Question: what is the most vonrable part of the body?

Becky Martin answered on 13 Mar 2014:

Dave, your cells are vulnerable!

Ionizing radiation can cause potentially cellular damage to whichever part of your body is exposed, by damaging DNA and meaning that you might produce cells with altered or mutated DNA in future.

Particular types of cell are more vulnerable to the effects of radiation than other, and this vulnerability is dependent upon the cell activity (cells that are reproducing rapidly are more vulnerable, which is one of the reasons why children are at greater risk from radiation); and the type of cell. We call this specific cell vulnerability “radiosensitivity”. White blood cells (Lymphocytes) that circulate your body in your bloodstream, and are produced from bone marrow, are constantly regenerating and are therefore more vulnerable.

The parts of the body that are vulnerable are also decided, by whether they can possibly accidentally uptake radioactive materials, as part of our body processes.

As far as specific parts of your body are concerned, your skin is high risk because it’s damaged by beta particles and gamma rays; and your thyroid gland in your neck is up there in the vulnerability stakes too, because Iodine is an important part of its function, and radioactive Iodine-131 escapes during a lot of nuclear accidents. Therefore we give people high doses of normal Iodine during nuclear accidents, because it helps to block the thyroid from absorbing the radioactive stuff.

We use things called “reference person models” to understand how radiation affects different types of people, according to age and gender, depending on the amount of radiation they are exposed to.