IS 



MISCELLANEOUS PUBLICATION NO. 10 65, U.S. DEPARTMENT OF AGRICULTURE 



our environment derive from testing of nuclear 

 weapons; power reactors, with emphasis on acci- 

 dental release; mining operations involving min- 

 erals containing natural radioactivity ; refining of 

 uranium and thorium ; and accidental release from 

 medical and research centers. 



Radioactivity can affect livestock either by di- 

 rect external radiation or by ingestion. Effects of 

 direct radiation from a nuclear catastrophe would 

 depend on the intensity and duration of the radia- 

 tion received. Animals that receive a lethal dose 

 at a slow rate may survive for weeks, whereas 

 deaths may occur within a few days from the same 

 radiation close applied at a high intensity over a 

 few hours. 



Detonation tests of nuclear weapons give off an 

 array of radioactive substances. We are particu- 

 larly concerned with the ones known as strontium - 

 90, cesium-137, and iodine-131 that enter into the 

 air as a result of atmospheric or surface tests, and 

 thereby are widely dispersed through the strato- 

 sphere. These radioactive particles may fall to the 

 earth as a downward drift knoAvn as radioactive 



fallout. Snow and rain help bring such fallout to 

 earth. A nuclear detonation anywhere in the north- 

 ern hemisphere could produce fallout on the 

 United States. Fallout can contaminate food, wa- 

 ter, fields, and buildings. 



A general diagram developed by Aleksakhin (7) 

 illustrates the importance of agricultural activity 

 as routes by which nuclear fission products may 

 be conveyed to man. (See diagram below.) 



Chemically, strontium is similar to calcium. It 

 enters into and behaves in water, soil, food and 

 feed, plants, animal tissues, bones, and milk much 

 as calcium does. Strontium-90 has a half-life of 

 28 years, meaning that it loses half of its radio- 

 activity every 28 years. Because of its long half- 

 life and its readiness to enter into bones wherein 

 accumulations could cause bone cancer, it is a po- 

 tentially dangerous contaminant. 



Eadioactive iodine may accumulate in thyroid 

 glands and induce thyroid cancer. Fortunately, 

 iodine-131 has a half-life of only 8 days so the 

 danger period is short. 



Cesium-137 behaves much like potassium. It has 



Soil 



Radioactive isotopes 

 from nuclear tests 

 in the atmosphere 



Plants and animals 

 of open water bodies 



Man 



