Human aflatoxin exposure in south-western Ethiopia assessed using serum biomarkers: A thesis submitted in partial fulfilment of the requirements for the Degree of Master of Science at Lincoln University

Abstract

Aflatoxins are secondary metabolites produced by the fungi Aspergillus flavus and A. parasiticus. Consumption of aflatoxin-contaminated food can cause hepatocellular carcinoma, immune suppression, child growth impairment, and death. The study aimed to assess aflatoxin exposure in South-western Ethiopian adults, using serum biomarkers. The study was conducted in five South-western Ethiopian rural districts (Shebe Senbo, Manna, Seka Chekorsa, Kersa, and Omo Nada) in the Oromia Region and included 100 adults aged 18–60 years. The 100 serum samples collected were analysed for aflatoxin B1 (AFB1), aflatoxin B1-lysine (AFB1-lys), aflatoxin B2 (AFB2), aflatoxin G1 (AFG1), aflatoxin G2 (AFG2) and aflatoxin M1 (AFM1) using liquid chromatography-tandem mass spectrometry. All six of the analysed aflatoxins were detected in 64/100 (64%) of the serum samples at levels ranging from 8.3 to 422.9 ng/L. The most frequently detected aflatoxin was AFM1 (38%), followed by AFB1 (37%), AFB1-lys (27%), AFG1 (25%), AFG2 (25%), and the least detected was AFB2 (5%). The mean aflatoxin concentrations were 72.3, 69.9, 58.6, 43.2, 36.9 and 6.1 ng/L for AFB1-lys, AFM1, AFG2, AFB1, AFG1 and AFB2, respectively. There was no association between sociodemographic characteristics and serum aflatoxin concentration. Body mass index (BMI) of the participants did not correlate with their serum aflatoxin concentration. There was a significant association between serum aflatoxin concentration and high millet (p = 0.031), groundnut (p = 0.019), chickpea (p = 0.023), lentil (p = 0.003) and soybean (p = 0.018) consumption. The results suggest the exposure of South-western Ethiopian adults to aflatoxins. Therefore, rules and regulations on the maximum limits of aflatoxin concentration in food and feed should be implemented by the government. We hope that the results of this study will encourage the implementation of evidence-based interventions and development of food regulations in Ethiopia.