Strålings effekt på celler og DNA skade

This image shows a beam of radiation breaking the double helix of a DNA strand resulting in DNA damage.

The primary way radiation affects our health is through breakage of DNA molecules. DNA consists of two long chains of nucleotides twisted together into a double helix; it is the molecular compound in the nucleus of a cell that forms the blueprint for the structure and function of the cell. Radiation is able to break these chains. When it does, three things can happen:

1) The DNA is repaired properly

In this case, the cell is repaired properly and it continues to function normally. DNA breakage occurs normally every second of the day and cells have a natural ability to repair that damage.

2) The DNA damage is so severe that the cell dies (deterministic effects)

When the DNA or other critical parts of a cell receive a very high dose of radiation, normally delivered over a short period of time, the cell may either die or be damaged beyond repair. If this kills a large enough number of cells in a tissue or organ, early radiation effects may occur. These are called deterministic effects and the severity of the effects varies according to the radiation dose received. They can include acute radiation syndrome, skin burns, loss of hair, and in extreme cases, death. Most deterministic effects occur shortly after exposure and above dose thresholds specific to each exposed tissue. The pattern of the symptoms for most of the effects is so specific that trained medical professionals can diagnose a deterministic effect of radiation.