7.6 - Why Radiation Is Harmful

How ionising radiation damages living cells

• Ionising radiation enters living cells and ionises the atoms and molecules inside them.
• Removing electrons damages or destroys these molecules, which damages the cell.
• The amount of harm depends on the radiation dose.

Lower dose - Mutation and cancer

• A lower dose tends to cause minor damage without killing the cell.
• This damage can mutate the cell's DNA.
• A mutated cell may divide uncontrollably, leading to cancer.

Higher dose - Radiation sickness

• A higher dose kills cells outright.
• Killing a large number of cells at once causes radiation sickness, with symptoms such as vomiting, tiredness and hair loss.
• Very high doses can be fatal.

Ionising power

• The more ionising the radiation, the more damage it causes to cells.
• Most to least ionising: alpha → beta → gamma.