BIOACCUMULATION AND METABOLIC-FATE OF SEWAGE-SLUDGE DERIVED ORGANIC XENOBIOTICS IN PLANTS

Sewage sludges will always contain a very complex mixture of organic c ontaminants. Therefore, information is needed to provide data on the p ersistence of these sludge derived organics in soils and their uptake by food crops. The results of this study demonstrate that all compound s, even non-polar ones, are assimilated by intact plants and different in vitro systems. Uptake depended on the plant species and on the phy sico-chemical properties of the chemicals. The main metabolites being formed are polar conjugates with carbohydrates and amino acids. Polycy clic aromatic hydrocarbons (PAHs) are partly converted to oxygenated d erivatives which are known to be even more toxic. Depending on the pla nt species, and especially in monocots, large amounts of the chemicals and/or their metabolites, are frequently incorporated into non-extrac table residues. The association, and type of binding to cell wall comp onents, enable conclusions to be made about the bioavailability of the se bound residues.