Docket Number EPA-HQ-OPP-2014-0175 

www.regulations.gov 

Thiabendazole Final Work Plan 

Registration Review 

Case Number 2670 

September 2014 

· Approved by: Efkt. nct.~~ .P <l&~ ~ 

Date: 

Richard P. Keigwin, Jr. 

Director 

Pesticide Re-evaluation Division 

Jc<-:),._.-, -~./J Susan Lewis 

Director 

Antimicrobials Division 
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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 thiabendazole. This work plan addresses public comments received 

concerning the Preliminary Work Plan (PWP), which was posted in the thiabendazole 

registration review docket (EPA-HQ-OPP-2014-0175). Thiabendazole is a systemic fungicide 

registered for use as a seed treatment on com, soybean, dry peas, chickpeas, lentils, and wheat; a 

treatment of seed pieces on potatoes and sweet potatoes; to control fungal diseases in mushroom 

culture; a postharvest application to a variety of terrestrial food and non-food crops; and a 

fungicide and preservative used in the manufacture of adhesives (non-food), carpets, ceiling tiles, 

paper products (non-food), paints and stains (used indoor and outdoor), plastics and rubber, 

textiles, and wallboard. 

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.

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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. This section is followed by registration 

review planned data needs, risk assessments expected to be conducted, and the projected 

registration review time line for thiabendazole. Lastly, there is a discussion of next steps. 

UPDATES SINCE THE PWP WAS ISSUED 

The anticipated Special Study, Non-guideline for Leaching from Treated Textiles has been 

reclassified as guideline 875.2300 Indoor Surface Residue Dissipation (see Table 1). 

The estimated timeframe for completion of the Residential handler inhalation exposure - indoor 

(GLN 875.1400) and Indoor surface residue dissipation (GLN 875.2300) were incorrectly listed 

as 12 months in the PWP. The correct timefrarne of24 months has been updated in the list of 

data requirements (see Table 1) in the FWP. The Projected Registration Review Timeline in the 

PWP is correct and matches the 24 month tirneframe for data submission in this FWP (see Table 

3). 

SUMMARY OF COMMENTS AND AGENCY RESPONSES 

During the 60-day public comment period on the thiabendazole PWP, which opened on March 

28, 2014 and closed on May 27, 2014, the Agency received six public comments. Comments 

1 http://www.epa.gov/oppsrrd I /registration_review/ 

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were submitted by the Washington State Pest Management Resource Service, Washington State 

University Tri-Cities; the Northwest Horticultural Council (NHC); the FIFRA Endangered 

Species Task Force (FESTF); the Center for Biological Diversity (CBD); Syngenta Crop 

Protection LLC; and Lanxess Corporation. The comments do not address the timeline described 

in the PWP, but they do address the planned ecological and human health risk assessments and 

data requirements. In the PWP, EPA also solicited comments on the specific topics of 

environmental justice, water quality concerns, and trade irritants. While no comments were made 

on environmental justice or water quality concerns, Syngenta and NHC commented on the 

importance of avoiding trade irritant issues. 

This section does not capture every comment made about the PWP ~or all of the Agency's 

responses. Summarized below are public comments that resulted in changes to the anticipated 

registration review data needs, risk assessments, or timeline, or are of a broader regulatory 

nature. Public comments and EPA responses in their entirety are located in the docket, EPAHQ-OPP-2014-0175. Summarized public comments and Agency responses related to the 

anticipated ecological risk assessment or data needs are in the EFED Response to Comments on 

the Problem Formulation for Thiabendazole and Thiabendazole Hypochloride (dated August 11 , 

20 14) while those relevant to the anticipated human health risk assessment or data needs are in 

the documents Thiabendazole and Salts: Health Effects Division's Response to Comments on the 

Thiabendazole Preliminary Work Plan (PWP) for Registration Review (dated June 24, 2014 and 

a second memo dated August 12, 20 14), and those relevant to the antimicrobial registrations are 

in the Antimicrobial Division 's Response to Public Comments on the Registration Review 

Preliminary Work Plan for Thiabendazole (dated August 21, 2014). 

1. Comments submitted by the Washington State Pest Management Resource Service 

on behalf of the Western Integrated Pest Management (IPM) Center in EP A-HQOPP-2014-0715-00 10. 

Comment: The submitted comments provided information on use of thiabendazole in the 

northwest U.S., including its use in IPM and agricultural benefits. 

Response: The Agency thanks the Washington State Pest Management Resource Service for 

its comments. EPA will consider this information during the thiabendazole registration 

revtew. 

2. Comments submitted by NHC in EPA-HQ-OPP-2014-0715-0011. 

Comment: NHC submitted information about the use of thiabendazole and highlighted 

potential trade irritant issues. 

Response: The Agency thanks NHC for its comments. EPA will consider this information 

during the thiabendazole registration review. 

3. Comments submitted by FESTF in EPA-HQ-OPP-2014-0715-0012. 

Comment: FESTF identified Aibaugh, lnc and Syngenta Corporation as FESTF members 

entitled to rely on FESTF data. 

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Response: The Agency thanks FESTF for its comment and will consider this information 

during the thiabendazole registration review. 

4. Comments submitted by CBD in EPA-HQ-OPP-2014-0715-0013. 

Comment: CBD's comments focus on EPA's duty to consult with the U.S. Fish and Wildlife 

Service and the National Marine Fisheries Service (the Services) on the registration review of 

thiabendazole in accordance with the Endangered Species Act (ESA). CBD's comments 

mention various aspects of the risk assessment process, including use of the best available 

data to develop endangered species risk assessments, and evaluation of effects on endangered 

and threatened species and their designated critical habitat. CBD also expresses concern 

regarding the rigor of the Agency's determinations. 

Response: EPA has reviewed the comments from CBD on the registration review docket 

opening for thiabendazole and plans to address many of the concerns raised by CBD as part 

of the implementation plan for assessing the risks of pesticides to listed species based on the 

recommendations of the April 2013 National Academy of Sciences (NAS) report. EPA will 

address concerns specific to thiabendazole in connection with the development of its final 

registration review decision for this pesticide. 

In November 2013, the EPA, along with the Services and the USDA, released a summary of 

their joint Interim Approaches for assessing risks to endangered and threatened (listed) 

species from pesticides. The Interim Approaches were developed jointly by the agencies in 

response to the NAS recommendations and reflect a common approach to risk assessment 

shared by the agencies as a way of addressing scientific differences between the EPA and the 

Services. The NAS report outlines recommendations on specific scientific and technical 

issues related to the development of pesticide risk assessments that EPA and the Services 

must conduct in connection with their obligations under the ESA and FIFRA. 

The joint Interim Approaches were released prior to a stakeholder workshop held on 

November 15, 2013. In addition, the EPA presented the joint Interim Approaches at the 

December 2013 Pesticide Program Dialogue Committee (PPDC) and State-FIFRA Issues 

Research and Evaluation Group (SFIREG) meetings. The agencies also held a stakeholder 

workshop in April2014, allowing additional opportunities for stakeholders to comment on 

the Interim Approaches. Additional workshops are planned to enhance stakeholder 

involvement; the next workshop is scheduled for October 20 14. As part of a phased, iterative 

process for developing the Interim Approaches, the agencies will also consider public 

comments on the Interim Approaches in connection with the development of upcoming 

registration review decisions. The details of the joint Interim Approaches are contained in 

the white paper, Interim Approaches for National-Level Pesticide Endangered Species Act 

Assessments Based on the Recommendations of the National Academy a/Sciences Apri/2013 

Report, dated November 1, 201 3. 

Given that the agencies are continuing to develop and work toward implementation of the 

Interim Approaches to assess the potential risks of pesticides to listed species and their 

designated critical habitat, the ecological problem formulation supporting this Final Work 

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Plan for thiabendazole does not describe the specific ESA analysis, including effects 

determinations for specific listed species or designated critical habitat~ to be conducted 

during registration review. In the ecological problem formulation document for 

thiabendazole, EPA described the screening-level risk assessment to determine the potential 

effects of thiabendazole on all taxa of non-target wildlife and plants, which wiU assume that 

listed species and their designated critical habitats may be present in the vicinity of the 

application of thiabendazole. This screening-level assessment will allow EPA to focus its 

future evaluations on the types of species where the potential for effects exists once the 

scientific methods being developed by the agencies have been fully vetted. While the 

agencies continue to develop a common method for ESA analysis, the planned screeninglevel risk assessment for the registration review of thiabendazole will describe the level of 

ESA analysis completed for this particular registration review case. Once the agencies have 

fully developed and implemented the scientific methods necessary to complete risk 

assessments for endangered and threatened (listed) species and their designated critical 

habitats, these methods will be applied to subsequent analyses for thiabendazole as part of 

completing this registration review. 

5. Comments submitted by Syngenta Crop Protection, LLC in EPA-HQ-OPP-2014-

0715-0014. 

Comment: Two studies have been submitted in response to the requirement for 

Environmental Chemistry Methods (ECM) and Independent Laboratory Validation (IL V); 

Water. Note: Additional comments made by Syngenta are addressed in the Thiabendazole 

and Salts: Health Effects Division 's Response to Comments on the Thiabendazole 

Preliminary Work Plan (PWP) for Registration review and the EFED Response to Comments 

on the Problem Formulation for Thiabendazole and Thiabendazole Hypochloride. 

Response: The Agency is in receipt of the two reports submitted by Syngenta Crop 

Protection, LLC on May 28, 2014. These studies are currently being evaluated. 

6. Comments submitted by Lanxess Corporation via email. 

The comments submitted by Lanxess along with the Agency's response can be found in the 

Antimicrobial Division 's Response to Public Comments on the Registration Review 

Preliminary Work Plan for Thiabendazole. 

Description of Other Changes to the List of Data Requirements from the PWP 

1. As stated in the problem formulation, EFED plans on estimating toxicity using the acute-tochronic ratio method. Thus the requirement to conduct the life-cycle study with the saltwater 

mysid (GLN 850.135) will not be included in the Generic Data Call-in (GDCI) for 

registration review. 

2. As noted in the PWP, the developmental thyroid toxjcity will not be included in the 

anticipated GDCI because it is already required as a condition of registration. 

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3. The anticipated Special Study, Non-guideline for Leaching from treated textiles has been 

reclassified as guideline 875.2300 Indoor Surface Residue Dissipation, with specific use 

sites. 

PLANNED DATA NEEDS 

Table 1 below summarizes the planned data needs for thiabendazole based on the Problem 

Formulation for the Ecological Risk and Drinking Water Exposure Assessments to be Conducted 

in Support of the Registration Review of Thiabendazole and its Hypophosphite Salt, and 

Thiabendazole and Salts: Human Health Risk Scoping Document in Support of Registration 

Review. The table has been updated since the PWP to reflect the data requirements that will be 

issued under the DCI for registration review. 

Table 1: Planned Data Needs for the Thiabendazole Registration Review I 

Estimated 

Guideline Study Title2 Timeframe 

Number Test Material (Months from 

receipt of DCI) 

850.2100 Avian oral toxicity (passerine) TGAl 12 

850.4500 Algal Toxicity Tier II - marine diatom, freshwater TGAI 12 diatom, green algae 

850.3300 Activated Sludge Respiration Inhibition (ASR1)3 TGAI 12 

835.3110 Ready Biodegradability or one of three 835.3220 

835.3240 biodegradation in activated sludge simulation TGAI 12 

835.3280 tests 4 

850.4550 Cyanobacteria toxicity TGAI 12 

2 On June 27, 2012, EPA announced certain revisions in harmonized guideline series 850 - Ecological Effects Tests 

- including renumbering and other designations or changes for some guideline studies. See "Final Test Guidelines; 

OCSPP 850 Series; Notice of Availability" 77 FR 38282, June 27,2012. 

http://www .regulations.gov/#! documentDetai I;D=EP A-HQ-OPPT -2009-0 154-0028 

3 EPA has a published final guidance for this study: http://www.regulations.gov/#!documentDetail;D=EPA-HOOPPT-2009-0 154-0021 . OECD Test Guideline 209 can also be used as guidance for this study, available online at 

htto://www.oecd-ilibrary.org/content/book/9789264070080-en. 4 The results of the Activated Sludge, Respiration Inhibition Test (ASRl), GLN 850.3300, will determine which of 

the four biodegredation tests is/are required. If the ASRI test results in an ECsoofless than or equal to 20 mg/L, then 

the registrant is required to conduct either the (i) Simulation tests to assess the biodegradability of chemicals 

discharged in wastewater1

, GLN 835.3280, (ii) the Simulation Test- Aerobic Sewage Treatment - A. Activated 

Sludge Units, GLN 835.3240, or (iii) the Porous Pot Test, GLN 835.3220. If.the ASRl test results in an ECso greater 

than 20 mg/L, then the registrant would be required to conduct either the (i) Ready Biodegradability, GLN 3110, (ii) 

Simulation tests to assess the biodegradability of chemicals discharged in wastewater, (iii) the Simulation TestAerobic Sewage Treatment - A. Activated Sludge Units, or (iv) the Porous Pot Test. If the Ready Biodegradability 

Study is conducted and passes, then no further testing is required. If, however, the pesticide fails the Ready 

Biodegradability study, then the registrant is required to conduct either the (i) Simulation tests to assess the 

biodegradability of chemicals discharged in wastewater, (ii) the Simulation Test - Aerobic Sewage Treatment - A. 

Activated Sludge Units, or (iii) the Porous Pot Test. 

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850.6100 Environmental chemistry methods and associated TGAJ 12 independent laboratory validations for water 

875.1200 Residential handler dermal exposure - indoor TEP 12 (airless sprayer and brush/roller) 

875.1400 Residential handler inhalation exposure- TEP 24 indoor (airless sprayer and brush/roller) 

875.1 700 Product use information TEP 12 

875.2300 Indoor surface residue dissipation (plush carpet TEP 24 and clothing)5 

875.2700 Product use data TEP 12 

875.2800 Descriptions of human activity TEP 12 

TGAI = techmcal grade acttve mgredtent; TEP = typtcal end-use product; 

RISK ASSESSMENTS FOR REGISTRATION REVIEW 

During registration review, the Agency will conduct a comprehensive ecological risk assessment, 

including an endangered species assessment, for all uses of thiabendazole. For human health, 

EPA anticipates the need to conduct revised dietary, residential, and occupational risk 

assessments during registration review. If toxicological endpoints or points of departure are 

revised based on the data that are anticipated to be required for registration review, they will be 

considered in the new assessments, as well as any changes to the standard operating procedures 

or default exposure assumptions. 

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

Problem Formulation and HED Scoping Document. The planned assessments have not changed 

from what was included in the PWP. 

5 Residue dissipation studies are required fortex'tiles (clothing) and the plush of carpets. If specified on the label that 

only carpet backing is treated, then a residue study wi ll not be needed for carpets. 

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Table 2: Planned Risk Assessments for the Thiabendazole Registration Review 

Type of Risk Assessment Conduct? Notes 

Ecolof.,-ical and Environmental Fate 

Comprehensive ecological y 

(species to be assessed 

include terrestrial and aquatic 

organisms), including 

endangered species 

Incidents Will check for Based on the low frequency and severity of incident 

updates cases reported for thiabendazole and salts, there does 

not appear to be a concern at this time that would 

warrant further investigation. The Agency will 

continue to monitor the incident information and if a 

concern is triggered, additional analysis will be 

included in the risk assessment. 

Human Health 

Dietary 

Food y A new dietary (food and water) risk assessment may 

need to be conducted if there are changes to the 

thiabendazole toxicological points of departure, 

safety factors or significant changes to the estimated 

drinking water concentrations. 

Drinking water y The Agency will assess the need for a down-thedrain assessment for the use of thiabendazole as a 

material preservative during the manufacturing 

process. 

Occupational 

Handlers (mixers, loaders, y Only the antimicrobial occupational handler 

applicators) assessment will need to be revised. For conventional 

uses the occupational exposur~ assessments may 

need to be updated to reflect the most recent 

occupational handler surrogate exposure data as well 

as any significant change in exposure assessment 

approaches. 

Post -application y For conventional uses the occupational postapplication exposure assessments may need to be 

updated to reflect the any significant change in 

exposure assessment approaches. 

Residential 

Handlers y Only the antimicrobial residential handler assessment 

will need to be conducted based on new handler 

exposure data for application of paints required for 

registration review. 

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Post-application y Only the antimicrobial post-application assessment 

\\ ill need to be completed. This "'ill include treated 

clothing and carpet for dermal and i~cidental oral 

exposure. 

Other 

Cumulative N Thiabendazole has not been identified as a member 

of a cumulative group that shares a common 

mechanism of toxicity. 

Tolerances N Tolerances are established under 40 CFR § 180.242 

for residues of thiabendazole, however a number of 

U.S. tolerances are not compatible with Canadian or 

CODEX MRLs. The tolerance residue definition and 

levels will need to be examined during Registration 

Review to determine if compatibility can be 

achieved. 

Incidents Will check for Based on the low frequency and severity of incident 

updates cases reported for thiabendazole and salts, there does 

not appear to be a concern at this time that would 

warrant further investigation. The Agency will 

continue to monitor the incident information and if a 

concern is triggered, additional analysis will be 

included in the risk assessment. 

TIMELINE 

EPA has created the following estimated timeline for the completion of the thiabendazole 

registration review in Table 3 below. The projected timeline has been updated to reflect minor 

delays in the publication of recent actions. 

Table 3: Registration Review for Thiabendazole- Pro,jected Registration Review Timeline 

Activities Estimated Date 

Opening the Docket 

Open Docket and 60-day Public Comment Period March 2014 -

Completed 

Close Public Comment Period May 2014 - Completed 

Case Development 

Final Work Plan Sep. 2014 - Completed 

Issue DCI 2014 Oct.- Dec. 

Data Submission 2016 Oct.- Dec. 

60-day Public Comment Period for Draft Risk Assessments6 2018 April - June 

Registration Review Decision 

6 The regulations governing Registration Review generally require the Agency to provide a public comment period 

of at"least 30 calendar days for draft risk assessments; see 40 CFR Part l55.53(c). For conventional pesticides, the 

Agency plans to provide a 60 calendar day public comment period generally for dralt risk assessments. 

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Table 3: Registration Review for Thiabendazole- Projected Registration Review Timeline 

Activities Estimated Date 

60-day Public Comment Period for Proposed Registration Review 2019 Jan- March 

Decision 

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

Total (years) 5 

NEXT STEPS 

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

and human health studies for thiabendazole through a Data Call-In Notice, expected to be issued 

in 2014. · 

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