Cadmium from soil amended with sewage sludge: effects and residues in swine

Liquid digested sewage sludge from a Chicago waste treatment plant was applied to experimental corn plots starting in 1968. The treatment plant received a high proportion of industrial effluent and the sludge averaged about 200 ppm Cd (dry weight). Corn grain harvested from the plots in 1974 was fed to growing swine for 56 days, and other swine were permitted to forage on the plots during the winters of 1975-76 and 1976-77. The sludge-fertilized corn contained higher concentrations of nutrient and toxic elements, but did not interfere with swine performance. Minor changes in hepatic microsomal oxidases and red blood cells accompanied significant increases in renal Cd and decreases in hepatic Fe. Swine foraging on these plots ingested considerable amounts of sludge soil and accumulated significantly higher concentrations of renal Cd. At lower rates of sludge application the swine outperformed those foraging both on control plots and those receiving heavy sludge applications in terms of weight gain, in-utero piglet survival, blood hemoglobin, and tissue Fe concentrations.