Prevalence and health risk assessment of aflatoxins in locally processed edible oil in Oromia, Ethiopia

Abstract

Aflatoxins are potent carcinogenic mycotoxins that frequently contaminate oilseed value chains in developing countries. This study assessed the occurrence of aflatoxins (AFB₁, AFTB₂, AFG₁, AFG₂) and associated dietary health risks in 69 samples comprising oilseeds, crude edible oils, and oil cakes collected from local pressing mills in six cities of Oromia, Ethiopia. Samples were extracted, purified using immunoaffinity columns and analyzed by validated high-performance liquid chromatography with fluorescence detection (HPLC-FLD). The analytical method showed excellent linearity (R², 0.9960–0.9993), limits of detection ranging from 0.12 to 0.31 μg kg⁻¹, and acceptable precision (RSD, 2.2–10.0%). Total aflatoxins were detected in 78.3% of oilseeds, 47.8% of crude oils and 72.7% of oil cakes. AFB₁, the predominant and most toxic congener, reached maximum concentrations of 4.24 μg kg⁻¹ in oilseeds, 12.63 μg kg⁻¹ in crude edible oils and 16.52 μg kg⁻¹ in oil cakes. While only 4.3% of oilseed samples exceeded the regulatory limit of 10 µg kg⁻¹, 30.4% of crude edible oil samples exceeded this limit, with total aflatoxin concentrations reaching 30.34 µg kg⁻¹, suggesting that mechanical oil extraction may concentrate aflatoxins in crude edible oils. Health risk assessment revealed that the hazard quotient values (HQ, 7.8–37.5) exceeded 1 for all age groups and the incremental lifetime cancer risk (ILCR, 0.9 × 10⁻⁵–4.5 × 10⁻⁵), indicating a measurable carcinogenic risk associated with chronic consumption of contaminated crude edible oils. These findings highlight the need for improved postharvest management, routine surveillance and practical mitigation strategies for small-scale oil processors.