Question: How does nuclear radiation affect human bodies, how does it change the body?

Becky Martin answered on 12 Mar 2014:

Hi Nell,

The effects of ionising radiation (radiation from radioactive materials, rather than UV or other sources) upon humans are dependent upon the amount of time that a person is exposed; amount of radiation, or radiation dosage that is absorbed by the body; the exposure route, which is the way that radiation gets into the body (via skin, ingestion or through an open injury, for example); and also the type of radiation that a person is exposed to.

There are three types of radiation; specifically alpha particles, beta particles and gamma waves.

Alpha particles are shielded by human skin, but can be harmful if you ingest or inhale them.

Beta particles need a thicker shield than skin to stop them from entering your body; because they’re over 8000 times smaller than alpha particles, which is what makes them a bit more dangerous! External exposure to beta particles can change the body by causing radiation burns and tissue damage, and radiation sickness.

Gamma rays are high energy photons, which are tiny bundles of electromagnetic energy, and can travel the furthest into the body through the skin, because they have no mass! It takes several inches of lead or several feet of concrete to prevent gamma rays from reaching humans. Because gamma rays can pass through the whole body, they can affect all your tissues from your skin to your bone marrow, which can cause widespread damage and radiation sickness.

The effects of radiation upon the body can be divided into immediate effects, which are known as deterministic; and long-term effects, which are known as stochastic.

Exposure to very high levels of radiation, such as the Chernobyl firefighters experienced, can cause deterministic effects such as radiation sickness and burns. Radiation sickness isn’t very nice! It causes nausea, vomiting, weight loss and depletion of white blood cells in the bone marrow, which increases likelihood of infections. Again, survival rate depends upon radiation dosage received.

Exposure to high levels of ionising radiation can increase the chance of stochastic effects, such as a person developing cancer over time; because of the effect that radiation has upon DNA. There can also be an increased risk of developing cataracts, and both women and men can be sterilised at high level exposure.

When someone is accidentally exposed to radiation, we use a model called the linear-no threshold model to understand the likelihood of developing cancer, according to the radiation dose they have received.

When we think about the effects that radiation has upon humans, we use a unit called the Sievert. However, 1 Sievert is a very high dosage, therefore we convert down to millisieverts, where 1 millisievert is equivalent to one thousandth of a Sievert (1000 mSv = 1Sv). To give you some perspective, we are all exposed to very low levels of radiation of about 2 mSv per year, whereas the typical dosage of Chernobyl workers within the exclusion zone was 6000 mSv!
However, the effect of radiation on humans can also be positive – When we use radiation for medical purposes, we use carefully measured and targeted amounts to damage the DNA of cancerous cells in order to kill them and prevent them from growing, so it’s pretty powerful stuff!

Hope that answers your question!