Review of Chemical and Radiotoxicological Properties of Polonium for Internal Contamination Purposes

Abstract

The discovery of polonium (Po) was first published in July, 1898 by P. Curie and M. Curie. It was the first element to be discovered by the radiochemical method. Polonium can be considered as a famous but neglected element: only a few studies of polonium chemistry have been published, mostly between 1950 and 1990. The recent (2006) event in which (210)Po evidently was used as a poison to kill A. Litvinenko has raised new interest in polonium. 2011 being the 100th anniversary of the Marie Curie Nobel Prize in Chemistry, the aim of this review is to look at the several aspects of polonium linked to its chemical properties and its radiotoxicity, including (i) its radiochemistry and interaction with matter; (ii) its main sources and uses; (iii) its physicochemical properties; (iv) its main analytical methods; (v) its background exposure risk in water, food, and other environmental media; (vi) its biokinetics and distribution following inhalation, ingestion, and wound contamination; (vii) its dosimetry; and (viii) treatments available (decorporation) in case of internal contamination.

Variation of 210Po daily urinary excretion for male subjects at environmental level

“…is subject to hydrolysis. In the presence of inorganic or organic ligands, polonium forms complex species (Ansoborlo et al 2012). However, two important findings concerning the fate of polonium in any biological medium provide some understanding of its behaviour in the human body.…”

A study on the effect of the internal exposure to 210Po on the excretion of urinary proteins in rats

“…Similar tissue distribution results were also observed in a previous study on the metabolism of 210 Po in rats, where 9-18, 2.9-9.7, 0.9-3.3 and 0.5-1.5 % of the injected activity was localized in the liver, kidney, spleen and lung, respectively, 4 days following intravenous administration (Li et al 2011a). Early distribution of polonium in target organs and tissues as determined in baboons, dogs and a human subject indicates that, in general, the liver (*35 %), kidney (*5 %), red bone marrow (*5 %) and spleen (*2 %) concentrate polonium more than other tissue except for temporary deposition in the lung after inhalation of an insoluble form (Leggett and Eckerman 2001;Ansoborlo et al 2012). These values have since been revised after the International Commission on Radiological Protection (ICRP) Publication 67 model, with a distribution corresponding to liver (30 %), kidney (10 %), bone marrow (10 %) and spleen (5 %) (ICRP 1993).…”

“…These values have since been revised after the International Commission on Radiological Protection (ICRP) Publication 67 model, with a distribution corresponding to liver (30 %), kidney (10 %), bone marrow (10 %) and spleen (5 %) (ICRP 1993). These studies (Li et al 2011a;Leggett and Eckerman 2001;Ansoborlo et al 2012;ICRP 1993) suggest that after internal exposure, a relatively high proportion of 210 Po localize in the liver compared to the other organs or tissues. One of the major metabolic functions of liver is the formation of plasma proteins.…”

Poisonous polonium

“…Isotope 210 Po is almost exclusively an alpha emitter with a half-life of 138.4 days. Consequently, it is both highly radioactive and highly toxic 3 . Because of its radiotoxicity, the fact that it volatilizes at low temperature (~50 °C) and that it sticks rather avidly to glass, it is difficult to handle, and therefore its chemistry remains only poorly known 4 .…”

“…It is also a concentrated source of heat, and small neutron sources can be prepared by mixing it with beryllium. It is perhaps most widely known, though, as a rare but highly toxic poison that targets the liver 3 and also affects the bone marrow, gastrointestinal and central nervous systems. The lethal dose for humans is estimated to be fewer than 10 μg, and its radiotoxicity was demonstrated soon after its discovery, when the accidental release of polonium from a distillation vessel in the Curie lab caused the death of a technician.…”