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Corn-based human foodstuffs from retail outlets in five countries were analyzed for fumonisin Bi (FBi) and fumonisin B2 (FB2). The highest mean concentrations occurred in two Egyptian samples (2380 ng/g FBi and 595 ng/g FB2). Only one of four Peruvian samples contained 660 ng/g FBi and 68 ng/g FB2, while only one of two Canadian samples contained a detectable level of FBi. The 16 cornmeal (CM) and 10 corn grits (CG) products from the United States contained mean concentrations of 1048 ng/g FBi and 298 ng/g FB2 and 601 ng/g FBi and 375 ng/g FB2, respectively, while the mean concentrations in 52 CM and 18 CG samples from South Africa were 138 ng/g FBi and 83 ng/g FB2 and 125 ng/g FBi and 85 ng/g FB2, respectively. Only 1 of 10 cornflakes/lime-treated samples contained a low level of FBi. Of several samples obtained from a high esophageal cancer (EC) risk area in the United States 7/7 contained FBi ng/g) and 6/7 FB2 (70-460 ng/g).

As part of a comprehensive risk assessment study for fumonisins, reliable data on exposure of populations to these dietary toxins must be obtained. To assess the extent of worldwide exposure, the published literature on the contamination of food and feed supplies has been reviewed and supplemented with unpublished material from various international sources. Fumonisin contamination of corn and corn-based products occurs in many countries. Animal mycotoxicoses such as equine leukoencephalomalacia and porcine pulmonary edema are caused by heavily contaminated animal feeds. For example, as much as 330 μg/g fumonisin B1 (FB1) has been found in swine feed. Although commercially available refined corn products for human consumption are generally contaminated at levels below 1 μg/g FB1, individual products in certain countries can reach far higher levels. Health risks associated with consumption of these products depend on the extent to which they are consumed in a varied diet. Home-grown corn in certain rural areas, where it also constitutes the staple diet, can be contaminated at >100 μg/g. Consumption of corn contaminated at these high levels has: been associated with a high incidence of esophageal cancer in these areas.

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.