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Polychlorinated Dibenzodioxins and -furans (PCDDs and PCDFs) are potent environmental toxins. Environmental exposures to these compounds in part-per-billion (ppb) and part-per-trillion (ppt) concentrations are of particular interest. These exposures may arise from bleached paper products, paper production process sludge, effluent waste water from paper plants, consumption of food and water from contaminated sources and contact to paper products.

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...