1. Felicia Wu and Yan Liu
Department of Environmental & Occupational Health
Graduate School of Public Health
University of Pittsburgh
And
Clare Narrod, Marites Tiongco, Rosemary Scott
International Food Policy Research Institute
International Food Policy Research Institute University of Pittsburgh
International Center for the Improvement of Maize ACDI/VOCA/Kenya Maize Development Program
and Wheat Kenya Agricultural Research Institute
International Crops Research Institute for the Semi- Institut d’Economie Rurale
Arid Tropics
Uniformed Services University of the Health Sciences
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2.  Aflatoxin: background & health effects
 Influence diagram linking aflatoxin to sequelae
 Burden of disease caused by aflatoxin
 Global liver cancer cases
 Expected liver cancer cases in Kenya
 Results using Kenya Integrated Household Budget Survey (KIHBS, 2005-2006) data
to
 Limitations and future directions
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3.  Produced by Aspergillus flavus, A. parasiticus
 Maize, peanuts, almonds, pistachios, hazelnuts
 Exposure highest in warm regions when these foods
are dietary staples  Poor nations
 (Postulated) Human health effects
 Liver cancer (fatal in 1-3 months)
▪ Synergizes with chronic hepatitis B virus (HBV)
infection: >> higher risk than either exposure alone
 Childhood stunting
 Acute aflatoxicosis
 Cirrhosis
 Immune suppression
 A. flavus  invasive aspergillosis
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4. Hepatitis B Hepatitis C Liver cancer Cirrhosis of the
liver
WORLD 1.63 0.84 9.47 11.99
AFRICA 1.64 0.72 8.19 3.85
THE AMERICAS 0.57 0.92 4.16 12.87
EUROPE 0.83 0.52 7.33 20.94
SOUTH-EAST 2.21 0.82 3.50 12.57
ASIA
WESTERN 1.60 0.88 21.68 9.53
PACIFIC
KENYA 0.50 0.22 2.58 2.47
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5. Plant stress in Poor storage
field conditions
Fungal growth and
aflatoxin accumulation
in food crops
Intermediate
Liver Acute
Aflatoxin dihydrodiol
biotransformation to aflatoxicosis
consumption binds to liver
aflatoxin-8,9-epoxide
proteins
AF-8,9-
Altered intestinal Modulation of
epoxide binds Liver cancer
integrity cytokine expression
to DNA
Source:
Stunted Chronic hepatitis B
growth in
Immune Wu 2010
suppression infection
children 5

6.  How many global
liver cancer cases
each year are
caused by
aflatoxin?

7.  Dose-response assessment  Exposure assessment
 Slope of curve = cancer “potency”  Find, for each nation:
▪ Aflatoxin  liver cancer: 0.01 cases /  Daily consumption of maize / nuts
100,000 / yr / ng/kg bw/day
 Aflatoxin levels in maize / nuts
▪ Aflatoxin + Hepatitis B virus liver cancer:
0.30 cases / 100,000 / yr / ng/kg bw/day  Hepitits B virus prevalence
 Population size
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8.  Global population cancer risk =
Σ(all nations)
([PopulationHBV+ /100,000 * PotencyHBV+ * Average aflatoxin intake] +
[PopulationHBV- /100,000 * PotencyHBV- * Average aflatoxin intake])
 PotencyHBV+ = 0.30 cases per 100,000/yr per ng/kg bw/day
 PotencyHBV- = 0.01 cases per 100,000/yr per ng/kg bw/day
Data Sources:
• Hepitits B virus prevalence: WHO, multiple peer-reviewed
papers
• Aflatoxin exposure & food consumption: WHO GEMS
database, multiple peer-reviewed papers
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9. 13 DALYs per case  328,000-2,000,000 DALYs/yr
Liu Y, Wu F. (2010). “Global Burden of Aflatoxin-Induced Hepatocellular Carcinoma:
A Risk Assessment.” Environmental Health Perspectives 118:818-824.
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10. World Region # DALYs annually attributable to
aflatoxin-induced HCC
Africa 147,940-778,700
North America 143-182
Latin America (inc. Central America) 8,749-65,520
Eastern Mediterranean 10,231-219,960
Southeast Asia 41,600-583,700
Western Pacific 117,260-360,230
Europe 2093-7,228
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11.  Estimated daily maize and peanut consumption (KIHBS 2005):
▪ Maize: 357 g/day/person
▪ Peanuts: 44 g/day/person
 Hepatitis B Virus prevalence: 11-15%
 Lifetime average daily dose (LADD) of aflatoxin in Kenyan adults
5.2 to 200 ng/kg bw/day
  Estimated aflatoxin-induced Liver cases/yr: 82- 4,080
  Estimated DALYs associated with aflatoxin-induced Liver
Cancer: 1066-53,040 per year
 Note: These exposures do not take into account occasional
excursions to very high aflatoxin levels (e.g., 2004, 2010), as acute
toxicoses are not associated with subsequent HCC.
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12.  Estimated daily maize consumption in urban vs rural
areas:
 Maize: urban areas 352 g/day/person, rural 624
g/d/ person
 Currently no way to estimate aflatoxin exposure in
urban vs. rural populations
 What we do know: rural maize consumption 1.77 times
higher than urban maize consumption
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13. Aflatoxin exposure HBV AF-induced cases
(ng/kg bw/day) prevalence of HCC[1]
Africa
Lower 5th 10 9 11,380
percentile
Geometric mean 42 13 26,100
Upper 95th 180 20 59,900
percentile
Kenya
Lower 5th 5.2 11 82
percentile
Geometric mean 32.2 12.8 578
Upper 95th 200 15 4080
percentile
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14.  Globally - 25,200-155,000 aflatoxin-induced liver cancer
cases each year
  Translates to 328,000 to 2,000,000 DALYs per year
 Most DALYs are suffered in 3 world regions: Africa, Southeast
Asia, and Western Pacific (China)
 Kenya 82- 4,080 aflatoxin-induced HCC cases/yr:
 Translates to 1066-53,040 DALYs associated with aflatoxin-induced
HCC
 But secondary data of different quality – poor quality data leads to
high variance
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