(Reuters) — Neonicotinoids have been found in more than half of streams sampled across the United States, according to a new study by government researchers.
The insecticide treatments are under scrutiny by the White House because of fears about their impact on honeybees.
The study, published in Environmental Chemistry and conducted by U.S. Geological Survey researchers, found that five types of neonicotinoids were present in varying degrees in 149 samples taken from 48 streams.
At least one type was detected in 63 percent of the samples collected, researcher Michael Focazio said. The samples included many waterways through the Midwest and Southeast. Concentration levels varied.
Evidence has mounted over the last few years that links the use of neonics to widespread honeybee deaths. There are also fears the insecticides are harming other pollinators.
Neonicotinoids, which are chemically similar to nicotine, are one of the fastest growing classes of insecticides in the world.
The study represents the first national-scale investigation of the environmental occurrence of neonicotinoid insecticides in agricultural and urban settings, the government agency said. The research spanned 24 states as well as Puerto Rico.
“In the study, neonicotinoids occurred throughout the year in urban streams, while pulses of neonicotinoids were typical in agricultural streams during crop planting season,” said USGS research chemist Michelle Hladik, report’s lead author.
Neonics and their effect on the environment have been a topic of debate in Washington lately.
The U.S. Environmental Protection Agency proposed a rule in May that would create temporary pesticide-free zones to protect commercial honeybees, which pollinate plants that produce one-quarter of the food consumed by Americans.
Losses of managed honeybee colonies hit 42.1 percent from April 2014 through April 2015, up from 34.2 percent for 2013-2014 and the second-highest annual loss to date, according to the U.S. Department of Agriculture.
Beekeepers, environmental groups and some scientists say it is the neonics that are harming the bees.
Agrichemical companies disagree and instead blame mite infestations and other factors.