1 Docket Number EPA-HQ-OPP-2011-0706 www.regulations.gov



## Tralkoxydim Final Work Plan Registration Review February 20123 Introduction

This is the Environmental Protection Agency’s (EPA or the Agency) Final Work Plan (FWP) for the registration review of tralkoxydim. The FW P includes the expected registration review timeline. The FWP also addresses any public comments received on the Preliminary Work Plan (PWP) in the Summary Document, which was posted in the tr alkoxydim registration review docket (EPA-HQ-OPP-2011-0706). The Summary Document, dated September 27, 2011, provided information on what EPA knows about the pesticide and what additional risk analyses and data or information the Agency believes are needed to make a regist ration review decision.

The Agency’s implementation of the registrati on review program requi res review of each registered pesticide every 15 years to determin e whether it continues to meet the Federal Insecticide, Fungicide, and R odenticide Act (FIFRA) standard for registration. Changes in science, public policy, and pest icide use practices occur over time. The registration review program is intended to make sure that, as the ab ility to assess risk evolves and as policies and practices change, all registered pesticides contin ue to meet that statutory standard. The public phase of registration review begins when the in itial docket is opened for each case. Information on this program is provided at http://www.epa.gov/oppsrrd1/registration_review/

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Tralkoxydim is a systemic, postemergence herbicide re gistered for agricultura l use to selectively control certain annual grass weeds in wheat, barley, and triticale. Target weeds include wild oats, green foxtail, yellow foxtail, annual ryeg rass (Italian), and Persian darnel. There are currently no residential uses. Tralkoxydim was first registered in the U.S. in 1998; therefore, it was not subject to the reregist ration requirements of FIFRA.

Comments Received on the Summary Document

No comments were received dur ing the 60-day public comment pe riod on the planned ecological assessment and human health scoping document discussed in the Preliminary Work Plan . In the Preliminary Work Plan , EPA also solicited comments on three specific topics: environmental justice, water body impairment, and trade irritants. No comments or information were received during the comment period concer ning these three topics.

Anticipated Risk Assessment and Data Needs

The Agency will conduct comprehensive human health and ecological risk assessments, including an endangered species risk assessment, for all uses of tralkoxydim. The Agency will require data for use in conducting these assessments. Below is a summary of the issues relevant to the registration review of tralkoxydim and a list of the data requirements.4 Ecological Risk:

• The most recent ecological risk assessment wa s a Section 3 review conducted in 1998 in support of new uses of tralkoxydim on wheat and barley.

• The Agency will conduct an updated environmen tal fate and ecological risk assessment for tralkoxydim, including an endangered spec ies assessment, during registration review. The new assessment will incorporate the most up-to-date modeling methodologies, updated toxicological endpoints, and any new data submitted and determined to be adequate.

• The Agency has not conducted a risk asse ssment that supports a complete endangered species determination for tralkoxydim. The ecological risk assessment planned during registration review will allo w the Agency to determine whether tralkoxydim’s use has “no effect” or “may affect” federally liste d threatened or endangered species (listed species) or their designated critical habita ts. 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 Wildli fe Service (USFWS) and/or National Marine Fisheries Service (NMFS) (the Services), as appropriate.

• Data gaps exist in the environmental fate a nd ecological toxicity database for tralkoxydim and two of its degradates. The Agency n eeds the following data for use in conducting a complete ecological risk assessment, including an endangered species assessment, for tralkoxydim and its degradates:

Environmental Fate

o Guideline Number 835.4300 – Aerobic Aquatic Metabolism with Compounds 8 and

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Ecological Toxicity

o Guideline Number 850.1400 – Fish Early Life-sta ge Toxicity Test (freshwater) with tralkoxydim TGAI

• Please refer to the Problem Formulation for the Envi ronmental Fate, Ecological Risk, Endangered Species, and Drinking Water Ex posure Assessments in Support of Registration Review of Tralkoxydim , dated September 13, 2011, located in docket EPAHQ-OPP-2011-0706 at www.regulations.gov, for a more detailed discussion of the ecological risk assessment and data needs.5 Human Health Risk:

• The most recent human health risk assessm ents were conducted in the 1999 Health

Effects Division Risk Characterization Docu ment for the First Food Use of Tralkoxydim in/on Wheat and Barley.

• During registration review, the endpoints, doses , and safety factors used in the most

recent human health risk assessments will be revisited based on current policy as well as to incorporate any new data received and determined to be adequate.

• The Agency will conduct updated dietary (food a nd water), aggregate, and occupational exposure risk assessments to include any ch anges in toxicological endpoints, doses, and procedures for risk assessment.

• The Agency will also conduct an updated drinking water exposure risk assessment during registration review.

• Currently, there are no registered residentia l uses for tralkoxydim or uses that would result in residential exposure. However, residential bystander inhalation exposures resulting from off-site transport (e.g., spray drift or volatilization) may occur as a result of applications of tralkoxydim. The Agency is in the proc ess of examining its policies and refining the methods used to complete re sidential exposure assessments. Therefore, the potential need for a bystander inhalati on risk assessment for tralkoxydim will be examined during registration review.

• During registration review, the Agency w ill conduct both an occupational handler exposure risk assessment and an occupationa l postapplication exposure risk assessment based on updated doses, endpoints, and procedures for risk assessment.

• The tolerance expression for tralkoxydim in 40 CFR §180.548 will be reviewed during registration review to ensure that it appropr iately covers the metabolites and degradates of tralkoxydim and that it specifies the residues to be measured in each commodity.

• The Agency will modify tolerance levels as needed, and work to harmonize tolerances/maximum residue limits (MRL), wh ere possible, in key export markets during registration review.6 • The toxicity database for tralkoxydim is comp lete except for the following studies, which the Agency will require for use in conducting an updated human health risk assessment:

Toxicology Data

o Guideline Number 870.6200 – Acute and Subchronic Neurotoxicity

o Guideline Number 870.7800 – Immunotoxicity

• Please refer to Tralkoxydim. Human Health Assessm ent Scoping Document in Support of Registration Review  ̧ dated September 19, 2011, available in docket EPA-HQ-OPP-2011-0706 at www.regulations.gov, for a detailed discussion of the human health risk assessment and data

needs.

Endocrine Disruptor Screening Program

As required by FIFRA and FFDCA, EPA reviews num erous studies to asse ss potential adverse outcomes from exposure to chemicals. Collectiv ely, these studies includ e acute, subchronic and chronic toxicity, including asse ssments of carcinogenicity, ne urotoxicity, developmental, reproductive, and general or systemic toxicity. These studies include endpoints which may be susceptible to endocrine influe nce, including effects on endocri ne target organ histopathology, organ weights, estrus cyclicity, sexual maturatio n, fertility, pregnancy rates, reproductive loss, and sex ratios in offspring. For ecological hazard assessments, EPA evaluates acute tests and chronic studies that assess gr owth, developmental and reprod uctive effects in different taxonomic groups. As part of its most recent re gistration decision, EPA re viewed these data and selected the most sensitive endpoi nts for relevant risk assessment scenarios from the existing hazard database. However, as required by FFDCA section 408(p), tralkoxydim is subject to the endocrine screening part of the Endocrine Disruptor Screenin g Program (EDSP).

EPA has developed the EDSP to determine whet her 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 ot her such endocrine effect s as the Administrator may designate.” The EDSP employs a two-tiered approach to making th e statutorily required

determinations. Tier 1 consists of a battery of 11 scr eening assays to identify the potential of a chemical substance to interact with the estrog en, androgen, or thyroid (E, A, or T) hormonal systems. Chemicals that go th rough Tier 1 screening and are found to have the potential to interact with E, A, or T hormonal systems will proceed to the next stag e of the EDSP where EPA will determine which, if any, of th e Tier 2 tests are necessary base d on the available data. Tier 2 testing is designed to identify a ny adverse endocrine-related eff ects 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 chemicals, which contains 58 pesticide active in gredients and 9 inert ingredients. Tralkoxydim7 is not among the group of 58 pesticide active ingred ients on the initial list to be screened under the EDSP. Accordingly, as part of registrati on review, EPA will issue future EDSP orders/data call-ins, requiring the submission of EDSP scr eening assays for tralkoxydim. For further information on the status of the EDSP, the polic ies and procedures, the list of 67 chemicals, future lists, the test guidelines and the Tier 1 screening battery, pl ease visit our website: http://www.epa.gov/endo/

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Timeline

The projected timeline for the completion of the tralkoxydim registration review is presented in

Table 1.

Table 1. Projected Tralkoxydim Registration Review Timeline Activity Estimated Date Opening the Docket Open Docket and Open Public Comment Period 2011 – September

Close Public Comment Period 2011 – November Case Development Develop Final Work Plan (FWP) 2012 – February Issue Data Call-In (DCI) 2012 – Oct. – Dec.

Data Submission 2014 – Oct. – Dec. Develop Preliminary Risk Assessments and Open Public Comment

Period 2016 – April – June

Close Public Comment Period 2016 – July – Sept. Registration Review Decision Develop Proposed Registration Revi ew Decision and Open Public

Comment Period 2016 – Oct. – Dec.

Close Public Comment Period 2017 – Jan. – March Issue Registration Review Decision a nd Begin Post-Decision Follow-up 2017 Total (years) 6

Next Steps

The Agency plans to conduct a human health ri sk assessment and comprehensive ecological risk assessment, including an endangere d species risk assessment, for tr alkoxydim. Drafts of the risk assessments are scheduled to be available for public comment in 2016.