Strontium (Strontium, Sr) is a chemical element of group II of the periodic system of elements of D. I. Mendeleyev. Alkaline earth metal: serial number 38, atomic weight 87,62. Strontium has 4 stable isotopes with mass numbers 84, 86, 87, 88 and several radioactive isotopes. In the earth's crust contains small quantities. Strontium can concentrate plant and animal organisms in animals and man he deposited mainly in the bones as phosphate.
In medicine the greatest application have received a radioactive isotope of strontium - Sr90, that at decay (T = 28,4 year) emits beta particles with energy 0,535 MeV (see Beta-radiation).
Sr90 apply for radiation therapy (see) by the method of applications for eye diseases (tumors) and superficial skin lesions and mucous membranes (capillary angioma, alvimarine, Bowen's disease, erosion, leukoplakia, and others). Peloponese beta radiation Sr90 primarily affects Superficial pathological lesions, whereas deeper healthy tissues remain intact. The radiation dose from strontian applicator placed on the skin is at a depth of 5 mm only 2.8 percent.
Toxicological importance of radioactive isotopes of strontium, produced in nuclear reactors (see nuclear Reactors), and when the explosions of atomic bombs (see fallout). Radioactive strontium, formed in the explosions, gets into the soil and water, absorbed by plants, and then with plant food, or with milk animals that feed on these plants, penetrates into the human body. In the body of radioactive strontium concentrated in the bones and firmly fixed there. The effective period (see) half-life of Sr -90 from the human body is 15.3 years. Thus, in the body is created constant hotbed of radioactivityaffecting bone and bone marrow. The outcome of this exposure in long term can be radiation osteosarcoma and leukemia.
By ingestion of large quantities of radioactive strontium in the body there is the risk of developing acute radiation injury; the long admission in small doses can cause chronic radiation sickness (see).
Working with radioactive strontium should be undertaken with great caution. Measures of protection against ingress of radioactive strontium into the body (see Nuclear industry. Antiradiation protection, physical).