6.1.5Radiation
Dangers of Radiation
5 min read 4 parts Lesson 5 of 14
Part 1 of 4How Radiation Harms Cells
The risk of harm depends on how much radiation is absorbed and on the type of radiation.
Ionisation in cells
- Ionising radiation can remove electrons from molecules inside cells, breaking chemical bonds and forming harmful free radicals.
DNA damage
- Damage to DNA can stop a cell working, kill it, or cause it to divide in an uncontrolled way.
Cancer
- If a damaged cell survives and multiplies abnormally it can form a tumour, so ionising radiation can cause cancer.
Repair
- Cells have repair mechanisms for low levels of damage, which is why small doses spread over time are less harmful.
Gametes
- Damage to reproductive cells may produce genetic mutations that are passed to children.
Part 2 of 4Effects of Exposure
Effects of Exposure
Large short-term dose
- Can cause radiation sickness, with symptoms such as nausea, hair loss, burns and a weakened immune system.
Very large dose
- Can damage so many cells that organs fail and death follows within days or weeks.
Long-term effects
- Smaller doses may raise the chance of cancers developing years later, even if no immediate symptoms are seen.
Chance effect
- The effects are probabilistica bigger dose increases the chance of harm, but does not make it certain.
Sensitive tissue
- Rapidly dividing cells, such as bone marrow and the lining of the gut, are especially vulnerable.
| Exposure | Typical outcome |
|---|---|
| Very high dose | Radiation sickness, possible death |
| Moderate dose | Burns, sickness, higher cancer risk |
| Low dose | Small increase in later cancer risk |
Part 3 of 4Reducing the Risk
1
Keep exposure time as short as possible, because the dose absorbed is proportional to the time spent near a source.
2
Increase the distance from the source, using tongs or remote handling, since radiation intensity falls with distance.
3
Use appropriate shielding, such as lead aprons and thick walls for X-rays and gamma rays.
4
Store sources in lead-lined containers, label them with the radiation hazard symbol and keep them locked away.
5
Monitor workers with dose badges so that doses can be recorded and compared with the legal limits.
Part 4 of 4Exam Checklist & Tips
6.1.5 – Key Points for the Exam
- DNA The molecule in cells that carries genetic information.
- Radiation sickness Illness resulting from a large dose of ionising radiation absorbed in a short time.
- Mutation A change in DNA that may lead to cancer or inherited effects.
- Shielding Material placed between a source and a person to absorb radiation.
- Dose badge A device worn by workers to record the radiation they absorb.
Common Mistakes
- Thinking all radiation, including visible light, is ionising and equally harmful.
- Believing that a person exposed to radiation becomes radioactive.
- Forgetting that alpha sources are most hazardous when taken inside the body.
- Stating that any dose will always cause cancer; the chance of harm rises with dose.