Gordon S. Shephard

The implications of naturally occurring levels of fumonisins in corn for human and animal health

Contamination of corn with the fungus Fusarium moniliforme and its secondary metabolites, the fumonisins, has been associated with several human and animal diseases. This paper summarizes present knowledge and presents new data on the levels of fumonisins present in foods and feeds associated with these diseases as well as in commercial corn and corn-based products. The doses of fumonisins to which humans and animals consuming these products would be exposed are compared with those doses known to produce LEM in horses and hepatocarcinogenesis in rats. It is concluded that the known naturally occurring levels of fumonisins present a potential threat to human and animal health and realistic tolerance levels need to be set.

Developments in mycotoxin analysis: an update for 2015-2016

This review summarises developments in the determination of mycotoxins over a period between mid-2015 and mid-2016. Analytical methods to determine aflatoxins, Alternaria toxins, ergot alkaloids, fumonisins, ochratoxins, patulin, trichothecenes and zearalenone are covered in individual sections. Advances in proper sampling strategies are discussed in a dedicated section, as are methods used to analyse botanicals and spices and newly developed liquid chromatography mass spectrometry based multi-mycotoxin methods. This critical review aims to briefly discuss the most important recent developments and trends in mycotoxin determination as well as to address limitations of presented methodologies.

Aflatoxins and growth impairment: A review

Aflatoxins, fungal toxins produced by Aspergillus flavus and Aspergillus parasiticus in a variety of food crops, are well known as potent human hepatocarcinogens. Relatively less highlighted in the literature is the association between aflatoxin and growth impairment in children. Foodborne aflatoxin exposure, especially through maize and groundnuts, is common in much of Africa and Asia—areas where childhood stunting and underweight are also common, due to a variety of possibly interacting factors such as enteric diseases, socioeconomic status, and suboptimal nutrition. The effects of aflatoxin on growth impairment in animals and human children are reviewed, including studies that assess aflatoxin exposure in utero and through breastfeeding. Childhood weaning diets in various regions of the world are briefly discussed. This review suggests that aflatoxin exposure and its association with growth impairment in children could contribute a significant public health burden in less developed countries.

Impact of mycotoxins on human health in developing countries

Adverse human health effects from the consumption of mycotoxins have occurred for many centuries. Although mycotoxin contamination of agricultural products still occurs in the developed world, the application of modern agricultural practices and the presence of a legislatively regulated food processing and marketing system have greatly reduced mycotoxin exposure in these populations. At the mycotoxin contamination levels generally found in food products traded in these market economies, adverse human health effects have largely been overcome. However, in the developing world, where climatic and crop storage conditions are frequently conducive to fungal growth and mycotoxin production, much of the population relies on subsistence farming or on unregulated local markets. The extent to which mycotoxins affect human health is difficult to investigate in countries whose health systems lack capacity and in which resources are limited. Aflatoxin B1, the toxin on which major resources have been expended, has long been linked to liver cancer, yet its other effects, such as immune suppression and growth faltering previously observed in veterinary studies, are only now being investigated and characterized in human populations. The extent to which factors such as immune suppression contribute to the overall burden of infectious disease is difficult to quantify, but is undoubtedly significant. Thus, food safety remains an important opportunity for addressing current health problems in developing countries.

Aflatoxin and Food Safety: Recent African Perspectives

The issue of food safety in Africa is one which interacts with and is frequently subjugate to issues of food security, especially in geographic areas where food shortages are caused by recurrent natural weather phenomena such as drought. In addition, many subsistence farming communities in Africa are reliant on the consumption of home‐grown crops, irrespective of the quality considerations normally applied in the developed world. Nevertheless, some African governments have instituted food safety regulations to control mycotoxin, especially aflatoxin, contamination of the national food supply and research into natural occurrence of aflatoxins in a range of local foods is widely conducted. This review summarises the work published in this field through the previous decade. It emphasizes that much of the research effort has been performed in South Africa, Egypt and in various countries in west Africa including Ghana, Nigeria and The Gambia. Although much of the published research deals with levels of aflatoxin contamination in staple foods such as maize and groundnuts, other particularly local foods such as cured and smoke‐dried fish have been implicated as sources of dietary aflatoxin in various areas of Africa. The conclusion to be drawn from this survey is that aflatoxin exposure remains an important aspect of food safety which needs to be addressed by African communities.

Risk assessment of aflatoxins in food in Africa

Aflatoxins are secondary metabolites of the fungi Aspergillus flavus and A. parasiticus, occur widely on many staple foods and cause a broad range of detrimental health effects in animals and humans. As a consequence, maximum tolerated levels (MTLs) have been legislated in many countries. However, in developing countries where food safety compliance can be low and significant levels of the food supply are locally consumed by the producers or purchased at local markets, more comprehensive strategies are required. In this regard, risk analysis with its components of risk assessment, risk management and risk communication, is an important tool in dealing with food safety issues. Risk assessment for aflatoxin B1 in Africa has been performed using the carcinogenic potency, established by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) and applying it to typical food products and consumption across the continent, to illustrate the significant health implications caused by the intake of high levels of contaminated foods. Highlighted in this assessment is the fact that even low levels of contamination, which might of themselves fall within legislated limits, can have serious health implications due to high levels of consumption, i.e. meeting a MTL does not of itself guarantee food safety. Recent developments have highlighted the growth retardation and immune suppression caused by aflatoxin exposure in human populations in west Africa. Using the limited data available on both these health effects, a first step has been taken to incorporate them into a risk assessment paradigm quantifying the risk of immunosuppression, malnutrition and stunting in children exposed to aflatoxins and highlighting again how excessive consumption of foods meeting MTLs can carry significant health risks.

Chromatographic determination of the fumonisin mycotoxins

The fumonisins are a recently identified group of fungal toxins, occurring worldwide in naturally contaminated maize, which have elicited considerable attention over the past decade due to their association with the animal disease syndromes, equine leukoencephalomalacia and porcine pulmonary oedema, and their reported association with oesophageal cancer in rural areas of Transkei, South Africa and Linxian County, China. This paper reviews the development of sensitive chromatographic analytical methods for the determination of these toxins in a range of mainly maize or maize-based food matrices. Initial attempts at gas chromatographic determination of these toxins were supplanted by the successful development of liquid chromatographic methods based on solid-phase extraction (SPE) of solvent extracts, followed by precolumn derivatisation and HPLC determination using fluorescence detection. The most widely used method involves strong anion-exchange (SAX) SPE and the use of o-phthaldialdehyde as derivatising agent. In contrast, the development of thin-layer chromatographic methods enables large numbers of samples to be screened economically. The recent advances in liquid chromatography-mass spectrometry have resulted in the development of suitable methods for fumonisin analysis without the need of derivatisation.

Aflatoxin analysis at the beginning of the twenty-first century

Aflatoxin mycotoxins were first described in the early 1960s as important fungal toxins, which contaminate many different human foods and animal feeds. Accurate and sensitive determination of these carcinogenic compounds immediately became an important requirement to meet food safety concerns and new official legislated regulations. For these reasons, analytical methods for aflatoxins continued to develop over the decades, reflecting advances in analytical chemistry. Currently, a wide range of methods are available to analytical scientists, ranging from newly described multi-toxin liquid chromatography tandem mass spectrometry to rapid methods based on immunological principles. These latter methods can provide quantitative outputs or a simple rapid determination of contamination level above or below a pre-determined cutoff value. The newest official methods as validated by Association of Official Analytical Chemists International or Comité Européen de Normalisation rely on immunoaffinity column clean-up of conventional extracts, followed by high-performance liquid chromatography separation of the analogues with detection based on natural fluorescence or the fluorescence generated by various derivatisation methods. In selecting from this range of available methods, the analytical chemist must decide on the requirements of the analysis such that the method chosen is ‘fit for purpose’.

Exposure assessment for fumonisins in the former Transkei region of South Africa

The fumonisins are mycotoxins produced mainly by Fusarium verticillioides and F. proliferatum in maize, the predominant cereal staple for subsistence farming communities in southern Africa. In order to assess exposure to these mycotoxins in the Bizana (now known as Mbizana) and Centane magisterial areas of the former Transkei region of the Eastern Cape Province of South Africa, the actual maize consumption by different age groups in these communities was measured. In the groups 1–9 years (n = 215) and 10–17 (n = 240) years, mean consumption (±standard error) was 246 ± 10.8 and 368 ± 10.3 g per person day−1, respectively, with no significant difference (p > 0.05) between the magisterial areas. For adults (18–65 years) mean maize consumption in Bizana (n = 229) and Centane (n = 178) were significantly different (p < 0.05) at 379 ± 10.5 and 456 ± 11.9 g per person day−1, respectively. An exposure assessment was performed by combining the maize consumption distribution with previously determined levels of total fumonisin (fumonisins B1 and B2 combined) contamination in home-grown maize in these two areas. Assuming an individual adult body weight of 60 kg, fumonisin exposure in Bizana, an area of relatively low oesophageal cancer incidence, was 3.43 ± 0.15 µg kg−1 body weight day−1, which was significantly lower (p < 0.05) than that in Centane (8.67 ± 0.18 µg kg−1 body weight day−1), an area of high oesophageal cancer incidence. Mean fumonisin exposures in all age groups in both Bizana and Centane were above the provisional maximum tolerable daily intake (PMTDI) of 2 µg kg−1 body weight day−1 set by the Joint FAO/WHO Expert Committee on Food Additives.

Patulin in South African commercial apple products

Abstract A survey on the presence of the mycotoxin, patulin, was conducted from 1996 to 1998 on sixty locally produced commercial apple products purchased from retail outlets in South Africa. Twenty-three of the 31 fruit juice samples had no detectable patulin contamination. The 8 contaminated juice samples had patulin concentrations ranging between 5 and 45 μg/l with a mean of 10 μg/l patulin. Of 6 whole fruit products, 2 samples were contaminated with 10 μg/g patulin. From 10 infant fruit juices, 6 samples had patulin concentrations ranging between 5 and 20 μg/l. The infant fruit purees showed no detectable patulin contamination. The low incidence of patulin in South African commercial apple products indicates that the quality of the fruit and the manufacturing practices are of a high standard.