Aflatoxins in Maize, an Unsolvable Burden for the North-East

It is true that maize for the most part stops in animal feed troughs and does not reach our plates, but the risk arising from the so-called aflatoxins is high precisely because of their ability to transfer to derived products, such as milk.

When we speak of aflatoxins we mean mycotoxins, that is, toxic chemical substances produced by fungi (in particular Aspergillus) or moulds. These are substances discovered relatively recently, around 1960, which under particular environmental conditions colonise various plant varieties such as maize, grains in general, peanuts and other oilseeds.

At the chemical level they are classified with an identifying letter, which is the designation under which we find them cited by the media.
Category B, considered the most dangerous, derives its code from "blue" to highlight the chromatic fluorescence spectrum that these substances emit when exposed to contact with ultraviolet rays.
Category G therefore indicates a "green" fluorescence and is considered less dangerous than category B1.
M, on the other hand, indicates the "metabolites" of aflatoxin B1, essentially the vehicle for contact with the human body, which are found mainly in milk -m in fact stands for "milk"- from animals fed with contaminated feed.

The most recent scientific data show how aflatoxins are among the most carcinogenic substances known. They are suspected of having a mutagenic action, that is, of inducing genetic mutations, through biotransformation processes such as epoxidation, hydroxylation and other non-enzymatic processes.
Therefore, while on the one hand the bonds (covalent adducts) that the epoxide causes at the DNA level are responsible for the carcinogenic reaction, the interaction between the epoxide and proteins is to be considered the main cause of the high level of toxicity of aflatoxins.

We human beings absorb aflatoxins through the digestive system; here metabolic activation and the "attempt" at detoxification by the intestinal mucosa and the liver take place. The toxicity dose that proves lethal to humans has been estimated in rather infinitesimal quantities, varying between 0.6 and 10 parts per million (PPM = mg/kg).
A first finding is therefore the wide variation between exposed subjects as regards the metabolic activation of aflatoxin B1; secondly, it must be said that several studies appear to have demonstrated the protective action of certain drugs such as Oltipraz or phenobarbital against the toxic action of aflatoxins.

The European Union (directive 32/2002) therefore establishes infinitesimal limits for the presence of aflatoxins in the various products: 4 ppb (parts per billion) of aflatoxins for human foods; in animal feed the maximum concentration currently permitted is 50 ppb for the feed of calves, lambs, poultry and pigs, while it is lower for dairy cattle, falling to 10 ppb. How is the presence of aflatoxins detected? Essentially through analysis procedures based on spectrometry: the most frequent are ELISA (Enzyme-linked immunosorbent assay), famous as a test for HIV, and again liquid chromatography, HPLC or TLC.

Unfortunately, to date there is no precise and direct toxicological data to assess the impact of aflatoxins on humans. Recourse has therefore been made to data gathered on animals and to statistical projections. Among the best-known cases of epidemiological evidence we can refer to a case that occurred in India where the local population consumed maize contaminated with at least 2ppm of aflatoxin B1: the deaths numbered over 100 out of as many as 400 patients who developed forms of chronic hepatitis.
Even in the absence of epidemiological studies we can reasonably assume some criteria of scientific validity: the impact on health depends first of all on the quantity of mycotoxin taken in with food and on its level of toxicity, on the physical characteristics of the exposed subject and on various dietary factors. In order to speak of a direct correlation between exposure or ingestion and the development of particular human diseases, one must be certain of the presence of aflatoxins in the product, certain that exposure has occurred, and establish at least a relationship of reproducibility between the pathological evidence in the animal field and in the human field.

From this point of view Italy presents an aflatoxin risk that is essentially linked to the importation of contaminated foods of equatorial or subtropical origin.
Contamination in fact occurs predominantly in hot-humid climate conditions, but it also depends strongly on cultivation and storage practices and on the type of substrate involved, since some products are more susceptible than others to fungal growth. Mycotoxins develop both on plants before harvest (field contamination) and in plant commodities after the harvest itself, during the processes of storage (warehouses, silos), processing and transport. The foods most exposed to direct contamination are above all cereals (maize, wheat, rice, barley, rye, etc.), oilseeds (peanuts, sunflower, cottonseed, etc.), nuts and dried fruit, legumes, spices, coffee and cocoa.
And while the climate changes of recent years have led to a steady increase in the presence of aflatoxins in maize (for example) throughout the Po Valley, nevertheless the system of production and post-production controls considerably reduces the risk that shares of contaminated product enter the distribution circuit. The probability of introducing a contaminated product is greater for those countries that notoriously do not exercise regular control of imports and towards which the most contaminated batches are directed, perhaps already rejected by others.

It nonetheless remains an issue and a problem, that of aflatoxins, strongly felt in regions such as the North-East with a markedly maize-growing vocation, which in the summer of 2012 alone saw about 1/4 of the regional production "burned" due to aflatoxin contamination, as reported by the newspaper Cronaca del Veneto on 2 March.
The Gazzettino of the following day, 3 March, seems to fear possible loopholes in post-production control with the consequent entry into the feed market of contaminated commodities. And the Mattino di Padova goes so far as to hypothesise (reporting the position of Coldiretti of Padua) that behind the fears of aflatoxin contamination last summer there may in reality lie a speculative manoeuvre by the large-scale grain distribution sector.

Attention must not, however, be reduced, as demonstrated by the Germany case cited by Sole24Ore of 4 March, where over 10,000 tonnes of contaminated maize from Serbia reportedly entered the feed-mill circuit, while another 35,000 tonnes belonging to the same supply were reportedly blocked at the port customs, upon the landing of the goods, on the instructions of the agriculture ministry of the Land of Lower Saxony.