Last year’s drought increased the spread of a carcinogenic mold called aspergillus (Aspergillus flavus), a fungal pathogen that poisons cattle, kills pets and has infected the 2012 corn crop, rendering significant portions of the harvest unfit for consumption.
Whereas the deadly organism mainly affects countries like China and developing African nations, many U.S. states have experienced an increase in corn contamination since 2011. Farmers are likely to see more of the carcinogen as temperatures continue to rise and droughts become more frequent.
“It's really a climate variable issue,” says Barbara Stinson, founding and senior partner of Meridian Institute, a public policy organization. “We're probably looking at an increase in aflatoxin as a result of that.”
A. flavus releases toxic spores that can be fatal when ingested, prompting symptoms that include jaundice, liver cancer and internal bleeding. The poison is so deadly that in 1995 Iraqi dictator Saddam Hussein confessed to weaponizing the mold spores for use in biological warfare. The high toxicity of the mold means crops with more than 20 parts per billion—the equivalent of about 100 kernels in a truckload of corn—can’t cross state lines, says Ronnie Heiniger, professor of cropping systems at North Carolina State University.
That’s bad news for the agricultural industry, which suffers annual losses of more than $190 million due to aspergillus. Last year the green-black mold contaminated more than half the corn harvested in Missouri by October. In contrast, only 8 percent of the 2011 crop suffered, according to the Missouri Grain Inspection Service.
“We have a big aflatoxin problem,” says Charles Woloshuk, a botanist and plant pathologist at Purdue University. “There are loads of corn coming to the [grain] elevators that have been rejected.”
Grains like corn and cereals are well documented hosts of aspergillus, although the fungus is also found in oilseed, spices, tree nuts, groundnuts, milk, meat and dried fruit—all staples on which a significant portion of the world’s population rely for sustenance. Drought conditions don’t cause the mold, but they do help speed its expansion. Unlike the fuzzy stuff that grows on bathroom tiles or in the back of the garage, A. flavus prefers hot, dry climes—precisely like the drought afflicting more than half the U.S.
Although the international community has adopted strict legislation to regulate the acceptable amount of aflatoxin for individual countries, cases of poisoning, called aflatoxicosis, still surface regularly. Because the level of aflatoxins found in any given load of corn can be higher than the legal maximum, farmers are allowed to mix contaminated corn with safe corn to dilute the amount—but sometimes contaminants slip through the cracks.
“That's always the problem with a contaminant at these low levels—the distribution of that contaminant in that load,” Heiniger says. “The detection of these contaminants is almost more of an art than a science because you're searching for this one little kernel.” He adds, “If you selected one bite from that whole area and happened to hit that one kernel you'd get the contaminant.”
Aflatoxin contamination is a global food security issue, but it’s especially a problem in developing countries, which are often largely populated by subsistence farmers who don’t have the resources, technology or infrastructure needed for adequate grain testing. Lack of education about the effects of the mold also contributes to aflatoxicosis poisoning.
“The average person can’t tell whether the mold contains aflatoxin. You can’t tell if it’s highly toxic or an innocuous fungus,” Stinson says. “So people are used to eating it and don’t know that they’re poisoning themselves or their children.”