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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 TFM and niclosamide. This work plan addresses public comments 

received concerning the Preliminary Work Plan (PWP), which was posted in the TFM and 

niclosamide registration review docket (EPA-HQ-OPP-2013-0137). TFM and niclosamide are 

biocides registered for use to control sea lampreys (Petromyzon marinus) in streams and rivers 

tributary to the Great Lakes by targeting the larval (ammocete) development stage of the 

lamprey. Given the intended target organisms, both compounds are frequently referred to as 

lampricides; however, they are also considered piscicides since both compounds are intended to 

kill fish. Historically, niclosamide has been used alone as a survey method for assessing larval 

sea lamprey populations and has been used as a molluscicide in Puerto Rico for the control of 

snails that vector blood flukes responsible for the potentially debilitating disease 

Schistosomiasis. In most sea lamprey control applications however, only TFM is applied. 

Occasionally a combination of TFM and niclosamide is applied to reduce the amount of TFM 

required for treatment.

The Agency is implementing the registration review program pursuant to Section 3(g) of the 

Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), and will review each registered 

pesticide every 15 years to determine whether it continues to meet the 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 on the Agency’s website.1

The FWP begins with any updates since the PWP was issued. Next is a summary of substantive 

comments received during the public comment period for the PWP concerning anticipated data 

needs, expected risk assessments, or the estimated timeline identified in the PWP, and a 

summary of the Agency’s responses to those comments. In this case, there were no comments 

received. This section is followed by registration review planned data needs, risk assessments 

expected to be conducted, and the projected registration review timeline for TFM and 

niclosamide. Lastly, there is a discussion of next steps.

UPDATES SINCE THE PWP WAS ISSUED

There are no additional updates on TFM and niclosamide since the PWP.

SUMMARY OF COMMENTS AND AGENCY RESPONSES

There were no comments received during the public comment period for TFM and niclosamide.

 1 http://www.epa.gov/oppsrrd1/registration_review/
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PLANNED DATA NEEDS

Table 1 below summarizes the planned data needs for TFM and niclosamide based on the 

Registration Review – Preliminary Problem Formulation for Ecological Risk and Environmental 

Fate, Endangered Species, and Drinking Water Assessments for TFM (PC Code 036201) and

Niclosamide (PC Code 077401) and 3-Trifluoro-Methyl-4-Nitro-Phenol and Niclosamide

Revised Human Health Risk Assessment Scoping Document in Support of Registration Review. 

The planned data needs have not changed from what was included in the PWP.

Table 1: Planned Data Needs for TFM and Niclosamide Registration Review

Guideline 

Number Study Title Test Material

Estimated 

Timeframe

(Months from 

receipt of DCI)

835.2240 Aqueous photolysis (niclosamide only) TGAI 12

835.4300 Aerobic aquatic metabolism (niclosamide only) TGAI 24

835.4400 Anaerobic aquatic metabolism (niclosamide only) TGAI 24

850.1500 Chronic fish life cycle toxicity (TFM only) TGAI 24

850.1735 Whole sediment acute freshwater invertebrates 

toxicity (TFM only) TGAI 12

850.4400 Aquatic vascular toxicity (TFM and niclosamide) TGAI 24

850.6100 Environmental chemistry methods for water (TFM 

and niclosamide) TGAI 12

TGAI = technical grade active ingredient

RISK ASSESSMENTS FOR REGISTRATION REVIEW

During registration review, the Agency anticipates the need to conduct a comprehensive

ecological risk assessment, including an endangered species assessment, for all uses of TFM and 

niclosamide.

Table 2 below summarizes the planned registration review risk assessments based on the EFED 

Problem Formulation and HED Scoping Document and the planned assessments have not 

changed from what was included in the PWP.
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Table 2: Planned Risk Assessments for TFM and Niclosamide’s Registration Review

Type of Risk Assessment Include? Notes

Ecological and Environmental Fate

Comprehensive ecological 

(species to be assessed include 

terrestrial and aquatic 

organisms), including 

endangered species 

Y 

Human Health

Dietary

Food N There are no registered food uses for TFM and 

niclosamide.

Drinking water N

Occupational

Handlers (mixers, loaders, 

applicators)

N A revised screening level short-term assessment for 

TFM handlers using conservative assumptions showed 

no risks of concern.

Post-application N No post-application occupational exposure is expected 

for TFM and niclosamide.

Residential

Handlers Y If there are significant changes in new use pattern data 

acquired during registration review, a new 

occupational risk assessment may be required.

Post-application N

Incidental oral N

Companion animal N

Recreational N

Other

Aggregate N There are no registered food uses or residential uses 

for TFM and niclosamide.

Cumulative N The Agency has not determined whether TFM and 

niclosamide share a common mechanism of toxicity 

with other chemical substances.

Tolerances N There are no tolerances registered for TFM and 

niclosamide.
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TIMELINE

EPA has created the following estimated timeline for the completion of TFM and niclosamide’s

registration review in Table 3 below. The projected timeline has not changed since the PWP.

Table 3: Registration Review for TFM and Niclosamide – Projected Registration Review 

Timeline

Activities Estimated Date

Opening the Docket

Open Docket and Public Comment Period 2013 - March

Close Public Comment 2013 - May

Case Development

Final Work Plan 2013 - August

Issue DCI 2014 – April - June

Data Submission 2016 – April - June

60-Day Public Comment Period for Draft Risk Assessments 2017 – Oct. - Dec.

Registration Review Decision

60-Day Public Comment Period for Proposed Registration Review 

Decision 

2018 – April - June

Registration Review Decision and Begin Post-Decision Follow-up 2019

Total (years) 6

NEXT STEPS

As noted previously, the Agency plans to require several environmental fate and ecological 

effects studies for TFM and niclosamide through a Data Call-In Notice, expected to be issued in 

April to June 2014.