DP Barcodes:D244862, D248122, D248123, D248359, 

D245119, D246782, D246987, D250295 

PC Code No. 129111 

MEMORANDUM

SUBJECT: EFED Risk Assessment for the Section 3 Registration of Kresoxim Methyl on 

Apples, Grapes, and Pecans. 

TO: Luis Suguiyama, Chief 

Mary Waller, Product Manager 21 

Fungicide Branch 

Registration Division 

FROM: N.E. Federoff, Wildlife Biologist 

Larry Liu, Ph.D., Environmental Scientist 

Ron Parker, Ph.D., Environmental Engineer 

Dana S. Spatz, Chemist 

Environmental Risk Branch IV 

Environmental Fate and Effects Division 

THROUGH: Mah T. Shamim, Ph.D., Chief 

Environmental Risk Branch IV / EFED 

This memo summarizes the attached EFED Environmental Risk Assessment for kresoxim 

methyl registration as a fungicide on apples, grapes, and pecans. An analysis of the 

environmental fate, ecological effects and use patterns of kresoxim methyl indicates that parent 

and its major degradate BF 490-1 are not likely to represent a significant threat to non-target 

organisms. In addition, the short-lived kresoxim methyl is unlikely to impact water resources. 

However, since the major acid degradate BF 490-1 has the physical/chemical characteristics in 

common with those pesticides that are known to leach to ground water or to move offsite to 

surface water, the potential for BF 490-1 to contaminate ground water and surface water exists, 

especially when it is applied to fields with one or more of the following characteristics: alkaline 

soils, low organic matter, high sand, shallow ground water table, and nearby bodies of water. 

Fortunately, the acute toxicity data available indicates this degradate is practically non-toxic to 

freshwater fish and invertebrates and it is unlikely that the degradate would pose risk to other 

species as well. The chronic toxicity of BF 490-1 is unknown. 
2 

It is noted that HED has raised concerns about cancer risk to mammals. In two 24-month 

feeding studies, the NOEL was 800 ppm and the LOEL was 8,000 ppm. However, these 

kresoxim methyl concentrations are over 10X the maximum residues expected in the field based 

on our terrestrial exposure assessment. Therefore, EFED does not believe that these concerns 

will translate to adverse effects on nontarget mammals. 

Drinking Water Exposure

Because of the concerns raised by HED with regard to cancer risk to mammals, a tier II drinking 

water assessment was conducted. Results from this assessment suggest that the surface water 

concentration values that should be used for the acute human health risk assessment are 1.2 μg/L 

for parent kresoxim methyl and 13.8 μg/L for BF 490-1. The surface water values that should be 

used for the chronic and cancer human health risk assessments are the long term average values 

of 5.8 ng/L for parent kresoxim methyl and 5.0 μg/L for BF 490-1. The ground water screening 

concentration for kresoxim methyl is negligible. The ground water screening concentration for 

BF 490-1 is 4.1 ppb. These values represent upper-bound estimates of the concentrations that 

might be found in surface water and ground water due to the use of kresoxim methyl on apples, 

grapes, and pecans. 

Data Gaps 

All environmental fate and ecological effects data requirements have been satisfied. 

Although the acute data for estuarine/marine invertebrates is less than 1 mg/L (LC50=0.0147 

ppm) and would normally trigger a required chronic study, this requirement is waived for the 

present uses due to the following factors: (1) the parent breaks down quickly (aerobic aquatic 

metabolism=1.3 days) and (2) BF 490-1 is persistent but extrapolation from toxicity data from 

freshwater studies using this degradate indicate that it is practically non-toxic. 

Suggested Label language 

The environmental hazards label statement should be as follows: 

This pesticide is toxic to freshwater and estuarine fish and invertebrates. Do not apply 

directly to water, to areas where surface water is present or to intertidal areas below the 

mean high-water mark. Drift and runoff may be hazardous to aquatic organisms in 

neighboring areas. Do not contaminate water when disposing of equipment wash water or 

rinsate. 

Suggested Ground Water and Surface Water Advisories 
3 

Ground Water Advisory: This chemical has properties and characteristics associated with 

chemicals detected in ground water. The use of this chemical in alkaline areas where soils are 

permeable, particularly where the water table is shallow, may result in ground water 

contamination. 

Surface Water Advisory: This chemical can contaminate surface water through spray drift. 

Under some conditions, it may also have a high potential for runoff into surface water (via both 

dissolution in runoff water and adsorption to eroding soil), for several days post-application. 

These include poorly draining or wet soils with readily visible slopes toward adjacent surface 

waters, frequently flooded areas, areas over-laying extremely shallow ground water, areas with 

in-field canals or ditches that drain to surface waters, areas not separated from adjacent surface 

waters with vegetated filter strips, and highly erodible soils cultivated using poor agricultural 

practices such as conventional tillage and down the slope plowing, and areas where an intense or 

sustained rainfall is forecasted to occur within 48 hours. 
4 

Table of Contents

Introduction......................................................................................................................................5 

Environmental Fate and Water Resource Assessment.....................................................................7 

Environmental Fate Summary .............................................................................................7 

Environmental Fate Assessment..........................................................................................8 

Water Resource Assessment..............................................................................................10 

Aquatic Exposure Assessment...................................................................................................... 12 

FQPA Drinking Water Exposure Assessment ...................................................................12 

Terrestrial Exposure Assessment...................................................................................................15 

Ecological Effects Hazard Assessment..........................................................................................16 

Ecological Risk Assessment ..........................................................................................................17 

Risk Characterization.....................................................................................................................18 

Appendix I: Ecological Toxicity Data...........................................................................................21 

Appendix II: Terrestrial and Aquatic Exposure and Risk Assessment..........................................27 

Appendix III: GENEEC for Ecological Effects Assessment.........................................................37 

Appendix IV: SCI-GROW for Environmental Fate Assessment ..................................................39 

Appendix V: Tier II Surface Water Site/Scenario.........................................................................40 

Appendix VI: Summary of Submitted Environmental Fate Studies..............................................41
5 

INTRODUCTION

Kresoxim methyl (Sovran) is a strobilurin fungicide. The chemical’s mode of action is through 

the inhibition of mitochondrial respiration by blocking electron transport at the cytochrome bc1-

complex (Sauter et al., 1995). Sovran fungicide has a protective effect due to inhibition of spore 

germination and curative-eradicative effect due to inhibition of mycelial growth and sporulation 

on the leaf surface. It can therefore be applied in either pre or post infection situations. 

Trade Name: Sovran 50 DF fungicide 

Treatment Area: Proposed label restricts use to apples, grapes, and pecans. 

Target Organisms

Apples: Scab, cedar apple rust, frogeye leafspot, flyspeck, sooty blotch, and powdery 

mildew diseases. 

 

Grapes: Black rot, downy mildew, phomopsis cane and leaf spot, and powdery mildew 

diseases. 

Pecans: Leaf and nut scab, downy spot, and powdery mildew diseases.

 

Formulation Information

Sovran 50 DF is formulated as a water-dispersible granule (WG) containing 50% active 

ingredient. 

 *Active Ingredient: Methyl (E)-2-methoxyimino-2-[2-(o-tolyloxymethyl) 

 phenyl] acetate 

*Kresoxim methyl.....................................50% 

 Inert Ingredients......................................50% 

*Contains 0.025 pounds of active ingredient per 0.8 ounces of product . 
6 

Application Methods and Rates

 

Crop 

Max Rate 

(lbs ai/a) 

Application 

method 

Min. interval 

between 

applications 

Max. # of 

applications/ 

season Max. lbs ai/year 

Apple 0.2 Ground Spray 7 days 4 0.8 (25.6 oz) 

Grapes 0.175 Ground Spray 7 days 4 0.8 (25.6 oz) 

Pecans 0.15 Ground Spray 14 days 5 0.8 (25.6 oz) 

Spray foliage to the point of runoff. Thorough coverage of the plants is required for optimum 

disease control. A protective barrier of Sovran must be established and maintained on the plant 

surface to achieve effective disease control. Repeat application every 14 days or every 7 days if 

disease pressure is heavy. 

Physical/Chemical properties: 

Chemical name: methyl (E)-2-methoxyimino-2-[2-(otolyoxmethyl)phenyl]acetate 

Molecular formula: C18H19NO4

Molecular weight: 313.4 

Formulations: DF (50:50) 

Physical state: Solid 

Color: Light brown 

Odor: Mildly aromatic 

Melting point: 98-100°C 

Boiling point: unknown 

Vapor pressure (20°C): 1.7x10-9 mmHg 

Water solubility (20°C): 2 ppm 

Octanol/water partition coefficient (Kow): 2,500 (25°C) 
ENVIRONMENTAL FATE 

7 

AND WATER RESOURCE ASSESSMENT

Environmental Fate Summary 

The environmental fate assessment for kresoxim methyl was mainly based on the data submitted 

by the registrant to support the environmental fate data requirements for the terrestrial food crop 

use on apples, grapes, and pecans. However, additional information obtained from other sources 

was also used in the assessment. Based on the environmental fate properties for kresoxim 

methyl, with consideration of the product formulation and application rates, EFED believes that 

the rapidly degraded parent compound is unlikely to have adverse effects on the environment. 

However, since the major acid degradate (BF 490-1) has the physical/chemical characteristics in 

common with those pesticides that are known to leach to ground water or to move offsite to 

surface water, the potential for BF 490-1 to reach ground water and surface water exists, 

especially when it is applied to fields with one or more of the following characteristics: alkaline 

soils, low organic matter, high sand, shallow ground water table, and nearby bodies of water. 

Kresoxim methyl has the following characteristics: 

• low water solubility (water solubility=2 ppm) 

• is very stable to hydrolysis at pH 5 and relatively stable at pH 7 (half-life=34 days); it 

becomes more susceptible to hydrolysis at pH 9 (with a half-life of 7 hours; BF 490-1 is 

the major degradate) 

• photodegrades very slowly with a half-life of 37.2 days in water and 35.2 days on soil 

• degrades very rapidly to BF 490-1 in soil under aerobic conditions (half-life=less than 1 

day) and in sediments flooded with water under aerobic conditions (half-life=1.3 days) 

• degrades very rapidly to BF 490-1 in soil flooded with pond water under anaerobic 

conditions (half-life=1.1 days) 

• is very mobile in sand, loamy sand, loam, and clay soils (Kads ranged from 0.93-10.5 with 

an average of 4.5; Koc ranged from 320-567 with an average of 419) 

• is non-volatile in water and soil (vapor pressure=1.7x10-9 mmHg; Henry's Law 

constant=3.5x10-10 atm m3

/mol) 

• is not expected to accumulate in fish based on the moderate octanol water partition 

coefficient (Kow=2,500) and results from a rainbow trout study showing bioconcentration 

factors (BCF) for viscera, fillet, and whole fish of 430X, 53X, 220X, respectively with 

rapid depuration. 
8 

Information on the fate of the major acid degradate (BF 490-1) is very limited. It has the 

following characteristics: 

• is expected to be very stable in aqueous media 

• is more mobile than the parent compound (Kads values for BF 490-1 were 0.8 for clay, 0.9 

for loam, and 0.4 for loamy sand; the corresponding Koc values were 43, 33, and 69) and 

mobility in alkaline soil is expected to be higher than that in acid soil 

• is highly water soluble (estimated to be 3,661 ppm based on the Koc.) 

• is more persistent than the parent compound in soil (half-life under aerobic conditions 

was 131 days) and aquatic environments (aerobic aquatic metabolism half-life >> 100 

days). 

Environmental Fate Assessment 

Abiotic Degradation

Kresoxim methyl does not hydrolyze and it photodegrades very slowly in the acid aqueous 

environment. However, as the pH of the solution increases from acid to neutral, especially to 

alkaline, hydrolysis increases its role in the dissipation of kresoxim methyl in the environment. 

Photolysis does not play a significant role in the dissipation of kresoxim methyl on the soil 

surface. 

Biotic Degradation

Kresoxim methyl degraded very rapidly to BF 490-1 in soil and in soil/natural water systems 

under aerobic and anaerobic conditions (half-lives were approximately one day or less). BF 490-

1 was found to be much more persistent than the parent compound. The half-life for BF 490-1 in 

soil under aerobic conditions was 131 days. 

Mobility

Based on the organic carbon adsorption coefficients (Koc) obtained from the adsorption studies, 

kresoxim methyl is classified as a chemical with a “medium” soil mobility potential (average 

Koc=419; average Kd=4.5) whereas BF 490-1 is classified as a chemical with a “very high” soil 
9 

 

mobility (average Koc=48; average Kd=0.7)

1

. 

1 Annual Book of ASTM (American Society for Testing and materials) 

Standards. 1994. Standard Test Method for Determining a Sorption Constant (Koc) for 

an Organic Chemical in soil and Sediments. Published by ASTM.

The potential for the parent compound to move into ground water and to move with surface 

runoff water exists. However, due to its extremely rapid metabolism in soil and natural water 

systems under either aerobic or anaerobic conditions, it is reasonable to believe that the amount 

of kresoxim methyl present in the top soil layer after application and available for subsequent 

leaching and runoff would be very minimal and relatively insignificant. On the contrary, BF 

490-1 is much more mobile and persistent (aerobic soil metabolism half-life=131 days; aerobic 

aquatic metabolism half-life >> 100 days) than the parent compound. Since BF-490-1 is an acid 

form of kresoxim methyl, the water solubility for BF 490-1 should be higher than the parent 

compound (2 ppm). Using the following equation, the water solubility for BF 490-1 was 

estimated to be 3,661 ppm: 
10 

Log Koc = - 0.55 log (water solubility, ppm) + 3.642

Freundlich Kads values for kresoxim methyl were measured in sand, loamy sand, loam, and clay 

soil:solution slurries. Freundlich Kads values were 0.93 for the sand soil, 3.45 for the loamy sand 

soil, 6.49 for the loam soil, and 10.52 for the clay soil; corresponding Koc values were 320, 541, 

249 and 567, respectively. In a similar study, BF 490-1 was determined to be very mobile in 

clay, loam, and loamy sand soil:solution slurries. Freundlich Kads values were 0.79 for the clay 

soil, 0.87 for the loam soil, and 0.44 for the loamy sand soil; corresponding Koc values were 44, 

33, and 69, respectively. 

Kresoxim methyl is basically non-volatile in water and soil (vapor pressure=1.7x10-9 mmHg; 

Henry's Law constant=3.5x10-10 atm m3/mol). Therefore, volatilization is not a significant route 

of dissipation in the environment. However, due to the lack of information on vapor pressure for 

BF 490-1, EFED is unable to assess the role of volatilization on the dissipation of this chemical. 

Bioaccumulation

Kresoxim methyl is not expected to accumulate in fish based on the moderate octanol water 

partition coefficient (Kow=2,500) and results from a rainbow trout study showing 

bioconcentration factors (BCF) for viscera, fillet, and whole fish of 430X, 53X, 220X, 

respectively with rapid depuration. 72%, 90%, and 78% of the respective residues accumulated 

by exposure day 28 were released from the viscera, fillet, and whole fish tissue within the first 

day of depuration. By 14 days of the depuration phase, 99.5%, 98.6% and 99.4% of the residues 

were eliminated from the viscera, fillet and whole fish tissue samples, respectively. 

 2

Lyman, W. J.1990. Adsorption Coefficient for Soils and Sediments. In 

Handbook of Chemical Property Estimation Methods: Environmental Behavior of 

Organic Compounds. Editors: W. J. Lyman, W. F. Reehl, and D. H. Rosenblatt. 

American Chemical Society.

Field Dissipation

Based on the information from the environmental fate laboratory studies, the major routes of 

dissipation of the parent compound appear to be rapid metabolism and the subsequent leaching 

and surface runoff of the rapidly-formed BF 490-1. Although rapid degradation of parent 

compound and formation of BF 490-1 was observed in all field dissipation studies (including a 

lysimeter study), this degradate was found to be relatively immobile. This is contradictory to the 
11 

prediction based on the findings from laboratory studies. 

Results from the field dissipation studies conducted in New York, Oregon, and California 

showed that kresoxim methyl degraded very rapidly to BF 490-1 with dissipation half-lives of 

4.5 hours, 2.9 days, and <1 hour, respectively. During the one year study period at all three 

study sites, kresoxim methyl remained in the top 0-3" soil zone with the exception of one 

detection (0.012 ppm) in one of the three replicate samples collected from the 3-6" soil zone 

immediately after the first application at the Oregon site. Since no rainfall was reported and no 

irrigation water was applied on that day, it appears that the detection in the 3-6" soil zone at the 

Oregon site was likely caused by contamination. At all three study sites, the dissipation was so 

rapid that BF 490-1 was detected in the surface soil even within hours after each of the four 

weekly applications. However, in contrast to the prediction based on the laboratory studies, a 

significant level of migration of BF 490-1 in the soil was not observed in all these three field 

studies. BF 490-1 was detected only in the top 6 inch soil zones at the New York and Oregon 

sites and it did not migrate deeper than 12 inches at the California site during the study duration 

of one year. 

Water Resource Assessment 

Ground Water

Even though kresoxim methyl appeared to be relatively mobile in the four soils tested, with 

Freundlich organic carbon adsorption coefficients (Koc) ranging from 320-567 (average 

Koc=419), the rapid metabolism of the parent compound observed in the soil and aquatic 

laboratory studies conducted under aerobic and anaerobic conditions suggests that a low level of 

kresoxim methyl would be present for subsequent leaching. On the contrary, the major acid 

degradate BF 490-1 is much more mobile (average Koc=48) and persistent (aerobic soil 

metabolism half-life=131 days; aerobic aquatic metabolism half-life >> 100 days) than the 

parent compound. 

The rapid dissipation of the parent compound was confirmed in the field dissipation studies 

conducted in New York, Oregon, and California. 
12 

BF 490-1 was found only in the 0-3" and 3-6" soil zones during the course of the one-year study 

at the New York and Oregon sites whereas it migrated into the 6-12" soil zone (with 23 

detections ranging from 0.010-0.033 ppm) at the California site. The greater mobility of BF 

490-1 in the soil profile at the California site than that at the New York and Oregon sites appears 

to be attributed to the higher pH (pH=7.1) and lower organic matter (1.1%) at the California site. 

 

Since the major degradate (BF 490-1) is much more mobile and persistent than the parent 

compound, EFED is concerned about the impact of BF 490-1 on ground water resources, 

especially when kresoxim methyl is applied to fields with alkaline soils, low soil organic matter, 

high sand content and a shallow ground water table. 

Surface Water

Kresoxim methyl can reach surface waters as a result of surface runoff and ground water 

discharge. Since kresoxim methyl is classified as a chemical with “medium soil mobility” and 

the rapidly-formed and very-persistent major degradate (BF 490-1) is classified as a chemical 

with “very high soil mobility”, both are subject to dissolution in the runoff water, as opposed to 

adsorption to the eroding soil. 

EFED believes that kresoxim methyl is not likely to persist in surface waters because it degrades 

very rapidly in the aquatic system under aerobic and anaerobic conditions. Furthermore, if 

kresoxim methyl reaches surface water with an alkaline pH, the dissipation of the parent 

compound would be increased due to alkaline hydrolysis. 

The potential for BF 490-1 to reach surface waters after the application of kresoxim methyl in 

the field is high, especially if a runoff-producing rain event occurs within several days to weeks 

after application. Surface water runoff will compete with movement to ground water. Once BF 

490-1 reaches surface waters, it is expected to be very persistent under either aerobic or 

anaerobic environments. 
13 

AQUATIC EXPOSURE ASSESSMENT

Exposure to aquatic nontarget organisms is possible through surface water runoff, soil erosion, 

and off-target spray drift The GENEEC model was used to predict estimated environmental 

concentrations (EEC’s) of kresoxim methyl in the aquatic environment (see Appendix 3). For 

the degradate BF 490-1, the PRZM/EXAMS model was used to predict surface water EEC’s. 

Modeling results for grapes, pecans, and apples are summarized below. 

 

Kresoxim Methyl EEC 

(ppb) 

BF 490-1 EEC 

(ppb) 

Crop Application Rate 

 ( lbs ai/A) 

Applications 

per season 

Peak 4-

days 

21-

days 

56-

days 

Peak long-term 

average 

Apples 0.2 4 5.95 3.17 0.68 0.26 13.8 5.0 

Grapes 0.175 4 5.20 2.77 0.60 0.22 

Pecans 0.15 5 4.42 2.36 0.51 0.19

Drinking Water Exposure Assessment

This section summarizes tier I ground water and tier II surface water estimated drinking water 

concentration values for use in the human health risk assessment. The tier I ground water 

estimate was developed using the SCI-GROW program and the tier II surface water estimate was 

calculated using PRZM/EXAMS. There are no refined tier II methods for ground water 

available at this time. Both the ground water and surface water assessments include estimates 

for parent kresoxim Methyl as well as its primary degradate BF 490-1. The SCI-GROW ground 

water concentration represents application to a vulnerable apple, grape or pecan growing area. 

The tier II PRZM/EXAMS simulation represents application to apples or grapes in New York 

State. These values represent upper bound estimates of the concentration that might be found in 

surface or ground water. The surface and ground water concentrations values are listed below in 

Table 1. The surface water concentration values that should be used for the acute human health 

risk assessment are the peak values of 1.2 μg/L for parent kresoxim methyl and 13.8 μg/L for BF 

490-1. The surface water values that should be used for the chronic and cancer human health risk 

assessments are the long term average values of 5.8 ng/L for parent kresoxim methyl and 5.0 

μg/L for BF 490-1. The ground water screening concentration for kresoxim methyl is negligible. 

 The ground water screening concentration for BF 490-1 is 4.1 ppb. 
14 

Table 1. Estimated environmental concentrations (drinking water) for Kresoxim Methyl and the 

primary degradate BF 490-1 as used on apples or grapes in New York State.

 Chemical 1 in 10 Year Maximum 

Surface Water Concentration 

Average of 36 Years of Daily 

Surface Water Concentration Values 

Parent Kresoxim Methyl 1.2 μg/L 5.8 ng/L 

Degradate BF 490-1 13.8 μg/L 5.0 μg/L 

SCIGROW Ground water Conc. 4.1 ppb (BF 490-1)

Environmental Fate Input Values

Environmental fate inputs to the PRZM and EXAMS programs are listed along with their 

sources in Tables 2a and 2b attached. Soil, cropping and management inputs to PRZM are those 

selected by the PIC (PRZM Input Collator) data base. EXAMS environment inputs are taken 

from the Georgia pond scenario. 

Table 2a. PRZM/EXAMS environmental fate input parameters for Kresoxim Methyl 

Chemical Kresoxim Methyl 

Molecular Weight 313.4 

Solubility 2 mg L-1

Vapor Pressure (torr) 1.7 e-9 

Henry’s Law Constant 3.51 e-10 

pH 5 Hydrolysis halflife (days) Stable 

pH 7 Hydrolysis halflife (days) 34 days 

pH 9 Hydrolysis halflife 7 Hours 

Soil Photolysis halflife (days) 35.2 

Aquatic Photolysis halflife (days) 18.6 

Aerobic soil metabolism (days) 1.0 

Aerobic aquatic metabolism (days) 1.3 

Anaerobic aquatic metabolism 

(days) 

1.1 

Soil Water Partitioning (Koc) 419L kg-OC-1

Source EFED Review of Registrant Study 
15 

Table 2a. PRZM/EXAMS environmental fate input parameters for Kresoxim Methyl 

Chemical Kresoxim Methyl 

Prepared By R. Parker 

Date April 22, 1999 

Crops Apples, grapes 

Application Rate 0.20 lb a.i. acre-1

Number Of Applications 4 

Application Method Airblast 

Table 2b. PRZM/EXAMS environmental fate input parameters for BF 490-1 

Chemical Degradate BF 490-1 

Molecular Weight 299.3 

Solubility 3,661 mg L-1 (estimated) 

Vapor Pressure (torr) 1.7 e-9 (assumed from parent) 

Henry’s law constant 3.51 e-10 (assumed from parent) 

Soil Water Partitioning (Koc) 48 L kg-OC-1

Aerobic soil metabolism half-life 

(days) 

131

The hydrolysis degradation values in Table 2a show a strong pH dependence varying from stable 

at pH 5 to a half-life of 7 hours at pH 9. In the absence of other degradation pathways, this would 

lead to significant differences in concentration between environments with different pH values. 

However, in the case of Kresoxim Methyl, this difference is not seen because both the aerobic and 

anaerobic degradation values are in the range of 1 to 2 days and therefore the overall degradation 

rate is similar for the two environments. 

Sci-Grow Input values for parent Kresoxim Methyl and for degradate BF 490-1 are given below. 

Kresoxim Methyl Environmental Fate Input Parameters for SCI-GROW (apples, grapes, and pecans).

Organic Carbon Partition Coefficient (Koc): 284 ml/g 

Aerobic Soil Metabolism Half-Life 1 day

BF 490-1 Environmental Fate Input Parameters for SCI-GROW (apples, grapes, and pecans).

Organic Carbon Partition Coefficient (Koc) 43 ml/g 

Aerobic Soil Metabolism Half-Life 131 days
16 

TERRESTRIAL EXPOSURE ASSESSMENT

The estimated environmental concentration (EEC) values used for foliar terrestrial exposure are 

derived from the Kenega nomograph, as modified by Fletcher et al. (1994), based on a large set of 

actual field residue data. The upper limit values from the nomograph represent the 95th 

percentile of residue values from actual field measurements (Hoerger and Kenega, 1972). The 

Fletcher et al. (1994) modifications to the Kenaga nomograph are based on measured field 

residues from 249 published research papers, including information on 118 species of plants, 121 

pesticides, and 17 chemical classes. These modifications represent the 95th percentile of the 

expanded data set. Risk quotients (Appendix II) are based on the most sensitive dietary LC50 and 

reproductive NOAEC for birds (in this instance, both the mallard duck and bobwhite quail) and a 

calculated dietary endpoint (derived from the rat LD50) and reproductive NOAEC for mammals 

(based on lab rat studies). 

For single application EECs, day zero maximum Fletcher residue values are used. For chemicals 

with multiple applications, foliar dissipation data are incorporated (when available) to estimate 

dissipation between applications. If adequate foliar dissipation data are not available, foliar halflives are estimated based on other fate properties of the chemical. In the case of kresoxim methyl, 

a 1 day foliar half-life was estimated and used for predicting EECs for multiple applications. 

Estimated Environmental Concentrations on Avian and Mammalian Food Items (ppm) Following a Single 

Application at 1 lb. ai/A (Hoerger and Kenaga, 1972, as modified by Fletcher et al, 1994)

EEC (ppm) 

Predicted Maximum Residue 

EEC (ppm) 

Food Items Predicted Mean Residue 

Short grass 240 85 

Tall grass 110 36 

Broadleaf plants and small insects 135 45 

Fruits, pods, seeds, and large insects 15 7 

EECs are based on the maximum application rates (worst case) for selected modeled crop uses for 

kresoxim methyl. These rates and crops include the following: 

• Pecan spray application:0.15 lbs ai/A x 5 applications at 14 day intervals 

• Apple spray application:0.2 lbs ai/A x 4 applications at 7 day intervals 

• Grape spray application:0.175 lbs ai/A x 4 applications at 7 day intervals 
ECOLOGICAL EFFECTS HAZARD ASSESSMENT

The information in the following assessment is based on studies either conforming or conducted 

to meet EPA data requirements. Based of the ecological effects data, the toxicity potential of 

kresoxim methyl can be characterized as follows: 

• Avian acute: practically non-toxic (LD50>2150 mg/Kg) 

• Avian dietary: practically non-toxic (LC50>5000 ppm) 

• Avian reproduction: effects of significant increase in eggs cracked and decrease in eggs 

laid (NOAEC=500 ppm) 

• Mammalian acute: practically non-toxic (LD50>5000 mg/Kg) 

• Mammalian reproduction: effects of systemic toxicity (NOAEC=10,000 ppm) 

• Non-target insect: practically non-toxic (LD50>25 ug/bee)

• Fish (freshwater) acute: highly toxic (LC50=0.19 to 0.499 ppm) 

• Fish (freshwater) chronic: effects of decreased survival and growth (NOAEC=0.087 ppm) 

• Fish (estuarine/marine) acute: moderately toxic(LC50=1.173 ppm) 

• Invertebrate (freshwater) acute: highly toxic (LC50/EC50=0.332 mg/L) 

• Invertebrate (freshwater) chronic: effects of decreased reproduction and growth 

(NOEAC=0.055 ppm) 

• Invertebrate (estuarine/marine) acute: very highly toxic (LC50/EC50=0.015 to 0.059 ppm)

• Tier I/II plant toxicity:Lettuce EC25=0.30lb ai/A; aquatic plant 120 hr EC50=0.029 to 

>0.305 ppm

Based of the available ecological effects data, the aquatic toxicity potential of the degradate BF 

490-1 can be characterized as follows:

• Fish (freshwater) acute: practically non-toxic (LC50 > 100 ppm)

• Invertebrate (freshwater) acute: practically non-toxic (EC50 > 100 ppm)

For a more complete listing of these and other toxicity studies, please see Appendix I.

17 
18 

ECOLOGICAL RISK ASSESSMENT

Risks to Nontarget Terrestrial Organisms

There are minimal risk concerns for terrestrial organisms. Kresoxim methyl was practically nontoxic to both avian and mammalian species on an acute basis. No acute or chronic LOCs were 

exceeded for either avian or mammalian species for either single or multiple applications. 

No data are available on the toxicity of the degradate BF 490-1 to terrestrial organisms. 

However, based on the low toxicity seen in studies with the parent compound, and the fact that 

kresoxim methyl rapidly metabolizes to the degradate, it is assumed that any toxic effects from 

the degradate would have been exhibited in the toxicity studies utilizing the parent. In addition, 

the degradate was shown to be practically non-toxic to freshwater fish and invertebrates. Based 

on these points, it is assumed that BF 490-1 is also of no toxic concern to terrestrial organisms. 

Currently, EFED does not assess risk to nontarget insects. Results of acceptable studies are used 

for recommending appropriate label precautions. As kresoxim methyl appears to be practically 

non-toxic to honeybees, no risk is assumed. 

Risks to Nontarget Aquatic Organisms

There are minimal risk concerns for aquatic organisms. An analysis of the results indicate that no 

acute or chronic LOC’s were exceeded for freshwater fish or freshwater invertebrates. Also, no 

acute LOC’s were exceeded for estuarine/marine fish. However, restricted use and endangered 

species LOC’s for estuarine/marine invertebrates are exceeded for all proposed uses. No data 

were submitted to assess chronic risk to estuarine/marine fish and invertebrates. There were no 

high acute or endangered species terrestrial or aquatic plant LOC’s exceeded for any proposed 

use (RQ<LOC of 1.0). The metabolite (BF 490-1) is practically non-toxic to freshwater fish and 

invertebrates and poses minimal concern. 

Exposure and Risk to Endangered Species

There are no endangered species concerns from the proposed uses. Although potential risk to 

estuarine/marine invertebrates was identified, there are no invertebrate species listed as endangered. 

The Agency has developed a program (the “Endangered Species Protection Program”) to 

identify pesticides whose use may cause adverse impacts on endangered and threatened 

species, and to implement mitigation measures that will eliminate the adverse impacts. At 
present, the program is being implemented on an interim basis as described in a Federal 

Register notice (54 FR 27984-28008, July 3, 1989), and is providing information to pesticide 

users to help them protect these species on a voluntary basis. As currently planned, the 

final program will call for label modifications referring to required limitations on pesticide 

uses, typically as depicted in county- specific bulletins or by other site-specific mechanisms 

as specified by state partners. A final program, which may be altered from the interim 

program, will be described in a future Federal Register notice. The Agency is not imposing 

label modifications at this time. Rather, any requirements for product use modifications 

will occur in the future under the Endangered Species Protection Program.

19 

RISK CHARACTERIZATION 

Based on the fact that kresoxim methyl rapidly degrades in soil and soil/water systems under 

both aerobic and anaerobic conditions, EFED concludes that the parent compound is unlikely to 

have adverse effects on the environment. However, since the major acid degradate (BF 490-1) 

has the physical/chemical characteristics in common with those pesticides that are known to 

leach to ground water or to move offsite to surface water (i.e., persistence and high mobility), the 

potential for BF 490-1 to reach to ground water and/or surface water exists, especially when it is 

applied to the field with alkaline soil, low organic matter, and high sand. Although there is 

concern about contamination of the resource, no risks associated with ground or surface water 

contamination have been identified. 

BF 490-1 could be formed at a very high level in various soils. Under aerobic metabolism 

conditions, BF 490-1 was detected not only in the acid North Carolina soils, but in the alkaline 

German soil. However, none of the soils at the field dissipation sites (3 studies in U.S. and 3 

studies in Canada) nor the lysimeter study sites had all of the characteristics mentioned above. 

Therefore, the fate of kresoxim methyl and BF 490-1 under the most vulnerable situations 

(especially in alkaline soils) can not be assessed. 

The hydrolysis degradation half-lives for kresoxim methyl show a strong pH dependence varying 

from stable at pH 5 to a half-life of 7 hours at pH 9. In the absence of other degradation 

pathways, this would lead to significant differences in the rate of kresoxim methyl degradation 

in environments with different pH values. However, in the case of kresoxim methyl, this 

variation is not seen because the aerobic and anaerobic degradation half-life values are in the 

range of 1 to 2 days, regardless of pH. Therefore the overall degradation rate is more dependent 

on metabolic than chemical processes. 

Kresoxim methyl poses practically no toxic risk to birds, mammals, or plants. Kresoxim methyl 
20 

could pose risks to estuarine invertebrates should the compound enter marine environments. 

However, due to the scope and nature of the proposed uses and label restrictions, EFED 

concludes there would be low risk to aquatic species. 

No data are available on the toxicity of the degradate BF 490-1 to terrestrial organisms. 

However, based on the low toxicity seen in studies with the parent compound, and the fact that 

kresoxim methyl rapidly metabolizes to the degradate, it is assumed that any toxic effects from 

the degradate would have been exhibited in the toxicity studies utilizing the parent. In addition, 

the degradate was shown to be practically non-toxic to freshwater fish and invertebrates. Based 

on these points, it is assumed that BF 490-1 is also of no toxic concern to terrestrial organisms.
21 

APPENDIX
22 

Appendix I: Ecological Toxicity Data

Toxicity testing reported in this section does not represent all species of bird, mammal, or 

aquatic organism. Only two 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. 

Estuarine/marine 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 toxicity are similar. The same assumption is used for fish and amphibians. 

Toxicity to Terrestrial Animals

Birds, Acute, Subacute and Chronic

Avian Acute Oral Toxicity

Species % ai LD50 (mg/kg) Toxicity 

Category 

MRID No. 

Author/Year 

Study 

Classification1

Northern bobwhite quail 

(Colinus virginianus)

94% >2150 Prac. non-toxic 438836-02 

Munk/1993 

Core

1

 Core (study satisfies guideline). Supplemental (study is scientifically sound, but does not satisfy guideline)

 

Since the LD50 is >2150 mg/kg, kresoxim methyl is practically non-toxic to upland gamebird 

species on an acute oral basis. The guideline (71-1) is fulfilled (MRID 438836-02). 

Avian Subacute Dietary Toxicity

Species % ai 5-Day LC50 

(ppm)1

Toxicity Category MRID No. 

Author/Year 

Study 

Classification 

Northern bobwhite quail 

(Colinus virginianus)

93.7% >5000 Prac. non-toxic 438642-23 

Munk/1993 

Core 

Mallard duck 

(Anas platyrhynchos)

94% >5000 Prac. non-toxic 438642-24 

Munk/1993 

Core

1

 Test organisms observed an additional three days while on untreated feed. 

Since the LC50's fall in the range above 5000 ppm, kresoxim methyl is practically non-toxic to 

avian species on a subacute dietary basis. The guideline (71-2) is fulfilled (MRID 438642-23 

and 438642-24). 
23 

Avian Chronic

Avian Reproduction

Species 

% ai 

NOEC/LOEC1

(ppm) 

LOEC 

Endpoints 

MRID No. 

Author/Year 

Study 

Classification 

Northern bobwhite quail 

(Colinus virginianus)

tech 500/1000 eggs cracked/ 

eggs laid 

438642-25 supplemental 

(reg. data; not 

reviewed) 

Mallard duck 

(Anas platyrhynchos)

94.3 1000/>1000 No effects 443410-03 supplemental

1 NOEC = No Observed Effect Concentration; LOEC = Lowest Observed Effect Concentration, ND = Not 

Determined

The registrant reported results of an avian reproduction study with the bobwhite quail (438642-

25) indicating effects (eggs cracked/eggs laid) occurring at the LOEC of 1000 ppm (NOEC=500 

ppm). The guideline (71-4) is fulfilled for the proposed uses (MRID# 438642-25 and 443410-

03).

Insects

 Nontarget Insect Acute Contact Toxicity 

Species % ai 

LD50 

(μg/bee) Toxicity Category 

MRID No. 

Author/Year 

Study Classification 

Honey bee 94.7 >25 prac. non-toxic 443410-30 supplemental

The reported results indicate that kresoxim methyl is practically non-toxic to bees on an acute 

contact basis. However, the report contained numerous typographical errors that need to be 

clarified before a complete review and verification of results can be achieved. The guideline 

(141-1) is not fulfilled. (MRID#443410-30) 

Mammal, Acute and Chronic

Mammalian Toxicity

Species 

% ai 

Test 

Type 

Toxicity 

Value 

Affected 

Endpoints 

MRID No. 

laboratory rat 

(Rattus norvegicus) 

tech Acute oral LD50=>5000 mg/kg N/A 438642-32 

Laboratory rat 

(Rattus norvegicus) 

tech Reproduction Repro. tox. NOEL= 

10,000 to >16,000 ppm 

systemic 

toxicity 

438642-53
24 

The results indicate that kresoxim methyl is practically non-toxic to small mammals on an acute 

oral basis. Results from a chronic study indicate reproductive toxicity at 10,000 to >16,000 ppm 

(MRID 438642-32 and 438642-53).

Toxicity to Freshwater Aquatic Animals

Freshwater Fish, Acute

Species/ 

(Flow-through or Static) 

% ai 96-hour 

LC50 (ppm) 

(measured/nominal) 

Toxicity 

Category 

MRID No. 

Author/Year 

Study 

Classification 

Rainbow trout 

(Oncorhynchus mykiss)

Flow-through 

94.3% 0.19 (measured) Highly toxic 438642-27 

Graves et 

al./1995 

Core 

Bluegill sunfish 

(Lepomis macrochirus)

Flow-through 

94.3% 0.499 (measured) Highly toxic 438642-26 

Graves et 

al./1995 

Core

Since the LC50's fall in the range of 0.19-0.499 ppm, kresoxim methyl is highly toxic to 

freshwater fish on an acute basis. The results of a study (MRID 438642-28) using a metabolite 

(BAS 490-1) indicate that this metabolite is practically non-toxic to rainbow trout on an acute 

basis (LC50 > 100 ppm). The guideline (72-1) is fulfilled (MRID 438642-26 and 438642-27). 

Freshwater Fish, Chronic

Freshwater Fish Early Life-Stage Toxicity Under Flow-through Conditions 

Species % ai NOEC/LOEC (ppb) MATC

1

 (ppb) 

Endpoints 

Affected 

MRID No. Study 

Classification 

Fathead Minnow 

 (Pimephales 

promelus) 

94.3 87/160 118 survival and 

growth 

443410-08 Core

1 MATC = Maximum Allowed Toxic Concentration, defined as the geometric mean of the NOEC and LOEC. 

The guideline (72-4) is fulfilled (MRID 443410-08). The data indicate that kresoxim methyl 

significantly affected survival and growth at concentrations of 160 ppb and above. 
25 

Freshwater invertebrates, Acute

Species/(Static or 

Flow-through) 

% ai 48-hour LC50/ 

EC50 (ppm) 

(measured/ 

nominal) 

Toxicity Category MRID No. 

Author/Year 

Study 

Classification 

Waterflea 

(Daphnia magna)

Flow-through 

94.3 0.332 mg/L 

measured 

highly toxic 438642-30 

Graves et al. 

1995 

Core

 

Since the LC50/EC50 is 0.332 ppm, kesoxim methyl is highly toxic to aquatic invertebrates on an 

acute basis. The results of a study (MRID 438642-29) using a metabolite (BAS 490-1) indicate 

that this metabolite is practically non-toxic to aquatic invertebrates on an acute basis (EC50 > 

100 ppm). The guideline (72-2) is fulfilled (MRID 438642-30). 

Freshwater Invertebrate, Chronic

Freshwater Aquatic Invertebrate Life-Cycle Toxicity 

Species % ai 21-day 

NOEC/LOEC (ppb) 

MATC1

(ppb) 

Endpoints 

Affected 

MRID No. Study 

Classification 

Waterflea 

(Daphnia 

magna)

93.6 55/107 77 reproduction 

and growth 

443410-04 Core

1 Maximum Allowed Toxic Concentration, defined as the geometric mean of the NOEC and LOEC. 

The data indicate that kresoxim methyl significantly reduced growth and reproduction at 

concentrations equal to or greater than 107 ppb. Guideline (72-4) is fulfilled. (MRID# 443410-

04). 

Toxicity to Estuarine and Marine Animals

Estuarine and Marine Fish, Acute

Estuarine/Marine Fish Acute Toxicity 

Species % ai 96-hour LC50 (ppb) Toxicity 

Category 

MRID No. Study 

Classification 

Sheepshead minnow 

(Cyprinodon variegatus)

94.3 1173 (flow-through) moderately toxic 443410-05 Core

Since the LC50 is 1173 ppb, kresoxim methyl is considered to be moderately toxic to 

estuarine/marine fish on an acute basis. The guideline (72-3a) is fulfilled (MRID 443410-05). 
26 

Estuarine and Marine Invertebrates, Acute

Estuarine/Marine Invertebrate Acute Toxicity 

Species % ai. 96-hour 

LC50/EC50 (ppb) 

Toxicity 

Category 

MRID/Acc No. Study 

Classification 

Eastern oyster 

(shell deposition) 

(Crassostrea 

virginica)

94.3 14.7 Very highly toxic 443410-06 Core 

Mysid 

(Mysidopsis bahia)

94.3 59 Very highly toxic 443410-07 Core

Because the LC50 ranges from 14.7 to 59 ppb, the TGAI of kresoxim methyl is considered very 

highly toxic to estuarine/marine invertebrates on an acute basis. The guideline (72-3b and 72-

3c) is fulfilled (MRID 443410-06 and -07). 

Toxicity to Plants

Terrestrial Plant Toxicity 

Study type % ai Results MRID No. Study 

Classification 

Tier I Veg. Vigor non-target 

phytotoxicity 

94.7 When exposed to 0.35 lb ai/A, 

only lettuce was affected by 

more than 25% inhibition. The 

other 9 species tested were not 

affected by more than 25%. 

444210-02 Core

Tier I seed 

germination/seedling 

emergence non-target 

phytotoxicity 

94.7 None of the 10 species tested 

exposed to 0.35 lb ai/a were 

affected by 25% or more 

inhibition. 

443410-13 Core 

Tier II Veg. Vigor nontarget phytotoxicity 94.7 Only lettuce was tested due to 

the results of the Tier I test 

(MRID 444210-02). The EC25 

and NOEL for lettuce was 0.30 

and 0.18 lb ai/A, respectively. 

443410-16 Core

Aquatic Plant Toxicity 

Species % ai 120-hour EC50 

(ppm) 

CI MRID No. Study Classification 

Freshwater alga

(Anabaena flosaquae)

94.68 >0.295 N/A 443410-21 Core 
27 

Aquatic Plant Toxicity 

Species % ai 120-hour EC50 

(ppm) 

CI MRID No. Study Classification 

Freshwater Diatom 

(Navicula pelliculosa) 

94.7 0.0292 0.0245-

0.0473 

443410-18 Core 

Duckweed (Lemna 

gibba)

94.7 >0.305 

(14 day EC50) 

N/A 443410-17 Core 

Marine Diatom 

(Skeletonema costatum) 

94.68 >0.293 N/A 443410-19 Core 

Freshwater alga 

(Selenastrum 

capricornutum)

94.8 0.0551 0.0373-

0.0815 

443410-20 Core

The guidelines (122-2 and 123-2) for Tier I and II terrestrial and aquatic testing are fulfilled for 

the proposed use. In addition, a Tier I non-target aquatic plant toxicity study (MRID 443410-14) 

was submitted. The study was scientifically sound and fulfilled the guideline requirements for 

algal toxicity testing. S. capricornutum, N. pelliculosa, and S. costatum were the species tested 

that were affected by 50% or more and were subsequently tested under Tier II guidelines. 
28 

Appendix II: Terrestrial and Aquatic Exposure and Risk Assessment

Hoerger-Kenaga estimates are based on residue data correlated from more than 20 pesticides on 

more than 60 crops. Representative of many geographic regions (7 states) and a wide array of 

cultural practices, Hoerger-Kenaga estimates also considered differences in vegetative yield, 

surface/mass ratio and interception factors. In 1994, Fletcher, Nellessen and Pfleeger, 

reexamined the Hoerger-Kenaga estimates to determine whether the terrestrial EECs were 

accurate. They compiled a dataset of pesticide day-0 and residue-decay data involving 121 

pesticides (85 insecticides, 27 herbicides, and 9 fungicides from 17 different chemical classes) 

on 118 species of plants. After analyses, their conclusions were that Hoerger-Kenaga estimates 

needed only minor modifications to elevate the predictive values for forage and fruit categories 

from 58 to 135 and from 7 to 15. Otherwise, the Hoerger-Kenaga estimates were accurate in 

predicting the maximum residue values. In addition, their findings indicate that residue levels of 

persistent pesticides (applied as granules or powders) were very low in comparison to day-0 

values and that modification of these estimates to include decay or accumulation of pesticide 

over time following application is not justified. As a result, only 5 percent of actual residues will 

exceed the maximum values indicated. These values represent the arithmetic mean of values 

from samples collected the day of pesticide treatment. These values are the predicted 0-day 

maximum and mean residues of a pesticide that may be expected to occur on selected avian, 

mammalian or reptilian food items immediately following a direct single application at a 1 lb ai/a 

application rate. 

In 1995, additional testing of the validity of the Hoerger-Kenaga simple linear model was also 

performed by Pfleeger, Fong, Hayes, Ratsch and Wickliff using field data. Regarding a simple 

linear relationship between application rate and residue level, Pflegger and his team concluded 

that assumption is questionable, rather the relationship between the application rate (x) and 

pesticide residue (y) is a polynomial function with a degree of 2, y=Ax2

+Bx+C, where A, B and 

C are coefficients of the various vegetation categories. Therefore, the Hoerger-Kenaga simple 

linear model should be modified as recommended by Fletcher, and these values would be 

predictive of 90 percent of the residues ranging from 0.05 to 2.5 lb ai/acre. However, at rates 

greater than 2.5 lb ai/acre, the modified Hoerger-Kenaga values could be underestimates, 

especially for tall grass. Pflegger’s research team, performed regression analyses on the 

collected field data. As the regression lines were extrapolated out to represent increasing rates of 

application, tall grass, short grass, and forage plants exceeded Hoerger-Kenaga values at 

application rates greater than 2.5, 6.0, and 4.0 lb ai/acre, respectively. 

 In addition, the modified Hoerger-Kenaga linear model does not contain information on 

expected residues after day 0; it assumes that residues will degrade, and the maximum residue 

levels will occur on the day of application. Overall, Pfleeger’s data supported this assumption 

with a few exceptions, one exception being systemic pesticides. Systemic pesticides may 

accumulate in particular plant parts at higher concentrations, especially after irrigation or a rain 

event. Fletcher and his research team also investigated pesticide residue decay over time for a 

number of pesticides applied at rates between 0.5 and 1.5 lb ai/acre. Decay occurred 

exponentially after day 0, with the exception of systemic pesticides. With systemic pesticides, 

no exponential decay occurred over the first 30-to-40 days following application. 
29 

Risk to Nontarget Animals

A means of integrating the results of exposure and ecotoxicity data is called the quotient method. 

 For this method, risk quotients (RQs) are calculated by dividing exposure estimates by 

ecotoxicity values, both acute and chronic. 

RQ = EXPOSURE/TOXICITY 

RQs are then compared to OPP's levels of concern (LOCs). These LOCs are criteria used by 

OPP to indicate potential risk to nontarget organisms and the need to consider regulatory action. 

 The criteria indicate that a pesticide used as directed has the potential to cause adverse effects 

on nontarget organisms. LOCs currently address the following risk presumption categories: (1) 

acute high - potential for acute risk is high, regulatory action may be warranted in addition to 

restricted use classification (2) acute restricted use - the potential for acute risk is high, but this 

may be mitigated through restricted use classification (3) acute endangered species - the 

potential for acute risk to endangered species is high, regulatory action may be warranted, and 

(4) chronic risk - the potential for chronic risk is high, regulatory action may be warranted. 

Currently, EFED does not perform assessments for chronic risk to plants, acute or chronic risks 

to nontarget insects, or chronic risk from granular/bait formulations to mammalian or avian 

species. 

The ecotoxicity test values (i.e., measurement endpoints) used in the acute and chronic risk 

quotients are derived from the results of required studies. Examples of ecotoxicity values 

derived from the results of short-term laboratory studies that assess acute effects are: (1) LC50

(fish and birds) (2) LD50 (birds and mammals) (3) EC50 (aquatic plants and aquatic invertebrates) 

and (4) EC25 (terrestrial plants). Examples of toxicity test effect levels derived from the results 

of long-term laboratory studies that assess chronic effects are: NOAEC (terrestrial and aquatic 

organisms). Other values may be used only when justified. Generally, the NOAEC is used as 

the ecotoxicity test value in assessing chronic effects to fish and aquatic invertebrates. 
30 

Risk presumptions, along with the corresponding RQs and LOCs are tabulated below. 

Risk Presumptions for Terrestrial Animals

Risk Presumption RQ LOC

Birds 

Acute High Risk EEC1

/LC50 or LD50/sqft2 or LD50/day3 0.5 

Acute Restricted Use EEC/LC50 or LD50/sqft or LD50/day (or LD50 < 50 mg/kg) 0.2 

Acute Endangered Species EEC/LC50 or LD50/sqft or LD50/day 0.1 

Chronic Risk EEC/NOEC 1 

Wild Mammals 

Acute High Risk EEC/LC50 or LD50/sqft or LD50/day 0.5 

Acute Restricted Use EEC/LC50 or LD50/sqft or LD50/day (or LD50 < 50 mg/kg) 0.2 

Acute Endangered Species EEC/LC50 or LD50/sqft or LD50/day 0.1 

Chronic Risk EEC/NOEC 1 

1

 abbreviation for Estimated Environmental Concentration (ppm) on avian/mammalian food items 

2

 mg/ft2 3 mg of toxicant consumed/day

 LD50 * wt. of bird LD50 * wt. of bird 

 

Risk Presumptions for Aquatic Animals 

Risk Presumption RQ LOC

Acute High Risk EEC1

/LC50 or EC50 0.5 

Acute Restricted Use EEC/LC50 or EC50 0.1 

Acute Endangered Species EEC/LC50 or EC50 0.05 

Chronic Risk EEC/MATC or NOEC 1 

1

 EEC = (ppm or ppb) in water 

Risk Presumptions for Plants

Risk Presumption RQ LOC

Terrestrial and Semi-Aquatic Plants 

Acute High Risk EEC1

/EC25 1 

Acute Endangered Species EEC/EC05 or NOEC 1 

Aquatic Plants 
31 

Acute High Risk EEC2/EC50 1 

Acute Endangered Species EEC/EC05 or NOEC 1 

1

 EEC = lbs ai/A 

2

 EEC = (ppb/ppm) in water 

Terrestrial Risk Assessment 

Birds: Acute and Chronic 

Non-Granular products: The agency estimated peak residues (EEC’s) for a single and multiple 

applications of kresoxim methyl on apples and pecans by using the predicted maximum residue 

values to assess acute and chronic risk to birds and mammals. 

The acute and chronic risk quotients for single broadcast applications of nongranular products 

are 

tabulated below. 

 

Avian Acute and Chronic Risk Quotients for Single Application of Nongranular Products (Broadcast) Based on 

a quail LC50 of 5000 ppm and a quail reproductive NOEC of 500 ppm. 

Site/App. Method 

App. 

Rate 

(lbs ai/A) Food Items 

Maximum EEC 

(ppm) 

Acute RQ 

(EEC/ 

LC50) 

Chronic 

RQ 

(EEC/ 

NOEC) 

Short 

grass 

48 0.01 0.10 

Tall 

grass 

22 0.00 0.04 

Broadleaf 

plants/Insects 

27 0.01 0.05 

Apple 0.2 

Seeds 3 0.00 0.01 

Short 

grass 

36 0.01 0.07 

Tall 

grass 

17 0.00 0.03 

Broadleaf 

plants/Insects 

20 0.00 0.04 

Pecan 0.15 

Seeds 2 0.00 0.00 

An analysis of the results indicate that for a single broadcast application of nongranular products, 

acute and chronic levels of concern are not exceeded at registered maximum application rates. 

The acute and chronic risk quotients for multiple broadcast applications of nongranular products 

are tabulated below. 
32 

Avian Acute and Chronic Risk Quotients for Multiple Applications of Nongranular Products (Broadcast) 

Based on a quail LC50 of 5000 ppm and a quail reproductive NOEC of 500 ppm. 

Site/App. 

Method 

App.Rate 

(lbs ai/A)/ 

No. of Apps. 

Food Items 

Maximum 

EEC1

 (ppm) 

Acute RQ 

(EEC/ 

LC50) 

Chronic 

RQ 

(EEC/ 

NOEC) 

Short 

grass 

76 0.02 0.15 

Tall 

grass 

35 0.01 0.07 

Broadleaf 

plants/Insects 

43 0.01 0.09 

Apple 0.2/4 

Seeds 5 0.00 0.01 

Short 

grass 

42 0.01 0.08 

Tall 

grass 

19 0.00 0.04 

Broadleaf 

plants/Insects 

24 0.00 0.05 

Pecan 0.15/5 

Seeds 3 0.00 0.01 

1 Assumes degradation using FATE program using a 1 day half-life. 

An analysis of the results indicate that for multiple broadcast applications of nongranular 

products, acute and chronic levels of concern are not exceeded at registered maximum 

application rates. 
33 

Mammals 

Mammalian Acute and Chronic Risk Quotients for Multiple Applications of Nongranular 

Products (Broadcast) Based on a calculated rat LC50 of 100,000 ppm (LD50/% body wt 

consumed=5000/0.05) and a rat reproductive NOEC of 10,000 ppm. 

Site/App. Method 

App.Rate 

(lbs ai/A)/ 

No. of Apps. 

Food Items 

Maximum 

EEC1

 (ppm) 

Acute RQ 

(EEC/ 

LC50) 

Chronic 

RQ 

(EEC/ 

NOEC) 

Short 

grass 

76 0.00 0.01 

Tall 

grass 

35 0.00 0.00 

Broadleaf 

plants/Insects 

43 0.00 0.00 

Apple 0.2/4 

Seeds 5 0.00 0.00 

Short 

grass 

42 0.00 0.00 

Tall 

grass 

19 0.00 0.00 

Broadleaf 

plants/Insects 

24 0.00 0.00 

Pecan 0.15/5 

Seeds 3 0.00 0.00 

1 Assumes degradation using FATE program using a 1 day half-life. 

An analysis of the results indicate that for multiple broadcast applications of nongranular 

products, acute and chronic levels of concern are not exceeded at registered maximum 

application rates.

Exposure and Risk to Nontarget Freshwater and Estuarine/Marine Animals

Freshwater Fish

Acute and chronic risk quotients are tabulated below. 

Kresoxim methyl: 

Risk Quotients for Freshwater Fish Based On a rainbow trout LC50 of 0.19 ppm and a fathead minnow 

NOEC of 0.087 ppm.

Site 

EEC 

Initial/Peak 

(ppm) 

EEC 

56 day Ave. 

(ppm) 

Acute RQ 

(EEC/LC50) 

Chronic RQ 

(EEC/NOEC) 
34 

Kresoxim methyl: 

Risk Quotients for Freshwater Fish Based On a rainbow trout LC50 of 0.19 ppm and a fathead minnow 

NOEC of 0.087 ppm.

Site 

EEC 

Initial/Peak 

(ppm) 

EEC 

56 day Ave. 

(ppm) 

Acute RQ 

(EEC/LC50) 

Chronic RQ 

(EEC/NOEC) 

Apples 0.00595 0.00026 0.03 0.00 

Grapes 0.0052 0.00022 0.03 0.00 

Pecans 0.00442 0.00019 0.00 0.00

BF 490-1:

Risk Quotients for Freshwater Fish Based On a rainbow trout LC50 of 100 ppm.

Site EEC 

Initial/Peak (ppm) 

Acute RQ 

(EEC/LC50) 

Apples 0.0138 0.00

An analysis of the results indicate that no LOC’s are exceeded for freshwater fish. 

Freshwater Invertebrates

The acute and chronic risk quotients are tabulated below. 

Kresoxim methyl:

Risk Quotients for Freshwater Invertebrates Based On a daphnia EC50/LC50 of 0.332 ppm and a daphnia 

NOEC of 55 ppb.

Site 

EEC 

Initial/Peak 

(ppm) 

EEC 

21-Day 

Average (ppm) 

Acute RQ 

(EEC/LC50) 

Chronic RQ 

(EEC/NOEC) 

Apples 0.00595 0.00068 0.02 0.01 

Grapes 0.0052 0.0006 0.02 0.01 

Pecans 0.00442 0.00051 0.01 0.01

 
35 

BF 490-1:

Risk Quotients for Freshwater Invertebrates Based On a daphnia EC50 of 100 ppm.

Site EEC 

Initial/Peak (ppm) 

Acute RQ 

(EEC/EC50) 

Apples 0.0138 0.00

 

An analysis of the results indicate that no LOC’s are exceeded for freshwater invertebrates.

Estuarine and Marine Fish

The acute risk quotients are tabulated below. No data were submitted to assess chronic risk. 

Risk Quotients for Estuarine/Marine Fish based on a sheepshead minnow LC50 of 1.173 ppm.

Site 

EEC 

Initial/ 

Peak 

(ppm) 

Acute RQ 

(EEC/LC50) 

Chronic RQ 

(EEC/NOEC or MATC) 

Apples 0.00595 0.01 ?? 

Grapes 0.0052 0.00 ?? 

Pecans 0.00442 0.00 ?? 

An analysis of the results indicate that no acute risk LOC’s are exceeded. No data were 

submitted to assess chronic risk.

 

Estuarine and Marine Invertebrates

The acute risk quotients are tabulated below. No data were submitted to assess chronic risk. 

Risk Quotients for Estuarine/Marine Aquatic Invertebrates based on an Eastern oyster LC50/EC50 of 

0.0147 ppm.

Site/ 

Application Method 

EEC 

Initial/ 

Peak 

(ppm) 

Acute RQ 

(EEC/LC50) 

Chronic RQ 

(EEC/NOEC) 

Apples 0.00595 0.40 ?? 

Grapes 0.0052 0.35 ?? 

Pecans 0.00442 0.30 ?? 

An analysis of the results indicate that restricted use and endangered species LOC’s for 

estuarine/marine invertebrates are exceeded for all proposed uses. No data were submitted to 
36 

assess chronic risk.

Terrestrial and Aquatic plants 

Risk Quotients for Terrestrial plants based on a lettuce EC25 of 72ppm (240 x 0.3 lbs ai/A) and 

for aquatic plants, based on the Freshwater Diatom (Navicula pelliculosa) EC50 of 0.0292 ppm.

Site EEC 

Initial/Peak (ppm) 

Terrestrial Acute RQ 

(EEC/NOEC) 

Aquatic 

Acute RQ 

(EEC/LC50) 

Apples 0.00595 0.00 0.20 

Grapes 0.0052 0.00 0.18 

Pecans 0.00442 0.00 0.15 

An analysis of the results indicate that no high acute or endangered species terrestrial or aquatic 

plant LOC’s are exceeded for any proposed use (RQ<LOC of 1.0). 
37 

Appendix III: GENEEC for Ecological Aquatic Effects Assessment

 APPLES 

 RUN No.1 FOR kresoxim-methyl INPUT VALUES 

 -------------------------------------------------------------------- 

 RATE (#/AC) APPLICATIONS SOIL SOLUBILITY % SPRAY INCORP 

 ONE(MULT) NO.-INTERVAL KOC (PPM) DRIFT DEPTH(IN) 

 -------------------------------------------------------------------- 

 .200( .202) 4 7 249.0 2.0 1.0 .0 

 FIELD AND STANDARD POND HALFLIFE VALUES (DAYS) 

 -------------------------------------------------------------------- 

 METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINED 

 (FIELD) RAIN/RUNOFF (POND) (POND-EFF) (POND) (POND) 

 -------------------------------------------------------------------- 

 1.00 0 N/A 37.20- 4564.44 1.30 1.30 

 GENERIC EECs (IN PPB) 

 -------------------------------------------------------- 

 PEAK AVERAGE 4 AVERAGE 21 AVERAGE 56 

 GEEC DAY GEEC DAY GEEC DAY GEEC 

 -------------------------------------------------------- 

 5.95 3.17 .68 .26 

 GRAPES 

 RUN No.2 FOR kresoxim-methyl INPUT VALUES 

 -------------------------------------------------------------------- 

 RATE (#/AC) APPLICATIONS SOIL SOLUBILITY % SPRAY INCORP 

 ONE(MULT) NO.-INTERVAL KOC (PPM) DRIFT DEPTH(IN) 

 -------------------------------------------------------------------- 

 .175( .176) 4 7 249.0 2.0 1.0 .0 

 FIELD AND STANDARD POND HALFLIFE VALUES (DAYS) 

 -------------------------------------------------------------------- 

 METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINED 

 (FIELD) RAIN/RUNOFF (POND) (POND-EFF) (POND) (POND) 

 -------------------------------------------------------------------- 

 1.00 0 N/A 37.20- 4564.44 1.30 1.30 

 GENERIC EECs (IN PPB) 

 -------------------------------------------------------- 

 PEAK AVERAGE 4 AVERAGE 21 AVERAGE 56 

 GEEC DAY GEEC DAY GEEC DAY GEEC 

 -------------------------------------------------------- 

 5.20 2.77 .60 .22 
38 

 PECANS 

 RUN No.3 FOR kresoxim-methyl INPUT VALUES 

 -------------------------------------------------------------------- 

 RATE (#/AC) APPLICATIONS SOIL SOLUBILITY % SPRAY INCORP 

 ONE(MULT) NO.-INTERVAL KOC (PPM) DRIFT DEPTH(IN) 

 -------------------------------------------------------------------- 

 .150( .150) 5 14 249.0 2.0 1.0 .0 

 FIELD AND STANDARD POND HALFLIFE VALUES (DAYS) 

 -------------------------------------------------------------------- 

 METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINED 

 (FIELD) RAIN/RUNOFF (POND) (POND-EFF) (POND) (POND) 

 -------------------------------------------------------------------- 

 1.00 0 N/A 37.20- 4564.44 1.30 1.30 

 GENERIC EECs (IN PPB) 

 -------------------------------------------------------- 

 PEAK AVERAGE 4 AVERAGE 21 AVERAGE 56 

 GEEC DAY GEEC DAY GEEC DAY GEEC 

 -------------------------------------------------------- 

 4.42 2.36 .51 .19 
39 

Appendix IV: SCI-GROW for Environmental Fate Assessment

Background Information on SCI-GROW: 

SCI-GROW provides a ground water screening exposure value to be used in determining the 

potential risk to human health from drinking water contaminated with the pesticide. Since the 

SCI-GROW concentrations are likely to be approached in only a very small percentage of 

drinking water sources, i.e., highly vulnerable aquifers, it is not appropriate to use SCI-GROW 

concentrations for national or regional exposure estimates. 

SCI-GROW estimates likely ground water concentrations if the pesticide is used at the maximum 

allowable rate in areas where ground water is exceptionally vulnerable to contamination. In most 

cases, a large majority of the use area will have ground water that is less vulnerable to 

contamination that the areas used to derive the SCI-GROW estimate. 

SCI-GROW Printout for Use of Kresoxim methyl on Apples, Grapes, and Pecans:

 RUN No. 1 FOR kresoxim methyl INPUT VALUES 

 -------------------------------------------------------------------- 

 APPL (#/AC) APPL. URATE SOIL SOIL AEROBIC 

 RATE NO. (#/AC/YR) KOC METABOLISM (DAYS) 

 -------------------------------------------------------------------- 

 .200 4 .800 284.0 1.0 

 GROUND-WATER SCREENING CONCENTRATIONS IN PPB 

 -------------------------------------------------------- 

 .000312 

 -------------------------------------------------------- 

 A= .167 B= 289.000 C= -.778 D= 2.461 RILP= -1.915 

 F= -3.409 G= .000 URATE= .800 GWSC= .000312 

SCI-GROW Printout for BF 490-1 from The Use of Kresoxim methyl on Apples (Assuming 

Complete Conversion to BF 490-1):

Maximum application rate (0.2 lb ai/A) and 4 allowable application numbers: 

 RUN No. 1 FOR BF490-1 INPUT VALUES 

 -------------------------------------------------------------------- 

 APPL (#/AC) APPL. URATE SOIL SOIL AEROBIC 

 RATE NO. (#/AC/YR) KOC METABOLISM (DAYS) 

 -------------------------------------------------------------------- 

 .190 4 .760 43.0 131.0 

 GROUND-WATER SCREENING CONCENTRATIONS IN PPB 

 -------------------------------------------------------- 

 4.080070 

 -------------------------------------------------------- 

 A= 126.000 B= 48.000 C= 2.100 D= 1.681 RILP= 4.870 

 F= .730 G= 5.369 URATE= .760 GWSC= 4.080070 

Appendix V: Tier 2 Surface Water Site/Scenario for Use of Kresoxim Methyl on 
40 

Apples and Grapes

One site/scenario was used to represent a high runoff use area for Kresoxim Methyl use on 

apples and grapes. It represents a 10 hectare field draining into a 1 hectare pond, 2 meters deep 

with no outlet. Inflow to the pond from runoff are assumed to be exactly balanced by losses due 

to evaporation and seepage. On the site it is assumed that grass covers the surface below the 

apples/ grapes and that applied pesticide lands either on the crop or on the grass below and that 

washoff/ runoff occurs from either source. 

The site is an orchard/vineyard in Columbia County, New York in MLRA 144B. The soil at the 

site is a Cabot silt loam. Data for this soil was taken from the PIC database and the 1987 

National Resources Inventory. A Cabot silt loam is hydrologic group D soil and SCS curve 

numbers were generated based on this grouping and the plant cover. A total of 4794 acres of 

apples were grown in Columbia County in 1987 (US Department of Commerce). Weather data 

was taken from weather station W04725 in Albany, NY. The weather data file is part of the 

PRZM program and is used to represent the weather for MLRA R-144B. This site receives an 

annual average precipitation of about 93 cm of which 19% on the average leaves site as runoff. 

The chemical specific parameters used in PRZM3 and EXAMS to describe the scenario are 

tabulated in Table 2 attached. The site was selected to represent orchards and vineyards in the 

eastern United States that are likely to present high exposure to aquatic organisms. 

Procedure

The PRZM simulation was run using 36 years of weather data encompassing the years from 

1948 to 1983. The modeling assumed application of the pesticide four times per year both for 

apples and for grapes at the maximum allowable rate permitted by the label. This scenario 

assumes 5% spray drift directly to the pond with the remainder of the chemical reaching the 

water through runoff from rainfall events. The maximum concentration values in Table 1 above 

are the one-in-ten year return period values taken the REPORT.XMS file produced by EXAMS. 

These 10 year return concentrations (or 10% yearly exceedence EEC's) were calculated by linear 

interpolation between the third and fourth largest values. 
41 

Appendix VI: Summary of Submitted Environmental Fate Studies 

1. Degradation

161-1 Hydrolysis

The submitted study (Bieber.; 1992; MRID 43864268) on the hydrolysis of kresoxim 

methyl is acceptable and the Hydrolysis (161-1) data requirement is fulfilled. 

Results from this study are summarized below: 

"[14C]kresoxim methyl, at approximately 0.23 mg/L, was hydrolytically stable in 

pH 5 sterile, aqueous buffer solution incubated in darkness at 25 ± 1°C for 30 

days. In sterile, aqueous pH 7 buffer solution, kresoxim methyl hydrolyzed with 

a half-life of 34 days. Following 30 days of incubation, kresoxim methyl was 

present in pH 7 buffer solution at a concentration of 53.9% of the applied 

radioactivity. The major degradate (BF 490-1; the free acid of BAS 490 F) was 

first detected at 8 hours posttreatment at a concentration of 1.7% of the applied, 

and increased to 45.3% by 30 days posttreatment. In sterile, aqueous pH 9 buffer 

solution, kresoxim methyl hydrolyzed with a half-life of 7 hours. Parent 

kresoxim methyl was present at 16.6% of the applied radioactivity following one 

day of incubation, and was <1% of the applied by 4 days posttreatment. The 

major degradate BF 490-1 was present at 1.4% of the applied at time 0, increased 

to 100% of the applied by 3 days posttreatment, and was present at concentrations 

ranging from 95.3 to 100% for the remainder of the study period. The material 

balances for the pH 5, 7 and 9 test systems ranged from 97.2-103.2% throughout 

the study period." 

161-2 Photolysis in Water

The submitted studies (Goetz and Reese. 1995; MRID 44341032; Goetz, et. al. 1994; 

MRID 44341031) on the photodegradation of kresoxim methyl in water are acceptable 

and the Photolysis in Water (161-2) data requirement is fulfilled. 

Results from these studies are summarized below: 

“Uniformly phenyl ring-labeled [A-14C]kresoxim methyl, at concentrations of 1.75 ppm 

or 1.78 ppm, degraded with a half-life of 14.8 days (based on the 12 hours light/12 hours 

dark cycle) in pH 5 acetate buffer solution which was irradiated continuously with a 

xenon arc lamp for 360 hours while maintained at approximately 25 oC. Based on the 

continuous irradiation, the half-life would be 7.4 days. In contrast, the parent compound 

was photolytically stable in the dark control solution. Based on HPLC analysis of the 

irradiated solutions, the parent compound was initially present at 91.7% of the applied 

radioactivity, decreased to 48.0% of the applied by 167 hours posttreatment and was 

20.9% of the applied at 360 hours posttreatment. In the dark control, the parent 
42 

compound was present at 95.3% of the applied radioactivity at 360 hours. In the 

irradiated solution, an unidentified major degradate was a maximum of 12.7% of the 

applied radioactivity at 167 hours posttreatment and was 6.7% at 360 hours. The minor 

degradate BF 490-Z (BAS 490 F Z-isomer) was present at a maximum of 5.0% of the 

applied radioactivity at 48 hours posttreatment. [14C]Organic volatiles were a maximum 

of 5.0% of the applied radioactivity at 263 hours posttreatment. 14CO2 accounted for a 

maximum of 7.9% of the applied radioactivity at 360 hours posttreatment. Material 

balances for the irradiated samples were 99.0-103.0% of the applied radioactivity from 0 

to 167 hours posttreatment and generally decreased with time to 92.9-93.8% by 215-263 

hours and 89.3% by 360 hours posttreatment. For the dark control sample, the material 

balance was 104.0% of the applied radioactivity”. 

“Uniformly phenyl ring-labeled [B-14C]kresoxim methyl, at a concentration of 1.7-2.1 

ppm, degraded with a half-life of 59.6 days (based on 12 hours light/12 hours dark cycle) 

in pH 5 acetate buffer solution which was irradiated continuously with a xenon arc lamp 

for 370 hours while maintained at approximately 25 oC. In contrast, the parent compound 

was photolytically stable in the dark control solution. Based on TLC analysis of the 

irradiated solutions, the parent compound was initially present at 91.9% of the applied 

radioactivity, decreased to 73.2% of the applied by 161 hours posttreatment and was 

55.7% of the applied at 370 hours posttreatment. In the dark control, the parent 

compound was present at 91.0% of the applied radioactivity at 370 hours posttreatment. 

In the irradiated solution, the minor degradate BF 490-Z (BAS 490 F Z-isomer) was 

present at a maximum of 4.8% of the applied radioactivity at 43 hours posttreatment. 

[

14C]Volatiles were negligible. Material balances for the irradiated samples were 97.6-

99.0% of the applied radioactivity at 0-206 hours posttreatment and decreased to 90.0% 

of the applied by 360 hours posttreatment (Table 9, p. 36). For the dark control samples, 

the material balance was 97.1% of the applied radioactivity”. 

161-3 Photolysis on Soil

The submitted study (McKenna. 1994; MRID 44341033) on the photolysis of kresoxim 

methyl on soil is acceptable and the Photolysis on Soil (161-3) data requirement is 

fulfilled. 

Results from this study are summarized below: 

“Phenyl ring-labeled [14C]kresoxim methyl degraded slowly on sandy loam soil 

that was irradiated continuously at 25°C for 15 days in a Hanau Suntest Unit 

equipped with a xenon arc lamp. The lamp had an emission spectrum of 300-800 

mm, and a total light intensity of 765 watts/m2

 ; based on the sunlight intensity on 

9/12/93 at 12:15 pm on a clear day in Research Triangle park, NC. Kresoxim 

methyl degraded very slowly in the irradiated sandy loam soil treated with 

phenyl ring-labeled [14C]kresoxim methyl, with a half-life of 35.2 days under 

continuous irradiation (or 70.4 days based on the 12 hours irradiation/12 hours 

dark cycle). Two degradates were identified after 360 hours of irradiation: BF 

490-Z (4% of the applied) and BF 490-1 (2.4% of the applied).” 
43 

2. Metabolism

162-1 Aerobic Soil Metabolism

 Four studies (Kellner. 1994. MRID 4386269; Kellner. 1995. MRID 43864270; Kellner. 

1994. MRID 4386271; McKenna and Billotte. 1997. MRID 44539707) were submitted to 

satisfy the Aerobic Soil Metabolism data requirement. Although all four studies are 

scientifically valid, only one study (Kellner. 1995. MRID 4386271) can be used to meet 

Subdivision N Guidelines for the fulfillment of EPA data requirements on aerobic soil 

metabolism. 

The second study (MRID 43864270) is a continuation (providing data for one additional 

sampling interval) of the first study (MRID 43864269) which examined the aerobic soil 

metabolism of uniformly phenyl-ring labeled [14C]kresoxim methyl {(E)-2-[2-(2-

methylphenoxy)-methyl]-phenyl-2-(methoxyimido)acetic acid methyl ester; label B} in a 

German sandy loam soil. The third study (MRID 43864271) examines the aerobic soil 

metabolism of uniformly phenoxy ring-labeled [14C]kresoxim methyl in a North Carolina 

sandy loam soil. 

Results from these studies are summarized below: 

Studies 1 and 2 (Kellner. 1994. MRID 4386269; Kellner. 1995. MRID 43864270): 

These studies are scientifically valid and provides useful information on the aerobic soil 

metabolism of kresoxim methyl (BAS 490 F). However, this study does not meet Subdivision N 

Guidelines for the fulfillment of EPA data requirements on aerobic soil metabolism for the 

following reasons: 

(1) the soil does not represent the typical use area in the U.S.; 

(2) the soil was moistured and maintained at 40% of the maximum water holding 

capacity (instead of 75% of field capacity as required by the subdivision N 

Guidelines). 

 

"Uniformly phenyl ring-labeled kresoxim methyl, at 0.5 mg/kg, degraded very 

rapidly in moistened (German) sandy loam soil incubated in darkness at 20 ± 1°C 

for up to 273 days (with a half-life of less than 1 day). Parent kresoxim methyl 

decreased to 25.6% (0.129 mg/kg) of the applied radioactivity by 1 day 

posttreatment and was 1.0% (0.005 mg/kg) of the applied at 273 days 

posttreatment. The major nonvolatile degradate, BF 490-1 {(E)-2-[2-(2-

methylphenoxy)methyl]-phenyl-2-(methoxyimido)acetic acid; the free acid of 

BAS 490 F}, was present at a maximum concentration of 80.4% (0.405 mg/kg) at 

2 days posttreatment, then decreased to 3.2% (0.016 mg/kg) of the applied by 273 

days posttreatment. Radiolabeled 14CO2 accounted for 47.7% (0.240 mg/kg) of 

the applied after 273 days of incubation; organic volatiles were not detected. 
44 

Study 3 (Kellner. 1994. MRID 4386271): 

This study is scientifically valid and can be used to meet Subdivision N Guidelines for the 

fulfillment of EPA data requirements on aerobic soil metabolism of kresoxim methyl. 

“Uniformly phenoxy ring-labeled kresoxim methyl, at 0.5 mg/kg, degraded very 

rapidly in moistened (North Carolina) sandy loam soil incubated in darkness at 20 

± 2°C for up to 364 days (with a half-life of less than 1 day). Parent kresoxim 

methyl decreased from an initial 0.349 mg/kg to 0.087 mg/kg by 1 day 

posttreatment and was 0.011 mg/kg at 364 days posttreatment. The major 

nonvolatile degradate, BF 490-1, was present at a maximum concentration of 

0.320 mg/kg at 2 days posttreatment, then decreased to 0.037 mg/kg by 364 days 

posttreatment. Radiolabeled 14CO2 accounted for 24.3% (0.116 mg/kg) of the 

applied after 364 days of incubation; organic volatiles were not detected." 

Study 4 (McKenna and Billotte. 1997. MRID 44539707): 

This study is scientifically valid and provides useful information on the aerobic soil metabolism 

of kresoxim methyl (BAS 490 F). However, this study does not meet Subdivision N Guidelines 

for the fulfillment of EPA data requirements on aerobic soil metabolism for the following 

reasons: 

(1) the reported half-life of the parent was determined based on a study in which an 

exaggerated dose rate was used. While exaggerated rate studies may be used for 

residue identification purposes, kinetics studies should be performed using the 

maximum application rate (USEPA. 1993. Pesticide Reregistration Rejection 

Rate Analysis: Environmental Fate. EPA 738-R-93-010, p. 67). The maximum 

proposed seasonal application rate of the parent is 0.8 lb a.i./acre. The application 

rate for the present study was 1.56 ppm (equivalent to 3.12 lbs ai/acre), which is 

almost 4 times the proposed maximum seasonal label rate. 

(2) The soil moisture was maintained at a level 16% higher than the required 

moisture level. Subdivision N Guidelines require that aerobic soil metabolism 

studies be performed at 75% of the soil moisture at 0.33 bar in order to ensure 

aerobic conditions and soil viability. The study authors reported that “the soil 

moisture at weighing for treatment was 8.2%” and “the soil moisture content was 

kept at this level by periodic addition of water during the study to maintain the 

initial soil weight” (pages 13 and 14). According to Figure A-1, the soil moisture 

at 0.33 bar was 9.4%. Therefore, 7% should have been the soil moisture used for 

this study. 

(3) The soil used in the aerobic soil metabolism study is a loamy sand which is not 

one of the two soils (sandy loam and silt loam) recommended in the Subdivision 

N Guidelines. 

“Uniformly phenyl ring-labeled [A-14C]kresoxim methyl, at a nominal application rate of 
45 

1.56 ppm, degraded with a registrant-calculated half-life of 2.3 days (r2

 = 0.96, reported 

as a DT50) in loamy sand soil incubated in darkness at 25 ± 1 o

C for up to 218 days. The 

degradation of the parent was biphasic. All data (designated as percentages of the 

applied) represent percentages of the nominal application. Concentration data for the 

parent compound are reviewer-calculated. Based on HPLC analysis, the parent 

compound was initially present at 102.0% (1.66 ppm) of the applied radioactivity, 

decreased to 45.2% (0.71 ppm) of the applied by 4 days posttreatment, varied from 

20.9% to 39.4% (0.33-0.61 ppm) at 7-14 days, then decreased to 3.5% (0.055 ppm) by 

218 days posttreatment. The major degradate BF 490-1 was a maximum of 57.2% of the 

applied radioactivity at 14 days posttreatment and was 5.6-7.6% from 98 to 218 days 

posttreatment. The major degradate BF 490-5 was a maximum of 19.4% of the applied 

radioactivity at 98 days posttreatment and was 9.0% at 218 days posttreatment. The 

minor degradate BF 490-Z (BAS 490 F Z-isomer) was present at 0.4-0.9% of the applied 

radioactivity from 29 to 218 days posttreatment. Nonextractable [14C]residues were a 

maximum of 43.6% of the applied radioactivity at 98 days and were 39.1% at 218 days; 

total [14C]residues (29-218 day samples) associated with humic acid, fulvic acid, and 

humin fractions were maximums of 12.4% (day 135), 16.3% (day 98), and 3.6% (day 

218) of the applied, respectively. Evolved 14CO2 was 27.2% of the applied following 218 

days of incubation; [14C]organic volatiles were negligible”. 

162-3 Anaerobic Aquatic Metabolism

The registrant submitted an anaerobic aquatic metabolism study (Bieber. 1995; MRID 

43864272) to support both the Anaerobic Soil and the Anaerobic Aquatic Metabolism 

data requirements. This study is acceptable and can be used to fulfill the Anaerobic Soil 

and the Anaerobic Aquatic Metabolism data requirements. 

Results from this study are summarized below: 

"A mixture of uniformly phenoxy ring-labeled [14C]kresoxim methyl (A-label) 

plus non-radiolabeled kresoxim methyl in acetonitrile or an undiluted mixture of 

uniformly phenyl ring-labeled [14C]kresoxim methyl (B-labeled), at 0.13 mg/kg of 

soil plus water, degraded with half-lives of 0.9 days and 1.3 days, respectively, in 

an anaerobic (nitrogen atmosphere) flooded sandy loam soil that was maintained 

in darkness at 20°C for 363 days. The concentration of parent [14C]kresoxim 

methyl in the A-label (phenoxy ring) flooded soil system decreased from 78.4% 

of the applied radioactivity at day 0 to 32.7% by 1 day posttreatment and 0.3% by 

7 days posttreatment. The major nonvolatile degradate BF 490-1 was at a 

maximum concentration of 90.7% of the applied at 7 days posttreatment and 

decreased continuously throughout the study to a concentration of 24.3% of the 

applied by 363 days posttreatment. The minor degradates BF 490-5 and BF 490-

9 were present at maximum concentrations of 1.9% (day 177) and 3.4% (day 62) 

of the applied, respectively. At 363 days posttreatment, 14CO2 accounted for 

41.4% of the applied radioactivity and unextracted [14C]residues comprised 

17.6% of the applied; volatile organic [14C]residues were <0.1% of the applied 

radioactivity. 
46 

The concentration of parent [14C]kresoxim methyl in the B-label (phenyl ring) 

flooded soil system decreased from 83.7% of the applied radioactivity at day 0 to 

24.4% by 1 day posttreatment and 1.5% by 7 days posttreatment. The major 

nonvolatile degradate BF 490-1 was at a maximum concentration of 91.5% of the 

applied at 14 days posttreatment and decreased continuously throughout the study 

to a concentration of 34.9% of the applied by 363 days posttreatment. The minor 

degradates BF 490-5, BF 490-9 and BF 490-14 were present at maximum 

concentrations of 1.8% (day 177), 4.6% (day 363) and 1.3% (day 90) of the 

applied, respectively. At 363 days posttreatment, 14CO2 accounted for 7.2% of 

the applied radioactivity and unextracted [14C]residues comprised 10.8% of the 

applied; volatile organic [14C]residues were <0.1% of the applied radioactivity." 

162-4 Aerobic Aquatic Metabolism

The submitted study (Bieber. 1993, MRID 43864273) is scientifically sound and can be 

used to fulfill the EPA data requirements on aerobic aquatic metabolism. It should be 

noted that the study was terminated prior to the pattern of the decline of the major 

degradate (BF 490-1) could be established. In both sediment/water systems, BF 490-1 

increased with time and reached to a maximum of 80-81% of the applied by 7 days 

posttreatment, then decreased to 73-76% of the applied by 30 days posttreatment and 68-

69% by 100 days posttreatment. 

Results from this study are summarized below: 

"A mixture of uniformly phenoxy ring-labeled [14C]kresoxim methyl 

(radiochemical purity >95%) plus non-radiolabeled kresoxim methyl dissolved in 

acetonitrile, at 0.17 mg/kg water, degraded with registrant-calculated half-lives of 

1.3 and 1.2 days, respectively, in aerobic, flooded German loam (Krempe) and 

sand (Ohlau) sediments that were incubated in darkness at 20 ± 1 or 2°C for 100 

days. 

In the Krempe water/sediment system, parent kresoxim methyl decreased from an 

initial 82.0% of the applied radioactivity to 47.5% by 1 day posttreatment and 

1.1% by 30 days posttreatment, and was 0.4% of the applied at 100 days 

posttreatment. The major nonvolatile degradate BF 490-1 was present at a 

maximum of 79.7% of the applied by 7 days posttreatment, then decreased to 

75.8% of the applied by 30 days posttreatment and 69.1% by 100 days 

posttreatment. At 100 days posttreatment, 14CO2 accounted for 7.7% of the 

applied radioactivity and nonextractable [14C]residues in the sediment phase 

comprised 11.9% of the applied; volatile organic [14C]residues were <0.1% of the 

applied radioactivity. 

In the Ohlau water/sediment system, parent kresoxim methyl decreased from an 

initial 84.3% of the applied radioactivity to 52.3% by 1 day posttreatment and 
47 

1.2% by 30 days posttreatment, and was 0.3% of the applied at 100 days 

posttreatment. The major nonvolatile degradate BF 490-1 was present at a 

maximum of 81.2% of the applied by 7 days posttreatment, then decreased to 

72.6% of the applied by 30 days posttreatment and 67.5% by 100 days 

posttreatment. At 100 days posttreatment, 14CO2 accounted for 10.1% of the 

applied radioactivity and nonextractable [14C]residues in the sediment phase 

comprised 7.2% of the applied; volatile organic [14C]residues were <0.1% of the 

applied radioactivity." 

3. Mobility/Leachability

163-1 Leaching-Adsorption/Desorption

Four studies (Goetz and Geiger. 1995; MRID 43864276; Keller. 1993; MRID 43864275; 

and Keller. 1991; MRID 43864274; Goetz and Mills. 1996; MRID 44341034) were 

submitted to satisfy the Leaching-Adsorption/Desorption data requirement. 

 

The first study (Goetz and Geiger. 1995; MRID 43864276) is scientifically valid and 

provides useful information on the soil mobility (batch equilibrium) of uniformly 

phenoxy-ring labeled [14C]kresoxim methyl {(E)-2-[2-(2-methylphenoxy)-methyl]-

phenyl-2-(methoxyimido)acetic acid methyl ester; BAS 490 F} in four soils. 

It should be noted that the soil used in the only accepted aerobic metabolism study 

(Kellner. 1994. MRID 43864271) was a sandy loam and this soil was not included in the 

adsorption/desorption study. However, the loamy sand soil (834-11-06) used in the 

adsorption/desorption study is very similar to the soil used in the aerobic soil metabolism 

study. 

Results from the first study are summarized below: 

"Uniformly phenoxy-ring labeled [14C]kresoxim methyl, at 0.049, 0.101, 0.205 

and 0.449 μg/mL, was determined to be relatively mobile in sand, loamy sand, 

loam, and clay soil:solution slurries (1:5, w:v) that were equilibrated in darkness 

for 60 minutes at 25 ±1°C. Freundlich Kads values were 0.93 for the sand soil, 

3.45 for the loamy sand soil, 6.49 for the loam soil and 10.52 for the clay soil; 

corresponding Koc values were 320, 541, 249 and 567, respectively. Respective 

Freundlich Kdes values determined following a 24-hour equilibration period were 

0.17, 0.78, 0.86 and 0.58; corresponding Koc values were not reported. 

Respective 1/n values were 1.20, 1.03, 1.00 and 0.96 for adsorption and 0.64, 

0.98, 1.02 and 1.02 for desorption. 

The second study (Keller. 1993; MRID 43864275) is not scientifically valid and can not 

be used to meet Subdivision N Guidelines for the fulfillment of EPA data requirements 

on mobility/batch equilibrium of the kresoxim methyl degradate BF 490-1 {(E)-2-[2-(2-

methylphenoxy)-methyl]-phenyl-2-(methoxyimido)acetic acid; the free acid of BAS 490 
48 

F} in soil. Reasons are: (1) the adsorption phase equilibration period (two hours) used 

for each soil was inadequate for complete equilibration; (2) the desorption phase of the 

experiment was not performed, and soils from the adsorption phase were simply 

extracted with methanol to determine the material balance; soil samples were not 

combusted; and (3) all soils used were foreign soils which were not completely 

characterized, precluding a full assessment of the validity of the submitted data for the 

purpose of determining adsorption in domestic soils. 

Results from this study are summarized below: 

"Uniformly phenyl-ring labeled [14C]BF 490-1, at nominal concentrations of 1.0, 

0.2, 0.04 and 0.008 mg/L, was determined to be very mobile in two German 

sandy loam, one German loamy sand and one German "clayey loam" soil:solution 

slurries (1:5, w:v) that were equilibrated at room temperature for two hours. 

However, the equilibration period was inadequate for complete adsorption. 

Freundlich Kads values for the two soils exhibiting adsorption were 0.62 for the 

sandy loam soil designated "Standard Soil 2.2" and 0.55 for the "clayey loam" 

soil designated "Bruch Ost"; corresponding Koc values were 24 and 17, 

respectively. Respective 1/n values associated with adsorption for the sandy loam 

and "clayey loam" soils were 0.94 and 0.91. Freundlich Kads values were not 

determined for the other two soils (Standard Soils 2.1 and 2.3) due to the low 

levels of adsorption which occurred." 

The third study (Keller. 1991; MRID 43864274) is not scientifically valid and does not 

provide useful information on the soil mobility (column leaching) of aged and unaged 

uniformly phenyl ring-labeled [14C]kresoxim methyl {(E)-2-[2-(2-methylphenoxy)-

methyl]-phenyl-2-(methoxyimido)acetic acid methyl ester; BAS 490 F} in one soil. The 

soil used in the column were too finely sieved (1.00 mm), so that a significant portion of 

the sand fraction (0.05-2.00 mm) may have been removed. Because residue 

concentration data for parent kresoxim methyl and its degradates before and after 

leaching were not presented, the validity of the mobility determination for the degradate 

BF 490-1 could not be adequately assessed. In addition, the columns were leached with 

20 cm of water rather than the required 50.8 cm. 

 

Results from this study are summarized below: 

"The mobility of parent kresoxim methyl and its degradates in German loamy 

sand soil could not be definitively determined because the individual residue 

concentrations were not reported for parent and degradates. Based on the results 

of TLC analysis of compounds present in soil column subsamples and leachates, 

the degradate BF 490-1 appeared to be very mobile, and even more mobile than 

the parent compound. In the aged residues study, radioactivity observed in the 

leachate from the two columns used was 56.7% and 58.4% of the applied 

radioactivity. In the unaged residues study, radioactivity observed in the leachate 

from the two columns used was 40.2% and 56.1% of the applied radioactivity." 
49 

The fourth study (Goetz and Mills. 1996; MRID 44341034) is scientifically valid and 

provides useful information on the soil mobility (batch equilibrium) of uniformly phenylring labeled [14C]BF 490-1 in three soils. 

Results from the fourth study are summarized below: 

"Uniformly phenyl-ring labeled [14C] BF 490-1 (the major degradate of kresoxim 

methyl), at 0.286, 0.569, 1.148, and 2.243 μg/mL, was determined to be very 

mobile in clay, loam, and loamy sand soil:solution slurries (1:5, w:v) that were 

equilibrated in darkness for 24 hours at 25 ±1°C. Freundlich Kads values were 

0.79 for the clay soil, 0.87 for the loam soil, and 0.44 for the loamy sand soil; 

corresponding Koc values were 44, 33, and 69, respectively. Respective 

Freundlich Kdes values determined following a 24-hour equilibration period were 

0.06, 0.43, and 0.19; corresponding Koc values were not reported. Respective 1/n 

values were 0.81, 0.84, and 0.75 for adsorption and 0.27, 0.76, and 0.25 for 

desorption. 

4. Fate of Kresoxim methyl in the Field

164-1 Field Dissipation

Two studies (Butterfield and Billotte. 1995; MRID 43883606; Jackson et al. 1996. MRID 

44421005) were submitted to satisfy the Field Dissipation data requirement. 

The first study (Butterfield and Billotte. 1995. MRID 43883606) is scientifically sound, 

but it does not meet Subdivision N Guidelines for the fulfillment of EPA data 

requirements on terrestrial field dissipation for the following reasons: 

* the registrant did not compare the total rainfall received between May and July at 

the study site with the average monthly rainfall for that region 

* the test site was too small 

* an insufficient number of samples were collected at each sampling period 

* the test substance was not applied according to the proposed label use directions 

* no analytical method validation data were reported; no control plots were used; 

and no chain-of-custody information was provided 

 

Results from the first study are summarized below: 

"Uniformly phenoxy-ring-labeled [14C]kresoxim methyl {methyl (E)-2-[2-(2-

methylphenoxy)-methyl]phenyl-2-(methoxyimido)acetic acid methyl ester; BAS 

490 F}, dissipated with a half-life of less than 4 days in a confined bare ground 

plot of loamy sand soil (based on the residues detected in the 0-3 inch soil zone) 

in Holly Springs, NC. The parent was present at a maximum concentration of 

0.932 ppm at day 0. 
50 

The major metabolite, (E)-2-[2-(2-methylphenoxy)-methyl]phenyl-2-

(methoxyimido) acetic acid (BF 490-1; acid metabolite), was present at a 

maximum concentration of 0.558 ppm at day 14. The Z-isomer of the parent (BF 

490-Z), present as a minor metabolite, reached a maximum concentration of 0.028 

ppm by day 8. A second minor metabolite, BF 490-5 {(E)-2-[2-(2-

carboxylphenoxy)methyl]phenyl-2-(methoxyimido)acetic acid}, was tentatively 

identified at a maximum mean concentration of 0.001 ppm at day 56, but was not 

confirmed. Four other unknown metabolites (Unknowns 1, 2, 3, and 4) were 

observed at maximums of ≤0.020 ppm each. Bound radioactive residues 

increased from 0.018 ppm at day 0 to 0.158 ppm at day 119 and were 

characterized mostly as humic components with trace amounts of parent, BF 490-

1, and unspecified polar compounds. 

Soils were not analyzed for the parent and its metabolites below the 3-inch depth 

because <10% of the applied radioactivity was detected below the 3-inch depth at 

any sampling interval. 

Uniformly phenyl-ring-labeled [14C]kresoxim methyl (BAS 490 F), dissipated 

with a half-life of less than 4 days in a confined bare ground plot of loamy sand 

soil in Holly Springs, NC. The parent was present at a maximum concentration of 

0.759 ppm at day 0. 

The major metabolite, BF 490-1 (acid metabolite), was present at a maximum 

mean concentration of 0.500 ppm at day 2. The Z-isomer of the parent (BF 490-

Z), present as a minor metabolite, reached a maximum mean concentration of 

0.033 ppm at day 8. A second minor metabolite, BF 490-5, was tentatively 

identified at a maximum mean concentration of 0.025 ppm at day 14. Four other 

unknown minor metabolites (Unknowns 1, 2, 3, and 4) were observed at 

maximums of ≤0.022 ppm each. Bound radioactive residues increased from 

0.023 ppm at day 0 to 0.142 ppm at day 119 and were characterized mostly as 

humic components with trace amounts of parent, BF 490-1, and unspecified polar 

compounds. 

Soils were not analyzed for the parent and its metabolites below the 3-inch soil 

depth because <10% of the applied radioactivity was detected below the 3-inch 

depth at any sampling interval. 

 

The second study (Jackson et al. 1996. MRID 44421005) is scientifically valid and provides 

useful information on the dissipation of kresoxim methyl in soils under field conditions. 

Results from the second study are summarized below: 

“Kresoxim methyl 50% a.i. formulated into a dry flowable powder, applied four times at 

seven day intervals at 0.24 lbs a.i./acre/application at three study sites in New York, 

Oregon, and California. The observed dissipation half-lives were: 4.5 hrs on a bare 
51 

loamy sand soil in New York; 2.9 days on a bare silty loam soil in Oregon; and <1 hour 

on a sandy loam soil in California. 

In New York, the major degradate, the acid form of the parent, BF 490-1 plus parent 

residue DT50 was 6.8 days and the degradate BF 490-5 had a DT50 of 10 days. On Day 1 

the parent, BAS 490F, residues were at 0.071 ppm at the 0-3" depth, by Day 3 the BAS 

490F residue concentration fell to 0.027 ppm at the same depth, and by Day 9 there were 

no residues detected at any depth. The parent was not found below 3". On Day 1 the 

major degradate, the acid BF 490-1, residue concentration was 0.204 ppm at the 0-3" 

depth, by Day 9 the residue concentrations fell to 0.122 ppm at the same depth, and by 

Day 300 there were no residues detected at the 0-3" depth. The degradate appeared at the 

3-6" depth on Day 30, the concentration was 0.015 ppm, by Day 180 the degradate was 

not found at the 3-6" depth. The degradate was not found below 6". 

In Oregon, BF 490-1 plus parent residue DT50 was 6.6 days and the degradate BF 490-5 

had a DT50 of 18 days. On Day 1 the parent, BAS 490F, residues were at 0.137 ppm at 

the 0-3" depth, by Day 4 the BAS 490F residue concentration fell to 0.097 ppm at the 

same depth, and by Day 14 there were no residues detected at any depth. The parent was 

not found below 3" with the exception of one detection (0.012 ppm) in one of three 

replicate samples collected at 3-6' immediately after the first application. Since no 

rainfall was received and no irrigation water was applied on that day, the detection in the 

sample collected at 3-6" is likely to be caused by contamination. On Day 1 the major 

degradate, the acid BF 490-1, residue concentration was 0.276 ppm at the 0-3" depth, by 

Day 14 the residue concentrations fell to 0.084 ppm at the same depth, and by Day 300 

there were no residues detected at the 0-3" depth. The degradate appeared at the 3-6" 

depth on Day 14, the concentration was 0.013 ppm, by Day 30 the degradate was not 

found at the 3-6" depth. The degradate was not found below 6". 

In California, BF 490-1 plus parent residue DT50 was 4.9 days and the degradate BF 

490-5 had a DT50 of 4 days. On Day 1 the parent, BAS 490F, residues were at 0.007 

ppm at the 0-3" depth, by Day 3 the BAS 490F residue concentration fell to 0.011 ppm at 

the same depth, and by Day 5 there were no residues detected at any depth. The parent 

was not found below 3". On Day 1 the major degradate, the acid BF 490-1, residue 

concentrations were 0.223 ppm at the 0-3" depth, by Day 5 the residue concentrations fell 

to 0.160 ppm at the same depth, and by Day 120 there were no residues detected at the 0-

3" depth. The degradate appeared at the 3-6" depth on Day 1, the concentration was 

0.048 ppm, by Day 21 the residue concentration of the degradate in the 3-6" depth was 

.030, and by Day 30 the degradate was not found at the 3-6" depth. The degradate 

appeared at the 6-12" depth on Day 1, the concentration was 0.023 ppm, by Day 30 the 

degradate was not found at the 6-12" depth. The degradate was not found below 12".” 

Results from three field dissipation studies conducted in New York, Oregon, and California 

showed that mobility of BF 490-1 was affected by soil pH. The soil properties and the fate of 

490-1 at the study sites are summarized in the following table. BF 490-1 was found only in the 

0-3" and 3-6" soil zones during the course of the one-year study at the New York and Oregon 

sites whereas it was detected 23 times in the 6-12" soil zone at the California site (concentrations 
52 

ranging from 0.010-0.033 ppm). The greater mobility of BF 490-1 in the soil at the California 

site than those at the New York and Oregon sites appears to be attributed to the higher soil 

alkalinity (pH=7.1) and low soil organic matter (1.1%) at the California site. 

Location of 

the study 

sites in U.S. 

 Soil type % 

Sand 

 % 

Silt 

 % 

Clay 

 pH 

(top 6" 

soil) 

Organic 

 matter 

 % 

Deepest soil 

zone with BF 

490-1 

detections 

Number of 

detections in the 6-

12" soil zone 

(conc., ppm) 

New York loamy sand 83 15 2 5.9 1.9 3-6" ------- 

Oregon silt loam 30 54 16 5.9 2.5 3-6" ------- 

California sandy loam 75 19 6 7.1 1.1 6-12" 

23 detections 

(ranging from 

0.010-0.033) 

In response to the concerns raised by EFED on the mobility of BF 490-1 in the field studies 

conducted in the U.S., the registrant submitted an additional three field dissipation studies 

conducted in Canada3

 and a field lysimeter study4 conducted in Germany to demonstrate the fate 

of the acid degradate under field conditions. 

 

Lysimeter Study conducted in Germany: 

The registrant submitted a field lysimeter study5 in which three undisturbed soil lysimeters 

(designated as Lysimeters #7, #8, and #9) were included. The lysimeter had a surface area of 

approximately 1 m2 and a depth of approximately 1.2 m (or 47 inches). The undisturbed soil 

cores were collected from the vicinity of Schifferstadt, Germany and the study was conducted in 

Germany. According to the report, the soil collected from the 0-14 inch zone is classified as a 

loamy sand (75.8% sand, 16.6% silt, 7.6% clay, pH 5.7, and 1.6% organic matter). For 

Lysimeter #7, four allocations of 14C-kresoxim methyl were made at a rate of 0.13 lbs 

 3

Jackson, S.H., Jordan J. and Wesley D.S. 1996. Soil dissipation BAS 

490 F in orchard/vineyard use patterns. Study submitted by BASF Corp. RTP, NC. 

4

Hamm, R.T. 1994. Field Lysimeter Study with 14C-242009 Formulated as 

BAS 490 04 F. Interim Report. Study Code P92-E030. Submitted by BASF.

5

Hamm, R.T. 1994. Field Lysimeter Study with 14C-242009 Formulated as 

BAS 490 04 F. Interim Report. Study Code P92-E030. Submitted by BASF.
53 

ai/acre/application (two applications were made on 4/1/92 and 5/4/92 and the other two 

applications were made on 4/5/93 and 5/11/93). For Lysimeters #8 and #9, only two 

applications were made on 4/1/92 and 5/4/93 at the same rate. The total precipitation between 

4/92 and 4/93 was 32 inches (including 12.3 inches irrigation). The total precipitation between 

4/93 and 4/94 was 32.5 inches (including 11.8 inches irrigation). Leachates from these 

lysimeters were continuously collected and analyzed for the parent compound and the major 

degradate (BF 490-1) during the 24 month period after the second application in 1992. 

As indicated in the following table, BF 490-1 was first detected in the leachates from Lysimeter 

#7 five and half months after the second application whereas it was first detected in the leachates 

from Lysimeters #8 and #9 six months after the second application. Thereafter, this degradate 

was detected in every leachate collected from all three lysimeters with the exception of the last 

leachate collected from Lysimeter #9 almost two years after the second application. The parent 

compound was not detected in the leachates collected during the two-year study period (data not 

shown). 

BF 490-1, ppb 

Sampling date, months 

after the 2nd application 

on 5/4/92a

Study year 

1992-1993 

Lysimeter #7 Lysimeter # 8 Lysimeter # 9 

1 0.000 0.000 0.000 

5.5 0.018 not collected not collected 

6 0.023 0.019 0.006 

6.5 0.014 0.030 0.016 

7 0.017 0.044 0.017 

8.5 0.021 0.052 0.018 

10 0.041 0.043 0.026 

11 0.060 0.077 0.039 

Average 0.024 0.038 0.017 

Study year 

1993-1994 

17 0.015 0.002 0.012 

18 0.003 0.001 0.001 

19.5 0.007 0.002 0.003 

20 0.004 0.001 0.002 

21 0.017 0.004 0.018 
54 

23.5 0.029 0.010 0.000 

Average 0.013 0.003 0.006

Footnote a: Lysimeter # 7 received four applications (two on 4/1/92 and 5/4/92; the other two on 

4/5/93 and 5/11/93) at a rate of 0.13 lbs ai/acre/application. Lysimeters # 8 and # 9 received two 

applications on 4/1/92 and 5/4/92 at the same rate. 

Quantitative assessment of the findings from this lysimeter study is not possible at this time 

because: (1) the soil was a German soil; (2) the application rate and frequency used in the 

lysimeter study do not reflect the label for the use of kresoxim methyl on apples, grapes, and 

pecan in the U.S. (the U.S. label states that it can be applied four times at a rate of 0.2 lbs 

ai/acre/application in a weekly interval); and (3) the annual precipitation (including rainfall and 

irrigation) the lysimeters received is much lower than the rainfall received in the Eastern region 

of the U.S. Nevertheless, this lysimeter study demonstrated very clearly that BF 490-1 is more 

mobile than the parent compound and this degradate is very persistent in the soil under natural 

field environment. EFED believes that, if the registrant had chosen an alkaline soil with low 

organic matter for the lysimeter study, the mobility of BF 490-1 would have been much higher 

than that in the acid soil (pH 5.7) used in the submitted lysimeter study. 

Field Dissipation Studies Conducted in Canada: 

A similar correlation between soil pH and the relative mobility of the acid degradate (BF 490-1) 

was also observed in the three field dissipation studies conducted in Nova Scotia, Ontario, and 

British Columbia, Canada6 (see the table below). Although the soil at the study site in Ontario 

contained the lowest sand (43%), the highest clay (20%), and the highest organic matter (3.2%) 

in these three soils, BF 490-1 was found to be more mobile at the Ontario site than at the Nova 

Scotia and British Columbia sites. At the Ontario site, three detections (0.017, 0.023, and 0.026 

ppm) were reported in the 6-12" soil zone during the course of the one-year study. The 

migration of BF 490-1 in the soil at the Nova Scotia site was very limited; it did not migrate 

below 6". Although BF 490-1 was detected in the 6-12" soil zone at the British Scotia site, the 

detection frequency (twice) and the concentrations (0.013 and 0.015 ppm) were lower than those 

observed at the Ontario site. Results from these studies conducted in Canada reaffirmed the 

effects of soil pH on the dissociation of BF 490-1 and the mobility of the resulting anionic 

species in the environment. 

location of 

the study 

sites in 

Canada 

 

 soil type 

 % 

sand 

 

% 

silt 

 % 

clay 

 pH 

(top 6" 

soil) 

organic 

 matter 

 % 

deepest soil 

zone with BF 

490-1 

detections 

number of 

detections in the 6-

12" soil zone 

(conc., ppm) 

Nova Scotia sandy loam 

 25 14 5.3 2.6 3-6" ----- 

 6

Jackson, S.H. and Wesley, D.S. 1997. Field Dissipation of BAS 490 F in orchard use 

patterns for Canada. Submitted by BASF.
55 

61 

Ontario loam 

 

 

43 

 37 20 7.4 3.2 6-12" 

3 detections 

(0.017; 0.023; 

0.026) 

British 

Columbia sandy loam 

 

 

65 

 

 

29 

 

 

6 

 6.1 2.6 6-12" 

2 detections 

(0.013; 0.015) 
56 

5. Bioaccumulation

165-1 Accumulation in Fish

The registrant submitted two fish accumulation studies (Mayo. 1994; MRID 44341037; 

Langford-Pollard, 1996; MRID 44341038) to support the fish accumulation (165-4)data 

requirement. The second study was conducted to characterize polar radioactivity that 

was not identified in the first study. Methods used in the second study (exposure phase 

conditions, and water and tissue analyses) were similar to those utilized in the first study. 

 These studies are scientifically valid and provides useful information on the 

bioaccumulation of kresoxim methyl in rainbow trout. These studies can support the data 

requirement on bioaccumulation in fish. 

Results from this study are summarized below: 

“Radiolabeled residues accumulated in rainbow trout that were exposed to uniformly 

phenyl ring-labeled [B-14C]kresoxim methyl, at a nominal concentration of 25 μg/L, 

under flow-through aquarium conditions. Bioconcentration factors (BCF), based on total 

radioactivity, were 430X for viscera, 53X for fillet and 220X for whole fish tissues. The 

maximum mean concentrations of [14C]residues were 15 ppm (21 days) for the viscera 

tissue, 1.5 ppm (3 days) for the fillet tissue, and 6.2 ppm (7 and 21 days) for the whole 

fish. Radiolabeled [14C]residues were identified only in the viscera and fillet tissues 

collected at 21 and 28 days of exposure; data reported for degradates are in parent 

equivalents. 

Parent compound (BAS 490 F) was present at 6.6 ppm and 3.8 ppm in the viscera, and 

1.1 ppm and 1.0 ppm in the fillet tissue samples at 21 and 28 days, respectively. The Zisomer (242010) of the parent compound was present at 0.15 ppm and 0.05 ppm in the 

viscera, and 0.04 ppm and 0.03 ppm in the fillet tissue samples at 21 and 28 days, 

respectively. The major metabolite BF 490-9 was present at 0.60 ppm and 0.32 ppm in 

the viscera, and 0.006 ppm and 0.003 ppm in the fillet tissue samples at 21 and 28 days, 

respectively. The major metabolite BF 490-2 was present at 0.38 ppm and 0.07 ppm in 

the viscera, and 0.01 ppm and 0.003 ppm in the fillet tissue samples at 21 and 28 days, 

respectively. The major metabolite BF 490-4 was present at 3.2 ppm and 1.4 ppm in the 

viscera, and 0.06 ppm and 0.07 ppm in the fillet tissue samples at 21 and 28 days, 

respectively. The major metabolite BF 490-1 was present at 0.94 ppm and 0.78 ppm in 

the viscera, and 0.04 ppm and 0.05 ppm in the fillet tissue samples at 21 and 28 days, 

respectively. Three unidentified major metabolites (designated as F1, F2 and F4) were 

present at ≤1.2 ppm in the viscera and ≤0.09 ppm in the fillet tissue samples at 21-28 

days. 

During depuration, 72%, 90%, and 78% of the respective [14C]residues accumulated by 

exposure day 28 were released from the viscera, fillet, and whole fish tissue within the 

first day. By 14 days of the depuration phase, 99.5%, 98.6% and 99.4% of the 

radioactivities were eliminated from the viscera, fillet and whole fish tissue samples, 

respectively. 
57 

In an additional study to identify bioaccumulated polar metabolites, radiolabeled residues 

accumulated in rainbow trout that were exposed to uniformly phenyl ring-labeled [B14C]kresoxim methyl at a nominal concentration of 25 μg/L under flow-through aquarium 

conditions. Radiolabeled [14C]residues were identified only in the viscera tissues 

collected at 28 days of exposure. Parent compound (BAS 490 F) and its Z-isomer 

(242010) were present at 1.7 ppm and 0.29 ppm, respectively. The major metabolites BF 

490-9, BF 490-2, BF 490-4 and BF 490-1 were present at 0.09 ppm, 0.20 ppm, 0.77 ppm 

and 0.33 ppm, respectively. Five polar components designated as FPA, FPB, FPC, FPD 

and FPE were present at 0.57 ppm, 1.3 ppm, 1.4 ppm, 1.2 ppm and 0.94 ppm, 

respectively. Two unidentified major metabolites (designated as F2C and F4) were 

present at 0.65 ppm and 0.32 ppm, respectively. Unidentified radioactivity was present 

in the hexane extracts at 0.78 ppm. The polar components FPB, FPC, FPD and FPE were 

separated into 7-15 metabolites following β-glucuronidase:sulphatase treatment. The two 

major metabolites of the polar component FPB were BF 490-2 (0.10 ppm) and BF 490-9 

(0.31 ppm). The two major metabolites of the polar component FPC were BF 490-2 

(0.07 ppm) and BF 490-9 (0.96 ppm). The two major unidentified metabolites of the 

polar component FPD were FPD5 (0.71 ppm) and FPD7 (0.15 ppm). The two major 

unidentified metabolites of the polar component FPE were FPE6 (0.37 ppm) and FPE7 

(0.22 ppm). 

Bibliography

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Registration Document No. 92/11828. Unpublished study performed by NATEC Institute, 

Hamburg, FRG; and submitted by BASF Corporation, Research Triangle Park, NC. (STUDY ID 

43864268) 

Bieber, W. D. 1993. Degradation of the test substance Reg. No. 242 009 (BAS 490 F) in an aerobic 

aquatic environment. BASF Registration Document No. 93/11344. Unpublished study performed 

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58 

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Research Triangle Park, NC. (STUDY ID 43864270) 
59 

Langford-Pollard, A. D. 1996. Further investigation of 14C-BAS 490 F (14C-Reg. No. 242009) 

Metabolites in rainbow trout. Laboratory Document No.: 96/10050. Unpublished study performed 

by Huntingdon Life Sciences Limited, Cambridgeshire, ENGLAND; and submitted by BASF 

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rainbow trout. Laboratory Document No.: 94/10725. Unpublished study performed by Huntingdon 

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