UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, D

.C

. 20460


## MAY 212015

MEMORANDUM OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION



### SUBJECT: BEAD Response to Public Comments in Support ofRegistration Review (EPA Docket ID No.: EPA-HQ-OPP-2014-0772}-Metolachlor Case [S-metolachlor (108800) and Metolachlor (108801)] FROM: Leonard Yourman, Ph.D., Plant Pathologist

THRU: Biological Analysis Branch

. . Jihad Alsadek, Ph.D., Economist

# ..;r~A-

# --A~ Science Information and Analysis Branch Elizabeth Hill, Economist Economic Analysis Branch Biological and Economic Analysis Division (7503P) ) 

### Arnet Jones, Chief Biological Analysis Bran Diann Sims, Chief I



### Science Information and Analysis Branch Timothy Kiely, Chief Economic Analysis Branch Biological and Economic Analysi TO: Steven Snyderman, Chemical Review Manager Risk Management and Implementation Division Branch 3 Pesticide Re-Evaluation Division (7508P)
Product Review Panel date: May 13, 2015

1INTRODUCTION This memorandum presents BEAD'sresponse to comments submitted by Syngenta concerning the BEAD Chemical Profile (BCP) document included in the initial Registration Review for Metolachlor Case (Yourman et. al., 2014).

EPA Statement Page 2, 4th paragraph "Based on usage data for the same time period usage [1998-2012] for metolachlor averaged approximately 9 millionpounds active ingredient (a.i.) applied annually on approximately 6 million acres treated." Syngenta Comment: These numbers are correct butpresent an incomplete picture ofthe variation among years. From 1998

- 2000 Syngentawas deregistering metolachlor following the registration ofS-metolachlor and, as shown in BEAD's Figure 3, usage dropped from approximately 50 million pounds to around 20 million pounds. Use continued to decline as stocks were eliminated and by 2004 less than 500,000 pounds were applied. Atthis time metolachlor was re-introduced to the market by otherregistrants. Since then metolachlor usage has increased, so that overthe 2008-2012 period use has averaged roughly 3.5 millionpounds per year. The 9 million average pounds applied does not reflectthe current use pattern over the last five years. The same rationale applies to the acres treated. Based onproprietary data, the current.five year average is around 3 million acres for metolachlor.
BEAD Response: BEAD acknowledges and appreciates the clarifications offered by Syngenta and will take it into consideration as appropriate as registration review progresses.

EPA Statement (Page 2, 4th paragraph) "(Regarding metolachlor): The average a.i. use rate overthis time period was 1.5 pounds a.i./acre." Syngenta Comment: For the 1998-2002 period, the average rate per base acre for Syngenta's metolachlor was 1.74 lbs a.i. /A. This can be compared to the current metolachlor average use rate of 1.26 lbs a.i. IA. This reflects the reduction oflabelled use rates required by the Agency on metolachlorproducts to coincide withthe introduction ofS-metolachlor. Therefore, the blending ofthese two time periods for the average 1.5 lbs a.i. 

### I A is not representative ofactual use rates.
BEAD Response: BEAD acknowledges and appreciates the clarifications offered by Syngenta and will take it into consideration as appropriate as registration review progresses.

2EPA Statement (Page 4, 2nd paragraph; Page 4 Figure 1; Page5 Figure 2) "The use ofS-metolachlor increases, both in terms ofpounds a.i. applied and total areatreated, during the 1998-2012 time frame." Syngenta Comment: S-metolachlor was registered as a reduced risk replacement for metolachlor and its use increased rapidly during its introduction and conversion from metolachlor during the years of 1998-2002. This is better described as a replacement of metolachlor usage, rather than an increase in overall pounds applied. This was followed by a period ofrelatively constant use through 2009. Use has increased in the latter years partly due to an increase inplanted acres, and partly due to an overall increase inthe use ofpre-emergence herbicides as weed resistance to contact herbicides has developed.
BEAD Response: BEAD acknowledges and appreciates the clarifications offered by Syngenta and will take it into consideration as appropriate as registration reviewprogresses.

EPA Statement (Page 5, Table 1 2003-2007) "Average Annual Usage: 31,000,000 lbs/yr.% Lbs: Com 82,000,000; Sorghum 7,000,000; Soybean 3,000,000; Cotton 2,000,000; Other 6,000,000." Syngenta Comment: The presented values do not fit the column heading.
BEAD Response: BEAD acknowledges the error; values shouldhave beenpercentages, not millions ofpounds: 82 percent for com, 7 percent for sorghum, 3 percent for soybeans, 2 percent for cotton and 6 percent for other crops. The corrected table is shown below.
Table 

### 1. ComparisoJJ ofCrops with Highest Use ofS-metolachlor- Percent ofTotalLbs. Aoolied (2003-2007 and 2008-2012)

2003-2007 2008-2012 Average Annual Usage = 31,000,000 lbs/yr Average Annual Usage= 33,000,000 lbs/yr Crop %Lbs Crop %Lbs Com 82 Com 70 Sonmum 7 Soybean 13 Soybean 3 Sorghum (Milo) 5 Cotton 2 Cotton 5 Other 6 Other 7 Source: Proprietary Data, 2003-2012.

EPA Statement (Page 5, Table 2) 2003-2007 Average Annual Usage = 31,000,000 lbs/yr. Reported values by state: IL 17,000,000; IA 12,000,000; NE 10,000,000; KS 8,000,000; IN 8,000,000. Syngenta Comment: These values exceed the annual total of31,000,000 pounds in the line above. Itis possible thatthe values representthe total pounds across the 5 yearperiod and each value should be divided by 5 to get the annual average use. Then instead ofreporting the average pounds per state, a calculation canbe made to determine the percentage ofpounds per state to

3matchthe columns in Table 1to allow the comparison ofpercent lbs to the 2008-2012 time interval.


### BEAD Response: BEAD acknowledges the error; values should have beenpercentages, not millions ofpounds: 17 percent for Illinois, 12 percent for Iowa, 10 percent for Nebraska and 8 percent each for Kansas and Indiana. Table 2 shows corrected values, below.


### Table 2. Comparison ofStates with Highest Use ofS-metolachlor- Percent ofTotal Lbs. Applied (2003-2007 

### and 2008-2012)

2003-2007 2008-2012 Average Annual Usage = 31,000,000 lbs/yr Average Annual Usage = 33,000,000 lbs/yr State %Lbs State %Lbs Illinois 17 Illinois 12 Iowa 12 Nebraska 11 Nebraska 10 Kansas 9 Kansas 8 Iowa 8 Indiana 8 Indiana 6 Source: Proprietary Data, 2003-2012



### EPA Statement (Page 5, last paragraph) "Thepercent ofthe total use ofS-metolachlor decreased similarly inthe combelt states ofIL, IA, and IN, with increases inthe Plains states ofNE and KS." 

### Syngenta Comment: This conclusion cannot be determined without the percent ofpounds for the 2003-2007 interval being known.


### BEAD Response: BEAD acknowledges and appreciates the information provided. Table 2 has been corrected to capture the percent ofpounds used in each state relative to the S-metolachlor total pounds a.i. used.



### EPA Statement (Page 6, last paragraph) "Based onprivate market usage data from 1998-2012, usage for metolachlor averaged approximately 9 million pounds active ingredient (a.i.) applied annually on approximately 6 million acres treated. The average a.i. rate overthis time period was 1.50 pounds a.i./acre. 

### Syngenta Comment: This paragraphpresents a blend ofSyngenta's metolachlorusage at high volumes and high use rates during the phase-outperiod of 1998 thorough 2002 withthe lower usage ofmetolachlor at reduced use rates following 2002, whichmarks the introduction ofthe reduced use rate replacementproduct S-metolachlor. The average use rate of 1.5 lbs/a does not accurately reflect either usage scenario."


### BEAD Response: BEAD acknowledges and appreciates the information and clarification provided pertaining to last paragraph onpage 6 ofthe BCP document.

4EPA Statement (Page 8, 1st paragraph) "BEAD does not have information as to why there is a nearly fivefold increase in use, although resistance to otherherbicides or weather conditions that may increase weed pressure are possible (but unsubstantiated) explanations." Syngenta Comment: Syngentabegan cancelling its metolachlor end-use productregistrations in July 2001 and cancelled its metolachlor technical registration inAugust 2002. The first nonSyngenta metolachlor registrations occurred in the 2002-2004 timeframe. Thus, the metolachlor sales ofless than 100,000pounds reported in 2003 reflect the re-initiation ofmetolachlor to the market. Since corn is the main crop treated, the majority ofsales and usage during the earlierreintroduction ofmetolachlor (2003-2007) would be expected to occur in corn. As overall sales increased other crop uses expanded, resulting in a reduction inthe percentage ofusage devoted to corn. The expansion ofuse in crops other than corn also explains the reduced percentage of sales inmajor com-growing states.
BEAD Response: BEAD appreciates the informationprovided by Syngenta and will take itinto consideration as appropriate as registration review progresses.

EPA Statement (Page 12, 2nd paragraph) "Itis unlikely thatthere would be observable efficacy differences at labeled rates for products containing either formulation, although the overall amount used would be greater for metolachlor (e.g., Hartzler, 2004; Ohio, 2007)." Syngenta Comment: This statement is inaccurate, mainly because metolachlor is currently labeled at the same use rates as S-metolachlor. A 35% rate increase inmetolachlor is required to provide equivalent control to S-metolachlor. Therefore, "the amount used would be greater for metolachlor" is not an option to match the upper label rates ofS-metolachlor. A bulletin published bythe University ofIllinois (Hager 2007) explains the difference in S-metolachlor and metolachlor use rates and equivalency and notes, "while applying the same productrate ofan Smetolachlor-containingproduct and a metolachlor-containing product can provide similar amounts oftotal active ingredient, the amount ofthe active isomer applied can vary considerably." Likewise, researchers at Colorado State University (Shaner 2006) conducted a comparison study that concluded, inpart, "formulationsbased primarily onthe S-metolachlor isomer are more active on a gram for gram metolachlorbasis than formulations based on a racemic mixture of metolachlor containing a 50:50 ratio ofthe Rand S isomers." Ofnote, while showing a difference inherbicidal activity, this study also demonstrated similar soil binding behavior and rate ofsoil solution dilution between S-metolachlor andracemic metolachlor. The BEADreferenced Hartzler 2004 Iowa State University document states, inpart, "The Stalwart C label recommends the same productuse rate as those for Dual II Magnum, butthe product contains the less active unresolved form ofmetolachlor. This results in Stalwartproviding less 'weed-killing power' than Dual II Magnum when applied at equal rates. [

...] However, the reduced activity ofthe unresolved isomer will result in reduced performance in many situations (i.e. heavy weed pressure, difficult to kill weeds, dry weather, late-season weeds, etc.)." Page 49-50 ofthe BEAD-referenced Ohio State University 2007 publication (Corn: Soil
5Applied Herbicides

- Preplant or Preemergence) includes comparisons oflabeled Bicep II Magnum/Cinch ATZ and Stalwart Xtrause rates, as well as Dual II Magnum/Cinch and Stalwart C/Parallel use rates. The labeled application rates are shown with the following comment: "Stalwart Xtrahas undergone limited testing in OSU and Purdue University field research. Bicep II Magnum includes primarilythe S isomer ofmetolachlor, which allows the use oflower rates ofactive ingredient compared to a mix ofS and R isomers. The mix ofS and R metolachlor isomers in Stalwart Xtra is similarto Bicep/Bicep II, which should result in similar use rates. StalwartXtrause rates are similarto Bicep II Magnum, however, and are lower than use rates of Bicep/Bicep II."
A similar statement occurs under the Dual II Magnum/Cinch Use Rates and the Stalwart C/Parallel Use Rates: "Dual II Magnum includes primarilythe S isomer ofmetolachlor, which allows the use oflowerrates ofactive ingredient compared to a mix ofS and R isomers. The mix ofS and R metolachlor isomers in Stalwart and Parallel is similar to Dual/Dual II, which should result in similar use rates. Stalwart and Parallel use rates are similarto Dual II Magnum, however, and are lower than use rates ofDual/Dual."
These statements showthat users recognize that current metolachlor labelled use rates do not provide equivalent efficacyto that which is delivered bythe S-metolachlor products at equivalentrates. The Table 5 Weed Response to Herbicides in Com in the Ohio State University report shows the same weed control ratings for metolaclilor and S-metolachlor with the footnote, "Metolachlor and S-metolachlor, and premixes ofthese with atrazine, are available from a number ofmanufacturers

- see comherbicide descriptions for more information. Metolachlor products have undergone limited testing at their labeledrates in OSU and Purdue University research."
While some University Extension Services may combine S-metolachlor and metolachlor products into a single category whenpresenting information, this does not imply equivalency. This is demonstrated in the Ohio State Universitypublicationreferenced above, and in the 2014 Georgia ComProduction Guide published bythe University ofGeorgia. The University of Georgia guide presents S-metolachlor and metolachlorproduct information together but notes, "The generic formulations ofmetolachlor (Parallel, Stalwart, Me-Too-Lachlor) have not provided the same length ofresidual control ofcertain weeds at similarrates ofDual Magnum formulations in some UGA field trials." 

### Syngenta**refer~nces:** • Hager A. 4/13/2007. Isomers Resolved. The Bulletin: Pest Management and Crop Development Information for Illinois, No. 3 Article 4. • Shaner DL, Brunk G, Belles D, Westra P, and Nissen P. 2006. Soil Dissipation and Biological Activity ofMetolachlor and S-metolachlor in Five Soils. Pesticide Management Science 62: 617-623. • Lee D. 2014. A Guide to ComProduct in Georgia in 2014. The University ofGeorgia, College ofAgriculture and Environmental Sciences, Cooperative Extension, Crop and Soil Sciences.



### 6BEAD Response: BEAD hoped to clearly point out (Yourman et. al., 2014) that S-metolachlor had a greaterproportion ofactive isomer than metolachlor. BEAD appreciates the correction regarding labeled use rates being the same for products containing either active ingredient.

EPA Statement (Page 12, 2nd paragraph) "The reduction in use [ofmetolachlor] may be due to increased use ofalternative herbicides or other factors currently unknownto BEAD." Syngenta Comment: Syngentaproposes thatthe reduction [inpounds ofmetolachlor] is due to S-metolachlor being registered at approximately 35% lower use rates thanthose originally labeled for metolachlor. After S-metolachlorregistration, metolachlor labels were registered withthe same 35%reduction in use rates. This results in an overall reduction ofroughly 35% of total pounds applied, even ifthe number ofacres treated remains unchanged.
BEAD Response: BEAD appreciates the insight addressing the possible reason for a reduction inpounds ofproduct. BEAD pointed out (Figure 1, below) thatthe total acres treated decreased from a high ofapproximately 30 million acres in 1998, to 4.7 million acres in 2012.
FIGURE 1. MetolachlorTotalArea Treated in Acres (1998-2012)

00 35,000,000**~** 

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### 'V" 'V" 'V" Years
Source: Proprietary Data, 1998-2012. Originally shown in Yourman et al. 2014 (Figure 4, page 7).

REFERENCE Yourman, L., Alsadek, J. and Hill, E. 2014. BEAD Chemical Profile (BCP) for Registration Review: Metolachlor Case [S-metolachlor (108800) and Metolachlor (108801)], Nov. 6, 2014. [Registration Review EPA Docket ID No.: EPA-HQ-OPP-2014- 0772-0005].

7