The current report of the Codex Alimentarius Commission (FAO) on contaminants in foods includes a new proposal for maximum levels for fumonisins in maize and maize products. As maize is a staple food in most parts of Africa it was clear for African delegations that the establishment of maximum levels for maize was long overdue in order to protect consumer health. These delegations did not support the previously proposed maximum level of 5,000 μg/kg fumonisins. In most parts of Africa, approximately 400 to 500 g of maize are consumed daily.
The Committee agreed on the maximum levels of 4,000 μg/kg for raw cereal grains and 2,000 μg/kg for maize flour and maize meal. It was settled that exposure and impact assessment should be undertaken by the Joint FAO-WHO Expert Committee Report on Food Additives (JECFA) within three years for reconsideration of the proposed maximum levels. The provisions taken by the Codex ruling concerning mycotoxins are very important first steps to assess maximum levels for these toxic substances.
In the past 10 years, the BIOMIN Mycotoxin Survey has focused on testing a wide variety of commodities for the presence of the main mycotoxins found worldwide. Out of a total of 4,500 maize samples from around the world 76% tested positive for fumonisins with an average concentration of 2,200 μg/kg.
Fumonisins have been shown to be toxic to pigs and poultry and the main cause of equine leucoencephalomalacia, a fatal disease of horses. Long term-experience has shown that fumonisin levels as low as 750 μg/kg in finished feed can pose a potential risk for some livestock species, especially sows, piglets and horses.
The results of this worldwide survey have shown that within the 26,000 samples that have been analyzed so far, 76% of all samples contained at least one mycotoxin and 42% of these samples contained more than one toxin. This shows the importance of considering the fact that mycotoxins tend to co-occur in many commodities and that the presence of multiple toxins may have even higher impacts on the animal than would be the case for only one mycotoxin. This scenario was unfortunately not considered by the Codex ruling.
Co-occurrence of mycotoxins may be one important reason for divergences in effects described in scientific studies in which, in contrast to in the field situation, mostly purified toxins are used. In field outbreaks, naturally contaminated feeds may contain multiple mycotoxins and thus apparently lower contamination levels of a single specific mycotoxin can be associated with more severe mycotoxicosis.
Data on the effect of combinations of toxins on animal health are rare and more data from different countries are needed to assess the problem of mycotoxin co-occurrence. More studies need to be conducted to provide information on the interactions of multiple mycotoxins under field conditions, with mycotoxin concentrations that commonly occur in the sub-acute contamination range.