Ensley said Iowa officials recently started testing for aflatoxin in milk from Iowa dairies; other Midwest states are already feeling the heat.
"There have been (corn) loads in southern Illinois, and northern parts of Missouri with high contamination levels.... A lot [is] getting rejected by grain buyers,” said Allen Wrather, a professor of Plant Sciences at the University of Missouri's College of Agriculture, Food and Natural Resources.
The Missouri Department of Agriculture has found aflatoxin at levels over 20 parts per billion – the legal limit for corn intended for humans or dairy cattle – in 58 percent of samples so far this season. Last season, only 8 percent of the crop was above that mark.
The Illinois Department of Agriculture already had 56 corn samples this season test for aflatoxin over the 20 ppb threshold There were only six samples over that limit in all of 2011.
While carcinogenic to humans, aflatoxin is also toxic to many animals.
"Pigs and cows can handle it a little bit better," Wrather said. But it will kill chicken, cats and dogs if it gets into their food, he added.
The U.S. Department of Agriculture regulates aflatoxin and sets strict contamination limits. Corn destined for humans and dairy cattle has the 20 ppb limit, whereas corn for beef cattle can contain concentrations up to 300 ppb.
But Heiniger said the desperate times are causing desperate measures in his state.
"There's a lack of grain on the market, and, therefore, a lack of vigilance on testing grain by grain buyers," he said. "I'm seeing a lot of grain that would be rejected in a normal year being bought to blend with other grain or be ground up to mitigate the toxic compounds in it."
The true impact of aflatoxin will be known in a few weeks, Parrish said. So far only 39 percent of the U.S. corn crop has been harvested, according to U.S. Department of Agriculture.
Climate scientists warn that these problems won't soon disappear. This year's drought has shown little sign of slacking, and climate modelers expect more of the same: This year's extreme weather may be closer to the future norm, scientists say.
"In the Midwest, as you go ... toward the south and west – places like Missouri, Iowa, Kansas and Nebraska – the future looks warmer and drier," said Jeff Andresen, an assistant professor at Michigan State University who specializes in applied climatology. These, he added, are "not very optimistic predictions for agriculture."
Parrish, of the American Farm Bureau Federation, is optimistic farmers can mitigate drought-stressed crops and excess nitrate runoff.
But for many farmers, the year has been a bust. The nitrate and aflatoxin worries pile onto a growing season already marred with low production. Through September, the Corn Belt was still "slightly" or "abnormally" dry in most areas, according to the USDA. Compared to 2011, corn and soybean yields are down 13 and 14 percent, respectively.
This article originally appeared at The Daily Climate, the climate change news source published by Environmental Health Sciences, a nonprofit media company.