IARC MONOGRAPHS ON THE EVALUATION OF CARCINOGENIC ...

ANNEX 293
Furthermore, the reduced animal production increases protein energy malnourishment in
vulnerable groups, e.g. children and pregnant women.
7. Conclusions
This Annex has dealt in general terms with a number of very complex issues. Many
areas have been highlighted which are in need of much future research to provide information
that is directly relevant not only to public health, but also to availability of a
wholesome food and feed supply worldwide. The following general conclusions and
recommendations emerged from the deliberations of the Working Group.
1. Limiting aflatoxin occurrence in crops before harvest can be achieved by
limiting drought and high temperature stress, controlling weeds, reducing
insect damage, using effective harvesting techniques and reducing Aspergillus
spore numbers in soil by crop rotation.
2. Genetic engineering may offer new ways of limiting the pre-harvest contamination
of some crops by aflatoxins.
3. Aflatoxins can be controlled in susceptible crops after harvest by controlling
factors which affect fungal growth, e.g. water activity, temperature, gas
atmospheres, and the use of insecticides or preservatives. The prime consideration
for storage of grains and nuts is to maintain the water activity (by
control of moisture content) below the limit for fungal growth.
4. Aflatoxin levels can be reduced in stored commodities by physical means, such
as colour sorting, density flotation, blanching and roasting.
5. Where approved, aflatoxin levels in commodities destined for animal feeds can
be reduced by chemical processes. Such processes include agents which bind
aflatoxins, such as adsorbent clays, and the ammoniation process. The main
use for ammoniation is in elimination of aflatoxin from feed for dairy cows.
6. Increased liver cancer incidence associated with aflatoxin exposure occurs in
areas of the world where chronic high levels of aflatoxins (often many times
higher than regulatory limits) and endemic infection with HBV or HCV occur
together. Populations with a low prevalence of HBV chronic carriers and a low
mean aflatoxin intake are unlikely to achieve a decrease in liver cancer cases
by introducing lower aflatoxin limits. In contrast, in populations with a high
prevalence of HBV chronic carriers and high exposure to aflatoxin, measures
to reduce aflatoxin exposure would be desirable and beneficial.