of most radionuclides is higher than that of general chemical poisons based on the weight of the toxin. 2. According to the effects of radiation damage, it may affect heredity and bring hidden dangers to offspring. 3. The size of the radioactive dose can only be detected by a radiation detector, which can be known by non-human sensory organs. 4. The secondary ray has penetrability, especially r-ray can penetrate a certain thickness of the barrier layer. 5. Radionuclide has the ability to degenerate. 6. Radioactivity can only be reduced by natural decay.

Sources and hazards of radioactive pollution

There are three main ways radioactive materials enter the body: respiratory tract entry, digestive tract ingestion, and skin or mucosal invasion.

Radioactive material enters the body mainly through the digestive tract, but smaller through the respiratory tract and skin. In nuclear tests and nuclear industry leakage accidents, radioactive materials can enter the human body through the three ways of the digestive tract, respiratory tract and skin and cause harm ^[1] .

(1) Respiratory inhalation

The degree of absorption of radioactive material inhaled from the respiratory tract is related to the nature and state of its gaseous material. Poorly soluble aerosols absorb slowly and are more soluble; the larger the aerosol particle size, the less it deposits in the lungs. After being absorbed by the alveolar membrane, the aerosol can directly enter the bloodstream and flow to the whole body.

(2) Digestive tract ingestion

Digestive tract ingestion is an important way for radioactive materials to enter the body. Radioactive materials can be directly ingested by the human body, or can enter the body through the food chain through the organism.

(3) skin or mucosal invasion

The skin's ability to absorb radioactive materials fluctuates widely, generally around 1% to 1.2%. Radioactive pollutants that penetrate through the skin can be transported directly to the body with the blood. Radioactive material entering from wounds has a high absorption rate.

No matter which way, after entering the human body, radioactive material will be selectively positioned in one or several organs or tissues, which is called "selection"

Selective distribution. Among them, the localized organ is called a critical organ and will be exposed to a certain amount of radioactivity and the possibility of damage is greater, such as

Radon can cause lung cancer. The distribution of radioactive material in the human body is related to its physical and chemical properties, the way into the human body, and the physiological state of the body. However, some radioactive distributions in the body are non-specific, and are widely distributed in various tissues and organs. They are called "uniform distribution throughout the body". After the nuclide of nutritional analogues enter the human body, they will participate in the metabolic process of the body and spread throughout the body. ^[3]

After radioactive materials enter the human body, they have to go through four different stages of radiation: physics, physical chemistry, chemistry, and biology. When the human body absorbs radiant energy, it first changes at the molecular level, causing ionization and excitation of molecules, especially damage to large molecules. Some occur momentarily, and some require physical, chemical, and biological magnification to show the visible damage of the tissues and organs that are caused. Therefore, it takes a long time, even after several years of delay.

The harm to human body mainly includes three aspects:

(1) Direct damage

Radioactive material directly ionizes the atoms or molecules of the body material, and destroys some large molecules in the body such as DNA, ribonucleic acid, protein molecules and some important enzymes.

(2) Indirect damage

Various kinds of radiation first ionize water molecules that are widely present in the body to produce highly active H +, OH-, and molecular products, etc., and then they interact with the organic components of the body to produce the same results as direct damage.

(3) Long-term effects

It mainly includes radiation-induced carcinogenesis, leukemia, cataract, shortened life span and other genetic damage. According to relevant information, young women are 9 times more likely to develop Downs syndrome in their children after diagnostic exposure before pregnancy. For another example, pregnant women who were irradiated by the atomic bombs in Hiroshima and Nagasaki gave birth to mentally handicapped children. According to research from medical authorities, the proportion of children born to pregnant women diagnosed with radiation has increased as a child. ^[3]

The radioactive material entering the human body continues to emit various rays in the human body to cause internal radiation. When the effective dose received is small, the physical damage is not obvious, mainly manifested by an increased risk of cancer. It should be noted that there is absolutely no need to worry about the very low radioactivity naturally present in food. In recent years, some experts believe that low-dose irradiation is not only harmless to the human body but also has certain benefits, the so-called excitatory effect ^[1] .