Bergeson & Campbell, P.C.

EPA Releases Preliminary Risk Assessment for Neonicotinoid Insecticide Imidacloprid

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Courtesy of Courtesy of Bergeson & Campbell, P.C.

On January 6, 2016, the U.S. Environmental Protection Agency (EPA), in collaboration with California’s Department of Pesticide Regulation (DPR) announced the release of a preliminary pollinator risk assessment for the neonicotinoid insecticide, imidacloprid (Preliminary Risk Assessment or Assessment). In its assessment, EPA states that imidacloprid potentially poses a risk to hives when the pesticide comes in contact with certain crops that attract pollinators.

EPA coordinated efforts with Canada’s Pest Management Regulatory Agency (PRMA). PMRA simultaneously released the overview and science evaluation of its imidacloprid pollinator-only assessment, which reaches the same preliminary conclusions as set forth in EPA’s Assessment. PMRA plans to release the complete assessment with appendices as a revised version on January 18, 2016, and to accept written comments until March 18, 2016.

EPA’s Preliminary Risk Assessment will be subject to a 60-day comment period commencing on the announcement of the Assessment in the Federal Register. EPA did not indicate how long it will be before the Federal Register notice is issued.

This Assessment is the first of four such assessments that will be prepared in 2016 under President Obama’s National Pollinator Strategy. The other three assessments, for neonicotinoid insecticides clothianidin, thiamethoxam, and dinotefuran, are scheduled to be released for public comment in December 2016. EPA also states that following the receipt of public comments on this Assessment by December 2016, it plans to issue a revised Preliminary Ecological Risk Assessment that will: “(i) consider any comments or information submitted in response to this bee-only preliminary risk assessment; (ii) incorporate additional data EPA anticipates to receive that is relevant to bees; and, (iii) assess the potential risks of all registered uses of imidacloprid to all taxa.”

EPA’s Preliminary Risk Assessment describes how EPA conducted a screening level assessment (Tier I) for the various uses of imidacloprid, with a stepwise, tiered risk assessment approach evaluating risks to individual bees first and, if needed, risks to the colony. EPA has divided its risk findings for honey bees for the registered use patterns of imidacloprid into three categories: (1) Crop Groups/Use Patterns that Present Low On-Field Risk; (2) Crop Groups/Use Patterns with Uncertainty in Colony (Tier II) Assessment; and (3) Crop Groups/Use Patterns with Colony (Tier II) Risk Indicated, with this last category including “Citrus Fruits (Oranges)” and “Oilseed (Cotton).” EPA further states: “ased on a tri-agency analysis of the statistical and biological considerations of the data, a NOAEC and LOAEC of 25 and 50 μg a.i./L in nectar were determined based on reductions of the number of adult workers, numbers of pupae, pollen stores and honey stores which persisted across much of the study duration. The level of imidacloprid in nectar at or below which no effects would be expected to the colony is determined to be 25 μg a.i./L.”

Additional information regarding EPA’s actions regarding neonicotinoid insecticides and the National Pollinator Strategy can be found on our blog. EPA stated its intent to hold a webinar regarding the imidacloprid Preliminary Risk Assessment in early February 2016. More information can be found on EPA’s website.


EPA’s statements about the assessment have indicated that imidacloprid uses on citrus and cotton are of greatest concern. Not included in this assessment is what, if any, specific regulatory actions might be needed to reduce any risks to an acceptable level. Regardless, the registrants, along with other stakeholders, will almost certainly comment on the assessment (likely to say that the risks are both overestimated, according to the registrants, and underestimated, according to environmental groups).

What may be of less notice is what EPA appears to conclude about the other uses of the pesticide. Not long ago, many claimed that significant honeybee decline was due to planting crops, especially corn, with neonicotinoid seed treatments such as imidacloprid. This assessment appears to contradict that assertion (along with other improvements that have been made in reducing fugitive dust exposures during application). And, even if EPA is correct in its assessment that the citrus and cotton uses are of concern, there are many other uses of imidacloprid currently suspended from the market in the European Union (EU) -- where cotton and citrus are not widely produced. This EPA assessment might become part of the debate about the rationale behind the current EU policies.

The documents released today are long (the assessment is 305 pages with an appendix of 212 pages). That EPA plans to complete its assessment within this calendar year indicates that current EPA leaders want any decision to be issued (or at least be framed) before the arrival of any new Administration. That alone will cause some to question the degree to which any actions are based more on “science and data” or on the “politics” of pollinator protection.

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