No. 6, October 2010
Aflatoxins – the invisible threat in foods and feeds
CGIAR Systemwide Program
on Integrated Pest
Management (SP-IPM) is a
global partnership that draws
together the diverse IPM
research, knowledge, and
expertise of the international
agricultural research centers
and their partners to build
synergies in research outcomes
and impacts, and to respond
more effectively to the needs
of farmers in developing
SP-IPM Technical Innovation
Briefs present, in short, IPM
research findings and
innovations for the
management of pests, diseases,
and weeds in agricultural
This and other IPM Briefs are
Aflatoxins are hi ghly toxic fungal metabolites ca using suppression of the immune system, gro wth retardation,
liver cancer, and even death in humans and do mestic animals. Aflatoxins also affect the rate of recovery from
protein malnutrition, Kwashiorko r (Hendrickse, 1984), and ex ert severe nutritional interference, includ ing in
protein synthesis, modification o f micronutrients, and upt ake of vitamin A and D. Exposure in animals reduce s
milk and egg yields. The contamination of milk and meat is passed on to humans.
Aflatoxins affect cereals, oilseeds, spices, tree nuts, milk, meat, and dried fruits.
Maize and grou ndnut are major sources of human exposure b ecause of the ir
higher susceptibility to contamination and frequent consumption. The toxins are
most prevalent within developing countries in tropical regions and the problem is
expected to be further exacerbated by climate change (Cotty and Jaime-Garcia,
The aflatoxin-producing fungi ( Aspergillus spp.) come in contact with crops in
the field during crop development. They stay with the crops until their final use.
If the environment where crops are stor ed is humid and warm, the fungi, which
moved into storage with the c rops, can proliferate and produce more aflatoxins.
Aspergillus communities in diffe rent regions differ in their aflatoxin-producing
ability. In some locations, the y produce large concentrations; in others, they
produce relatively lower amounts.
Green growth of Aspergillus
The high incide nce of aflatoxin throughout Sub-Saharan Africa aggravates an fungus on maize cob. – IITA
already food in secure situation. Agricultural pr oductivity is hampered by cont amination, compromising food
availability, access, and utilization. Unless aflatoxins in crops and livestock are e ffectively managed, marketable
production and food safety cannot improve. Thus, the economic benefits of increased trade cannot be achieved.
Aflatoxins cost farmers and countries hundreds of millions of dollars annually. These losses ha ve caused crops
to be moved ou t of regions, companies to go bankrupt, and entire agricultural communities to lose stability.
Additionally, effective control m ust be achieved before many development activities aimed at achieving food
security can be implemented, such as local foo d procurement strategies complementing food aid and school
feeding programs, and ready-to-use therapeutic foods.
Contamination occurs before and after crop maturity. To ensure the greatest crop value and the lowest exposure
of humans to aflatoxins, manage ment must extend from fi eld to fork. Currently, contamination is prevented by a
combination of tools, such as post-harvest drying (whe re cost-effective), proper st orage, shelling, de-hulling,
sorting, early harvest, using regionally ad justed planting dates, and insect control. Pre-harvest management is
unreliable. In 1989, farmers in t he USA formed the Multi-crop Aflatoxin Working Group and joined with the US
Department of Agriculture to in crease research on aflatoxin management with an emphasis o n breeding and
transgenic crops. When the program was discont inued in 2008, commercially useful resistant crops still had not
been developed, but there was an unexpected advance.
Biocontrol – a novel approach
A biological control technique greatly reduced aflatoxins in all the susceptible crops in a cost-effective manner
and over a broad geographic area. Native strains of A. flavus that do not produce aflatoxins (“atoxigenic strains”)
are used to competitively exclude aflatoxin-producing strains from the crop environment.