Brainlag PlusContamination and irradiation, background radiation and doses in sieverts, and how to choose an isotope for a job in medicine or industry from its radiation and half-life.
Contamination and irradiation
Ionising radiation can damage cells and the DNA inside them, which can kill cells or lead to cancer.
- Irradiation: being exposed to radiation from a source outside you. Move away, or shield the source, and the exposure stops. An irradiated object does not become radioactive.
- Contamination: radioactive atoms get onto or into something (dust on skin, a gas breathed in, a tracer swallowed). The exposure goes on until the material is removed or decays.
Outside the body, alpha is the least dangerous (air and skin stop it). Inside the body, it is the most dangerous: it is next to living cells and is the most ionising. Precautions: tongs, gloves, distance, short times near the source, lead-lined storage.
Findings about the effects of radiation are published and checked by other scientists (peer review), so that safety rules rest on evidence that others have tested.
The rest of this lesson and its 13 practice questions are in Plus.
Screen 1 of 4, free to read.
- 13 exam-style questions, marked as you go, each with a worked solution
- Anything you get wrong is saved to your flashcards