STRONTIUM (Strontium, Sr) — chemical element of a periodic system of D. I. Mendeleyev, subgroup of alkaline earth metals. In a human body of S. competes with calcium (see) for inclusion in a crystal lattice of oxyapatite bones (see). 90 Sr, one of the most dolgozhivupy radioactive products of splitting uranium (see), collecting in the atmosphere and the biosphere at tests of nuclear weapon (see), constitutes huge danger to mankind. Radioisotopes C. apply in medicine to radiation therapy (see), as a radioactive label in diagnostic radio headlights-matsevtichesky drugs (see) in a medico-biol. researches, and also in atomic electric batteries. Connections C. use in defectoscopes, in sensitive devices, in devices for fight against static electricity, besides, S. apply in radio electronics, pyrotechnics, in metallurgical, chemical industry and at production of stonewares. Connections C. are not poisonous. During the work with metal S. it is necessary to be guided by rules of the treatment of alkali metals (see) and alkaline earth metals (see).
For page it was open as a part of mineral, after called SrC03 strontianite, in 1787 near the Scottish city of Strontsiana.
Sequence number of strontium 38, atomic weight (weight) 87,62. S.'s maintenance in crust averages 4-10 2 weight. %, in sea water — 0,013% (13 mg/l). Industrial value minerals have strontianite and SrSO celestine 4 .
In a human body contains apprx. 0,32 g of strontium, generally in a bone tissue, in blood S.'s concentration normal makes 0,035 mg/l, in urine — 0,039 mg/l.
The page represents soft silvery white metal, t°pl 770 °, t°kip 1383 °.
On chemical properties C. it is similar to calcium and barium (see), in connections the valency of strontium 4-2, it is reactive, is oxidized at usual conditions water with formation of Sr (OH) 2 , and also oxygen and other oxidizers.
The hl comes to a human body of S. obr. with vegetable food, and also with milk. It is soaked up in a small bowel and quickly exchanges with S. which is contained in bones. S.'s removal from an organism is strengthened by complexons, amino acids, polyphosphates. The increased content of calcium and fluorine (see) in water interferes with S.'s cumulation in bones. At increase in concentration of calcium in a diet by 5 times S.'s accumulation in an organism decreases twice. Excess arrival of S. with food and water owing to its increased contents in the soil of nek-ry geochemical provinces (e.g., in certain districts of Eastern Siberia) causes a local disease — an urovsky disease (see. Kashina — Beck a disease ).
In bones, blood and others biol. substrates C. define hl. obr. by spectral methods (see Spectroscopy).
Natural S. consists of four stable isotopes with mass numbers 84, 86, 87 and 88, from to-rykh the last is most widespread (82,56%). 18 radioisotopes C. (with mass numbers 78—83, 85, 89—99) and 4 isomers at isotopes with mass numbers 79, 83, 85 and 87 are known (see the Isomerism).
The majority of radionuclides C. are short-lived or ultrashort-lived. Five radionuclides C. have half-lives (T 1/2 ) of 66 min. to 33 hours, four — from days to two months and one radionuclide C. with mass number 90 — long-living. Practical application was found 85Sr (T 1/2 = 65 days), 87mSr (T 1/2 =2,83 hours), 89Sr (T 1/2 , = 50,5 days) and 90Sr (T 1/2 2 = 27,7 years). Radioactive S. is used in the national economy at researches a tracer technique, a 90Sr, besides, apply in the closed sources of beta radiation, in particular in the atomic electric batteries used and as an energy source in pacemakers (see. Cardiostimulation ).
In medicine 90Sr apply to radiation therapy in ophthalmology and dermatology, and also in radio biological experiments as a source r-izl doctrines. 85Sr receive or radiation in the nuclear reactor neutrons of the strontic target enriched on isotope 84Sr on reaction 84Sr (11,7) 85Sr, or make on a cyclotron, irradiating with protons or deuterons of a target from natural rubidium, napr, on reaction 85Rb (p, n) 85Sr. Radionuclide 85Sr breaks up with electron capture, letting out gamma radiation with energy E scale , equal 0,513 Mev (99,28%) and 0,868 Mev (<0,1%).
87m Sr can also be received radiation of a strontic target in the reactor on reaction 86Sr (n, scale) 87mSr, but an exit of required isotope is small, besides, along with 87mSr isotopes 85Sr and 89Sr are formed. Therefore usually 87niSr receive by means of the isotope generator (see. Generators of radioisotopes ) on the basis of maternal isotope of yttrium-87 — 87Y (T1/2 = 3,3 days). 87mSr breaks up with isomeric transition, letting out gamma radiation with Egamm's energy, equal 0,388 Mev, and partially with electron capture (0,6%).
89Sr contains in cleavage products together with 90Sr therefore 89Sr receive natural S.'s radiation in the reactor. At the same time also impurity 85Sr is inevitably formed. Isotope 89Sr breaks up with emission of P-radiation with energy of 1,463 Mev (apprx. 100%). In a range there is also very weak line of gamma radiation with energy E scale , equal 0,95 Mev (0,01%).
90Sr receive allocation from mix of cleavage products of uranium (see). This isotope breaks up with emission of beta radiation with energy E beta , equal 0,546 Mei (100%), without the accompanying gamma radiation. Disintegration 90Sr leads to formation of affiliated radionuclide 90Y, to-ry breaks up (T1/2 = 64 hours) with emission of the r-from-spearing consisting of two a component with ER equal of 2,27 Mev (99%) and 0,513 Mev (0,02%). At disintegration 90Y also very weak gamma radiation with energy of 1,75 Mev (0,02%) is let out.
The radioisotopes 89Sr and 90Sr which are present at waste of the atomic industry and formed at tests of nuclear weapon at environmental pollution can get into a human body with food, water, air. Quantitative assessment of migration of S. in the biosphere is usually carried out in comparison with calcium. In most cases at the movement 90Sr from the previous chain link to the subsequent there is a reduction of concentration 90Sr per 1 g of calcium (so-called coefficient of discrimination), adults in a link have an organism — the diet this coefficient is equal to 0,25.
Like soluble compounds of other alkaline earth elements soluble compounds of S. are well soaked up from went. - kish. a path (10 — 60%), absorption of plokhorastvorimy connections C. (e.g., SrTi03) makes less than 1%. Extent of absorption of radionuclides C. in intestines depends on age. With increase in content of calcium in a diet S.'s accumulation in an organism decreases. Milk promotes increase in absorption of S. and calcium in intestines. Believe that it is connected with presence at milk of lactose and a lysine.
At inhalation soluble compounds of S. eliminirutsya quickly from lungs while plokhorastvorimy SrTi03 exchanges in lungs extremely slowly. Penetration of radionuclide C. through the unimpaired skin makes apprx. 1%. Through the injured skin (a cut wound, burns, etc.)? just as from hypodermic cellulose and muscular tissue, S. is soaked up almost completely.
The page is an osteotropny element. Irrespective of a way and a rhythm of receipt in an organism soluble compounds 90Sr selectively collect in bones. In soft tissues less than 1% 90Sr are late.
At intravenous administration of S. it eliminirutsya very quickly from a blood channel. Soon after introduction S.'s concentration in bones becomes by 100 times and more above, than in soft tissues. Nek-ry differences in accumulation 90Sr in separate bodies and fabrics are noted. Rather higher concentration 90Sr is found in experimental animals in kidneys, salivary and thyroid glands, and the lowest — in skin, marrow and adrenal glands. Concentration 90Sr in cortical substance of kidneys always above, than in marrow. The page originally lingers on bone surfaces (a periosteum, an endosteum), and then is distributed rather evenly on all volume of a bone. Nevertheless distribution 90Sr in various parts of the same bone and in different bones is uneven. At first after introduction concentration 90Sr in an epiphysis and a metaphysis of a bone of experimental animals is approximately twice higher, than in a diaphysis. From an epiphysis and a metaphysis 90Sr it is allocated quicker, than from a diaphysis: in 2 months concentration 90Sr in an epiphysis and a metaphysis of a bone decreases by 4 times, and in a diaphysis almost does not change. Originally 90Sr concentrates in those sites, in to-rykh there is an active formation of a bone. Plentiful krovo-and the lymphokinesis in epimetafizarny sites of a bone promotes more intensive adjournment in them 90Sr in comparison with a diaphysis of a tubular bone. The size of adjournment 90Sr in bones at animals is changeable. Sharp decrease in fixing 90Sr in bones is revealed at all animal species with age. Adjournment 90Sr in a skeleton essentially depends on a floor, pregnancy, a lactation, a condition of neuroendocrinal system. Higher adjournment 90Sr in a skeleton is noted at males of rats. In a skeleton of pregnant females 90Sr collects less (to 25%), than at control animals. 90Sr in a skeleton of females the lactation has significant effect on accumulation. At introduction 90Sr in 24 hours after the delivery in a skeleton of rats 90Sr is late 1,5 — 2 times less, than at not lactating females.
Penetration 90Sr in fabric of an embryo and fruit depends on a stage of their development, a condition of a placenta and duration of circulation of isotope in blood of mother. Penetration 90Sr in a fruit of subjects is more, than duration of gestation at the time of administration of radionuclide is more.
For reduction of the damaging effect of radionuclides of strontium it is necessary to limit accumulation them in an organism. For this purpose at pollution of skin it is necessary to make bystry deactivation of its open sites (the drug «Protection-7», washing powders of Ayr or «Aster», NEDE paste). At peroral intake of radionuclides of strontium it is necessary to apply the antidotes allowing to connect or occlude radionuclide. Carry the activated fixed white (adso-bar) to such antidotes, polisurmin, drugs alginic to - you, etc. E.g., drug adsobar at immediate inclusion after hit of radionuclides in a stomach reduces their absorption by 10 — 30 times. It is necessary to appoint adsorbents and antidotes right after detection of defeat radionuclides of strontium since the delay in this case leads to falloff of their positive action. At the same time recommend to appoint vomitives (Apomorphinum) or to make a plentiful gastric lavage, to apply salt laxatives, cleansing enemas. At defeat by dusts plentiful washing of a nose and oral cavity, expectorants (a thermopsis with soda), ammonium chloride is necessary, for an injection of drugs of calcium, diuretic. In later terms after defeat in bones recommend to apply so-called stable strontium (S.'s lactate or S.'s gluconate) to reduction of adjournment of radionuclides C. High doses of calcium orally or intravenously MofyT to replace drugs of stable strontium if they are unavailable. Due to the good reabsorption of radionuclides of strontium in renal tubules also use of diuretics is shown.
Nek-roye reduction of accumulation of radionuclides C. in an organism can be reached by creation of the competitive relations between them and a stable isotope of S. or calcium, and also creation of deficit of these elements when radionuclide C. was already recorded in a skeleton. However effective remedies of a dekorporation of radioactive strontium from an organism it is not found yet.
Minimum significant activity which is not demanding registration or obtaining permission of bodies of the State sanitary inspection for 85mSr, 85Sr, 89Sr and 90Sr makes respectively 3,5*10 - 8 , 10 - 10 , 2,8*10 - 11 and 1,2*10 - 12 curie/l.
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A. V. Babkov, Yu. I. Moskalyov (I am glad.).