5.2.7Nuclear Physics

Dangers of Radiation — Cambridge IGCSE Physics 0625 Revision Notes & Topical Questions

5 min read 10 parts Lesson 17 of 17 1 quiz

📚 Cambridge IGCSE Physics 0625 Hub / Topical Revision

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Lesson summary

5.2.7 Dangers of Radiation — IGCSE PHYSICS notes: Explain how ionising radiation harms living cells and describe safety precautions for handling, storing and disposing of radioactive materials.Ionisation — ionising radiation (alpha, beta, gamma and X-rays) removes electrons from …

DNA damage
Cell death
Damage depends on dose
Skin burns
White blood cells
Radiation sickness and hair loss

Part 1 of 8How radiation harms cells

Ionisation

Ionisation ionising radiation removes electrons from atoms and molecules in living cells.
- (alpha, beta, gamma and X-rays)

DNA damage

DNA damage if the atoms of a DNA strand are ionised, the strand can be damaged.

Cell death

Cell death a damaged cell may die.

Mutation

Mutation damaged DNA may be mutated when the cell replicates, and sometimes the cell repairs the DNA incorrectly.

Cancer

Cancer if a mutated cell replicates, a tumour may develop.

Damage depends on dose

Damage depends on dose harm increases with the dose and the sensitivity of the tissue,
- and rapidly dividing cells such as bone marrow and embryos are most at risk.

Part 2 of 8Acute exposure

1Skin burns

Skin burns similar to severe sunburn.

2White blood cells

White blood cells radiation reduces their number, which weakens the immune system and makes infection more likely.

3Radiation sickness and hair loss

Radiation sickness and hair loss occur at high doses.

4Delayed effects

Delayed effects a small dose may raise the chance of cancer many years later.

Part 3 of 8Source outside and inside the body

Position	Alpha	Beta	Gamma
Outside the body	Stopped by the dead outer layer of skin, so not very dangerous	Penetrates the skin and can cause burns	Passes through the body and can damage organs
Inside the body	Most dangerous, since all its energy is deposited in a very small region of tissue	Less dangerous, since more energy leaves the body	Less dangerous, since more energy leaves the body

Radon
- an alpha emitter that can be inhaled, so it is a health risk in poorly ventilated buildings.

Part 4 of 8Safe handling of sources

Storage

Storage keep sources in lead-lined boxes, at a distance from people, locked away and labelled with the radiation hazard sign.

Time

Time handle sources for as little time as possible and return them to their boxes immediately after use.

Distance

Distance keep every person as far from the source as possible and handle it at arm's length using tongs.

Monitoring

Monitoring workers wear dosimeter (film) badges that measure the dose.

Hygiene

Hygiene wash hands after use and record the date and time of use.

Part 5 of 8Safety precautions (Extended)

Reduce exposure time

Reduce exposure time limiting time near a source reduces the dose received.

Increase distance

Increase distance the radiation spreads out, so the dose falls greatly with distance.
Remote nuclear power plants and buried waste also increase the distance to people.

Use shielding

Use shielding a barrier of lead, water or concrete absorbs the radiation.
Radiographers stand behind a barrier or leave the room during X-rays, and the area around the image is shielded.

Dose

Dose the radiation received is called the dose and is measured in sieverts (Sv).
One sievert is a very large dose that would cause acute radiation poisoning.

Part 6 of 8Transport and waste

Transport

Transport used nuclear fuel moves in special casks that withstand fire, cold and submersion in water.

Long half-life

Long half-life a source with a long half-life decays slowly, so it stays a contamination risk for a very long time.

High-level waste

High-level waste sealed in glass, stored in steel containers and buried deep underground in stable rock.

Low-level waste

Low-level waste items such as contaminated clothing are stored at safe sites until they decay.

Part 7 of 8Irradiation and contamination

Irradiation

Irradiation exposure to radiation from outside, which stops when the source is removed or the person moves away.

Contamination

Contamination radioactive material on or in an object or person, which keeps irradiating them.

Becoming radioactive

Becoming radioactive an irradiated person does not become radioactive, but a contaminated one has radioactive material on or in them.

Risk and benefit

Risk and benefit uses of radiation are accepted when the benefit is greater, with exposure kept as low as reasonably practicable.

Part 8 of 8More from the specification

Key terms

Term	Meaning
Dose	Amount of radiation received by a person, measured in sieverts.
Sievert (Sv)	Unit of radiation dose.
Shielding	Barrier that absorbs radiation.
Contamination	Radioactive material on or inside an object or person.
Irradiation	Exposure to radiation from an outside source.
Mutation	Change in the DNA of a cell.

Avoid these mistakes

Saying alpha sources are harmless in all situations — they are very dangerous inside the body.

Thinking radiation makes you radioactive — only contamination does.

Forgetting that high doses of gamma from outside the body can be dangerous.

Using only lead as protection for alpha sources when paper is enough.

Last updated: 15 October 2026