Exposure, plutonium

Biomarkers of exposure to plutonium include the presence of plutonium in urine, which is identified by measuring alpha activity. From the levels of radioactivity in the urine, body burdens of plutonium may be estimated by the use of models. Body burdens of plutonium in several populations, including workers at Los Alamos National Laboratory, the Rocky Flats facility, and the Hanford facility, have been estimated from urinalysis data. However, whole body burdens determined from selected tissues obtained at autopsy have generally been lower than those estimated from urinalysis data (Voelz et al. 1979). The presence of radioactivity from plutonium in urine is specific to plutonium exposure. Plutonium may be found in the urine after any exposure duration (e.g., acute, intermediate, chronic). Although it can be assumed that exposure to greater levels of plutonium would result in the presence of greater levels of radioactivity in the urine, no information was located to directly quantify this relationship. 

People may inhale plutonium as a contaminant in dust. It can also be ingested with food or water. Most people have extremely low ingestion and inhalation of plutonium. However, people who live near government weapons production or te.sting facilities may have increa.sed exposure. Plutonium exposure external to the body poses very little health risk. 

Plutonium(IV) polymer is a product of Pu(IV) hydrolysis and is formed in aqueous solutions at low acid concentrations. Depolymerization generally is accomplished by acid reaction to form ionic Pu(IV), but acid degradation of polymer is strongly dependent on the age of the polymer and the conditions under which the polymer was formed (12). Photoenhancement of Pu(IV) depolymerization was first observed with a freshly prepared polymer material in 0.5 HClOh, Fig. 3 (3 ). Depolymerization proceeded in dark conditions until after 140 h, 18% of the polymer remained. Four rather mild 1-h illuminations of identical samples at 5, 25, 52, and 76 h enhanced the depolymerization rates so that only 1% polymer remained after the fourth light exposure (Fig. 3). 

The use of this direct oxide reduction process is replacing fluoride reduction as it eliminates neutron exposure to operating personnel (alpha particles from plutonium decay have sufficient energy to eject neutrons from fluorine by the a,n reaction) and eliminates reduction residues which require subsequent recovery. 

All reactor-produced plutonium contains a mixture of several plutonium isotopes. The continuous decay of 241pu (14.8 year half-life) is the source of 241/. jhis isotope decays by alpha emission with the simultaneous emission of 60 kilovolt gamma rays in 80% abundance. In order to minimize personnel exposure, this element is removed from the metal prior to fabrication. 

The buttons usually have a film of Pu02 as a result of exposure to glove-box air. Upon casting, this Pu02 floats and remains in the skull along with trapped plutonium metal. This portion of the skull is recycled back into the production sequence. 

Half-lives span a very wide range (Table 17.5). Consider strontium-90, for which the half-life is 28 a. This nuclide is present in nuclear fallout, the fine dust that settles from clouds of airborne particles after the explosion of a nuclear bomb, and may also be present in the accidental release of radioactive materials into the air. Because it is chemically very similar to calcium, strontium may accompany that element through the environment and become incorporated into bones once there, it continues to emit radiation for many years. About 10 half-lives (for strontium-90, 280 a) must pass before the activity of a sample has fallen to 1/1000 of its initial value. Iodine-131, which was released in the accidental fire at the Chernobyl nuclear power plant, has a half-life of only 8.05 d, but it accumulates in the thyroid gland. Several cases of thyroid cancer have been linked to iodine-131 exposure from the accident. Plutonium-239 has a half-life of 24 ka (24000 years). Consequently, very long term storage facilities are required for plutonium waste, and land contaminated with plutonium cannot be inhabited again for thousands of years without expensive remediation efforts. 

Radioisotopes have important commercial applications. For example, americium-241 is used in smoke detectors. Its role is to ionize any smoke particles, which then allow a current to flow and set off the alarm. Exposure to radiation is also used to sterilize food and inhibit the sprouting of potatoes. Radioisotopes that give off a lot of energy as heat are also used to provide power in remote locations, where refueling of generators is not possible. Unmanned spacecraft, such as Voyager 2, are powered by radiation from plutonium. 

Various cases of internal exposure to americium have been reported in which the exposures resulted from skin punctures with materials also containing plutonium. Information on the distribution of americium in these cases has been derived from the analysis of autopsy tissues. In most cases, the largest fraction of the 241 Am activity measured in the body was associated with tissues near the puncture wound. In one case,... 

Bioavailability from Environmental Media. The absorption and distribution of americium as a result of inhalation and ingestion exposures have been discussed in Sections 3.3.1 and 3.3.2. EPA lists identical uptake factors for inhaled and ingested americium (and all the other transuranics other than plutonium) regardless of compound solubility, indicating that the knowledge base for americium is not sufficiently developed to quantify the differences that are recognized for most other elements. 

Filipy RE, Kathren RL. 1994. Changes in soft tissue concentrations of plutonium and americium with time after human occupational exposure. Health Phys 66(6)(Suppl.) S73. 

Hammond SE, Lagerquist CR, Mann JR. 1968. Americium and plutonium urine excretion following acute inhalation exposure to high-fired oxides. Am Ind Hyg Assoc J 29(2) 169-172. 

Harrison JD, Hodgson A, Haines JW, et al. 1993. The biokinetics of plutonium-239 and americium-241 in the rat after subcutaneous deposition of contaminated particles from the former nuclear weapons site at Maralinga Implications for human exposure. Hum Exp Toxicol 12 313-321. 

Lagerquist CR, Hammond SE, Hylton DB. 1972b. Distribution of plutonium and americium in the body 5 years after an exposure via contaminated punctured wound. Health Phys 22 921-924. 

Miettinen JK, Mussalo H, Hakanen M, et al. 1980. Distribution of plutonium and americium in human and animal tissues after chronic exposures. In International Radiation Protection Society, ed. Radiation protection A systemic approach to safety Proceedings of the 5th congress of the International Radiation Protection Society, Jerusalem, March 1980. New York Pergamon Press, 1049-1052. 

Moody JC, Stradling GN, Britcher AR. 1994. Biokinetics of three industrial plutonium nitrate materials Implications for human exposure. Radiat Prot Dosim 53(1-4) 169-172. 

Riches AC, Herceg Z, Bryant PE, et al. 1997. Radiation-induced transformation of SV40-immortalized human thyroid epithelial cells by single exposure to plutonium -particles in vitro. Int J Radiat Biol 72(5) 515-521. 

Radioactive plutonium isotopes emit alpha particles. The amount of radioactive plutonium in a sample can be measured by alpha spectroscopy, a technique for counting the alpha radiation. The technique is used at the Los Alamos National Laboratory (LANL) in New Mexico in order to monitor employees for exposure. 

Geering, J. J., Froidevaux, P., Schmitler, T., Buchillier, T. Valley, J. F. 2000. Mesures de plutonium et d americium dans Tenvironment. In Voelkle, H. Gobet, M. (eds) Environmental Radioactivity and Radiation Exposure in Switzerland. Swiss Inspectorate for Public Health, Amiual Report 1999, Section B7.2.1-8. 

Radionuclide Exposure of the Embryo/Fetus (1998) Recommended Screening Limits for Contaminated Surface Soil and Review of Factors Relevant to Site-Specific Studies (1999) Biological Effects and Exposure Limits for Hot Particles (1999) Scientific Basis for Evaluating the Risks to Populations from Space Applications of Plutonium (2001)... 

Sherwood Stevens (1965) examined glass-fibre filters from personal air samplers worn by workers in the Radiochemical Laboratories at Harwell. The filters were mounted in an Araldite mixture which rendered them transparent and were covered by autoradiographic stripping film. After exposure and development, the samples were viewed with a high-power optical microscope. Particles were sized, and their activity determined from the number of alpha tracks coming from them. An extremely wide range of particle sizes, 0.2 to 90 m, was found. The smaller particles were plutonium compounds or alloys, and the larger were inert particles with one or more small Pu particles attached to them. An example of the latter is shown in Fig. 5.3. 

Shinn, J.H., Homan, D.N. Gay, D.D. (1983) Plutonium aerosol fluxes and pulmonary exposure rates during re-suspension from bare soils near a chemical separation facility. In Precipitation Scavenging, Dry Deposition and Re-suspension, ed. H.R. Pruppacher, R.G. Semonin W.G.N. Slinn, pp. 1131 43. Amsterdam Elsevier. 

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