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THIFENSULFURON METHYL AMENDED FINAL WORK PLAN 

Introduction:

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

for the registration review of thifensulfuron methyl. This document amends the September 

2011 Thifensulfuron methyl Final Work Plan (FWP) to remove data requirements previously 

included in the summary of data gaps. Unless otherwise stated in this amendment, all other 

elements of the Agency’s 2011 Thifensulfuron methyl FWP remain unchanged. 

Changes to Ecological Data Needs:

The Registration Review - Preliminary Problem Formulation for the Ecological Risk Assessment 

of Thifensulfuron methyl was completed on March 10, 2011. The data needs listed in the 

problem formulation were amended by the memorandum EFED update on Data Needs for 

Thifensulfuron (PC code 128845) Associated with the Registration Review DCI Issuance, dated 

December 8, 2011. 

Given the structural similarity of thiefensulfuron methyl degradates IN-L9225, IN-L9226, and 

IN-JZ789 to parent thifensulfuron methyl, the Agency will consider these degradates to be of 

equal toxicity to the parent compound. In addition, structural analysis suggests that degradates 

IN-V7160, IN-L9223, and IN-A4098 will not likely retain phytotoxic properties. Therefore, the 

Agency has determined that studies for the thifensulfuron methyl degradates are no longer 

needed. 

The Agency has completed its review of the study and supplemental information (MRIDs 

48043101 and 48043102) submitted to fulfill GDLN 835.4300 Aerobic Aquatic Metabolism. 

While this study is classified as supplemental and does not entirely fulfill the guideline 

requirements, the Agency believes that the existing fate data are sufficient to conduct a 

comprehensive ecological risk assessment. Therefore, no additional data are needed to satisfy 

this requirement for thifensulfuron methyl. 

For GDLN 850.2100, Avian Acute Oral Toxicity Test (passerine species), the Agency has 

determined that the low application rate of thifensulfuron methyl and low toxicity to other avian 

species tested indicate that risk to passerine species is unlikely to exceed levels of concern and, 

therefore, the study is no longer needed. 

To summarize, the Agency has removed the following ecological data requirements from the list 

of data needs for thifensulfuron methyl specified in the Final Work Plan: 

o GDLN 850.2100 Avian Acute Oral Toxicity Test (parent, passerine species)

o GDLN 850.4100 Seedling Emergence Test, Tier II (degradates IN-A4098, INJZ789, IN-L9223, IN-L9225, IN-L9226, and IN-V7160) 

o GDLN 850.4150 Vegetative Vigor Test, Tier II (degradate IN-L9223) 

o GDLN 835.4300 Aerobic Aquatic Metabolism 
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o GDLN 850.4400 Plant Toxicity Test with Lemna spp, Tier II (degradates INA4098, IN-JZ789, IN-L9223, IN-L9225, IN-L9226, and IN-V7160) 

All other environmental fate and ecological effects data requirements remain as listed in the 

September 29, 2011 FWP. 

Summary of Data Gaps – Thifensulfuron methyl 

The table below summarizes the data needs for thifensulfuron methyl in the Registration 

Review Preliminary Problem Formulation for the Ecological Risk Assessment of Thifensulfuron 

methyl, March 10, 2011, the EFED update on Data Needs for Thifensulfuron (PC code 128845) 

Associated with the Registration Review DCI Issuance, dated December 8, 2011, and the 

Thifensulfuron methyl. Human Health Assessment Scoping Document in Support of Registration 

Review, dated March 15, 2011. 

 

Guideline 

Number Data Requirement 

Test Material Estimated Timeframe 

835.6100 Terrestrial Field Dissipation1

 TGAI 12 

835.6200 Aquatic Field Dissipation2

 TGAI 12 

NonGuideline Special Study for Non-Target Plant Reproductive Toxicity TEP 24 

870.3200 21/28 Day Dermal Toxicity Study TGAI 12 

870.3465 90-day Inhalation Toxicity Study3 TGAI 24 

870.6200 Neurotoxicity Battery (Acute and Subchronic Studies) TGAI 24 

870.7800 Immunotoxicity Study TGAI 12 

 

1

 Only Environmental Chemistry Method for Residues in Soil and (associated ILV) are needed. 2

 Only Environmental Chemistry Method for Residues in Water and (associated ILV) are needed. 3

 Based on expected duration of exposure, the DCI is expected to provide that registrants may conduct a 28-day 

inhalation toxicity study in lieu of a 90-day study.