UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

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. 

Text Searchable File
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 Protection Agency 

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 assistance in 

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 Recommendations to 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 

EndangeredIThreatened Species ........................................... 46 

REFERENCES .............................................................. 47 

APPENDIX 1 . PRZMIEXAMS INPUT 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 CONCENTRATIONS ON AVIAN AND 

MAMMALIAN FOOD ITEMS (PPM) FOLLOWING A SINGLE APPLICATION AT 1 

lbai/A ................................................................ 70 

APPENDIX 5 NON-TARGET TERRESTRIAL PLANT 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 CALCULATIONS FOR SURFACE AND GROUNDWATER 

IRRIGATION ......................................................... 73 

........ . APPENDIX 8 . REFINED SPRAY DRIFT ANALYSIS FOR CHLORSULFURON 74 

APPENDIX 9 . TIER 1 DRINKING WATER ASSESSMENT MEMORANDUM ........ 84 
EXECUTIVE SUMMARY 

Chlorsulfuron Usage 

Chlorsulfuron is a broad spectrum, pre-emergent andpost-emergent sulfonylurea 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~timated exposure 

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 concern for 

nontarget terrestrial and aquatic plants are exceeded by orders of magnitude. 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 of drift 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 (plant dependant) for some important aspect of their life 

cycle, given the current extent of analysis of exposure, effects and co-occurrence of listed resources 

and areas of use. The extent to which the use of chlorsulfuron on wheat andpasture/rhngeland will 

indirectly effect listed animal species will require identlJication 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, given the level of refinement of this analysis we 

cannot preclude the possibility of a '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 

chlorsulfuron have not been estimatedquantitatively in this riskassessment, riskquotients for direct 

application to plants are expected to be higher than those estimated for indirect exposure through 

runoffand/or drift. 

Toxicity and Risk to Non-target and Endangered Plants 

Screening level (Tier 1) deterministic risk quotients (RQs) for direct effects to endangered 

plants exceed the endangered species level of concern (LOC) by several orders of magnitude. For 

aquatic plants, RQs for endangered species range from 18 to 31. The range of RQs for endangered 
plants in wetlands was 122 to 693. RQs for endangered terrestrialplants rangefrom 21 for ground 

application to small grains to 580JFom spray drift resultingfrom aerial applications to rangeland 

A refinedspray drift assessment has been performed to better characterize the potential risk to nontarget 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 of effect levels (EC,, to EC,d for all the plants 

tested that might occur from exposure to spray drift only. This assessment 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 that while 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 of this analysis 

of exposure, effects and co-occurrence of listed resources and areas of use. 

1. PROBLEM FORMULATION 

Chlorsulfuron is.a broad 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's the 

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 the reregistration 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,orsulfuron by integrating both registrant-submitted guideline data and 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 explicit expressions of the actual environmental value that 

is to be protects and for the purposes of this ecological risk assessment are operationally defined by 

an ecological entity and its attribute. The assessment endpoints of this ecological risk assessment 

include terrestrial and aquatic animal and plant mortality following acute exposure to chlorsulfuron 
and terrestrial and aquatic animal reproduction, growth and survival effects from chronic exposure I to chlorsulfuron. The valued entities are terrestrial and aquatic vertebrates and invertebrates, aquatic 

vascular and nonvascular plants, and terrestrial plants. 

The attributes used 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 

toxicity endpoints are used fiom surrogate test 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. These tests include short-term acute, subacute and reproduction studies and 

are typically arranged in a hierarchical or tiered system which progresses fiom 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 statements to minimize the potential adverse effects to non-target animals and plants (CFR 40 

5 158.202,2002). 

1.2.2 Measures of Exposure 

The risk assessment process considers formulations used 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 does it account for ingestion of chlorsulfwon residues by 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 for this 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 surrogate test species to estimate treatment-related direct effects on 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 Statements to 

minimize the potential adverse effects to nontarget animals and plants (CFR 40 §158.202,2002). 

1.3 Conceptual Model 
The 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 of current 

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 

growing on adjacent land if it is applied to crop land and inadvertently drifts andlor runs off into 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 of the 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 enzyme in the biosynthesis of branched-chain amino acids (valine, 

leucine and isoleucine). ALS inhibition in plants adversely affects plant growth and reproduction. 

This enzyme pathway does not exist in animals; therefore, the herbicide is less toxic to animals than 

plants. 

2.2 Use Characterization and Formulations 

Chlorsulfuron-containing products were first registered in the United States in the early 1980s. There 

are six products currently registered for use in the U.S. These include: TELARB DF, GLEANB FC, 

FINES SEB, 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 vast majority of chlorsulfuron is applied to winter wheat. The remaining uses 

are primarily spring wheat and oats. Little data exist on the recently approved pasture and rangeland 

uses. Registered applications with little or no current usage include lawn and ornamental turf. The 

non-crop land and industrial turf sites includes use on roadsides, railroads, industrial sites, rights of 

way, airports, fence rows, and lumberyards for control of noxious weeds. For cereal grains, the 

greatest chlorsulfuron usage is in Kansas, followed by Oklahoma, Montana, Washington, Texas, 

Nebraska, North Dakota, and California. For the non-crop market, the greatest usage is in Iowa, 

followed by Washington, Oregon, Colorado, Idaho, Minnesota, Mississippi and Nebraska. 

2.3 Rate and Method of Application 

For the cereal use, there is only one application per season, with the typical 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% 

of the turf acres treated with chlorsulfuron. Non-crop acres treated for the purposes of general weed 

control or bare ground maintenance receive only one application per year. A single yplication in 

non-crop situations in the Western United States is generally made inNovember to March/April time 

frame. In the West, environmental conditions and weed pressure may necessitate a second 

application. In the South, multiple applications (2-3) are common during a calendar ye$ at >3 month 

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 0.023 lbs 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 12 month 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-month period 
Non-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 

ailacre per year 

2.4 Current Label Restrictions 

Current chlorulfuron labels contain a number of restrictions that may tend to mitigate to some degree 

the potential impacts of chlorsulfuron on non-target and endangered plant species. For example, 

statements on the FinesseQ label (EPA Reg. No. 352-445) indicate that "Finessem herbicide is 

recommended for use on land primarily dedicated to the long-term production of wheat and barley". 

This recommendation may serve to decrease the likelihood that irrigation water contaminated with 

chlorsulfuron will be inadvertently applied to agricultural crops that are sensitive to chlorsulfuron. 

FinesseQ labels provide the following precaution: "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 

applied to fields to which certain other insecticides have been applied. The FinesseQ label states that 

"FinesseQ should not be used within 60 days of crop emergence if an organophosphate insecticide 

(such as "Di SystonQ") was used as an in-furrow treatment, or crop injury may result." Presumably, 

neither of these two pesticides if used alone will cause crop injury to wheat or barley. However, the 

Finessem label indicates that they apparently do 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 plus AssertQ may cause temporary crop discoloration/stunting or injury when heavy rainfall 

occurs shortly after application". Additionally, the label restricts the use of Finessem 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, the FinesseQ label includes the following statement "Do not apply FinesseQ during the boot 

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 areas near 

sensitive crops, use solid-stream nozzles oriented straight back. Adjust swath to avoid spray drift 
damage 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 chlorsulfuron under 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 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". The extent to which this statement serves to decrease the movement of Chlorsulfuron 

contaminated soils into nearby fields in which non-cereal crops are grown is uncertain. 

Several labels have restrictions based on soil pH. Primarily these restrictions are to protect replanted 

crops after chlorsulfuron application. 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 replantings may suffer the effects of residual chlorsulfuron. In certain states these 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 of the chlorsulfuron labels 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 represent the use sites with the largest 

amount of current or potential chlorsulfuron use. However, some of the non-crop uses have higher 

application rates than the crop uses. If risk quotients were to be calculated for the chlorsulfuron noncrop uses with the higher application rates, they would likely result in higher risk estimates than were 

calculated for the crop uses. 
3.0 ENVIRONMENTAL FATE 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 

appears to be the most significant mechanism for degradation of chlorsulfuron, 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 14 tb 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 concentrations were 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 421 567-02). 

3.1.3 Soil Photodegradation 
Soil 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] 19.6 meq/100g, pH 8). Minor degradates were observed at less than 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 of pH 6.4), chlorsulfuron had a half-life of 14 days. 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 (MRID 0 1 13-00 13 and 0 1 13-0024), chlorsulfuron half-lives were 

1 to 2 months. In more recent publications, Andersen et al. (2001) reported chlorsulfuron half-lives 

of 50 days for soil taken from 30 to 35 cm below surface, 160 days for soil taken 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, and 2-chloro-N- 

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

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 

system it was 182 days and only 10 1 days for the sterile system. Increased hydrolysis via lower pH 

changes upon heat sterilization were attributed to these counterintuitive results. 

3.1.6 Bioaccumulation 

Preliminary fish bioaccumulation studies (MRID 422 142-04) showed channel catfish accumulation 

factors of 1.5X in edible tissue, 12X in viscera, and 7X in liver. Residues declined by 90-95% 

during the depuration phase. In preliminary bluegill sunfish studies the bioaccumulation was 4X in 

the viscera, 6X in the 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 the 
field lysimeter studies (MRID 422142-02), estimated half-life ranged from 20 days to several 

months. MRID 422142-02 is a compilation of several studies identified by the registrant-assigned 

report numbers in parenthesis that follow. Lysimeter studies in Delaware, North Dakota, and 

Nebraska (Report No. 63-82) were conducted on both an alkaline and an acidic soil. For the acidic 

soils the dissipation half-life ranged fiom 1 to 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 Spring in Alberta, Manitoba and Siiskatchewan, 

Canada. Dissipation half-lives were reported to be 1 to 3 months for the Spring studies and 5 to 11 

months for the Fall studies. Leaching of chlorsulfuron was apparent. The time.for detectable levels 

of chlorsulhron to reach 22 - 35 cm ranged from 1 to 40 months. In another lysimeter Study (Report 

No. AMR 1417-89) leaching was also apparent down to the 18-24 inch range. The reported 

dissipation half-life was 20 days. In all the studies, only minor amounts (4 0%) of two 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 anionic with 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 3 5 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 1 mgL. 

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, with pH in the bioaccumulation section). Chlorsulfuron is also persistent, and its persistence 

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 12 water samples were 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 is unclear to what extent the locations of sampling sites overlap with areas 

where chlorsulfuron is applied. Because of limitations in the monitoring data, estimated 

environmental concentrations in this assessment were calculated solely fiom the Pesticide Root Zone 

Model coupled with the Exposure Analysis Model System (PRZMIEXAMS) and SCI-GROW model 

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 over the simulation period and chronic and peak concentrations 

are nearly the same for all scenarios tested. 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 .may accumulate over time to a higher 

degree than would a pond with flow into and out of the 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 Chlorsulfuron Used for PRZMIEXAMS Modeling I I 

Solubility 

Vapor Pressure 

Parameter 

Molecular Weight 

3 1800 mgll 

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 aquatic halflife 

320 days 

Photodegradation 

90% ci from submitted studies (half life data : 14, 

330, 60 days) 

Anaerobic metabolism 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 Drinking Water 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. Concentrations of chlorsulfuron in drinking water sources for the 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 for the ecological assessments, the application date chosen was 

the date that gave the highest exposure values at reasonable application dates as determined from the 

'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 of pesticides. For further information on this model see the 

EFED water model website at http:l/www.epa.govloppefedl/models/water/. The following model 

inputs were used: application rate = 0.0625 lblacre, on application per 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 1.6 pa 
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 

assessment of risk or hazard makes the assumption that avian and reptilian 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 female body weight, 14 day 

old survivors/normal hatchlings, viable embryosleggs set, and 14 day hatchling survivalleggs set 

(NOEC = 174 mglkg diet/day). A toxicity endpoint for chronic mammalian toxicity is not available. 

Chlorsulfuron is also practically nontoxic to honeybees on an acute contact basis. Table 7a provides 

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-eshwater and estuarinelrnarine fish on an acute 

exposure basis and is slightly toxic to estuarinelmarine invertebrates. Chronic exposure of 

rainbow trout (Oncorhynchus mykiss) to chlorsulfuron resulted in a NOEC of 32 mg/L while a 

chronic study of waterfleas (Daphnia magna) resulted in a NOEC of 20 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 

Anas platyrhynchos 

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

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) .......................................................... 

25 pglbee -- . -- 9 -- 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. 

Rainbow trout i Practically Nontoxic Oncorhynchus mykiss >250 j -- 000352-59 419764-05 

(formulated product) ....................... A .................................................... 

Acute Toxicity 

Water flea i Practically Nontoxic 1 -- 1 I i >370 i Daphnia magna 000352-62 ........................................... ........................................................................................ .............................. 4 ....................................... 

419764-08 

Chronic Toxicity 

I Sheepshead minnow i Practically Nontoxic 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. 

Chlorsulfuron is toxic to nontarget terrestrial plants with EC2, values as low as 1.0 x 10-,1bs a.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 curve for chlorsulfuron varies between species, suggesting a 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 Slightly Toxic 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" 

*shoot length 

4.4 Aquatic Plants 

Aquatic plant toxicity ranged f?om practically nontoxic to very highly toxic. Duckweed (Lemna 

gibba) was the most sensitive vascular aquatic plant, with an EC,, of 3.5 x 1 mg ai/L and a NOEC 

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 0000095 mgL 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 = 0.236 mgL 458329-03 Core 

(97.8%) EC50 = 0.609 mgL R.L.Boeri et al. 

(2001) 

Aquatic plant growth Lemna gzbba NOEC = 0.00024 mg/L 458329-01 Supplemental' 

(97.8 %) EC,, = 0.00035 mg/L R.L.Boeri et al. 

11 Thls study was 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 toxicity testing. 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 chlorsulfuron toxicity to 48 

plant species in 38 genera and 14 families. Monocotyledonous plants included nine genera and 11 

species in the Poaceae (grass family) and one species in the Liliaceae (lily family), while 

dicotyledonous plants were represented in 12 families, 27 genera and 39 species. 

Khodayari et al. (1 985) found that wild garlic (Allium vineale; Liliaceae) suffered 2 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 

rates up 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 

equivalent to 0.0045 lbs a.i./A (Rubin and Casida, 1985), ryegrass (Lolium rigida) 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 0.001 8 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 sensitive to chlorsulfuron application than monocots, 

with the possible exception of the 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 of 0.008 1bs a.i./A 

(Ivany, 1987; Klingaman and Peeper, 1988) and two related species, garden sorrel (Rumex 

acetosella) and curly dock (Rumex crispus) seedlings had mortality of 30% and 93% at rites of 0.008 

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 in biomass at 0.00005 lbs a.i./A 

(Saari et al., 1990). In the legume family (Fabaceae), winter vetch seedlings averaged 6$% mortality 

at a rate of 0.0 16 lbs a.i./A (Khodayari et al., 1985). Similar results are reported for the other species 

in the ECOTOX database. 

4.5.1 Fletcher et aL, 1995 

I 

The influence of chlorsulfuron on the reproduction of green pea (Pisum sativum) was examined by 

exposing plants at three different stages of development to three different exposure levels. The most 

susceptible stage of development was when plants possessed six expanded leaves and one visible 

flower bud. At that stage an application rate of 0.00016 lbs ai/A reduced yield of treated plants by 

99% compared to control plants without appreciably altering height or appearance of mature plants. 

1 When corresponding low application rates of atrazine, glyphosate, and 2,4-D were administered at 

the same development stage there were no effects on either growth or reproduction. Thus 

chlorsulfuron had 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 the non-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 compared to control plants. 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 atrazine for 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. Several of the fields studies below were conducted by researchers fiom 

the EPA laboratory in Corvalis, OR and one of the non-target plant incidents (at Horse Heaven Hills) 

was investigated by a researcher from the same EPA laboratory. 

Several researchers have concluded that these studies indicate that small quantities of chlorsulfuron 

change plant reproduction without altering vegetative growth. If the effect of chlorsulfuron on cherry 

trees is characteristic of other plant species, spray drift may severely reduce both the crop yields and 

fruit development on plants, the keystone component of the habitat and food web for wildlife. Plant 

reproductive processes may be more sensitive to chlorsulfuron than growth effects. Low levels of 

chlorsulfuron appear to 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 chlorsulfuron were administered until wetness with a dual nozzle spray wand at five 

concentrations representing 0,111 OOOth, 1/500th, 111 OOfh, and 111 Oth of the recommended tank mixture 

rate of chlor&lfuron for use on small grain crops in Washington, Oregon, and California. Three 

multiple applications experiments 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 100 times 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 cherry tree occurred from the 

use of 1/500th the maximum label rate for chlorsulfuron herbicide. 

Bhatti et al., 1995 
Field experiments were conducted at the Irrigated Agricultural Research and Extension Center, 

Prosser, WA in 1992 and 1993 to study the effects of low concentrations of chlorsulfuron by treating 

branches of three cherry (Prunus avium) cultivars at different growth stages. In single exposure 

experiments, the yield and quality of fruit 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, fruit yield, 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 full bloom and post 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. (1 993), 

in that the toxicity of chlorsulfuron to cherries was 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 affected by exposure to chlorsulfuron at concentrations substantially lower than 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 et al., 1996). Exposure ranged from 1 x 1 0-3 to 8 x 1 0-3 of the 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 of reduction depending on the 

time and rate of application. For canola and soybean, applications of 8.0 x 1 0-l1 and 1.6 x 1 0-lo lbs 

aiIA, respectively, reduced seed yields by 92 and 99% compared to controls without causing 

significant changes in vegetative growth. These low application rates suggest that chlorsulfuron may 

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 soybean were 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 of these incidents 

(I0 13 884-0 12) occurred in June 1998 in Benton County, WA, where an orchard bound on three sides 

by 'dry land' 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 

contamination by chlorsulfuron near Walla Walla, WA. Also in 1997, leaf spots in cherry and apple 

orchards in Douglas County, WA were reported (I0 13 883-003). Chlorsulfuron and 2,4-D were used 

on nearby wheat fields and the spots were thought by 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 1977 and was reported 

to the Agency in 1992. Peach trees in a Benton, WA orchard were severely damaged and cherry and 

prune trees were damaged to a lesser degree (pear trees were unaffected). It was determined that the 

damage was "definitely due" to chlorsulfuron, which had been applied to 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 suggests that the acch-ate date 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 involving peaches; however, as the Department routinkly discards 

records after seven years, no known records from that time exist. 

The Horse Heaven Hills lawsuits are 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 chlorsulfuron in 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,,) greater than 5,000 pprn and relatively low 

EECs, based on 240 pprn per lb ai applied (Appendix 4) chlorsulfuron is not expected to pose an 

acute risk to avian species. The NOEC for avian reproduction (1 74 mglkglday) is more than an order 

of magnitude above the highest EEC. Because of low acute toxicity to laboratory rats, risk quotients 

do not exceed the LOCs for mammals. Therefore, chronic risks to birds are not expected to 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 = 174 ppm 

1.9 - 15 pprn <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 chronic risk quotients do not exceed the LOC for freshwater or marinelestuarine fish and 

invertebrates (Table 11). With acute toxicity values (LC,,) greater than 50 pprn and EECs less than 

0.010 ppm, chlorsulfuron is not expected to pose an acute risk to aquatic animal species. Chronic 

toxicity tests result in NOECs that are greater than 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 ppb 
Marine invertebrate Acute LC,, = 89 ppm 

Chronic NOEC = 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 quotients for non-target and endangeredlthreatened aquatic 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 of Concern (RQ2 1 .O) for non-target plants is exceeded in all modeled scenarios. 

At current maximum application rates used on wheat, non-target aquatic plant 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 

aquatic plants. 

Table 12. Chlorsulfuron Risk Quotients (RQs) for Non-target and Endangered1 Threatened Aquatic 

Plants Using a EC,, of 0.35 pg/L and a NOEC of 0.24 pg/L for Lemna 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 of the following four scenarios: 

1) Off-target drift and runoff of chlorsulfuron fiom a ten acre application site to an adjacent one 

acre semi-aquatic area (wetland) using seedling emergence toxicity 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 site to an adjacent one 

acre terrestrial area using seedling emergence toxicity 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 vegetative vigor toxicity data to calculate risk quotients (Table 16), based 

on a single irrigation event. 

Screening level RQs for semi-aquatic areas (wetlands) resulting fiom off-target drift (concentrations 

estimated at the edge of the treated field) and runoff of chlorsulfuron fiom the application site (ten 

acres to one acre) we presented in Table 13. The toxicity endpoint used 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 103 for non-target plants and fiom 177 to 693 for endangeredlthreatened 

plants. RQs for aerial application to small grains, pasture and rangeland range fiom 18 to 7 1 for nontarget plants and fiom 122 to 476 for endangeredlthreatened plants. Since the LOC) is exceeded, 

At the current maximum application rate of chlorsulfuron to small grains, rangeland and pasture 

greatly, level of concerns (RQ2 1 .O) are exceeded for non-target and endangeredlthreptened plants 

found in semi-aquatic areas (wetlands). The highest calculated RQs are from industrial applications. 

Direct exposure scenarios were not calculated, but RQs for plants and endangered plants 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 3 8 255 26 175 

Oats (post-emergent) 0 016 0 00816 0.0056 26 177 18 122 

Wheat (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 3 8 255 NIA NIA 
Non-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 1 NOEC 

51 RQ = EEC for aerial applicat~on / EC,, 

61 RQ = EEC for aerial application 1 NOEC 

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 endpoints from the 

seedling emergence study and assumes one acre to one acre runoff. 

RQs for ground application of chlorsulfuron to 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 

application to small grains, pasture and rangeland range fiom 4 to 16 for non-target plants and from I 

I 28 to 109 for endangeredlthreatened plants. 

RQs for non-target plants range fiom 3 to 16 for small grains, rangeland and pasture. For 

endangered plants they 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 chlorsulfuron were 

greater than for ground application. RQs for non-target plants range from 16 to 63 for ground 

applications to 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 148 to 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 

assumes no runoff), the risk quotients for aerial applications are higher than for ground applications. 
Table 14. Chlorsulfuron Risk Quotients (RQs) for Non-Target and Endangered Terrestrial Plants Using 

(Seedling Emergence) an EC,, of 3.1 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 / NOEC 
Table 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 aerial appl.' 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 16x lo4 8.0~ 10." 16 30 80 148 

Unimproved turf 0.012 1.2 x 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 1 EC25 

41 RQ = EEC for ground appllcatlon I NOEC 

51 RQ = EEC for aerlal appllcatlon 1 EC25 

61 RQ = EEC for aerlal appl~catlon INOEC 

Risk quotients were also calculated to evaluate the potential risk to plants if exposed to irrigation 

water containing chlorsulfuron. Modeled estimates suggest that irrigation water from groundwater 

and surface water sources may contain high enough chlorsulfuron concentrations to 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% of the irrigation water drifts into adjacent wetlands. It was assumed that no 

run off of irrigation water occurs (Appendix 7). The RQs for non-target plants range from 2.0 for 

irrigation using groundwater to 7.0 when using surface water. For endangered plants fpund in areas 

adjacent to irrigated fields RQs range 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 species LOCs 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 sensitive agricultural crops such as 

soybeans, sugarbeets, onions, etc. (Appendix 6) if they are grown in fields that are irrigated with 

water containing chlorsulfuron. Risk quotients for sensitive crops within irrigated fields range from 

36 for irrigation using groundwater to 136 for using surface water to irrigate fields. In regions where 

chlorsulfuron has been used historically, agricultural crops grown in fields irrigated with 

groundwater or swface water containing chlorsulfuron could possibly be adversely affected. For this 

assessment it was assumed that there are no endangered plants 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 Chlorsulfuron in Groundwater or 

6.0 ppb in Surface Water (using the vegetative vigor EC,, of 1.0 x 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 adjacent to irrigated Surface water: 6 8 x 10" SW. 7 SW. 13 

fields 

Within the imgated Groundwater 3.6 x 1 0-4 GW: 36 NIA5 

field4 Surface water. 1 4 x 1 O5 SW: 136 

" Estimated Environmental Concentrat~on assuming 1 inch of irrigation water is applied to the target field '' Non-target plants in areas adjacent to the irrigated field or sensitive agricultural crops within the irrigated field 

27 
31 Assumes 5% drift of irrigation water containing chlorsulfuron and no runoff of irrigation water 

" Irrigation water applied directly to agricultural crops that may be sensitive to chlorsulfuron 

51 It is assumed that there are no endangered plants within agricultural fields that are migated 

5.2 Risk Discussion 

5.2.1 Terrestrial and Aquatic Animals 

Toxicity tests and estimated environmental concentrations indicate that risk to terrestrial and aquatic 

animals resulting from direct exposure chlorsulfuron are expected to be low. However, the potential 

exists for indirect impacts because animals ultimately depend on plants and plant communities for 

survival. The extent of said impacts will depend on the species involved and the extent of the 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 sensitive non-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 sensitive plants (which were from guideline studies) had an EC,, as low as 1.0 x 

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 13 for non-target plants and up to 693 for endangered plants. Furthermore, several of the nonagricultural uses have multiple applications and several chlorsulfwon product 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 

laboratory in Corvalis, OR (Fletcher et al., 1993 and Fletcher et al., 1996) suggest that 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. 
Results from the ECOTOX database reveal a range of toxicity between taxonomic groupings and in 

ecologically important families, such as the N-fixing Fabaceae and even among the grasses 

(Poaceae). There is a great deal of uncertainty regarding the effect chlorsulfuron may have on plant 

community composition, particularly with rangeland uses. As evidenced by 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 DF7 herbicide 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 of the 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 chlorsulfuron be 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 

chlorsulfuron is applied to fields to which certain other insecticides have been applied. For example, 

the label for ~inesse' states that "Finesse should not be used within 60 days of crop emergence if an 

organophosphate insecticide (such as "Di ston on^") was used as an in-furrow treatment, or crop injury 

may result". Presumably, neither ofthese two pesticides if used alone will cause crop injury to 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 of Finesse' 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 applied to fields along 

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 studies have 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 EC25 for non-target plants (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/A for.pastures and 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 12 for 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. 

The EECs for a single aerial application (Table 14) are approximately 25% higher than for a uomd 

application. To calculate EECs for an aerial application of chlorsulfuron, 5 .O% drift and 5 .O% runoff 

(one acre to one acre) are assumed. The RQs for non-target plants range from 4 to 6 for small grains 

up to 16 for pasture and rangeland. For endangered plants RQs range from 28 to 40 for small grains 

up to 109 for 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 (Vegetative vigor) 

The vegetative vigor EC25 for 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 1.6 x 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 quotients for nontarget plants range from 16 to 23 for small grains up to 63 for pasture 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 times higher than for a ground application. To 

calculate the EEC for an aerial application, 5.0% drift and no runoff was assumed. The RQs for nontarget plants range from 80 to 115 for small grains up to 3 13 for pasture and rangeland. For 

endangered plants RQs range from 148 to 21 3 for a small grains up to 580 for pasture and rangeland. 

Therefore, aerial application of chlorsulfuron to small grains, pastures and rangeland greatly exceeds 

LOCJs for 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 

required by the EPA do not include reproduction endpoints and available data evaluating this 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 soybean by 92 and 99%, respectively, as compared 

to controls, without causing significant changes in vegetative growth. While the delivery mechanism 

of these low application rates in these studies (saturation by solution) may not .be representative of 

spray drift, the concentrations are within the range of reported herbicide drift levels and suggest that 

chlorsulfuron may cause severe reductions 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 of plant 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 sensitive agricultural crops. Refinement of this analysis, specifically exposure, effects, 

co-occurrence of listed resources, and areas of use would be needed to determine the potential for 

effects. Risk quotients were calculated for semi-aquatic areas adjacent to irrigated fields, terrestrial 

areas adjacent to 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, initial terrestrial plant tests submitted by the registrant were conducted using 

TGAI, and results suggest greater sensitivity of plants to the active ingredient. 

Irrigation with surface water containing chlorsulfuron exceeds 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 endangered plants 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 Drift 
Non-target plants in areas where chlorsulfuron is applied may be exposed to short range 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 . greatest risk of experiencing relatively high exposures to chlorsulfuron, longer range drift has been 

alleged to occur and cause visible effects to terrestrial plants (Felsot et al., 1996, Barolo, 1993). 

Symptoms of chlorsulfuron exposure to non-target plants in areas away from applicatpn sites were 

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 is persistent 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 $0 non-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 soil binding, and mobility within plants (Weed 

Science Society, 1989) suggests that covering weeds evenly with fine droplets is not necessary to 

control them. Because chlorsulfuron can move with soil water and be taken up by plant roots or 

absorbed through plant foliage and be transported systemically throughout the weed, re)atively large 

droplets of chlorsulfuron contacting weeds or surrounding soil are expected to be effective in killing 

weeds. Coarse sprays minimize drift and 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 suggestions of particular droplets sizes 

that reduce drift but do no require the 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 the American Society of Agricultural Engineers standard definitiohs for droplet 

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, driftable droplets may be produced 

that do not result in improved weed control and result in off target movement and potentially in nontarget plant damage. 

The distance that fine spray droplets may travel is largely dependent on their size, release height, and 

meteorological conditions like wind speed. Larger droplets tend to deposit in the application area 

or nearby while smaller droplets may be blown farther downwind. Droplet settling velocity, the 

speed at which droplets settle in air without turbulence, can be useful for conveying the importance 

of droplet size on off-target movement. While a droplet with a diameter of 1000 pm (1 rnm) takes 

1.3 seconds to fall 10 feet and would travel 13.7-feet downwind, in a 10 mph wind, a 100 pm droplet 
takes 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 important application conditions actually 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 of published 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 data used in this analysis, delayed effects may occur at distances greater than 1000 feet 

from target applications. 

This assessment focuses on the effects of spray drift on non-target terrestrial plants. Exposure from 

chlorsulfwon runoff can also cause phytotoxicity to non-target plants. Chlorsulfuron's mobility 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 accounts for more than 98% of agricultural chlorsulfuron usage. The 

maximum application rate 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 flood jet nozzles. The 

lower volume is presumably allowed for the flat fan nozzle because this commonly used nozzle can 
produce a fine enough spray to cover the field with the low volume of 3 gallonslacre. With a volume 

of 3 gallonslacre, a relatively coarse spray would result in too few drops per 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 of treated 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 of typical aerial application 

parameters (Appendix 8). The DuPont survey included 15 aircraft set ups for chlorsulfiron 

applications in Washington and 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. The droplets size 

spectra estimated fi-om the equipment variables ranged from ASAE medium to ASAE coarse. 

Toxicity 

Toxicity for this evaluation are derived fi-om the guideline studies submitted by the registrant to 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 exposure effects fertilization or seed production, reproduction of plants in the wild would 

be expected to 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 representativeness ofplants used in phytotoxicity testing of non-target naturally occurring plants 

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 suggested in 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, specific test species may 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 aparticular herbicide. Native plants sharing species or genus family affinity with the tested 

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 of the phytotoxicity studies may result in higher measured toxicity 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 of the 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 of bounds makes it more difficult to determine what conditions should be 

used for risk assessment. The absence of basic mandatory label language also allows applicators to 

make unnecessarily high drift applications. Applicator common sense would prevent worst case 

applications but may not result 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 efficiency of 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 drifting spray would be less visible but still unnecessarily high. 

Specifying basic spray drift control measures provides applicators with the necessary information 

to perform an effective and low-drift application and risk assessors with the necessary information 

to model drift. 

AgDRIFT Background 

AgDRIFT is a computer model that can be used to estimate downwind deposition of spray drift from 

aerial, ground boom, and orchard and vineyard airblast applications. 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 of 
AgDRIFT only allows Tier 1 level analyses for ground and airblast application methods. In higher 

tiers more options are available for aerial applications. The aerial portion of the model is based on 

a mechanistic US Forest Service model (AGDISP. Bilanin et a1 1989). The ground boom and 

orchard airblast portions are empirical models based on data collected by the Spray Drift Task Force 

(SDTF). The SDTF field data were used to validate the aerial portion of AgDRIFT (Bird et a1 1996). 

AgDRIFT was developed under a cooperative research and development agreement between EPA, 

USDA, and the SDTF. 

Aerial AgDRIFT The most important factors affecting drift from aerial applications are spray quality 

(droplet size), release height, and wind speed. The aerial part of the model predicts mean values 

based on the inputs provided. The Tier 1 aerial results are generated using the specified droplet size 

spectra, 10 foot release height, and a 10 mph wind speed. When wind speed and/or release 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. 

Ground boom sprayers in AgDRIFT: The most important factors affecting drift from ground boom 

applications are spray quality, release height, and wind speed. The ground boom part of AgDRIFT 

is based on field trial data from bare ground applications. The results of the model reflect the quality 

and conditions of the data on which it is based. The data fiom the field trials were grouped into 

categories by spray quality (droplet size) and release height. Results from field trials conducted with 

different wind speeds were averaged. The average wind speed over all the trials was approximately 

10 mph. AgDRIFT outputs for ground boom applications estimate the 50th and 90th percentile of data 

collected from field trials. For this analysis the 50th percentile data was used. The field trial data 

were not corrected for incomplete analytical recoveries, suggesting the true mean deposition values 

would be approximately 20% higher than the model's deposition results. 

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 experienced by 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. Species with 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 calculate the various EC, 

levels: [EC,, 1 10.' 67's'0pe] x1 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 

deposition values to the EC, values to identify the downwind distance at which the EC, values would 

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 1 AgDRIFT 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 

rbeet 
Figure 3. Predicted phytotoxicity levels (vegetative vigor) and associated downwind distances fiom 

an aerial application conducted with a medium spray in a 10 mph wind with a 10 foot release height 

at an application rate of 0.0625 lbs chlorsulfuron per acre. 

No-Spray Zone (ft) 

Aerial: Medium Spray 
Figure 4. 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 2 foot release height at an application rate 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 application conducted with a medium/coarse spray in an approximate 10 mph wind 

with a 4 foot release height at an application rate of 0.0625 lbs chlorsulfiuon per acre. 

Ground: High Boom, Medium-Coarse Spray 

No-Spray Zone (ft) 

1 Effect 
Figure 6. Predicted phytotoxicity levels (vegetative vigor) and associated downwind distances fi-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 chlorsulfinon per 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 application conducted with a medium spray in an approximate 10 mph wind with 

a 4 foot release height at an application rate of 0.0625 lbs chlorsulf'uron per acre. 

No-Spray Zone (ft) 

Ground: Hlgh Boom, Medium Spray 

arbeet 
Conclusions 

Based on the phytotoxicity study results for wheat and chlorsulfuron use sites such as pasturelrange 

land, certain grass species appear to be tolerant to acute chlorsulfuron effects. Some tolerant species 

apparently are susceptible to reproductive effects fiom single exposures based on product claims of 

inhibiting seed head formation described on some product labels. Because of lack of data, 

reproductive effects cannot be evaluated at this time. 

Figures 2 through 7 above show the phytotoxicity downwind of chlorsulfuron applications is 

expected to vary based on a number ofparameter including application method (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 of rapid 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 phytotoxicity at 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 10 tested 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 distance exceeding 1000 feet downwind fiom the treatment area. Using a coarse spray, Figure 

2 shows that 4 of the 10 tested species would 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 of the 10 species tested 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 10 tested 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 expected to be affected at the EC,, level 1000 feet 

or more downwind (i.e. a 10% reduction in shoot weight in an areas stretching for more than 1000 

feet downwind). 

Ground boom Applications 

In all instances the ground boom applications modeled 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 drift conditions allowed by AgDRIFT 2.01 (2 foot boom 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 stretching for the edge of the field 

to beyond 1000 feet 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 

Chlorsulfuron is a selective herbicide. Some species, such as certain grasses, are relatively tolerant 

to chlorsulfuron while other species are sensitive to acute effects and reproductive effects. If certain 

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 selective pressure 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 displace the sensitive species and become 

more common. Changes in the species composition in the boundaries of herbicide-treated fields 

have been noted in the literature (Kleijn and Snoeijing, 1997, Jobin et al., 1997). Given the efficacy 

of chlorsulfuron and the drift potential associated with spray application methods, it is expected that 

chlorsulfbron is applying selective pressure against certain species downwind of applibation areas. 

The magnitude of the selective pressure is expected to depend on the level of drift as well as the 

sensitivity of exposed species. 

The results of this analysis suggest that placing restrictions on droplet size for aerial applications and 

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 applicators balance low release heights with flight safety. 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 of potential 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 chlorsulfiuon is uncertain. Toxicity data on a wider range of plants could be used to 

reduce uncertainty as to the potential effects of chlorsulfuron on perennial and woody species at field 

edges and farther downwind. 

2) The duration of exposure. Laboratory data is based on single exposures to plants with 

observation continuing for two weeks after dosing. Non-target plants in chlorsulfuron use areas may 

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 show chlo&ulfuron negatively affects plant reproduction. Data defining 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 amounts of herbicides tested in the laboratory but in much lower volumes of carrier. 

Plants are exposed to spray drift away far away from the field edge in discrete spots where 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 

endangeredlthreatened terrestrial or aquatic animals. However, the screening level risk assessment 

for endangered species indicates that chlorsulfwon exceeds the acute level of concern for endangered 

and threatened terrestrial and vascular aquatic plants. Thus, the Agency considers this to be 

indicative of a potential for adverse effects to those listed species that rely either on a specific plant 

species (plant species obligate) or multiple plant species (plant dependant) for some important aspect 

of their life cycle. Further analysis regarding the overlap of individual species with e?ch use site is 

required prior to determining the likelihood of potential 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 risks were assigned a "no effect" determination 

with regard to aquatic and terrestrial animals, Reasonable and Prudent Alternatives and Reasonable 

and Prudent Measures were not provided for this pesticide. Risks to endangered were not 

considered in this Biological Opinion. The FWS completed the rangeland 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 considered to be the area affected 

directly or indirectly by the Federal action and not merely the immediate area involved in the action. 

At the initial screening-level, the risk assessment considers broadly described taxonomic groups 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 organisms are assumed to 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, which has the relatively highest potential exposure to the pesticide, and that 

exposures are likely to decrease with distance fiom the treatment area. 

If the assumptions associated with the screening-level action area result in RQs that are below 

the listed species LOCs, a "no effect" determination conclusion is made with respect to listed species 

in that taxa, and no further refinement of the action area is necessary. Furthermore, RQs below the 

listed species LOCs for a given taxonomic group indicate no concern for indirect effects upon listed 

species that depend upon the taxonomic group covered by the RQ as a resource. However, in 

situations where the screening assumptions lead to RQs in excess of the listed species LOCs for a 

given taxonomic group, a potential for a "may affect" conclusion exists and may be associated with 

direct effects on listed species belonging to that taxonomic group or may extend to indirect effects 

upon listed species that depend upon that taxonomic group as a resource. In such cases, additional 

information on the biology of listed species, the locations of these species, and the locat'ions of use 

sites could be considered along with available information on the fate and transport properties of the 

pesticide to determine the extent to which screening assumptions regarding an action area apply to 
a particular listed organism. These subsequent refinement steps could consider how 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 endangered plants should exposure to chlorsulfuron through 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 areas for which the estimated exposure levels used for RQ calculation 

can be expected to occur. A specific determination of "may affect" for any RQ in excess of listed 

species LOCs cannot be 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 (plant species obligate) or multiple plant species (plant dependant) for some important aspect 

of their life cycle. The extent to which the use of chlorsulfuron on wheat 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-level risk assessment has identified potential concerns for indirect effects on 

listed species for those organisms dependant upon plants sensitive to chlorsulfuron. In light of the 

potential for indirect effects, the next step for The Agency and the Service(s) is to identify which 

listed species and critical habitat are potentially 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 
impacted by the pesticide. Then the Agency would determine whether use of the pesticide overlaps 

the critical habitat or the occupied range of those listed species. At present, 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 

directly by 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 features that, if they are constituent elements of one or more critical habitats, would be 

of potential concern. These correspond to the taxa identified above as being of potential concern for 

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-occurrence Analysis 

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 

information for listed species at the county level and compares it to agricultural census data for crop 

production at the same county level of resolution. The product is a listing of federally 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 exclude any taxonomic group from a LOCATES 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 

capacity at 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 of this analysis. 
6.0 REFERENCES 

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metsulfuron-methyl, tribenuron-methyl, chlorsulfuron and thifensulfuron-methyl in one Danish soil 

and groundwater sediment profile. Chemosphere 45,775-782. 

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 (Prunus Avium L.). 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 Deposition of Pesticides from Agricultural Aerial 

Spray Applications. J. Environ. Qual. 25: 1095- 1 104. 

Brewster, B.D., and A.P. Appleby. 1983. Response of Wheat andRotation Crops to Chlorsulfuron Weed Sci. 

31:861-865. 

Clark, J., L.S. Ortego and A. Fairbrother, 2004. Sources of variability in 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. 15 1-158. 

Coyner, A., G. Gupta, and T. Jones. 2000. Effect of Chlorsulfuron on Growth of Submerged Aquatic 

Macrophyte. Potamogeton pectinatus (Sago Pondweed). Environ. Pollut. 1 1 1, 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. Biomonitoring with Sentinel Plants to Assess 

Exposure ofNontarget Crops to Atmospheric Deposition of Herbicides. Environmental Toxicology 

and Chemisty. 15(4): 452-459. 

Fletcher, J.S. 1991. Horse Heaven Hills/Badger Canyon, A case Study of Alleged Pesticide Drift Damage. 

Presentation at the 84th Annual Meeting & Exhibition, Vancouver, British Columbia 91-1 50.7 

Fletcher J.S., T. G. Pfleeger and H.C. Ratsch 1993. Potential Environmental Risks Associated with the New 

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 

Chlorsulfuron and Other Herbicides on 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. Can J Plant 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 System Weed 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., and F.W. Slife. 1988. Absorption and Translocation of 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-Resistance to 

Herbicides in Annual Ryegrass (Lolium rigidum) 1.Properties of the Herbicide Target Enzymes 

Acetyl-Coenzyme A Carboxylase and Acetolactate Synthase Plant Physiol. 94(3): 1 180-1 186. 

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 Tolerance to Chlorsulfuron and Metsulfuron Methyl 

Herbicides Plant Prot Q 4(3): 100-103. 

Nalewaja, J.D., and Z. Woznica. 1985. Environment and Chlorsulfuron Phytotoxicity Weed Sci. 33(3):395- 

399. 

Pallett, K. Efficacy testing processes in industry: relevance for NTTP assessment. Efficacy Data Workshop. 

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. Mechanism of 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 of America. 1989. Herbicide Handbook. Published by the Weed Science Society of 

America. Champaign, IL. 

Zahnow, E.W. 1982. Analysis of the Herbicide Chlorsulfuron in Soil by 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 10 0 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 

10 2 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 0 
0.0021660.002166 0 

5 0.03 0.023 0.116 0 

***Record 40 

0 

YEAR 10 YEAR 10 

1 

1 ----- 

7 YEAR 

PRCP TCUM 0 0 

RUN F 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 

RZ FX 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 1605 0106 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 1611 0112 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 1 
010473 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 0.16 
010489 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, Silt Loam, 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 0.16 
050164 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 

***Record 40 

0 T 

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 Texas Wheat 

TX wheat; 8/13/200 1 

"Winter wheat in Blacklands prairie section of Texas grown on benchmark 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 1606 2006 0107 1607 0108 

.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 170677 
101078 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 18 
0 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(*) = 0.0 
RUN 

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, *) = 22.2104590672629 
set 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. 0 
set 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.D87 
SET 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 

67 
11 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 (st111 births) and the LOEL was 356 

mg/kg/day Reproduct~ve toxicity was observed in both generationshoth litters, as evidenced by decreased fertility of the dams No parental toxicity 

was observed 

31 This study does not fulfill test guidelines requ~rements It is repairable ~f additional information on the solvent control and dilution water is 

subm~tted 

41 Th~study 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 Terrestrial Field Study No 

71-5(b) Actual Terrestrial Field 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 Toxicity Fish 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 Toxicity Fish (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 41 9764-08 Yes l6 
Data 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) Simulated Aquat~c Field Study 

72-7(b) Actual Aquatlc Field Study 

8158.540 PLANT PROTECTION 

122-l(a) Seed Germ.,Seedling Emergence 

122-1 (b) Vegetative Vigor 

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 Photodegradation In Water 

161-3 Photodegradation On Soil 

Yes 421567-01 

Yes 421 567-02 

Yes 421 567-03 

Metabolism Studies-Lab: 

162-1 Aeroblc Soil Yes 422 1420 1 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=Indoor Non-Food d; 14=Indoor Medical; 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 study is scientifically sound but does not fulfill the guideline requirements for seedling emergence and vegetative vigor studies (Subdivision 

J, $123-1 (TIER 11)) because the light intensity in both studies was well below guideline recommendations. 

191 This study was conducted under static conditions. Test concentrations should be renewed 3-4 tlmes during the 14 day test. This study should 

be repeated 

201 Lysimeter studies were 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 APPLICATION AT 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/a applicatlon 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 spreadsheet based model calculates the decay of a chemical applied to 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) concentrations on 

plant surfaces following application. 

A first order decay assumption is used to determine the concentratlon at each day after inltlal 

appllcatlon based on the concentratlon resulting from the lnltlal and addalonal applications The 

decay is calculated by 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 

CI is calculated based on the Kanaga nomogram (Hoerger and Kenaga, (1972) as modlfied 

Fletcher (1994) For maximum concentration the applicatlon rate, in pounds active 

ingredient per acre, is multiplied by 240 for Short Grass, 1 I0 for 

Tall Grass, and 135 for Broad leafed plantslsmall insects and 15 for fru~tslpodsllg insects 

Additional applications are converted from pounds active lngredlent per acre to 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 = If the fohar dissipation data submttted to EFED are found scientifically val~d and stanstlcally 

robust for a spec~fic pestlclde, the 90% upper confidence limit of the mean half-llves should be used 

When sclentrfically valid, statistically robust data are not available TETT recommends the using a 

default half-life value of 35 days The use of the 35 day half-hfe is based on the highest reported value 

value (36 9 days) reported by W~llis and McDowell (Pesticide perslstence on 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 calculates concentratlon 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 calculate the 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 dominate process(m days) 

Frequency of Application The Interval between repeated applications, from the label (in days) 

Maximum # Application per year From the label 

The calculated concentrations are used to calculate Avian 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 give RQs for each type of plant 

surface. 

The rat LC 50 is calculated by dividing the mammalian LD 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 15 body wt for herbivores and ) 

insectivores and 0 21,0.15 and 0 03 body wt for granrvore) 

The number of days that the Input value of Chronic No Observable Adverse Effects Level and 

acute LC50 are exceeded tn the first 56 days is calculated by 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 

calculated by dividing the input value by the Kenaga maximum concentration for Short Grass (240). 

This version of ELL-Fate (v1.4) incorporates the ability to calculate EECs 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 plantslsmall insects 

and 7 for fruitslpodsllg insects. 
APPENDIX 5. NON-TARGET TERRESTRIAL PLANT 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 0.00 1463 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 0.00 107 1 

Rape 0.0001 83 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 46361 8-01 
APPENDIX 6 NON-TARGET TERRESTRIAL PLANT 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 1463 1 0.0040 1 0.001463 1 0.0065 1 

Pea 0.00001 16 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 SURFACE AND GROUNDWATER 

IRRIGATION 

To calculate risk quotients for plants when groundwater contaminated by chlorsulfuron is applied 

to crops, the following method 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 irrigation water 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 applicators to 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 sensitive crops. 

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 distribution was 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 distribution fiom 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, orientation angle, air speed, and 

pressure - were supplied by the applicators or representative values were selected as indicated in 

the attached table. 

The drop size distributions were evenly split between 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 settings would 

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 135 mph produces a medium to coarse size distribution, while at 100 mph would 

produce a very coarse to extremely coarse size distribution, according to the USDA model. 

Since the USDA model simulates drop size distributions for a spray solution with 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 distributions predicted 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 

Application 

Boomlength 

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 

90-1 10 

1 10- 120 

1 15 

13 5 

125-130 

130 

D-8 

CP Straight 

Stream 

Spray Systems D7 no core 

D8, 10, or 12 

CP .171 15deg 

plate 

Dl0146 

Dl0 

CP solid stream, 

no plate 

CP solid stream, 

no plate 

100-1 10 

135 

120-125 

120 

120 

120 

120 

1 15 

105- 1 15 

0,10 

0 

0 

3 5 

15 

0 

0 

0 

0 

Aircraft 

188 Cessna 

Airtractor AT 

400 & 502 

Thrush S2R-6 

Turbine Thrush 

Super Doer 

Thrush 

502 & 802 Air 

Tractor - - - - 

Pressure 

15 psi 

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- 

1 10 mph 

all orifices, 20-40psi, 1 10- 

120 mph 

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, 15 not 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 application ranges 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 application conducted with a coarse spray in a 10 mph wind with a 10 foot 

release height at an application rate of 0.012 lbs chlorsulfuron per 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 application rate 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-Spray Zone (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 chlorsulfuron per 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 10 mph 

wind with a 4 foot release height at an application rate of 0.012 lbs chlorsulfuron per acre. 

No-Spray Zone (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 LFU RON ESTIMATED ANNUAL AGRICULTURAL USE 

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

w 0.001 - 0.003 Wheat and amns 55.312 89895 56 zl? 166 1.17 

0 - o.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 ASSESSMENT MEMORANDUM 

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 Support TRED 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 Assessment for 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 represent upper-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 of toxicological concern, 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 Chlorsulfuron 
Model Concentration From Use on Concentration From Use on 

Wheat Non-Residential Turf 

FIRST Surface Water Peak Day (Acute) 1.6 ppb 

FIRST Surface Water Annual Average (Chronic) 0.55 ppb 16.4 ppb 

SCIGROW Ground Water (Acute and Chronic) Value 0 16 ppb 3.5 ppb 

Monitoring Data: 

Chlorsulfuron was not an analyte in the USGS, NAWQA monitoring program. Pesticides in Groundwater 

Database, A Compilation Of Monitoring Studies: 1971-1991 National Summav, US EPA September 1992, entries 

indicate that of eight wells 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, of the 7 1 streams tested, only detected in one of the outflow samples fi-om the 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 of the specific degree of mobility 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 soil metabolism studies, transforming into hydroxy 

triazine amine with concentrations increasing steadily throughout the study. 

Drinking Water Treatment Effects: 

Primary water treatment is not expected to remove chlorsulfuron fi-om drinking 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: 

FIRST4 is 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 

3Concentration ofselected Sulfonylurea, Sulfonamide, and Imzdazolinone Herbicides, Other Pesticides, and Nutrients in 71 Streams, 

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 standard water body used by the Office of Pesticide Programs to assess drinking water 

exposure (Hetrick et al, 1998). It is based on a real reservoir in Illinois that is known to vulnerable to pesticide 

contamination. The single runoff event moves a maximum of 8% of the applied pesticide into the pond. This amount can 

be reduced due to degradation on the field and the effects of binding to soil in the field. 

Background Information 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 drinking water contaminated with the pesticide. SCIGROW 

estimates likely groundwater concentrations if the pesticide is used at the maximum allowable rate in areas where 

groundwater is vulnerable to contamination. In most cases, a large majority of the use area will have groundwater that is 

less vulnerable to contamination than the areas used to drive the SCIGROW estimate. 

Modeling Inputs and Results: 

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 conservative estimate 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 surface water concentrations. The modeling results .from 

FIRST, using these assumed parameters, estimates pre-treatment surface water concentrations of total chbrsulfuron 

residues (both parent and degradationproducts), resulting from two applications, at 60 day intervals, of the 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 of this memo are for parent only, as Health Effects Division has indicated that only the parent compound is 

of toxicological 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 ingredient per 

acre for non-crop, non-residential turf. Labeled non-crop, non-residential turf uses include industrial turf 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 in Modeling the Environmental Fate and Transport ofpesticides, Version 11, February 28, 

20026. In the absence of anaerobic metabolism 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 concentrations of 1.6 ppb for wheat and 46.8 ppb for non-residential 

turf. Chronic (average annual) concentrations were 0.55 ppb for wheat and 16.4 ppb for non-residential turf. SCIGROW 

predicted groundwater concentration s of 0.16 ppb 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 1,800 ma 

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 1 L/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 

Application Frequency 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 

Application Frequency 2 per year 2 per year 

APPENDIX I 

FIRST SURFACE WATER MODELING RESULTS FOR 

CHLORSULFURON 

OUTPUT TABLES FOR CHLORSULFURON ON WHEAT 

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 SURFACE WATER MODELING RESULTS FOR CHLORSULFURON 

OUTPUT TABLES FOR CHLORSULFURON ON NON-RESIDENTIAL TURF 

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 SURFACE WATER MODELING RESULTS FOR CHLORSULFURON AND DEGRADATION PRODUCTS 

OUTPUT TABLES FOR BOTH CHLORSULFURON AND DEGRADATE RESIDUES ON NON-RESIDENTIAL TURF 

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 CHLORSULFURON ON 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 CHLORSULFURON ON 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