Question

Radioactive strontium poses a hazard to humans because it can be absorbed by the body and incorporated into a person's bones. Once there, it will continue to undergo radioactive decay and continue the exposure to radiation. Why is it taken into the bone tissue instead of being eliminated from the body?

Answer 1

From the chemical analysis of bone, we know that approximately 40% of it is made of Calcium. Now, if you notice in the periodic table, both Calcium and Strontium are of the same Alkaline Earth metals group(in fact, Sr is just below Ca) i.e. Group 2. So from here, it is quite evident that they both have similar properties as they both have a similar outer electronic configuration as shown below-

Having identical chemical properties like calcium, when Strontium enters into the blood flow and enters the cells, a good enough portion of Strontium gets stored into the surface(as taking up Ca and Sr is the same thing for the bone!) of the bones in adults while in children, it also takes part in the formation of the hard mineral of the bone and this way it gets stored in human body and continue its process of radioactive decay.