The interaction of arsenic and selenium compounds on the metabolism of these elements in golden hamsters was studied. Golden hamsters were divided into three groups and administered sodium selenite (Na,SeO,), sodium arsenite (NaAsO,) and Na,SeO, with NaAsO,, respectively, by a single subcutaneous injection of 25 pmol kg-' body weight as As or Se (arsenic and selenium were calculated as weight of elemental arsenic and selenium). Selenium and arsenic metabolites were determined by high-performance liquid chromatography-graphite furnace atomic absorption spectrometry (HPLC-GFA AA) and gas chromatography (GC). The results show (1): About 10% by weight of the given dose of selenium was excreted in expiration air as dimethylselenide (Me2Se) during 12 h after administration of Na,SeO,. Excretion of dimethylselenide with the respiratory air was inhibited by administration of Na,SeO, simultaneously with NaAsO,. (2) Giving Na,SeO, plus NaAsO, had no appreciable effect on the excretion of the trimethylselenonium ion (Me,Se+) into the urine and the feces. (3) Giving Na,SeO, plus NaAsO, increaed the excretion into the feces of an insoluble unknown-structure selenium compound, the proportion of which was 10.9% by weight of the given dose of selenium. (4) Giving NaAsO, plus Na,SeO, decreased the excretion of dimethylarsinic acid (Me,AsOOH) and inorganic arsenic into the urine during 120 h after the administration of the reagents, the decreased amount being 5.3% (dimethylarsinic acid) and 7.7% (inorganic arsenic) of the given dose of arsenic, respectively. (5) Giving NaAsO, plus Na,SeO, increased the excretion into feces of insoluble unknown-structure arsenic compound and inorganic arsenic, the increased amounts being 10.6% and 7.0% of the given dose of arsenic, respectively. (6) Giving NaAsO, plus Na,SeO, decreased * Author to whom correspondence should be addresxd.the excretion into feces of extractable unknownstructure arsenic compound, and the decreased amount was 4.9% of the given dose of arsenic. (7) It made little difference to the excretion of monomethylarsonic acid [MeAsO(OH),] into urine and feces and of dimethylarsinic acid (Me,AsOOH) into feces whether NaAsO, was administered alone or with Na,SeO,.
