2

TPTH Preliminary Work Plan – Table of Contents 

Overview 3 

Anticipated Data Needs 4 

Statutory and Regulatory Authority 5 

Use and Usage Information 6 

Recent Actions 7 

Anticipated Risk Assessments for Registration Review 7 

Timeline 9 

Next Steps 9 

Appendix – Additional Areas Considered in TPTH’s Registration Review 10 

References:

This Preliminary Work Plan summarizes the Environmental Protection Agency's current position 

based on the following documents: 

1. Registration Review: Preliminary Problem Formulation for Environmental Fate, 

Ecological Risk, Endangered Species, and Human Health Drinking Water Exposure 

Assessments for Triphenyltin Hydroxide (TPTH). Milians and Sayer. November 29, 2012. 

2. TPTH (Triphenyltin Hydroxide). Health Effects Division (HED) Scoping Document for 

Registration Review. Sahafeyan, McCarroll, and Bobowiec. December 4, 2012. 

3. BEAD Chemical Profile for Registration Review: Triphenyltin Hydroxide (TPTH) also 

Known as Fentin Hydroxide (083601). Chandgoyal, Doucoure, and Faulkner. June 25, 

2012. 

4. TPTH (Fentin Hydroxide): Review of Human Incidents. Recore. July 19, 2012.

These and other supporting documents for the TPTH registration review case may be found in 

the docket EPA-HQ-OPP-2012-0413 at http://www.regulations.gov. 
3

OVERVIEW

The docket for triphenyltin hydroxide (TPTH), also known as fentin hydroxide, is now open, 

initiating the first public comment period for this registration review (docket number EPA-HQOPP-2012-0413). TPTH is a non-systemic foliar fungicide registered for use to control early and 

late blight on potatoes; Colorado potato beetle and leaf spot on sugar beets; and scab, brown leaf 

spot and other diseases on pecans. In addition to its fungicidal activity, TPTH exhibits antifeeding properties for surface-feeding insects. There are no registered residential uses, and 

TPTH products are used primarily in agricultural areas. This Preliminary Work Plan (PWP) 

document explains what EPA's Office of Pesticide Programs knows about TPTH, highlighting 

anticipated data and assessment needs, identifying the types of information that would be 

especially useful to the Agency in conducting the review, and providing an anticipated timeline 

for completing TPTH’s review. 

 

The registration review process was designed to include a public participation component to 

solicit input from interested stakeholders. The Agency intends, by sharing this information in the 

docket, to inform the public of what it knows about TPTH and what types of new data or other 

information would be helpful for the Agency to receive as it moves toward a decision on TPTH. 

The Agency encourages all interested stakeholders to review the PWP and Appendix and to 

provide comments and additional information that will help the Agency’s decision-making 

process for this chemical. In addition to general areas on which persons may wish to comment, 

there are some areas identified in the PWP and Appendix about which the Agency specifically 

seeks comments and information. Interested stakeholders could include: environmental nonprofit or interest groups; pesticide manufacturers; agricultural labor or commodity groups; 

commercial, institutional, residential, and other users of pesticides; or the public at large. 

The Preliminary Work Plan begins by listing the anticipated data needs for TPTH. Next, it 

discusses the statutory and regulatory authority for Registration Review. Then the document 

provides TPTH’s chemical facts, use and usage information, recent actions, the anticipated risk 

assessments, and a projected registration review timeline. Finally, the Appendix to this 

document includes identification and discussion of some areas that are considered generally in 

Registration Review along with some additional chemical case-specific information. 

 
4

ANTICIPATED DATA NEEDS

Table 1 below summarizes anticipated data needs for TPTH. For additional discussion of the 

anticipated data needs, see the Registration Review: Preliminary Problem Formulation for 

Environmental Fate, Ecological Risk, Endangered Species, and Human Health Drinking Water 

Exposure Assessments for Triphenyltin Hydroxide (TPTH) and TPTH (Triphenyltin Hydroxide). 

Health Effects Division (HED) Scoping Document for Registration Review. 

Table 1: Anticipated Data Needs for TPTH’s Registration Review 

Guideline 

Number Study Title Test Material 

Estimated 

Timeframe 

(Months from 

receipt of DCI) 

835.4100 Aerobic Soil Metabolism TGAI or 

PAIRA 24 

850.1300 Aquatic Invertebrate Life Cycle (freshwater) TGAI 12 

850.1350 Aquatic Invertebrate Life Cycle (saltwater) TGAI 12 

850.1400 Fish Early-Life Stage (saltwater) TGAI 12 

850.2100 Avian oral toxicity (passerine species) TGAI 12 

850.6100 

Environmental Chemistry Methods and Associated 

Independent Laboratory Validation for soil and 

water1 

TEP 12 

870.7800 Immunotoxicity TGAI 12 

The study listed below was previously required through a generic data call-in (GDCI-083601-17847), 

issued in November 1999, and is still outstanding. This study is listed in this document as background; 

it will NOT be included in the anticipated Registration Review DCI as it is already required through the 

earlier DCI. 

835.1230 

(listed as 

163-1 in 

1999 

GDCI) 

Adsorption/Desorption 

(Batch Equilibrium) 2

TGAI or 

PAIRA due 11/2000 

TGAI = technical grade active ingredient; PAIRA = pure active ingredient radiolabeled; TEP = typical end-use product 

 

 

1 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/#!documentDetail;D=EPA-HQ-OPPT-2009-

0154-0028

2 The 1999 GDCI stated the following: “Adsorption/desorption studies are required in order for the Agency to perform 

environmental fate assessments. The submitted adsorption/desorption study was a thin-layer chromatography (TLC) study, which 

does not provide Kds, which are necessary for fate assessments. A batch study is required.”
5

STATUTORY AND REGULATORY AUTHORITY

The Food Quality Protection Act (FQPA) of 1996 mandated a registration review program. All 

pesticides distributed or sold in the United States (U.S.) generally must be registered by the 

Environmental Protection Agency (EPA or the Agency), based on scientific data showing that 

they will not cause unreasonable risks to human health or the environment when used as directed 

on product labeling. 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 of no unreasonable adverse effects to human health or the 

environment. Changes in science, public policy, and pesticide use practices will occur over time. 

Through the registration review program, the Agency periodically reevaluates pesticides to make 

sure that as change occurs, products in the marketplace can be used safely. Information on this 

program is provided on EPA’s website3

. 

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. The regulations governing registration review begin at 40 CFR 155.40. The 

Agency will consider benefits information and data as required by FIFRA. The public phase of 

registration review begins when the initial docket is opened for each case. The docket is the 

Agency’s opportunity to state what it knows about the pesticide and what additional risk analyses 

and data or information it believes are needed to make a registration review decision. After 

reviewing and responding to comments and data received in the docket during this initial 

comment period, the Agency will develop a Final Work Plan (FWP) and anticipated schedule for 

the registration review of TPTH. 

Table 2 provides a summary of the current regulatory status of TPTH. 

Table 2: TPTH Chemical Facts 

PC code 083601 

Case Number 99 

CAS Number 76-87-9 

Year first registered 1979 

Pesticide Type Fungicide 

Chemical class Conventional chemical 

Reregistration Eligibility 

Decision (RED) 

September 1999 

Tolerance Reassessment 

Eligibility Decision 

(TRED) 

Not applicable 

Cumulative group Not applicable 

40 CFR Citation Tolerances for TPTH are established in 40 CFR 180.236 

Dual-use Conventional pesticidal uses only 

Non-pesticidal uses No non-pesticidal uses of TPTH 

 

3

 http://www.epa.gov/oppsrrd1/registration_review/ 
6

Pesticide Re-evaluation 

Division, Chemical 

Review Manager 

Susan Bartow, bartow.susan@epa.gov, 703-603-0065 

Registration Division, 

Product Manager 

Tony Kish, kish.tony@epa.gov, 703-308-9443 

USE AND USAGE INFORMATION

Table 3 summarizes the use and usage information for TPTH. Please see the BEAD Chemical 

Profile for Registration Review: Triphenyltin Hydroxide (TPTH) also Known as Fentin 

Hydroxide (083601) in the registration review docket for more details. 

Table 3: TPTH Use and Usage Information 

Summary of Use TPTH is a non-systemic foliar fungicide registered for use on 

agricultural crops. TPTH belongs to a class of chemicals that inhibits 

oxidative phosphorylation and fungal growth. In addition to its 

fungicidal activity, TPTH exhibits anti-feeding properties for surfacefeeding insects. TPTH is registered for use on pecans primarily for 

control of scab, brown leaf spot, and other diseases. For potatoes, 

TPTH is registered for use to control early and late blight. For sweet 

potatoes, TPTH is registered for use to control Colorado potato beetle 

and leaf spot.

Use Sites TPTH is registered for use on pecans, potatoes, and sugar beets. It is 

not registered for non-agricultural/residential use. 

Summary of Usage During the years of 2006-2010, on average, approximately 230,000 

pounds of TPTH were reported to have been used to treat 950,000 

acres.

Formulation Type(s) TPTH is formulated as a wettable powder and flowable concentrate.

Application Method(s) Products can be applied by ground and aerial spraying, as well as 

chemigation (irrigation supply water system). 

Technical Registrant(s) Bayer CropScience; Nufarm Americas, Inc.; and United 

Phosphorus, Inc. 

No. of Registrations 10 Section 3 products4 and 8 Section 24(c) products. 

Restricted Use Yes 

Guidance for Commenters: Additional areas of use and usage related information

requested for this registration review, and of particular interest to EPA, are described below. 

 Confirmation of the maximum application rate of active ingredient per season for pecans, 

potatoes, and sugar beets. 

 Confirmation of the following label information: sites of application; formulations; 

application methods and equipment; maximum application rates; frequency of 

application, application intervals, and maximum number of applications per season; and 

geographic limitations on use. 

 

4

 Section 3 product labels can be obtained from the Pesticide Product Label System (PPLS) website 

(http://oaspub.epa.gov/pestlabl/ppls.home). 
7

 Use distribution (e.g., acreage and geographical distribution of relevant use sites). 

 Median and 90th percentile reported use rates (lbs ai/A) from usage data – national, state, 

and county. 

 Application timing (date of first application and application intervals) – national, state, 

and county. 

 Typical application interval (days). 

 State or local use restrictions. 

 Foreign technical registrants not listed above who supply technical TPTH to the US 

market. 

RECENT ACTIONS

On October 8, 2009, the Agency included TPTH on the third Contaminant Candidate List (CCL 

3) issued since the Safe Drinking Water Act (SDWA) amendments of 1996. The CCL 3 is a list 

of contaminants that are currently not subject to any proposed or promulgated national primary 

drinking water regulations, that are known or anticipated to occur in public water systems, and 

which may require regulation under SDWA (FRL 51850). 

ANTICIPATED RISK ASSESSMENTS FOR REGISTRATION REVIEW

The most recent comprehensive human health risk assessment for TPTH was completed in 

September 1999 in preparation for the Reregistration Eligibility Decision. The most recent 

ecological and environmental fate risk assessment was completed June 1999 for the same 

purpose. Findings and conclusions from these risk assessments are summarized in the 

Registration Review: Preliminary Problem Formulation for Environmental Fate, Ecological 

Risk, Endangered Species, and Human Health Drinking Water Exposure Assessments for 

Triphenyltin Hydroxide (TPTH) and TPTH (Triphenyltin Hydroxide). Health Effects Division 

(HED) Scoping Document 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 TPTH. 

For human health, EPA anticipates the need to conduct revised dietary 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 4 below summarizes the anticipated registration review risk assessments based on the 

EFED Problem Formulation and HED Scoping Document. 

 
8

Table 4: Anticipated Risk Assessments for TPTH’s Registration Review 

Type of Risk Assessment Conduct? Notes 

Ecological and Environmental Fate 

Comprehensive ecological 

(species to be assessed 

include terrestrial and aquatic 

organisms), including 

endangered species 

Y 

The Agency plans to evaluate risks to nontarget 

terrestrial and aquatic organisms, including 

Federally-listed threatened and/or endangered 

species. 

Incidents Y For a discussion of TPTH’s reported ecological 

incidents, see page 14 of the Problem Formulation. 

Human Health 

Dietary 

Food Y The Agency anticipates conducting a revised dietary 

risk assessment. 

Drinking water Y The Agency plans to conduct a drinking water 

exposure assessment for TPTH. 

Occupational 

Handlers (mixers, loaders, 

applicators) Y 

The Agency anticipates conducting a revised 

occupational exposure and risk assessment during 

registration review. 

Post-application Y 

The Agency anticipates conducting a revised 

assessment for post-application exposures from 

TPTH. The need for a bystander inhalation risk 

assessment for TPTH also will be examined. 

Residential 

Handlers, post-application, 

incidental oral, and 

recreational 

N 

TPTH is not registered for use in residential settings. 

Therefore, a residential exposure assessment is not 

required. 

Other 

Aggregate Y 

Evaluates the combined risk from dietary and 

residential exposures. Since there are no residential 

uses of TPTH, the aggregate risk estimate will be 

equivalent to the dietary risk estimate. 

Cumulative N TPTH is not a member of a cumulative group and no 

cumulative risk assessment is planned. 

Tolerances Y 

The tolerance expression will be revised to ensure 

that it appropriately covers the metabolites and 

degradates of TPTH and that it specifies the residues 

to be measured for each commodity. 

Incidents Y For a discussion of TPTH’s reported human 

incidents, see page 8 of the Scoping Document. 
9

Guidance for Commenters: Additional ecological information requested for this 

registration review, and of particular interest to EPA, is described below. 

 Fate or toxicity data for the monophenyltin (MPT) degradate. 

 Information (e.g., fate or toxicity data) regarding inorganic forms of tin (Sn) once TPTH 

is released in the environment. 

 Information regarding whether MPT is more likely to form as an oxide or a hydroxide 

compound under certain circumstances. 

 Ecological incidents (non-target plant damage and avian, fish, reptilian, amphibian and 

mammalian mortalities) not already reported to the Agency. 

 Water quality monitoring data (see Appendix for further details). 

TIMELINE

EPA has created the following estimated timeline for the completion of TPTH’s registration 

review in Table 5 below. 

Table 5: Registration Review for TPTH – Projected Registration Review Timeline

Activities Estimated Date 

Opening the Docket 

Open Docket and 60-day Public Comment Period 2012 - December 

Close Public Comment 2013 - February 

Case Development 

Final Work Plan 2013 - May 

Issue DCI 2014 – Jan – March 

Data Submission 2016 – Jan – March 

30-day Public Comment Period for Draft Risk Assessments 2017 – July – Sept. 

Registration Review Decision 

60-day Public Comment Period for Proposed Registration Review 

Decision 

2018 – Jan – March 

Registration Review Decision and Begin Post-Decision Follow-up 2018 

Total (years) 6 

NEXT STEPS

After the 60-day public comment period closes, the Agency will review and respond to any 

comments received in a timely manner and then issue a Final Work Plan for the registration 

review of TPTH. 

 
10

Appendix – Additional Areas Considered in TPTH’s Registration Review

PUBLIC COMMENTS AND FEEDBACK:

Guidance for Commenters: The areas below highlight topics of special interest to the Agency 

where your comments, data submissions, or reference to sources of additional information could 

be of particular use.

Trade Irritants: 

Through the registration review process, the Agency intends to solicit information on trade 

irritants and, to the extent feasible, take steps toward facilitating irritant resolution. The Agency 

will work to harmonize tolerances and international maximum residue limits (MRLs) and may 

modify tolerance levels to do so, when possible. Growers and other stakeholders are asked to 

comment on any trade irritant issues resulting from lack of MRLs or disparities between U.S. 

tolerances and MRLs in key export markets, providing as much specificity as possible regarding 

the nature of the concern. 

Water Quality: 

TPTH is not identified as a cause of impairment for any water bodies listed as impaired under 

section 303(d) of the Clean Water Act5

. In addition, no Total Maximum Daily Loads (TMDLs) 

have been developed for TPTH6. More information on impaired water bodies and TMDLs can 

be found at the Agency’s website7. The Agency invites submission of water quality data for 

this pesticide. To the extent possible, data should conform to the quality standards in Appendix 

A of the OPP Standard Operating Procedure: Inclusion of Impaired Water Body and Other

Water Quality Data in OPP’s Registration Review Risk Assessment and Management Process8

 in 

order to ensure they can be used quantitatively or qualitatively in pesticide risk assessments. 

Environmental Justice: 

EPA seeks to achieve environmental justice, the fair treatment and meaningful involvement of all 

people, regardless of race, color, national origin, or income, in the development, implementation, 

and enforcement of environmental laws, regulations, and policies. To help address potential 

environmental justice issues, the Agency seeks information on any groups or segments of the 

population who, as a result of their location, cultural practices, or other factors, may have 

atypical, unusually high exposure to TPTH compared to the general population. Please 

comment if you are aware of any sub-populations that may have atypical, unusually high 

exposure compared to the general population.

 

5 http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d?p_cause_group_id=885

6

http://iaspub.epa.gov/tmdl_waters10/attains_nation.tmdl_pollutant_detail?p_pollutant_group_id=885&p_pollutant_

group_name=PESTICIDES

7 http://www.epa.gov/owow/tmdl/

8 http://www.epa.gov/oppsrrd1/registration_review/water_quality_sop.htm
11

ENDANGERED SPECIES:

A risk assessment that supports a complete endangered species determination has not been 

conducted for TPTH. The ecological risk assessment planned during registration review will 

allow the Agency to determine whether TPTH’s use has “no effect” or “may affect” federally 

listed threatened or endangered species (listed species) or their designated critical habitats. 

When an assessment concludes that a pesticide’s use “may affect” a listed species or its 

designated critical habitat, the Agency will consult with the U.S. Fish and Wildlife Service 

and/or National Marine Fisheries Service (the Services), as appropriate. 

On January 19, 2011, the Center for Biological Diversity and the Pesticide Action Network 

North America filed a lawsuit in the United States District Court for the Northern District of 

California, against the Environmental Protection Agency (EPA) for allegedly failing to undergo 

consultation with the United States Fish and Wildlife Service and the National Marine Fisheries 

Service regarding the effects of over 350 pesticides, including TPTH (listed as fentin hydroxide 

in the lawsuit), on over 200 endangered and threatened species throughout the United States 

(Center for Biological Diversity, et al. v. EPA, et al., No. C 11-00293 (N.D.Cal.). 

ENDOCRINE DISRUPTOR SCREENING PROGRAM: 

As required by FIFRA and FFDCA, EPA reviews numerous studies to assess potential adverse 

outcomes from exposure to chemicals. Collectively, these studies include acute, subchronic and 

chronic toxicity, including assessments of carcinogenicity, neurotoxicity, developmental, 

reproductive, and general or systemic toxicity. These studies include endpoints which may be 

susceptible to endocrine influence, including effects on endocrine target organ histopathology, 

organ weights, estrus cyclicity, sexual maturation, fertility, pregnancy rates, reproductive loss, 

and sex ratios in offspring. For ecological hazard assessments, EPA evaluates acute tests and 

chronic studies that assess growth, developmental and reproductive effects in different 

taxonomic groups. As part of its reregistration decision for TPTH, EPA reviewed these data and 

selected the most sensitive endpoints for relevant risk assessment scenarios from the existing 

hazard database. However, as required by FFDCA section 408(p), TPTH is subject to the 

endocrine screening part of the Endocrine Disruptor Screening Program (EDSP). 

EPA has developed the EDSP to determine whether certain substances (including pesticide 

active and other ingredients) may have an effect in humans or wildlife similar to an effect 

produced by a “naturally occurring estrogen, or other such endocrine effects as the Administrator 

may designate.” The EDSP employs a two-tiered approach to making the statutorily required 

determinations. Tier 1 consists of a battery of 11 screening assays to identify the potential of a 

chemical substance to interact with the estrogen, androgen, or thyroid (E, A, or T) hormonal 

systems. Chemicals that go through Tier 1 screening and are found to have the potential to 

interact with E, A, or T hormonal systems will proceed to the next stage of the EDSP where EPA 

will determine which, if any, of the Tier 2 tests are necessary based on the available data. Tier 2 

testing is designed to identify any adverse endocrine-related effects caused by the substance, and 

establish a dose-response relationship between the dose and the E, A, or T effect. 

Under FFDCA section 408(p), the Agency must screen all pesticide chemicals. Between 

October 2009 and February 2010, EPA issued test orders/data call-ins for the first group of 67 
12

chemicals, which contains 58 pesticide active ingredients and 9 inert ingredients. TPTH is not 

among the group of 58 pesticide active ingredients on the initial list to be screened under the 

EDSP. Accordingly, as part of registration review, EPA will issue future EDSP orders/data callins, requiring the submission of EDSP screening assays for TPTH. For further information on 

the status of the EDSP, the policies and procedures, the list of 67 chemicals, future lists, the test 

guidelines and the Tier 1 screening battery, please visit our website9

. 

HUMAN STUDIES:

Occupational 

Past TPTH risk assessments rely in part on data from studies in which adult human subjects were 

intentionally exposed to a pesticide to determine their dermal and inhalation exposure. Many 

such studies, involving exposure to many different pesticides, comprise generic pesticide 

exposure databases such as the Pesticide Handlers Exposure Database (PHED) and the 

Agricultural Reentry Task Force (ARTF) Database. EPA has reviewed all the studies supporting 

these multi-pesticide generic exposure databases, and has found no clear and convincing 

evidence that the conduct of any of them was either fundamentally unethical or significantly 

deficient relative to the ethical standards prevailing at the time the research was conducted. All 

applicable requirements of EPA’s Rule for the Protection of Human Subjects of Research (40 

CFR Part 26) have been satisfied, and there is no regulatory barrier to continued reliance on 

these studies. 

 

9 http://www.epa.gov/endo/