Underreported Human Exposure to Mycotoxins: The Case of South Africa

Incidence and mortality of acute aflatoxicosis: A systematic review

BACKGROUND

Aflatoxins are mycotoxins produced by Aspergillus fungi in crops intended for food and feed. Acute exposure to high levels of aflatoxin B1, one of the most toxic mycotoxins, can result in severe poisoning, defined as acute aflatoxicosis, which manifests as acute hepatic failure followed by death in severe cases. Currently global burden estimates of acute aflatoxicosis are lacking - in contrast to burden estimates of chronic exposure - making it difficult to implement and prioritize risk management strategies in the prevention and control of aflatoxin exposure.

AIM

This systematic review assessed global evidence on the incidence and mortality of acute aflatoxicosis from 1990 to 2023. While symptomology & disease duration was also examined, it served as a secondary outcome to provide additional clinical context.

SEARCH STRATEGY AND ELIGIBILITY

A structured search was conducted in PubMed, Web of Science, Embase, Scopus, INASP and grey literature. Studies were imported into Covidence for review.

STUDY SELECTION AND EXTRACTION

Two independent reviewers screened and extracted titles, abstracts, and full texts. Eligible studies included all human studies.

RESULTS

From 11,539 references, 9 studies were included. Heterogeneity existed in study design, region, age of the study population and aflatoxin analysis. Number of cases ranged from 1 to 317, with aflatoxin concentrations varying widely, i.e. between 10 and 51,100 µg/kg in food, 36 and 209,000 pg/mg albumin in serum, and 19 and 18,521 pg/g in tissue. Only one outbreak provided sufficient data to estimate an attack rate of 8 cases per 100,000. Mortality ranged from 16.2 to 76.5 %, affecting children under 15 and adults over 40 most severely. Common symptoms included vomiting (77-100 %), jaundice (88-100 %), and abdominal pain (8-87 %). The risk of bias was generally low.

CONCLUSION

This review shows that acute aflatoxicosis remains a significant public health burden, especially among vulnerable groups in African countries, although the variability in studies and lack of standardized reporting make burden estimation difficult, highlighting the need for better warning systems and standardized reporting, despite challenges with infrastructure and resources in affected areas.

Three-year multi-mycotoxin analysis of South African commercial maize from three provinces

Introduction

The Food and Agricultural Organization (FAO) reported that numerous diseases can be traced back to the consumption of unsafe food contaminated with mycotoxins. Mycotoxins are secondary metabolites produced by toxigenic filamentous fungi. Mycotoxins reported to be of socio-economic concerns include aflatoxins, fumonisins, zearalenone, ochratoxin A, and deoxynivalenol. These mycotoxins are frequent contaminants of maize especially in the face of climate change and global food insecurity. South Africa is a leading exporter of maize in Africa, hence, it is crucial to evaluate exposure risks with respect to mycotoxin contamination of maize for consumers' safety.

Materials and method

In total, 752 post-harvest maize samples collected from silos over a 3-year period were analysed using liquid chromatography with tandem mass spectrometry (LC-MS/MS) for the occurrence of mycotoxins.

Results and discussion

The overall mean values for all the quantified mycotoxins were within the South Africa regulatory limit as well as the individual samples, apart from DON and FB mycotoxins with 5% and 1% samples, respectively, above the limit. Citrinin was quantified in South African commercial maize for the first time. The presence of major mycotoxins in South African commercial maize even within safety limits is of public health concern, hence, continuous monitoring and evaluation is recommended.

Climatic effects on aflatoxin contamination of maize

Aflatoxins are frequent contaminants of maize especially in the face of climate change with deleterious health and socio-economic impacts. South Africa is ranked 9th maize exporter globally; hence, insights need to be gained in terms of the maize value chain in South Africa with respect to aflatoxin contamination to evaluate consumers' exposure. High-performance liquid chromatography (HPLC) technique was used in this study to quantify aflatoxins in South African commercial maize. One thousand and twenty-eight (1028) maize samples were collected across six distinct agro-climatic regions over five harvest seasons (2017 - 2021). A total of 205 samples (19.94 %) were found to be contaminated with aflatoxins, with mean total aflatoxin concentration of 64.17 ppb amongst the contaminated samples, which is above the SA regulatory limit of 20 ppb for animal consumption. The year 2018 recorded the highest mean total aflatoxin value while North-West agro-climatic region had the highest mean total aflatoxin value. Drastic reduction in average rainfall significantly influence aflatoxin contamination of South African maize.

Aflatoxin Contamination of Various Staple Foods from Angola and Mozambique

Aflatoxins constitute a significant risk in staple foods produced in African countries. This research aimed to analyze the total aflatoxin (AFT) contamination of various staple foods in Angola and Mozambique. A total of 233 samples of corn, peanuts, beans, rice, and cassava flour collected from farmers or local markets from the province of Cuanza Sul, Angola, and the provinces of Gaza and Inhambane, South Mozambique, were analyzed for the presence of AFT using the lateral flow strip method via AgraStrip® Pro WATEX® (Romer). The results showed that, from all matrices, the highest incidence and level of AFT were found in corn produced in Mozambique, with medians ranging from 6.5 to 66.5 µg/kg, with the samples showing values as high as 9200 µg/kg. Levels higher than the maximum admissible levels recommended by the Codex Alimentarius Commission for cereals and pulses (15 µg/kg) were observed in up to 90% of the corn samples, depending on the province. Corn produced in Angola showed lower amounts of AFT, with medians ranging from 1.2 to 7.7 µg/kg. Considering the maximum admissible levels for AFT recommended by the European Commission and the Codex Alimentarius Commission for cereals and pulses, the level of AFT contamination in staple food produced and consumed in the studied provinces is high and constitutes a public health risk for the population. Therefore, risk mitigation strategies are urgently needed.

The Role of AFB1, OTA, TCNs, and Patulin in Forensic Sciences: Applications in Autopsy, Criminal Investigations, and Public Health Prevention

Mycotoxins, specifically aflatoxin B1 (AFB1), ochratoxin A (OTA), trichothecenes (TCNs), and patulin, are a group of secondary metabolites that can contaminate food, leading to severe health implications for humans. Their detection and analysis within forensic toxicology are crucial, particularly as they can be implicated in cases of poisoning, foodborne illnesses, or lethal chronic exposure. However, little is known about the application that mycotoxins could have in forensic investigations and especially about the possibility of extracting and quantifying these molecules on tissues or post-mortem fluids collected at autopsy. We propose a review of the scientific literature on autopsy case studies in which the presence of mycotoxins on cadavers in cases of acute and chronic exposure has been investigated and identified. This review demonstrates how the analysis of mycotoxins on cadavers could be fundamental in the study of mushroom poisonings or even in the investigation of the chronic effects of mycotoxins on the human organism, by virtue of the known carcinogenic and mutagenic effects of many of them. This paper aims to explore the multifaceted role of mycotoxins within forensic sciences, focusing on their detection methods, implications in criminal contexts, and their potential as forensic evidence, thereby underscoring the critical importance they could assume in post-mortem toxicology, public health prevention, and forensic investigations.

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

Mycotoxins are a heterogeneous group of toxins produced by fungi that can grow in staple crops (e.g., maize, cereals), resulting in health risks due to widespread exposure from human consumption and inhalation. Dried blood spot (DBS), dried serum spot (DSS), and volumetric tip microsampling (VTS) assays were developed and validated for several important mycotoxins. This review summarizes studies that have developed these assays to monitor mycotoxin exposures in human biological samples and highlights future directions to facilitate minimally invasive sampling techniques as global public health tools. A systematic search of PubMed (MEDLINE), Embase (Elsevier), and CINAHL (EBSCO) was conducted. Key assay performance metrics were extracted to provide a critical review of the available methods. This search identified 11 published reports related to measuring mycotoxins (ochratoxins, aflatoxins, and fumonisins) using DBS/DSS and VTS assays. Multimycotoxin assays adapted for DBS/DSS and VTS have undergone sufficient laboratory validation for applications in large-scale population health and human biomonitoring studies. Future work should expand the number of mycotoxins that can be measured in multimycotoxin assays, continue to improve multimycotoxin assay sensitivities of several biomarkers with low detection rates, and validate multimycotoxin assays across diverse populations with varying exposure levels. Validated low-cost and ultrasensitive minimally invasive sampling methods should be deployed in human biomonitoring and public health surveillance studies to guide policy interventions to reduce inequities in global mycotoxin exposures.

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 are toxic compounds produced by certain strains of fungi that can contaminate raw feed materials. Once ingested, even in small doses, they cause multiple health issues for animals and, downstream, for people consuming meat. It was proposed that inclusion of antioxidant-rich plant-derived feed might diminish the harmful effects of mycotoxins, maintaining the farm animals' health and meat quality for human consumption. This work investigates the large scale proteomic effects on piglets' liver of aflatoxin B1 and ochratoxin A mycotoxins and the potential compensatory effects of grapeseed and sea buckthorn meal administration as dietary byproduct antioxidants against mycotoxins' damage. Forty cross-bred TOPIGS-40 hybrid piglets after weaning were assigned to three (n = 10) experimental groups (A, M, AM) and one control group (C) and fed with experimental diets for 30 days. After 4 weeks, liver samples were collected, and the microsomal fraction was isolated. Unbiased label-free, library-free, data-independent acquisition (DIA) mass spectrometry SWATH methods were able to relatively quantify 1878 proteins from piglets' liver microsomes, confirming previously reported effects on metabolism of xenobiotics by cytochrome P450, TCA cycle, glutathione synthesis and use, and oxidative phosphorylation. Pathways enrichment revealed that fatty acid metabolism, steroid biosynthesis, regulation of actin cytoskeleton, regulation of gene expression by spliceosomes, membrane trafficking, peroxisome, thermogenesis, retinol, pyruvate, and amino acids metabolism pathways are also affected by the mycotoxins. Antioxidants restored expression level of proteins PRDX3, AGL, PYGL, fatty acids biosynthesis, endoplasmic reticulum, peroxisome, amino acid synthesis pathways, and, partially, OXPHOS mitochondrial subunits. However, excess of antioxidants might cause significant changes in CYP2C301, PPP4R4, COL18A1, UBASH3A, and other proteins expression levels. Future analysis of proteomics data corelated to animals growing performance and meat quality studies are necessary.