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Introduction:

This document amends the Final Work Plan (FWP) for the registration review of imidacloprid. 

Since the publication of the June 2009 Final Work Plan for the registration review of 

imidacloprid, the Agency has identified additional data necessary to support the registration 

review of imidacloprid. This document amends the June 2009 Imidacloprid FWP to include the 

revised ecological data requirements and the revised registration review schedule to account for 

the additional data requirements. Unless otherwise stated in this amendment, all other elements 

of the Agency’s 2009 Imidacloprid FWP remain unchanged. Rationales for the additional data 

requirements can be found in the document entitled “Imidacloprid: Amended Data 

Requirements for Registration Review” (D378465). This document as well as other supporting 

documents can be found in the imidacloprid docket (EPA-HQ-OPP-2008-0844) at 

http://www.regulations.gov. 

The Agency is implementing the Registration Review program, pursuant to FIFRA section 3(g), 

and will review each registered pesticide every 15 years to determine whether it continues to 

meet the FIFRA standard for registration. Changes in science, public policy, and pesticide use 

practices will occur over time. The registration review program is intended to make sure that, as 

the ability to assess risk evolves as policies and practices change, all registered pesticides 

continue to meet that statutory standard. The public phase of registration review begins when the 

initial docket is opened for each case. Information on this program is provided at: 

http://www.epa.gov/oppsrrd1/registration_review/. 

Imidacloprid is a systemic neonicotinoid nitroguanidine insecticide used on food crops, 

ornamentals, turf, seed treatments, domestic pets, and structural pests. Imidacloprid’s mode of 

toxic action is the disruption of the nervous system by acting as an inhibitor at nicotinic 

acetylcholine receptors. It was first registered for use in 1994, and as a result was not reviewed 

under the reregistration process. 

Changes to the Ecological Data Needs:

Following additional review of available imidacloprid data, the Agency has concluded that it 

lacks adequate exposure data to estimate potential risk to terrestrial invertebrates. Imidacloprid 

is a systemic insecticide that is taken up by a plant’s roots, and translocated throughout plant 

tissues resulting in residue concentrations in different plant tissues. The Agency does not have 

adequate data to understand the potential exposure of imidacloprid to terrestrial invertebrates that 

may be exposed to imidacloprid through reliance on plant flower parts for habitat or diet. In 

addition to the ecological, fate, and human health data requirements identified in the June 2009 

FWP for imidacloprid, the Agency will also require the following exposure data to support 

registration review: 
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• Field Residue Test (Special Study): Imidacloprid residues in Leaves and/or Nectar and/or 

Pollen (2 Years) in the following crops: 

Crop Matrices

o Citrus Leaves, Nectar, and Pollen 

o Blueberry Leaves, Nectar, and Pollen 

o Stone Fruit (Apples or Cherries) Leaves, Nectar, and Pollen 

o Cotton Leaves and Nectar 

o Corn Leaves and Pollen 

Revised Timeline:

To accommodate the additional 2-year field studies, the Agency will adopt the amended schedule 

for the registration review of imidacloprid as outlined below. 

Revised Registration Review Schedule for Imidacloprid 

Activities Estimated Month/Year 

Phase 1: Opening the Docket 

Open Public Comment Period for Imidacloprid Docket Completed 2008– Dec. 

Close Public Comment Period Completed 2009– Mar. 

Phase 2: Case Development 

Final Work Plan (FWP) Completed 2009– Jun. 

Amend FWP 2010– Jul. 

Issue DCI 2010– Aug. 

Data Submission 2013– Jul.-Aug. 

Preliminary Risk Assessment & Public Comment 2015– Jan.-Mar. 

Close Public Comment Period 2015– Apr.-Jun. 

Phase 3: Registration Review Decision 

Open Public Comment Period for Proposed Reg. Review Decision 2015– Jul.-Sep. 

Close Public Comment Period 2015– Oct. – Dec. 

Final Decision and Begin Post-Decision Follow-up 2016– Jan-Mar. 

Total 8 years 

 

Introduction:

This is EPA’s Final Work Plan (FWP) for the registration review of imidacloprid. The FWP 

includes the expected registration review time line. The FWP also addresses public comments 

received concerning the Preliminary Work Plan (PWP) in the Summary Document which was 

posted in the initial registration review docket (EPA-HQ-OPP-2008-0844), and any other 

comments on the initial docket postings. The Summary Document provided information on what 

EPA knows about the pesticide and what additional risk analyses and data or information the 

Agency believes are needed to make a registration review decision. 

The Agency is implementing the Registration Review program, pursuant to FIFRA section 3(g), 

and will review each registered pesticide every 15 years to determine whether it continues to 

meet the FIFRA standard for registration. Changes in science, public policy, and pesticide use 

practices will occur over time. The registration review program is intended to make sure that, as 

the ability to assess risk evolves as policies and practices change, all registered pesticides 

continue to meet that statutory standard. The public phase of registration review begins when the 

initial docket is opened for each case. Information on this program is provided at: 

http://www.epa.gov/oppsrrd1/registration_review/. 

Imidacloprid is systemic neonicotinoid nitroguanidine insecticide used on food crops, 

ornamentals, turf, seed treatments, domestic pets, and structural pests. Imidacloprid’s mode of 

toxic action is the disruption of the nervous system by acting as an inhibitor at nicotinic 

acetylcholine receptors. It was first registered for use in 1994, and as a result was not reviewed 

under the reregistration process. 

Comments Received on Preliminary Work Plan:

The imidacloprid registration review docket received more than 12,000 comments during the 90-

day public comment period, which began on December 17, 2008. The Agency believes that the 

comments received do not change the data and risk assessment needs or the timeline detailed in 

the Imidacloprid PWP. An overview of comments is presented in the “Summary of Comments 

and Agency Responses” section of this document. A more detailed description of the comments 

received and the Agency’s response to these comments is available in the separate response 

memoranda from the Agency’s Environmental Fate and Effects Division (EFED), Health Effects 

Division (HED), and Special Review and Reregistration Division (SRRD) located in the 

imidacloprid docket (EPA-HQ-OPP-2008-0844). 

Risk Assessment and Data Needs:

Ecological Risk:

• The most recent risk assessment for all registered uses was conducted in October 2007. 

That assessment did not include a complete endangered species determination for 

imidacloprid. 

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• The Agency has not conducted a risk assessment that supports a complete endangered 

species determination. The ecological risk assessment planned during registration review 

will allow the Agency to determine whether imidacloprid’s use has “no effect” or “may 

affect” federally listed threatened or endangered species (listed species) or their 

designated critical habitats. When an assessment concludes that a pesticide's use “may 

affect” a listed species or its designated critical habitat, the Agency will consult with the 

U.S. Fish and Wildlife Service and/or National Marine Fisheries Service (the Services), 

as. Appropriate. 

• Please refer to the November 13, 2008 document, EFED Preliminary Problem 

Formulation for the Registration Review of Imidacloprid in the registration review docket 

(Document ID EPA-HQ-OPP-2008-0844-003), for a detailed discussion of the 

anticipated ecological risk assessment needs. 

• The Agency intends to issue a data call-in in early 2010 to require the following data on 

imidacloprid to complete these assessments: 

o (GLN 835.4300) Aerobic aquatic soil metabolism study using TGAI 

imidacloprid. 

o (GLN 850.3040) Field test for pollinators using TEP imidacloprid. 

o (Special Study) Repeat dose field study for pollinators. 

o (GLN 850.4100) Tier 1 seedling emergence study (Tier 1) using TEP 

imidacloprid. 

o (GLN 850.4150 ) Tier 1 vegetative vigor study using TEP imidacloprid. 

o (GLN 850.4400) Tier 1 aquatic plant growth study using TGAI imidacloprid. 

o (Special Study) Seed leaching study using TEP imidacloprid. 

Human Health Risk:

• The most recent risk assessment for all uses was conducted in May 2007, and reflects 

current registrations and uses of imidacloprid, current FQPA policies, and addresses 

susceptibility of infants and children and aggregate exposures. Anticipated new toxicity 

and residential exposure data may require revisions to the dietary risk assessment and 

residential exposure assessment. A new occupational risk assessment and a companion 

animal risk assessment, which includes an analysis of pet incidents, will be required to 

support registration review. 

• Please refer to the December 3, 2008 document, Imidacloprid. Human Health Assessment 

Scoping Document in Support of Registration Review in the registration review docket 

(Document ID EPA-HQ-OPP-2008-0844-004), for a detailed discussion of the 

anticipated human health risk assessment needs. 

• The Agency intends to issue a data call-in in early 2010 to require the following data to 

support registration review: 

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o (GLN 870.7800) Immunotoxicity study using TGAI. 

o (Special Study) Post-application wood wipe and leaching study 

Timeline:

Activities Estimated Month/Year 

Phase 1: Opening the Docket 

Open Public Comment Period for Imidacloprid Docket Completed 2008– Dec. 

Close Public Comment Period Completed 2009– Mar. 

Phase 2: Case Development 

Final Work Plan (FWP) Completed 2009– Jun. 

Issue DCI 2010– Jan.-Mar. 

Data Submission 2012– Jan.-Mar. 

Preliminary Risk Assessment & Public Comment 2013– Jul.-Sep. 

Close Public Comment Period 2013– Oct.-Dec. 

Phase 3: Registration Review Decision 

Open Public Comment Period for Proposed Reg. Review Decision 2014– Jan.-Mar. 

Close Public Comment Period 2014– Apr.-Jun 

Final Decision and Begin Post-Decision Follow-up 2014– Jul-Sep. 

Total 6 years 

Summary of Comments Received During Docket Opening:

During the public comment period, the Agency received over 12,000 comments. The majority of 

those comments were received as a result of a letter writing campaign organized by Natural 

Resources Defense Council (NRDC) voicing concern that imidacloprid presents unacceptable 

risks to pollinators. The Agency received similar comments, i.e., concern over the risk to 

pollinators, from private citizens, honey beekeeper interests represented by the National Honey 

Bee Advisory Board (NHBAB), and environmental advocacy groups like Beyond Pesticides, 

NRDC, and Sierra Club. Some commenters cited open literature or provided anecdotal 

information on the effect of imidacloprid on bees. Other comments were received offering 

suggestions on how the Agency could collect data or manage the risk of imidacloprid to bees. 

Few comments were received regarding the risks presented by imidacloprid either to wildlife 

species other than pollinators or to humans. 

The Agency also received numerous comments in support of imidacloprid from growers; 

agricultural interest groups including the National Cotton Council, National Potato Council, 

National Sunflower Association, and the Northwest Horticulture Council; residential pest control 

users; and academics. The technical registrant provided comments regarding the Agency’s risk 

assessment and on the anticipated data requirements discussed in the Imidacloprid Preliminary 

Work Plan. 

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Finally, in the Preliminary Work Plan, EPA solicited comments on three specific topics: 

environmental justice, water body impairment, and trade irritants. During the comment period 

the Agency received one comment regarding water body impairments, one comment regarding 

trade irritants, and no comments regarding environmental justice. 

Comments relevant to human health have been addressed by the Health Effects Division’s 

document, Response to Comments on Human-Health Assessment Scoping Document in Support 

of Registration Review (dated May 5, 2009). Comments regarding the ecological fate or effects 

of imidacloprid have been addressed by the Environmental Fate and Effects Division’s 

document, Imidacloprid: EFED Response to Comments on Registration Review PWP (dated 

June 27, 2009). Comments regarding policy and process have been addressed in Special Review 

and Reregistration Division’s document, Imidacloprid: SRRD Response to Comments on 

Registration Review PWP (Dated June 30, 2009). All three documents are available in the 

docket (EPA-HQ-OPP-2008-0844). 

Next Steps

The Agency plans to develop a Data Call-In Notice for this pesticide and expects to issue it in 

January, 2010. 

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