A toxin called a neonicotinoid is commonly found in agricultural insecticides and has been turning up consistently in the Midwest, according to an article in the Star Tribune. With results published this week, the article said scientists at the U.S. Geological Survey found the compound in six states and nine Midwestern rivers,

The synthetic nicotine neurotoxin has been an increasingly popular form of insecticide for farmer. This rose concerns about possible threats to insects, that are the foundation of the aquatic food chain ecosystem, the article reported. Another study last month in Holland found a great decline in birds wherever this insecticide was widely used.

With enough rain transporting the toxin over land or tile drains, the Star Tribune said, it could easily find its way to streams which would mean higher concentrations.

Though this nuance is raising concern for some, manufacturers of the compound say that neonicotinoids provide success for farmers and that there is no evidence to prove its harmful effect on the environment. However, the article reported that recent studies have found that the toxins may play a big part in the decline of honeybees, other pollinating insects and wildlife.

The Star Tribune points out that the compounds are most commonly used as seed treatment for corn, soybeans and other cash crops.  Because neonicotinoids are water-soluble, as they plants grow, they become part of the plant’s vascular system. The large majority of the toxin remains in the soil, the article said, but a small amount is absorbed into the plant.

The EPA considers compounds as toxic at much higher levels than those found in the USGS samples, but other studies have found that toxicity levels are different for other species. At this point it is not clear what impact the toxins will have on the aquatic ecosystem, the article said.