Radiation Safety Training

Tissue and Organ Effects of Acute Radiation Exposure

Degree of Sensitivity Tissue Type Remarks


Extremely radiosensitive

Blood-forming Organs
  • lymph nodes 
  • thymus 
  • spleen 
  • bone marrow
Exposures as low as 50 rad can affect the white cell population. Red cell counts fall 2-3 weeks later. General weakness, anemia, and a lower resistance to infection results.


Moderately radiosensitive


Reproductive Organs

Exposures below 100 rad can reduce fertility. Temporary sterility can occur lasting 12 to 15 months following 200-300 rad. On the average, a larger exposure is needed to produce sterility in the male than in the female. 





Digestive Organs

  • small intestine 
  • lower intestine 
  • pharynx 
  • esophagus
Degenerative changes occur as soon as 30 minutes after exposure of 500-1000 rad. Initial effects are: impaired secretion of necessary fluids: cell breakdown results in failure of food and water absorption leading to infection and dehydration from diarrhea.



Moderately radioresistant



Vascular system

Sensitivity varies for the vascular system. Damage is great only in the 600-1500 rad range. This damage by radiation contributes to some of the heart, changes in other tissues.






Exposures between 500-1000 rad can produce skin changes. However, as little as 100 rad can cause cell death in the germinal layer.


Relatively radioresistant


Bone and Teeth; 

Respiratory System

Some parts of bone can be damaged by 700-1500 rad. Inflammation of the lungs can occur at 1000-2000 rad. Possible hemorrhaging due to changes produced in blood vessels.


Very radioresistant


Urinary System; 

Muscle and Connective Tissues

Secondary effects can show up years after exposure in the 500-2000 rad range due to changes in blood vessels. Massive exposures (over 2000 rad) are needed to cause slight changes in these tissues.


Extremely Radioresistant


Nervous system

Massive exposures are required (over 3000 rad) to bring about morphological changes in these tissues.


Back to the Biological Effects Module


Miami University's Radiation Safety Office would like to thank Sue Dupre and Princeton University for the training materials used in this website.

© Miami University | 501 East High Street | Oxford, Ohio 45056 | 513-529-1809
Equal opportunity in education and employment | Trouble viewing this page? accessibility@muohio.edu
Privacy Statement | Miami University is a smoke-free environment.