Date: December 22, 2010 

MEMORANDUM 

SUBJECT: Reclassification of MRID 46907801/46907802 Data Package 336888 for 

Clothianidin, PC Code 044309 

TO: 

FROM: 

THRU: 

Kable Davis, Risk Manager Reviewer 

Venus Eagle, Risk Manager, RM 01 

Insecticide Branch 

Registration Division (7505P) 

Anita Pease, Senior Biologist X45- 11-111/1° 

Environmental Risk Branch 6 Environmental Fate and Effects Division (7507P) 

Mark Corbin, Branch Chief 

Environmental Risk Branch 6 

Environmental Fate and Effects Division (7507P) 

12,11-10 

The purpose of this memorandum is to transmit the Environmental Fate and Effects Division's 

(EFED's) final Data Evaluation Record (DER) for the study entitled, "An Investigation of the 

Potential Long-Term Impact of Clothianidin Seed Treated Canola on Honey Bees, Apis mellifera 

L." (MRID 46907801/46907802) and provide a brief history of activities related to the 

reclassification of this study. 

This field study was originally reviewed by EFED in November 2007 and classified as 

"Acceptable". A subsequent re-review of the study was conducted in November 2010 as part of 

a new use assessment for clothianidin seed treatment on mustard seed and cotton. EFED 

scientists routinely reevaluate studies to determine whether the information submitted is valid 

and if it is relevant or useful to the regulatory matter in question. In the case of the clothianidin 

honeybee field study, the study was reconsidered based on an increased understanding and 

awareness of the potential uncertainties normally encountered in field studies with honeybees. 

Based on the initial re-review, which occurred on November 2, 2010, the study was thought to be 

"Invalid"; however, it was later reclassified, on December 3, 2010, as "Supplemental". The 

study was initially reclassified as "Invalid" based on clothianidin contamination of controls. 
In this field study, control and treated plots were each 1 hectare in size and paired, so that 4 sites 

were established with a formulation control plot paired with a clothianidin-treated plot. These 

plots were separated by a minimum of 250 m. The major source of uncertainty is the ability of 

this study to discriminate treatment-related effects because clothianidin residues were detected in 

nectar from formulation control colonies. In addition, no negative control was reported to 

determine if there were statistically significant effects due to the formulation (actives plus inerts 

minus clothianidin). The presence of clothianidin residues in albeit a limited number of control 

hive nectar samples at concentrations similar to those detected in nectar from colonies placed in 

treated fields suggests that at least some workers from control colonies foraged on clothianidintreated canola. According to the study authors, the minimum distance between the treated and 

control fields was 250 m and was likely insufficient to prevent cross-foraging of bees between 

treated and control fields. In addition to the close proximity of treated and control fields, control 

bees may have foraged in clothianidin-treated fields because the forage in some of the control 

fields was of lower quality due to insect damage and reduced emergence of canola. Likewise, the 

extent to which bees in treated fields may have availed themselves to untreated canola is 

uncertain given the close proximity of the control fields. Additionally, the study did not 

adequately evaluate the exposure bees to canola via pollen identification analysis. Additional 

confounding factors associated with overall colony health included the loss of queens from 11 colonies, including three colonies that were classified as "dead" part way through the study and 

not included in "some" of the statistical analysis. Finally, raw data were not provided in the 

study to conduct a statistical reanalysis of the study results 

Based on the confounding factors associated with potential clothianidin cross-contamination of 

nectar from control hives and the lack of a negative control, the results of the investigation of the 

potential long-term impact of clothianidin seed-treated canola on honeybees are not adequate for 

use in risk assessment. Under the conditions tested, the study indicates that clothianidin residues 

were brought back to the bee colonies in nectar and pollen and were found in comb honey as well; residues were not detected in comb wax though. The study addendum on the assessment of 

overwintering colonies provides useful information on the subsequent effects of bee colonies in 

the year following exposure at measured residue concentrations. In summary, this field toxicity 

study with honeybees (OPP Gdln. No. 141-5; OPPTS 850.3040) is classified as "supplemental". 
1 OPPIN Classifications: 

Acceptable/Guideline; Acceptable/Non-Guideline; Cited; Confirmatory; Decision Deferred; Extraneous 

submission; In Review; No Decision; Partially Acceptable; Supplemental; Unacceptable/Guideline; 

Unacceptable/Non-Guideline; Upgradeable.