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Contamination of foods and feeds with Aflatoxin and fumonisin
This document summarizes research on the contamination of foods and feeds with aflatoxin and fumonisin in Kenya. The research found: 1) Maize and milk samples from Makueni county had much higher levels of aflatoxin and fumonisin contamination than samples from Nandi county, with Makueni maize containing 31 times more aflatoxin. 2) Rates of stunting and underweight in children were higher in Makueni, and exposure to aflatoxins increased the likelihood of these conditions. 3) Differences in fungal strains between the regions help explain the differing contamination levels, with more toxigenic strains found in Makueni.
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Contamination of foods and feeds with Aflatoxin and fumonisin
- 1. CONTAMINATION OF FOODSAND FEEDS WITH AFLATOXIN AND FUMONISIN Kang’ethe, E. K University of Nairobi and Hannu Korhonen MTT Agrifood Research Finland
- 2. OUTLINE • Introduction • Objectives • Results • Challenges
- 3. INTRODUCTION • Aflatoxinand 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).
- 4. INTRODUCTION • Aflatoxinand 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
- 5. INTRODUCTION • InAfrica, 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
- 6. OBJECTIVES Determine thecontamination 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
- 7. CHARACTERISTICS Nandi Makueni 100 0 100 200 Miles Makueni N Nandi W E 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
- 8. 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
- 9. FUMONISINS NANDI •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
- 10. AFLATOXIN • Urinesamples from children 80% were positive for AFM1 - the children were recently exposed aflatoxin. • The average stunting rate in Makueni and Nandi was 28.38 and 17.47 % respectively and Underweight was 13.0 and 2.9% in Makueni and Nandi respectively ( were < than 16.4% for underweight and 36.2% for stunting by the World Bank in 2009) • 55 and 75% of home grown maize and 60-85% of market maize samples (905) had both Aflatoxin and fumonisins in Nandi and Makueni respectively – Co-occurrence of the two toxins increases additively the probability of the risk for cancer (hepatocellular and esophageal)
- 11. RISK FOR STUNTINGAND 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
- 12. FUNGAL ISOLATION Themost 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
- 13. FUNGAL ISOLATION Makuenitoxigenic 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
- 14. FOOD CONSUMPTION Foodconsumption(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
- 15. KEY MESSAGES Thedifferences 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)
- 16. CONTROL OF THECONTAMINATION CHALLENGES WE FACE
- 17. CHALLENGES Loweducation 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
- 18. 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 3.6 4.2 12. 1 9.7 13 19 formal Edu Primary - 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
- 19. EDUCATION& POVERTY CHALLENGES 80% of the agricultural labor force is female 11% of standard 8 cannot do standard 3 arithmetic
- 20. 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)
- 21. OVER RELIANCE ONMAIZE 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
- 22. 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
- 23. AGRONOMIC CHALLENGES –POSTHARVEST • Bad post harvest practices in Nandi did not result into high toxin accumulation due to the prevalence of non-toxigenic and less toxin producing strains in the 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
- 24. ACKNOWLEDGEMENTS • Fundedby Finnish Ministry of Foreign Affairs University of Nairobi Kenya • MTT Agrifood Research Finland • • Kenya Agricultural Research Institute Egerton University Kenya EVIRA – Finnish Food Safety Authority 24
- 25. ACKNOWLEDGEMENTS Kenya GovernmentOfficials 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 25