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

Abstract

<jats:p> As an input to dose assessments, measurements have been made of the clearance of Pu and Am after subcutaneous implantation in rats for six particulate materials and one dust from the Maralinga test sites. The tissue distribution of Pu and Am were measured in groups of six animals at one month and 6 months after implantation. In addition, in vitro solubility tests were carried out on eight different particulate materials. Histological examination of the subcutaneous implantation site was undertaken after one year for selected materials. Autoradiographs of tissue sections showed that particles were surrounded by fibrotic tissue with macrophage and polymorphonuclear cell infiltration, the normal tissue response to foreign materials. The clearance data have been used to make estimates of the likely range in potential radiation doses in humans. To calculate the dose from dissolved <jats:sup>239</jats:sup>Pu and <jats:sup>241</jats:sup>Am, four different situations have been considered. For the dust, the results suggest that dissolution essentially ceases after the removal of Pu and Am from the surfaces of dust particles. From the values obtained, the acute release of a fraction of 10<jats:sup>-2</jats:sup> of both nuclides from a dust contaminated wound was assumed. For a number of particles the results suggested continued dissolution and the clearance of 10-3 per year of both nuclides, continuing for a number of years, has therefore been considered. For the least soluble particles, there was no clear evidence of continued clearance and the acute release of 10<jats:sup>-4</jats:sup> has therefore been taken as a lower estimate for dose calculations. To calculate radiation doses to lymphatic tissue the data were taken to suggest that, in general, a fraction of between 10 <jats:sup> -2</jats:sup> and 10<jats:sup>-4</jats:sup> may be translocated to the lymphatic system each year. </jats:p>

Take a Swipe at Actinide Bioavailability: Application of a New In Vitro Method

“…The assessment of the amount and physicochemical nature of radioactive contaminants has been carried out for many years using filters obtained from air monitoring devices and swipe tests. These are integral to radiation protection routine monitoring, assessment of accidental conditions, and nuclear forensics ( Lee et al 1982 ; Harrison et al 1993 ; Cheng et al 2004 ; Aladova et al 2007 ; Garger et al 2013 ; Bellucci et al 2013 ). Swipe tests can offer important information in the initial emergency phase, after inadvertent release of radioactive elements from industrial or military sources or resulting from detonation of a radioactive dispersal device (RDD) or an improvised nuclear device (IND).…”

“…In the case of filters obtained from air monitoring systems, in addition to isotopic and elemental analysis, the collected material has been used to assess the dissolution or transportability of different actinides such as Pu and U ( Lee et al 1982 ; Harrison et al 1993 ; Khokhryakov et al 1998 ; Cheng et al 2004 ; Aladova et al 2007 ; Garger et al 2013 ; Hansson et al 2022 ). Data from these measurements have contributed to the estimation of the bioaccessible and bioavailable fraction of the contaminants and to aid dose determination using ICRP biokinetic models ( ICRP 2019 ).…”

Increased retention of americium in kidneys as compared with plutonium in an actinide wound contamination model in the rat

“…For nuclear industry workers the most frequent actinide forms encountered are nitrates or oxides. However whatever the form, Am has been demonstrated in vitro to be more soluble than Pu (Eidson and Mewhinney 1983) as well as in vivo following diff erent modes of contamination such as ' simulated wounds ' or inhalation (Harrison et al 1993, Ramounet et al 2000, Paquet et al 2003, Van der Meeren and Gremy 2010, Griffi ths et al 2012). Due to this higher solubility Am has been shown to distribute more rapidly than Pu to tissues such as bone and liver that are the major retention organs for these actinides (ICRP 1986).…”