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Introduction

This is the Environmental Protection Agency’s (EPA or the Agency) Final Work Plan (FWP) for 

the registration review of clothianidin. The FWP includes the expected registration review 

timeline. The FWP also addresses public comments received concerning the Preliminary Work 

Plan (PWP) in the Summary Document, which was posted in the clothianidin registration review 

docket (EPA-HQ-OPP-2011-0865), and any other comments concerning 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 and will review each registered 

pesticide every 15 years to determine whether it continues to meet the Federal Insecticide, 

Fungicide, and Rodenticide Act (FIFRA) standard for registration. Changes in science, public 

policy, and pesticide use practices occur over time. The registration review program is intended 

to make sure that, as the ability to assess risk evolves and as policies and practices change, all 

registered pesticides continue to meet the 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/.

Clothianidin is a broad-spectrum, systemic neonicotinoid insecticide registered for use to control 

chewing and sucking pests on a number of row and tree crops and turf. It is also registered for 

use in poultry houses and recreational and residential settings. Clothianidin induces paralysis 

and death in insects by enhancing nicotinic acetylcholine receptor activity. Clothianidin is a 

degradate of thiamethoxam that is also going through the registration review process (Case # 

7614). Products containing clothianidin were first registered in 2003 and, therefore, clothianidin 

was not subject to reregistration. 

Comments Received on and Changes Made Since the Preliminary Work Plan

On December 21, 2011 EPA opened a 60-day public comment period on the PWP for the 

registration review of clothianidin. During the public comment period the Agency received more 

than 120,000 comments. Most comments were the result of a letter writing campaign asking 

EPA to suspend the use of clothianidin. However, there were several comments on the use of 

clothianidin and some substantive comments from registrants and other stakeholders. 

Comments received did not result in a modification to the anticipated data needs or timeline 

detailed in the clothianidin PWP. However, there were three studies which were listed in error as 

required in the PWP and one study that was erroneously omitted from the PWP. The required 

data list in this FWP corrects these errors. For details see Table I at the end of this document.

On March 20, 2012, the EPA received an emergency citizen petition seeking suspension of 

registration for clothianidin. The petition requested action within 90 days. The agency is 

reviewing the petition and is in the process of responding to the petitioners' allegation that 

clothianidin poses an imminent hazard to pollinators. Many of the matters raised in the March 

20, 2012 petition were also received as comments during the 60 day comment period on the 

Preliminary Work Plan (PWP) for the Registration Review of Clothianidin. Comments received 
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on the PWP that are duplicated in the March 20, 2012 petition will only be responded to in the 

Agency’s responses to this petition. 

An overview of the comments and the Agency’s response is presented in the “Summary of 

Comments and Agency Responses” section of this document.

Risk Assessment and Data Needs

The Agency anticipates conducting a comprehensive ecological risk assessment, including an 

endangered species assessment, and a revised human health risk assessment for all uses of 

clothianidin. The following is a summary of the issues relevant to the registration review of 

clothianidin.

Ecological Risk:

• The most recent ecological risk assessment for clothianidin was completed in 2010 in 

support of the registration of clothianidin for use as seed treatments on mustard and 

cotton.

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

species determination for clothianidin. The ecological risk assessment planned during 

registration review will allow the Agency to determine whether clothianidin’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.

• On January 19, 2011, the Center for Biological Diversity and the Pesticide Action 

Network North America filed a lawsuit in the United States District Court for the 

Northern District of California, against the EPA for allegedly failing to undergo 

consultation with the United States Fish and Wildlife Service and the National Marine 

Fisheries Service regarding the effects of over 350 pesticides, including clothianidin, on 

over 200 endangered and threatened species throughout the United States (Center for 

Biological Diversity, et al. v. EPA, et al., No. C 11-00293 (N.D.Cal.).

• Previous risk assessments have assessed most major and minor degradates and the 

Agency concluded that they are expected to be as toxic or less toxic than parent 

clothianidin. Uncertainty regarding the clothianidin degradate thiazolylmethylguanidine 

(TMG) remain and the Agency will require data on this degradate to support registration 

review.

• The environmental fate and effects database is largely complete for clothianidin with the 

exception of effects data on avian and terrestrial invertebrate species. 
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• Based upon the current use pattern and the current available database on clothianidin, the 

Agency is requiring the following ecological fate and effects data for use in conducting a 

complete ecological risk assessment, including an endangered species assessment. 

GLN 850.2100 Acute avian oral toxicity for passerines

GLN 850.3040 Field testing for pollinators (TEP)

Non-Guideline Pollinator larval toxicity 

Non-Guideline Laboratory pollinator feeding study 

Non-Guideline Residues in pollen and nectar/field residue analysis 

study

Non-Guideline Chronic sediment toxicity test with midge larvae (with 

TGAI and the degradate TMG)

Non-Guideline Poultry litter residue study

835.7100 Prospective groundwater study

• To further evaluate risks to pollinators and other beneficial insects, EPA is requiring data 

to assess bees as a representative for all beneficial insects. In moving forward with 

addressing potential risk to these organisms, EPA will consider the recommendations of 

the Society of Environmental Toxicology and Chemistry (SETAC) Workshop on 

Pesticide Risk Assessment for Pollinators, and is working with its federal and state 

partners, industry, and academia to determine appropriate assessment methodology. For 

compounds, such as clothianidin, which (1) show acute toxicity to bees and (2) have 

exposure routes for bees, EPA will require toxicity and exposure studies to allow for 

evaluation of risks to pollinators. The registrant should consult with EPA on the conduct 

of these studies.

• The prospective groundwater study was included as a data gap in Registration Review: 

Problem Formulation for the Environmental Fate and Ecological Risk, Endangered 

Species, and Drinking Water Exposure Assessments of Clothianidin, dated December 13, 

2011, but was erroneously omitted from the PWP. The Agency will require this study to 

support registration review.

• Please refer to the document, Registration Review: Problem Formulation for the 

Environmental Fate and Ecological Risk, Endangered Species, and Drinking Water 

Exposure Assessments of Clothianidin, dated December 13, 2011, located in the docket 

for a detailed discussion of the anticipated risk assessment and data needs.

Human Health Risk:

• The most recent comprehensive human health risk assessment for clothianidin was 

completed in 2009 to support new use registrations on berries, Brassica vegetables, 
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cotton, cucurbits, fig, fruiting vegetables, leafy vegetables, peach, pomegranate, soybean, 

tree nuts, and tuberous and corm vegetables. 

• The Agency will require the following data for use in the registration review of

clothianidin:

GLN 870.3465 90 day inhalation toxicity

GLN 875.2100 Turf transferable residue study

Special Study Residue chemistry comparisons of different 

formulations on select commodities

• Side-by-side trials comparing residues from the WDG 

and SC formulations for leafy vegetables, Brassica

vegetables, non-bell peppers. Furthermore, HED 

determined that side-by-side trials were needed to 

demonstrate the effect of spray mix adjuvants on residue 

levels.

• Side-by-side trials comparing residues from foliar and 

soil applications to leaf lettuce, mustard greens, peppers, 

and cucumbers.

• For the human health risk assessment, the residue of concern for the dietary assessment 

(i.e., drinking water) is parent clothianidin. To support the registration review of 

clothianidin, the Agency will update the dietary risk assessment for clothianidin to 

incorporate any changes in policy.

• The Agency will conduct a new residential exposure assessment to incorporate changes 

in policy and to incorporate new data from the turf transferable residue study that is 

required.

• The Agency will calculate new aggregate risk estimates during this registration review to 

incorporate any revisions to dietary or residential exposure estimates.

• In addition to the dermal and oral hand-to-mouth residential exposure assessments,

residential bystander inhalation exposures resulting from off-site transport (e.g., spray 

drift or volatilization) may occur as a result of applications of clothianidin. The Agency 

is in the process of examining its policies and processes regarding assessment of these 

types of residential exposures. Therefore, the potential need for a bystander inhalation 

risk assessment for clothianidin will be examined during registration review.

• The Agency will update the occupational handler and post application risk assessment, 

especially for seed treatment uses, to incorporate changes in policy and new agricultural 

transfer coefficients.

• The tolerance expression for clothianidin will be reviewed during registration review to 

ensure that it appropriately covers the metabolites and degradates of clothianidin and that 

it specifies the residues to be measured for each commodity.
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• The Agency will modify tolerance levels as needed, and work to harmonize 

tolerances/maximum residue limits (MRL), where possible, in key export markets during 

registration review.

• Please refer to the document, Clothianidin. Human Health Assessment Scoping document 

in Support of Registration Review, dated December 8, 2011, located in the docket for a 

detailed discussion of the anticipated risk assessment and data needs for human health.

Timeline

EPA has created the following estimated timeline for the completion of the clothianidin

registration review.

Registration Review for Clothianidin – Projected Registration Review Timeline

Activities Estimated Date

Opening the Docket

Open Docket and Public Comment Period 2011 – December

Close Public Comment 2012 – February

Case Development

Final Work Plan 2012 – June

Issue DCI 2013 – Jan. – March

Data Submission 2016 – Jan. – March

Open Public Comment Period for Draft Risk Assessments 2017 – July – Sept.

Close Public Comment Period 2017 – Oct. – Dec.

Registration Review Decision

Open Public Comment Period for Proposed Registration Review 

Decision

2018 – Jan. – March

Close Public Comment Period 2018 – April – June

Registration Review Decision and Begin Post-Decision Follow-up 2018

Total (years) 7

Next Steps:

The Agency will require ecological effects and a human health studies through a data call-in 

(DCI), which is expected to be issued in early 2013. This new information will be used to 

conduct risk assessments for all registered uses of clothianidin.

Summary of Comments Received During Docket Opening

On December 21, 2011 EPA opened a 60-day public comment period on the PWP for the 

registration review of clothianidin. The comment period ended on February 21, 2012. Due to 

the quantity of comments received the Agency accepted comments until February 28, 2012. 

During the public comment period the Agency received more than 120,000 comments. 
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Comments received did not result in a modification to the anticipated data needs or timeline 

detailed in the clothianidin PWP.

The majority of the comments were received as a result of a letter writing campaign organized by 

Beyond Pesticides (BP) and Pesticide Action Network of North America (PANNA) voicing 

concern that clothianidin presents unacceptable risks to pollinators. The Agency received similar 

comments, i.e., concern over the risk to pollinators, from beekeepers, private citizens, the 

National Honey Bee Advisory Board (NHBAB), and the Rachel Carson Council. 

The Agency also received numerous comments in support of clothianidin from numerous grower

and commodity groups; seed manufacturers; and academics. The technical registrant Valent and 

the end use registrant Bayer CropScience provided comments regarding the Agency’s ecological 

risk assessment, the drinking water assessment, and on the anticipated data requirements 

discussed in the Clothianidin Preliminary Work Plan. Valent also commented on trade irritants 

and conditionally required magnitude of residue studies.

Finally, in the PWP, EPA solicited comments on three specific topics: environmental justice, 

water body impairments, and trade irritants. During the comment period the Agency received 

one comment on trade irritants and no comment on environmental justice and water body 

impairments.

Comments regarding the ecological fate or effects of clothianidin have been addressed by the 

Environmental Fate and Effects Division’s document, EFED Response to Comments Submitted 

to the Clothianidin Registration Review Docket (dated June 11, 2012). Comments regarding 

policy, process, and benefits have been addressed in, Clothianidin: PRD Response to Comments 

on Registration Review PWP (Dated June 20, 2012). Both documents are available in the docket 

(EPA-HQ-OPP-2011-0865).
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Data Requirements Table

The table below summarizes data requirement needs for clothianidin. For additional discussion 

of the data requirement needs, see the Registration Review: Problem Formulation for the 

Environmental Fate and Ecological Risk, Endangered Species, and Drinking Water Exposure 

Assessments of Clothianidin, dated December 13, 2011; and Clothianidin. Human Health 

Assessment Scoping document in Support of Registration Review, dated December 8, 2011.

*The prospective groundwater study was erroneously omitted from the PWP.

Table 1. Clothianidin Registration Review Data Requirements

Data Requirement Guideline 

Number

Listed In PWP Listed In FWP

90 day inhalation toxicity GLN 870.3465 Yes, these studies are listed in both the 

PWP and FWP. The Agency will issue a 

DCI for these studies.

Turf transferable residue study GLN 875.2100

Residue chemistry comparisons of different formulations on 

select commodities

• Side-by-side trials comparing residues from the WDG and 

SC formulations for leafy vegetables, Brassica vegetables, 

non-bell peppers. Furthermore, HED determined that 

side-by-side trials were needed to demonstrate the effect 

of spray mix adjuvants on residue levels.

• Side-by-side trials comparing residues from foliar and soil 

applications to leaf lettuce, mustard greens, peppers, and 

cucumbers.

Non-Guideline

Acute avian oral toxicity for passerines 850.2100

Field testing for pollinators (TEP) 850.3040

Pollinator larval toxicity Non-Guideline

Laboratory pollinator feeding study Non-Guideline

Residues in pollen and nectar/field residue analysis study Non-Guideline

Poultry litter residue study Non-Guideline

Chronic sediment toxicity test with midge larvae (with TGAI 

and the degradate TMG)

Non-Guideline

Prospective groundwater study* 835.7100 No Yes

Honey bee toxicity of residues on foliage (TEP) 850.3030 Yes No. The Agency is only 

interested in additional 

information from an 

existing alfalfa residue 

study.

Aquatic field dissipation (In Review) 835.6200 Yes No. If the study under 

review is found to be 

unacceptable, the Agency 

will make conservative 

assumptions.

Chronic sediment toxicity test with midge larvae (the 

degradate TZNG)

Non-Guideline Yes No. Chronic sediment 

toxicity testing with midge 

larvae on the degradate 

TZNG will not be 

required to support 

registration review.