Radioactivity and life. YK Kudrytski (MD) 1971 Part 10.

 radiation. To get the dose that causes the development of radiation sickness, it is necessary to 100-500 thousand times higher than the daily dose received by man from natural sources of ionizing radiation.
It is considered for human dose of 300-400 F for a single whole-body irradiation of semi-legal, that is causing the death of 50% of the irradiated and the dose of 600-700 p absolutely lethal when killed all irradiated.
The biological effect depends not only on dose but also on other conditions of radiation exposure. Among them are the most important are the distribution of radiation exposure, ie dose, time and space, meaning the last volume of the irradiated part of the body.
The biological effect of a large extent. Depends on the dose rate OR the total duration of exposure during multiple impacts. Increasing the radiation exposure at a fixed dose, usually leads to a decrease in biological effectiveness of ionizing radiation.
Indeed, people who are subject to the conditions of professional exposure to radiation, for 30 years of its activity may professionalpoy po.chuchit without any ssrezpyh violations in the health ca "tin 150 rubles, which corresponds to the modern sanitary regulations, deistvuyuschem in the Soviet Union. The same dose received a single dose neizbs / 1 (110 causes the development of radiation sickness. ..
Another example is the comparison moschposti dose poluchaemoi from natural sources of ionizing radiation, with doses of rec once moschnostyo absolutely deadly radiation. They otlichaYul> ~ from each other a billion times. The difference between the dose, poluchaemoi from natural sources of ionizing radiation, and capacity of the maximum permissible dose as high and more than the difference between these doses. Thus, the natural radiation dose rate of about 0.012 mR per hour and the maximum allowable - 3 mR per hour, is the last 250 times longer.
The distribution of exposure over time is not limited to changes in power. Dose. Considerable importance is the fraction or, as it is often referred to fractionated irradiation. The dependence of biological effect on the degree of dose fractionation on the merits has to per.vomu example the influence of dose rate, when. compared deistvie single exposure to 150 r and receiving the same dose over 30 years of professional life. This dose is the person podvergayup: Party or exposure to occupational conditions are kazhdyi working day for a few hours, that is fractional. On average, for 30 years, they can work through about 10,000 days. This means that the professionals dose of 150 p, obtained for 30 years, separated by at least 10,000 faction.
The distribution of radiation exposure over time, as shown by Moule (1959), influences and changes in the blood. With increasing duration of exposure at the same dose reduced the number of mice infected with leukemia.
. Very substantial dependence of the biological effect