**1. Introduction**

Maize (Bhutta) or *Zea mays L.* (corn) is one of the supreme vital cereals in the globe which belongs to Poaceae family and it has been ranked as a third position in the last few decades after wheat and rice [1]. A fair number of food and industrial commodities such as maize flour, animal feed, cooking ingredient, corn syrup, grain alcohol and whiskey are processed from maize [2]. Maize has been known as a significant emerging crop in Bangladesh as well as maize production is familiarized day by day due to its diverse use for feed, food, fish meal and edible oil processing [3]. Bangladesh has achieved 11th position when it comes to average yield which was 8 tons per ha in the year of 2019–2020 [4] and maize production were 40 lakh ton [5]. Anyway, maize plant is quite vulnerable for various fungi as they get favorable environment to infect via fluctuation of humidity and temperature conditions in both of storage and growing phase [6]. In harvesting period less care in drying and storage processing leads to a surge in infection and production of toxin [7]. Dominant pathogens such as *Aspergillus* spp. and *Fusarium* spp. in maize have the capability to destroy seeds, germination procedure in seeds as well as generating vital mycotoxins [8]. Mycotoxins are light molecular weight developed from saprophytic fungi, most significantly *Aspergillus*, *Fusarium* and *Penicillium* as secondary metabolites [9]. Mycotoxins were detected as one of the deadly toxins after the outbreak of ruinous 'Turkey X' in 1960s at England which leads to the death of Turkey poults (100,000) [10]. Mycotoxin comtamination can develop in any stage of food chain especially in the field, during transportation, processing, harvesting and storage [11].

Aflatoxins are mainly hepatocarcinogenic toxins comprising of major three metabolities named Aflatoxin G, M and B under derivative compounds named difurocoumarin [12–14]. The paramount aflatoxin producing fungi globally is *A. flavus* divided into two distinct morphotypes named L and S [15]*,* among them S morphotype was potentially ruinous as it was capable of producing gigantic level of toxins [16, 17]. A significant research has been made by toxigenic communities that innumerable lineages of fungi are belong to S morphotype among them a few were able to engender enormous concentration of both B and G aflatoxins [18]. Several *Aspergillus* spp. is accounted for several toxins such as aflatoxin B is mainly produced from *A. flavus, A. parasiticus* whereas aflatoxins G is developed from *A. nomius.* Moreover, G and B are highly produced inspices, fruits, corn, nuts, peanuts and copra [19, 20]. *A. flavus* is ubiquitous and mostly detected in corn producing toxins, while in peanut *A. parasiticus* is the main culprit of developing toxins [21]. The toxicity level of aflatoxins of different types chronologically are B1 > G1 > B2 > G2 [22]. Basically, aflatoxins levels were found ascendency in the food markets of Bangladesh [23]. Temperature, pH, relative humidity, and the presence of other fungi are predominant factor for developing aflatoxins and substrates [24]. Aflatoxins level surges due to drought, insect damage, and heat during fungal growth [25]. The *AflR* gene regulates the activation of other structural genes including *omt-A*, *ver-1*, and *nor-1*, which are involved in the aflatoxin biosynthesis process [26]. In hot and humid settings, aflatoxins contamination are also thrived [27]. Seasonal variation has been observed in Bangladesh including high humidity, high temperature and seasonal variation in rainfall (http://en.wikipedia.org/wiki/Geography of Bangladesh). Extreme humid conditions significantly triggered the growth of aflatoxins [28], as a result, it is obvious that aflatoxins was reported in maize, cereals and groundnuts and other feed in Bangladesh and exceeding European Union (EU) permissible limit for aflatoxins [29].

*Fusarium* spp. are among the utmost crucial fungal pathogens of maize, where they cause severe abatement of yield and accumulation of a vast range of harmful mycotoxins in the grain [30]. *Fusarium* spp. also have the ability to infect crucial crops such as potato, wheat, barley, asparagus, mango, oats, rice and other feed and food crops [31]. High moisture conditions triggered the production of *Fusarium* toxins near or at harvesting stage in cereals [32, 33]. Fumonisins toxins can be developed from a numerous species such as *F. moniliforme*, *F. verticillioides*, *F. nygamai*, *F. proliferatum* [34] as well as *A. niger* [35]. Fumonisins comprise of four types of toxins which are A, B, C, and P, among them fumonisin B1 is the most exploited and ruinous one [34]. FB1, FB2, and FB3 were designated as utmost

*Aflatoxins and Fumonisins Contamination of Maize in Bangladesh: An Emerging Threat… DOI: http://dx.doi.org/10.5772/intechopen.101647*

destructive and highly abundant fumonisin toxins where FB1 is the most ruinous due to its availability of high concentration on host ranging from 70 % to 80 % of all fumonisins [36–38]. Several biotic (temperature, water stress) and abiotic (osmotic stress, pH, and fungicides) factors are resposnsible for *Fusarium* growth and Fumonisin production [39, 40]. At maturity stage damage occurs by insects, during flowering wet warm weather, rain before harvest, humidity, and media composition for both the *Fusarium* spp., all the activites are related to fumonisins production [41, 42]. *FUM1* gene can also expressed by ecological conditions reported by [43, 44]. As *Fusarium* is widespread and ubiquitous in all cereal growing regions of the globe and corresponding mycotoxins are produced which has been influenced by storage methods and crop production [45]. In the midst of milling, storage, processing, cooking of food and feed, *Fusarium* are highly stable due to its structure and humans and animals are exhibited to them to a certain degree [46–48]. In Bangladesh, animal feed samples were detected and found fumonisin contamination mainly maize based feed contamination [49].

An investigation came out that in South Asia has been ranking as the utmost prevalent continent in case of exposing aflatoxins contamination (82 %) in the globe as well as 41 % maize samples were detected higher amount of aflatoxins contamination than the permissible limit of lenient EU criteria [49]. The very first outbreak of mycotoxin (Sterigmatocystin) was found in Bangladesh in rice straw [50], later in maize and poultry birds [51]. Liver cancer and hepatitis B infection promotes carcinogenic potency in specific individuals by aflatoxins [52, 53]. In Japan, in the year of 1991–2009, violation cases were detected exceeded 1500 in foods which were imported at a level of 10–4918 mg/kg [54]. 62 % children with the age of 3 are at a complete risk of infecting with aflatoxins as aflatoxins biomarkers was detected in plasma of their blood [55]. According to WFP (World Food Program), permissible limit of aflatoxins is 10 ppb (10 μg/kg) and for fumonisins it is 1 ppm (1 mg/kg) [56]. Fumonisins toxin may causes esophageal carcinoma in humans [57], as well as contaminated with folate uptake in cellular level [58] and surging the intensity of neural tube defect [59]. 52 % positive rate of fumonisins was found with an overall level of 936 mg/kg in Asia [60]. *Fusarium* mycotoxin can cause leukoencephalomalacia, porcine pulmonary edema and rat hepatocarcinoma in human and livestock as well [55, 61, 62] detected that in Dhaka, Bangladesh 62 % of 3 year old children had aflatoxin biomarkers in their blood plasma revealing chronic aflatoxin exposure as reported earlier that significant amount aflatoxins were found from corn selling in the Bangladeshi market. Probably 1311 cases of liver cancer was detected every year in Bangladesh [63]. In can be deduced from abovementioned fact that determining aflatoxins and fumonisins and all other mycotoxins in food and feed are the prime need for the country like Bangladesh as these mycotoxin substantially subverts our plants yield concurrently human and animal lives as well. Thus, more research needs to be conducted to elicit the specific mycotoxin hampering specific food, feed and plants, besides to find out the plausible management for controlling these mycotoxins. This study highly exhibited the aflatoxins and fumonisins toxin level in Bangladesh from maize samples of different regions as it has been concerned as one of the burning issues for ensuring safety food.

### **2. Materials and methods**

### **2.1 Sample collection**

Composite stored maize grain samples were collected from 15 maize growing areas of Bangladesh such as Bogura, Kushtia, Meherpur, Chuadanga, Kishoreganj, Manikganj, Cumilla, Rajshahi, Dinajpur, Rangpur, Natore, Thakurgaon,

Panchagarh, Nilphamary and Jashore. Maize samples were collected from stores of traders in local markets of different districts. Ten markets were sampled in each district having at least five traders in each market. At least two quarter of kilogram unique samples were coalesced from each trader for laboratory analysis. Samples were collected after thoroughly mixing maize in the bag to increase chances of getting the fungi. The samples were stored at temperatures below 4° C to await analysis.
