On August 1, 2014 the industry group European Centre for Ecotoxicology and Toxicology of Chemicals (ECETOC) published a report proposing an evaluation strategy to assess whether a substance is persistent, bioaccumulative and toxic (PBT), or very persistent/very bioaccumulative (vPvB). The report recommends focusing the evaluation on those compartments into which a substance would initially partition. The evaluation strategy is based on a review of new information and the “weight-of-evidence” approach set out in Annex XIII of the European chemical regulation REACH. It focuses on persistence and bioaccumulation guidance, as sufficient guidance on toxicity exists recommends additional research on several endpoints. The report suggests to screen for bioaccumulation potential based on octanol-water and octanol-air coefficients, in vitro studies and other modelling calculations. For higher-tier assessments classical bioconcentration studies may be used, the report details. It is stressed that organ-specific bioconcentration factors and human or environmental biomonitoring are of limited use as they do not allow for conclusions on overall bioaccumulation.