| Russian Institute of Agricultural Radiology and Agroecology |  |
| Russian Institute of Agricultural Radiology and Agroecology | |
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strontium-90 |
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| Editor | Anisimov Vyacheslav |
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| Entity code | STRON | |
| CAS registry No. | 10098-97-2 | |
| Family | ||
| Functions | ||
| Chemical name | Strontium-90 (EN) | |
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| Last updated | 20/5/2003 | |
Fate
Strontium-90 is one of 11 radioisotopes of strontium that are produced in nuclear fission. Strontium-90 is a low-energy beta emitter that decays to its radioactive daughter, yttrium-90, with a relatively long physical half-life of approximately 28 years (1.06 x 104 days). Because of radioactive decay, yttrium-90 is always present in the environment with strontium-90. Strontium-90 may be released to the environment from normal operation of nuclear power plants and reactors, nuclear plant accidents, past nuclear weapons testing, and leakage from radioactive waste sites. Strontium is an alkaline earth metal belonging to Group IIA of the periodic table. The chemical behaviour of a radionuclide is essentially the same as that of the stable element (stable strontium or strontium-88) and is similar to that of other elements in the same chemical group, such as calcium.
Toxicology
Metabolically, strontium is an analog of calcium. Strontium-90 is rapidly absorbed from the digestive tract or the lung into the bloodstream and is subsequently deposited in bone. Retention in the bone is long-term, with yearly loss of the existing burden in adults of 7.5% from cortical bone and 30% from trabecular bone. Oral intake at high levels of activity results in irradiation of target organs and nearby tissues. At high exposures, death results from radiation-induced hemorrhagic syndrome; at lower exposures, death results from destruction of the bone marrow. Inhalation of soluble forms of strontium-90 at high activity levels resulted in early death of beagle dogs from bone marrow hypoplasia, panleukocytopenia, terminal hemorrhage, and bacterial infection.
The EPA (1994) has calculated slope factors for strontium-90 for lifetime excess total cancer risk per unit intake of exposure for ingestion, inhalation, and external exposure.
The combined slope factors (risk) from strontium-90 plus its decay product, yttrium-90, have also been calculated:
Detection
Sampling
Methods
Radiostrontium is a radionuclide which needs chemical separation before measurement, since 89Sr or 90 Sr are only ß-emitters. The pure ß-emitter 90Sr(Eßmax = 0.546 MeV) undergoes radioactive decay with a half life of 28.1 years via 90Y(Eßmax = 2.27 MeV, T1/2 = 64.1 hours) to stable 90Zr.
Therefore the reliable determination of 90Sr is possible through:
The determination of 90Sr via its daughter product is recommended because 90Y is more easily measured and its radiochemical purity can be checked, but this is a more time-consuming method. More rapid methods are based on Sr- or Y-separation from matrix and direct counting of the source for beta activity.
Because 89Sr can not be chemically separated from 90Sr, when 89Sr is presented in the sample the total 89Sr+90Sr activity is measured at first after chemical separation of strontium, and then the sample is measured again after about 14 days (89Sr+90Sr+90Y). Alternative - measuring of accumulated 90Y after separation (activity of 90Y= activity of 90Sr). 89Sr is calculated by subtracting.
MRLs
Uses
Strontium-90 is one of 11 radioisotopes of strontium that are produced in nuclear fission. Strontium-90 is a low-energy beta emitter that decays to its radioactive daughter, yttrium-90, with a relatively long physical half-life of approximately 28 years (1.06 x 104 days). Because of radioactive decay, yttrium-90 is always present in the environment with strontium-90. Strontium-90 may be released to the environment from normal operation of nuclear power plants and reactors, nuclear plant accidents, past nuclear weapons testing, and leakage from radioactive waste sites. Strontium is an alkaline earth metal belonging to Group IIA of the periodic table.
Metabolically, strontium is an analog of calcium. Strontium-90 is rapidly absorbed from the digestive tract or the lung into the bloodstream and is subsequently deposited in bone. Retention in the bone is long-term, with yearly loss of the existing burden in adults of 7.5% from cortical bone and 30% from trabecular bone. Oral intake at high levels of activity results in irradiation of target organs and nearby tissues. At high exposures, death results from radiation-induced haemorrhagic syndrome. Lower exposures may result in death from destruction of the bone marrow.
The EPA (1994) has calculated slope factors for strontium-90 for lifetime excess total cancer risk per unit intake of exposure for ingestion, inhalation, and external exposure.
The combined slope factors (risk) from strontium-90 plus its decay product, yttrium-90, have also been calculated:
Notes
Bibliography
Mode of action
Ecotoxicology
Plant metabolism & residues
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