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2.5.3 Cottonseed
A. flavus is also a commensal in the cotton plant (Klich et al., 1984). Infection occurs
through the nectaries (natural openings in the cotton stem), which are important in pollination
(Klich & Chmielewski, 1985), or through cotyledonary leaf scars (Klich et al.,
1984). Upward movement occurs in the stem towards the boll, but not downwards from
boll to stem (Klich et al., 1986). Insect damage is also a potential cause of infection (Lee
et al., 1987), but insects are often well controlled in cotton crops. As in peanuts and
maize, temperature appears to be a major environmental factor in pre-harvest infection
of cottonseed (Marsh et al., 1973; Simpson & Batra, 1984). Daily minimum temperatures
above 24 °C, in combination with precipitation exceeding 2–3 cm, appear to lead to
extensive aflatoxin formation (Diener et al., 1987).
3. Management of Aflatoxin Contamination
A variety of approaches exist to limit aflatoxin production in crops. Limiting
aflatoxins in crops before and immediately after harvest involves strategies aimed at
reducing drought stress, by irrigation and weed control, by control of insect damage and
by the use of fungicides. Improvements in harvesting procedures, better drying, and
sorting of defective grains or nuts are all beneficial. The principles of safe storage are
well known, and cannot be overemphasized. Physical methods to reduce aflatoxins in
crops are widely practised, especially in developed countries. The technology involved
in these approaches to limiting and reducing aflatoxins are relatively simple and
inexpensive, and can be practised even by small-scale farmers. For heavily contaminated
commodities, the use of chemical treatments can effectively reduce aflatoxins, but then
use of the resulting materials is limited to animal feed. These procedures, systems and
approaches are outlined below.
3.1 Intervention strategies
Interventions to reduce aflatoxin-related exposures can be considered in terms of
those which are applicable at the individual level or those applicable at the community
level (Figure 1).
3.1.1 Individual level
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Dietary changes to avoid foods contaminated with aflatoxin are rarely an option in
countries of high exposure where staple foods are contaminated (e.g. maize or peanuts).
However, efforts to improve crop and dietary diversity must be made. Sorting procedures
can be of value, but require education at the consumer level. Chemoprevention aims to
diminish the toxicological effects of aflatoxins once exposure has occurred. Clinical