The rapid increase in the scope of application of radioactive substances has made the problem of radioactive contamination increasingly prominent and a concern for mankind all over the world. On the earth where we live, there have long existed radioactive substances that expose our bodies to a certain dose of irradiation. This naturally occurring exposure is called natural radioactive background. There are three sources of natural radiation background: cosmic rays, each person receives about 35 millirems per year; radioactive elements in the soil, each person receives about 100 millirems per year; trace radioactive elements in humans and animals, each person receives about 35 millirems per year. Under natural conditions, each person receives about 170 millirems of natural radioactive elements per year.
The so-called radioactive pollution, refers to the use of artificial sources of radiation due to the pollution of the environment. Artificial sources of radiation, mainly medical ray sources, radioactive fallout from nuclear weapons tests, and various radioactive wastes discharged by the atomic energy industry.
The hazards of rays have two major categories: near-term effects and long-term effects. Atomic bomb explosion of high intensity and medical treatment of large doses of radiation, resulting in leukemia and various cancers, belong to the near-term effects. The commonly referred to radioactive contamination of the environment, refers to the long-term acceptance of low-dose radiation, causing chronic damage to the body of the long-term effects or potential effects. Such as long-term acceptance of low-dose radiation, will cause leukocytosis or reduction, lung cancer and reproductive system lesions, etc., can leave a few years, a decade or more after-effects, and even the physiological lesions inherited to future generations.
The source of radioactive contamination of the environment, medical rays accounted for 94% of artificial sources of pollution, accounting for 30% of the total amount of all rays.
Nuclear tests can cause radioactive fallout pollution. Nuclear tests, the atmosphere formed a lot of fissionable material fine particles, they have 10% to 20% per year landed on the ground. According to the British projections, nuclear testing, if the existing scale continues, 100 years later can reach 200 millicurie/kilometer 2 radiation levels. The radioactive fallout most closely associated with humans is strontium-90 and cesium-137, which increase the incidence of bone cancer and leukemia and have a significant impact on the reproductive glands.
The nuclear energy industry discharges all kinds of radioactive waste pollution of the sea, atomic energy equipment accidents, etc. are formed environmental pollution, bring harm to human beings.