Inhalation of plutonium

Espinosa A, Aragon A, Stradling N, et al. 1998. Assessment of doses to adult members of the public in Palomares from inhalation of plutonium and americium. Radiat Prot Dosim 79(1-4) 161-164. 

Hahn F, Brooks A, Mewhinney J. 1984. A pulmonary sarcoma in a Rhesus monkey after inhalation of plutonium dioxide. Annual Report to U.S. Department of Energy, Washington, DC, by Inhalation Toxicology Research Institute, Albuquerque, NM. Report No. LMF-113. 

Moores S, Talbot R, Evans N, et al. 1986. Macrophage depletion of mouse lung following inhalation of plutonium-239 dioxide. Radiat Res 105 387-404. 

Park J, Lund J, Ragan H, et al. 1976. Bone tumors induced by inhalation of plutonium-238 dioxide in dogs. Recent Results Cancer Res 54 17-35. 

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. 

Pu (86 years) is formed from Np. Pu is separated by selective oxidation and solvent extraction. The metal is formed by reduction of PuF with calcium there are six crystal forms. Pu is used in nuclear weapons and reactors Pu is used as a nuclear power source (e.g. in space exploration). The ionizing radiation of plutonium can be a health hazard if the material is inhaled. 

Elaborate precautions must be taken to prevent the entrance of Pu iato the worker s body by ingestion, inhalation, or entry through the skin, because all common Pu isotopes except for Pu ate a-emitters. Pu is a P-emitter, but it decays to Am, which emits both (X- and y-rays. Acute intake of Pu, from ingestion or a wound, thus mandates prompt and aggressive medical intervention to remove as much Pu as possible before it deposits in the body. Subcutaneous deposition of plutonium from a puncture wound has been effectively controlled by prompt surgical excision followed by prolonged intravenous chelation therapy with diethylenetriaminepentaacetate (Ca " —DTPA) (171). 

Okabayashi H. 1980. Differential movement of plutonium and americium in lungs of rats following the inhalation of submicron plutonium nitrate aerosol. J Radiat Res 21 111-117. 

Stanley JA, Edison AF, Mewhinney JA. 1982. Distribution, retention and dosimetry of plutonium and americium in the rat, dog and monkey after inhalation of an industrial-mixed uranium and plutonium oxide aerosol. Health Phys 43(4) 521-530. 

Pu(IV), which forms highly charged polymers, strongly sorbs to soils and sediments. Other actinide III and IV oxidation states also bind by ion exchange to clays. The uptake of these species by solids is in the same sequence as the order of hydrolysis Pu > Am(III) > U(VI) > Np(V). The uptake of these actinides by plants appears to be in the reverse order of hydrolysis Np(V) > U(VI) > Am(III) > Pu(IV), with plants showing little ability to assimilate the immobile hydrolyzed species. The further concentration of these species in the food chain with subsequent deposit in humans appears to be minor. Of the 4 tons of plutonium released to the environment in atmospheric testing of nuclear weapons, the total amount fixed in the world population is less than 1 g [of this amount, most (99.9%) was inhaled rather than ingested]. 

Most radioactive particles and vapours, once deposited, are held rather firmly on surfaces, but resuspension does occur. A radioactive particle may be blown off the surface, or, more probably, the fragment of soil or vegetation to which it is attached may become airborne. This occurs most readily where soils and vegetation are dry and friable. Most nuclear bomb tests and experimental dispersions of fissile material have taken place in arid regions, but there is also the possibility of resuspension from agricultural and urban land, as an aftermath of accidental dispersion. This is particularly relevant to plutonium and other actinide elements, which are very toxic, and are absorbed slowly from the lung, but are poorly absorbed from the digestive tract. Inhalation of resuspended activity may be the most important route of human uptake for actinide elements, whereas entry into food chains is critical for fission products such as strontium and caesium. 

Cooper et al. (1994) have reported re-suspension studies on soils contaminated with plutonium during nuclear weapons tests by use of a mechanical dust-raising apparatus. Airborne dust was analysed in terms of mass and Am activities for particle sizes less than 7 pm. The AMAD was determined as 4.8-6 pm for re-suspended soil. Also, surface soil was characterised in the laboratory by means of sieving and microparticle classification, yielding mass and "Am activity distribution with respect to size. Data indicate the granularity of plutonium contamination at both major and minor trial sites. Depth profile analyses for undisturbed areas demonstrate that most (74% on average) of the americium and plutonium activity is found in the top 10 mm of soil. Plutonium and americium activities were found to be enhanced in the inhalable fraction over their values in the total soil, and the enhancement factors were similar in re-suspended dust and surface soil. Observed enhancement factors ranged from 3.7 to 32.5. 

An analysis of 203 workers with internal deposits of plutonium showed that 131 were contaminated by inhalation, 48 through wounds, and eight by both routes. Most exposures to the general population involve minute quantities inhaled with ambient air or ingested in food and water. In the 1970s, a mean dietary intake of 1.6 pCi year was estimated for New York City. 

There are several isotopes of plutonium (Pu-238 and Pu-239 being the most important), and it is the chemistry of the isotopes that determines the reactions within the environment as well their transport and reactions within the body. Ingested plutonium is primarily excreted in feces, as there is very poor absorption from the gastrointestinal tract. For inhalation, the regional deposition pattern depends primarily on particle size distribution. Within the first few days, a fraction of the deposited activity is rapidly cleared from the respiratory tract. The remaining fraction is cleared slowly, with retention half-time of months to years, depending on the chemical form (oxides, for example, tend to be cleared more slowly than nitrates). Materials absorbed from the respiratory tract are primarily deposited in bone and liver, where it is retained for many years. A very small fraction may also be deposited in testes or ovaries. 

Chronic effects of plutonium exposure include lifeshortening and cancer. These effects have been observed in numerous animal studies. The main late pulmonary effects of plutonium inhalation are pulmonary fibrosis and lung cancer. Lung cancers in animals have been reported for intakes equivalent to 37kBq (1 pCi) in man. 

Clinical management can potentially reduce the effects of plutonium intake, although the effectiveness can be highly variable. Administration of the calcium salt of diethylenetriaminepentaacetic acid (DTPA) can accelerate removal of soluble forms of plutonium from body fluids and recent deposits. It is unable to remove intracellular deposits or activity buried in bone and must therefore be administered as soon as possible after an intake. In a review of 18 patients exposed to plutonium, americium, or curium, the US Food and Drug Administration concluded that administration of 1 g Ca-DTPA in 5 ml sterile aqueous solution, either by intravenous injection or as a nebulized inhalation dose, increased the rate of radioactivity elimination in urine by an average of 39-fold. Daily maintenance doses of Zn-DTPA resulted in continued elimination of radioactivity. 

Deterministic effects are those that increase in severity as the radiation dose increases and for which a threshold is presumed to exist. Besides acute somatic effects, deterministic effects also include radiation effects (other than cancer and genetic effects) that continue to occur after an extended period (e.g., years) of chronic exposure. Such chronic exposures can arise from long-lived radionuclides (e.g., isotopes of plutonium and cesium) ingested via contaminated food or inhaled via contaminated air... 

Asbestos exerts a synergistic influence on cigarette smoke (which contains several PAHs) in the development of bronchopulmonary cancers. This has important implications for workers occupationally exposed to asbestos, who also smoke. The interaction between cigarette smoke and asbestos may be explained partly by differences in the kinetics of PAH cell uptake when PAHs are preadsorbed on asbestos (Fournier and Pezerat 1986). Plutonium oxide (PuO2) has also been shown to enhance benzo[a]pyrene-induced lung carcinogenesis following simultaneous inhalation of both compounds (Metivier et al. 1984). 

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