Elsevier

The Lancet

Volume 365, Issue 9475, 4–10 June 2005, Pages 1950-1956
The Lancet

Articles
Reduction in exposure to carcinogenic aflatoxins by postharvest intervention measures in west Africa: a community-based intervention study

https://doi.org/10.1016/S0140-6736(05)66661-5Get rights and content

Summary

Background

Aflatoxins are fungal metabolites that frequently contaminate staple foods in much of sub-Saharan Africa, and are associated with increased risk of liver cancer and impaired growth in young children. We aimed to assess whether postharvest measures to restrict aflatoxin contamination of groundnut crops could reduce exposure in west African villages.

Methods

We undertook an intervention study at subsistence farms in the lower Kindia region of Guinea. Farms from 20 villages were included, ten of which implemented a package of postharvest measures to restrict aflatoxin contamination of the groundnut crop; ten controls followed usual postharvest practices. We measured the concentrations of blood aflatoxin–albumin adducts from 600 people immediately after harvest and at 3 months and 5 months postharvest to monitor the effectiveness of the intervention.

Findings

In control villages mean aflatoxin–albumin concentration increased postharvest (from 5·5 pg/mg [95% CI 4·7–6·1] immediately after harvest to 18·7 pg/mg [17·0–20·6] 5 months later). By contrast, mean aflatoxin–albumin concentration in intervention villages after 5 months of groundnut storage was much the same as that immediately postharvest (7·2 pg/mg [6·2–8·4] vs 8·0 pg/mg [7·0–9·2]). At 5 months, mean adduct concentration in intervention villages was less than 50% of that in control villages (8·0 pg/mg [7·2–9·2] vs 18·7 pg/mg [17·0–20·6], p<0·0001). About a third of the number of people had non-detectable aflatoxin–albumin concentrations at harvest. At 5 months, five (2%) people in the control villages had non-detectable adduct concentrations compared with 47 (20%) of those in the intervention group (p<0·0001). Mean concentrations of aflatoxin B1 in groundnuts in household stores in intervention and control villages were consistent with measurements of aflatoxin–albumin adducts.

Interpretation

Use of low-technology approaches at the subsistence-farm level in sub-Saharan Africa could substantially reduce the disease burden caused by aflatoxin exposure.

Introduction

Staple foods in west Africa and other parts of the developing world are frequently contaminated with aflatoxins, metabolites of aspergillus species.1 Aflatoxins have a carcinogenic action on the liver and act synergistically with chronic hepatitis B virus.1 A joint Food and Agriculture Organisation of the United Nations/WHO committee thus concluded that reduced intake of aflatoxins in places where infection with hepatitis B virus is endemic would have a substantial effect on the incidence of hepatocellular carcinoma,2 which accounts for about a fifth of all cancers in men in west Africa.3 Furthermore, aflatoxins can cause growth inhibition and immune suppression in animals.4 Consistent with these observations, aflatoxin exposure in west Africa at the time of weaning has been associated with impaired child growth5, 6, 7 and with a decreased immune response.8 These health effects further emphasise the potential benefit to public health of reducing aflatoxin exposure in developing countries.

Aflatoxin contamination of foods is especially severe after long-term crop storage because excessive heat, humidity, and insect and rodent damage result in proliferation and spread of fungal spores. The main crops affected include maize (corn) and groundnuts (peanuts), which together are the main dietary staples in many parts of sub-Saharan Africa. The reliance on subsistence farming, the limited food diversity, and toxin contamination result in high aflatoxin exposures throughout life.9 By use of a blood-based biomarker, aflatoxin–albumin adducts, data for several west African countries show that more than 98% of children and adults have detectable amounts in their blood.9, 10 Exposures are orders of magnitude higher than those allowed by regulation in Europe, the USA, and other parts of the developed world.

Several approaches can prevent aflatoxin exposure in developing countries.11 Because much food contamination occurs during postharvest storage, methods to remove nuts or kernels damaged by fungus before storage and to restrict humidity during storage could reduce fungal growth and toxin production. However, the effect of this strategy on exposure in subsistence-farming communities in Africa has not been assessed.

Our aim was to assess the use of improved methods of groundnut storage for subsistence farmers in a rural area of Guinea. Aflatoxin and infection with hepatitis B virus are endemic in this region, and groundnuts are the main source of aflatoxin exposure.12, 13, 14 We introduced a package of postharvest intervention measures to farmers in ten villages at the time of groundnut harvest and made comparisons with farmers in ten neighbouring villages that used usual storage practices.

Section snippets

Participants

The study was undertaken in 20 villages in the Kindia prefecture of lower Guinea, which were close to each other (within about 60 km of Kindia) to ensure that climate—as well as practices of groundnut cultivation, harvesting, and storage—were much the same in all villages. The ten intervention villages were to the north of Kindia and ten control villages were to the southeast to keep to a minimum the risk of prevention strategies being used in control villages.

In every village we recruited, by

Results

150 pairs of men and women were recruited from ten villages for both the intervention and control groups. Participants in the intervention group were younger than those in the control group (table 1). Three main ethnic groups (Soussou, Peulh, and Kissi) were represented, and intervention villages had an over-representation of Soussou compared with the control group. Neither age nor ethnic group correlated with concentrations of aflatoxin–albumin adducts. Data were obtained for 535 (89%) of 600

Discussion

This community-based intervention has shown a striking reduction in aflatoxin exposure by use of simple, low-technology postharvest practices in a rural subsistence-farming community. Exposure was more than halved 5 months after harvest in individuals from the intervention villages. Moreover, only 2% of individuals in the control villages had undetectable concentrations of aflatoxin–albumin adducts compared with about 20% in the intervention villages. In west Africa more than 98% of people test

References (22)

  • Some traditional herbal medicines, some mycotoxins, naphthalene and styrene

    IARC Monogr Eval Carcinog Risks Hum

    (2002)
  • Cancer in Africa: epidemiology and prevention. Liver cancer

    IARC Sci Publ

    (2003)
  • S Raisuddin et al.

    Immunosuppressive effects of aflatoxin in growing rats

    Mycopathologia

    (1993)
  • YY Gong et al.

    Dietary aflatoxin exposure and impaired growth in young children from Benin and Togo: cross sectional study

    BMJ

    (2002)
  • YY Gong et al.

    Determinants of aflatoxin exposure in young children from Benin and Togo, West Africa: the critical role of weaning

    Int J Epidemiol

    (2003)
  • YY Gong et al.

    Postweaning exposure to aflatoxin results in impaired child growth: a longitudinal study in Benin, West Africa

    Environ Health Perspect

    (2004)
  • PC Turner et al.

    Modification of immune function through exposure to dietary aflatoxin in Gambian children

    Environ Health Perspect

    (2003)
  • R Montesano et al.

    Hepatocellular carcinoma: from gene to public health

    J Natl Cancer Inst

    (1997)
  • CP Wild et al.

    The toxicology of aflatoxin as a basis for public health decisions

    Mutagenesis

    (2002)
  • CP Wild et al.

    Primary prevention of hepatocellular carcinoma in developing countries

    Mutat Res

    (2000)
  • Cited by (243)

    • Edible Nuts, Oilseeds and Legumes

      2023, Food Safety Management: a Practical Guide for the Food Industry, Second Edition
    View all citing articles on Scopus
    View full text