Pyrolysis and combustion of wood contaminated with pentachlorophenol and development of bioassay for detection of polychlorinated dibenzofurans in insulating fluids

In this work, PCDD/PCDF yields from the pyrolysis or combustion of PCP in solvent, in the gas phase, in spiked sawdust, and in sawdust derived from a PCP-impregnated utility pole were studied. Pyrolysis typically produced higher yields than combustion. A novel PCDF-forming process, involving combination of a PCP-derived species with a benzene derived species, was identified, based on the observed product distributions from certain experiments. Of greater interest, under various pyrolyses and combustion scenarios, a sharp dependence of PCDD/PCDF yield on initial PCP concentration was demonstrated. This result indicates that simple extrapolation of the PCDD/PCDF forming potential of high concentration PCP containing materials will substantially overestimate the likely yields from low concentration materials such as PCP-impregnated wood. Studies were also performed to determine the feasibility of using an in vitro bioassay to detect the conversion of polychlorinated biphenyls (PCBs) to polychlorinated dibenzofurans (PCDFs) in Aroclor based dielectric fluids which were subjected to pyrolysis or combustion. Pyrolysis of Aroclor 1254 at 550{degree}C for 15 minutes results in a 100-fold increase in the bioassay activity, shown by gas chromatographic/mass spectrometric analysis to be correlated to enhanced PCDF levels. Results of testing of six chemically characterized, inservice transformer fluids demonstrated that the bioassaymore » is potentially useful for economical screening of used dielectric fluids and other substances for PCDF-like aggregate activity. 48 refs., 12 figs., 18 tabs.« less