Tell the EPA Its Imidacloprid Assessment is Lacking in Key Areas

The EPA has released a preliminary pollinator risk assessment for a neonicotinoid insecticide called imidacloprid. This pesticide has been implicated in several major bee kill events in Oregon and elsewhere. Imidacloprid is sold as Admire, Gaucho, Merit and other trade names. In home and garden products, this active ingredient is often in products labeled “Systemic”. 

The EPA is soliciting public comment on its risk assessment until April 14, which examines risks of agricultural uses of imidacloprid to bees. The risk assessment makes no regulatory suggestions; those come later in the registration review process. However, assessment identifies a nectar residue level for imidacloprid of 25 ppb, above which the EPA believes that effects on pollinator hives are likely. These effects may include reduction in numbers of pollinators as well as the amount of honey produced.



NCAP is reviewing the assessment and recommends that supporters submit the following comments. More analysis and comments will be available in March at our website.

  1. Seven Hawaiian bees were proposed for listing under the Endangered Species Act in 2015. The EPA has committed to risk assessment procedures for endangered and threatened species recommended by the National Academy of Sciences.  Normally agencies analyze proposed species under the same guidelines. The document contains no evidence that the EPA has considered effects to the proposed Hawaiian bees. The EPA needs to fix this oversight.
  2. Mixtures that are commonly used and have been implicated in bee death incidents have not been explicitly accounted for in the assessment. Imidacloprid is very commonly applied with other pesticides, including fungicides, and these application and environmental mixtures need to be part of the analysis.
  3. It is important that the EPA quantify two exposure routes- surface water and dust. Given the huge amount of imidacloprid- treated corn and soybean seed in the Midwest, bees likely have a high potential to contact both surface water and dust containing imidacloprid residue.
  4. The EPA concluded that certain crops that are harvested before bloom time or are “unattractive” to honey bees do not pose an “on-field” risk to bees. Included in this list are fruiting vegetables– such as tomatoes. Tomatoes are well known for attracting bumblebees and should not be excluded from consideration based solely on their attraction to honey bees.
  5. A major gap in the risk assessment is that pollen residues have not been evaluated at the colony level. Although the EPA dismisses the likelihood that such evaluation would alter its risk conclusions, it does acknowledge that in certain crops, such as corn, pollen is the dominant route of exposure. Given the enormous number of acres planted of imidacloprid-treated corn, this is too large of a gap in the analysis.  
  6. The EPA recognized that soil residues of imidacloprid can and do build up (due to imidacloprid’s persistence) but then concluded that there is limited indication that accumulation of imidacloprid resides in soil translates to increased residues in pollen and nectar. It is not clear how they reached this conclusion, since they also stated that residues in cotton pollen nearly doubled and in corn, there did not appear to be a consistent increase or decrease in pollen residues in year 2 values relative to year 1. The reasoning is unclear and does not seem to be supported by the study.

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