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 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.

KEYWORDS:

• Polychlorinated biphenyls
• dioxins
• cancer risk
• hazard quotient
• mechanic village

Authors’ contribution

VCE contributed to writing the original draft of the manuscript. ARN contributed to methodology and investigation. CED assisted in supervision and validation. BOI helped in conceptualization, methodology and statistical data analysis. FCI assisted in conceptualization and visualization. JOO contributed to supervision and validation. CEE contributed to statistical data analysis, review and editing. MOM helped in investigation, review and editing.

Data availability statement

All data and materials are available.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research was funded by the authors.