2 INTRODUCTION

This is the Environm ental Protection Agency’s (EPA or the Agency ) Final Work Plan (FWP) for the registration review of rimsulfuron . This work plan addresses public comments received concerning the Preliminary Work Plan (PWP), which was posted in rimsulfuron’s registration review docket (EPA

- HQ

- OPP

- 2012

- 0178 ). Rimsulfuron is a selective herbicide registered for use to control broadleaf and grassy weed s on various agricultural and non

- agricultural food and

non

- food sites. There are no registered residential uses.

The Agency is implementing the registration review program pursuant to Section 3(g) of the Federal Insecticide, Fungicide, and Rodenticide Ac t (FIFRA), and will review each registered pesticide every 15 years to determine whether it continues to meet the FIFRA standard for registration. Changes in science, public policy, and pesticide use practices occur over time. The registration review prog ram is intended to make sure that, as the ability to assess risk evolves and as policies and practices change, all registered pesticides continue to meet the statutory standard. The public phase of registration review begins when the initial docket is open ed for each case.

Informatio n on this program is provided on the Agency’s website 1

.

The FWP begins with any updates since the PWP was issued. Next is a summary of substantive

comments received during the public comment period 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 response s to th o se comments

. This section is followed by

rimsulfuron’s registration review planned data needs, risk assessments expected to be conducted

, and the projected registration review timeline. Lastly, there is a discussion of next steps.

UPDATES SINCE THE PWP WAS ISSUED

Changes have been made to the data requirements anticipated in the PWP. Please see t he Planned

Data Needs section below

.

SUMMARY OF COMMENTS AND AGENCY RESPONSES

During the 60

- day public comment period on the rimsulfuron Preliminary Work Plan , which opened on September 26, 2012 and closed on November 26, 2012, the Agency received one

pu blic comment, a submission by technical registrant Dupont. The comment do es not address the

timeli ne described in the PWP, but it does address the planned ecological risk assessment and data requirements. In the PWP, EPA also solicited comments on the specific topics of environmental justice, water quality concerns , and trade irritants, but no comments or

information were received on those issues.

This section does not capture every comment made on the PWP nor all of the Agency’s

responses. Summarized below is a public comment that resulted in a change to the anticipated regist ration review data needs. Public comments and EPA responses in their entirety are located in the docket, EPA

- HQ

- OPP

- 2012

- 0178 . Su mmarized public comments and Agency responses

related to the anticipated ecological risk assessment or data needs are in the February 25, 2013

1 http://www.epa.gov/oppsrrd1/registration_review/3 Registration Review: Response to Comments on Preliminary Problem Formulation for Environmental Fate, Ecological Risk, Endangered Species, and Human Health Drinking Water Exposure Assessments for Rimsulfuron

.

Comments submitted by DuPont in EPA

- HQ

- OPP

- 2012

- 0178

- 0009

.

1. Comment: DuPont believes that further characterization of secondary metabolites in the submitted anaerobic aquatic metabolism study should not be warranted based on OPPTS guideline 835.4400 and the facts below:

1. The overall mass balance was 101.1±3.9% (the data summarized from Table VI, VII, and VIII in MRID #48332004).

2. All maj or metabolites (IN

- 70942, IN

- 70941, IN

- J0290, and IN

- E9260) were well identified by HPLC method and confirmed by the secondary TLC method, which is consistent with other rimsulfuron aerobic and anaerobic degradation studies.

3. Unknown 1 from the combine d amount of sediment and water phases (as shown in Tables IX, X, XIII, and XIV in MRID #48332004) was indicated greater than 10%. However, Unknown 1 was not a single metabolite; rather it was the sum of multiple polar components not retained by original HP LC method. Unknown 1 was separated into 4 distinct approximately equal peaks by modified HPLC as demonstrated in Figure 17 from MRID #48332004. Therefore, no single component was indicated greater than 10% or even 5%.

Response: The Agency has reviewed the information cited in DuPont’s response and agrees in principle with each of the points made. However, DuPont did not in their response discuss the identity of unextracted residues or the possibility of attempting further extraction steps t o release these residues. The level of unextracted residues is high

– for example, in Table VI on page 42 it is shown that the unextracted residues in nonsterile Canadian pond water and sediment at 25 C increased steadily over time (e.g., about 19% at 14 d ays and 71% of the applied radioactivity at 3 months after application). The Agency reviewed the submitted report (MRID 48332004) and notes while the fraction of bound residues observed under nonsterile conditions is quite high, the registrant did extract the sediment three times with 2:1 acetonitrile:water and then three times with a methanol phosphate buffer system before declaring the remaining radioactivity as unextractable. Some characterization of the large

amount of radiolabeled residues in the sedim ent was conducted by fractionation into humin, fulvic acid, and humic acid fractio ns. The fractionation procedure needs to be described in more detail as only a citation of a Federal Register notice is given as a reference.

Normally, the high degree of u nextracted residues observed in the anaerobic aquatic metabolism study would be a basis for requesting an additional study, or, at the very least, necessitate more conservative assumptions in risk assessments (e.g., assuming that the

unextracted residues w ere part of the total toxic residues.)

. Somewhat reducing these concerns is that much of the formation and decline of parent to and from residues such as IN

70941, IN

- 70942, IN

- J0290, and IN

- E9260 occurs prior to most of the rise in the amount of

unextract ed radiolabeled residues. Therefore most of the residues which become bound to soil organic matter or colloids would more likely be secondary metabolites of less4 toxicological concern. A special sediment toxicity study could further address whether any

of the unextracted residues are of toxicological concern and, if it were to show these residues

to be non

- toxic, might allow less conservative exposure assumptions to be made in future

risk assessments.

It is also relevant to note that unextracted residues while generally less than 25% in the aerobic soil metabolism studies, did appear to be rising when these studies were terminated after about four months incubation (MRID 48332003; study under review). The Agency will

not include the anaerobic soil metaboli sm data requirement in the data call

- in for the registration review of rimsulfuron.5 PLANNED DATA NEEDS

The table below summarizes the planned data needs for rimsulfuron based on the September 13,

2012 Registration Review: Preliminary Problem Formulation for Environmental Fate, Ecological Risk, Endangered Species, and Human Health Drinking Water Exposure Assessments for Rimsulfuron

, as well as the February 25, 2013 Registration Review: Response to Comments on Preliminary Problem Formulation fo r Environmental Fate, Ecological Risk, Endangered Species, and Human Health Drinking Water Exposure Assessments for Rimsulfuron

. The table has been updated since the PWP to reflect the public comment that resulted in removal of the anaerobic aquatic metabo lism data requirement

. Also, a terrestrial plant reproduction toxicity study has been added to the list below and will be included in the Data Call

- in. The study has been typically required of all sulfonyl urea herbicides . However, the Agency has determi ned that generation of new non

- guideline plant reproduction studies for each sulfonyl urea herbicide is unnecessary. Since this determination was made based on plant reproduction data submitted by a registrant, the plant reproduction data requirement is b eing added t o t he Data Call

- in for all SU’s for data compensation purposes

.

Planned D ata Needs for R imsulfuron’s Registration Review

Guideline

Number Study Title Test Material Estimated

Timeframe

(Months from receipt of DCI)

835.6100 Terrestrial field dissipation study 2 TGAI and degradates 12

835.6200 Aquatic field dissipation study 2 TGAI and degradates 12

850.1350 Aquatic invertebrate life

- cycle (marine) 3 TGAI 12

850.1400 Estuarine/marine fish early life stage 3 TGAI 12

850.4100 Terrestrial plant toxicity, seedling emergence,

Tier II TEP 12

850.4150 Terrestrial plant toxicity, vegetative vigor, Tier

II TEP 12

Non

guideline Terrestrial plant reproduction toxicity 4 TGAI 24

2 See footn ote 7 of 40 CFR 158.1300. EPA is requiring only the environmental chemistry analytical methods and

independent laboratory (ILV) portions of this guideline for soil and water, rather than the full field dissipation study.

3 Results from the review of the submitted freshwater studies may negate the need for additional data.

4 Based in part on a review of previously submitted data for another sulfonyl urea herbicide, the Agency has determined that generation of new non

- guideline plant reproduction studies for each sulfonyl urea herbicide is unnecessary. The previously submitted data provide sufficient information for EPA to characterize potential impacts of the sulfonyl u rea herbicides on plant reproduction. Therefore, to satisfy this requirement, registrants may wish to consider citing these existing data in response to the DCI.6 Planned D ata Needs for R imsulfuron’s Registration Review

Guideline

Number Study Title Test Material Estimated

Timeframe

(Months from receipt of DCI)

The studies listed below were previously required and are under review. They will NOT be included in the anticipated Registration Review DCI. However, if the studies are not determined to be acceptable, the registrants will have to resubmit or upgrade them.

835.4100 Aerobic Soil Metabolism TGAI and degradates In review

835.4300 Aerobic aquatic metabolism TGAI and degradates In review

850.1300 Aquatic invertebrate life

- cycle (freshwater) TGAI In review

850.1400 Freshwater fish early life

- stage TGAI In review

TGAI = technical grade active ingredient; TEP = typical end

- use product ;7 RISK ASSESSMENTS FOR REGISTRATION REVIEW

During registration review, t he Agency will conduct a comprehensive ecological risk assessment, including an endangered species assessment, for all uses of rimsulfuron

. For human health, EPA

will conduct revised residential and occupational risk assessments during registration review

. If toxicological endpoints or points of departure are revised based on the data that are required for registration review

, they will be considered in the new assessment s
, as well as any changes to the standard operating procedures or default exposure assumptions.

The table below summarizes the planned registration review risk assessments based on the EFED

Problem Formulation and HED Scoping Document and the planned assessments have not changed from what was included in the PWP

.

Planned Risk Assessments for R imsulfuron’s Registration Review

Type of Risk Assessment Conduct? Notes

Eco logical and Environmental Fate Comprehensive ecological (species to be assessed include terrestrial and aquatic organisms), including endangered species Y

Incidents Y For a discussion of rimsulfuron’s reported ecological incidents, see page 22 of the Problem Formulation.

Human Healt h Dietary

Food N Drinking water N Occupational Handlers (mixers, loaders, applicators) Y Occupational handler exposure and risk assessments are anticipated for the following uses: golf course, sod farms athletic fields, industrial and commercial lawns

and similar nonresidential areas; agricultural food crops including soybeans, potatoes, field corn, tomatoes, grapes, various tree fruits, and tree nuts.

Post

- application Y Occupational post

- application exposure and risk assessments are anticipated for the following uses: soybeans, potatoes, field corn, tomatoes, grapes, various tree fruits, tree nuts, and golf course turf.

Residential

Handlers N

Post

- application Y Based on the current use patterns, there is only potential for post

- application de rmal exposure for recreational golfers. Therefore, a new risk assessment is anticipated for the existing golf course turf use.

Other8 Aggregate Y A new aggregate assessment may be needed to

include the short

- term dermal exposure for the

recreational golfer.

Cumulative N

Tolerances N

Incidents Y For a discussion of rimsulfuron’s reported human incidents, see page 7 of the Scoping Document.

TIMELINE

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

. The projected timeline has been updated to reflect changes to the planned

data needs

.

Registration Review for R imsulfuron

– Projected Registration Review Timeline

Activities Estimated Date Opening the Docket Open Docket and 60

- day Public Comment Period 2012

– Sept.

– Completed

Close Public Comment 2012

– Nov.

– Completed Case Development

Final Work Plan 2013

- March

– Completed

Issue DCI 2013

– Oct.

- Dec.

Data Submission 201 4

– Oct.

– Dec. Open 60

- day Public Comment Period for Draft Risk Assessments 201 6

– April

– June Registration Review Decision Open 60

- day Public Comment Period for Proposed Registration Review

Decision 201 6

– Oct.

– Dec.

Registration Review Decision and Begin Post

- Decision Follow

- up 201 7 Total ( years ) 5

NEXT STEPS

As noted previously, the Agency plans to require environmental fate and ecological effects

studies for rimsulfuron through a data call

- in, expected to be issued in 2013

.