Aflatoxin contamination of groundnut and maize in Zambia: observed and potential concentrations

Aims Quantify aflatoxins, the potent carcinogens associated with stunting and immune suppression, in maize and groundnut across Zambia's three agroecologies and determine vulnerability to aflatoxin increases after purchase. Methods and Results Aflatoxin concentrations were determined for 334 maize and groundnut samples from 27 districts using lateral-flow immunochromatography. Seventeen percent of crops from markets contained aflatoxin concentrations above allowable levels in Zambia (10 μg kg−1). Proportions of crops unsafe for human consumption differed significantly (P<0.001) among agroecologies with more contamination (38%) in the warmest (Agroecology I) and the least (8%) in cool, wet Agroecology III. Aflatoxin in groundnut (39 μg kg−1) and maize (16 μg kg−1) differed (P=0.032). Poor storage (31°C, 100% RH, 1 week) increased aflatoxin in safe crops by over 1,000 fold in both maize and groundnut. The L morphotype of A. flavus was negatively correlated with post-harvest increases in groundnut. Conclusions Aflatoxins are common in Zambia's food staples with proportions of unsafe crops dependent on agroecology. Fungal community structure influences contamination suggesting Zambia would benefit from biocontrol with atoxigenic A. flavus. Significance and Impact of Study Aflatoxin contamination across the three agroecologies of Zambia are detailed and the case for aflatoxin management with atoxigenic biocontrol agents provided. The first method for evaluating the potential for aflatoxin increase after purchase is presented. This article is protected by copyright. All rights reserved.