Carcinogen Role of Food by Mycotoxins and Knowledge Gap

In today’s world health and safety are among the basic human needs. Ensuring food safety has been a major focus of international and national action over the last decades. Both, microbiological and chemical risks are of concern. The “World Health Organization” (WHO) has identified as significant sources of food-borne diseases contamination of food and feed by mycotoxins (toxic metabolites of molds) and the contamination of fishery products by phycotoxins (toxins produced by algae). Despite public health and prevention managers have paid particular attention to mycotoxins, in several areas of the world they are still an important food safety issue (Fig 1). Fig. 1. Notifications for food and feed in 2005 (from EU rapid alert system, by European Commission 2006). Mycotoxins can cause diseases in humans, crops and animals that have led many Countries to establish limits on mycotoxins in food and feed to safeguard people’s health, as well as the economical interests of producers and traders.

Human exposure to mycotoxins may occur at all levels of the food chain: via consumption of plant-derived products contaminated with toxins (cereal grains, coffee, oil seeds, spices, fruit juices, and beverages as wine and beer), or even from carrying-over of mycotoxins and their metabolites (e.g.aflatoxin M1) in milk, meat, and other products of animal origin contaminated because of using feeds with mycotoxins (Bhat et al., 2010;CAST, 2003), or by exposure to air and dust containing toxins (Jarvis, 2002;).In recent times, in actual fact, concerns have been raised about exposures to mycotoxins in indoor environments as a damp houses and buildings (Straus, 2011).
In Ferrante and colleagues study (2007) was carried out a monitoring of wheat samples because it is the main ingredient of bread and pasta, basic aliments, and quantitatively substantial of Mediterranean diet.Wheat samples, from various areas of East Sicily, was analyzed for carcinogenic micotoxins (AFLs, OTA, ZEA).The results show that all samples collected do not contained AFLs whereas OTA and ZEA have been found in the samples to medium concentrations of 0.01 mg/kg and 0.108 mg/kg, respectively.Instead all samples contained OTA and ZEA.So this study confirmed the previous findings of the related studies present in literature.
The main mycotoxins that contaminate food rarely are found in indoor environments.Indeed, Penicillium and Aspergillus are the main contaminants of both food and damp buildings, though in the latter they produce different mycotoxins.
The genera found in outdoor air, as Aspergillus and Penicillium, are not associated with human or animal toxicosis.
The molds associated with buildings comprise a narrow group of species that grow thanks to the nutrients present in building materials and to the available water (Jarvis & Miller, 2005;Straus, 2011).
A. versicolor, that is often encountered in damp buildings, typically produces Sterigmatocystin, a class 2B carcinogen (IARC, 1993;Jarvis & Miller, 2005).The most frequent toxigenic fungi in Europe are Aspergillus, Penicillium and Fusarium (Bhat et al., 2010;Creppy, 2002), while the prevalence of specific toxins around the world is as follows: AFLs in Africa and in the Asian continent; AFLs and FUMO in Australia; AFLs, OTA, It is hard to define mycotoxins, as well as to classify them.The classification schemes tend to reflect the training of the categorizing person (Zain, 2011).
AFLs are important causal factors of liver cancer while FUMO and OTA are suspected to have an important role in the etiology of esophageal cancer and in the famous BEN (Balkan Endemic Nephrotoxicity) respectively (Tab.2.).
The impact of mycotoxins on health depends on various factors, as the fungus species, the daily intake of the mycotoxins consumed and their concentration, the toxicity of the compound, their mechanisms of action, the body weight of the individual, the presence of other synergic or protective elements present in the food, the metabolism and defense mechanisms of the host (Hussein & Brasel, 2001;Stayn, 1995).
Their toxic effects, however, are mostly proven in experimental models.
The inaccuracy of extrapolation of results for humans is an important point for research; it may be explained by the lack of adequate food consumption data, by the gap of knowledge about health risks associated with the actual proposed limits and by the big possibility of synergism or additive toxicity with other mycotoxins present in the same food (Creppy, 2002).

Aflatoxins
The main aflatoxins include aflatoxins B1, B2, G1 and G2 (see Fig. 4) produced by Aspergillus flavus and A. parasiticus that contaminate plants and plant products.
Among all aflatoxins, the Aflatoxin B1 (AFB1) is the most potent hepatocarcinogenic substance known; recently, after a thorough risk evaluation, it has been proven to be also genotoxic (Van Egmond & Jonker, 2004;Zain, 2011).
In 1993, the WHO-International Agency for Research on Cancer (WHO-IARC, 1993 a,b) evaluated the carcinogenic potential of Aflatoxins and they were classified as carcinogenic for humans (Group 1).In particular, studies have shown that AFB1 may act in synergy with hepatitis B virus in human hepatocellular carcinoma.
For this type of carcinogen, it is generally felt that there is no threshold dose below which no tumor formation would occur.In other words, only a zero level of exposure will result in no risk.
Aflatoxins are known to bind DNA and induce mutagenic and carcinogenic effects in rats.
Especially the AFB1 is bioactivated from its original form to a mutagenic and carcinogenic metabolite (Hussein & Brasel, 2001).Aflatoxins have been found also in tissues of children suffering from Kwashiorkor and Reye's syndrome, that has led to the hypothesis that they could also be causal factors for these diseases.
Reye's syndrome, in particular, is characterized by liver and kidney enlargement and cerebral edema (Hussein & Brasel, 2001).
Aflatoxins M1 (AFM1) and M2 (AFM2) are the hydroxylated metabolites of aflatoxin B1 (AFB1) and B2 (AFB2) respectively and may be found in milk products obtained from livestock that have ingested contaminated feed.
Aflatoxins can be present in cows milk, pork meat or chicken eggs if those animals were exposed to aflatoxins in their feed.The main sources of aflatoxins in feeds are peanuts, meal maize and cottonseed meal (Creppy, 2002;McLean & Dutton, 1995;Richard, 2007).
The concentration of AFB1 in feed can be strongly reduced thanks to good manufacturing and storage practices.If those preventive measures fail, however, AFB1 can be reduced in feed by blending (or diluition) or by physical or chemical treatments.Physical treatments include heat, microwaves, gamma-rays, X-rays and ultra-violet light (Creppy, 2002).About 0.3-6.2% of AFB1 from animal feed is transformed into AFM1 in milk.The toxicity of AFM1 is about one order of magnitude less than that of AFB1 (Creppy, 2002;Van Egmond & Jonker, 2004 ;Voss et al., 2002).
AFM1 is a possible carcinogenic to humans.
In literature are not yet known specific exposure biomarkers for aflatoxins.
The AFM1 intake from milk is calculated to be 6.8 ng/person per day for the European diet, 3.5 ng/person per day for the Latin American diet, 12 ng/person per day for three son per day for the Middle Eastern diet and 0.1 ng/person per day for the African diet (Creppy, 2002).
Aflatoxins have been regulated with limits in many Countries of the world; for more detailed information see section 6.
OTA toxicity has been intensively studied (Mally & Dekant, 2009;Abrunhosa et al., 2010); the kidney is the target of OTA toxicity in all animal species exposed to this mycotoxin.
Dietary human exposure to OTA is been suspected to be involved in BEN, a progressive kidney disease associated with an increased risk for the development of urothelial cancers, that occur in some rural areas of Bosnia, Bulgaria, Croatia, Romania, and Serbia.
OTA has a very high affinity to plasma proteins, as 99.9% of the circulating OTA is bound to plasma proteins.
OTA is poorly metabolized and slowly excreted with plasma half-life of 230 hrs in humans (Mally & Dekant, 2009).
Inappropriate farm management practices have been associated with higher OTA amounts.It is also known that meat may contain OTA through secondary contamination and carryover (Pfohl-Leszkowicz & Manderville, 2007).
Studies have not completely identified so far the mechanism nor the extent of the carcinogenic potential of OTA in humans; therefore, OTA is classified by IARC as possible carcinogen (Group 2B) (Abrunhosa et al., 2010).
The provisional tolerable weekly intake (PTWI) for OTA established by the Joint FAO/WHO Expert Committee on Food Additives and Contaminants is 100 ng/kg bw/week (Juan et al., 2008;Kabak, 2009;Pfohl-Leszkowicz & Manderville 2007).Some scientist have shown that the DNA lesions (on dG exclusively) induced by OTA in vivo exposure were no longer repaired in case of repeated exposure; these lesions could then be proposed as a marker of exposure in populations at risk (Creppy, 2002;Abrunhosa et al., 2010).
Prevention of growth of A. ochraceus consists in application of standard practices as rapidly and thoroughly drying the grains and also fumigation, aeration and cooling, sealed storage and controlled atmosphere.
An important preventive factor for correlated pathologies is the diet rich in antioxidants, vitamins, amino acids and aspartame.In fact positive and protective effects of aspartame in kidney and brain have been reported.Actually aspartame is used for prevention of OTA genotoxicity in kidneys (Creppy, 2002).
Several studies are available on OTA-induced nephrotoxicty and renal tumor formation.
Oxidative DNA damage induced by direct oxidation of DNA constituents or through oxidative stress has been implicated in renal tumor formation and it represents the most accepted theory in current literature (Mally & Dekant, 2009;Abrunhosa et al., 2010).
However, currently the OTA carcinogenicity pathway is unknown because it has not yet been observed sperimentally.

S e v e r a l p a t h w a y s o f k i d n e y t u m o r i g e n i c i t y b y o c h r a t o x i n h a v e b e e n p r o p o s e d b y scientists:
Alteration of gene expression (Kamp et al., 2005;Kuan et al., 2008;Mally & Dekant, 2009 ;Reddy & Bhoola, 2010).
EFSA has recently established a tolerable weekly intake (TWI) of 120 ng/kg of body weight for OTA.While the exposure of the general population in Europe is below this TWI, additional data regarding OTA-exposure of infants and children are considered necessary to account for their specific dietary preferences and needs (EFSA, 2006;Kabak, 2009;Mally & Dekant, 2009).6) is a toxic metabolite closely related to the aflatoxins structure and consists of a xanthone nucleus attached to a bifuran structure.The IARC have included the sterigmatocystin in group 2B, which means it is a likely carcinogenic to humans.
It has been found in mouldy grain, green coffee beans and cheese although current information on its occurrence in foods is again incomplete and poor.It appears to occur much less frequently than the aflatoxins perhaps because the analytical methods for its determination have not been as sensitive, therefore it is possible that small concentrations of Sterigmatocystin in food commodities may at times not have been detected.Sterigmatocystin is considered a potent carcinogen, mutagen and teratogen toxin.
A number of closely related compounds such as o-methyl Sterigmatocystin are known and some may occur naturally.
Effects of chronic exposure that have been reported include induction of hepatomas in rats, pulmonary tumours in mice, renal lesions and alterations in the liver and kidneys of African monkeys.Rats fed with 5-10 mg/kg of sterigmatocystin for two years showed a 90% incidence of liver tumours.
The acute toxicity, carcinogenicity and metabolism of Sterigmatocystin have been compared to those of aflatoxin and several other hepatotoxic mycotoxins.
Contamination by Sterigmatocystin usually occurs in wheat, maize, animal feed, hard cheese, pecan nuts and green coffee beans but also in cereals, grain products, fruits and marmalade, dried meat products and grapefruit juice.
Relatively high levels of sterigmatocystin have been formed in bread, cured ham and salami after inoculation with A. versicolor.No country has legislation for sterigmatocystin; however, it is important to emphasize that the natural occurrence of this mycotoxin appears to be infrequent, though only a limited number of surveys have been carried out (Noda et al., 1981;Stich & Laishes, 2006;Veršilovskis & De Saeger, 2010).
The IARC has classified Fumonisins as possible human carcinogens (Class 2B).Consumption of fumonisin has been associated with elevated human esophageal cancer incidence in various parts of Africa, China, Central America, and among the black population in Charleston, South Carolina, USA (Hussein & Brasel, 2001;Murphy et al., 2006).
FB1 is responsible for leukoencephalomalacia (necrotic lesions in the brain) in horses and pulmonary edema in swine.Hepatotoxicity and nephrotoxicity effects have also been reported in connection with chronic dietary exposure to fumonisin.Fumonisins are also a real risk factor in neural tube and related teratogenic defects because they reduce folate uptake (Zain, 2011).Fumonisins are known to disrupt sphingolipid synthesis and concentrations; thus, the altered plasma sphingosine/sphinganine ratios is an important biomarker of fumonisin dietary exposure (Murphy et al., 2006).
Many biochemical pathways have been postulated to explain the induction of illnesses by fumonisins.Several hypotheses are proposed and all are related to disruption of lipid metabolism as the initial step.
Some researchers have proposed that the first mechanism involves disruption of sphingolipid metabolism through inhibition of ceramide synthase.Glycerophospholipid metabolism is also affected (Voss et al., 2002).
A second theory proposes a biochemical mechanism that involves the fatty acid disruption, Glycerophospholipid metabolism, the relative induction of oxidative stress but also an incorrect modulation of gene expression.
Fumonisin has been unequivocally shown to be genotoxic, in fact DNA adducts of fumonisin B1 have been found.
A provisional maximum of tolerable daily intake (PMTDI) for FB1, FB2 and FB3, individually or in combination, is fixed at 2 µg/kg of body weight per day on the basis of the NOEL of 0.2 mg/kg of body weight per day and a safety factor of 100 (Creppy, 2002).

Zearalenone
Zearalenone (Fig. 9) is a mycotoxin produced by F. graminearum and other Fusarium molds as F. culmorum, F. cerealis, F. equiseti, and F. semitectum, using corn, wheat, barley, oats and sorghum as substrates.Fusarium infects cereals in the field.Toxin production occurs before harvesting, but also post harvest if the crop is not handled and dried properly (see section 6).
Fig. 9.Chemical structure of ZEA Among the human population, children are the most affected due to consumption of ZEAcontaminated foods (mainly cereals and cereal-based food products) (Massart & Saggese, 2010).This toxin is worldwide distributed and can contaminate most of the cereals like barley, maize, oats, sorghum, millet, rice, soybeans but also wheat and bread.ZEA has been implicated in several incidents of early puberty, as it is suspected to be the causative agent in an epidemic of early puberty changes in young children in Puerto Rico.
Altogether ZEA may have a species-dependent carcinogenic effect possibly secondary to the hormonal effect (Massart & Saggese, 2010); however, no data about formation of DNAadducts in humans are actually available.
ZEA and some of its metabolites have been shown to competitively bind to oestrogen receptors ( -zearalenol and -zearalenol); all of them have been included by IARC in Group 3, as not classifiable as carcinogens to humans.
No international homogeneous maximum limit exists in foodstuff for ZEA.Eight countries of the World have specific regulations for ZEA ranging from 30 to 1000 μg/kg.
The JECFA has established a provisional maximum tolerable daily intake for ZEA to be 0.5 μg/kg of body weight (JECFA, 2000).
The Canadian daily intake of ZEA from maize and maize-based cereals has been estimated to be 0.005 -0.087 μg/kg b.w. for 12 -19 year-old males, the highest consumption group.An additional intake from popcorn was estimated to be 0.001 -0.023 μg/kg b.w.

Combined toxic effects of mycotoxins
It has been known for many years that several products derived from plants contaminated by fungi during plant growth or during harvest and storage of the food item, can contain more types of mycotoxins; as a consequence, food intake results in a simultaneous exposure to a mix of mycotoxins; for example, often citrinin and ochratoxin A are found together (see Table 3).
There are several combinations of mycotoxins that frequently occur as verified by specific monitoring programs.These combinations are summarized in When mycotoxins are of similar structure and of the same species or of the same family, it is likely to expect similar mechanism of action, therefore mycotoxins are likely to exert additive effects.However, there are relatively poor information on the interaction between mycotoxins that occur at the same time and the consequences for animal and human health.
The available data in literature show that adequate studies to establish antagonistic, additive or synergistic effects after combined exposure to mycotoxins are rare and some of them are difficult to interpret.
The few studies conducted on the mycotoxins co-presence have shown that combined exposure to several mycotoxins generally results in an additive toxic effect with a few exceptions.The synergic capacity is relatively small for NIV, DON, T-2, ZEA and FB1.
The interaction between NIV and T-2 has been seen as synergistic because the effect of T-2 is potentiated in the presence of high levels of NIV (Berthiller et al., 2009;Bouslimi et al., 2008;Speijers & Speijers, 2004;Tammer et al., 2007).
It would be proper for future research to try to understand how mycotoxins can interact and thus interfere between them.

Ghost mycotoxins
Mycotoxins may also occur in conjugated forms such as:


soluble or masked mycotoxins  mycotoxins incorporated into/associated with/attached or bound to macromolecules.
Conjugated mycotoxins can be produced after metabolization by living plants, fungi and mammals, after food processing or because of some cooking methods.
It has been shown that wheat enzymatically produces deoxynivalenol 3-glucoside (D3G) from DON to defend itself from the very same toxin attack.
During storage, on the contrary, the plant product generally has a low metabolic activity and its enzymatic protections may not be as active.
Mycotoxins can be altered by subsequent food processing and most frequently through conjugation.The reliable analytical methods, measurement standards and occurrence and toxicity for this forms of mycotoxins are still lacking.
So, the risk assessment from exposure of consumers to mycotoxins should also take into account the presence of those forms (Berthiller et al., 2009;Bouslimi et al., 2008;Tammer et al., 2007).

Fungal conjugates
Some mycotoxin conjugates can be excreted directly by fungi, although examples are rare.This is the case of the well known 3-acetyl deoxynivalenol (3ADON) and 15-acetyl deoxynivalenol (15ADON), that can be found in cereals contaminated by Fusarium.Both substances are biosynthetic precursors of DON.

Plant conjugates
Plants protect themselves from xenobiotic compounds like mycotoxins by converting them into more polar metabolites.
It remains unclear, however, whether glycosylated mycotoxins are less toxic than the storage forms or they are part of the mechanism of the plant self-protection.
In wheat and maize cell suspension cultures OTA is transformed into ochratoxin and methylester-ochratoxin A (two isomers of hydroxyochratoxin A) as well as into their glucosides and methyl esters.
Fumonisin conjugates were long believed to occur only after food processing but recently it has been shown that bound fumonisins could also be found in unprocessed maize.
The exact chemical nature of these naturally occurring hidden forms is still unknown.In particular, it has to be understood whether conjugates are formed by the plant from non covalent interactions, e.g. with starch or proteins.

Food-processing conjugates
Food processing, especially heating and fermentation, can potentially alter some mycotoxins.D3G in fact was detected in malt and beer made from barley naturally contaminated with Fusarium, but also DON conjugates with higher masses as diglucosides and triglucosides have been detected in beer.Generally, very little is known regarding bound mycotoxins.
Depending on the type of linkage to proteins, starch, pectins, hemicellulose, cellulose and lignin, it is possible that at least some of the bound mycotoxins could become bioavailable again in the digestive tract of humans and animals.
Conjugation does not occur only during food processing; an excessive heat can also alter mycotoxins structure considerably; in fact, although mycotoxins are very stable, thermal degradation products of NIV and DON have been found in food and feed.
Fumonisins conjugates with sugars, amino acids and proteins are known to occur in food and feed.Heating FB1 with reducing sugars can yield N-(carboxymethyl) FB1, even in corn products.
Protected lysine and cysteine methyl esters react with FB1 demonstrating that free groups as thiol or amino groups of proteins are likely to react with the mycotoxins.Furthermore, it has been proven that thermal food processing influences the chemical structure and toxicity of fumonisins (Berthiller et al., 2009;Bouslimi et al., 2008;Speijers & Speijers, 2004;Tammer et al., 2007).

Mammalian conjugates
Conjugates that arise from mammalian metabolization unlikely have a role in food or feedstuffs and are therefore not regarded as masked mycotoxins.
Mycotoxins are conjugated by humans and animals during metabolization in the liver and are excreted in urine.Serum albumin adducts of AFB1 can be formed by Patulin that has been shown to react with cellular nucleophiles such as proteins or glutathione.This is the most probable pathway of detoxification in man and animals after dietary exposure to patulin-contaminated apples.
The ability to form glutathione and cysteine conjugates has also been shown for ochratoxin A. The most common mycotoxin conjugation products in mammals are glucuronides, as found for the Fusarium mycotoxins DON and ZEA.Besides the unchanged mycotoxins, both deoxynivalenol glucuronides and zearalenone glucuronide were detected in the urine of exposed animals.
Some DON and ZEA sulfates are formed and excreted by animals too.These conjugates might be used as biomarkers; by doing so, also inhalation of mycotoxins (e.g. by grain workers or from indoor moulds) and the consumption of all bioavailable forms of mycotoxins (including masked mycotoxins) might be monitored (Berthiller et al., 2009;Bouslimi et al., 2008;Speijers & Speijers, 2004;Tammer et al., 2007).

Mycotoxins control strategies, a possible form of prevention
Good agricultural practices (GAPs), good manufacturing practices (GMPs), HACCP (Hazard Analytical Critical Control Point), biological control measures and transgenic approaches, are actually the only realistic and possible form of primary prevention for mycotoxins flowering.
A control program for mycotoxins from the field to the table should include the HACCP approach, thus requiring an understanding of the interactions of the toxigenic fungi with crop plants, of the production and harvest methods for crops, of the production of livestock using grains and processed feeds, a thorough knowledge including diagnostic capabilities for mycotoxicoses, the development of new practices of foods processing for human consumption including storage and delivery (Jard et al., 2011).
A good protocol for mycotoxins checking is necessary to manage all control points and finally for being able to ensure to the consumer a food supply free from mycotoxins (Binder, 2007 ;Richard, 2007;Abrunhosa et al., 2010).
The results of HACCP show that the products obtained have an elevated hygienic quality, thus lowering the risk of contamination.The dried pasta, for example, is one of the foods most commonly consumed by Italians and Italy is leading the world ranking for the consumption of pasta.Also, pasta is conquering more and more important positions in the dietary habits of various peoples.The study of Ferrante and colleagues (2009) was to assess the presence of ZEA and OTA with the aim of identifying the consumer's risk.
The results of this study have showed OTA and Zea concentrations below the limit of methods in all types of dried pasta tested, also have showed that the HACCP system adopted by Italian food industries are adequate for preserve the food quality.This study m o r e o v e r h a v e s h o w e d i n p a r t i c u l a r t h a t the products for celiac consumers and the products made with whole wheat flour have an elevated hygienic quality.
The efficient storage systems can be also a good practice for reduction of contamination by mycotoxins.
One of the conservation techniques for food is the lyophilization.Ferrante and colleagues in 2006 carried out the study for verify presence of : tri-5 gene, ZEA, NIV and DON, in the primary products used for the preparation of lyophilized foodstuffs and in their final products (prontocrepes and prontocone).
The study have showed that the Tri-5 gene are always present in prontocrepes and always absent in prontocone products.With the air treatment a reduction of DON and NIV in both products has been obtained.The nitrogen treatment has had a single influence on the DON and in both final products, in which has had a reduction to 50 %.While, the NIV with the same treatment has reached the lowest percentage of reduction in both final products.The treatments affect relatively on the contamination of processed-foods that, therefore, in this case was due on the first quality of the primary products.
Populations residing in developed Countries are usually considered to be less exposed to mycotoxins than those in developing Countries; this might be attributed to various factors:  execution and practice of modern food handling/preservation technology  successful governmental regulation and commercial control over food quality and safety.
However, even monitoring and exercising of good agricultural and manufacturing practices (GAP and GMP) along with an effective HACCP approach might not completely avoid or eliminate mycotoxins in the food chain (Bhat, 2010;Jard et al., 2011;Zain, 2011).

Biological control
Various biocontrol strategies are possible for reducing the levels of mycotoxins in the crops, such as development of atoxigenic bio-control fungi that can out-compete their closely related, toxigenic strains in field environments.
It has been reported the existence of non-toxigenic strains of A. flavus and A. parasiticus that can reduce the post-harvest aflatoxin contamination by 95.9%.
The competitive use of biological agents such as F. verticillioides strains was observed to suppress the growth of fumonisin-producing fungi.
Control of fumonisins producing fungi by endophytic bacteria has also been reported and competitive exclusion was thought to be the mechanism involved.
It has also been reported that Pichia anomala, Pichia kluyveri and Hanseniaspora uvarum can inhibit in vitro OTA.
Furthermore, fungal strains of Trichoderma have been demonstrated to control pathogenic molds through mechanisms such as competition for nutrients and space, fungistasis, rhizosphere modification, mycoparasitism, biofertilization and the stimulation of plantdefense mechanisms (Bhat, 2010;Jard et al., 2011;Zain, 2011).

Chemical control
Appropriate use of pesticides during the production period could help in minimizing fungal infections or insect infestation of crops and consequently mycotoxins contamination; therefore, Fumonisins contamination could be reduced by application of fungicides that have been used for controlling Fusarium, such as prochloraz, propiconazole, epoxyconazole, tebuconazole, cyproconazole and azoxystrobin.
On the other hand, fungicides such as itraconazole and amphotericin B have been shown to effectively control the aflatoxin-producing Aspergillus species.However, use of fungicides is been discouraged because of economic, environment and severe food safety issues (Bhat, 2010;Jard et al., 2011;Zain, 2011).

Decontamination
Decontamination of food and feed from mycotoxins could be achieved through chemoprotection or enterosorption.
Chemoprotection from aflatoxins has been demonstrated with the use of a number of chemical compounds like oltipraz and chlorophylin or through dietary interventions based on broccoli sprouts and green tea that increase animal's detoxification processes or prevent the production of epoxide, that is known to cause chromosomal anomalies.
However, this intervention might not be sustainable in the long-term because it is expensive and shows some side effects.
Entersorption is based on the discovery of certain clay minerals, such as Novasil, that can selectively adsorb mycotoxins enough to prevent their absorption from the gastrointestinal tract .
There are different adsorption agents but their efficacy in preventing mycotoxicosis varies.Calcium montorillonites have proven to be the most highly selective and effective of enterosorbents.However, with enterosorption, there is a risk that non-specific adsorption agents may prevent uptake of micronutrients from the food (Bhat, 2010;Jard et al., 2011;Zain, 2011).

Breeding for resistance
Breeding for resistance is the most promising and encouraged long-term strategy for control of mycotoxins contamination in Africa.Sources of resistance to A. flavus and Fusarium spp.have been identified, particularly F. verticillioides.Zain (2011) states that "Prototypes of genetically engineered crops have been developed that a. contain genes for resistance to the phytotoxic effects of certain trichothecenes, thus helping reducing fungal virulence or b. contain genes encoding fungal growth inhibitors for reducing fungal infection in the USA".
To devise effective strategies to control fungal infections and minimize mycotoxins production in host plants, a good knowledge of genetic variability and plants population structure is necessary (Kazan et. al., 2011;Jard et al., 2011;Zain, 2011).

Regulation of mycotoxins in foods and feeds
A series of studies on mycotoxins in food and feed have been carried out around the world in order to improve policy making.
Regulations relating to mycotoxins have been established in many Countries to protect consumers from the harmful effects of these compounds.In 2003 about 100 Countries (covering approximately 85% of the world's inhabitants) had already specific regulations or detailed guidelines on mycotoxins in food.Regulations concerned AFB1, AFB2, AFG1, AFG2 and AFM1, trichothecenes (Vomitoxin, diacetoxyscirpenol, T-2 toxin and HT-2 toxin), FB1, FB2, and FB3, agaric acid, ergot alkaloids, OTA, patulin, phomopsins and ZEA, leaving out sterigmatocystin.
Harmonized EU limits now exist for 40 mycotoxin-food combinations.The direct or indirect influence of European organizations and programs on the EU mycotoxins regulatory developments was significant.
The current maximum limits are more and more based on scientific evidence from authoritative agencies such as FAO/WHO, Joint Expert Committee on Food Additives of the United Nations (JECFA) and the European Food Safety Authority (EFSA) (Van Egmond & Jonker, 2004).
The FDA has action levels for aflatoxins but the European Community levels are more restrictive (Creppy, 2002;Mally & Dekant, 2009).
Efforts have continued internationally to establish better guidelines to control mycotoxins.FAO, for example, has worked with developing Countries (African and East-Asian Countries) to mitigate mycotoxins contamination in foods and feeds.
Many Countries have regulatory or guideline limits for OTA in foods but in the majority of cases OTA content limits have been established only for cereals and cereal products (see Tab. 5).
There are still some discussions in those organizations regarding the limit that should be established for OTA in some cereal-derived foods, in fact in some Countries there is no limit or it is not harmonized with the international level (see Tab. Table 4. Worlwide limits for AFB1 and sum of AFB1, B2, G1, G2 in food.
Many Countries, even if industrialized, such as USA and Canada, still today lack of legal limit for AFB1, showing how the problem is unfortunately underestimated.
Furthermore, looking at

Table 1 .
Some mycotoxins and their biological effects on human health.

Table 2 .
List of mycotoxins and relative pathologies.

Table 3 .
Combinations of mycotoxins in food.

maize products, peanut and peanut products, peanut oil, irradiated peanut 10 Rice, irradiated rice, edible vegetable oil 5 Soya bean sauce, grain paste, vinegar, other grains, beans, fermented foods, fermented bean products, starch products, fermented wine, red rice, butter cake, pastry biscuit and bread
Table5, it is also evident that still today in many Countries of the world there are no limits for OTA, ZEA and Fumonisins, and that worldwide regulations for sterigmatocystin are completely lacking.