• Question: What is the determining factor between harmful and harmless radiation? Or is it simply the quantity of exposure?

    Asked by Tomiris Tatisheva to Samantha on 23 Nov 2020.
    • Photo: Samantha Watson

      Samantha Watson answered on 23 Nov 2020:

      Hi. Really good question.

      Firstly, radiation exposure to the body can cause two main types of effect. The first is called determinisitic, and refers to something that will occur – perhaps a skin burn or radiation sickness. The other is called stochastic effects, which is where something might occur – largely we are talking about risk of developing cancer.

      Most scientists (but not all) think that deterministic effects have a threshold dose and if you get less radiation dose than that threshold, you won’t see an effect, but if you go over the threshold you will, and the severity of the effect increases with increasing exposure. But for stochastic effects most think that there is no safe dose – no harmless level of exposure – and any exposure will increase an individual’s chance of getting cancer. So if you have more radiation exposure, you are more likely to get cancer, but if you do get cancer it won’t be any better or worse depending on the exposure.

      The rate at which you receive the exposure also has an effect – whether you get all the exposure in one hit, or spread out over time. Generally, if the exposure is spread out, the body has a chance to recover between one part of the exposure and the next, so the effect is less.