Plutonium toxicity

Comparative Toxicokinetics. There is limited information regarding comparative toxicokinetics among laboratory animal species and humans. However, similar target organs have been identified among laboratory animals exposed to plutonium. Toxic effects that have been observed in animals have not been observed in humans. In addition, hamsters develop many of the toxic effects in the lung... 

B. L. Cohen, Hazards from Plutonium Toxicity, Health Phys. 32, 359-379 (1977). 

Plutonium has a much shorter half-life than uranium (24.000 years for Pu-239 6,500 years for Pu-240). Plutonium is most toxic if it is inhaled. The radioactive decay that plutonium undergoes (alpha decay) is of little external consequence, since the alpha particles are blocked by human skin and travel only a few inches. If inhaled, however, the soft tissue of the lungs will suffer an internal dose of radiation. Particles may also enter the blood stream and irradiate other parts of the body. The safest way to handle plutonium is in its plutonium dioxide (PuOj) form because PuOj is virtually insoluble inside the human body, gi eatly reducing the risk of internal contamination. 

Work has also been conducted that involved the investigation, via infrared spectroscopy, of matrix-isolated, plutonium oxides (40), with the appropriate precautions being taken because of the toxicity of plutonium and its compounds. A sputtering technique was used to vaporize the metal. The IR spectra of PuO and PUO2 in both Ar and Kr matrices were identified, with the observed frequencies for the latter (794.25 and 786.80 cm", respectively) assigned to the stretchingmode of Pu 02. Normal-coordinate analysis of the PUO2 isotopomers, Pu 02, Pu 02, and Pu 0 0 in Ar showed that the molecule is linear. The PuO molecule was observed in multiple sites in Ar matrices, but not in Kr, with Pu 0 at 822.28 cm" in the most stable, Ar site, and at 817.27 cm" in Kr. No evidence for PuOa was observed. 

Jee WSS, Dell RB, Parks NJ, et al. 1985. Toxicity of plutonium and americium Relationship of bone composition to location of 226Ra, 239Pu and241 Am induced bone sarcomas. EUR 9250 155-174. 

Lindenbaum A, Rosenthal MW. 1972. Deposition patterns and toxicity of plutonium and americium in liver. Health Phys 22 597-605. 

Nenot JC, Stather JW. 1980. The toxicity of plutonium, americium, and curium Plutonium recycling in light water reactors. Oxford Pergamon Press. 

Taylor DM. 1989. The biodistribution and toxicity of plutonium, americium and neptunium. Sci Total Environ 83 217-225. 

The conceptual problems start when considering materials such as plutonium, which is a by-product of the nuclear electricity industry. Plutonium is one of the most chemically toxic materials known to humanity, and it is also radioactive. The half-life of 238Pu is so long at 4.5 x 108 years (see Table 8.2) that we say with some certainty that effectively none of it will disappear from the environment by radioactive decay and if none of it decays, then it cannot have emitted ionizing a and f) particles, etc. and, therefore, cannot really be said to be a radioactive hazard. Unfortunately, the long half-life also means that the 238Pu remains more-or-less for ever to pollute the environment with its lethal chemistry. 

But if we accept that plutonium is chemically toxic, then we must also recognize that the extent of its toxicity will depend on how the plutonium is bonded chemically, i.e. in what redox and chemical form it is present. As an example, note how soldiers were poisoned with chlorine gas during the First World War (when it was called Mustard Gas), but chloride in table salt is vital for life. Some plutonium compounds are more toxic than others. 

If we accept that plutonium is chemically toxic, then we also need to recognize that the extent of its toxicity will depend on how the plutonium is bonded chemically (see p. 59). 

Nuclear fission power plants were at one time thought to be the answer to diminishing fossil fuels. Although the enriched uranium fuel was also limited, an advanced nuclear reactor called breeders would be able to produce more radioactive fuel, in the form of plutonium, than consumed. This would make plutonium fuel renewable. Although plutonium has been called one of the most toxic elements known, it is similar to other radioactive materials and requires careful handling since it can remain radioactive for thousands of years. 

Plutonium is by far one of the most toxic radioactive poisons known. The metal, its alloys, and its compounds must be handled in a shielded and enclosed glove box that contains an inert argon atmosphere. It is a carcinogen that can cause radiation poisoning leading to death. 

Plutonium is not readily absorbed from the animal intestine (65), though on long continued low-level feeding some is taken up (79). There is some absorption through the lungs, and when it enters the body by this path or by injection, it localizes in the bones (64, 65). It is probably more toxic than radium under these conditions (65). It is not actually incorporated into the mineralized matter of the bone as is radium, but seems to concentrate in the cartilaginous portion (24). 

Dioxin (TCDD — 2,3,7,8-Tetrachlorodibenzoparadioxin) A by-product of Silvex herbicides production, more toxic than plutonium. 

Millions of radioactive sources exist around the world, usually distributed not only at nuclear power plants, but also medical radiotherapy facihties and industrial irradiators. Unfortunately, the radioactive materials housed in these places are often not under adequate control and are therefore susceptible to theft by terrorists.34 The appalling events of September 11, 2001, spawned a major international initiative to strengthen security for such materials and facihties worldwide. Highly toxic radionuchdes (plutonium radionuclides, 210Po or 137Cs) at trace level are increasingly being used as modern weapons to kill undesirable persons. 

The plutonium values are based on the assumption that 98% of the plutonium has been removed by reprocessing of the fuel. Relative toxicities smaller than 1 E-9 have been arbitrarily assumed to be negligible and hence are not included. 

The first organic derivative of DTPA to be screened for medicinal application was the pentaethyl ester which was examined for ability to reduce hepatic deposits of plutonium in mice120. Although superior to DTPA in removing plutonium from mice, this derivative was too toxic for further use. 

Transuranic Waste. Much of DOE s transuranic radioactive waste is classified as hazardous waste under RCRA and is managed as mixed waste (DOE, 1999b). Many transuranic wastes are hazardous due to the presence of toxic heavy metals or organic chemicals introduced into the waste during processing of plutonium. 

Plutonium is so toxic that processing and fabrication are always done in sealed cells or glove boxes, but accidental dispersions of aerosol occur from time to time. Following combustion of Pu metal chips in a production area at Rocky Flats, Colorado, in 1964, airborne contamination was widespread. Alpha tracks from individual particles caught on membrane filters were detected on nuclear film, and the Pu content, and hence the particle size, was deduced (Fig. 5.2, curve E). The activity median diameter was 0.3 /urn (Mann Kirchner, 1967). The same method, used during normal operations in a production area at Los Alamos, gave activity median diameters in the range 0.15 to 0.65 /urn (Moss et al., 1961). However, when a spill occurred, followed by clean-up operations, the Pu particles were found to be associated with inert dust particles of mass median diameter 7 /urn. 

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. 

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