Cadmium, lead and zinc in growing rats fed corn leaf tissue grown on soil amended with sewage sludge or heavy metal salts.

Rats were fed, from weaning through 11 weeks of age, dried leaf tissue of corn plants grown on soil amended with regular NPK fertilizer (150-22-62), with 33.6 ad 67.2 metric ton/ha of sewage sludge or with salts of cadmium (10kg/ha), lead (25kg/ha), and/or zinc (50kg/ha). A very high proportion of the cadmium (cd) consumed was eliminated in feces. Only in rats fed diets containing leaf tissue from plants grown on soil to which CdCl2 salt or the high level of sludge had been added did the metal accumulate in significantly greater quantity than in rats fed a standard diet without leaf tissue. Most of the carcass accumulation of Cd could be accounted for by that in the liver and kidneys. The proportion of dietary zinc (Zn) that was excreted in feces was less than that for Cd, indicating that more Zn was absorbed into the body. There was no correlation between intake and accumulation of Zn in the tissues, however, so that much of the absorbed Zn must have been eliminated in some way. Fecal elimination did not serve as a way to rid the body of excessive intake of lead (Pb). However, with intakes ranging from 2 to 11 mg total in this study, the carcass load did not exceed 1.1 mg of Pb. Thus absorbed Pb, like Zn, must also be eliminated efficiently. No gross signs of toxicity or of physiological impairment were observed in rats fed any of the plant tissue samples.