Human health risk exposure from suspected BTEX and HMs contamination of Manihot spp. from nearby remediated oil spill field in Niger Delta, Nigeria

Abstract

Background

Crude oil related activities in the Niger Delta region has exposed the environment to various degrees of pollutants, including heavy metals (HMs) and BTEX (Benzene, Toluene, Ethylbenzene, m, p-xylene, and o-xylene). The study assessed the human health risk exposure to BTEX and HMs (Lead, (Pb), chromium (Cr), cadmium (Cd), Nickel (Ni), copper (Cu) and iron (Fe) from remediated oil spilled field. Soil and Cassava tubers were collected around the field and analysed through laboratory procedures using Atomic Absorption Spectrophotometry and Gas Chromatography Flame under ASTMD 4691 and USEPA 8260B for HMs and BTEX, respectively.

Result

The mean concentration of Pb, Cd, Cr, Ni, Fe and Cu in the soil was 0.234 mg/kg, 0.004 mg/kg, 0.299 mg/kg, 0.307 mg/kg, 1.552 mg/kg and 0.527 mg/kg respectively and the concentration exceeded the allowable limit of WHO. The mean concentration of BTEX in the soil and Cassava was 0.0419 mg/kg and 0.1603 mg/kg, respectively and trended as Toluene (0.016 mg/kg) > Xylene (0.011 mg/kg) > Benzene (0.007 mg/kg) > Ethylbenzene (0.007 mg/kg) in soil and Ethylbenzene (0.057 mg/kg) > Xylene (0.051 mg/kg) > Benzene (0.034 mg/kg) > Toluene (0.02 mg/kg). The human health risk based on the target hazard quotient (THQ) for non-carcinogenic parameters in soil and Cassava ranged from “No Significant Risk of Non-Carcinogenic-NSRNc (THQ x 10^-6) to Moderate Significant Risk of Non-Carcinogenic- MSRNc (THQ × 10^-3)” for adults and children. The total carcinogenic risk (TCR) of the HMs and BTEX in soil and Cassava for adults and children was within the “Negligible Carcinogenic Risk for Human-ACRH (TCR × 10^-6 to TCR × 10^-9)”.

Conclusion

Continuous consumption and bioaccumulation of Cassava means the population are not entirely free from the risk of health exposure to BTEX and heavy metals; therefore, effective environmental sustainability practices must be encouraged.