Although it generally is agreed on in the scientific community that an evaluation of sediment quality solely based on total contaminant levels should be regarded only as a 1st tier or 1 LOE in a WOE framework, not all regulatory frameworks follow this approach. As will be discussed later, dredged material disposal in Venice Lagoon currently is regulated based upon the use of regionally developed SQGs as strict pass/fail criteria. The implications of this policy upon the management of the lagoon are under investigation, but studies on contaminant mobility and bioavailability and on sediment-related effects on biota and exposure (bioassays, biomarkers, bioaccumulation, biomagnification) having the characteristics (duration, number of sites and samples, frequency, number of chemicals and endpoints, etc.) to properly support (e.g., preliminary and/or detailed quantitative risk assessment) decisions on a basin scale have been carried out only recently in the Venice Lagoon (Thetis 2003; Losso et al. 2004; Carrer et al. 2005; Thetis 2005c).