The greater part of the radiation we receive comes from natural sources, mostly, natural radio-nuclides contained in the lithosphere, construction materials, air, food and water as well as cosmic rays. They constitute over 80% of the annual effective dose we receive as a result of internal irradiation.

Radiation is one of the most ancient natural factors. The average natural radiation makes up 2.2 mSv a year, but in calculating natural radiation we should know that background irradiation is widely variant. In different regions of the Earth the annual natural irradiation dose ranges within 1-10 mSv, but somewhere it is 10-20 mSv and even more. In Europe the natural irradiation dose is higher than in Russia. Our organism is not only prepared for radiation impacts; in fact, it has been shaped by them. Observations of the population of the regions with higher-than-average  natural radiation background have detected no deviations in their health. The radiation dosage structure in Russia is similar to that worldwide with the natural background and radiation-related medical procedures constituting the greater part of the dose. 

Indeed, the latest reports of the UN Scientific Committee on Atomic Radiation show that the share of medical irradiation in the total anthropogenic irradiation is constantly growing and makes up an average of 50% in developed countries.

In contrast with various types of voluntary risks (alcohol, smoking), there are so-called forced risks, which are caused mostly by regular effects of harmful emissions of chemical, metallurgical, power and other industries.

Just like the other types of industrial risks, the radiation risk may have a negative impact on human health. Since it is impossible to ensure absolute safety, the world community has decided to set admissible risk levels that allow it to attain balance between the negative consequences and the profit of a specific activity.

The level of risk that ensures maximum profit when losses and expenses are excluded can be conventionally called admissible. The problem of admissible risk has social, economic, psychological and other aspects.

The psychological aspect of the admissible risk is the attitude of the public to the industrial risk as such. People generally accept the risks related to conventional industries – even though sometimes they are concerned over them - but they almost always reject new risks even if they are much lower than the conventional ones. The inadequate public reaction to the recent plans of nuclear energy development was a vivid example of that.

The assessment of various types of risk allows to outline the range of lethal risk changes.

Obviously, the level of lethal risk may range within 10 –9-10 –2 per capita a year. The minimum risk 10- characterizes events happening in natural human environment and claiming several dozens of lives worldwide a year. The lethal risk 10 –  is related to dangerous professions (miners) and age peculiarities.

In considering the prospects of nuclear energy development, one should compare the effects of radiation and non-radiation factors on the personnel and the population. This analysis should be based on the assessment of electricity production risks and their comparison with natural risks.

Even though nuclear fuel and coal have almost equal shares in the present-day energy balance of Russia, the risks of their respective productions (the number of disabled workers per year) differ by hundreds of times. Nuclear fuel is the safest of all.

The effect of radiation on human health has been studied for over 100 years already. Small doses (less than 100 mSv) have no negative impact on individuals and populations. Even though there are no clear proofs that radiation doses of 100-200 mSv are harmful, Russia has set a very tough personnel irradiation standard – 20 mSv a year. This standard is based on the hypothesis of linear nonthreshold effect of small doses, which says that even very small doses may have effects on human health in the course of time. Though very tough on radiation, the existing ecological and human health laws set unreasonably high admissible levels for chemical pollutants – even though the carcinogenic risk of toxicants within the maximum admissible concentration is 100 times higher than that of many-year radiation exposure of 1 mSv a year.

The existing system of radiation monitoring detects changes that are millions of times smaller than the admissible level, while the control of toxic emissions starts from their maximum admissible level. In the areas near big oil refineries and metallurgical enterprises the air pollution levels are several times higher than the maximum limit. 

It should be noted that radiation safety experts are not unanimous as to whether small radiation doses actually have negative effect on human health. Even if the linear nonthreshold concept is true, it is very hard to detect the negative impacts of small doses. Many big scientists believe that radiation is not dangerous below the threshold level (almost 100 mSv).