Farmers in northwestern Iowa and southeastern South Dakota have found aflatoxin in recently harvested corn. Both areas suffered high temperatures and a drought this summer, which favor the development of the toxin. The mold can cause cancer in humans if consumed in large amounts.
“With several parts of the Midwest having gone through a scorching summer, more farmers in the Corn Belt may find aflatoxin,” said Don White, professor of crop sciences at the University of Illinois. “We've had the environment for it and I would think there are going to be scattered pockets,” he added.
The extension office in Plymouth County, Iowa, has received 20 to 25 reports from farmers, with levels mostly between 20 and 100 parts per billion. “The highest level found was 600 parts per billion,” said Joel DeJong, extension field agronomist.
The U.S. Food and Drug Administration limits aflatoxin for food or animal feed to 20 parts per billion. Countries importing U.S. corn often demand even lower limits.
Aflatoxin is a byproduct of a fungus that grows on corn, peanuts and other crops. Consuming aflatoxin in large amounts can cause liver cancer in humans or kill animals. In 2005, the FDA found that 76 dogs died after eating Diamond Pet Food made at the company's Gaston, South Carolina, plant.
“The Farmers Cooperative Co, which has three grain elevators in northwest Iowa, has rejected about 25 to 30 percent of the corn brought in for having more than 20 parts per billion of aflatoxin,” said general manager Roger Price. "The fact that it's on everyone's radar screen is very positive."
The last time aflatoxin was found in the Iowa corn crop was in 2005, when it affected the southeast corner of the state. "It was probably more widespread in 2005 than it is this year," said Charles Hurburgh, professor of agriculture at Iowa State. The toxin-producing fungus, Aspergillus flavus, thrives in hot days and nights with temperatures near 90 degrees Fahrenheit (32 degrees Celsius).