Polonium-210 as a poison

Abstract

The death of Alexander Litvinenko on 23 November 2006 has brought into focus scientific judgements concerning the radiotoxicity of polonium-210 ((210)Po). This paper does not consider the specific radiological circumstances surrounding the tragic death of Mr Litvinenko; rather, it provides an evaluation of published human and animal data and models developed for the estimation of alpha radiation doses from (210)Po and the induction of potentially fatal damage to different organs and tissues. Although uncertainties have not been addressed comprehensively, the reliability of key assumptions is considered. Concentrating on the possibility of intake by ingestion, the use of biokinetic and dosimetric models to estimate organ and tissue doses from (210)Po is examined and model predictions of the time-course of dose delivery are illustrated. Estimates are made of doses required to cause fatal damage, taking account of the possible effects of dose protraction and the relative biological effectiveness (RBE) of alpha particles compared to gamma and x-rays. Comparison of LD(50) values (dose to cause death for 50% of people) for different tissues with the possible accumulation of dose to these tissues suggests that bone marrow failure is likely to be an important component of multiple contributory causes of death occurring within a few weeks of an intake by ingestion. Animal data on the effects of (210)Po provide good confirmatory evidence of intakes and doses required to cause death within about 3 weeks. The conclusion is reached that 0.1-0.3 GBq or more absorbed to blood of an adult male is likely to be fatal within 1 month. This corresponds to ingestion of 1-3 GBq or more, assuming 10% absorption to blood. Well-characterised reductions in white cell counts would be observed. Bone marrow failure is likely to be compounded by damage caused by higher doses to other organs, including kidneys and liver. Even if the bone marrow could be rescued, damage to other organs can be expected to prove fatal.

Health Risk Evaluations for Ingestion Exposure of Humans to Polonium-210

“…Absorption of Po-210 is reported to possibly have reached 10 % (f 1 = 0.1); however, the authors indicated that the estimate was largely conjectural and may have been considerably overestimated. Higher values for f 1 have been reported when Po-210 is ingested in foods (Harrison et al 2007).…”

“…Target cells may therefore include vascular endothelial cells, mesenchymal fibroblast and other cell types (Harrison et al 2007). Animal data revealed an association between ingested Po-210 and intestinal tissue.…”

“…The parameter λ relates to the effective retention halftime (T 1/2 ) of Po-210 in bone marrow according to the equation λ = ln(2)/T 1/2 . Total-body retention of Po-210 has been reported to decrease exponentially with an effective retention half-time from about 30 to 60 days (Harrison et al 2007). It is assumed that Equation 4 can be applied to Po-210 that enters the blood and is taken up by bone marrow since it quickly enters the bone marrow from the blood (Harrison et al 2007).…”

Biotransformation of metal(loid)s by intestinal microorganisms

“…210 Po, which has gained considerable attention after the intoxication of Alexander Litvinenko [105], is a naturally occurring radioisotope (T ½ = 138.4 d) of the U radioactive series. 210 Po was estimated to contribute to 60 % of the average world individual effective dose from ingestion of radionuclides from the U and Th series [106].…”

The Polonium-210 Public Health Assessment: The Need for Medical Toxicology Expertise in Radiation Terrorism Events

“…The events of November 2006, however, stimulated and reinvigorated worldwide interest in this relatively obscure element, and those events prompted the authoring of many new articles in the literature about its toxicity and the public health response to this event [16][17][18][19][20][21][22][23][24]. Articles concerning the "biological behavior" of this element have expanded our knowledge about its potential use as a poison.…”