Polonium-210 and Caesium-137 in lynx (Lynx lynx), wolverine (Gulo gulo) and wolves (Canis lupus).

Wolves, lynx and wolverines are on the top of the food-chain in northern Scandinavia and Finland. (210)Po and (137)Cs have been analysed in samples of liver, kidney and muscle from 28 wolves from Sweden. In addition blood samples were taken from 27 wolves. In 9 of the wolves, samples of muscle, liver and blood were analysed for (210)Po. Samples of liver and muscle were collected from 16 lynx and 16 wolverines from Norway. The liver samples were analysed for (210)Po and (137)Cs. Only (137)Cs analyses were carried out for the muscle samples. The wolves were collected during the winter 2010 and 2011, while the samples for lynx and wolverines were all from 2011. The activity concentrations of (210)Po in wolves were higher for liver (range 20-523 Bq kg(-1) d.w.) and kidney (range 24-942 Bq kg(-1) d.w.) than muscle (range 1-43 Bq kg(-1) d.w.) and blood (range 2-54 Bq kg(-1) d.w.). Activity ratios, (210)Po/(210)Pb, in wolf samples of muscle, liver and blood were in the ranges 2-77, 9-56 and 2-54. Using a wet weight ratio of 3.8 the maximal absorbed dose from (210)Po to wolf liver was estimated to 3500 µGy per year. Compared to wolf, the ranges of (210)Po in liver samples were lower in lynx (range 22-211 Bq kg(-1) d.w.) and wolverine (range16-160 Bq kg(-1) d.w.). Concentration of (137)Cs in wolf samples of muscle, liver, kidney and blood were in the ranges 70-8410 Bq kg(-1) d.w., 36-4050 Bq kg(-1) d.w., 31-3453 Bq kg(-1) d.w. and 4-959 Bq kg(-1) d.w., respectively. (137)Cs in lynx muscle and liver samples were in the ranges 44-13393 Bq kg(-1) d.w. and 125-10260 Bq kg(-1) d.w. The corresponding values for (137)Cs in wolverine were 22-3405 Bq kg(-1) d.w. for liver and 53-4780 Bq kg(-1) d.w. for muscle. The maximal absorbed dose from (137)Cs to lynx was estimated to 3000 µGy per year.

Relative biological effectiveness (RBE) of 210Po alpha-particles versus X-rays on lethality in bovine endothelial cells.

PURPOSE: Alpha-radiation from polonium-210 ((210)Po) can elevate background radiation dose by an order of magnitude in people consuming large quantities of meat and seafood, particularly caribou and reindeer. Because up to 50% of the ingested (210)Po body burden is initially found in the blood, a primary target for the short range alpha-particles is the endothelial cells lining the blood vessels. This study examined the relative biological effectiveness (RBE) of (210)Po alpha-particles versus 250 kVp X-rays in producing injury to cultured bovine aortic endothelial cells. MATERIALS AND METHODS: Radiation effects on cells were measured in four different ways: the percentage viable cells by trypan blue dye exclusion, the number of live cells, the lactate dehydrogenase (LDH) release to medium and the ability to form colonies (clonogenic survival). RESULTS: Comparison of dose-response curves yielded RBE values of 13.1+/-2.5 (SEM) for cell viability, 10.3+/-1.0 for live cell number and 11.1+/-3.0 for LDH activity. The RBE values for clonogenic survival were 14.0+/-1.0 based on the ratio of the initial slopes of the dose-response curves and 13.1, 9.9 and 7.7 for 50, 10 and 1% survival rate, respectively. At X-ray doses <0.25 Gy, a pronounced stimulatory effect on proliferation was noted. CONCLUSIONS: Exposure to (210)Po alpha-particles was seven to 14 times more effective than X-ray exposure in causing endothelial cell damage.

A systemic biokinetic model for polonium.

Although the biokinetics of polonium has been studied extensively, interpretation of the data is complicated by potential differences with species and route of exposure and the questionable reliability of much of the reported excretion data for man. A study was undertaken to identify the data that are most likely to represent the typical behavior of polonium and apply those data to construct an improved, physiologically realistic systemic biokinetic model for polonium in man. Such a model is needed for interpretation of urinary excretion data for workers exposed to 210Po and reconstruction of the radiation doses received by those workers. This paper reviews the database on the biokinetics of polonium and describes a new systemic biokinetic model for polonium in man.

Evaluation of the contribution of smoking to total blood polonium-210 in Saudi population.

A preliminary study of 210Po concentrations in the blood of some smokers and nonsmokers is presented in order to evaluate the contribution of smoking to total blood 210Po in Saudi population. Blood samples were collected from 30 volunteers and analyzed by high resolution alpha-spectrometry using a radiochemical technique. The technique is based on the separation of polonium from other components of the sample by wet ashing with an HNO3/H2O2 oxidizing mixture and spontaneous deposition on a silver disc under the relevant conditions for alpha-particle counting. The results indicated that a significant fraction (about 30%) of blood 210Po is related to smoking.

Relative effectiveness of dithiol and dithiocarbamate chelating agents in reducing retention of polonium-210 in rats.

Nine different sulphur-based chelators, including dithiols and dithiocarbamates, were examined for their ability to remove Po-210 from the rat. In general, treatments merely caused a redistribution of Po-210 in the body. Greatest reduction of Po-210 in blood was achieved by 2,3-dimercaptopropanol (BAL), sodium diethyldithiocarbamate (DDTC), and N-(2,3-dimercaptopropyl) phthalamidic acid (DMPA). Nearly all the compounds tested decreased Po-210 in the spleen and muscle. On the other hand, BAL and DDTC substantially increased the accumulation of Po-210 in the brain while DMPA, DMPS (sodium 2,3-dimercaptopropane-1-sulphonate) and DMSA (meso-2,3-dimercaptosuccinic acid) increased by several times the Po-210 in kidneys. A less pronounced increase of Po-210 was sometimes observed in liver (due to DDTC and DMPA) and in muscle (due to BAL and DDTC). Three of the dithiocarbamates (BGDTC, MeOBGDTC and BLDTC) did not increase accumulation of Po-210 in the brain and muscle but they reduced Po-210 in blood to a lesser degree than DDTC. A derivative of DMSA (Mi-ADMS) reduced Po-210 in blood, bone and muscle more than DMSA, but at the same time increased Po-210 in the kidney. When BAL or DDTC were combined with other agents there was a greater reduction in the whole-body burden of Po-210. Removal of Po-210 from the bone, spleen and kidneys by BAL was increased by repeated treatment. However, under similar experimental conditions the effect of a single injection of BAL on Po-210 in blood was less pronounced when the period of observation was prolonged. Total-body retention of Po-210 could not be reduced to less than 85% of the untreated controls by any of the chelators tested. In spite of this some of them (BAL, DMPS, DMSA, DMPA) could still have a useful role in reducing the toxicity of Po-210.