The health impacts of mycotoxins in the eastern Africa region

Mycotoxins contamination of market maize and the potential of density sorting in reducing exposure in unregulated food systems in Kenya

Aflatoxins and fumonisins commonly contaminate key food staples in tropical countries, causing recurring acute and chronic public health problems. The present study was conducted to assess the potential of a simple device designed for density-based sorting of maize for its potential to reduce aflatoxins and fumonisins in diverse samples of naturally contaminated maize. A cross sectional survey was conducted, analysing market maize samples (n=204) from eight counties in Western Kenya. A quarter (25%) of the maize samples were contaminated with aflatoxin B1 above the legal limit of 5 μg/kg and nearly half (48%) were contaminated with fumonisins at levels above the legal limit of 2 μg/g. Analysis of additional samples (n=24) from Meru County showed that contamination of maize with the two toxins was also common in Eastern Kenya. A simple density sorter was used to separate grain samples into heavy and light fractions. With an out-sort rate of 31%, density sorting was effective in separating maize by bulk density and 100-kernel weight (P<0.001). Bulk density was negatively correlated with aflatoxins in unsorted (r=-0.20, P<0.01) and heavy fractions (r=-0.32, P<0.01). Density sorting was effective at reducing fumonisins; for maize samples with >1 μg/g, the heavy (accepted) fraction had 66% lower fumonisins than the unsorted maize. After density sorting, the light and heavy fractions fumonisin levels differed by an average of 8.38 μg/g (P<0.001). However, sorting was not effective at significantly reducing aflatoxin levels in maize that was highly contaminated. A simple density sorting equipment that could be adopted by local small-scale millers has potential to reduce fumonisins in maize. Additional and complementary sorting technologies, such as size screening and spectral sorting might improve the effectiveness of reducing aflatoxins in maize.

Estimating the risk of aflatoxin-induced liver cancer in Tanzania based on biomarker data

Evidence about the magnitude of the aflatoxin menace can help policy makers appreciate the importance of the problem and strengthen policies to support aflatoxin mitigation measures. In this study, we estimated aflatoxin-induced liver cancer risk in 2016 for Tanzania and used the information to estimate the health burden due to the aflatoxin exposure in the country. The burden of aflatoxin-induced liver cancer was assessed based on available aflatoxin biomarker data from a previous epidemiology study, hepatitis B virus infection prevalence and population size of Tanzania in 2016. The health burden due to aflatoxin-induced liver cancer was estimated using disability adjusted life years (DALYs). The aflatoxin exposures ranged from 15.0–10,926.0 ng/kg bw/day (median, 105.5 ng/kg bw/day). We estimated that in 2016 there were about 1,480 (2.95 per 100,000 persons) new cases of aflatoxin-induced liver cancer in Tanzania and assumed all of them would die within a year. These morbidity and mortality rates led to a total loss of about 56,247.63 DALYs. These results show, quantitatively, the cases of liver cancer and related deaths that could be avoided, and the healthy life years that could be saved, annually, by strengthening measures to control aflatoxin contamination in Tanzania.

The occurrence of aflatoxins and human health risk estimations in randomly obtained maize from some markets in Ghana

Maize and its products are most often prone to fungal contamination especially during cultivation and storage by toxigenic fungi. Aflatoxicosis still persist in Ghana despite the numerous education on several ways of its prevention at the farm as well as its adverse health implications which are food safety concerns. A random assessment and human risk analysis was conducted on 90 maize (72 white and 18 colored) samples from markets across all the regions of Ghana. Total aflatoxins (AFtotal) and the constitutive aflatoxins (AFB₁, AFB₂, AFG₁, and AFG₂) were analyzed by High-Performance Liquid Chromatography (HPLC). Out of a total of ninety (90) samples investigated, 72 (80%) tested positive for AFB₁ and the contamination levels ranged from 0.78 ± 0.04 to 339.3 ± 8.6 µg kg⁻¹. Similarly, AFG2 was detected in only 14 (15.5%) samples, and their values ranged between 1.09 ± 0.03 and 5.51 ± 0.26 µg kg⁻¹ while AF total ranged between 0.78 ± 0.04 and 445.01 ± 8.9 µg kg⁻¹ constituting approximately 72 (80%). Limits of AFB₁ and total aflatoxins (AFtotal) for the Ghana Standards Authority (GSA) (5 and 10 µg kg⁻¹) and the European Food Safety Authority (EFSA) (2 and 4 µg kg⁻¹), were used as checks. A total of 33 (41.25%) samples were above the limits for both. Risk assessments recorded for Estimated Daily Intake (EDI), Hazard Quotient (H.Q), Hazard Index (H.I), Margin of Exposure (MOE), av. Potency, and population risks ranged 0.087–0.38 μg kg⁻¹ bw day⁻¹, 1.5–6.9, 0.0087–0.38, 3.64–12.09, 0–0.0396 ng Aflatoxins kg⁻¹ bw day⁻¹ and, 3.5 × 10^–1–0.015 respectively for total aflatoxins. While ranges for aflatoxins B1 (AFB1) recorded were 0.068–0.3 μg Kg bw⁻¹ day⁻¹, 2.43–10.64, 0.0068–0.030, 4.73–20.51, 0–0.0396 ng Aflatoxins kg⁻¹ bw day⁻¹ and, 2.69 × 10^–3–0.012 for Estimated Daily Intake (EDI), Hazard Quotient (H.Q), Hazard Index (H.I), Margin of Exposure (MOE), Av. potency, and population risks respectively. It was deduced that although there was some observed contamination of maize across the different ecological zones, the consumption of maize (white and colored) posed no adverse health effects on the population of Ghana since computed H.I was less than 1 (< 1).

Aflatoxins in randomly selected groundnuts (Arachis hypogaea) and its products from some local markets across Ghana: Human risk assessment and monitoring

A random assessment and human risk analysis were conducted on 80 groundnut pastes and raw groundnuts from some local markets across the different agroecological zones of Ghana. Total aflatoxins (AFtotal) and aflatoxins (AFB₁, AFB₂, AFG₁, and AFG₂) were analyzed using the High-Performance Liquid Chromatography (HPLC) method. Out of 80 samples investigated, 49 (61.25 %) tested positive for AFB₁ and ranged from 0.38 ± 0.04-230.21 ± 22.14 μg/kg. The same proportion was recorded for total aflatoxins (AF_total) and ranged between 0.38 ± 0.02-270.51 ± 23.14 μg/kg. Limits of AFB₁ and total aflatoxins (AFtotal) for the Ghana Standards Authority (GSA) (5 and 10 μg/kg) and the European Food Safety Authority (EFSA) (2 and 4 μg/kg), were used as checks. A total of 33 (41.25 %) samples were above the limits for both. Risk assessments recorded for Estimated Daily Intake (EDI), Margin of Exposure (MOE), potency, cancer risk, and population risks ranged 0.087-0.380 μg/Kg.bw/day, 1052.630-4597.700, 0-0.00396 ng Aflatoxins kg^-1bwday^-1 and, 1.5 × 10^-3 - 7.9 × 10^-4 respectively for total aflatoxins. While for aflatoxins B₁ (AFB₁), ranges of values of 0.068-0.300 μg/Kg.bw/day, 1333.33-5882.35, 0-0.00396 ng aflatoxins kg/bw/day and, 1.19 × 10^-3 - 6.34 × 10^-4 corresponded for Estimated Daily Intake (EDI), Margin of Exposure (MOE), potency, cancer risk, and population risk respectively. There were risks of adverse health effects involved in the consumption of groundnuts for all age groups investigated since MOE values were all below 10,000.

Aflatoxin M1 in Africa: Exposure Assessment, Regulations, and Prevention Strategies - A Review

Aflatoxins are the most harmful mycotoxins causing health problems to human and animal. Many acute aflatoxin outbreaks have been reported in Africa, especially in Kenya and Tanzania. When ingested, aflatoxin B1 is converted by hydroxylation in the liver into aflatoxin M1, which is excreted in milk of dairy females and in urine of exposed populations. This review aims to highlight the AFM1 studies carried out in African regions (North Africa, East Africa, West Africa, Central Africa, and Southern Africa), particularly AFM1 occurrence in milk and dairy products, and in human biological fluids (breast milk, serum, and urine) of the populations exposed. Strategies for AFM1 detoxification will be considered, as well as AFM1 regulations as compared to the legislation adopted worldwide and the assessment of AFM1 exposure of some African populations. Egypt, Kenya, and Nigeria have the highest number of investigations on AFM1 in the continent. Indeed, some reports showed that 100% of the samples analyzed exceeded the EU regulations (50 ng/kg), especially in Zimbabwe, Nigeria, Sudan, and Egypt. Furthermore, AFM1 levels up to 8,000, 6,999, 6,900, and 2040 ng/kg have been reported in milk from Egypt, Kenya, Sudan, and Nigeria, respectively. Data on AFM1 occurrence in human biological fluids have also shown that exposure of African populations is mainly due to milk intake and breastfeeding, with 85-100% of children being exposed to high levels. Food fermentation in Africa has been tried for AFM1 detoxification strategies. Few African countries have set regulations for AFM1 in milk and derivatives, generally similar to those of the Codex alimentarius, the US or the EU standards.

Rural Subsistence Maize Farming in South Africa: Risk Assessment and Intervention models for Reduction of Exposure to Fumonisin Mycotoxins

Maize is a staple crop in rural subsistence regions of southern Africa, is mainly produced for direct household consumption and is often contaminated with high levels of mycotoxins. Chronic exposure to mycotoxins is a risk factor for human diseases as it is implicated in the development of cancer, neural tube defects as well as stunting in children. Although authorities may set maximum levels, these regulations are not effective in subsistence farming communities. As maize is consumed in large quantities, exposure to mycotoxins will surpass safe levels even where the contamination levels are below the regulated maximum levels. It is clear that the lowering of exposure in these communities requires an integrated approach. Detailed understanding of agricultural practices, mycotoxin occurrence, climate change/weather patterns, human exposure and risk are warranted to guide adequate intervention programmes. Risk communication and creating awareness in affected communities are also critical. A range of biologically based products for control of mycotoxigenic fungi and mycotoxins in maize have been developed and commercialised. Application of these methods is limited due to a lack of infrastructure and resources. Other challenges regarding integration and sustainability of technological and community-based mycotoxin reduction strategies include (i) food security, and (ii) the traditional use of mouldy maize.

Investigation and Characterization of Myroides odoratimimus Strain 3J2MO Aflatoxin B1 Degradation

Aflatoxin B₁ (AFB₁), is a type I carcinogen that is one of the strongest naturally occurring aflatoxins and can be injurious to humans and livestock upon ingestion, inhalation, or skin contact, with carcinogenic and mutagenic effects. It causes significant hazardous effects to the food- and animal-production industries. We found a bacterial strain, 3J2MO, that degraded AFB₁ well, and here we tested and characterized its AFB₁-degradation ability. The strain degraded about 93.82% of the AFB₁ after incubation for 48 h in Luria-Bertani (LB) medium at 37 °C with a final concentration of 100 ppb and an inoculation quantity of 1 × 10⁷ cfu/mL. High-performance liquid chromatography-fluorescence detection (HPLC-FLD) was used to determine AFB₁ amounts. The maximum degradation rates were 89.23% at pH 8.5; 55.78% at an inoculation quantity of 1 × 10⁸ cfu/mL; and 71.50 and 71.21% at 34 and 37 °C, respectively. Treatment with sucrose and soluble starch as carbon sources and beef extract and ammonium acetate as nitrogen sources stimulated the degradation rate. Mg²⁺ and Ca²⁺ ions were activators for AFB₁ degradation; however, Mn²⁺, Fe³⁺, Zn²⁺, and Cu²⁺ were strong inhibitors. This bacterial strain has potential in bioremediation and the detoxification of aflatoxin contamination for biocontrol strategies in both agricultural products and food-industry matrices.

Bioaccessibility in daily diet and bioavailability in vitro of aflatoxins from maize after cooking

Bioavailability is not a constant percentage of a contaminant in food but is affected by many factors, such as food type, treatment, diet structure and interaction with other compounds. To evaluate these influences, we measured the bioaccessibility of aflatoxins from nine naturally polluted maize samples, collected from southeast China, using an in vitro digestion model, and analysed the intestinal transport of aflatoxins by a Caco-2 cell model. Steam cooking treatment could reduce the aflatoxin levels in maize bread. The degradation rates of aflatoxin B1, aflatoxin B2, aflatoxin G1, and aflatoxin G2 ranged from 24.9±3.2 to 33.9±3.5%, 27.0±2.0 to 39.0±1.8%, 27.9±7.9 to 34.4±8.2% and 25.6±3.6 to 37.2±6.5%, respectively. As a result, the bioaccessibility of aflatoxins determined by an in vitro digestion model (41.5-63.3%) was much lower than the previously reported 80%. Edible oil could increase the bioaccessibility of aflatoxin, whereas lettuce would decrease the exposure amount from maize. With a Caco-2 cell model, the apparent permeability coefficient exceeding 10-5 cm/s indicated that there is high absorption of aflatoxins in the human body, while the intestinal transport can be effectively restrained in the presence of chlorophyll.

Inadequate management of complementary foods contributes to the risk of aflatoxin exposure and low nutrition status among children

Early exposure to aflatoxins through complementary food is linked to impaired growth in childhood. The current study assessed the household’s practices on management of complementary foods in relation to the risk of aflatoxin exposure and poor nutritional status among infant and young children in Tanzania. A cross-sectional study of complementary feeding practices, aflatoxin exposure and nutritional status was conducted to 101 infants and young children aged between 6-23 months in Dodoma region of Tanzania. The intake of complementary food was estimated by using repeated 24 h dietary recall. Flour used as complementary food was sampled from each of the 101 families and aflatoxins were analysed using high-performance liquid chromatography. A deterministic approach was used to estimate dietary exposure of aflatoxins in the complementary foods. Anthropometric measurements were taken and rates of stunting, underweight and wasting estimated according to the WHO standard procedures. Multivariate logistic regression analysis was used to assess the association between feeding practices and aflatoxin exposure or the growth performance among subjects. The average consumption of complementary flour was 118 g per child per day and 52% of the flours contained groundnuts. AFB1 was detected in 42.5% of the flour and levels ranged from 0.3 to 2,128.0 μg/kg (mean 228.11±49.84 μg/kg). Dietary exposures of aflatoxin B1 ranged from 0.1 to 23,172.81 ng/kg body weight per day (mean 1,337±392.5 ng/kg). Of the subjects, 40.4% (95% CI; 29.8; 50.9) were stunted and significant association was found between stunted growth and dietary exposure of AFB1 (adjusted odd ratio (AOR)=5.9; 95% CI: 0.019-0.028). Early introduction of cereal-and groundnut-based complementary foods in Tanzania is associated with high risk of aflatoxin exposure and impaired growth in children. There is need to integrate aflatoxin management measures in the guidelines for Infant and Young Children Feeding of Tanzania.

Mycotoxin contamination of foods in Southern Africa: A 10-year review (2007-2016)

Major staple foods in Southern Africa are prone to mycotoxin contamination, posing health risks to consumers and consequent economic losses. Regional climatic zones favor the growth of one or more main mycotoxin producing fungi, Aspergillus, Fusarium and Penicillium. Aflatoxin contamination is mainly reported in maize, peanuts and their products, fumonisin contamination in maize and maize products and patulin in apple juice. Lack of awareness of occurrence and risks of mycotoxins, poor agricultural practices and undiversified diets predispose populations to dietary mycotoxin exposure. Due to a scarcity of reports in Southern Africa, reviews on mycotoxin contamination of foods in Africa have mainly focused on Central, Eastern and Western Africa. However, over the last decade, a substantial number of reports of dietary mycotoxins in South Africa have been documented, with fewer reports documented in Botswana, Lesotho, Malawi, Mozambique, Zambia and Zimbabwe. Despite the reported high dietary levels of mycotoxins, legislation for their control is absent in most countries in the region. This review presents an up-to-date documentation of the epidemiology of mycotoxins in agricultural food commodities and discusses the implications on public health, current and recommended mitigation strategies, legislation, and challenges of mycotoxin research in Southern Africa.

Mycotoxin in the food supply chain-implications for public health program

Mycotoxins are a group of naturally occurring toxic chemical substances, produced mainly by microscopic filamentous fungal species. Regarding potential synergisms or even mitigating effects between toxic elements, mycotoxin contamination will continue to be an area of concern for producers, manufacturers, regulatory agencies, researchers, and consumers in the future. In Serbia, recent drought and then flooding confirmed that mycotoxins are one of the foodborne hazards most susceptible to climate change. In this article, we review key aspects of mycotoxin contamination of the food supply chain and implications for public health from the Serbian perspective.

Determination of Exposure to the Alternaria Mycotoxin Tenuazonic Acid and Its Isomer allo-Tenuazonic Acid in a German Population by Stable Isotope Dilution HPLC-MS(3)

The content of the Alternaria toxin tenuazonic acid and its isomer allo-tenuazonic acid was quantitated in urine of a German cohort (n = 48) using a newly developed and successfully validated solid phase extraction based stable isotope dilution HPLC-MS(3) method. Tenuazonic acid was detected in all of the samples and quantifiable in 97.9% of these samples in a range of 0.16-44.4 ng/mL (average = 6.58 ng/mL) or 0.07-63.8 ng/mg creatinine (average = 8.13 ng/mg creatinine). allo-Tenuazonic acid was for the first time detected in human urine (95.8% of the samples positive) and quantitated in 68.8% of the samples in a range of 0.11-5.72 ng/mL (average = 1.25 ng/mL) or 0.08-10.1 ng/mg creatinine (average = 1.52 ng/mg creatinine), representing 3.40-25.0% of the sum of both isomers (average = 12.4%). Food-frequency questionnaires were used to document food consumption of study participants to correlate mycotoxin exposure to nutritional habits. Although no statistically significant correlation between consumption of a specific food and urinary excretion of tenuazonic acid could be determined, a trend regarding elevated intake of cereal products and higher excretion of tenuazonic acid was evident. On the basis of these results, a provisional mean daily intake (PDI) for both tenuazonic acid and allo-tenuazonic acid was calculated, being 0.183 and 0.025 μg/kg body weight, respectively. A combined mean PDI for both isomers amounts to 0.208 μg/kg body weight with the highest individual PDI for one of the participants (1.582 μg/kg body weight) slightly exceeding the threshold of toxicological concern assumed for tenuazonic acid by the European Food Safety Authority of 1.500 μg/kg body weight. This is the first study to investigate the tenuazonic acid content in human urine of a larger sample cohort enabling the calculation of PDIs for tenuazonic acid and allo-tenuazonic acid.