Concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans from chemical manufacturers and waste disposal facilities.

Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) were measured in various source and environmental samples obtained from eight chemical manufacturers producing agricultural chemicals, synthetic dye, or resin and eight chemical waste disposal facilities. The concentrations of PCDDs and PCDFs ranged from 3.0 to 3504 ng/g for PCDDs and from 1.2 to 1668 ng/g for PCDFs in fly ash. Their concentrations in emission were in the ranges of 21.8 to 3205 ng/m3 for PCDDs and not detected to 4344 ng/m3 for PCDFs. PCDD and PCDF concentrations were higher in fly and bottom ashes and in emissions from two manufacturers that incinerate waste plastics than in those from other manufacturers. For emission and liquid samples from the manufacturers. For emission and liquid samples from the manufacturers of agricultural chemicals, significantly high concentrations of tetra-CDDs were detected. Furthermore, the high concentrations of PCDFs, especially hepta- and octa-CDF congeners, existed in emissions from waste incinerators that manufacture rubber. Among manufacturers and disposal facilities, the total emission equivalent (2.94 ng/m3) of PCDDs and PCDFs was highest for a certain manufacturer of agricultural chemicals, showing that more 2,3,7,8-chlorine-substituted PCDDs and PCDFs were present in their emissions.