The report gives results of a theoretical assessment of polychlorinated biphenyl (PCB) formation and destruction in conventional fossil fuel fired sources. Results suggest a small but finite possibility that PCB isomers may be found in their emissions. The study was the result of concern caused by tentative identification of PCB isomers in ash and flyash from a utility steam generating boiler. The theoretical assessment concluded that: (1) PCB emissions are more likely from higher-chlorine content coal or residual oil combustion than from refined oil or natural gas; (2) PCB isomers with four or more chlorine atoms per molecule are more of an environmental hazard than those with three or less; (3) the probability of forming PCB isomers with four or more atoms of chlorine per molecule during combustion is restricted by the short residence times and low concentrations of chlorine available in many fossil fuels; (4) the amount of PCB emissions, if any, may be related to polynuclear aromatic hydrocarbon emissions; (5) based on the above, inefficient combustion control is more likely to produce PCB emissions than optimum conditions; and (6) the highest priority for field sampling and analysis of PCB from combustion sources should be for small- and medium-sized, hand- and underfeed-stoked coal furnaces.

Prepared by Monsanto Research Corporation under Contract No. 68-02-1320, Task 26, Program Element No. EHE624A. Issued Oct. 1976. "EPA 600-7-76-028." "Cover title." Includes bibliographical references (20-22).