Human Health Risk Assessment of The Levels of Dioxin-Like Polychlorinated Biphenyls (PCBs) in Soils From Mechanic Workshops Within Nekede Mechanic Village, Imo State, Nigeria

Abstract

Dioxin-like polychlorinated biphenyls (DL-PCBs) are a class of persistent toxic substances with a high potential to accumulate in the soil as an organic pollutant and bioaccumulate in humans. The study determined the level and human health risk of twelve (12) DL-PCBs in soils from mechanic workshops within Nekede mechanic village (NMV), Imo State. In this study, soil samples (0–15 cm depth) were collected at four different sampling points within Nekede mechanic village. At each sampling point, composite samples consisting of 10 subsamples were collected with pre-cleaned pet bottles using soil auger and were labeled SA, SB, SC, SD. Control sample was taken 500 metres away from the mechanic village where there was no form of auto-mechanic activities. Sample analysis was conducted using Agilent GC 6890N coupled with Agilent MS 5970B to determine the levels of DL-PCBs. The data were analyzed using SPSS version 23. The results revealed that the mean concentration of 12 DL-PCB congeners (Σ12PCBs) in soil ranged from 0.31–16.31 µg kg− 1, which was much higher than that in the control sample (0.006–0.087 µg kg− 1). PCB-126 was the major contributor (58.99%) while the least contributor was PCB-157 (0.0040%) of the Σ12 DL-PCBs TEQ. The estimated LCR (adults 1.29×101, children 4.42×101) and HQs (adults 6.68×102, children 2.29×103) were above the acceptable risk limit (LCR = 10− 4, HQ = 1); indicating a very high adverse effect of DL-PCBs on humans especially children.