When a living cell is exposed to ionising radiation it sustains some form of damage. If the dosage is low enough, the cell can often repair itself. But in higher doses, radiation will either kill a cell immediately or alter its DNA so significantly as to trigger mutations.
Severe exposure to radiation, like the dosages absorbed by atomic bomb survivors, leads to widespread cell death called radiation poisoning. The intestinal lining withers, causing internal bleeding, or the central nervous system collapses – death is inevitable within hours.
Lower doses of radiation have more long-term effects. A cell damaged by ionising radiation will attempt to repair itself. Mistakes can be made, resulting in an altered DNA sequence called a mutation. Sometimes the genes controlling cell division are damaged, leading to cancerous growths. If a foetus is exposed, the damaged DNA can lead to developmental mutations like small head size. If an adult is exposed, the DNA within reproductive cells can sustain mutations that are passed on to the next generation.
Radiation side effects:
1. Hair loss – Since hair cells divide at a fast rate, they are most vulnerable to radiation.
2. Brain – Radiation-induced brain swelling (oedema) can cause temporary speech problems, headaches or double vision.
3. Thyroid – The thyroid naturally absorbs iodine to function. Unfortunately, this also makes it a natural repository for radioactive isotopes of iodine.
4. Blood system – White blood cells (lymphocytes) are constantly regenerating, making them highly sensitive to radiation.
5. Heart – Damage to valves and ventricles can lead to stiffening of heart muscles and congestive heart failure.
6. Gastrointestinal tract – The GI tract is very sensitive to radiation. Widespread cell damage can lead to internal bleeding and death.
7. Reproductive tract – Damage to reproductive cells can result in DNA mutations that are passed on to the next generation.