“Given the rates of corn planting and talc usage, we are blowing large amounts of contaminated talc into the environment. The dust is quite light and appears to be quite mobile,” Krupke said. Krupke said the corn pollen that bees were bringing back to hives later in the year tested positive for neonicotinoids at levels roughly below 100 parts per billion.
“That’s enough to kill bees if sufficient amounts are consumed, but it is not acutely toxic,” he said.
On the other hand, the exhausted talc showed extremely high levels of the insecticides – up to about 700,000 times the lethal contact dose for a bee.
“Whatever was on the seed was being exhausted into the environment,” Krupke said. “This material is so concentrated that even small amounts landing on flowering plants around a field can kill foragers or be transported to the hive in contaminated pollen. This might be why we found these insecticides in pollen that the bees had collected and brought back to their hives.”