**2.1. Common mycotoxins in Africa**

**1. Introduction**

4 Mycotoxins - Impact and Management Strategies

regulatory mechanisms [3, 4].

contamination in Africa.

Globally, the consumption of contaminated foods accentuates a clear food security threat, and the central elements leading to contamination are microorganisms, specifically, fungi, which produce low-molecular weight toxic secondary metabolites known as mycotoxins. About 25% of the global food and feed output is contaminated by mycotoxins, which negatively affects human and animal health, productivity, livelihood, household security, income and causes significant economic losses [1]. Very often, contamination of agricultural commodities by mycotoxins results from a cumulative process, which begins from pre-harvest through post-harvest stage and continues throughout the entire food production chain [2]. Some factors that drive mycotoxin contamination along the African food and feed chain are the mid and hot tropical climates that are favourable growth conditions for fungi, food shortages, ignorance of the cause and implications of mycotoxins, food dumping and adulteration of foods with mouldy agricultural products as well as inadequate

A recent investigation on the mycotoxin issue across the entire continent of Africa led by Professor Sheila Okoth of the University of Nairobi (Kenya) and commissioned by the Technical Centre for Agricultural and Rural Cooperation (CTA) in conjunction with Partnership for Aflatoxin Control in Africa (PACA), confirmed and re-affirmed the seriousness of the mycotoxin issue [5, 6]. Economic losses arising from mycotoxicosis in Africa are alarming; losses incurred by developed nations are usually trade-related, whereas Africa tends to incur both economic losses and additional costs related to health challenges. This immense socio-economic impact of mycotoxins threatens the UN's sustainable development goal of improving nutrition, achieving food security and attaining a healthy agro-economic growth [6]. Often, socio-economic impact of mycotoxin contamination in Africa can be measured through reduced food availability, specifically amongst the rural poor, regulatory rejections of goods mainly at ports of exit, reduced market value of contaminated produce in domestic markets, decreased marketability of crops, forced alternative uses, increased livestock and human diseases, as well as mortality. Moreover, this impact should not exclude the high cost of research and regulatory activities aimed at reducing health risks because of the existence of causal relationships between mycotoxins and their impact on health. It is also overwhelming that in Africa, an annual cost of over USD 750 million is been accrued to aflatoxin (AF) contamination of crops, while the European Union (EU) regulation of AFs reportedly costs food exporters an estimated USD 670 million yearly [7]. Misdiagnosis, poor infrastructures, undependable and inconsistent data amongst other factors make it difficult to account for the additional and indirect costs associated with mycotoxin exposure in Africa. If the scale of economic and health impact of mycotoxin contamination is well understood, it will hasten policy makers towards imposing regulations and supporting affected populations. This chapter discusses on some pertinent socio-economic impacts of mycotoxin From an African context, the major mycotoxins of significance in terms of health and the economy are the AFs, fumonisins (FBs), ochratoxins (OTs), trichothecenes (THs) and the zearalenones (ZEAs). This is equally relative to their widespread occurrence in major food and feed commodities, aggravated by favourable climatic conditions in the continent. Of all the several occurring mycotoxins, the AFs are considered the most important. This is particularly associated with its prevalence in commodities and potency of aflatoxin B<sup>1</sup> (AFB<sup>1</sup> ), an AF form known to be the most noxious naturally occurring carcinogen. They have thus received substantial attention as compared to other mycotoxins as they frequently contaminate food and feed commodities in Africa [8]. Though there are about 20 different identified forms of these AFs [9], those of significant and economic importance are AFB<sup>1</sup> , aflatoxin B<sup>2</sup> (AFB<sup>2</sup> ), aflatoxin G<sup>1</sup> (AFG<sup>1</sup> ) and aflatoxin G<sup>2</sup> (AFG<sup>2</sup> ). Equally important are also aflatoxins M<sup>1</sup> (AFM<sup>1</sup> ) and M<sup>2</sup> (AFM<sup>2</sup> ), which are hydroxylated metabolites of AFB<sup>1</sup> and AFB<sup>2</sup> , respectively [10]. FBs, particularly fumonisin B<sup>1</sup> (FB<sup>1</sup> ), have been classified as a group 2B carcinogen by the International Agency for Research on Cancer (IARC) [11], and is highly prevalent in African staples such as maize, millet and sorghum [12]. The OTs are isocoumarin derivatives, occurring as ochratoxin A (OTA), B (OTB), C (OTC), D (OTD) and their methyl and ethyl esters [13]. Similar to FB<sup>1</sup> , OTA is a prevalent toxin, classified as a Group 2B potential carcinogen to human [11]. The THs, which are tetracyclic sesquiterpenes with an epoxy-ring [12, 14], are divided into type A consisting of T-2 and HT-2 toxins and type B with deoxynivalenol (DON) and nivalenol (NIV), the most important representatives [12]. Zearalenone (ZEA) and its hydroxylated derivatives α- and β- zearalenone (α-ZEA and β-ZEA) are lactone derivatives commonly found in food commodities [15]. It has been reported that ZEA usually co-occurs with one or more of the THs, because of the ability of its producing fungi to synthesize more than one mycotoxin [16]. The occurrence of modified and emerging forms of these mycotoxins including 3-acetyldeoxynivalenol (3-ADON), 15-acetyldeoxynivalenol (15-ADON), beauvericin (BEA), the enniatins (ENNs) and moniliformin (MON) have also been reported in African commodities [12]. The prevalence of these mycotoxins in African food crops have been reviewed extensively in literature [17–20], and can be strongly associated with a number of factors which are discussed in the next section.
