Journal of Basic and Applied Research International

This study evaluated the health risk of iron (Fe) in petroleum-polluted soil amended with cocoa pod husk (CPH), potato peels (PP) and fluted pumpkin husk (FPH). The soil was collected from the Gokana Local Government Area of Rivers State, Nigeria. Two kilograms (2 kg) of the polluted soil were weighed into 48 transparent plastic buckets. Treatments were applied in triplicate across three concentrations (250, 500, and 1000 mg/kg) along with a control group. The soil was amended with CPH, PP, and FPH of the three treatment concentrations and monitored for 150 days. Iron levels were measured using an atomic absorption spectrophotometer (AAS). The percentage (%) reduction of Fe, average daily dose (ADD) (via ingestion, dermal contact, and inhalation), and hazard quotient (via ingestion) related to Fe consumption were calculated using standard risk assessment models. Results showed that CPH had the best remediating properties, reducing Fe concentration from 91.174 ± 0.003 mg/kg at day 0 to 62.59 ± 0.070, 54.674 ± 0.004 and 54.847 ± 0.001 mg/kg with remediation percentages of 31.35%, 39.84% and 40.03% respectively, at day 150 across 250, 500 and 1000 mg/kg substrate concentrations, compared to PP, FPH, and the control. FPH exhibited the least bioremediation capability with the highest Fe concentrations of 87.463 ± 0.001, 84.241 ± 0.003, and 80.789 ± 0.003 mg/kg, and the lowest percentage reductions of 4.07%, 7.60%, and 11.39% across 250, 500, and 500 mg/kg, respectively. The results also show that CPH, PP, and FPH significantly reduced HQ and ADD for Fe in adults and children via ingestion, inhalation and dermal contact compared to the control. These findings show that agro-waste amendments, especially CPH are sustainable and cost-effective materials for reducing iron-related health risks in petroleum-polluted soils, thereby contributing to improved public health and better environmental management.