Question

At one time, nuclear bombs were tested by exploding them aboveground. The fallout from such tests contained some Sr-90, a radioactive isotope of strontium. If Sr-90 gets into the food supply, it can become incorporated into the bones of humans and other animals. Explain how this can happen even though strontium is not a normal compounds of bones.

(Thank you for explaining!)

Answer 1

Answer: Sr-90 is found nearly everywhere in small amounts from past nuclear accidents and fallout from nuclear explosions. You can be exposed to low levels of Sr-90 by eating food, drinking water, or accidentally eating soil or dust that contains Sr-90. Food and drinking water are the largest sources of exposure to Sr-90. Because of the nature of Sr-90, some of it gets into fish, vegetables, and livestock. Grain, leafy vegetables, and dairy products contribute the greatest percentage of dietary Sr-90 to humans.The intake of radioactive strontium for most people will be small. You can take in more Sr-90 if you eat food that was grown on a radioactive strontium-contaminated hazardous waste site.

Both stable strontium and radioactive strontium enter and leave the body in the same way. If a person breathes in vapors or dust containing a chemical form of strontium that is soluble in water, then the chemical will dissolve in the moist surface inside the lungs and strontium will enter the bloodstream relatively quickly. If the chemical form of strontium does not dissolve in water easily, then particles may remain in the lung for a time. When you eat food or drink water that contains strontium, only a small portion leaves the intestines and enters the bloodstream. Studies in animals suggest that infants may absorb more strontium from the intestines than adults. If a fluid mixture of a strontium salt is placed on the skin, the strontium will pass through the skin very slowly and then enter the bloodstream. If the skin has scratches or cuts, strontium will pass through the skin much more quickly.

Once strontium enters the bloodstream, it is distributed throughout the body, where it can enter and leave cells quite easily. In the body, strontium behaves very much like calcium. A large portion of the strontium will accumulate in bone. In adults, strontium mostly attaches to the surfaces of bones. In children, whose bones are still growing, strontium may be used by the body to create the hard bone mineral itself. As a result the strontium will be stored in the bone for a long time (years). Because of the way bone grows, strontium will be locally dissolved from bone and recirculate through the bloodstream, where it may be reused by growing bone, or be eliminated. This process accounts for the slow removal of strontium from the body.

Strontium is eliminated from the body through urine, feces, and sweat. Elimination through urine may occur over long periods, when small amounts of strontium are released from bone and do not get recaptured by bone. When strontium is taken in by mouth, the portion that does not pass through the intestinal wall to enter the bloodstream is eliminated through feces during the first day or so after exposure...

I hope that the above explanation will help you...