USTUR whole body case 0262: 33-y follow-up of Puo2 in a skin wound and associated axillary node

Abstract

This whole body donation case (USTUR Registrant) involved two suspected PuO2 inhalation intakes, each indicated by a measurable Pu alpha activity in a single urine sample, followed about 1(1/2) y later by a puncture wound to the thumb while working in a Pu glovebox. The study is concerned with modelling simultaneously the biokinetics of deposition and retention in the respiratory tract and at the wound site; and the biokinetics of Pu subsequently transferred to other body organs, until the donor's death. Urine samples taken after the wound incident had readily measurable Pu alpha activity over the next 14 y, before dropping below the minimum detectable excretion rate (<0.4 mBq d(-1)). The Registrant died about 33 y after the wound intake, at the age of 71, from hepatocellular carcinoma with extensive metastases. At autopsy, all major soft tissue organs were harvested for analysis of their 238Pu, 239+240Pu and 241Am content. The amount of 239+240Pu retained at the wound site was 68 +/- 7 Bq (1 SD), measured by low-energy planar Ge spectrometry. A further 56.0 +/- 1.2 Bq was retained in an associated axillary lymph node, measured by radiochemistry. Simultaneous mathematical analysis (modelling) of all in vivo urinary excretion data, together with the measured lung, thoracic lymph node, wound, axillary lymph node and systemic tissue contents at death, yielded estimated intake amounts of 757 and 1504 Bq, respectively, for the first and second inhalation incidents, and 204 Bq for the total wound intake. The inhaled Pu material was highly insoluble, with an estimated long-term absorption rate from the lungs of 2 x 10(-5) d(-1). The Pu material deposited at the wound site was mixed: approximately 14% was rapidly absorbed, approximately 49% was absorbed at the rate of about 6 x 10(-5) d(-1), and the remainder ( approximately 37%) was absorbed extremely slowly (at the rate of about 5 x 10(-6) d(-1)). Thus, it was estimated that only approximately 40% of the Pu initially deposited in the wound had been absorbed systemically over the 33-y period until the donor's death. The biokinetic modelling also indicated that, in this individual case, some of the parameter values (rate constants) incorporated in the ICRP Publication 67 Pu model were up to a factor of 2 different from ICRP's recommended values (for reference man).

Reevaluation of USTUR Plutonium Wound Case 0262 Using Bayesian Methodology and New Data

“…Evaluation of NCRP Report 156 model predictions According to the analysis of James et al (2007), the plutonium in the wound contamination was predominately composed of ''insoluble particles'' (86%). Although no plutonium fragments were observed to be deposited in the wound, the long term wound/lymph node retention of plutonium is better characterized by the NCRP Report 156 recommended values for ''fragment'' deposition than for any other categories of deposition.…”

“…Accordingly, the calibrated value of the total 239 Pu activity retained in the wound as a whole is 103 T 7 Bq (1 S.D. ), which is 51% higher than the value assumed by James et al in 2007. The additional amount of 56 T 1 Bq (1 S.D.) retained in the associated lymph node adopted for analysis by James et al (2007) was accurate, since this was determined by radiochemical analysis of the digested lymph node.…”

“…), which is 51% higher than the value assumed by James et al in 2007. The additional amount of 56 T 1 Bq (1 S.D.) retained in the associated lymph node adopted for analysis by James et al (2007) was accurate, since this was determined by radiochemical analysis of the digested lymph node. Accordingly, the total amount of 239 Pu retained in the wound and lymph node (combined) at the time of death was 159 T 7 Bq (1 S.D.).…”

“…The measured quantity of radioactivity on this wound tissue sample was 68 T 7 Bq ). James et al (2007) analyzed the biokinetics of USTUR Case 0262 given the urinalysis and postmortem tissue analysis data. This was done using the rate matrix method (Birchall and James 1989) to solve in successive time steps an empirical (multiexponential compartment) wound/lymph node model combined with the ICRP Publication 67 plutonium biokinetic model (ICRP 1993).…”

“…After the James et al (2007) study was published, an additional (previously unrecorded) sample of wound tissue was located in the National Human Radiobiological Tissue Repository. The additional 239 Pu content of this sample (again measured using a LEGe detector at PNNL) was found to be 97 T 13 Bq (1 S.D.).…”