Half-time studies of mercury and cadmium by whole-body counting

Abstract

The retention and elimination rates of protein-bound methylmercury (MeHg) and mercury (Hg) in man were investigated using /sup 203/Hg-labelled compounds and a whole-body counting technique. Similarly, the retention and elimination rate of cadmium (Cd) was studied using /sup 115m/Cd. Fifteen subjects, six female and nine male, were administered about 2 ..mu..Ci each of Me/sup 203/Hg incorporated in fish-muscle protein. Eight subjects, three female and five male, received 4-8 ..mu..Ci each of /sup 203/Hg in calf-liver protein. The female subjects were given 4 and 14 ..mu..Ci, respectively, of /sup 203/Hg(NO/sub 3/)/sub 2/ in water solution. Whole-body counting of the subjects was performed in an iron room using a standard chair geometry and one 4-in. X 8-in. NaI(Tl) crystal. Faeces, urine and blood samples were also collected and counted. The resorption and excretion of cadmium was investigated by administering, to each of five male volunteers, one oral dose of about 5 ..mu..Ci of mostly protein-bound /sup 115m/Cd (containing 100 ..mu..g elemental Cd) served in a calf-kidney suspension. Measurements were made of the radioactivity contained in the whole blood, red cells, plasma, faeces and urine. Preliminary results show that during the first three days about 70% of the /sup 115m/Cd is excreted in the faeces and the urine, and that at least two components exist in the excretion function: a fast one with a half-time of 2.2 +/- 0.3 days and a slow one corresponding to 6% of the dose and having a half-time of not less than a few hundred days.