UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, D.C. 20460 

### OCT 1 3 2011

MEMORANDUM OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION

SUBJECT: BEAD Chemical Profile for Registration Review: Paraquat Dichloride (061601) FROM:

THRU: Sunil Ratnayake, Biologist 

# n Biological Analysis Branch
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- JihadAlsadek,Economist

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## .A-~ Science Information and Analysis Branch Derek Berwald, Economist 

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### ~**~ ~**  Biological and Economic Analysis Divisi (7503P) Arnet Jones, Chief Biological Analysis Branch Diann Sims, Chief Science Information and Analysis Branch

# ~**~** Timothy Kiely, Chief \ A " Economic Analysis Branch VV\.. Biological and Economic Analy' ivision (7503 TO: Christina Scheltema, Chemical Review Manager Risk Management and Implementation Branch 3 Pesticide Re-evaluation Division (7508P)


### Product Review Panel date: June 22, 2011 INTRODUCTION The purpose ofthis document is to convey usage information and a broad overview ofthe pest management roles ofpesticides that are beginning to undergo registration review. The anticipated audience consists ofthe team ofEPA staffcurrently evaluating the registration status ofParaquat Dichloride (061601), and eventually the general public. This document builds upon the data already provided inthe "Usage and Label Use Data Packages" that are also provided toRegistration Reviewteams by BEAD. The document is based on infonnation and data available to BEAD as ofJune 22, 2011. Paraquat dichloride is a non-selective herbicide whichbelongs to the bipyridyliums class of herbicides and it is applied to the foliage ofweed plants as a burn-downtreatment. Also, it can be applied as a band, spot, ordirected treatment after the crop emergence. Inthe United States, paraquat dichloride was first registered in 1964 and became the most widely used herbicide until the registration ofglyphosate (pesticide news, 1996). The mode ofaction ofthis class of herbicide is the inhibition ofthe photosynthesis process. The activity ofparaquat dichloride depends onthe sunlight and affected plants shows quick wilting and desiccation. Paraquat dichloride is also applied,as a pre-harvest desiccation treatment on some crops including cotton (peterson et al. 2001). 

### USE SITES Agricultural Use Sites Cereal and oil seed crops, cotton, fruit and nut crops, and vegetables Non-Agricultural Use Sites Airports, conservation reserve lands, fallow lands, right ofway, non-crop areas, lawns and storage yards. COMMON FORMULATIONS AND APPLICATION METHODS Paraquat dichloride is fonnulated as flowable and emulsifiable concentrates only. Application methods are aerial, broadcast, band treatment, directed spray, ground spray, spot treatment, spray, and tree wound treatment. This herbicide should not be applied through any type of irrigation systems. 

### USAGE Agricultural Based onprivate market pesticide usage data from 1998-2010, the annual total agricultural usage . averaged approximately 3 million pounds active ingredient for 7 million treated acres, for an overall average application rate of0.4 lbs. a.i. per acre. From 1998-2010, the crops with mostpounds used are cotton (25%), com (23%), soybeans (9%), and almonds (7%). Crops with mosttreated acres are cotton (37%), com (20%), soybeans (8%), peanuts (5%), and almonds (4%) and alfalfa (4%). On average, the states With the most agricultural use intenns ofpounds a.i. applied are California (23%), Texas (17%), and Georgia (5%) (Proprietary Data, 1998-2010). Non-Agricultural Lawn Care Operators (LCOs) used about 3,000 pounds a.i. ofparaquat dichloride in 2004. The use ofparaquat dichloride innurseries/greenhouses was almost 2,000 lbs. a.i. in 2002 and 2004 and decreased to less than 1,000 lbs. a.i. in 2006 (Kline and Company, Inc 2002-2006).
2USE TRENDS Figure 1provides usage trends, interms ofpounds applied, for paraquat dichloride's leading agricultural markets. The use ofparaquat dichloride on almonds, com, cotton, soybeans, and other crops fluctuated during the period 1998-2010. The dataprovided in this section is provided for preliminary scoping purposes only because the data have notbeen analyzed. Figure 1. Paraquat dichloride Usage Data 4,500,000 

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• Other Crops PoundsA.I. • Soybeans • Cotton • Corn 

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"Other crops" include wine grapes (5%), alfalfa (4%), apples (4%), and table grapes/oranges/peanuts/peaches (2% each). Source: Proprietary Data, 1998-2010 BIOLOGICAL ASPECTS RELEVANT TO PARAQUAT DICHLORIDE Unlike many other herbicides, paraquat is effective under lowtemperatures and when weeds are having little active growth. This is an important characteristic ofparaquat and ithelps for early season seedbed preparation. Rainfall soon after application has little or no effects onthe performance ofparaquat. The activity ofparaquat is light dependent. In soil, paraquat is deactivated bytight adsorption to clay particles. Paraquat does not have residual activity and it canbe applied before planting crops or seedling emergence (Syngenta Crop Protection, 2011). It has beenreported that hairyfleabane (Conyza bonariensis), horse weed (Conyza canadensis), goosegrass (Eleusine indica), dotted duckweed (Landoltiapunctata), and American black nightshade, (Solanum americanum) have developed resistance to the mode ofaction ofthis class ofherbicides (WSSA, 2011).
HISTORY OF BEAD ASSESSMENTS FORPARAQUAT DICHLORIDE There have been only two recent analyses ofparaquat by BEAD. In 2006, BEAD analysts considered the market effects from entry ofgeneric paraquat into the herbicide market. There was considerable uncertainty intheir estimates, butthey found that costs to consumers of paraquat may be reduced $6 to 9 millionper year as a result ofcost competition from generics (Kim et al, 2006). In 2005, the registrant applied for registration ofa newparaquat productthat 3contained additional emetic and a gelling agent, which might reduce poisoning from ingesting paraquat. BEAD was asked to evaluate the additional costs to growers and estimate the value of reduced deaths that mightresult from these additional protections, ifthe new formulation replaced the old. The additional cost ofthe newformulation to growers was small, and unlikely to result inusers switching to alternative pesticides, althoughthe aggregate costs were estimated to be from $1.8 to $ 2.3 million. The value ofreduced illnesses was dominated bythe value from reducing deaths, over $15 millionper year if2.4 deaths were prevented each year, on average. However, there was no way to determine ifillnesses actually would be prevented by the changes, so the benefit estimated by BEAD was the range $0 to $15.4 millionperyear (Zinn and Kim, 2005). DATANEEDS RELEVANT TO BEAD'S FUTURE WORK ON PARAQUAT DICHLORIDE Obtaining additional information onthe following items would improve future BEAD assessments ofthe importance ofparaquat dichloride and may be required as part ofthe registrationreview ofthis pesticide. Use on/in fallow land, airports, commercial buildings, conservation reserve program land, fencerows, right-of-way, areas around commercial/industrialbuildings including pumping stations and pipelines pumping stations, substations, and storage areas. REFERENCES International Survey ofHerbicide Resistant Weeds. 2011. http://www.weedscience.org/In.asp
. Proprietary Data, 1998-2010. Kim, J., Istanbul, Y., and A. Grube, 

### Economic Impacts a/Generic ParaquatEntry, April 27, 2006. Kline and Company, Inc 2002-2006. Paraquat. 1996. Pesticides News. No.32, June 1996, p20-21. http://www.panuk.org/pestnewsl Actives/paraquat.htm
. Paraquat Fact Sheet. 2011. Syngenta Crop Protection. http://paraquat.comlspanishlnodeIl94
. Peterson, D, Thompson, D. R. Regehr, D. L. and K. AI-Khatib, 2001. Herbicide Mode ofAction. Publication ofAgricultural Experiment Station and Cooperative Extension Service. Kansas State University
. http://www.northeastcropadvisers.orglherbicidemode.pdf
. Zinn, N., and J. Kim, 2005
. Paraquat Assessment, D323223. OPPIBEAD memorandum. December 8, 2005.



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