What are the effects of ionising radiation?

When ionising radiation hits a cell, the radiation energy is taken up (absorbed) by the molecules of the cell. This energy can eject electrons from molecules (ionisation) or break molecular bonds. The resulting molecular types (radicals) are highly reactive chemically and can be electrically charged or neutral. These radicals react with other molecules inside the cell, which may, directly or indirectly, lead to cell damage. In most cases, water molecules are affected. However, other substances inside the cell can also be affected, such as proteins and DNA (carriers of genetic information).

For the long-term effects on the organism the alterations of the DNA are particularly important.

The effects of radiation on the cell

In general, the cell can repair radiation damage, so no biological effects are observed. However, if the cell is unable to repair the damage, it usually dies by targeted programmed cell death (apoptosis). In the case of severe damage from radiation exposure at very high doses, the cell dies uncontrollably (necrosis). If a faulty or insufficient repair occurs, genetically altered (mutated) cells that can also replicate may develop.

The effects of radiation on the organism

If and to what extent radiation exposure leads to health damage depends on the absorbed radiation dose, the type of radiation, and the organ or body tissue primarily affected. Radiation damage may also be caused by ionising radiation from natural sources (such as radon).

As a reference, For people living in Germany, the dose from natural sources is about 2 to 3 millisieverts per year on average.

A distinction is generally made between deterministic and stochastic radiation effects.