Study of guinea pigs fed Swiss chard grown on municipal sludge-amended soil. Multi-element content of tissues.

Swiss chard, field-grown on soil amended with 100 dry tons per acre of municipal sewage sludge from Washington, DC, was fed to guinea pigs for 28 days. Control animals were fed Swiss chard grown on unfortified soi. Forty-one elements were determined in the sludge, the plant material, and liver, kidney, muscle, adrenal, and spleen tissues by neutron activation and other methods. Elevated concentrations of several elements found in the Swiss chard grown on the sludge-soil mixture also appeared at higher levels in certain of the animal tissues. These included antimony in adrenal, cadmium in kidney, manganese in liver tissues, and tin in several tissues. The animals showed no observable toxicological effects.