UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

 WASHINGTON, D.C. 20460

 OFFICE OF

CHEMICAL SAFETY AND

POLLUTION PREVENTION

Joint PMRA / USEPA

Re-evaluation Update for 

the Pollinator Risk 

Assessment of the 

Neonicotinoid Insecticides

6 January 2016
Page 1

Introduction

In May 2015, Health Canada’s Pest Management Regulatory Agency (PMRA) and the United 

States Environmental Protection Agency’s Office of Pesticide Programs (USEPA OPP) 

(Agencies) announced, as an initiative of the Regulatory Cooperation Council, that they would 

be collaborating on a bilateral pesticide re-evaluation process for the pollinator assessment of 

three neonicotinoid pesticides (clothianidin, imidacloprid, and thiamethoxam), based on the 

jointly developed harmonized Pollinator Risk Assessment Framework.

1 The Agencies have been 

working closely with the California Department of Pesticide Regulation (CDPR). In addition, 

USEPA OPP and CDPR are using the same framework to conduct a co-operative re-evaluation 

of dinotefuran, a neonicotinoid pesticide which is registered in the United States but not in 

Canada.

These pesticides are nitroguanidine neonicotinoids, a group of insecticides that have been 

approved for use in the United States and Canada for a number of years. In recent years, there 

have been reports in scientific literature suggesting that exposure to neonicotinoids may impact 

pollinator health; however, these studies have generally been conducted under laboratory 

situations, or in the field with exposure to doses that are higher than would normally be 

encountered in the environment. 

In support of science-based risk management decisions, the Agencies are relying on the 

harmonized Pollinator Risk Assessment Framework methodology to conduct the pollinator risk 

assessment for the neonicotinoids. The Framework relies on a tiered approach which begins with 

conservative exposure assumptions and laboratory toxicity data conducted with individual bees, 

then progresses to more realistic exposure measurements in nectar and pollen, as well as colony 

level bee studies conducted in the field.

Data required under the Framework has been divided into three tiers. Tier 1 consists of 

laboratory toxicity studies with both adult and larval honey bees exposed for acute and chronic 

durations. Tier 2 effects studies include feeding and tunnel studies in which honey bee hives are 

exposed to neonicotinoids in a more realistic setting than the laboratory. Tier 2 residue studies 

measure exposure based on pollen and nectar residue data from neonicotinoid products applied 

to crops using different application methods. Tier 3 studies are generally large-scale field studies 

that most closely resemble an in-field exposure scenario for honey bees. 

Neonicotinoid registrants have submitted, or are in the process of conducting, a number of

studies to support their chemical-specific pollinator risk assessments. The Agencies will use 

these studies as well as information from published literature in the tiered risk assessment 

approach. All relevant scientific information will be considered alongside incident data in a 

weight-of-evidence approach, which considers if the information is robust and consistent, for the 

risk characterization.

This document provides a status update on the pollinator risk assessments of clothianidin, 

imidacloprid, thiamethoxam, and dinotefuran.

 1 http://www2.epa.gov/sites/production/files/2014-06/documents/pollinator_risk_assessment_guidance_06_19_14.pdf
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Status of Registrant Data Submission and Review by the Agencies

Over 350 pollinator studies have been submitted by the neonicotinoid registrants and are 

currently undergoing a cooperative review by all three agencies. To date, over 300 of the studies 

received have been reviewed by at least one agency. While progress is being made with the study 

reviews, there are additional studies that are currently being conducted which are required for the 

completion of the re-evaluations.

Status of Open Literature Review

The Agencies will incorporate information from the body of peer-reviewed scientific literature 

into the pollinator risk assessments. Studies may include information about neonicotinoid 

residues in pollen/nectar as well as lethal and sublethal effects (foraging behavior, etc.) to 

different life stages (larvae, adults) in honey bee hives, and overall colony health. Studies on 

different types of bees (for example bumble bees and solitary bees) will also be included. 

The Agencies have conducted a number of literature searches which have identified hundreds of 

peer reviewed scientific studies. After a screen of the results, the Agencies prioritized about 250 

open literature studies for further evaluation based on whether they assessed the residues or 

effects described above. Studies which are considered to be informative will be incorporated into 

the pollinator risk assessment. The Agencies continue to monitor current research findings and 

will incorporate more recent information as it becomes available.

Next Steps

Since the Agencies began the imidacloprid review about a year before the other neonicotinoids, 

imidacloprid is further along in the review process and initial findings have been presented in 

preliminary pollinator risk assessment documents:

• Health Canada’s PMRA – Re-evaluation of Imidacloprid – Preliminary Pollinator 

Assessment

• USEPA – Preliminary Pollinator Assessment to Support the Registration Review of 

Imidacloprid

See table below for anticipated milestones for the pollinator assessments. The publication of each 

document will be followed by a public consultation period.

Neonicotinoid Assessment PMRA / USEPA/ 

CDPR1

Imidacloprid Preliminary Jan. 2016

Final Dec. 2016

Clothianidin Preliminary Dec. 2016

Final Dec. 2017

Thiamethoxam Preliminary Dec. 2016

Final Dec. 2017
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Neonicotinoid Assessment PMRA / USEPA/ 

CDPR1

Dinotefuran Preliminary Dec. 20162

Final Dec. 20172

1 CDPR plans to issue its determination with respect to its reevaluation of neonicotinoids (clothianidin, dinotefuran, 

imidacloprid, and thiamethoxam) on or before 1 July 2018. 2 Not Applicable to PMRA.

Additional Information

The issue of pollinator health is complex, and is likely influenced by a number of factors 

including pests, pathogens and viruses, nutrition, pesticide exposure, bee management practices, 

and lack of genetic diversity. The PMRA and USEPA OPP, as the federal regulators of 

pesticides in Canada and the United States, respectively, are working together to protect bees and 

other pollinators from pesticide exposure. 

Information regarding PMRA’s and USEPA OPP’s actions to protect pollinators and additional 

resources can be found at: 

Health Canada’s PMRA - www.healthcanada.gc.ca/pollinators

USEPA - http://www2.epa.gov/pollinator-protection