Hazardous Effects Of Radiation

Section 1 of 8How radiation harms the body

1Atoms are ionised

• Atoms are ionised Ionising radiation strips electrons from atoms and breaks up molecules in cells.

2DNA is altered

• DNA is altered Damage to the DNA inside a cell can change genes, which is a mutation.

3Cells lose control

• Cells lose control A mutated cell may divide in an uncontrolled way.

4Cancer may develop

• Cancer may develop A group of such cells forms a tumour, and cancer can result.

Section 2 of 8Ultraviolet and other ionising sources

Ultraviolet effects

• Ultraviolet effects Too much UV can cause sunburn and blistering, skin cancer, early skin ageing and eye damage including cataracts.

Other hazards

• Other hazards X-rays, gamma rays, alpha particles and beta particles can all harm tissue.

What decides the damage

• What decides the damage The type of radiation and the size of the dose both matter.

A helpful use

• A helpful use Carefully aimed gamma rays can destroy cancer cells in radiotherapy.

Section 3 of 8Types of tumour

Feature	Benign tumour	Malignant tumour
Where it stays	Stays in one place, often inside a membrane	Invades nearby tissue
Spread	Does not spread to other organs	Cells travel in the blood to form secondary tumours
Danger	Usually less dangerous, though it may press on organs	Cancer; can be life threatening

Section 4 of 8Reducing the risk

1

Wear safety glasses and gloves when working with radioactive sources.

2

Pick sources up with tongs and never with bare hands.

3

Keep as far from the source as possible and never point it at anyone.

4

Use lead shielding or a lead-lined container to absorb radiation.

5

Take the source out of storage for the shortest time needed.

6

Radiation workers wear dosimeter badges that record their total exposure.

Section 5 of 8Short-term and long-term effects

Radiation exposure

Very high dose

• Very high dose Large doses received quickly can cause radiation sickness, burns, hair loss and, in extreme cases, death within days or weeks.

Low dose over years

• Low dose over years Small doses may cause no immediate symptoms but slightly raise the chance of developing cancer later in life.

Reproductive cells

• Reproductive cells Damage to the DNA in sperm or egg cells can be passed to children as a genetic mutation.

Rapidly dividing cells

• Rapidly dividing cells Cells that divide often,
  • such as skin and bone marrow, are most at risk because damaged DNA is copied before it can be repaired.

Section 6 of 8Balancing risk and benefit

Situation	Risk	Benefit
Medical X-ray	Small dose of ionising radiation	Shows broken bones and disease so treatment can be planned
Radiotherapy	Healthy tissue near the tumour can be damaged	Beams aimed from different angles destroy cancer cells
Working with sources in a laboratory	Exposure if rules are not followed	Understanding of radioactivity; risk is limited by precautions

Section 7 of 8Key terms

Term	Meaning
Mutation	A change in the DNA sequence of a gene.
Cancer	A disease caused by cells dividing in an uncontrolled way.
Benign tumour	A growth that stays in one place and does not spread.
Malignant tumour	A cancerous growth that invades tissues and spreads.
Dosimeter	A badge or device worn to measure a person's radiation exposure.

Section 8 of 8Exam technique

1

Saying all tumours are cancer. Benign tumours do not invade other tissues.

2

Leaving out DNA when explaining how radiation causes cancer: ionisation damages DNA, producing mutations.

3

Suggesting that distance does not matter. The further from a source, the lower the dose.

4

Forgetting that ultraviolet is also ionising and harms skin and eyes.

5

Forgetting that rapidly dividing cells are the most vulnerable to radiation damage.