Elsevier

Food Control

Volume 34, Issue 2, December 2013, Pages 596-600
Food Control

The risk management dilemma for fumonisin mycotoxins

https://doi.org/10.1016/j.foodcont.2013.05.019Get rights and content

Abstract

Since the discovery of the fumonisins in 1988, extensive academic studies have generated much knowledge, including data on chemistry, biochemistry, toxicology, methods of analysis, natural occurrence in food supplies, fate during various processing procedures, and human and animal exposures. These mycotoxins have also been assessed by the International Agency for Research on Cancer (IARC) and have twice been the subject of risk assessments by the Joint FAO/WHO Expert Committee on Food Additives (JECFA). The outcome of these investigations has been of a nature to alert risk managers to the necessity of controlling human exposure. However, the fumonisins occur mostly in maize, a world staple crop which is consumed in various communities at levels which can be as many as 100-fold different. Compounding the problem is the fact that maize is widely used as animal feed in many developed countries, whereas in Africa and some other developing countries, it is the primary food source. This contrast produces a problem for risk managers, partly solved at national level by the regulation of maximum tolerated levels (MTLs) applicable to individual countries. MTLs at an international level are currently under discussion at the Codex Committee on Contaminants in Food. The divergence in use and consumption and the fact that maize in various regions of the world can also vary greatly in contamination levels, leads to a dilemma for setting such MTLs, which would need to be low to protect the high maize consumers, but might then cause rejection of high amounts of the world supply. Higher MTLs, acceptable to maize exporters, would only protect the low maize consumers. This dilemma may only be solved by accepting that harmonizing regulations for raw maize is problematic and a more nuanced approach may be required.

Introduction

The fumonisin mycotoxins, of which fumonisin B1 (FB1) and B2 (FB2) are the most important, occur ubiquitously in maize and hence in maize products worldwide (Bolger et al., 2001). Although sporadic reports exist of fumonisins in other products, maize and possibly sorghum remain the primary sources of human exposure (Bulder et al., 2012). The effects of fumonisin ingestion in animal species have been documented and are very species specific. Ingestion of FB1 causes leukoencephalomalacia in horses (Kellerman et al., 1990) and pulmonary oedema in swine (Harrison, Colvin, Green, Newman, & Cole, 1990). In rodents, fumonisins are hepato- and nephrotoxins and carcinogens (Gelderblom, Kriek, Marasas, & Thiel, 1991; Howard et al., 2001).

The acute intake of fumonisins from mouldy maize and sorghum has been linked to an outbreak in the Deccan Plateau in southern India of food-borne disease characterized by borborygmy, abdominal pain and diarrhoea (Bhat, Shetty, Amruth, & Sudershan, 1997). Chronic ingestion of fumonisins has been linked as one possible risk factor for the occurrence of oesophageal cancer in areas such as the former Transkei region of South Africa, where fumonisin exposure from contaminated maize is high (Rheeder et al.,1992). Similar associations have been reported in maize grown in Linxian County, Henan Province and Cixian County, Hebei Province, China (Zhang, Nagashima, & Goto, 1997), maize grown in Huaian County, Jiangsu Province, China (Sun et al., 2007), maize grown in Santa Catarina state, southern Brazil (Van der Westhuizen et al., 2003) and in polenta produced in northern Italy (Pascale, Doko, & Visconti, 1995). Fumonisins have also been linked as a risk factor for primary liver cancer in China (Sun et al., 2007; Ueno et al., 1997). The International Agency for Research on Cancer (IARC) has classified FB1 as a possible human carcinogen (group 2B) (IARC, 2002).

Evidence has emerged of the detrimental effects of fumonisin on the developing foetus and young infants. A cluster of cases of neural tube defects (NTDs) in infants in southern Texas has provided epidemiological evidence that fumonisins may have played a role in these cases in which mothers are presumed to have consumed fumonisin contaminated food (Missmer et al., 2006). It is also known that other areas of the world where fumonisin exposure is high, such as former Transkei region in South Africa and regions in northern China, have elevated incidences of neural tube defects (NTDs) (Marasas et al., 2004). Support for this association has come from evidence that fumonisins, via their depletion of sphingolipids, interfere with the folate receptor, inhibiting uptake of folate, the cellular deficiency of which is a known cause of NTDs (Stevens & Tang, 1997). Further evidence for these interactions comes from a dose-dependent rise in NTDs in fumonisin-dosed experimental mice, an effect that could be prevented by folate supplementation (Gelineau-van Waes et al., 2005). Further studies in infants in Tanzania have shown that ingestion of fumonisin was associated with growth retardation as measured in infants at 12 months of age (Kimanya, De Meulenaer, Roberfroid, Lachat, & Kolsteren, 2010).

Section snippets

Risk assessment

In 2001, the 56th meeting of the Joint FAO/WHO Expert Committee on Food Additives (JECFA) evaluated fumonisins and established a provisional maximum tolerable daily intake (PMTDI) of 2 μg/kg body weight/day for FB1, FB2 and FB3, either alone or in combination, based on a no observed effect level (NOEL) of 0.2 mg/kg body weight/day for renal toxicity and a safety factor of 100 (Bolger et al., 2001). This PMTDI was re-assessed and confirmed in 2010 at the 74th meeting of JECFA in which benchmark

Effects of processing

The primary source of fumonisin exposure is via consumption of maize or its processed products. Thus, the processing of maize and the exact form of the product used as food has an important bearing on the exposure assessment and is an important consideration in the setting of regulations. The fate of fumonisins during various processing stages has been the subject of various research papers and published results indicate that large reductions in contamination levels can be achieved. The

Risk management

The risk assessments described above clearly indicate the need for intervention by risk managers. The current response to this need can be divided into research initiatives to investigate ways to reduce fumonisin levels on a field-to-fork basis and the implementation of national MTLs. Table 1 lists MTLs for human food as recorded in the Food and Agriculture Organization survey of 2003 (FAO, 2004) and other sources. The basis and rationale for these exact levels are not available. Besides the

Future MTL scenarios

For the sake of international trade, an agreement is required for MTL applicable to maize grain. This MTL should not lead to wide rejection of the maize harvest, yet should not be implemented at the expense of health in African maize consuming countries. A reasonable approach to the setting of MTLs would challenge producers to improve maize quality without destroying the supply. It would need to be recognized at international level that maize can be marketed in Africa not only as a commercially

Conflict of interest

The authors declare that there are no conflicts of interest.

Acknowledgements

The authors thank the Codex Committee Africa and African Union - Interafrican Bureau for Animal Resources (AU-IBAR) for funding the meeting of the authors (GSS, MEK, KAK and GJBG) at which these concepts were developed.

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    Current address: School of Life Sciences and Bio-Engineering (LSBE), The Nelson Mandela African Institute of Science and Technology (NM-AIST), Tengeru, P.O. Box 447, Arusha, Tanzania.

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