Use of In Vivo Counting Measurements to Estimate Internal Doses From 241Am in Workers from the Mayak Production Association

Abstract

Comparisons between results of in vivo counting measurements of americium burden and results from radiochemical analyses of organ samples taken at autopsy of 11 cases of former Mayak workers were made. The in vivo counting measurements were performed 3-8 y before death. The best agreement between in vivo counting measurements for americium and autopsy data was observed for the skull. For lungs and liver, the ratios of burden measured by in vivo counting to those obtained from radiochemical analyses data ranged from 0.7-3.8, while those for the skull were from 1.0-1.1. There was a good correlation between the estimates of americium burden in the entire skeleton obtained from in vivo counting with those obtained from autopsy data. Specifically, the skeletal burden ratio, in vivo counting/autopsy, averaged 0.9 ± 0.1. The prior human americium model, D-Am2010, used in vivo counting measurements for americium in the skeleton to estimate the contents of americium and plutonium at death. The results using this model indicate that in vivo counting measurements of the skull can be used to estimate internal doses from americium in the Mayak workers. Additionally, these measurements may also be used to provide a qualitative assessment of internal doses from plutonium.

ICRP Publication 141: Occupational Intakes of Radionuclides: Part 4

“…There are also differences in the sites of deposition of americium and plutonium on bone surfaces, and perhaps associated differences in the net rate of removal of these elements from bone. (940) Sokolova et al. (2013, 2014) assessed the potential contributions of direct intake and in-vivo production of 241 Am to its total body content in a group of workers at the Mayak Production Association. The analysis was based on estimated quantities of 241 Am and 241 Pu at various work locations over time.…”

“…(940) Sokolova et al. (2013, 2014) assessed the potential contributions of direct intake and in-vivo production of 241 Am to its total body content in a group of workers at the Mayak Production Association. The analysis was based on estimated quantities of 241 Am and 241 Pu at various work locations over time.…”

Updated biokinetic model for systemic americium

“…Much additional information on Am biokinetics has been developed since the early 1990s, including measurements of retention and excretion of 241 Am in many workers with 241 Am burdens and post mortem measurements of 241 Am in tissues of some of those workers. The updated information for workers may be divided into two categories: data for intake of relatively pure 241 Am; and a much larger set of data for workers exposed mainly to Pu isotopes including 241 Pu but sometimes mixed with 241 Am in quantities that exceeded subsequent production of 241 Am from in vivo decay of 241 Pu (Sokolova et al 2013(Sokolova et al , 2014. Comparisons of the two data sets and consideration of some known differences in the systemic behaviour of Pu and Am in the human body indicate that 241 Am produced in vivo by decay of 241 Pu probably migrates to a large extent from 241 Pu over time and behaves as if entering blood as a parent radionuclide.…”

“…Thus, 241 Am produced in vivo by decay of 241 Pu may reflect some combination of the biokinetic characteristics of Am and distinctive characteristics of Pu. Sokolova et al (2013Sokolova et al ( , 2014 assessed the potential contributions of direct intake and in vivo production of 241 Am to its total body content in workers at the Mayak Production Association. The analysis was based on autopsy data, biokinetic models for Pu and Am, and consideration of the relative concentrations of 241 Am and Pu isotopes in air over time at different work locations at Mayak.…”