UNITED STATES E NVIRONMENTAL PROTECTION AGENCY WASHINGTON , D
. C

. 20460 

### AUG 192015

OFFICE O F CHE M ICAL SAFETY A N O POLLUTIO N PREVE N TIO N
MEMORANDUM
SUBJECT:
FROM:

THRU:

TO: BEAD C hem ical Profile (BCP) for Registration Review: End othall (Case 2245 P C Codes: 038901-038908) Carl Chen , Biologist Biolo g ical Analysis Branch

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# ~ Economic Anal ys is Branch Biological and Economic Analy ·s Di v ision ( ..., ) Garland Waleko , Chemica l Revi e w Manager Pesticide Re-evaluation Division (7508P)
Peer Review Panel date : April 29, 2014SUMMARY Endothall is primarily u sed as an aquatic herbicide and bioci de, but it is a lso registered as a harvest aid for crops like cotton, alfalfa seed and c lover seed. BEAD has li ttle information o n the non-agricultural u ses of endothall, even though the amount of use in aquatic environments may be far higher than the amount used on agricultural crops.
INTROD UCT IO N The Biological and Eco nomic Analysis Divi s ion ( B EAD ) Chemical Profil e (BCP) provides an overview ofthe pest management roles and quantitative usage information for endothall. The BCP includes summaries of previous B EAD products and available pub li c and/or private use and usage data for Endothall to describe the role of this chemical in pest management. Additional information on us e is avai lable in the Endothall Label Data Report. Information provided in thi s BCP may be used by stakeholders (e.g. , users and registrants), OPP risk assessors , and OPP ri sk managers, and the general public during the Registration Re view process of this pesticide.
HISTORY OF ENDOTHALL AND BEAD PRODUCTS E ndothall is registered as an aquatic herbicide , d es iccant, and biocide. T he re are currently three active ingredients with e nd-use products associated with this case: endotha ll acid (03890 I) , endo thall-dipotass ium (038904) , and e ndothall mono salt (038905). Endotha ll acid (038901) is registered exclusively for use on cotton. Endo thall -d ipotas sium (038904) is registered exclus ively for aquatic use. Endothall mono salt (038905) is registered for use on alfalfa and clover grown for seed , potatoes, and for aquatic use. Hereafter, the term endothall refers to all three active ingredi e nt s in this case, unle ss otherwise specified. A Registration Eligibility Decision (RED) for endo thall was publi shed by EPA in 2005. BEAD has issued several documents on endotha ll since the RED was published. There were two rev iews of Section 18 Eme rge ncy Exemption req ues ts for the use of endothall to control weeds in irrigation canals w itho ut a holding time restriction. Endothall was requested by a canal company in Idaho after other control method s were determined to be too dangerous to company staff. B EAD concluded that thi s was an urgent s itu at ion where the canal company did not have saf e alternative control metho d s available (E PA 2008), and thus a Section 18 was issued. Another Section 18 request was made by the Nebraska Department of Agri culture. BEAD ' s review (EPA 2009) concluded that' there was not eno ugh information to eva luate the request , so no Section 18 was iss ued.

2USE SITES Agricultural Use S ites Endothall is registered as a desiccant for use on alfalfa and clover grown for seed, cotton , and potatoes. Non-Agric ultural Use Sites Endothall is registered for use in lakes , ponds , and irri gation canals to controls algae and submerged aquatic vegetati<?n, and to control mollusks and algae in commercial/industrial water cooling systems.
FORMULATIONS E ndothall is formulated as granular and soluble concentrate.
APPLICATION METHODS Endothall is app lied to terrestrial s ites as a broadcast application with air or ground equipment. For aquatic applications , endothall is applied by metering device , drip feed, injection , sprayer, or granul e applicator.

3USAGE Agricultural Usage

70,000

Pounds Al 

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co en 0 en en 0 en en 0

..... ..... N 

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..... N ,...,**~** U'I \D r-.. co en 0 ..... 0 0 0 0 0 0 0 0 0 ..... ..... 0 0 0 0 0 0 0 0 0 0 0 N N N N N N N N N N N

- Pounds Al

- T ota l Area Treated N ,...,

..... ..... 0 0 N N 210,000

Total Area

Treated

F igure 

### 1. E ndothall Total Acres Treated & Tota l Pounds A.I. App li ed (1998-2013). Sou r ce : Proprietary Da t a, 1998-2 013 Agricultural usage ofendothall was at one point quite high, with almost 210 , 000 acres treated in l 998. During the last five years, however, agricultural usage of endothall has been very low (F ig ure I). From , 2004-2008, approximately 4 , 500 pounds of endothall were applied annually. During this period , the majority of endothall u sed on agricu ltural crops was applied to potatoe s, with the remaining 30% be ing applied to cotton (Tab le l ). From 2009

- 20 1 3, no usage was record ed for potatoes and only a small amou nt was app li ed to cotton.
Table 

### 1. Comparison of Crops with Highe st Use of Endotha ll

- Percent of Total Pounds of A.I. A li ed between i004-2008 and 2009-2013. 2004-2008 Av e Annual = · 4,500 lbs Cro Cotton % ofTotal Pounds A lied 30 Potato es 70 So urc e : P ro prietary Da t a, 2004-2 013 Cro Cotton 2009-2013 e Annual 

## = I 50 lbs % ofTotal Pounds A lied

100

The only remaining agricultural crop with recorded endo thall usage is cotton. Approximately 150 lbs per year of endothall were applied to over 4,000 acres of cotton at an average rate of 0.04 lbs A.I per ac re between 2009 and 2013 (Table 2).

4Crop Cotton *Total Acres Treated sums all acres treated for a crop , including those acres that receive multiple treatments. Source: Proprietary Data, 2009-2013 Along with the decrease in total usage the number of states with recorded endothall usage also greatly decreased , from 16 between 2004 and 2008 , to just two between 2009 and 2013 (Table 3)
. This pattern reflects the end ofusage in potato production , as well as a decrease in usage on cotton.


### Tab le 3. Comparison of States with Highest Use of Endothall

- Percent of Total P 

### d A I A I" 

### db tw 2004 2008 

### d 2009 2013

oun s 

# . . .pp 1e e een 

## - an - 

# . 2()();b2008 " 2009-2013 - - Avera2e Annual = 4,500 lbs A verasze Annual = ISO lbs State % of Total Pounds State**~** % oJTotal Pounds Aoolied Annlled Colorado 40 Texas 55 North Dakota 20 California 45

Wisconsin 10

Ari zona 10 Texas 5 California 5

Other * 10 , *Other stat e s : ME , LA , OK , MS , AL, SC , PA , NY , TN , MO Source: Proprietary Data, 2003-2012
No usage data are available on endothall usage on alfalfa and clover seed crops. Non-Agricultural Usage In nonagricultural settings , endothall is used in lakes , ponds , and irrigation canals to control algae and submerged aquatic vegetation , and to control mollusks and algae in commercial/industrial water cooling systems. The only data available data on endothall usage in these sectors describes usage in golf course ponds to control the growth of aquatic plants. In 2011 , approximately 3 , 000 pounds ofendothall were applied to golf course ponds , accounting for less than 2 percent of total aquatic herbicide usage and making it the fifth most commonly used aquatic pesticide in this sector (Table 4).

5

### Table 4. Endothall use as an a Secto"F 2011 Golf Course Pond s 3 , 000 Source: Proprietary Data 2006, 2011 While no usage data are available on other aquatic uses of endothall , these other aquatic uses have the potential to be large.
CHEMICAL AND USE CHARACTERISTICS The endothall acid that results in pesticidal activity is fom1ed as a breakdown product from application of its salt forms. E ndothall is a contact herbicide and algicide. It can also function as a plant growth regulator to defoliate plants , and a biocide to control invasive organisms such as mollusk. Endothall ' s mode of action has not been classified by the Herbicide Re sis tance Action Committee (HRAC) or the Weed Science Society of America (WSSA) (HRAC, 2015 ; WSSA, 2015).
ROLE OF ENDOTHALL IN PEST MANAGEMENT Endothall is mainly used as an aquatic herbicide and algicide. It is registered to control aquatic weeds such as algae and submerged aquatic plants in ponds , lakes, and other water bodies unde r Section 3 of the Federal Insecticide , Fungicide , and Rodenticide Act (FIFRA). In Florida, the estimated aquatic usage of endothall for the p eriod of 2004-2005 is approximately 220 , 000 pounds of active ingredient (Moss i
. er and Langeland , 2006). Thus , the aquatic use in Florida alone dwarfs the agricultural uses nationwide. Multiple Section 2(ee) recommendations have also been issued for use ofendothall in 48 states to control aquatic plants including approximately 10 specific pondweed species (CDMS , 2015). Endothall and its salts are registered for use on cotton, potatoes, and seed crops of alfalfa and clover. One endothall end-use product, Des-i-cate , played a role as a harvest aid or a vine killer on potato crops but was cancelled in 2005. One endothall mono salt end-use product, Desicate II , is still registered for use on potatoes, however, no usage has been recorded in the past five years (Proprietary Data 2009-2013). As mentioned above , the data show current agricultural use of endothall only on cotton at a low le vel (Proprietary Data, 2009-2013).



### 6DATA NEEDS The Agency currently does not have complete information on endothall. Obtaining the following information may impro ve future assessments conducted by the Agency re lated to the use and importance of endo thall. Agricultural Use
• Endothall usage data for a lfalfa and clo ver seed crops , s uch as amount applied, application timing and area treated
. • Any information on the imp ortance of endothall compared to alternatives for cotton production
. Non Agricu ltura l Use
• EPA has little information on how much and how e ndothall is used for aquatic weed control. Usage data on aquatic uses of endothall , such as type of water body treated , amount applied , and the area treated would be very helpful.

7REFERENCES BEAD. 2014. Endotha ll Screening Level Usage Analysis. Biological and Economic Analysis Division, Office of Pesticide Programs , US Environmental Protection Agency. CDMS. 2015. Crop Data Management Systems (CDMS) Label Search. CDMS , Inc. Accessed March 2015 at https: // premier
.cdms.net/webapls/FormsLogin.asp? / webapls/
. \ EPA. 2005. Registration Eligibility Decision Endothall. Prevention Pesticides and Toxic Substances , US Environmental Protection Agency. http: //www.epa.gov IoppOOOO 1 /reregistration/REDs/endothall

_ red. pdf EPA. Pesticide Chemical Search Ehdothall. Online: http: //iaspub.epa.gov/ apex/pesticides/f?p = CHEMICALSEARCH:21 :0: :N0:2 l :P21

_NA ME VAL:\ENDOTHALL%20AND%20SALTS%20REREGISTRA TION%20CASE\ HRAC. 2015. Classification of Herbicides According to Site of Action. Herbicide Resistance Action Committee (HRAC). Accessed March 2015 at http: // hracglobal.com/pages/classificationofherbicidesiteofaction
. aspx Kline and Company , Inc. , 2006 , 2011 Mossier MA , Langeland KA. 2006. Florida Crop/Pest Management Profile: Aquatic Weeds. PI138 of Pesticide Information Office. Florida Cooperative Extension service. University of Florida. Accessed April 2015 at h ttps: //edis.ifas.ufl
.edu/pil 75
. Proprietary Data. 1998-2013. (pesticide usage data) WSSA , 2015. Classification of Herbicides According to Site of Action. Weed Science Society of America. Accessed March 20 1 5 at http ://weedscience
. org / documents/ showdocuments.aspx?OocumentID= I 19 3
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