A study of mercury redistribution, excretion and renal pathology in guinea-pigs implanted with powdered dental amalgam for between 2 and 4 years.

Ten guinea-pigs were implanted subcutaneously with 2 x 25 mg of powdered amalgam for 2, 2.5, 3, 3.5, and 4 years, two animals at each time period. Five animals served as controls. Their diet contained 0.2 micrograms/g selenium (Se). In control animals no detectable mercury (Hg) was present in the liver, urine and faeces and only 0.11-0.18 micrograms/g was present in the kidneys, which were structurally normal. One control animal (3.5 year) had an epidermal tumour. In the implanted animals mean renal cortical Hg reduced from 116.1 micrograms/g at 2 years to 70.2 micrograms/g at 4 years and mean liver Hg ranged from 0.17 to 0.39 micrograms/g. The mean 24-h Hg excretion reduced to close to the detection limit by 45 moths. Proximal tubular cells contained HgSe deposits in lysosomes and nuclei. Renal pathology was seen in only two animals both of which also had abdominal tumours which almost certainly arose spontaneously and probably influenced the development of renal pathology to a major degree.