Systematic review on Aflatoxin contamination in Ethiopia: current status and implications

Aflatoxin contamination, caused by molds like Aspergillus flavus and A. parasiticus, poses a significant threat to food safety and public health worldwide, with particularly severe impacts in countries like Ethiopia, where it affects both the economy and the sustenance of the population due to its potent carcinogenic properties^[1]. Also, Aflatoxins are potent carcinogens produced by molds like Aspergillus flavus and A. parasiticus, commonly infecting crops such as maize and peanuts^[2]. Contamination of staple foods like maize and peanuts has significant health and economic impacts, particularly in warm, humid regions where mold growth thrives^[3]. Africa bears a significant burden of Aflatoxin contamination due to its climate, agricultural practices, and inadequate food storage facilities^[4]. Crops such as maize, wheat, barley, and cassava can be harmful due to toxins like Aflatoxins, cyanogenic glycosides, and solanine, which pose serious health risks if not properly handled or processed, with Ethiopia being particularly vulnerable to Aflatoxin contamination in staple crops like maize and peanuts^[5]. In Ethiopia, Aflatoxin contamination mainly arises from poor post-harvest handling, inadequate storage, and limited awareness among farmers and food processors^[6]. Factors such as high temperatures, humidity, and improper drying and storage exacerbate the risk of Aflatoxin contamination in staple crops^[7]. Many African countries, including Ethiopia, struggle to combat Aflatoxin contamination due to ideal conditions for mold growth created by high temperatures and humidity, inadequate agricultural practices and storage methods, and challenges such as limited detection technology, insufficient regulatory frameworks, and heavy reliance on agriculture^[8]. Other affected nations in Africa include Kenya, Nigeria, Tanzania, and Uganda, among others^[9]. In Ethiopia, Aflatoxin contamination threatens food security and public health, impacting both rural and urban populations^[10]. Consuming Aflatoxin-contaminated foods can cause liver cancer, immune suppression, and stunted growth in children^[11]. Chronic exposure to Aflatoxins can lead to long-term health complications and increased healthcare costs^[12]. Aflatoxin contamination also harms the economy by reducing agricultural productivity, causing trade restrictions, and resulting in revenue losses from rejected exports^[13]. The economic burden extends beyond agriculture, affecting healthcare costs, livelihoods, and consumer confidence in domestic foods^[14]. Comprehensive mitigation strategies, including promoting proper drying, storage, and handling of crops, are essential to address Aflatoxin contamination in Ethiopia and other affected regions^[15]. Research should focus on breeding crops resistant to Aflatoxin-producing fungi to reduce contamination risk^[16]. Strengthening food safety regulations and enforcement mechanisms can ensure compliance with Aflatoxin limits in food products, safeguarding public health and facilitating trade^[17]. Raising awareness about Aflatoxin risks and prevention is crucial for encouraging best practices^[18]. Investing in storage infrastructure and Aflatoxin detection technologies can reduce contamination risks along the food supply chain^[19]. Hence, this review aimed to assess the current status of Aflatoxin contamination in Ethiopia, its sources, and mitigation strategies.

To facilitate a comprehensive and efficient literature search for the systematic review on Aflatoxin contamination in Ethiopia, several key index terms were employed. These included 'Aflatoxin', which encompassed related terms such as 'Mycotoxins' and specific types like 'Aflatoxin B1' and 'Aflatoxin M1', critical for identifying relevant studies on the contaminants themselves. The term 'Contamination' was also used to capture studies related to 'Mycotoxin contamination', 'Agricultural contamination', 'Food contamination', and 'Environmental contamination'. To narrow the focus to the regional context, 'Ethiopia' and related terms like 'Ethiopian agriculture' and 'Ethiopian food safety' were included. For exploring health impacts, 'Health Implications' terms were utilized, addressing the 'Health effects of Aflatoxins', 'Toxicity', 'Carcinogenicity', and 'Liver disease' associated with exposure. The term 'Prevalence and Occurrence' helped to identify studies on 'Aflatoxin levels', 'Occurrence of Aflatoxins', and 'Prevalence in crops'. Additionally, 'Mitigation and Management' strategies were explored, including 'Aflatoxin control', 'Mitigation strategies', 'Food safety measures', and 'Agricultural practices'. 'Regulation and Policy' terms like 'Food safety regulations', 'Policy interventions', and 'National guidelines' were also explored. To ensure a thorough and rigorous review process, methodological terms were also used such as 'Systematic review', 'Literature review', 'Data extraction', and 'Quality assessment'. Finally, 'Search Strategies' including 'Search methodology', 'Database search', and 'Keyword search' were focussed on, and 'Data Synthesis' methods such as 'Qualitative synthesis', 'Meta-analysis', and 'Data analysis' were employed to effectively summarize and interpret the findings.

Aflatoxins, difuranocoumarin derivatives produced by Aspergillus species such as A. flavus and A. parasiticus, include the highly toxic Aflatoxin B1(C17H12O6) and are a global concern, especially in hot, humid regions^[20]. Contamination levels vary by year and region due to factors like weather and storage, but efforts to mitigate Aflatoxin include improving agricultural practices, enhancing storage, and rigorous testing^[21]. Aflatoxin levels in Ethiopia vary due to practices, climate, and storage conditions, so for the latest data, consult Food and Agriculture Organization (FAO), World Health Organization (WHO), and local reports, while international organizations like FAO and WHO collaborate globally to raise awareness, develop regulations, and provide technical assistance to address Aflatoxin contamination and its effects on public health and food security^[22]. Aflatoxin contamination has been a persistent issue in Africa, particularly in regions with warm and humid climates where crops such as maize, peanuts, and tree nuts are commonly grown^[23]. Aflatoxin contamination, which leads to severe health issues and billions in economic losses, affects agriculture and public health, with Africa focusing on improving practices and storage^[24]. In Ethiopia, where Aflatoxin contamination is a major concern in maize and groundnuts, initiatives focus on raising awareness among farmers, traders, processors, and consumers about the risks and prevention measures^[5]. Efforts to address Aflatoxin contamination in Ethiopia includes better agricultural practices, improved storage, and increased awareness^[25]. Groundnuts and maize are among the most affected crops, with contamination levels exceeding regulatory limits in many instances^[26]. The FAO and WHO combat Aflatoxin contamination by enforcing food safety standards, promoting good agricultural practices, supporting research, and improving local testing capacities, with recommended measures including proper storage, regular testing, and education to protect public health and enhance food safety globally and in Ethiopia.

In Ethiopia, Aflatoxin contamination mainly originates from crops, storage practices, feed, and environmental factors, commonly affecting maize, peanuts, cottonseed, and tree nuts (Table 1). Poor storage conditions, inadequate drying, and improper handling practices contribute to the growth of Aspergillus fungi, which produce Aflatoxins^[27]. Improper storage in warm, humid conditions can lead to fungal growth and Aflatoxin production, with traditional methods, often inadequate for prevention^[28]. Inadequate processing methods, such as milling and shelling, can spread Aflatoxin contamination throughout food products^[29]. Additionally, processing facilities with poor hygiene standards may contribute to Aflatoxin contamination^[30]. Contaminated crops, such as maize and peanuts, used in livestock feed can lead to Aflatoxin buildup in animal products like milk, meat, and eggs^[31]. Ethiopia's warm and humid climate provides favorable conditions for the growth of Aspergillus fungi, the primary Aflatoxin producers^[5]. Climate change may worsen Aflatoxin contamination in crops, so improving agricultural practices, upgrading storage, enhancing processing methods, and raising awareness about the risks is essential.

Several African nations, including Ethiopia, Ghana, Kenya, Malawi, Mozambique, Nigeria, Senegal, Tanzania, Uganda, and Zambia have faced Aflatoxin contamination^[17]. These countries struggle with Aflatoxin contamination due to inadequate storage, poor agricultural practices, and limited resources, especially in Ethiopia, where maize and groundnuts are staple crops^[5]. Aflatoxin contamination affects multiple regions in Ethiopia, with heavy impacts in maize-producing areas of Eastern Ethiopia and maize and groundnut zones of Southern Ethiopia^[41]. Similarly, in Central Ethiopia (Amhara), maize-producing areas are also at risk of Aflatoxin contamination^[42]. Aflatoxin contamination in cereals, nuts, and seeds poses serious health risks to humans and animals if consumed in high levels^[43].

Aflatoxins, especially Aflatoxin B1, are potent carcinogens classified as Group 1 by the International Agency for Research on Cancer (IARC)^[44]. Prolonged exposure to Aflatoxins in contaminated food can cause various cancers, especially liver cancer^[45]. Aflatoxin exposure, primarily from contaminated food contributes significantly to global health issues by causing an estimated 25,000 to 155,000 liver cancer cases annually, with a notable impact in Ethiopia, and can also lead to acute toxicity with symptoms such as vomiting, abdominal pain, convulsions, and potentially death^[46]. Chronic Aflatoxin exposure can weaken the immune system, increase susceptibility to infections, and cause stunted growth and developmental delays in children^[47].

Economic impacts

Aflatoxin contamination causes food losses, scarcity, waste, and undermines food security and economic productivity^[10]. Aflatoxin-related issues can reduce export revenues and impose significant healthcare costs for diagnosis, treatment, and care for cancer and other complications^[48]. Aflatoxin contamination can devastate the livelihoods of farmers and food producers, especially in developing countries where agriculture is a major economic sector^[49]. Farmers dealing with Aflatoxin contamination faces severe health risks and economic losses as affected crops may be unmarketable or fetch lower prices, leading to reduced incomes and food insecurity, compounded by inadequate storage, ineffective control measures, and limited handling knowledge^[50]. Thus, addressing Aflatoxin contamination demands a comprehensive strategy including prevention, detection, regulation, and innovation to mitigate its public health and economic impacts.

Efforts to mitigate Aflatoxin contamination in Ethiopia include pre-harvest, harvest, and post-harvest interventions, such as promoting good agricultural practices like crop rotation, pest management, and irrigation^[15]. Post-harvest interventions focus on improving storage facilities, implementing proper drying techniques, and utilizing Aflatoxin-detoxifying agents^[51] (Table 2). Raising awareness about Aflatoxin risks and implementing testing and certification protocols is crucial for ensuring food safety and market access.

Implementing these strategies can significantly reduce Aflatoxin contamination in the food supply chain. Positive results include improved public health, enhanced trade opportunities due to compliance with safety standards, and increased crop yields from resistant varieties. Additionally, raising awareness and improving infrastructure can lead to widespread adoption of best practices, further minimizing contamination. However, negative aspects include the high initial costs of research, infrastructure development, and technology implementation, as well as potential resistance from stakeholders resistant to change. Effective implementation of these strategies could prevent up to 90% of Aflatoxin contamination, although actual results may vary based on region-specific factors and the extent of adoption.

Although some studies on Aflatoxin contamination in Ethiopia exist, comprehensive nationwide data is lacking. Extensive surveys covering various regions, crops, and storage conditions are needed. While current research focuses on staple crops like maize, peanuts, and cereals, more studies are required for other commonly consumed crops such as millet, sorghum, and spices. Understanding the economic, health, and social impacts, including food security and trade restrictions, is crucial. Additionally, limited research on environmental factors like climate variability and soil conditions exists. Further investigation is needed to assess the effectiveness of existing mitigation strategies and regulatory frameworks. Establishing a nationwide surveillance program and developing integrated crop management strategies are essential steps. Climate-resilient agricultural practices and public health interventions are also necessary. Capacity-building initiatives and multi-stakeholder collaborations can enhance Aflatoxin management. Advocating for policy reforms will strengthen regulatory enforcement and ensure compliance. Addressing these gaps will enhance Ethiopia's capacity to mitigate Aflatoxin contamination effectively, protecting public health and agricultural productivity.

Aflatoxin contamination is a pressing issue globally, with Africa and Ethiopia facing significant challenges. In Ethiopia, groundnuts, maize, and other staple crops are major sources of Aflatoxin. Several African countries, including Ethiopia, suffer from its effects, impacting public health and the economy. Aflatoxin exposure can lead to health problems like liver cancer and economic losses due to reduced crop yields and trade restrictions. Mitigation strategies include improved agricultural practices, post-harvest management, and regulatory measures. Aflatoxin contamination is a complex challenge in Ethiopia and Africa, affecting both health and the economy. Comprehensive efforts involving stakeholders at all levels are crucial for mitigation. Stringent regulations, awareness campaigns, and research are necessary to address this issue effectively. Collaboration among African nations and international organizations is vital for sustainable solutions.

The author confirms the sole responsibility for all aspects to this study.

Data sharing is not applicable to this article as no new data were analyzed in this study.

The author acknowledges the anonymous editors and potential reviewers for their valuable input for the script.