“…Selenium and molybdenum--and possibly cadmium, cobalt, copper, and zinc--may be exceptions, however, since feed and food crops grown on soils receiving sludge at rates within EPA standards may contain levels of Mo, Se, and possibly Cd sufficiently high to arouse concern. It has been shown, for example, that when selenium is added to soils to a level of approximately 2 kg, it results in toxic levels of Se in forage crops (Sharma, 1983). Information on the concentrations of Se present in sewage sludges, while not extensive, tends to suggest that repeated applications of sludge to the soil could cause forage to absorb sufficient quantities of Se to be toxic to foraging animals.…”