Docket Number EPA-HQ-OPP-2008

-0657 www.regulations.gov



# Trinexapac-ethyl
Interim Registration Review Decision Case Number 7228

December 2014

Approved by:



### ~~p **~~,:J:>** 

### Richard P. Keigwin, Jr. Director Pesticide Re-evaluation Division

Date: /.;J.

- !) -/ '-/Table of Contents Contents I. Introduction .. . .. ... . .. .. .. . ... .. .. . ...... .. .. . ... . ... . .. .. .. .. .. .. .. .. .. . .. .. .. .. ... . ... . ... . ... .. .. . .. .. ... .. .. ... . .. .. .. ....... .. ... .. 3 II. Use and Usage . ....... . .. .. .. .. .. : .......................... ... . ... . ........ . ....................................................... 5 III. Scientific Assessments . ......................... . ... . ....... . .................................................................. 6 A. Human Health Assessment ................... . ... . ...... . ........ . ..................... . .... . .................... ...... ....... 6 1. Hazard Characterization and Risk .... . .......................... . ................................................. 6 2. Risk Conclusions .......................................................................................................... 7 3. Tolerances ... . ................................................................................................................. 7 4 . Human Incidents .. . ... .. . .. .. .. .. .. .. . ... . .. .. .. .. .. .. .. .. .. . ....... .. .. . .. .. ... . ... . ... . ... . ... . ... .. .. .. .. .. .. ... .. .. ... . 7 B . Env i ronmental Assessment ...... . ... . ... . ...... . ....................... . ... . ............... . ....... . ... . ... . ... . .... . ......... 8 1 . Envirorunental Fa te and Exposure ................................................................................ 8 2. Ecological Risk Assessment Uncertainties .......... . ........................................................ 8 3 . Ecological Risk Characterization ................................................................................. 8 4. Overview of Ecological Risk Conclusions .............................. ..................................... 9 5. Effects on Terrestrial Organisms ................................................. . .... . .. . ........................ 9 6. Effects on Aquatic Organisms ............................................................. . ..................... . 10 7. Ecological Incidents .............................. . ... . ... . ..................................................... . .... .. 1 0 8. Ecologica l Risk Management Conclusions for Non
- Listed Species .......................... 10 C. Endangered Species Assessment.. ............................................................ . ....... ...... ......... . 11 D . En docri ne Disrupter Screeni ng Program ...................................................................... ... 12 IV . Interim Registration Review Decision .............................................................................. . 13 V . Next Steps and Timeline ......................................................... . ............................................. 14 A. Interim Registration Review Decision.................................................................................. 14 B. Implementation of Mitigation Measures . .. .. .. .. .. . ... . ... . ... . ...... .. ... . ........................................... 14 A ppendi x A: Summary of**Action~** Taken for Trinexapac-ethyl .................................................. 15 Appendix B: Trinexapac-eth y l Label Table ................................................................................ . 16 2

### I. Introduction
This document is the Environmental Protection Agency's (EPA or the Agency) 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 meet, the standard for registration in the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). The Agency may issue, when it determines it to be appropriate, an interim registration

. review decision before completing a registration review. Among other things, the 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-2008-0657) at www.regulations.gov. FIFRA, as amended by the Food Quality Protection Act (FQPA) of 1996, mandated the continuous review ofexisting pesticides. All pesticides distributed or sold in the United States generally must be registered by the EPA based on scient ific 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 the ability to assess and reduce risk evolves and as policies and practices change, all registered pesticides continue to meet the statutory standard ofno unreasonable adverse effects. 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 these changes occur, products in the marketplace can continue to be used safely. Information on this program is provided as www.epa.gov/oppsrrd 1/registration review /.
In 2006, the Agency implemented the registrat ion 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 plan t growth regulator registered for use on turfgrass, several cereal grain crops, and sugarcane
. On turfgrass, trinexapac-ethyl reduces the frequency of mowing , and on crops it reduces the problem oflodging (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 emulsifiable concentrate, granular, liquid, micro

-encapsulated, and wettable powder and applied via chemigation and broadcast (aerial and ground) spray. It was first registered in 1993 for the management ofwarm and cool season turfgrasses. Trinexapac-ethyl is registered for commerCia l 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:

3• September 15 , 2008
- Publication of trinexapac -ethyl Summary Document for a 60-day public comment period. The Summary Document included the Preliminary Work Plan (PWP) and was accompanied by the scoping document and prob lem formu l ation. • February 18 , 2009
- Final Work Plan (FWP) for trinexapac-ethyl was issued. No public comments were received during the 60-day comment period fo r the Trinexapac

- ethy l PWP ; thu s, the FWP did not modify

**t~e** PWP. • March 11 , 2010
- Generic Data Call-In (GDCI) for trinexapac-ethyl issued. • September 27, 2013- The · Agency published the Registration Review- Ecological Risk Assessm ent and Effects Determination ofTrinexapac-ethyl and the Tri nexapac-ethyl:

Human Health Risk Assessment for Registration Review for a 60-day public comment period. Two sets of comments concerning the ecological risk assessment were received during the comment period; no comments were received about the human health risk assessment. • July 201 4- The Agency publi shed the Trinexapac-ethyl Proposed Interim Registration Review Decision for a 60 -da y public comment period and the Response to Comments on the Prelimin a ry Ecologica l Risk Assessment for the Registration Review ofTrinexapacethyl and Use/Usage Refinement in Support of Registration R evie w ofTrinexapac-ethyl. Several comments were received during the comment period. Two comments were received from Syngenta Crop Protection, LLC concerning the eco l ogical risk assessment. One comment was received from the Center for Biological Diversity regarding the Agency 's obligations under the Endangered Species Act. • December 2014
- The Agency is now publishing the Trinexapac-ethyl Interim Registration Review Decision and the Response to Comments on the Proposed Interim Decision for the Registration Review ofTrinexapac

- ethyl .

Additional information on tri nexapac-ethyl can be found in EPA 's public docket, EPA-HQOPP-2008-0657 , accessed at www.regulations.gov. Public Comments During the public comment period for the proposed interim decision, the Agency received comments from Syngenta Crop Protection , LLC and the Center for Biological Diversity. Syngenta's comments on the propo sed interim decision focused on conservative

assumpt ion s made in th e ecologica l risk assessment. These comments are addressed in detail in the Response to Public Com ment on the Trinexapac-ethyl Registration Review Proposed Interim Decision, dated November 18 ,20 14, available in the public docket EPA-HQ-OPP-2008-0657. Comment Recei v ed from the Center for Bi o logical Diversitv Comment: The Center for Biological Diversity 's (CBD) comments focus on the EPA ' s duty to consult with the US. Fish and Wildlife Service and the National Marine Fis h eries Service (the Services) on the registration review of trinexapac-ethyl in accordance with the ESA. The CBD 4comments mention various aspects of the risk assessmentprocess , including use of the best available data to develop endangeredspecies 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'spreliminary determinations regarding the effects of trinexapac-ethyl on endangered and threatened (listed) species and their designated critical habitat for the trinexapac-ethyl registration review. Response: EPA has reviewed the comments from CBD on the Trinexapac-ethyl Proposed Interim Registration Review Decision and plans to address many ofthe concerns raised by CBD as part ofthe implementation plan for assessing the risks ofpesticides to listed species based on the recommendations ofthe April2013 National Academy ofSciences (NAS) report. EPA will address concerns specific to trinexapac-ethyl in connection

**wi~h** the development ofits final registration review decision for this pesticide

. See Endangered Species Assessment on page 9 of this document for more information. 

### II. Use and Usage
As described in the June 2014 Use / Usage Refinement in Support of Registration Review ofTrinexapac-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 ofturfgrass, 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 applica tion around

**orn~ental** trees, shrubs , and flower beds. Trinexa pac-ethyl inhibits the biosynthesis ofthe phytohormone gibberellin that promotes growth ofturfgrasses, reducing the frequency ofmowing

. Also , in turfgrass, trinexapac suppresses seed head formation. In cereal grains, it reduces the length ofinternodes, which produces sturdier plants and reduces the problem oflodging before harvesting, minimizing yield loss. 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 horticultur e management, which includes golf courses, institutional turffacilities, turffarms, as well as professional lawn care and landscape management. 

### In 2011, approximately 90,000 lbs of trinexapac-ethyl were applied, accounting for over 30% oftotal PGR usage in professional turf and horticulture management. Golfcourses account for the majority ofusage ; it is reportedly the second most commonly used PGR on golfcourses, accounting for more than 60,000 lbs active ingredient (a.i) annually

. While fewer total pounds oftrinexapac-ethyl are used on inst itu tional turffacilities (approximately 8,000 lbs a.i.), this accounts for over 55% oftotal PGR use in these facilities. Similarly, while use ofPGRs on turffarms is quite limited, nearly 100% ofthe PGR use is trinexapac-ethyl (less than 7,000 lbs a.i.). Final)y, low usage is reported among lawn care operators (less than 8,000 lbs a.i., less than 7% oftotal PGR use), and landscape contractors (less than 500 lbs a.i.). Publicly available data on trinexapac-ethyl usage are limited. Data from the California Department ofPesticide Regulation (CDPR ) indicate approximately 5 ,200 lbs a.i. are applied annually in California, nearly all ofwhich are applied in landscape maintenance. Trinexapacethyl is also used in less than 1% ofcut flower and bedding plant operations. 

### 5III. Scientific Assessments A. Human Health Assessment A swnmary of the**Agen y~s**  human health risk assessmen t is presented below. The

Agency used the HED scoping document, its supporting documents, and the most updated Agency science policies and ris k assessment methodologies to prepare a qualitative risk assessment in support of the registration review of trinexapac-ethyl. The most recent human health risk assessment was con d ucted on September
· 12 , 2013. The h uman health risk assessment consisted of updated acute and chronic dietary (food and drinking water ) exposure assessments, residential handler and post-application exposure assessmen t s, an aggregate exposure assessment , and occupational handler and post-application exposure assessments . Risk estimates were below the Agency's level of concern for all human health scenarios assessed. For a detailed discussion, see the Trinexapac

- ethyl: Human Health Risk Assessment for Registration Review,

published on September 27, 2013 in the public docket EPA-HQ -O PP-2008-0657, which can be

accessed on http: // www .regulat i ons. gov / . 1. H azard Characterization and Risk The acute toxicity for trinexapac-ethyl technical formulation is rela t ively l ow, and was

classified as Toxicity Category II for acute oral , dermal, and eye irritation, and IV for acute inhala t ion and skin irritation. Trinexapac -e t hyl is not a skin sensit i zer. Trinexapac-ethy l is a low

acute toxicity chemica l with systemic effects occurring at or well above 300 mglkg/day in subchronic and lifetime dosing studies. Evidence of increased qualitative and quantitative

susceptibi lit y to offspring exists at or**abov~** the limit dose (300- 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 mglkg/day ) . Reproductive toxicity was not observed up t o the limit dos e . . The combined chronic toxicity/carcinogenicity study in the rat did no t 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 mutagenici t y. 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 mglkg/day) following subchronic or chronic oral exposure. The 90
- day subchronic dog study showed decreased body weight ga in 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 neurotoxicity 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 mglkg/day (male / female), 6respectively. The toxicity database for trinexapac-ethyl is complete under the revised 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 oftrinexapac-ethyl. No risk estimates exceeded the Agency's level ofconcern (LOC) for existing uses oftrinexapac-ethyl. It has not been determined that trinexapac

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

. In the most recent human health risk assessment, the Agency indicated that a 30-day plant-back restriction was needed on labels for cereal grains, as well as a prohibition ofplanting all other crops not listed on the label. However, comments received by Syngenta Crop Protection, LLC on the human health risk assessment referred to a previously subm itted and reviewed rationale supporting a 0-day plant-back interval for crops currently on the label and a 30-day interval for all other crops
. The rationale indica ted that results of the confined accumulation in a rotational crop study (MRID 48043709) supported 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 memorandum dated February 17, 2012, now available in the trinexa pac-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. Label changes to the plant-back interval are not required. 

### 3. Tolerances
Tolerances are currently established for residues oftrinexapac-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 ofminor human health incidents have been reported to the Agency involving trinexapac-ethyl. From January 1, 2009 to May 27, 20 14, there were 3 incidents reported to the 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 ofeight cases, stemming from eight events, involving trinexapac-et hyl. 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 not suggest there is risk from the current uses oftrinexapac

-ethyl when used as directed by labels. The Agency has determined that the reported incidents are not of c<, :mcern, but will continue to monitor the incident information and ifa concern is triggered, additional analysis will be conducted.

7B . Environmental Assessment The risk assessment supporting this Interim Registration Review Decision evaluates risks to species that are no t subject to the Endangered Species Act (ESA) and provides a screening level assessment for potential risks 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 aspects of the environmental risk assessment, see the Registration Review- Ecological Risk Assessment and Effects Determination ofTrinexapac-ethyl, published on September 27, 2013 in th e public docket EPA -H Q-OPP

- 2008 -06 57, wh i ch can be accessed on http:/ /www.regu l a t ion s.gov/. 1. Environmental Fate and Exposure Trinexapac-ethyl is considered to be moderately mobile to mobile in soil, while its major metabolite, trinexapac acid , is**mo~erately** mobile in soil. Trin exapac

- ethy l is not expected to accumulate in aquatic or terrestria l food chains. Trinexapac-ethyl is not volatile and, therefore, i s not likely to be transported via atmospheric processes following application. The primary route of degradation for trinexapac-ethyl is b i odegradation in aerobic and

anaerobic water bodies and aerobic terrestria l environments. Half
- lives ranged between 2.8 hour s and 4.3 days, depending on the microbial environment of the app li cation site. However, biodegradation was slower under anaerobic soil conditions. The estimated half-life is 25 days in a sandy loam soil. Trinexapac-ethyl is susceptible to hydrolysis under basic conditions. In addition , photolysis does not appear to be a major degradation pathway in aqueous and soi l environments. 2. E cological Risk Assessment Uncertainties Whi l e there are to xicity data gaps for some species, the database for trinexapac-ethyl is considered substantially complete and sufficient for risk assessment and regulatory decision making. Subsequent to the completion of the preliminary risk assessment, Syngenta submitted an acute honeybee oral tox i ci t y 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 trinexapacethyl. 3 . Ecological Risk Characterizat i on To estimate potential ecological risk, EPA integrates the results of exposure and ecotoxicity**stu~ies** using the risk quotient method. Risk quotients (RQs) are calcu la ted by dividing acute and chronic estimated environmental concentrations (EECs) by ecotoxicity values for various wild l ife 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 adverse effects and the possible impact of those effects by considering the fate of the 8chemical and its degradates in the environment, organisms potentially at risk, and the nature of the effects observed.


### 4. Overview ofEcological Risk Conclusions
Conservative assumptions were made in the conduct ofthe ecological risk assessment for trinexapac-ethyl to estimate the ecological risks (e.g., risk estimates are based on the maximum application rates and number ofapplications rather than typical rates and the most sensitive endpoints from toxicity studies applications). RQs were below the screening level LOCs for nearly all trinexapac

-ethyl use scenarios, with on ly several turfand grasses grown for seed scenarios resulting in RQs slightly above the LOC. An acute RQ exceedance of0.52 was identified for non-listed small (20 g) birds from granular turfuse at the highest application rate, just above the LOC of0.50. Similarly, RQ exceedances above the LOC of 1.0 ranged from 1.1 5- 1.70 for non-listed terrestrial plants from liquid turfand grasses grown for seed uses. There were no acute or chronic risks to non-listed terrestrial species identified as a result ofthe use of trinexapac-ethyl on cereal grains or sugarcane. 

### 5. Effects on Terrestrial Organisms
The primary route ofexposure for terrestrial organisms is the dietary route, from consumption offood items , such as plant leaves or insects that have trinexapac-ethyl residues as a result of spraying, or from the ingestion oftrinexapac-ethyl granules. Direct contact and spray drift are the major routes ofexposure assumed for terrestrial aJ?d riparian plants. Mammals
There were no acute or chronic risks ofconcern for non-listed mammals or terrestrial invertebrates from the registered uses oftrinexapac-ethyl.
Birds
Direct effects to non-listed terrestrial birds (surrogates for reptiles and amphibians) were identified for turfuses. One scenario exceeded the acute LOC and one scenario exceeded the chronic LOC; as explained below, both exceedances were minimal. For granular turfuses (assuming the highest registered use rate) the acute RQ for small (20g) birds was 0.52, an exceedance ofthe LOC of0.5. For the liquid turfuses, the chronic-dietary-based RQ for a bird eating a diet ofshort grass only was 1.2, which minimally exceeded the chronic dietary-based LOC of 1.0. However, RQs for liquid turf scenarios were recalculated after replacing the default foliar half-life value of 35 days with 1.383 days and presented ' in the Response to Comments on the Preliminary Ecological RiskAssessment for the Registration Review ofTrinexapac-ethyl. As a result ofthis change, the chronic-dietary-based RQ for birds decreased from 1.2 to 0.83 and is now below the LOC.

9Plants For non-listed terrestrial and riparian plants, RQ exceedances ranged from 1.15
- 1.70 as a result oftrinexapac

- ethyl use on grasses grown for seed (dicot plants only) and turf use. No risks were identified as a result oftrinexapac-ethyl cereal grain uses. 6. Effects on Aquatic Organisms The primary route of exposure to aquatic organisms is through direct contact with the water co l umn, sediment, and pore water with residues from spray drift and/or runoff from areas treated with trinexapac

- ethyl. Acute and chronic risk estimates were below the L OC for freshwater and estuar i ne / marine fish (surrogates for aquatic-phase amphibians), freshwater and estuarine/marine invertebrates, and aquatic vascular and non-vascular plants for all uses of trinexapac

- ethyl. Therefore, no r i sks of concern are anticipated fo r non
- listed aquatic organisms based on the registered uses oftrinexapac

- ethyl. 7 . Ecologica l Incidents A review of the Eco l og i cal Incident Information System (EllS), the Aggregate Summary

Module ofthe Office of Pesticide Program's Incident Database, and the Avian Monitoring Information System (AIMS), which is maintained by the American Bird Conservancy, was

conducted on May 16 , 2013 for trinexapac-ethyl. Neither the EllS nor the AIMS database identified any adverse eco l ogical 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 2003 or 2004. No other information was available. 8. Ecolog i cal Risk Management Conclusions for Non-Listed Spec i es The preliminary risk assessment for trinexapac

- ethyl identified an acute LOC exceedances for non
- listed terrestria l 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 l b 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 twice the recommended rate from the application rate table may be applied." Therefore, risks were assessed a t twice the intended single maximum application rate to account for this statement on end-use labels. EPA is working with the trinexapac-ethyl technical and end-use registrants to

amend their labels to clarify that the single maximum application rate fo r liquid end-use products registered for use on turf grass is 0 . 68 lb ai / A, by requiring the following proposed label language: "The sing l e maximum application rate must not exceed 0.68 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 Interim Registra t ion Review Decision for the registration review oftrinexapac

- ethyl. Therefore, once these changes to labels are made, risks 10identified as a result ofthe doubled single maximum application rate for liquid turfgrass products would no longer be ofconcern. Based on the low risk estimates, the label clarification ofthe maximum single application rate for liquid turfuses, and the conservative nature ofthe risk assessment (e.g., risk estimates are based on maximum application and the most sensitive endpoints from toxicity studies), the Agency does not anticipate ecological risks ofconcern for assessed taxa from currently registered uses oftrinexapac-ethyl. C. Endangered Species Assessment

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. Department ofAgriculture (USDA) released a summary ofthejoint Interim Approaches in the white paper "Interim Approaches for National-Level Pesticide Endangered. Species Act Assessments Based on the Recommendations ofthe Na tional Academy ofSciences April2013 Report," dated November 1, 2013.
The Interim Approaches were developedjointly by the agencies in response to the Nationa l Academy ofSciences ' (NAS) recommendations and reflect a common approach to risk assessment shared by the agencies as a way ofaddressing scientific differences between the EPA and the Services. The NAS report outlines recommendations on specific scientific and technical

. issues related to the development ofpesticide risk assessments· that EPA and the Services must conduct in connection with their obligations under the ESA and FIFRA.
Thejoint Interim Approaches were released prior to a stakeholder workshop held on November 15, 2013. In addition, the EPA presented thejoint Interim Approaches at the December 2013 Pesticide Program Dialogue Committee (PPDC) and State-FIFRA Issues Research and Evaluation Group (SFIREG) meetings, and held stakeholder workshops in April and October 2014, allowing additional opportunities for stakeholders to comment on the Interim Approaches. Additional workshops are planned to enhance stakeholder involvement. As part ofa phased, iterative process for developing the Interim Approaches, the agencies will also consider public comments on the Interim Approaches in connection with the development ofupcoming Registration Review decisions.
Given that the agencies are continuing to develop and work toward implementation ofthe Interim Approaches to assess the potential risks ofpesticides to listed species and their designated critical habitat, the ecological risk assessment sup porting this 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 effects determinations for specific species or habitats, for this preliminary assessment EPA conducted a screening

-level assessment for all taxa ofnon-target wildlife and plants that assumes for the sake ofthe assessment that listed species and designated critical habitats may be present in the vicinity ofthe application oftrinexapac-ethyl. Thi s screening level assessment will allow EPA to focus its future evaluations on the types ofspecies 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 , 11the regulatory section of the Interim Registration Review Decision document will describe the level of ESA analysis completed for this particular registration review case. Once the agencies have fully developed and implemented the scientific me thods 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 trinexapac-ethyl as part of completing

this registration review. As part of the screening level assessment, the Agency has made several refmements to the list of endangered and threatened species that may be affected by tr inexapac-ethyl sugarcane, and grasses grown for seed. The following refinement does not apply to turf grass uses. To date, there are 1421listed species identified in the LOCATES database (v. 2.2.7, derive d from USFWS and NMFS). For sugarcane and grasses grown for seed uses, a "no effect" determination for 342 of t he species for direct and indirect effects can be made based on a lack of geographical overlap, based on a county leve l of resolution, between the species and trinexapac-ethyl uses. A

further 46 species can be e liminated from consideration of direct effects based on species specific ecological and biological information from list ed species trus tee agencies. There are 794 s pecies that will need to be considered in more depth before direct effects calls are made for the s ugarcane and grasses grown for seed uses. Biological, geographical, and u se pa ttern information will be necessary to further refine the assessment. D. Endocrine Disruptor Screening Program As required by FIFRA and FFDCA 1 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

diff erent taxonomic groups. As part of its most recent registration decision for trinexapac-ethyl, EPA reviewed these data and selected the mos t sensitive endpoints for relevant ri sk assessment scenarios from t he existing hazard database. However, as required by FFDCA section 408(p ), trinexapac-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 ingred ien ts) may have an effect in human s 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 trinexapac-ethyl substance to int eract 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 nex t 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 i s designed to identify any adverse endocrine-related effects caused 12by the substance, and establish a dose-response relationship between the dose and theE, A, or T effect.
Under FFDCA section 408(p ), the Agency must screen
.all pesticide chemica ls. Between October 2009 and February 20 10, EPA issued test orders/data call-ins for the first group of67 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, 2013 1 and includes some pesticides scheduled for Registration Review and chemicals found in water. For further information on the status ofthe EDSP, the policies and procedures, the lists ofchemicals, future lists, the test guidelines and the Tier 1 screening battery, please visit our website

.2

In this Interim Registration Review Decision, EPA is making no human health or environmental safety fmdings 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. 

### Interim Registration Review Decision
In accordance with 40 CFR Sections 155.56 and 155.58, the Agency is issuing this Interim Registration Review Decision for

**trinexapac-~thyl.** Except for the EDSP and Endangered Species Act (ESA) components ofthe 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. As the Agency works toward implementing its Guidance for Assessing Pesticide Risks to Bees3

, additional data may be required for trinexapac-ethyl to assess non-target exposure to bees.
In the interim, EPA is making no human health or environmental safety fmdings associated with the EDSP screening oftrinexapac-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 the Agency's obligations under both the Endangered Species Act (ESA) and FIFRA. While the risk assessment supporting this Interim Registration Review Decision evaluates risks to species that are not subject to the ESA, EPA is still in the process ofconducting a risk assessment for endangered and threatened (listed) species and their designated critical habitats for trinexapac-ethyl. In this Interim Decision, therefore, EPA has not completed effects determinations for listed species associated with the registered uses oftrinexapac-ethyl. The Agency is issuing an Interim Registration Review Decision pending completion ofthe ESA and EDSP assessments.

1 See http://www
.regulations .gov /#! documentDetaii;D=EPA-HO-OPPT-2009-0477-0074 for the final second list of chemicals. 2 http://www.epa.gov /endo/ 3 http:// www2.epa.gov/sites/production/files/2014- 06/documents/pollinator risk assessment guidance 06 19 14.pdf. 13V . Next Steps and Timeline A. Inter i m Registration Review Decis i on A final decision on the trinexapac-ethyl registration review case will occur after ESA and EDSP FFDCA section 408(p) determinations have been made. B. Implementation of Mitigation Measures Registrants must submit amended labels that include the risk mit i gation t o clarify single maximum appl i cation rates for end
- use turf grass products to the Agency for approval within 60 days of publication ofthis Interim Decision. The mitigation measures and required label amendments are described in Appendices A and B below. 14**~ppendix** A: Summary of Actions Taken for Trinexapac-e thyl

Registration Revie w Case#: 7228

PC Code : 11260 2: rrrinexapac-ethyl T ype: Plant g ro wt h regulator

rr rine x apa c-et h y l Family: N/A

Mode of Action: Gibberellin inh ibito r Affected Population( s) Source of Exposure Route of Exposure Duration of Risk of Concern Action(s) Tak e n Comment (use

E x po s ure **~o** briefl y clarify

or elab or ate on
risk or mitigation)

./ Terrestria l P l ants ./ Residues on ./ Runoff ./ Ac u te ./ Direct ./ Clarify sing l e

site of ./ Spray drift ./ Chron ic ./ Indir ect maximum

treatment) application rate

for t ur f grass

./ Birds ./ Residues on ./ Ingestion ./ Chronic ./ Direct ./ Clarify single

s i te of maximum

treatment) application rate

./ Dietary for turf grass 16AppendixB:Trinexapac-ethylLabelTableSummaryofLabelingChangesforTrinexapac-ethylUsesDescriptionAmendedLabelingLanguageforTrinexapac-ethylUseProductsPlacementonLabelTechnicalProductsLanguagetolimitsingleDirectionsforUsemaximumapplication"Forliquidend-useturfproducts,thesinglemaximumapplicationratemustnotexceed0.68lbailA.DONOTrateforliquidturfgrassdoublethesinglemaximumapplicationrateforextendedsuppression."productsEndUseProductsLanguagetolimitsingleForliquidend-useturfproducts: ''Thesinglemaximumapplicationratemustnotexceed0.68lbai/A.DONOT"DirectionsforUse"maximumapplication·doublethesinglemaximumapplicationrateforextendedsuppression."under"ApplicationrateforliquidturfgrassInformation"andproducts"RecommendedApplicationRate"tableLanguagetolimitsingle"DirectionsforUse"maximumapplicationRemovethestatement:"Forextendedgrowthsuppressionupto8weeks,wheretemporarydiscolorationcanbeunder"Applicationrateforliquidturfgrasstolerates,amaximumoftwicetherecommendedratefromtheApplicationRateTablemaybeapplied."Information"products17