hazards of nuclear radiation

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Effect of nuclear radiation on living cells

  radiation damage
Example of radiation damage.

When radiation collides with molecules in living cells it can damage them. If the DNA in the nucleus of a cell is damaged, the cell may become cancerous. The cell then goes out of control, divides rapidly and causes serious health problems.

The greater the dose of radiation a cell gets, the greater the chance that the cell will become cancerous. However, very high doses of radiation can kill the cell completely. We use this property of radiation to kill cancer cells, and also harmful bacteria and other micro-organisms.

Alpha, beta and gamma radiation

  image: the radiation warning symbol: a yellow circle with three black, pie-shaped segments inside" title="image: the radiation warning symbol: a yellow circle with three black, pie-shaped segments inside
This hazard symbol is shown on containers of radioactive substances to warn of the dangers

The degree to which each different type of radiation is most dangerous to the body depends on whether the source is outside or inside the body.

If the radioactive source is inside the body, perhaps after being swallowed or breathed in:

  • Alpha radiation is the most dangerous, because it is absorbed easily by cells.
  • Beta, gamma (and X-ray) radiation are not so dangerous, as they are less likely to be absorbed by a cell and usually just pass right through it.

If the radioactive source is outside the body:

  • Alpha radiation is not as dangerous, because it is unlikely to reach living cells inside the body.
  • Beta, gamma (and X-ray) radiation are the most dangerous sources, as they can penetrate the skin and damage the cells inside.

Notice that these effects are opposites.

Safety precautions

Precautions are necessary when working with radioactive sources. Such sources should be kept away from the body and never brought close to the eyes. Sources should be shielded from the body and handled using tongs so that the source is kept away from the body.

The radiation that a person receives can be monitored using film badges. The film in the badge is developed once the badge has been worn for a certain length of time. The amount of blackening that is produced on the film is a measure of the dose received by the person wearing the badge. Film badges are checked regularly to ensure that the dose received by the person does not exceed safety limits.

[ This page has been adapted from www.bbc.co.uk/schools/gcsebitesize/science ]