The U.S. Environmental Protection Agency has weighed in on the debate over a class of insecticide called neonicotinoids, issuing a preliminary assessment that found that the chemical can pose a health threat to honeybees in some instances.
The preliminary report issued last week found that a type of neonicotinoid called imidacloprid leaves a residue on some crops that attract pollinating insects, such as cotton and citrus plants, that exceeds safe levels for bee colonies. For other crops, such as corn and leafy vegetables, there was no evidence that imidacloprid posed a risk.
Both critics that consider neonicotinoids toxic to bees as well as the companies that produce and sell the chemicals singled out portions of the 300-page report that they contend buttresses their positions.
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Neonic producers contend that, when properly used, the chemicals aren’t responsible for the alarming mortality rate of bee colonies.
Environmental groups and pesticide makers have tussled for years about the effects of neonics on bees. The European Union temporarily suspended many uses of three neonics in 2013 because of concerns about their impact on bee health.
Studies have shown that bee colonies suffer from a cascade of factors, including pests, diseases and fungal infections, extreme weather and other problems. But environmental groups contend neonics are a major culprit.
The EPA’s preliminary risk assessment – the first of four that it plans to issue – focused only on imidacloprid. Releasing the assessment triggered a 60-day public comment period, after which the EPA could revise its finding and then take any action it deems necessary.
Last year the EPA proposed prohibiting using neonics when crops are in bloom and bees are brought in to pollinate them.
Friends of the Earth, an environmental group based in Washington, issued a statement saying the report shows that “the EPA needs to stop dragging its feet and take decisive action to suspend these bee-toxic pesticides.”
Bayer, which has nearly 900 Triangle employees, invented imidacloprid and today is one of several producers of the chemical.
David Fischer, director of pollinatory safety at Bayer, said the EPA assessed about 35 uses of the chemical but “in only three of those uses did they conclude there was a risk for bees.”
That means, he added, that in 90 percent of the uses they assessed, “they couldn’t identify a risk.” In addition, Fischer said, the EPA assessment “errs on the side of overestimating the risk.”
Bayer contends that imidacloprid can still be used safely on the crops where the agency identified problems by limiting how and when it is sprayed.
Bayer also is encouraged that the EPA found that the level of imidacloprid residue needed to be above 25 parts per billion to pose a risk to bees. Imidacloprid leaves a residue “in the low single digits” when used as a seed coating and the residue is “generally less than 20 parts per billion” when it is used to treat soil, Fischer said.
Syngenta, which doesn’t produce imidacloprid, said in a statement that although it is still reviewing EPA’s assessment, “we did note the agency’s finding that treated seeds do not appear to harm bees.”
“Neonicotinoids are an essential crop protection tool for farmers and when used according to the product label, also safe for the environment,” said Syngenta, which has 375 employees in RTP.
An association of citrus growers, California Citrus Mutual, criticized the EPA study, noting that the citrus industry is seriously threatened by an incurable disease, commonly called citrus greening.
Neonics “are a vital tool in the battle to save the citrus industry,” the organization’s president, Joel Nelsen, said in a statement.
But Friends of the Earth contends that the report “reinforces the strong body of independent science demonstrating that neonicotinoids are a leading driver of bee declines.”
Aimee Code, pesticide director for The Xerces Society for Invertebrate Conservation in Oregon, said the EPA underestimated the risk of imidacloprid because, among other things, it focuses only on honeybees.
Honeybees, she said, are much more resilient than native bees such as bumblebees. Honeybees were originally imported from Europe and are managed by beekeepers.
“Imidacloprid is definitely part of the problem for our bees, and EPA failed to look at many of the risks,” she said.
Dennis vanEngelsdorp, an entomologist at the University of Maryland, said he was encouraged that the EPA assessment “is following the science pretty closely. It does represent our current state of knowledge as it pertains to honeybee health. I think there is little question that other non-honeybee bees may be more impacted than honeybees are.”