Scientists Discover Widespread Insecticides Leach into Midwest Rivers

How widespread are insecticides? They're apparently leaching into our water supplies. Scientists have taken a closer look at neonicotinoid insecticides in the Midwestern United States and have found that they're present in our rivers.

Neonicotinoid insecticides are effective at killing a broad range of insect pests. This, in turn, has caused their use to increase dramatically over the last decade-especially across in the Midest.

"Neonicotinoid insecticides are receiving increased attention by scientists as we explore the possible links between pesticides, nutrition, infectious diseases and other stress factors in the environment possibly associated with honeybee dieoffs," said Kathryn Kuivila, research team leader, in a news release.

These insecticides actually dissolve easily in water, but don't break down in the environment. This means that they can easily be carried downstream from runoff in fields where they're used. That's why scientists decided to measure exactly how much were concentrated n rivers.

The scientists examined nine rivers and streams, including the Mississippi and Missouri Rivers.  The researchers found that clothianidin was the most commonly found chemical, showing up in 75 percent of the sites and at the highest concentration. Thiamethoxam was found at 47 percent of the sites and imidacloprid was found at 23 percent of the sites.

"We noticed higher levels of these insecticides after rain storms during crop planting, which is similar to the spring flushing of herbicides that has been documented in Midwestern U.S. rivers and streams," said Michelle Hladick, the lead author of the new report. "Inf act, the insecticides also were detected prior to their first use during the growing season, which indicates that they can persist from applications in prior years."

The findings are published in the journal Environmental Pollution.