Kang’ethe, E. K University of Nairobi

andHannu Korhonen

MTT Agrifood Research Finland

CONTAMINATION OF FOODS AND FEEDS WITH AFLATOXIN AND

FUMONISIN

OUTLINE

• Introduction

• Objectives

• Results

• Challenges

INTRODUCTION

• Aflatoxin and Fumonisins are fungal metabolites produced by Aspergillus and Fusarium genera respectively.

• Aspergillus flavus and parasiticus are the primary fungal species producing aflatoxins

• Fusarium verticilloides mainly produce fumonisins.

• Aflatoxins have been listed as carcinogens (Hepatic carcinomas) by IARC and Fumonisins as potential carcinogens (esophageal cancers).

INTRODUCTION

• Aflatoxin and fumonisins affect the pillars of food security

o Access to food – contaminated food removed from the food chain

o Affordability – less volumes in market leads to increase in prices of staple foods

o Nutrition – though not directly connected but may affect the assimilation of ingested food due to liver damage –kwashiorkor and aflatoxin

o Safety – carcinogenic, mutagenic, teratogenic and immunosuppresant

INTRODUCTION

• In Africa, liver cancer mortalities are 8.19/100,000 population with liver cirrhosis at 3.85/100,000 (WHO,2004)

• In Kenya Aflatoxins are associated with 8.9 and 4.5 liver cancers incidences /100,000 in males and females respectively (IARC Globocan 2008)

• Mortalities in Kenya due to liver cancer are 2.58/1000,000 population and liver cirrhosis 2.47/100,000 population (WHO,2004)

• Associated with stunting in children no causal relationship yet established

OBJECTIVES

Determine the contamination levels in foods and feeds that contribute to household exposure

Explain why aflatoxin outbreaks in Lower and Mid Eastern none in North Rift

Knowledge attitudes and practices that may contribute to the exposure

CHARACTERISTICS

Nandi

Makueni

100 0 100 200 Miles

N

EW

S

Nandi

Makueni

Nandi

Elevation 1200-2500 m above sea level

Rainfall 1200 – 2000mm of rainfall ; one maize growing season

Makueni

Elevation 800m-1700m

Rainfall300 and 600mm

Two maize growing seasons

RESULTS-AFLATOXIN

NANDI

• Maize home grown 68% positive

• Maize market 73% positive

Mean 0.98± 0.06 ppb; 25% >10ppb

• Sorghum 37.08 ±8.85 ppb X1.8

• Millet

• Cow or goat milk 52% positive

• Breast milk 57% positive 0.0011 ±0.0017 ppt

MAKUENI

• Maize home grown 80% positive

• Maize market 91% positive

Mean 31.14±4.08 ppb 45% > 10ppb X31

• Sorghum 20.03 ±3.45 ppb

• Millet

• Cow or goat milk 77% positive 3 samples > 50ppt

• Breast milk 87% 0.0085 ±0.0011 ppt X 8.5

FUMONISINSNANDI

• Maize home 0.29 ±0.89ppm

• Maize market 0.34 ±0.67 ppm

• Sorghum home 1.63 ±1.88 ppm

MAKUENI• Maize home 1.31 ±2,09 ppm

X4.5

• Maize market 2.14 ±3.05 ppm X6.3

• Sorghum home 2.19 ±1.81 ppm X1.3

• Sorghum market 1.84 ±1.90 ppm

AFLATOXIN• Urine samples from children 80% were positive for AFM1 -

the children were recently exposed aflatoxin.

• The average stunting rate in Makueni and Nandi was 28.38and 17.47 % respectively and Underweight was 13.0 and2.9% in Makueni and Nandi respectively ( were < than 16.4%for underweight and 36.2% for stunting by the World Bank in2009)

• 55 and 75% of home grown maize and 60-85% of marketmaize samples (905) had both Aflatoxin and fumonisins inNandi and Makueni respectively – Co-occurrence of the twotoxins increases additively the probability of the risk forcancer (hepatocellular and esophageal)

RISK FOR STUNTING AND UNDERWEIGHT

The probability of underweight children being exposed to aflatoxins was 2.4 times more likely to occur in Makueni compared to 1.9 times among children in Nandi (OR= 2.4 and 1.9 respectively

The probability of children who are stunted and being exposed to aflatoxins was 6.8 times more likely to occur in Makueni compared to 2.1 times in Nandi (OR= 6.8 and 2.1 respectively

FUNGAL ISOLATIONThe most commonly isolated fusarium species in Nandi were

F. verticilloides and proliferatum which were also found to have the FUM 1 gene 75% and 65% respectively. The amount of fumonisin correlated with the presence of these species in maize kernels

Aspergillus flavus (82%) and parasiticus (73%) were the most commonly isolated in maize kernels in both Nandi and Makueni. A higher incidence of section flavi was isolated in Nandi

Toxigenic strains were more prevalent than non toxigenic strains

FUNGAL ISOLATIONMakueni toxigenic strains were mainly S type while in Nandi

were L type.

S strains produced more toxin (152,966 ppb) in vitro than the L strain (116,666 ppb).

The Aspergillus distribution mirrors the maize and sorghum contamination with aflatoxin. Makueni had 31 times higher aflatoxin in maize than Nandi.

The fact that less toxigenic L strains are more in Nandi and produce less amounts toxins – currently no acute toxicities but chronic exposure is sure. Future security uncertain

FOOD CONSUMPTION

Food consumption(maize) was 0.27 and 0.34kg /day in Makueni and Nandi respectively.

Considering the contamination levels of 0.98 and 31.14ppb in Nandi and Makueni, households were chronically exposed to 15ppb/kg/day in Makueni.

Exposure from milk, AFM1 6-14ppt/litre/day consumed in Makueni compared to 1ppt/litre/ day consumed in Nandi

KEY MESSAGES

The differences in the mycoflora in both sites is account for differences in contamination and exposure

Mitigation strategies should reflect these differences

Kenya should consider food diversity and functional diversity than over reliance on maize (maize >35% dietary energy/day)

CHALLENGES WE FACE

CONTROL OF THE CONTAMINATION

CHALLENGES

Low education of the populace

Barrier to Change – Poverty

Inadequate or non- existence extension services

Heavy reliance on maize to meet daily energy needs

Extension messages do not emphasize practice and attitude change – passing of information

Poor agronomical practices

CHALLENGES- EDUCATION &POVERTY

Attribute Makueni Nandi Kenya

Male Female Male Female Male Female

Popul % 48.8 51.2 48.3 51.3 49 51

Edu – no formal

3.6 4.2 12. 1 9.7 13 19

EduPrimary -

53.8 57.3 53.2 57.4 ND ND

Edu-Secondary

14.6 11.4 16.6 15.1 12 9

Poverty index

64.1 47.4 34-42

EDUCATION& POVERTY CHALLENGES

80% of the agricultural labor force is female

11% of standard 8 cannot do standard 3 arithmetic

CHALLENGES –EXTENSION SERVICES

• Number of Public extension officers -5470 across the country (private, non profit extension sectors)

• Kenya’s agricultural population is 72% of total population (1 extension officer to 5,265 farmers)

OVER RELIANCE ON MAIZE

Kenyans maize consumption will be 3.50 million tons in 2030, represents 2.9% of world maize consumption. 2030 SSA consumption will be 15.8 MMT 13.8% of worlds consumption (Rosegrant et al, 2009).

Cassava 100 g root provides 160 calories. Their calorie mainly comes from sucrose, forming the bulk in these tubers accounting for more than 69% of total sugars.

Potatoes have 36Kcal/10g of edible portion

AGRONOMIC CHALLENGES PRE- HARVEST

• Crop rotation was associated with reduction of aflatoxin and fumonisin (toxins) levels in maize. Intercrop without crop rotation did not help in reducing toxins levels in maize

• Stacking of maize stovers with maize cobs in the field increased toxin levels

• Use of soil amendments and agrochemicals also contributed to toxin reduction in maize

AGRONOMIC CHALLENGES –POST HARVEST

• Bad post harvest practices inNandi did not result into hightoxin accumulation due to theprevalence of non-toxigenic andless toxin producing strains inthe region

• The prevalence of toxigenic Aspergillus species in Makueni seems to override the effects of good postharvest practices that were done resulting in contaminated maize at harvest

ACKNOWLEDGEMENTS

• Funded by Finnish Ministry of Foreign Affairs

University of Nairobi Kenya

• MTT Agrifood Research Finland

•

• Kenya Agricultural Research Institute

Egerton University Kenya

EVIRA – Finnish Food Safety Authority24

ACKNOWLEDGEMENTSKenya Government Officials in Nandi and

Makueni counties

• Communities in the Makueni and Nandi counties

• Research team: Kang’ethe, E.K ; Okoth, S ; Korhonen ,H ; Mungatu, J. K; Shalo, P ; Wamae, L.W ; Hietaniemi, V; Joutsjoki ,V; Peltonen, K; Lindfors, S; Berg, S; Ramos, S; Anima, S. J ; Ouko, E ; Gatwiri,M ; Mburugu, C. K ; Ayugi, V; Mutele, B. N ; Kihara, S ; Kiaye, D ; Alberg, S.; Mburu, H.N; Nderitu,J; Nduhiu, G and Githinji, T. W.

• Project details available on www.safefood.uonbi.ac.ke

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