UNITED STATES ENVIRONMENTAL PROTECTIONAGENCY WASHINGTON D.C., 

### 20460

OFFICE OF PREVENTION, PESTICIDES AND TOXIC SUBSTANCES

PC Code: 1 18601 DP Barcode: D330621 Date: May 10, 2005 MEMORANDUM SUBJECT: Revised Environmental Fate and Ecological Risk Assessment of Chlorsulfuron TO: Susan Jennings, Chemical Review Manager Special Review and Reregistration Divis' FROM: Brian D. Kiernan, Biologist Environmental Risk Branch IV 

# d Environmental Fate and Effects Division (7507~) THROUGH: Kevin Costello, Risk Assessment Process Leader Environmental Risk Branch IV Environmental Fate and Effects Division (7507~)

2' I APPROVED .c* BY: Elizabeth Behl, Branch Chief Environmental Risk Branch IV Environmental Fate and Effects Division



### Please find attached the electronic file containing EFED's revised ecological risk assessment in support of the reregistration (DP Barcode D330621) of chlorsulfuron (PC Code 11 8601). 

### This is the fourth revision of the ecological risk assessment and should replace the previous assessment under DP Barcode D289953.

### Office 

### of 

### Prevention, Pesticides, and 

### Toxic Substances



# Environmental Fate and Ecological Risk Assessment for the Re-registration of Chlorsulfuron

CAS Registry Number: 64902-72-3 

### PC Code: 118601

Prepared by: Dan Balluff, Biologist U. S. Environmental ProtectionAgency Dirk Young, PhD, Environm Office of Pesticide Programs Brian D. Kiernan, Biologist. Environmental Fate and Effects Division Environmental Risk Branch IV 1200 Pennsylvania Ave., NW Reviewed by: Mail Code 7507C Kevin Costello, Risk Assessment Process Leade Washington, DC 20460 Elizabeth Behl, Branch Chief

### Acknowledgments
The authors would like to thank Dr. Leo LaSota and Dr. Norman Birchfield for their assistancein this assessment.

### TABLE OF CONTENTS
EXECUTIVESUMMARY



### ...................................................... v ChlorsulfuronUsage



### ..................................................... v



### ....................................................... Chlorsulfuron Risk v



### .......................... Toxicity and Risk to Non-target and Endangered Plants v



### ..................................................... PROBLEM FORMULATION 1 AnalysisPlan



### ........................................................... 1



### .................................................... Assessment Endpoints 1



### ................................................. Measures of Effect 1



### .............................................. Measures of Exposure 2



### ........................................................ Conceptual Model 2 INTRODUCTION



### ............................................................. 3



### ...................................... Identification and Mechanism of Action 3



### ....................................... Use Characterization and Formulations 3



### ............................................ Rate and Method of Application 3



### ................................................. Current Label Restrictions 5



### ................................. ENVIRONMENTAL FATE CHARACTERIZATION 6



### ................................................ Chlorsulfuron Fate Studies 

### 7



### ....................................................... Hydrolysis 

### 7



### .......................................... Photodegradation in Water 

### 7



### .............................................. Soil Photodegradation 

### 7



### ............................................ Aerobic Soil Metabolism 8



### ....................................... Anaerobic Aquatic Metabolism 

### 8



### .................................................. Bioaccumulation 8



### .................................................. Field Dissipation 

### 8



### ......................................................... Sorption 9



### ............................................... Water Resource Assessment 9



### .......................................... Surface Water (Farm Pond) 10



### ............................... Drinking Water Assessment for Human Health 12



### .................................................... Surfacewater 12 Groundwater



### .................................................... 12



### ............................ Drinking Water Recommendationsto HED 13



### ................................. ECOLOGICAL EFFECTS CHARACTERIZATION 14 TerrestrialAnimals



### ..................................................... 14 AquaticAnimals



### ....................................................... 14



### ....................................................... Terrestrial Plants 15 Aquaticplants



### ......................................................... 15



### .................................... Toxicity Studies (from Public Literature) 16



### ............................................... Fletcher et 

### al., 

### 1995 17

### ................................................ Coyneretal

.. 

### 2000 17



### ........................ Field Studies. Greenhouse Studies. and Incident Reports 18



### ..................................................... Fieldstudies 18



### ......................................... Fletcher et al.. 1993 18



### ........................................... Bhattietal..1995 19



### ............................................... Greenhouse Studies 19



### .......................................... Non-target Plant Incident Reports 19



### .................................................. RISKCHARACTERIZATION 21

. 

### RiskEstimation



### ........................................................ 21



### ................................ Risk Quotients for Terrestrial Animals 21 Risk Quotients for Freshwater and Marinelestuarine Fish and Invertebrates



### ...21



### ........................ Risk Quotients for Aquatic and Terrestrial Plants 22 Aquaticplant



### .............................................. 22



### ...................... .................... Terrestrial Plants r 

### 22 RiskDiscussion



### ........................................................ 28



### ..................................... Terrestrial and Aquatic Animals 28



### ....................................... Terrestrial and Aquatic Plants 28



### ............................... Terrestrial Plants (Seedling Emergence) 29



### .................................. Terrestrial Plants (Vegetative Vigor) 30 Plants Exposed to Irrigation Water Containing Chlorsulfuron



### .............. 31 Plants Exposed to Chlorsulfuron Drift



### ................................. 31 Refined Assessment of Spray Drift on Non-target Terrestrial Plants



### ............... 32 EndangeredIThreatenedSpecies



### ........................................... 46



### .............................................................. REFERENCES 47 APPENDIX 1



### . PRZMIEXAMSINPUT FILES



### ..................................... 51 APPENDIX 2



### . SUMMARY OF CHLORSULFURON TOXICITY TESTS FOR TERRESTRIAL AND AQUATIC ANIMALS



### ................................ 64 APPENDIX 3



### . DATA REQUIREMENTS FOR CHLORSULFURON



### ................... 67 APPENDIX 4 ESTIMATED ENVIRONMENTAL CONCENTRATIONSON AVIAN AND MAMMALIAN FOOD ITEMS (PPM) FOLLOWING A SINGLE APPLICATION AT 1 lbai/A



### ................................................................ 70 APPENDIX 

### 5 NON-TARGET TERRESTRIALPLANT SEEDLING EMERGENCE TOXICITY (TIER 11) FOR CHLORSULFURON (TEP 75%; lbs a.i./A).



### ........... 71 APPENDIX 6 NON-TARGET TERRESTRIAL PLANT VEGETATIVE VIGOR TOXICITY (TIER 11) FOR CHLORSULFURON (TEP 75%; lbs a.i./A).



### ..................... 72

iii

### APPENDIX 7



### . RQ CALCULATIONSFOR SURFACE AND GROUNDWATER IRRIGATION



### ......................................................... 73



### ........ 

### . APPENDIX 8



### . REFINED SPRAY DRIFT ANALYSIS FOR CHLORSULFURON 74



### ........ APPENDIX 

### 9



### . TIER 

### 1DRINKING WATER ASSESSMENT MEMORANDUM 84

### EXECUTIVE SUMMARY Chlorsulfuron Usage 

### Chlorsulfuron isa broad spectrum, pre-emergent andpost-emergentsulfonylurea herbicide applied by both aerial and ground equipment to small grains such as wheat, barley and oats. It is also registered for use on pastures, rangeland and fallow fields. Non-crop sites include: unimproved turx industrial turx industrial sites, ornamentals, and non-crop restoration. Chlorsulfuron Risk 

### Based on a screening level [deterministic] risk assessment, e~timatedexposure concentrations to terrestrial and aquatic animals do not exceed either acute or chronic risk levels of concern at current maximum application rates; however, acute risk levels of concernfor nontarget terrestrial and aquatic plants are exceeded by orders ofmagnitude. In regions where chlorsulfuron has been used regularly, chlorsulfuron concentrations in ground and surface irrigation water may result in damage to agricultural crops that are sensitive to chlorsulfuron. Additionally, some available literature data indicate that small quantities ofdrift may reduce the fruit development in nontarget plant communities. Because plant RQs are above non-endangered species LOCs, the Agency cannot preclude the potential for effects to those listed species that rely either on a speciJic plant species (plant species obligate) or multiple plant species (plantdependant) for some important aspect oftheir life cycle, given the current extent ofanalysis ofexposure, effects and co-occurrence oflisted resources and areas ofuse. The extent towhich the use ofchlorsulfuron onwheat andpasture/rhngeland will indirectly effect listed animal species will require identlJicationof listed species that co-occur in areas ofchlorsulfuron use and an evaluation of critical habit as described below. Because ofthe national extent ofthe labeled uses ofchlorsulfuron, given the level of refinement ofthisanalysis we cannot preclude the possibility ofa 'may effect' designation for all listed animals. Uncertainties 

### There is uncertainty regarding the extent to which the incident data can be associated with chlorsulfuron alone. Additionally, while the risks to nontarget plants @om direct application of chlorsulfuronhave not been estimatedquantitativelyin this riskassessment, riskquotients for direct application to plants are expected to be higher than those estimated for indirect exposure through runoffand/or drift. ToxicityandRisk toNon-target and Endangered Plants 

### Screening level (Tier 1) deterministic risk quotients (RQs) for direct effects to endangered plants exceed the endangered species level ofconcern (LOC) by several orders ofmagnitude. For aquatic plants, RQs for endangered species range from 18 to 31. 

### The range of RQs for endangered

### plants inwetlands was 122 to 693. 

### RQs for endangered terrestrialplants rangefrom 21 for ground application tosmall grains to 580JFomspray drift resultingfrom aerial applications to rangeland


### A refinedspraydrift assessment has been performed to better characterize the potential risk tonontarget plants at varying distances @om a chlorsulfuron-treated field. mereas the initial Tier 1 assessment includes RQs calculated from the most sensitive 

### EC,, from guideline laboratory plant toxicity tests, this refined assessment looks at a range ofeffect levels 

### (EC,, to

### EC,d for all the plants tested that might occur from exposure tospray drift only. Thisassessment considered both ground and aerial application, maximum application rates for pasture and rangeland and typical application rates for wheat, and a variety of wind speeds and droplet size spectra. The results ofz this assessment indicate thatwhile the extent ofpotential risk depends on the application rates and conditions chosen, almost all of the scenarios indicate that we cannot preclude the potential for effects to plants hundreds offeetfrom 

### chlorsulfuron-treatedfields, given the extent ofthis analysis ofexposure, effects and co-occurrence of listed resources and areas ofuse. 1. 

### PROBLEM FORMULATION Chlorsulfuron is.abroad spectrum, pre- and post-emergent herbicide used on a range of agricultural and nonagricultural uses. Originally registered for use in the United States in the early 1980'sthe chemical is now undergoing re-registration in accordance with the Food Quality Protection Act (FQPA). As 

### part of the re-registration effort, the Environmental Fate and Effects Division of the Office of Pesticide Programs is assessing the environmental fate and ecological risk of the current uses of chlorsulfuron. 

### 1.1 Analysis Plan
In general, the analysis plan and rationale for completing this assessment, 

### i.e., the problem formulation, has been to,determine whether current label uses of chlorsulfuron provide a means of exposure that could potentially represent the likelihood of adverse effects (risk) to nontarget endangeredthreatened and non-endangered animals and plants that could potentially impact thereregistration eligibility decision under the Federal Insecticide, Fungicide and Rodenticide Act, the Food Quality Protection Act, and the Endangered Species Act. Over the course of its assessment, the Office of Pesticide Programs (OPP) has attempted to refine its problem formulation for ch1,orsulfuronby integratingbothregistrant-submitted guidelinedataand information collected from open literature to characterize the environmental fate and ecological effects of chlorsulfuron. 

### 1.2 Assessment Endpoints 

### 1.2.1 Measures of Effect
Assessment endpoints are intended to be explicitexpressions ofthe actual environmental value that is to be protects and for the purposes ofthis ecological risk assessment are operationally definedby an ecological entity and its attribute. The assessment endpoints of this ecological risk assessment include terrestrial and aquaticanimal and plant mortality following acute exposureto chlorsulfuron

### and terrestrial and aquatic animal reproduction, growth and survival effects from chronic exposure

I 

### to chlorsulfuron. The valued entities are terrestrialand aquaticvertebrates and invertebrates, aquatic vascular and nonvascular plants, and terrestrialplants. The attributesused to gauge the effects of chlorsulfuron on the valued entities are acute mortality l 

### and chronic reproductive, growth (length and weight) and survival effects. The most sensitive toxicityendpoints areused fiom surrogatetest species (receptors) to estimate treatment-related direct effects on acute mortality and chronic reproductive, growth and survival assessment endpoints. 

### FIFRA Part 158 guideline toxicity tests (CFR 40 9158.202, 2002) are intended to determine pesticidal effects on ecological entities that include birds, mammals, fish, terrestrial and aquatic invertebrates and plants. Thesetestsinclude short-term acute, subacuteandreproduction studies and aretypically arrangedin ahierarchical ortiered system which progresses fiom basic laboratory tests to applied field studies. The studies areused to evaluatethe potential of apesticide to cause adverse effects,to determine whether further testing is required, and to determinethe need for precautionary label statementsto minimize the potential adverse effects to non-target animals and plants (CFR40 

## 5 158.202,2002). 1.2.2 Measures of Exposure 

### The risk assessment process considers formulationsused for soil and foliar treatments, including granular, as well as seed treatments. Not all routes of exposure are considered, though. This ecological risk assessment does not take into account atmospheric transport in estimating environmental concentrations,nor doesit account for ingestion ofchlorsulfwonresiduesby animals in drinking water or contaminated grit, ingestion through preening activities, or uptake through inhalation or dermal absorption by terrestrial animals. Exposure to terrestrial animals is based primarily on dietary consumption of foliar residues and treated seeds while aquatic assessments assume that all potential routes of direct exposure are accounted for. Maximum application rates on vulnerable soils for representative crops are selected for modeling environmental concentrations forthis screening-level deterministic (risk quotient-based) assessment. This assessment is not intended to represent a site or time-specific analysis, i.e. 

### assessments are intended to represent a national-level exposure based on vulnerable soils as opposed to being a regionally specific exposure assessment. Likewise, the most sensitive toxicity endpoints are used from surrogatetest speciesto estimate treatment-related direct effectson acute mortality and chronic reproductive, growth and survival assessment endpoints. Toxicity tests are intended to estimate pesticidal effects on birds, mammals, fish, terrestrial and aquatic invertebrates and plants. These tests include short-term acute, subacute and reproduction studies and are typically banged in a hierarchical or tiered system which progresses from basic laboratory tests to applied field studies. The studies are used to evaluate the potential of a pesticide to cause adverse effects,(to determine whether further testing is required, and to determine the need for precautionary label Statementsto minimize the potential adverse effects to nontarget animals and plants (CFR 40 §158.202,2002). 1.3 Conceptual ModelThe conceptual model used to depict the potential ecological risk associated with chlorsulfuron is fairly generic and assumes that as a pesticide, chlorsulfuron is capable of affecting terrestrial and aquatic animals provided environmental concentrations are sufficiently elevated as a result ofcurrent label uses. In agricultural ecosystems there is a patchwork of crops interspersed with pasture and natural plant communities and as a herbicide, chlorsulfuron poses a potential threat to vegetation growingon adjacent land ifitis appliedto crop land and inadvertentlydriftsandlorruns offinto nontarget areas. Adverse consequences of such an event will likely vary depending on the level of exposure (e.g.aerial vs ground application), plant species involved, habitat (aquatic 

### ys terrestrial), plant size, and stage of development ofthe plant. The response may range from plant death to sublethal effects with no apparent alteration of plant growth, depending on different combinations of these variables.
2.0 INTRODUCTION
2.1 Identification and Mechanism 

### of Action
Chlorsulfuron is a broad spectrum herbicide, structurally classified as a sulfonylurea. Its mode of action is the inhibition of amino acid synthesis in plants through inhibition of acetolactate synthase (ALS);ALS is the first common enzymein the biosynthesis ofbranched-chain amino acids (valine, leucine and isoleucine). ALS inhibition in plants adversely affects plant growth and reproduction. This enzyme pathway does not existin animals; therefore, the herbicide is less toxicto animals than plants. 

### 2.2 Use Characterization and Formulations Chlorsulfuron-containing productswere firstregisteredin theUnited States in theearly 1980s. There are six products currently registered for use in the U.S. These include: TELARB DF, GLEANB FC, FINESSEB, Chlorulfuron Technical, LANDMARKQ MP, LANDMARK II@ MP, and CORSAIRB. Over 80% of chlorsulfuron use is on cereal grains (wheat, oats and barley) to control a wide variety of weed pests. Over 5 million acres are treated annually. Most of the acreage is treated with 0.01 lbs ailacre or less. The vastmajority ofchlorsulfuronis appliedto winter wheat. The remaining uses are primarily spring wheat and oats. Little data exist on therecently approved pasture and rangeland uses. Registered applications with little or no current usage include lawn and ornamentalturf. The non-crop land and industrial turf sites includes use onroadsides, railroads, industrial sites, rights of way, airports, fence rows, and lumberyards for control of noxious weeds. 

### For cereal grains, the greatest chlorsulfuronusage is 

### in Kansas, followed by Oklahoma, Montana, Washington, Texas, Nebraska, North Dakota, and California. For the non-crop market, the greatestusage is 

### in Iowa, followed by Washington, Oregon, Colorado, Idaho, Minnesota, Mississippi and Nebraska. 2.3 Rate and Method 

### of Application
Forthe cereal use, there is only one applicationper season, with thetypical rate being 0.1875 ozlacre (0.0 1 lb ailacre). The use rates on cereals range from 0.16 oz acre to 0.5 oz ailacre (0.0 1-0.03 lbs ailacre). Only growers with hard-to-kill weeds, such as ryegrass, use the highest rate (0.03 lbs

### ailacre). Pasture and rangeland uses are labeled for 0.0625 lbs ailacre. For other non-crop uses, the most common use rate is 0.375 ozlacre (0.02 lbs ailacre). Typically only one application is made per season. While higher rates (up to 0.25 lbs ailacre) are not typical, they can be used for control of noxious weeds in support of state and federal programs.
For the non-crop uses, some selective weeding of rough turf sites may require two applications within a year 

### - once in the fall for control of thistles, and again in the spring for general broadleaf control. These repeat applications are made at 3-7 month intervals and take place on less than 2% ofthe turf acrestreated with chlorsulfuron. Non-crop acres treated forthe purposes of generalweed control or bare ground maintenance receive only one application per year. 

### A single yplication in non-crop situations intheWestern United Statesisgenerally madeinNovembertoMarch/Apriltime frame. 

### In the West, environmental conditions 

### and weed pressure may necessitate a second application.

### Inthe South, multiple applications (2-3) arecommonduringacalendarye$ at>3month intervals. The highest rates (0.047 

### - 0.25 lbs ailacre) are for sod farms, golf bourses, and ornamentals. Application rates and methods for chlorsulfuron are presented in 

### Table 

### 1.
Table 1. 

### Chlorsulfuron Use Information Maximum number of

. . . . . - .. - . . seasonaYyearly
Barley Broadcast 0.0078 - 0.016 Ranges from once per crop season 0.016 lbs ailacre Post-emergent aerial or ground to once every 36 months (Finessea (Finedsea label does label does not specify) not specify) Oats Broadcast aerial or Up to 0.023 Range of once per crop season to 0.023lbs ailacre pre-emergent ground every 36 months Oats Broadcast aerial or 0.0078 

### - 0.016 Range of once per crop season to 0.016 lbs ailacre Post-emergent ground once every 36 months Wheat Broadcast aerial or 0.0195 - 0.023 Range of once per crop season to 0.023 lbs aiiacre Pre-emergent ground once every 36 months (Finessem (Finessea label does label does not specify) not specify) Wheat Broadcast aerial or Post-emergent ground

Pastures and Broadcast aerial or rangeland ground Fallow Broadcast aerial or ground Unimproved turf Broadcast ground only 0.0078 - 0.016 Range of once per crop season to 0.016 lbs ailacre once every 36 months (Finessea (Finedsem label does label does not specify) not specify) 0.012 

### - 0.0625 Label does not specify 0.0625 lbs ai per acre per 12month period 0.0078 - 0.016 Label does not specify Label does not specify I 0.012

. Label does not specify 0.023 lbs ailacrelyear
Unimproved Broadcast ground 0.01 17

### - 0.0234 2 per year 0.0234 lbs ai per acre industrial turf only (Telarm DF label does not specify) per 12-monthperiodNon-crop sites Broadcast ground 0.047 

### - 0.021 Label does not specify 0.12 lbs aiiacrelyear only Non-crop Broadcast ground 0.0212 

### - 0.14 Label does not specify 0.125 lbs ailacre (industrial) sites only (Telar DF label does not specify) Non-cropland Broadcast ground 0.021 - 0.031 Label does not specify 0.125 lbs ailacrelyear restoration only Sod farms and Handheld or boom 0.047 - 0.25 2 per year (60 day interval) 0.50 lbs ailacrelyear golf courses sprayer Ornamentalslfine Broadcast ground 0.13 -0.25 2 per year turf only 0.25 

### - 0.50 lbs ailacreper year 

### 2.4 Current 

### Label Restrictions Current chlorulfuron labels contain a numberofrestrictions that may tend to mitigate to some degree the potential impacts of chlorsulfuronon non-target and endangered plant species. For example, statements on the FinesseQ label (EPA Reg. No. 352-445) indicate that "Finessemherbicide is recommended for use on land primarily dedicated to the long-term production ofwheat and barley". Thisrecommendation may serve to decreasethe likelihood that irrigation water contaminated with chlorsulfuronwill be inadvertently applied to agricultural crops that are sensitive to chlorsulfuron. FinesseQ labelsprovidethe followingprecaution: "Do not apply to irrigated land where tailwater will be used to irrigate other cropland." The extent to which this statement serves to decrease chlorsulfbron contamination of surface water used for irrigation is uncertain.
Some label precautions appear to suggest that synergistic effects may occur if chlorsulfuron is appliedto fieldsto which certain other insecticides have been applied. The FinesseQ label statesthat "FinesseQshould not be used within 

### 60 days of crop emergence if an organophosphate insecticide (such as "Di SystonQ")was used as an in-furrowtreatment, or crop injury may result." Presumably, neither of these two pesticidesif used alone will cause crop injuryto wheat or barley. However,the Finessem label indicatesthatthey apparentlydo cause crop injury when used together. This suggests that there may be synergistic effects to plants when chlorsulfuron is applied to fields along with organophosphate insecticides. The Finessem label also indicates that "tank-mix applications of Finessem plusAssertQ may cause temporarycropdiscoloration/stuntingorinjury whenheavyrainfall occurs shortly after application". Additionally, the label restrictstheuse ofFinessem plus Malathionm and the use of FinesseQ plus LorsbanQ in the Northwest, as crop injury may result. Although current EFED plant toxicity study guidelines do not include full life-cycle testing, label statements appear to suggest that chlorsulfuron may have an impact on plant reproduction. For example,theFinesseQ label includes the following statement "Do not apply FinesseQ duringtheboot stage or early heading stage, as crop injury may result." Several statements have been placed on chlorsulfuron labels to reduce the likelihood of spray drift. The Finessem label provides the following statement: "When applying Finessem by air in areasnear sensitive crops, use solid-stream nozzles oriented straight back. Adjust swath to avoid spray driftdamage to downwind sensitive crops and/or use ground equipment to treat border edges of fields". The extent to which these statements reduce the potential for spray drift is uncertain.
An indication of the persistence of chlorsulfuronunder actual field conditions is provided in the ~inesse'label, in the table on rotation intervals. The table indicates that the rotation interval for non-cereal crops in non-irrigated land ranges from 11 months for field corn to 48 months for sorghum. These intervals indicate that chlorsulfuron may persist in the soil at levels that are toxic to plants for extended periods of time. Additionally, Finesse' labels provide the following precaution: "To reduce the potential for movement oftreated soil due to wind erosion, do not applyto powdery, dry, or light sandy soil until they have been stabilizedby rainfall, trashy mulch, reduced tillage or other cultural practices. Injury to adjacent crops may result when treated soil is blown onto land used to produce crops other 

### than cereal grains". The extentto whichthis statement servesto decreasethe movement ofChlorsulfuron contaminated soils into nearby fields in which non-cereal crops are grown is uncertain. Several labels haverestrictionsbased on soil pH. Primarilytheserestrictions areto protect replanted cropsafter chlorsulfuronapplication. Several labels (e.g, Dupont Glean' and Finesse') prohibit the use of chlorsulfuron on soils with pH greater than 7.9 because chlorsulforon is quite persistent at high pH and replantingsmay sufferthe effects ofresidual chlorsulfuron. 

### In certain statesthese labels require a field bioassay if pH is above 6.5 to determine whether planting is feasible. Crop rotation intervals are pH dependent in some states. Supplemental labels may imply that the maximum pH limitation is less for certain statelcrop conditions.Some labels (e.g., Dupont Telar' and Landmark' MP) appear not to restrict the use chlorsulfuron based on soil pH, but instead onlb restrict the replanting interval. Other labels (e.g., ~esco'TFC and Riverdale Corsair') spqcify reduced application rates on soils with pH above 7, but do not prohibit use at any specific soil pH. Chlorsulfuron may be broadcast applied by air or ground equipment to small grains at application rates that range fiom 0.0078 to 0.023 lbs ailacre. It may be broadcast applied by air or ground equipment to fallow, pasture, and rangeland at rates that range from 0.0078 to 0.0625 lbs ailacre. According to product labels, it appears that the non-crop uses may only be applied by ground equipment. Application rates range fiom 0.021 to 0.33 lbs ailacre. Several ofthe chlorsulfuronlabels do not specify information needed to fully assess the ecological risk. This risk assessment assumes a single application where the label is not specific. Actual exposure may be substantially higher. This screening level ecological risk assessment for non-target and endangered plants focuses on the small grain,turf,rangeland, and pasture use sites because they representthe use siteswiththe largest amount of current or potential chlorsulfuron use. However, some of the non-crop uses have higher applicationratesthan the crop uses. Ifrisk quotientswereto be calculated forthe chlorsulfuronnoncrop uses withthehigher application rates,they would likelyresult inhigher risk estimates than were calculated for the crop uses.3.0 

### ENVIRONMENTALFATE CHARACTEFUZATION Chlorsulfuron 

### (2-chloro-N-[[(4-methoxy-6-methy1-1,3,5-triazin-2-yl)amino]carbonyl] benzenesulfonamide, 

### Figure 1)is likely to be persistent and highly mobile in the environment. It may be transported to nontarget areas by runoff andlor spray drift. Degradation by hydrolysis appearstobe themost significant mechanism for degradationofchlorsulfuron, but is only significant in acidic environments (23 day half-life at pH = 5); it is stable to hydrolysis at neutral to high pH. Degradation half-lives in soil environments were quite variable and ranged from 14tb 320 days.



### Figure 1. 

### Chemical structure of chlorsulfuron

3.1 

### Chlorsulfuron Fate Studies
3.1.1 

### Hydrolysis Chlorsulfuron degraded with a half-life of 23 days in the pH 5 solution, but was stable in the pH 7 and 

### 9 solutions. Hydrolysis tests (MRID 421567-01) were performed in buffered solutions at pH values of 5, 7, and 

### 9 at 25OC. Buffered solutions were made from Milli-QTM water and acetate, phosphate, and borate buffers, respectively. Initial chlorsulfuron concentrations were 5 mg/L. Chlorsulfuron concentrationswere measured at 

### 3, 7, 14, 21, and 3 1 days. Major degradates were from the pH 5 test were chlorosulfonamide (33% of applied), ring-opened chlorsulfuron (16% of applied), o-desmethylchlosulfuron (10% of applied), and lesser amounts of triazine and dihydroxy triazine.
3.1.2 

### Photodegradation in Water Chlorsulfuron does not readily photodegrade in water. Tests were conducted at pH 5, 7 and 

### 9 at temperature of 25°C over 3 1 days (MRID 421567-02). 

### 3.1.3 

### Soil PhotodegradationSoil photolysis tests (MRID 421 567-03) showed that chlorsulfuron degraded with a half-life of 65 days. The test soil was a Nora silty clay (20% sand, 52% silt, 29% clay, 2% organic matter, Cation Exchange Capacity [CEC] 19.6meq/100g,pH 8). Minor degradates were observed at lessthan 10% of the applied and included: dihydroxy triazine, triazine amine, triazine urea, and o-desmethyl chlorsulfuron. 

### 3.1.4 Aerobic Soil Metabolism
Soil metabolism tests (MRID 422142-01) conducted at 25OC showed a wide range in variability of the aerobic soil half life of chlorsulfuron. In a silt loam soil (21% sand, 63% silt, 17%clay, 2.75% organic matter and a ofpH 6.4), chlorsulfuronhad a half-life of 14days. In another soil (24% sand, 68% silt, 8% clay, 2.6% loam, pH 9, CEC 15.03 meq/lOOg), chlorsulfuron had a half-life of 11 , months. In older submitted studies

### (MRID0 113-0013and 0 113-0024),chlorsulfuronhalf-lives were 1 to 2 months. In more recent publications, Andersen 

### etal. (2001) reported chlorsulfuron half-lives of 50 days for soil taken from 30 to 35 cm below surface, 160days for soiltaken 40 to 45 cm below surface and 230 days for soil taken at 70-75 cm below surface. One reason for the decrease in degradation rates was possibly due to a decrease in microbial activity with depth. Andersen 

### et al. (2001) did not report near-surface soil data due to interference problems. Major degradates were 2- 

### chlorobenzenesulfonamide (30-35%),

### 2-arnino-4-methoxy-6-methyl-1,3,5-triazine, and2-chloro-N- 

### [[(4-hydroxy-6-methyl-1,3,5-triazin-2-y1) -amino]carbonyl]benzenesulfonamide(1 5%). 

### In all ofthe studies, it is not clear how much degradation occurred by microbial metabolism or by hydrolysis. 

### 3.1.5 Anaerobic Aquatic Metabolism Chlorsulfuron is relatively stable under conditions of anaerobic metabolism. Controls degraded faster than test systems. Hydrolysis was likely the dominant mechanism in the system 

### (MRID 421467-04). In recent literature, Berger and Wolfe (1996) found 

### an anaerobic sediment half life of 89 days and 301 days for unsterile and sterile sediment respectively; however for another sediment systemit was 182days and only 10 1 days for the sterile system. Increased hydrolysisvia lower pH changes upon heat sterilizationwere attributed to these counterintuitive results. 

### 3.1.6 Bioaccumulation Preliminaryfishbioaccumulation studies(MRID 422 142-04) showed channelcatfishaccumulation factors of 1.5X in edible tissue, 12X in viscera, and 7X in liver. Residues declined by 90-95% duringthe depuration phase. 

### In preliminarybluegill sunfish studies the bioaccumulation was 4X in the viscera, 6X inthe liver, with residue decline of 70-90 % in the depuration phase. Chlorsulfuron has a relatively low KO, of 2.13 at pH 5, 0.10 at pH 7, and 0.04 at pH 9 at 25OC. This information is sufficient to indicate that chlorsulfuron has a low potential to bioaccumulate. 

### 3.1.7 Field Dissipation Although guideline field studies were not submitted, older lysimeter studies were available and provide sufficient information to evaluate chlorsulfuron field dissipation for this assessment. In thefield lysimeter studies (MRID 422142-02), estimated half-life ranged from 20 days to several months. MRID 422142-02 is a compilationof several studies identified by the registrant-assigned report numbers in parenthesis that follow. Lysimeter studies in Delaware, North Dakota, and Nebraska (ReportNo. 63-82) were conducted on both an alkaline and an acidic soil. For the acidic soils the dissipationhalf-life ranged fiom 1to 2 months, and for the alkaline soils, dissipation halflives were reported to be 2 

### - 4 months. Another study (Report No. AMR 307-84) was carried out in the Fall in Ohio, Idaho,North Dakota, and in the Springin Alberta, Manitoba and Siiskatchewan, Canada. Dissipation half-lives were reported to be 1to 3 months for the Spring studies and 5 to 11 months for the Fall studies. Leaching of chlorsulfuron was apparent. Thetime.for detectable levels of chlorsulhron to reach 22 

### - 35 cm ranged from 1to 40 months. In another lysimeter Study (Report No. AMR 1417-89) leaching was also apparent down to the 18-24 inch range. The reported dissipationhalf-life was 20 days. In all the studies, only minor amounts (4 0%) oftwo degradates 

### (2-chlorobenzenesulfonamide and 

### 2-amino-4-methoxy-6-methyl-1,2,3,5-triazine) wdre observed.
3.1.8 Sorption A summary of batch sorption tests is given in the table below. Batch studies (MRID 421567-05) were conducted on four soils with an equilibration time of 24 hours at 25 

### "C. From the sorption parameters chlorsulfuron can be considered mobile (Table 2). It is expected (as with many chemicals that become increasingly anionicwith increasing pH) that the mobility of chlorsulfuron will increase with increasing pH.
Table 2. Summarv of Submitted Sorntion Studies of Chlorsulfuron Registrant's

Name texture YO CEC soil % silt % clay % om meq1100 Kf lln Koc " for Soil sand pH mgA/(mg/kg) 

### '" g (mllg)
Madera loam 48 35 17 0.8 19.6 - 8 0.28 0.9 60
> Woodstone sandy loam 60 33 7 1.1 5.3 6.6 0.09 0.85 14 Keyport sllt loam 20 39 2 1 19 6 4 5.7 0.38 0.88 34 Flanagan silt loam 2 81 17 4.3 21.1 5.4 0.91 0.91 36 " Koc is based on the sorption coefficient at 1mgL. 3.2 Water Resource Assessment
Due to its mobility and persistence, chlorsulfuron may contaminate surface and groundwater. Fate studies show that chlorsulfuron is mobile, and that mobility should increase as the environmental pH increases (chlorsulhron becomes more anionic as pH increases, see for example the variation in 

### KO, withpH inthe bioaccumulation section). Chlorsulfuron is alsopersistent, and itspersistence should also increase with increasing pH.
To obtain information about the occurrence of sulfonylurea (SU), sulfonamide (SA), and imidazolinone (IMI) herbicides in the Midwestern United States,2 12water sampleswere collected from 75 surface water sites (177 samples taken) and 25 groundwater sites (29 samples taken) in

### 1998. These samples were analyzed for SU, SA and IMI herbicides. Samples were collected from streams, large rivers, reservoir outflows, and wells. All reconnaissance samples were analyzed for 16 SU, SA and IMI herbicides. The 75 surface water sites were located in the Upper Mississippi, Missouri, and Ohio River basins. Twenty groundwater samples were collected fiom a network of municipal wells in Iowa. The depths of the wells ranged from 6 to 83 m. with most yells less than 30 m. Samples were also collected fiom five observation wells in lower Illinois. These wells were less than 8 m deep. Of the 130 samples taken from Midwestern rivers and streams, only 1 sample contained chlorsulfuron (0.013 pglL) above the method reporting limit of 0.01 ,ug/L. Battaglin reported no chlorsulfuron detections out of 25 ground water samples. This is likely due to the very low application rate of chlorsulfuron(Battaglin et 

### al., 2000) and its expected low concentrations in the environment. However, it isunclearto what extentthe locations of sampling sitesoverlapwith areas where chlorsulfuron is applied. Because of limitations 

### in the monitoring data, estimated environmentalconcentrations 

### inthis assessment were calculatedsolelyfiomthe Pesticide RootZone Model coupledwith theExposure Analysis Model System(PRZMIEXAMS)and SCI-GROWmodel results. These models are consistent with the Agency's screening level assessment process. 

### i 3.2.1 Surface Water (Farm Pond)

I 

### Surface water concentrations resulting from chlorsulfuron application to wheat and turf were predicted with PRZM (version 3.12 beta) coupled to EXAMS (version 2.98.04). Four scenarios were simulated- North Dakota wheat, Texas wheat, Pennsylvania turf and Florida turf. Application timing was estimated fiom the product labels, and a range of application dates were used. A summary of chemical properties used as PRZMIEXAMS inputs is given in Table 

### 3, and copies of actual input files are in Appendix 7. 

### Because of its low degradation rate, chlorsulfuron concentrations continually increased overthe simulation period and chronicandpeak concentrations are nearly the same for all scenariostested. Table 

### 4 presents the peak and average concentrations for the simulated farm pond. Note that the standard EFED pond is confined such that flushing by external flows does not occur, and therefore, concentrations.mayaccumulate over time to a higher degree than would a pond with flow into and out ofthe system. The date chosen for thle application had a small (absolute) effect on the output, as EEC values are within about 1 ppb; bowever, the relative difference is substantial, i.

### e., up to about 30%. For a protective assessment, dhe highest of these values should be used.Table 3. Salient Chemical Properties of ChlorsulfuronUsed for PRZMIEXAMS Modeling I I

Solubility Vapor Pressure Parameter Molecular Weight 3 1800mgll 4.6 e-6 torr Koc 

# 1 36 mug 

# I mean of values in Table 2 Value 357.8

Aerobic Soil half life Notes

Aerobic aquatichalflife 320 days

Photodegradation 90% ci from submitted studies (half life data :14, 330, 60 days)

Anaerobicmetabolism 

# I stable 

# I

Table 4. Summary of Ecological Concentrations Modeled with PRZMIEXAMS. Chlorsulfuron applied once per season at maximum labeled rate applied aerially. All values in ppb.

, Scenario Formulation Date peak 96 hr 21-day 60-day 90-day year and Application Applied Hydrolysis

ND wheat Glean 1 -Apr 4.2 4.2 4.2 4.2 4.2 1 4.2 0.023 lblacre 1 -May 4.1 4.1 4.1 4.1 4.1 4.1

TX wheat Glean 1 -Aug 5.5 5.5 5.5 5.5 5.5 5.5 0.023 Iblacre 1-Sep 5.8 5.8 5.8 5.8 5.8 5.7

I 15-Sep 6.0 6.0 6.0 6.0 6.0 5.9 1 -0ct 6.3 6.3 6.3 6.3 6.3 6.3 stable

PA turf Telar 15-3 0.0625 Iblacre 1-4 15-4 1-5 15-5 scenarios are performed at pH =7

FL turf Telar 1-3 0.0625 lblacre 1-4 1-5

### 3.3 DrinkingWater Assessment for Human Health 3.3.1 

### Surface Water
This drinking water assessment focuses on parent chlorsulfuron only. EFED is unaware of a determination by the Health Effects Division's (HED's) metabolism committee as to whether any degradates should be included in a chlorsulfuron drinking water assessment. If metabolites of concern are identified a revised assessment will be prepared. EFED previously conducted a Tier 1 human drinking water assessment which can be found in 

### Appendix 9. Although HED did not indicate problems with the concentrations from the Tier 1 assessment, EFED performed a Tier 2 human drinking water assessment in order to be consistent with the Tier 2 ecological water assessment described above. Concentrationsofchlorsulfuron in drinking water sources forthe Tier 2 assessment were estimated with PRZMIEXAMS for surface sources. Four standard agricultural scenarios were investigated, which appear to capture the high end use scenarios. Because the scenarios are the same as those used forthe ecological assessments,the application date chosen was the date that gavethehighest exposure values atreasonable application dates as determined fromthe 'ecological assessment PRZMEXAMS runs. The final concentrations reported in 

### Table 

### 5 are

reduced by the percent crop area (PCA) factors reported in the table. 

### Table 5. 

### Summary of estimated screening level surface water drinking water concentrations for chlorsulfuron in pg/L ( 

### ppb). Scenario Formulation PCA Application Peak Chronic Date (PP~) (PP~) ND wheat Glean 0.56 May 1 0.32 0.23 0.023 lblacre TX wheat Glean 0.56 Sep 15 0.95 0.25 0.023 lblacre PA turf Telar 0.87 April 1 1.3 0.93 0.0625 lblacre FL turf Telar 0.87 Aril 1 0.0625 lblacre 

### 3.3.2 Groundwater
Groundwater concentrations were estimated with SCIGROW, which is EFED's standard model for estimating groundwater concentrations ofpesticides. For further information on this model see the EFED water model website at http:l/www.epa.govloppefedl/models/water/.The following model inputswere used: applicationrate =0.0625 lblacre, on applicationper year, half-life =320 days, and 

### KO,= 36. With these inputs, SCIGROW estimates the groundwater concentration to be 1.6 ppb.

### 3.3.3 Drinking Water Recommendations to HED
The surface water EECs in 

### Table 6 were based on a PRZMEXAMS simulation using EFED's standard Index Reservoir. The Pennsylvania turf scenario was found to provide the highest EECs among 

### the scenarios tested. For groundwater, the SCIGROW-derived model estimated concentration of 

### 1.6 yg/L was derived from the cotton scenario (see previous section). 

### Appendix 9 provides additional details on the drinking water assessment for chlorsulfuron.



### Table 6. Drinking Water Estimated Environmental Concentrations for Chlorsulfuron Acute Concentration Chronic Concentration (upper 1-in-10 year peak (upper 1-in-10 year annual mean concentration) concentration) Surface Water 1.9 yglL 0.96 pa Groundwater 1.6 ygk 1.6pa

### 4.0 ECOLOGICAL EFFECTS CHARACTERIZATION Toxicity testing reported in this section does not represent all species of bird, mammal, or aquatic organism. Only a few surrogate species for both freshwater fish and birds are used to represent all freshwater fish (2000+) and bird (680+) species in the United States. For mammals, acute studies are usually limited to Norway rat or the house mouse. Estuarinelmarine testing is usually limited to a crustacean, a mollusk, and a fish. Also, neither reptiles nor amphibians are tested. The assessmentofrisk orhazard makesthe assumptionthat avian andreptilian toxicities aresimilar. The same assumption is used for fish and amphibians. 4.1 

### Terrestrial Animals

4.2 

### Aquatic Animals Chlorsulfuron is practically non-toxic to birds and mammals on an acute exposure basis and is also practically nontoxic to birds on a subacute dietary exposure basis. Following chronic exposure, bobwhite quail (Colinus virginianus)exhibited significant reductions in femalebody weight, 14day old survivors/normal hatchlings, viable embryosleggs set, and 14 day hatchling survivalleggs set (NOEC = 174mglkg diet/day). A toxicityendpoint for chronic mammalian toxicity isnot available. Chlorsulfuronisalsopractically nontoxic to honeybeeson an acutecontactbasis. 

### Table 7aprovides a summary of the most sensitive ecological toxicity endpoints used in the hazard assessment of terrestrial animals.
Table 7a. Summary of acute and chronic toxicity data for terrestrial organisms exposed to chlorsulfuron.

Chlorsulfuron is practically nontoxic to both fi-eshwaterand estuarinelrnarine fish on an acute exposure basis and is slightly toxic to estuarinelmarine invertebrates. 

### Chronic exposure of rainbow trout (Oncorhynchusmykiss)

### to chlorsulfuronresulted in aNOEC 

### of32 mg/L 

### while a 

### chronic study ofwaterfleas (Daphniamagna)

### resulted in 

### aNOEC 

### of20 

### mg/L. Table 7b summarizes the most sensitive endpoints used in the risk assessment of aquatic animals. No Chronic Toxicity

........................................................... NOEC/LOEC (pprn) i Endpoints (MRID) il
I 174

# '961 

### ! reproduction (426340-01) i,

. ..........................................................................................

-- --

............................... A ...........................
-- --

............................... a ...........................

-- -- Species

Northern bobwhite quail Colznus vzrgznzanus

................................................................

Mallard duck Anasplatyrhynchos

.............................................

Honey bee Apzs rnelEferus

.............................................

Laboratory rat Rattus norvegzcus Acute Toxicity

.................................................................................................. i Acute Oral i 5-day i Subacute Dietary LD50 Toxicity i LC,, i Toxicity (PPrn) (MRID) i (pprn) i (MRID)



### -- . 

### -- . -- --

A.. ........................A.................. i practically non- 

### -- -- i >5,000 i toxic i (000352-66)

..........................................................
-- . -- 9 -- 25 pglbee i ...................$..........................
A .................................................. i practically non- i



### . -- 5,500 i toxic I -- i (000314-06) i

### registrant-submitted data were available to assess the toxicity of chlorsulfuron to beneficial terrestrial insects or the chronic toxicity to estuarinelmarine animals. A more detailed listing of the ecological toxicity studies that went into this assessment can be found in 

### Appendix 2.

Species 96-hr LC, 48-hr EC,, j Acute Toxicity NOEC

, i Affekted Endpoints (mglJ-4 i (m@) i (MRw (mgk) i (MRID) Table 7b. Summary of acute and chronic aquatic toxicity data for chlorsulfuron.

Rainbowtrout i PracticallyNontoxic Oncorhynchusmykiss >250 j -- 000352-59 419764-05 (formulated product)

....................... A .................................................... Acute Toxicity

Water flea i Practically Nontoxic 

# I 1

-- 

# 1 i >370 i Daphnia magna 000352-62

........................................... ........................................................................................ .............................. 4 ....................................... 419764-08 Chronic Toxicity


# I Sheepshead minnow i PracticallyNontoxic 

# I

-- >980 j -- -- Cyprinodon variegatus 419764-01

........................................... ......................*................................................................ ..............................+.......................................



### 4.3 

### ~errestrial Plants Mysid shrimp Mysidopsis bah~a



### Laboratory-derived toxicity values for terrestrial and aquatic plants are summarized Table 

### 8. Chlorsulfuronis toxic to nontargetterrestrial plants with EC2,values as low as 1.0x 10-,1bsa.i./acre and an NOEC value of 5.4 x lbs a.i./acre (vegetative vigor). Based on available data, the slope of the dose-response curvefor chlorsulfuron varies between species, suggestinga range ofexpected sensitivities.
Table 

### 8. The most sensitive Tier I1 seedling emergence and vegetative vigor (MRID 

### 463618-01 and 

### 463268-01) toxicity endpoints for dicots and monocots exposed to chlorsulfuron. i SlightlyToxic 89 i -- 419764-02

Crop Seedling Emergence (Shoot dry weight) Crop Vegetative Vigor (Shoot dry weight) -- --

NOEC ECzs NOEC ECzs (Ibs

### a.i/A) (Ibs 

### a.i./A) (Ibs 

### a.i./A) (Ibs 

### a.i./A)

Dicot Pea 1.8 x lo4 2.2 x lo4 sugarbeet 

### 5.4 x 104 1.0 10" Monocot onion 

### 4.6 x 10"" 3.1 x lo4 onion 

### 5.4 lo6 2.2 x 10" *shootlength 

### 4.4 Aquatic Plants Aquatic plant toxicity ranged f?om practically nontoxic to very highly toxic. Duckweed 

### (Lemna gibba) was themost sensitivevascular aquaticplant, with an EC,, of 3.5

### x 

### 1 mg ai/L and aNOEC of 2.4 x loF4 mg ai/L (Table 9). 

### The most sensitive nonvascular aquatic plant is green algae (EC5,=5.5x 

### 1 0-5 mg/L; NOEC=9.5x 1 0-6 mg/L).Table 9. Summary of Chlorsulfuron Toxicity Tests For Aquatic Plants Study Type (%Active. Ingredient) Species Toxicity Value (application rate) MRID'Acc.' study Classification Author (Year) Aquatic plant growth Pseudokzrchnerzella EC,, = 0 000055 mg/L 421868-01 Supplemental' (98.2%) subcapztata NOEC = 0 0000095mgL Blasburg, J. et al. (1991) Aquatic plant growth Skeletonema costaturn NOEC =I26 mg/L 458329-02 Core (97 8%) EC50 >I26 mg/L R L.Boeri et al. (2001) Aquatlc plant growth Navzculapellzculosa NOEC =I26 mg/L 458329-04 Core (97.8%) EC50 >I26 mgL R L Boer1 et al (2001) Aquatic plant growth Anabaenaflos-aquae NOEC = 0.236mgL 458329-03 Core (97.8%) EC50 = 0.609 mgL R.L.Boeri et al. (2001) Aquatic plant growth Lemna gzbba NOEC = 0.00024mg/L 458329-01 Supplemental' (97.8 %) EC,, = 0.00035 mg/L R.L.Boeri et al.

11 Thls studywas conducted under static conditions Test concentrations should be renewed 3-4 times during the 14 day test. Because of guideline deviations, some studies are classified as supplemental and do not fulfill data requirements for plant toxicitytesting. However,these studies were determined to be scientifically sound and are suitable for use in the screening level risk assessment for non-target and endangered plants. 

### 4.5 Toxicity Studies (from Public Literature) The Agency's ECOTOX database contains references for studies on chlorsulfurontoxicity to 48 plant species in 38 genera and 14families. Monocotyledonous plants included nine genera and 11 species in the Poaceae (grass family) and one species in the Liliaceae (lily family), while dicotyledonousplants were represented in 12 families, 27 genera and 39 species. Khodayari etal. (1985)foundthatwild garlic (Alliumvineale;Liliaceae) suffered2 1-3 5%mortality of mature plants at 0.027 lbs a.i./A, while Leys and Slife (1988) found biomass reductions between78 and 96% in seedlings of the same species at the same rate. 

### In the Poaceaceae, wheat (Triticum aestivum) and barley (Hordeum vulgare) were generally unaffected by chlorsulfuron at ratesup to 0.5 lbs a.i./A (Lemerle, et al., 1990;Martin et al., 1990;Mersie and 

### Fry; 1986;Brewster and Appleby, 1983). Corn (Zea mays) seedling biomass was reduced 47-70% at an application rate equivalentto 0.0045lbs a.i./A (Rubinand Casida, 1985),ryegrass (Loliumrigida) seedling biomass was reduced10-70% at 0.022 lbs a.i./A (Matthews et al., 1990) and green bristlegrass (Setaria viridis) seedling biomass was reduced 23% at a rate of 0.0018 lbs a.i./A (Nalewaja and Woznica, 1985). Dernoeden (1990) found the 'percent cover of Kentucky bluegrass (Poa pratensis) was reduced 11-23% at a rate of 0.14 lbs a.i.lA and of Korean lawngrass (Zoysia japonica) 0-26% at a rate of 0.09 lbs a.i./A.

### Dicotyledonous plants were generally more sensitiveto chlorsulfuron application than monocots, with the possible exception ofthe wine grape (Vitis vinijiera; Vitaceae) which demonstrated a 23% reduction in biomass at a rate of 0.16 lbs a.i./A (Moore and Elliott, 1989). Seedlings of the mint Lamium amplexicaule (Lamiaceae) suffered 66% mortality at rates of 0.016 lbs a.i./A (Khodayari et al., 1985). Evening primrose (Oenothera lacinata; Onagraceae) mortality was 91% at a rate of 0.008 lbs a.i./A (Klingaman and Peeper, 1988). In the buckwheat family, black bindweed (Polygonum convolvulus;Polygonaceae), seedling mortality was 52-67%at a rate of0.008 1bsa.i./A (Ivany, 1987; Klingaman and Peeper, 1988) and two related species, garden sorrel (Rumex acetosella) and curly dock (Rumex crispus) seedlingshad mortality of 30% and 93% atrites of0.008 and 0.009 lbs a.i./A, respectively (Ivany, 1987; Khodayari et al., 1985). In the goosdfoot family (Chenopodiaceae),Chenopodium album had 77% mortality at 0.008 lbs a.i./A (~vany, 1987) and Mexican fire-weed (Kochia scoparia) seedlings had 50% reduction inbiomass at 0.00005 lbs a.i./A (Saarietal., 1990). Inthe legume family (Fabaceae), wintervetch seedlings averaged6$%mortality at a rate of 0.0 16 lbs a.i./A (Khodayariet al., 1985). Similar results arereported forthe other species in the ECOTOX database. 4.5.1 Fletcher 

### et 

### aL, 1995

I 

### The influence of chlorsulfuronon the reproduction of green pea (Pisum sativum) was examinedby exposing plants at three different stagesofdevelopmentto three different exposure levels. Themost susceptible stage of development was when plants possessed six expanded leaves and one visible flower bud. At that stage an application rate of 0.00016lbs ai/A reduced yield oftreated plants by 99% compared to controlplants without appreciably altering height or appearanceofmature plants.
1 

### When corresponding low applicationrates of atrazine, glyphosate, 

### and 2,4-D were administered at the same development stage there were no effects on either growth or reproduction. Thus chlorsulfuronhad an influence on plant reproduction that was not produced by other herbicides at low levels. The researchers concluded that small amounts of drifting sulfonylureas are potentially more damaging to the yield of non-target plants than that of other commonly used herbicides. However, the plants were saturated with a solution containing the low concentrations, which may not be representative of actual field conditions.
4.5.2 Coyner 

### et 

### al., 2000 The effect ofchlorsulfuron on thenon-target freshwater macrophyte,Potamogetonpectinatus (sago pondweed) was evaluated in environmental growth chambers. This ecologically important submerged plant is a food source for many species of wildlife such as ducks, geese and swans, as well as marsh and shorebirds (Hurly, 1994). P.pectinatus also provides habitat and nursery area for many fish and other aquatic life. It grows in regions where chlorsulfuron is used. In this study,plants exposed to 0.25 ppb chlorsulfuron showed a 76% reduction in length and a 50% reduction of stems and leaves comparedto controlplants. Increased mortality was observed at 1.0 ppb or greater. As a comparison, Correll and Wu (1982) found that P.pectinatus exposed to 650 ppb atrazinefor 4 

### week period did not have a mortality rate higher than the control plants.

### Together with results from the guideline aquatic plant studies (Table 

### 9), it appears that vascular plants may be more susceptible to chlorsulfuron than many non-vascular plants, such as the freshwater diatom 

### Navicula pelliculosa.
4.6 

### Field Studies, Greenhouse Studies, and Incident Reports Results fiom a number of field studies, greenhouse studies and laboratory studies suggest that chlorsulfuron applied at labeled rates may result in high risk to non-target plants grown in the vicinity of application sites. Severalofthe fields studiesbelow were conductedby researchers fiom theEPA laboratoryin Corvalis,OR and one ofthe non-target plant incidents (at Horse Heaven Hills) was investigated by a researcher from the same EPA laboratory. Several researchers have concluded that these studiesindicatethat small quantities of chlorsulfuron change plant reproductionwithoutalteringvegetative growth. Ifthe effectofchlorsulfurononcherry trees is characteristic of other plant species, spray driftmay severely reduce both the crop yields and fruitdevelopment onplants, the keystone componentofthe habitat and food web for wildlife. Plant reproductive processes may be more sensitive to chlorsulfuronthan growth effects. Low levels of chlorsulfuron appearto adversely influence plant reproduction, which is not characteristic of many common herbicides. 

### 4.6.1 Field Studies Fletcher et al., 1993 Researchers at the Oregon State University Lewis-Brown Horticulture Farm near Corvallis, Oregon investigated the influence of chlorsulfuron on cherry trees during the fall of 1991 and the spring of 1992, by comparing the weight of fruit collected from treated and control branches. Single applications of chlorsulfuronwere administered until wetness with a dual nozzle spray wand at five concentrations representing0,111OOOth,1/500th, 111OOfh, and 111Oth oftherecommendedtankmixture rate of chlor&lfuron for use on small grain crops in Washington, Oregon, and California. Three multiple applicationsexperiments were also conducted at 1 -week intervals. Results indicate that exposure of the developing buds to low levels of chlorsulfuron in September caused the next spring's yield to be reduced to 15% of the controls. Spring treatment resulted in yields of treated branches of 40% that of controls. Study authors concluded that the low dose herbicides are approximately 100times more toxic than herbicides used prior to 1982. Significant adverse effects on yields (up to 85% yield loss) were measured following treatment at, during, or shortly after bloom. These effects on the full grown,woody perennial cherrytree occurred fromthe use of 1/500th the maximum label rate for chlorsulfuron herbicide. Bhatti et al., 1995Field experiments were conducted at the Irrigated Agricultural Research and Extension Center, Prosser, WA in 1992 and 1993to studythe effects oflow concentrations ofchlorsulfuronby treating branches of three cherry (Prunus avium) cultivars at different growth stages. In single exposure experiments, the yield and quality offruit decreased significantly with the increase of chlorsulfuron concentrations. The concentrations correspond to 1/900th,1/300~, 111

### OOth and 111

### Oth the field application rates recommended for wheat. In multiple exposure experiments, fruityield, fruit size, and color was significantly reduced with increasing chlorsulfuron concentrations and numbers of exposures. The data suggest that multiple exposures of a susceptible cherry cultivar to low levels of chlorsulfuron at fullbloom andpost bloom stages can reduce yield and delay maturity of cherries while increasing firmness.
The researchers concluded that these results concur with the observations by Fletcher 

### et al. (1993), in that the toxicity of chlorsulfuronto cherrieswas correlated with concentration and reproductive growth stage at the time of exposure. However, if visible symptoms were not present, there were no yield reductions. The researchers concluded that reproduction in cherry trees appear to be adversely affectedby exposureto chlorsulfuron at concentrations substantially lowerthan application rates. 4.6.2 Greenhouse Studies The influence of low application rates of chlorsulfuron on the growth and reproduction of four taxonomically diverse plant species (canola, smart weed, soybean, and sunflower) were examined (Fletcher 

### etal., 1996). Exposure ranged from 1 x 1 0-3 to 8 x 1 0-3 ofthe recommended field rates for cereal crops. Each species received a single application at one of the three different stages of reproduction development. The comparative effects of four different herbicides (atrazine, chlorsulfuron, glyphosate, and 2,4-D) were determined in the same manner. Chlorsulfuron reduced the yields of all plants tested,with the amount ofreduction depending onthe time and rate of application. For canola and soybean, applications of 8.0 x 1 0-l1 and 1.6x 1 0-lo lbs aiIA, respectively, reduced seed yields by 92 and 99% compared to controls without causing significant changesinvegetative growth. Theselowapplicationrates suggest that chlorsulfuronmay cause severe reductions in the yields of some non-target crops if they are subject to exposure at critical stages of development. In this study, canola and soybeanwere the most sensitive species to chlorsulfuron. Smart weed, a food source for waterfowl, was moderately sensitive and sunflower was sensitive only at the highest application rate and only one stage in development. 4.7 Non-target Plant Incident Reports There are five non-target plant incidents possibly linked to offsite drift of chlorsulfuron in the Agency's Ecolgical Incident Information System(EIIS) database. The most recent ofthese incidents (I0 13884-0 12) occurredinJune 1998inBenton County,WA, where an orchard bound onthree sides by 

### 'dryland' wheat reported four years of reduced Bing cherry production. The Washington State Department of Agriculture investigated, but the cause remains unknown and the investigation was not continued. Chlorsulfuron was one of the herbicides used on the wheat fields.

### Another incident occurred in 1997 (I0 13882-035),where potatoes were possibly affected by tank contaminationby chlorsulfuron near Walla Walla, WA. Also in 1997, leaf spots in cherry and apple orchardsinDouglas County,WA were reported (I0 13 883-003). Chlorsulfuron and 2,4-D were used on nearby wheat fields and the spots were thoughtby investigators to be due to chlorsulfuron drift. In 1994,a farmer in 

### KY reported damage to tobacco seedlings after 2,4-D and chlorsulfbron were used on a nearby road right-of-way (1001473-001). That the damage (chlorosis and growth cessation) was due to chlorsulfuron was determined to be "possible". The last incident in the database (1000230-001)is reported to be from Spring 1977and wasreported to the Agency in 1992. Peach trees in a Benton, WA orchardwere severely damaged and cherry and prune treeswere damagedto a lesser degree (peartreeswere unaffected). It was determinedthat the damage was "definitely due" to chlorsulfuron, which had been appliedto a nearby whesit field. The date of 1977 raised questions, as chlorsulfuron was not registered until 1982. The ihident was reported by George Abel, Pesticide and Toxic Substance Branch, US EPA, Region 101 1200 Sixth Avenue, Seattle,WA 98 101. An investigation into this anomaly suggeststhat the acch-atedate of this incident was likely 1987, according Cliff Weed, Compliance Program Managdr, Pesticide Management Division, Washington State Department of Agriculture (personal cohunication, March 09, 2005). 

## fi. Weed, an employee since 1985, recalls that numerous incidents of crop damage, most allegedly due to chlorsulfbron, were investigated in the spring of, 1987. He specifically recalls an incident involvingpeaches; however, as the Department routinkly discards records after seven years, no known records from that time exist. TheHorse Heaven Hills lawsuitsare not in the Agency's EIIS database,but the allegedincidents of

I 

### chlorsulfkon drift were investigated by Fletcher (1991). An 

### orchard suffered sevyral years of reduced yield in the late 1980s in an area proximal to wheat farms at Horse Heaven Hills, where herbicides w&e regularly used. While the reduced yields and plant damage were not hoted before the use of chlorsulfuronin the area, the investigation results were inconclusive.5.0 

### RISK CHARACTERIZATION
5.1 

### Risk Estimation
5.1.1 

### Risk Quotients for Terrestrial Animals
Acute and chronic risk quotients do not exceed EFED's Levels of Concern (LOC) for birds and mammals 

### (Table 10).With acute toxicity values (LC,,) greaterthan 5,000 pprn and relatively low EECs, based on 240 pprn per lb ai applied 

### (Appendix 

### 4) chlorsulfuron is not expected to pose an acuteriskto avian species. TheNOEC for avian reproduction (1 74mglkglday) ismore than 

### an order ofmagnitude abovethe highest EEC. Because oflow acute toxicity to laboratory rats, risk quotients do not exceed the LOCs for mammals. Therefore, chronic risks to birds are not expectedto exceed the Agency's LOCs. Chronic risk to mammals remains uncertain.
Table 10. Chlorsulfuron Risk Quotients for Terrestrial Animals EEC range Risk Quotients acute I Species Toxicity chronic
Birds Acute LC,, > 5,000 pprn Chronic NOEL = 174ppm 1.9 - 15pprn <0.01 / < 0.01

Acute LD,, = 5 5 g/kg Mammals 19-15ppm <O 0 1/ not available Chronic NOEC =not available Risk quotients are not calculated for terrestrial insects; however, based on an acute contact study, chlorsulfuron is classified as practically nontoxic to honeybees. Therefore, direct risk to insects is thought to be minimal.
5.1.2 

### Risk Quotients for Freshwater and Marinelestuarine Fish and Invertebrates
Acute and chronicrisk quotients do not exceedthe LOC for freshwater or marinelestuarine fish and invertebrates 

### (Table 11).With acute toxicity values (LC,,) greater than 50 pprn and EECs lessthan 0.010 ppm, chlorsulfuronis not expected to pose an acute risk to aquatic animal species. Chronic toxicity tests result inNOECs that are greaterthan or equal to 20 ppm. Therefore, chlorsulfuron is expected to present low acute or chronic risks to freshwater and marinelestuarine fish and invertebrates.
Table 11. Chlorsulfuron Risk Quotients for Terrestrial Animals Species Toxicity EEC range Risk Quotients acute I chronic Freshwater fish

Freshwater invertebrate Acute LC,, = *0 ppm Chronic NOEC = 32 ppm

Marine fish Acute LC,, = >370 ppm Chronic NOEC =20 ppm Acute LC,, =>950 ppm Chronic NOEC = NIA 3.0 - 9.6 ppb

3.0 - 9.6 ppb

3.0 - 9.6 ppbMarine invertebrate Acute LC,, = 89 ppm ChronicNOEC =NIA 3.0

### - 9.6 ppb <0.01 I NIA
5.1.3 Risk Quotients for Aquatic and Terrestrial Plants
5.1.3.1 Aquatic Plants Screening level risk quotientsfor non-target and endangeredlthreatenedaquatic plants are reported in Table 12. PRZMIEXAMS was used to estimate environmental concentrations (EECs). The assumptions used in this modeling are provided in Section 3.2.1. The Agency's Level ofConcern (RQ2 1

### .O) for non-target plants is exceededin allmodeled scenarios. At current maximum application rates used on wheat, non-target aquaticplant RQs range from 12 to 16 and from 18 to 23 for endangered aquatic plant species. For use on turf (at the same rate as rangeland), RQs range from 17 to 21 for non-target aquatic plants and from 26 to 3 1 for endangered aquaticplants.
Table 12. ChlorsulfuronRisk Quotients (RQs) for Non-target and Endangered1Threatened Aquatic Plants Using a EC,, of 0.35 pg/L and a NOEC of 0.24 pg/L forLemna gibba. (Single Application) Crop (state) Application rate Peak EEC (ppb) RQs for non-target RQs for endangered (Ibs ailacre) (PRZMJEXAMS) aquatic plants 

### ' aquatic plants

### "
Wheat (ND) 0.023 4.2 12 18 Wheat (TX) 0.023 5.5 16 23 Turf (PA) 0.0625 5.9 17 26 Turf (FL) 0.0625 7.5 21 31

5.1.3.2 Terrestrial Plants 

### The screening level terrestrial assessment consists ofthe following four scenarios: 1) Off-target drift and runoffof chlorsulfuron fiom a ten acre application site to an adjacent one acre semi-aquatic area (wetland) using seedlingemergencetoxicity data to calculate risk quotients (Table 13),based on a single application of chlorsulfwon. 2) Off-target drift and runoff of chlorsulfuron from a one acre application siteto an adjacent one acre terrestrial area using seedling emergencetoxicity data to calculate risk quotients (Table 14), based on a single application of chlorsulfuron. 3) Off-target drift and no runoff of chlorsulfwon fiom a one acre application site tb an adjacent one acre terrestrial area using vegetative vigor toxicity data to calculate risk quotients (Table 15), based on a single application of chlorsulfuron.

### 4) Use of contaminated irrigation water (groundwater or surface water inadvertently containing



### . chlorsulfuron) using the 

### vegetativevigortoxicity datato calculate risk quotients

### (Table 16),based on a single irrigation event. Screening level RQs for semi-aquaticareas(wetlands) resulting fiom off-targetdrift (concentrations estimated at the edge ofthe treated field) and runoff of chlorsulfuron fiom the application site (ten acres to one acre) we presented in 

### Table 13. The toxicity endpointused in the RQ calculations was seedling emergence. A ten-acre application area running off into a one-acre wetland was simulated to determine the estimated environmental concentrations from runoff into wetlands. RQs for ground application of chlorsulfuron to small grains (wheat, barley, and oats),pasture and rangeland range from 26 to 103for non-target plants and fiom 177 to 693 for endangeredlthreatened plants. RQsfor aerial applicationto small grains, pasture andrangeland range fiom 18to 7 1 for nontarget plants and fiom 122 to 476 for endangeredlthreatened plants. Since the 

### LOC) is exceeded, At the current maximum applicationrate of chlorsulfuron to small grains, rangeland and pasture greatly, level of concerns (RQ2 1.O) are exceeded for non-target and endangeredlthreptenedplants foundin semi-aquatic areas (wetlands). The highest calculatedRQs are from industrial applications. Direct exposure scenarios were not calculated, but RQs for plants and endangeredplants would be higher than those estimated fiom exposure via spray drift andlor runoff.
Table 13. Chlorsulfuron Risk Quotients (RQs)for Non-Target Semi-Aquatic Areas (Wetlands) Using an EC,, of 3.1 x lbs ai/acre for Non-Target Plants and a NOEC of 4.6 x lbs ai/acre for Endangered Plants with Ten Acres to One Acre Runoff. Appl. rate EEC for EEC for RQs for ground application RQs for aerial application Crop (Ibs ai/A) ground Single aerial appl.' appl.' (1bs ai/~) Non-target Endangered Non-target Endangered application (lbs ai/A) plants plants 

### ' plants plants Barley (post emergent) Oats (pre-emergent) 0.023 0 01173 0.0081 38 255 26 175 Oats (post-emergent) 0 016 0 00816 0.0056 26 177 18 122Wheat (preemergent Wheat (postemergent Pastured rangeland 0.0625 0.03188 0.0219 103 693 7 1 476 Fallow 0 016 0.00816 0 0056 26 177 18 122 Unimproved turf 0.012 0 00612 NIA 20 133 NIA N/A Unimproved industrial turf 0.023 0 01173 NIA 3 8 255 NIA NIA Non crop sites 0.021 0 01169 N/A 38 255 NIA NIANon-crop (indushlal 0 14 0.0714 NIA 23 0 1552 NIA N/A sltes) Non-crop land 0 031 0.01625 NIA 52 353 NIA N/A restoration 1/ EEC for ground applications = drift +runoff = total load 6111 = application rate (lbs ailacre)x 0 01 (drift) Runoff = appl~catlon rate (Ibs adacre) x 0 05 (based on solubility) 21 EEC for aerial applications = dr~ft +runoff = total load Drift = application rate (Ibs ailacre)x 0.05 (drift) Runoff = applicat~on rate (lbs ailacre)x 0 05 (based on solubility)x 0 6 efficiency factor 31 RQ = EEC for ground apphcation / EC,, 41 RQ = EEC for ground application 1NOEC 51 RQ =EEC for aerial applicat~on / EC,, 61 RQ =EEC for aerial application 1NOEC Screening level risk quotients for non-target and endangered terrestrial plants in areas adjacent to

- the application area are presented in 

### Table 14. This scenario uses toxicity endpointsfrom the seedling emergence study and assumes one acre to one acre runoff. RQs for ground application of chlorsulfuronto small grains, pasture and rangeland range from 3 to 12 for non-target plants and fiom 21 to 82 for endangeredlthreatened plants. RQs for aerial applicationto small grains, pasture and rangeland range fiom 

### 4 to 16for non-targetplants and from I I 28 to 109for endangeredlthreatenedplants. RQs for non-target plants range fiom 3 to 16 for small grains, rangeland and pasture. For endangeredplantsthey range from 21 to 109. The RQs are higher for industrial rates. The LOC of 1.0 for non-target and endangered terrestrial plants are exceeded for all uses. Therefore, the application of chlorsulfuron to small grains, rangeland, pasture and non-crop sites greatly exceeds LOC's for non-target and endangeredhreatened terrestrial plants. Direct exposure scenarios were not calculated,but RQs for plants and endangered plants would be higher than those estimated from exposure via spray drift and runoff. Screening level RQs for non-target and endangered terrestrial plants resulting from spray drift alone (no runoff) are reported in 

### Table 

### 15. RQs resulting from aerial application of chlorsulfuronwere greater than for ground application. RQs for non-target plants range from 16 to 

### 63 for ground applicationsto small grains, rangeland and pasture. For endangered plants they range from 30 to 116. For aerial applications, RQs for non-target plants range from 80 to 313 for small grains, rangeland and pasture. For endangered plants they range from 

### 148to 580. The toxicity endpoint used in these RQ calculations was from the vegetative vigor study. Therefore, the application of chlorsulfuron to small grains, rangeland and pasture exceeds LOC's for non-target and endangeredhhreatened terrestrial plants by several orders of magnitude. For this scenario (which assumesno runoff), the risk quotientsfor aerial applications are higherthan for ground applications.Table 14. Chlorsulfuron Risk Quotients (RQs) for Non-Target and Endangered Terrestrial Plants Using (Seedling Emergence)an EC,, of3.1 x 10-41bs ailacre for Non-Target Plants and a NOEC of 4.6 x 10 -5 lbs ailacre for Endangered Plants with One Acre to One Acre Runoff. Appl. rate RQs for ground RQs for aerial (Ibs ai/A) EEC for EEC for application application Crop ground aerial appl.' Single appl.' (Ibs ai/A) Non-target Endangere (Ibs ai/A) d Non-target Endangered application plants nlants plants plants Barley 0.016 0 00096 0.00128 3 2 1 4 28 (post emergent) Oats (pre- 0.023 0 00138 0.00184 4 30 6 40 emergent) Oats (post- 0.016 0 00096 0.00128 3 2 1 4 28 emergent) Wheat (pre- 0.023 0.00138 0.00184 4 30 6 40 emergent Wheat (post- 0.016 0.00096 0.00128 3 2 1 4 28 emergent Pastures and 0.0625 0.00375 0.005 12 82 16 109 rangeland Fallow 0.016 0.00096 0.00128 3 2 1 4 28 Unimproved turf 0.012 0.00072 N/A 2 16 N/A N/A Unimproved 0.023 0 00138 N/A 4 30 N/A N/A industrial turf 

### - Non crop sites 0.021 0.00126 N/A 4 27 N/A N/A
Non-crop 0 14 0 0084 N/A 27 183 N/A N/A (industnal sites) Non-crop land 0 031 0.00186 N/A 6 40 N/A N/A restoration
11 EEC for ground applications = drift + runoff = total load Dr~ft = appllcation rate (lbs adacre) x 0 01 (drift) Runoff = application rate (lbs adacre) x 0 05 (based on solubil~ty) 21 EEC for aerial appllcatlons = drift + runoff = total load Drift = application rate (lbs ailacre) x 0 05 (drift) Runoff = appllcatlon rate (lbs ailacre)x 0 05 (based on solubility)x 0 6 efficiency factor 31 RQ = EEC for ground applicat~on / EC25 41 RQ = EEC for ground appllcation/ NOEC 51 RQ =EEC for aerial application/ EC25 61 RQ =EEC for aerlal application/ NOECTable 15. Chlorsulfuron Risk Quotients (RQs) for Non-Target and Endangered Terrestrial Plants Resulting From Drift Exposure Alone ( 2e. No Runoff) (using the vegetative vigor EC,, of 1.0 x for non-endangered plants and the NOEC of 5.4 x for endangered plants). RQs for ground RQs for aerial Appl. rate EEC for EEC for application application (lbs ai/A) ground aerialappl.' Crop appl.' Endangere Non-target Endangere Single (Ibs ai/A) (lbs aiIA) Non-target plants d plants d application plants plants Barley (post emergent) Oats (preemergent)Oats (postemergent)Wheat (preemergent Wheat (postemergent Pastures and rangeland Fallow 0.016 16xlo4 8.0~ 10." 16 30 80 148 Unimproved turf 0.012 1.2x 10 -4 NIA 12 22 NIA NIA Unimproved industrial turf NIA NIA Non crop sites 0.021 1.2~ lo4 NIA 12 22 NIA NIA Non-crop (industrial sites) Non-crop land restoration 0.03 1 3.1 lo-4 NIA 31 57 NIA NIA
11 EEC for ground applications = drlft = total load Drlft = appllcat~on rate (Ibs allacre) x 0.01 (dnft) 21 EEC for aerlal appllcat~ons = dr~ft = total load Drlft = application rate (lbs ailacre) x 0 05 (drlft) 31 RQ = EEC for ground applicat~on 1EC25 41 RQ = EEC for ground appllcatlonI NOEC 51 RQ =EEC for aerlal appllcatlon 1EC25 61 RQ =EEC for aerlal appl~catlon I NOEC Risk quotientswere also calculated to evaluate the potential risk to plants if exposed to irrigation water containing chlorsulfuron. Modeled estimates suggestthat irrigation water from groundwater and surface water sourcesmay contain high enough chlorsulfuron concentrationsto damage adjacent non-target plants and sensitive crops within irrigated fields.Risk quotients for non-target and endangered plants resulting from exposure to irrigation water containing 1.6 ppb of chlorsulfuron in groundwater are presented in 

### Table 16. These RQs are derived from SCIGROW 

### (Table 6) or 6.0 ppb of chlorsulfuron in surface water, generated using PRZWEXAMS. The 6.0 ppb estimate roughly covers North Dakota, Texas, and Pennsylvania scenarios, although Florida could be as high as 

### 9.5 ppb 

### (Table 

### 4).

r Toxicity endpoints from the vegetative vigor study were used in the RQ calculations because it was assumed that non-target plants are exposed to chlorsulfuron directly through spray drift from irrigation water. The RQs for semi-aquatic and terrestrial areas adjacent to irrigated fields were calculated assuming 

### 5% ofthe irrigation water driftsinto adjacent wetlands. It was assumedthat no run off of irrigation water occurs 

### (Appendix 7). The RQs for non-target plants range from 2.0 for irrigation using groundwaterto 7.0 when using surface water. For endangeredplants fpund in areas adjacent to irrigated fieldsRQsrange from 3.0 to 13. The RQs for non-target plants in semi-aquatic and terrestrial areas adjacent to agricultural fields irrigated with water containing chlorsulfuron exceed the acute risk to listed and non-listed plant speciesLOCs of 1.O. These calculations suggest that we cannot preclude the potential for impacts to non-target and endangered plants through the inadvertent use of irrigation water containing chlorsulfuron, given the extent of this analysis of exposure, effects, and coo-occurrence of listed resources and areas of use. Results o/f SCIGROW and PRZMIEXAMS modeling suggest that using surface water for irrigation may inckease the risk over groundwater irrigation. Additionally, this screening-level assessment indicates that irrigation water may inadvertently contain high enough levels of chlorsulfuron to adversely impact sensitiveagricultural crops such as soybeans, sugarbeets, onions, etc. 

### (Appendix 6) if they are grown in fields that are irrigated with water containing chlorsulfuron. Risk quotientsfor sensitive crops within irrigated fieldsrange from 36 for irrigation using groundwater to 136for using surfacewater to irrigate fields. In regions where chlorsulfuron has been used historically, agricultural crops grown in fields irrigated with groundwateror swfacewater containing chlorsulfuron could possiblybe adversely affected. Forthis assessment it was assumed that there are no endangeredplants that occur within irrigated fields.
Table 16. Risk Quotients for Non-target Plants,Endangered Plants, and Sensitive Agricultural Crops Resulting From Exposure to Irrigation Water Containing 1.6 ppb Chlorsulfuronin Groundwater or 6.0 ppb in Surface Water (using the vegetative vigor EC,, of 1.0x for non-endangered plants and the NOEC of 5.4 x for endangered plants). Risk Quotients for groundwater (GW) andsurface water EEC: chlorsulfuron in irrigation (SW) irrigation Location groundwater and surface water (Ibs ai/A)' Non-Endangered plants2 Endangered plants (EEC/ECz& (EECJNOEC) Semi-aquatic and terrestrial Groundwater. 1 8x105 GW: 2 GW: 3 areas adjacentto irrigated Surface water: 6 8 x 10" SW. 7 SW. 13 fields Within the imgated Groundwater 3.6x 1 0-4 GW: 36 NIA5 field4 Surface water. 1 4 x 1 O5 SW: 136

" Estimated Environmental Concentrat~on assuming 1 inch ofirrigation water is applied to the target field 

### '' Non-target plants in areas adjacentto the irrigated field or sensitive agricultural crops within the irrigated field 2731 Assumes 5% drift of irrigationwater containing chlorsulfuronand no runoff of irrigationwater " Irrigationwater applied directlyto agricultural crops that may be sensitiveto chlorsulfuron 51 It is assumed that there are no endangered plants within agriculturalfields that are migated



### 5.2 Risk Discussion 5.2.1 Terrestrial and Aquatic Animals Toxicitytests and estimated environmental concentrations indicatethatrisktoterrestrial and aquatic animals resulting from directexposure chlorsulfuron are expectedto be low. However,thepotential exists for indirect impacts because animals ultimately depend on plants and plant communities for survival. The extent of said impactswill depend on the species involved andthe extentofthe effects on plant communities. Effects could range from disruption in food supply to reduction in nesting

, habitat.



### 5.2.2 Terrestrial and Aquatic Plants Estimated environmental concentrations (EECs) of chlorsulfuron resulting from labeled greatly exceed LOCs for sensitivenon-target and endangered plants. Based on the chemical concentration inhibiting 25% (50% for aquatic) of the test plants (EC,,/EC,,), chlorsulfuron is classified as very highly toxic to both' terrestrial and aquatic plants. While sensitivity varied between taxonomic groups, the most sensitiveplants (which were from guideline studies)had an EC,, as low as 1.0x lo-, lbs a.i./A and an NOEC value of 5.4 x lbs a.i. /A (vegetative vigor). Based on available data, the slope of the dose-response curves for chlorsulfuron varies considerably between species, suggesting a range of expected toxicity. Tabular summaries are provided in 

### Appendices 5 

### and 

### 6. A single aerial application of chlorsulfuron, assuming 5% of the application drifts into non-target areas, results in EECs as high as 0.003 lbs ailacre. Therefore, RQs for agricultural use sites range up to 3 13for non-targetplants andup to 693 for endangered plants. Furthermore, severalofthe nonagricultural uses have multiple applications and several chlorsulfwonproduct labels do not specify " important information on maximum application rates, numbers of applications and methods of application. The risk quotients in 

### Tables 13 

### through 16 were calculated assuming only one application of chlorsulfuron. If multiple applications are assumed, the risk quotients would be higher. While guideline laboratory plant toxicity tests required by the EPA do not include reproduction endpoints, results of field studies and green house studies conducted by researchers from the EPA laboratoryin Corvalis, OR (Fletcher

### et al., 1993and Fletcher 

### etal., 1996)suggestthat chlorsulfuron adversely affects plant reproduction at very low concentrations. Together with published studies, results also indicate a range of sensitivity that varies by species, as well as timing of application in relation to plant development stage. It is possible that avoiding chlorsulfuron applications at times when species of concern are flowering may reduce the risk of reproductive failure.Resultsfrom the ECOTOX database reveal a range oftoxicitybetweentaxonomicgroupings and in ecologically important families, such as the N-fixing Fabaceae and even among the grasses (Poaceae). There is a great deal ofuncertainty regarding the effect chlorsulfuron may have onplant community composition, particularly with rangelanduses. As evidencedby the label warnings, even apparently insensitive species may have reduced seed production unless careful application timing is observed. Selective pressure as may be a result of chlorsulfuron usage may result in unforseen effects on populations of desirable plant species as well as community composition. Additionally, the Dupont Vegetation Management Report of 2002 indicates that Telar 

### DF' (chlorsulfuron) herbicide inhibits seed formation and the production of viable seed. This aspect is characteristic of Telar DF7herbicide when applied at the rosette-bloom stages of growth. The viability of weed seed is greatly reduced or eliminated following the application of Telar 

### DF~ herbicides when applied prior to maturation ofthe seed embryo. The report also indicates that while many grasses are tolerant to Telar 

### DF' at early or late stages of growth, it should not be used on grasses grown for seed. Field research and practical use experience have demdnstrated that numerous desirable tree and shrub species (established plantings) have a high degree of tolerance to Telar 

### DF' from incidental soil residual contact when used according to the label. However, tolerance to this product is expected to 

### vary by species and site considerations. Another source of uncertainty is that current product labels recommend that chlorsulfuronbe tank mixed with other common herbicides to ensure that resistant weeds are killed, which may result in synergistic effects to non-target plants. Toxicity data on combinations of herbicides are lacking. However, current label precautions appear to suggest that synergistic effects may occur if chlorsulfuronis appliedto fields to which certain otherinsecticideshave been applied. For example, the label for ~inesse' statesthat "Finesse should not be used within 60 days of crop emergence if an organophosphate insecticide (such as "Di

### ston on^") wasused as an in-furrow treatment,orcrop injury mayresult". Presumably, neither ofthesetwopesticidesif used alone will cause crop injuryto wheat or barley. However, the label for ~inesse' indicates that they apparently do cause crop injury when used together. The label restricts the use of Finesse7 plus ~alathion' and the use ofFinesse' plus ~orsban in the Northwest, as crop injury may result. This suggests that we cannot, preclude the possibility that synergistic effects may occur to plants when chlorsulfuron is appliedto fieldsalong with organophosphate insecticides. The Finesse label also indicates that "tank-mix applications of Finesse plus Assert may cause temporary crop discoloration/stunting or injury when heavy rainfall occurs shortly after application". The extent to which indirect effects of chlorsulfuron occur in relation to endangered terrestrial and aquatic animals is uncertain. Several studieshave documented adverse effects of chlorsulfuron to cherry trees and other non-target plant species. If these impacts are characteristic of responses in natural plant communities, we cannot preclude the possibility that drifting chlorsulfuron may severely reduce growth and reproductive development of non-target plants, a keystone component of the habitat and food web for endangered wildlife. 5.2.2.1 Terrestrial Plants (Seedling Emergence)To calculate the RQs for terrestrial plants the EC25for non-targetplants (3.1 x 1 

### O4 lbs ai/A) and the NOEC for endangered species (4.6 x 1bs aiIA) were used. For a single ground application of chlorsulfuron the EECs ranged from 0.0014 lbs ai/A for small grains (wheat, barley and oats) to 0.0038 lbs ai/Afor.pasturesand rangeland. These EECs are calculated assuming 1.0%off-site drift and 5.0%'runoff(one acre to one acre). The RQs for non-target plants range from 3 to 4 for small grains up to 12for pasture and rangeland. For endangered plants RQs range from 2 1 to 30 for small grains up to 82 for pasture and rangeland. Therefore, application of chlorsulfuron to small grains, pastures, and rangeland greatly exceed risk LOCs for non-target and endangered plants inhabiting areas near application sites. 

### TheEECsfor asingleaerial application(Table 

### 14)are approximately25%higher

### thanforauomd application. TocalculateEECsfor

### anaerialapplicationofchlorsulfuron, 

### 5.O% 

### drift

### and5.O% 

### runoff (one acreto 

### one acre) are assumed. The RQs for non-target plants range from 4 to 6 for small grains up to 16 forpasture and rangeland. For endangeredplantsRQsrange from 28 to 40 for small grains up to 109for pasture and rangeland. Therefore, aerial application of chlorsulfuron to small grains, pastures and rangeland greatly exceeds risk LOCs for non-target and endangered plants inhabiting areas near application sites. 

### 5.2.2.2 

### Terrestrial Plants (Vegetativevigor) The vegetative vigor EC25for non-target plants (1.0 x 1 0-5 lbs ai/A) and the NOEC for endangered species (5.4 x lbs ai1A) were used to calculate the RQs for terrestrial plants exesed to drift 

### (Table 15). For a single ground application of chlorsulfuron the EECs ranged from 1.6x 10 lbs ai/A for small grains (wheat, barley and oats) to 6.3 x 10 -4 lbs ai/A for pastures and rangeland. These EECs are calculated assuming 1.0% off-site drift and no runoff. The risk quotientsfor nontarget plants range from 16to 23 for small grainsup to 63 forpasture and rangeland. For endangered plants RQs range from 30 to 43 for a small grains up to 116 for pasture and rangeland. Therefore, ground application of chlorsulfwon to small grains, pastures and rangeland greatly e+ceeds LOCs for non-target and endangered plants inhabiting areas near application sites.
The RQs for a single aerial application are about five timeshigherthan for a ground application. To calculatethe EEC for an aerial application, 5.0%drift and no runoffwas assumed. TheRQs fornontarget plants range from 80 to 115 for small grains up to 3 13 for pasture and rangeland. For endangeredplantsRQsrange from 148to 213 for a small grainsup to 580 forpasture and rangeland. Therefore, aerial applicationofchlorsulfuronto small grains, pastures andrangeland greatlyexceeds LOCJsfor non-target and endangered plants inhabiting areas near application sites.
Field studies conducted by researchers fkom the EPA laboratory in Corvalis, Oregon suggest that chlorsulfuron adversely effects plant reproduction at concentrations that may be kound in the environment (Fletcher 

### et al., 1993;Bhatti et al., 1995). However, laboratory plant toxicity' tests requiredby the EPA do not include reproduction endpoints and available data evaluatingthis effect are limited.

### Greenhouse studies provide further evidence of potential adverse effects to non-target plants. Fletcher et 

### al. (1996) found that chlorsulfuron applications of 9.2 x and 

### 1.8 x kgha, respectively, reduced seed yields of canola and soybeanby 92 and 99%, respectively, as compared to controls, without causing significantchanges invegetative growth. Whilethedelivery mechanism of these low application rates in these studies (saturation by solution)may not .berepresentative of spray drift, the concentrations are within the range ofreported herbicide drift levels and suggestthat chlorsulfuron may cause severereductions in the yields of some non-target crops if they are subject to exposure at critical stages of development. Application of other herbicides at comparable rates and stages ofplant development had no influence on either canola or soybean. 5.2.2.3 

### Plants Exposed to Irrigation Water Containing Chlorsulfuron Results of ground and surface water modeling indicate that in regions where chlorsulfuron is historically used, irrigation water from groundwater or surface water sources may contain levels of chlorsulfuron high enough to potentially effect non-target plants, endangeredlthreatened plant species, and sensitiveagricultural crops. Refinement ofthis analysis, specificallyexposure,effects, co-occurrence of listed resources, and areas of use would be needed to determine the potential for effects. Risk quotientswere calculated for semi-aquatic areas adjacent to irrigated fields,terrestrial areas adjacentto irrigated fields,and for sensitive crops within agricultural fields. This assessment does not consider chlorsulfuron TGAI, which could be expected to be the form exposed in these applications;however, initialterrestrial plant tests submittedby the registrant were conducted using TGAI, and results suggest greater sensitivity ofplants to the active ingredient. Irrigation with surface water containing chlorsulfuronexceeds risk LOCs for non-target plants in adjacent wetlands 

### (Table 16). RQs for endangered plant species in semi-aquatic areas adjacent to irrigated fields range from 3.0 for ground water irrigation to 13 for surface water irrigation. Therefore, irrigation with ground and surface water containing chlorsulfuron exceeds the LOC for risk to endangeredplants in adjacent wetlands. Risk quotients were also calculated for sensitive crops within irrigated fields. The RQs for crops range fkom 36 for irrigation using groundwater to 136 for using surface water to irrigate fields. Therefore, in regions where chlorsulfuron has been used historically, we cannot prelude the possibility that groundwater and surface water irrigation may result in damage to agricultural crops that are sensitive to chlorsulfuron. 

### 5.2.2.4 Plants Exposed to Chlorsulfuron DriftNon-target plants in areas where chlorsulfuronis applied may be exposed to shortrange drift (1 m to 1 

### km) andlor longer range drift (greater than 1 

### Ism). Drift may result fiom fine droplets which blow off-target before settling (spray drift) or, potentially, from treated soil blowink off-target (secondary drift). Although plants growing in proximity to application sites are expected to be at


### . greatestrisk of experiencing relatively high exposuresto chlorsulfuron,longer range drifthas been alleged to occur and cause visible effects to terrestrial plants (Felsot et al., 1996, Barolo, 1993). Symptomsof chlorsulfuron exposure to non-targetplants in areas away from applicatpn siteswere documented during the same time period as spray applications, suggesting that drift in these instances was mostly due to the movement of spray droplets. However, chlorsulfuron labels (e.g. Finesse) include the following precaution: "To reduce the potential for movement of treated soil due to wind erosion, do not apply to powdery, dry, or light sandy soil until they have been stabilized by rainfall, trashy mulch, reduced tillage or other cultural practices. Injury to adjacent crops may result when treated soil is blown onto land used to produce crops other than cereal grains". Chlorsulfuron ispersistent on soil at most pH's and the majority of it is applied to winter wheat (pre-or post-plant), which is commonly grown in dry regions. Therefore, the potential for treated soil to be blown off-target and result in exposure $0non-target plants should not be discounted.
While for some pesticides, application of fine sprays is important for control of target pests, chlorsulfuron's solubility, persistence, relatively low soilbinding, and mobility within plants (Weed Science Society, 1989) suggests that covering weeds evenly with fine droplets is not necessary to control them. Because chlorsulfuroncan move with soil water and be taken up by plant roots or absorbed through plant foliageandbe transported systemically throughoutthe weed,re)ativelylarge droplets ofchlorsulfuron contacting weeds or surrounding soil are expected to be effective inkilling weeds. Coarse sprays minimize driftand are not expected to reduce efficacy. Chlorsulhron product labels (e.g. ~inesse?) provide the following statement: "The most effective way to reduce drift potential is to apply large droplets (>I50 

### - 200 microns). The best drift management strategy is to apply the largest droplets that provide sufficient coverage and control." The langu

# a ge, which is standard on most DuPont pesticide product labels,provides suggestionsofparticular droplets sizes that reduce drift but do no requirethe applicator to use a specific droplet size spect&. Although a range of droplet diameters is mentioned, chlorsulfuron labels do not describe a droplet size distribution (such as theAmerican SocietyofAgricultural Engineers standard definitiohsfordroplet size) which is more appropriate for describing spray quality in regard to spray dri4. When the product is applied according to the label directions, many fine, driftabledroplets maybe produced that do not result in improvedweed controlandresultin off target movement and potentially innontarget plant damage. The distance that fine spraydropletsmay travel is largely dependentontheir size,release height, and meteorological conditions like wind speed. Larger dropletstend to deposit in the application area or nearby while smaller droplets may be blown farther downwind. Droplet settling velocity, the speed at which droplets settlein air without turbulence, can be useful for conveyingthe importance of droplet size on off-target movement. While a droplet with a diameter of 1000 pm (1 rnm) takes 1.3 secondsto fall 10feet and would travel 13.7-feet downwind, in a 10mphwind, a 100pm droplettakes 

### 14 seconds to reach the ground and will travel 185 feet, and a 10 ym droplet will take 18 minutes to reach the ground and travel 2.7-miles downwind. These calculations are simplified in that they don't take into account vertical mixing in the atmosphere, the range of droplet sizes produced by a nozzle, or, for aerial applications, the wake of aerial application equipment. It is possible to use spray drift models better account for these aspects of off-target drift. In order to better assess the potential risk to non-target plants from exposure to chlorsulfwon through spray drift, a refined spray-drift assessment was performed.
5.3 

### Refined Assessment of 

### Spray Drift on Non-target Terrestrial Plants The following assessment is focused primarily on chlorsulfuron use on crops and is intended to accurately reflect the most importantapplication conditionsactually used in applying chlorsulfuron to assess spray drift risks to non-target plants. Application parameters used by aerial applicators in Washington and Oregon were used to estimate a range of spray drift levels in this assessment. Reports of set ups for ground boom applications were not available and thus ground boom configurations were assumed to include the range of values available in the AgDRIFT model. Laboratory toxicity data used in this analysis were limited to effects occurring in a relatively short amount of time after a single exposure. A number ofpublished reports suggest that chlorsulfuron, and other herbicides with the same mode of action, may result in delayed effects on crop yield and plant reproduction at levels lower than those noted to cause short-term visible effects (for a review see Ferenc 2001). If reproductive effects occur at similar or lower levels than laboratory phytotoxicity dataused in this analysis, delayed effects may occur at distances greater than 1000feet from target applications. This assessment focuses on the effects of spray drift on non-target terrestrial plants. Exposure from chlorsulfwonrunoff can alsocause phytotoxicity to non-target plants. Chlorsulfuron'smobility and persistence in soil suggests that runoff may be an important route of exposure to non-target plants down slope of application areas. Plants in up-slope areas are not affected by runoff but are potentially damaged by spray drift. 

### Use Pattern Evaluated This refined assessment focused on chlorsulfuron use on grain crops, such as wheat. According to the USGS and USDA,this use accountsfor more than 98% of agricultural chlorsulfuron usage. The maximum applicationrate for wheat on the Glean product label is 0.023 lbs ailacre. Product label rates for wheat are 0.0078 to 0.016 lbs ai /acre with application per crop season (Finesse product label). Up to 0.0625 lbs ailacre may be used on pasturelrangeland and higher application rates are allowed for industrial areas. Chlorsulfwon is applied as a liquid spray and, for most uses, may be applied by ground or air. Directions for ground applications to wheat (Glean label) suggest that spray volume should be at least 3 gallonslacre for flat fan nozzles or 20 gallonslacre for Raindrop or floodjet nozzles. The lower volume is presumably allowed forthe flat fan nozzle because this commonly used nozzle canproduce a fineenough sprayto coverthe field with the lowvolume of 3 gallonslacre. With a volume of 3 gallonslacre, a relatively coarse spray would result intoo few dropsper unit area to adequately distribute the herbicide and control weeds in that area. Raindrop and flood jet nozzles are two models of nozzle that can be used to produce coarser sprays. With coarser sprays,higher volumes are generally necessary to result in adequate coverage oftreated fields and weeds for control. (For information on the design of flat fan and flood jet nozzles and their relative drift levels see 

### http://www.hardi-international.com/Agronomy/Education~Material/pdf/04a.pdf or 

### http://lancaster.unl.edu/ag/factsheets/289.htm).
DuPont conducted a small survey of aerial applicators as an indication oftypical aerial application parameters (Appendix 8). The DuPont survey included 15 aircraft set ups for chlorsulfiron applicationsin Washingtonand Oregon. Reported in the survey is the application voltme (gallons per acre), boom length (relative to wingspan), nozzle type, nozzle angle, aircraft speed, spray pressure, and variables that were assumed in order to calculate spray droplet size. Thedroplets size spectra estimated fi-om the equipment variables ranged from ASAE medium to 

### ASAE coarse.


### Toxicity Toxicity for this evaluation are derived fi-omthe guideline studies submittedby the registrantto the Agency (MRIDs 463268-01; 463618-01). Toxicity tables for the successive plant life stages (seedling emergence and vegetative vigor) are in 

### Appendix 4 and 

### 5. The most sensitive species tested were pea 

### (vegetative vigor, EC,, 1.0

### x 10" lbs 

### ailacre) and onion (vegetative vigor, EC,, 

### 5.4 xlO-' lbs 

### ailacre). The most sensitive effects measured in these tests were reductions in shoot dry weight. The phytotoxicity data was limited in that the confidence in the estimated

### EC,~ was low for most species. J Non-target plants exposed to herbicides may be killed outright or weakened, reducing their fitness. Non-lethal effects could cause plants to become more susceptible to plant pathogens, become less effective in competing with syrnpatric species, or reduce reproductive success. In instances where herbicide exposureeffects fertilization or seed production, reproduction of plants in the wild would be expectedto be reduced and population level changes could occur. Endangered plant species, not addressed in this evaluation, need to be protected as individuals, making mitigation efforts much more complex. The representativenessofplantsused inphytotoxicity testing ofnon-target naturally occurringplants is uncertain. The range of plants used in testing is limited to annuals despite the fact that woody plants and other perennials are commonly found in agricultural areas. Moreover, homogenous crop test plant seed lots purposely lack the variation that occurs in natural populations, so the test plants are likely to have less variation in response than would be expected from wild populations. However, it is suggestedin the literature

### (e.g.Clarke et al. 2004) that, at least for herbaceous plants, crop species may be adequate indicators of expected toxicity.In some instances, specifictest speciesmay be indicative of an effect to another naturally occurring non-target species. For instance wild onions may show similar sensitivity to commercially grown onions to aparticularherbicide. Native plants sharing speciesor genus family affinity with thetested crop plant may show similar levels of sensitivity to a pesticide (Fletcher et al., 1990), but it is uncertain how much familial affinity is predictive of response. However, given the intensive breeding and selection that is used to develop commercial strains of a species, it is possible that natural and commercial plants of the same species may show very different responses. 

### Phytotoxicity Tests and Spray 

### Drift Spray drift exposure to plants away fiom field edges is expected to result in relatively few concentrated droplets depositing on and around plants. In contrast, laboratory vegetative vigor and seedling emergence phytotoxicity tests, use relatively high volumes of spray to better cover the test plant or the soil surface. In instances where an herbicide's movement in plants or soil is limited, the test conditions ofthe phytotoxicity studiesmay result in higher measuredtoxicity than would result from spray drift away fiom the field's edge. In the instance of herbicides that are mobile within plants and soil, such as chlorsulfbron which is mobile in soil and can be transported throughout exposed plants, the volume of spray used for the exposure may not alter the magnitude ofthe toxic effect. 

### Exposure Current Label Directions Relevant to Sprav Drift Chlorsulfwon product labels have very few restrictions on how and under what conditions the product may be applied. For instance there are no droplet size, wind speed, or boom height restrictions. The absence ofbounds makes it more difficult to determine what conditions shouldbe used for risk assessment. The absence ofbasic mandatory label language also allows applicatorsto make unnecessarily high drift applications. Applicator common sense would prevent worst case applicationsbut may notresult in optimal applications. For instance, it is unlikely that an applicator would make a ground boom application with a high boom and a fine spray because drifting spray would be visible and it would be apparent that the efficiencyof the application was low. However, without proper guidance an applicator may use a low boom but a finer spray than necessary to achieve control. Under this scenario driftingspray wouldbe less visible but stillunnecessarily high. Specifying basic spray drift control measures provides applicators with the necessary information to perform an effective and low-drift applicationand risk assessorswith the necessary information to model drift. AgDRIFT Background AgDRIFT is a computer model that canbe used to estimate downwinddeposition of spray driftfrom aerial, ground boom, and orchard and vineyard airblastapplications. The model contains three tiers of increasing complexity. In Tier 1, the user can assess downwind deposition from a single application from all three application methods under default conditions. The current version ofAgDRIFT only allows Tier 1level analyses for ground and airblast application methods. In higher tiers more options are available for aerial applications. The aerialportion ofthe model is based on a mechanistic US Forest Service model (AGDISP. Bilanin et a1 1989). The ground boom and orchard airblastportions are empirical models based on data collectedby the Spray Drift Task Force (SDTF). The SDTFfield datawere used to validatethe aerial portion of AgDRIFT (Birdet a1 1996). AgDRIFT was developed under a cooperative research and development agreement between EPA, USDA, and the SDTF. 

### AerialAgDRIFT The most important factors affectingdriftfrom aerial applications are spray quality (droplet size), release height, and wind speed. The aerial part of the model predicts mean values based on the inputsprovided. The Tier 1 aerial results are generated using the specified droplet size spectra, 10foot release height, and a 10mph wind speed. When wind speed and/orrelease height is lower than the modeled values the spray drift levels would be expected to be lower. Conversely, in instances where applications may be made in higher wind speeds or at a higher release height these inputs may not be adequately conservative and higher tier modeling may be necessary. 

### Groundboom sprayers inAgDRIFT: Themost important factors affecting drift from groundboom applications are spray quality, release height, and wind speed. The ground boom part of AgDRIFT isbased on field trial datafrombare ground applications. The results ofthe model reflect the quality and conditions of the data on which it is based. The data fiom the field trials were grouped into categoriesby spray quality (droplet size)andrelease height. Resultsfrom fieldtrials conducted with different wind speeds were averaged. The average wind speed over all the trials was approximately 

### 10mph. AgDRIFT outputsfor ground boom applications estimatethe 50th and 90th percentile ofdata collected from field trials. For this analysis the 50th percentile data was used. The field trial data were not corrected for incomplete analytical recoveries, suggestingthe true mean deposition values would be approximately 20% higher than the model's depositionresults. Phvtotoxicity and Downwind Distance Using the AgDRIFT model (v. 2.01) and registrant submitted phytotoxicity data it is possible to estimate distances downwind from application areas at which a particular toxic effect level would be experiencedby a particular tested plant species. To make Figures 1 through 6 below, EC,,values (for vegetative vigor shoot weight) of the tested species were used with the toxicity slope"' fiom each species to calculate EC,,, EC,,, EC,,, to EC,, effect levels2,,. These EC, values were entered iMo an Excel spreadsheet with Tier 1 AgDRIFT deposition distance results and the maximum chlorsulfuron application rate for pasturelrangeland (0.0625 lbs ai1A). Estimated downwind

Toxicity slopes are calculated from dose-response relationship of chlorsulfuron on of the test plant species. Specieswith high (steep) slopes show large increases in toxicity from small increases in exposure. Species with low (shallow) slopes show small increases in toxicity from relatively large increases in exposure. A log normal toxicity distribution is assumed. The following equation is used to calculatethe various EC, levels: [EC,, 1 10.' 67's'0pe] x 1 O-a's'ope =EC, where a= 1.28, 0.84, 0.54,0.25, 0, -0.25, -0.54, -0.84, and -1.28 forEC,,, EC,,, EC,,, EC,,, EC50, EC6,, EC70, EC8,, EC9,, respectively.

### deposition levels were calculated for chlorsulfuron use on pasturelrangeland and compared the depositionvalues tothe 

### EC, valuesto identifythe downwind distance atwhichthe 

### EC, valueswould be reached. Excel was used to arrange the distances into three dimensional bar charts showing the downwind distsuice at which a particular toxicity level for each species is expected to occur under the Tier 1AgDRIFT conditions with the specified application rate. The barcharts shown in Figures 2 through 7 

### are specific to the maximum application rate for pasturelrangeland (0.0625 lbs ailA). Appendix 8 contains phytotoxicity barcharts for a mid-range application rate fiom the Finesse product label for wheat (0.012 lbs ai1A).

Figure 2. Predicted phytotoxicity levels and associated downwind distances from an aerial application conducted with a coarse spray in a 10 mph wind with a 10 foot release height at an application rate of 0.0625 lbs chlorsulfuron per acre.Aerial: Coarse Spray

rbeetFigure 

### 3. Predicted phytotoxicity levels (vegetative vigor) and associated downwind distances fiom an 

### aerial application conductedwith a 

### medium spray in a 10mphwind with a 10footrelease height at 

### an application rate of 0.0625 lbs chlorsulfuron per acre.

No-Spray Zone (ft) Aerial: Medium SprayFigure

### 4. Predicted phytotoxicity levels (vegetative vigor) and associated downwind distancesfrom a groundboom applicationconducted with a medium/coarsesprayin an approximate 

### 10mph wind with a 2 foot release height at an applicationrate of 0.0625 lbs chlorsulfuron per acre.

Ground: Low Boom, Medium-Coarse Spray

, u 

### Percent Effect 80 9; ---Figure 5. Predicted phytotoxicity levels (vegetative vigor) and associated downwind distances from a 

### ground boom applicationconducted with a 

### medium/coarse sprayin an approximate 10mph wind with a 

### 4 foot release height at an application rate of 0.0625 lbs chlorsulfiuonper acre.

Ground: High Boom, Medium-Coarse Spray

No-Spray Zone (ft)



# 1 Effect

### Figure 6. Predicted phytotoxicitylevels (vegetative vigor) and associated downwind distancesfi-om a ground boom 

### application conducted with a medium 

### spray in 

### an approximate 10 mph wind with a 

### 2 foot release height 

### at an application rate of 0.0625 lbs chlorsulfinonper acre.

No-Spray Zone (ft) Ground: Low Boom, Medium Spray

3" Effect

### Figure 

### 7. Predicted phytotoxicity levels (vegetative vigor) and associated downwind distances from a ground boom applicationconducted with a medium spray in an approximate 

### 10mph wind with a 4 

### foot release height at an application rate of 0.0625 lbs chlorsulf'uronper acre.

No-Spray Zone (ft) Ground: Hlgh Boom, Medium Spray

arbeet

### Conclusions Based on the phytotoxicity studyresults for wheat and chlorsulfuron use sites such aspasturelrange land, certaingrass species appear to be tolerant to acute chlorsulfuron effects. Sometolerant species apparently are susceptibleto reproductive effects fiom single exposures based onproduct claims of inhibiting seed head formation described on some product labels. Because of lack of data, reproductive effects cannotbe evaluated at this time. Figures 2 through 

### 7 above show the phytotoxicity downwind of chlorsulfuron applications is expectedtovary based on a numberofparameterincluding applicationmethod (ground boom versus aerial), the droplet size spectrum, and the release height. Figures 2 through 7 show effects 

### (EC, effect levels) by distance, but do not show at what distance plants are likely to be killed outright. When plants are tested by pesticide companies for efficacy generally a 70% effect level is considered to be a threshold for lethal effects to a healthy weed (Pallett 2003). Thus the EC,, effect level can serve as estimate of when non-target plants are expected to have a high likelihood ofrapid death similar to the desired effect for weed species. Aerial Applications


### For aerial applications,medium and coarse sprays are apparently the most commonly used sprays by aerial applicators in Washington and Oregon (Appendix 8B). Medium spray is expected to produce higher drift levels than coarse sprays resulting in greater phytotoxicityat greater downwind distances. Using the EC,, as an estimate for an exposure that would lead to rapid death, Figure 3 shows that 

### 5 of the 10tested species downwind of an application with a medium spray would be expected to be killed soon after application in an area stretching from the edge of the treated field to a distanceexceeding 1000feet downwind fiom the treatment area. Using a coarse spray, Figure 

### 2 shows that 4 of the 10 tested specieswould be expected to be killed from the edge of the field to a distance exceeding 1000 feet downwind from the treatment area. Aerial applications with a medium spray are expected to affect at least 8 

### ofthe 10 speciestested at the 

### EC,, level or above for shoot weight greater than 1000 feet downwind of applications. 

### In other words, a 40% or more reduction in shoot weight would be expected for at least 8 

### of 10tested species for over 1000 feet downwind of applications under the assumed conditions. With a coarse spray, under the same conditions, at least 

### 8 of the 10 tested species are expectedto be affected at the 

### EC,, level 1000feet or more downwind (i.e. a 10% reduction in shoot weight in an areas stretching for more than 1000 feet downwind). Ground boomApplications


### In all instances the ground boom applicationsmodeled resulted in lower drift deposition levels and downwind phytotoxicity than modeled aerial applications. Ground boom deposition values were affected by both droplet size and release height. Spray drift and predicted off-target effects can be reduced by lowering the release height andlor increasing spray droplet size.

### Under the lowest ground boom driftconditions allowedby AgDRIFT 2.01 (2 footboom height) and medium/coarse spray, 3 

### of 10 tested species would be expected to have a 50% reduction in shoot weight 200 feet or greater downwind the treated area (Fig. 4). Under the same conditions, 5 of the 10 tested species would be affected at the EC,, level in the area stretchingfor the edge of the field to beyond 1000feet downwind. Under the highest ground boom drift conditions (4 foot boom and medium spray), shoot weight reductions of 50% 

### would be expected in the area 200 feet downwind of the treated field for 70f 10 

### tested plants (Fig. 7). Characterization of Risk from Drift Chlorsulfuronis a selectiveherbicide. Some species, such as certain grasses, are relatively tolerant to chlorsulfuron while other species are sensitiveto acute effects andreproductive effects. Ifcertain plants in a plant community consisting of many species are consistently selected against through inhibiting growth, reducing reproductive success, or being killed, the sensitive plant species are likely to be removed from the community. Plants under selectivepressure are not abl'e to compete as successfully with other plants for resources such as light and water. Thus with pressure on a particular group of species other species would be likely displacethe sensitive species and become more common. Changes in the species composition in the boundaries of herbicide-treated fields have been noted inthe literature(Kleijn and Snoeijing, 1997,Jobin et

### al., 1997). Giventhe efficacy ofchlorsulfuron andthe driftpotential associated with sprayapplicationmethods, it is expectedthat chlorsulfbron is applying selective pressure against certain species downwind of applibation areas. The magnitude of the selectivepressure is expected to depend on the level of drift as well as the sensitivity of exposed species. The results ofthis analysis suggest that placingrestrictionsondroplet sizefor aerial applicationsand droplet size and boom height for ground boom application may reduce risks associated with chlorsulfuron applications. Typical values for both wind speed and release height are likely to vary geographically. Aerial applicatorsbalance lowrelease heights with flightsafety. Aerial applicators will generally use higher release heights in hilly areas or fields with tall windbreaks at their boundaries. For ground boom applications, high release heights are used to avoid having the ends of the spray boom hitting the ground in uneven fields or when relatively high sprayer speed is desired. Ground boom release height can vary fiom less than 2 feet to more than 

### 6 feet above the ground or crop canopy. Average wind speed for chlorsulfuron use areas vary with lopation with higher wind speed occurring in plains states. Table 17 shows wind speeds ranges for some representative areas. I

### Table 17. Wind speeds during the windiest month of the year for cities in high agricultural chlorsulfuron use areas. Wind speed (mph) City, State Approximate location Month in state 75fh 50th 25fh 

### Percentile Percentile Percentile Yakima, WA south central April 10 6 

### 4.5

\ 

### Pendleton, OR northwestern April 10.5 6 4.5 

### North Platte, 

### NE central southwestern April 14 11 7 More wind speed data for the above locations are in Appendix 8C. 

### Uncertaintv and Potential Refinement of ~isk Estimates 

### A number of uncertainties exist in this assessment ofpotential effects of chlorsulfuron spray drift to plants. With additional information it may be possible to further refine this assessment. 

### 1)The representativeness of tested species for non-target plant species in chlorsulfuron use areas. In chlorsulfuron use areas woody and other perennial species are exposed to spray drift but their sensitivity to chlorsulfiuonis uncertain. Toxicity data on a wider range of plants could be used to reduce uncertaintyas to the potentialeffectsof chlorsulfuron onperennial andwoody speciesatfield edges and farther downwind. 

### 2) The duration of exposure. Laboratory data is based on single exposures to plants with observation continuingfor twoweeks after dosing. Non-targetplantsin chlorsulfuron use areasmay be exposed to multiple pulses of chlorsulfuron. Data on the effect of repeat exposures at environmentally relevant levels could be used to determine the potential impacts to plants that are exposed to drift from multiple applications. 3) 

### The toxic endpoint measured. Some chlorsulfuron product labels and research on non-target plants showchlo&ulfuronnegatively affects plant reproduction. Datadefining what exposure levels at various developmental stages result in impaired plant reproduction could be used for assessing potential impacts of spray drift 

### on plant reproduction. 4) The adequacy of laboratory spraying treatments in representing spray drift far from field boundaries. Plants in laboratory studies are exposed to herbicide in volumes of carrier that are adequate to cover the test plants. Plants exposed to spray drift away from field boundaries would contact the same amountsofherbicides tested in the laboratorybut inmuch lowervolumesofcarrier. Plants are exposed to spray driftaway far away from the field edge in discrete spotswhere droplets impact the plant foliage opposed to the diffuse coating used in lab studies. The effect of small concentrated exposures relative to diffuse exposure is uncertain. Data on the effect of exposure volume on phytotoxicity could be used to refine effect level estimates.

### 5.4 EndangeredIThreatened Species Available data indicate that chlorsulfuron does not exceed the LOCs for endangeredlthreatenedterrestrialor aquatic animals. However, the screening level risk assessment for endangered speciesindicatesthat chlorsulfwonexceedsthe acute levelofconcernforendangered and threatened terrestrial and vascular aquatic plants. Thus, the Agency considers this to be indicative of a potential for adverse effectsto those listed speciesthat rely either on a specific plant species (plant speciesobligate)ormultiple plant species(plantdependant)for someimportantaspect oftheir life cycle. Further analysis regarding the overlap of individual species with e?ch use site is required prior to determining the likelihood ofpotential impact to listed species. Chlorsulfuron was included in the small grains cluster consultation with the Fish and Wildlife Service(FWS)in 1983. 

### As chlorsulfuron's riskswere assigned a "no effect" determination with regard to aquatic andterrestrial animals, Reasonable and Prudent Alternatives and Reasonable and Prudent Measures were not provided for this pesticide. Risks to endangered were not consideredinthis Biological Opinion. TheFWS completedtherangeland cluster~iolo~ical Opinion in December 1984. 

### Although chlorsulfuron was included in this Opinion, it did not consider endangered plants nor the potential indirect effects of chlorsulfuron on listed animals.

a. Action Area


### For listed species assessment purposes, the action area is consideredto be the area affected directly or indirectlyby the Federal action andnot merelythe immediate area involved in the action. Atthe initial screening-level,the risk assessment considers broadly describedtaxonomicgroups and so conservatively assumes that listed species within those broad groups are co-located with the pesticide treatment area. This means that terrestrial plants and wildlife are assumed to be located on or adjacent to the treated site and aquatic organismsare assumedto be located in a surface water body adjacent to the treated site. The assessment also assumes that the listed species are located within an assumed area, whichhas therelatively highest potential exposure to the pesticide, and that exposures are likely to decrease with distance fiom the treatment area. Ifthe assumptions associatedwith the screening-level action arearesult inRQsthat arebelow the listed species LOCs, a "no effect" determination conclusionismadewithrespecttolisted species in that taxa, and no further refinement ofthe action area is necessary. Furthermore, RQs below the listed speciesLOCs for a giventaxonomicgroup indicate no concern for indirect effects upon listed species that depend upon the taxonomic group covered by the RQ as a resource. However, in situationswhere the screening assumptions lead to RQs in excess of the listed species LOCs for a giventaxonomicgroup, a 

### potential for a "may affect" conclusion exists and maybe associated with direct effects on listed species belonging to that taxonomic group or may extend to indirect effects upon listed species that depend upon thattaxonomic group as a resource. In such cases, additional information on the biology of listed species, the locations ofthese species, and the locat'ionsofuse sites couldbe considered along with available information on the fate and transport properties of the pesticide to determine the extentto which screening assumptions regarding an action area apply to

### a particular listed organism. Thesesubsequent refinement stepscould considerhow this information would impact the action area for a particular listed organism and may potentially include areas of exposure that are downwind and downstream of the pesticide use site. b. Taxonomic Groups Potentially at Risk The risk quotients (RQs) calculated based on the ratio of estimated environmental concentrations (EECs) to toxicity endpoints, in this case the NOEL from plant toxicity studies, indicate potential to affect endangeredplants should exposure to chlorsulfuronthrough spray drift or runoff.occur. Should estimated exposure levels occur in proximity to listed resources, the available screening level information suggests a potential concern for direct effects on listed plant species associated use of chlorsulfuron, particularly wheat and pasturelrangeland. This Level I screening assessment is based on the initial assumption that listed species within the taxonomic groups of concern are actually present in areasfor whichthe estimatedexposurelevelsused for RQ calculation can be expected to occur. A specific determination of "may affect" for any RQ in excess of listed species LOCs cannotbe made until a determination of the co-occurrence of the listed species with the action area has been determined.

c. Indirect Effects Analysis Because plant RQs are above non-endangered species LOCs, the Agency considers this to be indicative of a potential for effects to those listed species that rely either on a specific plant species (plantspeciesobligate)ormultipleplant species (plant dependant) for some importantaspect oftheir life cycle. The extentto which the use ofchlorsulfurononwheat and pasturelrangeland will indirectly affect listed animal species will require identification of listed species that co-occur in areas of chlorsulfuron use and an evaluation of critical habit as described below. Because of the national extent of the labeled uses of chlorsulfuron, we cannot preclude the possibility of a 'may effect' for all listed animals, given the current extent of analysis of exposure, effects, and cooccurrence of listed species and areas of use. d. Critical Habitat The screening-levelrisk assessment has identified potential concerns for indirect effects on listed species for those organisms dependant upon plants sensitive to chlorsulfuron. 

### In light ofthe potential for indirect effects, the next step for The Agency and the Service(s) is to identify which listed species and critical habitat arepotentially implicated. Analytically, the identification of such species and critical habitat can occur in either of two ways. First, the agencies could determine whether the action area overlaps critical habitat or the occupied range of any listed species. If so, the Agency would examine whether the pesticide's potential impacts on non-endangered species would affect the listed species indirectly, or directly affect a constituent element of the critical habitat. Alternatively, the agencies could determine which listed species depend on biological resources, or have constituent elements that fall into, the taxa that may be directly or indirectly

### impactedby the pesticide. Then the Agency would determine whether use ofthepesticide overlaps the critical habitat or the occupied range ofthoselisted species. Atpresent,the information reviewed by the Agency does not permit use of either analytical approach to make a definitive identification of species that are potentially impacted indirectly or critical habitats that is potentially impacted directlyby the use of the pesticide. The Agency and the Service(s) will work together to conduct the necessary analysis. This screening-level risk assessment for critical habitat provides a listing of potential biological featuresthat, if they are constituent elements of one or more critical habitats, would be ofpotentialconcern. Thesecorrespondto thetaxa identified above asbeing ofpotential concernfor indirect effects and include birds, mammals, terrestrial-phase amphibians, reptiles, fish, aquatic invertebrates and aquatic-phase amphibians. This list should serve as an initial step in problem formulation for further assessment of critical habitat impacts outlined above.

e. 

### Co-occurrenceAnalysis 

### The goal of the analysis for co-location is to determine whether sites of pesticide use are geographically associated with known locations of listed species. At the screening level, this analysis is accomplished using the Agency's LOCATES database. The database uses location informationfor listed species at the county level and comparesitto agricultural census data for crop production at the samecounty level ofresolution. Theproduct is a listing offederally listed species that are located within states known to produce the crop upon which the pesticide will be used. Because the Level 

### I screening assessment considers both 

### direct and indirect effects across generic taxonomic groupings,it is not possible to excludeanytaxonomic group from aLOCATES database run for a screening risk assessment. Although use data is available, the labeled wheat usage allows for nationwide application. Additionally, the LOCATES database does not have a pasturelrangeland co-occurrence search capacityat the present time. As noted previously, at the screening level, it is not possible to evaluate all the potential indirect effects that could impact endangered animals because the potential biological significance of the interdependency between directly affected plants and potentially adversely affected animals requires species-specific analysis.. Therefore, we cannot preclude the possibility of a 

### 'may effect' designation all listed animals at the current extent ofthis analysis.

### 6.0 

### REFERENCES Andersen, S.A., P.B. Hertz, T. Holst, R. Bossi, C.S. Jacobsen. 2001. Mineralization studies of 14C-labeled metsulfuron-methyl, tribenuron-methyl, chlorsulfuronandthifensulfuron-methylin one Danish soil and groundwater sedimentprofile. Chemosphere45,775-782. Barolo, D. 1993. EPA Memo to Vic Kimm and Susan Wayland and Background Paper on Sulfonylurea Herbicides and Drift. Battaglin, W.A., E.T. Furlon,., M.R. Burkhardt,., and C.J. Peter. 2000. Occurrence of Sulfonylurea, Sulfonamide, Imidazolinone, and Other Herbicides in Rivers, Reservoirs, and Ground Water in the Midwestern United States, 1998. The Science of the Total Environment, 248(2-3), 123-133. Berger, B and N.L. Wolfe. 1996. Hydrolysis and Biodegradation of Sulfonylurea Herbicides in Aqueous Buffers and Anaerobic Water-Sediment Systems: Assessing Fate Pathways using Molecular Descriptors, Environmental Toxicology and Chemistry 15(9), 1500-1 507. Beyer, E.M., M.E. Duffj..,J. V. Hay and D.D Schlueter. 1988 Sulfonylurea herbicides. In P. C. Kearny and D.D. Kaufman, eds., Herbicides-Chemistry, Degradation ,and Mode of Action. Marcel Dekker, New York, NY, USA, pp. 1 17-1 89. Bhatti, M.A., K. Al- Khatib, A.S. Felsot, R. Parker and S. Kadir. 1995. Effects of Simulated Chlorsulfuron Drift on Fruit Yield and Quality of Sweet Cherries (PrunusAviumL.). Environ. Tox. Chem. Vol 14 No. 3, pp. 537-544. Bird, S.L. 1992. A Compilation of Aerial Spray Drift Data. Abstracts, 13th Annual Meeting, Society of Environmental Toxicology and Chemistry. Cincinnati, OH, USA, November 8- 12,pp.27 Bird, S.L., D.M. Esterly, and S.G.Perry. 1996. Off-Target DepositionofPesticides from Agricultural Aerial Spray Applications.J. Environ. Qual. 25: 1095- 1104. Brewster,B.D., and A.P.Appleby. 1983. Response of Wheat andRotation Cropsto ChlorsulfuronWeed Sci. 31:861-865. Clark, J., L.S. Ortego and A. Fairbrother, 2004. Sourcesofvariabilityin plant toxicity testing. Chemosphere 57:1599-1612. Correll, D.L. and T.L. Wu. 1982.Atrazine Toxicity to Submerged Vascular Plants in Simulated Estuarine Microcosms. Aqu. Bot. 14, pp. 151-158. Coyner, A., G. Gupta, and T. Jones. 2000. Effect of Chlorsulfuron on Growth of Submerged Aquatic Macrophyte. Potamogetonpectinatus (Sago Pondweed). Environ. Pollut. 111, pp 453-455. Dernoeden, P.H. 1990. Comparison of Three Herbicides for Selective Tall Fescue Control in Kentucky Bluegrass Agron J 82(2):278-282. Dupont Vegetation Management. 2002. Noxious/Selective Weed Control, Escort XP herbicide and Telar DF Herbicide. 25 pp.Felsot, A.S., M.A.Bhatti, G.I.Mink, and G. Reisenauer. 1996. Biomonitoringwith Sentinel PlantstoAssess ExposureofNontarget CropstoAtmospheric Deposition of Herbicides. Environmental Toxicology and Chemisty. 15(4): 452-459. Fletcher, J.S. 1991. Horse Heaven Hills/BadgerCanyon, A case Study of Alleged Pesticide Drift Damage. Presentation at the 84th Annual Meeting & Exhibition, Vancouver, British Columbia 91-1 50.7 FletcherJ.S., T. G. Pfleegerand H.C. Ratsch 1993. PotentialEnvironmentalRisks Associatedwith theNew Sulfonylurea Herbicides. Environ. Sci. Technol.Vol27, No 10, pp. 2250-2252. Fletcher J.S., T. G. Pfleeger and H.C. Ratsch 1995. Chlorsulfuron Influence on Garden Pea Reproduction. Physiologia Plantarum 94: pp 261-267. Fletcher J.S., T. G. Pfleeger, H.C. Ratsch and R. Hayes 1996. Potential Impacts of Low Levels of Chlorsulfuronand OtherHerbicideson Growth and Yields of Non-target Plants. Environ, Tox. and Chem. Vol. 15, No. 7. pp 1189-1 196. Hewitt, A.J., D.R. Johnson, J.D.Fish, C.G.Hermansky, and D.L.Valcore. 2002. Development ofthe Spray Drift Task Force Database for Aerial Applications. Environmental Toxicology and Chemisty. 21(3):648-358. Hurly, L.M., 1994. Field Guide to the Submerged Aquatic Vegetation of Chesapeake Bay. U.S. Fish and Wildlife Service, Annapolis, MD. Ivany, J.A. 1987. Chlorsulfuron Use in Barley and Residual Effect on Potato and Rutabaga Grown in Rotation Can J Plant Sci Rev Can Phytotechnie 67(1):337-341. Jobin, B., C Boutin, and JL DesGranges. 1997. Effects of agricultural practices on the flora of hedgerows and woodland edges in southern Quebec. CanJPlant 

### Sci 77:293-299. Khodayari, K., R.E. Frans, and K.H. Akkari. 1985. Evaluation of Chlorsulfuron in Wheat (Triticum Aestivum) and in A Wheat-Soybean(Glycine Max)Double-Cropping SystemWeed Sci.33(5):746- 749. Kleijn, D., and GI Snoeijing. 1997. Field boundary vegetation and the effects of agrochemical drift: botanical change caused by low levels of herbicide and fertilizer. Journal of Applied Ecology 34: 1413-1425. Klingarnan, T.E., and T.F. Peeper. 1989. Weed Control in Winter Wheat (Triticum Aestivum) with Chlorsulfuron and Cga 131036 and Comparison of Modes of Action. Weed Technol J Weed Sci.. Soc. Am. 3(3):490-496. Lemerle, D., A.R. Leys, C.R. Kidd, and B.R. Cullis. 1990. Influences ,of Soil Ph and Climate on the Tolerance of Barley and Wheat to Chlorsulfuron Aust. J. Exp. Agric. 30(5):629-635. Leys, A.R., andF.W. Slife. 1988.Absorption and Translocationof 14C-Chlorsulfuron and 14C-Metsulfuron in Wild Garlic (Allium Vineale) Weed Sci. 36(1): 1-4.Martin, D.A., S.D. Miller, and H.P. Alley. 1990. Spring Wheat Response to Herbicides Applied at Three Growth Stages Agr0n.J. 82(1):95-97. Matthews, J.M., J.A.M. Holtum, D.R. Liljegren, B. Furness, and S.B. Powles. 1990. Cross-Resistanceto Herbicides in Annual Ryegrass (Lolium rigidum) 1.Properties of the Herbicide Target Enzymes Acetyl-Coenzyme A Carboxylase and Acetolactate Synthase Plant Physiol. 94(3): 1 180-1186. Mersie, W., and C.L. Foy. 1986. Effects of Acidity of Simulated Rain and Its Influence on the Phytotoxicity of Chlorsulfbron on Velvetleaf and Barley Environ Exp Bot Oxford 26(4):341-347. Moore, J.H., and J.F. Elliott. 1989. Wine Grape-Vine Toleranceto Chlorsulfuron and Metsulfuron Methyl Herbicides Plant Prot Q 4(3): 100-103. Nalewaja, J.D., and Z. Woznica. 1985.Environmentand Chlorsulfuron PhytotoxicityWeed Sci. 33(3):395- 399. Pallett,K.Efficacy testing processes in industry: relevance forNTTP assessment. Efficacy DataWorkshop. August 20,2003. Office of Pesticide Programs, Crystal City, Arlington, VA. Rubin, B., and J.E. Casida. 1985.R-25788 Effects on Chlorsulfuron Injury and Acetohydroxyacid Synthase Activity Weed Sci. 33(4):462-468. Saari,L.L., J.C. Cotterman, and M.M. Primiani. 1990. Mechanismof Sulfonylurea Herbicide Resistance in the Broadleaf Weed, Kochia Scoparia Plant Physiol. 93(1):55-61. Teske, M.E., S.L. Bird, D.M. Esterly, T.B. Curbishley, S.L. Ray, and S.G. Perry. AgDRIFT: A Model for Estimating Near-Field Spray Drift from Aerial Applications. Environmental Toxicology and Chemistry.2 1(3)659-671. Weed Science Society ofAmerica. 1989. Herbicide Handbook. Published by the Weed Science Societyof America. Champaign, 

### IL. Zahnow, E.W. 1982. Analysis of the Herbicide Chlorsulfuron in Soilby Liquid Chromatography.J. Agric. Food Chem. 302354457.

### APPENDIX 1. 

### PRZMIEXAMS INPUT FILES
PRZM input for Florida Turf FL 8/09/2001 Osceola County; Representation of the Lake Kissimmee/Indian River Region; MLRA 156A; Metfile: W12834.dvf [Daytona Beach] (old: Met156A.met) 

### *** Record 3: 0.78 0 0 2 5 1 3 *** Record 6 -- ERFLAG 4 

### *** Record 7: 0.04 0.303 *** Record 8 1. *** Record 9 1 0.1 10 100 3 74 74 74 0 *** Record 9a-d 5 1 2 5 0101 1601 0102 1602 0103 1603 0104 1604 0105 1605 0106 1606 0107 1507 1607 0108 .023 .026 .030 .035 .042 .050 .056 .060 .063 .068 .074 .079 .082 .I25 .I48 .I89 .023 .023 .023 .023 .023 .023 .023 .023 .023 .023 .023 .023 .023 .023 .023 .023 1608 0109 1609 0110 1610 0111 1611 0112 1612 .229 .265 .294 .314 .326 .017 .018 .019. .021 .023 .023 .023 .023 .023 .023 .023 .023 .023 *** Record 10 -- NCPDS, the number of cropping periods 3 0 *** Record 11 010261 150261 151261 1 010262 150262 151262 1 010263 150263 151263 1 010264 150264 151264 1 010265 150265 151265 1 010266 150266 151266 1 010267 150267 151267 1 010268 150268 151268 1 010269 150269 151269 1 010270 150270 151270 1 010271 150271 151271 1 010272 150272 151272 1 010273 150273 151273 1 010274 150274 151274 1 010275 150275 151275 1 010276 150276 151276 1 010277 150277 151277 1 010278 150278 151278 1 010279 150279 151279 1 010280 150280 151280 1 010281 150281 151281 1 010282 150282 151282 1 010283 150283 151283 1 010284 150284 151284 1 010285 150285 151285 1 010286 150286 151286 1 010287 150287 151287 1 010288 150288 151288 1 010289 150289 151289 1 010290 150290 151290 1 *** Record 12 -- PTITLE chlor - 1 applications @ 0.0625 kg/ha*** Record 13 3 0 1 0 0 

### *** Record 15 -- PSTNAM chlor *** Record 16 010461 0 2 0.00.0625 0.95 0.16 010462 0 2 0.00.0625 0.95 0.16 010463 0 2 0.00.0625 0.95 0.16 010464 0 2 0.00.0625 0.95 0.16 010465 0 2 0.00.0625 0.95 0.16 010466 0 2 0.00.0625 0.95 0.16 010467 0 2 0.00.0625 0.95 0.16 ' 010468 0 2 0.00.0625 0.95 0.16 010469 0 2 0.00.0625 0.95 0.16 010470 0 2 0.00.0625 0.95 0.16 010471 0 2 0.00<0625 0.95 0.16 010472 0 2 0.00.0625 0.95 0.16 010473 0 2 0.00.0625 0.95 0.16 010474 0 2 0.00.0625 0.95 0.16 010475 0 2 0.00.0625 0.95 0.16 010476 0 2 0.00.0625 0.95 0.16 010477 0 2 0.00.0625 0.95 0.16 010478 0 2 0.00.0625 0.95 0.16 010479 0 2 0.00.0625 0.95 0.16 010480 0 2 0.00.0625 0.95 0.16 010481 0 2 0.00.0625 0.95 0.16 010482 0 2 0.00.0625 0.95 0.16 010483 0 2 0.00.0625 0.95 0.16 010484 0 2 0.00.0625 0.95 0.16 010485 0 2 0.00.0625 0.95 0.16 010486 0 2 0.00.0625 0.95 0.16 010487 0 2 0.00.0625 0.95 0.16 010488 0 2 0.00.0625 0.95 0.16 010489 0 2 0.00.0625 0.95 0.16 010490 0 2 0.00.0625 0.95 0.16 *** Record 17 0 1 0 *** Record 18 0 0 0.5 

### *** Record 19 -- STITLE Adamsville Sand; Hydrologic Group C *** Record 20 102 001000000 

### *** Record 26 0 0 0 

### *** Record 30 4 3 6 *** Record 33 4 1 2 0.37 0.47 0 0

0.0021660.002166 0 0.1 0.47 0.27 7.5 0 2 10 1.44 0.086 0 0

0.0021660.002166 0 0.1 0.086 0.036 0.58 0 3 \ 10 1.44 0.086 0 0

0.0021660.002166 0 0.1 0.086 0.036 0.58 0 4 8 0 1.58 0.03 0 00.0021660.002166 0 5 0.03 0.023 0.116 0 ***Record 40 0 YEAR 10 YEAR 10 1 1 ----- 7 YEAR PRCP TCUM 0 0 RUNF TCUM 0 0 INFL TCUM 1 1 ESLS TCUM 0 0 1.OE3 RFLX TCUM 0 0 1.OE5 EFLX TCUM 0 0 1.OE5 RZFX TCUM 0 0 1.OE5 YEAR 10 1

PRZM input for Pennsylvania Turf PA Turf; 912810 1 "York Co, MLRA 148;Metfile: W14737.dvf (old: Metl48.met), 

### *** Record 3:

0.76 0.3 0 12.5 1 3 

### *** Record 6 

### -- ERFLAG 4 

### *** Record 7:

0.33 0.123 1 172.8 3 12 600 

### *** Record 8 1 

### *** Record 9 1 0.1 10 100 3747474 0 5 

### *** Record 9a-d 1 26 0101 16010102 16020103 1503 1603 0104 16040105 16050106 1506 16060107 1607 .015 .015 .015 .015 .015 .017 .012 ,006 .002.007 .004 .002 .007 .005 .003 .001 110.110.110 .I10 .I10 .I10 .110.110 .I10 .I10 .I10 .I10 .I10 .I10 .110.110 0108 16080109 16090110 16100111 16110112 1612 .005 .003 .003 .005 .009 .013 .013 .014 .014 .015 .I10 .I10 .I10 .I10 .I10 .110.110 .I10 .I10 .I10 

### *** Record 10

### -- NCPDS, the number of cropping periods 3 0 

### *** Record 1 1

010461 150461 011161 1 010462 150462011162 1 010463 150463 011163 1 010464 150464 011164 1 010465 150465 011165 1 010466 150466011166 1 010467 150467 011167 1 010468 150468 011168 1 010469 150469 011169 1 010470 150470011170 1 010471 150471 011171 1 010472 150472 011172 1010473 150473 011173 1 010474 150474 011174 1 010475 150475011175 1 010476 150476011176 1 010477 150477011177 1 010478 150478 011178 1 010479 150479 011179 1 010480 150480 011180 1 010481 150481 011181 1 010482 150482 011182 1 010483 150483 011183 1 010484 150484011184 1 010485150485 011185 1 010486 150486 011186 1 010487 150487 011187 1 010488 150488 011188 1 010489 150489 011189 1 010490 150490 011190 1 

### *** Record 12 

### -- PTITLE chlor 

### - 1 applications @ 0.0625 kg/ha 

### *** Record 13 30100 

### *** Record 15 

### -- PSTNAM chlor 

### *** Record 16

010461 0 2 0.00.0625 0.95 0.16 010462 0 2 0.00.0625 0.95 0.16 010463 0 2 0.00.0625 0.95 0.16 010464 0 2 0.00.0625 0.95 0.16 010465 0 2 0.00.0625 0.95 0.16 010466 0 2 0.00.0625 0.95 0.16 010467 0 2 0.00.0625 0.95 0.16 0 10468 0 2 0.00.0625 0.95 0.16 010469 0 2 0.00.0625 0.95 0.16 010470 0 2 0.00.0625 0.95 0.16 010471 0 2 0.00.0625 0.95 0.16 010472 0 2 0.00.0625 0.95 0.16 010473 0 2 0.00.0625 0.95 0.16 010474 0 2 0.00.0625 0.95 0.16 010475 0 2 0.00.0625 0.95 0.16 010476 0 2 0.00.0625 0.95 0.16 010477 0 2 0.00.0625 0.95 0.16 010478 0 2 0.00.0625 0.95 0.16 010479 0 2 0.00.0625 0.95 0.16 010480 0 2 0.00.0625 0.95 0.16 010481 0 2 0.00.0625 0.95 0.16 010482 0 2 0.00.0625 0.95 0.16 010483 0 2 0.00.0625 0.95 0.16 010484 0 2 0.00.0625 0.95 0.16 010485 0 2 0.00.0625 0.95 0.16 010486 U2 0.00.0625 0.95 0.16 010487 0 2 0.00.0625 0.95 0.16 010488 0 2 0.00.0625 0.95 0.16010489 0 2 0.00.0625 0.95 0.16 010490 0 2 0.00.0625 0.95 0.16 

### *** Record 17 010 

### *'* Record 18 0 0 0.5 

### *** Record 19

### -- STITLE "Glenville, SiltLoam, HYDG: C" 

### *** Record 20 102 001000000 

### ***Record 26 000 

### *** Record 30 4 36 

### *** Record 33 4 1 2 0.37 0.47 0 0 0 0.0021660.002166 0 0.1 0.47 0.27 7.5 0 2 10 1.4 0.254 0 0 0 0.002 1660.002166 0 0.1 0.254 0.094 1.74 0 3 12 1.4 0.254 0 0 0 0.0021660.002166 0 2 0.254 0.094 1.74 0 4 78 1.8 0.201 0 0 0 0.0021660.002166 0 2 0.201 0.121 0.174 0 ***Record 40 0 YEAR 10 YEAR 10 YEAR 10 1 1 1 

### ----- 7 YEAR PRCP TCUM 0 0 RUNF TCUM 0 0 INFL TCUM 1 1 ESLS TCUM 0 0 1.OE3 RFLX TCUM 0 0 1.OE5 , EFLX TCUM 0 0 1.OE5 RZFX TCUM 0 0 1.OE5
PRZM input for North Dakota Wheat North Dakota Spring Wheat MLRA F56 Cass County Bearden silty clay loam "Red River Valley of the North MLRA 56 MN, ND, SD 1948-1983;Metfile: W14914.dvf (old: Met56.met), 

### *** Record 3:

0.75 0.5 0 12 1 1 

### *** Record 6 

### -- ERFLAG 4 

### *** Record 7:

0.28 0.17 1 172.8 3 1.5 600 

### *** Record 8 1

### **

### * Record 9 1 0.1 22 100 1918587 0 100 

### *** Record 9a-d 1 28 0101 16010102 16020103 16030104 1604200401050505 16050106160601071607 .583 .581 .579 .577 .574 .574 ,575 .575 .611 .617 .610 .562 .468 .268 .092 .064 .014 .014 .014 .014 .014 .014 .014 .014 .014 .014 .014 .014 .014 .014 .014 .014 01080508 1008 160801091609011016100111 16110112 1612 .065 .036 .098 .110 .I26 .I39 .I52 .I62 .I68 .I70 .I71 .I71 .014 .014 .014 .014 .014 .014 .014 .014 .014 .014 .014 .Old 

### *** Record 10

### -- NCPDS, the number of cropping periods 3 0 

### *** Record 1 1

150561 250761 050861 1 150562 250762 050862 1 150563 250763 050863 1 150564 250764 050864 1 150565 250765 050865 1 150566 250766 050866 1 150567 250767 050867 1 150568 250768 050868 1 150569 250769 050869 1 150570 250770 050870 1 150571 250771 050871 1 150572 250772 050872 1 150573 250773 050873 1 150574 250774 050874 1 150575 250775 050875 1 150576 250776 050876 1 150577 250777 050877 1 150578 250778 050878 1 150579 250779 050879 1 150580 250780 050880 1 150581 250781 050881 1 150582 250782 050882 , 1 150583 250783 050883 1 150584 250784 050884 1 150585 250785 050885 1 150586 250786 050886 1 150587 250787 050887 1 150588 250788 050888 1 150589 250789 050889 1 150590 250790 050890 1 

### *** Record 12 -- PTITLE chlor 

### - 1 applications @ 0.023 kg/ha 

### *** Record 13 30100 

### *

### ** Record 15 -- PSTNAM chlor 

### *** Record 16

050161 0 2 0.0 0.023 0.95 0.16 050162 0 2 0.0 0.023 0.95 0.16 050163 0 2 0.0 0.023 0.95 0.16050164 0 2 0.0 0.023 0.95 0.16 050165 0 2 0.0 0.023 0.95 0.16 050166 0 2 0.0 0.023 0.95 0.16 050167 0 2 0.0 0.023 0.95 0.16 050168 0 2 0.0 0.023 0.95 0.16 050169 0 2 0.0 0.023 0.95 0.16 050170 0 2 0.0 0.023 0.95 0.16 050171 0 2 0.0 0.023 0.95 0.16 050172 0 2 0.0 0.023 0.95 0.16 050173 0 2 0.0 0.023 0.95 0.16 050174 0 2 0.0 0.023 0.95 0.16 050175 0 2 0.0 0.023 0.95 0.16 050176 0 2 0.0 0.023 0.95 0.16 050177 0 2 0.0 0.023 0.95 0.16 050178 0 2 0.0 0.023 0.95 0.16 050179 0 2 0.0 0.023 0.95 0.16 050180 0 2 0.0 0.023 0.95 0.16 050181 0 2 0.0 0.023 0.95 0.16 050182 0 2 0.0 0.023 0.95 0.16 050183 0 2 0.0 0.023 0.95 0.16 050184 0 2 0.0 0.023 0.95 0.16 050185 0 2 0.0 0.023 0.95 0.16 050186 0 2 0.0 0.023 0.95 0.16 050187 0 2 0.0 0.023 0.95 0.16 050188 0 2 0.0 0.023 0.95 0.16 050189 0 2 0.0 0.023 0.95 0.16 050190 0 2 0.0 0.023 0.95 0.16 

### *** Record 17 0 10 

### *** Record 18 0 0 0.5 

### *** Record 19 -- STITLE Bearden silty clay loam; HTDG: C 

### *** Record 20 100 001000000 

### *** Record 26 0 0 0 

### *** Record 30 4 36 

### *** Record 33 3 1 10 1.40.377 0 0 0 0.0021660.002166 0 0.1 0.377 0.207 1.74 0 2 52 1.5 0.292 0 0 0 0.002 1660.0021 66 0 1 0.292 0.132 0.116 0 3 38 1.80.285 0 0 0 0.0021660.002166 0 2 0.285 0.125 0.058 0 ***Record40 0 T YEAR 10 YEAR 10 YEAR 10 11 1 

### ----- 7 YEAR PRCP TCUM 0 0 RUNF TCUM 0 0 INFL TCUM 1 1 ESLS TCUM 0 0 1.OE3 RFLX TCUM 0 0 1.OE5 EFLX TCUM 0 0 1.OE5 RZFX TCUM 0 0 1.OE5 PRZM input for Texas Wheat TX wheat; 8/13/200 1 "Winterwheat in Blacklandsprairie sectionofTexas grown onbenchmark Crockett soil.HGRP: D; MLRA 87;Metfile: W13958.dvf (old: Met87.met), Waco met station " 

### *** Record 3:

0.71 0.5 0 10 1 3 

### *** Record 6 -- ERFLAG 4 

### *" Record 7:

0.43 0.103 1 172.8 1 3 600 

### *** Record 8 1 

### *** Record 9 1 0.1 110 99 3948788 0 90 

### *** Record 9a-d 1 28 0101 1601 0102 1602 0103 1603 0104 1604 0105 1605 0106 16062006 0107 16070108 .I25 .I11 .lo1 .094 .074 .043 .044 .046 .080 .083 .086 .087 .026 .027 .029.03 1 .014 .014 .014 .014 .014 .014 .014 .014 .014 .014 .014 .014 .014 .014 .014 .014 16080109 10091609200925090110 16100111 1611 01121612 .033 .035 .I10 .I19 .266 .318 .318 .293 .218 .I87 .I63 .I36 .014 .014 ,014 .014 .014 .014 .014 .014 .014 .014 .014 .014 

### * * * Record 10 -- NCPDS, the number of cropping periods 30 

### *** Record 11

101061 300461 170661 101062 300462 170662 101063 300463 170663 101064 300464 170664 101065 300465 170665 101066 300466 170666 101067 300467 170667 101068 300468 170668 101069 300469 170669 101070 300470 170670 101071 300471 170671 101072 300472 170672 101073 300473 170673 101074 300474 170674 101075 300475 170675 101076 300476 170676 101077 300477 170677101078 300478 170678 1 101079 300479 170679 1 101080 300480 170680 1 101081 300481 170681 1 101082 300482 170682 1 101083 300483 170683 1 101084 300484 170684 1 101085 300485 170685 1 101086 300486 170686 1 101087 300487 170687 1 101088 300488 170688 1 101089 300489 170689 1 101090 300490 170690 1 

### *** Record 12 

### -- PTITLE chlor - 1 applications @ 0.023 kgiha 

### **

### * Record 1 3 30100 

### *** Record 15 

### -- PSTNAM chlor 

### *** Record 16

150961 0 2 0.0 0.023 0.95 0.16 150962 0 2 0.0 0.023 0.95 0.16 150963 0 2 0.0 0.023 0.95 0.16 150964 0 2 0.0 0.023 0.95 0.16 150965 0 2 0.0 0.023 0.95 0.16 150966 0 2 0.0 0.023 0.95 0.16 150967 0 2 0.0 0.023 0.95 0.16 150968 0 2 0.0 0.023 0.95 0.16 150969 -0 2 0.0 0.023 0.95 0.16 150970 0 2 0.0 0.023 0.95 0.16 150971 0 2 0.0 0.023 0.95 0.16 150972 0 2 0.0 0.023 0.95 0.16 150973 0 2 0.0 0.023 0.95 0.16 150974 0 2 0.0 0.023 0.95 0.16 150975 0 2 0.0 0.023 0.95 0.16 150976 0 2 0.0 0.023 0.95 0.16 150977 0 2 0.0 0.023 0.95 0.16 150978 0 2 0.0 0.023 0.95 0.16 150979 0 2 0.0 0.023 0.95 0.16 150980 0 2 0.0 0.023 0.95 0.16 150981 0 2 0.0 0.023 0.95 0.16 150982 0 2 0.0 0.023 0.95 0.16 150983 0 2 0.0 0.023 0.95 0.16 150984 0 2 0.0 0.023 0.95 0.16 150985 0 2 0.0 0.023 0.95 0.16 150986 0 2 0.0 0.023 0.95 0.16 150987 0 2 0.0 0.023 0.95 0.16 150988 0 2 0.0 0.023 0.95 0.16 150989 0 2 0.0 0.023 0.95 0.16 150990 0 2 0.0 0.023 0.95 0.16 

### *** Record 17 0 10 

### *** Record 180 0 0.5 

### *** Record 19 

### -- STITLE "Crockett fine sandy loam 

### - Fine, smectic, thermic Udertic Paleustalf " 

### *** Record 20 110 001000000 

### *** Record 26 000 

### *** Record 30 4 36 

### *** Record 33 3 1 10 1.6 0.17 0 0 0 0.0021660.002166 0 0.1 0.17 0.06 1.16 0 2 10 1.6 0.17 0 0 0 0.0021660.002166 0 10 0.17 0.06 1.16 0 3 90 1.7 0.247 0 0 0 0.0021660.002166 0 10 0.247 0.127 0.29 0 *"Record 40 0 YEAR 10 YEAR 10 YEAR 10 1 1 1 

### ----- 7 YEAR PRCP TCUM 0 0 RUNF TCUM 0 0 INFL TCUM 1 1 ESLS TCUM 0 0 1.OE3 RFLX TCUM 0 0 1.OE5 EFLX TCUM 0 0 1.OE5 RZFX TCUM 0 0 1.OE5 Typical EXAMS input file (index reservoir shown here, farm pond differs only by setting STFLO to zero)
set mode = 3 set outfil(4) to Y set outfil(2) to N READ ENV C:\models\INPUTS\EXAMSenv\ir298.exv READ MET C:\models\INPUTS\Metfiles\w12834.dvf SET YEAR1 = 1961 recall chem 1 chemical name is chlor set MWT(1) = 357.8 set VAPR(1) = 4.6e-6 set SOL(1,l) = 31800 set KOC(1) = 36 set QTBAS(*,l,l) = 2 set QTBAW(*,l,l) = 2 READ PRZM P2E-Cl.D61 SET STFLO (1, *) = 22.2104590672629 set EVAP(*,*) = 0.0 set NPSFL(*,*)=O.O set NPSED(*,*)=O.O set RAIN(*) = 0.0RUN READ PRZM P2E-C1.D62 SET STFLO(1, *) = 22.2104590672629 set EVAP(*,*) = 0.0 set NPSFL (*, *)=O. 0 set NPSED(*,*)=O.O set RAIN(*) = 0.0 CONTINUE READ PRZM P2E-Cl.D63 SET STFLO(1,*) = 22.2104590672629 set EVAP(*,*) = 0.0 set NPSFL (*, *)=O. 0 set NPSED(*,*)=O.O set RAIN(*) = 0.0 CONTINUE READ PRZM P2E-Cl.D64 SET STFLO (1, *) = 22.2104590672629 set EVAP(*,*) = 0.0 set NPSFL(*,*)=O.O set NPSED(*,*)=O.O set RAIN(*) = 0.0 CONTINUE READ PRZM P2E-Cl.D65 SET STFLO (1, *) = 22.2104590672629 set EVAP(*,*) = 0.0 set NPSFL(*,*)=O.O set NPSED(*,*)=O.O set RAIN(*) = 0.0 CONTINUE READ PRZM P2E-Cl.D66

- -- SET STFLO (1, *) = 22.2104590672629 set EVAP(*,*) = 0.0 set NPSFL(*,*)=O.O set NPSED(*,*)=O.O set RAIN(*) = 0.0 CONTINUE READ PRZM P2E-Cl.D67 SET STFLO (1, *) = 22.2104590672629 set EVAP(*,*) = 0.0 set NPSFL (*, *)=O. 0 set NPSED(*,*)=O.O set RAIN(*) = 0.0 CONTINUE READ PRZM P2E-Cl.D68 SET STFLO (1, *) = 22.2104590672629 set EVAP(*,*) = 0.0 set NPSFL(*,*)=O.O set NPSED(*,*)=O.O set RAIN(*) = 0.0 CONTINUE READ PRZM P2E-Cl.D69 SET STFLO(1,*) = 22.2104590672629 set EVAP(*,*) = 0.0 set NPSFL(*,*)=O.O set NPSED(*,*)=O.O set RAIN(*) = 0.0 CONTINUE READ PRZM P2E-Cl.D70 SET STFLO (1, *) = 22.2104590672629set EVAP(*,*) = 0.0 set NPSFL (*, *) =O. 0 set NPSED(*,*)=O.O set RAIN(*) = 0.0 CONTINUE READ PRZM P2E-C1.D71 SET STFLO(1,*) = 22.2104590672629 set EVAP(*,*) = 0.0 set NPSFL (*, *)=O. 0 set NPSED (*, *)=O. 0 set RAIN(*) = 0.0 CONTINUE READ PRZM P2E-Cl.D72 SET STFLO (1, *) = 22.2104590672629 set EVAP(*,*) = 0.0 set NPSFL (*, *) =O. 0 set NPSED (*, *)=O. 0 set RAIN(*) = 0.0 CONTINUE READ PRZM P2E-Cl.D73 SET STFLO(l,*) = 22.2104590672629 set EVAP(*,*) = 0.0 set NPSFL(*,*)=O.O set NPSED(*,*)=O.O set RAIN(*) = 0.0 CONTINUE READ PRZM P2E-Cl.D74 SET STFLO (1, *) = 22.2104590672629 set EVAP(*,*) = 0.0 set NPSFL(*,*)=O.O set NPSED(*,*)=O.O set RAIN(*) = 0.0 CONTINUE READ PRZM P2E-Cl.D75 SET STFLO (1, *) = 22.2104590672629 set EVAP(*,*) = 0.0 set NPSFL (*, *)=O. 0 set NPSED(*,*)=O.O set RAIN(*) = 0.0 CONTINUE READ PRZM P2E-Cl.D76 SET STFLO(1,*) = 22.2104590672629 set EVAP(*,*) = 0.0 set NPSFL(*,*)=O.O set NPSED (*, *)=O. 0 set RAIN(*) = 0.0 CONTINUE READ PRZM P2E-Cl.D77 SET STFLO (1, *) = 22.2104590672629 set EVAP(*,*) = 0.0 set NPSFL (*, *)=O. 0 set NPSED(*,*)=O.O set RAIN(*) = 0.0 CONTINUE READ PRZM P2E-Cl.D78 SET STFLO (1, *) = 22.2104590672629 set EVAP(*,*) = 0.0 set NPSFL(*,*)=O.O set NPSED(*,*)=O.0set RAIN(*) = 0.0 CONTINUE READ PRZM P2E-Cl.D79 SET STFLO (1, *) = 22.2104590672629 set EVAP(*,*) = 0.0 set NPSFL (*, *)=Of 0 set NPSED(*,*)=O.O set RAIN(*) = 0.0 CONTINUE READ PRZM P2E-Cl.D80 SET STFLO (1, *) = 22.2104590672629 set EVAP(*, *) = 0.0 set NPSFL(*,*)=O.O set NPSED(*,*)=O.O set RAIN(*) = 0.0 CONTINUE READ PRZM P2E-Cl.D81 SET STFLO(l,*) = 22.2104590672629 set EVAP(*,*) = 0.0 set NPSFL(*,*)=O.O set NPSED(*,*)=O.O set RAIN(*) = 0.0 CONTINUE READ PRZM P2E-Cl.D82 SET STFLO(l,*) = 22.2104590672629 set EVAP(*,*) = 0.0 set NPSFL (*, *)=O. 0 set NPSED (*, *)=O. 0 set RAIN(*) = 0.0 CONTINUE READ PRZM P2E-Cl.D83 SET STFLO (1, *) = 22.2104590672629 set EVAP(*,*) = 0.0 set NPSFL (*, *)=O. 0 set NPSED(*,*)=O.O set RAIN(*) = 0.0 CONTINUE READ PRZM P2E-Cl.D84 SET STFLO (1, *) = 22.2104590672629 set EVAP(*,*) = 0.0 set NPSFL (*, *)=O. 0 set NPSED(*,*)=O.O set RAIN(*) = 0.0 CONTINUE READ PRZM P2E-C1.D85 SET STFLO (1, *) = 22.2104590672629 set EVAP(*,*) = 0.0 set NPSFL (*, *)=O. 0 set NPSED(*,*)=O.O set RAIN(*) = 0.0 CONTINUE READ PRZM P2E-Cl.D86 SET STFLO (1, *) = 22.2104590672629 set EVAP(*,*) = 0.0 set NPSFL (*, *)=O. 0 set NPSED(*,*)=O.O set RAIN(*) = 0.0 CONTINUE READ PRZM P2E-Cl.D87SET STFLO(1,*) = 22.2104590672629 set EVAP(*,*) = 0.0 set NPSFL (*, *)=O.0 set NPSED(*,*)=O.O set RAIN(*) = 0.0 CONTINUE READ PRZM PZE-~"1 

### .D88 SET STFLO (1, *) = 22.2104590672629 set EVAP(*,*) = 0.0 set NPSFL(*,*)=O.O set NPSED(*,*)=O.O set RAIN(*) = 0.0 CONTINUE READ PRZM P2E-Cl.D89 SET STFLO(1, *) = 22.2104590672629 set EVAP(*,*) = 0.0 set NPSFL (*, *)=O. 0 set NPSED(*,*)=O.O set RAIN(*) = 0.0 CONTINUE READ PRZM P2E-Cl.D90 SET STFLO (1, *) = 22.2104590672629 set EVAP(*,*) = 0.0 set NPSFL(*,*)=O.O set NPSED(*,*)=O.O set RAIN(*) = 0.0 CONTINUE QUIT

### APPENDIX 2. 

### SUMMARY OF 

### CHLORSULFURON TOXICITY TESTS 

### FOR 

# 11

NOEL =35 mglkglday

6711 Due to mortality in the controls,this study is invalid and does not fulfil test guideline requirements. 21 Although the reproduction study is unacceptable, a NOAEL was determined for the effect of concern (st111births) and the LOEL was 356 mg/kg/day Reproduct~ve toxicity was observed in both generationshoth litters, as evidencedby decreased fertility of the dams No parentaltoxicity was observed 31 This study does not fulfill test guidelines requ~rementsIt is repairable ~f additional information on the solvent control and dilution water is subm~tted 41 Th~s tudy does not fulfill test guidehne requirements because mortality data were not provlded In the report

### APPENDIX 3. 

### DATA REQUIREMENTS FOR CHLORSULFURON Chemical No: 118601

1 Data Requirement Use Does EPA Have B~bliographic Must Addit~onal Pattern' Data To Satisfy Citation Data Be Subm~tted This Under FIFRA 3(c)(2)(B)7 Requirement? (Yes, No, or Part~ally) 8158.490 WILDLIFE AND AQUATIC ORGANISMS 71-l(a) Acute Avian Oral, Duck and Quail

71-2(a) Acute Avian Diet, Quail
71-2(b) Acute Avian Diet, Duck Yes 000352-63 No 000352-64 (099462)

Yes 000352-66 No (099462) 71 -3 Wild Mammal Toxicity No 71-4(a) Avian Reproduction Quail Yes 42634001 No 71-4(b) Avian Reproduction Duck Yes 42634002 No 71-5(a) Simulated TerrestrialField Study No 71-5(b) Actual TerrestrialField Study No 72-l(a) Acute Fish Toxicity BluegilllFathead
72-l(b) Acute Fish Toxicity (TEP) 72-1(c) Acute Fish Toxicity Rainbow Trout Yes 000352-58 No (099462)

419764-05 No Yes (099462) 72-l(d) Acute Fish Toxicity Rainbow Trout (TEP) No 72-2(a) Acute Aquatic Invertebrate Yes 000352-62 No (099462) 72-2(b) Acute Aquat~c Invertebrate (TEP) No 72-3(a) Acute Est/Mar ToxicityFish Yes 419764-01 No 72-3(b) Acute Est/Mar Toxicity Mollusk ' Yes 423286-01 419764-03 72-3(c) Acute EstiMar Toxicity Shrimp Yes
72-3(d) Acute EstMar ToxicityFish (TEP) No 72-3(e) Acute EstiMar Toxicity Mollusk (TEP) No 72-3(f) Acute EstIMar Toxicity Shrimp (TEP) 72-4(a) Early Life Stage Fish Yes 72-4(b) Life Cycle Aquatic Invertebrate No 419764-08 Yes l6Data Requirement Use Does EPA Have Bibliographic Must Additional Pattern' Data To Satisfy Citation Data Be Submitted This Under FIFRA 3(c)(2)(B)? Requirement? (Yes, No, or Partially) 72-5 Life Cycle F~sh 72-6 Aquatic Organism Accumulation

72-7(1) SimulatedAquat~c Field Study 72-7(b) Actual Aquatlc Field Study 8158.540 PLANT PROTECTION 122-l(a) Seed Germ.,SeedlingEmergence 122-1(b) VegetativeVigor 122-2 Aquatic Plant Growth No 123-1 (a) Seed Germ /Seedling Emerg. 463618-01 Yes l7 123-1(b) Vegetative Vigor 463268-01 Yes l7 123-2 Aquat~c Pliint Growth 421868-01 Yes l8 458329-01 No 458329-02 No 458329-03 No 458329-04 Yes l9 124-1 Terrestrial Field Study 124-2 Aquatlc F~eld Study $158.490 NONTARGET INSECT TESTING 141-1 Honey Bee Acute Contact Yes 421299-02 141-2 Honey Bee Residue on Fol~age 141-5 Field Test for Pollinators $158.290 ENVIRONMENTAL FATE Degradation Studies-Lab: 161-1 Hydrolysis 161 -2 PhotodegradationIn Water 161-3 PhotodegradationOn Soil Yes 421567-01
Yes 421567-02 Yes 421 567-03 Metabolism Studies-Lab: 162-1 Aeroblc Soil Yes 422 14201 No 0113-0013 01 13-0024 162-2 Anaerobic Soil Yes 421467-04 No Mobility Studies:Data Requirement Use Does EPA Have Bibliographic Must Additional Pattern' Data To Satisfy Citation Data Be Submitted This Under FlFRA 3(c)(2)(B)? Requirement? (Yes, No, or Partially) 163-1 Leaching-AdsorptionBesorp. 163-2 Volatility (Lab) Dissipation Studies-Field: 164-1 Soil

Accumulation Studies: 165-4 In Fish Yes

Yes

Yes 422 142-04

Ground Water Monitoring Studies: 166-1 Small-Scale Prospective 5158.440 SPRAY DRIFT

201-1 Droplet Size Spectrum 202-1 Drift Field Evaluation

FOOTNOTES:
1. l=Terrestrial Food; 2=Terrestrial Feed; 3=Terrestrial Non-Food; 4=Aquatic Food; 5=Aquatic Non-Food(Outdoor);6=Aquatic Non-Food (Industrial);7=Aquatic Non-Food (Residential);S=Greenhouse Food; 9=Greenhouse Non-Food;lO= Forestry; 1 l=Residential Outdoor; 12=Indoor Food; 13=IndoorNon-Food d; 14=IndoorMedical;l 5=Indoor Residential. 161. This study does not fulfill test guidelines requirements. It is repairable if additional information on the solvent control and dilution water is submitted. 171 This studyis scientifically sound but does not fulfillthe guideline requirements for seedlingemergence andvegetativevigor studies (Subdivision J, $123-1 (TIER 11))because the light intensity in both studies was well below guideline recommendations. 191 This studywas conductedunder static conditions. Test concentrations should be renewed 3-4 tlmes during the 14day test. This study should be repeated 201 Lysimeter studieswere submitted which do not satlsfy current guideline requirements However, the lnfonnation provlded is sufficient for this assessment.APPENDIX 4 ESTIMATED ENVIRONMENTAL CONCENTRATIONS ON AVIAN AND MAMMALIAN FOOD ITEMS (PPM) FOLLOWING A SINGLE APPLICATIONAT 1 lb ai/A

EEC (PP~) EEC (PP~) Food Items Predicted Maximum Predicted Mean Residue' Residue'
Short grass 240 85 Tall grass Broadleaflforage plants and small insects Fruits, pods, seeds, and large insects 15 7
'Predicted maximum and mean resldues are for a I lb a/aapplicatlon rate and are based on Hoerger and Kenaga (1972) as modified by Fletcher et al. (1994)

ELL-Fate Version 1.4 April 7,2004 Developed by Laurence Libelo. February, 1999 Updated by John Ravenscroft,April 2004

i This spreadsheetbased model calculates the decay of a chemical appliedto foliar surfaces for single or multiple applications. It uses the same principle as the batch code models FATE and TERREEC for calculating terrestrial estimates exposure (TEEC) concentrationson plant surfaces following application. A first order decay assumption is used to determine the concentratlonat each day after inltlal appllcatlon based on the concentratlon resulting from the lnltlal and addalonal applications The decay is calculatedby from the first order rate equatlon

or in log form:

Where CT = concentratlon at tlme T = day zero CI = concentration, in parts per milllon (PPM) present initially (on day zero) on the surfaces CIis calculatedbased on the Kanaga nomogram (Hoerger and Kenaga, (1972) as modlfied Fletcher (1994) For maximum concentration the applicatlon rate, in pounds active ingredientper acre, is multiplied by 240 for Short Grass, 1I0 for Tall Grass, and 135for Broad leafed plantslsmall insects and 15 for fru~tslpodsllg insects Additional applications are converted from pounds active lngredlentper acreto PPM on the plant surface and the additional mass added to the mass of the chemlcal still present on the surfaces on the day of applicatlon k = Ifthe fohar dissipation data submttted to EFED are found scientificallyval~d and stanstlcally robust for a spec~fic pestlclde, the 90% upper confidence limit of the mean half-llves should be used When sclentrficallyvalid, statistically robust data are not available TETT recommends the using a default half-life value of 35 days The use ofthe 35 day half-hfe is based on the highest reported value value (36 9 days) reported by W~llis and McDowell (Pesticide perslstenceon foliage, Envlron Contam TOXICO~, 100 23-73, 1987)
T = time, in days, since the start of the simulation. The initial application is on day 0. The simulation is designed to run for 365 days.The program calculatesconcentratlon on each type of surface on a daily interval for one year. The maximum concentration during the year and the average concentration during the first 56 days are calculated. The Inputs used to calculatethe amount of the chemical present are in highlighted in yellow on the spread sheet Outputs are in blue. The inputs required are. Application Rate The maximum label applicat~on rate (in pounds adacre) Half-hfe The degradation half-life for the dominateprocess(m days) Frequencyof Application The Interval between repeated applications, from the label (in days) Maximum # Application per year From the label

The calculated concentrations are used to calculateAvian and Mammalian RQ values. The maximum calculated concentration is divided by user input values of Chronic No Observable Adverse Effects Level and acute LC50 to giveRQs for each type ofplant surface. The rat LC 50 is calculatedby dividing the mammalianLD 50 by 0.05 (to correct for actual food consumption)

For 15g,35g and 1000 g mammals the RQ values are calculated by dividing the maxtmum concentratlon for each surface by the LD 50 or NOAEL corrected for consumption (0 95, 0 66 and 15body wt for herbivores and ) insectivores and 0 21,0.15 and 0 03 body wt for granrvore) The number of days that the Inputvalue of Chronic No ObservableAdverse Effects Level and acute LC50 are exceeded tn the first 56 days is calculatedby comparing the input value to the calculated concentration A graph of concentration on each plant surface vs time iGplotted and a "level of concern" line can be added at a user specified level. The maximum single application which can be applied and not exceed the toxicity input values if calculatedby dividing the input value by the Kenaga maximum concentration for Short Grass (240). This version of ELL-Fate (v1.4) incorporates the ability to calculateEECs and RQs for maxlmum and mean residues. Mean residues are calculated exactly as the maxtmum residues are, except the corresponding Kenaga values are. 85 for Short Grass, 36 for Tall Grass, and 45 for Broad leafed plantslsmallinsects and 7 for fruitslpodsllginsects.

### APPENDIX 5. 

### NON-TARGET TERRESTRIALPLANT SEEDLING EMERGENCE TOXICITY (TIER 11) FOR CHLORSULFURON (TEP 75%; 

### lbs a.i.lA).
Shoot Dry Weight Shoot Height NOEC EC,, NOEC EC,, Corn 0.000366 0.001874 0.001463 0.005174 Oat 0.001463 0.006513 0.001463 0.018735 Onion 0.000183 0.000303 0.000046 0.0005 Sorghum 0.002926 0.00 1963 0.001463 0.002141
Cucumber 0.002926 0.008922 0.011714 0.01249
Pea 0.000183 0.000223 0.002926 0.00 1071 Rape 0.000183 0.000428 0.001463 0.001517 Soybean 0.01 1714 0.023 196 0.011714 0.01249 Sugarbeet 0.000366 0.00033 0.001463 0.0004 19 Tomato 0.000366 0.000321 0.000732 0.001784



### From 

### the supplemental guideline study by Porch 

### and Martin, 2003. 

### MRID 463618-01

### APPENDIX 6 NON-TARGET TERRESTRIALPLANT VEGETATIVE VIGOR TOXICITY (TIER 11) FOR CHLORSULFURON (TEP 75%; 

### Ibs 

### a.i./A).

Species Shoot Dry Weight Shoot Height NOEC ' EC,, NOEC EC,, Corn 0.0003658 0.00037 0.0003658 0.00076
Oat 0.001463 1 0.01071 0.0058525 0.04461 Onion 0.0000054 0.00002 0.0000054 0.00005 Sorghum 0.0000919 0.000 18 0.00009 19 0.00054 Cucumber 0.00 14631 0.0040 1 0.0014631 0.0065 1
Pea 0.0000116 0.00001 0.0000232 0.00002 Rape 0.0000054 0.00001 0.0000054 0.00001 Soybean 0.0000232 0.00005 0.0000232 0.0001 1 Sugarbeet 0.0000054 0.00001 0.0000054 0.00002
Tomato 0.0001 829 0.00014 0.000 1829 0.00050

, 

### From the supplemental guideline study by Porch and Martin, 2003. MRID 463268-01

### APPENDIX 7. 

### RQ CALCULATIONS FOR SURFACEAND GROUNDWATER IRRIGATION

To calculate risk quotients for plants when groundwater contaminated by chlorsulfuron is applied to crops, the followingmethod was used. Assume a field is irrigated with one inch of water containing 1.6 ppb chlorsulfuron. One acre has 6,272,640 cubic inches of water on the field. The1 acre field with 1 inch of water has 3,630 cubic ft of water (6,272,640 

### x 0.00058 cubic Wcubic inch). The field has 27,156 gallons of water (3,630 cubic ft

### x 7.481 gallonslcubic ft). Therefore,l inch of water on the 

### 1 acre field weighs 226,625 lbs (27,156 gallons 

### x 8.3453 Ibs/gallon of water). 226,625 lb of waterlacre 

### x 1.6 (ai chlorsulfuron) = 

### 0.00036 Ibs aijacre chlorsulfuron. 1,000,000,000
Therefore, the risk quotients for sensitive crops within the field 

### that is irrigated with groundwater containing 1.6 ppb chlorsulfuron and surface water containing 6.0 ppb are calculated as follows: Ground water: EEC/EC,, for vegetative vigor = 

### 0.00036 lbs ailacre = 

### 36 0.00001 lbs ailacre Surface water: EEC/EC,, for vegetative vigor = 

### 0.00136 lbs ailacre = 

### 136 0.00001 lbs ailacre The risk quotients for endangered terrestrial plants in areas near a field 

### that is irrigated with surface water containing 1.6 ppb and groundwater containing 6.0 ppb chlorsulfuron,assuming 5% drift (of irrigation water) and no runoff are calculated as follows: If the irrigationwater from surface water contains 6.0 ppb, then it has 0.00 136 lbs ailacre chlorsulfkon. EEC = 

### 0.05 (drift)

### x 0.00136 = 

### 0.0000681 Ibs ailacre Groundwater: EECNOEC for vegetative vigor = 

### 0.0000 18 lbs ailacre = 

### 3 

### 0.0000054 Ibs ailacre Surface water: EECNOEC for vegetative vigor = 

### 0.0000681 lbs ailacre = 

### 13 0.0000054 lbs ai/acre

### APPENDIX 8. REFINED 

### SPRAY 

### DRIFT ANALYSIS FOR CHLORSULFURON
APPENDIX 8A. 

### SURVEY OF AERIAL APPLICATORS TO DETERMINE TYPICAL AIRCRAFT SETUPS Non-Confidential Version of Attachment A to DuPont Letter to USEPA Dated May 2,2003
In previous correspondence with EPA regarding the droplet size spectrum expected for typical aerial applications of chlorsulfuron products, we proposed a small, informal survey of aerial applicatorsto determine typical aircraft setups. To that end, we have obtained descriptions of the spray setups used on fifteen aircraft fiom fourteen applicators in Washington and Oregon.
To minimize drift, the Glean FC and Finesse labels specify the use of solid stream nozzles oriented straight back when the product is applied by air in the vicinity of sensitivecrops. As shown in the attached table, most of the aircraft were fitted with solid stream nozzles with a nozzle angle of 0, as recommended on the label. The drop size distributionwas determined by the USDA -ARS model implemented in A~DRIFT@ version 2.04. The model provides a drop size spectrum for a spray solution of water containing 0.25% Triton X-100. In general, we expect the drop size distributionfiom the model to be shifted toward the fine size distribution as compared to the size distribution for typical agricultural products. The inputs to the model 

### - nozzle type, orientationangle, air speed, and pressure - 

### were supplied by the applicatorsor representative values were selected as indicated in the attached table. The drop size distributionswere evenly splitbetween ASAE medium, medium to coarse, and coarse. The intent of the label recommendations is to produce 

### a drop size spectrum that will minimize drift, and we anticipated that most of the solid stream nozzles and spray settingswould produce a coarse size distribution. We attribute the difference between our expectations and the model results primarily to the higher than expected air speed used for applications. We expected that air speeds would be in the range of 100-1 10 mph, as it was for aircraft 14 and 15 in the attached table. In contrast, 10 of the 15 applicators fly at a speed of 120 mph or higher. The droplet size distribution shifts toward the fine distribution at higher speeds. For example, aircraft 4 flown at 135mph produces a medium to coarse size distribution, while at 100mph would produce a very coarse to extremely coarse size distribution, according to the USDA model. Since the USDA model simulates drop size distributionsfor a spray solutionwith low surface tension, those distributions are likely to show a greater volume of fine droplets than would be expected for typical products. Our experience in the Pacific Northwest suggests that the label recommendations have been successful in reducing drift, as compared to the potential indicated by the drop size distributionspredicted by the USDA model.

Attachment from 5/12/2003 email from Jake Vukich (DuPont) to Tyler Lane (Chemical Review Manager, Special Review and Reregistration Division, OPP, EPA) 77

### APPENDIX 8B. 

### PHYTOTOXICITY RESULTING FROM SPRAY DMFT DUIUNG A 

### MEDIUM APPLICATION RATE Aircraft

Aircraft

Setup 1
2
3 4 5
6
7
8
9
10
11
12
13
14
15 

### Setups for GPA
7
5
5 3 3
3 5
3
3
3 to 5

5
5
5
3
7.5 

### ApplicationBoomlength 65%
75%
75% 68% 70%
68%
68%
68%
68%
68%
67%
67%
67%
68%
60% 

### of Chlorsulfuron Products in Washington and Oregon Nozzle type
CP 30 deg plate
CP 30 deg plate
D-8 Lund multi-tip 8 CP 0 deg Lund multi-tip -8 Angle
0
0
0 0 0
0 Speed
90-110
110- 120
115 13

5 125-130
130
D-8 CP Straight Stream Spray SystemsD7 no core D8, 10, or 12
CP .171 15deg plate Dl0146
Dl0
CP solid stream, no plate CP solid stream, no plate 100-110
135
120-125
120
120
120
120
115
105-115 0,10

0
0
3 5
15
0
0
0
0 Aircraft
188Cessna
AirtractorAT 400 & 502 Thrush S2R-6 Turbine Thrush Super Doer Thrush 502 & 802 Air Tractor

- - - - Pressure
15psi

40 psi
40 psi


### ----

- - - - Agcat GI64 Super B Super Doer 1200 Wright 1820 Cessna Husky
Airtractor AT502 

### - turbine Agcat
Airtractor AT502 

### - turbine Airtractor AT502

- turbine Air tractor Turbo Agcat Assumed Variables
all orifices, 20-40psi, 90- 110mph all orifices,20-40psi, 110- 120mph DC46 core, 40 psi all orifices, 40 psi

20 psi

25 psi
30 psi

40 psi
22 psi Droplet spectrum (ASAE) Medium
Medium
Coarse Medium to coarse Medium to coarse Medium to coarse 40 psi
40 psi

DC46 core, 40 psi
used 5 

### " plate, 15not in model

DC46 core, 40 psi Coarse
Medium to coarse Medium
Medium
Medium
Medium to coarse Coarse
Coarse
Coarse

### Finesse product applications to preemergent wheat. The applicationranges from 0.0078 to 0.016 lbs ailacre. The mean of the high and low values was used for these graphs. Figure 

### 8B1. Predicted phytotoxicity levels(vegetative vigor) and associated downwind distances from an aerial 

### applicationconducted with a coarse 

### spray in a 10

### mph wind with a 10 foot release height at an 

### application rate of 0.012 lbs chlorsulfuronper acre.

Aerial: Coarse Spray

\

No-Spray Zone (ft)

### Figure 

### 8B2. Predicted phytotoxicity levels (vegetative vigor) and associated downwind distances from an aerialapplication conducted with a medium spray in a 10

### mph wind with a 10 

### foot release height at an applicationrate of 0.012 Ibs chlorsulfuron per acre.

Aerial: Medium Spray

No-Spray Zone (ft)

Percent Effect " 80 

## '7""'

### Figure 

### 8B3. Predicted phytotoxicity levels (vegetative vigor) and associated downwind distances fiom a 

### ground boom application conducted with a 

### medium/coarse spray in an approximate 10 mph wind with a 

### 2 foot release height at an application rate of 0.012 lbs chlorsulfuron per acre.

Ground: Low Boom, Medium-Coarse Spray

No-SprayZone (ft)

rbeet

### Figure 

### 8B4. Predicted phytotoxicity levels (vegetative vigor) and associated downwind distances from a ground boom 

### application conducted with a medium/coarse 

### spray in an approximate 10 mph wind with a 4 foot release height 

### at an application rate of 0.012 lbs chlorsulfuron per acre.

i~o-~pray Zone (ft) 

### Ground: 

### High Boom, Medium-Coarse Spray



### Effect i

### Figure 

### 8B5. Predicted phytotoxicity levels (vegetative vigor) and associated downwind distances from a ground boom 

### application conducted with a medium 

### spray in an 

### approximate 10 mph wind with a 

### 2 foot release height 

### at an 

### application rate of 0.012 lbs chlorsulfuronper acre.

No-Spray Zone (ft) Ground: Low Boom, Medium Spray

Effect YO

### Figure 8B6. Predicted phytotoxicity levels (vegetative vigor) and associated downwind distances from a ground boom 

### application conducted with 

### a medium 

### spray in 

### an approximate 

### 10mph wind with a 

### 4 foot release height 

### at an application rate of 0.012 

### lbs chlorsulfuron per acre.

No-SprayZone (ft) 

### Ground: High Boom, Medium Spray



### Effect 90 arbeet

### APPENDIX 8C. Chlorsulfuron Uses Areas and Relative Wind Speeds. Estimated agricultural usage of chlorsulfuron from the US Geological Survey (http:llca. 

### water.usgs.gov/pnsp/use92lchlrsulf. html) :

CHLORSU LFURON ESTIMATEDANNUAL AGRICULTURAL USE

0 No EstimetsdUss crow Taal o co.col ~ounas~mea ~50"1!= 

### w 0.001 - 0.003 Wheat and amns 55.312 898 95 56 

## zl? 166 1.17 0o.oim

### - eoqs - Q. a8

Wind speed data for three representative cities in areas where chlorsulfuron is used agriculturally. Graphs show 75&, 50th, and 2Sh percentile wind speeds for each month. Wind speed data is from SAMSON weather monitoring stations. Yakima, south central Washington:

>

### Pendleton, northwestern Oregon:

North Platte, central southwestern Nebraska:

### APPENDIX 

### 9. 

### TIER 1 DRINKING WATER ASSESSMENTMEMORANDUM

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON,D C 20460

OFFICE OF PREVENTION, PESTICIDES, AND TOXIC SUBSTANCES PC Code: 118601 DP Barcode: D266073

I MEMORANDUM June 25,2002 SUBJECT: Drinking Water Assessment to SupportTRED for Chlorsulfuron FROM: Lucy Shanaman, Chemist Environmental Risk Branch IV Environmental Fate and Effects Division I I THROUGH: R. David Jones, Senior Agronomist ~nvironmenial Risk Branch IV Environmental Fate and Effects Division Betsy Behl, Chief Environmental Risk Branch IV Environmental Fate and Effects Division TO: Jim Tompkins, Product Manager 25 Herbicide Branch, Registration Division This memo presents the Tier I Drinking Water Assessmentfor the parent compound, chlorsulfuron, calculated using FIRST (surface water; version 1.0, 8/1/01) and SCIGROW (groundwater; version 1 .O, 11/12/97)for use in the human health risk assessment. This assessment does not encompass degradation products of chlorsulfuron. For drinking water derived fiom surface water sources, the acute (peak) value is 46.8 ug/L (ppb),and the chronic (average annual) value is 16.4 ug/L (ppb),for non-crop, non-residential turf. The groundwater screening concentrations for both acute and chronic exposure values are 3.5 ug4 (ppb)for non-crop, non-residential turf. These concentrations were predicted from maximum label use information. The reported values representupper-bound estimates of the concentrations that might be found in locations vulnerable to pesticide contamination, for either surface water used for drinking water, or in groundwater, due to the use of chlorsulfuron on non-residential turf. Modeling was also done using label information for application to wheat crops. Should the results of this assessment indicate a need for further refinement, or if any degradation products become oftoxicologicalconcern, please contact us as soon as possible so that we may schedule a Tier I1 assessment. A more conservative estimate which included the degradation products, assuming both stability and mobility equal to the parent compound, was also made. Table 1. Modeling Results Based on Low Pressure Ground Spray Application of ChlorsulfuronModel Concentration From Use on Concentration From Use on Wheat Non-Residential Turf
FIRST SurfaceWater Peak Day (Acute) 1.6ppb FIRST SurfaceWater Annual Average (Chronic) 0.55ppb 16.4 ppb SCIGROW Ground Water (Acute and Chronic) Value 0 16 ppb 3.5 ppb Monitoring Data: Chlorsulfuronwas not an analyte in the USGS, NAWQA monitoring program. Pesticides in Groundwater Database, A Compilation Of MonitoringStudies: 1971-1991National Summav, US EPA September 1992, entries indicate that of eightwells tested, there were no recorded detections of chlorsulfuron. An article from the open literature examining streams, reservoir outflows, and wells in the Midwestern United States3 indicates that chlorsulfuron was detected in 5 %, or fewer, ofthe 7 1 streams tested, only detected in one of the outflow samples fi-omthe five reservoirs, and was not detected in groundwater samples collected from 25 wells. Maximum concentrations, measured using high performance liquid chromatography in tandem with mass spectroscopy (HPLC-MS), were less than one pgL (ppb). The. estimated reporting limit (MRL) was 0.010 pgL. Environmental Fate: Chlorsulforon is expected to be very mobile in the environment. Laboratory data (soil thin layer chromatography)indicates that the degradation product sulfonamide is less mobile than chlorsulfuron, and that triazine amine is less mobile than both the parent compound, chlorsulfuron, and the degradation product, sulfonamide. However, a precise estimate ofthe specific degree ofmobility which can be attributed to either of these degradation products is undetermined. Laboratory studies indicate that chlorsulfuron is not expected to be highly persistent in the environment. With some exceptions, reported concentrations of degradation products peaked at study termination. Triazine atnine concentrations were reported to peak relatively early in aerobic soilmetabolism studies, transforming intohydroxy triazine amine with concentrations increasing steadily throughoutthe study. Drinking Water TreatmentEffects: Primary water treatment is not expected to remove chlorsulfuron fi-omdrinking water. The predicted high mobility of chlorsulfuron means that it is not expected to sorb appreciably to soil andfor sediment, indicating that it would not be expected to be removed fiom drinking water by either sedimentation or flocculation. Additionally, water treatment processes are more likely to raise the pH during treatment, therefore, hydrolysis is not expected to be a primary I degradation pathway. Background Information on FIRST: FIRST4is a screening model designed by the Office of Pesticide Programs to estimate the concentrations found , I in drinking water eom surface water sources for use in human health risk assessment. As such, it provides upper bound values on the concentrations that might be found in drinking water due to the use of a pesticide. It was designed to be simple to use and to only require data which is typically available early in the pesticide registration process. FIRST is a

3Concentrationofselected Sulfonylurea, Sulfonamide, and Imzdazolinone Herbicides, Other Pesticides, andNutrients in 71Streams, 5 Reservoir Out$ows, and 25 Wells in the Midwestern United States, 1998;Battaglin WA, Furlong ET, Burkhardt MR, U.S. Department of the Interior, U.S. Geological Survey, Water-Resources Investigations Report 00-4225, Denver, Colorado; 2001.single event model (one runoff event), but can account for spray drift from multiple applications. FIRST is hardwired to represent the Index Reservoir, a standardwater body used by the Office of Pesticide Programs to assess drinkingwater exposure (Hetrick et al, 1998). It is based on a real reservoir in Illinoisthat is known to vulnerable to pesticide contamination. The single runoff event moves a maximum of 8% ofthe applied pesticide into the pond. This amount can be reduced due to degradation on the field and the effects ofbinding to soil in the field. BackgroundInformation on SCIGRO W: SCIGROW5(version 1.0,November 12, 1997) provides a Tier 1, groundwater screening exposure value to be used in determining the potential risk to human health from drinkingwater contaminated with the pesticide. SCIGROW estimates likely groundwater concentrations if the pesticide is used at the maximum allowable rate in areas where groundwater is vulnerableto contamination. In most cases, a large majority of the use area will have groundwater that is less vulnerableto contamination than the areas used to drive the SCIGROW estimate. Modeling Inputs andResults: A conservative estimate of surface water EEC's and drinking water concentrations were made which would included any possible degradation products. While laboratory data did indicate that some of the degradation products were less mobile than the parent, the results were unquantified. A conservativeestimate of degradate mobility equal to that of the parent compound, chlorsulfuron, was made. In the absence of any quantified biotic or abiotic degradation date for the transformation products, which generally reached the reported maximum at study termination, complete stability was assumed for both parent and the degradates. This assumption assured that both the parent compound and the degradation products would be included in the estimated surfacewater concentrations. The modeling results .from FIRST, using these assumed parameters, estimatespre-treatment surface water concentrations oftotal chbrsulfuron residues (both parent and degradationproducts),resulting from two applications, at 60 day intervals,ofthe maximum use rate of LESCO TFC Dispersible Granule Turf Herbicide, at an acute (peak) value of 59.7 ug/L (ppb), and a chronic (average annual) value of 41.3 ug/L (ppb). Please note that these values for parent, and any possible degradation products, are more conservative,and replace the values which were included in the FQPA memo. The values reported at the beginning ofthis memo are for parent only, as Health Effects Division has indicatedthat only the parent compound is oftoxicological concern. Table 2 and Table 3 summarize the general input values used in the model runs for FIRST and SCIGROW for chlorsulfuron, applied two times by low pressure ground spray and incorporated to a depth of 3 to 4 inches for wheat crops, at a rate of 0.0156 pounds of active ingredient per acre for wheat crops and 0.333 pounds of active ingredientper acre for non-crop, non-residential turf. Labeled non-crop, non-residential turf uses include industrialturf grass areas such as: airports, military installations,fence rows, roadsides, right-of-ways, lumberyards, tank farms, pipeline and utility right-of-ways, pumping installations, railroads, storage areas, plant sites, and other similar areas. Input parameter values were selected in accordance with US EPA OPP EFED water model parameter selection guidelines, Guidance for Selecting Input Parameters inModeling the Environmental Fate and Transport ofpesticides, Version 11, February 28, 20026. In the absence of anaerobicmetabolism data, that value was multiplied by two, as outlined in the guidelines, to generate an anaerobic metabolism half-life of 160 days. Application rates were obtained fiom submitted labels. FIRST predicted surface water acute peak concentrationsof 1.6ppb for wheat and 46.8 ppb for non-residential turf. Chronic (average annual) concentrationswere 0.55 ppb for wheat and 16.4ppb for non-residentialturf. SCIGROW predicted groundwater concentration s of 0.16ppb for wheat and 3.5 ppb for non-residential turf. Modeling results appear in Table 2 and Table 3. FIRST and SCIGROW output files have been appended to this document.Table 2. Input Parameters for FIRST
Parameter Wheat Crops Non-Residential Turf Chemical chlorsulfuron chlorsulfuron Water Solubility (pH 7; 25 OC) 3 1,800ma Hydrolysis Half-Life (pH7) stable Aerobic Soil Metabolism Half-Life 80 days 31,800 mg/L stable 80 days Aerobic Aquatic Metabolism Half-Life 160 days (2 x aerobic soil half-life) 160 days (2 x aerobic soil half-life) Photolysis Half-Life stable stable Organic Carbon Adsorption Coefficient 21 Lkg 2 1L/kg (Koc) Application Method ground spray, incorporate 3 inches low pressure ground spray Application Rate 0.0156 lbs. a.i./acre 0.33 lbs. a.i./acre ApplicationFrequency 2 per year 2 per year Interval Between Applications 30 days 60 days
Table 3. Input Parameters for SCIGROW

Parameter Wheat Crops 'Chemical chlorsulfuron chlorsulfuron Organic Carbon Adsorption Coefficient (KOc) 2 1 L/kg 2 1 Lkg Aerobic Soil Metabolism Half-Life 80 days 80 days Application Rate 0.0156 lbs. a.i./acre 0.333 lbs. ailacre ApplicationFrequency 2 per year 2 per year

APPENDIX I FIRST SURFACE WATER MODELING RESULTS FOR CHLORSULFURON OUTPUT TABLES FOR CHLORSULFURONONWHEAT
RUN No. 1 FOR CHLORSULFURON ON WHEAT 

### * INPUT VALUES *

....................................................................

RATE (#/AC) No.APPS & SOIL SOLUBIL APPL TYPE %CROPPED INCORP

ONE (MULT ) INTERVAL Koc (PPM ) (%DRIFT) AREA (IN)FIELD AND RESERVOIR HALFLIFE VALUES (DAYS)

.................................................................... METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINED (FIELD) RAIN/RUNOFF (RESERVOIR) (RES.-EFF) (RESER.) (RESER.)

.................................................................... 80.00 2 N/A .OO- .OO 160.00 160.00
UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.0 AUG 1, 2001
PEAK DAY (ACUTE) ANNUAL AVERAGE (CHRONIC) CONCENTRATION CONCENTRATION

.................................................................... 1.566 .550 FIRST SURFACEWATER MODELING RESULTS FOR CHLORSULFURON OUTPUT TABLES FOR CHLORSULFURON ON NON-RESIDENTIALTURF
RUN No. 2 FOR CHLORSULFURON ON NON RESIDE - * INPUT VALUES *

....................................................................

RATE (#/AC) No.APPS & SOIL SOLUBIL APPL TYPE %CROPPED INCORP

ONE (MULT) INTERVAL Koc (PPM ) (%DRIFT) AREA (IN)

.................................................................... .333 ( .531) 2 60 21.031800.0 GROUND( 6.4) 87.0 .o FIELD AND RESERVOIR HALFLIFE VALUES (DAYS)

.................................................................... METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINED (FIELD) RAIN/RUNOFF (RESERVOIR) (RES.-EFF) (RESER.) (RESER.)

.................................................................... 80.00 2 N /A .OO- .OO 160.00 160.00
UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.0 AUG 1, 2001

.................................................................... PEAK DAY (ACUTE ) ANNUAL AVERAGE (CHRONIC) CONCENTRATION CONCENTRATION

.................................................................... 46.811 16.446 FIRST SURFACEWATER MODELING RESULTS FOR CHLORSULFURONAND DEGRADATION PRODUCTS OUTPUT TABLES FOR BOTH CHLORSULFURONAND DEGRADATE RESIDUES ON NON-RESIDENTIALTURF
RUN No. 1 FOR chlorsulfuron and degradates ON industrial turf * INPUT VALUES 

### *

....................................................................

RATE (#/AC) No.APPS & SOIL SOLUBIL APPL TYPE %CROPPED INCORP

ONE (MULT) INTERVAL Koc (PPM ) (%DRIFT) AREA (IN)

FIELD AND RESERVOIR HALFLIFE VALUES (DAYS)

.................................................................... METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINED (FIELD) RAIN/RUNOFF (RESERVOIR) (RES

### .-EFF) (RESER. ) (RESER. )

....................................................................UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.0 AUG 1, 2001

- .................................................................... PEAK DAY (ACUTE) ANNUAL AVERAGE (CHRONIC) CONCENTRAT I ON CONCENTRATION

.................................................................... 59.566 41.344
APPENDIX I1 SCIGROW GROUND WATER MODELING RESULTS FOR CHLORSULFURON

OUTPUT TABLES FOR CHLORSULFURONON NON-RESIDENTIAL TURF
RUN No. 1 FOR chlorsulfuron INPUT VALUES -____---_--_--------------------------------------------------------

APPL (#/AC) APPL. URATE SOIL SOIL AEROBIC RATE NO. (#/AC/YR) KOC METABOLISM (DAYS)

.................................................................... .016 2 .031 21.0 80.0
GROUND-WATER SCREENING CONCENTRATIONS IN PPB

........................................................ .I62135

........................................................ A= 75.000 B= 26.000 C= 1.875 D= 1.415 RILP= 4.847 F= .716 G= 5.197 URATE= .031 GWSC= .I62135

SCIGROW GROUND WATER MODELING RESULTS FOR CHLORSULFURON

OUTPUT TABLES FOR CHLORSULFURONON NON-RESIDENTIAL TURF
RUN No. 2 FOR chlorsulfuron INPUT VALUES

APPL (#/AC) APPL. URATE SOIL SOIL AEROBIC RATE NO. (#/AC/YR) KOC METABOLISM (DAYS)

.................................................................... .333 2 .666 21.0 80.0
GROUND-WATER SCREENING CONCENTRATIONS IN PPB

........................................................ 3.460952

........................................................ A= 75.000 B= 26.000 C= 1.875 D= 1.415 RILP= 4.847