Underreported Human Exposure to Mycotoxins: The Case of South Africa

Abstract

South Africa (SA) is a leading exporter of maize in Africa. The commercial maize farming sector contributes to about 85% of the overall maize produced. More than 33% of South Africa’s population live in rural settlements, and their livelihoods depend entirely on subsistence farming. The subsistence farming system promotes fungal growth and mycotoxin production. This review aims to investigate the exposure levels of the rural population of South Africa to dietary mycotoxins contrary to several reports issued concerning the safety of South African maize. A systematic search was conducted using Google Scholar. Maize is a staple food in South Africa and consumption rates in rural and urban communities are different, for instance, intake may be 1–2 kg/person/day and 400 g/person/day, respectively. Commercial and subsistence maize farming techniques are different. There exist differences influencing the composition of mycotoxins in food commodities from both sectors. Depending on the levels of contamination, dietary exposure of South Africans to mycotoxins is evident in the high levels of fumonisins (FBs) that have been detected in SA home-grown maize. Other potential sources of exposure to mycotoxins, such as carryover effects from animal products and processed foods, were reviewed. The combined effects between FBs and aflatoxins (AFs) have been reported in humans/animals and should not be ignored, as sporadic breakouts of aflatoxicosis have been reported in South Africa. These reports are not a true representation of the entire country as reports from the subsistence-farming rural communities show high incidence of maize contaminated with both AFs and FBs. While commercial farmers and exporters have all the resources needed to perform laboratory analyses of maize products, the greater challenge in combatting mycotoxin exposure is encountered in rural communities with predominantly subsistence farming systems, where conventional food surveillance is lacking.

Advancing Global Health Surveillance of Mycotoxin Exposures using Minimally Invasive Sampling Techniques: A State-of-the-Science Review

“…3,51 Exposure to fumonisins may be higher in regions where maize is a staple crop, such as Mexico, Central America, 62 and South Africa. 3,8 Fumonisin B 1 (FB 1 ) is likely the most prevalent and toxic to humans, with animal models demonstrating the kidneys and liver to be target organs of effects, including carcinogenicity. 3,51 A few epidemiologic studies have also found exposure to FB 1 to be associated with esophageal cancer risk.…”

“…3,8 In addition, climate change is expected to increase human exposure to mycotoxins in many geographic regions, 7 including Europe and other regions that may experience more extreme weather events, such as heat waves and droughts. 16 More research is needed to identify the effects of climate change on exposures to mycotoxins in geographic areas where exposures are endemic, 8,17,18 including regions in Africa and Asia where concerning elevations in levels of aflatoxin exposure biomarkers have been reported. 3 While aflatoxins are recognized to be highly hepatocarcinogenic in humans, especially in those with chronic hepatitis B virus (HBV) infection, 1,3 other possible health effects from aflatoxins and other mycotoxins have been less well studied.…”

Discussion on emergency management of food safety from the perspective of foodborne diseases caused by mycotoxins

“…Its primary target organ is the liver, which typically produces acute cirrhosis and necrosis with edema and bleeding, but high concentrations of aflatoxin have also been found in the kidneys, lungs, heart, and brain (Marrez & Ayesh, 2022). In addition, some diseases such as malaria and AIDS may be due to the immunomodulatory effects of aflatoxin, because of immune regulation, the repeated infection of children leads to growth disorders or changes in intestinal integrity, making the host more vulnerable to foreign intestinal microorganisms (Nji et al, 2022;Matumba et al, 2016).It has also been suggested that aflatoxins may cause nutritional disorders by interfering with the absorption, protein synthesis, and metabolic enzyme activities of micronutrients (such as zinc, iron, and vitamins) (Benkerroum, 2020;Degen, 2017;Degen et al, 2017). It may, together with other mycotoxin, affect the development of edema in malnourished people and is also associated with Kwashiorkor disease (Misihairabgwi et al, 2019; International Agency for Research on Cancer, 2012).…”

“…One toxic substance we may not be able to avoid, even if we choose our foods carefully, is mycotoxin, which don't appear on ingredient lists but can be found in foods like grains, milk, fruits, and vegetables. Mycotoxin comes from the Greek word mycosis, which means fungus, and the Latin word Toxium, which means poison, is a low molecular weight metabolic secretion produced by fungi (Nji et al, 2022;Janik et al, 2020).…”

Natural Antioxidant By-Product Mixture Counteracts the Effects of Aflatoxin B1 and Ochratoxin A Exposure of Piglets after Weaning: A Proteomic Survey on Liver Microsomal Fraction

“…Mycotoxins present in feed can have significant impacts on human health [18,19]. Consumption of contaminated animal products, such as meat, by human beings facilitates their exposure to mycotoxins and their secondary metabolites, causing a range of health problems, depending on the type and level of mycotoxin involved [1,[20][21][22][23].…”