Aflatoxins and Their Management · 2018-05-10 · . Aflatoxin Contamination Occurs in Two Phases....
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P Aflatoxins and Their Management Ranajit Bandyopadhyay IITA, Ibadan, Nigeria
Transcript of Aflatoxins and Their Management · 2018-05-10 · . Aflatoxin Contamination Occurs in Two Phases....
P
Aflatoxins and Their Management
Ranajit BandyopadhyayIITA, Ibadan, Nigeria
www.iita.org
Outline
• Aflatoxin facts• Impact of aflatoxins in people’s lives
• Prevalence and exposure• Aflatoxins and trade• Aflatoxin management practices• Promise of Biocontrol• Summary
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• Highly toxic metabolite produced by the ubiquitous Aspergillus flavus fungus
• The fungus infects crops and produces the toxin in the field and in stores
• Fungus carried from field to store• Contamination possible without
visible signs of the fungus
• Some predisposing factors: – pre-harvest high temp and
drought stress– wet conditions at harvest
and post-harvest periods
– insect damage
Aflatoxin Facts
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Aflatoxin Contamination Occurs in Two Phases
Phase I: Before Crop MaturityDeveloping crops become infected. Associated with crop damage (insect, bird, stress). Favored by high temperature (night) and dry conditions.
Phase II: After Crop MaturityAflatoxin increases in mature crop.Seed is vulnerable until consumed. Rain on the mature crop increases contamination.Associated with high humidity in the field & store, insect damage, and improper crop storage or transportation.
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Aflatoxin Problem Starts in the Field
020406080
100120140160
1 2 3 4 5 6 7 8 9 10 11 12 13 14
Farmers
Afla
toxi
n (p
pb)
792 309
2010: Maize
64% fields above 20 ppb at harvest in northern Nigeria
Increases in stores; interventions required in field and stores
Contamination is most severe at low elevations and during dry periods. During drought the zone with contamination expands.
35°N
35°S Zone with PerennialContamination Risk
Aflatoxin Contamination: A Perennial Concern in Warm Climates
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Aflatoxin Impacts People’s Lives
~2.3 million bags contaminated maize not ‘officially’ tradable in 2010 in Kenya
Prevalence of Aflatoxins in Food & Feed
• Several African staple commodities affected• High human exposure in Africa – mother to baby• Levels and frequency of occurrence high
– >30% maize in stores with >20 ppb aflatoxin– ~90% stores are contaminated with Afla fungi– Up to 40% grain in households with aflatoxin
• Concern for food and feed processors, government and emergency food reserve agencies, school‐feeding
• Aflatoxins disproportionately impact the poor• Highly toxic strains, conducive environmental
conditions, traditional farming methods and improper grain drying and storage practices, unregulated markets
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Aflatoxin Contamination in West Africa
• Maize: 4,000 – Benin• Peanut: 925 – Burkina• Sorghum: 80 – Ghana• Rice: 372 – Nigeria• Millet: 200 – Nigeria• Tiger nuts: 120 – Nigeria
Primary products• Peanut paste: 3,278 – Ghana• Peanut sauce: 943 – Ghana• Leaf sauce: 775 – Gambia• Maize dough: 313 – Ghana• Kenkey: 524 – Ghana• Cashew paste: 366 – Ghana• Peanut oil: 500 – Nigeria• Yam flour: 7,600 – Nigeria• Local beer: 135 – Nigeria• Infant food: 19* – Burkina
Food productsMTL = 10 - 20 ng/g
International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org
Aflatoxin-albumin adducts (pg AFB1-lysine eq./mg albumin)
<5 5-25 26-100 >100
Num
ber o
f ind
ivid
uals
(%)
0
20
40
60
80
100 Gambia (n = 950)Benin (n = 479)USA (n = 48)Europe (n = 74)
Aflatoxin Exposure in Africa, Europe & USA
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Aflatoxin and Poultry (Broilers)
Aflatoxin levels in feeds in Nigeria
Aflatoxin level (ppb) Samples (%)
<20 (safe) 38
>20 to 100 (up to 5x) 14
>100 to 500 (up to 25x) 41
>500 to 1,000 (up to 100x) 7
AF-free diet 500 ppb AF dietAF-freediet
500 ppb AF diet
~40% reduction in live weight (8 weeks)
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Trade Losses due to Aflatoxins
• Export compliance with food safety and quality standards.
• Total losses: $1.2 billion• World Bank estimate of unrealized
trade– 2005 study: ~ Tens of millions of $
• Reasonable estimate: US$ 450 million• Some countries active to meet
standards by putting in place relevant institutions
• Best quality exported; poorer quality consumed domestically. Peanut
Maize
Coffee
Cocoa
Presenter
Presentation Notes
EXPAND Groundnut kernel and maize earhead infected with Aspergillus flavus. Milk (contaminated with Aflatoxin M1) poured into drain. The reduction in aflatoxin standard in EU will result in one less death in EU in two years. But cost to African nations is huge. This is a non-tariff trade barrier. This is based on a World Bank study by Otsuki et al (2001). The Asian study is from Lubulwa (1996)
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Meeting Aflatoxin Standards Benefits Exporting Nations
• Nigeria and Senegal major groundnut exporters in 1960s, but completely lost the export market since 1980s.
• Senegal: US$ 4.1 million added capital investment and 15% recurring cost would attract 30% price differential to oil cake.
• Export would increase from 25K tons to 210K tons.
• Increased export volume and price differential would annually add $281 million value to groundnut export for the capital investment.
• For confectionary groundnut, adherence to Good Management Practices would increase export value by US$ 45 million annually.
• Malawi: Fair Trade groundnut export improved with better aflatoxin testing protocol. World Bank; Mbaye (2004)
Groundnut Pyramids in Nigeria during 1960s
Aflatoxin Intervention
Medical
Agriculture
Surveillance
Enterosorption
Pre-harvest
Post-harvest
Crop resistance to fungal infection or aflatoxin biosynthesis
Biocontrol e.g. nonaflatoxigenic strainsReduce crop stress- irrigation, Insecticides, fungicides
Improved drying, sorting, insect control and storageDetoxification, e.g., ammoniationAlternative uses
e.g. Novasil clay
Agriculture & Medical Prevention of Aflatoxin-related Food Security and Health Effects
(Adapted from Wild and Hall, Mutation Res., 2000)
AwarenessRegulation
Provision of safe food
Early diagnosis
Agriculture Based Prevention of Aflatoxin-related Food Security and Health Effects
• Pre-harvest– Resistant cultivars, if available– Biological control, e.g., aflasafe– Irrigation and water conservation practices– Lime and FYM application
• Post-harvest– Sorting– Insect control– Improved drying and storage– Detoxification, e.g., ammoniation– Alternative uses including blending
Contaminated Crops have Uses and Can be ValuableMarkets are needed to provide value to crops unsafe for human consumption
US FDA Action Level
Permitted Use(Examples)
500 ppb Middleman (Blender)300 ppb Finishing Beef200 ppb Finishing Swine
100 ppb Breeding beef and swine; mature poultry
20 ppb Human Food, Feed0.5 ppb (M1) Milk
Ammoniation is Highly Effective in
Eliminating Aflatoxin
Trade Based Prevention of Aflatoxin-related Food Security and Health Effects
• Awareness campaigns to increase demand for aflatoxin safe products and incentivize adoption of aflatoxin control strategies along the value chain
• Upgrade food control system• Enhanced laboratory capacity and availability of rapid test kits, trained
users, documentation of results and withdrawal of contaminated products
• Improved trader compliance with national regulatory codes• Create a commodity exchange system such as warehouse receipts• Improve enforcement mechanisms for domestic, import and export
trades
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Awareness and Training
Branding for Aflatoxin Testing as a Case for Self‐Regulation
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Aflatoxin Mitigation by Native Beneficials: Principles
In nature, some strains produce a lot (toxigenic), and others no aflatoxin (atoxigenic)Atoxigenic strains identified from nature, introduced in a carrier, and applied in fields to exclude toxigenic strainsShift strain profile from toxigenic to atoxigenicThus, aflatoxin contamination reducedStrains move from field to storesMultiple year carry-over effectWe identify and promote only native beneficial strains
0
25
50
75
100
Natural Biocontrol
Inci
denc
e (%
)
TOXIGENIC
ATOXIGENIC
Presenter
Presentation Notes
Biological control agents act against plant pathogens through different modes of action. Antagonistic interactions that can lead to biological control include antibiosis, competition and hyperparasitism. Competition occurs when two or more microorganisms require the same resources in excess of their supply. These resources can include space, nutrients, and oxygen. In a biological control system, the more efficient competitor, i.e., the biological control agent, out-competes the less efficient one, i.e., the pathogen. Antibiosis occurs when antibiotics or toxic metabolites produced by one microorganism have direct inhibitory effect on another. Hyperparasitism or predation results from biotrophic or necrotrophic interactions that lead to parasitism of the plant pathogen by the biological control agent. Some microorganisms, particularly those in soil, can reduce damage from diseases by promoting plant growth or by inducing host resistance against a myriad of pathogens. Efficient biological control agents often express more than one mode of action for suppressing the plant pathogens.
Product: Aflasafe
Mixture of 4 native atoxigenic strains
Nigeria
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Farmers treating maize and groundnut fields with AflaSafe
Aflatoxin reduction in corn:Harvest 2009: 80% 2010: 89%Storage 2009: 90% 2010: 96%
71% and 52% carry-over of inoculum 1 & 2 years after
application
Aflatoxin reduction of peanut at harvest:Nigeria ‐‐ 2009: 96% 2010: 98%Senegal ‐‐ X 2010: 87%
75
94100
03
39
73
27
100
80
60
40
20
0<4 <10 <20 >20EU WFP US unsafe
maximum allowable aflatoxin level (ppb)
farm
ers' fie
lds (%)
Aflasafeuntreated
Productivity increased of communities in
aflasafe‐treated areas
DALYs saved: 103,000 ‐ 184,000cost‐effectiveness ratio: 5.1 ‐ 24.8
Source: Felicia Wu, Pittsburgh Univ.
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Impact of Aflasafe on Trade and Health
B
Ownership and Advocacy by the Nigerian Government
Billboard Interactive Forum
A commercialization strategy for distribution and adoption being pilotedConsider Aflasafe as public health intervention for aflatoxin
AF36 manufacturing facilityArizona Cotton Research & Protection Council, USA
Innovative Product, Excellent Efficacy……. SCALING!
Manufacturing facility in
Africa is the missing piece for SCALING
• G20: Aflasafe incentivization selected for implementation in Nigeria• Aflasafe will be used by smallholder farmers in 200,000 ha
National Products
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Products ready for registration
Products under testing in farmers’ fields
Strain development in progress
Aflasafe-NigeriaTM
Aflasafe-SenegalTM
Aflasafe-KenyaTM etc…
Aflasafe-WestTM
Aflasafe-EastTM
Aflasafe-SouthTM
Regional Products
SenegalMali
Burkina
Ghana
Nigeria
Kenya
Tanzania
Mozambique
Zambia
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Summary
Aflatoxins in food and feed pervasive in AfricaIncreased awareness + good management + effective regulations + strong institutions = low human health & high market impactsLow awareness + low management + inadequate regulations = high human health & low market impactsAflatoxin is a public health issue in AfricaTechnologies available but must be implemented to reduce aflatoxin burden in African economies and food systemSupport needed to coordinate and galvanize partnerships
