Assessment of health risks and immunological effects from oral exposure to 2,4ꞌ-dichlorobiphenyl (PCB 8) and its bacterial degradation products

The adverse effects of polychlorinated biphenyls (PCBs) on human and animal health pose a significant concern. However, to date, most studies have considered the risks of environmental contamination by highly chlorinated biphenyls. This study, on the contrary, focuses on the impact of dichlorinated biphenyl (PCB 8) and its bacterial transformation products on the immune system. PCB 8 was found to suppress antibody formation without affecting cell-mediated immunity responses. The degradation of PCB 8 by Rhodococcus opacus FG1 reduced its impairment of humoral immunity. The bacterial transformation by Rhodococcus opacus FG1 (VKM Ac-3030) enzymes induced a 16.9-fold decrease in the PCB 8 concentration over 14 days. Concurrently, 2-chlorobenzoic acid (2-CBA) and 4-chlorobenzoic acid (4-CBA) accumulated in the medium. The assessment of the immune parameters following the exposure to 2-CBA and 4-CBA revealed no negative changes. The data from the health risk assessment demonstrated that, despite the observed decrease in the PCB 8 concentration during biotransformation, the non-carcinogenic risk remained high for both children and adults, whereas the carcinogenic risk declined to acceptable and safe levels for children and adults, respectively, by day 14. The calculated non-carcinogenic risk values from the resulting CBAs were not associated with health hazards.