Occurrence of major mycotoxins and their dietary exposure in North-Central Nigeria staples

Abstract

Mycotoxins are natural contaminants of cereals and other food commodities throughout the world and they significantly impact human and animal health. This work determined the occurrence, co-occurrence and levels of total aflatoxin (AfT), fumonisins (Fums), and ochratoxin A (OTA) in six staples; rice, corn, millet, sorghum, cassava flake (garri) and yam flour in North-Central Nigeria. To achieve this, a total of 162 samples of the staples from field, market and stores from four microclimatic zones of Niger state were quantified for the mycotoxins by the enzyme-linked immuno-sorbent assay (ELISA) method. The result revealed that AfT, Fums and OTA showed deference to microclimatic zones. While AfT had 100% occurrence in all analysed samples within 2.1–248.2 µg/kg, Fums and OTA had lower occurrences and were found within 10–8400 µg/kg and 1.20–170.1 µg/kg, respectively. Rice (25.06 ± 52.39 µg/kg), sorghum (6198 ± 1046 µg/kg) and garri (45.87 ± 61.94 µg/kg) had the highest levels of AfT, Fums and OTA, respectively, while corn (13.83 ± 11.16 µg/kg), rice (119.4 ± 248.3 µg/kg) and sorghum (2.44 ± 1.78 µg/kg) were least contaminated with of AfT, Fums and OTA, respectively. AfT in the field, store and market staples ranged between 5.20 and 45.60 µg/kg, 0.01 and 55.40 µg/kg and 2.10 and 248.2 µg/kg, respectively. Fums was within 50–8400 µg/kg, 50–8150 µg/kg and 10–6150 µg/kg in field, store and market samples respectively. Also, OTA ranged from 3.67 to 5.60 µg/kg, 1.30 to 174.7 µg/kg and 1.20 to 106.1 µg/kg in field, store and market samples, respectively. Co-occurrence of various combinations of the three mycotoxins was evident. In rice co-occurrence was determined to be 24.32%, 37.88%, 64.86% and 24.32% for AfT/OTA/Fums, AfT/OTA, AfT/Fums, and OTA/Fums combinations respectively. Dietary exposure and risk characterisation study was further estimated for the mycotoxins. EDI and%TDI for AfT, Fums and OTA from root and tuber products were lower compared to that for cereals and grains. It is therefore concluded that the climate in North-Central Nigeria is favourable to AfT, Fums and OTA producing fungi. The levels of contamination of these staples with major mycotoxins is of public health importance, it should bring stakeholders together to review the food value chain from farm to folk and identify critical control points in managing this situation.