Atoms with unstable nuclei are called isotopes. When unstable atomic nuclei decay, they produce radioactivity with high-energy particles (α and β radiation) or electromagnetic γ radiation.
At the latest since Chernobyl in 1986 and Fukushima in 2011, the general public has been aware that all three types of radiation may cause tissue damage in the human body.
While α and β rays have a very short penetration depth in the millimeter to centimeter range, the range of γ rays is almost unlimited. The energy of the three types of rays depends on the decaying isotope. In this process, radiation first causes the ionization of biological molecules and then their chemical modification. Depending on the radiation dose, two types of reaction of the human body can be distinguished:
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The acute radiation sickness occurs briefly at very high radiation exposure with doses of more than 1000 mSv (milli-Sievert).
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The carcinogenesis, on the other hand, is the result of a lower radiation exposure after years, after it has led to genetic mutation of the genome.
There are two types of exposure to high-energy radiation:
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The direct irradiation of the human body by an external radiation source: This includes natural environmental radiation of terrestrial and cosmic origin (about 1 to 3 mSv per year) and, to an increasing extent, radiation exposure in medical diagnostics and therapy (about 3 to 4 mSv).
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The incorporation of radioactive substances into the organs of the human body: this can occur through the food supply chain or during diagnostic procedures and therapy in nuclear medicine. How long the incorporated isotopes radiate depends on their half-life (physical half-life) on the one hand and their biochemical metabolism (biological half-life) on the other.
