The toxicity of orally ingested arsenic, selenium, tellurium, vanadium, and molybdenum
The effects of sodium-arsenite (13466063), ammonium-molybdate (12027677), sodium-tellurate (10101834), sodium-tellurite (10102202), sodium-vanadate (13718268), and sodium-selenate (13410010), on growth and hemoglobin concentrations were studied in rats. Wistar-rats were fed salts of these elements at levels of 25 or 50 parts per million (ppm) of their diets. The effects upon growth, food consumption, mortality, and hemoglobin levels were examined. The rats were killed on the day 100 and autopsied. Only one rat given selenium lived 100 days, even at the 25ppm concentration. At the 50ppm concentration of selenium, the rats lived only a short time and lost body weight. At 25ppm arsenic and molybdenum had no effect on body weight. At 50ppm, a slight decrease in growth rate was seen. Tellurium produced lower body weights and lower food consumption. Vanadium produced lower body weights at 100 days. Rats receiving vanadium, especially at 50ppm, suffered diarrhea throughout the experiment. Of the five elements studied, selenium was the only one which affected hemoglobin concentrations; concentrations of hemoglobin were reduced and the rats with low hemoglobin died. The authors conclude that selenium was the most toxic of the elements investigated. The toxicity of the other elements decreased in the following order: vanadium, tellurium, molybdenum, and arsenic. All of these elements are present in soils of the western United States in concentrations high enough to produce toxic vegetation.