AQA · GCSE · Physics
Course version: 8463 · Version from Sept 2016
The hazard from contamination is due to the decay of the contaminating…
Full specification wording
Radioactive contamination: The hazard from contamination is due to the decay of the contaminating atoms.
Contamination is hazardous because the atoms that have been transferred go on decaying exactly where they have landed.
Checked against the AQA 8463 specification (opens in a new tab) on .
- Point 2 of 8
- 3 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Contamination is hazardous because the atoms that have been transferred go on decaying exactly where they have landed. Every decay happens in contact with, or inside, living tissue, so the ionising radiation is absorbed by cells rather than by the air or by clothing. This flips the usual ranking of danger. Outside the body alpha radiation is almost harmless because its low penetrating power means skin stops it, but inside the body that same alpha radiation is absorbed by tissue and organs and, being highly ionising, does a great deal of damage in a small volume. The extra dose raises the chance of damage to cells, DNA and genes, and so of mutations or cancer. The hazard lasts as long as the contaminating atoms keep decaying.
What earns the marks
- The hazard lasting as long as the contaminating atoms continue to decay.
- Alpha radiation having a low penetrating ability, so externally it is stopped or absorbed by the skin and the risk is low.
- Internal contamination putting the source where alpha radiation is absorbed by living tissue or organs.
- Alpha radiation being highly ionising, so the internal dose causes greater harm to cells, tissues, organs or DNA.
- Linking the increased radiation dose to a greater chance of mutations or of developing cancer.
Common mistakes and how to put them right
Saying the radiation stays in the body, when it is the radioactive material that stays.
Assuming alpha is the least dangerous radiation in every situation.
Giving 'radiation is harmful' with no mention of ionisation or of damage to cells.
Claiming a contaminated object is safe once it has been moved away from the original source.
Confusing the decay of the contaminating atoms with the object itself becoming radioactive through irradiation.
Exam tips
- Answer in two halves: what happens outside the body, then what happens inside, because the mark scheme awards both.
- Use 'highly ionising' and 'absorbed by tissue' as a pair; one without the other rarely gets the full explanation mark.
- Mention the half-life if the question gives one, since a long half-life means the hazard persists.
Try the lesson
The start of the Radioactive contamination: The hazard from contamination is due to the decay of the contaminating atoms. lesson, made from checked teaching notes for this specification point.
Have a go first
A worker spills a radioactive liquid on their hand. Why is this contamination hazardous to the worker?
Listen
Contamination is hazardous because the atoms that have been transferred go on decaying exactly where they have landed. Every decay happens in contact with, or inside, living tissue, so the ionising radiation is absorbed by cells rather than by the air or by clothing. This flips the usual ranking of danger. Outside the body alpha radiation is almost harmless because its low penetrating power means skin stops it, but inside the body that same alpha radiation is absorbed by tissue and organs and, being highly ionising, does a great deal of damage in a small volume. The extra dose raises the chance of damage to cells, DNA and genes, and so of mutations or cancer. The hazard lasts as long as the contaminating atoms keep decaying. A strong answer earns marks for these points. the hazard lasting as long as the contaminating atoms continue to decay. alpha radiation having a low penetrating ability, so externally it is stopped or absorbed by the skin and the risk is low. internal contamination putting the source where alpha radiation is absorbed by living tissue or organs. alpha radiation being highly ionising, so the internal dose causes greater harm to cells, tissues, organs or DNA. Exam tip: Answer in two halves: what happens outside the body, then what happens inside, because the mark scheme awards both.
Key words
Say what each word means before you turn the card.
decay in contact with tissue
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alpha inside the body
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radiation dose
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See every definition
- decay in contact with tissue
- Every decay of the contaminating atoms happens in contact with, or inside, living tissue, so the ionising radiation is absorbed by cells.
- alpha inside the body
- Inside the body alpha radiation is absorbed by tissue and organs and, being highly ionising, does a great deal of damage in a small volume.
- radiation dose
- The extra dose raises the chance of damage to cells, DNA and genes, and so of mutations or cancer.
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