**2. The global problem of AF in crops and food**

The prevalence of AF in crops and livestock is a serious problem in many parts of the world, undermining public health and development efforts. AF are highly toxic, cancer causing fungal metabolites known to cause immune-system suppression, growth retardation, liver disease, and death in both humans and domestic animals. According to the United Nations Food and Agriculture Organization (FAO), 25% of world food crops are affected, and coun‐ tries that are situated between 40ºN and 40ºS are most at risk. Over 4.5 billion people in de‐ veloping countries are at risk of chronic AF exposure [9]. Unless AF levels in crops and livestock are effectively managed, international development efforts to achieve greater agri‐ cultural development, food security and improve health will be undermined.

AF are very stable and persistent, so they are difficult to remove. Due to they are contained in many crops that are consumed by animals, AF have turned into a serious animal problem too. The most susceptible animals are rabbits, turkeys, chickens, pigs, cows and goats [10]. AF can be transmitted from animals to human food (by eggs, meat and dairy) with the con‐ sequent risk to human health.

Even non-mouldy foods or raw materials may contain AF. Spores can be transferred by in‐ sects (especially flies, wasps and bees) or by birds to foods where the spores germinate, pro‐ duce mycelium, and AF are excreted. Seeds can contain AF by infection of the egg-cells of the flowering plants. The spores of *A. flavus* and *A. parasiticus* can germinate on the stigma surfaces of plants, then the germ tube penetrates to the developing embryo mimicking pol‐ len germ tubes. The mycelium can establish an endotrophic relationship which is not harm‐ ful for the healthy plant. However, if the plant is under drought stress, then significant levels of AF may be produced in the plant tissue during growth in the field. Under these circumstances food commodities may already be contaminated at harvest and, although the concentrations are never as high as those formed in stored commodities, they can be eco‐ nomically significant [11, 12].

The danger of AF lies in their mode of action by inhibiting the incorporation of precursors for the synthesis of DNA, RNA and proteins; they also block the action of some enzymes that are responsible for the synthesis of nucleic acids, causing centrilobular necrosis in the liver, polymorphonuclear infiltration and fatty degeneration. AF toxicity depends on the dose, the exposure degree, the age, the nutritional status of the animal and the possible syn‐ ergic effects of the chemical agents to which they are exposed [13]. Some secondary metabo‐ lites produced by Aspergillus species are harmful for animals too. That's the case of cyclopiazonic acid (CPA), which causes necrosis of liver or gastrointestinal tissue and ne‐ crotic changes in skeletal muscle and kidney [14, 15].

The economic impacts of AF contamination can vary greatly among affected food and feed commodities. These differences include the severity of the contamination problem, the geo‐ graphic range of AF problems, the types of AF control methods available, and which sectors bear the burden of the cost of AF contamination. All of these factors affect whether AF con‐ trol methods are adopted [16]. AF and mycotoxins in general have not been widely priori‐ tized from a public health perspective in low-income countries. This is because knowledge of mycotoxins and the full range and scale of their adverse health effects is incomplete and the known risks are poorly communicated to governments in regions where the contamina‐ tion is greatest [17]. Matters that have to be considered by government to avoid diseases from aflatoxicosis are: an opportune and nonexpensive analytic detection, unifying world‐ wide government regulations, deviation of AF-contaminated commodities from the food supply, improving research on the biosynthesis and molecular biology of AF, and designing new control strategies for the abolition of AF contamination of food crops, inter alia [10].
