Strontium is a natural and commonly occurring element, usually found in nature in the form of minerals. Natural strontium is not radioactive and exists in four stable types (or isotopes), each of which can be written as 84Sr, 86Sr, 87Sr, and 88Sr. All four isotopes behave the same chemically, so any combination of the four would have the same chemical effect on your body. At Micro Trace Minerals, we test natural strontium.
Strontium compounds, such as strontium carbonate, are used in making ceramics and glass products, pyrotechnics, paint pigments, fluorescent lights, medicines, and other products.
Strontium can also exist as radioactive isotopes. 90Sr is the most hazardous of the radioactive isotopes of the chemical element strontium. 90Sr is formed in nuclear reactors or during the explosion of nuclear weapons.
The radioactive isotope 89Sr is used as a cancer therapeutic to alleviate bone pain. 85Sr has also been used in medical applications.
Stable and radioactive strontium compounds in the air are present as dust. Emissions from burning coal and oil increase stable strontium levels in air. In water, most forms of stable and radioactive strontium are dissolved. Stable strontium that is dissolved in water comes from strontium in rocks and soil that water runs over and through. Only a very small part of the strontium found in water is from the settling of strontium dust out of the air.
Both stable strontium and radioactive strontium enter and leave the body in the same way.
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).
There are no harmful effects of stable strontium in humans at the levels typically found in the environment. The only chemical form of stable strontium that is very harmful by inhalation is strontium chromate, but this is because of toxic chromium and not strontium itself. Problems with bone growth may occur in children eating or drinking unusually high levels of strontium, especially if the diet is low in calcium and protein.
The harmful effects of radioactive strontium are caused by the high energy effects of radiation. Since radioactive strontium is taken up into bone, bone itself and the soft tissues nearby may be damaged by radiation released over time. Because bone marrow is the essential source of blood cells, blood cell counts may be reduced if the dose is too high. This has been seen in humans who received injections of radioactive strontium (89Sr) to destroy cancer tissue that had spread to the bone marrow.
Strontium is eliminated from the body through urine, feces, hair, and nails. When strontium is taken in by mouth, the portion that does not pass through the intestinal wall to enter the bloodstream, but is eliminated through feces during the first day or so after exposure.