On the long-term behaviour of Ag-110m in the soil-plant system and its transfer from feed to pig

The long-term transfer of radiosilver from soil to pasture grass was invest igated over 5 years on an undisturbed pasture using stable silver (Ag-109) isotope as a tracer. The silver content of all the samples was determined b y neutron activation analysis. The temporal change of the Ag+ uptake into f orage was negligible mainly due to the low mobility of silver in the soil ( orthihumic-gleysol). The mean grass/soil concentration factor levelled out at 1.3 +/- 0.5 x 10(-2) during the 59-month observation period. In a 30-day feeding experiment with pigs, Ag-110m was used to determine distribution a nd retention. The internal distribution of Ag-110m showed the liver to be t he most contaminated tissue. The highest Ag-110m retention was found in the brain. The biological half-lives obtained for the liver and the brain were 35 and 136 days, respectively. (C) 2000 Elsevier Science Ltd. All rights r eserved.