WASHINGTON, Jan. 6, 2016 - A widely used neonicotinoid insecticide poses a risk to honey bees, EPA said in an analysis released today that drew criticism from a leading manufacturer of the product as well as environmental groups.

The neonic is imidacloprid, and EPA said that it “potentially poses risk to hives” when used on crops that attract pollinators. Citrus and cotton, in particular, appear to present a risk to honey bee hives and other pollinators, the agency said.

“Other crops such as corn and leafy vegetables either do not produce nectar or have residues below the EPA identified level” at which adverse effects were observed, EPA said in its news release.

But the preliminary risk assessment itself contained numerous caveats. It focused primarily on the best known and most economically important species, the Western honey bee (Apis mellifera) and said more study was needed to fully evaluate the effects of imidacloprid on all pollinators.

The assessment is the first of four EPA will conduct on neonicotinoids. The public will have an opportunity to comment for 60 days once a Federal Register notice is published.

Preliminary assessments for clothianidin, thiamethoxam and dinotefuran are scheduled to be released for public comment in December 2016. A preliminary risk assessment of all ecological effects for imidacloprid, including a revised pollinator assessment and impacts on other species such as aquatic and terrestrial animals and plants, will also be released in December 2016, EPA said.

Although EPA estimated thresholds above which adverse effects on honey bees could be expected, its assessment also said that risks of imidacloprid to other species of bees – bumble bees, for example – “may differ . . . due to differences in their exposure and sensitivity to imidacloprid. Therefore, uncertainty exists in extrapolating the risk findings of this assessment.”

Bayer CropScience, a major manufacturer and registrant of imidacloprid, responded quickly: “We will review the EPA document, but at first glance it appears to overestimate the potential for harmful exposures in certain crops, such as citrus and cotton, while ignoring the important benefits these products provide and management practices to protect bees. We hope the final risk assessment is based on the best available science, as well as a proper understanding of modern pest management practices.”

The Center for Biological Diversity (CBD) which has sued EPA to force it to conduct assessments of pesticide risks, said the analysis was flawed in numerous ways.

“EPA focused solely on one bee species, ignoring the 4,000 native (bee species) in North America,” CBD Environmental Health Director Lori Ann Burd said in an email. “It glossed over the fact that effects on individual bees were found for most crops. And rather than considering the many published bee colony studies, this risk assessment relied on a single study submitted by the pesticide registrant.”

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The assessment said that “although there were other evaluated colony studies conducted with colonies of Apis mellifera, only this study was considered acceptable for quantitative use in this risk assessment.” It also said that “a robust registrant-submitted dataset was available to characterize the acute and chronic toxicity of imidacloprid to (individual) adult and larval honey bees.”

EPA also said that it worked with Health Canada’s Pest Management Regulatory Agency and California’s Department of Pesticide Regulation to evaluate more than 75 studies investigating the toxic effects on Apis and non-Apis bees at the individual and colony level.


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