Problems with the toxic residue of a mold that attacked the 2012 drought-hit U.S. corn crop may worsen this summer and autumn as Midwest farmers blend off tainted supplies held in storage, grain experts say.
The substance, aflatoxin, is a chronic problem in dry, hot southern states like Texas where stressed crops are vulnerable to the mold. But in 2012, the worst U.S. drought in more than half a century extended the aflatoxin threat moved northward into the heart of the Midwest, resulting in the biggest outbreak since the 1980s.
"As we get into summer, you are going to see the worst of it," said Doug Bartlett, co-owner of Midwest Farm Services, an advisory service in Higginsville, Missouri. "We have tight corn supplies and when we get down to the nitty gritty, there is going to be a lot of the aflatoxin left over, and it will have to be blended off into the new crop," he said.
Aflatoxin can sicken humans and animals if ingested and is carcinogenic. So corn users - from pet food and livestock feed makers to vegoil and sweetener producers - test for it, and reject tainted supplies.
Ethanol makers, which consume 40 percent of U.S. corn output, can be even more picky because the aflatoxins concentrate during the distilling process, contaminating dried distillers' grains, a valuable ethanol byproduct sold for feed.
Months after the harvest, aflatoxin continues to cause headaches along the corn supply chain.
"From eastern Kansas across northern Missouri and up into central and southern Illinois - there is an area there that has significant aflatoxin issues," said Charles Hurburgh, an agricultural engineering professor at Iowa State University who specializes in grain quality.
TAINTED CORN BLENDED INTO FEED
Most of the contaminated corn is now being blended into feed for hogs and beef cattle, large animals that can tolerate low levels of aflatoxin.
Under guidelines from the U.S. Food and Drug Administration, certain types of feed can contain an aflatoxin concentration of up to 300 parts per billion. Human foods must contain less than 20 ppb, while the threshold for milk is even lower, at 0.5 ppb.
For the export market, outbound U.S. corn must also test at less than 20 ppb.
Cows that eat tainted corn can pass on aflatoxin through their milk. Dairy processors in the St. Louis area have had to dump loads of milk found to contain elevated levels of aflatoxin, said Max Hawkins, a nutritionist with Alltech, a Kentucky-based feed supplement company.