Fortified by Global Warming, Deadly Fungus Poisons Corn Crops, Causes Cancer

A carcinogenic mold, its growth exacerbated by the warming climate, reached record highs in 2012















Image: Ewok Jorduman/Flickr

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.”



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  1. 1. sault 01:21 PM 1/15/13

    To all those deniers that keep harping on how much we DON'T know about climate change: Yeah, we don't know everything, but that doesn't stop frightening surprises like this aflatoxin mold from popping up! How can YOU be so sure we won't face a string of unforseen consequences like this mold as the climate warms? How come you cherry-pick and goad over uncertainties in climate science (both real and imagined) yet are SO SURE that we have nothing to worry about as we increase CO2 concentrations by 40% with no sign of slowing down?

    Look, this is just another cost to bear for burning millions of years of buried carbon. If you run your society on fossils, expect to become one soon.

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  2. 2. Sisko in reply to sault 03:21 PM 1/15/13

    Sault-

    are you ready to claim that the same thing would not have occured if there had been less CO2 in the atmosphere? Would there have been more or less severe weather?

    Answer- you and nobody else knows, but that does not stop the propaganda like claims of harms.

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  3. 3. Crasher in reply to Sisko 04:52 PM 1/15/13

    Sisko, if you are such an expert that you know more than all the real scientists why are you not at the IPCC meeting in Tasmania. Surely they need an 'expert' such as yourself.
    You would be laughed from the floor.
    I think the words 'dunning kruger' come to mind.

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  4. 4. BruceWMorlan 08:33 PM 1/15/13

    First I must say, THIS IS NOT A DISCUSSION ABOUT GLOBAL WARMING.

    But, the statement that this is "... 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." begs the question, are small CSA and home growers such as are usually distributing through farmer's markets and road side stands able to adequately detect and react to this mold?

    And the second question is whether this is a safe feedstock for ethanol plants, or would this possibly turn the effluent from ethanol plants into a toxic plume?

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  5. 5. BruceWMorlan 08:35 PM 1/15/13

    And a second question ... can the big seed distributors guarantee their seeds and be held responsible if they are not careful? (A due diligence question)

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  6. 6. greenhome123 08:59 PM 1/15/13

    I believe I have developed an increased sensitivity to aflatoxin do to eating so many nuts, figs, and chocolate over the past few years (all of which can contain aflatoxin). I believe that contaminated nuts taste like a bad nut, moldy, and stale, and also will make your tongue tingly a bit and a little numb feeling. I have had to throw away a lot of nuts lately cause they have obviously been contaminated. These nuts include almonds, brazil nuts, peanuts, cashews, walnuts, and pecans. One way to test is with a UV light. The mold will glow bright greenish blue. but the aflatoxin itself doesn't glow...only the mold that produces it, so that isn't a sure way. I think the US should lower the acceptable levels to 5 parts per billion and do a better job at checking for it cause they are letting a lot slip by right now.

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