A comparison of the effects of sodium selenite and seleno-L-methionine on disposition of orally administered mercuric chloride.

Previous studies demonstrated extensive effects of the administration of selenite on the biokinetics of simultaneously injected inorganic mercury. As the results of simultaneous administration might well be of questionable value for the assessment of the interaction between mercury and selenium during the long-term exposures relevant for human beings, the present study was performed. The purpose of the present study was to compare the effects of prolonged oral exposure to sodium selenite and seleno-L-methionine (7.5, 37.5, or 75 mumol/L drinking water) on the biokinetics of a single oral dose of 203Hg-labelled mercuric chloride (5 or 25 mumol/kg b.w.) in mice. Both selenium compounds caused a dose-dependent decrease in the excretion of absorbed mercury, as indicated by a 2-7 fold increase in whole-body retention of mercury. Selenite caused a significantly higher whole-body retention of mercury at day 14 than did seleno-L-methionine. Both selenium compounds affected the relative deposition of mercury in most organs, but the effect depended on the type of selenium compound, on the dose of mercury as well as on the molar ratio between mercury and the selenium compound. The amounts of mercury deposited in the liver, kidneys and spleen increased, whereas the amounts deposited in the uteri and the brain were unaffected by the selenium supplementation. Significant differences in relative organ deposition of mercury between mice given selenite and mice given seleno-L-methionine were observed in the stomach, intestinal tract and the kidneys.(ABSTRACT TRUNCATED AT 250 WORDS)