Radiation dose and its effect on humans

Year 11 Physics

Fear of RadiationMany people are worried about being exposed to radiation, however, not all radiation is harmful and some radiation is essential to sustain life.

Harmful RadiationHarmful radiation is called ionising radiation because it has enough energy to remove electrons from an atom creating a highly reactive ion (sometimes called a free radical)

For electromagnetic radiation to be ionising it must have a frequency above 1.2 × 1016 Hz

The electromagnetic spectrum*

Measuring Radiation ExposureThere are three methods used for measuring radiation exposure.1. Absorbed Dose - measured in grays (Gy)2. Dose Equivalent - measured in sieverts (Sv)3. Effective Dose – measured in sieverts (Sv)

The Effects of RadiationSomatic (short-term effects)

These occur when ordinary body cells are damaged

Long-term effectsThese include cancers that take a many years to

developGenetic effects

These occur when cells in the reproductive organs are damaged and can cause genetic changes (mutations) in babies.

The Effects of Radiation

Putting it into PerspectiveThe average annual exposure to background

radiation in Australia is 2 mSv.Coffee and alcohol are known to cause

genetic defects (not due to radiation).The risk of genetic damage from 2 mSv is

equivalent to...84 cups of coffee per year45 mL of alcohol per year

Putting it into PerspectiveThe older someone is when they conceive a

child the greater the risk of genetic defects.The increased risk associated with receiving

the average annual radiation dose in Australia is the same as the increased risk of conceiving a child when the mother is 10 days older.

Putting it into PerspectiveThe carcinogen benzpyrene occurs in air

pollution and in foods such as bacon, fish, cabbage and many others.

The risk of cancer caused by the average annual radiation dose in Australia is equivalent to the risk associated with the intake of 40 µg of benzpyrene, which the average person in Britain takes in every three-and-a-half days