2 

### Table of Contents

Contents
I. Introduction

................................ ................................ ................................ .............................. 3

II. Use and Usage

................................ ................................ ................................ .......................... 5

III. Scientific Assessments

................................ ................................ ................................ ............ 5
A. Human Health Assessment

................................ ................................ ................................ ..... 5
1. Hazard Characterization and Risk

................................ ................................ ................. 6
2. Risk Conclusions

................................ ................................ ................................ ........... 6
3. Tolerances

................................ ................................ ................................ ...................... 7
4. Human Incidents

................................ ................................ ................................ ............ 7
B. Environmental Assessment

................................ ................................ ................................ .... 7
1. Public Comments

................................ ................................ ................................ ........... 7
2. Environmental Fate and Exposure

................................ ................................ ................. 8
3. Ecological Risk Assessment Uncertainties

................................ ................................ .... 9
4. Ecological Risk Characterization

................................ ................................ .................. 9
5. Overview of Ecological Risk Conclusions

................................ ................................ .... 9

6. Effects on Terrestrial Organisms

................................ ................................ ................. 10

7. Effects on Aquatic Organisms

................................ ................................ ..................... 10
8. Ecological Incidents

................................ ................................ ................................ .... 10
9. E cological Risk Management Conclusions for Non

- Listed Species

........................... 11
C. Endangered Species Assessment

................................ ................................ .......................... 11

D. Endocrine Disruptor Screening Program

................................ ................................ ............. 13

IV

. Proposed Interim Registration Review Decision

................................ ................................ 14

V. Next Steps and Timeline

................................ ................................ ................................ ..... 14
A. Interim Registration Review Decision

................................ ................................ .................. 14

B. Im plementation of Mitigation Measures

................................ ................................ ............... 15 Appendix A: Summary of Actions Taken for Trinexapac

- ethyl

................................ .................. 1 6 Appendix B: Trinexapac

- ethyl Label Table

................................ ................................ ................. 173



### I. Introduction

This document is the Environmental Protection Agency’s (EPA or the Agency) Proposed Interim Registration Review Decision for trinexapac

- ethyl ( PC Code 112602, Case 7228) and is being issued pursuant to 40 CFR sections 155.56 and 155.58

. A registration review decision is the Agency's determination whether a pesticide meets, or does not me et, the standard for registration in the Federal Insecticide, Fungicid e, and Rodenticide Act (FIFRA). The Agency may issue, when it determines it to be appropriate, a proposed interim registration review decision before completing a registration review. Among other things, the proposed interim registration review decision may require new risk mitigation measures, impose interim risk mitigation measures, identify data or information required to complete the review, and include schedules for submitting the required data, conducting the new risk assessment and completing the registration review. For further information on trinexapac

- ethyl , additional documents can be found in EPA’s public docket (EPA

- HQ

- OPP

- 200 8

- 0 657 ) at www.regulations.gov

. FIFRA, as amended by the Food Quality Protection Act (FQPA) of 1996, mandated the continuous review of existing pesticides. All pesticides distributed or sold in the United States generally m ust be registered by the EPA based on scientific data showing that they will not cause unreasonable risks to human health or to the environment when used as directed on product labeling. The registration review program is intended to make sure that, as th e ability to assess and reduce risk evolves and as policies and practices change, all registered pesticides continue to meet the statutory standard of no unreasonable adverse effects. Changes in science, public policy, and pesticide use practices will occ ur over time. Through the registration review program, the Agency periodically reevaluates pesticides to make sure that as these changes occur, products in the marketplace can continue to be used safely. Information on this program is provided as www.epa.gov/oppsrrd1/registration_review/

. In 2006, the Agency implemented the registration review program pursuant to FIFRA section 3(g) and will review each registered pesticide every 15 years to determine whether it continues to meet the FIFRA standard for registration.

Trinexapac

- ethyl is a plant growth regulator registered for use on tur f grass , several cereal grain crops , and sugarcane

. On turf grass, trinexapac

- ethyl reduces the frequency of mowing , and on crops it reduces the problem of lodging (stalk bending or breakage) before harvesting

. On sugarcane, it maintains or increases the sugar content and induces internode shortening and harvest extension. It is formulated as an em ulsifiable concentrate, granular, liquid, micro

- encapsulated, and wettable powder and applied via chemigation and broad cast (aerial and ground) spray. It was first registered in 19 93 for the management of warm and cool season turf grasses. Trinexapac

- eth yl is registered for commercial and residential use

. A Reregistration Eligibility Decision document (RED) for trinexapac

- ethyl was not completed because it was registered after 1984.

Pursuant to 40 CFR section 155.50, EPA formally initiated registration review for trinexapac

- ethyl (case 7228 )

. The following highlights significant events that have occurred during the registration review of trinexapac

- ethyl :4

 September 15, 2008

– Publication of trinexapac

- ethyl Summary Document for a 60

- day public comment period

. The Summary Document included the P reliminary W ork P lan (PWP) and was accompanied by the scoping document and problem formulation.

 February 18, 2009

– Final Work Plan (FWP) for trinexapac

- ethyl was issued . N o public

comm ents were received during the 60

- day comment period for the Trinexapac

- ethyl PWP; thus

, the FWP did not modify the PWP.

 March 11, 2010

– Generic Data Call

- In (GDCI) for trinexapac

- ethyl issued.

 September 27, 2013

– The Agency published the Registration Review

- Ecological Risk Assessment and Effects Determination of Trinexapac

- ethyl and the Trinexapac

- ethyl: Human Health Risk Assessment for Registration Review for a 60

- day public comment period. Two sets of comments concerning the ecological risk assess ment were received during the comment period ; no comments were received about the human health risk
assessment

.

 July 201 4

– The Agency is now publishing the Response to Comments on the Preliminary Ecological Risk Assessment for the Registration Review of Trinexapac

- ethyl and Use/Usage Refinement in Support of Registration Review of Trinexapac

- ethyl

.

 Ju ly 2014

– The Agency is now publishing the Trinexapac

- ethy l Proposed Interim Registration Review Decision , dated June 2014 in docket number EPA

- HQ

- OPP

- 2008

- 0657 for a 60

- day public comment period.

Additional information on trinexapac

- ethyl can be found in EPA’s public docket

, EPA

- HQ

OPP

- 2008

- 0657 , accessed at www.regulations.gov

.5



### II. Us e and Us age

As described in the June 2014 Use/Usage Refinement in Support of Registration Review of Trinexapac

- ethyl available in the trinexapac

- ethyl docket , trinexapac

- ethyl is a plant growth regulator (PGR) registered for use by homeowners and professional applicators to manage growth of turf grass, wheat, barley, oats, triticale, sugarcane, and grasses grown for seed. Turf grass uses include golf courses, sod farms, commercial and residential lawns, athletic fields and parks. It is also registered for application around ornamental trees, shrubs, and flower beds

. Trinexapac

- ethyl inhibits the biosynthesis of the phytohormone gibberellin that promotes growth of turf grasses , redu cing the frequency of mowing. Also, in turf grass, trinexapac suppresses seed head formation. In cereal grains, it reduces the length of internodes, which produces sturdier plants and reduces the problem of lodging before harvesting, minimizing yield los s. On sugarcane, it maintains or increases the sugar content for an extended harvest window and induces internode shortening to improve seed piece production

. Trinexapac

- ethyl is reported to be widely used in professional turf and horticulture
managemen t , which includes golf courses, institutional turf facilities, turf farms, as well as professional lawn care and landscape management

. In 2011, approximately 90,000 lbs of
t rinexapac

- ethyl were applied, accounting for over 30% of total PGR usage in profes sional turf and horticulture management

. Golf courses account for the majority of usage; it is reportedly the second most commonly used PGR on golf courses, accounting for over 60,000 lbs active ingredient (a.i ) annually

. While fewer total pound s of trinexapac

- ethyl are used on institutional turf facilities (approximately 8,000 lbs a.i. ), this accounts for over 55% of total PGR use in these facilities. Similarly, while use of PGRs on turf farms is quite limited, nearly 100% of the usage is accounted for by t rinexapac

- ethyl (less than 7,000 lbs a.i. ). Finally, low usage is reported among lawn care operators (less than 8,000 lbs a.i. , less than 7% of total PGR use), and landscape contractors (less than 500 lbs a.i.).

Publicly available data on trinexa pac

- ethyl usage are limited. Data from the California Department of Pesticide Regulation (CDPR) indicate approximately 5,200 lbs a.i. are applied annually in California, nearly all of which are applied in landsc ape maintenance. Trinexapac

ethyl is also us ed in less than 1% of cut flow er and bedding plant operations.



### II I

. Scientific Assessments

A. Human Health Assessment

A summary of the Agency’s human health risk assessment is presented below. The Agency used the HED scoping document, its supporting do cuments, and the most updated Agency science policies and risk assessment methodologies to prepare a qualitative risk assessment in support of the registration review of trinexapac

- ethyl. The most recent human health r isk assessment was conducted on Septe mber 12, 2013

. The human health risk assessment consisted of upd ated acute and chronic dietary ( food and drinking water) exposure assessments, residential handler and post

- application exposure assessments, an aggregate exposure assessment, and occupationa l handler and post

- app lication exposure assessments. Risk estimates were below the Agency's level of concern for all hu man health scenarios assessed. For a detailed6

discussion, see the Trinexapac

- ethyl: Human Health Risk Assessment for Registration Review

, published on September 27, 2013 in the public docket EPA

- HQ

- OPP

- 2008

- 0657

, which can be accessed on http://www.regulations.gov/

.

1. Hazard Characterization and Risk

The acute toxicity for trinexapac

- ethyl technical formulation is relatively low, and was classified as Toxicity Category II for acute oral, dermal, and eye irritation, and IV for acute inhalation and skin irritation. Trinexapac

- ethyl is not a skin sensitizer. Trinexapac

- ethyl is a low acute toxicity chemical with systemic effects occurring at or well above 300 mg/kg/day in subchronic and lifetime dosing studies. E vidence of increased qualitative and quantitative susceptibility to offspring exists at or above the limit dose (3 00

– 1,000 mg/kg/day) of the developmental and reproductive studies

. Qualitative sensitivity was observed in the 2

- generation reproduction study but only above the limit dose (1,000 mg/kg/day). Reproductive toxicity was not observed up to the limit dose

.
The combined chronic toxicity/carcinogenicity study in the rat did not demonstrate an increase in any tumor type that would be relevant to humans. In the mouse, there was no evidence of carcinogenicity. The mutagenicity database is complete, with no evidence of mutagenicity. The cancer classification for trinexapac

- ethyl is “Not likely to be carcinogenic to humans.”

In adult animals, no systemic adverse effects were seen in rats, rabbits, or mice below the limit dose (1

, 000 mg/kg/day) following subchronic or chronic oral exposure. The 90

- day subchronic dog study showed decreased body weight gain and food consumption, diffuse thymic atrophy, and changes in the epithelial cells of the renal tubules were seen in the 90

- day dog study at 516/582 mg/kg/day (males/females). Similar lesions were not observed in the rat or mouse following subchronic or chronic dietary exposure, and there was no other evidence in any other species tested to indicate a neuroto xicity potential.

There was no evidence of neurotoxicity in the acute and chronic neurotoxicity studies in rat at the highest dose tested of 2000 mg/kg and 948/1171 mg/kg/day (male/female), respectively. The toxicity database for trinexapac

- ethyl is complete under the rev ised 40 CFR Part 158 data requirements for conventional pesticides.

2. Risk Conclusions The Agency conducted dietary, occupational, aggregate, and residential risk assessments to support the registration review of trinexapac

- ethyl. No risk estimates exceeded the Agency’s level of concern (LOC) for existing uses of trinexapac

- ethyl. It has not been determined that trinexapac

- ethyl shares a common mechanism of toxicity with other chemicals; therefore a cumulative risk assessment was not required.

In the most re cent human health risk assessment, t he Agency indicated that a 30

- day plant

- back restriction was needed on labels for cereal grains, as well as a prohibition of planting all other crops not listed on the label. However, c omments received by Syngenta Crop Protection, LLC on the human health risk assessment referred to a previously submitted and reviewed rationale supporting a 0

- day plant

- back interval for crops currently on the label and a7

30

- day interval for all other crops

. The rationale indicated that r esults of the confined accumulation in a rotational crop study (MRID 48043709) support ed a 0

- day plant

- back interval for crops on the labels and a 30

- day plant

- back interval for all crops not on the label

. The Agency accepted this rationale in a memorandu m dated February 17, 2012 , now available in the trinexapac

- ethyl registration review docket (EPA

- HQ

- OPP

- 2008

- 0657 ). Therefore

, a 0

- day plant

- back interval for crops currently on the label and a 30

- day interval for all other crops is supported. L abel changes to the plant

- back interval are not required.

3. Tolerances

Tolerances are currently established for residues of trinexapac

- ethyl, including its metabolites and degradates, in or on plants and livestock in CFR 40 180.662. There are no established or proposed Codex, Canadian , or Mexican maximum residue limits (MRLs) for trinexapac

- ethyl in or on any food or feed crops.

4. Human Incidents

A small number of minor human health incidents have been reported to the Agency involving trinexapac

- ethyl. From Janu ary 1, 2009 to May 27, 2014, there were 3 incidents reported to th e Office of Pesticide Program’s Main Incident Database System. These incidents were classified as moderate severity. A query of SENSOR

- Pesticides 1998

- 2009 identifies a total of eight cases , stemming from eight events, involving trinexapac

- ethyl. All cases were low in severity. Five cases involved multiple active ingredients and three involved a single active ingredient. These three cases were low in severity. The reported incidents do n ot suggest there is risk from the current uses of trinexapac

- ethyl when used as directed by labels. The Agency has determined that the reported incidents are not of concern, but will continue to monitor the incident information and if a concern is triggere d, additional analysis will be conducted.

B. Environmental Assessment

The risk assessment supporting this P roposed I nterim R egistration R eview D ecision evaluates risks to species that are not subject to the Endangered Species Act (ESA) and provides

a screening level assessment for potential risk s to listed species under ESA

. A summary of the Agency’s environmental risk assessment for trinexapac

- ethyl is presented below. For detailed discussions of all a spects of the environmental risk assessment, see the Registration Review

- Ecological Risk Assessment and Effects Determination of Trinexapac

- ethyl

, published on September 27, 2013 in the public docket EPA

- HQ

- OPP

- 2008

- 0657

, which can be accessed on http://www.regulations.gov/

.

1. Public Comments

During the public comment period, the Agency received comments about the ecological risk assessment from Syngenta Crop Protection, LLC (Syngenta) , and Crop Life America (CLA)

. Syngenta ’s comments on the prelimi nary ecological risk assessment focused on conservative assumptions made in the review of submitted data and subsequent risk assessment. These
comments are addressed in detail in the Response to Public Com ment on the Trinexapac

- ethyl8

Registration Review Ecological Risk Assessment

, dated June 3, 2014, available in the public docket EPA

- HQ

- OPP

- 2008

- 0657.

One comment from Syngenta resulted in a change to the ecological risk assessment. Syngenta stated th at the default half

- life value of 35 days for turf uses was overly conservative and did not accurately represent the environmental fate of trinexapac

- ethyl on turf. Syngenta noted that submitted studies (MRIDs 48043710, 48043711, 41869539, and 41869540) s upport a shorter half

- life value of <1 day for trinexapac

- ethyl turf scenarios. After review, the Agency agrees that the referenced studies do support a foliar dissipation half

- life of 1.383 days, the 90 th percentile half

- life estimate of the submitted st udies, on turf scenarios excluding grasses grown for seed. The Agency’s findings after revising the terrestrial risk assessment are presented in the Response to Public Comments on the Trinexapac

- ethyl Registration Review Ecological Risk Assessment

.

CLA commented that the draft risk assessment for trinexapac

- ethyl compared screening level estimates of exposure to the l isted species level of concern . CLA further stated that screening tiers indicate whether a potential risk exists, but additional refinemen ts to reduce uncertainties would indicate whether a risk of concern actually exists. CLA stated that risk mitigation decisions for listed species should not be considered until all data gathering and refinements have been completed to indicate what the ri sks actually are.

EPA appreciates and acknowledges CLA’s comments about the preliminary ecological risk assessment for trinexapac

- ethyl. EPA would like to reaffirm its interest in engaging in mitigation discussions with affected stakeholders as early as possible during registration review. EPA recognizes that in the case of listed species assessments, mitigation discussions may be most fruitful once the listed species assessment process has further matured. However, EPA believes that the Preliminary Ri sk Assessment (PRA) is an appropriate place in registration review to discuss potential risks of concern and risk mitigation as determined under FIFRA. Further, EPA notes that it is in the interests of stakeholders to engage at the earliest possible point in registration review to discuss risk mitigation, even prior to a potential listed species risk
assessment. As per th e Stakeholder Engagement Paper ( www.epa.gov/pesticides

/oppfead1/endanger/archive

- 2013.html ), early engagement by stakeholders allows EPA to focus on potential risks of concern to listed and non

- listed species identified either via litigation or risk assessments conducted to support prior regulatory decisions. It may be possible to achieve “early risk reductions” as a result of alternative chemistries developed since the previous risk assessments were conducted, changes to labels that incorporate rate reductions, clarifications to use instructions, and/ or exis ting conservation practices. Early risk reductions have the potential to narrow the scope of any necessary risk assessment for listed speci es, saving time and resources. For more information on the endangered species risk assessment process and screening level assessment specific to trinexapac

- ethyl, please see the “Endangered Species Assessment” section of this document.

2. Environmental Fate and Ex posure

Trinexapac

- ethyl is considered to be moderately mobile to mobile in soil, while its major metabolite, trinexapac acid, is moderately mobile in soil. Trinexapac

- ethyl is not expected to9

accumulate in aqua tic or terrestrial food chains. Trinexapac

- ethyl is not volatile and , therefore, is not likely to be transported via atmospheric processes following application.

The primary route of degradation for trinexapac

- ethyl is biodegradation in aerobic and anaerobic water bodies and aerobic terrestrial environments. Half

- lives r anged between 2.8 hours and 4.3 days, depending on the microbial environment of the application site. However, biodegradation was slower under anaerobic soil conditions. The estimated half

- life is 25 days in a sandy loam soil. Trinexapac

- ethyl is suscepti ble to hydrolysis under basic conditions. I n addition, photolysis does not appear to be a major degradation pathway in aqueous and soil environments.

3. Ecological Risk Assessment Uncertainties

While there are toxicity data gaps for some species, the database for trinexapac

- ethyl is considered substantially complete and sufficient for risk assessment a nd regulatory decision making. Subsequent to the completion of the preliminary risk assessment, Syngenta submitted an acute honeybee oral toxicity study to address uncertainty identified in the EPA’s 2013 ecological preliminary risk assessment for potential risk to non

- target terrestrial invertebrates

, such as bees. While risks of concern were not identified for non

- listed terrestrial invertebrates, this study will be reviewed prior to the completion of an endangered species risk assessment for trinexapac

- ethyl.

4. Ecological Risk Characterization

To estimate potential ecological risk, EPA integrates the results of exposure and ecotoxicity studies using the risk quotient method. Risk quotients (RQs) are calculated by dividing acute and chronic estimated environmental concentrations (EECs) by ecotoxicity values for various wildlife and plant species. RQs are then compared to levels of concern (LOCs) and when the RQ exceeds the LOC for a particular category, the Agency evaluates the potential for a risk of concern to that category. Risk characterization provides further information about potential adve rse effects and the possible impact of those effects by considering the fate of the chemical a nd its degradates in the environment, organisms potentially at risk, and the nature of the effects observed.

5. Overview of Ecological Risk Conclusions

Conservati ve assumptions were made in the conduct of the ecological risk assessment for trinexapac

- ethyl to estimate the ecological risks (e.g

. risk estimates are ba sed on the maximum application rates and number of applications rather than typical rates and the mos t sensitive endpoint s from toxicity studies applications ). RQs were below the screening level LOCs for nearly all trinexapac

- ethyl use scenarios, with only several turf and grasses grown for seed scenarios resulting in RQs slightly above the LOC. A n acut e RQ exceedance of 0.52 was identified for non

- listed small (20 g) birds from granular turf use at the highest application rate, just above the LOC of 0.50. Similarly, RQ exceedances above the LOC of 1.0 ranged from 1.15

- 1.70 for non

- listed terrestrial pl ants from liquid turf and grasses grown for seed uses. There were no acute or chronic risks to non

- listed terrestrial species identified as a result of the use of trinexapac

- ethyl on cereal grains or sugarcane.10 6. Effects on Terrestrial Organisms

The primary route of exposure for terrestrial organisms is the dietary route, from consumption of food items, such as plant leaves or insects that have trinexapac

- ethyl residues as a result of spraying, or from the ingestion of trinexapac

- ethyl granules. Direct contact and spray drift are the major routes of exposure assumed for terrestrial and riparian plants.

Mammals

There were no acute or chronic risks of concern for non

- listed mammals or terrestrial invertebrates from the registered uses of trine xapac

- ethyl

.

Birds

Direct effects to non

- listed terrestrial birds (surrogates for reptiles and amphibians) were identified for turf uses. O ne scenario exceeded the acute LOC and one scenario exceeded the chronic LOC ; as explained below, both exceedances were minimal . For granular turf uses (assuming the highest registered use rate) the acute RQ for small (20g) birds was 0.52

, an exceedance of the LOC of 0.5. For the liquid turf uses, t he chronic

- dietary

- based RQ fo r a bird eating a diet of s hort grass only was 1.2, which minimally exceed ed the chronic dietary

- based LOC of 1.0. However, RQs for liquid turf scenarios were recalculated after replacing the default foliar half

- life va lue of 35 days with 1.383 days and presented in the Response to Comments on the Preliminary Ecological Risk Assessment for the Registration Review of Trinexapac

- ethyl

. As a result of this change, the chronic

- dietary

- based RQ for birds decreased from 1.2 to 0.83 and is now below the LOC

.

Plants

For non

- listed terre strial and riparian plants, RQ exceedances rang ed from 1.15

- 1.70 as a result of trinexapac

- ethyl use on grasses grown for seed (dicot plants only) and turf use

. No risks were identified as a result of trinexapac

- ethyl cereal grain uses.

7. Effects on Aquatic Organisms

The primary route of exposure to aquatic organisms is through direct contact with the water column, sediment, and pore water with residues from spray drift and/or runoff from areas treated with trinexapac

- ethyl. A cute and chronic risk estimates were below the LOC for freshwater and estuarine/marine fish (surrogates for aquatic

- phase amphibians)

, freshwater and estuarine/marine invertebra tes , and aquatic vascular and non

- vascular plants for all uses of trinexapac

- ethyl

. Therefore, no ri sks of concern are anticipated for non

- listed aquatic organisms based on the registered uses of trinexapac

- ethyl.

8. Ecological Incidents

A review of the Ecological Incident Information System (EIIS), the Aggregate Summary Module of the Office of Pesticide Program’s Incident Database, and the Avian Monitoring Information System (AIMS), which is maintained by the American Bird Conservancy, was11

conducted on May 16, 2013 for trinexapac

- ethyl. Neither the EIIS nor the AIMS database identified any adverse ecolo gical incidents involving trinexapac

- ethyl. Two aggregate incident summaries were documented in OPP’s Incident Database. One incident was reported as a minor fish and wildlife incident in 2000, the other was reported as a minor plant incident in late 200 3 or 2004. No other information was available.

9. Ecological Risk Management Conclusions for Non

- Listed Species

The preliminary risk assessment for trinexapac

- ethyl identified an acute LOC exceedances for non

- listed terrestrial birds at 0.62 and plants varying from 2.3

- 3.40 for the turf grass use; which was assessed at a single maximum application rate of 1.36 lb active ingredient/ Acre (a.i./A). However, the registered single maximum application rate for use on turf grass is intended to be 0.88 lb a.i. /A for granular products, and 0.68 lb a.i./A for liquid products, but a statement on end

- use liquid turf grass product labels also states that “for extended growth suppression up to 8 weeks, where temporary discoloration can be tolerated, a maximum of twic e the recommended rate from the application rate table may be applied.” Therefore, risks were assessed at twice the intended single maximum application rate to account for this statement on end

- use labels. EPA is working with the trinexapac

- ethyl technic al registrants to amend their labels to clarify that the single maximum application rate for liquid end

- use products registered for use on turf grass is 0.68 lb ai/A, by requiring the following proposed label language: “ T he single maximum appl ication rate must not exceed 0.6 8 lb ai/A. DO NOT double the single maximum application rate for extended suppression ”. Amended labels for technical and liquid end

- use products registered on turf grass must be submitted to the Agency for approval within 60 days of the publication of the final Interim Registration Review Decision for the registration review of trinexapac

- eth yl. Therefore, once these changes to labels are made, risks identified as a result of the doubled single maximum application rate for liquid turf grass products would no longer be of concern.

Based on the low risk estimates, the anticipated clarification of the maximum single application rate for liquid turf uses, and the conservative nature of the risk assessment ( e.g., risk estimates are ba sed on maximum application and the most sensitive endpoint s from toxicity studies), the Agency does not anticipate ecological risks of concern for assessed taxa from currently registered uses of trinexapac

- ethyl

.
C. Endangered Species Assessment

Before completing this Registration Review, the Agency will conduct an ecological risk assessment to address the Agency’s obligations under both the Endangered Species Act (ESA) and FIFRA. While the risk asses sment supporting this P roposed I nterim Registration Review D ecision evaluates risks to species that are not subject to the ESA, EPA is still in the process of conductin g a risk assessment for endangered and threatened (listed) species and their designated critical habitats for trinexapac

- ethyl. In this P roposed I nterim Registration Review D ecision, therefore, EPA has not completed effects determinations for listed speci es associated with the registered uses of trinexapac

- ethyl

.
In November 2013, the EPA, along with the U.S. Fish & Wildlife Service (USFWS), the National Marine Fisheries Service (NMFS) (collectively, the Services) , and the U.S. D epartment12

of Agriculture (USDA) released a summary of their joint Interim Approaches for assessing risks to listed species from pesticides. The “ Interim Approaches for National

- Level Pesticide Endangered Species Act Assessments Based on the Recommendations of the National Academy of Sciences April 2013 Report” ( Interim Approaches ), dated November 1, 2013, were developed jointly by the a g encies in response to the N ational A cademy of S ciences’ (NAS) recommendations and reflect a common approach to risk assessment shared by the a genc ies 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 developme nt of pesticide risk assessments that EPA and the Services must conduct in connection with their obligations under the Endangered Species Act (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 P esticide P rogram D ialogue C ommittee (PPDC) and S tate

- FIFRA Issues Research and Evaluation Group ( SFIREG ) meetings, and held a stakeholder workshop in April 2014, allowing additional opportunities for stakeholders to comment on the Interim Approaches. As part of a phased, iterative process for developing the Interim Approaches, the agencies will also consider public co mments on the Interim Approaches in connection with the development of upcoming Registration Review decisions. The details o f the joint Interim Approaches are contained in the Interim Approaches white paper

. 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 risk assessment support ing this Proposed Interim Registration Review Decision for trinexapac

- ethyl does not contain a complete ESA analysis that includes effects determinations for specific listed species or designated critical habitat

. Although EPA has not yet completed effect s determinations for specific species or habitats, for this preliminary assessment EPA conducted a screening

- level assessment for all taxa of non

- target wildlife and plants that assumes for the sake of the assessment that listed species and designated crit ical habitats may be present in the vicinity of the application of trinexapac

- ethyl . 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 regulatory section of the Proposed Interim Registration Review Decision document will describe the level of ESA analysis c ompleted 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 habitat s, these methods will be applied to subsequent analyses for trinexapac

- ethyl as part of completing this registration review.

As part of the screening level assessment, t he Agency has made several refinements to the list of endangered and threatened speci es that may be affected by trinexapac

- ethyl sugarcane, and grasses grown for seed . The following refinement does not apply to turf grass uses. To date, there are 1421 listed species identified in the LOCATES database (v. 2.2.7 , derived from USFWS and NMF S). For sugarcane and grasses grown for seed uses , a “no effect” determination for 342 of the species for direct and indirect effects can be made based on a lack of geographical overlap, based on a county level of resolution, between the species and trinexapac

-13

ethyl uses. A further 46 species can be eliminated from consideration of direct effects based on species specific ecological and biological information from listed species trustee agencies. There are 794 species that will need to be considered in more depth before direct effects calls are made for the sugarcane and grasses grown for seed uses. Biological, geographical, and use pattern information will be necessary to further refine the assessment.

D. 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, neurotoxici ty, 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 maturati on, 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 most recent registration decision for trinexapac

- ethyl

, 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),
t rinexapac

- ethyl 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 hu mans 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 consis ts of a battery of 11 screening assays to identify the potential of a trinexapac

- ethyl 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 potent ial 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 issue d test orders/data call

- ins for the first group of 67 chemicals , which contains 58 pesticide active ingredients and 9 inert ingredients. A second list of chemicals identified for EDSP screening , which included trinexapac

- ethyl, was published on June 14, 20 13 1 and includes some pesticides scheduled for Registration Review and chemicals found in water. For further information on the status of the EDSP, the policies and procedures, the lists of chemicals , future lists, the test guidelines and the Tier 1 scre ening battery, please visit our website. 2

1 See http://www.regulations.gov/#!documentDetail;D=EPA

- HQ

- OPPT

- 2009

- 0477

- 0074 for the final second list of chemicals.

2 http://www.epa.gov/endo/14

In th is Proposed I nterim Registration Review Decision , EPA is making no human health or environmental safety findings associated with the EDSP screening of trinexapac

- ethyl . Before completing this Registration Review, the Agency will make an EDSP FFDCA section 408(p) determination.



### IV

. Proposed Interim Registration Review Decision

In accordance with 40 CFR Sections 155.56 and 155.58, the Agency is issuing this P roposed I nterim R egistration R eview D ecision

. EPA’s P roposed Registration Review Decision

. Except for the EDSP and Endangered Species Act (ESA) components of the trinexapac

- ethyl registration review case, the Agency has made the following interim decision: (1) no additional data are required at this time; and (2) changes are required to trinexapac

- ethyl products registered for use on turf grass

. The Agency has been working with the technical registrants for trinexapac

ethyl, and the registrants of all technical and end

- use products registered for use on turf grass will submit revised labels to clarify the single maximum application rate for turf grass application

. In the interim, EPA is making no human health or environmental safety findings associated with the EDSP screening of trinexapac

- ethyl. Before completing this Registration Review, the Agency will make an EDSP FFDCA section 408(p) determination. Likewise, before completing this Registration Review, the Agency will conduct an ecological risk assessment to address t h e Agency’s obligations und er both the Endangered Species Act (ESA) and FIFRA. While the risk assessment supporting this P roposed I nterim Registration Review D ecision evaluates risks to species that are not subject to the ESA, EPA is still in the process of conducting a risk assess ment for endangered and threatened (listed) species and their designated critical habitats for trinexapac

- ethyl. In this P roposed Interim Decision , therefore, EPA has not completed effects determinations for listed species associated with the registered uses of trinexapac

- ethyl. The Agency is issuing a P roposed I nterim R egistration Review Decision pending completion of the ESA and EDSP assessments

.


### V. Next Steps and Timeline

A. Interim Registration Review Decision

A Federal Register N otice will announce the availability of this P roposed I nterim R egistration R eview D ecision for trinexapac

- ethyl and allow a 60

- day comment period

. If there are no signi ficant comments or additional information submitted to the docket during the comment period that leads the Agency to change its decision, EPA may issue a n I nterim R egistration R eview D ecision for trinexapac

- ethyl (case 7228 ). However, a final decision for trinexapac

- ethyl may be issued without issuing an interim decision. A final decision on the trinexapac

- ethyl registration review case will occur after ESA and EDSP FFDCA section 408(p) determination s ha ve been mad e.15

B. Implementation of Mitigation Measures

Within 60 days following issuance of the final Interim Registration Review Decision

, registrants are to submit to the Agency for review and approval proposed amended labels that include the risk mitigation to clarify single maximum application rates for end

- use turf grass products

. The mitigatio n measures and required label amendments are described in Appendi ces A and B below.Docket Number EPA

- HQ

- OPP

- 2008

- 0657

www.regulations.gov

16 Appendix A: Summary of Actions Taken for Trinexapac

- ethyl

Registration Review Case#: 7228 PC Code: 112602 Trinexapac

- ethyl Type : Plant growth regulator Trinexapac

- ethyl Family: N/A Mode of Action: Gibberellin inhibitor Affected Population(s) Source of Exposure Route of Exposure Duration of Exposure Risk of Concern Action(s) Taken Comment (use to briefly clarify or elaborate on risk or mitigation)  Terrestrial Plants  Residues on site of treatment)  Runoff

 Spray drift  Acute  Chronic  Direct

 Indirect  Clarify single maximum application rate for turf grass

 Birds  Residues on site of treatment)
 Dietary  Ingestion  Chronic  Direct  Clarify single maximum application rate for turf grass17

Appendix B: Trinexapac

- ethyl Label Table

Summary of Labeling Changes for Trinexap a c - ethyl Uses Description Amended Labeling Language for Trinexapac

- ethyl Use Products Placement on Label

Technical Products
Language to limit single maximum application rate for liquid turf grass products “For liquid end

- use turf products, the single maximum application rate must not exceed 0. 6 8 lb ai/A. DO NOT double the single maximum application rate for extended suppression

. ” Directio ns for Use

End Use Products Language to limit single maximum application
rate for liquid turf grass products For liquid end

- use turf products: “ T he single maximum app lication rate must not exceed 0.6 8 lb ai /A. DO NOT double the single maximum application rate for extended suppression

. ” “Directions for Use” under “Application Information” and “Recommended Application Rate” table
Language to limit single maximum application rate for liquid turf grass product s Remove the statement: “For extended growth suppression up to 8 weeks, where temporary discoloration can be tolerates, a maximum of twice the recommended rate from the Application Rate Table may be applied. “ “Directions for Use” under “Application Information”