title: Inventory of heavy metal content in organic waste applied as fertilizer in agriculture: evaluating the risk of transfer into the food chain.
abstract: OBJECTIVE
  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.
  
  
  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.
  
  
  CONCLUSIONS
  These results suggest that the Zn content in organic waste should be reduced or more heavily regulated to guarantee the safe management and reuse of waste residues according to the current policies promoted by the European Union.
authors.affiliation: Sustainable Processes and Products Engineering and Management Group, Department of Chemical Engineering, School of Engineering, University of Santiago de Compostela, Campus Vida, 15782, Santiago de Compostela, Spain.
authors.forename: Carla
authors.initials: C
authors.lastname: Lopes
authors.forename: Marta
authors.initials: M
authors.lastname: Herva
authors.forename: Amaya
authors.initials: A
authors.lastname: Franco-Uría
authors.forename: Enrique
authors.initials: E
authors.lastname: Roca
mesh_terms: D003247:Conservation of Natural Resources; D018556:Crops, Agricultural / Q000254:growth & development; D004785:Environmental Pollutants / Q000032:analysis* / Q000633:toxicity; D005062:European Union; D005308:Fertilizers; D020387:Food Chain; D006801:Humans; D008372:Manure / Q000032:analysis; D019216:Metals, Heavy / Q000032:analysis* / Q000633:toxicity; D018570:Risk Assessment; D012722:Sewage / Q000032:analysis; D012987:Soil / Q000032:analysis; D014866:Waste Products / Q000032:analysis*
chemical_list: D004785:Environmental Pollutants; D005308:Fertilizers; D008372:Manure; D019216:Metals, Heavy; D012722:Sewage; D012987:Soil; D014866:Waste Products