Polychlorinated biphenyls (PCBs) have been produced commercially since be fore 1930. They proved to be highly versatile mixtures and their uses continued to expand during the early 1970's even after the unanticipated world-wide en vironmental contamination had been discovered (Jensen et aI. , 1969; Koeman et aI. , 1969). Over 600,000 metric-tons were produced and/or used in the U. S. during this time and it is estimated that worldwide production totaled about 1,200,000 metric-tons (Table 1). With low acute toxicities (Fishbein, 1974), these mixtures were considered gen erally biologically inactive even though industrial exposure had demonstrated he patic and dermatological effects (Fishbein, 1974; Hansen, 1987). Thus, use and disposal were not carefully monitored and it is estimated that one-third of the world-wide production of PCBs has been released into the global environment (Table 1). Table 1. Estimated production and disposition of PCBs b U. s. a Worldwide 6 6 Production/use 610 X 10 kg 1200 X 10 kg Mobil environmental reservoir 82 400 Static reservoirs In service 340 Dumps 130 Total static 470 800 a NAS, 1979 b Tatsukawa and Tanaba, 1984 2 Environmental Distribution Many countries now impose strict controls on the use and release of PCBs. Re lease into the environment has declined dramatically in the last decade, but con tinued release from reservoirs (Table 1) into burdened ecosystems (Table 2) ap pears inevitable for several more decades (Barros et aI. , 1984).

During the past ten years a variety of methods involving mass spectrom etry have been developed for the analysis of environmentally important compounds. Much has been accomplished in that period to solve some of the important problems in the field. Growth of this methodology and its accomplishments has reached the point where an individual scientist can no longer have an in-depth knowledge of all the areas involved. We have attempted to provide this in-depth picture to those scientists con cerned by having the important topics treated by experts in the subject matter. In order to provide all the relevant material in one volume we begin with the general topics which provide the basic background material necessary to understand the techniques discussed in the in-depth topics. These general chapters are kept brief, containing only the essentials needed by the working scientist to deal with the practical applications. References in these chapters are chosen to permit a more complete study of each chapter. The concept for this book was developed during the activities of two of the editors under a NATO travel grant. These editors gratefully acknowledge this support which made the initial planning of this book possible. The editors would like to thank the individual authors of each chap ter for their cooperation and generously giving of their time for this project."