Breaking the mold: new strategies for fighting aflatoxins.

Abstract

In 2010 Kenyan authorities reported that 2.3 million bags of corn harvested in that country had been contaminated with fungal poisons known as aflatoxins.1 These toxins—which include aflatoxin B1, the most potent naturally occurring liver carcinogen ever identified—are produced by Aspergillus flavus and A. parasiticus, and they infect corn (maize), nuts, and other crops, especially during periods of drought stress and intense heat. Aflatoxins have been implicated in poisoning outbreaks that killed hundreds of people in developing countries, and experts suspect many aflatoxin-related fatalities go unreported.2 Toxicity risks from aflatoxins are very low in the United States and other developed countries, according to Charles Hurburgh, a professor of agricultural engineering and an extension grain specialist at Iowa State University. People in these countries eat a wide variety of foods with little or no risk of aflatoxin contamination, and for those foods where aflatoxins may occur, contamination is closely monitored and tightly regulated. However, chronic exposures are endemic in developing countries, because aflatoxin monitoring is inadequate, populations tend to rely heavily on just a few staple crops that are vulnerable to Aspergillus infection, and growing conditions often favor mold growth. In a recent analysis of data from the National Health and Nutrition Examination Survey, only 1.3% of more than 2,000 U.S. blood samples had detectible levels of aflatoxins,3 compared with 78% of more than 3,000 blood serum samples from the nationally representative Kenya AIDS Indicator Survey.4 The U.S. Centers for Disease Control and Prevention estimates that 4.5 billion people in the developing world may have chronic exposure to aflatoxins in the diet.5 And according to one analysis, these exposures account for between 25,200 and 155,000 cases of liver cancer every year, particularly in Asia and sub-Saharan Africa.6 Now aflatoxins are drawing international attention from development groups and aid agencies, who are teaching farmers and buyers how to spot and combat the pervasive threat.