SYMPOSIUM OVERVIEW - TOXICITY OF NONCOPLANAR PCBS

Research into the mechanism of toxicity of PCBs has focused on the Ah receptor, However, it is becoming increasingly clear that certain orth o-chlorine-substituted, non-coplanar PCB congeners having low affinity for the Ah receptor exhibit important biological activities. Actions of non-coplanar PCB congeners in a variety of biological systems have been discovered and the mechanisms for these effects are being elucida ted. The objectives of this symposium are to examine the state of know ledge concerning the mechanisms of toxic action of non-coplanar PCBs a nd to identify similarities and differences using a variety of biologi cal systems. Effects to be considered will include: neurotoxicity, est rogenicity, insulin release, neutrophil function, calcium regulation, and relevant signal transduction systems. Finally, the symposium addre sses the need to consider non-coplanar congeners within the context of risk assessment. The use of Ah-receptor binding and its associated bi ological effects to assess the total toxicity of PCBs may no longer be defensible because of the actions produced by non-coplanar congeners. This symposium provides documentation for that conclusion and focuses attention on emerging mechanisms of PCB action that have received rel atively little attention to date. The topics presented should be of in terest to toxicologists interested in mechanisms of action, in PCB ris k assessment, and in regulatory toxicology. (C) 1998 Society of Toxico logy.