U.S. scientists found neonicotinoid insecticides in about three-quarters of samples from 10 major Great Lakes tributaries.
The study is the first to examine the insecticides—gaining notoriety in recent years as a prime suspect in bee die-offs— in the world’s largest freshwater system and suggests Great Lakes’ fish, birds and entire ecosystems might be at risk.
“This study is one of many that shows we know very little about the repercussive effects of pesticides once released into the environment,” said Ruth Kerzee, executive director of the Midwest Pesticide Action Center, who was not involved in the study. “We are told these compounds break down rapidly when exposed to sunlight and, yet, this study shows persistence in the environment long after applications.”
The study comes as draft legislation is circulating in Congress that would remove requirements that the U.S. Environmental Protection Agency consult with the U.S. Fish and Wildlife Department and the National Marine Service over pesticides’ impact on threatened and endangered species.
Neonicotinoids are the most heavily used insecticides on the planet—designed to attack the nervous systems of insects and protect crops from damage. Once thought to be relatively innocuous to wildlife higher up the food chain, scientists are increasingly reporting toxic effects.
The chemicals are linked to bee die-offs. Last summer a major study in Science reported bees near cornfields exposed to neonicotinoids for a few months via pollen suffered from decreased survival and poor immune systems. In birds, exposure to the chemicals has been linked to population declines.