GCSE PHYSICS - Radioactivity - What is Internal Radiation? - What is the most Harmful type of Internal Radiation?

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Damage to Living Cells from Internal Radiation.

What is Internal Radiation?

Radiation which has come from radioactive sources inside of
the body is called internal radiation. All three types of radioactivity
are harmful and safety precautions must always be taken.

What is the Most Harmful Type of Internal Radiation?

Of the three types of radioactivity, alpha particles are the
most harmful form of internal radiation. Alpha particles can not
penetrate through body tissue and so will be absorbed by the
cells which are near to the radioactive source. This can cause
damage and lead to cancer of the internal organs of the body.

For example, granite rock contains radium-224 which decays
to form the gas radon-220. Radon-220 is an alpha emitter and can
be present in some buildings which have been built on granite.
People who live in the buildings can breath in radioactive
radon-220 which than continues to emit alpha particles from
inside the lungs. This increases the risk of getting lung cancer.

Both beta particles and gamma rays will penetrate through all
body tissues and are less likely to cause damage than alpha particles.
Beta particles are more ionising than gamma rays and will cause
more damage for the same exposure and intensity. Gamma rays
are the least harmful form of internal radiation. Gamma emitters
with a short half-life are the most suitable for use as medical tracers.

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