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Summary of Meeting with Pyrethroid Work Group

To Discuss Pyrethroid Ecological Risk Assessment

March 4, 2013

Attendees

Pyrethroid Work Group (PWG): 

Dave Haughey (BASF Corporation)

Annette Bloomberg (Bayer CropScience)

Michael Dobbs (Bayer CropScience)

Ann Orth (FMC Corporation)

Richard Allen (Valent BioSciences)

Dick Collier (Landis International)

Robert Morris (FMC Corporation, via Teleconference)

Gary Mitchell (FMC Corporation, via Teleconference)

Jeff Giddings (Compliance Services International, via Teleconference)

Alex Porges (Landis International, via Teleconference)

Paul Hendley (Phasera Limited, via Teleconference)

Environmental Protection Agency (EPA or Agency): 

Environmental Fate and Effects Division

Don Brady 

Mah Shamim

James Wolf

Melissa Panger

Reuben Baris

Steve Wente

Rosanna Louie-Juzwiak

Dana Spatz

Jose Melendez (via teleconference)

Keith Sappington (via teleconference)

Donna Judkins (via teleconference)

Pesticide Re-evaluation Division

Rick Keigwin 

Patty Parrott 

Monica Wait

Molly Clayton

Tracy Perry

Purpose

The purpose of the meeting was for the PWG to meet with members of the EPA’s Pesticide Reevaluation Division (PRD) and the Environmental Fate and Effects Division (EFED) to discuss 

PWG’s plans for conducting “unified” pyrethroid risk assessments, including an explanation of 

what a unified approach entails, progress to date, and other information PWG may be able to 
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provide to EPA to inform the ecological risk assessments for the pyrethroid class of insecticides

that EPA will be conducting during registration review.

Presentation

PWG’s presentation covered:

 Concept for a unified higher tier pyrethroid ecological assessment 

 Current status of PWG risk assessment 

 Proposal to collaborate with EPA through future meetings 

Discussion

Explanation of Unified Approach

PWG explains that it is proposing conducting nine separate, higher tier risk assessments for the 

active ingredients (ai’s) represented by the PWG (bifenthrin, cyfluthrins, cypermethrin, 

cyahalothrins, deltamethrin, esfenvalerate, fenpropathrin, permethrin, tefluthrin, and zetacypermethrin), unified by a common approach to risk assessment and management, i.e., 

employing the same assessment methodologies for each and implementing similar 

mitigation/label changes as necessary.

EPA Feedback

EPA currently employs a consistent approach in its ecological risk assessments, particularly in 

assessments conducted for various ai’s within a chemical class such as the pyrethroids. 

Based on this meeting and previous conversations, EPA believes PWG’s approach is similar to a 

pyrethroid ecological risk assessment conducted by industry and considered by a Scientific 

Advisory Panel (SAP) in 1999. The 1999 assessment employed a probabilistic landscape 

analysis, which the SAP found to be flawed. The landscape approach used a Mississippi 

watershed for cotton, and concluded from modeling this scenario that drift from pyrethroid 

applications does not reach water bodies. This conclusion was based on the topography of the 

Mississippi site, and on the local distance from fields to water bodies. This Mississippi 

watershed cannot be extrapolated to the entire U.S. Furthermore, PWG’s modeling can not 

negate the large amount of monitoring data collected by California and others which does show 

that pyrethroids reach water bodies. 

In 2000, EFED provided extensive comments on this risk assessment methodology, and EPA is 

unclear if or how those comments will be addressed in the new pyrethroid risk assessments 

proposed by the PWG. EPA asks PWG to submit a brief paper describing the PWG’s planned 

approach, and to the extent that it is similar to the approaches previously considered by EPA and 

the SAP, PWG should address the previous comments. EPA does not advise PWG to expend 

resources pursuing a new pyrethroid risk assessment which is based on similar methodology to 

that which was previously found to be deficient. 
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Any drastic change to EPA’s risk assessment methodology would need to undergo extensive 

peer review, and EPA must consider the timeframe allowed for pyrethroid risk assessments

during registration review. Therefore, EPA anticipates conducting risk assessments for all 

pyrethroid active ingredients following the Agency’s standard policies and procedures. Rather 

than conducting alternative assessments, PWG may be able to provide other information, such as 

monitoring data and use information, which could potentially help inform the Agency’s 

ecological pyrethroid risk assessments.

Additional Information Requested by EPA

EPA requests that PWG continue to submit the following: data generated on runoff from 

impervious surfaces, California monitoring data, and additional data from other PWG studies 

that have been submitted to California Department of Pesticide Regulation (CDPR). 

EPA requests crop and urban use pattern information, specifically information that is generally 

not included on product labels. This includes non-agricultural label application rates (maximum 

single application rate, number of applications per year, retreatment intervals, etc.) with the 

understanding that ambiguous use instructions on labels may necessitate that the Agency make 

conservative assumptions in its upcoming registration review ecological risk assessments.

PWG indicated during the meeting it will soon initiate a survey to determine urban outdoor use 

patterns (Kline survey). The survey will focus on typical use patterns around the country, 

including worst case scenario outdoor uses. PWG requested EPA input on the proposed survey

prior to initiation. The survey would take approximately one month to conduct. EPA agrees to 

review survey design. 

Action Items

PWG will prepare a white paper describing the unified risk assessment approach, including the 

basic concepts, proposals, and progress, by end of April 2013. PWG will address EPA’s 

comments on previous, similar risk assessments.

PWG will perform a review of current pyrethroid end use product labels to determine actual and 

intended use patterns.

PWG will continue to submit data it has generated on runoff from impervious surfaces, 

California monitoring data, and additional data from other PWG studies that have been submitted 

to CDPR.

PWG will submit to EPA its plans for the urban outdoor use pattern survey by end of April 2013.

Next Steps

EPA and PWG will schedule another meeting to discuss PWG’s plans for unified assessments 

once the white paper describing the assessments has been submitted and EPA has completed its 

review. If PWG submits the white paper in April, this meeting could take place in early June.
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EPA plans to complete the first of the planned pyrethroid ecological risk assessments for 

registration review in 2015 and post them for public comment in the docket.