Re: SMM Amended RED - Comments Regarding Buffers 

Russell Wasem to: Jack Cain 03/29/2010 03:16 PM

Cc: Jim Tompkins, Thomas Moriarty

Bcc: Michele Knorr, Peter Caulkins

Greetings Jack,

We have discussed the issues raised in the email below, and your earlier email dated January 11, 2010. 

Outside of your comment regarding the AgDrift model, we believe most of your points can be address 

when you submit amended labels and we do not intend to further amend the Sulfometuron Methyl RED. If 

there are points DuPont, or other registrants, feel can be communicated on a label better and stay within 

the intent of the RED then we suggest you submit this in your draft labels. 

Regarding your comments on AgDrift's ability to model rights of way scenarios and the Agency's 

consideration of AgDrift modeling in the buffer zones for sulfometuron, the AgDrift model is the current 

drift modeling tool and it has been considered in the reregistration of sulfometuron and numerous other 

pesticides with similar uses. The Agency considered both the limitations of the AgrDrift modeling scenario 

and the benefits of sulfometuron use when reaching its regulatory decision. And while the buffer zones 

modeled RQs above the Agency's level of concern, EPA considered these risks in balance with the 

benefits of suflometuron use.

If DuPont wishes to propose conducting a drift study that demonstrates estimated environmental 

concentrations of sulfometuron when applied in a rail or rights of way scenario, then the Agency would 

consider using such data as new and relevant for assessing spray drift risk from sulfometuron 

applications. 

This email and the two emails referenced earlier in this email will be added to the docket. 

Regards,

Rusty____________

__________

Rusty Wasem / Chemical Review Manager

Risk Management & Implementation Branch 1*

Pesticide Re-evaluation Division* / Office of Pesticide Programs

703 / 305 6979

Jack Cain Dear Rusty, Thank you for taking the time to spe... 01/27/2010 06:18:14 PM

From: Jack Cain <Jack.Cain@USA.dupont.com>

To: Russell Wasem/DC/USEPA/US@EPA

Cc: Jim Tompkins/DC/USEPA/US@EPA, Thomas Moriarty/DC/USEPA/US@EPA

Date: 01/27/2010 06:18 PM

Subject: SMM Amended RED - Comments Regarding Buffers

Dear Rusty,

Thank you for taking the time to speak with me this past Thursday regarding

the Amended Sulfometuron Methyl (SMM) RED, and your invitation to submit in

writing the concerns we discussed specific to the subject of buffers.

I would first like to commend you and the many others within EPA for acting

in response the large number of Public Comments received following the
initial publication of the SMM RED. The Amended RED clearly reflects your

considerations and DuPont is especially pleased with the revised

Environmental Hazards labeling requirements. The new statements address

our shared stewardship concern for off-site movement, and will only serve

to further emphasize existing label precautions.

We would like to address two concerns related to the buffer text as

currently required in the Amended RED. The first pertains to use site

applicability, and the second is in regard to intent. Following is our

rationale as to why the buffers set forth in the Amended RED should not be

applicable to right of way, railroad, or industrial site applications, and

not established opposite crops.

SMM containing products are applied to a variety of agricultural (crop) and

non-agricultural sites. Forested areas including conifer and hardwood crop

plantations, and rangeland (crop) restoration sites are generally

characterized as large plot areas similar to many agricultural row crop

sites. However, over 50% of SMM containing product applications are

actually made to non-agricultural sites described as roadway, utility,

pipeline and railroad Right-Of-Ways (ROW), and industrial sites. The

Environmental Fate and Effects Risk Assessment that issued on November 28,

2007 specifically noted in the section entitled Identification of

Uncertainties and Their Impact on the Risk Assessment that “There are a

variety of Vegetation Management uses on sites that are less clearly

defined than agricultural crops and have disjoint or unusual treatment area

configurations. (e.g.: as with rights of way and railroad uses, or

industrial site grounds).” In this same Assessment, spot spraying was

categorized as a method of application in forestry sites, but not on ROW

sites. In the context of buffers we believe this was a significant

oversight.

The current requirements for aerial application buffers of 75 feet,

broadcast ground application buffers of 50 feet, and spot spray ground

application buffers of 30 feet were all predicated directly or indirectly

on results obtained using the AgdriftTM model. Input parameters of use rate

and droplet size were varied, but in all instances an agricultural

application site scenario was modeled. For aerial applications the model

employed an application swath width of 60 feet, and 20 (adjacent) flight

lines (a total treatment area width of 1200 feet). Ground modeling was

comprised of a swath width of 45 feet and 20 applied swaths (a total

treatment area width of 800 feet). Also, in a footnote to the ground model

it was noted that “For ground application scenarios the AgdriftTM tier I

model is restricted to using Fine to Medium coarse (droplet sizes), and can

not model Very coarse, which is required.”

A Railroad ROW seldom exceeds a total width of 100 feet, or 50 feet from

center line to either side of the rail bed. These sites are treated with

single swath applications which typically extend 10 to 20 feet each side of

center line. The untreated balance of the ROW may serve as a buffer but it

is not uncommon for growers to plant agricultural crops on the untreated

portions of these easements based on prior experiences including minimal

injury due to herbicide ROW application. The sides of primary roadways are

also treated with single swath applications that seldom extending more than

25 feet beyond the side of the road. Secondary road treatment areas are

considerably smaller. In ROW application scenarios where the use of a boom

may be obstructed by a sign post, guardrail, etc., or there is a recognized

risk to adjacent areas, applications are augmented by hand held spot

spraying. These spot treatments are made around the base of the

obstruction and extended only a few feet in width. A typical guardrail

application only extends 1 to 2 feet each side of the rail. These spot
spray applications to ROW sites are completely dissimilar to agricultural

applications where a treatment may encompass up to 20% of each treated

acre.

The disparity of using the AgdriftTM model for large plot vs. ROW

applications needs to be recognized when establishing buffers on labels.

Otherwise, a much needed use of SMM will be substantially curtailed or

eliminated. DuPont is supportive of buffers when applications are made to

large plot sites consistent with the model, but respectfully submits that

ROW and Industrial site applications do not even begin to approximate the

modeled scenarios. The risk to adjacent non-target species from ROW and

Industrial site applications is significantly less, and the buffers that

have been established based on agricultural use scenarios should not be

applied to these sites.

The EFED Risk Assessment for SMM identifies the "Basis for Direct Effect

Concerns" to terrestrial and semi-aquatic plants as the: “Endangered

species LOC is exceeded for terrestrial plants”, and the "Basis for

Indirect Effect Concerns" is: “Potential concerns from shifts in plant

community structure and function due to/from selective impacts on plant

species.” The Assessment also notes that “plants are the primary producers

upon which the succeeding trophic levels depend.” The LOC’s that were

presented in the Risk Assessment were derived from study data on five

aquatic vascular and non-vascular species, and ten terrestrial monocots and

dicots. DuPont agrees with EFED that the sensitivities of these various

surrogate species are a Basis for Concern that legitimizes the requirement

for buffers opposite aquatic plants, their habitats, and any threatened or

endangered species. But there is no environmental concern to warrant the

establishment of buffers opposite all crops.

In my previous correspondence of January 8, 2010 I called your attention to

a number of errors and ambiguities including the matter of requiring "Very

coarse or coarser" vs. Extremely coarse nozzles for all applications. I

had anticipated these matters might be addressed prior to the issuance of

an SMM Data Call-In (DCI). However, as I am now it receipt of the SMM DCI,

I would encourage the Agency to resolve these items before a registrant

seeks a label amendment action in accordance with them. I would also hope

that the issues raised herein regarding buffers may be similarly resolved.

Sincerely,

Jack Cain

DuPont Crop Protection

Stine-Haskell Research Center

1090 Elkton Rd.

Newark, DE 19711

jack.cain@usa.dupont.com

Office: 302 366-6417

Cell: 610 316-5006

Fax: 302 351-6841

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