Aflatoxin contamination of household stored grains for smallholder farmers in Dodoma, Tanzania

Abstract

Aflatoxins are toxic and carcinogenic secondary metabolites, produced by Aspergillus flavus and Aspergillus parasiticus, which contaminate stored grains including maize, groundnuts and sunflower seeds and cause negative health effects to both humans and animals. The aim of this study was to determine the level of aflatoxins contamination of household stored grains (maize, groundnuts and sunflower seeds) in Dodoma, Tanzania. Immuno-affinity high performance liquid chromatography with post column derivatization was used to analyse AFB1, AFB2, AFG1, AFG2 and total aflatoxins in 45 samples. Out of 45 samples, 38% were contaminated with aflatoxins; the highest mean levels of total aflatoxins were observed in groundnuts (269 μg/kg) followed by maize (74.9 μg/kg) and lastly sunflower (0.2 μg/kg). About 27% of maize and 67% of groundnut samples had higher levels of AFB1 and total aflatoxins beyond the East African Community limits of 5 and 10 μg/kg, respectively. The mean moisture contents were 9.6% for maize, 4.1% for groundnuts and 5.7% for sunflower seeds. These moisture levels were far below the recommended safe storage moisture levels of 13.5% for maize, 8% for groundnuts and 10% for sunflower seeds. Such moisture levels would not allow mould growth and subsequent aflatoxins contamination. It suggests that contamination could have occurred in the field or during the drying stages before reaching the observed moisture levels. Therefore, there is a need to conduct further study to assess aflatoxin contamination in the field, during drying operations and storage to identify the critical stage for intervention. Moreover, farmers should be trained on best management and handling practices to prevent contamination.