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

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.