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< prev - next > Agriculture Cultivation aflatoxins the invisable threat in foods and feeds (Printable PDF)
About the author
Ranajit Bandyopadhyay is a
plant pathologist at IITA based
in Ibadan, Nigeria. He is
responsible for IITA’s Africa-
wide research and
development activities related
to diseases of maize, soybean,
cowpea, cassava, banana, and
yam. His current research on
mycotoxins focuses on
developing an understanding
of their occurrence, the bio-
ecology of toxigenic fungi,
policy and institutional issues,
and methods to manage
mycotoxins with focus on
biological control and
integrated management.
This Technical Innovation
Brief is published by:
SP-IPM Secretariat
Inoculated sorghum grains broadcast in the field.
– R. Bandyopadhyay
The atoxigenic strains are inserted into a carrier
sorghum) which acts as a funga l food source and is applied to
crops 2-4 weeks prior to flowering. For small field s the product
can be tossed onto the crop by hand. The strain profile shifts
from one dominated by aflato xin producers to one in which
atoxigenics dominate, resulting in reduced contamination o f
the crop. The positive influences of atoxigen ic strains carry
over between crops, providing additive effects across years. A
single application benefits not only the treated crop but also
crops in rotation. Additionally, because fungi move throughout
the environment, as the safety level of fungal communities
within treated fi elds improves, so does the safety of fungal
communities in areas neighboring treated fields. Th e
technology also brings benefit s into storage. F irst, there are
fewer aflatoxin-producers moving into the store, and secondly,
the biocontrol agents stay wit h the crop until use. Thus,
competitive exclusion in the fi eld translates into a decreased
risk of contamination during storage and transport.
A technology highly suitable and beneficial for small producers in Africa
Biocontrol in the field has proved a useful method for preventing aflatoxin contamination in maize and groundnut.
The International Institute of Tropical Agricu lture (IITA) conducted trials in Nigeria. Native at oxigenic strains
reduced contamination by up to 99%. The National Agency for Food and Drugs Admin istration and Control
(NAFDAC) gave IITA provisional registra tion to begin testing of the inoculum of a mixture of fou r strains under
the trade name aflasafe. In 2009, maize farmers who applied aflasafeachieved, on ave rage, an 80 %
reduction in aflatoxin contamination at harvest an d 90% after storage. Private and public sector e ngagement is
now necessary to introduce the technology country-wide and at regional level, as with the widely used AF36 and
Afla-Guard™ products in the USA.
When various aflatoxin management practices were evaluated, it was
found that biological control is one of the most cost-effective so lutions
in Africa. Wu an d Khlangwiset (2010) applied health-based analyse s
of cost-effectiveness to the method in Nigeria. Although the analyses
examined only impacts on the incidence of liver cancer, the potentia l
payoff is compelling. Estimating the cost-effectiveness ratio (CER) as
the gross domestic product mu ltiplied by disability-adjusted life years
saved per unit cost, the study revealed that th e CER of treating all
maize fields in Nigeria rated between 5.1 and 9.2, rising to be tween
13.8 and 24.8 if treatment were restricted
to maize for
aflasafeTM to reduce aflatoxin contamination
in maize. – R. Bandyopadyhay
The reality in future
Biocontrol is hig hly effective, but some contamin ation is inevitable. Thus, aflatoxin management cannot sole ly
rest in biocontro l. It must be ble nded with traditional management as well as th e redirection of contaminate d
crops to alternative use s to avoid human exp osure. Governments and indust ry need to esta blish standard
procedures for effective low-cost testing and alternativ e uses o f contaminated products. Contamination levels
>20 ppb are unsafe for human consumption b ut the crop may still be utilize d for animal feed as long a s
contamination does not exceed 300 ppb in fee d for mature beef cattle or 100 ppb in feed for swine. Other
alternative uses include ethanol production. Wh en such rules a re established, the crop can be managed for
maximum value without risking human exposure to unacceptable aflatoxin concentrations.
Further reading:
Cotty, P.J. and Jaime-Garcia, R., 2007, Influences of climate on aflatoxin-producing fungi and aflatoxin contamination.
International Journal of Food Microbiology 119: 109–115.
Hendrickse, R.G. 1984. The influence of aflatoxins on child health in the tropics with particular reference to Kwashiorkor.
Transactions of the Royal Society of Tropical Medicine and Hygiene 78: 427–435.
Lewis, L., Onsongo, M., Njapau, H., Schurz-Rogers, H., Luber, G., Kieszak, S., Nyamongo, J., Backer, L., Dahiye, A., Misore,
A., DeCock, K., and Rubin, C., 2005. Aflatoxin contamination of commercial maize products during an outbreak of acute
aflatoxicosis in Eastern and Central Kenya. Environmental Health Perspectives 113: 1762–1767.
SP-IPM, 2009. Advances in Preventing and Managing Contaminants in Foods, Feeds, and the Environment. IPM Research
Brief No. 7. SP-IPM Secretariat, IITA, Ibadan, Nigeria. 40 pp. (accessed
29 September 2010).
Wu, F. and Khlangwiset P., 2010. Health economic impacts and cost-effectiveness of aflatoxin-reduction strategies in Africa:
case studies in biocontrol and post-harvest interventions. Food Additives and Contaminants 27: 486–509.
SP-IPM Steering Committee Members:
Sikora, R (Program Chair); Nwilene, F (AfricaRice); Ramasamy, S (AVRDC); Staver, C (Bioversity); Buruchara, R (CIAT); Nicol, J (CIMMYT); Kroschel, J (CIP); Yahyaoui, A (ICARDA);
Chabi-Olaye, A (icipe); Sharma, H (ICRISAT); Narrod, C (IFPRI); Bandyopadhyay, R (IITA); Heong, KL (IRRI); Bramel, P (DDG –R4D convening center, IITA); Hoeschle-Zeledon, I
(Program Coordinator, IITA)