Question: How does radiation poisoning work?

Sarah O'Sullivan answered on 5 Mar 2019:

Essentially radiation can cause damage to any cells by different methods of depositing energy into the cells.

Alpha radiation is just helium nuclei so relatively heavy particles. These don’t penetrate things very well and can be stopped by paper but it means that within the body they can cause radiation dose to a specific area. Beta particles are electrons, so they penetrate further in the body before dumping it’s energy into the cells and gamma photons are essentially light. They can go right through a person, putting some energy into the cells, as can x-rays.

The energy of the radiation can ionise structures in cell- essentially cause electrons to ripped off the atoms so they’re not the same as they were. As cells are very delicate structures with lots of complicated bits (as I’m sure the biologists will tell you more about) ionising them can have drastic effects on the cells and causes them to die.

Radiation sickness is a special case where the dose received is not necessarily going to kill the person but it does cause a lot of the cells to be damaged. Damaged cells die and the DNA doesn’t reproduce correctly. This is most noticeable where the cells renew themselves very quickly so a person with radiation sickness will vomit, have diarrhoea and their hair may fall out and skin shed, because these areas renew quickly and so lots of cells dying is visible. Where this effect occurs on a person bone marrow and important glands like the thymus that make your white blood cells, the person can become very ill very quickly from infections as they have no immune system any more. Symptoms can also include seizures and bleeding due to a lack of platelets from reduced red blood cell counts. It’s not a pleasant experience