Juliet Akello Prevalence of aflatoxins in Zambian maize and groundnuts Stakeholders’ Consultative Meeting on Aflatoxin Awareness & Management, 28 th April, Lusaka
Jul 27, 2015
Juliet Akello
Prevalence of aflatoxins in Zambian maize and groundnuts
Stakeholders’ Consultative Meeting on Aflatoxin Awareness & Management, 28th April, Lusaka
Aflatoxins
2
Highly toxic substances
Causative agent: Green mold (Aspergillus spp)
Fungus is common & widespread in soil & decaying matter
Affects several crops (legumes, cereals, tuber crops, chilies, etc)
Maize & groundnuts: major sources of aflatoxin exposure in
humans.
Contamination starts in the field & continues throughout the
value chain
Aflatoxins
Contamination is favoured by several
factors:
• Climate: drought, high temperatures &
insect damage.
• Poor post-harvest handling techniques:
inappropriate storage, transportation &
processing.
Incidence: prevalent in many parts of
sub-Saharan Africa
Year Maize Groundnut Reference
1979 - 5 Kannaiyan et al. 1979
1998 900-929 6200-8600 Njapau et al. 1998
2009 0.7-108 - Kankolongo et al. 2009
2010 10 - Mukanga et al. 2010
Aflatoxin levels (ppb) detected in maize & groundnut samples from
different parts of Zambia
Surveillance studies (1979-2010)
Aflatoxin levels depended on: locality, crop, processing method &
presence of microbial contaminants
Aflatoxin prevalence (2011-2014)
Survey sites
Eastern Province
• Nyimba
• Petauke
• Mambwe
• Chipata
• Lundazi
Central Province
• Chibombo
• Kabwe
• Kapiri-Mposhi
• Mkushi
• Serenje
Soil samples Unshelled groundnuts
Maize Processed commodities
Aflatoxin prevalence in Zambia Aflatoxin prevalence in Zambia
Incidence of aflatoxin producing fungi in soil
Key
Low
<100 cfu/g
Medium
100-499 cfu/g
High
500-999 cfu/g
Very high
>1000 cfu/g
Average CFU/g: 220-328000
Aspergillus population in Zambia
Incidence of aflatoxin producing fungi in Zambian soil
0
20
40
60
80
100
Non-toxin producers Toxin producers
Asp
erg
illu
s i
ncid
en
ce
(%
) Aspergillus population in Zambia
Levels of aflatoxin detected in maize grains at harvest & in storage
District Aflatoxin levels (ppb)
Harvest samples Storage samples (3 months)
Range Mean Unsafe (%) Range Mean Unsafe (%)
Chipata 0-101
1.4 0.6 0-109
5.0 5.2
Mambwe 0-27
1.1 0.7 0-207
21.7 8.2
Nyimba 0-11
0.8 0.5 0-214
7.2 7.7
Petauke 0-6
1.0 0.0 0-86
4.3 10.7
< 4 < 10 < 20 > 20
EU WFP/ COMESA
USA unsafe
Maximum allowable aflatoxin level (ppb)
Aflatoxin prevalence in maize grain
District Range Mean Proportion of samples deemed safe (%)
< 4 ppb 4.1-10 ppb > 10 ppb
Chipata 0.4-3435 176.5 28.6 17.9 53.6
Lundazi 0.7-310 63.6 15.8 15.8 68.4
Katete 0.3-482 77.9 6.7 6.7 86.7
Mambwe 1.1-5234 523.3 10.0 10.0 80.0
Nyimba 1.4-376 76.0 33.3 11.1 55.6
Petauke 1.7-775 147.3 13.3 20.0 66.6
Total aflatoxins (ppb) in groundnut flour, from markets & homesteads
Aflatoxin prevalence in groundnut flour
Aflatoxin levels (ppb) in maize flour collected from markets & homesteads
District Range Mean Proportion of samples deemed safe (%)
< 4 ppb 4.1-10 ppb > 10 ppb
Chipata 0.7-108.8 15.1 69.2 0.0 30.8
Katete 0.0-10.9 3.3 85.7 0.0 14.3
Mambwe 0.0-255 55.1 10.0 10.0 80.0
Nyimba 0.0-81.4 16.6 60.0 6.7 33.3
Petauke 0.1-103.2 17.5 73.3 6.7 20.0
Aflatoxin prevalence in maize flour
Prevalence of aflatoxin in peanut butter
Red: >20 ppb
Black: >10 ≤ 20 ppb
Orange: ≥4 ≤10 ppb
Green: < 4 ppb
Mean aflatoxin B1 levels in peanut butter (ICRISAT 2014)
Conclusion
Aflatoxin producing fungi are highly prevalent in Zambian soils
Consequently, the maize and groundnut commodities that are produced
and marketed in Zambia are contaminated by aflatoxins
There is need to join hands in mitigating this poison in maize/ gnut value
chains
www.iita.org A member of CGIAR consortium
-FAS
Research partners
Acknowledgement