The human alimentary tract transfer and body retention of environmental polonium-210

Abstract

This paper presents the results of a 4 year study to investigate the human alimentary tract transfer factor (f(A) value) and body retention of 210 Po in shellfish. In the first 3 years, mussels (Mytilus edulis L.), cockles (Cerastoderma edule L.) and brown meat from crab (Cancer pagurus L.) were successively studied. In each year five volunteers (from a pool of seven) ate a suitable portion of the shellfish and provided 24 h samples of excreta usually for 3 days before and for at least 7 days during and after eating. Subsamples of shellfish were analysed to determine the intakes of 210 Po. Faeces were analysed and the data used to assess apparent fA values. Urine samples were analysed in the mussel and crab studies to provide urinary excretion parameters. Pb-210 was also analysed during the mussel study; the levels were low, leading to large uncertainties, but confirming the negligible effect of radioactive decay to its granddaughter 210 Po in the main study. In the fourth year, larger samples of brown crab meat were eaten by five volunteers and faecal samples were taken at suitable times over periods of up to 43 days to study body retention of 210 Po. The first approximately 7 days provided additional data on fA values. Pooled results for the apparent fA for the whole study lay in the range 0.15-0.65 with a mean of 0.46; corrections for endogenous excretion suggest a true fA value of approximately 0.51, supporting the value of 0.5 currently used by the International Commission on Radiological Protection (ICRP). The retention data suggest a biological half-time of about 40 days, in broad consistency with the 50 days currently used by the ICRP. Thus there is no strong evidence from this study suggesting a change in dose coefficient for 210 Po. Full experimental data are provided to allow independent further interpretation.

Increase of 210Po levels in human semen fluid after mussel ingestion

“…This low 210 Po concentration fixed at 200 g (corresponding to the intake of 6.6 Bq of 210 Po) the amount of mussels the volunteers should eat. Based on Hunt and Rumney (2007) who studied the human alimentary tract transfer and body retention of environmental 210 Po from shellfish ingestion, this intake of 210 Po was believed to warrant its detection in semen fluid samples on a short term experience.…”

“…Our data showed that 210 Po reaches seminal fluid in a very short time (one day), but also for a very short period of time (maximum two days). Long-term retention was not investigated, but it might be anticipated that results should be inconclusive due to the very low levels of 210 Po normally observed in seminal fluid and the even lower concentrations that might be eliminated at long-term that are expected to be lower than the detection limit of our methodology (Hunt and Rumney, 2007).…”

Radionuclide exposure in animals and the public health implications

“…Measures for reducing radionuclide contamination in animals and their products Countermeasures aimed at reducing radionuclide contamination of food animals and their products usually involve treatment of land used for growing fodder crops or grazing, changes in animal management regime, administration of binding agents or analogues to animals, and delayed animal slaughter (53). Some adjustments (49) that can be made in animal management systems include permanent housing and provision of uncontaminated feedstuff (particularly in exposure situations resulting from a nuclear accident), pasture management (e.g., growing of forage species with low potential for radionuclide uptake), and selective grazing (54). Administration of binding or chelating agents to animals aims at reducing gut uptake of radionuclides.…”

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]. Human absorption of Po from foodstuffs is dependent on the food matrix and varies between 15 and 65 % [106].…”

“…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]. Human absorption of Po from foodstuffs is dependent on the food matrix and varies between 15 and 65 % [106].…”