Scientists from the U.S. Geological Survey found neonicotinoid insecticides in 74 percent of the water samples they analyzed from 10 major tributaries of the Great Lakes. The insecticides were “detected in every month sampled and five of the six target neonicotinoids were detected.” Environmental Health News says the study “suggests the Great Lakes’ fish, birds and entire ecosystems might be at risk” from the insecticides that are believed to be a factor in high mortality rates of honeybees.
“Neonicotinoid concentrations generally increased in spring through summer, coinciding with the planting of neonicotinoid-treated seeds and broadcast applications of neonicotinoids,” said the USGS. The study was published in the journal Environmental Pollution. Two of the neonicotinoids, clothianidin and thiamethoxam, were most common in agricultural watersheds. Another, imidacloprid, was more often found in urbanized areas. “Three neonicotinoids were ubiquitously detected in all water samples collected within this basin”
An environmental group, Midwest Pesticide Action Center, said sunlight was supposed to break down the insecticides, “yet, this study shows persistence in the environment long after applications.”
Environmental Health News said, “The chemicals are linked to bee die-offs … There’s also nascent evidence the chemicals may directly hurt aquatic wildlife — from tiny organisms to fish — with potential to disrupt entire ecosystems.” The lead author of the USGS study said levels of the insecticides in the river water were relatively low, but in some of the rivers they exceed the EPA threshold for part of the year.