Polychlorinated Biphenyls (PCBs) in Soils Around Old Transformers in Nsukka, Nigeria: Assessing the Ecological and Health Risks

Polychlorinated biphenyls (PCBs) are persistent organic pollutants known for their environmental toxicity and resistance to degradation. This study determined PCB concentrations and evaluated their ecological and health risks in soils around transformer facilities in Nsukka, Nigeria. Soil samples were analyzed using a Hewlett-Packard GC 1290 gas chromatograph equipped with an electron capture detector (ECD, 63Ni). The results showed that Σ18PCB concentrations ranged from 126.83 to 1101.02 mg/kg, with pollution levels following the decline order: Transformer T2 > T4 > T6 >T8 >T3 >T5 >T7 >T1 >T9 >T10. The congener profile was dominated by tri-PCBs, followed by di-PCBs, penta-PCBs, and tetra-PCBs. Furthermore, lower-chlorinated PCBs (LC-PCBs) accounted for 99.70–100% of the total PCBs, whereas higher-chlorinated PCBs (HC-PCBs) contributed only 0–0.3%. The concentrations of Σ18PCBs in transformer soils exceeded the guideline values for both agricultural and urban soils. The source analysis suggested that the PCBs likely originated from the Aroclor 1254 mixtures and other PCB-containing products. The ecological risk index and cancer risk assessment indicated that the soils in the study area pose significant risks to human health and the environment. Therefore, stricter regulatory measures are recommended to minimize PCB release from anthropogenic activities, particularly the leakage of transformer fluids during maintenance.