Why radioactive substances can cause people with to death?

Radioactive metals mainly refers to the uranium-radium, thorium and actinium system and other metals with radioactivity (the periodic table of the elements of the bottom two rows of a lot of), can radiate rays that can not be seen by the human eye, the hazards of radioactive metals is that these rays are caused by the human body, which can be a serious harm.

In large doses of irradiation, radioactivity on the human body and animals there is some kind of damage effect. For example, in the 400rad irradiation, 5% of the irradiated people died; if irradiation 650rad, then 100% of the people died. If the dose of exposure is below 150 rad, the mortality rate is zero, but it is not harmless, and it takes 20 years for some symptoms to show up. Radioactivity can also damage the genetic material, mainly in the cause of gene mutation and chromosome aberrations, so that one generation or even several generations of victims.

Radioactive substances have three forms of decay: alpha, beta and gamma. Three kinds of decay characteristics are different, the degree of harm to the human body is different. One of the α ray of internal irradiation is the most harmful, because of its short range, a piece of paper can be blocked. It can be concentrated in a small area of the human body for intense internal irradiation, so that a small area of muscle tissue to withstand a high concentration of radiation energy and cause damage. Such as in the respiratory organs of the alpha particles in the range just can bombard the bronchial epithelial basal cell nuclei, and cause serious respiratory diseases, and even lung cancer.

The harm of rays on the human body not only comes from the internal irradiation of alpha particles, but also from the external irradiation of beta, gamma and other rays.

According to the relevant data, young women in the pre-pregnancy diagnostic irradiation (0.7-5rad) after the child's Down?s syndrome 9 times more likely to occur. Low-dose irradiation is harmful to the human fetus.

In addition, radioactive radiation can also be induced by carcinogenic mechanism, there are two main hypotheses: "First, radiation-induced mutations in somatic cells, so that normal cells to malignant cells; second, radiation can make the cellular environment changes, which is conducive to the replication of viruses and viruses induced by malignant lesions.

In addition to the carcinogenic effects, the late effects of radiation also include aplastic anemia, shortened life expectancy, cataracts and abnormal retinal development.