This paper represents 1 of 9 papers generated from a SETAC Pellston Workshop entitled “Science-Based Guidance and Framework for the Evaluation and Identification of PBTs and POPs,” (January 2008, Florida, USA). The workshop objectives were to develop guidance and recommendations on the evaluation of substances fulfilling PBT and POP criteria, using scientific information such as experimental and monitoring data, and computer models.

For the identification and assessment of persistent, bioaccumulative, and toxic (PBT) chemicals and persistent organic pollutants (POPs), overall persistence (P_ov) and long-range transport potential (LRTP) are important indicators. In this article, we first give an overview of methods to determine P_ov and LRTP and discuss the influence of multimedia partitioning of semivolatile organic chemicals (SOCs) on P_ov and LRTP. Next, we summarize the most important features of various multimedia fate and transport models that can be used to calculate P_ov and LRTP. Complementary to environmental fate models, field data provide important empirical information about the spatial distribution and time trends of SOC concentrations in the environment. We discuss the role of field data in the estimation of P_ov and LRTP and give an overview of important field studies showing the levels and trends of various groups of chemicals in different parts of the world. Then, we address key topics in the field of PBT and POP assessment that require further research, such as the formation of transformation products, the influence of atmospheric aerosols on the degradation and transport of SOCs, and the effect of long-range transport by ocean currents. In addition, we describe the most important types of uncertainty associated with estimates of P_ov and LRTP, which are mainly uncertainty of chemical property data and uncertainty of the design of environmental fate models. Finally, we illustrate the characterization of SOCs in terms of P_ov and LRTP with the example of the consensus model for P_ov and LRTP Tool that is provided by the Organization for Economic Cooperation and Development.