The document indicates that ionizing radiation from natural sources, such as radon, thoron, cosmic rays, as well as natural radionuclides in soil and food, constitutes the major part of population exposure. In contrast, the contribution from anthropogenic sources is significantly lower, except in cases of serious nuclear or radiological incidents.
Global Analysis
The findings are presented in the latest scientific annex of UNSCEAR titled "Assessment of Radiation Exposure of the Population from Ionizing Radiation." This is the most comprehensive analysis to date of the radiation burden on humans from both natural and anthropogenic sources. The report is based on data from a global study covering the period from 2007 to 2022.According to the committee's estimates, the average global annual dose of radiation from natural sources is approximately 3.0 millisieverts (mSv). The largest contribution to this dose comes from the inhalation of radon, thoron, and their decay products, amounting to about 1.8 mSv per year. This is followed by the intake of radionuclides from food and water (0.5 mSv), external exposure from radionuclides in the Earth's crust (0.4 mSv), and cosmic radiation (0.3 mSv).
This new figure exceeds the previous estimate published in 2008, which was 2.4 mSv. However, UNSCEAR notes that the increase is related to improved data access and research methodology, rather than a real rise in background radiation.
"The new assessment provides a more accurate and representative picture of the radiation doses that people receive in their daily lives," comments UNSCEAR Chair Dr. Sara Baatut. "With better quality data and advancements in science, we can more accurately assess the level of population exposure and support efforts to ensure health protection at national and international levels."
Impact of Anthropogenic Sources
The report also emphasizes that the contribution of anthropogenic sources, including medical, industrial, and scientific applications of radiation technologies, under normal operating conditions typically amounts to only a few microsieverts per year.Radiation doses for populations living near nuclear power plants remain extremely low and usually do not exceed tens of microsieverts per year. The effective dose per unit of electricity generated is about 0.4 person-sieverts per gigawatt-year.
Radiation Reduction in Testing Areas
Radiation exposure in areas of former nuclear testing has significantly decreased. While the radiation levels were high immediately after the tests, annual doses at the sites in New Mexico, the Marshall Islands, Mururoa, and Fangataufa, as well as in Semipalatinsk, are now generally significantly lower than the natural background.Consequences of the Chernobyl and Fukushima Accidents
Radiation exposure levels associated with the Chernobyl and Fukushima nuclear accidents continue to decrease due to radioactive decay, natural processes, and decontamination measures. Currently, annual doses in the vicinity of Chernobyl range from tens of microsieverts to several millisieverts, while in non-evacuated municipalities near Fukushima, they range from a few microsieverts to about 0.3 mSv.The UNSCEAR report aims to provide governments and international organizations with relevant scientific data for developing policies in the field of radiation protection and public health.
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