Polychlorinated biphenyls (PCBs) were mass-produced and used throughout the world until the 1970s, owing totheir excellent physical and chemical stability. However, they were subsequently classed as persistent organic pollutants (POPs) because of their toxicity, diffusivity, and persistence in the environment, and their international transfer was restricted by the Stockholm Convention. It is stipulated that, by 2028, all PCBs should be correctly disposed of, leading to countries now actively working towards this target. The main origin of PCBs is industrial production of so-called technical PCBs such as Aroclor, Chlophen, and Kanechlor. However, it was recently found that PCB congeners that are not categorized as technical, such as 3,3′-dichlorobiphenyl (PCB-11), are present as impurities in some organic pigments and chemical products. These were often detected as the main congeners, and different congener patterns were exhibited compared to technical PCBs1-5. As a result, such pigments are attracting increasing attention as a source of PCBs that has so far been overlooked. In a previous paper, we reported on the concentrations and congener patterns of the PCBs present in azo-type and phthalocyanine-type organic pigments, and speculated on the process by which these byproducts were formed6. It has also been found that certain concentrations of PCBs are contained in some polycyclic-type pigments and chemical products (silicone-based glue). Accordingly, this study reports on the concentrations and congener patterns of PCBs within such substances.