IARC scientific publications最新文献

This chapter provides information about the chemical and physical properties of the mycotoxins considered in this book: aflatoxins; fumonisins; ochratoxin A; trichothecenes, especially deoxynivalenol and nivalenol; zearalenone; and ergot alkaloids. This information about structures reveals the chemical diversity of mycotoxins, which is relevant to the wide range of toxicological effects in animals and humans discussed later in the book.

The economic impacts of mycotoxins to human society can be thought of in two ways: (i) the direct market costs associated with lost trade or reduced revenues due to contaminated food or feed, and (ii) the human health losses from adverse effects associated with mycotoxin consumption. Losses related to markets occur within systems in which mycotoxins are being monitored in the food and feed supply. Food that has mycotoxin levels above a particular maximum allowable level is either rejected outright for sale or sold at a lower price for a different use. Such transactions can take place at local levels or at the level of trade among countries. Sometimes this can result in heavy economic losses for food producers, but the benefit of such monitoring systems is a lower risk of mycotoxins in the food supply. Losses related to health occur when mycotoxins are present in food at levels that can cause illness. In developed countries, such losses are often measured in terms of cost of illness; around the world, such losses are more frequently measured in terms of disability-adjusted life years (DALYs). It is also useful to assess the economics of interventions to reduce mycotoxins and their attendant health effects; the relative effectiveness of public health interventions can be assessed by estimating quality-adjusted life years (QALYs) associated with each intervention. Cost-effectiveness assessment can be conducted to compare the cost of implementing the intervention with the resulting benefits, in terms of either improved markets or improved human health. Aside from cost-effectiveness, however, it is also important to assess the technical feasibility of interventions, particularly in low-income countries, where funds and infrastructures are limited.

The analytical methods for mycotoxin determination used in fully developed countries require sophisticated infrastructure, stable electricity, ready availability of supplies, and qualified and experienced technicians for instrument maintenance. Simple and appropriately validated tools analogous to those used for the management of contaminated bulk commodities at the grain elevator level are needed at the rural level in developing countries. These tools are needed to promote public health and to manage emergency situations in subsistence farming communities with an immediate and severe problem of mycotoxin contamination of food grains, with the goal of working towards feasible reductions in exposure. Two general analytical approaches that require less infrastructure are described here. The first approach is thin-layer chromatography (TLC), which has been used for more than 50 years to analyse mycotoxins. The advantages of TLC include simplicity and proven reliability. Accuracy may be improved by using precision spotters to apply precise amounts of sample to TLC plates and optical readers. The costs of these refinements to TLC are far lower than those of gas or liquid chromatography systems. The disadvantages of TLC include the need for stable supplies of solvents and standards as well as safe conditions for their storage. The second approach described here is based on immunological methods using anti-mycotoxin antibodies. These tests are available as kits, have the necessary standards built in, use little or no organic solvent, and are generally easy to use. The disadvantages of these methods include the need to refrigerate the kits before use and the limited shelf-life. It has been proposed that companies and development agencies could be solicited to develop packages of kits, sampling equipment (e.g. grinders), and training models for deployment in the many areas where mycotoxins are a chronic problem.

Sample variation is often the largest error in determining concentrations of mycotoxins in food commodities. The worldwide safety evaluation of mycotoxins requires sampling plans that give acceptably accurate values for the levels of contamination in specific batches or lots of a commodity. Mycotoxin concentrations show a skewed or uneven distribution in foods and feeds, especially in whole kernels (or nuts), so it is extremely difficult to collect a sample that accurately represents the mean batch concentration. Sample variance studies and sampling plans have been published for select mycotoxins such as aflatoxin, fumonisin, and deoxynivalenol, emphasizing the importance of sample selection, sample size, and the number of incremental samples. For meaningful data to be generated from surveillance studies, representative samples should be collected from carefully selected populations (batches or lots) of food that, in turn, should be representative of clearly defined locations (e.g. a country, a region within a country). Although sampling variability is unavoidable, it is essential that the precision of the sampling plan be clearly defined and be considered acceptable by those responsible for interpreting and reporting the surveillance data. The factors influencing variability are detailed here, with reference to both major mycotoxins and major commodities. Sampling of large bag stacks, bulk shipments, and domestic supplies are all discussed. Sampling plans currently accepted in international trade are outlined. Acceptance sampling plans and the variabilities that affect operating characteristic curves of such plans are also detailed. The constraints and issues related to the sampling of harvested crops within subsistence farming areas are also discussed in this chapter, as are the essential rules of sample labelling and storage. The chapter concludes with a short section on sample preparation methods.