Survey of Aflatoxin and Fumonisin Contamination from Different Grain Sources in Costa Rica.

Aflatoxins and fumonisins are fungal secondary metabolites produced by Aspergillus spp. and Fusarium spp., respectively. These mycotoxins are toxic for humans and animals and maximum permitted levels have been established in many countries for both food and feed. In Costa Rica, total aflatoxin limits are 20 ug kg^-1 for all cereals and legumes, and 15 ug kg^-1 for peanuts, while for fumonisins, there currently does not exist a maximum permitted level. Futhermore, mycotoxin analyses are performed only on imported agricultural commodities like maize, wheat and rice, meaning that little is known about the potential impact of local sources of commodity grains in terms of mycotoxin risk. Therefore, the objective of this survey was to determine the level of contamination with aflatoxins and fumonisins for samples of rice (Oryza sativa), black beans (Phaseolus vulgaris), red beans, maize (Zea mays), and peanuts (Arachis hypogea) collected from different local sources, including, farmers fields, supermarkets, cooperatives, and farmers markets. Initial samples were obtained from the provinces of Alajuela and Heredia, and a total 86 samples were analyzed for total aflatoxins (B₁+B₂+G₁+G₂) and total fumonisins (B₁+B₂+B₃) with a fluorometric method using immunoaffinity columns Aflatest® and Fumonitest®. Highest aflatoxin contamination levels were 32 ug kg^-1, 6.7 ug kg^-1, 4.9 ug kg^-1and 2.8 ug kg^-1 for white maize, rice, peanut and red beans, respectively. For total fumonisins, the highest values were 6.9 mg kg^-1, 4.8 mg kg^-1, 4.5 mg kg^-1 and 4.1 mg kg^-1 for black beans, peanut, white maize and, black beans, respectively. These preliminary results indicate that some crops may be at greater risk for mycotoxin contamination. A second survey is currently being conducted to corroborate and expand on preliminary results.