Dioxin and PCB levels in sea trout with ulcerative disease syndrome.

This paper reports concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) in fish with symptoms of ulcerative disease syndrome (UDS) and in healthy fish collected from the Słupia River in northwestern Poland. Altogether 174 samples from sea trout were analyzed using an isotope dilution technique with high-resolution gas chromatography coupled with high-resolution mass spectrometry. The levels determined in material collected from healthy and diseased fish did not raise concerns for human health. All results were below the maximum permitted levels established in European Commission Regulation No 2023/915. However, considering instead fish health, dioxins and PCBs could have a negative effect at the levels detected. The highest concentration of dioxins and dioxin-like PCBs (DL- PCBs) was found in diseased sea trout muscles and was 6.19 pg World Health Organization Toxic Equivalents (WHO-TEQ) g-1 fresh weight (f.w.). The most-accumulated dioxin congeners were 2,3,7,8-tetrachlorinated dibenzofuran (TCDF) and 2,3,4,7,8-pentachlorinated dibenzofuran (PeCDF). The most abundant DL-PCBs were PCB-118 and PCB-105, and among non-dioxin like PCBs they were PCB-153, PCB-138, and PCB-101. The polluted sea trout environment and exposure to a mixture of chemical pollutants may increase the incidence of disease. The presence of dioxins and PCBs in their bodies may disrupt the functioning of their immune system. Also the time of spawning, when the fish are exhausted, may affect the increase in the incidence of UDS.