Abstract
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 sub-samples were collected with pre-cleaned pet bottles using soil auger and were labelled SA, SB, SC, SD. The 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 6890 N coupled with Agilent MS 5970B to determine the levels of DL-PCBs. The data were analysed 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 significantly 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 sum total 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.
Highlights
The impact of wastes from auto-mechanic workshops on health and the environment has been an issue in developing countries over the years (Nwachukwu and Huan, 2010; Okoro et al, 2013; Mahmood et al, 2014; AlWabel et al, 2016)
The results revealed that the mean concentration of 12 Dioxin-like polychlorinated biphenyls (DL-polychlorinated biphenyls (PCBs)) 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)
The highest Σ12PCBs was observed in sample SC while the lowest was observed in sample SB
Summary
The impact of wastes from auto-mechanic workshops on health and the environment has been an issue in developing countries over the years (Nwachukwu and Huan, 2010; Okoro et al, 2013; Mahmood et al, 2014; AlWabel et al, 2016). Auto-mechanic workshops are sources of environmental pollution through which persistent organic pollutants (POPs) such as polychlorinated biphenyls (PCBs), Hexachlorobenzene and polyaromatic hydrocarbons (PAHs) are introduced into the environment through soil and groundwater at levels that are considered to be above their threshold limit (Bentum, 2012; Ibe et al, 2021). The presence of PCBs in the environment could bioaccumulate within the food chain, due to their high affinity for organic materials (Scheter et al, 2006). They have been found in human tissues, blood, and breast milk, and are introduced via the consumption of meat, fish, and dairy products (Van den Berg et al, 2006). The effect of PCBs on human health is dependent upon the concentrations of PCBs, type of chlorinated homology and the extent of exposure (Wang et al, 2012; Kumar et al, 2014; Al-Wabel et al, 2016; Enyoh and Isiuku, 2020; Eze et al, 2020a; Eze et al, 2021)
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