Inventory of heavy metal content in organic waste applied as fertilizer in agriculture: evaluating the risk of transfer into the food chain

22 páginas, 2 figuras, 5 tablas.-- The final publication is available at www.springerlink.com

Background, aim, and scope In this work, an environmental risk assessment of reusing organic waste of differing origins and raw materials as agricultural fertilizers was carried out. An inventory of the heavy metal content in different organic wastes (i.e., compost, sludge, or manure) from more than 80 studies at different locations worldwide is presented. Materials and methods The risk analysis was developed by considering the heavy metal (primarily Cd, Cu, Ni, Pb, and Zn) concentrations in different organic residues to assess their potential environmental accumulation and biotransfer to the food chain and humans. A multi-compartment model was used to estimate the fate and distribution of metals in different environmental compartments, and a multi-pathway model was used to predict human exposure. Results The obtained hazard index for each waste was concerning in many cases, especially in the sludge samples that yielded an average value of 0.64. Among the metals, Zn was the main contributor to total risk in all organic wastes due to its high concentration in the residues and high biotransfer potential. Other more toxic metals, like Cd or Pb, represented a negligible contribution.

This work was supported by the Spanish Government (Science and Innovation Ministry) through the Project INDIE (CTM2010-18893). Marta Herva wishes to thank the University of Santiago de Compostela for her pre-doctoral contract. Dr. Amaya Franco-Uría would like to thank MICINN for the support provided by the “Juan de la Cierva” Subprogram.

Peer reviewed