Aflatoxin Contamination of Different Grains in Costa Rica.

Aflatoxins are fungal secondary metabolites produced by Aspergillus flavus and A. parasiticus. Aflatoxins are toxic for humans and animals and are classified as carcinogenic by the International Agency for Research on Cancer (IARC). In Costa Rica, a maximum limit of 20 ug kg^-1 of total aflatoxins has been established for cereals, oilseeds and legumes, and a limit of 15 ug kg^-1 for peanut. The Mycotoxin Laboratory at CIGRAS works in coordination with the Costa Rican State Phytosanitary Service (SFE) to monitor aflatoxin levels in imported agricultural commodities, as well as with the food processing industry that requires aflatoxin monitoring to assure quality control. The objective of this work was to summarize results for aflatoxin testing conducted in the Mycotoxin Laboratory during the past 12 years of monitoring. For samples received during the period 2003 to early 2010, these were analyzed with method AACC 45-15 (confirmation with TLC), while for those samples received starting from June 2010 until December 2015, these were analyzed with a fluorometric method and Aflatest[Symbol] immunoaffinity columns (AOAC  991.31 items A-G). Over the 12-year period, a total of 5298 samples were analyzed for total aflatoxins (B₁+B₂+G₁+G₂). Rice (Oryza sativa) (43 %) was the most frequently tested grain, followed by yellow maize (Zea mays) (15 %), peanut (Arachis hypogaea) (11 %), and white maize (8 %). Highest aflatoxin incidence and contamination levels were observed in red beans (Phaseolus vulgaris), followed by white maize, and peanuts. In spite of having few samples tested, results for P. vulgaris were very interesting since aflatoxins are not considered to be a serious problem in beans. These results indicate the need to further research the mechanisms related to how and when beans can be affected by Aspergillus spp.