2 INTRODUCTION

This is the Environmental Protection Agency’s (E PA or the Agency) Final Work Plan (FWP) for the registration review of 2,4-DP-p. This wo rk plan addresses public comments received concerning the Preliminary Work Plan (PWP), which was posted in the 2,4-DP-p registration review docket (EPA-HQ-OPP-2013-0726). This case includes the following active ingredients: 2,4-DP-p acid, 2,4-DP-p dimethylamine (DMAS), a nd 2,4-DP-p 2-ethylhexyl ester (EHE). The
PC codes included in this case are: 0 31402, 031403, and 031465. These compounds are referred to collectively as 2,4-DP-p and individually as the acid, DMAS, and EHE. 2,4-DP-p is a nonsystemic herbicide in the phenoxy family of herbic ides that is registered for non-agricultural use to control a variety of weeds on commercial and residential lawns; turfgrass; golf courses; sod farms; outdoor residential areas; and forest trees. It is regi stered for noxious weed and brush control use on uncultivated, non-agricultural areas such as rights -of-way, roadsides, and airports. There are no registered food or agricultural us es, and 2,4-DP-p products are used primarily in residential, commercial, institu tional, and industrial areas.

The Agency is implementing the registration revi ew program pursuant to Section 3(g) of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), and will review each registered pesticide every 15 years to determine whether it continues to meet th e FIFRA standard for registration. Changes in scienc e, public policy, and pesticide us e practices occur over time. The registration review program is intended to make su re that, as the ability to assess risk evolves and as policies and practices change, al l registered pesticides continue to meet the statutory standard. The public phase of registration review begins wh en the initial docket is opened for each case. Information on this program is provided on the Agency’s website. 1

The FWP begins with any updates since the PWP wa s issued. Next is a summary of substantive comments received during the public comment peri od for the PWP concerning anticipated data needs, expected risk assessments, or the estimated timeline identified in the PWP, and a summary of the Agency’s responses to those comme nts. This section is followed by registration review planned data needs, risk assessments expected to be conducted, and the projected registration review timeline for 2,4-DP-p. Last ly, there is a discussion of next steps.

UPDATES SINCE THE PWP WAS ISSUED

The Registration Review: Preliminary Problem Form ulation for Environmen tal Fate, Ecological Risk, Endangered Species, and Dr inking Water Exposur e Assessments for 2,4-Dp-p Containing R Isomer Compounds (2,4-DP-p acid, 2,4-DP-p Am ine salt, and 2,4-DP-p 2-ethylhexyl ester), dated November 27, 2013, listed Guideline (GDLN) 835.6100, terrestr ial field dissipation, as an anticipated data need. However, as indicated in the PWP, twelve st udies were previously submitted by 2,4-DP-p registrants to EPA to fu lfill GDLN 835.6100 and were in review at the time of the publication of the PWP. EPA’s review of this inform ation indicated that eleven of
the submitted studies were scientif ically sound and classified as supplemental for risk assessment purposes. Additionally, this data also fulf ills the anticipated data need for GDLN 850.6100 environmental chemistry methods and associated independent laboratory validations (ECM/ILV) for soil. Therefore, EPA has determined that additional terrestrial field dissipation data and ECM/ILV for soil are no longer needed. Table 1 in the “Planned Data N eeds” section of this

1 http://www.epa.gov/oppsrrd1/registration_review/3 FWP has been updated to reflect this change. Al l other environmental fate and ecological effects data requirements remain as listed in the December 2013 PWP.

SUMMARY OF COMMENTS AND AGENCY RESPONSES

During the 60-day public comment period on th e 2,4-DP-p Preliminary Work Plan, which opened on December 20, 2013 and closed on February 18, 2014, the Agency received five public comments. Comments were submitted by the California San Francisco Bay Regional Water Quality Control Board (San Francisco Bay Water Board), the California Central Valley Regional Water Quality Control Board (Central Valley Wate r Board), the Center fo r Biological Diversity, the FIFRA Endangered Species Task Force (FES TF), and the 2,4-DP-p Task Force. The
comments do not address the timeline described in the PWP, but they do address the planned ecological and human health risk assessments and data requirem ents. In the PWP, EPA also solicited comments on the specific t opics of environmental justice, water quality concerns, and trade irritants; comments pe rtaining to water quality c oncerns only were received.

This section does not capture every comment made about the PWP nor all of the Agency’s responses. Summarized below ar e public comments that resulted in changes to the anticipated registration review data needs, risk assessments, or timeline, or are of a broader regulatory nature. Public comments in their entirety are located in the do cket, EPA-HQ-OPP-2013-0726. Summarized public comments that provide clar ification and information that will be incorporated into the planned ecological risk assessment are in an addendum to Registration Review: Preliminary Problem Formulation for Environmen tal Fate, Ecological Risk, Endangered Species, and Drinking Water Exposure Assessments for 2,4-Dp-p Containing R Isomer Compounds (2,4-DP-p acid, 2,4-DP-p Am ine salt, and 2,4-DP-p 2-ethylhexyl ester)

. No substantive comments were received on the planned hum an health risk assessment or data needs.

Comments submitted by San Francisco Bay and Central Valley Water Boards in EPA-HQOPP-2013-0726-0013 and EPA-HQ-OPP-2013-0726-0014.

1. Comment: The San Francisco Bay and Central Valley Water Boards’ comments center on considerations of the Clean Water Act and preventing water quality impairments of phenoxy family herbicides (2,4-D, 4-DB, and 2,4-DP-p). The Central Valley Water Board indicated that while 2,4-DP-p use in California is limited, 2,4-D is the most frequently detected herbicide in California urban waterways. The Board stated that for 2,4-DB and 2,4-DP-p registrations, additional fate and toxicity data should be required for 2,4-DCP, the common phenoxy herbicide degradate, in order to ensure conservative risk assessments are conducted and to prevent water quality impairments caused by 2,4-DB and 2,4-DP.

Response: 2,4-DCP is a common degradate of 2,4-DB as well as 2,4-DP-p and 2,4-D. EPA’s review of the public lite rature database indicated that some data on the aquatic toxicity of 2,4- DCP are available, and that 2,4-DCP may be more toxic than 2,4-DP-p to some aquatic species.
If a further review of availabl e data corroborates this initia l determination, aquatic exposure estimates may be conducted for 2,4-DP-p and 2,4-DCP separately or based on a total equivalency factor (TEF) approach depending on the availability of additional 2,4-DCP data. Therefore, based on the availability of relevant public literature on 2,4-DCP, additional data are not required. However, the 2,4-DP-p Task Force al so indicated in its public comments that it will submit relevant information on 2,4-DCP. The Agency welcomes this information and will4 review relevant information regarding the toxi city of 2,4-DCP to confirm that the Agency’s assumptions regarding 2,4-DCP are appropriate. In the absence of data , values from ECOSAR, a toxicity endpoint modeling tool, may be used to predict the toxicity of 2,4-DCP. If a review
of available data indicate that 2,4-DCP is not more toxic to a quatic species, toxicity of the degradate will be characterized using the total t oxic residue approach, which would be expected to conservatively estimate th e toxicity of 2, 4-DCP.

2. Comment: The San Francisco Bay and Central Valley Water Boards also requested clarification on the approach that will be taken to consider cumulative risk of additive toxicities of phenoxy herbicides.

Response: EPA agrees that exposure to mixtures of compounds may affe ct the overall toxicity of any chemical. However, a quantitative assessm ent of risks associated with mixtures requires extensive data. Currently EPA does not have adequate data and has not yet developed the methodology to quantitatively model and assess mixtures of chemicals in the environment. Therefore, a quantitative assessment of mixtures cannot be conducted at this time. EPA has a long-term goal to develop a quantitative appr oach including guidance on weight-of-evidence analysis for assessing risk of pesticide mixtures. In the interim, EPA intends to qualitatively discuss the potential for differential exposure an d toxicity from mixtures of compounds.

3. Comment: The San Francisco Water Board also commented that the Agency should consider the potential ecological risks of 2,4-DP-p in urban settings, including and in particular, the fate and aquatic toxicity impacts from the common degradate 2,4-DCP.

Response: The Agency is evaluati ng all registered uses of 2,4-DP -p during registration review. 2,4-DP-p is primarily used on lawns, rights-of -ways, residential area s, and non-cultivated agricultural lands. The environmental fate prope rties and use patterns of 2,4-DP-p indicate that direct spray, spray drift, leaching through so il, and runoff represen t potential transport mechanisms of 2,4-DP-p to non-target aquatic and terrestrial organisms and will be included as exposure pathways of concern for both urban and non-urban settings. However, for urban settings, the Agency has limited scenarios/tool s to evaluate exposur e for urban uses of pesticides.

Comments submitted by the Center for Bi ological Diversity in EPA-HQ-OPP-2013-0726-
0011.

4. Comment : The Center for Biological Diversity’s (CBD) comments focus on the EPA’s independent duty under the Endangered Species Ac t (ESA) to consult with the U.S. Fish and Wildlife Service and the National Marine Fisheries Service (the Services) on the registration review of 2,4-DP-p.

Response : EPA has reviewed the comments from CBD on the registration review docket opening for 2,4-DP-p and plans to address many of the concerns raised by CBD as part of the implementation plan for assessing the risks of pesticides to listed species based on the recommendations of the April 2013 National Acad emy of Sciences (NAS) report. EPA will address concerns specific to 2,4-DP-p in conne ction with the developm ent of its registration review decision for 2,4-DP-p.5 At this time, EPA has not fully developed its ri sk assessment process for listed species. In November 2013, the EPA, along with the Services and the U.S. Department of Agriculture (USDA) released a summary of their joint Inte rim Approaches for assessing risks to listed species from pesticides. The Interim Approaches were developed jointly by the Agencies in response to the National Academy of Scien ces’ (NAS) recommendations and reflect a common approach to risk assessment shared by th e Agencies as a way of addressing scientific
differences between the EPA and the Serv ices. The NAS report, available at http://www.nap.edu/catalog.php?record_id=183 44, outlines recommendations on specific
scientific and technical issues related to the development of pesticide risk assessments that
EPA and the Services must conduct in connect ion with their obliga tions under the ESA and FIFRA. The joint Interim Approaches were rele ased prior to a stakeholder workshop held on November 15, 2013. In addition, the EPA presen ted the joint Interim Approaches at the December 2013 Pesticide Program Dialogue Co mmittee (PPDC) and State-FIFRA Issues
Research and Evaluation Gr oup (SFIREG) meetings, allowi ng 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 comments on the Interim Approaches in connection with the development of upcoming Registration Review decisions. The details of the joint Interim Approaches are contained in the white paper “Interim Approaches for National-Level Pe sticide Endangered Species Act Assessments
Based on the Recommendations of the Nationa l Academy of Sciences April 2013 Report,” dated November 1, 2013, available at http://www.epa.gov/espp/2013/nas.html

.

Comments submitted by FE STF in EPA-HQ-OPP-2013-0726-0012.

5. Comment: FESTF commented that the 2,4-DP-p tec hnical registrants are current members of FESTF and, thus, entitled to rely on FESTF data on federally-lis ted threatened and endangered species. FESTF also indicated the data they have previously submitted to the Agency are the best available for the proxim ity analysis of 2,4-DP-p use and endangered species locations, and fulfill the requirements indicated in Pe sticide Registration Notice
2000-2.

Response: EPA thanks FESTF for its comment and will consider all appropriate information as we conduct the registration review assessment and make our registrati on review decision.

Comments submitted by 2,4-DP-p Task Force in EPA-HQ-OPP-2013-0726-0015.

6. Comment: The 2,4-DP-p Task Force provided clar ification on use sites and restrictions, including possible explanations for an apparent off-label us e on pasture reported in the BEAD Chemical Profile for Registration Review. The Task Force believes that 2,4-D use is sometimes confused with 2,4-DP-p in grower surveys. Also, registered uses around pastures, such as fencerows, may be mistakenly reported as pasture use. Lastly, the Task Force stated that registered use on non-agricultural, uncul tivated areas, including grasses grazed by nonfood/nonfeed animals such as horses, may be reported as pasture uses. The Task Force further indicated that USDA Census of Agriculture data on horse and pony populations coincide with EPA’s data on reported pasture us e in Missouri and Tennessee. These states
have the 5 th and 4 th largest horse and pony populations in the U.S. and are more likely to have cool season pasture and weed species that 2,4-DP-p is used on as compared to the states with the largest horse populations.6 Response: EPA thanks the 2,4-DP-p Task Force for this information. The EPA concurs that use along fencerows and on non-agricultural, uncu ltivated lands may be reported as pasture use. However, EPA will continue to monitor us age data in registration review to determine if further information on reported 2,4-DP-p use on past ures is needed and if label clarifications and/or grower outreach may be warranted.

7. Comment: The Task Force also provided information on the size of 2,4-DP-p spot treatment areas, the size of various granules in 2,4-DP-p end-use formulations, and a list of supported PC codes to differentiate between PC codes that were historically part of the 2,4-DP case and which PC codes are actively supported in registration review under the 2,4-DP-p case. The Task Force further indicated that it will co ntinue to work with EPA to clarify label use
directions and restrictions in registration review.

Response: The EPA thanks the Task Force for this information and the clarification of supported PC codes. The Registration Review: Problem Fo rmulation for Environmental Fate, Ecological Risk, Endangered Species, and Drinking Water Exposure Assessments for 2,4-DP-p Containing R Isomer Compounds (2,4- DP-p acid, 2,4-DP-p Amine salt, and 2,4- DP-p 2-ethylhexyl ester) has been amended to incorporat e relevant granular and spot
treatment information.

PLANNED DATA NEEDS

Table 1 on the following page summarizes the planned data needs for 2,4-DP-p based on the Registration Review: Preliminary Problem Form ulation for Environmental Fate, Ecological Risk, Endangered Species, and Dr inking Water Exposur e Assessments for 2,4-DP-p Containing R Isomer Compounds (2,4-DP-p acid, 2,4-DP-p Amine salt, and 2,4-DP-p 2-ethylhexyl ester)
and the 2,4-DP-p (dichloroprop-p) Human Health A ssessment Scoping Document in Support of Registration Review . The table has been updated since th e PWP to reflect the completion of study reviews, which resulted in the removal of a terrestrial field dissipation study from the list
of data needs.

Table 1: Planned Data Needs for the 2,4-DP-p Registration Review

Guideline
Number 2 Study Title 1 Test Material Estimated
Timeframe

(Months from receipt of DCI)

835.4100 3 Aerobic soil metabolism TGAI 24 835.4400 Anaerobic aquatic metabolism TGAI 24

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

– including renumbering and other designations or changes for some guideline studies. See “Final Test Guidelines; OCSPP 850 Series; Notice of Av ailability” 77 FR 38282 , June 27, 2012. http://www.regulations.gov/#!documen tDetail;D=EPA-HQ-OPPT-2009-0154-0028

3 A single aerobic soil metabolism study has been submitted and classified accepta ble. However, additional data for three soils are required under 40 CFR Part 158 for terrestri al outdoor uses and are anticipated data needs for this registration review.7 Table 1: Planned Data Needs for the 2,4-DP-p Registration Review

Guideline
Number 2 Study Title 1 Test Material Estimated
Timeframe

(Months from receipt of DCI)

850.1010 Freshwater inverteb rate acute toxicity TGAI (EHE) 12

850.1025 4 Acute toxicity estu arine and marine organisms (oyster shell growth) TGAI (acid or
DMAS 5 , and EHE) 12

850.1035 4 Acute toxicity estu arine and marine organisms (mysid) TGAI (acid or
DMAS 5 , and EHE) 12

850.1075 Acute toxicity estuar ine and marine fish TGAI (acid or
DMAS 5 , and EHE) 12

850.1300 Aquatic invertebrate life cycle (freshwater) TGAI (acid or
DMAS 5 ) 12

850.1350 Aquatic invertebrates life cycle (saltwater) TGAI (acid or
DMAS 5 ) 12

850.1400 6 Fish early-life stage (freshwater and saltwater) TGAI (acid or
DMAS 5 ) 12

850.2100 Avian oral toxicity (p asserine species) TGAI 12

850.2300 Avian reproduction (upland game and waterfowl species) TGAI 24

850.4100 Terrestrial plant toxi city, seedling emergence TEP (EHE) 7 12

850.4150 Terrestrial plant t oxicity, vegetative vigor TEP (DMAS and

EHE 8 ) 12

4 Data are required on one estuarine/marine mollusk and one estuarine/marine invertebrate. The DCI will provide that Guidelines 850.1045 and 850.1055 may be conducted in lieu of Guidelines 850.1025 and 850.1035.

5 The DCI will provide that the test material be either 2, 4-DP-p acid technical grade active ingredient (TGAI) or 2, 4-DP-p DMAS TGAI. Data on the 2,4-DP-p EHE TGAI are also expected to be required.

6 Data are anticipated to be needed on both a freshwater and saltwater species.

7 Data are required for 2,4-DP-p EHE for soybean.

8 Data are required for both 2,4-DP-p DMAS and EHE. For 2,4-DP-p EHE, data are required for soybean only.8 Table 1: Planned Data Needs for the 2,4-DP-p Registration Review

Guideline
Number 2 Study Title 1 Test Material Estimated
Timeframe

(Months from receipt of DCI)

850.4500 Algal toxicity TGAI (EHE) 9 12

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

870.3465

10 90-day inhalation toxicity TGAI 12

NONGDLN 11 Pollinator acute oral toxicity (honeybee larvae) TGAI 12

TGAI = technical grade active ingredie nt; TEP = typical end-use product;

RISK ASSESSMENTS FOR REGISTRATION REVIEW

During registration review, the Agency will conduct a comprehensive ecological risk assessment, including an endangered species assessment, for all uses of 2,4- DP-p. For human health, EPA
will need to conduct revised diet ary (drinking water only), reside ntial, and occupational risk assessments during registration review. If toxico logical endpoints or po ints of departure are revised based on the data that are required for regi stration review, they will be considered in the new assessments, as well as any changes to th e standard operating procedures or default exposure assumptions.

Table 2 below summarizes the planned registrati on review risk assessments based on the EFED Problem Formulation and HED Scoping Docume nt and the planned assessments have not changed from what was included in the PWP.

9 Data are required for 2,4-DP-p EHE for the freshwater diatom.

10 For the inhalation toxicity study, an acce ptable test of 28 days duration is exp ected to be sufficient to satisfy this data requirement.

11 Refer to OECD 237 honey bee larv al toxicity test for guidance.9 Table 2: Planned Risk A ssessments for the 2,4-DP-p Registration Review

Type of Risk Assessment Conduct? Notes
Ecological and Environmental Fate Comprehensive ecological (species to be assessed include terrestrial and aquatic organisms), including endangered species Y

Incidents Will check for updates For a discussion of reporte d ecological incidents for 2,4-DP-p, see page 13 of the Problem Formulation.

Human Health Dietary Food N 2,4-DP-p is not currently registered for use on food or
feed. Drinking water Y Updated dietary ri sk assessments may be needed during registration review to consider newly estimated drinking water concentrations and/or changes in the toxi cological endpoints.

Occupational Handlers (mixers, loaders, applicators) Y Updated occupational exposure assessment may be needed during registration review to consider new exposure estimates based on current science policies or if there are changes in the toxicological endpoints.

Post-application N There is no evidence of systemic toxicity from dermal exposure. Appropriate re-e ntry intervals (REIs) are currently on product labels, thus significant dermal exposure from recently treated areas is not anticipated.

Residential Handlers Y Updated residential exposure assessments may be needed during registration review to consider new exposure estimates based on current science policies or if there are changes in the toxicological endpoints. Post-application Y

Other Aggregate Y Evaluates the combined risk from dietary (water) and residential exposures. Cumulative N 2,4-DP-p has not been identified as a member of a cumulative group that shares a common mechanism of toxicity.
Tolerances N Tolerances are not es tablished for 2,4-DP-p since it is not registered for use on food or feed at this time.10 Table 2: Planned Risk A ssessments for the 2,4-DP-p Registration Review

Human Health
Other
Incidents Will check for updates For a discussion of reported human incidents for 2,4- DP-p, see page 10 of the Scoping Document and the Dichlorprop

, 2,4 -DP-p, 2,4

- DP-p, amine sa l t, Dimethy l amine-2-(2

, 4-dich l orophenoxy) propionate, Isooctyl 2-(2

, 4-dichlorphenoxy)propionate,Propionic acid, 2-(2,4 dichlorophenoxy)-

, 2-ethylhexyl ester

, and
2 ,4 -DP-p , 2

- ethylhexy l ester: Tier I Re v i ew of Human
In cidents.

TIMELINE

EPA has created the following estimated timeline for the completion of the 2,4-DP-p registration review in Table 3 below. The projected timeline has not change d since the PWP.

Table 3: Registration Review for 2,4-DP-p – Projected Registra tion Review Timeline

Activities Estimated Date Opening the Docket
Open Docket and 60-day Public Comment Period Dec. 2013 – Completed

Close Public Comment Feb. 2014 – Completed
Case Development

Final Work Plan May 2014 – Completed

Issue DCI 2014: July – Sept.

Data Submission 2016: July – Sept.
60-day Public Comment Period for Draft Risk

Assessments [12] 2018: Jan. - March

Registration Review Decision
60-day Public Comment Peri od for Proposed Registration

Review Decision 2018: Oct. – Dec.

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

Total (years) 6

NEXT STEPS

As noted previously, the Agency plans to requir e several environmental fa te, ecological effects, and human health studies for 2,4-DP-p through a Data Call-In Notice, expected to be issued in August 2014.

[12] The regulations governing Registration Review generally require the Agency to provide a public comment period

of at least 30 calendar days for draft risk assessments; see 40 CFR Part 155.53(c). For conventional pesticides, the Agency plans to provide a 60 calendar day public comment period generally for draft risk assessments.