Aflatoxin B1 Contamination and Dietary Risk Assessment in Commonly Consumed Smoke Dried Fish Species in Minna, Niger State, Nigeria

Abstract

The contamination of smoke-dried fish with Aflatoxin B1 (AFB1) poses a significant yet under investigated food safety threat in Nigeria. This study assessed the levels of AFB1 and evaluated the associated dietary risk among consumers of commonly consumed smoke-dried fish species in Minna, Niger State. A total of 24 smoke-dried fish samples comprising Clarias gariepinus, Protopterus annectens, Gymnarchus niloticus, and Synodontis membranaceus were collected from three major markets in Minna metropolis: Kure, Mobil, and Kasuwa-Gwari between July and August 2025. AFB1 was quantified using a validated indirect Enzyme-Linked Immunosorbent Assay (ELISA). Dietary risk was evaluated deterministically and probabilistically using the Estimated Daily Intake (EDI) and Margin of Exposure (MOE) methods, with consumption data derived from a structured survey of 84 respondents. The results indicated that AFB1 was detected in all 24 samples (100% prevalence), with concentrations ranging from 0.38 to 6.05 µg/kg (overall mean: 2.95 µg/kg). Clarias gariepinus recorded the highest mean AFB1 concentration (5.42 ± 0.47 µg/kg), while Synodontis membranaceus had the lowest (0.69 ± 0.27 µg/kg). Market level differences were not statistically significant. The deterministic MOE was 27.78, and the Monte Carlo-simulated median MOE was 35.47, both substantially below the regulatory concern threshold of 10,000 for genotoxic carcinogens. Furthermore, 88.3% of simulated population-level MOE values fell below 100, indicating a high probability of public health concern. These findings demonstrate widespread AFB1 contamination across fish species and market locations in Minna and signal an elevated carcinogenic risk for regular consumers. Urgent regulatory intervention, improved smoke-drying practices, proper storage and routine surveillance are recommended.