Toxicity of trimethylselenonium chloride in the rat with and without arsenite

Abstract

Trimethylselenonium chloride (TMSeCl) was submitted to a toxicologic evaluation in rats. The ip LD50 was 49.4 mg Se/kg. In the presence of 4 mg of As/kg injected as arsenite, the LD50 was reduced to 2–3 mg Se/kg. The toxicity of trimethylsulfonium iodide was similar to that for TMSeCl, but arsenite had no effect. To further examine the apparent synergism between arsenite and TMSeCl, the effect of arsenic on the elimination of TMSe-selenium in the breath and in the urine was studied. At different levels of selenium administration, 3–9% was exhaled, and this amount was increased by the injection of arsenite. On the other hand, arsenite injection reduced urinary selenium excretion. It was also found that arsenite and dimethyl selenide (DMSe) were more toxic in combination than when injected individually, but arsenite did not affect the exhalation of Se from DMSe. When TMSeCl was fed, levels above 240 ppm Se were required to reduce growth, and even at a level of 960 ppm Se, no deaths were observed in a 5-wk experimental period. The presence of arsenite in the diet slightly increased the toxicity of the TMSeCl administered in the diet at intermediate levels of selenium.