The distribution and biological half-time of 203Hg in the human body according to a modified whole-body counting technique.

The distribution and biological half-life of 203Hg in the human body was investigated using 203Hg-labeled compounds and a regional whole-body counting technique. Fifteen volunteers were administered methylmercury as a labeled fish proteinate. A single serving of the proteinate contained an average of 1.8 uCi of 203Hg-activity and 22 mug of total mercury. Inorganic mercury was given to eight volunteers as labeled calf liver paste containing 4-8 muCi of inorganic 203Hg-activity and 6 mug of total mercury. The radiomercury determinations were performed in a steel room equipped with the standard chair geometry and one 4 inch x 8 inch NaI(Tl) crystal. For determinations of 203Hg-activity in the head a 3 inch x 3 inch NaI(Tl) crystal was used. A lead collar was utilized as a shield in order to absorb any disturbing radiation that might originate in the stomach region. The effectiveness of the Pb collar was determined using phantoms. The activities in the whole-body, the head, the legs and the liver were determined. About 20% of the methylmercury activity in the whole-body was found to be localized in the head 30 d after administration. No significant amounts of 203Hg-activity were found in the head during the first 58 d after administration of inorganic mercury. An average value of 10-15% methylmercury activity was found in the legs 30 d after administration. A control mean value of 13% was determined by measuring five of the same volunteers the next day in Sweden. Not more than 1% of inorganic mercury was found in leg muscle after 39 d in one male volunteer. The biological half-life of protein-bound inorganic mercury in the liver region, studied in one male volunteer, was estimated at 53 +/- 15 d.