Prevalence of aflatoxins in Zambian maize and groundnuts

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