5th International PCB Workshop--summary and implications.

A summation of new and novel findings presented at "The Fifth PCB Workshop: New Knowledge Gained from Old Pollutants" workshop is provided in this overview, along with discussion of data gaps and research needs in the future. Relative to the previous workshop, the scientific presentations had a decreased emphasis on toxicology; rather, more than half of the sessions dealt with environmental sources, fate and transport, or transformations. Approximately 100 presentations in the form of talks and posters were included in the workshop. The presentations were generally divided into: emissions and transport of PCBs in natural and urban settings; chiral aspects of PCB transport; metabolism and distribution; new aspects of environmental metabolism of PCBs--from microbes to plants to animals; reproduction, developmental and cardiovascular effects of PCBs; updates on Anniston--the most highly exposed PCB community in the U.S. to date; and new and novel approaches for evaluating PCB mixtures (e.g., PCB toxic equivalency factors, and TEFs)--and the implications of such for risk assessment. An overarching state-of-the-science view is important to the goal of preventing negative health consequences. Currently, there are still many roadblocks to evaluating risk associated with this large group of 209 congeners--all of which have different physiochemical properties, variable fate and transport mechanism in the environment, and a range of ability for persistence, bioaccumulation, and biological activity.