Over the past decade, development literature has placed significant emphasis on learning how agriculture
can be leveraged for improved nutrition and health. It is generally expected that agricultural development
should lead to improved health and nutritional outcomes, but evidence has been scant to support this
hypothesis (see Fan and Pandya-Lorch, 2002 for a detailed literature review). In this paper we argue that
Aflatoxins, which are poisons that occur naturally in the environment, create a negative nexus between
agriculture production and public health because any level of aflatoxin in foods makes it unsafe to
consume. It is possible that they could explain away lack of the positive link in certain geographies.
Aflatoxins are produced mainly by Aspergillus flavus and Aspergillus parasiticus fungi that are present in
soils and can contaminate many important staple crops: maize, sorghum, millet, rice, oilseeds, spices,
groundnuts, tree nuts, and cassava. Hot, humid, and drought-prone climates located within 40ºN and 40ºS
latitude are favorable environments for the fungus, implying that aflatoxins are most prominent in
developing countries.
Aflatoxin contamination during crop development and maturity depends on environmental conditions that
are optimal for the growth of fungi. During crop development, damage by pests (birds, mammals, and
insects) or the stress of hot, dry conditions can result in significant infections. Drought stress (elevated
temperature and low relative humidity) increases the number of Aspergillus spores in the air, increasing
the chance of contamination. In addition, other stresses (e.g., nitrogen stress) that affect plant growth
during pollination can increase the level of aflatoxin produced by the Aspergillus fungi. The impact of
drought on aflatoxin contamination is further exacerbated by the fact that drought stress can reduce the
ability of crops to resist the growth of aflatoxin-causing fungus. At the time of harvest, high moisture and
warm temperatures can increase the risk of aflatoxin contamination. Inadequate drying and improper
storage also increases the risk of aflatoxin contamination. Therefore, although environmental factors play
a role, lack of good agricultural practices and poor access to irrigation and fertilizer that are important for
plant health implies that developing countries are more likely to have higher aflatoxin prevalence in
crops. Exacerbating the problem, once crops are contaminated, their presence can only be confirmed
through specialized testing, they can be present in healthy looking grains and it is also not possible to
‘neutralize’ aflatoxins by, for example, washing or heating.
Chronic exposure to the B1 form of aflatoxins causes liver cancer (IARC, 2002), and is linked to cirrhosis
of the liver (Kuniholm et al., 2008) as well as to immune suppression in humans (Williams et al., 2004).
Evidence also suggests that aflatoxins may cause stunting in children (Khlangwiset et al., 2011). Because
of its natural presence in soils and the difficulty in verifying its presence, production, trade and
consumption of aflatoxin-contaminated crops is a significant concern in developing countries. Though
this issue is recognized by the global markets, in many developing countries aflatoxin-contaminated food
produced by the agriculture sector is consumed domestically, resulting in significant social costs of dietrelated
illness. This represents a failure of private markets to generate a socially efficient quantity of the
‘food safety’–a public good. Even when domestic food markets can discern the aflatoxin-free food, ‘food
safety’ good may be under-provided. This is because the contaminated food could still be consumed by
poorer households that are unable to participate in the aflatoxin-free food markets.