Jonathan H Williams

Abstract

The generally accepted model for the management of mycotoxins is regulation and the institutions usually identified as having a stake in mycotoxin contamination represent either producers/suppliers or regulators/consumers at both the global and the national levels. Stakeholders also service the need for analysis and enforcement of the regulations in trade. Consumers, although paying more, are passive stakeholders. The regulatory approach is effective for developed country food systems, but is ineffective for most situations in developing countries. Food systems and scales of production, processing, and the lack of effective means of assuring food with safe levels of mycotoxins prevent regulation from being effective in developing countries where the model applied generally is one of denial or neglect. In these settings, a consumer management model is required to reduce mycotoxin exposure.

Introduction

Almost all commodities are at risk of contamination by one or more mycotoxins. Mycotoxins are common, and are considered by the Food and Drug Administration of the United States to be unavoidable. Thus everyone is a stakeholder in the mycotoxin problem as a consumer of potentially contaminated food. In developed countries, the popular knowledge of these toxins usually is minimal, since regulated food systems operate to provide safe food and such knowledge is not necessary for an individual's well being. In developing countries the poor people are the most at risk of exposure to mycotoxins since contamination commonly is associated with poorer quality and lower priced foods that can usually be avoided by the affluent.

Aflatoxins are the best known and most heavily regulated of the mycotoxins. There are individual stakeholders in aflatoxin contamination all along the value chain from producer to consumer and beyond, but this chapter is about the institutions that presently represent the individuals with a stake, and those who should have a role in the future. Since our perceptions of the problem change as our knowledge, economy and technology evolves, the stakeholders also change. Thus, we can identify a number of classes of institutional stakeholders: (i) those actively involved; (ii) those with mandated involvement; and (iii) those with a logical reason for future involvement. Rather than provide a detailed list, these institutional stakeholders are considered by their generic functions.

Two major classes of stakeholder can be defined - those on the supply side of the issue and those on the demand side (consumers), although some entities may be both a consumer of a commodity for processing and a supplier of a processed product. Thus, the institutional perspectives can be complicated. On the supply side of the equation there are the stakeholders that produce, trade, process and add value to the commodity. Their returns on investments are dependent upon the level of contamination in the commodities. The mycotoxin of concern depends on the commodity and the fungal species involved. A general model is provided by aflatoxin, which is perhaps the most extensively investigated mycotoxin, has numerous stakeholders, is the first identified and most extensively regulated mycotoxin; and is the toxin about which the author has the most knowledge.

Aflatoxins are a group of secondary metabolites produced primarily by Aspergillus spp. when they invade the tissue of many food products. These fungi grow most actively if the water content is between 10% and 18%, i.e., partially dried produce, and when the temperatures are between 24 and 33°C. Such conditions often are found in crops exposed to drought or in storage, particularly in the tropics. Infection and contamination may occur preharvest, but most aflatoxin is synthesized postharvest. A number of staple tropical crops, e.g., maize, peanut, rice and cassava can be contaminated and temperature conditions in the tropics and sub-tropics often are appropriate for contamination to occur. For example, aflatoxin contamination of maize is a common annual risk for farmers in Texas, but is an issue for corn belt farmers in the United States only in years of drought and abnormally high temperatures.

A large number of facts and intersecting forces must be described and then synthesized to make the present situation clear and to make logical predictions of the future for stakeholders in the issue.

Sequences of institutional involvement

There is a natural sequence of institutional involvement in any mycotoxin problem. Aflatoxin is a mature hazard in this regard so reviewing this sequence provides details about both the toxin and established management approaches. It also provides some insight into failures in the present paradigms for managing mycotoxins and enables us to predict that a new set of institutions should be involved in the issue. Maturity, after all, is a relative state.

Mycotoxin discovery

Discovery of a mycotoxin usually occurs in the animal science or veterinary fields because animals have a wide range of susceptibilities to mycotoxins and act as biological sentinels for problems. The institutions involved at this stage are the veterinary and toxicology research institutions. Once a possible risk to human health is defined the regulatory and food production agencies become involved as well.

Problem description

Description of the problem is the next stage, with the involved institutions seeking to establish a comprehensive description of the scale and scope of the problem, the difficulties of addressing it and the economic and health consequences. This description is needed for an economic assessment of the problem. Investigations now follow a standardized procedure for each newly identified hazard, and from these investigations a national or international set of regulations are proposed, adjusted to optimize the protection and cost considerations, and put into place.

Regulation

Regulation is established at both the national and the international level, but for different reasons. The first reason is to protect the health of citizens, while the second is to protect the assets of traders and industries. Economics plays an important role in the development of regulations. A critically important consequence of such an economic analysis is the development of dual standards for commodities that are used for both animal feeds and human foods. The limits to contamination allowed in animal feeds usually are guided by acute toxicities, while the limits applied to humans are, in the case of carcinogens, driven by cumulative toxicities, and thus may be very low. There usually is a significant difference between the levels set for animals and those set for humans with consequences to knowledge and management strategy.

Management

Management comes into effect as soon as people find that they have a problem, i.e., that the mycotoxin is affecting their economic activity regardless of whether it is regulated. For example, if animals die or produce poorly, then farmers avoid the sources of contamination as soon as these sources are identified. As soon as there are market consequences, then the producers of a commodity usually respond with attempts to manage the problem that allow them to remain competitive and to continue selling their product. Management requirements usually are defined once research institutions identify the factors that are contributing to contamination and suggest ways to optimize the management response. For example, the water content range for aflatoxin production suggested that drying was essential in the American environment and has lead to the development of drying capacity for entire crops. Presently this capacity is located at buying points. Extension services and commercial laboratories are stakeholders from this phase of the process onwards as they, respectively, transfer research results to producers and monitor contamination.

Enforcement

Enforcement of regulations also requires that government institutions representing the consumer invest significantly in enforcement mechanisms, and that industries invest to minimize their risks in the given regulatory environment. Enforcement requires surveillance, laboratories, legal accountability and the people to implement them. The ability to enforce regulations is a feature of the mycotoxin management system that is a major challenge for most developing countries.

Toxicology

It is not the purpose of this chapter to detail the biochemical aspects of mycotoxin activity. However, some important toxicological concepts must be described as they condition how these toxins are perceived. Such perceptions help determine institutional interests and stakes. As in all toxicology the dose is critical and for aflatoxin three dose-related classes of intoxication can be defined.

Acute poisoning occurs when sufficient toxin has been ingested to cause the appearance of a set of characteristic symptoms, illness and/or death of the intoxicated person. For anatoxin the characteristic symptoms manifest as severe and acute hepatotoxicity, anorexia, malaise, low-grade fever, vomiting, abdominal pain, jaundice, hepatitis, and death. A high mortality rate is observed in people with these symptoms. However, humans are one of the more "tolerant" species with a high LD50 relative to that of many domesticated animals, and outbreaks of acute human aflatoxicosis are rare enough to be newsworthy when they are correctly diagnosed.

Chronic asymptomatic poisoning occurs when exposure to the toxin is insufficient to provoke the characteristic symptoms of acute exposure. Often, people suffering from this problem don't even know that they are being exposed to the toxin. The symptoms vary with the toxin, but for aflatoxin the consequences of sustained chronic exposure include immune suppression, nutritional interference, teratogenic effects, and cancer promotion through genetic mutations.

Cumulative poisoning results from damage, normally genetic, from repeated exposures that enhance the risks of adverse events, particularly cancer. For regulatory purposes, tolerable dosages generally are very low for toxins with cumulative or genetic toxicities.

Species differences and these basic forms of toxicity interact in determining regulations and managing toxins in food. Humans may be exposed to a toxin over a long period of time, so cumulative poisoning is a serious consideration. In contrast, farm animals usually are not fed for extended periods of time so the thresholds for regulation often are set at levels that ignore the cumulative form of toxicity, but avoid the acute toxicities that would cause immediate economic losses to those engaged in animal feeding operations.

Management models for mycotoxins

We also must understand the currently available models for managing mycotoxin contamination problems. Three main approaches exist with the management strategy usually dependent upon governmental responses to the contamination problem.

Denial/neglect

This response is common and may result from limited institutional capacity, perceptions of health priorities, and economic considerations. Developing country health systems do not need to look for reasons to justify their existence. Instead they usually are trying to address serious, immediate problems and have neither the time nor the resources to invest in or provide the most cost-effective long-term interventions. The food systems in these countries are not easily regulated and they usually lack the resources to enforce existing regulations. Consequently, a wide range of degrees of neglect exist and it is only when there are significant economic losses, or the health consequences are clear that action is taken. Kenya responded to the outbreak of acute aflatoxicosis in 2004 (CDC, 2004; Okioma, Chapter 11) and 2005, but earlier reports of market contamination were largely unheeded, e.g., Muriuki and Siboe (1995), since Kenya does not export these commodities. Denial also is a common response - particularly when the prevailing exposure occurs in the chronic range and other diagnoses, e.g., infectious diseases are possible. Even when toxins are shown to be a component of the food being consumed, the response may be that the food is a traditional product and has not "harmed" people previously. Governments may consider either that a myco-

toxin problem, if/when it is publicized, does not apply to their situation, or that it is an anomaly, outside of the normal set of events and not worthy of a response that will consume resources into the future. Many governments promulgate regulations and then neglect to provide the means to enforce them for obvious practical and economic reasons - it can be expensive to provide the services that quality assurance regulations demand. The challenge for science is to show that the cost of neglect is greater than the cost of enforcement.

Based on reported market food contamination, biomarkers for selected populations, and food system considerations (Williams et al., 2004), some 4.5 billion people living in developing countries probably live with uncontrolled exposure to aflatoxins.

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