About the author - Food processing Food Hygiene and Safety aflatoxins the invisable threat in foods and feeds

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.

email:

r.bandyopadhyay@cgiar.org

This Technical Innovation

Brief is published by:

SP-IPM Secretariat

SP-IPM@cgiar.org

www.spipm.cgiar.org

Inoculated sorghum grains broadcast in the field.

– R. Bandyopadhyay

The atoxigenic strains are inserted into a carrier (e.g.

sorghum) which acts as a fungal food source and is applied to

crops 2-4 weeks prior to flowering. For small fields the product

can be tossed onto the crop by hand. The strain profile shifts

from one dominated by aflatoxin producers to one in which

atoxigenics dominate, resulting in reduced contamination of

the crop. The positive influences of atoxigenic 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 fields improves, so does the safety of fungal

communities in areas neighboring treated fields. The

technology also brings benefits into storage. First, there are

fewer aflatoxin-producers moving into the store, and secondly,

the biocontrol agents stay with the crop until use. Thus,

competitive exclusion in the field 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 Agriculture (IITA) conducted trials in Nigeria. Native atoxigenic strains

reduced contamination by up to 99%. The National Agency for Food and Drugs Administration and Control

(NAFDAC) gave IITA provisional registration to begin testing of the inoculum of a mixture of four strains under

the trade name aflasafe™. In 2009, maize farmers who applied aflasafe™ achieved, on average, an 80%

reduction in aflatoxin contamination at harvest and 90% after storage. Private and public sector engagement 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 solutions

in Africa. Wu and Khlangwiset (2010) applied health-based analyses

of cost-effectiveness to the method in Nigeria. Although the analyses

examined only impacts on the incidence of liver cancer, the potential

payoff is compelling. Estimating the cost-effectiveness ratio (CER) as

the gross domestic product multiplied by disability-adjusted life years

saved per unit cost, the study revealed that the CER of treating all

maize fields in Nigeria rated between 5.1 and 9.2, rising to between

13.8 and 24.8 if treatment were restricted to maize for human

consumption.

aflasafeTM to reduce aflatoxin contamination

in maize. – R. Bandyopadyhay

The reality in future

Biocontrol is highly effective, but some contamination is inevitable. Thus, aflatoxin management cannot solely

rest in biocontrol. It must be blended with traditional management as well as the redirection of contaminated

crops to alternative uses to avoid human exposure. Governments and industry need to establish standard

procedures for effective low-cost testing and alternative uses of contaminated products. Contamination levels

>20 ppb are unsafe for human consumption but the crop may still be utilized for animal feed as long as

contamination does not exceed 300 ppb in feed for mature beef cattle or 100 ppb in feed for swine. Other

alternative uses include ethanol production. When such rules are established, the crop can be managed for

maximum value without risking human exposure to unacceptable aflatoxin concentrations.