Up to .25 Sv there are no outward symptoms in the average adult. But this is accumulating radiation - and radiation is like having microscopic bullets shot through your body - the more shot, the better the chances a bullet will hit something strategic in a cell......and cause its death or damage. Also, small children in more danger.
Symptoms of acute radiation (dose received within one day):
- 0 – 0.25 Sv (0 – 250 mSv): None
- 0.25 – 1 Sv (250 – 1000 mSv): Some people feel nausea and loss of appetite; bone marrow, lymph nodes, spleen damaged.
- 1 – 3 Sv (1000 – 3000 mSv): Mild to severe nausea, loss of appetite, infection; more severe bone marrow, lymph node, spleen damage; recovery probable, not assured.
- 3 – 6 Sv (3000 – 6000 mSv): Severe nausea, loss of appetite; hemorrhaging, infection, diarrhea, peeling of skin, sterility; death if untreated.
- 6 – 10 Sv (6000 – 10000 mSv): Above symptoms plus central nervous system impairment; death expected.
- Above 10 Sv (10000 mSv): Incapacitation and death. (Source: Wikipedia)