The Mayak Worker Dosimetry System (MWDS 2013): Soluble Plutonium Retention in the Lungs of An Occupationally Exposed USTUR Case

Abstract

For the first time, plutonium retention in human upper airways was investigated based on the dosimetric structure of the human respiratory tract proposed by the International Commission on Radiological Protection (ICRP). This paper describes analytical work methodology, case selection criteria, and summarizes findings on soluble (ICRP 68 Type M material) plutonium distribution in the lungs of a former nuclear worker occupationally exposed to plutonium nitrate [Pu(NO)]. Thirty-eight years post-intake, plutonium was found to be uniformly distributed between bronchial (BB), bronchiolar (bb) and alveolar-interstitial (AI) dosimetric compartments as well as between the left and right lungs. Pu andPu total body activity was estimated to be 2333 ± 23 and 42.1 ± 0.7 Bq, respectively. The results of this work provide key information on the extent of plutonium binding in the upper airways of the human respiratory tract.

Plutonium in Manhattan Project workers: Using autopsy data to evaluate organ content and dose estimates based on urine bioassay with implications for radiation epidemiology

“…The isolated plutonium is electroplated, and 239+240 Pu is measured by alpha spectrometry. The process was described elsewhere [ 30 – 33 ].…”

ICRP Publication 150: Cancer Risk from Exposure to Plutonium and Uranium

“…Recently, ICRP (2019) has reviewed human and animal studies following inhalation of plutonium nitrate to derive specific absorption parameter values. An s s value of 2.0 × 10 −3 day −1 was recommended based on: long-term monkey and dog studies with follow-up periods of 8 years and 15 years, respectively (Brooks et al., 1992; Dagle et al., 1993; Puncher et al., 2017b; Pellow et al., 2019); analysis of autopsy and bioassay data of USTUR Case 0269, a plutonium worker who inhaled plutonium nitrate (James et al., 2007; Puncher et al., 2017a; Tolmachev et al., 2017); and the volunteer experiment discussed above (Puncher and Etherington, 2016). (67) It was noted that a large fraction dissolving at a slow rate ( s s = 2.5 × 10 −4 day −1 ), as reported for the MWC based on autopsy data, was inconsistent with the results of the USTUR and the long-term dog and monkey studies, but it was considered that a slow rate could apply to higher levels of exposures (ICRP, 2019). The data available suggest that the different time scales of the volunteer study (approximately 4 months) and the Mayak autopsy data (>5 years) cannot explain the discrepancy in the assessed s s values for the SWC and MWC.…”

“…Approximately 33% of the alveolar deposit of insoluble particles is assumed to be sequestered in the interstitium, and as such is not subject to particle transport other than very slow clearance to lymph nodes. Sequestration to the interstitium of relatively insoluble forms of plutonium is consistent with observed long-term retention in the lungs of Mayak workers. (52) Circumstantial evidence of a bound state for plutonium comes from a re-analysis of historic beagle dog data where dogs were exposed to plutonium nitrate and followed for 15 years (Puncher et al., 2017b); and autopsy data of a US Trans-Uranium and Uranium Registries (USTUR) whole-body donor (Case 0269), a plutonium worker who inhaled plutonium nitrate (Puncher et al., 2017a; Tolmachev et al., 2017). In both cases, a bound state was required to fit the late retention data.…”

The Mayak Worker Dosimetry System (Mwds-2013): An Introduction to the Documentation

“…The three articles using human evidence are led by Tolmachev et al . ( 5 ) with a description of a study of long-term retention of plutonium nitrate in the lungs of a US Transuranium and Uranium Registries donor. For the first time, plutonium distribution in human upper airways was investigated based on the dosimetric structure of the human respiratory tract proposed by the International Commission on Radiological Protection (ICRP) ( 6 ) .…”

“…The data collected in the Tolmachev et al . ( 5 ) study is further analyzed by Puncher et al . ( 7 ) using a novel Bayesian analysis to determine the value of the bound fraction parameter.…”