UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

OFFICE OF

CHEMCICAL SAFETY AND

POLLUTION PREVENTION

PC code: 128905

DP Barcode: 404124 and 386992

August 3, 2012

MEMORANDUM

SUBJECT: Revised Section 3 Environmental Fate and Ecological Risk Assessment for 

Tolclofos-methyl

FROM: Keith Sappington, Senior Biologist

Mohammed Ruhman, Senior Fate Scientist

Environmental Risk Branch V

Environmental Fate and Effects Division (7507P) 

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

Environmental Risk Branch V

Environmental Fate and Effects Division (7507P)

TO: Lisa Jones, Risk Manager Reviewer,

Mary Woller, Risk Manager, RM-21

Fungicide Branch,

Registration Division (7505P)

Please find attached a revision of the new chemical environmental fate and ecological risk 

assessment for the proposed seed treatment uses of tolclofos methyl effects. This revision was 

necessary in response to new registrant submission related to the environmental chemistry

methods (ECMs) and associated Independent laboratory validations (ILVs) for residues in soil 

and water (DP Barcode: 404124). 

It is important to note that the attached revised chapter does not affect contents and summary of 

the major conclusions and uncertainties included in the previous memo entitled: Section 3 

Environmental Fate and Ecological Risk Assessment for Tolclofos-methyl (May 15, 2012; DP 

Barcode: 386992).
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION

Environmental Fate 

and Ecological Risk Assessment

for Tolclofos Methyl Registration

O-(2,6-dichloro-4-methylphenyl) O,O-dimethyl phosphorothioate

CAS: 57018-04-9; PC code: 128905

Prepared by:

Mohammed A. Ruhman, Ph.D.

Keith Sappington, M.S.

Joseph Beaman, M.S.

Reviewed by:

Mah Shamim, Ph.D.

United States Environmental Protection Agency

Office of Pesticide Programs

Environmental Fate and Effects Division

Environmental Risk Branch V

1200 Pennsylvania Ave.

Mail Code 7507P

Washington, D.C. 20460

H

H

H

H

H

H

H

H

H

O

O

P

S

O

Cl

Cl
ii

Contents

I. EXECUTIVE SUMMARY .................................................................................................................................6

A. Nature of Chemical Stressor..................................................................................................................6

B. Potential Risks to Non-target Organisms...............................................................................................7

C. Conclusions - Exposure Characterization ..............................................................................................9

D. Conclusions - Effects Characterization..................................................................................................9

E. Data Gaps and Uncertainties..................................................................................................................9

1. Environmental Fate........................................................................................................................................9

2. Ecological Effects........................................................................................................................................10

II. PROBLEM FORMULATION .....................................................................................................................10

A. Stressor Source and Distribution .........................................................................................................10

1. Stressor Of concern......................................................................................................................................10

2. Source and Intensity ....................................................................................................................................11

3. Physicochemical, Fate, and Transport Properties........................................................................................11

4. Pesticide Type, Class, and Mode of Action (MOA)....................................................................................12

5. Overview of Pesticide Usage.......................................................................................................................13

B. Receptors.............................................................................................................................................13

1. Ecological Effects........................................................................................................................................13

C. Ecosystems at Risk ..............................................................................................................................15

D. Assessment Endpoints .........................................................................................................................16

E. Conceptual Model................................................................................................................................16

1. Risk Hypotheses ..........................................................................................................................................16

2. Conceptual Diagram ....................................................................................................................................17

F. Analysis Plan .......................................................................................................................................20

1. Methods for Conducting Ecological Risk Assessment and Identification of Data Gaps.............................20

2. Measures of Exposure..................................................................................................................................22

3. Measures of Effects .....................................................................................................................................23

4. Measures of Ecosystem and Receptor Characteristics.................................................................................23

III. ANALYSIS.....................................................................................................................................................25

A. Use Characterization............................................................................................................................25

B. Exposure Characterization...................................................................................................................29

1. Environmental Fate and Transport Characterization ...................................................................................30

2. Aquatic Exposure Assessment.....................................................................................................................45

3. Terrestrial Exposure Assessment.................................................................................................................63

4. Non-Target Terrestrial Plant Exposure Assessment ....................................................................................65

C. Ecological Effects Characterization.....................................................................................................66

1. Aquatic Effects ............................................................................................................................................66

2. Terrestrial Effects ........................................................................................................................................75

IV. RISK CHARACTERIZATION....................................................................................................................83

A. Risk Estimation - Integration of Exposure and Effects Data ...............................................................83

1. Non-target Aquatic Animals and Plants ......................................................................................................83

2. Non-target Terrestrial Animals....................................................................................................................91

3. Piscivorous Birds and Mammals .................................................................................................................93

4. Non-target Beneficial Insects.......................................................................................................................95

5. Non-target Terrestrial Plants........................................................................................................................95

B. Risk Description - Interpretation of Direct Effects..............................................................................96

1. Risks to Aquatic Animals............................................................................................................................96

2. Risks to Terrestrial Animals........................................................................................................................99

3. Risks to Terrestrial Plants..........................................................................................................................101

4. Review of Incident Data ............................................................................................................................102

5. Threatened and Endangered Species Concerns .........................................................................................102

C. Description of Assumptions, Limitations, Uncertainties, Strengths and Data Gaps..........................103

1. Exposure for All Taxa................................................................................................................................103

2. Exposure for Aquatic Species....................................................................................................................104
iii

3. Exposure for Terrestrial Species................................................................................................................105

4. Effects Assessment ....................................................................................................................................107

V. REFERENCES TO OPEN LITERATURE AND GOVERNMENT REPORTS...................................110

Appendix A. Environmental Fate Study Bibliography..............................................................................................111

Appendix B. Ecotoxicity Study Bibliography ...........................................................................................................113

Appendix C. Data Requirements and Data Gaps.......................................................................................................121

Appendix D. Ecotoxicity Study Summaries..............................................................................................................129

Appendix E. Risk Quotient Method and Levels of Concern .....................................................................................142

Appendix F. Output From T-REX Model (v 1.5)......................................................................................................144

Appendix G: Summary of Submitted Environmental Fate Studies...........................................................................147

Appendix H. Results from STIR and SIP Screening Tools......................................................................................185
iv

Table of Figures

Figure 1 Degradates of TM resulting from abiotic and biotic transformation in aerobic/ anaerobic soil and aquatic 

systems. .......................................................................................................................................................................12

Figure 2. The aquatic conceptual model for seed-coat application of TM to seeds of agricultural crops (dotted lines 

indicate unlikely routes of chemical dissipation).........................................................................................................18

Figure 3. The terrestrial conceptual model for seed-coat application of TM to agricultural crops (excluding abraded 

seed coat drift; dotted lines indicate unlikely routes of chemical dissipation).............................................................19

Figure 4. The terrestrial conceptual model for seed-coat application of TM to agricultural crops via abraded seed 

coat drift (dotted lines indicate unlikely routes of chemical dissipation) ....................................................................20

Figure 5. Position of radiolabel for TM used in fate and transport studies.................................................................32

Figure 6. Un-extracted bound residues following the most effective extraction procedure; extraction procedure 2 (EP 

2, Table 9, above)........................................................................................................................................................39

Figure 7 Expected environmental degradation pathways for TM (degradates are color coded)..................................42

Figure 8. Surface water exposure EECs (Case 1, Case 2 and Ornamentals)...............................................................62

Figure 9. Acute Risk Quotients for Freshwater Fish (top panel) and Saltwater Fish (bottom panel) Relative to LOCs 

(0.5=listed sp.; 0.05 = non-listed sp.) Downward arrows denote non-definitive RQs (“<” values) ............................85

Figure 10. Chronic Risk Quotients for Freshwater Fish Relative to LOC (1.0). Upward arrows denote non-definitive 

RQs (“>” values). ........................................................................................................................................................86

Figure 11. Acute Risk Quotients for Freshwater (top panel) and Saltwater Invertebrates (bottom panel) Relative to 

Acute Risk LOCs (0.05 and 0.5). ................................................................................................................................88

Figure 12. Chronic Risk Quotients for Freshwater (top panel) and Saltwater Invertebrates (bottom panel) Relative to 

the LOC (1.0)...............................................................................................................................................................89
v

Table of Tables

Table 1. Taxonomic groups and test species evaluated for ecological effects in this screening-level risk assessment

.....................................................................................................................................................................................13

Table 2. Toxicity endpoints used in risk quotient calculations....................................................................................14

Table 3. Crop use patterns and application rates for the TM new chemical registration for seed treatment ...............25

Table 4. Physical and chemical properties of TM .......................................................................................................30

Table 5. Maximum quantities of organic volatiles found in different biotic studies (ED= Experimental duration in 

days; ED= Experiment duration in days; T= Incubation temperature in oC; and AR= Application rate ppm)............31

Table 6. Fate properties of TM in abiotic systems.......................................................................................................33

Table 7 Available data for characteristics of soil and aquatic systems used in laboratory biotic studies. ...................34

Table 8. Fate properties of TM in biotic systems (Refer to Table 7 above for soil identification/ characteristics and to 

Appendix G for a details) ............................................................................................................................................35

Table 9. Percentages of bound residues found in different biotic studies following varied extraction procedures 

studies (ED= Experimental duration in days; T= Incubation temperature in oC; AR= Application rate ppm; and EP= 

Extraction Procedure Number “refer to Table 10. for description of the procedures”) ...............................................37

Table 10. Description of extraction procedures used in soil and sediment extraction in biotic studies (Refer to Table 

8 for a list of these studies)..........................................................................................................................................38

Table 11. Adsorption/Desorption properties of TM ....................................................................................................43

Table 12. Modeling inputs for Case 1 and ornamentals (application rate used for all run= 0.02 lbs a.i/A)* ..............47

Table 13. Modeling inputs for Case 2 .........................................................................................................................49

Table 14. Summary of PRZM/EXAMS environmental fate and transport data used as aquatic exposure inputs 

(TTR=total toxic residues)...........................................................................................................................................54

Table 15. Surface water 1-in-10 Year EECs (μg/L) for TM1use patterns (Case 1)....................................................54

Table 16. Surface water 1-in-10 Year EECs (μg/L) for TM1use patterns (Case 2)....................................................56

Table 17. Pore-water 1-in-10 Year EECs (μg/L) for TM1use patterns (Case 1).........................................................63

Table 18. Estimated Exposure of TM to Birds and Mammals Based on Label Seed Application Rates.....................64

Table 19. Toxicity Reference Values For Aquatic Organisms Exposed To Tolclofos Methyl and Metabolite (DMTM)..............................................................................................................................................................................67

Table 20. Toxicity Reference Values For Terrestrial Organisms Exposed To Tolclofos Methyl................................76

Table 21. Acute and chronic risk quotients (RQs) for evaluating toxic risk of TM exposure to freshwater and 

saltwater fish................................................................................................................................................................84

Table 22. Maximum Acute and chronic risk quotients (RQs) for evaluating toxic risk of TM exposure to freshwater 

and saltwater invertebrates ..........................................................................................................................................86

Table 23. Subchronic and Chronic Risk Quotients for evaluating toxic risk of TM exposure to freshwater and 

estuarine/marine benthic invertebrates. .......................................................................................................................90

Table 24. Acute RQs for non-vascular aquatic plants exposed to TM. .......................................................................91

Table 25. Acute Avian RQs for Proposed TM Seed Treatment Uses..........................................................................91

Table 26. Acute Mammalian RQs for Proposed TM Seed Treatment Uses................................................................92

Table 27. Chronic Mammalian RQs for Proposed TM Seed Treatment Uses.............................................................93

Table 28. Predicted residues of TM in aquatic organisms using KABAM and BCF Methods. ..................................94

Table 29. Calculation of RQ values for mammals and birds consuming fish contaminated by Tolclofos Methyl......95

Table 30. Aquatic Plant Toxicity Data Obtained For Other Phosphorothionate Organophosphate Pesticides............99

Table 31. Terrestrial Plant Toxicity Data Obtained For Other Phosphorothionate Organophosphate Pesticides.....102
6

I. EXECUTIVE SUMMARY

A. Nature of Chemical Stressor 

Tolclofos-Methyl (O-2,6-dichloro-p-tolyl O,O-dimethyl phosphorothioate) also identified as 

Rizolex, Grancer, Basilex, S-3349; CAS 57018-04-9, PC code128905), and hereafter referred to 

as “TM” in this document, belongs to the organophosphate (OP) class of pesticides which are 

typically known for their insecticidal modes of action. Although TM exhibits 

acetylcholinesterase inhibition in animal studies, the extent of inhibition is weak relative to other 

OP insecticides. In this action, TM is being proposed for use as a fungicide seed treatment on 

numerous crops. According to the Fungicide Resistance Action Committee (FRAC),1the 

proposed mode of action of TM is disruption of lipid synthesis and membrane integrity via lipid 

peroxidation. The fungicidal activity of TM is thought to be related to its inhibition of the 

zoospore mobility of phycomycetous fungi and disturbance of normal cytokinesis similar to the 

compound cytochalasin A2. 

TM is active against Rhizoctonia solani, Fusarium spp., and other Deuteromycete fungi that 

cause seed decay and seedling blights. Plant studies suggest that the chemical is not systemic as 

there was minimal translocation of the parent compound or metabolites from the seed to emerged 

seedlings based on submitted plant metabolism studies (MRIDs 483419-56/57). 

TM is proposed for use as a flowable fungicide (42% a.i by weight) for seed treatment (true 

seeds only) on fifteen crop groups: Root Vegetables (Crop Group 1 A, with exceptions; 13 

Crops); Bulb Vegetables (Crop Group 3-07; 12 Crops); Leafy Vegetables (except Brassica 

Vegetables) (Crop Group 4; 30 Crops); Brassica (Cole) Leafy Vegetables (Crop Group 5; 16 

Crops); Legume Vegetables (Succulent or Dried) (Crop Group 6; 44 Crops); Fruiting 

Vegetables (Crop Group 8-10; 22 Crops); Cucurbit vegetables (Crop Group 9; 38 Crops); Cereal 

Grains (Crop Group 15 except rice and wild rice; 11 Crops); Grass, Forage, Fodder, and Hay 

(Crop Group 17); Non-Grass animal Feeds (Forage, Fodder, Straw, and Hay) (Crop Group 18; 

12 Crops); Herbs and Spices (Crop Group 19; 69 Crops); Oilseeds (Crop Group 20, except 

cotton; 31 Crops); Conifers; Cotton; and Ornamental Flowers. According to the registrant, TM is 

a contact, broad-spectrum fungicide that provides protection for planted seeds and emerging 

seedlings from soil borne fungal pathogens. 

Since TM is intended as a seed treatment, the primary source of exposure will be below the soil 

surface since the label indicates treated seeds may not be planted by broadcast. In this case, no 

spray drift is expected, although drift of abraded seed coating may occur from seed planting 

practices. The depth of TM placement will depend on recommended seeding depth for a given 

crop and the depth of the moist zone where seeds are usually planted. Upon planting, TM is 

expected to be subject to degradation within the aerobic soil system with limited 

leaching/runoff/volatilization. Although TM is semi volatile, its placement below the soil surface 

 

1

FRAC. 2012. FRAC Code List ©*2012: Fungicides sorted by mode of action. 

http://www.frac.info/frac/publication/anhang/FRAC-Code-List2011-final.pdf

2

http://dar.efsa.europa.eu/dar-web/provision
7

is expected to limit its ability to escape into the atmosphere possibly increasing the availability of 

the chemical in the soil and in aquatic compartments of the environment, including groundwater. 

Degradation of TM in soil/aquatic systems (when it reaches the aquatic systems via runoff), is 

expected through three major processes: mineralization to CO2, formation of bound residues; and 

degradation into few major degradates and many minor degradates (usually <1% each). The 

major/minor degradates include DM-TM (a major degradate), ph-CH3 (mostly a minor 

degradate), and oxons including DM-TMO and TMO (minor degradates in the soil and aquatic 

compartments). These degradation products show decline to low levels, in most cases reaching 

limits of detection, and are not considered as part of the stressor of concern. In contrast, 

uncharacterized bound residues are considered as part of the total residues of concern in addition 

to parent.

B. Potential Risks to Non-target Organisms 

A summary of the major conclusions and uncertainties of this assessment for aquatic and 

terrestrial receptors respectively is included below. 

Acute Risks Concerns to Aquatic Animals. The results of this screening-level risk assessment 

suggest a low likelihood of acute toxicity to fish (and to aquatic-phase amphibians for which fish 

serve as surrogates) and aquatic invertebrates (freshwater and saltwater) as a result of runoff of 

TM from seeds to adjacent surface waters. Acute effects on these taxa were at or near the limits 

of TM solubility (0.7 mg ai/L). This low acute toxicity combined with the low predicted aquatic 

EECs (maximum = 0.344 ug ai/L) results in risk quotients (RQ) that are approximately 2 orders 

of magnitude below Agency levels of concern (LOC). 

Chronic Risk Concerns to Aquatic Animals. There is a low likelihood for chronic toxic 

effects to aquatic invertebrates (water column and benthic dwelling), with chronic RQ values 2-3 

orders of magnitude below the Agency LOC. Chronic risks to freshwater and saltwater fish 

could not be determined definitively due to lack of toxicity data (saltwater fish) and a nondefinitive NOAEC for freshwater fish (< 12 ug ai/L). However, estimated exposure 

concentrations (EEC) for evaluating the likelihood of chronic effects are 100X lower than the 

current LOAEC for freshwater fish (12 ug ai/L). Furthermore, the similarity in acute toxicity

among freshwater and saltwater fish suggests that saltwater fish would be of similar sensitivity to 

freshwater fish on a chronic exposure basis. Based on these lines of evidence, the risk of chronic 

effects to freshwater and saltwater fish from the proposed uses of TM is expected to be low.

Risks to Aquatic Plants. Based on limited submitted data for TM, the likelihood of adverse 

effects to non-vascular aquatic plants is expected to be low. However, data were only submitted 

for one species of algae (not the usual 4 species) and were not submitted for vascular aquatic

plants. The uncertainty associated with lack of aquatic plant toxicity data was characterized 

based on data for other phosphorothionate organophosphate pesticides. These surrogate plant 

toxicity data suggest the predicted EECs in surface water (maximum peak EEC of 0.344 ug ai/L) 

have a low potential for adverse effects to aquatic vascular and non-vascular plants. 
8

Acute Risks Concerns for Birds and Mammals. Acute risks were evaluated on the assumption 

that birds and mammals consume 100% of their diet as TM-treated seed. The likelihood of 

acute toxicity is considered low for both birds (and terrestrial-phase amphibians and reptiles for 

which birds serve as surrogates) and mammals with the proposed seed treatment rates. No acute 

risk concerns were identified for piscivorous birds or mammals.

Chronic Risk Concerns for Birds and Mammals. A potential for chronic risks to birds (and 

terrestrial-phase amphibians and reptiles for which birds serve as surrogates) and mammals was 

evaluated in this assessment based on consumption of treated seeds. Specifically, the maximum 

chronic RQ values derived from the root vegetables and cotton crop scenarios are equivalent to 

the Agency chronic risk LOC for birds (RQ=1.0) and exceed the chronic risk LOC for mammals 

(RQ=7.9). For birds, the chronic risk finding is highly sensitive to the assumption of 100% of 

the diet consisting of treated seed since soil incorporation is required for the proposed seed 

treatment uses of TM. The current terrestrial exposure assessment model (T-REX v. 1.5) does 

not take into account the effect of soil incorporation on wildlife exposure to treated seeds. In 

addition, the NOAEL from the chronic avian toxicity study (500 ppm diet) is somewhat 

uncertain due to the wide dose spacing used in the study (LOAEL = 2500 ppm diet). No chronic 

risk concerns were identified for piscivorous birds. 

For mammals, chronic risk concerns were identified for both seed treatment rates proposed on 

the label (i.e., both the higher rate for root vegetables and cotton and the lower rate for other 

vegetables). Similar to the avian risk assessment, the wide dose spacing associated with the 

chronic NOAEL (100 ppm diet) and LOAEL (3000 ppm) introduces uncertainty in the 

interpretation of exposures that exceed the NOAEL but not the LOAEL. No chronic risk 

concerns were identified for piscivorous mammals. 

Risk Concerns for Terrestrial Plants. No data were submitted on the toxicity of TM to 

terrestrial plants. However, its use as a seed treatment and non-systemic characteristics 

minimize off-site transport to terrestrial plants. A potential for off-site transport does exist for 

abraded seed coatings containing TM. The maximum application rate of TM (0.02 lb ai/A) is 

1to2 orders of magnitude below the most sensitive plant toxicity values reported for other 

phosphorothionate organic pesticides, suggesting that risk concerns for terrestrial plants are low. 

Risk Concerns for Beneficial Insects. Although spray drift is not an exposure route of concern 

for beneficial insects (honeybee), off-site drift of abraded seed coatings during planting is a 

potential route of concern. Available toxicity data for TM indicate it is practically non-toxic to 

young adult honeybees on an acute contact exposure basis. Given the low application rate 

proposed for TM (0.02 lb a.i/A) and its non-systemic characteristics in terrestrial plants, risk 

concerns for pollinating insects are considered low. 
9

C. Conclusions - Exposure Characterization 

TM is semi volatile (vapor pressure= 1.38 x 10-5torr and Henry’s law constant= 3.68 x 10-6atm 

m

3 mole-1

) and is characterized by low solubility in water (0.7 mg/L at 20

oC & 1.10 mg/L at 

25oC). Photolysis in water and on soil is not expected to be important processes in TM 

dissipation in the natural environment. The pesticide is applied on seeds that are placed below

the soil surface limiting exposure due to drift, volatility and runoff. TM breaks down through 

hydrolysis and biotic degradation processes into many degradation products that are expected to 

be non-persistent with the exception of bound residues. Metabolites of TM are not expected to be 

persistent in the environment based on their rapid decline following formation. However, bound 

residues formed in high quantities in aerobic soil and aquatic environments appear to be 

persistent and are considered to be of exposure concern. Batch adsorption/desorption studies 

indicate a low potential for mobility in soil for TM thereby limiting the possibility of leaching. 

Aquatic exposures of concern for this chemical include those that may be caused by parent 

compound and bound residues reaching aquatic systems through limited runoff. Finally, the noctanol water partition coefficient (Kow) of TM is 6,310 (log Kow=3.8) suggesting a potential for 

bioconcentration in aquatic organisms such as fish.

D. Conclusions - Effects Characterization 

For aquatic animals and plants, the acute toxicity of TM approaches its solubility in water (0.7-

1.1 mg a.i/L). TM is considerably more toxic on a chronic exposure basis, with NOAECs of < 

0.012 mg a.i/L for rainbow trout (Oncorhynchus mykiss), 0.026 mg a.i/L for Daphnia magna, 

and 0.0039 mg a.i/L for mysid shrimp. There were no data submitted on the toxicity of TM to 

aquatic vascular plants or on the chronic effects of TM on saltwater fish. For terrestrial animals, 

TM is practically non-toxic to both birds and mammals on an acute exposure basis. For birds, 

both the LD50 and LC50 values were non-definitive (“>”) values, with the lowest being >2000 

mg a.i/kg bw for zebra finch. For mammals, the most sensitive LD50 value is 3,500 mg a.i/kg-bw 

for mouse. TM is chronically toxic to birds at exposure levels greater than 500 ppm in the diet. 

For mammals, TM is chronically toxic at concentrations above 100 ppm in the diet (12.2 mg 

a.i/kg bw). 

E. Data Gaps and Uncertainties 

1. Environmental Fate 

Although uncertainties and data gaps were identified with the available environmental fate 

studies (e.g., volatilization, nature of bound residues, supplemental classification of some of the 

fate studies and all of the mobility studies), the limited proposed use of this chemical ((seed 

treatment only), combined with the low ecological risk findings indicate that additional data on 

environmental fate of TM is of low priority at this time. However, data will be needed in case of 

requests for new use(s). The chemical is to be used as seed treatment only with maximum one 

time rate of 0.02 lbs a.i/A.
10

2. Ecological Effects 

Solubility problems were encountered or suspected in several of the acute toxicity studies with 

TM. However, the exceptionally low aquatic EECs indicate that uncertainty associated with the 

bioavailability of TM in acute toxicity studies is not likely to affect the aquatic risk conclusions, 

since aquatic RQs are two or more orders of magnitude below acute risk LOCs. The chronic 

toxicity database for TM effects on fish is also uncertain. Specifically, the existing data support 

a NOAEC of <12 ug ai/L for freshwater fish and no data are available for saltwater fish. Again, 

however, the low chronic EECs of TM from the proposed seed treatment uses combined with the 

available toxicity information for freshwater fish suggests that additional data on the chronic 

toxicity to fish would not materially affect the risk assessment conclusions for the proposed seed 

treatment uses. Although data are limited for aquatic plants and unavailable for terrestrial plants, 

the low aquatic EECs combined with data for similar OP pesticides suggest a low potential for 

TM to adversely affect aquatic or terrestrial plants. Therefore, the need for additional data on the 

effects of TM on aquatic or terrestrial plants is deemed a low priority for the proposed seed 

treatment uses.

II. PROBLEM FORMULATION

A. Stressor Source and Distribution 

1. Stressor Of concern

As discussed further in III.B, the stressor of concern for TM defined in this assessment is the 

parent TM and unidentified bound residues. Multi degradation products, including oxons, were 

not included, as part of the stressor, based on the following reasons:

 The only major degradate identified was DM-TM, which is practically non-toxic to 

aquatic life and therefore not of toxicological concern;

 Terrestrial exposure modeling for seed treatment uses does not consider degradation;

 All other identifiable degradates were considered minor (<10%) in the presence of biotic 

processes;

 Although oxons were identified in fate studies, these were present in minor amounts and 

were not persistent. No toxicity data were available for oxons, but a sensitivity analysis 

indicates that even if oxons were 100X more toxic than parent TM, no aquatic risk 

concerns would be identified given the very low EECs for the parent and even lower 

EECs for the oxon degradate.

Bound residues are included as part of the stressor because fate studies indicate these 

unidentified bound residues form in significant quantities, especially in aerobic soil/aquatic 

systems. Observed concentrations in aerobic soil/aquatic systems ranged from 21-64% (90th

percentile= 51%, n=14) and in anaerobic soil was 4.1% in one soil, 31-39% in two soils and 

2.5% in one anaerobic aquatic system. In absence of toxicity data for bound residues, they are 

assumed of equal toxicity as parent TM.
11

2. Source and Intensity 

TM is formulated as a flowable fungicide for seed treatment only. The rate of application for TM 

ranges from a minimum one time rate of 0.01lb a.i/100 lbs of seeds (cwt) for most use patterns to 

a maximum one time rate of 0.05 lb a.i/100 lbs of seeds (cwt) for cotton and root vegetables. 

When the maximum amount of seed needed to plant an acre of land is considered, the application 

rates vary widely from 0.00003 lb a.i/A for cauliflower seeds to 0.04257lb a.i/A for bean seeds. 

Seeds treated with this chemical are the source of the stressor noting that no drift is expected to 

result from planting treated seeds (the potential drift of fugitive dust “dust-off” from abraded 

treated seed coat is possible but was not considered quantitatively in the this assessment due to 

lack of appropriate exposure models for this pathway). Although the chemical will be buried 

with the seeds, partitioning into the air may not be excluded because of the relatively high vapor 

pressure (VP= 1.38 x 10-5torr) and Henry’s Law constant (HLC= 3.68 x 10-6atm m3 mole-1). 

Environmental exposure resulting from volatility is expected to reduce modeled aquatic 

concentrations and be a source of terrestrial exposure. Both issues will be addressed later in this 

assessment.

3. Physicochemical, Fate, and Transport Properties 

TM is characterized by a water solubility of 0.7 -1.1 ppm depending on temperature. As 

discussed in the preceding section, the chemical has the potential for volatilization from dry and 

wet surfaces.

In the laboratory, TM was slightly affected by hydrolysis (t1⁄2= 51, 61, and 62 days at pH values 

of 5, 7, and 9, respectively) and showed high persistence to photolysis in water and on soil. 

Degradates forming as a result of abiotic degradation included: DM-TM (major in 

photolysis/hydrolysis), TMO (major in hydrolysis/minor in photolysis), and ph-CH3 (minor in 

photolysis/hydrolysis). In contrast to abiotic routes of degradation (photolysis/hydrolysis), TM 

shows relatively lower persistence to biotic degradation in the aerobic soil systems (90th

percentile t1⁄2 for TM alone was 40 days in aerobic soil within a range of 16-79 days) and in 

anaerobic soil (t1⁄2= 34-87 days) and in aerobic/anaerobic water sediment systems (t1⁄2= 19-26 

days/47 days). Biotic degradation in various systems resulted in the initial formation of 

degradates stated above, for abiotic systems, including SM-TM and TM-COOH in addition to 

the major process of mineralization to CO2 (Figure 1). Further transformation of degradates 

listed in Figure 1 resulted in the formation of low concentration of many minor degradates by

biologically induced oxidation and cleavage. Most of the degradation products of this chemical 

show decline following maximum formation suggesting that most are non-persistent. 

Furthermore, one of the major processes in the degradation of this chemical is the formation of 

large quantities of (quantified but unidentified) bound residues that showed relatively high 

resistance to degradation. These bound residues, along with the parent, are considered in this 

assessment to be residues of concern, and when half lives are calculated with the inclusion of 

bound residues and parent, half-lives are in the range of 98 to 239 days, with an upper 90th
12

percentile bound on the mean half-life of 171 days (90th percentile t1⁄2 for TM alone was 40 days 

in aerobic soil within a range of 16-79 days) 

Parent TM

(1) Abiotic/Biotic Transformation

DM-TM: O-2,6-Dichloro-p-tolyl O-hydrogen, O-methyl 

phosphorothioate (Cleavage of P-methyl moiety)

ph-CH3: 2,-6-Dichloro-4-methylphenol (Cleavage of P-O-aryl

moiety); 

TMO (Oxon): 2,6-Dichloro-4-methyl-phenyl) dimethyl 

phosphate (Oxidation: P-S to P-O)

DM-TMO (Oxon): (2,6-Dichloro-4-methyl-phenyl) methyl 

hydrogen phosphate (Oxidation: P-S to P-O)

(2) Biotic Transformation Only

SM-TM: O,S-dimethyl O-2,6-dichloro-4-methyl phenyl 

phosphorothioate (Sulfur substitution @ aryl methyl group)

TM-COOH: O,O-Dimethyl O-2,6-dichloro-4-carboxphenyl 

phosphorothioate (Oxidation @ aryl methyl group)

Figure 1 Degradates of TM resulting from abiotic and biotic transformation in aerobic/

anaerobic soil and aquatic systems.

4. Pesticide Type, Class, and Mode of Action (MOA)

TM is a fungicide that belongs to the organophosphorus (OP) class of pesticides. Although this 

pesticide class is mostly associated with insecticides, TM is practically non-toxic to bees on an 

acute contact exposure basis. Furthermore, numerous studies of cholinesterase inhibition in 

mammalian studies indicate TM has low activity relative to other OP pesticides and exhibits low 

acute toxicity to mammals and birds (Section III.C).
13

According to the Fungicide Resistance Action Committee (FRAC),3TM affects lipid synthesis 

and membrane integrity via lipid peroxidation (proposed MOA). According to the EU 2005 

Draft Assessment Report (DAR),4TM inhibits the mobility of zoospores of phycomycetous 

fungi and may achieve its fungicidal properties via disturbance of normal cytokinesis similar to 

the compound cytochalasin A. TM is also considered non-systemic in plants, according to the 

EU DAR and submitted plant metabolism studies.

5. Overview of Pesticide Usage 

TM is a new pesticide that is proposed for use in preventing and/or controlling certain fungal 

diseases on seeds for many major crops. Therefore it is proposed as a seed treatment, in most 

agricultural areas of the US. In addition treated seeds will be used in nurseries and greenhouses.

B. Receptors 

1. Ecological Effects 

Ecological measures of effect for this screening-level risk assessment are based on a suite of 

registrant-submitted toxicity studies performed on a limited number of organisms in broad 

groupings. Table 1 gives examples of taxonomic groups and test species evaluated for 

ecological effects in this screening level risk assessment. Within each of these very broad 

taxonomic groups, an acute and/or chronic endpoint is selected from the available test data (see 

Table 2). A complete discussion of all toxicity data available for this risk assessment and the 

resulting measures of effect selected for each taxonomic group are included in Appendix D. 

Table 1. Taxonomic groups and test species evaluated for ecological effects in this screening-level 

risk assessment

Taxonomic group Representative species

Birds a Mallard duck (Anas platyrhynchos)

Bobwhite quail (Colinus virginianus)

Ring-Necked Pheasant (Phasianus colchicus)

Zebra finch (Taeniopygia guttata)

Mammals Laboratory rat (Rattus norvegicus)

Mouse (Mus musculus)

Beagle dog (Canis lupus familiaris)

Terrestrial Invertebrates Honeybee (Apis mellifera)

Freshwater fish b Bluegill sunfish (Lepomis macrochirus)

Rainbow trout (Oncorhynchus mykiss)

Guppy (Poecilia reticulata)

Fathead minnow (Pimephales promelas)

Carp (Cyprinus carpio)

Japanese medaka (Oryzias latipes)

 

3

FRAC. 2012. FRAC Code List ©*2012: Fungicides sorted by mode of action. 

http://www.frac.info/frac/publication/anhang/FRAC-Code-List2011-final.pdf

4

http://dar.efsa.europa.eu/dar-web/provision
14

Table 1. Taxonomic groups and test species evaluated for ecological effects in this screening-level 

risk assessment

Taxonomic group Representative species

Freshwater Invertebrates Water flea (Daphnia magna)

Estuarine/marine Fish Sheepshead minnow (Cyprinodon variegatus)

Estuarine/marine Mollusk Eastern oyster (Crassostrea virginica)

Estuarine/marine Invertebrates Mysid shrimp (Americamysis bahia)

Benthic Freshwater Invertebrates Amphipod (Hyalella azteca)

Freshwater midge (Chironomus riparius)

Benthic Estuarine/Marine Invertebrates Amphipod (Leptocheirus plumulosus)

Aquatic Plants and Algae Green algae (Scenedesmus quadricauda)

a Birds may be surrogates for amphibians (terrestrial phase) and reptiles.

b

Freshwater fish may be surrogates for aquatic phase amphibians.

For screening-level risk assessments, the following toxicity endpoints presented in Table 2 are 

used as inputs to the risk quotient (RQ) method for expressing risk (US EPA, 2004). The 

designation of “listed species” refers to either federally threatened or endangered species.

Table 2. Toxicity endpoints used in risk quotient calculations

Taxonomic group Representative species

Aquatic Animals

Acute assessment 

Chronic assessment 

Lowest tested EC50 or LC50 for freshwater fish and invertebrates and 

estuarine/marine fish and invertebrates acute toxicity tests.

Lowest no-observed-adverse-effects- concentration (NOAEC) for 

freshwater fish and invertebrates and estuarine/marine fish and 

invertebrates early life-stage or full life-cycle tests.

Terrestrial Animals 

Acute avian assessment 

Chronic avian assessment 

Acute mammalian assessment 

Chronic mammalian assessment 

Lowest LD50 (single oral dose) and LC50 (subacute dietary).

Lowest NOAEC for 21-week avian reproduction test.

Lowest LD50 from single oral dose test. 

Lowest NOAEC for two-generation reproduction test or chronic dietary 

study
15

Table 2. Toxicity endpoints used in risk quotient calculations

Taxonomic group Representative species

Plants

Terrestrial non-listed species 

Aquatic vascular and algae

Terrestrial listed species 

Lowest EC25 values from both seedling emergence and vegetative vigor for 

both monocots and dicots. 

Lowest EC50 for both vascular and algae.

Lowest EC5 or NOAEC for both seedling emergence and vegetative vigor 

for both monocots and dicots. 

a

Freshwater fish may be surrogates for amphibians (aquatic phase).

b Birds may be surrogates for amphibians (terrestrial phase) and reptiles.

a. Aquatic Effects 

Acute and chronic laboratory and field tests on TM provide information regarding lethality, as 

well as sublethal measures of effect. Data are available on the technical grade active ingredient 

(TGAI) effects on freshwater and saltwater fish, aquatic invertebrates, aquatic nonvascular plants 

(green algae). No data were available for vascular aquatic plants. However, this data gap 

requirement was waived as part of a recent response to a waiver request (D393184); the waiver 

was granted due to the low potential for risks to aquatic plants based on a comparison of the 

aquatic EECs derived from the proposed seed treatment use and to plant toxicity endpoints from 

other OP pesticides. Uncertainty associated with lack of data for aquatic vascular plants is 

discussed in Section IV.C.

b. Terrestrial Effects 

For terrestrial effects, registrant-submitted studies on TM TGAI are available for acute, subacute, 

and chronic exposure to birds, and acute and chronic exposure to mammals. Additional 

ecological effects data for TM are available for honeybees (Apis mellifera). No data were 

submitted on the effects of TM on terrestrial plants. This data gap requirement was waived as 

part of a response to a waiver request (D393184); the waiver was granted on the basis of low 

likelihood of risk concerns to non-target terrestrial plants from the proposed seed treatment use 

given the low EECs and low phytotoxicity of other similar OP pesticides. Uncertainty associated 

with lack of data for terrestrial plants is discussed in Section IV.C.

C. Ecosystems at Risk 

The ecosystems at potential risk from the proposed seed treatment use of TM are extensive in 

scope due to the wide geographic distribution of potential TM application sites. In general 

terms, terrestrial ecosystems potentially at risk could include the treatment areas directly and 

adjacent areas that may receive runoff. This could include the treatment area itself as well as 
16

other cultivated fields, fencerows and hedgerows, meadows, fallow fields or grasslands, 

woodlands, riparian habitats and other uncultivated areas. 

Aquatic ecosystems potentially at risk include water bodies adjacent to (or downstream from) the 

treatment area and might include impounded bodies such as ponds, lakes, reservoirs and wetland 

areas, or flowing waterways such as streams and rivers. For uses in coastal areas, aquatic habitat 

also includes marine ecosystems, including estuaries and salt marshes. 

D. Assessment Endpoints 

Assessment endpoints represent the actual environmental value that is to be protected and are 

defined by an ecological entity (species, community, or other entity) and its attributes or 

characteristics (US EPA, 1998). For the proposed TM uses, the ecological entities may include 

the following: birds, mammals, freshwater fish and invertebrates, estuarine/marine fish and 

invertebrates (pelagic and benthic dwelling), insects, and plants. The attributes for each of these 

entities may include growth, reproduction, survival, biomass (standing crop for plants). For both 

aquatic and terrestrial animal species, direct acute and direct chronic effects are considered. 

Although these endpoints are measured at the individual level, they provide insight about risks at 

higher levels of biological organization (such as populations and communities). 

E. Conceptual Model 

For a pesticide to pose an ecological risk, it must reach ecological receptors in biologically 

significant concentrations. An exposure pathway is the means by which a pesticide moves in the 

environment from a source to an ecological receptor. For an ecological pathway to be complete, 

it must have a source, a release mechanism, an environmental transport medium, a point of 

exposure for ecological receptors, and a feasible route of exposure.

A conceptual model is used in this risk assessment to provide a written and visual description of 

the predicted relationships between TM application, potential routes of exposure, and the 

predicted effects for the assessment endpoint. A conceptual model consists of two major 

components: risk hypothesis and a conceptual diagram (USEPA, 1998).

1. Risk Hypotheses 

Risk hypotheses are specific assumptions about potential adverse effects (i.e., changes in 

assessment endpoints) and may be based on theory and logic, empirical data, mathematical 

models, or probability models (EPA 1998). For TM, the following ecological risk hypothesis is 

being employed for this risk assessment:

 Given the proposed seed treatment uses of TM and its environmental fate properties, 

there is a likelihood of exposure to non-target terrestrial and aquatic organisms. 
17

 When used in accordance with the label, TM results in potential adverse effects upon the 

survival, growth, and reproduction of non-target terrestrial and aquatic organisms. 

2. Conceptual Diagram

Based on the preliminary iterative process of examining fate, transport and effects data, the 

conceptual model or the risk hypothesis model for seed treatment is established. In establishing 

the diagram for the conceptual model it is necessary to go through an iterative process to 

identify: (1) likely stressors/exposure pathways and (2) organisms that are most relevant and 

applicable to this assessment. 

The conceptual model diagram for aquatic receptors (including piscivorous wildlife) is shown in 

Figure 2, Figure 3, and Figure 4. Overall exposure of TM (and bound residues) to aquatic 

ecosystems is likely to be small due to the subsurface planting requirement on the proposed label 

and low application rate (restricted to <0.02 lb ai/A). However, there is some potential for TM to 

desorb from coated seeds during precipitation events and contaminate surrounding soil. 

Subsequently, erosion of contaminated soil and runoff may occur, thereby transporting TM to 

nearby surface waters. In addition, “drift” of abraded seed coatings (dust-off) is also a potential 

source of TM to offsite areas including water, as documented for other pesticides used for seed 

treatment (e.g., Krupke et al. 2012). Leaching to groundwater is considered a minor exposure 

route given the moderately high Koc values for TM (1600-6100 L/kgoc; Table 11). Similarly, 

although TM shows some propensity to volatilize, this pathway is considered minor due to 

subsurface planting of seeds and low application rates. Once in surface water, the moderately 

high logarithm of the octanol-water partition coefficient (log Kow=3.8; Table 4) and moderately 

high Koc indicate that the compound will likely partition to benthic sediments, but retain a 

potential for bioaccumulation in aquatic food webs, although primarily through direct uptake 

across respiratory membranes rather than biomagnification via the food web. 

The conceptual model diagrams for terrestrial receptors (excluding piscivorous wildlife) are 

shown in Figure 3 and Figure 4. For terrestrial vertebrate receptors (e.g., birds, mammals), 

potential routes of exposure to TM include direct ingestion of treated seeds (assuming some 

spillage and/or subsurface foraging), inhalation of abraded seed coating dust, and ingestion of 

plants and prey that have been contaminated with seed coat dust. Drift of seed coating dust is 

also a potential exposure route for some terrestrial invertebrates (e.g., bees) through direct 

contact. There is also a potential for TM to desorb from seeds and be taken up directly across the 

integument of soil-dwelling invertebrates, with subsequent exposure to consumers thereof. 

However, the non-systemic nature of TM in plants combined with its low application rate and 

high Koc suggest that root uptake of desorbed TM will be a limited route of exposure.
18

Figure 2. The aquatic conceptual model for seed-coat application of TM to seeds of agricultural 

crops (dotted lines indicate unlikely routes of chemical dissipation)

* Drift from abraded seed coatings during planting; ** Route of exposure includes only ingestion of fish and 

aquatic invertebrates; Blue arrows denote form of chemical stressor 

Stressor

Source

Receptors

Attribute

Change

TM Applied with Seeds

Aquatic animals

Invertebrates 

Vertebrates

**Piscivorous mammals 

and birds

Individual organisms

Reduced survival

Reduced growth

Reduced reproduction

Food chain

Reduction in algae and 

vascular plants

Reduction in prey

Modification of PCEs 

related to prey availability

Habitat integrity

Reduction in primary productivity

Reduced cover

Community change

Modification of PCEs related to 

habitat

Surface water/

Sediment

Runoff

Aquatic Animals

Invertebrates

Vertebrates

Exposure

Media

Uptake/gills 

or integument

Ingestion Ingestion

Atmospheric 

transport

Wet/dry deposition

Soil Leaching to

Groundwater

Uptake/gills 

or integument

Aquatic Plants

Non-vascular

Vascular

Uptake/cell, 

roots, leaves Riparian plants

(see terrestrial 

exposure CM)

TM & TM Bound Residues TM Only

Drift*
19

Figure 3. The terrestrial conceptual model for seed-coat application of TM to agricultural 

crops (excluding abraded seed coat drift; dotted lines indicate unlikely routes of chemical 

dissipation)

Stressor

Source

Attribute

Change

TM Applied with Seeds

Coated 

Seeds

Terrestrial 

vertebrates*

Terrestrial 

Inverts

Individual organisms

Reduced survival

Reduced growth

Reduced reproduction

Food chain

Reduction in prey and food

Modification of PCEs 

related to prey availability

Habitat integrity

Reduction in primary productivity

Reduced cover

Community change

Modification of PCEs related

to habitat

Terrestrial plants

grasses/forbs, fruit, seeds 

(trees, shrubs)

Runoff

Terrestrial 

vertebrates* 

Exposure Media 

& Receptors Soil

Ingestion

Ingestion

Dermal uptake/Ingestion

Atmospheric 

transport

Root uptake/contact

Wet/dry deposition

Ingestion

Leaching to

Groundwater

Irrigation 

water

TM Only TM & TM Bound Residues

TM Only

Ingestion

Blue arrows denote form of chemical stressor
20

Figure 4. The terrestrial conceptual model for seed-coat application of TM to agricultural 

crops via abraded seed coat drift (dotted lines indicate unlikely routes of chemical 

dissipation)

F. Analysis Plan 

1. Methods for Conducting Ecological Risk Assessment and Identification 

of Data Gaps 

The primary method used to assess risk in this screening-level assessment is the risk quotient 

(RQ) and follows the methods outlined in the EPA Overview Document (EPA, 2004). The RQ 

is the primary risk value for the screening-level assessment and is the result of comparing 

measures of exposure to measures of effect. A commonly used measure of exposure is the 

estimated exposure concentration (EEC) and commonly used measures of effect include toxicity

values such as the LD50 or NOAEC. The RQ is calculated as a ratio comparing the estimated 

environmental concentration (EEC) to an effect level (e.g., LC50, LD50 or NOAEC) using the 

effect level as a divisor. The resulting RQ is then compared to a specified level of concern 

(LOC), which represents a point of departure for concern. For example, if the RQ exceeds the 

LOC, then there is the potential for risk. In general, the higher the RQ, the more certain the 

potential risks. However, the risk quotients are not necessarily a true estimate of risk since there 

Stressor

Source

Attribute

Change

Application of TM Coated Seeds

Terrestrial 

vertebrates

Terrestrial 

invertebrates

Individual organisms

Reduced survival

Reduced growth

Reduced reproduction

Food chain

Reduction in prey and food

Modification of PCEs 

related to prey availability

Habitat integrity

Reduction in primary productivity

Reduced cover

Community change

Modification of PCEs related

to habitat

Exposure Media 

Receptors

Dermal/Ingestion/uptake 

across integument Inhalation

Dust/Air

Abraded Seed 

Coat Drift

Deposition 

onto soils, 

plants, prey

Terrestrial 

Plants

TM & TM Bound 

Residues

TM only

Blue arrows denote form of chemical stressor
21

is no estimated probability of effect. Risk presumptions, along with the corresponding RQs and 

LOCs, are summarized in Appendix E.

Generation of robust risk quotients is dependent on the quality of data from both fate and 

toxicological studies. The adequacy of the submitted data is evaluated relative to Agency

guidelines. The following identified data gaps for ecological fate and toxicity endpoints result in 

a degree of uncertainty in evaluating the ecological risk of TM.

For the ecological effects, the following data gaps were initially identified as part of the 

preliminary chemical screening analysis (D388586; Appendix C):

1. 850.1400: Fish Early-Life Stage (Saltwater fish). 

2. 850.4100: Seedling Emergence, Tiers 1 and 2

3. 850.4150: Vegetative Vigor, Tiers 1 and 2

4. 850.5400: Aquatic Plant Growth, Algae (blue green, diatoms), Tiers 1 and 2

5. 850.4400: Aquatic Plant Growth, Vascular Plant, Tiers 1 and 2 

6. Acute toxicity data for oxon degradates (e.g., TMO, DM-TMO)

For the current use, no major environmental fate data gaps are identified although some of the 

studies were classified as supplemental. It is noted, however, that and the corresponding 

environmental chemistry methods (ECMs) for the submitted independent laboratory validations 

(ILVs) need to be submitted by the registrant. 

In response to a waiver request submitted by the registrant for data gaps identified above, the 

need for these data was considered in the context of:

 the proposed use (seed treatment/subsurface incorporation)

 the maximum application rate (0.02 lb a.i/A)

 maximum expected aquatic and terrestrial EECs

 available toxicity data for TM (and other OP pesticides for plants). 

Based on these factors, EFED concluded that fulfillment of these data gaps would have a very

low potential to alter the risk assessment conclusions and a waiver was granted (D393184). 

Regarding oxons TMO and DM-TMO, these were found to be a minor degradate in soil and 

aquatic compartments of the environment. Although some OP oxons may be more toxic than the 

parent compound, the need for oxon toxicity data for TM was waived because even if the TMO

and DM-TMO oxons are assumed to be 100X more toxic than the parent, the risk to aquatic 

organisms would still be below levels of concern (Section IV.C). For terrestrial organisms, 

metabolism studies in mice and rat indicate rapid metabolism and excretion of orallyadministered TM into various degradates, including several oxons. Thus, acute and chronic 

toxicity data for mammals (and by extension, birds) would likely account for oxon formation in 

vivo. Importantly, however, this waiver is conditioned on the current proposed use pattern and 

application rates (seed treatment only) and would be subject to modification for any additional 

uses proposed in the future or additional information available in future registration review. 

Further details of the impact of these data gaps on the risk assessment conclusions are provided

in Section IV.C. 
22

2. Measures of Exposure 

Measures of exposure are estimates of exposure for a receptor determined by modeling or 

monitoring data. Measures of exposure for TM in this assessment are obtained from modeling 

efforts only, since this is a new chemical and national-scale monitoring data is not expected to be 

present. Exposure models used for this assessment include the suite of standard exposure models 

commonly used in pesticide risk assessments (EPA, 2004). Generally, aquatic exposure 

estimates are generated from EFED models and for seed treatment the model incorporate 

maximum proposed use rates, minimum seeding depth and empirically-derived fate properties.

For the proposed seed treatment use of TM, exposure to aquatic organisms is assumed to occur 

through direct contact with surface water contaminated by runoff/erosion from agricultural 

fields, drift from abraded seed coatings contaminated with TM, and with ground water 

contaminated by leaching. Aquatic exposure concentrations for this assessment are based on 

EECs calculated using Tier II linked, Pesticide Root Zone Model PRZM (v3.12.2, May 2005) 

and EXAMS (v2.98.4.6, April, 2005). PRZM/EXAMS are fate and transport simulation models 

coupled together with the input shell pe5.pl (August, 2007) to generate daily exposures and 1-in10 year EECs. In addition, estimation of TM bioaccumulation in aquatic organisms is based on 

the KABAM model (Kow (based) Aquatic Bio-accumulation Model, v. 1.0) and registrant 

submitted data on the bio-concentration factor. More information on these models can be found 

at this website5. It is noted at this time, that EFED does not have approved methods for 

quantifying surface water EECs resulting from contaminated dust (abraded seed coatings) or 

ground water discharge.

Measures of exposure for terrestrial mammals, birds, reptiles and amphibians similarly

incorporate maximum proposed use rates but rely less on fate properties. For TM, acute and 

chronic terrestrial exposure estimates from direct consumption of treated seeds are derived using 

the Terrestrial Residue Exposure Model (T-REX) version 1.5 (March, 2012)6. As with the 

aquatic exposure assessment, some aspects of the terrestrial exposure assessment cannot be 

addressed quantitatively at this time. These include direct and indirect exposure to abraded seed 

coating dust and dermal uptake from exposure to coated seeds. Exposures via atmospheric 

transport /inhalation, irrigation water, and off site runoff are assumed to be negligible based on 

the chemical properties, use pattern, and low acute and chronic toxicity of TM to birds and 

mammals. It is also worth noting that T-REX makes a couple conservative assumptions that may

overestimate exposure to avian and mammalian organisms. The first assumption is that T-REX 

assumes a diet of 100% treated seed. Secondly, T-REX does not take into account incorporation 

or planting depth and assumes that treated seeds are to be broadcast onto a field. As described in 

Section III of this assessment, label requirements of TM require the treated seeds to be planted 

anywhere from 0.32 to 3.81 cm deep, depending on the crop. Seeds planted at these depths 

would theoretically not be as available to birds and mammals as they would if they were 

broadcast on a field.

 

5

http://www.epa.gov/oppefed1/models/water/index.htm. 

6

http://www.epa.gov/oppefed1/models/terrestrial/.
23

Additionally, the Screening Imbibition Program (SIP) and the Screening Tool for Inhalation Risk 

(STIR) were used to determine if drinking water and/or inhalation, respectively, are potentially 

significant routes of concern for terrestrial animals. Results from these models indicate that 

drinking water and inhalation are not likely to be potential exposure routes of concern for the 

proposed seed treatment uses of TM.

3. Measures of Effects 

Measures of ecological effects are obtained from a suite of registrant-submitted guideline studies 

conducted with a limited number of surrogate species. Measures of effect are based on 

deleterious changes in an organism as a result of chemical exposure. Functionally, measures of 

effect typically used in risk assessments include changes in survival, reproduction, or growth as 

determined from standard laboratory toxicity tests. The focus on these effects for quantitative 

risk assessment is due to their clear relationship to higher-order ecological systems such as 

populations, communities, and ecosystems. Although monitoring data may also be used to 

provide supporting lines of evidence for the risk characterization, monitoring data is not 

available for this new chemical. Commonly used laboratory-derived toxicity values include 

estimates of acute mortality (such as LD50, LC50, or EC50) and estimates of effects due to longer 

term, chronic exposures (such as the NOAEC or NOAEL). In addition, effects other than 

survival, reproduction, and growth may be considered (such as changes in biochemical, cellular, 

organ-level responses), but these are typically used qualitatively to characterize risks since, in 

many cases, the relationship between these effects and higher-order processes is prone to more 

uncertainty. The latter can reflect changes seen in mortality, reproduction, or growth. In general, 

for a given assessment endpoint, the lowest relevant measure of effect is used in calculating the 

risk quotient. 

4. Measures of Ecosystem and Receptor Characteristics 

The assessment endpoints can be summarized as survival, growth, and reproduction of terrestrial 

and aquatic receptors to include birds, mammals, reptiles, amphibian, fish, terrestrial and aquatic 

invertebrates and terrestrial and aquatic plants. The response of these receptors to TM exposure 

is represented by a small number of toxicity studies on representative or surrogate species. 

Hence, there is considerable uncertainty regarding the response of a receptor since data for all 

species potentially exposed are not available. The lowest available measure of effect for a given 

assessment endpoint is used to calculate risk to accommodate for some of this inherent 

uncertainty. 

The ecosystems selected for modeling using PRZM/EXAMS aquatic assessment and T-REX for 

the terrestrial animal assessment are intended to be generally representative of any aquatic or 

terrestrial ecosystem associated with areas where TM is used. The receptors addressed by the 

aquatic and terrestrial risk assessments for TM are summarized in Table 1. For aquatic 

assessments, generally fish and aquatic invertebrates in both freshwater and estuarine/marine 

environments are represented. For terrestrial assessments, three different size classes of small 

mammals are represented, along with five potential foraging categories (short grass, tall grass, 

broadleaf plants/small insects, fruits/pods/seeds/large insects, and seeds). For the two different 

size classes of small birds, four potential foraging categories are considered (short grass, tall 
24

grass, broadleaf plants/small insects, and fruits/pods/seeds/large insects). In addition, data are 

available so that earthworms, terrestrial non-target insects, and sediment-dwelling organisms are 

represented. Detailed information regarding the toxicity data available for these various classes 

of aquatic and terrestrial receptors is provided in the Ecological Effects Characterization section 

and in Appendix D.
25

III. ANALYSIS

A. Use Characterization 

TM is proposed to be widely used in the US as a seed treatment to prevent and/or control certain 

fungal diseases on many crops. The chemical is formulated alone as a flowable. Table 3

contains a summary of all crops proposed to be treated with TM.

Table 3. Crop use patterns and application rates for the TM new chemical registration for 

seed treatment 

Table Continues into the next page

Crop Group 1 A: Root Vegetables (except: Burdock, Chervil; Turnip-rooted; Ginseng; Horseradish; Salsify, Black; Salsify, 

Spanish; and Skirret; 13 Crops): Application rate: 0.049 lb a.i/cwt seed

Beet, garden Turnip-rooted Parsnip

Beet, sugar Chicory Radish

Burdock, edible Parsley Radish, oriental

Carrot Turnip Rutabaga

Celeriac

Crop Group 3-07: Bulb Vegetables (with many exceptions “see label” 12 Crops): Application rate: 0.010 lb a.i/cwt seed

Chive Chinese, fresh leaves Leek (lady’s) Onion, Beltsville bunching

Chive, fresh leaves Leek (wild) Onion, bulb

Kurrat Onion Onion, fresh

Leek Onion, pearl Onion, green

Crop Group 4: Leafy Vegetables (Except Brassica Vegetables) (30 Crops): Application rate: 0.010 lb a.i/cwt seed

Arugula (roquette) Corn salad Parsley

Cardoon Cress, garden Purslane, garden

Celery Cress, upland Purslane, winter

Celery, Chinese Dandelion Rhubarb

Celtuce Dock (sorrel) Spinach

Chervil Endive (escarole) Spinach, Chinese (Amaranth)

Chicory, red (radicchio) Fennel, Florence Spinach, New Zealand

Chrysanthemum, edible-leaved Lettuce, head and leaf Spinach, vine

Chrysanthemum, garland Orach Swiss chard

Crop Group 5: Brassica (Cole) Leafy Vegetables (16 Crops): Application rate: 0.010 lb a.i/cwt seed

Broccoli Collards Mustard greens

Broccoli cavalo Gailon Chinese Mustard spinach

Broccoli raab (rapini) Kale Napa Chinese

Brussels sprouts Kohlrabi Rape greens

Cabbage Chinese (bok choy) Mizuna

Cauliflower Mustard Chinese (gai choy)

Crop Group 6: Legume Vegetables (Succulent or Dried) (44 Crops): Application rate: 0.010 lb a.i/cwt seed
26

Table Continues into the next page

Bean, Lupiinus: grain lupin Bean, Vigna: adzuki bean Guar

Bean, Lupiinus: sweet lupin Bean, Vigna: asparagu bean Lentil

Bean, Lupiinus: white lupin Bean, Vigna: blackeyed pea Pea, Pisum: dwarf pea

Bean, Lupiinus: white sweet lupin Bean, Vigna: catjang Pea, Pisum: edible-podded pea

Bean, Phaseolus: field bean Bean, Vigna: Chinese longbean Pea, Pisum: English pea

Bean, Phaseolus: kidney bean Bean, Vigna: cowpea Pea, Pisum: field pea

Bean, Phaseolus: lima bean Bean, Vigna: crowder pea Pea, Pisum: garden pea

Bean, Phaseolus: navy bean Bean, Vigna: moth bean Pea, Pisum: green pea

Bean, Phaseolus: pinto bean Bean, Vigna: mung bean Pea, Pisum: snowpea

Bean, Phaseolus: runner bean Bean, Vigna: rice bean Pea, Pisum: sugar snap pea

Bean, Phaseolus: snap bean Bean, Vigna: southern pea Pea: Chickpea (garbanzo)

Bean, Phaseolus: tepary bean Bean, Vigna: urd bean Pea: Pigeon pea

Bean, Phaseolus: wax bean Bean, Vigna: yardlong bean Soybean

Bean: Broad bean (fava) Bean: Lablab bean Soybean (immature seed)

Bean: Jackbean Bean: Sword bean

Crop Group 8-10: Fruiting Vegetables (22 Crops): Application rate: 0.010 lb a.i/cwt seed

Cocona Martynia Sunberry

Eggplant Naranjilla Tomatillo

Eggplant, African nonbell pepper Tomato

Eggplant, scarlet Okra Tomato, Bush

Eggplant,pea Peper (bell) Tomato, currant

Goji berry Peper (nonbell) Tomato, tree

Groundcherry Pepino

Huckleberry, garden Roselle

Crop Group 9: Cucurbit vegetables (38 Crops): Application rate: 0.010 lb a.i/cwt seed

Cantaloupe Melon, citron Squash, winter acorn

Chayote (fruit) Melon, Muskmelon Squash, winter, butternut

Cucumber Momordica spp (balsam apple) Squash, winter, hubbard

Gherkin Momordica spp (balsam pear) Squash, winter, spaghetti

Gourd, edible (Chinese okra) Momordica spp (bittermelon) Squash, winter,calabaza

Gourd, edible (cucuzza) Momordica spp (Chinese cucumber) Watermelon

Gourd, edible (hechima) Pumpkin Waxgourd, Chinese (Preserving melon)

Gourd, edible (hyotan) Squash, summer

Crop Group 15: Cereal Grains (except rice and wild rice; 11 Crops): Application rate: 0.010 lb a.i/cwt seed

Barley Millet, proso Sorghum (milo)

Buckwheat Oats Teosinte

Corn Corn (popcorn) Wheat (triticale)

Millet, pearl Rye

Crop Group 17: Grass, Forage, Fodder, and Hay: Application rate: 0.009773 lb a.i/cwt seed

Grass, any grass Grass, pasture and range grasses grown for silage or hay.
27

Table Continues into the next page

Crop Group 18: Non-Grass animal Feeds (Forage, Fodder, Straw, and Hay); (12 Crops): Application rate: 0.010 lb 

a.i/cwt seed

Alfalfa Kudzu Trefoil

Bean, velvet Lespedeza Vetch

Clover: Melilotus Lupin Vetch, crown

Clover: Trifolium Sainfoin Vetch, milk

Crop Group 19: Herbs and Spices (69 Crops): Application rate: 0.009773 lb a.i/cwt seed

Allspice Cinnoamon Nasturtium

Angelica Clary Nutmeg

Anise Clove buds Parsley (dried)

Anise, star Costmary Peenyroyal

Annatto (seed) Culantro, leaf Peper, white

Balm Culantro, seed Pepper, black

Basil Cumin Poppy (seed)

Borage Curry (leaf) Rosemary

Burnet Dill (dillweed) Rue

Camomile Dill (seed) Saffron

Caper buds Fennel (common) Sage

Caraway Fennel Florence (seed) Savory, summer and winter

Caraway, black Fenugreek Star

Cardamom Grains of Paradise Sweet bay

Cassia bark Horehound Tansy

Cassia buds Hyssop Tarragon

Catnip Juniper berry Thyme

Celery seed Lavender Vanilla

chamomile Lemongrass Wintergreen

Chervil (dried) Lovage (leaf) Woodruff

Chive Lovage (seed) Wormwood

Chive, Chinese Mace

Cilantro or coriander, leaf Marigold, marjoram

Cilantro or coriander, seed Mustard (seed)

Crop Group 20: Oilseeds (Crop Group 20, except cotton; 31 Crops): Application rate: 0.010 lb a.i/cwt seed

Borage Jojoba Rosehip

Calendula Lesquerella Safflower

Castor oil plant Lunaria Sesame

Chinese tallowtree Meadow foam Stokes aster

Crambe Milkweed Sunflower

Cuphea Mustard seed Sweet rocket

Echium Mustard: hare’s ear mustard Tallowwood
28

Table Continues into the next page

Euphorbia Niger seed Tea oil plant

Evening primrose Oil radish Vernonia

Flax seed Poppy seed

Gold of Pleasure Rapeseed

Cotton: Application rate: 0.049 lb a.i/cwt seed

Conifers: Application rate: 0.010 lb a.i/cwt seed (Note: X-mass trees are conifers or pine)

Ornamental Flowers: Application rate: 0.010 lb a.i/cwt seed
29

B. Exposure Characterization 

In this section, the physical/chemical and laboratory fate and transport properties (mobility) of 

the chemical will be discussed. The chemical is of low solubility, semi volatile. TM is stable to 

photolysis on soil, almost stable to photolysis in water (t1⁄2= 153 days) and slightly affected by

hydrolysis (t1⁄2= 62 days). In aerobic soil and aquatic systems, the chemical is moderately 

persistent (t1⁄2 range= 16-79 days; n=10 in aerobic soil and t1⁄2 range= 18-26 days in aerobic 

aquatic systems; n=2). In contrast to aerobic systems, TM is slightly more persistent (t1⁄2 range= 

34-87 days n=3 in anaerobic soil and t1⁄2 = 47 days in anaerobic aquatic systems; n=1). In all of 

these laboratory systems, three major important processes were found to affect the chemical, 

namely: mineralization to CO2, formation of persistent un-identified bound residues and 

degradation into few major to minor degradates and many very minor degradates. The major/

minor degradates include DM-TM (mostly a major degradate), DC-ph-CH3 (mostly a major 

degradate), ph-CH3 (mostly a minor degradate), and oxons including DM-TMO and TMO 

(minor degradates). All of these degradation products were observed in all systems and show 

decline to low levels and in most cases reach levels that were below the limit of detection.

Finally, this section includes a summary of expected degradation pathway for TM in soil and 

aquatic systems. Degradation pathway was used to identify relevant residues of concern (parent 

+ bound residues) based on expected exposure concentrations and toxicities. It is noted that a

summary of all environmental fate studies is provided in Appendix G.
30

1. Environmental Fate and Transport Characterization 

a. Physical and chemical properties

The physical and chemical properties of TM are summarized in Table 4. 

Table 4. Physical and chemical properties of TM

Property Description or Value Reference (MRID Or Others)

CAS name O-(2,6-dichloro-4-methylphenyl) O,O-dimethyl phosphorothioate

Registrant Data

IUPAC name O-2,6-dichloro-p-tolyl O,O-dimethyl phosphorothioate

Molecular formula C9H11Cl2O3PS

Molecular weight 301.12 g/mol

CAS number 57018-04-9

PC code 128905 EPA

Solubility

Water: 1.10 ± 0.08 ppm @ 25 ̊C

 0.708 ± 0.06 ppm @ 20 ̊C (pH 7 to 7.5) 

Solvents: 

 476 x 103 ppm in acetone; 

 343 x 103 ppm in xylene; 

 20 x 103 ppm in n-hexane; and

 38 x 103 ppm in methanol

Water

FAO1and 483419-14

Respectively

Solvents

Footprint2

Vapor pressure 1.38 x 10-5

torr @ 24.8 °C (Percent deviation= 15%); 417018-01

Henry’s law constant 3.68 x 10-6

atm m3 mole-1 Calculated from value at 20 °C 

(483419-01)3

UV/Visible spectra 

(190 to 700 nm) @ pH 

7.2 and 25 ̊C

Absorption spectra shows very limited absorption in the visible 

range (>300- 400 nm) with absorption limited to the 190- 300 nm

range. Peak absorption was at 215.5 nm (wide peak) with lower 

absorption at 275.0 and 282.5 (narrower peaks with height of ≈ 22 

and 24%, respectively, of the peak absorption at 215.5 nm)

483419-12

Stability in air t1⁄2= 5.3 hours 483419-45 (Calculated) using 

Atkinson method

Kow 6,310 (Log Kow = 3.8) @ 25 oC (483419-13)4

1 FAO (visited 01/21/12): http://www.fao.org/ag/AGP/AGPP/Pesticid/JMPR/Download/94_eva/tolclofo.pdf

2 Footprint (visited 01/21/12): http://sitem.herts.ac.uk/aeru/footprint/en/index.htm

3 Calculated from a value that was calculated by the registrant (MRID 483419-01) to equal 3.73 10-1

Pa m3 mole-1 Or 3.68 x 10-6

atm m3 mole-1 @ 20 °C (48341901; calculation was based on molecular weight, vapor pressure= 8.77 x 10-4Pa (MRID 483419-

15. Or 6.58x10-torr at @ 20 °C and solubility= 0.708 ppm (MRID 483419-14)

4 Estimated by Liquid Chromatography, noting that a value of 36,308 (Log Kow = 4.56) @ 25 oC was reported, by the registrant 

earlier 

The chemical is characterized by a low water solubility of nearly 1 ppm in neutral conditions. 

The chemical has relatively high to moderate potential for volatilization from dry and wet 

surfaces. Therefore relatively high partitioning to the air is expected and the amount that 

partitions into the air is expected to degrade rather quickly (t1⁄2= 5.3 hours) presumably by 

reacting with hydroxyl radicals in the troposphere.
31

As stated previously, the measured vapor pressure for TM is 1.38x 10-5torr (MRID 417018-01) 

and the calculated Henry’s law constant is 3.68 x 10-6atm m3 mole-1. This suggests that the 

chemical is semi volatile from wet/dry surfaces. Volatility was also confirmed by the presence of 

relatively high amounts of volatile organics in the traps for volatile organics connected to some 

aerobic soil/aquatic experiments (Table 5).

Table 5. Maximum quantities of organic volatiles found in different biotic studies (ED= 

Experimental duration in days; ED= Experiment duration in days; T= Incubation temperature in oC; and 

AR= Application rate ppm) 

System MRID Number ED T AR Maximum Volatilized Organics (Type of Trap Used)1

Aerobic Soil 1

001561-06

180

25 20

19.6% @ 180 d 

Aerobic Soil 2 28.6% @ 180 d 

Aerobic/Sterilized Soil (1s)

30

0.2% @ 30 d

Aerobic/Sterilized Soil (2s) 0.4% @ 30 d

Aerobic Soil 3 427032-01 365 25 16

A total of 26% @ 365 d (18% Parent, 6% ME-phCH3 and 2% ph-CH3)

Aerobic Soil 4 483419-23

Supplemented 

W/483419-25 112 10 2.0

max= 0.22% @ 112 d (Ethanediol trap)

Aerobic Soil 5 max= 0.21% @ 112 d (Ethanediol trap)

Aerobic Soil 6 max= 0.22% @ 112 d (Ethanediol trap)

Aerobic Soil 7, 8, 9 & 10 483419-24 90 20 2.0 A total of 0.2 to 0.4% @ varied times from 3 to 90 d

Anaerobic Soil 1

001561-06 60 25 20

0.6% @ 60 d

Anaerobic Soil 2 1.1% @ 60 d

Aerobic Aquatic Syst. 1

483419-26 100 20 0.67

A total of 12.7 to 11.6% @ 62-100 d (Parent 

>95%)(Ethanediol + 2% paraffin/ xylene trap)

Aerobic Aquatic Syst. 2 A total of 21.8% @ 00 d (Parent >95%)

Anaerobic Aquatic Syst. 3 431281-01 364 25 16.5 A total of 2.5% @ 32 d (mostly Parent)

1 Maximum Volatilized Organics= As % of the applied radioactivity (Type of Trap Used= Type of trap used was ethylene glycol except as 

indicated)

Based on data summarized in Table 5, above, the following can be concluded:

(a) Volatile organics ranged from 13 to 29% in traps associated with aerobic soils 1-3 and 

aerobic aquatic systems 1 & 2; noting the traps used either ethylene glycol or ethanediol + 

2% paraffin/xylene;

(b) Volatile organics ranged from 0.21 to 0.22% in traps associated with aerobic soils 1s, 2s, and 

4-5; noting the traps used ethylene glycol;

(c) Volatile organics were <1% in traps associated with aerobic soils and 7-10; noting the traps 

used ethanediol and ethylene glycol, respectively;

(d) Volatile organics ranged from 1 to 3% in traps associated with anaerobic soils/aquatic 

systems; noting the traps used ethylene glycol; and
32

H

H

H

H

H

H

H

H

H

O

O

P

S

O

Cl

Cl

*

* Radiolabel Position

(e) Trapped organics were mostly parent and volatile degradates (Me-ph-CH3 and ph-CH3).

The above conclusions suggest parent and degradates Me-ph-CH3 and ph-CH3 are expected to 

volatilize from some aerobic soils and from aerobic aquatic systems. However, volatility appears 

to be restricted in other aerobic soils (i.e., soils 4 to 10), especially if it is assumed that ethanediol 

alone is effective in trapping volatile organics compared to ethylene glycol. In contrast, volatility

appears to be restricted in anaerobic soils (n=2) and aquatic systems (n=1); noting that the 

number of systems examined were only three and more systems need to be examined to support 

this conclusion.

Expected effects of volatility on exposure will be discussed later as it will be affected by TM use 

pattern. TM is applied in association with seeds that would be planted at depths 0.32 to 3.81 cm;

broadcast of treated seeds is not allowed as per the label.

Finally, the n-octanol water partition coefficient (Kow) of TM is 6,310 (log Kow=3.8) suggesting a 

potential for bio-concentration in aquatic organisms such as fish.

c. Fate and Transport Properties

The fate and transport behaviour of TM has been investigated in a series of laboratory and field 

studies. Laboratory studies were all conducted with 

14

C-labelled active substance uniformly 

labelled in the phenyl ring (Figure 5).

Figure 5. Position of radiolabel for TM used in fate and transport studies

Abiotic Degradation 

TM labeled at the [phenyl 14C] was used in conducting hydrolysis and photolysis studies. Data 

are summarized in Table 6 and show that the chemical is slightly affected by hydrolysis (t1⁄2= 61 

days @ pH 7) with main degradation products being DM-TM and TMO (major degradates) and 

pH-CH3 (a minor degradate) (MRID 417147-01). Photolysis in water (t1⁄2= 153 days) and on soil 

(stable) is not expected to be important processes for TM dissipation in the environment.
33

Table 6. Fate properties of TM in abiotic systems

Property, Description or Value, and Study References

(1) Hydrolysis (MRIDs 417147-01 and 483419-21; respectively are both “Acceptable”)

t1⁄2= 61 days @ pH 7; 51 days @ pH 5; 62 days @ pH 9@ initial concentration of 0.11 ppm and 25 oC for 30 days

Major degradates @ pH 7: Minor degradates @pH 7:

DM-TM: max= 16% @ 30 days ph-CH3: max= 0.4% @ 30 days

TMO: max= 12% @ 30 days

Experiment conducted at high temperatures (50, 62 & 74 oC) shows that the chemical was highly unstable at these temperatures 

and that it degrades into two main degradates DM-TM and ph-CH3 (MRID 483419-21)

(2) Aqueous photolysis (MRID 414229-02; “Acceptable”)

t1⁄2= 153 days @ pH 7 (corrected for dark control and for 12 hr/12hr cycle)

Major degradates: Maximum in Irradiated Samples Maximum in Dark Control Samples

DM-TM 12.6% @ 30 d 7.3% @ 21 d declined to 5.4% @ 30 d

Minor degradates:

ph-CH3, DM-TMO, TMO & TM-SCH3

 0.2-1.3% @ 30 d Not determined-1.5% @ 30 d

Other un-identified degradates (total) 11.1% @ 30 d 7.3% @ 21 d declined to 5.4% @ 30 d

CO2

 <0.1% @ 30 d <0.1% @ 30 d

Others:

Organic volatiles: None

(3) Soil photolysis (MRID 425360-01; “Acceptable”)

Stable (The chemical degraded faster in the dark than when irradiated on a sandy loam soil from Tulare county at a rate of 16 lbs 

a.i/A and 25 oC for 30 days (Soil 70% sand, 18% silt, 12% clay, 7 meq/100g CEC, 1.32% organic matter, and pH 7.1)

Light source: Natural sunlight in Richmond, California at latitude 37.45N, longitude 122.26W.

Major degradates:

None

Minor degradates:

Maximum in Irradiated Samples Maximum in Dark Control Samples

SM-TM 6.2% @ 30 d 2.5% @ 30 d

DM-SM-TM 1.0% @ 25 d decreased to 0.2% @ 30 d 7.6% @ 30 d

Other un-identified degradates (total) 3.4% @ 30 d 2.7% @ 25-30 d

CO2 max= 1.1% @ 30 d max= 1.1% @ 30 d

Others: Organic volatiles: No significant amount detected; Bound residues: max 6.40% @ 25 days declining to % 3.8% @ 30 

days (irradiated samples) compared to a max of 1.5% @ 18 days declining to % 1.1% @ 30 days (dark control samples)

Biotic Degradation

Biotic degradation was investigated in the laboratory in eleven soils and three aquatic systems 

and in five field soils in GA, OH, CA, LA and MO. Characteristics for these systems are 

summarized in Table 7.
34

Table 7 Available data for characteristics of soil and aquatic systems used in laboratory biotic studies.

Designation System Characteristics

Soil 1

Sapporo clay loam from Japan (Allophane clay mineral) incubated for 180 days and 30 days when 

sterilized @ 25 oC (Application rate 20 ppm). The soil is characterized by 48% sand, 28% silt, 24% 

clay, 39 meq/100g CEC, 11.6% OM, and pH 5.3 (MRID 001561-06)

Soil 2

Azuchi sandy clay loam from Japan (kaolinitic) incubated for 180 days and 30 days when satirized @ 

25 oC (Application rate 20 ppm). The soil is characterized by 62.5% sand, 17% silt, 20.5% clay, 39 

meq/100g CEC, 0.4% OM, and pH 5.5(MRID 001561-06)

Soil 3

A sandy loam soil from Tulare county, CA incubated for 365 days @ 25 oC (Application rate 16 ppm= 

equivalent to 32 lbs a.i/A to a depth of 6”). The soil is characterized by 70% sand, 18% silt, 12% clay, 

7 meq/100g CEC, 0.8% OM, and pH 7.1) ( MRIDs: 427032-01, 428183-01)

Soil 4

Sandy loam from the UK (Abington; pH 7.7 and OM 2.6% (MRID 483419-23 supplemented by 

483419-25)

Soil 5

Loamy sand from the UK (Shuttle worth; pH 6.0 and OM 2.4%) (MRID 483419-23 supplemented 

by 483419-25)

Soil 6

Silt loam from the UK (Terling; pH 5.2 and OM 4.6%) (MRID 483419-23 supplemented by 483419-

25)

Soil 7 Sandy loam from the UK (PT-102): pH 6.9-7.1 and OM 4.3% (MRID 483419-24)

Soil 8

Sandy loam from the UK (PT-103; sand 75%, 12% silt, 13% clay; pH 4.1-5.5; CEC= 6.1 meq/100 g; 

and OM 2.1-2.4%) (MRIDs 483419-22 for DM-TM; 483419-24)

Soil 9 Clay loam from the UK (SK 15556090): pH 6.2-6.7 and OM 7.8% (MRID 483419-24)

Soil 10 Clay loam from the UK (SK 960087): pH 7.2-8.0 and OM 4.7% (MRID 483419-24)

Soil 11

Sandy loam from the UK (SK 108672; sand 20%, 53% silt, 27% clay; pH 6.0-6.2; CEC= 20.0 

meq/100 g; and OM 5.2%) (MRIDs 483419-22 for DM-TM)

Soil 12

Sandy loam from the UK (SK 920191; sand 36%, 29% silt, 35% clay; pH 7.5-8.1; CEC= 31.0 

meq/100 g; and OM 3.4%) (MRIDs 483419-22 for DM-TM)

System 1

Pond water: pH=7.9 and sandy silt loam sediment from the UK: pH 6.9-7.2, CEC 29.8 meq/100g and 

OM 12.7% (MRID 483419-26)

System 2

Lake water: pH=6.6and sandy loam sediment from the UK: pH 5.7-6.1, CEC 16.2 meq/100g and OM 

5.8% (MRID 483419-26)

System 3

Soil/water: sandy loam soil: water incubated for 364 days @ 25 oC. The soil is sandy loam from Tulare 

county, CA (Application rate 16.5 ppm). The soil is Soil 3 (see above) (MRID 431281-01)

Abbreviations: OM= Organic Matter; CEC= Cation exchange capacity

Environmental fate data are summarized in Table 8. Data include results obtained from studies 

submitted for laboratory degradation: aerobic/anaerobic soil and water/sediment systems, field 

dissipation in terrestrial systems, and fish bio-concentration. A summary of these studies is also 

included in Appendix G. As shown in Table 8, aerobic degradation in soil and aquatic systems 

is a result of three major processes: mineralization to CO2, formation of bound residues followed, 

in importance, by degradation into few major to minor degradates and many minor degradates 

(usually <1% each). The degradation results from oxidation of the aryl methyl group and the P=S 

to P=O; and cleavage of the P-methyl and P-O-aryl moieties. The major/minor degradates 

include DM-TM (mostly a major degradate), ph-CH3 (mostly a minor degradate), and oxons 

including DM-TMO and TMO (minor degradates). All of these degradation products show 

decline to low levels and in most cases reaching levels that were below the limit of detection.

In contrast to aerobic systems, degradation in anaerobic soil/aquatic systems is slower but 

produce similar degradation products in addition to the unique degradate DC-ph-CH3.
35

Bioconcentration

The bioconcentration and transformation of TM was investigated using bluegill sunfish (Lepomis 

macrochirus) for 35-days exposure to radiolabelled TM (MRID 48737503). Bluegill were

exposed to 0.001 and 0.01 mg ai/L under flow-through conditions for 35 days followed by a 

depuration period of 14 days in clean water. These exposure concentrations are ~ 0.01X and 

0.001X the 96-h LC50 reported for TM with bluegill (>702 mg ai/L). Residues in water and 

tissue (including various metabolites) were measured on a weekly basis. The uptake data 

indicated that TM reached steady-state accumulation in fish quickly (within 3 days of exposure 

initiation). TM concentrations were stable in the water, but extensive degradation

occurred in the fish during the exposure phase. Major degradates included DM-TM-CH2OH, 

DCMP, and ph-CH2OH of which only DM-TM-CH2OH retained the thiophosphate ester moiety. 

Minor degradates included TMO and ph-COOH. The steady state BCF for total radioactive 

residues (TRR) was determined as 63-71 L/kg w.w. (edible tissue); 780-1054 L/kg w.w. (nonedible tissue) and 384-506 L/kg w.w. (whole body). Lipid fraction in whole body corresponding 

to these BCFs ranged from 4.3 to 4.5%. Depuration of TM (and TRR) was rapid, with whole 

body depuration half lives ranging from 0.41-0.42 days (TRR) and 0.31-0.38 days (TM).

An earlier study was conducted on bioconcentration of TM in bluegill sunfish (L. macrochirus) 

using labeled TM for 28 days followed by a 14-day depuration period (MRID 00163642). This 

study is classified as “supplemental” because exposure concentrations fluctuated beyond guideline 

recommendations and degradates were not characterized in the water. Despite these limitations, BCFs 

were similar to the previously described study and ranged from 120X (edible tissues), 1300X (nonedible tissues) and 770X (whole body).

 

Table 8. Fate properties of TM in biotic systems (Refer to Table 7 above for soil identification/

characteristics and to Appendix G for a details)

Study Soil

Half-life (t1⁄2 in 

days) Observed Maxima of degradates

(% of the Applied Parent)

MRID Number 

Parent TTR “Classification” 1

Aerobic 

soil 

metabolism

Soil 1 48 239

Major degradates (>10%): CO2; and DM-TM

Minor degradates:1-4%: DM-TMO; and ph-CH3;

<1%: TM-COOH; TM-CH2OH; TMO-COOH; TMOCH2OH; ph-COOH; and ph-CH2OH 

001561-06 

“Supplemental

”

Soil 1 

(Sterilized) 80 NC

Major degradates (>10%): None

Minor degradates: 1-3%: ph-CH3; <1%: DM-TM; DMTMO; TMO; TMO-COOH; TMO-CH2OH; TM-COOH; 

TM-CH2OH; ph-COOH; ph-CH2OH; and CO2

Soil 2 44 210

Major degradates (>10%): CO2

Minor degradates:1-5%: DM-TM; DM-TMO; and phCH3; <1%: TM-COOH; TM-CH2OH; TMO; TMOCOOH; TMO-CH2OH; ph-COOH; and ph-CH2OH
36

Study Soil

Half-life (t1⁄2 in 

days) Observed Maxima of degradates

(% of the Applied Parent)

MRID Number 

Parent TTR “Classification” 1

Soil 2 

(Sterilized) 116 NC

Major degradates (>10%): None

Minor degradates:1-3%: DM-TM; and ph-CH3;

<1%: DM-TMO; TMO; TMO-COOH; TMO-CH2OH; 

TM-COOH; TM-CH2OH; ph-COOH; ph-COOH; phCH2OH; and CO2

Soil 3 79 161

Major degradates (>10%): CO2; and DM-TM

Minor degradates:1-3%: ph-CH3; <1%: DM-TMO; DMTMO-COOH; TM-COOH; TM-CH2OH; TMO-COOH; 

TMO-CH2OH; ph-COOH; and SM-TM

427032-01 

“Acceptable”

Soil 4 28 116

Major degradates (>10%): CO2

Minor degradates: 2%: TM-COOH; <1%: DM-TM; DMTMO; TMO; TM-COOH; ph-COOH; and ph-CH2OH

483419-23 

Supplemented 

by 483419-25 

“Supplemental”

Soil 5 23 169

Major degradates (>10%): CO2

Minor degradates: Degradates Not Tracked

Soil 6 31 165

Major degradates (>10%): CO2

Minor degradates: Degradates Not Tracked

Soil 7 17 139

Major degradates (>10%): CO2

Minor degradates: 1%: DM-TM; and ph-CH3

483419-24 

“Acceptable”

Soil 8 16 128

Major degradates (>10%): CO2; and DM-TM

Minor degradates:8%: ph-CH3

Soil 9 16 114

Major degradates (>10%): CO2

Minor degradates: 4%: DM-TM; and ph-CH3

Soil 10 17 98

Major degradates (>10%): CO2

Minor degradates: 4%: ph-CH3 <1%: DM-TM

Aerobic/ 

Anaerobic Soil 

Metabolism

Soil 3:

Aerobic Phase 53 NC

Major degradates (>10%): DM-TM

Minor degradates: 4%: CO2; and ph-CH3

428183-01 

“Acceptable”

Soil 3: 

Anaerobic Phase 87 NC

Major degradates (>10%): DM-TM

Minor degradates: 3 & 8%: CO2 (3%); and ph-CH3 (8%)

Anaerobic Soil 

Metabolism

Soil 1 36 107

Major degradates (>10%): None

Minor degradates: 2-8%: DM-TM; DM-TMO; TMO; and

ph-CH3; <1%: CO2; TMO-COOH; TMO-CH2OH; TMCOOH; ph-COOH; and ph-CH2OH

001561-06 

Soil 2 57 161 “Supplemental”

Major degradates (>10%): None

Minor degradates:1-7%: DM-TM; DM-TMO; TMO; and

ph-CH3; <1%: CO2; TMO-COOH; TMO-CH2OH; TMCOOH; ph-COOH; and ph-CH2OH

Aerobic 

Aquatic 

Metabolism

System 1 19 49

Major degradates: (24-53%): CO2; and DM-TM

Minor degradates:3-7%: DM-TMO; and ph-CH3; <1%:

TM-COOH

483419-26 

System 2 26 65 “Acceptable”

Major degradates: (13-36%): CO2; and DM-TM

Minor degradates:3-5%: DM-TMO; and ph-CH3; <1%:

TM-COOH

Anaerobic 

Aquatic 

Metabolism System 3 47 95

Major degradates: (10-58%): CO2; DC-ph-CH3; and DMTM

Minor degradates: 5-8%: ph-Cresol; and ph-CH3

431281-01 

“Acceptable”

Aerobic Soil 

Metabolism Soil 8 1.22 NC

Major degradates: (15-19%): CO2; and ph-CH3

Minor degradates: 9%: DM-TMO; <1%: ph- COOH

483419-22 

“Acceptable”
37

Study Soil

Half-life (t1⁄2 in 

days) Observed Maxima of degradates

(% of the Applied Parent)

MRID Number 

Parent TTR “Classification” 1

(Test Substance: 

DM-TM (major 

TM degradate)

Soil 11 0.62 NC

Major degradates: (13-23%): CO2; and ph-CH3

Minor degradates: 6%: DM-TMO; <1%: ph- COOH

Soil 12 0.32 NC

Major degradates: (12-20%): CO2; and ph-CH3

Minor degradates:8%: DM-TMO; 1%: ph- COOH

Terrestrial 

Field 

Dissipation

TFD data were submitted between April 1987 and November 1988 in support of registration of 

the chemical as seed treatment and soil application on several terrestrial food and non-food crops. 

The chemical was applied to bare soil (not with treated seeds) at a significantly higher rate than 

expected to accompany treated seeds (5.5 to 24 lbs a.i/A compared to 0.02 labs a.i/A). Therefore, 

results from these studies (MRIDs 001561-11 and 265176-08) are probably not relevant to the 

current assessment and are not discussed here.

001561-11

and

265176-08

Fish 

Bioconcentration

Bluegill sunfish (35-day exposure period and 14-day depuration period): 

Max. Steady State BCFs (TRR): 71x (edible tissues), 1054x (non-edible tissues), and 506x

(whole fish)

Bluegill sunfish (28-day exposure period and 14-day depuration period): 

BCFs: 120x (edible tissues), 1,300x (non-edible tissues), and 770x (whole fish) 

48737503

“Acceptable”

00163642

“Supplemental”

1 TTR= Total Toxic Residues= Parent+ Bound Residues, 

2 Very short half-life resulting from the formation of un-identified bound residues (71-84% of the applied radioactivity)

NC= TTR Half-lives were not calculated for sterilized soils and for soils with low bound residues (<5%)

Bound residue

High percentages of bound residues were observed in most biotic degradation studies (Table 9).

These bound residues were relatively persistent and were quantified by radioactivity as percent 

of applied parent but the nature of these residues were not identified. The residues were only 

characterized by partitioning into fulvic and humic acids following harsh extraction by 0.5N 

NaOH.

Table 9. Percentages of bound residues found in different biotic studies following varied extraction 

procedures studies (ED= Experimental duration in days; T= Incubation temperature in oC; AR= 

Application rate ppm; and EP= Extraction Procedure Number “refer to Error! Reference source not 

found.Error! Reference source not found.Table 10. for description of the procedures”)

System MRID # ED T AR EP Maximum Bound residues (% of Applied Radioactivity 

Aerobic Soil 1

001561-06

180

25 20 1

53.4% @ 120 d declined 50.8% @ 180 days (d)

Aerobic Soil 2 46.6-47.0% @ 120-180 d

Aerobic/Sterilized Soil 1

30

19.1% @ 30 d

Aerobic/Sterilized Soil 2 11.0% @ 30 d

Aerobic Soil 3 427032-01 365 25 16 2 21.0% @ 271 d declining to % 19.0% @ 365 d

Aerobic Soil 4 483419-23 112 10 2.0 3 44.0% @ 84 d declined to 41.9% @ 112 d
38

Aerobic Soil 5 Supplemented 

W/483419-25

61.0% @ 84 d declined to 54.5% @ 112 d

Aerobic Soil 6 52.2% @ 112 d

Aerobic Soil 7

483419-24 90 20 2.0 4

63.6% @ 30 d declined to % 56.1 @ 90 d; 

Aerobic Soil 8 60.2% @ 15 d declined to 49.0% @ 90 d;

Aerobic Soil 9 55.9% @ 15 d declined to % 52.6% @ 90 d

Aerobic Soil 10 48.9% @ 30 d declined to 45.4% @ 90 d

Aerobic Soil 8

483419-22* 7 20 0.26 5

73.6% @ 3 d declined to 73.2% @ 7 d

Aerobic Soil 11 78.6% @ 3 d declined to 68.6% @ 7 d

Aerobic Soil 12 81.0% @ 0.7 d declined to 76.4% @ 7 d

Anaerobic phase (soil 3) 428183-01 60 25 16 2 4.1% @ 60 d

Anaerobic Soil 1

001561-06 60 25 20 1

39.0% @ 60 d

Anaerobic Soil 2 31.0% @ 30-60 d

Aerobic Aquatic System 1

483419-26 100 20 0.67 4

25.9% @ 62 d declined to 20.4% @100 d

Aerobic Aquatic System 2 35.0% @76 d declined to 19.9% @100 d

Anaerobic Aquatic System 3 431281-01 364 25 16.5 2 2.5% @ 32 d

* Test substance in all studies is 14C TM except for one aerobic soil study (MRID 483419-22) where it was 14C DM-TM; the major 

degradate of TF (Rows highlighted in light blue)

Five different extraction procedures were used in submitted biotic studies to extract residues 

from the soil and sediment. These procedures are summarized in Table 10.

Table 10. Description of extraction procedures used in soil and sediment extraction in 

biotic studies (Refer to Table 8 for a list of these studies)

Extraction 

Procedure 

(EP) Procedure Summary

EP 1 Once with 1 N HC1: Ethyl acetate (3:2) followed by Two times with Ethyl acetate alone → Bound Residues

EP 2 1

st Extraction (Acetone/water): Three times with Acetone: Water 1:5 (v:v) → Bound Residues-1

2

nd Extraction (Acetone/HCl): Three times with Acetone: 0.5N HCl 5:1 (v:v) → Bound Residues-2

EP 3

1

st Extraction: used for samples Up to 7 days: 

Soxhlet extracted with acetone : glacial acetic acid (98:2 v/v) for 18 hrs → Bound Residues

2

nd Extraction: used for samples >7 day contains more than 20% of applied radioactivity:

Additional three times extraction with 0.5M HC1 5:1 (v:v), three times.

Note: Additional recovery, from the second extraction procedure, was low

EP 4 Soxhlet extracted with acetone : glacial acetic acid (98:2 v/v) for 18 hrs → Bound Residues

EP 5

1

st Three times with acetone:0.01M HCl (5:1, v:v) → Bound Residues

Samples of each soil containing the highest concentration of un-extracted residues were Soxhlet-extracted 

overnight using acetone: glacial acetic acid (98:2, v:v). 

Note: Additional recovery, from the second extraction procedure, was <1% of applied radioactivity
39

Data in Table 9 and Table 10 show that acetone/water and acetone/HCl was the most effective 

extraction procedure (refer EP 2 in Table 9 and Table 10). The maximum levels were relatively 

low following EP 2 (3% in an anaerobic aquatic system and 21% in an aerobic soil system) 

compared to a higher range following EP 1 and EP 3-5 (a range of 26-35% in two aerobic 

aquatic systems and 31-64% in nine aerobic soil systems). The results for one soil (EP 2), under 

aerobic conditions and under anaerobic conditions are also shown in Figure 6 which also shows 

the change in the levels of bound residues with time and its relative persistence after reaching its 

maximum formation. Data in Figure 6 suggest that the second extraction step in EP 2 

(acetone/HCl) was able to significantly reduce levels of the maximum bound residues from 36% 

following the first step (with acetone/water) to 21% following the second step (with 

acetone/HCl). Data on the constituents of the second extraction show that additional parent and 

degradates were extracted suggesting that insufficient extraction may result in parent and 

degradates being part of the bound residues. Additionally, anaerobic conditions appear to reduce

the formation of bound residues (Figure 6).

Figure 6. Un-extracted bound residues following the most effective extraction procedure; extraction 

procedure 2 (EP 2, Table 9, above)

Based on data summarized in Table 9, Table 10 and Figure 6, the following may be concluded:

(1) With the exception of EP 2, the extraction methods may have not been successful 

in reaching complete extraction of the unidentified/unknown bound residues. 

These bound residues could be parent and/or major degradate(s). 

(2) The un-identified bound residues are of significant quantities and show relative 

persistence; and

(3) Relatively low bound residues are observed in anaerobic and sterilized systems 

compared to aerobic/viable systems. Examples include:

(a) The level of bound residues was 2.5% in anaerobic aquatic system; 

(b) The level bound residues in viable soil 1 was 53% compared to 19% 

Bound residues following two consecutive extractions for aerobic/anaerobic 

soils (MRIDs 427032-01 & 428183-01) 

0%

5%

10%

15%

20%

25%

30%

35%

40%

0 50 100 150 200 250 300 350 400

Time (dates)

Bound Residues (% of Applied

Radioactivity)

Bound Residues 1 (Solid fill markers:

Aerobic; No fill markers: anaerobic)

Bound Residues 2 (Solid fill markers:

Aerobic; No fill markers: anaerobic)
40

after sterilization;

(c) The level bound residues in viable soil 2 were 47% compared to 11% 

after sterilization; and

(4) The levels of bound residues were exceptionally high (74-81%) when DM-TM (a 

major degradate of TM) was used as test material. 

The above stated lines of evidence indicate that aerobic parent and degradates (e.g. DM-TM) 

might constitute part of the unidentified/unknown bound residues (item 1 above). Especially that 

the aerobic soil degradation profile for this DM-TM degradate resulted in high concentration of 

bound residues (item 4 above). Additionally the data indicates that the bound residues are

significant and relatively persistent. Bound residues were included as part of the stressor because 

of the possibility of presence of parent and degradates as part of these residues in addition to 

presence in significant quantities and its persistence.

Transformation Profile 

Figure 7 contains a summary of the expected transformation profile for TM in the natural 

environment based on laboratory studies. The degradation profile for TM shows the formation 

of many degradates but at relatively low concentrations. It also shows that the multi degradation 

products, including oxons, were not persistent as most degrade rather quickly to levels of no 

detection. Therefore, TM degradates are not included in the definition of the stressor of concern.

Additionally, the very low application rate for this chemical is expected to yield very low 

exposure EECs for the chemical itself and even much lower for degradates. 

Conservative exposure EECs for the combined parent and bound residues are chosen to represent 

expected exposure from parent, bound residues and degradates on the assumption that not all of 

the bound residues are of concern. The bound residues are included as part of the stressor 

because data shows that these un-identified bound residues are of significant quantities that may

not be ignored. However, this assumption is considered a conservative one and is expected to 

yield relatively conservative surface water exposure EECs.
41

 TM Parent

DM-TM SM-TM TMO (Oxon) Ph-CH3 TM-COOH

DC-ph-CH3

Me-ph-CH3

p-cresol

DM-TM-COOH ph-COOH

ph-CH2OH

Cleavage of P-O-aryl moiety

Abiotic + Biotic Degradation1

Cleavage of P-methyl moiety

Abiotic + Biotic Degradation1

Sulfur substitution @ aryl methyl group

Biotic Degradation1

Oxidation: P-S to P-O Abiotic + Biotic Degradation1

Oxidation @ aryl methyl group

Biotic Degradation1

DM-TM-COOH

DM-TMO (Oxon)

ph-CH3

ph-COOH

DM-TM

DM-TMO (Oxon)

ph-CH3

DM-TMO (Oxon)

ph-CH3

DC-ph-CH3

Me-ph-CH3

DC-ph-CH3

(Refer to structure below)

Me-ph-CH3

(Refer to structure below)

p-cresol

(Refer to structure below)

p-cresol

DM-TM-COOH

(Refer to structure below)

ph-COOH & pH-CH2 OH

(Refer to structure below)

ph-COOH & pH-CH2 OH
42

1Abiotic Degradation refers to hydrolysis which appear to cause the 1st degradation step (i.e. production of the 1st degradate).

Biotic degradation refers to observed degradtion in aerobic/anaerobic soil and aquatic systems. Noting that mineralization to CO2 and the 

formation of Bound Residues are important processes in the biotic degradation of this chemical.

Figure 7 Expected environmental degradation pathways for TM (degradates are color coded)

TM is expected to mineralize to CO2, form significant quantities of bound residues and produce 

many degradation products. Observed mineralization to CO2 ranged from 17 to 53% while bound 

residues reached maxima over 50% in some soil/aquatic systems. Submitted fate studies show 

that the chemical is affected by hydrolysis with main degradation products from hydrolysis being 

DM-TM and TMO (major degradates) and pH-CH3 (a minor degradate) (MRID 417147-01). In 

biotic studies, hydrolysis and biotic degradation may both occur, and TMO is a minor degradate. 

Aerobic and anaerobic degradation, in the soil and aquatic systems, suggest degradation into:

(a) Few major to minor degradates that may be categorized into two categories, namely:

i. DM-TM (maxima= 11-18% in some aerobic soils and <1-5% in others; 13-

24% in aerobic aquatic systems and 58% in anaerobic aquatic systems) and phCH3 (maxima= 1-8% in aerobic soil and aquatic systems). It is however noted 

that maximum observed levels in anaerobic soil are7-8% for DM-TM and 3-

4% for ph-CH3. In all soil/aquatic aerobic and anaerobic systems both DM-TM

and ph-CH3 decline to very low level and sometimes to no detection.

ii. Oxons: Observed only in soil/aquatic systems under aerobic conditions. Oxon 

degradates include: DM-TMO (observed at maximum levels ranging from <1-

5%) and TMO (observed at maximum levels of ≤1%). Both oxons show a clear 

decline following maxima. It is therefore concluded that the formation levels of 

oxons are low resulting in expected low concentrations in the natural 

environment.

iii. DC-ph-CH3: Reach maxima of 10% in anaerobic aquatic systems followed by

clear decline to 2%.

(b) Many minor degradates with concentrations usually <1% each resulting from oxidation of the 

P=S to P=O or the aryl methyl group and cleavage of the P-methyl and P-O-aryl moieties.

An aerobic soil study was submitted for the major degradate of TM; that is DM-TM. Data show 

that DM-TM degrades into CO2 (maxima ranging from 19-23%), ph-CH3 (maxima ranging 

from 12-15% followed by clear decline), DM-TMO (maxima ranging from 6-8% followed by 

clear decline) and large amounts of un-identified bound residues (maxima ranging from 74-81% 

with no clear decline during the 7-day experiment). 

The degradation profile for TM shows the formation of many degradates but at relatively low 

concentrations (Figure 7). It also shows that the multi degradation products, including oxons, 

were not persistent as most degrade rather quickly to levels of no detection. Therefore, TM 

degradates are not included in the definition of the stressor of concern. Additionally, the very

low application rate for this chemical is expected to yield very low exposure EECs for the 
43

chemical itself and even much lower for degradates. 

Conservative exposure EECs for the combined parent and bound residues are chosen to represent 

expected exposure from parent, bound residues and degradates on the assumption that not all of 

the bound residues are of concern. The bound residues are included as part of the stressor 

because data shows that these un-identified bound residues are of significant quantities that may

not be ignored. However, this assumption is considered a conservative one and is expected to 

yield relatively conservative surface water exposure EECs.

Mobility 

The adsorption/desorption characteristics of TM were determined for six soils which varied in 

organic matter and clay content (MRIDs: 422733-01 and 483419-19). Data are summarized in 

Table 11. Based on Koc values (range from 1,649 to 6,139 L/Kg with an average of 3,279

L/Kg), mobility of TM in the tested soils is classified as slightly mobile in accordance to the 

FAO mobility classification (FAO, 2000). Therefore, moderate mobility is expected in the 

natural environment which limits the possibility for contaminating the ground water resources.

Table 11. Adsorption/Desorption properties of TM

Property/Description or Value

Reference (MRID 

#)

Kd= 7.59 and Koc= 1,649 L/Kg in a Sandy Loam soil from California (0.46% organic carbon, 7 meq/100g CEC 

and pH of 7.1)

Kd= 25.17 and Koc= 6,139 L/Kg in a Loamy sand soil from Kentucky (0.41% organic carbon, 4 meq/100g CEC and 

pH of 7.6)

Kd= 43.96 and Koc= 3,209 L/Kg in a Silty clay Loam soil from Kentucky (1.37% organic carbon, 18 meq/100g 

CEC and pH of 6.7)

Kd= 24.03 and Koc= 3,482 L/Kg in a Clay soil from Kentucky(0.69% organic carbon, 24 meq/100g CEC and pH of 

7.3)

422733-01 

“Supplemental”

Kd= 32.4 and Koc= 2,655 L/Kg in a Loam soil from New Jersey (1.2% organic carbon, 9 meq/100g CEC and pH=

6.9)

Kd= 16.3 and Koc= 2,541 L/Kg in a Sand soil from Florida (0.64% organic carbon, 4 meq/100g CEC and pH= 6.1)

483419-19 

“Supplemental”

Environmental Chemistry Methods (ECMs)/Independent Laboratory Validations (ILVs) 

Environmental chemistry methods (ECMs) and associated Independent laboratory validations 

(ILVs) for residues in soil and water are used to evaluate analyses described in submitted 

environmental fate and ecological effects studies. These validated analytical methods are also 

used, in the future, by various Federal, State, Tribal, and local agencies to detect and monitor 

residues that are suspected to be in environmental compartments due to outdoor uses and 

accidental releases of registered chemicals. 

Three soil and water analytical methods were initially submitted, by the registrant as ILVs 
44

documenting methods developed by Covance laboratory for soil (MRID 48341916) and RRC 

laboratory for drinking (tap) water and surface (river) water (MRIDs 483419-17 and 483419-18, 

respectively) . These three methods were developed by the two laboratories, stated above, using 

German standard multi-residue methods. Therefore, These ILVs are considered, by the Agency, 

to be ECMs and were re-submitted as such under new MRID numbers (MRIDs 488421-02/01/03 

representing ECMs submittals for soil/drinking water/surface water, respectively). Therefore, the 

registrant is requested to submit ILVs for these ECMs which are to be conducted by independent 

laboratories other than the developers of the methods.

Submitted ECM for soil was developed by Covance laboratory based on the German multiresidue method S197

. The method determines TM in soil using GC/MS at the working range of 

0.01 and 10.0 mg a.i/Kg (MRID 488421-02 supplemented by and MRID 48341916). Overall 

recovery averaged 98 ± 12.4% (mean ± RSD, range 82-124%, n = 10) of the applied and the 

limit of detection (LOD) and quantitation (LOQ) for TM were established at 0.00295 mg/kg and 

0.01 mg/kg, respectively.

It is noted that the established working range of the method (between 0.01 and 10.0 mg a.i/Kg Or 

0.01 to 10 ppm) is appropriate because modeled diet-based EECs that may cause ecological risk 

in the soil is approximately 60 mg a.i/kg (60 ppm) based on chronic risks to small mammals 

consuming treated seeds (Needs dilution). However, most of the other expected concentrations 

were at least one to two orders of magnitude less than the highest soil EEC (60 ppm) that may

cause ecological risk from soil. Additionally, the highest bulk sediment EECs is in the range of 

0.0168 to 0.0169 ppm while lies within the working range of the method.

Submitted ECMs for drinking/surface waters were developed by RRC laboratory based on the 

German Multi-residue method F128. The methods determine TM in drinking (tap) water (MRID 

488421-01 supplemented by MRID 483419-17) and surface (river) water (MRID 488421-03 

supplemented by MRID 483419-18) at levels of 0.1 to 1.0 μg/L. Data on overall recoveries, 

LODs and LOQs were:

 For drinking (tap) water, overall recovery averaged 90.8 ± 5.8% (mean ± RSD, range 

81.8-100.1%, n = 10) of the applied. 

 For rural surface (river) water, overall recovery averaged 94.4 ± 10.3% (mean ± RSD, 

range 82.1-107.4%, n = 10) of the applied. 

 The limit of detection (LOD) for tolclofos-methyl was estimated, for both waters, at ca. 

 

7 The German multi-residue method S19 (EU guidance document SANCO/825/000): German Research 

Foundation (Deutsche Forschungsgemeinschaft, or DFG) method S19. DFG-Methode S19, § 35 LMBG 

(Lebensmittel Bundesgesetz) 00.00-34. Method S19 was published as “Modular Multimethod for Detecting 

Pesticide Residues in Foods” in 1999.

8 German Multi-residue method F12 (EU guidance document SANCO/825/000): German Standard Methods 

(Deutsche Einheitsverfahren), and referenced in "Hanel R., Siebers J. and Alder L.: "Anforderungen an 

Analysenmethoden zur Bestimmung von Pflanzenschutzmittelruckstandenim Rahmen des Zulassungsverfahrens", 

Nachrichtenbl. Deut. Pflanzenschutzd., 52, 2000, p. 292"
45

0.01μg/mL, based on lowest calibration standard. A limit of quantitation (LOQ) of 

0.1μg/L was established.

It is noted that the established working range of the method (between 0.1 to 1.0 μg/L Or 100 to 

1,000 ppb) is appropriate for parent TM because modeled surface water EECs range from 0.002 

to 0.344 ppb; and all concentrations were at least two order of magnitude less than the highest 

aquatic EECs that may cause ecological risk from surface water (3.9 ppb based on chronic 

effects to saltwater invertebrates). 

Finally, it is important to state that while these ECMs and associated ILVs are necessary for 

future use in detecting and monitoring residues that are suspected to be in environmental 

compartments due to outdoor uses and accidental releases.

2. Aquatic Exposure Assessment

Based on laboratory fate data, TM is expected to be slightly affected by hydrolysis (t1⁄2= 62 days) 

and biotic degradation in the soil system (90th % t1⁄2 in days for 10 soils= 40 days). However, 

degradation if TM in most systems containing soil or sediment produces relatively high amounts 

of bound residues. These bound residues were relatively persistent and were quantified by 

radioactivity as percent of applied parent but the nature of these bound residues was not 

identified. Due to concern about these bound residues, it was decided to include them in the 

residues of concern; meaning that the stressor is considered to be TM with the unidentified 

bound residues. Therefore, when considering these total residues of concern, the degradation 

half-lives become much longer than parent alone (90th percentile t1⁄2 for 10 soils= 171 days). The 

aquatic exposure assessment also made use of the measured vapor pressure for TM (1.38x 10-5

torr) and the calculated Henry’s law constant (3.68 x 10-6atm m3 mole-1). 

The label for TM contains a restriction on the maximum seeding rate for all crop groups to 200 

lbs treated seeds/A except root vegetable and cotton, which have limits of 40 and 50 lbs treated 

seeds/A, respectively. A further proposed label restriction limits applications to 0.02 lbs 

a.i/A/cropping cycle for all uses. Therefore, modeling for the total toxic residue (TTR= parent+ 

bound residues) was conducted for two different cases, namely:

(1) A conservative case (Case 1): which is the most conservative for all crops: in this case 

the application rate was assumed to equal 0.02 lbs a.i/A for all crop groups using 

scenarios that represent each of these groups with the minimum reported seeding depths; 

and

(2) A realistic (Case 2): which is still conservative for each representative crop from each 

crop group: in this case the application rate was calculated for each of the representative 

crops from the label application rate specified for its crop group and the seeding rate 

reported for that crop by BEAD Memo dated March 24, 2011. 

For example, in Case 1 (the conservative case), the application rate for crop group 15 (cereal 

grains) was considered to equal 0.02 lbs a.i/A (which is the restricted maximum rate= 200 lbs 
46

seeds “the maximum seeding rate allowed for this group” x 0.0098 lbs a.i/100 lbs of seed divided 

by 100 multiplied by 200= 0.0196 lbs a.i/A)9. Sixteen scenarios were chosen to represent this 

group: CAcornOP, FLsweetcornOP, ILCornSTD, KSsorghumSTD, MScornSTD, NCcorn OP, 

NDcornOP, NDwheatSTD, OHCornSTD, ORswcornOP, ORwheatOP, PA corn STD, 

STXcornNMC, TX corn OP, TXsorghumOP10 and TXwheatOP. All of these scenarios were run 

at the same maximum rate of 0.02 lbs a.i/A. Execution of modeling for this conservative Case 1

was necessary in order to cover exposure for crops, within each crop group, to which seeding 

rates were not reported by BEAD

In contrast, for Case 2 (the realistic case) more than one crop was modeled “to represent the 

same crop group 15” with the expected a.i rate/A calculated from BEAD seeding rate. The crops 

chosen included: 

 Wheat modeled at a rate equal to 0.01525 lbs a.i/A (calculated as follows: 156 lbs seed x 

0.0098 lbs a.i/100 lbs of seed divided by 100) using NDwheatSTD, ORwheatOP, and 

TXwheatOP; 

 Barley modeled at a rate equal to 0.00938 lbs a.i/A (calculated for its reported seeding 

rate of 96 lbs/A as shown for wheat above) using the same scenarios stated above for 

wheat; 

 Oat/rye modeled at a rate equal to 0.0088 lbs a.i/A calculated for its reported seeding 

rate of 90 lbs/A using the same scenarios stated above for wheat; 

 Corn modeled at a rate equal to 0.00324 lbs a.i/A calculated for its reported seeding rate 

of 33.2 lbs/A using CAcornOP, FLsweetcornOP, ILCornSTD, MScornSTD, NCcorn OP, 

NDcornOP, OHCornSTD, ORswcornOP, PAcornSTD, STXcornNMC, and TX corn OP; 

 Millet modeled at a rate equal to 0.00147 lbs a.i/A calculated for its reported seeding rate 

of 15 lbs/A using the corn scenarios stated above for corn; and 

 Sorghum modeled at a rate equal to 0.00089 lbs a.i/A calculated for its reported seeding 

rate of 9.1 lbs/A using KSsorghumSTD and TXsorghumOP.

Finally, ornamental flowers or flowering ornamental include: 

 Flowering annuals “planted/flower each season” such as petunia, zinnia, marigold and 

other flowering plants that are grown from bulbs;

 Flowering biennials “vegetative 1st season and flowers the 2nd season”; and

 Flowering perennials

 

9 Label rate= 0.0098 lb a.i/100 lbs of seeds; therefore the rate= (0.0098/100) lb a.i/1 lb of seeds and the rate per acre 

when a 200 lbs of seeds is used= 200 x 0.0098/100= 0.0196 lb a.i/A (the rate was stated in the label to be 0.02 lb 

a.i/A)

10 Note: Scenario Names consists of location, crop and purpose. Location= State name (e.g., STX= south Texas and 

TX= Texas); Crop= crop name (e.g., corn= corn); Purpose= either standard scenario= STD or scenarios used for 

special purpose “e.g., OP= for organophosphate cumulative assessment, NMC= for N-methyl carbamate 

assessment”
47

No seeding rate data are available for these plants, therefore only the label maxima rate of 0.02 

lbs/A were used in modeling.

a. Modeling inputs 

TM has only one formulated product label. The end-use product is formulated as flowable 

and is used directly to treat “true seeds= no seed parts or vegetative parts” for many crops. 

Therefore, the source of environmental exposure to TM is from planted seeds and will be 

directly related to crop scenario and amount of chemical applied (use rates/100 lbs of seed, 

crop seeding rates and seeding depths). Modeling inputs for case 1 are summarized in Table 

12 along with representative scenarios noting that the application dates were set to be the 

scenario planting dates.

Table 12. Modeling inputs for Case 1 and ornamentals (application rate used for all run= 0.02 lbs 

a.i/A)*

Crop Group Representative Crop (s) Scenario Minimum Seeding Depth 

(cm)

CG-1A

Carrot FLcarrotSTD 0.32

Parsley ORmintSTD 0.64

Turnip

FLpotatoeNMC 1.27

WApotatoeNMC 1.27

ME_potatoe 1.27

ID_potato 1.27

Sugarbeet (field, Garden, Seed)

CAsugarbeetOP 1.27

MNsugarbeetSTD 1.27

CG-3-07 onion, pearl

GAOnion_WirrigSTD 0.64

CAonion_WirrigSTD 0.64

WAonionNMC 0.64

CG-4 Lettuce & Corn Salad CAlettuceSTD 0.64

CG-5 Canola (rape) NDcanolaSTD 0.64

CG-6

Soybean (field/edamame) MSsoybeanSTD 1.91

Lupine

TXalfalfa OP 2.54

ILalfalfa NMC 2.54

NCalfalfa OP 2.54

PAalfalfa OP 2.54

CAalfalfa OP 2.54

MNalfalfa OP 2.54

Beans (snab, Garden, southern & peas)

MIbeansSTD 2.54

ORsnbeansSTD 2.54

WAbeansNMC 2.54

ILbeansNMC 2.54

CG-8-10

peppers FLpeppersSTD 0.64

Tomato FLtomatoSTD 0.64
48

Crop Group Representative Crop (s) Scenario Minimum Seeding Depth 

(cm)

PAtomatoSTD 0.64

CAtomato_WirrigSTD 0.64

CG-9

Melons (water, honeydew, musk & cantaloupe) TXmelonNMC 1.27

Cucumber FL cucumber 1.27

CG-15

wheat (durum/hard red/white), Barley

TXwheatOP 2.54

ORwheatOP 2.54

NDwheatSTD 2.54

corn (field/pop/sweet) & millet for seed

FLScorn OP 3.81

TX corn OP 3.81

OHCornSTD 3.81

CAcornOP 3.81

NCcornOP 3.81

ORscornOP 3.81

MScornSTD 3.81

NDcornOP 3.81

OHCornSTD 3.81

NCcornESTD 3.81

ILCornSTD 3.81

PAcornSTD 3.81

CG-17

Sorghum for forage

TXsorghumOP 1.91

KSsorghumSTD 1.91

Grass, Sudan grass & annual/perennial ryegrass ORgrassseedSTD 0.64

CG-18 

Lespedeza & sericea for forage CAlettuceSTD 0.64

Lupine for forage

TXalfalfa OP 2.54

ILalfalfa NMC 2.54

NCalfalfa OP 2.54

PAalfalfa OP 2.54

CAalfalfa OP 2.54

MNalfalfa OP 2.54

CG-19 cilantro ORmintSTD 0.64

CG-20 mustard greens FLcabbageSTD 0.64

Cotton cotton

TX cotton OP 1.27

TX cotton NMC 1.27

MScottonSTD 1.27

NCcottonSTD 1.27

CAcotton_WirrigSTD 1.27

Conifer Conifer ORXmasTreeSTD 2.54

Ornamental Flowering annuals, biennials, and perennials

TN, FL, NJ, OR & MI 

nurserySTD_V2.txt 0.64
49

Crop Group Representative Crop (s) Scenario Minimum Seeding Depth 

(cm)

All 

Vegetables Vegetables

TX vegetables NMC 0.64

PA vegetables NMC 0.64

* Note that this application rate is based on two label statements: 

(1) Do not apply more than a total of 0.02 lbs of Tolclofos-methyl active ingredient per acre per 

cropping cycle; and

(2) A restricted maximum seeding rate allowed of 40 lbs seeds/A for CG-1A, 50 lbs seeds/A for 

Cotton and 200 lbs seeds/A for all others

Modeling inputs for Case 2 are summarized in Table 13 along with representative scenarios 

noting that the application dates were set to be the scenario planting dates. In this case, 

representative scenarios are run using realistic application rates (based on the BEAD memo) 

calculated for crops being modeled.

Table 13. Modeling inputs for Case 2

Crop 

Group Representative Crop (s)1

Scenario Lbs 

Seeds/A Lb a.i/A

Minimum 

Seeding Depth 

(cm)

Burdock FLcarrotSTD 1.6 0.00078 0.32

Carrot FLcarrotSTD 12 0.00584 0.32

Parsley ORmintSTD 40 0.01955 0.64

radish

GAOnion_WirrigSTD 32.7 0.01596 0.64

CAonion_WirrigSTD 32.7 0.01596 0.64

WAonion NMC 32.7 0.01596 0.64

rutabaga

ME_potatoe 2 0.00098 1.27

ID_potato 2 0.00098 1.27

Sugarbeet (field, Garden, Seed)

MNsugarbeetSTD 25 0.01222 1.27

CAsugarbeet_WirrigOP 25 0.01222 1.27

CAsugerbeetOP 25 0.01222 1.27

Turnip

ME_potatoe 6 0.00293 1.27

ID_potato 6 0.00293 1.27

CG-3-

07

onion, pearl

GAOnion_WirrigSTD 110 0.01075 0.64

CAonion_WirrigSTD 110 0.01075 0.64

WAOnion NMC 110 0.01075 0.64

Onion (dry/green/seed)

GAOnion_WirrigSTD 13 0.00127 0.64

CAonion_WirrigSTD 13 0.00127 0.64

WAonion NMC 13 0.00127 0.64

CG-4

Coriander, leaf ORmintSTD 50 0.00489 0.64

Corn Salad CAlettuceSTD 37 0.00362 0.64

Lettuce (head/leaf) Celery CAlettuceSTD 0.8 0.00008 0.64

Spinach CAlettuceSTD 25 0.01222 1.27
50

Crop 

Group Representative Crop (s)1

Scenario Lbs 

Seeds/A Lb a.i/A

Minimum 

Seeding Depth 

(cm)

CG-5

Broccoli, Collard FLcabbageSTD 5 0.00049 0.64

Brussels sprouts FLcabbageSTD 0.4 0.00004 0.64

Cabbage Chinese (bok-choy) FLcabbageSTD 2.2 0.00021 0.64

Cauliflower FLcabbageSTD 0.3 0.00003 0.64

Kale FLcabbageSTD 5.8 0.00056 0.64

CG-6

Beans (snab) & Garden southern peas

ILbeansNMC 200 0.04257 2.54

MIbeansSTD 200 0.04257 2.54

ORsnbeansSTD 200 0.04257 2.54

WAbeansNMC 200 0.04257 2.54

Beans (dry & Lima)

ILbeansNMC 163.4 0.01596 2.54

MIbeansSTD 163.4 0.01596 2.54

ORsnbeansSTD 163.4 0.01596 2.54

WAbeansNMC 163.4 0.01596 2.54

Lupine

TXalfalfaOP 160 0.01564 2.54

ILalfalfaNMC 160 0.01564 2.54

NCalfalfaOP 160 0.01564 2.54

PAalfalfaOP 160 0.01564 2.54

CAalfalfa_WirrigOP 160 0.01564 2.54

MNalfalfaOP 160 0.01564 2.54

Soybean (field/edamame) MSsoybeanSTD 166.7 0.01629 1.91

CG-8-

10

Peppers FLpeppersSTD 4.2 0.00041 0.64

Tomato

STXvegetableNMC 1.1 0.00011 0.64

FLtomatoSTD 1.1 0.00011 0.64

PAvegetableNMC 1.1 0.00011 0.64

PAtomatoSTD 1.1 0.00011 0.64

CAtomato_WirrigSTD 1.1 0.00011 0.64

CG-9

Cucumber

FLcucumberSTD 11.6 0.00114 1.27

STXmelonNMC 11.6 0.00114 1.27

Melons (water, honeydew, musk, cantaloupe)

FLcucumberSTD 9.1 0.00089 1.27

STXmelonNMC 9.1 0.00089 1.27

Squash, summer & winter bush type

FLcucumberSTD 8 0.00078 1.27

STXmelonNMC 8 0.00078 1.27

Pumpkin, vine type, small

FLcucumberSTD 4.5 0.00044 1.27

STXmelonNMC 4.5 0.00044 1.27

CG-15

Barley, Buckwheat

TXwheatOP 96 0.00938 2.54

NDwheatSTD 96 0.00938 2.54

ORwheatOP 96 0.0088 2.54

Corn (field/pop/sweet) MScornSTD 33.2 0.00324 3.81
51

Crop 

Group Representative Crop (s)1

Scenario Lbs 

Seeds/A Lb a.i/A

Minimum 

Seeding Depth 

(cm)

FLsweetcornOP 33.2 0.00324 3.81

TXcornOP 33.2 0.00324 3.81

STXcornNMC 33.2 0.00324 3.81

CAcornOP 33.2 0.00324 3.81

NCcornESTD 33.2 0.00324 3.81

OHCornSTD 33.2 0.00324 3.81

ILCornSTD 33.2 0.00324 3.81

NCcornOP 33.2 0.00324 3.81

PAcornSTD 33.2 0.00324 3.81

ORswcornOP 33.2 0.00324 3.81

NDcornOP 33.2 0.00324 3.81

Millet, pearl

FLsweetcornOP 15 0.00147 3.81

MScornSTD 15 0.00147 3.81

TXcornOP 15 0.00147 3.81

STXcornNMC 15 0.00147 3.81

CAcornOP 15 0.00147 3.81

NCcornESTD 15 0.00147 3.81

OHCornSTD 15 0.00147 3.81

ILCornSTD 15 0.00147 3.81

NCcorn OP 15 0.00147 3.81

PAcornSTD 15 0.00147 3.81

ORswcornOP 15 0.00147 3.81

NDcornOP 15 0.00147 3.81

Oats & rye

TXwheatOP 90 0.0088 2.54

NDwheatSTD 90 0.0088 2.54

ORwheatOP 90 0.0088 2.54

Sorghum for grain

TXsorghumOP 9.1 0.00089 1.91

KSsorghumSTD 9.1 0.00089 1.91

Wheat (durum/hard red/white), Barley & Triticale

TXwheatOP 156 0.01525 2.54

NDwheatSTD 156 0.01525 2.54

ORwheatOP 156 0.01525 2.54

CG-17

Oats, triticale & rye for forage NDwheatSTD 109 0.01065 2.54

Grass, Sudan grass, annual ryegrass & perennial ryegrass ORgrassseedSTD 25 0.00244 0.64

Grass, Indian ORgrassseedSTD 12 0.00117 0.64

Grass, Kentucky & orchard grass & reed canary grass ORgrassseedSTD 10 0.00098 0.64

Grass, eastern gama & switch grass ORgrassseedSTD 9 0.00088 0.64

Grass, Bermuda ORgrassseedSTD 8 0.00078 0.64

Millet for forage FLsweetcornOP 30 0.00293 3.81
52

Crop 

Group Representative Crop (s)1

Scenario Lbs 

Seeds/A Lb a.i/A

Minimum 

Seeding Depth 

(cm)

MScornSTD 30 0.00293 3.81

TXcornOP 30 0.00293 3.81

STXcornNMC 30 0.00293 3.81

CAcornOP 30 0.00293 3.81

NCcornESTD 30 0.00293 3.81

OHCornSTD 30 0.00293 3.81

ILCornSTD 30 0.00293 3.81

NCcorn OP 30 0.00293 3.81

PAcornSTD 30 0.00293 3.81

ORswcornOP 30 0.00293 3.81

NDcornOP 30 0.00293 3.81

Oats, triticale & rye for forage

TXwheatOP 109 0.01065 2.54

ORwheatOP 109 0.01065 2.54

Sorghum for forage

TXsorghumOP 12 0.00117 1.91

KSsorghumSTD 12 0.00117 1.91

CG-18

Alfalfa

TXalfalfaOP 15 0.00147 0.64

ILalfalfaNMC 15 0.00147 0.64

NCalfalfaOP 15 0.00147 0.64

CAalfalfa_WirrigOP 15 0.00147 0.64

MNalfalfaOP 15 0.00147 0.64

Collards & Forage, kale for forage FLcabbageSTD 4 0.00039 0.64

Lespedeza

TXalfalfaOP 35 0.00342 0.64

NCalfalfaOP 35 0.00342 0.64

ILalfalfaNMC 35 0.00342 0.64

PAalfalfaOP 35 0.00362 0.64

CAalfalfa_WirrigOP 35 0.00342 0.64

MNalfalfaOP 35 0.00342 0.64

Lupine for forage

TXalfalfaOP 160 0.01564 2.54

ILalfalfaNMC 160 0.01564 2.54

NCalfalfaOP 160 0.01564 2.54

PAalfalfaOP 160 0.01564 2.54

CAalfalfa_WirrigOP 160 0.01564 2.54

MNalfalfaOP 160 0.01564 2.54

Vetch

TXalfalfaOP 9 0.00088 0.64

ILalfalfaNMC 9 0.00088 0.64

PAalfalfaOP 9 0.00147 0.64

NCalfalfaOP 9 0.00088 0.64

CAalfalfa_WirrigOP 9 0.00088 0.64
53

Crop 

Group Representative Crop (s)1

Scenario Lbs 

Seeds/A Lb a.i/A

Minimum 

Seeding Depth 

(cm)

MNalfalfaOP 9 0.00088 0.64

CG-19 

Borage ORmintSTD 15 0.00147 0.64

Burnet ORmintSTD 3.4 0.00033 0.64

Cilantro ORmintSTD 50 0.00489 0.64

Dill weed ORmintSTD 8 0.00078 0.64

CG-20

Canola (rape) NDcanolaSTD 8.2 0.0008 0.64

Mustard greens FLcabbageSTD 7 0.00068 0.64

Safflower

TXwheatOP 35 0.00342 2.54

ORwheatOP 35 0.00342 2.54

NDwheatSTD 35 0.00342 2.54

Sesame

TXcottonOP 12 0.00117 0.64

MSsoybeanSTD 12 0.00117 0.64

STXcottonNMC 12 0.00117 0.64

MScottonSTD 12 0.00117 0.64

NCcottonSTD 12 0.00117 0.64

CAcotton_WirrigSTD 12 0.00117 0.64

Sunflower

MScornSTD 4 0.00039 2.54

FLsweetcornOP 4 0.00039 2.54

TXcornOP 4 0.00039 2.54

STXcornNMC 4 0.00039 2.54

CAcornOP 4 0.00039 2.54

NCcornESTD 4 0.00039 2.54

OHCornSTD 4 0.00039 2.54

ILCornSTD 4 0.00039 2.54

NCcornOP 4 0.00039 2.54

PAcornSTD 4 0.00039 2.54

ORswcornOP 4 0.00039 2.54

NDcornOP 4 0.00039 2.54

Conifer Conifer ORXmasTreeSTD 5 0.00049 2.54

Cotton Cotton

TXcottonOP 18.9 0.00923 1.27

STXcottonNMC 18.9 0.00923 1.27

MScottonSTD 18.9 0.00923 1.27

NCcottonSTD 18.9 0.00923 1.27

CAcotton_WirrigSTD 18.9 0.00923 1.27

1

Based on the highest seeding rate for listed crops in this column.

Environmental fate and transport based on total residues of concern (parent plus bound residues) 

and other data used as parameters for PRZM/EXAMS runs are listed in Table 14. 
54

Table 14. Summary of PRZM/EXAMS environmental fate and transport data used as aquatic 

exposure inputs (TTR=total toxic residues).

Input Parameter (Unit) Value Reference

Molecular Weight g/mole 301.12 Registrant data

Vapor pressure 1.38 x 10-5

torr @ 24.8 °C 417018-01

Henry’s law constant 3.68 x 10-6

atm m3 mole-1

Calculated from value at

20 °C (483419-01)**

Solubility in Water (mg/L) 1.1 FAO1 & 483419-14 and

Photolysis in Water (t1⁄2 in days @ pH 7) Considered Stable 414229-02

Aerobic Soil Metabolism (90th % t1⁄2 in days 

for 10 soils) 171

427032-01; 001561-06; 

483419-23 supplemented by 

483419-25; and 483419-24

Hydrolysis (t1⁄2 in days @ pH 7) 61 days 417147-01

Aerobic Aquatic Metabolism Considered Stable Hydrolysis is significant

Anaerobic Aquatic Metabolism Considered Stable Hydrolysis is significant

Koc (Average of five values in L/Kg) 3,279 Average value

Application rate and frequency

Application intervals Once/season at time of planting

Chemical Application Method (CAM) 5 (depth varies with crop)

Application Efficiency/ Spray Drift Fraction 100%/0% (seed treatment)

b. Aquatic EECs 

Aquatic exposure surface water EECs for the various crop use patterns are summarized in Table 

15 for Case 1 and in Table 16 for Case 2. Example output from the PRZM/EXAMS modeling is 

provided in Appendix H.

Table 15. Surface water 1-in-10 Year EECs (μg/L) for TM1use patterns (Case 1)

Crop Group Scenario Peak (ppb) 21-day (ppb) 60-day (ppb)

CG-1A

FLcarrotSTD 0.344 0.194 0.116

ORmintSTD 0.028 0.016 0.012

FLpotatoNMC 0.090 0.054 0.040

WApotatoNMC 0.025 0.013 0.008

ME_potato 0.036 0.024 0.018

ID_potato 0.020 0.018 0.016

CAsugarbeetOP 0.018 0.010 0.007

MNsugarbeetSTD 0.028 0.016 0.011

CG-3-07

GAOnion_WirrigSTD 0.185 0.116 0.075

CAonion_WirrigSTD 0.027 0.016 0.011

WAonionNMC 0.008 0.004 0.002

CG-4 CAlettuceSTD 0.171 0.098 0.062
55

Crop Group Scenario Peak (ppb) 21-day (ppb) 60-day (ppb)

ORmintSTD 0.028 0.016 0.012

CG-5 NDcanolaSTD 0.053 0.031 0.020

CG-6

MSsoybeanSTD 0.131 0.070 0.057

TXalfalfa OP 0.064 0.037 0.026

ILalfalfa NMC 0.038 0.022 0.016

NCalfalfa OP 0.033 0.021 0.014

PAalfalfa OP 0.029 0.018 0.012

CAalfalfa OP 0.015 0.009 0.007

MNalfalfa OP 0.010 0.005 0.003

MIbeansSTD 0.023 0.015 0.010

ORsnbeansSTD 0.022 0.014 0.011

WAbeansNMC 0.018 0.010 0.005

ILbeansNMC 0.042 0.028 0.021

CG-8-10

FLpeppersSTD 0.340 0.209 0.147

FLtomatoSTD 0.208 0.114 0.087

PAtomatoSTD 0.105 0.060 0.042

CAtomato_WirrigSTD 0.047 0.029 0.019

CG-9

TXmelonNMC 0.154 0.084 0.057

FL cucumber 0.275 0.161 0.092

CG-15

TXwheatOP 0.082 0.056 0.034

ORwheatOP 0.010 0.006 0.005

NDwheatSTD 0.013 0.007 0.005

FLScorn OP 0.050 0.030 0.017

TX corn OP 0.045 0.025 0.017

OHCornSTD 0.017 0.010 0.006

CAcornOP 0.023 0.014 0.009

NCcornOP 0.012 0.008 0.005

ORscornOP 0.008 0.005 0.004

MScornSTD 0.050 0.032 0.022

NDcornOP 0.005 0.003 0.002

NCcornESTD 0.018 0.012 0.008

ILCornSTD 0.013 0.008 0.005

PAcornSTD 0.010 0.006 0.004

CG-17

TXsorghumOP 0.196 0.101 0.061

KSsorghumSTD 0.070 0.043 0.030

ORgrassseedSTD 0.042 0.024 0.017

CG-18 

CAlettuceSTD 0.171 0.098 0.062

TXalfalfa OP 0.064 0.037 0.026

ILalfalfa NMC 0.038 0.022 0.016
56

Crop Group Scenario Peak (ppb) 21-day (ppb) 60-day (ppb)

NCalfalfa OP 0.033 0.021 0.014

PAalfalfa OP 0.029 0.018 0.012

CAalfalfa OP 0.015 0.009 0.007

MNalfalfa OP 0.010 0.005 0.003

CG-19 ORmintSTD 0.028 0.016 0.012

CG-20 FLcabbageSTD 0.123 0.073 0.043

Cotton

TX cotton OP 0.211 0.119 0.079

TX cotton NMC 0.193 0.104 0.068

MScottonSTD 0.143 0.089 0.073

NCcottonSTD 0.091 0.059 0.042

CAcotton_WirrigSTD 0.027 0.014 0.012

Conifer ORXmasTreeSTD 0.016 0.009 0.005

Flowering 

Ornamental

TNnurserySTD_V2.txt 0.219 0.128 0.089

FLnurserySTD_V2.txt 0.146 0.088 0.072

NJnurserySTD_V2.txt 0.142 0.080 0.054

ORnurserySTD_V2.txt 0.063 0.039 0.025

MInurserySTD_V2.txt 0.046 0.034 0.026

All Vegetables

TX vegetables NMC 0.284 0.149 0.096

PA vegetables NMC 0.166 0.110 0.070

1 EECs reflect TM + bound residues

Table 16. Surface water 1-in-10 Year EECs (μg/L) for TM1use patterns (Case 2)

Crop 

Group Representative Crop(s)2

Scenario

Peak 

(ppb)

21-day 

(ppb) 60-day (ppb)

CG-1A

Burdock FLcarrotSTD 0.014 0.008 0.005

Carrot FLcarrotSTD 0.100 0.056 0.034

Parsley ORmintSTD 0.027 0.016 0.012

radish

GAOnion_WirrigSTD 0.148 0.093 0.060

CAonion_WirrigSTD 0.022 0.013 0.009

WAonion NMC 0.006 0.003 0.002

rutabaga

ME_potatoe 0.002 0.001 0.001

ID_potato 0.001 0.001 0.001

Sugarbeet (field, Garden, Seed)

MNsugarbeetSTD 0.017 0.010 0.007

CAsugarbeet_WirrigOP 0.011 0.006 0.004

CAsugerbeetOP 0.011 0.006 0.004

Turnip

ME_potatoe 0.005 0.003 0.003

ID_potato 0.003 0.003 0.002

CG-3-

07 onion, pearl

GAOnion_WirrigSTD 0.099 0.062 0.040

CAonion_WirrigSTD 0.015 0.009 0.006
57

Crop 

Group Representative Crop(s)2

Scenario

Peak 

(ppb)

21-day 

(ppb) 60-day (ppb)

WAOnion NMC 0.004 0.002 0.001

Onion (dry/green/seed)

GAOnion_WirrigSTD 0.012 0.007 0.005

CAonion_WirrigSTD 0.002 0.001 0.001

WAonion NMC 0.000 0.000 0.000

CG-4

Coriander, leaf ORmintSTD 0.007 0.004 0.003

Corn Salad CAlettuceSTD 0.046 0.026 0.016

Lettuce (head/leaf); and Celery CAlettuceSTD 0.001 0.001 0.000

Spinach CAlettuceSTD 0.105 0.060 0.038

CG-5

Broccoli, Collard FLcabbageSTD 0.003 0.002 0.001

Brussels sprouts FLcabbageSTD 0.000 0.000 0.000

Cabbage Chinese (bok- choy) FLcabbageSTD 0.001 0.001 0.000

Cauliflower FLcabbageSTD 0.000 0.000 0.000

Kale FLcabbageSTD 0.003 0.002 0.001

CG-6

Beans (snab) & Garden; southern peas

ILbeansNMC 0.042 0.028 0.021

MIbeansSTD 0.023 0.015 0.010

ORsnbeansSTD 0.022 0.014 0.011

WAbeansNMC 0.018 0.010 0.005

Beans (dry & Lima)

ILbeansNMC 0.034 0.023 0.017

MIbeansSTD 0.018 0.012 0.008

ORsnbeansSTD 0.017 0.011 0.009

WAbeansNMC 0.014 0.008 0.004

Lupine

TXalfalfaOP 0.050 0.029 0.020

ILalfalfaNMC 0.029 0.017 0.012

NCalfalfaOP 0.026 0.016 0.011

PAalfalfaOP 0.023 0.014 0.010

CAalfalfa_WirrigOP 0.012 0.007 0.005

MNalfalfaOP 0.008 0.004 0.002

Soybean (field/edamame) MSsoybeanSTD 0.107 0.057 0.047

CG-8-

10

Peppers FLpeppersSTD 0.008 0.005 0.003

Tomato

STXvegetableNMC 0.001 0.001 0.000

FLtomatoSTD 0.001 0.001 0.000

PAvegetableNMC 0.001 0.000 0.000

PAtomatoSTD 0.000 0.000 0.000

CAtomato_WirrigSTD 0.000 0.000 0.000

CG-9

Cucumber

FLcucumberSTD 0.016 0.009 0.005

STXmelonNMC 0.009 0.005 0.003

Melons (water, honeydew, musk, cantaloupe)

FLcucumberSTD 0.012 0.007 0.004

STXmelonNMC 0.007 0.004 0.003

Squash, summer & winter bush type FLcucumberSTD 0.011 0.006 0.004
58

Crop 

Group Representative Crop(s)2

Scenario

Peak 

(ppb)

21-day 

(ppb) 60-day (ppb)

STXmelonNMC 0.006 0.003 0.002

Pumpkin, vine type, small

FLcucumberSTD 0.006 0.004 0.002

STXmelonNMC 0.003 0.002 0.001

CG-15

Barley, Buckwheat

TXwheatOP 0.039 0.026 0.016

NDwheatSTD 0.006 0.003 0.002

ORwheatOP 0.005 0.003 0.002

Corn (field/pop/sweet)

MScornSTD 0.008 0.005 0.003

FLsweetcornOP 0.008 0.005 0.003

TXcornOP 0.007 0.004 0.003

STXcornNMC 0.005 0.003 0.002

CAcornOP 0.004 0.002 0.001

NCcornESTD 0.003 0.002 0.001

OHCornSTD 0.003 0.002 0.001

ILCornSTD 0.002 0.001 0.001

NCcornOP 0.002 0.001 0.001

PAcornSTD 0.002 0.001 0.001

ORswcornOP 0.001 0.001 0.001

NDcornOP 0.001 0.000 0.000

Millet, pearl

FLsweetcornOP 0.004 0.002 0.001

MScornSTD 0.004 0.002 0.002

TXcornOP 0.003 0.002 0.001

STXcornNMC 0.002 0.001 0.001

CAcornOP 0.002 0.001 0.001

NCcornESTD 0.001 0.001 0.001

OHCornSTD 0.001 0.001 0.000

ILCornSTD 0.001 0.001 0.000

NCcorn OP 0.001 0.001 0.000

PAcornSTD 0.001 0.000 0.000

ORswcornOP 0.001 0.000 0.000

NDcornOP 0.000 0.000 0.000

Oats & rye

TXwheatOP 0.036 0.025 0.015

NDwheatSTD 0.006 0.003 0.002

ORwheatOP 0.004 0.003 0.002

Sorghum for grain

TXsorghumOP 0.011 0.006 0.004

KSsorghumSTD 0.003 0.002 0.001

Wheat (durum/hard red/white), Barley & Triticale

TXwheatOP 0.063 0.043 0.026

NDwheatSTD 0.010 0.005 0.004

ORwheatOP 0.008 0.005 0.004

CG-17 Oats, triticale & rye for forage NDwheatSTD 0.007 0.004 0.003
59

Crop 

Group Representative Crop(s)2

Scenario

Peak 

(ppb)

21-day 

(ppb) 60-day (ppb)

Grass, Sudan grass, annual ryegrass & perennial ryegrass ORgrassseedSTD 0.005 0.003 0.002

Grass, Indian ORgrassseedSTD 0.002 0.001 0.001

Grass, Kentucky & orchard grass & reed canary grass ORgrassseedSTD 0.002 0.001 0.001

Grass, eastern gama & switch grass ORgrassseedSTD 0.002 0.001 0.001

Grass, Bermuda ORgrassseedSTD 0.002 0.001 0.001

Millet for forage

FLsweetcornOP 0.008 0.005 0.003

MScornSTD 0.007 0.005 0.003

TXcornOP 0.007 0.004 0.003

STXcornNMC 0.004 0.003 0.002

CAcornOP 0.004 0.002 0.001

NCcornESTD 0.003 0.002 0.001

OHCornSTD 0.002 0.001 0.001

ILCornSTD 0.002 0.001 0.001

NCcorn OP 0.002 0.001 0.001

PAcornSTD 0.001 0.001 0.001

ORswcornOP 0.001 0.001 0.001

NDcornOP 0.001 0.000 0.000

Oats, triticale & rye for forage

TXwheatOP 0.063 0.043 0.026

ORwheatOP 0.008 0.005 0.004

Sorghum for forage

TXsorghumOP 0.011 0.006 0.004

KSsorghumSTD 0.004 0.003 0.002

CG-18

Alfalfa

TXalfalfaOP 0.017 0.010 0.007

ILalfalfaNMC 0.010 0.006 0.004

NCalfalfaOP 0.008 0.005 0.003

CAalfalfa_WirrigOP 0.004 0.003 0.002

MNalfalfaOP 0.003 0.001 0.001

Collards & Forage, kale for forage FLcabbageSTD 0.002 0.001 0.001

Lespedeza

TXalfalfaOP 0.050 0.029 0.020

NCalfalfaOP 0.026 0.016 0.011

ILalfalfaNMC 0.024 0.014 0.010

PAalfalfaOP 0.023 0.014 0.010

CAalfalfa_WirrigOP 0.012 0.007 0.005

MNalfalfaOP 0.008 0.004 0.002

Lupine for forage

TXalfalfaOP 0.050 0.029 0.020

ILalfalfaNMC 0.029 0.017 0.012

NCalfalfaOP 0.026 0.016 0.011

PAalfalfaOP 0.023 0.014 0.010

CAalfalfa_WirrigOP 0.012 0.007 0.005

MNalfalfaOP 0.008 0.004 0.002
60

Crop 

Group Representative Crop(s)2

Scenario

Peak 

(ppb)

21-day 

(ppb) 60-day (ppb)

Vetch

TXalfalfaOP 0.010 0.006 0.004

ILalfalfaNMC 0.006 0.004 0.003

PAalfalfaOP 0.005 0.003 0.002

NCalfalfaOP 0.005 0.003 0.002

CAalfalfa_WirrigOP 0.003 0.002 0.001

MNalfalfaOP 0.002 0.001 0.000

CG-19 

Borage ORmintSTD 0.002 0.001 0.001

Burnet ORmintSTD 0.001 0.000 0.000

Cilantro ORmintSTD 0.007 0.004 0.003

Dill weed ORmintSTD 0.001 0.001 0.000

CG-20

Canola (rape) NDcanolaSTD 0.002 0.001 0.001

Mustard greens FLcabbageSTD 0.004 0.003 0.002

Safflower

TXwheatOP 0.014 0.009 0.006

ORwheatOP 0.002 0.001 0.001

NDwheatSTD 0.000 0.000 0.000

Sesame

TXcottonOP 0.097 0.055 0.036

MSsoybeanSTD 0.018 0.010 0.008

STXcottonNMC 0.017 0.009 0.006

MScottonSTD 0.013 0.008 0.007

NCcottonSTD 0.010 0.006 0.005

CAcotton_WirrigSTD 0.002 0.001 0.001

Sunflower

MScornSTD 0.002 0.001 0.001

FLsweetcornOP 0.002 0.001 0.001

TXcornOP 0.002 0.001 0.001

STXcornNMC 0.001 0.001 0.000

CAcornOP 0.001 0.001 0.000

NCcornESTD 0.001 0.000 0.000

OHCornSTD 0.001 0.000 0.000

ILCornSTD 0.001 0.000 0.000

NCcornOP 0.000 0.000 0.000

PAcornSTD 0.000 0.000 0.000

ORswcornOP 0.000 0.000 0.000

NDcornOP 0.000 0.000 0.000

Conifer Conifer ORXmasTreeSTD 0.000 0.000 0.000

Cotton Cotton

TXcottonOP 0.097 0.055 0.036

STXcottonNMC 0.089 0.048 0.031

MScottonSTD 0.065 0.041 0.034

NCcottonSTD 0.042 0.027 0.019

CAcotton_WirrigSTD 0.013 0.007 0.005
61

1 ECs reflect TM + bound residues; 2 Based on the highest seeding rate for listed crops in this column.

A summary of all surface water exposure EEC results (Case 1, Case 2 and Ornamentals) are 

included in Figure 8 (shows only the range of EECs obtained for scenarios representing the crop 

or crop group.
62

Figure 8. Surface water exposure EECs (Case 1, Case 2 and Ornamentals)

With an average Koc of over 3,000 and a log Kow of 3.8, TM is expected to partition onto 

sediment particles to a relatively significant extent. Therefore, exposure to pore water in aquatic 

systems was also obtained for selected runs including scenarios with the highest and lowest 

surface water EECs. In this case, pore-water EECs for the most conservative runs (Case 1 runs) 

are summarized in

Table 17.

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

Exposure EECs (ppb)

0

0.05

0.1

0.15

0.2

0.25

Exposure EECs (ppb)

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

Exposure EECs (ppb)

Crop Group

1= Case-1 (modled using maximum rate); 2= Case-2 (modeled using expected rate for each crop calculated from 

seeding rates). Range is mostly taken from modeling results for more than one representatative scenarios.

1

2

1 1

1

1

1

1

1

1

1

1 1

1

1 1

2

2

2

2

2

2 2 2 2

2

2 2

2

Crop or Crop Group

Peak (Acute) EECs

60-day (Chronic) EECs

21-day (Chronic) EECs
63

Table 17. Pore-water 1-in-10 Year EECs (μg/L) for TM1use patterns (Case 1)

Crop Group Representative Crop (s) Scenario Peak (ppb) 21-day 

(ppb)

60-day 

(ppb)

Scenarios with the Highest Surface Water EECs

All 

Vegetables Vegetables

TX vegetables NMC 0.0630 0.0612 0.0587

PA vegetables NMC 0.0580 0.0578 0.0570

Cotton Cotton

TX cotton OP 0.0527 0.0524 0.0512

TX cotton NMC 0.0446 0.0443 0.0428

CG-17 Sorghum for forage TXsorghumOP 0.0408 0.0406 0.0392

CG-3-07 Onion, pearl GAOnion_WirrigSTD 0.0400 0.0393 0.0372

CG-9

Melons (water, honeydew, 

musk & cantaloupe) TXmelonNMC 0.0367 0.0365 0.0353

CG-1A Carrot FLcarrotSTD 0.0332 0.0330 0.0316

CG-6 Soybean (field/edamame) MSsoybeanSTD 0.0320 0.0318 0.0306

CG-4 Lettuce & Corn Salad CAlettuceSTD 0.0240 0.0239 0.0233

Scenarios with the Lowest Surface Water EECs

CG-15

Corn (field/pop/sweet) & 

millet for seed

ILCornSTD 0.0007 0.0007 0.0006

PAcornSTD 0.0005 0.0005 0.0005

CG-8-10 Tomatoes

FLtomatoSTD 0.0003 0.0003 0.0003

PAtomatoSTD 0.0002 0.0002 0.0002

CAtomato_WirrigSTD 0.0000 0.0000 0.0000

1 EECs reflect TM + bound residues

Furthermore, bulk sediment EECs were also obtained for the highest surface water EEC scenario 

“FLcarrotSTD”. Modeled EECs were: peak= 16.87μg/kg, 21-day= 16.75 μg/kg, 60-day= 

16.10μg/kg.

c. Aquatic Exposure Monitoring (Field Data) 

This is a new pesticide and therefore no data were identified to provide information on aquatic 

monitoring.

3. Terrestrial Exposure Assessment 

a. Consumption of Treated Seeds

The T-REX model (v. 1.5, March 2012) is used in this assessment for estimating direct exposure 

of birds and mammals to TM via consumption of treated seeds. Exposure from the consumption 

of treated seed is calculated two ways: 
64

Exposure Method #1 is based on the TM concentration in seed (mg ai/kg seed) for 

comparing with acute and chronic dose and diet-based toxicity endpoints, and 

Exposure Method #2 is based on the mg ai/A for estimating LD50/ft2. 

For exposure method #1, the concentration in treated seed is usually determined from the 

application rate (fl oz of product/100lb seed), % ai, and the density of product. However, the 

label for TM specifies the maximum allowable application rate in terms of lb ai/100 kg seed (see 

Table 3). Across all crop groupings, only two different maximum application rates are allowed 

on the label:

 Cotton & root vegetables (CG1A): 0.048867 lb ai/100 lb seed (= 487.79 mg ai/kg seed)

 All other crops: 0.009773 lb ai/100 lb seed (= 97.73 mg ai/kg seed).

Therefore, these two application rates were used as the basis of subsequent avian and 

mammalian exposure calculations using exposure method #1 above. Specifically, dose-based 

EECs (mg/kg-bw) for various size classes of mammals and birds were calculated based on 

allometric relationships between food intake and body weight to reflect exposure of different 

weight class of animals. The size classes assessed are:

Birds:

 small (20g) 

 medium (100g)

 large (1000g) 

Mammals:

 small (15g) 

 medium (35g)

 large (1000g).

Equations for the dose-based EEC calculations are described in the T-REX v 1.5 Users Guide.11 

Estimated doses (mg ai/kg-bw-d) to the different size classes of birds and mammals are provided 

in Table 18. 

Table 18. Estimated Exposure of TM to Birds and Mammals Based on Label Seed Application 

Rates

Animal 

Size

Crop

Maximum Seed 

Application Rate

(mg ai/kg seed)

Avian Nagy Dose

(mg ai/kg-bw/day)

Mammalian Nagy 

Dose

(mg ai/kg-bw/day)

Small Root Vegetables (CG1A) 

& 488

124 103

Medium 70.4 71.4

 

11 details of this model are available at http://www.epa.gov/oppefed1/models/terrestrial/index.htm#trex
65

Large Cotton 31.5 16.6

Small All Other Crops*

97.7

24.7 20.7

Medium 14.1 14.3

Large 6.30 3.31

*See Table 3 for description of crop groups.

Diet-based EECs are also determined assuming 100% of the diet is treated seed (100% 

available). Thus, the diet-based EECs are equivalent to the maximum seed application rates 

shown in Table 18.

Terrestrial EECs calculated using exposure method #2 are based on the maximum allowable rate 

on the label: 0.02 lb ai/A. This value is equivalent to 0.21 mg ai/ft2. It is then compared to the 

appropriate body-weight adjusted LD50 for determining the fraction of LD50 per square foot.

Both exposure method 1 and 2 above involve a number of assumptions including: (1) seeds are 

readily available for consumption by wildlife; (2) 100% of the diet is treated seed; (3) no 

degradation of pesticide occurs over time; and (4) food consumption rates are scalable according 

to allometric relationships. Uncertainty associated with these and other assumptions is described 

in Section IV.C. 

b. Consumption of Aquatic Biota

In addition to consumption of treated seeds, the risk to birds and mammals that consume aquatic 

biota contaminated with TM was also evalutated, since TM is hydrophobic and may

bioaccumulate in aquatic food webs. Bioaccumulation in aquatic biota was estimated using the 

reported BCF values (Table 8) and the KABAM model. Details and result of this evaluation are 

presented in Section IV.A.4.

c. Terrestrial Exposure Monitoring (Field Data) 

TM is a new chemical proposed for registration in the US; therefore, no data are available on 

terrestrial monitoring. 

4. Non-Target Terrestrial Plant Exposure Assessment 

An exposure assessment for terrestrial plants was not conducted for several reasons. First, the 

proposed use of TM is for seed treatment. Thus, the usual spray drift exposure analysis is not 

applicable to TM. Second, the label specifies that seeds are to be planted below the soil surface, 

which would tend to minimize runoff of TM to adjacent areas. Third, while drift of abraded seed 

coating containing TM residues is a plausible exposure vector to terrestrial plants (and animals), 

methods to quantify this exposure route are currently lacking. Lastly, toxicity data on the effects 

of TM on terrestrial plants are not available. The uncertainty associated with not assessing risks 

to terrestrial plants is further described in Section IV.C based on terrestrial plant toxicity data 

from surrogate chemicals (other OP pesticides). 
66

C. Ecological Effects Characterization 

The effects of TM on aquatic and terrestrial organisms as derived from laboratory studies are 

summarized in this section. It is important to recognize that the tested species reported herein 

represent a small fraction of avian, mammalian, aquatic organisms and plant species resident to 

North America. Specifically, only a few surrogate species for both freshwater fish and birds are 

used to represent all freshwater fish (2000+) and bird (680+) species in the United States. For 

mammals, acute studies are usually limited to Norway rat or the house mouse. Estuarine/marine 

testing is usually limited to a crustacean, a mollusk, and a fish. Also, neither reptiles nor 

amphibians are commonly tested. In the absence of toxicity data for reptiles and terrestrial phase 

amphibians, this risk assessment uses the sensitivity of birds as a surrogate for terrestrial-phase 

amphibians and reptiles. Similarly, freshwater fish are used as a surrogate for aquatic-phase 

amphibians. 

In general, categories of acute toxicity ranging from “practically nontoxic” to “very highly toxic” 

have been established for aquatic organisms (based on LC50 and EC50 values or limit of 

solubility), mammals (based on acute oral LD50 values), avian species (based on and acute oral 

LD50 and subacute dietary LC50 values), and non-target insects (based on acute contact LD50

values for honeybees) (U.S. EPA 2001). These categories are presented in Appendix E.

1. Aquatic Effects 

The acute and chronic toxicity values associated with freshwater and estuarine/marine species 

exposure to TM are summarized in Error! Reference source not found.Table 19. Toxicity endpoints 

shown in bold represent the most sensitive endpoints within a taxonomic grouping (e.g., 

freshwater fish, freshwater invertebrates, aquatic plants, etc.). These endpoints are termed the 

“toxicity reference values” which are used for quantitative risk assessment in Section IV. An 

overview of the toxicity test results for aquatic organisms is provided in this section with a more 

detailed summary of each study provided in Appendix D. 

An important consideration for interpreting results of aquatic toxicity studies with TM is its 

relatively low solubility in water (0.7 -1.0 mg/L). A number of aquatic studies are known or 

suspected to have problems with the formation of precipitates. In these situations, the actual 

amount of TM that is dissolved in solution is uncertain unless samples are centrifuged and/or 

filtered prior to analysis. Therefore, when available, results are based on centrifuged samples in 

order to determine the most bioavailable portion of the test material that is comparable to the 

aquatic EECs. Toxicity studies of the major degradate, DM-TM are available for freshwater fish, 

freshwater invertebrates, and aquatic algae. There are no submitted studies on the formulated 

product. However, the proposed use pattern of TM (seed treatment) would not invoke concerns 

associated with exposure to most end use products (e.g., spray drift). 
67

Table 19. Toxicity Reference Values For Aquatic Organisms Exposed To Tolclofos Methyl and Metabolite 

(DM-TM)

Exposure 

Scenario % A.I. Species Dur.

Toxicity Reference 

Value** 

(95% CL)

Effect Notes

MRID;

Classification (Year)

Freshwater Fish

Acute

TGAI

97.8%

Rainbow Trout

Oncorhynchus 

mykiss

96 h LC50 = 0.69 mg a.i./L 

(0.64-0.74)

Probit Slope = 16 (8.2-

24)

NOAEC = 0.35 mg ai/L

 No mortality or clinical signs of 

toxicity were observed at or below 

0.35 mg ai/L.

 At 0.61 and 0.8 mg ai/L, mortality 

was 30 and 85% respectively and 

sublethal effects included loss of 

equilibrium and lethargy. 

 Results are based on centrifuged 

samples as precipitate was observed 

in the two highest treatments (0.61 

and 0.8 mg ai/L) 

48341930

Acceptable

Sousa et al 

(2003)

TGAI

99.8%

Rainbow Trout

Oncorhynchus 

mykiss

96 h LC50 = 0.87 mg ai/L

(0.31-1.3)

Probit slope = 4.2 (2.4-

6.0)

NOAEC = 0.05 mg ai/L

 No mortality was observed below 

0.56 mg ai/L. 

 Above 0.05 mg ai/L, sublethal 

effects included abnormal 

respiration, lethargy, loss of 

equilibrium, darken color

00156117

Supplemental

Miyamoto et al 

(1982)

DM-TM 

(98.9%)

Rainbow Trout

Oncorhynchus 

mykiss

96 h LC50 > 110 mg/L

NOAEC = 110 mg/L

 No lethal or sublethal effects 

observed in test concentrations <110 

mg/L DM-TM (a metabolite of 

tolclofos methyl) 

47837502

Acceptable

Dionne (1998)

TGAI

99.8%

Carp (Cyprinus 

carpio)

96 h LC50 = 2.1 mg ai/L (1.5-

2.7)

Probit slope = 7.7 (3.3-

12.2)

NOAEC = 0.1 mg ai/L

 No mortality was observed at or 

below 1.0 mg ai/L. 

 Clinical signs of toxicity were 

observed > 0.18 mg ai/L and 

included loss of equilibrium, 

abnormal respiration lethargy, 

darkened color. 

00156118

Supplemental 

(Takimoto et al 

(1981)

TGAI

99.8%

Japanese 

medaka 

(Oryzias 

latipes)

96 h LC50 = 3.0 mg ai/L (2.2-

4.6)

Probit slope = 4.2 (2.4-

5.9)

NOAEC = 0.18 mg ai/L

 No mortality was observed at or 

below 0.56 mg ai/L.

 Clinical signs of toxicity were 

observed > 0.32 mg ai/L and 

included loss of equilibrium, 

abnormal respiration lethargy, 

darkened color. 

00156118

Supplemental

Takimoto et al 

(1981)

TGAI

99.8%

Guppy 

(Poecilia 

reticulata)

96 h LC50 = 3.2 mg ai/L

(2.4-3.9)

Probit slope = 5.7 (3.2-

8.3)

NOAEC = 1.0 mg a.i./L

 No mortality was observed at 1.0 mg 

ai/L (lowest treatment).

 Occurrence of sublethal effects in 

specific treatments was not reported. 

NOAEC based on reported mortality.

 90%-100% mortality > 5.6 mg ai/L.

00156119 

Supplemental

Takimoto et al 

(1981)
68

Table 19. Toxicity Reference Values For Aquatic Organisms Exposed To Tolclofos Methyl and Metabolite 

(DM-TM)

Exposure 

Scenario % A.I. Species Dur.

Toxicity Reference 

Value** 

(95% CL)

Effect Notes

MRID;

Classification (Year)

TGAI

97.2%

Bluegill 

(Lepomis 

macrochirus)

96 h LC50 > 0.72 mg ai/L

NOAEC = 0.72 mg ai/L

 No lethal or sublethal effects were 

observed up to and including the 

highest test concentration (0.72 mg 

ai/L). 

 At highest treatment, the 

bioavailability of TM is uncertain, as 

a precipitate formed each day and 

samples apparently were not 

centrifuge prior to analysis

41400301 

Supplemental

McAllister 

(1989)

Chronic

TGAI

97.6%

Rainbow Trout

(Oncorhynchus 

mykiss)

97 d NOAEC = <0.012 mg 

a.i./L

LOAEC = 0.012 mg 

a.i./L

 The most sensitive endpoints were 

fry weight (60d post hatch) and 

length (37d post hatch) which were 

significantly reduced relative to 

negative controls (14% and 4% 

respectively) at 12 ug ai/L. 

 Fry survival was significantly 

reduced at 110 and 200 ug ai/L

 Egg hatching was significantly 

reduced only at the highest 

concentration (200 ug ai/L)

42106501

Supplemental

Cohle and Leak 

(1991)

Freshwater Invertebrates

Acute

TGAI

98.8%

Water flea

Daphnia magna

48 h EC50 48 mg ai/L (42.8-

53.7)

Probit Slope: 10.4 (5.9-

14.9)

NOAEC= 17 mg a.i./L

 No mortality at 48-hr < 26 mg ai/L

 90% immobility at 64 mg ai/L 

 Precipitates observed at 

concentrations > 17 mg ai/L; 

 Although co-solvent was used, there 

was no indication of filtering or 

centrifugation prior to analysis.

43528001

Supplemental

Murrell et al 

(1994)

DM-TM 

(98.9%)

Water flea

Daphnia magna

48 h EC50 > 95 mg/L

NOAEC = 95 mg/L

 No lethal or sublethal effects 

observed in test concentrations <95 

mg/L DM-TM (a metabolite of 

tolclofos methyl)

47837501

Acceptable

Dionne (1998)

TGAI

99.8%

Water flea

Daphnia pulex

24 h EC50 = 2.4 mg ai/L

(2.1-2.8)

Probit Slope: 7.3 (4.4-

10.1)

NOAEC= 1.0 mg ai/L

 No mortality was reported at any test 

concentration (1-10 mg ai/L 

nominal)

 >20% immobilization occurred at 

1.8 mg ai/L (nominal) and above

00156120

Supplemental

Takimoto and 

Kagoshima 

(1982)

Chronic TGAI

97.6%

Water flea

Daphnia magna

21 d NOAEC = 0.026 mg 

ai/L

LOAEC = 0.062 mg 

ai/L.

 Reproduction and growth of 

daphnids were significantly reduced 

at > 0.062 ug ai/L

 Daphnid survival was significantly 

reduced at > 0.19 ug ai/L

 No effects were observed on time to 

first brood at any treatment. 

41400303

Supplemental

Burgess (1989)

Estuarine/Marine Fish
69

Table 19. Toxicity Reference Values For Aquatic Organisms Exposed To Tolclofos Methyl and Metabolite 

(DM-TM)

Exposure 

Scenario % A.I. Species Dur.

Toxicity Reference 

Value** 

(95% CL)

Effect Notes

MRID;

Classification (Year)

Acute

TGAI

95.6%

Sheepshead 

minnow

Cyprinodon 

variegatus

96 h LC50 >0.372 mg ai/L

NOAEC=0.372 mg ai/L

 No mortality or sublethal effects 

were reported up to the highest 

concentration tested (<0.372 mg 

a.i./L based on mean measured)

 A precipitate was observed only at 

the highest test concentration (1000 

ug ai/L nominal; 317 ug ai/L 

measured); samples in this treatment 

were filtered and centrifuged prior to 

analysis. 

 Mean measured concentration at the 

second highest treatment (372 ug 

ai/L; non-centrifuged) and the 

highest treatment (317 ug ai/L; 

centrifuged) are suggestive of no 

effects at or near limits of aqueous 

solubility in seawater. 

48341932

Acceptable

Palmer et al 

(2010)

Chronic No Data (waiver request accepted)*

Estuarine/Marine Invertebrates

Acute

TGAI

95.6%

Saltwater mysid 

Americamysis 

bahia

96 h LC50 = 0.327 mg ai/L 

(0.269-0.410)

Probit Slope: N/A

NOAEC= 0.121 mg ai/L

 15%, 65% and 100% mortality 

occurred at 0.23, 0.46 and 0.74 mg 

ai/L (mean measured)

 Mysids in the control groups and 

0.60, and 0.121 mg ai/L showed no 

sublethal effects.

48341929

Acceptable

Palmer et al 

2010

TGAI

95.6%

Eastern Oyster 

(Crassostrea 

virginica)

96 h EC50 = 0.21 mg ai/L

(0.15-0.30 mg ai/L)

NOAEC= 0.14 mg ai/L

 Shell growth was reduced by 14, 21, 

66 and 86% relative to controls at 

0.07, 0.14, 0.28 and 0.60 mg ai/L, 

respectively (mean measured).

 Slight precipitate observed at highest 

treatment; centrifuged samples 

showed no appreciable difference 

from uncentrifuged samples

48341928

Acceptable

Gallagher et al 

(2010) 
70

Table 19. Toxicity Reference Values For Aquatic Organisms Exposed To Tolclofos Methyl and Metabolite 

(DM-TM)

Exposure 

Scenario % A.I. Species Dur.

Toxicity Reference 

Value** 

(95% CL)

Effect Notes

MRID;

Classification (Year)

Chronic

TGAI

95.6%

Saltwater mysid 

Americamysis 

bahia

38 d NOAEC50 = 0.0039 mg 

ai/L

LOAEC= 0.0082 mg 

a.i./L

 No significant treatment-related 

effects on F0 mysid survival 

occurred 

 Insufficient young were available for 

effectively evaluating survival of F1 

mysids 

 Mysid reproduction was the most 

sensitive endpoint; reduced by 50% 

compared to negative controls 

(means) at 8.2 ug ai/L. This was a 

biologically determined LOAEC, as 

test design issues led to poor 

statistical power.

48341933

Supplemental

Palmer et al 

(2009)

Freshwater Benthic Invertebrates

Subchronic TGAI

95.6%

Freshwater 

amphipod, 

Hyalella azteca

10 d Sediment value: 

NOAEC (growth and 

survival) =103 mg 

a.i./kg dw

Pore water value:

NOAEC (growth and 

survival)= 0.854 mg 

ai/L 

 Mean percent survival after 10 days 

was 86, 93, 89, 90, 85, 80, and 95% 

for the negative control, solvent 

control, and mean-measured 4.8, 12, 

24, 48, and 103 mg ai/kg sediment 

levels, respectively

 No sublethal effects on growth (dry 

weight) were observed at any 

treatment level vs. negative controls

48341931

Acceptable

Thomas et al 

(2010)

Chronic

Freshwater 

midge

Chironomus 

riparius

28 d

Sediment value: 

NOAEC (development 

rate) = 0.186 mg ai/kg 

dw (=7.7 mg ai/kg-OC)

Pore water value:

NOAEC (development 

rate)= 0.013 mg a.i./L

 Test vessels were spiked once via 

overlying water 

 Overlying water concentrations 

decline over time, while pore water 

and sediment concentrations 

increased

 No effects on percent emergence at 

any treatment

 Development rate were significantly 

reduced at 0.64 mg/kg dw in 

sediment (mean measured) 

48737504

Supplemental

Putt (2002)

Estuarine/Marine Benthic Invertebrates

Subchronic TGAI

95.6%

Saltwater 

amphipod

Leptocheirus 

plumulosus

10 d Sediment value: 

LOAEC=5.3 mg ai/kg 

dw (survival)

NOAEC= 2.1 mg ai/kg 

dw (survival)

(=75 mg ai/kg-OC)

Pore water value:

LOAEC= 0.42 mg ai/L 

NOAEC = 0.38 mg ai/L 

 An unbounded LOAEC of 5.3 mg 

ai/kg dw as obtained from the initial 

definitive study (61% survival).

 An unbounded NOAEC of 2.1 mg 

ai/kg dw was obtained from a 

continuation study (95% survival). 

48341935

Supplemental

Thomas et al 

(2010)

Aquatic Plants *
71

Table 19. Toxicity Reference Values For Aquatic Organisms Exposed To Tolclofos Methyl and Metabolite 

(DM-TM)

Exposure 

Scenario % A.I. Species Dur.

Toxicity Reference 

Value** 

(95% CL)

Effect Notes

MRID;

Classification (Year)

Algae 

TGAI

98.3%

Green Algae 

Scenedesmus 

quadricauda

7-

days

EC50 = >5.6 mg a.i./L

LOAEC = 0.1 mg a.i./L

NOAEC = 0.032 mg 

a.i./L (biomass)

 LOAEC was determined to be 0.1 

mg ai/L based on significant 

reduction (42%) of biomass (growth 

inhibition) from control by day 4. 

 The maximum test level was 5.6 

ppm because of the low solubility of 

the test compound. DMSO used as a 

co-solvent 

00156121

Supplemental

Takimoto and 

Ysutaniya 

(1983)

TGAI

97.83%

Green Algae 

Scenedesmus 

subspicatus

72 h EC50 = 0.78 mg a.i./L

(0.62-0.92)

NOAEC = 0.18 mg

a.i./L (biomass)

 Algae exposed to 0.13, 0.22, 0.39, 

0.69 and 1.1 mg a.i./L

 Concentrations based on centrifuged 

samples due to solubility limts at 

highest test concentration

48737506

Supplemental

Sayers (2003)

DM-TM 

98.9%

Green Algae S. 

subspicatus

72 h EC50 >97 mg/L

NOAEC = 12 mg/L

LOAEC = 23 mg/L

 Cell density, biomass and growth 

rate were reduced by 8.3%, 8.6% and 

1.3% at the highest test concentration 

(97 mg/L)

48737505

Supplemental

Hoberg (1998)

*Waiver request accepted for chronic toxicity to estuarine/marine fish and aquatic plant toxicity studies (D393184)

** Toxicity endpoints in bold are those used for RQ calculation

a. Freshwater Fish

Acute toxicity studies with technical-grade TM were available for 5 species of freshwater fish: 

rainbow trout (Oncorhynchus mykiss), common carp (Cyprinus carpio) , Japanese medaka 

(Oryzias latipes), bluegill sunfish (Lepomis macrochirus) and guppy (Poecilia reticulata). All 

studies were conducted on TGAI with >97% purity (Error! Reference source not found.Table 19). 

Substantial differences are noted among these studies in terms of when they were conducted 

(e.g., from the early 1980s to 2010), their use of co-solvents (some used dimethylsulfoxide 

[DMSO] and polyoxyethylene hydrogenated castor oil [HCO]), and their test design (static vs. 

flow-through; centrifuged vs. uncentrifuged samples). Despite these differences, the LC50 values 

varied only about 5-fold from 0.69 mg ai/L to 3.2 mg ai/L across all 5 species. These LC50 

values are at or above the reported limit of solubility of TM in laboratory water (0.7-1.0 mg/L; 

Section 3.B). In two of the tests, precipitates were noted in the higher test concentrations (e.g., 

MRID 48341930 and 41400301). In the former test with rainbow trout, reported concentrations 

were based on centrifuged samples. In the latter study with bluegill, samples were not 

centrifuged prior to analysis. Although lack of sample centrifugation in the presence of 

precipitates can justify invalidation of a study, it is highly unlikely that the uncertainty associated 

with the bioavailability of TM in this study would change the aquatic risk conclusions due to the 

extremely low aquatic EECs. Therefore, this study is classified as supplemental. All remaining 

acute toxicity studies with freshwater fish did not report the presence of precipitates (although it 

is unclear whether investigators looked for precipitates). These remaining studies also used an 

atypical co-solvent (DMSO:HCO), although there were no indications that the solvent interfered 

with integrity of the test and the low aquatic EECs renders uncertainty associated with the use of 
72

DMSO as not likely to alter the risk assessment conclusions. Relative to parent TM, the 

degradate DM-TM was practically non-toxic (LC50 >110 mg/L) on an acute exposure basis. For 

risk assessment purposes, an acute toxicity reference value of 0.69 mg ai/L (MRID 48341930) 

will be used for calculating acute risk quotients for freshwater fish. Based on an acute 96-hr 

LC50 value of 0.69 mg ai/L, TM is classified as highly toxic to freshwater fish on an acute 

exposure basis.

The observed NOAECs for sublethal effects to freshwater fish included loss of equilibrium, 

abnormal respiration, lethargy and darkened color and were observed at exposure concentrations 

ranging between 0.05 to 1.0 mg ai/L. 

Chronic toxicity to freshwater fish is estimated based on an early life stage study with rainbow 

trout (MRID 42106501). Embryos (<24 hours old) were exposed in a flow-through system to 

TM (TGAI 97.6%) to mean-measured concentrations of 0.012, 0.028, 0.053, 0.11, and 0.20 mg 

ai/L for 97-days. A negative control and a solvent control were also tested. Results indicate that 

hatching time was not significantly different at any treatment concentration relative to controls. 

The percentage of eggs that hatched was affected at only the highest treatment level (200 ug 

ai/L) while both time to swim-up and fry survival (60-d post hatch) were significantly different 

from controls at the two highest treatments (110 and 200 ug ai/l). Trout length (37-d post-hatch) 

and wet weight (60-d post-hatch) were the most sensitive endpoints examined, with statisticallysignificant reductions of 1.3% and 24%, respectively, in the 12 ug ai/L treatment relative to 

negative controls. The overall chronic NOAEC is <12 ug ai/L and LOAEC is 12 ug ai/L for 

fish weight (60-d post-hatch) and fish length (37-d post-hatch) which will be used for 

calculating chronic risk quotients to freshwater fish. This study is considered supplemental 

because a definitive NOAEC was not achieved.

b. Freshwater Invertebrates

Acute toxicity studies of TM TGAI to freshwater (pelagic) invertebrates were available for 

Daphnia magna and D. pulex (Table 19). A 48-h EC50 of 48 mg ai/L and a NOAEC of 17 mg 

ai/L were determined for D. magna on the basis of immobilization. These concentrations are 1-2 

orders of magnitude higher than the solubility of TM in water. Even with the use of 

dimethylformamide (DMF) as a co-solvent, surface films and precipitation was observed in the 

study. There was no indication that samples were filtered or centrifuged prior to analysis. 

Therefore, endpoints from this study are considered uncertain with respect to the actual amount 

of TM that was dissolved in test media Although lack of sample centrifugation in the presence of 

precipitates can justify invalidation of a study, it is highly unlikely that the uncertainty associated 

with the bioavailability of TM in this study would change the aquatic risk conclusions due to the 

extremely low aquatic EECs. Therefore, this study is classified as supplemental.. A 24-h acute 

toxicity test with D. pulex was also available, but it did not fulfill guideline requirements because 

the test was only conducted for 24 hours. The 24-h EC50 based on organism immobility was 2.4 

mg ai/L; there were also no mortalities at the highest test level (10 ppm). Although samples 

were not centrifuged prior to analysis, no solubility problems (precipitates) were reported by the 
73

study authors. Similar to the results with freshwater fish, the degradate DM-TM was practically 

non-toxic to freshwater invertebrates as indicated by a 48-h EC50 of >95 mg/L. 

For risk assessment purposes, the most sensitive acute toxicity endpoint for freshwater 

invertebrates is a 24-h EC50 of 2.4 mg ai/L for D. pulex. Since this value exceeds the reported 

solubility of TM (0.7-and 1.0 mg/L), and reflects only 24-h exposure (not the recommended 48 

hours), an acute toxicity reference value equivalent to the solubility of TM in water (0.7 

mg/L) will be used for calculating acute risk quotients for freshwater invertebrates. Based 

on a 24-hr EC50 of 2.4 mg ai/L, TM is classified as moderately toxic to freshwater invertebrates 

on an acute exposure basis.

A freshwater invertebrate (D. magna) lifecycle test with TM TGAI (97.6%) was submitted and 

found to be supplemental (raw data on reproduction were not included; MRID 41400303). 

Daphnids were exposed throughout their life cycle to mean-measured concentrations of TM 

ranging from 0.026 to 0.39 mg ai/L for 21 days. Survival was significantly different between the 

pooled controls and the mean measured exposure levels 0.19 and 0.39 mg/L. The mean 

young/adult reproduction day after 21 days was significantly greater in the solvent control (4.7 

young/adult reproduction day) compared to the negative control (3.8 young/adult reproduction 

day). Therefore, the original analysis of the data compared results to the solvent control, which 

indicated significant effects at mean-measured concentrations of 0.062, 0.089, and 0.19 mg ai/L. 

Based on reproductive effects, the NOAEC and LOAEC are estimated at 0.026 and 0.062 mg 

ai/L. respectively. Raw data were not provided in the study report from which to recalculate the 

endpoints according to comparisons to negative controls (current EFED policy). However, the 

apparent solvent effect resulted in an increase in reproduction and the LOAEC (3.2 

young/reproduction day at 0.062 ug ai/L) still represents a 15% reduction relative to the negative 

controls (3.8 young/reproduction day). Therefore, it is reasonable to consider the effects at 0.062 

mg ai/L biologically significant even if recalculation resulted in no statistically significant 

difference relative to negative controls. For risk assessment purposes, a chronic toxicity 

reference value of 0.026 mg ai/L will be used for calculating chronic risk quotients for 

freshwater invertebrates.

c. Estuarine/Marine Fish

One study was submitted for this taxonomic group that consisted of an acute exposure to 

sheepshead minnow (Cyprinodon variegates) to TM (MRID 48341932). In this study, no 

mortality or sublethal effects were reported up to and including the highest concentration tested 

(0.372 mg ai/L). At the highest test concentration (1.0 mg ai/L), a precipitate was observed and 

test concentrations were centrifuged prior to analysis. Results from this study indicate that TM is 

not acutely toxic to sheepshead minnow at levels approaching the limit of solubility for TM in 

saltwater. 

No data were submitted on the chronic effects of TM to estuarine/marine fish. A waiver request 

for this study was accepted on the basis of expected low likelihood of chronic effects to 

estuarine/marine fish in consideration based on low projected EECs in relation to available 
74

toxicity data for fish. Additional characterization of the uncertainty associated with the lack of 

chronic toxicity data for estuarine/marine fish is provided in Section IV.B (Risk Description). 

d. Estuarine/Marine Invertebrates

Acceptable acute toxicity studies were available for two species of estuarine/marine 

invertebrates: the mysid shrimp (Americamysis bahia; MRID 48341929) and Eastern oyster 

(Crassostrea virginica; MRID 48341928). With mysids, a 96-h LC50 value of 0.327 mg ai/L was 

obtained which is about 2X lower than the reported solubility of TM. The solvent DMF was 

used in this test and no precipitates were noted in test vessels. No overt signs of toxicity were 

noted up to 0.121 mg ai/L, which is considered the NOAEC in this study.

With the Eastern oyster, a 96-h EC50 for shell deposition was determined . Shell growth was 

reduced by 14, 21, 66 and 86% relative to controls at 0.07, 0.14, 0.28 and 0.60 mg ai/L, 

respectively (mean-measured concentrations). A solvent (DMF) was used in this study. A 

precipitate was observed at the highest test concentration but analysis of centrifuged samples 

yielded similar results as uncentrifuged samples. For risk assessment purposes, an acute 

toxicity reference value of 0.21 mg ai/L will be used to assess acute risks to estuarine/

marine invertebrates. Based on a 96-hr EC50 of 0.21 mg ai/L, TM is classified as moderately 

toxic to estuarine/marine invertebrates on an acute exposure basis.

e. Benthic (Sediment Dwelling) Invertebrates

Effects of TM on freshwater benthic invertebrates are available from two studies: a 10-d 

exposure via spiked sediment to the amphipod Hyalella azteca (MRID 48341931) and a 28-d 

exposure via spiked overlying water to the midge Chironomus riparius (MRID 48737504; Error! 

Reference source not found.Table 19). In the first study, 7-14 day old H. azteca were exposed to 

spiked sediment concentrations of 4.8, 12, 24, 48, and 103 mg ai/kg dry weight (meanmeasured). Concentrations in sediment and interstitial sediment “pore” water remained 

relatively stable from day 0 to day 10. No treatment related reductions in amphipod survival or 

growth (dry weight; dw) relative to negative controls occurred after 10 days exposure. On the 

basis of sediment dry weight, sediment organic carbon (OC), and pore water, the NOAECs from 

this study are 103 mg/kg dw, 4120 mg/kg-OC, and 0.854 mg ai/L, respectively. As seen with 

other toxicity studies of aquatic animals, the NOAEC from this study approximates the solubility

limit of TM in water. 

Results from the chronic study on C. riparius indicate development rate was significantly 

reduced by 3.4% relative to negative controls at 0.188 mg ai/L porewater, resulting in a NOAEC 

of 0.013 mg ai/L pore water (0.186 mg ai/kg dw in sediment, 7.7 mg ai/kg-OC). This NOAEC is 

substantially lower than the 10-d NOAEC obtained for H. azteca (0.013 mg ai/L pore water for 

midge vs. 0.854 mg ai/L pore water for amphipod; Error! Reference source not found.Table 19). 

This lower NOAEC likely reflects a combination of factors including interspecies differences in 

sensitivity to TM, inclusion of a longer exposure duration, and measurement of additional 
75

endpoints (e.g., development rate). It is important to note, however, that this study involved 

exposure via the overlying water and concentrations varied considerably over time. Specifically, 

both pore water and sediment concentrations increased dramatically from day 0 to day 14, while 

overlying water concentrations decreased, thus reflecting the expected partitioning of TM to 

sediments from the water column. Although the test guideline followed in this study (OECD 

219) is designed to mimic a spray drift event, spray drift is not expected for the proposed uses of 

TM (seed treatment). OSCPP test guidelines recommend that sediments be equilibrated with test 

compound prior to testing and Agency-wide guidelines (USEPA 2000) recommend inclusion of 

reproductive effects as measurement endpoints in Chironomus chronic tests. In this study, 

midges were added 24 hours after addition of the test substance to sediment. Therefore, this 

study is classified as supplemental.

The effects of TM on the saltwater amphipod, Leptocheirus plumulosus, were examined in a 

series of two 10-d spiked sediment exposures (MRID 48341935). In the first exposure series, 

amphipods were exposed to mean-measured concentrations of 5.3, 11, 23, 48 and 97 mg a.i./kg 

dw plus solvent and negative controls. However, the lowest test concentration (5.3 mg ai/dw) 

resulted in statistically-significant effects on amphipod survival (61% of amphipods survived at 

this concentration). Therefore, another study was conducted in which amphipods were exposed 

to 0.45, 1.1 and 2.1 mg ai/kg dw plus solvent and negative controls for 10 days. In this study, no 

statistically-significant effects occurred relative to controls (>95% survival at the highest test 

concentration.) The pore water concentration corresponding to this NOAEC is 0.38 mg ai/L, 

which is about half the limit of solubility for TM. The NOAEC in sediment is 2.1 mg ai/kg dw 

and 75 mg ai/kg-OC when normalized to 100% organic carbon. Although in combination both 

test series can be used to identify a definitive NOAEC, the fact that neither test series resulted in 

a NOAEC that was bounded with a LOAEC introduces uncertainty in the estimated NOAEC. 

For example, different groups of organisms from in-house cultures were used to test TM at 

different times. Therefore, this study is classified as supplemental.

f. Aquatic plant

Of the two aquatic plant toxicity studies submitted on TM TGAI using freshwater green algae 

(Pseudokirchneriella subcapitata), the most sensitive yielded a 72-hr EC50 of 0.78 mg ai/L and a 

NOAEC of 0.18 mg/L. A toxicity test of the degradate DM-TM with P. subcapitata indicated 

that the degradates was less toxic to green algae (96-hr EC50>97 mg ai/L; NOAEC=12 mg ai/L) 

by several orders of magnitude. There is uncertainty though regarding the effects to other 

nonvascular plants (algae) as only one rather than the four species recommended in OPPTS 

Guideline 850.5400 was tested. Additionally, there is uncertainty regarding the potential effects 

of TM on vascular aquatic plants (OPPTS Guideline 850.4400) as no data are available. 

However, a recent analysis conducted to support a data waiver request for additional aquatic 

plant data suggests that additional data for aquatic plants would have a low potential to affect 

risk assessment conclusions (D393184). Additional discussion of the uncertainty associated with 

the lack of a full aquatic plant data set is provided in Section IV.C.

2. Terrestrial Effects 
76

All toxicity reference values used to assess the potential acute and chronic risks of TM exposure 

to mammals were obtained from acceptable or supplemental studies using TM TGAI submitted 

to the OPP Health Effects Division (HED) for review. No data on the toxicity of TM degradates 

to terrestrial plants and animals were submitted. Acute and chronic data for other terrestrial taxa 

were reviewed by EFED and the resulting endpoints are reported in Table 20. A brief summary

of these studies follows this table, with detailed summaries provided in Appendix D.

Table 20. Toxicity Reference Values For Terrestrial Organisms Exposed To Tolclofos Methyl

Exposure 

Scenario % A.I. Species Dur.

Toxicity Reference 

Value** 

(95% CL)

Effect Notes

MRID;

Classification 

Avian Toxicity

Acute

TGAI 

99.8%

Mallard Duck 

Anas 

platyrhynchos

(Acute Oral)

14 d LD50 >5000 mg ai/kg 

bw

NOAEL =5000 mg ai/kg 

bw

 No mortalities in control or at the 

5000 mg/kg test level. 

 Weight changes were variable for all 

birds, but within normal limits.

00156112 

Acceptable

Roberts and 

Haskins (1981)

TGAI 

97.7%

Mallard Duck A.

platyrhynchos

(Subacute, 

Dietary)

8 d LC50 >5620 mg ai/kg 

diet

NOAEL = 5620 mg 

ai/kg diet

 No mortalities occurred at any test 

concentration

 Food consumption and weight gain 

were similar at all test levels.

00156115 

Acceptable

Beavers (1985)

TGAI 

99.8%

Bobwhite Quail 

Colinus 

virginianus

(Acute Oral)

14 d LD50 >5000 mg ai/kg 

bw

NOAEL = 5000 mg 

ai/kg bw

 No mortalities in control or at the 

5000 mg/kg test level. 

 Weight changes were variable for all 

birds, but within normal limits. 

00156113 

Acceptable

Roberts and 

Haskins (1982)

TGAI 

97.7%

Bobwhite Quail 

C.virginianus

(Subacute 

Dietary)

8 d LC50= >5620 mg ai/kg 

diet

NOAEL = 5620 mg 

ai/kg diet

 No mortalities at the 562, 1780, 3160 

and 5620 ppm levels. 

 A total of 6/50 (12%) of control 

birds died which was attributed to 

aggression 

 There was 20% mortality (2 of 10) at 

the 1000ppm level but this did not 

appear treatment related.

 There was no apparent effect on 

body weight or feed consumption at 

any treatment level. 

00156116

Acceptable

Beavers (1985)

TGAI 

99.8%

Ring-necked 

Pheasant 

Phasianus 

colchicus

(Acute Oral)

14 d LD50 >5000 mg ai/kg 

bw

NOAEL = 5000 mg 

a.i./kg bw

 One mortality (5%) occurred of the 

20 test birds at the 5000 mg/kg test 

level. This was considered a result of 

aggression, not test treatment. 

 No treatment-related impact was 

observed on body weights, which 

appeared variable but within normal 

limits. 

00156114

Acceptable

Roberts and 

Haskins (1981)
77

Table 20. Toxicity Reference Values For Terrestrial Organisms Exposed To Tolclofos Methyl

Exposure 

Scenario % A.I. Species Dur.

Toxicity Reference 

Value** 

(95% CL)

Effect Notes

MRID;

Classification 

TGAI 

95.6%

Zebra Finch 

Poephilia guttata 14 d LD50 >2000 mg ai/kg 

bw

LOAEL= >2000 mg 

ai/kg bw

NOAEL= 2000 mg ai/kg 

bw

 No mortality, change in body weight 

or clinical signs of toxicity occurred 

at the limit dose (2000 mg ai/kg bw). 

 However, regurgitation occurred in 2 

(17%) of the test animals in the 

nominal 2000 mg ai/kg bw treatment 

group within the first hour of dosing

 Given that the remaining 10 birds 

that did not regurgitate the test 

material and no other lethal or 

sublethal effects occurred, the LD50 

is considered > 2000 mg ai/kg bw. 

48341936 

Acceptable

(2010)

Chronic TGAI 

97.7%

Mallard Duck A. 

platyrhynchos 12 wk LOAEL=2500 mg ai/kg 

diet

NOAEL=500 mg ai/kg 

diet

 At 500 ppm, no treatment related 

mortalities or overt signs of toxicity 

occurred.

 At 2500 ppm, 3 of the 32 adults died 

and significant reductions (up to 

50% of controls) occurred in # eggs 

laid/set; viable embryos and egg 

hatch.

 At 7500 ppm, 10 of 32 adults died. 

At both 2500 and 7500, lower limb 

weakness and other toxic symptoms 

were observed. 

40190202

Acceptable

(Beavers et al. 

1987)

TGAI 

97.7%

Bobwhite Quail 

C. virginianus 13 wk LOAEL=2500 mg ai/kg 

diet

NOAEL= 500 mg ai/kg 

diet

 A significant reduction in the 

number of eggs laid, eggs set, viable 

embryos live embryos and eggs 

hatched occurred in both the 2500 

and 7500 ppm concentrations. 

 No clinical signs of toxicity occurred 

at 500 ppm diet.

40190201 

Acceptable

Beavers and 

Jaber (1987)

Mammals

Acute

TGAI

97.7%

Rat

(Rattus 

norvegicus)

14 d LD50 >5000 mg ai/kg bw 

(both sexes)

 No mortality, change in body weight 

at the limit dose (5000 mg ai/kg bw). 

 sublethal signs of toxicity (e.g., 

hunched posture) occurred but full 

recovery was observed by day 5

00156124

Acceptable

(Kynoch 1985)

Rat

(R. norvegicus)

14 d LD50 = 4900 mg ai/kg 

bw (both sexes)

Probit Slope: n/a

NOAEC = 2500 mg 

ai/kg bw

 55% mortality (11/20) at the highest 

treatment (5000 mg ai/kg bw). 

 Sublethal effects occurred at 3750 

and 5000 mg ai/kg bw.

00156128

Acceptable

(Segawa et al. 

1978)

TGAI

97.0%

Mouse

(Mus musculus)

14 d LD50 =3500 mg ai/kg 

bw (males) (2760-4800)

LD50 =3600 mg ai/kg 

bw (females; 2710-

4790)

Probit slope: n/a/

NOAEC =1000 mg 

ai/kg bw

 10, 20, 30 and 60% mortality 

occurred at 1500, 2000, 3000, and 

4000 mg ai/kg bw, respectively.

 Clinical signs of toxicity >1500 mg 

ai/kg included ataxia, irregular 

respiration, decreased motor activity

00156128

Acceptable

(Segawa et al. 

1978)
78

Table 20. Toxicity Reference Values For Terrestrial Organisms Exposed To Tolclofos Methyl

Exposure 

Scenario % A.I. Species Dur.

Toxicity Reference 

Value** 

(95% CL)

Effect Notes

MRID;

Classification 

Chronic

TGAI

94.9%

Rat

(R.norvegicus)

Dvlp* NOAEL =300 mg/kg 

bw/d

LOAEL = 1000 mg 

ai/kg bw/d

 Rats dose with 0, 100, 300, and 1000 

ppm (D6 – D15 of gestation via 

gavage).

 No treatment related effects on 

survival, body weight, food 

consumption, histopathology

 Significant increase in skeletal 

deformation (unossification of 6th

sternebrae) of fetus at 1000 ppm 

highest dose (12%) vs. control (4%)

41422901 

Acceptable

(Morseth 1987)

TGAI

98.7%

Beagle dog

(C. lupus 

familiaris)

6 mo NOAEL = The NOAEL 

is 600 ppm (23/20 

mg/kg/day M/F).

 At 2000 ppm diet, decreased body 

weight gain, hematocrit, hemoglobin 

erythrocyte count. In addition, 

alkaline phosphatase and absolute 

and relative liver weight were 

significantly increased. 

 Plasma cholinesterase activity was 

significantly depressed in high dose 

females at all reporting periods (4-24 

wks).

00156138

Supplemental

(Pence et al. 

1979)

TGAI 

97%

Mouse

M. musculus

9 mo NOAEL = 100 ppm 

(13.8 and 12.2 mg 

ai/kg bw for M/F)

 Oral dietary exposure to 0, 10, 30, 

100, and 3000 ppm

 Significantly lower weight gain in 

males and females at 3000 ppm (503 

mg ai/kg bw)

 Cholinesterase inhibition in 30, 100 

and 3000 ppm in females (plasma)at 

study termination (9 mo)

00156137 

Supplemental

(Suzuki et al. 

1978)

Nontarget Insects - Bees

Acute

TGAI 

97.7%

Honeybee Apis 

mellifera 48 h LD50 >100 ug ai/bee  Mortality was 4% or less at 13, 22, 

36, 60, and 100 ug ai/bee

 Mortality in the negative and solvent 

controls was 2% and 10% 

respectively. 

41794202

Acceptable

Winter et al 

(1990)

TGAI 

97.6%

Honeybee A. 

mellifera 24 h LD50 >100 ug ai/bee  Mortality was 0% at 12.5 and 50 ug 

ai/bee; 6.7 and 16.7% at 25 and 100 

ug ai/bee. 

 No information on whether a control 

was used was indicated by the study 

authors.

00163557

Supplemental

(1983)

Nontarget Terrestrial Plants (No data; waiver request accepted)*

*Waiver request accepted for terrestrial plant toxicity studies (D393184)

** Toxicity endpoints in bold are those used for RQ calculation
79

a. Birds (Acute Toxicity)

Acute oral and subacute dietary toxicity studies are available for four avian species, i.e.,bobwhite 

quail (Colinus virginianus) , ring-necked pheasant (Phasianus colchicus) , mallard duck (Anas 

platyrhynchos), zebra finch (Poephilia guttata) represent three orders of birds, i.e, Galliformes, 

Anseriformes, and Passeriformes (Table 20). Overall, these studies indicate that, based on the 

toxicity classification scheme used by EFED, TM is practically non-toxic, i.e., LD50>2000 mg 

ai/kg bw, to these species of birds on an acute exposure basis. For bobwhite, ring-necked 

pheasant, and mallard, no treatment-related mortality occurred at the highest dose tested 

(Accession No. 00156112, 00156113, 00156114). Furthermore, no treatment-related sublethal 

signs of toxicity (e.g., adverse effects on body weight, food consumption) were reported in these 

studies. Similarly for zebra finch, no treatment related effects on mortality, body weight or 

clinical signs of toxicity occurred at the limit dose (2000 mg ai/kg bw). Within the first hour of 

dosing, 2/12 finches regurgitated at the limit dose. However, none of the remaining birds 

regurgitated or showed other sublethal signs of toxicity. Therefore, the finch study validity is not 

considered to be impacted by this low rate of regurgitation. For risk assessment purposes, an 

acute oral LD50 of >2000 mg ai/kg bw) for passerines will be used qualitatively to evaluate 

potential acute effects to birds (i.e., a value of 2000 mg ai/kg bw will be assumed as a screen 

for acute effects). Based on an 14-day LD50>2000 mg ai/kg bw for zebra finches, TF is 

classified as practically non-toxic to birds on an acute oral exposure basis.

For bobwhite quail and mallard, the subacute dietary LC50 is >5260 mg ai/kg diet since no 

treatment-related mortality occurred at the highest concentrations tested. In the bobwhite quail 

study, control mortality (12%) was greater than normally accepted. However, this was attributed 

to aggression (evidenced by toe picking) in 2 of the 5 control replicates. Furthermore, no 

mortalities occurred at the lowest test level, 562 ppm, or at the 1780, 3160 and 5620 ppm levels. 

No apparent effect of TM on body weight or food consumption was observed at any treatment 

level. For mallard, no mortality occurred in controls or in any treatment level tested. For risk 

assessment purposes, an acute oral LC50 of >5260 ppm in the diet) will be used qualitatively 

to evaluate potential acute effects to birds (i.e., a lower bound of 5260 ppm will be assumed 

as a screen for acute effects). Based on an 8-day LC50>5260 mg ai/kg diet for mallard duck, TF 

is classified as practically non-toxic to birds on a subacute dietary exposure basis. 

b. Birds (Chronic Toxicity)

Two studies were submitted that examined the chronic toxicity of TM to avian species (Table 

20). In the study with mallards, Beavers et al. (1987; MRID 40190202) 41-week old mallards (3

groups of 16 replicate pairs/group) approaching their first breeding season were fed a diet 

containing 500, 2500 or 7500 ppm of TM (97.7% ai). A fourth group was fed a control diet 

containing 0.09% corn oil, the amount used as a carrier for the test material. No treatment-related 

mortalities or overt signs of toxicity occurred at 500 ppm. At 2500 ppm, 3(9.3%) of the 32 adults 

died; and at 7500, 10 died (31%). At both 2500 and 7500, lower limb weakness and other toxic 

symptoms were observed. Analysis of variance indicates that at 2500 ppm, statistically
80

significant reductions were observed in number of eggs laid, eggs set, viable embryos, and eggs 

hatched. The NOAEC from this study is 500 mg ai/kg-diet.

In the study of bobwhite quail, Beavers et al. (1987 MRID 40190201) fed 22-week old quail (3 

groups of 16 replicate pairs/ group) approaching their first breeding season a diet containing 

500, 2500 or 7500 ppm of TM (97.7% ai). A fourth group was fed a control diet containing 

0.09% corn oil, the amount used as a carrier for the test material. No treatment-related mortalities 

or overt signs of toxicity occurred. There were no statistically significant differences in adult 

body weight of males between control and any treatment groups. Females at 7500 ppm exhibited 

a slight (5%), but statistically significant reduction of body weight during week 7. Feed 

consumption appears to have been reduced at the 7500 ppm level. There was no apparent effect 

on treatment parameters or sublethal effects at the 500 ppm concentration. When compared to 

the control group, there was a significant reduction in the number of eggs laid in both the 2500 

and 7500 ppm concentrations. The reduction in number of eggs laid (22% & 3%) resulted in a 

reduced number of eggs set (25% & 11%), viable embryos (20% & 10%), live embryos (20% & 

11%) and eggs hatched (23% & 40%) relative to controls at the 2500 and 7500 ppm levels, 

respectively. There was no apparent effect on cracked eggs. The NOAEL for TM in this study is 

500 ppm. The dietary chronic NOAEL of 500 ppm will be used for calculating chronic risk 

quotients to avian species. 

c. Mammals (acute toxicity)

For evaluating acute oral toxicity, four studies were available for rat, mouse and dog (Table 20). 

All studies with mammals indicated TM was practically nontoxic or at most, slightly toxic to 

mammals on an acute oral exposure basis. 

In the first of two acute oral studies conducted with rats (Rattus norvegicus), Segawa et al. 

(1978; Accession No. 00156128) exposed groups of 10 male and 10 female Sprague-Dawley

(SD) strain rats via gavage to TM (97.0% ai) to 1000, 2500, 3750, and 5000 mg ai/kg bw and 

followed the animals for 14 days. At the highest dose (5000 mg ai/kg bw), 5 males and 6 

females were found dead within 1-5 days post-treatment. Clinical signs of toxicity occurred in 

rats dosed at 3750 and 5000 mg ai/kg bw and included decreases in spontaneous motor activity, 

irregular respiration, piloerection, urinary incontinence and hind-limb ataxia. The 14-day LD50

was calculated to be 4900 mg ai/kg bw (both sexes combined). No visible lesions were evident 

at gross necropsy. 

Kynoch 1985 (Accession No. 00156124) also investigated the acute toxicity of TM technical in 

SD rats. After a range finding study, a limit test was conducted using a single dose of 5000 mg 

ai/kg bw (97.7%) to 5 male and 5 female rats. No mortality occurred for either male or female 

rats 14 days after dosing. Clinical signs of toxicity were observed in all animals tested and 

included piloerection and hunched posture shortly after dosing with complete recovery in 5 days. 

Body weight gains were observed in all test animals and at sacrifice none of these animals had 

any abnormal gross morphological lesions. Thus, the acute oral LD50 for male and female rats 

was >5,000 mg ai/kg.
81

Toxicity was observed with mice (Mus musculus) on an acute oral exposure basis as that 

described above for rats. Specifically, Segawa et al. 1978 (Accession No. 00156128) exposed 

10 male and 10 female mice to TM at doses of 1000, 1500, 2000, 3000, 4000 mg ai/kg bw. After 

14 days, mortality at these doses (from low to high) was 0, 5, 15, 25 and 60% respectively and 

was similar for both sexes. Mice (male and female) receiving 1500 mg ai/kg or higher exhibited 

the same signs of toxicity as those reported for rats by the same authors (see above). The 14-day

acute oral LD50 for male mice was 3500 mg ai/kg and 3600 mg ai/kg for male and female mice, 

respectively. 

Based on a 14-day acute oral LD50 of 3500 mg ai/kg bw for mice, TM is classified as practically 

non-toxic to mammals on an acute exposure basis.

d. Mammals (chronic toxicity)

Although several studies were available on the chronic oral toxicity of TM to rats and mice that 

included effects on reproduction, most were considered by HED to be invalid due to study

performance issues. Therefore, for assessing ecological risks to mammalian wildlife, the most 

appropriate studies identified among submitted studies include a developmental toxicity study 

with rat, a 6-month dietary study with dog and a 9-month subchronic dietary exposure study with 

mice (Error! Reference source not found.Table 20.). 

Morseth 1987(MRID 41422901) evaluated the developmental toxicity of TM to rats. TM 

(94.9% ai) was administered by gavage to rats on gestation days 6 through 15, inclusive at doses 

of 0, 100, 300, and 1000 mg /kg bw/d. No clinical signs of toxicity were noted during the study. 

No fetal deaths were reported in any of the groups. There was a non-significant dose-related 

decrease in corrected body weight gains during the dosing period and during the entire gestation 

period, when compared to the controls. The only finding of statistical significance was unossified 

6

th sternebra, at the 1,000 mg/kg/day group when compared to the controls. The NOAEL from 

this study is 300 mg ai/kg bw/d based on skeletal abnormalities in developing rats.

Pence et al. 1979 (Accession No. 00156138) examined the effect of TM (98.7%) on beagle dogs 

fed diets spiked with 0, 200, 600, and 2000 ppm TM over 6 months. Animals (6/treatment) were 

5-7 months old ranging in weight from 6.7 to 12.4 kg in males, and 5.8 to 10.2 kg in weight for 

females. The following parameters were depressed at 2000 ppm at test termination: body weight 

gain, hematocrit, hemoglobin and erythrocyte count. In addition, alkaline phosphatase and 

absolute and relative liver weight were significantly increased in high dose males and females. 

Relative to controls, plasma cholinesterase activity was significantly depressed by 19-27% in 

high dose females at all reporting periods (4-26 wks). No compound related gross or microscopic 

lesions were reported. Based on these findings, the NOAEL is 600 ppm which corresponds to 20 

and 23 mg ai/kg bw/d for males and females respectively. 

In the subchronic oral toxicity study with mice, Suzuki et al. 1978 (MRID 00156137) fed 15 

male and 15 female mice a diet containing 0, 10, 30, 100, and 3000 ppm TM (97% ai) for 90 

days. All animals survived the study, and no abnormal clinical signs were reported. Both body

weight and body weight-gain were reduced in the highest dosage group (3000 ppm), although 
82

food consumption was increased in these groups. At 3000 ppm, body weights of males and 

females at the highest dose group were about 20% reduced relative to controls. The only other 

significant toxicity observed in this study was plasma cholinesterase inhibition in female mice at 

doses of 30 ppm and above at test termination (9 mo). For ecological risk assessment 

purposes, a NOAEL of 100 ppm in the diet (13.8 mg ai/kg bw for males, 12.2 mg ai/kg bw 

for females) is determined from this study. 

e. Non-target Beneficial Insects

Two studies were submitted that examined the acute contact toxicity of TM to young adult 

honeybee (Apis mellifera; Error! Reference source not found.Table 20.). The first study, conducted 

in 1983, examined contact exposure of bees to TM (97.6% ai) for 24 hours (Accession No.

00163557). A maximum of 16.7% mortality occurred at the limit dose (100 ug ai/bee) thus 

yielding a 24-hr LD50 of >100 ai/bee. Because the exposure duration was just 24 hours (rather 

than the 48 hours recommend in the 850.3020 test guidelines, and information on control 

performance was not provided, this study is considered supplemental. The second study, 

conducted for the recommended 48 hours in 1987, corroborated the results from the first study

(MRID 41794202). The maximum mortality was 4% up to 100 ug ai/bee and <10% in the 

controls. The 48-hr acute contact LD50 is therefore >100 ug ai/bee which classifies TM as 

practically non-toxic to young adult bees on a acute contact exposure basis.

f. Terrestrial Plants

No toxicity data are available for terrestrial plants. However, a recent analysis conducted to 

support granting a data waiver request for terrestrial plant data suggests that additional data for 

terrestrial plants would have a low potential to affect the risk assessment conclusions (D393184). 

Additional discussion of the uncertainty associated with the lack of a terrestrial plant data is 

provided in Section IV.C. .
83

IV. RISK CHARACTERIZATION

Risk characterization is the integration of exposure and effects characterization to determine the 

potential ecological risk from the proposed use of TM as a seed treatment and the likelihood of 

adverse effects on aquatic life, wildlife, and plants based on varying pesticide-use scenarios. The 

risk characterization provides estimation and a description of the risk; articulates risk assessment 

assumptions, limitations, and uncertainties; synthesizes an overall conclusion; and provides the 

risk managers with information to make regulatory decisions.

A. Risk Estimation - Integration of Exposure and Effects Data 

Results of the exposure and toxicity effects data are used to evaluate the likelihood of adverse 

ecological effects on non-target species. As discussed in the Problem Formulation, for the 

assessment of TM risks, the risk quotient method is used to compare exposure and measured 

toxicity values (refer to Appendix E). Estimated environmental concentrations are divided by 

the most sensitive acute and chronic toxicity values. The RQs are then compared to the 

Agency’s levels of concern. These LOCs, summarized in Appendix E, are the Agency’s 

interpretive policy and are used to analyze potential risk to non-target organisms and the need to 

consider regulatory action. These criteria are used to indicate when a pesticide’s use as directed 

on the label has the potential to cause adverse effects on non-target organisms. 

1. Non-target Aquatic Animals and Plants 

To assess risk of TM to non-target aquatic animals and plants, surface water, pore water and 

sediment EECs for TM were obtained from the Tier 2 models PRZM and EXAMS based on the 

label-recommended usage scenarios (Table 3). As discussed in Section III.B, two different TM 

use assumptions were used to generate aquatic EECs: 

Case 1 (Most Conservative): Assuming that the application of TM-treated seeds results 

in the maximum application rate 0.02 lb ai/A specified on the label for all crops, 

irrespective of the realism in the seeding rate needed to achieve this maximum 

application rate; and,

Case 2 (Most Realistic): Using realistic (BEAD recommended) seeding rates specific for 

each crop combined with label recommended seed treatment rates (mg ai/100 kg seed).

Case 1 results in the highest aquatic EECs, but in some cases, it requires unrealistically-high 

seeding rates to achieve the 0.02 lb ai/A maximum allowable rate specified on the label. Case 2 

results in equal (some crops) or lower (most crops) aquatic EECs, but the seeding rates used are 

considered realistic high-end rates.

a. Water Column Exposure: Acute and Chronic Risk to Animals 
84

Fish

Risk quotients for evaluating the potential for fish to be exposed to acutely toxic concentrations 

of TM were determined as the ratio of the 1-in-10 year maximum daily EEC to the appropriate 

acute toxicity reference value (96-hr LC50=690 and >372 ppb for fresh and saltwater fish, 

respectively) described in Section III.B. Risk quotients for evaluating the potential of fish to be 

exposed to chronically toxic concentrations of TM were determined as the ratio of the 1-in-10 

year maximum 60-day average EEC to the appropriate chronic toxicity reference value 

(NOAEC<12 ug ai/L) for freshwater fish. A total of 65 acute and chronic EECs were derived 

using the exposure assumptions of Case 1 (using the most conservative use rate assumptions) and 

171 EECs were derived for Case 2 (using the most realistic use rate assumptions). Of these, the 

greatest peak EEC in surface water is 0.344 ppb for Case 1 (Table 15) and 0.148 ppb for Case 2 

(Table 16). These maximum peak EECs were modeled with the Florida Carrots exposure 

scenario (Case 1) and the Georgia Onion w/ irrigation exposure scenario (Case 2). Maximum 

60-d average EECs using Case 1 resulted from the Florida Pepper scenario (0.147 ppb) while 

that for Case 2 resulted from the Georgia Onion w/ irrigation crop exposure scenario (0.060 

ppb). 

Overall maximum acute and chronic RQs for fish determined from all the crop exposure 

scenarios are provided in Table 21. The maximum acute RQs are at least two orders of 

magnitude below the acute risk LOC. For saltwater fish, the acute LC50 value was non-definitive 

(>372 ug ai/L). Therefore, a definitive RQ is not able to be calculated; however it is known to be 

less than <0.0008 (Case 1) and <0.0004 (Case 2). For chronic RQs, data were available only for 

freshwater fish. For this risk assessment, re-analysis of the toxicity data yielded a NOAEC of 

<12 ug ai/L. Therefore, the actual chronic RQ is unknown, but is known to be >0.008 (Case 1) 

and >0.005 (Case 2). The uncertainty in these upper and lower bound RQ values is discussed 

further in Section IV.B (Risk Description).

Table 21. Acute and chronic risk quotients (RQs) for evaluating toxic risk of TM exposure to 

freshwater and saltwater fish 

Organism

LC50

(μg a.i./L)b NOAEC

(μg a.i./L) b

EECc

Peak

(μg a.i./L)

EECc

60-Day

(μg a.i./L)

Acute

RQ

(peak 

EEC/LC50)

Chronic

RQ

(60-day 

EEC/NOAEC)

Freshwater Fish

(Case 1) a

690 <12 0.343 0.147 0.0005 >0.01

Freshwater Fish 

(Case 2) a

0.148 0.060 0.0002 >0.005

Saltwater Fish 

(Case 1) a

>372 Not 

available

0.343 0.147 <0.0009 Not calculated

Saltwater Fish 

(Case 2) a

0.148 0.060 <0.0004

a Aquatic EECs (TM+bound residue) derived according to “Case 1” are based on the maximum allowable application rate 

(0.02 lb ai/A), regardless of seeding rate necessary to achieve this application rate (Table 15). Aquatic EECs derived 

according to “Case 2” are based on the maximum allowable seed treatment rates (i.e., mg ai/100 kg seed) and the realistic 

estimate of seeding rates specific to the crop or crop group (Table 16).

b Toxicity reference values from Error! Reference source not found.Table 19.

A cumulative frequency distribution of acute RQs for fish derived using each crop exposure 
85

scenario is shown in Figure 9 and displayed relative to risk to acute listed (0.05) and non-listed 

(0.5) species LOCs. It can be readily seen from this figure that aquatic RQs are 2-3 orders of 

magnitude below the acute risk LOCs for freshwater fish and at least the same for saltwater fish.

 

Figure 9. Acute Risk Quotients for Freshwater Fish (top panel) and Saltwater Fish (bottom panel) 

Relative to LOCs (0.5=listed sp.; 0.05 = non-listed sp.) Downward arrows denote non-definitive 

RQs (“<” values)

A cumulative frequency distribution of chronic RQs for freshwater fish derived using each crop 

exposure scenario is shown in Figure 10 relative to the chronic risk to listed and non-listed 

speciesLOC (1.0). Since these RQs are based on a non-definitive chronic NOAEC for 

1.0E-07

1.0E-06

1.0E-05

1.0E-04

1.0E-03

1.0E-02

1.0E-01

1.0E+00

0% 20% 40% 60% 80% 100%

Risk

Q

u

otie

nt

Cumulative Frequency

FW Fish (Acute) 

Case 1 Case 2

Non-listed Sp. LOC Lised Sp. LOC

1.0E-07

1.0E-06

1.0E-05

1.0E-04

1.0E-03

1.0E-02

1.0E-01

1.0E+00

0% 20% 40% 60% 80% 100%

Risk

Q

u

otie

nt

Cumulative Frequency

SW Fish (Acute) 

Case 1 Case 2

Non-listed Sp. LOC Lised Sp. LOC
86

freshwater fish (<12 ug ai/L), only the lower bound of the chronic RQ can be described with 

certainty (i.e., that it is greater than the value shown). Therefore, the actual RQ could 

conceivably exceed the chronic risk LOC depending on the value of the definitive NOAEC. This 

is denoted by the upward facing arrows on Figure 10. Although such non-definitive (“greater 

than”) RQs are not traditionally determined in EFED ecological risk assessments, they are shown 

here because the lower bound of these chronic RQs (i.e., RQs that are based on the LOAEC of 

12 ug ai/L) are at least two orders of magnitude below the chronic risk LOC. The likelihood of 

the actual NOAEC occurring two orders of magnitude below the LOAEC of 12 ug ai/L is 

discussed in Section IV.B (Risk Description).

Figure 10. Chronic Risk Quotients for Freshwater Fish Relative to LOC (1.0). Upward arrows 

denote non-definitive RQs (“>” values).

Aquatic Invertebrates-Water Column

Maximum acute and chronic RQs for aquatic invertebrates are determined from the 1-in-10 year 

maximum daily and 1-in-10 year maximum 21-d average EECs and the appropriate toxicity

reference values (Table 22). The maximum acute RQs are approximately two orders of 

magnitude below the listed species acute risk LOC (0.05) for freshwater and saltwater 

invertebrates, respectively for case 1. The maximum chronic RQs are approximately two orders 

of magnitude below the chronic risk LOC for freshwater and saltwater invertebrates, 

respectively. 

Table 22. Maximum Acute and chronic risk quotients (RQs) for evaluating toxic risk of TM 

exposure to freshwater and saltwater invertebrates 

Organism

EC50

(μg a.i./L)b NOAEC

(μg a.i./L) b

EEC

Peak

(μg a.i./L)

EEC

21-Day

(μg a.i./L)

Acute

RQ

(peak 

EEC/LC50)

Chronic

RQ

(21-day 

EEC/NOAEC)

1.0E-06

1.0E-05

1.0E-04

1.0E-03

1.0E-02

1.0E-01

1.0E+00

0% 20% 40% 60% 80% 100%

Risk

Q

u

otie

nt

Cumulative Frequency

FW Fish (Chronic) 

Case 1 Case 2 Chronic LOC = 1
87

Table 22. Maximum Acute and chronic risk quotients (RQs) for evaluating toxic risk of TM 

exposure to freshwater and saltwater invertebrates 

Freshwater Inverts. (Case 

1) a

700 26 0.344 0.209 0.0005 0.008

Freshwater Inverts. (Case 

2) a

0.148 0.093 0.0002 0.004

Saltwater Inverts. (Case 

1) a

210 3.9 0.344 0.209 0.0016 0.05

Saltwater Inverts. (Case 

2) a

0.148 0.093 0.0007 0.024

a Aquatic EECs (TM+bound residue) derived according to “Case 1” are based on the maximum allowable application rate (0.02 

lb ai/A), regardless of seeding rate necessary to achieve this application rate (Table 15). Aquatic EECs derived according to 

“Case 2” are based on the maximum allowable seed treatment rates (i.e., mg ai/100 kg seed) and the realistic estimate of seeding 

rates specific to the crop or crop group (Table 16).

b Toxicity reference values from Error! Reference source not found.Table 19.

A cumulative frequency distribution of acute and chronic RQs for aquatic invertebrates derived 

using each crop exposure scenario is shown in Figure 11 and Figure 12, respectively. Acute RQs 

are below the acute risk to listed species LOC (0.05) by approximately two orders of magnitude 

for freshwater and saltwater invertebrates. Chronic RQs for aquatic invertebrates are at least two 

orders of magnitude below the chronic risk LOC (1.0) for freshwater invertebrates and one order 

of magnitude for saltwater invertebrates. 
88

Figure 11. Acute Risk Quotients for Freshwater (top panel) and Saltwater Invertebrates (bottom 

panel) Relative to Acute Risk LOCs (0.05 and 0.5).

1.0E-07

1.0E-06

1.0E-05

1.0E-04

1.0E-03

1.0E-02

1.0E-01

1.0E+00

0% 20% 40% 60% 80% 100%

Risk

Q

u

otie

nt

Cumulative Frequency

FW Invert. (Acute)

Case 1 Case 2

Non-listed Sp. LOC Lised Sp. LOC

1.0E-06

1.0E-05

1.0E-04

1.0E-03

1.0E-02

1.0E-01

1.0E+00

0% 20% 40% 60% 80% 100%

Risk

Q

u

otie

nt

Cumulative Frequency

SW Invert. (Acute)

Case 1 Case 2

Non-listed Sp. LOC Lised Sp. LOC
89

Figure 12. Chronic Risk Quotients for Freshwater (top panel) and Saltwater Invertebrates (bottom 

panel) Relative to the LOC (1.0).

b. Sediment Exposure: Acute and Chronic Risk to Benthic 

Invertebrates

Comparisons of EECs and sediment toxicity endpoints are provided below to supplement risk 

estimation to water column organisms. The evaluation of risk to the benthic organisms was 

1.0E-06

1.0E-05

1.0E-04

1.0E-03

1.0E-02

1.0E-01

1.0E+00

0% 20% 40% 60% 80% 100%

Risk

Q

u

otie

nt

Cumulative Frequency

FW Invert. (Chronic) 

Case 1 Case 2 Chronic LOC=1.0

1.0E-05

1.0E-04

1.0E-03

1.0E-02

1.0E-01

1.0E+00

0% 20% 40% 60% 80% 100%

Risk

Q

u

otie

nt

Cumulative Frequency

SW Invert. (Chronic) 

Case 1 Case 2 Chronic LOC=1.0
90

approached by assuming equilibrium partitioning TM between the sediment and the pore water . 

Risk to benthic organisms was assessed using two approaches: (1) EECs for sediment were 

model-generated (PRZM/EXAMS) and compared to the toxicity value (NOAEC) as reported for 

sediment exposure in the sediment toxicity tests (normalized to organic carbon) and (2) EECs for 

pore water were model-generated (PRZM/EXAMS) and compared to the toxicity value 

(NOAEC) as reported for pore water in the sediment toxicity tests. 

Results from the comparison of the maximum overall sediment EECs for TM to the various pore 

water NOAECs are shown in Table 23. Comparison of pore water EECs and NOAECs indicate 

that pore water exposure to TM is three to four orders of magnitude below levels that affect 

growth, emergence and survival of benthic invertebrates. On the basis of sediment concentrations 

normalized to organic carbon, RQs are two to three orders of magnitude below adverse effect 

levels in freshwater and saltwater benthic invertebrates.

Table 23. Subchronic and Chronic Risk Quotients for evaluating toxic risk of TM exposure to 

freshwater and estuarine/marine benthic invertebrates. 

Organism

NOAEC a, 

(μg a.i./kg

OC)

NOAEC (μg 

a.i./L pore 

water)

Sediment 

EEC b

(μg a.i./ kg 

OC)

Pore Water 

EEC

(μg a.i./L pore 

water)

OCNormalized 

Sediment

RQ

Pore water

RQ

FW Midge, 

C. riparius 

(28-d)

7,700 13

418

0.061 0.05 0.005

SW Amphipod,

L. plumulosus

(10-d)

81,000 380 0.061 0.005 0.0002

a Normalized to sediment organic carbon based on %TOC reported in the studies

b Normalized to sediment organic carbon based on 4% default sediment TOC used in PRZM/EXAMS 

c. Aquatic Plants 

Risk quotients for listed and non-listed aquatic plants were calculated for the modeled crop use 

with the highest estimated peak EECs (FL carrot for Case 1 and GA onion for Case 2; Table 24). 

No data were submitted on the effects of TM on other non-vascular plants (e.g., freshwater and 

saltwater diatoms, blue green algae) or aquatic vascular plants (e.g., duckweed) so RQs were not 

calculated for these taxa. For both Case 1 and Case 2, RQ values for both listed and non-listed 

aquatic non-vascular plants were orders of magnitude below the risk to listed and non-listed 

species LOCs.
91

Table 24. Acute RQs for non-vascular aquatic plants exposed to TM. 

Plant Type EC50

(ug ai/L) a

NOAEC 

(ug ai/L) a

Peak Water 

Column EEC

Non-Listed Species 

RQ (EEC/EC50)

Listed Species RQ

(EEC/NOAEC)

Non-vascular plants 

(Case 1)

780 180

0.344 0.0004 0.002

Non-vascular plants 

(Case 2) 0.148 0.0002 0.0008

a

For freshwater green algae (Pseudokircheriella subcapitata) the EC50 = 780 ug a.i./L and NOAEC = 180 ug a.i./L (MRID 

48737506) 

2. Non-target Terrestrial Animals 

As described in Section III.B.3, the T-REX model (v. 1.5, March 2012) was used in this 

assessment for estimating direct exposure of birds and mammals to TM via consumption of 

treated seeds. Exposure from the consumption of consumption of treated seed is calculated two 

ways: 

Exposure Method #1 is based on the TM concentration in seed (mg ai/kg seed) for 

comparing with acute and chronic dose- and dietary-based toxicity endpoints, and 

Exposure Method #2 is based on the mg ai/A for estimating LD50/ft2. 

a. Birds (Terrestrial Feeding) 

Using these two methods, acute RQs are calculated for different size classes of birds (Table 25). 

None of the acute RQs exceed the risk to listed species LOC of 0.1, indicating a low potential for 

acute adverse effects to birds (a surrogate for terrestrial-phase amphibians and reptiles). Since 

all acute toxicity endpoints for birds were non-definitive values, the lowest acute avian toxicity

endpoint was selected for RQ derivation (14-d LD50>2,000 mg ai/kg bw for the zebra finch). 

Therefore, a definitive acute RQ cannot be determined; however, a non-definitive (“less than”) 

acute RQ can be determined which defines a value which the RQ is below. 

Table 25. Acute Avian RQs for Proposed TM Seed Treatment Uses

Crop Animal Size

Avian Nagy Dose

(mg ai/kg-bw/day) a

Adjusted LD50

(mg ai/kgbw/day) b

Acute 

Dosebased RQ c

Acute 

LD50/ ft2 d

Root Vegetables 

(CG1A) &

Cotton e

Small (20g) 124 2,159 <0.06 <0.01

Medium (100g) 70.4 2,749 <0.03 <0.01

Large (1000g) 31.5 3,883 <0.01 <0.01

All Other Crops e Small (20g) 24.7 2,159 <0.01 <0.01

Medium (100g) 14.1 2,749 <0.01 <0.01

Large (1000g) 6.30 3,883 <0.01 <0.01
92

Table 25. Acute Avian RQs for Proposed TM Seed Treatment Uses

Crop Animal Size

Avian Nagy Dose

(mg ai/kg-bw/day) a

Adjusted LD50

(mg ai/kgbw/day) b

Acute 

Dosebased RQ c

Acute 

LD50/ ft2 d

a

based on maximum allowable seed treatment rate for TM (Table 18)

b

Avian LD50 values scaled according to body weight (unadjusted LD50 >2000 mg ai/kg bw based on finch; Table 20)

c

Acute RQ based on the ratio of the estimated dose to the body weight-adjusted LD50.

d

LD50/ft

2

based on maximum label application rate of 0.02 lb ai/A (=0.21 mg ai/ft2) divided by the body weight adjusted LD50

values

e See Table 3 for description of crop groups and seed treatment rates.

Chronic risks to birds are estimated by comparing the allowable maximum seed treatment rates on the 

proposed TM label (488 mg ai/kg seed for Root Vegetables (CG1A) & Cotton and 97.7 mg ai/kg seed for 

all other uses) with the avian chronic NOAEC (500 mg ai/kg diet for mallard; MRID 40190202). The 

resulting chronic RQs are 0.98 and 0.20 respectively. For the higher allowable seed treatment rate for 

root vegetables and cotton, the predicted exposure is essentially equivalent to the chronic NOAEC 

resulting in a RQ of 1.0.

b. Mammals (Terrestrial Feeding)

Using these two methods described previously for birds, acute RQs are calculated for different 

size classes of mammals (Table 26). None of the acute RQs exceed the risk to listed species 

LOC of 0.1, indicating a low potential for acute adverse effects to mammals from direct 

consumption of TM-treated seeds. 

Table 26. Acute Mammalian RQs for Proposed TM Seed Treatment Uses

Crop Animal Size

Mammalian Nagy 

Dose

(mg ai/kg-bw/day) a

Adjusted LD50

(mg ai/kgbw/day) b

Acute 

Dosebased RQ c

Acute 

LD50/ ft2 d

Root Vegetables 

(CG1A) &

Cotton e

Small (15g) 103 3,761 0.03 <0.01

Medium (35g) 71.4 3,043 0.02 <0.01

Large (1000g) 16.6 1,316 0.01 <0.01

All Other Crops eSmall (15g) 20.7 3,761 0.01 <0.01

Medium (35g) 14.3 3,043 <0.01 <0.01

Large (1000g) 3.31 1,316 <0.01 <0.01

a

based on maximum allowable seed treatment rate for TM (Table 18)

b Mammalian LD50 values scaled according to body weight (unadjusted LD50 =3500 mg ai/kg bw for mouse; Table 20)

c

Acute RQ based on the ratio of the estimated dose to the body weight adjusted LD50.

d

LD50 /ft2 based on maximum label application rate of 0.02 lb ai/A (=0.21 mg ai/ft2) divided by the body weight adjusted LD50

values

e See Table 3 for description of crop groups and seed treatment rates.

Chronic risks to mammals from consumption of seeds treated with TM are based on the body weight 

adjusted NOAEL of 12.2 mg ai/kg bw determined for the mouse compared to the estimated dose for 
93

different size classes (Table 27). Chronic RQs range from 0.72 to 7.9, thus indicating a potential for 

chronic risks to mammalian wildlife consuming seeds treated with TM for all but the largest mammalian 

size class (1000g) with “other crops” using the lower seed treatment rate (97.7 mg ai/kg seed).

Table 27. Chronic Mammalian RQs for Proposed TM Seed Treatment Uses

Crop Animal Size

Mammalian Nagy 

Dose

(mg ai/kg-bw/day) a

Adjusted NOAEL

(mg ai/kg-bw/day) b

Chronic Dosebased RQ c

Root Vegetables 

(CG1A) &

Cotton d

Small (15g) 103 13.1 7.9

Medium (35g) 71.4 10.6 6.7

Large (1000g) 16.6 4.6 3.6

All Other Crops dSmall (15g) 20.7 13.1 1.6

Medium (35g) 14.3 10.6 1.4

Large (1000g) 3.31 4.6 0.72

a

Based on maximum allowable seed treatment rate for TM (Table 18)

b Mammalian NOAEL values scaled according to body weight (unadjusted NOAEL =12.2 mg ai/kg bw for mouse; Table 20).

c

Chronic RQ based on the ratio of the estimated dose to the body weight-adjusted LD50.

d See Table 3 for description of crop groups and seed treatment rates.

RQ values in bold indicate exceed the chronic risk LOC of 1.0.

3. Piscivorous Birds and Mammals

As discussed in the Section III, TM is hydrophobic with a measured log Kow of 3.8. Therefore, 

the potential exists for TM and its bound residues to bioaccumulate in aquatic organisms that 

serve as dietary sources for terrestrial wildlife. In this section, risks to piscivorous birds and 

mammals are described that result from consumption of aquatic prey that have been predicted to 

bioaccumulate TM and its associated degradates of concern.

a. Predicted Residues in Fish 

Two approaches were used to predict residues of TM in aquatic organisms. The first approach 

relied on the KABAM model (v. 1.0) which uses a food web bioaccumulation model to estimate 

chemical concentrations in tissues of aquatic organisms. The technical basis and 

parameterization of this model is summarized in USEPA 200912. The primary chemical-specific 

inputs to the KABAM model are Kow, Koc, surface water EEC, and pore water EEC. Since the 

expected time to steady state in fish tissue is short (< 0.5 days based on bioconcentration 

studies), peak EECs were used as input to KABAM. Peak surface water and pore water EECs 

(0.34 and 0.07 ug ai/L, respectively) were obtained from Florida Carrot scenario (Table 15) 

which produced the highest surface water EECs.

 

12 Available at: http://www.epa.gov/oppefed1/models/water/#KABAM
94

The second approach used to predict TM in aquatic organisms involved the use of the measured 

bioconcentration factor (BCF). Specifically, a whole-fish BCF of 506 L/kg wet wt was used in 

conjunction with the maximum peak EEC in surface water (0.34 ug ai/L) to estimate TM in fish 

tissue. This whole body fish BCF represents concentrations of parent TM and any degradate that 

formed during the exposure portion of the BCF study. 

Predicted residues in aquatic organisms using both approaches (KABAM and measured BCF) 

are provided in

Table 28. Notably, KABAM estimates similar BCF values as that measured for TM (200-300 

vs. 506 L/kg wet wt.) and as a result, predicted concentrations in fish tissue are similar. This 

finding provides evidence that the assumptions used in the KABAM modeling (no 

biotransformation) are reasonable. It is also worthy to note that KABAM includes uptake from 

the aquatic diet as well as through respiration, while the measured BCF includes uptake only

through respiration. For chemicals with log Kow <4, dietary uptake is not predicted to be a 

significant route of exposure to top trophic level fish. Again, the similarity in KABAMpredicted BCFs to the measured BCF supports the conclusion that dietary uptake is not an 

important route of exposure to fish. 

Table 28. Predicted residues of TM in aquatic organisms using KABAM and BCF 

Methods.

Peak EECs in surface 

water (pore water); ug 

ai/L

Organism Type

(% lipid)

Predicted TM in 

Tissue (ug ai/kg 

ww)

Predicted BCF 

(measured BCF) 

(L/kg ww)

KABAM-Based Modeling Method

0.34 (0.07) Phytoplankton (2%) 100 304

Zooplankton (3%) 74 217

Benthic Invertebrates (3%) 77 226

Filter Feeders (2%) 51 149

Small Fish (4%) 100 290

Medium Fish (4%) 101 290

Large Fish (4%) 108 304

BCF-Based Modeling Method

0.34 Fish (~4%) 174 (506)

Based on the predicted residues in aquatic organisms, feeding and respiration rates for aquatic 

organisms, and toxicity values for birds and mammals, risks to piscivorous wildlife were 

calculated (Table 29). Not surprisingly given the low aquatic EECs and low toxicity of TM to 

terrestrial wildlife, acute and chronic RQ values are well below levels of concern.

Table 29. Calculation of RQ values for mammals and birds consuming fish contaminated by 
95

Tolclofos Methyl.

Wildlife Species

Acute RQs* Chronic RQs**

Dose Based Dietary 

Based Dose Based Dietary Based

Mammalian

fog/water shrew 0.000 N/A 0.004 0.001

rice rat/star-nosed mole 0.000 N/A 0.005 0.001

small mink 0.000 N/A 0.006 0.001

large mink 0.000 N/A 0.007 0.001

small river otter 0.000 N/A 0.008 0.001

large river otter 0.000 N/A 0.009 0.001

Avian

sandpipers 0.000 0.000 N/A 0.000

cranes 0.000 0.000 N/A 0.000

rails 0.000 0.000 N/A 0.000

herons 0.000 0.000 N/A 0.000

small osprey 0.000 0.000 N/A 0.000

white pelican 0.000 0.000 N/A 0.000

* based on acute LD50 values of >2000 mg ai/kg bw for birds (zebra finch) and 3500 mg ai/kg bw for mammals 

(mouse)

** based on chronic NOAEC of 500 ppm in diet for birds (mallard) and 100 ppm for mammals (mouse)

4. Non-target Beneficial Insects

The Agency does not currently conduct quantitative risk assessments for non-target beneficial 

insects (e.g., honeybee). Rather, the potential exposure of honeybees to pesticides is assessed 

qualitatively based on laboratory data and if available, field data. For the proposed seed 

treatment uses of TM, the usual routes of exposure such as spray drift are not applicable. 

Furthermore, TM is considered a non-systemic fungicide thus reducing potential exposure via 

transport within the plant to pollen and nectar. However, there is evidence of potential exposure 

to other pesticides used for seed treatment via drift of dust from abraded treated seed coat 

(Krupke et al. 2012). Conceptually, this route of exposure may also exist for TM; however, no 

information specific to TM or this proposed use is available to quantify this exposure route. It is 

also noted that TM is classified as practically non-toxic to young adult honeybees (acute contact 

LD50 >100 ug ai/bee) and has a very low application rate (0.02 lb ai/A). Therefore, while 

conceptually a potential route of exposure of TM-treated seeds exists for honeybees and other 

insect pollinators, the very low toxicity of TM to honeybee and its low application rate suggest 

that this route of exposure is not likely to be a concern.

5. Non-target Terrestrial Plants
96

No data were submitted on the effects of TM on non-target terrestrial plants. Therefore, RQs 

were not derived and risks to terrestrial plants could not be quantified. As discussed above with 

honeybee, spray drift and runoff are not considered dominant routes of exposure of TM to 

terrestrial plants. However, there is a potential for exposure of terrestrial plants adjacent to 

treated fields via drift of abraded seed coating dust. Additional discussion of the potential risks 

of TM is provided in Section IV.B (Risk Description). 

B. Risk Description - Interpretation of Direct Effects 

In risk description, the results from the risk estimation are interpreted and synthesized into 

overall risk conclusions. When available, other lines of evidence are considered for 

characterizing ecological risk (e.g., monitoring data, ecological incident reports, refined exposure 

and effects modeling, data for structurally similar pesticides, etc.). In the case of TM, no 

information is available on monitored concentrations in the environment or ecological incident 

reports because it is a new pesticide. The risk description also contains a discussion of relevant 

sources of uncertainty in the risk assessment and sensitivity of the risk assessment findings to 

important methodological assumptions. Those uncertainties that are specific to certain 

taxonomic groups are discussed in the following sections. Those uncertainties that are generic to 

this assessment (i.e., extending across taxonomic groups) are described in Section IV.C. 

1. Risks to Aquatic Animals 

a. Potential for Acutely Toxic Exposures 

Fish and Aquatic Invertebrates

The previous risk estimation section indicates a low potential for acutely toxic exposures to 

aquatic animals from the proposed seed treatment uses of TM. Even with the most conservative 

exposure assumptions considered (Case 1), acute RQs calculated for fish and aquatic 

invertebrates are at least two orders of magnitude below the LOC for listed species (0.05) and 

three orders of magnitude below the LOC for non-listed species (0.5; Table 21, Table 22, Figure 

9, Figure 11). This low potential for acute effects to aquatic animals is determined by the limited 

exposure to aquatic systems (low application rate of 0.02 lb ai/A and soil incorporation of treated 

seeds) and low acute toxicity of TM to aquatic animals. Regarding the latter, available data 

indicate TM is acutely toxic to aquatic animals near its reported solubility in water (700 ug ai/L) 

which is much greater than the maximum EEC predicted in surface water (0.344 ug ai/L). It is 

further noted that the difference in acute RQs derived using the two exposure methods (Case 1 

and Case 2) was relatively minor (about a factor of two) and therefore, does not impact these risk 

assessment conclusions. Available information also indicates the major degradate (DM-TM) is 

practically non-toxic to D. magna and rainbow trout, thus supporting the exclusion of this 

degradate from the aquatic EECs (Error! Reference source not found.Table 19).
97

It is noted here that the EC50 reported for D. magna (2.4 mg ai/L; MRID 00156120) is well 

above the reported solubility in water (0.7 mg ai/L). Although a co-solvent was used in this 

study and no precipitates were reported, it is not clear that observations of precipitates were 

made, and other similar studies reported precipitation problems with multiple co-solvents as 

concentrations approach the solubility limit. Therefore, because of the uncertainty regarding the 

actual bioavailability of TM in the Daphnia study, the EC50 was assumed to be at the limit of 

water solubility (0.7 mg ai/L). This assumption did not alter the risk conclusions in relation to 

the reported EC50 of 2.4 mg ai/L.

b. Potential for Chronically Toxic Exposures

Aquatic Invertebrates (Water Column)

Available data also suggest a low potential for chronic toxicity to aquatic invertebrates (water 

column dwelling) with maximum chronic RQ values ranging from 0.004 to 0.05, depending on 

exposure assessment method and taxonomic group (Table 22). 

Aquatic Invertebrates (Benthic)

For benthic-dwelling invertebrates, subchronic (10-d) and chronic RQs range from 0.0007 to 

0.005 (pore water basis). Although uncertainties were identified in two of the three submitted 

benthic invertebrate toxicity studies, these uncertainties are not likely to affect the risk 

assessment conclusions regarding benthic invertebrates. Specifically, the NOAEC of 0.013 mg 

ai/L-pore water derived for the freshwater midge (MRID 48737504) reflects a spiked overlying 

water design with no equilibration prior to testing. As a result, overlying water concentrations 

declined as TF partitioned to sediments; sediment concentrations increased substantially during 

the first two weeks of the test. Although this test design is in accordance with OECD Guideline 

#219, OSCPP draft guidelines recommend spiked sediment with equilibration prior to testing. 

Furthermore, the OECD Guideline #219 is intended to simulate a single spray drift event, 

whereas TM is expected to be transported to water primarily via erosion of TM-sorbed sediment. 

The NOAEC of 0.38 mg ai/L-pore water derived from the toxicity study with the saltwater 

amphipod, L. plumulosus, reflects a combination of dose response information from two separate 

experiments (see Section III.C) because the first experiment resulted in adverse effects at all 

treatment levels. Neither experiment determined a NOAEC that was bounded by a LOAEC, but 

in combination, a definitive NOAEC of 0.38 mg ai/L-pore water could be estimated. Therefore, 

this NOAEC is subject to uncertainty associated with using dose-response information from 

separate batches of organisms over different times. Despite the aforementioned uncertainties in 

the submitted sediment toxicity studies, the maximum pore water EEC (0.06 ug ai/L) is still 

several orders of magnitude below the available NOAECs (13 - 854 ug ai/L-pore water). Thus, 

these uncertainties are not likely to alter the conclusion of low potential risk to benthic 

invertebrates. 
98

Fish

Qualitatively, the likelihood of chronic effects to fish also appears to be low with the proposed 

seed treatment uses of TM (Table 21). However, limitations in the available chronic toxicity

data introduce some uncertainty in this risk conclusion. Specifically, no chronic data are 

available for saltwater fish and the only available study for freshwater fish (rainbow trout) 

resulted in a non-definitive NOAEC of <12 ug ai/L (MRID 42106501). For bounding purposes, 

the LOAEC of 12 ug ai/L (14% reduction in fry weight) was used to calculate a chronic RQ 

based on a maximum 1 in 10 year 60-d average EEC of 0.147 ug ai/L (Table 21). This 

calculation resulted in a chronic RQ of >0.01 using the maximum EEC derived for Case 1 and 

>0.005 for the maximum EEC derived using Case 2. The “>” sign is used to distinguish these 

RQs because the actual NOAEC is known to be below 12 ug ai/L. Obviously, such unbounded 

RQs do not enable a conclusive determination of risk (or lack thereof) to be made. However, in 

order for the chronic risk LOC to be exceeded for freshwater fish, the NOAEC would have to be 

about 0.15 ug ai/L which is about 100X below the LOAEC of 12 ug ai/L. For several reasons, 

this occurrence is considered highly unlikely. First, the original NOAEC derived from this study

was 12 ug ai/L based on comparison to the solvent controls. However, according to current 

EFED policy, comparisons should be made to negative controls which resulted in a NOAEC of 

<12 ug ai/L. Since no significant difference was detected between the solvent and negative 

controls, it is evident that the statistical determination of the NOAEC is sensitive to the type of 

controls used for comparison and their associated variance. Second, the biological responses 

associated with the LOAEC (14% reduction in fry weight 60d post-hatch; 4% reduction in fry

length, 37d post-hatch) are considered relatively modest from a biological perspective. Fry

lethality occurred at much higher concentrations (>110 ug ai/L) and reductions in egg hatching 

occurred at 200 ug ai/L. Therefore, this dose-response pattern is not suggestive of a NOAEC 

that would be two orders of magnitude below the current LOAEC of 12 ug ai/L. Rather, it is 

suggestive of a NOAEC that would be one or two dose levels below the current LOAEC.

No data are available on the effect of chronic exposures of saltwater fish to TM. However, the 

available toxicity data do not suggest that saltwater fish are any more sensitive compared to 

freshwater fish (Error! Reference source not found.Table 19). Specifically, The acute LC50 for 

saltwater fish (0.372 mg ai/L for sheepshead minnow) is similar to the range of LC50 values for 

freshwater fish (0.69 to 3.2 mg ai/L). Furthermore, given the low aquatic EECs associated with 

the proposed seed treatment uses of TM, the chronic NOAEC for saltwater fish would have to be 

100X lower than the current LOAEC for freshwater fish (12 ug ai/L). Although theoretically 

possible, the available data suggest that it is unlikely for saltwater fish to be so much more 

chronically sensitive to TM to warrant chronic risk concerns, hence, the requirement for chronic 

toxicity data for saltwater fish was recently waived for the proposed seed treatment uses 

(D393184).

Aquatic Plants

Based on the only available data for green algae (P. subcapitata), risk quotients are 1000X below 

aquatic plant risk LOCs (1.0) for the modeled crop use with the highest estimated exposure 

values (FL carrot for Case 1 and GA onion for Case 2; Table 24). However, no data were 
99

available for other taxa of non-vascular aquatic plants (diatoms, blue-green algae) or vascular 

aquatic plants, thereby introducing uncertainty in the risk conclusions for aquatic plants.

In order to characterize the uncertainty associated with the lack of toxicity data for aquatic 

plants, relevant toxicity endpoints for aquatic plants tested with other phosphorothionate

organophosphate pesticides were evaluated. The phosphorothionate class of OP pesticides was 

chosen since it has the potential to form oxon degradates of greater toxicity, similar to TM. 

Available data in OPP/EFED’s Ecotoxicity database were identified, screened for acceptable or 

supplemental studies. The vast majority data were non-definitive (“>”) values, indicating overall 

low phytotoxicity as would be expected given the MOA of OP insecticides. Among these data, 

the most sensitive, definitive toxicity values were selected for a given chemical/species 

combination (Table 30). Data on aquatic plants were limited for this type of OP pesticides. 

However, the maximum peak aquatic EEC for TM (0.344 ug ai/L) is still three orders of 

magnitude below the most sensitive EC50 (140 ug ai/L for bensulide) and two orders of 

magnitude below the most sensitive NOAEC (42 ug ai/L for bensulide). Although not 

conclusive, this comparison, combined with the mode of action of TM, suggests that the 

proposed seed treatment uses of TM have a low potential to result in risk concerns for aquatic 

plants.

Table 30. Aquatic Plant Toxicity Data Obtained For Other Phosphorothionate Organophosphate 

Pesticides

Chemical Species EC50

(mg ai/L)

NOAEC 

(mg ai/L) MRID

Bensulide Duckweed

(Lemna gibba) 0.14 0.042 44720406

Dimethoate Green Algae (P. 

subcapitata)

110 19.7 47784001

Methyl parathion Marine diatom

(Skeletonema costatum) 5.3 N.R. 40228401

Phorate Marine diatom

(S. costatum) 1.3 N.R. 40228401

Diazinon Green Algae (P. 

subcapitata)

3.7 N.R. 40509806

Chlorpyrifos Marine algae

(Isochrysis galbana)

0.14 N.R. 40228401

Source: USEPA EFED Ecotoxicity Database (accessed 9-23-3011)

2. Risks to Terrestrial Animals 

a. Potential for Acutely Toxic Exposures 

Birds and Mammals

Acute risk to birds are considered low as indicated by acute RQs of <0.01 to <0.06 (Table 25) 

which are all below the acute risk LOC for listed species (0.1). These RQ values are based on 
100

the most sensitive LD50 value available (LD50>2,000 mg ai/kg bw for zebra finch; Table 20). 

Only upper bound (non-definitive) RQs could be determined because no treatment related 

mortality occurred at the highest dose tested in the available toxicity studies (i.e., non-definitive 

LD50 values). A review of these studies for sublethal effects also indicates no treatment-related 

effects on endpoints such as food consumption, body weight and behavior.

Similar to birds, acute risks to mammals are considered low as indicated by acute RQs of <0.01 

to 0.03 (Table 26). These RQ values are based the most sensitive acute toxicity endpoint

available (LD50=3,500 mg ai/kg bw for mouse; Table 20). Clinical signs of toxicity occurred at 

>1,500 mg ai/kg bw for mouse and included ataxia, irregular respiration, decreased motor 

activity. Clinical signs of toxicity in rats occurred at >3,500 mg ai/kg bw. These levels are all an 

order of magnitude or more above the estimated ingested dose associated with the proposed TM 

uses (3.3-103 mg ai/kg bw). Risk estimation also indicates that piscivorous birds and mammals 

are not likely to encounter acutely toxic exposures to TM (Table 29).

b. Potential for Chronically Toxic Exposures

Birds

Chronic dietary-based RQs for birds (0.20-0.98; Section IV.A.2) indicate chronically toxic 

exposure to TM treated seeds may be approached with the proposed uses on root vegetables and 

cotton, where the highest seed treatment rate is used. These chronic RQs are based on a dietary

NOAEL of 500 ppm for mallard duck (MRID 40190202) based on reproductive effects 

(reductions in # eggs set, viable embryos, hatching success) which occurred at the LOAEL of 

2,500 ppm in the diet. Very similar results were obtained from a chronic study with bobwhite 

quail in terms of the NOAEL (500 ppm) and LOAEL (2,500 ppm). The wide dose spacing used 

in these two studies (a factor of 5 between the NOAEL and LOAEL) introduces some 

uncertainty as to the potential for chronic toxicity to birds with an effective chronic RQ of 1.0. It 

is also noted that the potential for chronic risks to birds is also sensitive to the assumption that 

the avian diet is comprised of 100% of seeds treated with TM (488 mg ai/kg seed). Some factors 

that would likely lead to lower chronic risks include the soil incorporation of TM treated seeds 

(broadcast applications are not allowable) and the availability of alternative forage items. 

Furthermore, any additional exposure of birds to TM via abraded seed coating dust would also 

increase the potential for chronic risks. 

Risk estimation also indicates that piscivorous birds are not likely to encounter chronically toxic 

exposures to TM (Table 29).

Mammals 

Chronic risks associated with mammalian consumption of TM treated seeds are indicated in this 

assessment, with chronic RQs ranging from 0.7 to 7.9; Table 27). Chronic risks are identified for 

all size classes of mammals considered (15, 35 and 1000g) with the highest TM seed treatment 
101

rate for root vegetables and cotton (488 mg ai/kg seed). With the lower seed treatment rate (97.7 

mg ai/kg seed), chronic risk concerns are identified for the small and medium size mammals, but 

not large (1000 g) mammals. These RQ values are based on a NOAEL of 100 ppm in the diet 

(12.2 mg ai/kg bw) identified for mouse (MRID 00156137). The LOAEL from this study was 

3000 ppm in the diet (503 mg ai/kg bw) based on reduced body weighs of males and females. A 

reduction in plasma cholinesterase was also observed at 30 ppm for female mice. As with the 

chronic avian toxicity study, the wide dose spacing between the NOAEL (100 ppm) and LOAEL 

(3000 ppm) introduces uncertainty in the risk assessment conclusions because the actual NOAEL 

may be anywhere between 100 and 3000 ppm and narrower dose spacing been used. For other 

mammalian taxa (rat, dog), developmental and subchronic NOAELs are 300 and 600 ppm 

respectively, suggesting that the potential exists for chronic risk to other mammalian taxa as 

well. As noted with the chronic avian risk characterization, the incorporation of TM-treated 

seeds in soil as required by the label would lead to reductions in chronic risks to mammals, 

particularly for crops with deeper minimum planting depths (e.g., corn at 3.8 cm; Table 3). 

Risk estimation also indicates that piscivorous mammals are not likely to encounter chronically 

toxic exposures to TM (Table 29).

Non-target Beneficial Insects 

Current data suggest a low potential for adverse effects of the proposed seed treatment uses of 

TM to honeybees. This low risk potential is based on the lack of spray drift from the proposed 

uses (seed treatment) and low acute toxicity to young adult bees (LD50 >100 ug ai/bee). 

Furthermore, TM is considered a non-systemic fungicide thus reducing potential exposure via 

transport within the plant to pollen and nectar. Although the conceptual model identified the 

potential for off-site transport of abraded seed coat dust during planting of TM-treated seeds, the 

very low application rate (0.02 lb ai/A) in relation to its low acute toxicity suggest this route of 

exposure is not likely to be a concern.

3. Risks to Terrestrial Plants 

No data were submitted on the effects of TM on non-target terrestrial plants. Therefore, RQs 

were not derived and risks to terrestrial plants could not be quantified. As discussed above with 

honeybees, spray drift and runoff are not considered dominant routes of exposure of TM to 

terrestrial plants. There is potential, however, for exposure of terrestrial plants adjacent to 

treated fields via drift of abraded seed coating dust.

In an effort to characterize the uncertainty associated with the lack of toxicity data for terrestrial 

plants and its effect on the risk conclusions, terrestrial plant toxicity data for other 

phosphorothionate OP pesticides were reviewed. The phosphorothionate class of OP pesticides 

was chosen since it has the potential to form oxon degradates of greater toxicity, similar to TM. 

Of the 92 terrestrial plant EC25 values reported for acceptable or supplemental studies in the 

EFED Ecotoxicity database, only 25 were definitive values for three pesticide active ingredients 

(four formulations). Nearly all the remaining were “>” values indicating less than 25% effect at 
102

the highest treatment tested, suggesting that this class of pesticides is not readily toxic to 

terrestrial plants at labeled application rates.

The most sensitive definitive EC25 and NOAEL values from the aforementioned OP plant 

toxicity studies are summarized below in Table 31. Assuming that TM acts similarly on 

terrestrial plants as these other OP pesticides, it appears that its proposed use for seed treatment 

would have a low potential for risk to terrestrial plants, even if plants were exposed at maximum 

labeled application rate (0.02 lb ai/A). In other words, TM would have to be about 50 times 

more toxic than the most toxic OP for which we have data in order for risks concerns to nonlisted terrestrial plants to be realized. For listed terrestrial plant species, TM would have to be 20 

times more toxic than the most toxic OP for which we currently have data in order for risk 

concerns to be identified. 

Table 31. Terrestrial Plant Toxicity Data Obtained For Other Phosphorothionate

Organophosphate Pesticides

Chemical Species EC25

(lb ai/A)

NOAEL 

(lb ai/A) MRID

Bensulide Cucumber

(Cucumis sativus) 1.3 0.38 44746301(v.v.)

Dimethoate (400 

Formulation)

Tomato

(Lycopersicon 

esculentum)

0.91 0.91 47709702

(s.e.)

Dimethoate Corn

(Zea mays) 0.98 0.98 47709702

(s.e.)

Diazinon Cucumber

(Cucumis sativus) 3.2 3.2 40803002

(s.e.)

Source: USEPA EFED Ecotoxicity Database (accessed 9-23-3011); v.v.=vegetative vigor 

study; s.e. = seeding emergence study.

4. Review of Incident Data 

Because TM has not been previously approved for use in the United States, there are no incident 

reports for this chemical.

5. Threatened and Endangered Species Concerns 

For listed species assessment purposes, the action area is considered to be the area affected 

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

action. At the initial screening-level, the risk assessment considers broadly described taxonomic 

groups and so conservatively assumes that list species within those broad groups are collocated 

within the pesticide treatment area. This means that terrestrial plants and wildlife are assumed to 

be located on or adjacent to the treated site and aquatic organisms are assumed to be located in a 

surface water body adjacent to the treated site. The assessment also assumes that the listed 

species are located within an assumed area which has the relatively highest potential exposure to 

the pesticide, and that exposures are likely to decrease with distance from the treated area. 

If the assumptions associated with the screening-level action area result in RQs that are below 
103

the listed species LOCs, “no effect,” determination conclusion may be made with respect to 

listed species in that taxa (for direct effects), and no further refinement of the action is necessary. 

Furthermore, RQs below the listed species LOCs for a given taxonomic group indicate no 

concern for indirect effects upon listed species that depend upon the taxonomic group as a 

resource. However, in situations where the screening assumptions lead to RQs in excess of the 

risk to listed species LOCs for a given taxonomic group, a potential “may affect,” conclusion 

exists and may be associated with direct effects on listed species belonging to that taxonomic 

group or may extend to indirect effects upon listed species that depend on that taxonomic group 

as a resource. In such cases, additional information on the biology of the listed species, the 

locations of these species, and the locations of use sites could be considered along with available 

information on the fate and transport properties of the pesticide to determine the extent to which 

screening assumptions regarding an action area apply to a particular listed organism. These 

subsequent refinement steps could consider how this information would impact the action area 

for a particular listed organism and may potentially include areas of exposure that are downwind 

and downstream of the pesticide use site. 

In conducting a screen for indirect effects, direct effects LOCs for each taxonomic group are 

used to make inferences concerning the potential for indirect effects upon listed species that rely 

upon non-listed organisms in these taxonomic groups as resources critical to their cycle. 

Pesticide use scenarios resulting in RQs that are below all direct effect listed species LOCs for 

all taxonomic groups assessed are considered of no concern for risks to listed species either by 

direct or indirect effects.

For TM, the potential direct effects to listed species should they co-occur with application sites 

are indicated for mammals (chronic toxicity) and birds (including terrestrial-phased amphibians 

and reptiles; chronic toxicity) based on consumption of treated seeds. Risk to listed species 

LOCs are not exceeded for any other taxonomic group assessed (aquatic animals, aquatic plants, 

non-target invertebrates). For the maximum proposed TM application rates, there may be a 

potential concern for direct effects to the following groups of organisms:

• Birds 

• Mammals

• Terrestrial-phase reptiles

• Terrestrial-phase amphibians

A spatial co-occurrence analysis would be necessary to delineate the action area. 

C. Description of Assumptions, Limitations, Uncertainties, Strengths and Data 

Gaps 

1. Exposure for All Taxa 
104

There are a number of areas of uncertainty in the aquatic and terrestrial risk assessments. The 

toxicity assessment for terrestrial and aquatic plants and animals is limited by the number of 

species tested in the available toxicity studies. Use of toxicity data on representative species 

does not provide information on the potential variability in susceptibility among species to acute 

and chronic exposures. 

For each proposed use, the risk assessment is based on the maximum application rate on the 

proposed label. The frequency at which actual uses approach these maximum scenarios is 

dependent on the resistance to the pesticide, the timing of applications, and market forces. 

Exposure and risks could be overestimated if the actual application rates, frequency of 

application, or number of applications are lower than the input parameters used for the 

conservative exposure scenario that was modeled. . 

 

2. Exposure for Aquatic Species 

This Tier II risk assessment relies on best available estimates of environmental fate and 

physicochemical properties, maximum application rate of TM, minimum planting depth of seeds, 

and maximum seeding rates. However, several uncertainties and model limitations are noted and 

should be considered in interpreting the results of this aquatic risk assessment. 

• The frequency at which actual TM uses approach the use estimates modeled is dependent 

on resistance to the insecticide, timing of applications, and market forces. In general, 

model output values represent the upper-bound estimates of concentrations that might be 

observed in surface water due to the application of TM, given available data and model 

limitations.

• Although there are uncertainties associated with using the standard PRZM/EXAMS 

runoff scenario (10-ha field draining into 20,000 m3pond with no outlet) for an aquatic 

exposure assessment, it is designed to represent pesticide exposure from an agricultural 

watershed impacting a vulnerable aquatic environment. Extrapolating the risk 

conclusions from this standard pond scenario may either underestimate or overestimate 

the potential risks.

• Major uncertainties associated with the standard runoff scenario include the physical 

construct of the watershed and representation of vulnerable aquatic environments for 

different geographic regions. The physicochemical properties (pH, redox conditions, 

etc.) of the standard farm pond are based on a Georgia farm pond. These properties are 

likely to be regionally specific because of local hydrogeological conditions. Any

alteration in water quality parameters may impact the environmental behavior of a 

pesticide. The farm pond represents a well mixed, static water body. Because the farm 

pond is a static water body (no flow through), it does not account for pesticide removal 

through flow through or water releases. The lack of flow through the farm pond provides 

an environmental condition for accumulation of persistent pesticides. The assumption of 

uniform mixing does not account for stratification due to thermoclines (e.g., seasonal 

stratification in deep water bodies). Additionally, the dimensions of the standard runoff 
105

scenario assume a watershed area to water body volume ratio of 10 ha: 20,000m3. This 

ratio is recommended to maintain a sustainable constructed pond in the Southeastern 

United States. The use of higher watershed area to water body volume ratios (as 

recommended for sustainable ponds in drier regions of the United States) may lead to 

higher pesticide concentrations when compared to the standard watershed area to water 

body volume ratio.

• The standard runoff scenario assumes uniform soils and agronomic management 

practices across the standard 10-hectare field. Soils can vary substantially across even 

small areas; this variation is not reflected in the model simulations. Additionally, the 

impact of unique soil characteristics and soil management practices (e.g., tile drainage) 

are not considered in the standard runoff scenario. The assumption of uniform site and 

management conditions is not expected to represent some site-specific conditions. 

Extrapolating the risk conclusions from the standard pond scenario to other aquatic 

habitats (e.g., marshes, streams, creeks, and shallow rivers, intermittent aquatic areas) 

may either underestimate or overestimate the potential risks in those habitats.

• For an acute risk assessment, there is only a one-day averaging time for exposure. Use of 

such a “peak” concentration, with a 1-in-10 year annual return frequency, implies that 

exposure is sufficient to elicit acute effects comparable to those observed over more 

protracted exposure periods tested in the laboratory, typically 48 to 96 hours. In the 

absence of data regarding time-to-toxic event analyses and latent responses to peak 

exposure, the degree to which risk is overestimated cannot be quantified.

3. Exposure for Terrestrial Species 

This risk assessment relies on the best available estimates of environmental fate and 

physicochemical properties, maximum application rate of TM, maximum number of 

applications, and the shortest interval between applications. However, several uncertainties and 

model limitations are noted and should be considered in interpreting the results of this terrestrial 

risk assessment. 

a. Location of Wildlife Species 

For screening terrestrial risk assessments, a generic bird or mammal is assumed to consume 

100% of its diet as treated seeds from the application site. This assumption may lead to an 

overestimation of exposure to species that do not occupy the treated field. The actual habitat 

requirements of any particular terrestrial species are not considered, and it is assumed that 

species occupy, exclusively and permanently, the treated area being modeled. This assumption 

leads to a maximum level of exposure in the risk assessment. 

b. Routes of Exposure 
106

Dietary Exposure

Screening-level risk assessments for spray applications of pesticides assume that 100% of the 

diet is relegated to single food types foraged only from treated fields. These assumptions are 

likely to be conservative for many species and will tend to overestimate potential risks when 

species are foraging on multiple sources of food (i.e., not just treated seeds). Specific to the 

proposed seed treatment use of TM, the terrestrial exposure modeling did not account for the 

required soil incorporation of seeds (broadcast application is prohibited by the label). Therefore, 

exposure is likely to be overestimated especially for seeds with greater planting depths. 

Furthermore, while the assumption of 100% diet from a treated area may be reasonable worst 

case assumption for acute exposures, this assumption is likely much less applicable to long-term 

(chronic) exposures modeled as single food types composed entirely of treated seeds. Data on the 

amount of wildlife diet composed of seeds from treated fields would be needed to reduced this 

uncertainty.

Dermal Exposure

The screening assessment does not consider TM dermal exposure to terrestrial organisms. 

The Agency is actively pursuing modeling techniques to account for dermal exposure via direct 

application of spray and by incidental contact with contaminated vegetation, soil and water.

Drinking Water Exposure 

Drinking water exposure to a pesticide active ingredient may be the result of consumption of 

surface water or consumption of the pesticide in dew or other water on the surfaces of treated 

vegetation. For pesticide active ingredients with a potential to dissolve in runoff, puddles on the 

treated field may contain the chemical. The SIP tool (version 1.0) was used to assess the 

potential for exposure concerns to birds and mammals via drinking water alone. TM’s solubility

in water (0.7 mg/L) and toxicity to avian and mammalian species are inputs for the potential 

upper-bound drinking water calculations. Because no definitive endpoints were available for 

acute oral avian studies, the highest concentration tested was used as an upper-bound estimate of 

acute toxicity (2000 mg a.i./kg bw for birds). For mammals, an LD50 of 3,500 mg/kg bw was 

used (mouse) which was the lowest acceptable LD50 value identified. Chronic NOAEL/NOAEC 

toxicity values used for birds and mammals are 500 ppm (mallard) and 12.2 mg/kg bw (mouse). 

Based on this information, TM exposure through drinking water alone does not present an acute 

or chronic exposure route of concern for mammals or birds.

c. Incidental Pesticide Releases Associated with Use 

This risk assessment is based on the assumption that the entire treatment area is subject to TM 

application at the rates specified on the label. This translates to an even seeding rate across an 

entire field. In reality, there is the potential for uneven application of TM through such plausible 

incidents as changes in calibration of application equipment, spillage, and localized releases at 
107

specific areas of the treated field that are associated with specifics of the type of application 

equipment.

4. Effects Assessment 

The data available to support the terrestrial and aquatic effects assessment for TM is incomplete. 

Data gaps, uncertainties and limitations are summarized as follows:

 Chronic effects to estuarine/marine fish and estuarine/marine invertebrates: No chronic 

data were submitted for estuarine/marine fish or estuarine/marine invertebrates. An acuteto-chronic ratio could not be calculated due to lack of available data on definitive chronic 

toxicity endpoints for freshwater fish. The expected chronic exposure of TM to aquatic 

organisms is low (maximum 60-day EEC = 0.147 μg a.i./L). The LOAEC associated with 

the freshwater chronic study is 12 ug ai/L and reflects a 14% reduction in body weight 

relative to negative controls. As described in Section IV.B, the NOAEC for saltwater 

fish would have to be nearly 100X lower than the LOAEC for freshwater fish in order for 

chronic risk concerns to be identified. Given that acute toxicity of freshwater and 

saltwater fish appear similar (albeit based on a limited data set), there is currently no 

evidence to suggest that saltwater fish would be more sensitive than freshwater fish by 

this magnitude. Based on these lines of evidence, chronic testing with estuarine/marine 

fish or estuarine/marine invertebrates is not requested at this time.

 Solubility in aquatic tests: According to the submitted fate information, TM is 

characterized by a water solubility ranging from 0.7 to 1.0 mg a.i./L. In several acute 

toxicity studies with aquatic organisms, solubility problems were either noted or 

suspected (see Section III.B) even with the use of co-solvents. Although the 

bioavailability of TM in these studies is in question when samples were not centrifuged 

and/or filtered prior to analysis, the extremely low aquatic EECs (maximum peek = 0.344 

ug ai/L) render this uncertainty less likely to affect the risk conclusions. 

 Aquatic /Terrestrial plant toxicity studies: Toxicity data were available for only 1 aquatic 

non-vascular plant (green algae) and no vascular aquatic plants. No toxicity data were 

submitted for terrestrial plants either. Based on an analysis of other OP pesticides in a 

similar class (Phosphorothionate), the need for additional data for plants was considered 

not likely to materially affect the risk assessment conclusions. 

 Oxons: Under biologically mediated degradation, oxons of TM (e.g., TMO and DMTMO) may be formed in minor amounts (< 10%). Such oxons have the potential to be 

substantially more toxic than the parent compounds. However, no data were available on 

the toxicity of these oxons. A bounding analysis was conducted to exposure the 

importance of oxon data for the proposed TM uses. Specifically, it was assumed that the 

TM aquatic EECs contain 10% oxons and that their toxicity is 100X greater than that of 

parent TM (the maximum toxicity difference observed in other oxon studies13). For risks 

 

13 Guidance for Registration Review Data Requests for Oxon Degradates of Organophosphate Insecticides (OP). 

Memo from Don Brady (Division Director). March 10, 2009
108

to aquatic organisms, the taxon/effect with the least least difference between the RQ and 

LOC is chronic risk to saltwater invertebrates; RQ =0.05, LOC=1). If one assumes the 

maximum 21-d chronic EEC (0.149 ug ai/L) is comprised of 10% oxon (0.0149 ppb) and 

that the oxon is 100X more toxic than the saltwater invertebrate toxicity reference value 

(i.e., 0.039 ppb based on mysid NOAEC of 3.9 ppb), the combined RQ of the parent and 

oxon would still be 0.4 (0.03 for parent, 0.38 for oxon) which is still less than the chronic 

LOC of 1. For terrestrial risk assessment, data on the metabolism of TM by mammals 

indicates that oxons form in vivo via hepatic metabolism. Therefore, it is likely that the 

current battery of terrestrial toxicity tests with mammals also reflect the toxicity of oxons 

to some extent. Given these lines of evidence, the uncertainty associated with lack of 

oxon toxicity data is judged to not materially affect the current risk assessment 

conclusions. However, if new uses are proposed for TM in the future, the issue of oxon 

data would need to be re-evaluated. 

a. Age Class and Sensitivity of Effects Thresholds 

It is generally recognized that test organism age may have a significant impact on the observed 

sensitivity to a toxicant. The screening risk assessment acute toxicity data for fish are collected 

on juvenile fish and aquatic invertebrate acute testing is performed on recommended immature 

age classes. Similarly, acute dietary testing with birds is also performed on juveniles, with 

mallard being 5-10 days old and quail at 10-14 days of age. 

Testing of juveniles may overestimate the toxicity of direct acting pesticides in adults. As 

juvenile organisms do not have fully developed metabolic systems, they may not possess the 

ability to transform and detoxify xenobiotics equivalent to the older/adult organism. The 

screening risk assessment has no current provisions for a generally applied method that accounts 

for this uncertainty. In so far as the available toxicity data may provide ranges of sensitivity

information with respect to age class, the risk assessment uses the most sensitive life-stage 

information as the conservative screening endpoint.

b. Lack of Effects Data for Amphibians and Reptiles 

Currently, toxicity studies on amphibians and reptiles are not required for pesticide registration. 

Since these data are lacking, the Agency uses fish as surrogates for aquatic-phase amphibians 

and birds as surrogates for terrestrial-phase amphibians and reptiles. If other species are more or 

less sensitive to TM than the surrogates, risks may be under- or overestimated, respectively. The 

Agency is not limited to a base set of surrogate toxicity information in establishing risk 

assessment conclusions. The Agency also considers toxicity data on non-standard test species 

when available. Further research is needed to determine whether, in general, reptiles and 

terrestrial-phase amphibians are suitably represented by bird species in assessing risks for TM 

and fish are an appropriate surrogate for aquatic-phase amphibians. 
109

c. Use of the Most Sensitive Species Tested 

Although the screening-level risk assessment relies on a selected toxicity endpoint from the most 

sensitive species tested, it does not necessarily mean that the selected toxicity endpoints reflect 

sensitivity of the most sensitive species existing in a given environment. The relative position of 

the most sensitive species tested in the distribution of all possible species is a function of the 

overall variability among species to a particular chemical. The relationship between the 

sensitivity of the most sensitive tested species versus wild species (including listed species) is 

unknown and a source of significant uncertainty. In addition, in the case of listed species, there is 

uncertainty regarding the relationship of the listed species' sensitivity and the most sensitive 

species tested. 
110

V. REFERENCES TO OPEN LITERATURE AND GOVERNMENT 

REPORTS

FAO, 2000. Food and Agricultural Organization of the United Nations. FAO Pesticide Disposal 

Series 8. Assessing Contamination: A reference Manual. Appendix 2. Parameters of pesticides 

that influence processes in the soil. Editorial Group, FAO Information Division: Rome.

http://www.fao.org/DOCREP/003/X2570E/X2570E00.HTM

Fungicide Resistance Action Committee. FRAC code list: Fungicides sorted by mode of action. 

2009. http://www.frac.info/frac/publication/anhang/FRAC_CODE_LIST.pdf 

Krupke CH, Hunt GJ, Eitzer BD, Andino G, Given K . 2012. Multiple Routes of Pesticide 

Exposure for Honeybees Living Near Agricultural Fields. PLoS ONE 7(1): e29268. 

doi:10.1371/journal.pone.0029268 

US EPA. 2004a. Overview of the Ecological Risk Assessment Process in the Office of Pesticide 

Programs, U.S. Environmental Protection Agency: Endangered and Threatened Species Effects 

Determinations. Office of Prevention, Pesticide, and Toxic Substances.

US EPA. 2000. Methods for Measuring the Toxicity and Bioaccumulation of SedimentAssociated Contaminants with Freshwater Invertebrates, Second Edition, EPA 600/R-99/064. 

Office of Research and Development. Washington, DC 20460.
111

APPENDIX A. ENVIRONMENTAL FATE STUDY BIBLIOGRAPHY

MRID No.

00156106 Yoshimura, J.; Mikami, N.; Matsuda, T.; et al. (1985) Degradation of the 

Fungicide Tolclofos-methyl in Soils under Aerobic, An- aerobic and Sterilized 

Conditions. Unpublished study prepared by Takarazuka Research Center, 

Sumitomo Chemical Co., Ltd. 29 p. 

00156111 Ali, S.; Cahill, W. (1985) Dissipation of Tolclofos-methyl in Soil: Project No. 

411968. Unpublished study prepared by Velsicol Chemical Corp. 15 p. 

00163641 Forbis, A.; Bunch, B. (1986) Uptake, Depuration and Bioconcentra- tion of 

[Carbon 14]-Rizolex by Bluegill Sunfish (Lepomis macro- chirus): ABC Final 

Report #33971. Unpublished study prepared by Analytical Biochemistry

Laboratories Inc. 42 p. 

00163642 Yu, C.; Guirguis, A. (1986) Metabolism of Tolclofos-methyl in Blue- gill 

Sunfish (Lepomis macrochirus): Project No. 411968: Report No. 7. 

Unpublished study prepared by Sandoz Crop Protection Corp. 15 p. 

41422902 Katagi, T.; Takahashi, N. (1988) Photolysis of Tolclofos-methyl in Water: 

Study Number: PHW 87001. Unpublished study prepared by Sumitomo 

Chemical Co., Ltd. 39 p. 

41701801 Pesselman, R. (1990) Vapor Pressure Determination of Rizolex: Final Report: 

Lab Project Number: 6001-555. Unpublished study prepar- ed by Hazleton 

Laboratories America, Inc. 32 p. 

41714701 Ekdawi, M.; Yu, C. (1990) Hydrolysis of Tolclofos-methyl: Lab Pro- ject 

Number: 480545: 1. Unpublished study prepared by Sandoz Crop Protection 

Corp. 43 p. 

42273301 Mikami, N.; Kono, A.; Matsuo, M.; et al. (1991) Adsorption and Desorption of 

?carbon 14|-Rizolex in Soils: Lab Project Number: ADS91002. Unpublished 

study prepared by Sumitomo Chemical Co., Ltd. 68 p. 

42536001 Concha, M.; Ruzo, L.; Shepler, K. (1992) Sunlight Photodegradation of Phenyl-

?carbon 14| Rizolex on Soil: Lab Project Number: 232W-1: P232W: QM-21-

0036. Unpublished study prepared by PTRL-West, Inc. 116 p. 

42703201 Itoh, K.; Mikami, N.; Matsuo, M.; et al. (1993) Aerobic Soil Metabolism of 

(carbon 14)-Rizolex: Lab Project Number: SOI91001: QM-30-0037. 

Unpublished study prepared by Sumitomo Chemical Company, Ltd. 167 p. 

42818301 Kono, A.; Mikami, N. (1993) Anaerobic Soil Metabolism of (carbon 14)-

Rizolex: Lab Project Number: SOI91003: QM-30-0038. Unpublished study

prepared by Sumitomo Chemical Co., Ltd. 152 p. 
112

43128101 Mikami, N.; Itoh, K. (1993) Anaerobic Aquatic Soil Metabolism of (carbon 14)-

Rizolex: Lab Project Number: SOI91005. Unpublished study prepared by

Sumitomo Chemical Co., Ltd. 206 p. 

48341901 Okada, Y. (2001) Henry's Law Constant for Tolclofos-Methyl. Project Number: 

201000338, HEN2001B, QP/0096. Unpublished study prepared by Sumitomo 

Chemical Co. 5 p.

48341912 Bondarenko, S. (2010) UV/Visible Absorption of Tolclofos-Methyl. Project

Number: 201000266, 37636. Unpublished study prepared by Valent U.S.A. 

Corporation. 47 p.

48341913 Bondarenko, S. (2010) Tolclofos-Methyl: Determination of n-Octanol/Water 

Partition Coefficient (Pow) by High Performance Liquid Chromatography 

(HPLC). Project Number: 201000270, 37631. Unpublished study prepared by

Valent U.S.A. Corporation. 55 p.

48341914 Concha, M. (2010) Solubility of Tolclofos-Methyl in Water. Project Number: 

200900184, 1019W/1, QP/0095. Unpublished study prepared by PTRL West, 

Inc. 53 p.

48341919 Gohre, K. (2009) V-10178: Soil Adsorption/Desorption. Project Number: 

200900665, VP/32699. Unpublished study prepared by Valent U.S.A. 

Corporation. 93 p.

48341921 Lewis, C. (2001) (Carbon 14)- Tolclofos-Methyl: Hydrolytic Stability. Project 

Number: 200900116, 333/147. Unpublished study prepared by Covance 

Laboratories, Ltd. 135 p.

48341923 Lewis, C. (1995) (Carbon 14)-Tolclofos-Methyl: Laboratory Study: Aerobic 

Degradation of Phenyl Label in Three Soils. Project Number: 200900115, 

194/84, QM/51/0042. Unpublished study prepared by Hazleton UK. 154 p.

48341924 Lewis, C. (2001) (Carbon 14)-Tolclofos-Methyl: Soil Metabolism and 

Degradation. Project Number: 200900113, 333/145, QM/0049. Unpublished 

study prepared by Covance Laboratories, Ltd. 105 p.

48341925 Kodaka, R.; Nambu, K.; Nishioka, K.; et al. (1999) Addendum Report 

Concerning the Aerobic Degradation of [(Carbon 14)-Phenyl] Tolclofos-Methyl 

in Three Soils. Project Number: 200900112, SOI9900B, QM/0046. Unpublished 

study prepared by Sumitomo Chemical Co. 11 p.

48341926 Lewis, C. (2001) (Carbon 14)-Tolclofos-Methyl: Degradation and Retention in 

Water-Sediment Systems. Project Number: 200900114, 333/146, QM/0050. 

Unpublished study prepared by Covance Laboratories, Ltd. 116 p.
113

48341916 Croucher, A. 2001. Tolclofos-methyl: validation of an analytical method for 

the determination of residues in soil. Unpublished study performed by Covance 

Laboratories Ltd., North Yorkshire, England; sponsored by Sumitomo Chemical 

Company Ltd., Hyogo, Japan; and submitted by Valent U.S.A. Corporation (pp. 

1, 1i, 10; Appendix 6, p. 42). Covance Study No.: 333/153 (p. 1). Sumitomo 

Report No.: QA-0073. Experimental start date March 12, 2001 and completion 

date May 17, 2001 (p. 5). Final report issued October 11, 2001 (p. 1).

48341918 Wolf, S. 2001. Validation of a multi-residue method for the determination of 

tolclofos-methyl in surface water. Unpublished study performed by RCC Ltd., 

Itingen, Switzerland; sponsored by Sumitomo Chemical Co., Ltd., Hyogo, 

Japan; and submitted by Valent U.S.A. Corporation (p. 3; Appendix II, p. 40). 

RCC Study No.: 835503 (p. 1). Sumitomo Report No.: QA-0076. Experimental 

start date October 4, 2001, and completion date October 19, 2001 (p. 9). Final 

report issued November 14, 2001 (p. 1).

48341917 Wolf, S. 2001. Validation of a multi-residue method for the determination of 

tolclofos-methyl in drinking water. Unpublished study performed by RCC Ltd., 

Itingen, Switzerland; sponsored by Sumitomo Chemical Co., Ltd., Hyogo, 

Japan; and submitted by Valent U.S.A. Corporation (p. 3; Appendix II, p. 40). 

RCC Study No.: 833872 (p. 1). Sumitomo Report No.: QA-0075. Experimental 

start date October 4, 2001, and completion date October 22, 2001 (p. 9). Final 

report issued November 12, 2001 (p. 1).

48842101 Green, C., 2012. Tolclofos-methyl: Determination of Tolclofos-methyl in 

Drinking Water, Laboratory Project Identification VP-38290; submitted by Valent 

U.S.A. Corporation, Valent Technical Center, 6560 Trinity Court, Dublin, 

California 94568; July 10, 2012; 30 pages., 2001.

48842102 Green, C., 2012. Tolclofos-methyl: Determination of Tolclofos-methyl in Soil, 

Laboratory Project Identification VP-38287; submitted by Valent U.S.A. 

Corporation, Valent Technical Center, 6560 Trinity Court, Dublin, California 

94568; July 10, 2012; 30 pages., 2001.

48842103 Green, C., 2012. Tolclofos-methyl: Determination of Tolclofos-methyl in Surface 

Water, Laboratory Project Identification VP-38293; submitted by Valent U.S.A. 

Corporation, Valent Technical Center, 6560 Trinity Court, Dublin, California 

94568; July 10, 2012; 30 pages., 2001.
114

APPENDIX B. ECOTOXICITY STUDY BIBLIOGRAPHY

71-1 Avian Single Dose Oral Toxicity

MRID Citation Reference

156112 Roberts, N.; Hakin, B. (1981) The Acute Oral Toxicity (LD50) of S-3349 to the 

Mallard Duck: HRC Rept. No. SMO/137/81739. Unpub- lished study prepared 

by Huntingdon Research Centre. 14 p. 

156113 Roberts, N.; Hakin, B. (1982) The Acute Oral Toxicity (LD50) of S-3349 to the 

Bobwhite Quail: HRC Rept. No. SMO 138/81880. Un- published study prepared 

by Huntingdon Research Centre. 15 p. 

156114 Roberts, N.; Hakin, B. (1981) The Acute Oral Toxicity (LD50) of S-3349 to the 

Ring-necked Pheasant: HRC Rept. No. SMO/135/81740. Unpublished study

prepared by Huntingdon Research Centre. 15 p. 

71-2 Avian Dietary Toxicity

MRID Citation Reference

156115 Beavers, J. (1985) Technical Rizolex: A Dietary LC50 Study with the Mallard: 

Final Report: Project No. 107-207. Unpublished study prepared by Wildlife 

International Ltd. 16 p. 

156116 Beavers, J. (1985) Technical Rizolex: A Dietary LC50 Study with the Bobwhite: 

Final Report: Rept. No. 107-206. Unpublished study prepared by Wildlife 

International Ltd. 15 p. 

71-4 Avian Reproduction

MRID Citation Reference

40190201 Beavers, J.; Jaber, M. (1986) Rizolex Technical: A One Generation 

Reproduction Study with the Bobwhite (Colinus virginianus): Project No. 107-

213. Unpublished study prepared by Wildlife International Ltd. 118 p. 

40190202 Beavers, J.; Jaber, M. (1986) Rizolex Technical: A One Generation 

Reproduction Study with the Mallard (Anas platyrhynchos): Project No. 107-

214. Unpublished study prepared by Wildlife International Ltd. 119 p. 

72-1 Acute Toxicity to Freshwater Fish

MRID Citation Reference
115

156117 Takimoto, Y.; Kagoshima, M. (1982) The Acute Toxicity of S-3349 to Rainbow 

Trout (Salmo gairdneri). Unpublished study prepared by Sumitomo Chemical 

Co., Ltd. 11 p. 

156118 Takimoto, Y.; Kagoshima, M.; Ashida, S.; et al. (1981) The Acute Toxicity of 

S-3349 to Carp (Cyprinus carpio) and Killifish (Ory- zias latipes). Unpublished 

study prepared by Sumitomo Chemical Co., Ltd. 12 p. 

156119 Takimoto, Y.; Kagoshima, M.; Ashida, S. (1981) The Acute Toxicity of S-3349 

to Guppy (Poecilia reticulata). Unpublished study prepared by Sumitomo 

Chemical Co., Ltd. 8 p. 

163558 Bowman, J. (1986) Acute Toxicity of Rizolex Technical to Bluegill Sunfish 

(Lepomis macrochirus): Rept. #34647. Unpublished study prepared by

Analytical Bio-Chemistry Laboratories Inc. 48 p. 

41400301 McAllister, W. (1989) Acute Flow-through Toxicity of Rizolex Tech- nical to 

Bluegill (Lepomis macrochirus): Lab Project Number: 37795. Unpublished 

study prepared by Analytical Bio-Chemistry Laboratories, Inc. 169 p. 

48737502 Dionne, E. 1998. Desmethyl-Tolclofos methyl - Acute Toxicity to Rainbow 

Trout (Oncorhynchus mykiss) Under Static Acute Conditions Lab ID Number: 

13048.6177

72-2 Acute Toxicity to Freshwater Invertebrates

MRID Citation Reference

156120 Takimoto, Y.; Kagoshima, M. (1982) The Acute Toxicity of S-3349 to Daphnia 

pulex. Unpublished study prepared by Sumitomo Chemical Co., Ltd. 5 p. 

40096301 Forbis, A. (1987) Acute Toxicity of Rizolex Technical to Daphnia magna: ABC 

Laboratory Project ID: #35337. Unpublished study prepared by Analytical BioChemistry Laboratories, Inc. 44 p. 

41400302 Burgess, D. (1989) Acute Flow-through Toxicity of Rizolex to Daphnia magna: 

Lab Project Number: Final Report #37796. Unpub- lished study prepared by

Analytical Bio-Chemistry Laboratories, Inc. 157 p. 

43528001 Murrell, H.; Bucksath, J. (1994) Acute Toxicity of Rizolex to Daphnia magna: 

Final Report: Lab Project Number: 41242. Unpublished study prepared by ABC 

Labs, Inc. 271 p. 

48737501 Dionne, E. 1998. Desmethyl-Tolclofos methyl- Acute Toxicity to Daphnids 

(Daphnia magna) Under Sialic Conditions. Lab ID Number: 13048.6178

72-4 Fish Early Life Stage/Aquatic Invertebrate Life Cycle Study

MRID Citation Reference
116

41400303 Burgess, D. (1989) Chronic Toxicity of Rizolex to Daphnia magna under Flowthrough Test Conditions: Lab Project Number: 37552. Unpublished study

prepared by Analytical Bio-Chemistry Labora- tories, Inc. 29 p. 

41624501 Burgess, D. (1989) Chronic Toxicity of Rizolex to Daphnia magna under Flowthrough Test Conditions: Lab Project Number: 37552. Unpublished study

prepared by Analytical Bio-Chemistry Labora- tories, Inc. 417 p. 

42106501 Cohle, P.; Leak, T. (1991) Early Life Stage Toxicity of Rizolex Technical to 

Rainbow Trout (Oncorhynchus mykiss) in a Flow- through System: Final 

Report: Lab Project Number: 38586R. Un- published study prepared by ABC 

Laboratories, Inc. 1476 p. 

141-1 Honeybee acute contact

MRID Citation Reference

156122 Takarazuka Research Center (1983) Toxicity of Tolclofos-methyl against 

Honeybees, Apis mellifera. Unpublished study prepared by Sumitomo Chemical 

Co., Ltd. 2 p. 

163557 Sumitomo Chemical Co., Ltd. (1983) Toxicity of Tolclofos-methyl against 

Honeybees, Apis mellifera: Doc. Code QW-30; Ref. No. -0018. Unpublished 

study. 3 p. 

41794202 Winter, P.; Hoxter, K.; Smith, G. (1990) Rizolex: An Acute Contact Toxicity

Study with the Honeybee: Lab Project Number: 131-141. Unpublished study

prepared by Wildlife International, Ltd. 15 p. 

165-4 Bioaccumulation in fish

MRID Citation Reference

163641 Forbis, A.; Bunch, B. (1986) Uptake, Depuration and Bioconcentration of [Carbon 

14]-Rizolex by Bluegill Sunfish (Lepomis macrochirus): ABC Final Report #33971. 

Unpublished study prepared by Analytical Biochemistry Laboratories Inc. 42 p. 

163642 Yu, C.; Guirguis, A. (1986) Metabolism of Tolclofos-methyl in Blue- gill Sunfish 

(Lepomis macrochirus): Project No. 411968: Report No. 7. Unpublished study

prepared by Sandoz Crop Protection Corp. 15 p. 

48737503 Herczog, K; Panthani, A. 2004. Bioconcentration of 14C Tolclofos-methyl by Bluegill 

Sunfish (Lepomis macrochirus). Lab ID Number: 016416-1

850.1010 Aquatic invertebrate acute toxicity, test, freshwater daphnids
117

MRID Citation Reference

48737501 Dionne, E. (1998) Desmethyl-Tolclofosmethyl: Acute Toxicity to Daphnids 

(Daphnia magna) Under Static Conditions. Project Number: 200900134, 13048/6178, 

QW/0054. Unpublished study prepared by Springborn Smithers Laboratories. 50p.

850.1025 Oyster acute toxicity test (shell deposition)

MRID Citation Reference

48341928 Gallagher, S.; Kendall, T.; Krueger, H. (2010) A 96-Hour Shell Deposition Test with 

the Eastern Oyster (Crassostrea virginica) (Tolclofos-Methyl). Project Number: 

201000049, 263A/110A. Unpublished study prepared by Wildlife International, Ltd. 

57 p.

850.1035 Mysid acute toxicity test

MRID Citation Reference

48341929 Palmer, S.; Schneider, S.; Kendall, T.; et al. (2010) V-10178: A 96-Hour StaticRenewal Acute Toxicity Test with the Saltwater Mysid (Americamysis bahia). 

Project Number: 201000249, 263A/112, VP/37053. Unpublished study prepared by

Wildlife International, Ltd. 58 p.

850.1075 Fish acute toxicity test, freshwater and marine

MRID Citation Reference

48341930 Sousa, J. (2003) Tolclofos-Methyl Acute Toxicity to Rainbow Trout (Oncorhynchus 

mykiss) Under Flow-Through Conditions. Project Number: 13048/6416, QW/0071, 

040703/RBT/FT/SUMITO. Unpublished study prepared by Springborn Viscient 

Laboratories. 55 p.

48341931 Thomas, S.; Kendall, T.; Krueger, H. (2010) V-10178: A 10-Day Survival and 

Growth Sediment Toxicity Test with the Freshwater Amphipod (Hyalella azteca) 

Using Spiked Sediment. Project Number: 263A/113, VP/37063, 201000330. 

Unpublished study prepared by Wildlife International, Ltd. 88 p.

48341932 Palmer, S.; Schneider, S.; Kendall, T.; et al. (2010) V-10178: A 96-Hour StaticRenewal Acute Toxicity Test with the Sheepshead Minnow (Cyprinodon variegatus). 

Project Number: 201000250, 263A/111, VP/37051. Unpublished study prepared by

Wildlife International, Ltd. 55 p.

48737502 Dionne, E. (1998) Desmethyl-Tolclofosmethyl: Acute Toxicity to Rainbow Trout 

(Oncorhynchus mykiss) Under Static Acute Conditions. Project Number: 200900135, 

13048/6177, QW/0055. Unpublished study prepared by Springborn Smithers 

Laboratories. 50p.

850.1350 Mysid chronic toxicity test

MRID Citation Reference
118

48341933 Palmer, S.; Claude, M.; et al. (2009) V-10178: A Flow-Through Life-Cycle Toxicity

Test with the Saltwater Mysid (Americamysis bahia). Project Number: 201000324, 

263A/115C, VP/37125. Unpublished study prepared by Wildlife International, Ltd. 

131 p.

850.1400 Fish early-life stage toxicity test

MRID Citation Reference

48341934 Rose, A. (2010) Toclofos-Methyl: Salt Water Fish Early Life-Stage Waiver Request. 

Project Number: 201000332, VP/37837. Unpublished study prepared by Valent 

U.S.A. Corporation. 6 p.

850.2100 Avian acute oral toxicity test

MRID Citation Reference

48341936 Hubbard, P.; Beavers, J. (2010) V-10178: An Acute Oral Toxicity Study with the 

Zebra Finch (Poephilia guttata). Project Number: 201000053, 263/164. Unpublished 

study prepared by Wildlife International, Ltd. 46 p.

850.4100 Terrestrial plant toxicity, Tier 1 (seeding emergence)

MRID Citation Reference

48341937 Shen, S. (2010) Rizolex Flowable Fungicide - Waiver for Non-Applicable NonTarget Plant Protection Studies. Project Number: 201000326, VP/37701. 

Unpublished study prepared by Valent U.S.A. Corporation. 8 p.

48341938 Shen, S. (2010) Waiver Request: Toclofos Methyl Seed Treatment Registration Tier I 

Seedling Emergence, Tier I Vegetative Vigor, Tier I Aquatic Plant Growth, 

Honeybee Acute Contact. Project Number: 201000335, V/37701. Unpublished study

prepared by Valent U.S.A. Corporation. 8 p.

850.4150 Terrestrial plant toxicity, Tier 1 (vegetative vigor)

MRID Citation Reference

48341937 Shen, S. (2010) Rizolex Flowable Fungicide - Waiver for Non-Applicable NonTarget Plant Protection Studies. Project Number: 201000326, VP/37701. 

Unpublished study prepared by Valent U.S.A. Corporation. 8 p.

48341938 Shen, S. (2010) Waiver Request: Toclofos Methyl Seed Treatment Registration Tier I 

Seedling Emergence, Tier I Vegetative Vigor, Tier I Aquatic Plant Growth, 

Honeybee Acute Contact. Project Number: 201000335, V/37701. Unpublished study

prepared by Valent U.S.A. Corporation. 8 p.

850.4400 Aquatic plant toxicity test using Lemna spp. Tiers I and II

MRID Citation Reference

48341937 Shen, S. (2010) Rizolex Flowable Fungicide - Waiver for Non-Applicable NonTarget Plant Protection Studies. Project Number: 201000326, VP/37701. 

Unpublished study prepared by Valent U.S.A. Corporation. 8 p.
119

48341938 Shen, S. (2010) Waiver Request: Toclofos Methyl Seed Treatment Registration Tier I 

Seedling Emergence, Tier I Vegetative Vigor, Tier I Aquatic Plant Growth, 

Honeybee Acute Contact. Project Number: 201000335, V/37701. Unpublished study

prepared by Valent U.S.A. Corporation. 8 p.

850.5400 Algal toxicity, Tiers 1 and II

MRID Citation Reference

48341937 Shen, S. (2010) Rizolex Flowable Fungicide - Waiver for Non-Applicable NonTarget Plant Protection Studies. Project Number: 201000326, VP/37701. 

Unpublished study prepared by Valent U.S.A. Corporation. 8 p.

48341938 Shen, S. (2010) Waiver Request: Toclofos Methyl Seed Treatment Registration Tier I 

Seedling Emergence, Tier I Vegetative Vigor, Tier I Aquatic Plant Growth, 

Honeybee Acute Contact. Project Number: 201000335, V/37701. Unpublished study

prepared by Valent U.S.A. Corporation. 8 p.

48737505 Hoberg, J. (1998) Desmethyl-Tolclofosmethyl: Toxicity to the Freshwater Green 

Alga (Scenedesmus subspicatus). Project Number: 200900098, 13048/6176, 

QW/0053. Unpublished study prepared by Springborn Smithers Laboratories. 62p.

48737506 Sayers, L. (2003) Tolclofosmethyl: Toxicity to the Freshwater Green Alga 

(Scenedesmus subspicatus). Project Number: 200900097, 13048/6415, QW/0072. 

Unpublished study prepared by Springborn Smithers Laboratories. 61p.

850.1740 Whole sediment: acute marine invertebrates

MRID Citation Reference

48341935 Thomas, S.; Kendall, T.; Krueger, H. (2010) V-10178: A 10-Day Survival Toxicity

Test with the Marine Amphipod (Leptocheirus plumulosus) Using Spiked Sediment. 

Project Number: 201000339, 263A/114, VP/37058. Unpublished study prepared by

Wildlife International, Ltd. 121 p.

850.1790 Chironomid Sediment Toxicity Test

MRID Citation Reference

48737504 Putt, A. (2002) Tolclofos-methyl: The Full Life-Cycle Toxicity to Midge 

(Chironomus riparius) Under Static Conditions. Project Number: 200900139, 

13048/6331, QW/0063. Unpublished study prepared by Springborn Smithers 

Laboratories. 101p.

Submitted Mammalian Studies

MRID Author(s) Year Title 
120

MRID Author(s) Year Title 

156124 Kynoch, S. 1985 Acute Oral Toxicity to Rats of Rizolex Technical: 

HRC Rept. No.85677D/VCL 83/AC. 

Unpublished study prepared by Huntingdon 

Research Centre Ltd. 10 p 

156140 Pence, D. 1982 Chronic Toxicity Study in Rats: S3449: Final 

Report: Project No. 343-118. Un1published study 

prepared by Hazleton Laboratories America, Inc. 

1939 p. 

156137 Suzuki, T 

Okuno, Y 

Hiromori, T

1978 Nine- month Feeding Study of S-3349 in mice. 

Unpublished study prepared by Institute for: 

Biological Science, Hyogo, Japan. 185 p.

156121 Takimoto, Y. 

Yasutaniya, T.

1983 The Effect of Tolclofos-methyl on the Growth of 

the Green Alga, Scenedesmus quadricauda.

Unpublished study prepared by Sumitomo 

Chemical Co.Ltd 20 p.

156128 Segawa, T 1978 Acute Toxicity Study of S-3349 in Rats and 

Mice. Institute of Pharmaceutical Sciences, 

Hiroshima University, Japan Sumitomo Chemical 

Company, Ltd., Japan; QT-71-0003

41422901 Morseth, S 1987 Teratology Study of S-3349 T.G. in Rats. HLA 

343-192, Sumitomo Chemical Co., Ltd. Osaka, 

Japan

156138 Pence, D et al 1979 Subacute Dietary Administration in Dogs S-3349 

Final Report. 343-120. Hazleton Laboratories 

America, Inc. Herndon, Va. Sandoz Crop Protection 

Chicago, Illinois.

265173 Mihara, K., 

Ohkawa, H., 

Miyamoto, J

1980 Metabolism of tolclofos-methyl in rats and mice. 

(Unpublished study No. QM-OO-0008 performed 

and submitted by Sumitomo Chemical Co., Ltd., 

Osaka, Japan
121

APPENDIX C. DATA REQUIREMENTS AND DATA GAPS 

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

OFFICE OF

CHEMCICAL SAFETY AND

POLLUTION PREVENTION

PC code: 128905

DP Barcode: 388586

November 3, 2011

MEMORANDUM

SUBJECT: Environmental Fate and Ecological Effects New Chemical Screen for Tolclofosmethyl

FROM: Keith Sappington, Senior Biologist

Larry Liu, Chemist

Environmental Risk Branch V

Environmental Fate and Effects Division (7507P) 

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

Environmental Risk Branch V

Environmental Fate and Effects Division (7507P)

TO: Lisa Jones, Risk Manager Reviewer,

Mary Woller, Risk Manager, RM-21

Fungicide Branch,

Registration Division (7505P)

EFED has completed a new chemical screen of the environmental fate and ecological effects 

studies submitted by Valent USA Corporation in support of a new registration for the fungicide, 

Tolclofos-methyl. This screen included:

 A check of the submission to ensure that all studies triggered by the use pattern are 

included in the package

 An evaluation as to whether each study is reviewable, i.e., has no fatal flaws 

rendering the study scientifically invalid

 Consideration of the submitted waiver requests (detailed under a separate action).
122

Please note that this screen is not intended to be a comprehensive evaluation of the quality of 

submitted studies. Rather, it is an indication of the completeness of the data package that has 

been submitted to the Agency. Therefore, studies that pass this screen are not automatically

assured of acceptance in support of the respective data requirement. 

Based on this new chemical screen, the following data gaps are noted:

 Photodegradation in water (835.2240)

 Aerobic soil metabolism (835.4100)

 Anaerobic soil metabolism (835.4200)

 Corresponding ECMs for the submitted ILVs

In addition to these data gaps, we note that tolclofos methyl (a phosphorothionate

organophosphate (OP) pesticide), has been shown to form oxon degradates in various 

environmental fate studies (see summaries below). Oxon degradates can be substantially more 

toxic than parent organophosphates (up to 100X). Although EFED’s policy regarding data 

requirements for oxon degradates would ordinarily recommend additional toxicity and fate 

studies,14 the low toxicity of this chemical combined with its relatively low estimated 

environmental concentrations (EECs) indicates that additional data on the oxon degradate would 

not likely affect the risk assessment conclusions (including endangered species) for the proposed 

seed treatment uses. However, should new uses of tolclofos methyl be proposed in the future, 

the need for oxon-related fate and ecological effects data will be re-evaluated and additional 

studies may be requested at that time. 

A study-by-study evaluation of data gaps is provided in the following table. Please let us know 

if you have any questions or concerns.

 

14 Guidance for Registration Review Data Requests for Oxon Degradates of Organophosphate Insecticides (OP). 

Memo from Don Brady (Division Director). March 10, 2009.
123

DATA PACKAGE NEW CHEMICAL SCREEN FOR:

Tolclofos-methyl

PC Code: 128905

Data Requirement Test Species MRID

Are Data 

Reviewable? 

(Y/N)

Study 

Classification 1

Additional 

Data 

Needed?

(Y/N)

§158.630 WILDLIFE AND AQUATIC ORGANISMS

Avian Studies

850.2100/71-1(a) Avian Acute 

Oral, Quail/Duck

Mallard

Bobwhite

Pheasant

00156112

00156113

00156114

Y

Y

A

A N

3

850.2100 Avian Acute Oral, 

Passerine zebra finch 48341936 YN

850.2200/71-2(a) Avian Dietary, 

Quail Bobwhite 00156116 YA N

850.2200/71-2(b) Acute Dietary, 

Duck Mallard 00156115 YA N

850.2400/71-3 Wild Mammal 

Toxicity N

850.2300/71-4(a) Avian 

Reproduction, Quail Bobwhite 40190201 YA N

850.2300/71-4(b) Avian 

Reproduction, Duck Mallard 40190202 YA N

Terrestrial Field Studies

850.2500/71-5(a) Simulated 

Terrestrial Field Study N

850.2500/71-5(b) Actual 

Terrestrial Field Study N

Aquatic Studies: Acute

850.1075/72-1(a) Acute 

Freshwater Fish, Warmwater

Carp, Killifish

Guppy

Bluegill

Bluegill

00156118

00156119

00163558

41400301

Y

Y

Y

Y

S (test sp)

S (test sp)

S (precip)

S (> LC50)

N

3

850.1075/72-1(b) Acute Fish 

Toxicity, Warmwater (TEP) N

850.1075/72-1(c) Acute 

Freshwater Fish, Coldwater

Rainbow trout

Rainbow trout

48341930

00156117

Y

Y

A (FT)

A (SR) N

850.1075/72-1(d) Acute 

Freshwater Fish, Coldwater (TEP) N
124

Data Requirement Test Species MRID

Are Data 

Reviewable? 

(Y/N)

Study 

Classification 1

Additional 

Data 

Needed?

(Y/N)

850.1010/72-2(a) Acute 

Freshwater Invertebrate

D. pulex

D. magna

00156120

43528001

Y

Y

S (24h)

A N

3

850.1010/72-2(b) Acute 

Freshwater Invertebrate (TEP) N

850.1075/72-3(a) Acute 

Estuarine/Marine, Fish

Sheepshead 

Minnow

48341932 Y NR N

850.1075/72-3(d) Acute 

Estuarine/Marine, Fish (TEP) N

850.1025/72-3(b) Acute 

Estuarine/Marine, Bivalve (shell 

deposition)

850.1055 (embryo/lavae)

Eastern oyster 48341928 Y NR N

850.1025/72-3(e) Acute 

Estuarine/Marine, Bivalve (shell 

deposition)

850.1055 (embryo/larvae) (TEP)

N

850.1035/72-3(c) Acute 

Estuarine/Marine, Crustacean 

(mysid) 

850.1045 (penaeid)

Mysid 48341929 Y NR N

850.1035/72-3(f) Acute 

Estuarine/Marine, Crustacean 

(mysid)

850.1045 (penaeid) (TEP)

N

Aquatic Studies: Chronic

850.1400/72-4(a) Fish Early-Life 

Stage (FW, SW)

Rainbow trout

Saltwater fish

42106501

48341934

Y

W.R.

Waiver 

request 

accepted

N

850.1300/72-4(b) Freshwater 

Invertebrate Life Cycle D. magna

41400303

41624501

Y A N

850.1350/72-4(b) Saltwater 

Invertebrate Life Cycle Mysid 48341933 Y NR N

Aquatic Studies: Other

850.1500/72-5 Fish Life Cycle N

850.1735 Whole Sediment Acute 

Invertebrate, Freshwater Hyalella azteca 48341931 Y NR N

850.1740 Whole Sediment Acute 

Invertebrate, Saltwater

Leptocheirus 

plumulosus 48341935 Y NR N

850.1760, 1770Whole Sediment 

Chronic Invertebrate, Freshwater 

(midge, amphipod)

N
125

Data Requirement Test Species MRID

Are Data 

Reviewable? 

(Y/N)

Study 

Classification 1

Additional 

Data 

Needed?

(Y/N)

850. 1780 Whole Sediment Chronic 

Invertebrate, Saltwater (amphipod) N

850.1950/72-7 Simulated or Actual 

Aquatic Field Study N

§158.660 PLANT PROTECTION

850.4100/122-1(a) Seedling 

Emergence, Tier 1

48341937

48341938

W.R.

Waiver 

request 

accepted N

850.4150/122-1(b) Vegetative 

Vigor, Tier 1

48341937

48341938

W.R.

Waiver 

request 

accepted N

850.5400/122-2 Aquatic Plant 

Growth, Algae, Tier 1

Green algae

48341937

48341938

00156121

W.R.

Y

Waiver 

request 

accepted

A N

850.4400/123-2 Aquatic Plant 

Growth, Vascular Plant, Tier 1

48341937

48341938

W.R.

Waiver 

request 

accepted N

850.4100/123-1(a) Seedling 

Emergence, Tier 2 N

850.4150/123-1(b) Vegetative 

Vigor, Tier 2 N

850.4400/123-2 Aquatic Plant 

Growth, Vascular Plant, Tier 1 N

850.5400/123-2 Aquatic Plant 

Growth, Algae, Tier 2

N

850.4300, 124-1 Terrestrial Field 

Study, Tier 3 N

850.4450, 124-2 Aquatic Field 

Study, Tier 3 N

§158.630 NONTARGET INSECT TESTING

850.3020/141-1 Honeybee Acute 

Contact

48341938

41794202

W.R.

Y (TGAI) A N

850.3030/141-2 Honeybee, 

Residues on Foliage N

Non-Guideline Study: Honeybee, 

acute oral N

850.3040/141-5 Field Test for 

Pollinators N
126

Data Requirement Test Species MRID

Are Data 

Reviewable? 

(Y/N)

Study 

Classification 1

Additional 

Data 

Needed?

(Y/N)

§158.1300 ENVIRONMENTAL FATE

Degradation Studies-Lab:

835.2120/161-1 Hydrolysis

156104

41714701

48341921

Y

Y

Y

S

A

U (prelim.)

N

835.2240/161-2 Photodegradation 

In Water

156105 

41422902

Y

Y

S

S 

(upgradable)

Y 2

835.2410/161-3 Photodegradation 

on Soil 42536001 Y A N

835.2370/161-4 Photodegradation 

in Air 48341945 Y S 

(preliminary) N

Metabolism Studies-Lab:

835.4100/162-1 Aerobic Soil

4156106

42703201

48341922

48341923

48341925 

(addendum 

to 

48341923)

48341924

Y

S

A (1 soil 

only)

S (prelim.)

S (prelim.)

S (prelim.)

S (prelim.)

Y

3,4

835.4200/162-2 Anaerobic Soil 42818301 Y

A (1 soil 

only) Y

4

835.4300/162-4 Aerobic Aquatic

158107

48341926

Y

S

S (prelim.)

N

835.4400/162-3 Anaerobic 

Aquatic 43128101 Y A N

Mobility Studies:
127

Data Requirement Test Species MRID

Are Data 

Reviewable? 

(Y/N)

Study 

Classification 1

Additional 

Data 

Needed?

(Y/N)

835.1230/163.1 LeachingAdsorption/Desorption

835.1240

156108

156109

42273301

42273302

48341919 

(two soils)

Referred to 

MRID 

42273301 

for 

additional 

Koc

Y

 S

S

A

A

S (prelim.)

N

3

835.1410/163-2 Volatility (Lab)

156110

40352201

Waiver 

request

Y

U

U

N

5

Dissipation Studies-Field:

835.6100/164-1 Terrestrial

156111

43785001

43785002

43785003

Waiver 

request

Y

S

A

A

A

N

835.6200/164-2 Aquatic 

(Sediment)

Waiver 

request

Y N

835.8100/163-3 Volatility (Field) Waiver 

request Y N

Accumulation Studies:

850.1730/72-6/165-4 Fish BCF 

163641

163642 Y

U (exposure 

conc.) N

5

Analytical Methods

ECMs/ILVs

(48341916;

48842102)

48341917;

48842101)

48341918;

48842103)

Y Y

6

FOOTNOTES:

1. Note: study classifications of older (previously reviewed) studies is indicated by the following: A=acceptable, S= 

supplemental; U= unacceptable. Study classifications of newer data submissions are indicated as being “preliminary” (prelim.) 
128

or not yet reviewed (NR). W.R. = waiver request. 

2. Study is upgradable per the summary on the aqueous photolysis study below.

3. Study on the oxon degradate (TMO and/or DM-TMO) is not requested for the proposed seed treatment use. However, the 

need for this study may be triggered by additional uses if proposed in the future. 

4. Data requested for additional soil types according to current OSCPP test guidelines.

5. Study of parent tolclofos methyl (with measurement of oxon degradates) is not being requested for this proposed use. 

However, the need for this study may be triggered by additional uses if proposed in the future. 

6. Corresponding ILVs should be submitted.
129

APPENDIX D. ECOTOXICITY STUDY SUMMARIES 

Fish, Acute Toxicity 

156117

Miyamoto et al (1982) conducted a 96-hour static-renewal study on juvenile rainbow trout, Oncorhynchus 

mykiss weighing 0.85 ± 0.14 g on average. 10 trout were exposed in 20-L glass aquaria to nominal 

concentrations of 0.05, 0.1, 0.18, 0.32, 0.56, 0.75, 1, 1.8, 3.2 mg ai/L TGAI (97.8%). Test vessels were 

renewed every 24 hours. Actual test measurements at the 0.56 ppm every 24 hours suggested that actual 

concentrations ranged from 72.5% to 96.4% of nominal. Test temperature was 15C, pH ranged from 7.2 

to 7.7, and dissolved oxygen was > 7 mg/L. Control mortality was 0% and the 96-hour LC50 is estimated 

to be 0.87 ppm (Probit). Symptoms of intoxication for included (in the order of occurrence): abnormal 

respiration (slackness), lethargy, loss of equilibrium, darkening and death. At 0.05 ppm, no adverse 

effects were observed. No precipitation was reported in this study despite test concentrations that 

exceeded solubility limit of 0.7-1.0 ppm and precipitation problems reported on other similar studies. It is 

noted that this study used an unusual solvent (10 parts dimethylsulfoxide and 10 parts polyoxyethylene 

hydrogenated castor oil) that evidently was adequate to achieve dose response at the levels tested. This 

study is considered supplemental because of a number of deficiencies including: frequency of temperature 

determination was not indicated, the lighting schedule was not specified, aeration was not specified, no 

total residual chlorine measurement was made of dilution water (dechlorinated tap water), the solvent was 

not one of those normally accepted; however, there was no mortality in the solvent control.

48341930

In a 96-h acute toxicity study, Sousa et al (2003) exposed rainbow trout (Oncorhynchus mykiss) to 

Tolclofos-methyl TGAI (97.8%) at nominal concentrations of 0 (negative and solvent controls), 0.21, 

0.36, 0.59, 0.99, and 1.6 mg ai/L under flow-through conditions. Mean-measured concentrations were 

<LOQ (<0.025, controls), 0.17, 0.25, 0.35, 0.61, and 0.80 mg ai/L; a precipitate was noted in test 

solutions as the limit of solubility was approached by these concentrations. Therefore, samples were 

centrifuged prior to analysis.

The 96-h LC50 was 0.69 mg ai/L. The NOAEC, based on mortality and sub-lethal effects was 0.35 mg 

ai/L; loss of equilibrium and lethargy were observed after 6 hours in the 0.61 and 0.80 mg ai/L levels. No 

mortality occurred in either the negative or solvent controls. Based on the results of this study, tolclofosmethyl would be classified as highly toxic to Oncorhynchus mykiss in accordance with the classification 

system of the U.S. EPA. This toxicity study is classified scientifically sound and satisfies the guideline 

requirement for a freshwater fish toxicity study.

47837502

Dionne (1998) exposed 10 rainbow trout (0.68-1.8g) to 98.9% DM-TM (a metabolite of tolclofos methyl) 

in a static system over a period of 96 hours. Nominal concentrations were 18, 30, 50, 84 and 140 mg 

a.i./L. In addition, a dilution water control was tested (solvents were not used so a solvent control was not 

necessary). Each test chamber (18.9 L glass aquaria, each containing 15 L of test solution) served as one 

replicate. Trout were maintained at 14-15C and not fed during exposure. For analytical verification of the 

test item, samples were taken at 0 and 96 hours from all concentrations. QA spike results indicate 

recovery of 96% to 101% respectively using high performance liquid chromatographic with ultraviolet 

detection (HPLC/UV) procedure. Mortality and signs of toxicity were assessed at 6 hours after test 

initiation and daily thereafter. Temperature, pH and dissolved oxygen concentrations were also measured 
130

daily. Alkalinity, hardness, and conductivity were measured in a sample of the dilution water at test 

initiation.

The test substance was stable over 96 hours although measure concentrations were 77-79% of nominal. 

Regulatory endpoints are reported as mean measured concentrations. All water quality parameters 

remained within acceptable limits. Following 96 hours of exposure (test termination), no mortality or 

sublethal adverse effects were observed among trout exposed to any treatment level tested or the control. 

Based on these results, the 96-hour LC50 was empirically estimated to be greater than 110 mg a.i./L, the 

highest mean measured concentration tested. The No-Observed-Effect Concentration (NOEC) was 

determined to be 110 mg a.i./L. DM-TM is classified as practically non-toxic to rainbow trout.

00156118

Takimoto et al (1981) exposed juvenile carp (Cyprinus carpio, avg. weight 0.46g) and killifish (Japanese 

medaka, Oryzias latipes, avg. weight 0.36g) to TM TGAI (99.8%) in a 24-h static renewal system for 96-

hours. Ten fish of each species were exposed/treatment (1 replicate/treatment). Exposure concentrations 

were 0, 0.1, 0.18, 0.32, 0.56, 1.0, 1.8, 5.6 and 7.8 mg ai/L. Fish were acclimated 14 days and fasted 2 days 

prior to testing. Test temperature was 23C, pH was in the range of 7.30-7.80 and dissolved oxygen 

concentrations was more than 6 ppm. The analytical results of TM in the test solution showed that the 

actual concentrations were found to be equivalent to the nominal soon after introduction of the solution. 

Subsequently, the test concentrations decreased to about 70%, (killifish) and 80% (carp) of the initial 

concentrations during the 24 hr renewal. On average, measured concentrations for carp and medaka were 

92.8% and 88.2% of the nominal, respectively. 

The 96-h LC50 values for carp and medaka are 2.1 and 3.0 mg ai/L, respectively, which exceed the 

reported solubility of TM in water (0.7-1.0 mg/L). Sublethal effects (loss of equilibrium, abnormal 

respiration lethargy, darkened color) were observed at 0.18 ppm and above for carp and 0.32 ppm and 

above for medaka. No precipitate was reported in test solutions, however, a non-standard solvent was 

used (10 parts dimethylsulfoxide and 10 parts polyoxyethylene hydrogenated castor oil) at a concentration 

(0.15 ml/L) that exceeded the recommended 0.1 ml/L level. This study is considered supplemental 

because of a number of deficiencies including: frequency of temperature determination was not indicated, 

the lighting schedule was not specified, aeration was not specified, the solvent was not one of those 

normally accepted; however, there was no mortality in the solvent control.

00156119

Takimoto et al (1981) exposed guppy (Poecilia reticulata, avg. weight 40.4 mg) to TM TGAI (99.8%) in 

a 24-h static renewal system for 96-hours. Exposure concentrations were 1.0, 1.8, 5.6, 7.8, 10, 13.5, and 

18 mg ai/L. Fish were acclimated 30 days and fasted 24 hours prior to testing. Test temperature was 23C, 

pH was in the range of 7.4 to 7.8, and dissolved oxygen concentrations were 7.0 ppm and greater. Test 

concentration was measured only in the 1.0 ppm treatment., which averaged 95.8% of nominal. 

The 96-hour LC50 is estimated to be 3.18 ppb and the observed NOAEC is estimated to be 1.0 mg/L based 

on lack of mortality. No problems with solubility were reported in this study, however, a non-standard 

solvent was used (10 parts dimethylsulfoxide and 10 parts polyoxyethylene hydrogenated castor oil) at a 

concentration (0.36 ml/L) that exceeded the recommended 0.1 ml/L level. This study is classified as 

supplemental due to no reported data on temperature range and photoperiod, no total residual chlorine 

measurement of dilution water (dechlorinated tap water), no specification of treatments in which sublethal 

effects occurred. 
131

41400301

McAllister (1989) exposed juvenile bluegill (Lepomis macrochirus, 3.4+ 0.94g) to TM (97.2%) in a flowthrough system (10.7 overturns/day) for 96 hours. Bluegill were reared for 6 months and not fed 48 hours 

prior to testing (no mortality during this period). Temperature was maintained at 22 + 1°C and dilution 

water used in the test was a soft blended water (a mixture of well water and reverse-osmosis well water). 

Nominal test concentrations were 46, 93, 185, 370, and 740 ug ai//L) plus a negative and solvent control 

(0.1 ml/L acetone). During the test, dissolved oxygen ranged from 87 to 94% saturation, pH ranged from 

7.7-8.0 and temperature ranged from 21.5-21.8C. The mean measured concentrations were 43, 93, 179, 

360 and 720 ug/L, representing 93, 100, 97, 97, and 97% of the nominal concentrations, respectively. No 

mortality occurred during the observation periods. The 24-, 48-, 72-, and 96-hour LC50 values were all 

estimated to be >720 ug/L, based on the mean measured concentrations at 0 and 96 hours. The noobserved-effect concentration (NOEC) was determined to be 720 ug/L. This study is considered 

supplemental because an LC50 was not achieved and a precipitate was observed at highest test treatment 

every day but samples were not apparently centrifuged.

48341932

Palmer et al (2010) conducted a static renewal 96-h acute toxicity study of sheepshead minnow, 

Cyprinodon variegatus, using TM TGAI (95.6%) at nominal concentrations of 0 (negative and solvent 

controls), 63, 125, 250, 500, and 1,000 μg ai/L. The mean-measured concentrations were <LOQ (<30, 

controls), 50, 89, 183, 372, and 312 μg ai/L. Precipitation was reported at the highest test concentration 

and therefore, results were centrifuged prior to analysis. No mortality or sublethal effects occurred at any 

test concentration, resulting in a 96-h LC50 of >372 μg ai/L. The NOAEC value, based on a lack of 

mortality and sub-lethal effects, was 372 μg ai/L. 

Based on the results of this study, Tolclofos-methyl would be classified as not toxic at the limit of its 

water solubility to Cyprinodon variegatus. 

Fish, Chronic Toxicity

42106501

Cohle and Leak (1991) conducted a 97-day chronic early life stage test on rainbow trout, O. mykiss using 

flow through condition. Thirty-five eggs were randomly placed in each of 4 incubation cups/treatment 

with hard blended dilution water. Viability was determined on dilution water controls. Endpoints 

measured included mortality, hatching, fry mortality, growth and behavioral changes. The temperature, 

dissolved oxygen (DO), conductivity and pH were measured weekly and on days 0, 1, and 97. Dissolved 

oxygen ranged from 8.1 to 10.8 mg/l (75 to 100% saturation at test temperatures), pH values ranged from 

8.0 to 8.7, conductivity ranged from 373 to 445, umhos/cm, alkalinity and hardness ranged from 178 to

200 mg/l and 158 to 178 mg/l , respectively. With the exception of days 36 and 82-87, the temperature 

ranged from 8.6 to 11.2C. On these days, cooling system failure resulted in gradual temperature 

fluctuations outside this range (7.9-13.6C) which did not appear to affect the integrity of the test. 

The mean measured concentrations for the 97-day test were 12, 28, 53, 110, and 200 ug/l. These values 

represent 92, 122, 106, 110, and 100% of nominal concentrations. The viability of the eggs held in control 

water was 100%. Hatching began on day 32 and was 95% complete by day 37. Percent egg, hatch in all 

replicates of the controls was 100% and no significant reduction in percent egg hatch was detected for any 

test level compared to the controls. The number of fry swimming-up in each chamber was recorded for 

days 49 through 59. Although initially swim-up progressed somewhat slower in 28 ug/l and 53 ug/l 

compared to controls, only in 110 ug/l and 200 ug/l did there appear to be a biologically significant delay 

in swim-up. Fry survival at 37-d post hatch was significantly reduced at the highest test concentration 
132

(200 ug/l). At test termination (60 days post hatch), fry survival in the two highest concentrations (110 

and 200 ug/l) was significantly lower than the controls. At 37 days post-hatch, significant reductions in 

fish lengths were observed at 12, 28, 53, 110 ug/l relative to negative controls.. Significant reductions in 

fish weight were observed at all test concentrations at 60-d post hatch. For fish weight (60d post hatch), 

the LOAEC represents a 24% reduction relative to negative controls, while the length LOAEC represents 

a 1.3% reduction relative to negative controls. The NOAEC for this study is determined to be < 12 ug 

ai/L and the LOAEC determined to be 12 ug ai/L. This study is classified as supplemental because a 

definitive NOAEC was not achieved.

Invertebrates, Acute Toxicity

43528001

Murrell et al (1994) exposed < 24h old Daphnia magna to TM (98.8%) for 48 hours in a static test 

system. Ten daphnids were exposed to a series of 5 test concentrations (plus solvent and negative 

controls) in each of 2 replicate containers. Mean measured concentrations were 8.4, 17, 26, 41, and 64 

mg ai/L and averaged 65% of nominal). Concentrations were stable from 0 to 48 hours. Immobility was 

0% at 26 mg ai/L and below. At 41 and 64 mg ai/L, 25% and 90% immobility occurred after 48 hours. A 

48-h EC50 of 48 mg ai/L was determined from this test, which is over two orders of magnitude above the 

solubility of TM. This study is considered supplemental because solvent concentrations of 1.06 ml/L 

exceeded the limit of 0.1 ml/L and surface films were observed in all test vessels at >17 ppm mean 

measured concentration at 48 ppm without centrifugation prior to analysis. 

00156120

Takimoto and Kagoshima (1982) exposed D. pulex to 1.0, 1.8, 5.6, 7.8, and 10 mg ai/LTM (99.8%) in a 

static system for 24 hours. Twenty daphnids were exposed/treatment among 4 replicates. Concentrations 

were not measured in this study. No immobilization occurred at 1.0 mg ai/L, but 20%, 80%, 100%, 100% 

and 100% immobilization occurred at 1.8, 5.6, 7.8 and 10 mg ai/L, respectively. No precipitate was 

reported in test solutions, however, a non-standard solvent was used (10 parts dimethylsulfoxide and 10 

parts polyoxyethylene hydrogenated castor oil) at a concentration (0.15 ml/L) that exceeded the 

recommended 0.1 ml/L level. This study is classified as supplemental because the test duration was less 

than recommended in guidelines and test concentrations were not measured. Furthermore, no reported 

data on temperature range and photoperiod and no total residual chlorine measurement of dilution water 

(dechlorinated tap water)

47837501

Dionne, E. (1998) exposed 20 D. magna (< 24h) to DM-TM (a degradate of TM) in a static system over a 

period of 48 hours (five daphnia/replicate). Nominal concentrations were 16, 27, 45, 75 and 125 mg 

a.i./L. In addition, a dilution water control was tested (solvents were not used so a solvent control was not 

necessary). For analytical verification of the test item, samples were taken at 0 and 48 hours from all 

concentrations. QA spike results indicate recovery of 96% to 104% respectively using high performance 

liquid chromatographic with ultraviolet detection (HPLC/UV) procedure. Immobilization and signs of 

toxicity were assessed daily. Temperature, pH and dissolved oxygen concentrations were also measured 

daily. Alkalinity, hardness, and conductivity were measured in a sample of the dilution water at test 

initiation.

The test substance was stable over 48 hours although measure concentrations were 67 – 76% of nominal. 

Regulatory endpoints are reported as mean measured concentrations. All water quality parameters 

remained within acceptable limits. Test solutions were observed to be clear and colorless throughout the 

exposure period. Following 48 hours of exposure (test termination), no immobilization or adverse effects 
133

were observed among daphnids exposed to any treatment level tested or the control. Based on these

results, the 48-hour EC50 was empirically estimated to be greater than 95 mg a.i./L, the highest

concentration tested. The NOAEC was determined to be 95 mg a.i./L. This study is considered 

acceptable.

48341929

Saltwater mysids (Americamysis bahia) <24 hours old were exposed to nominal concentrations of 63, 

125, 250, 500 and 1000 ug ai/L, a negative control (dilution water), and a solvent control (0.1 mL/L 

dimethylformamide) for 96 hours under static-renewal conditions (Palmer et al 2010). Two replicate test 

chambers were maintained in each treatment and control group, with 10 mysids in each test chamber, for 

a total of 20 mysids per concentration White precipitate was observed on the solution surface of the 1000 

ug a.i./L nominal test concentration at preparation. Therefore, the 1000 ug a.i./L solutions were filtered 

through a glass microfiber filter. No precipitate or visual evidence of insoluble material was noted in any 

of the test chambers. Mean measured test concentrations for this study were 60, 121, 230, 458 and 742 ug 

a.i./L, representing 95, 97, 92, 92 and 74% of nominal concentrations. There was 10% (one animal in 

each replicate) mortality among the mysids in the negative control group. All other mysids in the negative 

control and solvent control groups appeared normal throughout the test. A single mortality occurred in the 

60 ug a.i/L treatment group, but it was deemed not treatment related due to the absence of mortality and 

signs of toxicity in the next higher treatment group. All remaining mysids in the 60 and 121 ug a.i./L 

treatment groups appeared normal throughout the test, with no mortalities or overt signs of toxicity 

observed. Percent mortality in the 230, 458 and 742 ug a.i./L treatment groups at test termination was 

15,65 and 100%, respectively. Surviving mysids in the 458 ug a.i./L treatment group appeared small in 

comparison to control organisms. The 96-h LC50 is 327 ug ai/L and the NOAEC is 121 ug ai/L. This 

study is considered acceptable and classifies TM as highly toxic to saltwater invertebrates.

48341928

Gallagher et al (2010) exposed Eastern oysters (Crassostrea virginica ) in natural seawater to a geometric 

series of five test concentrations, a negative control (dilution water) and a solvent control (0.1 mL/L 

HPLC-grade dimethylformamide) for 96 hours under flow-through conditions. Prior to use, the 20 ppt 

seawater was filtered to 0.45 um to remove fine particles. One test chamber was maintained in each 

treatment and control group with 20 eastern oysters in each test chamber. Nominal test concentrations 

selected were 0.038, 0.075, 0.15, 030, and 0.60 mg ai/L. Just prior to initiation, recently deposited shell 

was removed by grinding the periphery of the oysters. The oysters then were indiscriminately assigned to 

exposure chambers at test initiation. Observations of mortality and other signs of toxicity were made 

approximately 5, 24, 48, 72 and 96 hours (±1 hour) after test initiation, and shell deposition was measured 

at 96 hours.

Mean measured test concentrations for this study were 0.036, 0.070, 0.14, 0.28, and 0.54 mg a.i./L,

and represent 95, 93, 93, 93 and 90% of nominal concentrations, respectively. A slight precipitate was 

observed in the highest treatment (0.60 mg ai/L nominal), and centrifugation confirmed that 72% of test 

substance was in solution. No precipitates were observed other test concentrations. All oysters appeared 

normal throughout the 96-hour exposure period and no mortalities occurred. Mean shell deposition in the 

0.036, 0.070, 0.14, 0.28 and 0.54 mg a.i./L treatment groups was -18.4, 14.8, 21.8, 64.3 and 85.2%, 

respectively, relative to pooled controls. The 96-hour EC50 was calculated to be 0.22 mg a.i./L, with a 

95% confidence interval of 0.18 to 0.29 mg a.i./L. The NOAEC was 0.14 mg a.i./L.
134

Invertebrate, Chronic Toxicity

41400303

Burgess (1989) conducted a freshwater invertebrate (D. magna) lifecycle test with TM TGAI (97.6%) 

Forty daphnids (10/rep.) were exposed throughout their life cycle to mean-measured concentrations of 

TM of 0.026, 0.062, 0.089, 0.19, and 0.39 mg ai/L, representing 108, 129, 89, 95, and 98% of the nominal 

values, respectively. Survival was significantly different between the pooled controls and the mean 

measured exposure levels 0.19 and 0.39 mg/L. The mean young/adult reproduction day after 21 days was 

significantly greater in the solvent control (4.7 young/adult reproduction day) compared to the negative 

control (3.8 young/adult reproduction day). Therefore, the original analysis of the data compared results 

to the solvent control, which indicated significant effects at mean-measured concentrations of 0.062, 

0.089, and 0.19 mg ai/L. Based on reproductive effects, the NOAEC and LOAEC are estimated at 0.026 

and 0.062 mg ai/L. respectively. Raw data were not provided in the study report from which to recalculate 

the endpoints according to comparisons to negative controls (current EFED policy). However, the 

apparent solvent effect resulted in an increase in reproduction and the LOAEC (3.2 young/reproduction 

day at 0.062 ug ai/L) still represents a 15% reduction relative to the negative controls (3.8 

young/reproduction day). Therefore, it is reasonable to consider the effects at 0.062 mg ai/L biologically 

significant even if recalculation resulted in no statistically significant difference relative to negative 

controls. This study is classified as supplemental because raw data on reproduction were not included in 

the study report). 

48341933

Four replicate chambers containing 15 mysids each were exposed to a geometric series of five test 

concentrations, a negative control (dilution water) and a solvent control (0.1 mL/L dimethyl-formamide) 

under flow-through conditions for 38 days (Palmer et al 2009). The mean measured test concentrations 

for this study were 3.9, 8.2, 17, 35 and 63 ug a.i./L, representing 70, 75, 74, 78 and 70% of nominal 

concentrations, respectively. No precipitates or visual evidence of insoluble material was observed in any 

control or treatment solution. On Day 15 of the test, after mysids attained sexual maturity, male and 

female adults were paired in each treatment and control group, with a maximum of five reproductive pairs 

per replicate. No treatment related effects were observed on mysid survival (mean measured NOAEC = 

63 ug ai/L). The overall survival of first generation control mysids (negative and solvent controls 

combined) over the entire exposure period was 73.3%, which is above the acceptance criteria of >70% 

survival (although solvent control survival was slightly below at 68.3%). Time to first brood was 

unusually long in controls and all treatments (mean occurring >27days), which may have resulted in 

extension of the test duration from the usual 28 to 38 days. Male and female total length were 

significantly reduced by ~5% relative negative controls at 35 ug ai/L. Significant reductions in dry weight 

relative to the negative control occurred at 63 ug ai/L (females; 30% reduced) and 35 ug ai/L (males, 27% 

reduced). The mean number of young produced per female in the negative and solvent controls was 4.4 

and 4.3, respectively and was sufficient to evaluate reproductive effects according to ASTM guidelines. 

A statistically significant treatment related effect on # young/reproductive day was observed at 63 ug 

ai/L; However, the study demonstrated exceptionally poor statistical power due to high variability within 

treatments in this endpoint (MDD =107% relative to negative controls). Based on a 50% reduction in # 

young/reproductive day at 8.2 ug ai/L, the statistically-based endpoint was considered to be unreliable and 

inferred a biologically significant NOAEC at 3.9 ug ai/L. This study is considered supplemental due to 

the low statistical power associated with the reproductive endpoints and unusually long time required for 

first brood resulting in an extension of the test duration by 10 days.
135

Benthic Invertebrate Toxicity

48341931 

Thomas et al (2010) exposed amphipods to a geometric series of five test concentrations of TM TGAI 

(95.6%), a solvent control and a negative control for 10 days under flow-through test conditions. Eight 

replicate test compartments were maintained in each treatment and control group, with 10 amphipods in 

each test compartment, for a total of 80 amphipods per test concentration. An additional two replicates 

were added in each treatment and control group for analytical sampling of sediment, pore water and 

overlying water. Nominal test concentrations were 6.3, 13, 25, 50 and 100 mg a.i./kg sediment dry 

weight. Formulated sediment (81% sand, 8% silt, and 11% clay; 2.5% total organic carbon and 

moderately-hard well water freshwater were used in this study. Temperature was 23 + 1C during the 

study, dissolved oxygen concentrations in overlying water were > 80% (6.8 mg/L) of saturation and pH 

ranged from 8.3 to 8.5.

Amphipods were fed 1.0 mL of YCT.

The mean measured test concentrations were 4.8, 12, 24, 48 and 103 mg a.i./kg. from the 6.3, 13, 25, 50 

and 100 mg a.i./kg treatment groups, respectively. Mean percent survival after 10 days was 86, 93, 89, 

90, 85, 80, and 95% for the negative control, solvent control, and mean-measured 4.8, 12, 24, 48, and 103 

mg ai/kg sediment levels, respectively. The 10-day LC50 was >103 mg ai/kg, and the NOAEC for 

survival was 103 mg ai/kg. This study is considered acceptable.

48341935

During the initial study, groups of amphipods (Leptocheirus plumulosus) were exposed to a geometric 

series of five test concentrations, a solvent control and a negative control for 10 days under static test 

conditions. During the continuation study, groups of amphipods were exposed to a geometric series of 

three test concentrations, a solvent control and a negative control for 10 days under static conditions. Five 

replicate test chambers were maintained in each treatment and control group, with 20 amphipods in each 

test chamber, for a total of 100 amphipods per test concentration. Nominal definitive test concentrations 

were 6.3, 13, 25, 50 and 100 mg a.i/kg of sediment based on the dry weight of the sediment. The nominal 

concentrations for the continuation study were 0.78, 1.6 and 3.1 mg a.i./kg. Samples of the sediment used 

in both the initial trial and the continuation study were determined to have an organic carbon content of 

2.4 and 2.8%, respectively. The mean measured concentrations (day 0 and day 10) for the 6.3, 13, 25, 50 

and 100 mg a.i./kg treatment groups were 5.3, 11, 23, 48 and 97 mg a.i./kg. The mean measured 

concentrations (day 0 and 10) for the 0.78, 1.6and3.1 mg a.i/kg treatment groups were 0.45, 1.1 and 2.1 

mg a.i./kg. The mean survival of Leptocheirus in the negative control, solvent control, 5.3, 11, 23, 48 and 

97 mg a.i./kg treatment groups were 96, 98, 61, 33, 18, 17 and 0%, respectively, at test termination. The 

mean percent survival of Leptocheirus in the negative control, solvent control, 0.45, 1.1, 2.1, mg a.i./kg 

treatment groups were 96, 95, 89, 96 and 95%, respectively and were not significantly different. The 

results of the definitive test and the continuation study were combined for the determination of the NOEC 

(2.1 mg ai/kg sediment), LOAEC (5.3 ug ai/kg sediment) and LC50 (7.05 mg a.i./kg sediment). This study 

is considered supplemental because the NOAEC and LOAEC were derived from separate studies. 

Therefore, there is some uncertainty regarding the possible effect of different batches of organisms on the 

relationship between the unbounded LOAEC from the first study and the unbounded NOAEC from the 

second study. Given that both studies were conducted in the same lab over very similar time periods with 

the same sediment and organism source, these endpoints are still considered scientifically valid and useful 

for risk assessment. 

48737504

Putt (2002) conducted a 28-d chronic sediment toxicity test of the freshwater midge, Chironomus riparius, 
136

according to OECD 219 protocol (spiked water). Twenty, 1st instar midge (3-days post hatch) were added 

to each of 8 replicate test chambers (4 for biological measurements, 4 for chemical measurements) with 

gentle aeration. Prior to organisms addition, field-collected test sediments (2.4% TOC, 94% sand, 6% 

silt, 0% clay) and overlying water (soft well water) were condition in test vessels for 7 days. Temperature 

was 19-21C, dissolved oxygen was >7.9 mg/L and pH in overlying water ranged from 5.5-7.7. Midge 

larvae were fed finely ground fish flake food daily during the test. 

Measured concentrations of total [14C] at 1-hour in the 0.063, 0.13, 0.25, 0.50 and 1.0 mg a.i./L treatment 

levels were 0.064, 0.13, 0.23, 0.47 and 0.76 mg a.i./L, respectively. Total [14C] concentrations decreased 

dramatically by day 7 and were generally less than 20% of the targeted [14C] concentration in the 

overlying water for the remainder of the exposure. Measured concentrations of total [14C] at 1-hour in the 

0.063, 0.25 and 1.0 mg a.i./L treatment levels were 0.00037, 0.00068 and 0.0057 mg a.i./L, respectively. 

The total [14C] in pore water increased by more than 10-fold during the exposure. On test day 28 (test 

termination), measured concentrations of total [14C] in the 0.063, 0.25 and 1.0 mg a.i./L treatment levels 

were 0.0048, 0.019 and 0.16 mg a.i./L, respectively. Measured concentrations of tolclofos-methyl at 1-

hour in the 0.063, 0.13, 0.25, 0.50 and 1.0 mg a.i./L treatment levels were 0.020, 0.024, 0.063, 0.10 and 

0.26 mg a.i./kg, respectively. Total [[14C] concentrations in the sediments had generally increased 5-fold 

by day 7. Total [14C] sediment concentrations then increased slightly or decreased slightly

throughout the remainder of the study. These results are consistent with the expected partitioning of TM 

from the overlying water into the sediments and pore water. Results indicate development rate was 

significantly reduced by 3.4% relative to negative controls at 0.188 mg ai/L porewater (mean measured), 

resulting in a NOAEC of 0.013 mg ai/L pore water (0.186 mg ai/kg dw in sediment, 7.7 mg ai/kg-OC). 

Mean percent emergence in test treatments (79-86%) was not affected at any test concentration relative to 

controls (86%). Reproductive endpoints were not included in this study, per OECD guidelines. 

However, a full life cycle test using spiked sediments with measurement of reproduction is required per 

USEPA pesticide registration for TM. Therefore, this study is considered supplemental.

Aquatic Plant Toxicity

48737506

The toxicity of TM TGAI (97.8%) to the freshwater green alga, Scenedesmus subspicatus, was 

investigated according to OECD Guideline #201 (Sayers 2003). After the test solutions (TM added to 

AAP medium) were added to the test flasks (100 ml per flask), a 0.730-ml inoculum of S. subspicatus

cells (cell density of approximately 137 x 104cells/m), was aseptically introduced into each flask. This 

inoculum provided the required initial (0 hour) cell density of approximately1.0 x 104 cells/ml. During 

the 72-h exposure, temperature ranged from 23 to 24°C, continuous illumination was provided at 7000 to 

8900 lux (650 to 825 foot candles), and a shaking rate of 100 rpm was applied.

Due to the limited solubility of tolclofos-methyl (0.708 mg/L), the mean measured concentrations ranged

from 53 to 97% (decreasing with increasing tolclofos-methyl concentration) and defined the treatment 

levels as 0.13, 0.22, 0.39, 0.69 and 1.1 mg a.i./L. Analysis of centrifuged samples indicated no impact of 

algae on test concentrations. The effect of TM on inhibition of total biomass (area under the growth 

curve) and average growth rate (uave) were evaluated. Based on mean measured concentrations, the 72-hr 

EC50 value for total biomass was determined to be 0.78 mg ai/L with 95% confidence intervals of 0.62 to 

0.92 mg ai/L. The 72-h NOAEC was determined to be 0.18 mg a.i./L. This study is classified as 

supplemental since OSCPP test guidelines (850.5400)require that a 96-h study be conducted with aquatic 

algae.
137

48737505

Hoberg (1998) evaluated the effects of DM-TM (a degradate of TM) to freshwater green alga S. 

subspicatus in replicate 250-mL flasks, three flasks (A, B and C) per treatment level and the controls. 

0.35-mL inoculum of algal cells, at a density of approximately 2.84 x 104cells/mL, was aseptically 

introduced into each flask. This inoculum provided the required initial (0 hour) cell density of 

approximately 1.0 x 104cells/mL. At each subsequent 24-hour interval, cell counts were conducted on 

each replicate vessel of each treatment solution and the controls using a hemacytometer and compound 

microscope.

The test substance was stable over 72 hours although measure concentrations were 75-77% of nominal. 

Light intensity (4100-5000 lux) was slightly lower than OECD guideline (5000 lux) based on 

optimization with this laboratory/light source. Algae appeared to be on log growth phase throughout the 

test. Cell density, biomass and growth rate were reduced by a maximum of 8.3, 8.6 and 1.3%, 

respectively, in the highest test concentration (97 mg DM-TM /L). As a result, EC50 values for all three 

endpoints were > 97 mg/L. NOAECs for cell density, biomass and growth rate were 23, 12 and 23 mg 

DM-TM/L, respectively. The test generally conformed to OECD guidelines and no guideline deviations 

were reported by the study authors. However, for USEPA/OPP purposes, a 96h duration is required 

(850.5400). Therefore, this study is considered scientifically sound, but supplemental.

00156121

Takimoto and Ysutaniya (1983) evaluated the effects of TM TGAI (98.3%) on the green algae, 

Scenedesmus quadricauda, in triplicate 500ml flasks at dose levels of 0.01, 0.032, 0.1, 0.32, 1.0, 5.6 mg 

ai/L of Closterium medium according to OECD guideline #201. Test solutions were inoculated with a 

suspension of the algae (1x104colonies/ml) at exponential growth phase along with a solvent control 

which contained 50 ul of added DMSO. Flasks were plugged with silicone, and incubated at 20±2°C 

with fluorescent light of about 5000 lux under shaking at 100 rpm. Test concentrations were not 

measured analytically. The significant reduction of biomass (p<0.05) was observed at 0.1 mg/1 and above 

on day 3 and later of incubation, however, these adverse effect did not inhibit biomass by 50%. The 

NOAEC (biomass) was determined to be 0.032 mg ai/L. The 7-d EC50 was determined to be > 5.6 mg 

ai/L, which exceeds solubility of TM in water (0.7-1.0 mg ai/L). No information about the formation of 

precipitates (or lack thereof) was provided by the study authors. No significant reduction in growth rate 

(maximum or relative) was observed relative to controls. Furthermore, no morphological abnormalities in 

algal cells were observed at any treatment during the test. This study is considered supplemental due to 

apparent lack of a negative control from which to evaluate the potential effect of the solvent on algae 

growth.

Avian Acute Oral Toxicity

00156112

Roberts and Haskins (1981) evaluated the acute oral toxicity of TM TGAI (99.8%) to mallard duck (Anas 

platyrhynchos) using a limit dose of 5000 mg ai/kg bw followed by a 14-d observation period. After 15 

hours fasting, 10 16-week old mallard ducks were tested in controls (receiving just corn oil) and 20 were 

tested at the limit dose. Cage size or # organisms/cage was not specified. Temperature ranged from 13-

26C and a natural daylight photoperiod was utilized. No mortalities in control or at the 5000 mg/kg test 

level. Weight changes were variable for all birds, but within normal limits. This study is classified as 

acceptable and results indicate that TM is practically non-toxic to the mallard duck on an acute, oral basis.

00156113

Roberts and Haskins (1982) evaluated the acute oral toxicity of TM TGAI (99.8%) to bobwhite quail 
138

(Colinus virginianus) using a limit dose of 5000 mg ai/kg bw followed by a 14-d observation period. 

After 15 hours fasting, 10 16-week old quail were tested in controls (receiving just corn oil) and 20 were 

tested at the limit dose. Five birds were housed per cage but cage size was not specified. Temperature 

ranged from 13-26C and a natural daylight photoperiod (17h daylight) was utilized. No mortalities in 

control or at the 5000 mg/kg test level. Weight changes were variable for all birds, but within normal 

limits. This study is classified as acceptable and results from this study indicate that TM is practically 

non-toxic to the bobwhite quail on an acute, oral basis.

Roberts and Haskins (1981) also studied the acute oral toxicity of TM TGAI (99.8%) to ring necked 

pheasant (Phasianus colchicus) using a limit dose of 5000 mg ai/kg bw followed by a 14-d observation 

period. After overnight hours fasting, 10 0.94-1.34 kg old pheasants were tested in controls (receiving just 

corn oil) and 20 were tested at the limit dose. Cage size and #birds/cage were not specified. Temperature 

ranged from 13-30C and a natural daylight photoperiod (17h daylight) was utilized. Only one mortality 

occurred among the 20 test birds. This was not considered to be dose related. Body weights were variable, 

but considered within normal limits. The acute oral LD50 is estimated to be > 5000 mg ai/kg bw. This 

study is classified as acceptable and results from this study indicate that TM is practically non-toxic to the 

pheasant on an acute, oral basis.

48341936

The acute oral toxicity of TM TGAI (95.6%) to zebra finches, Poephila guttata, was assessed over 14 

days using a limit test design. TM was administered to the birds by a 14 gauge cannula at nominal doses 

of 0 (vehicle control), and 2000 mg ai/kg bw. There was no mortality in the control or the treatment 

group. There were no signs of toxicity/abnormal behaviors with the exception of regurgitation. Within 

the first hour of dosing, 2/12 birds (17%) at the 2000 mg ai/L dose regurgitated. The remaining 10 birds 

that did not regurgitate the test material were unremarkable. There were no significant reductions in % 

body weight gain for either males or females nor were there any clinical or behavioral signs of 

intoxication. Gross necropsies were not performed and were not necessary based on the lack of sublethal 

effects.

The 14-day acute oral LD50 and NOAEL were determined to be >2000 and 2000 mg ai/kg bw, 

respectively, based a lack of mortality, minimal abnormal behavior, and affected % body weight gain. 

According to the US EPA classification, TM would be classified as practically non-toxic to Poephila 

guttata on an acute oral basis. Although there was some regurgitation (2/20 birds), the frequency was low 

and does not impact interpretation of the study results (i.e., LD50 is still > 5000 mg ai/kg bw). This 

toxicity study is classified as scientifically sound/acceptable and thus satisfies the guideline requirement 

for an acute oral avian toxicity study with a passerine species. 

Avian Subacute Dietary Toxicity

00156115

Beavers (1985) evaluated the dietary toxicity of TM TGAI (97.7%) to 10-d old mallard duck (A. 

platyrhynchos) fed a diet containing 0 (2% corn oil), 562, 1000, 1780, 3160 and 5620 ppm TM. Ten 

ducks were tested per treatment in cages (72 cm x 90 cm L x 24 cm H) during a 5-d exposure and a 3-d 

observation period. Temperature was 81 F (+/- 2F), photoperiod was 17 hours, and humidity was 57%. 

No mortalities occurred, therefore, the dietary LC50 is greater than 5620 ppm. Food consumption and 

weight gain were similar at all test levels. This study is classified as acceptable and results indicate that 

TM is practically non-toxic to the mallard duck on an subacute, dietary basis.

00156116

Beavers (1985) evaluated the dietary toxicity of TM TGAI (97.7%) to 12-d old bobwhite quail (C. 
139

virginianus) fed a diet containing 0 (2% corn oil), 562, 1000, 1780, 3160 and 5620 ppm TM. Ten quail 

were tested per treatment in cages (72 cm x 90 cm L x 24 cm H) during a 5-d exposure and a 3-d 

observation period. Controls contained 50 quail. Temperature was 100 F (+/- 2F), photoperiod was 17 

hours, and humidity was 57 A total of 6 birds (out of 50) in the controls died (12%). This was attributed 

to aggression as was evidenced by toe-picking. There was 20% mortality (2 of 10) at the 1000 ppm

level. One occurred at 4 days, the second at six days. The study author indicated the mortalities did not 

appear to be dose related, since no mortalities occurred at higher levels. There was no apparent effect on 

body weight or feed consumption. This study is classified as acceptable and results indicate that TM is 

practically non-toxic to the mallard duck on a subacute, dietary basis.

Avian Chronic Toxicity

40190202

Beavers et al (1987) evaluated the chronic dietary toxicity of TM (97.7%) on 41 week old mallard ducks. 

Three groups, 16 replicates (pairs) per group, of pen-reared mallard ducks approaching their first breeding 

season were fed a diet containing 500, 2500 or 7500 ppm of TM. A fourth group was fed a control diet 

containing 0.09% corn oil, the amount used as a carrier for the test material. No treatment related 

mortalities or overt signs of toxicity occurred at 500 ppm. At 2500 ppm, 3 of the 32 adults died; and at 

7500, 10 died. At both 2500 and 7500, lower limb weakness and other toxic symptoms were observed. 

Analysis of variance indicates that at 2500 ppm, statistically significant reductions were observed in 

number of eggs laid, eggs set, viable embryos, eggs hatched. This study is classified as acceptable.

40190201

Beavers and Jaber (1987) ) evaluated the chronic dietary toxicity of TM (97.7%) on 22 week old 

bobwhite quail. Three groups, 16 replicates (pairs) per group, of pen-reared bobwhite quail approaching 

their first breeding season were fed a diet containing 500, 2500 or 7500 ppm of TM. A fourth group was

fed a control diet containing 0.09% corn oil, the amount used as a carrier for the test material. No 

treatment related mortalities or overt signs of toxicity occurred. Five adults mortalities occurred, none of 

which appeared to be treatment related. There were no statistically significant differences in adult body 

weight of males between control and any treatment groups. Females, at 7500 ppm exhibited a slight, but 

statistically significant reduction of body weight during week 7. Feed consumption appears to have been 

reduced at the 7500 ppm level. There was no apparent effect on treatment parameters or sublethal effects 

at the 500 ppm concentration. When compared to the control group, there was a significant reduction in 

the number of eggs laid in both the 2500 and 7500 ppm concentrations. The reduction in number of eggs 

laid continued to result in a reduced number of eggs set, viable embryos, live embryos and eggs hatched 

at the 2500 and 7500 ppm levels. There was no apparent effect on cracked eggs. This study is classified as 

acceptable, and the NOEL for TM is 500 ppm.

Mammals, Acute Toxicity

00156128

Segawa et al (1978) evaluated the acute oral toxicity of TM (97%) to the rat, (Rattus norvegicus) and the 

mouse (Mus musculus). Ten male and female Sprague-Dawley rats approximately 7 weeks old and 

weighing 200 to 260 g (males) or 170 to 210 g (females) and 10 male and female mice (7 weeks old) 

weighing 20 to 24 g (males) or 18 to 20 g (females), were used in these studies. TM was dissolved in corn 

oil and administered to 10 rats/dose level/sex and 10 mice/dose level/sex (gavage) in concentrations: 

1000, 2500, 3750 and 5000 mg/kg bw (rats) and 1000, 1500, 2000, 3000, 4000 mg/kg (mice). The 

animals were kept in a room with a temperature of 23 + 1 °C and with a relative humidity of 60 + 5 

percent. Food (CE-2 type) and water were available ad libitum. All animals were observed daily for signs 
140

of toxicity/mortality.

Rats (both sexes) receiving the dose levels of 3750 or 5000 mg/kg developed a variety of toxic symptoms 

which included: irregular respiration, dyspnea, piloerection, decreased motor activity, and ataxia of the 

hind limb or whole body, 3 to 4 hours post-administration. Mortality was observed only in the high dose 

tested (5000 mg/kg) in both sexes of rats and total mortality reached 5/10 (or 50%) in male rats and 6/10 

(or 60%) in female rats by the end of the 14-day observation period. All toxic signs disappeared from 

surviving animals 3 to 8 days postadministration. The acute oral LD50 for male rats was calculated to be 

4900 mg/kg bw using the binomial method 

Mice (male and female) receiving 1500 mg/kg or higher developed the same toxic symptoms as those 

reported for rats. Maximum mortality occurred at the highest test concentration (4000 mg ai/kg bw) 

resulting in an LD50 of 3500 mg ai/kg bw. Both the rat and mouse studies are classified as acceptable and 

indicate that TM is practically non-toxic (rat) and slightly toxic (mouse) on an acute oral basis.

00156124

Kynoch (1985) studied the acute oral toxicity of TM to male and female HC/CFY Remote SpragueDawley rats. Animals (4 to 6 weeks old and weighed 100 to 135 g) were acclimated for at least 7days to 

experimental conditions prior to testing. For the main study, five male and five female rats were treated 

with 5 g TM /kg bodyweight. All animals were housed in metal cages separately for each sex, identified 

by cage number and ear punching, and kept in an animal room with a temperature of 21 to 22°C, relative 

humidity of 55 percent, approximately 15 air changes/hour, and a l2-hour light/ dark cycle. The animals 

had free access to food (rodent diet-Labsure LAD I) and water throughout the study. Food was withheld 

from all test animals approximately 12 hours prior to and 4 hours after dosing. Animals were observed for 

14 days for signs of toxicity and/or mortality. Body weights were recorded on days 1, 8, or 15 on study. 

At sacrifice (day 15) all animals were examined macroscopically.

The single high-dose level (5 g/kg) tested in the main study did not result in mortality of the male or 

female rats. Clinical signs of toxicity were observed in all animals tested and included piloerection and 

hunched posture shortly after dosing with complete recovery in 5 days. Body weight gains were observed 

in all test animals of the main study and at sacrifice none of these animals had any abnormal macroscopic 

lesions. Thus, the acute oral LD50 for male and female rats was higher than 5 g/kg, indicating TM is 

practically non-toxic to the rat on an acute oral basis. This study is classified as acceptable.

Mammals, chronic and subchronic toxicity

41422901

Morseth (1987) assessed the developmental toxicity of TM when administered by gavage to rats on 

gestation days 6 through 15, inclusive. Doses were 0 100, 300, and 1000 mg /kg bw/d. No clinical signs 

were noted during the twice daily cage-side observations., There was a non-significant dose-related 

decrease in corrected body weight gains during the dosing period and during the entire gestation period, 

when compared to the controls. The only finding of statistical significance was unossified 6th sternebra, at 

the 1,000 mg/kg/day group, when compared to the controls. No fetal deaths were reported in any of the 

groups. There were no external variations observed The NOAEL from this study is 300 mg ai/kg bw/d.

00156138

Pence et al (1979) studied the effect of TM on beagle dogs via dietary exposure. Animals were 5-7 

months old at testing and ranged in weight from 6.7 to 12.4 kg (males) and 5.8 to 10.2 kg (females). Six 

male and female dogs were tested per dose. TM was administered in the diet at concentrations of 0, 200, 
141

600, and 2000 ppm for 6 months. Toxic effects observed at 2000 ppm included reduced body weight 

gain, hematocrit, hemoglobin, and erythrocyte count in both sexes. Alkaline phosphatase and absolute and 

relative liver weights were increased in both sexes. Plasma cholinesterase was significantly reduced in 

high dose females at all report periods. These data support a NOEL of 600 ppm.

00156137

Suzuki et al. (1978) evaluated the effect of 9 months exposure to TM in the diet on mice. Mice were 

exposed to 0, 10, 30, 100 and 3000 ppm TM (1.20, 3.78, 12.20, 513 mg/kg/day for males and 1.42, 4.14, 

13.80, and 564 mg/kg/ day for females respectively). Both body weight and body weight gain were 

reduced in the highest dosage group (3000 ppm) of both sexes, although food consumption was increased 

in these groups. The NOAEL (body weight/weight gain) is 100 ppm. The only other significant toxicity 

observed in this study was plasma cholinesterase inhibition in female mice at doses of 30 ppm and above. 

The study is classified as supplementary because the analysis for concentration, homogeneity, and 

stability of the test compound in the diet was not submitted with the study. 

Toxicity to Honeybee

41794202

Winter et al (1990) evaluated the acute contact toxicity of TM (97.7%) to young adult honeybees (Apis 

mellifera). All test bees were 1 to 4 days old at initiation of the study and were apparently healthy. On the 

day of study initiation, all bees that had emerged were immobilized with N2 and at least 25 bees were 

placed into each test chamber containing 50% sugar solution. The photoperiod was eight hours of light 

per day. Ambient temperatures in the test room at the time of observations ranged from 22 to 23 C. Five 

treatment levels, 13, 22, 36, 60, and 100 ug/bee, were tested along with a solvent control and a negative 

control. Two replicates were tested at each dosage, with 25 bees per replicate. The solvent control bees 

received a volume of acetone equal to the largest volume used during the test. The study authors found 

that TM was practically nontoxic to honey bees, with an LD50 greater than 100 ug per bee. This study is 

classified as acceptable.

00163557

A second study was conducted on the toxicity of TM to honeybees (A. mellifera) on an acute contact 

basis. TM was diluted with acetone and topically applied on the dorsal thorax of bees at the ratio of 1 ug 

per bee. The treated bees were kept in a polyethylene cup with food. Thirty bees were used for each dose. 

Mortality was observed 24 hours after treatment. The study authors found that tolclofos-methyl was 

relatively nontoxic to honey bees, with an > 100 ug per bee. There were a number of deficiencies in the 

study report (e.g., environmental conditions during test, type of food provided, and method used to 

immobilize test bees, etc.). Also, the test was run for 24 hours instead of the recommended 48hours. This 

study is classified as supplemental.
142

APPENDIX E. RISK QUOTIENT METHOD AND LEVELS OF CONCERN 

The Risk Quotient Method is the means used by the Office of Pesticide Programs (OPP), Environmental Fate and 

Effects Division (EFED) integrates the results of exposure and ecotoxicity data. For this method, Risk Quotients 

(RQs) are calculated by dividing exposure estimates by the acute and chronic ecotoxicity values (i.e., RQ = 

EXPOSURE/TOXICITY). These RQs are then compared to OPP's levels of concern (LOCs) (see Table E.1). 

These LOCs are criteria used by OPP to indicate potential risk to non-target organisms and the need to consider 

regulatory action. EFED has defined LOCs for acute risk, potential restricted use classification, and for endangered 

species.

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

organisms. LOCs currently address the following risk presumption categories: 

(1) Acute - there is a potential for acute risk; 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 – there is a potential for acute risk to endangered species, regulatory action 

may be warranted; and 

(4) Chronic risk – there is a potential for chronic risk, regulatory action may be warranted. 

Table E.1. Level of concern (LOC) by risk presumption category (EPA, 2004).

Risk Presumption RQ LOC

Mammals and Birds

Acute Riska EECb/LC50 or LD50/sqftcor LD50/dayd0.5

Acute Restricted Usee EEC/LC50 or LD50/sqft or LD50/day (or LD50

<50 mg/kg)

0.2

Acute Listed Speciesf EEC/LC50 or LD50/sqft or LD50/day 0.1

Chronic Risk EEC/NOEC 1

Terrestrial Invertebrates

Interim Acute Listed Speciesi EECj/ LD50

k

0.05

Aquatic Animals

Acute Risk EECg/LC50 or EC50 0.5

Acute Restricted Use EEC/LC50 or EC50 0.1

Acute Listed Species EEC/LC50 or EC50 0.05

Chronic Risk EEC/NOEC 1

Terrestrial Plants and Terrestrial Plants in Semi-Aquatic Areas Plants

Acute Risk EEC/EC25 1

Acute Listed Species EEC/EC05 or NOEC 1
143

Table E.1. Level of concern (LOC) by risk presumption category (EPA, 2004).

Risk Presumption RQ LOC

Aquatic Plants

Acute Risk EECh/EC50 1

Acute Listed Species EECg/EC05 or NOEC 1

a

Potential for acute toxicity for receptor species if RQ > LOC (EPA, 2004).

bEstimated environmental concentration (ppm) on avian/mammalian food items.

cmg/ft2

dmg of toxicant consumed per day

e

Potential for acute toxicity for receptor species, even considering restricted use classification, if RQ > LOC (EPA, 2004).

f

Potential for acute toxicity for listed species of receptor species if RQ > LOC (EPA, 2004).

gEEC = ppb or ppm in water 

hEEC = lbs a.i./A

i

Potential for acute toxicity for listed species of receptor species if RQ > LOC (EPA, 2007).

j Estimated environmental concentration (ppm) calculated by T-REX for small or large insects.

k The toxicity value for terrestrial invertebrates is typically calculated by multiplying the lowest available acute contact LD50 for honeybees by 1 

bee/0.128g (which is based on the weight of an adult honeybee) to convert units to μg a.i./g of bee.

Literature Cited

U.S. EPA. 2004. U.S. Environmental Protection Agency. Overview of the Ecological Risk Assessment 

Process in the Office of Pesticide Programs, U.S. Environmental Protection Agency: Endangered and 

Threatened Species Effects Determinations. Office of Prevention, Pesticide, and Toxic Substances. 

January 23. 

U.S. EPA. 2007. U.S. Environmental Protection Agency. Interim Policy: Acute Endangered Species 

Level of Concern (LOC) for Terrestrial Invertebrates. Environmental Fate and Effects Division, Office of 

Pesticide Programs. Memorandum issued, May 15, 2007.
144

APPENDIX F. OUTPUT FROM T-REX MODEL (V 1.5)

1. Seed Treatment Rate for Root Vegetables and Cotton

Chemical:

Name of seed treatment formulation:

Percent AI in formulation: 100% 1 9.99

Tested Body

Weight (g)

Avian LD50: 2000.00 12 2159 Small (20g)

Avian repro. NOAEC: 500.00 2749 Medium (100g)

3883 Large (1000g)

Mammalian LD50: 3500.00 20 3761 Small (15g)

Mammalian NOAEL: 100.00 3043 Medium (35g)

1316 Large (1000g)

Small (15g) 13.11

Medium (35g) 10.61

Large (1000g) 4.59

Crop

Maximum 

Application 

Rate

Maximum Seed 

Application Rate Avian Nagy Dose

Mammalian Nagy 

Dose Available AI

(lbs ai/A) (mg ai/kg seed) (mg ai/kg-bw/day) (mg ai/kg-bw/day) (mg ai ft-2)

Small 123.45 103.35

Medium 70.40 71.43

Large 31.52 16.56

Acute (# 1) Acute (# 2) Chronic Acute (# 1) Acute (# 2) Chronic

corn, all or unspecified

0.06 0.00 0.98 0.03 0.00 7.88

Acute (# 1) Acute (# 2) Chronic Acute (# 1) Acute (# 2) Chronic

corn, all or unspecified

0.03 0.00 0.98 0.02 0.00 6.73

Acute (# 1) Acute (# 2) Chronic Acute (# 1) Acute (# 2) Chronic

corn, all or unspecified 0.01 0.00 0.98 0.01 0.00 3.61

† Acute RQ #1 = (mg ai /kg-bw/day) / LD50

Acute RQ #2 = mg ai ft-2 /(LD50*bw)

Avian Chronic RQ = mg kg-1 seed / NOAEL

Mammalian Chronic RQ = mg a.i./kg-bw/day / adjusted NOAEL

Avian (1000 g) Mammalian (1000 g)

Animal Size

corn, all or unspecified 0.0162 487.79 0.17

Crop

Tolclofos methyl

Rizolex Floable Fungicide

Density of product (lbs/gal):

Data inputs are in blue

Avian (100 g) Mammalian (35 g)

Avian (20 g) Mammalian (15 g)

Risk Quotients†

Endpoints Adjusted LD50 Size class for 

adjusted LD50 Reported

Adjusted NOAEL for Mammals
145

2. Seed Treatment Rate for all other crops 

Chemical:

Name of seed treatment formulation:

Percent AI in formulation: 100% 1 9.99

Tested Body

Weight (g)

Avian LD50: 2000.00 12 2159.27 Small (20g)

Avian repro. NOAEC: 500.00 2748.86 Medium (100g)

3882.87 Large (1000g)

Mammalian LD50: 3500.00 20 3760.99 Small (15g)

Mammalian NOAEL: 100.00 3043.05 Medium (35g)

1316.21 Large (1000g)

Small (15g) 13.11

Medium (35g) 10.61

Large (1000g) 4.59

Crop

Maximum 

Application 

Rate

Maximum Seed 

Application Rate Avian Nagy Dose

Mammalian Nagy 

Dose Available AI

(lbs ai/A) (mg ai/kg seed) (mg ai/kg-bw/day) (mg ai/kg-bw/day) (mg ai ft-2)

Small 24.69 20.67

Medium 14.08 14.29

Large 6.30 3.31

Acute (# 1) Acute (# 2) Chronic Acute (# 1) Acute (# 2) Chronic

corn, all or unspecified

0.01 0.00 0.20 0.01 0.00 1.58

Acute (# 1) Acute (# 2) Chronic Acute (# 1) Acute (# 2) Chronic

corn, all or unspecified

0.01 0.00 0.20 0.00 0.00 1.35

Acute (# 1) Acute (# 2) Chronic Acute (# 1) Acute (# 2) Chronic

corn, all or unspecified 0.00 0.00 0.20 0.00 0.00 0.72

† Acute RQ #1 = (mg ai /kg-bw/day) / LD50

Acute RQ #2 = mg ai ft-2 /(LD50*bw)

Avian Chronic RQ = mg kg-1 seed / NOAEL

Mammalian Chronic RQ = mg a.i./kg-bw/day / adjusted NOAEL

Avian (1000 g) Mammalian (1000 g)

Animal Size

corn, all or unspecified 0.0032 97.56 0.03

Crop

Tolclofos methyl

Rizolex Floable Fungicide

Density of product (lbs/gal):

Data inputs are in blue

Avian (100 g) Mammalian (35 g)

Avian (20 g) Mammalian (15 g)

Risk Quotients†

Endpoints Adjusted LD50 Size class for 

adjusted LD50 Reported

Adjusted NOAEL for Mammals
146

3. LD50 PER SQUARE FOOT OUTPUT 

Chemical:

Name of seed treatment formulation:

Percent AI in formulation: 100% 1 9.99

Tested Body

Weight (g)

Avian LD50: 2000.00 12 2159.27 Small (20g)

Avian repro. NOAEC: 500.00 2748.86 Medium (100g)

3882.87 Large (1000g)

Mammalian LD50: 3500.00 20 3760.99 Small (15g)

Mammalian NOAEL: 100.00 3043.05 Medium (35g)

1316.21 Large (1000g)

Small (15g) 13.11

Medium (35g) 10.61

Large (1000g) 4.59

Crop

Maximum 

Application 

Rate

Maximum Seed 

Application Rate Avian Nagy Dose

Mammalian Nagy 

Dose Available AI

(lbs ai/A) (mg ai/kg seed) (mg ai/kg-bw/day) (mg ai/kg-bw/day) (mg ai ft-2)

Small 154.07 128.98

Medium 87.86 89.14

Large 39.34 20.67

Acute (# 1) Acute (# 2) Chronic Acute (# 1) Acute (# 2) Chronic

corn, all or unspecified

0.07 0.00 1.22 0.03 0.00 9.84

Acute (# 1) Acute (# 2) Chronic Acute (# 1) Acute (# 2) Chronic

corn, all or unspecified

0.03 0.00 1.22 0.03 0.00 8.40

Acute (# 1) Acute (# 2) Chronic Acute (# 1) Acute (# 2) Chronic

corn, all or unspecified 0.01 0.00 1.22 0.02 0.00 4.50

† Acute RQ #1 = (mg ai /kg-bw/day) / LD50

Acute RQ #2 = mg ai ft-2 /(LD50*bw)

Avian Chronic RQ = mg kg-1 seed / NOAEL

Mammalian Chronic RQ = mg a.i./kg-bw/day / adjusted NOAEL

Tolclofos methyl

Rizolex Floable Fungicide

Density of product (lbs/gal):

Data inputs are in blue

Avian (100 g) Mammalian (35 g)

Avian (20 g) Mammalian (15 g)

Risk Quotients†

Endpoints Adjusted LD50 Size class for 

adjusted LD50 Reported

Adjusted NOAEL for Mammals

Avian (1000 g) Mammalian (1000 g)

Animal Size

corn, all or unspecified 0.0202 608.77 0.21

Crop
147

APPENDIX G: SUMMARY OF SUBMITTED ENVIRONMENTAL FATE STUDIES
148

I. Study Summaries

Hydrolysis (MRID 471147-01)

Study Classification

This study was classified as acceptable and fulfills the data requirements of EPA Pesticide 

Assessment Guidelines, Subdivision N, Section 161-1 on Hydrolysis

Material and Methods

14 C ring labeled -Tolclofos-methyl, 0,O-dimethyl 0-(2,6-dichloro-4-methylphenyl) 

phosphorothioate (99.4% pure, 45.0 mCi/mole) at 0.11 ppm concentration (aqueous solubility is 

0.3-0.4 ppm) was dissolved in sterile buffered solutions at pH 5.0, 7.0 and 9.0, and examined for 

hydrolysis in the dark at 25 oC for 30 days. Samples were taken for analysis at days 0, 1, 7, 14, 

21, and 30, acidified to pH 2 and extracted with ethyl acetate. Parent and degradates were 

identified by TLC, GC and LSC.

Results

(1) 14C-Tolclofos-methyl hydrolyzed with a half-life of 51.0 ± 4.4 days (pH 5), 60.8± 8.0 days 

(pH 7) and 62.4± 12.2 days (pH 9).

(2) The isolates (as % of applied) at 30 days at pH 5 were 63.61% parent, 23.10% 0-Methyl 0-

(2,6-dichloro-4-methyl-phenyl) hydrogen phosphorothioate (DM-TM), 8.16% 0,0-dimethyl 

0-(2,6-dichloro-4-methylphenyl) phosphate (TMO), 0.51% 2,6-Dichloro-4-methylphenol 

(ph-CH3). At pH 7, 63.12% parent, 16.08% (DM-TM), 11.97% (TMO) and 0.42% (phCH3). At pH 9, 72.92% parent, 11.24% (DM-TM), 7.66% (TMO) and 0.64% (ph-CH3).

(3) The major degradates were the 0-demethylated product (DM-TM) and the oxidation of P=S 

to P=O, a minor product was formed from the cleavage of the phosphate ester bond to form 

the phenol (ph-CH3). 

(4) The range of material balance was 98 to 103%.

Hydrolysis (MRID 48341921)

Classification

This study was classified as supplemental (conducted at high temperatures) for previously 

submitted study at 25 oC. 

Summary

The hydrolysis of [phenyl-U14C]-labeled O-2,6-dichloro-p-tolyl O,O- dimethyl 

phosphorothioate (tolclofos-methyl), applied at 0.2 mg a.i./L, was studied at 50C, 62C, and 

74C in sterile aqueous buffered pH 4, 7 and 9 solutions incubated in the dark for 50-120 hours. 

Duplicate samples were collected and analyzed using LSC and reverse phase HPLC, with 

identifications confirmed using TLC. 

Based on first order linear regression analysis, tolclofos-methyl dissipated with reviewercalculated half-lives of 63.0-100.5 hours at 50C, 18.4-32.1 hours at 62C, and 5.1-9.9 hours at 

74C. At all temperatures, degradation was most rapid at pH 7 and slowest at pH 5. Two 

transformation products were identified: DM-TM (O-2,6-dichloro-p-tolyl O-hydrogen, Omethyl phosphorothioate) and ph-CH3 (DCMP; 2,6-dichloro-4-methylphenol).
149

Results Synopsis

Half-life

(hours) Major Transformation products (% of the applied); No Minor Degradates were identified

50 C

pH 4 100.5 DM-TM (max 49.4% at 120.0 hours)

pH 7 63.0

DM-TM (max 65.5% at 120.2 hours)

pH 9 78.8

DM-TM (max 46.7% at 120.9 hours) and ph-CH3 (max 12.5% at 120.9 hours)

62C

pH 4 32.1 DM-TM (max 62.7% at 51.2 hours)

pH 7 18.4

DM-TM (max 81.3% at 50.4 hours)

pH 9 23.7

DM-TM (max 57.4% at 50.6 hours); ph-CH3 (max 12.7% at 50.6 hours)

74C

pH 4 9.9 DM-TM (max 58.4% at 14.2 hours)

pH 7 5.1

DM-TM (max 64.4% at 8.2 hours)

pH 9 7.2

DM-TM (max 49.7% at 11.2 hours); and ph-CH3 (max 12.9% at 11.2 hours)

Aqueous Photolysis (MRID 414229-02)

Study Classification

This study was classified as acceptable and fulfills the data requirements of EPA Pesticide 

Assessment Guidelines, Subdivision N/Section 161-2 on photolysis. The decision was taken 

following the registrants’ submittal of additional documentation to satisfy the following issues: 

the Xenon arc- lamp irradiation spectrum; possibility of shift in the absorption spectrum of 

tolclofos-methyl to longer wavelengths in water; providing the absorption spectrum of tolclofosmethyl in water; clarify differences between degradation pattern/half-lives reported for 

hydrolysis and that for the dark control in this experiment; and specify in what proportions the 

co-solvent was used.

Material and Methods

14 C phenyl ring labeled -Tolclofos-methyl, 0-dimethyl 0-(2,6-dichloro-4-methylphenyl) 
150

phosphorothioate at 0.2 ppm concentration (aqueous solubility is 1.0 ppm) was dissolved in 

sterile buffered solutions at pH 7.0 and examined after irradiation (continuous 24 hours exposure 

using Xenon arc lamp) and in the dark at 25 oC for 30 days. Samples were taken for analysis at 

days 0, 1, 3, 5, 7, 14, 21, and 30, acidified to pH 2 and extracted with ethyl acetate. Parent and 

degradates were identified by two dimensional TLC and HPLC. Experimental system included 

traps for CO2 and volatile organics (never exceeded 0.1% of the applied).

Results

(1) 14C Tolclofos-methyl degraded to 60.1% of the applied radioactivity at day 30 in samples 

irradiated continuously with a Xenon arc lamp. In the dark control, 14C Tolclofos-methyl 

degraded to 80.1% of the applied radioactivity at day 30. Reported photolytic half-lives 

of tolclofos methyl in the pH 7 buffer were 38.3 days in the irradiated samples and 76.6 

days in the dark control samples. Half-life of 153 days was obtained following correction 

for dark control and 12 hr/12 hr light/dark cycle.

(1) The major degradate was identified as O-methyl O-hydrogen O-(2,6-dichloro-4-methyl 

phenyl) phosphorothioate, designated as DM-TM, formed at 12.6% of the applied 

radioactivity at day 30 in the irradiated samples. DM-TM formation peaked at 7.3% of 

the applied radioactivity at day 30 in the dark control samples.

(2) Minor degradates detected were O,O- dimethyl O-(2,6-dichloro-4-methylphenyl) 

phosphate, designated as TMO; 2,6-dichloro-4-methylphenol, designated as Ph-CH3; Omethyl O-hydrogen O-( 2,6 -dichloro-4-methylphenyl) phosphate, designated as DMTMO; O-methyl S-methyl O-(2,6-dichloro-4-methylphenyl) phosphorothioate, 

designated as TM-SCH3; and others, presumable unknown compounds. The 

aforementioned degradates were detected in both the irradiated and dark control samples 

with the exception of DMO-TMO and TM-SCH3 which were found only in the 

irradiated samples. No minor degradates formed at greater than 10% with the exception 

of the unknowns which formed at 11.1% of the applied radioactivity at 30 days in the 

irradiated samples. Accumulation of volatiles was insignificant.

(3) Material balances for this study ranged from 93.4% of the applied radioactivity at day 21 

to 106.6% of the applied radioactivity at day 3 in the irradiated samples. In the dark 

control samples, material balances ranged from 93.2% of the applied radioactivity at day

21 to 105.5% of the applied radioactivity at day 1.

Photolysis on Soil (MRID 414229-02)

Study Classification

This study was classified as acceptable and fulfills the data requirements of EPA Pesticide 

Assessment Guidelines, Subdivision N/Section 161-3 on photolysis on soil.

Material and Methods

Sieved (2mm) sandy loam soil (70% sand, 18% silt, 12% clay, CEC 7.0 meq/100g, OM 1.32%, 

pH 7.05) was mixed with distilled water and then added to the bottom surface of a Petri dish. A 

stock solution (0.74 mg in 240.5 μl acetonitrile, 3.22 x 108 dpm) of pheny-14C rizolex (437,340 

dpm/μg, radiochemical purity of 99.5%, and 110.9 mg of unlabeled rizolex to 6,160 μl of 
151

acetonitrile was prepared and applied to the Petri dish containing the soil achieving a starting 

concentration of 1,126.1 μg/g, or 16 lb/acre. Sunlight intensity, cumulative sunlight energy (250-

700 nm) and temperature at the soil surface were measured and recorded at 10 or 20 minute 

intervals throughout the study. The soil chambers were oriented at a perpendicular to the sun's 

path. The temperature control chambers were covered with quartz plates for the light exposed 

samples and normal glass covered with a dark material (unspecified) for the dark controls. 

Irradiated and non-irradiated samples were analyzed in duplicate at time 0, 3, 7, 18, 25, and 30 

days. Samples were extracted with acetone/water, 5: l (v/v) and the extracts were analyzed by 

LSC and then by HPLC, Selected samples were analyzed by 2-dimensional TLC 

autoradiography and GC-MS to identify unknown. An aliquot of soil at each sampling time was 

combusted to determine total radiocarbon. Humidified ambient air was drawn through the 

irradiated and non-irradiated samples; gas traps (ethylene glycol and 10% NaOH) were analyzed 

and replaced with fresh material at each sampling interval.

Results

Rizolex exposed for 30 days on a sandy loam soil under natural sunlight at 25 C degraded 

slowly with a calculated first order half-life of 113 days. Degradation of pheny-14C rizolex was 

slow and represented 83.4% of the applied radiocarbon in light exposed samples and 74.8% in 

dark controls after 30 days. In contrast, the dark control gave a half-life of 71.9 days which was 

attributed to a difference in microbial populations and water content of the soils. The major 

degradate in the irradiated soils was SM-TM that reached a maximum of 6.2% by day 30. A 

minor degradate in the irradiated soils at day 30 was DM-SM-TM at 0.2% of applied. The major 

degradate in the dark control was DM-SM-TM which reached 7.6% by day 30. The minor 

degradate in the dark control was SM-TM present at 2.5% of applied. Total unknowns accounted 

for 3.4% and 2.7% in the irradiated and dark controls respectively. HPLC and TLC analysis 

showed each unknown was a mixture of products. Non-extractable residues accounted for 3.8% 

and 1.1% in the irradiated and dark controls respectively. Radiocarbon recoveries averaged 

95.7% of the applied. No significant amount of volatiles were trapped and CO2 levels were 

<1.1% at day 30.

Aerobic Soil Metabolism (MRID 000156106)

Study Classification

This study was classified as supplemental for the data requirements of EPA Pesticide 

Assessment Guidelines, Subdivision N/Section 162-1 (Aerobic soil metabolism). The 

supplemental classification was given to this study mainly because foreign soils were used that 

may not be typical of US soils where the pesticide is to be used.

Material and Methods

Samples of Sapporo loam (48% sand, 28% silt, 24% clay, 11.6% organic matter, pH 5.3, CM: 39 

meq/100 g) and Azuchi sandy clay loam (62.5% sand, 17% silt, 20.5% clay, 0.4% organic 

matter, pH 5.5, CM: 13.2 meq/100 g). Soils were sieved (2 mm), moistened to 75% of field 

capacity, and maintained in the dark at 25 ± 2 oC for 10 days. Following this period, the soils 
152

were treated with ring-labeled [14C] tolclofos-methyl (radiochemical purity >99%, specific 

activity 35.5 mi/m mole, Sumitomo Chemical Co.) in methanol at 20 ppm. The treated soils were 

incubated in the dark at 25 oC in glass jars attached to a gas collection system having traps for 

volatiles (a polyurethane foam plug) and evolved 14 C CO2 (0.5 N sodium hydroxide solution). 

CO2-free air (air flow rate 25-30 mL/minute) was continuously passed over the soil. Soil 

moisture content was adjusted as needed to maintain 75% of field capacity. 

Additional samples of Sapporo loam and Azuchi sandy clay loam soils were autoclaved (1 hour 

at 121°C and 2 atmospheres on two consecutive days), moistened to 75% of field capacity, 

treated with ring-labeled [14C] tolclofos-methyl at 20 ppm, and incubated as described above.

Samples of non-sterile soil were taken at 1, 3, 7, 14, 30, 60, 90, 120, and 180 days posttreatment. Sterile soil samples were taken at 1, 3, 7, 14, and 30 days post-treatment. Gas traps 

were sampled at the same intervals as the soils. The polyurethane foam plugs were extracted four 

times with methanol. Radioactivity in the methanol extracts and sodium hydroxide solutions was 

quantified by LSC. l h 2 in the sodium hydroxide solutions was quantified by barium chloride 

precipitation. Soil samples were extracted with 1 N hydrochloric acid: ethyl acetate (3:2). The 

aqueous layer of the extract was re-combined with the extracted soil and the mixture was reextracted twice with ethyl acetate. Ethyl acetate extracts were combined, evaporated to dryness, 

and the residue was analyzed by TLC on silica gel plates using the following solvent systems: 

to1uene: acetic acid (7:1), benzene: ethyl acetate (1:1), to1uene: ethyl formate: formic acid 

(5:7:1), hexane: toluene: acetic acid (3:15:2), and chloroform. Reference compounds were cochromatographed with the samples and, following development were detected under UV light 

and by spraying with a 2% palladium chloride in 2 N hydrochloric acid solutions. Radioactive 

areas were detected by autoradiography and quantified by scraping the silica gel from the plates 

and counting it using LSC. Radioactivity remaining at the origin of the TLC plate was eluted 

with methanol and reanalyzed by TLC on silica gel plates developed in ethyl acetate: ethano1: 

water (4:2:1). Following development, radioactive areas and unlabeled compounds were detected 

and quantified as described above.

Un-extractable [14C] residues remaining in the extracted soil were separated into fulvic acid, 

humic acid, and humin fractions and analyzed by combustion and LSC to determine the 

distribution of radioactivity in the soil organic matter.

Results

Ring-labeled [14C] tolclofos-methyl (radiochemical purity >99%) at 20 ppm, degraded with a 

half-life of 14-30 days in Sapporo loam and Azuchi sandy clay loam soils; the registrantcalculated half-lives were 26.3 and 31.8 days, respectively. At 180 days post-treatment, 

tolclofos-methyl comprised 5.6-7.5% of the applied radioactivity; evolved 14CO2 totaled

17-22.9% of the applied; and degradates included (Each comprised ≤4.1% of the applied):

 O,O-dimethyl O-(2,6-dichloro-4-hydroxymethylpenyl) phosphorothioate (TM-CH2OH),

 O,O-dimethyl O-(2,6-dichloro-4-carboxyphenyl) phosphorothioate (TM-COOH)

 O ,O-dimethyl O- ( 2,6-dichloro-4-methylphenyl ) phosphate (TMO),

 O,O-dimethyl O-(2,6-dichloro-4-hydroxymethylphenyl) phosphate (TMO- CH2OH),
153

 O,O-dimethyl O- ( 2 ,6-dichloro-4-carboxyphenyl) phosphate (TMO-COOH),

 O-methyl O-(2,6-dichloro-4-methylphenyl)hydrogen phosphorothioate (DM-TM),

 O-methyl O-(2,6-dichloro-4-methylphenyl)hydrogen phosphate (DM-TMO),

 2,6-dichloro-4-methylphenol (Ph-CH3), 

 2,6-dichloro-4-hydroxymethylphenyl (Ph-CH2OH), and

 2,6-dichloro-4-carboxyphenol (Ph-COOH).

Un-extractable [14C] residues in the soils comprised 47-50.8% of the applied at 180 days posttreatment.

Under sterile conditions, [14C] tolclofos-methyl at 20 ppm degraded with a half-life of >30 days 

in Sapporo loam and Azuchi sandy clay loam soils; the registrant-calculated half-lives were 79.7 

and 116.3 days, respectively. At 30 days post-treatment, tolclofos-methyl comprised 65.4-76.3% 

of the applied radioactivity, volatiles comprised ≤2% of the applied, and un-extractable [14C] 

residues in the soil comprised 11-19.1% of the applied. All degradates detected under non-sterile 

conditions were detected in the sterile soil at 53.1% of the applied except Ph-CH2OH, which 

was not detected (<0.01% of the applied) in either soil.

Aerobic Soil Metabolism (MRID 427032-01)

Study Classification

This study was classified as acceptable and fulfills the data requirements of EPA Pesticide 

Assessment Guidelines, Subdivision N/Section 162-1 on aerobic soil metabolism.

Material and Methods

Sieved (2mm) sandy loam soil (70% sand, 18% silt, 12% clay, CEC 7.0 meq/100g, OM 0.8%, 

pH 7.1) was moistened with distilled water to 75% of 0.33 bar moisture content and incubated in 

the dark at 25 oC for 19 days. A stock solution of [phenyl14C] Rizolex w as adjusted to 30 -

mCi/mmol by dissolving 49.6 mg of non-radiolabeled rizolex in 20 ml of 1/1 benzene/n-hexane

containing 50.8 mg of 14C] Rizolex, radiochemical purity of 99.66%. The test solution was 

purified by TLC and dissolved in 10 ml of acetonitrile to prepare the dosing solution, and applied 

to the Petri dish containing the soil achieving a starting concentration of 16.1 μg/g soil, or 32 

lb/acre. Inlet air was passed through NaOH trap to remove carbon dioxide and through a water 

trap to saturate the air with water. Outlet air was passed through to ethylene glycol traps and 

NaOH trap. Test vessels were maintained in darkness at 25±1 oC. The soil moisture content was 

maintained by adding distilled water at least once every two weeks. Duplicate samples were 

analyzed at time 0, 1, 3, 7, 14, 30, 60, 90, 121, 180, 271 and 365 days. Samples were extracted 

with acetone/water, 5: 1(v/v) (Extract-1). The acetone was evaporated from Extract-1 and the 

remaining aqueous solution extracted with dichloromethane to form Organic-1andAqueous-1. 

Residues remaining in the soil (Bound-1) were air-dried and homogenized by grinding, then 

stored for exhaustive extraction or combustion analysis. Exhaustive extraction was performed 

with 5: l (v/v) acetone/0.5 N HC1 and the extract identified as Extract-2. Remaining soil residues 

(Bound-2) were air-dried and homogenized by grinding, then stored for alkaline extraction or 
154

combustion. Extract-2 was partitioned into organic and aqueous fractions (Organic-2 and 

Aqueous-2). Humic substances were precipitated from Aqueous-2, while Bound-2 was 

fractionated into fulvic acid, humic acid, and humin. The NaOH trap was analyzed for 14CO2 by

precipitation with BaC12. Samples from the ethylene glycol trap solutions were mixed with 

methanol for LSC analysis, while the remainder was partitioned into Vol-aqueous and Volorganic solutions. Samples of all of the extracts were analyzed by LSC. Identification was 

accomplished by performing both HPLC and two-dimensional TLC with authentic standard 

samples. The performing lab synthesized 19 standards, confirmed by NMR and MS, and 

purchased 2 others for comparison to extracted degradates. 

Rizolex and its degradation products present in Organic-1 (Day 60A), Organic-2 (Day 90 B and 

Day 180 A), Aqueous-1 (Day 60 B) and Vol-organic (Day 30 A) were separated by HPLC. Each 

HPLC fraction was concentrated by nitrogen gas flow, and the aliquot mixed with the authentic 

standard in methanol prior to HPLC and TLC analysis. Radioactivity in the various fractions and 

in silica gel following TLC was measured by LSC. HPLC was performed to quantify Rizolex 

and degradates, and to separate degradates for confirmative identification from Organic-1 and 2, 

Aqueous-1, Vol-organic and fulvic acid organic extracts. The limit of detection by radio-HPLC 

was 4.5 x 10-3μg of Rizolex.

Results

Rizolex applied to Tulare sandy loam soil ( 70% sand, 18% silt, 12% clay, 0.8% organic matter, 

CEC 7.0 meq/100g, pH 7.1) at 25oC degraded slowly with a calculated first order half -life of 79 

days recalculated (59.7 days reported by registrant). 14C rizolex represented 5.25% of the applied 

radiocarbon at 365 days. While a total of 28 compounds were extracted from the soil, only eight 

(including parent Rizolex) could be fully identified by comparison with the 21 synthesized 

standards. However, only two of the twenty seven degradates exceeded 1% of the applied 

radioactivity when averaged over the duplicate samples. The two degradates are:

 O-Methyl O-(2, 6-dichloro-4-methyl-phenyl) hydrogen phosphorothioate (DM-TM), which 

reached a maximum of 18.47% by day 90. DM-TM declined from this maximum with a 

reviewer calculated half-life of approximately 56.7 days ; and

 2, 6-Dichloro-4-methylphenol (ph-CH3), which reached 2.84% at 121 days.

Identified minor degradates included 3, 5-dichloro-4-hydrobenzoic acid (ph-COOH);

O-methyl- O-hydrogen O-2, 6-dichloro-4-carboxyphenyl phosphorothioate (DM-TMCOOH);

O-methyl-0-hydrogen O- 2, 6-dichloro-4-methylphenyl phosphate (DM-TMO); O, O-dimethyl 

O-2, 6-dichloro-4-carboxy phenyl phosphate (TM-COOH); and 0, S-dimethyl O-2, 6-dichloro4-methyl phenyl phosphorothioate (SM-TM). Non-extractable residues in the soil organic 

fraction accounted for 20.61% of the applied by day 365. Carbon dioxide increased to 33.29% of 

the applied by day 365, while organic volatiles totaled 25.81%. Organic volatiles included: 

Rizolex (18.00%), Me-ph-CH3 (2,6-dichloro-4-methylanisole; 5.58%) and ph-CH3 (1.72%) at 

day 365. Material balances ranged from 95.76-102.70%.

Aerobic Soil Metabolism (MRID 483419-23 supplemented by 483419-25)

Study Classification
155

Note: The study author stated that the Abington soil experiment was designed to identify the rate 

and route of degradation of tolclofos-methyl, and the Terling and Shuttleworth soil experiments 

were designed only to establish the rate of degradation of tolclofos-methyl. 

This study was classified as supplemental for the following reasons:

 Temperature during incubation was reported to be 10 ± 2C.

 It was not shown that the soil extraction procedure was the best available method. At study

termination, un-extractable soil residues totaled 42.84-60.46% of the applied.

 Most samples were analyzed only using TLC, which did not adequately separate many of the 

transformation products. 

 Although 20.43-44.49% of the applied was recovered from the ethanolamine trap totaled at 

study termination, it was not confirmed that these residues were CO2.

Summary

The biotransformation of [14C]- O-2,6-dichloro-p-tolyl O,O dimethyl phosphorothioate 

(tolclofos-methyl; radiochemical purity 99.4%), at a nominal concentration of 2 mg a.i./kg, was 

studied in three soils from the UK:

 A sandy loam (Abington; pH 7.7, organic matter 2.6%);

 A loamy sand (Shuttleworth, pH 6.0, organic matter 2.4%); and

 A silt loam (Terling; pH 5.2, organic matter 4.6%). 

The experiments were conducted under aerobic conditions for 112 days in the dark at 10 ± 2C 

and a soil moisture content of 40% of maximum water holding capacity. The test system for the 

Abington soil consisted of Erlenmeyer flasks containing moist treated soil (100 g dry wt) that 

were connected to individual volatile traps. The test systems for the Shuttleworth and Terling 

soils consisted of open crystallizing dishes containing moist treated soil (50 g dry wt.) that were 

placed in incubation chambers; the chambers were attached to the volatile traps. Humidified 

CO2-free air was continually drawn through the samples or chambers, then through tubes of 

ethanediol and ethanolamine. Duplicate samples of each soil were collected 0, 3, 7, 14, 28, 55, 

84, and 112 days post-treatment. The soils were Soxhlet-extracted with acetone: glacial acetic 

acid (98:2, v:v), then with acetone. The Abington sandy loam soil was further extracted three 

times with acetone: 0.5 M HCl (5:1, v:v). The extracts were analyzed by LSC and onedimensional TLC. Abington soil extracts from 7, 28, and 112 days were also analyzed by HPLC. 

Portions of the extracted soils were analyzed using LSC following combustion. The trapping 

solutions were analyzed by LSC; identification of CO2 was not confirmed.

The incubation temperature and soil moisture content were reportedly maintained throughout the 

experiment; supporting data were not provided. No determinations were made to verify that 

aerobic conditions were maintained in the soils. The soils were viable at initiation and 

termination.

Overall [14C] residue recoveries averaged 96.22  3.11% (range 88.44-100.22%) of the applied 

for the Abington sandy loam soil, 95.06  3.92% (range 84.08-99.18%) for the Shuttleworth 

loamy sand soil and 93.74 ± 4.18% (range 87.40-100.65%) for the Terling silt loam soil. 

Based on nonlinear regression analyses, tolclofos-methyl dissipated with reviewer-calculated 

half-lives of 19.2 days in Abington sandy loam soil, 22.6 days in Shuttleworth loamy sand soil 
156

and 30.9 days in the Terling silt loam soil. Transformation products were identified only in the 

Abington soil; six minor transformation products were identified:

 3,5-dichloro-4-hydroxybenzoic acid (ph-COOH);

 2,6-dichloro-4-(hydroxymethyl)phenol (ph-CH2-OH); 

 O-2,6-dichloro-p-tolyl O-hydrogen, O-methyl phosphorothioate (DM-TM); 

 3,5-dichloro-4-dimethoxyphosphoryloxy-benzoic acid (TM-COOH);

 (2,6-dichloro-4-methyl-phenyl) dimethyl phosphate (TMO); and

 (2,6-dichloro-4-methyl-phenyl) methyl hydrogen phosphate (DM-TMO).

Total transformation products were a maximum of 6.69% of the applied in the Shuttleworth 

loamy sand soil and 37.15% in the Terling silt loam soil; no single compound was present at 

>5% of the applied. In the three soils at study termination, non-extractable [14C] residues totaled 

42.84-60.46% of the applied and CO2 totaled 20.43-45.65%.

In Shuttleworth loamy sand soil incubated at 15°C, tolclofos-methyl dissipated with a nonlinear 

reviewer-calculated half-life of 26.5 days. Transformation products were not individually

identified but totaled a maximum of 14.56% of the applied at 14 days post-treatment.

Results

Abington sandy loam soil at 10°C.

Linear half-life: 28.2 days (r2= 0.9732).

Nonlinear half-life: 19.2 days (r2= 0.9911).

Observed DT50: ca. 14 days.

Major transformation products: CO2 (maximum 45.65% at 112 days).

Minor transformation products: 

 3,5-Dichloro-4-hydroxybenzoic acid (ph-COOH, maximum 0.77% at 28 days).

 2,6-Dichloro-4-(hydroxymethyl)phenol (ph-CH2OH, maximum 0.29% at 28 days).

 O-2,6-Dichloro-p-tolyl O-hydrogen, O-methyl phosphorothioate (DM-TM, maximum 

0.50% at 28 days).

 3,5-Dichloro-4-dimethoxyphosphoryloxy-benzoic acid (TM-COOH, maximum 1.67% at 7 

days).

 (2,6-Dichloro-4-methyl-phenyl) dimethyl phosphate (TMO, maximum 0.37% at 28 days).

 (2,6-Dichloro-4-methyl-phenyl) methyl hydrogen phosphate (DM-TMO; maximum 0.19% 

at 7 days).

Shuttleworth loamy sand soil at 10°C.

Linear half-life: 23.2 days (r2= 0.9920).

Nonlinear half-life: 22.6 days (r2= 0.9986).

Observed DT50: 14-28 days.

Major transformation products: CO2 (maximum 27.27% at 112 days).

Minor transformation products: None identified.

Terling silt loam soil at 10°C.

Linear half-life: 30.7 days (r2= 0.9737).

Nonlinear half-life: 30.9 days (r2= 0.9847).

Observed DT50: ca. 30 days.
157

Major transformation products: CO2 (maximum 20.43% at 112 days).

Minor transformation products: None identified.

Aerobic Soil Metabolism (MRID 483419-24)

Study Classification

This study was classified as acceptable and fulfills the data requirements of EPA Pesticide 

Assessment Guidelines, Subdivision N/Section 162-1 on aerobic soil metabolism. However, the 

following deficiencies were identified:

 It was not shown that the soil extraction procedure was the best available method. At study

termination, un-extractable soil residues totaled 45.4-56.1% of the applied. This deficiency

initiated the consideration of calculating the total toxic residues half -lives to account for the 

un-extracted un-identified residues.

 Single rather than replicate samples were analyzed at each sampling interval.

 The pesticide use history at the test sites was not reported, and it was not confirmed that the 

soils were free of pesticide residues. 

 The test soils were from the UK, and were not compared with soils typical of tolclofosmethyl use areas in the US.

Summary

The biotransformation of [phenyl-U14C]-labeled O-2,6-dichloro-p-tolyl O,O dimethyl 

phosphorothioate (tolclofos-methyl), at 2 mg a.i./kg, was studied in four English soils:

 A sandy loam (PT-102; pH 6.9-7.1, organic matter 4.3%);

 A sandy loam (PT-103, pH 4.9-5.5, organic matter 2.4%); 

 A clay loam (SK 15556090; pH 6.2-6.7, organic matter 7.8%); and

 A clay loam (SK 960087; pH 7.2-8.0, organic matter 4.7%). 

The experiments were conducted under aerobic conditions for 90 days in the dark at 20 ± 1C 

and a soil moisture content of 45% of maximum water holding capacity. The test system 

consisted of Erlenmeyer flasks containing moist treated soil (50 g dry wt) that were connected to 

individual volatile trapping systems. Humidified air was pulled through the sample flask, then 

through polyurethane foam and tubes of ethanediol, 2% paraffin in xylene, and 2M NaOH. 

Single vessels of each soil were collected at 0, 1, 3, 7, 15, 30, 62, and 90 days post-treatment. 

Samples were Soxhlet-extracted for 18 hours using acetone: glacial acetic acid (98:2, v:v (98:2, 

v:v), and aliquots of the extracts were analyzed by LSC and HPLC. Identifications were 

confirmed using one-dimensional TLC. Portions of the extracted soils were analyzed using LSC 

following combustion, and samples containing maximum concentrations of un-extracted residues 

were fractionated into fulvic acids, humic acids, and humin. The polyurethane foam extracts and 

liquid trapping solutions were analyzed by LSC; CO2 was confirmed by precipitation with 

barium chloride. 

The incubation temperature and soil moisture content were reportedly maintained throughout the 
158

experiment; supporting data were not provided. No determinations were made to verify that 

aerobic conditions were maintained in the soils. The soils were viable at initiation and 

termination.

Overall [14C]residue recoveries averaged 95.9  2.3% (range 91.8-98.7%) of the applied for the 

PT-102 sandy loam soil, 94.7  3.0% (range 91.5-99.3%) for the PT-103 sandy loam soil, 96.2 

2.7% (range 92.1-100.8%) for the SK 15556090 clay loam soil, and 94.2 ± 3.0% (range 91.2-

99.3%) for the SK 960087 clay loam soil. There was some loss of radioactivity from the test 

systems over time

Based on nonlinear regression analyses, tolclofos-methyl dissipated with reviewer-calculated 

half-lives of 3.5 days in PT-102 sandy loam soil, 2.0 days in the PT-103 sandy loam soil. 5.6 

days in SK 15556090 clay loam soil and 5.9 days in the SK 960087 clay loam soil. Two 

nonvolatile transformation products were identified: 

 DM-TM (O-2,6-dichloro-p-tolyl O-hydrogen, O-methyl phosphorothioate and 

 ph-CH3 ( 2-6-dichloro-4-methylphenol).

In the four soils at study termination, non-extractable [14C] residues totaled 45.4-56.1% of the 

applied and CO2 totaled 36.9-42.6%.

Results

Test system used: PT-102 sandy loam soil.

Linear half-life: 16.7 days (r2= 0.8044); TTR=139 days

Nonlinear half-life: 3.5 days (r2= 0.9943)

Observed DT50: ca. 3 days

Major transformation products: 

CO2 (maximum 36.9% at 90 days)

Minor transformation products: 

O-2,6-Dichloro-p-tolyl O-hydrogen, O-methyl phosphorothioate (DM-TM, maximum 1.1% 

at 1 day)

2,6-Dichloro-4-methylphenol (ph-CH3, maximum 1.3% at 3 days)

Test system used: PT-103 sandy loam soil.

Linear half-life: 17.0 days (r2= 0.6844); TTR=128 days

Nonlinear half-life: 2.0 days (r2= 0.9943)

Observed DT50: 1-3 days

Major transformation products:

DM-TM (maximum 13.3% at 3 days)

CO2 (maximum 40.9% at 90 days)

Minor transformation products: 

ph-CH3 (maximum 8.0% at 3 days)

Test system used: SK 15556090 clay loam soil.

Linear half-life: 16.3 days (r2= 0.8295); TTR=114 days

Nonlinear half-life: 5.6 days (r2= 0.9989)
159

Observed DT50: 3-7 days

Major transformation products: 

CO2 (maximum 39.6% at 90 days)

Minor transformation products: 

DM-TM (maximum 3.6% at 7 days)

ph-CH3 (maximum 2.9% at 7 days)

Test system used: SK 960087 clay loam soil.

Linear half-life: 16.9 days (r2= 0.8123); TTR= 98 days 

Nonlinear half-life: 5.9 days (r2= 0.9974)

Observed DT50: ca. 7 days

Major transformation products: 

CO2 (maximum 42.6% at 90 days)

Minor transformation products: 

DM-TM (maximum 0.6% at 15 days)

ph-CH3 (maximum 4.1% at 7 days)

Aerobic and Anaerobic Soil Metabolism (MRID 428183-01)

Study Classification

This study was classified as acceptable and fulfills the data requirements of EPA Pesticide 

Assessment Guidelines, Subdivision N/Section 162-1 on aerobic soil metabolism.

Material and Methods

Air-dried sieved (2 mm) sandy loam soil (70% sand. 18% silt, 12% clay, 0.8% organic matter, 

pH 7.1, and CEC 7 :0 meq/100 g) was weighed (20 g dry weight) into beakers, moistened t o 

75% of 0.33 bar and incubated in the dark at 25 ± 1C for 18 days. After the pre-incubation, the 

soi1s were treated a t 16.6 ppm with phenyl ring labeled [U-14C] tolclofos (0-2,6-dichloro-p -

tolyl 0 ,0-dimethyl phosphorothioate: radiochemical purity 99.5%, specific activity 59.5 mCi /m 

Mol , Sumitomo Chemical Company) , dissolved in acetonitri1e. The individual treated soil 

samples were mixed "thoroughly" and transferred to glass incubation vessels equipped with inlet 

and outlet ports. The vessels were attached to a continuous airflow system. Humidified, CO2-free 

air was drawn (20-30 mL/minute) through the sample vessel, then through ethylene glycol (two 

traps) and 0.5 N NaOH trapping solutions. The samples were incubated in a temperaturecontrolled room at 25 ± 1C in darkness. The soi1 was remoistened to 75% of 0.33 bar "at least" 

once every 2 weeks. Duplicate vessels of treated soil were collected for analysis a t 0, 10, 21, and 

32 days post-treatment.

At 32 days post-treatment, al1 remaining treated soi1 samples were \ flooded with 20 mL of O2-

free water that had been amended with 0.1g of glucose. The samples were stirred to remove 

trapped air, the redox potentia1 was measured, and the incubation vessels were flushed with 

nitrogen gas. The inlet and outlet ports were sealed; and the vessels were returned to the 

temperature controlled room. After 10, 11, 31. 42, and 60 days of anaerobic incubation (42, 63. 

74, and 92 days post-treatment) the vessels were purged with nitrogen gas for 5 minutes: effluent 

gases were passed through ethylene glycol and 0.5 N I NaOH trapping solutions. "On each 
160

sampling day of volatile trap solutions, the incubation vessel s and connections were rinsed with 

acetone". After collection of the headspace gases, duplicate vessels of flooded, treated soil were 

collected for analysis. The pH and redox potential of the samples were measured at the time of 

sampling.

The flooded soil samples were analyzed according t o the scheme presented in Figure 4 of the 

report. After sampling, the flooded soils were centrifuged, and the water and soil phases were 

separated. Aliquots of the floodwater were analyzed for total radioactivity using LSC. The 

remaining water was partitioned three times against methylene chloride; aliquots of the 

combined methylene chloride extracts and of the extracted floodwater were analyzed using LSC. 

Additional aliquots of the methylene chloride solutions were washed with a saturated NaCl 

solution, and filtered through a silicone-treated phase separator. The filtered solutions were 

concentrated at 40 C under reduced pressure; the concentrated solutions were diluted with 

methanol , filtered ( 0.5 um) , and analyzed by reverse-phase HPLC using a Sumipax ODS-A212

column coupled with a u-Bondapac C-18 guard column , and eluted with water : acetonitrile: 

methanol (gradient from 70: 0: 30 t o 20: 30: 50 t o 70: 0: 30) ; the column was equipped with 

UV (254 nm) and radioactive flow detection. Aliquots o f the extracted floodwater were freezedried, the residues were dissolved in methanol or methanol: water (1:l or 4:1, v:v), and aliquots 

of the solutions were filtered (0.5 um) and analyzed by HPLC as described. All samples were cochromatographed with non-labeled reference standards (Figure 3 of the report). Limits of 

detection were reported t o be 0.00045 μg for LSC and 0.0045 μg for HPLC. 

The treated-soi1 samples from the aerobic and anaerobic phases of the study were extracted three 

times with acetone: water (5: 1. v: v) by shaking for 10 minutes per extraction; after each 

extraction, the mixtures were centrifuged and the supernatant removed. The extracts were 

combined, and aliquots of the extracts were analyzed f o r total radioactivity using LSC; the 

extracted soi1 was a air-dried, and subsamples were analyzed by LSC following combustion. 

The acetone was removed from the extracts using a rotary evaporator at 40 C. The resulting 

aqueous solutions were partitioned three times against methylene chloride; the methylene 

chloride extracts from each solution were combined, and aliquots of the methylene chloride and 

aqueous phases were analyzed using LSC. Prior t o HPLC analysis, additional aliquots of the 

methylene chloride and aqueous phases were prepared as described with a saturated NaCl 

solution and by freeze drying, respectively. 

The acetone: water-extracted soil samples were further extracted three times with acetone: 0.5 N 

HC1 (5:1, v: v) by shaking for 10 minutes per extraction; after each extraction, the mixtures were 

centrifuged and the supernatant removed. The extracts were combined, and a1iquots were 

analyzed using LSC; the extracted soil was air-dried, and subsamples were analyzed by LSC f o l 

lowing combustion. The acetone was removed from the acetone: HC1 extracts by rotary

evaporation at 40 C; the resulting aqueous solutions were partitioned three times against 

methylene chloride as described and a1iquots of the resulting methylene chloride and aqueous 

phases were analyzed using LSC. Prior t o HPLC analysis, additional aliquots of the methylene 

chloride extracts were prepared as described with a saturated NaCl solution. The extracted 

aqueous solution was neutralized with a 0.5 N NaOH solution, and the resulting precipitate was 
161

separated from the solution by centrifugation; a1iquots of the supernatant were analyzed using 

LSC, and the radioactivity in the precipitate ("humic substance" was determined by difference 

(rather than direct analysis). Additional a1iquots of the neutralized supernatants were prepared 

by freeze-drying prior t o HPLC analysis.

Identification of tolclofos methyl and its degradates isolated by HPLC was confirmed 'using twodimensional TLC on plates (type unspecified) developed in chloroform: methanol 9: 1, v: v) in 

the first direction and either to1uene: ethyl formate: formic acid (5:7: 1, v:v:v) or ethyl acetate: 

ethanol: water (4':2:1, v:v:v) in the second direction. [14C] residues on the plates were visualized 

using auto-radiography.

All aliquots of the acetone rinses of the incubation vessels and connections were analyzed by 

LSC. Aliquots o f the ethylene glycol trapping solutions were di1uted with methanol and 

analyzed f o r total radioactivity using LSC. The remaining ethylene glycol solutions were 

diluted with water and partitioned three times against methylene chloride, the methylene chloride 

extracts were combined and aliquots of the methylene chloride extracts and the extracted 

solutions were analyzed using LSC. Additional a1iquots of the methylene chloride extracts were 

washed with a saturated NaCl solution, and fi1tered through a silicone-treated phase separator; 

the filtered solutions were combined with the associated acetone /rinses of the incubation 

equipment, filtered (0.5 um), and analyzed using HPLC as described. Aliquots of the NaOH 

trapping solutions were analyze: using LSC. Identification of [14C] residues in the NaOH 

solution as CO2 was confirmed by precipitation with barium chloride.

Results

Phenyl ring-labeled [U-14C] tolclofos methyl (0-2.6-dichloro-p- tolyl 0.0-dimethyl 

phosphorothioate: radiochemical purity 99.5%). at 16.6 1 ppm, degraded with an observed halflife of >60 days in anaerobic (flooded plus nitrogen atmosphere) sandy loam soi1 that was 

incubated in the dark at 25 C for 60 days following 32 days of incubation under aerobic 

conditions. Registrant calculated half -lives were 52.7 and 80.0 days for the aerobic and 

anaerobic phases of the experiment, respectively. [14C] tolclofos methyl comprised 100.88-

101.49% of the applied immediately post-treatment. 64.24-68.89% after 32 days of aerobic 

incubation, 59.71-61.44% after 10 days o f anaerobic incubation (42 days post-treatment. 48.44-

49.19% after 31 days of anaerobic incubation and 39.47-40.12% after 60 days of anaerobic 

incubation. Eleven degradates were identified in the flooded soi1:

 0-methyl 0-hydrogen 0-2 .6-dichloro-4-kethylphenyl phosphorothioate (DM-TM);

 2.6-dichl oro-4-methyl phenol (ph-CH3) ;

 4-methyl phenol (p-cresol);

 3.5-dichloro-4-hydroxybenzoic acid (ph-COOH) :

 3.5-dichloro-4-hydroxybenzyl alcohol (ph-CH2OH);

 0-methyl 0-hydrogen 0-2,6-di chdoro-4-carboxyphenyl phosphate (DM-TM-COOH);

 0-methyl 0-hydrogen '0-2, 6-dichloro-4-methyl phenyl phosphate (DM-TMO);

 0.0-dimethyl 0-2, 6-dichl oro-4-carboxyphenyl phosphorothioate (TM-COOH);

 0.0-dimethyl 0-2.6-di chloro-4-methylphenyl phosphate (TMO);
162

 0, S-dimethyl 0-2,6-dichloro-4-methyl phenyl phosphorothioate (SM-TM) ; and

 2-chloro-4-methyl phenol (DC-ph-CH3).

DM-TM, the major degradate, increased steadily to an average 12.63% of the applied after 32 

days of aerobic incubation and 31.19% after 60 days of anaerobic incubation. The degradate phCH, averaged a maximum 7.99% of the applied after 42 days of anaerobic incubation, and pcresol was 55.06% after 60 days of anaerobic incubation. No other identified degradate was 

isolated at >1.0% of the applied. At least 18 unidentified [14C] compounds were isolated from the 

soi1 or water, each at ≤1.28% of the applied. Evolved CO2 and other [14C] volat1ies, including: 

2, 6-dichloro-4-methylani sole (Me-ph-CH), totaled 2.86-5.31% and 2.32-2.59% of the applied, 

respectively, after 32 days of aerobic incubation, and 4.50-5.75% and 3.18-3.46%, respectively, 

after 60 days of anaerobic incubation. At all sampling intervals, un-extracted [14C] residues 

averaged <5.0% of the applied, and "humic substance" averaged <2.0%. After 60 days of 

anaerobic incubation, the distribution of [14C] residues between the soi1 and water fractions was 

approximately 2: 1. Material balances were 101.51- 102.07% of the applied immediately after 

post-treatment, 95.34-96.21% after 32 days of aerobic incubation, and 93.36-96.44% after 60 

days of anaerobic incubation.

Anaerobic Soil Metabolism (MRID 000156106)

Study Classification

This study was classified as supplemental and partially fulfills the data requirements of EPA 

Pesticide Assessment Guidelines, Subdivision N/Section 162-1 on anaerobic soil metabolism.

Material and Methods

Same as the aerobic soil metabolism above (MRID 000156106) except that the soils (30 g) in 50-

ml beakers were moistened with distilled water to 75 % of 0.33 bar, and incubated at 25±2 C for 

2 weeks in BBL GasPak anaerobic systems (Becton Cickinson and Company). Then, the soils 

were treated with 14C-tolclofos-methyl at a rate of 20 ppm.

Results

The half-life of disappearance for tolclofos-methyl under anaerobic conditions was 34 and 44 

days for Sapporo and Azuchi soils, respectively. Under these conditions, DM-TM and ph-CH3 

gradually increased with time, amounting to 4.8-7.7 % and 2.6-3.7 % of the applied 14C at 60 

days post-treatment. The bound 14C amounted to approximately 31-39 % of the applied 14C 

during the same periods, whereas the amount of 14CO2did not exceeds 1.0%.

Aerobic Aquatic Metabolism (MRID 483419-26)

Study Classification

This study is [Acceptable]. Deviations from the objectives of OCSPP guidelines were noted. 

Only sediments, with associated waters, from the United Kingdom were used in this study, and it 

was not established that the application rate (equivalent to 2 kg/ha) was equivalent to the 

maximum field use rate. Only single samples were collected at each sampling interval.
163

Summary

The biotransformation of [phenyl-U14C]-labeled O-2,6-dichloro-p-tolyl O,O-dimethyl 

phosphorothioate (tolclofos-methyl), at 0.67 mg a.i./kg, was studied in two freshwater aquatic 

systems from the United Kingdom: 

 A pond water/sandy silt loam sediment (water, pH 7.91; sediment, pH 6.9-7.2, organic matter 

12.7%) system and 

 A lake water/sandy loam sediment (water, pH 6.55; sediment, pH 5.7-6.1, organic matter 

5.8%) system. 

The experiments were conducted under aerobic conditions for 100 days in the dark at 20 °C. The 

test systems consisted of borosilicate glass bottles containing water (ca. 95.4 mL) and sediment 

(ca. 14 or 24 g dry wt.) that were attached to continuous flow-through volatile trapping systems 

(polyurethane foam [PUF], ethylene glycol, 2% paraffin in xylene and 2M NaOH). A single 

sample for each system was collected at 0, 1, 2, 3, 7, 30, 62, 76 (lake system only) and 100 days 

post-treatment. Following removal of the water, the sediment was Soxhlet-extracted with 

acetone: glacial acetic acid (98:2, v:v). Residues were recovered from the water layer using C18 

solid-phase extraction. PUF was extracted with acetonitrile. Water layers, sediment extracts, 

extracted sediment, trapping solutions and PUF extracts were analyzed for total radioactivity

using LSC. Water, sediment and PUF extracts were also analyzed by HPLC and onedimensional TLC. Non-extractable residues were characterized by organic matter fractionation.

The test conditions presented in the study protocol appear to have been maintained throughout 

the experiments. Throughout the study, redox potentials and dissolved oxygen in the water 

layers were ca. +275 to +475 mV and ca. 25-95%, respectively, with redox potentials in the 

sediments of ca. -50 to +150 mV.

Overall recovery of [14C] residues averaged 94.4  2.2% (range 90.9-97.0%) of the applied for 

the sandy silt loam (pond) system and 92.2  4.7% (range 81.6-97.1%) for the sandy loam (lake) 

system. There were no consistent patterns of loss of radioactivity from the systems over time. 

Tolclofos-methyl dissipated with reviewer-calculated nonlinear half-lives of 18 days in the sandy 

silt loam (pond) system and 24 days in the sandy loam (lake) system. In both systems, 

volatilized tolclofos-methyl was detected at a maximum 12.7-31.6% of the applied. Four

transformation products were identified: 

 O-2,6-dichloro-p-tolyl O-hydrogen, O-methyl phosphorothioate (DM-TM); 

 2,6-dichloro-4-methylphenol (ph-CH3[DCMP]);

 (2,6-dichloro-4-methyl-phenyl) methyl hydrogen phosphate (DM-TMO, oxon product); and

 3,5-dichloro-4-dimethoxyphosphoryloxy-benzoic acid (TM-COOH).

DM-TM was a major product in both systems, while ph-CH3[DCMP], DM-TMO and TMCOOH were minor products in both systems. Also in both systems, non-extractable residues 

were a maximum 25.9-35.0% of the applied and CO2 totaled 35.6-52.5%.
164

Results

Test system used: United Kingdom pond water-sandy silt loam sediment system 

Linear half-life in water: 8.2 days (r2= 0.7212).

Linear half-life in sediment: 19.5 days (r2= 0.9945).

Linear half-life in the total system: 18.5 days (r2= 0.9955).

Nonlinear half-life in water: 0.45 days (r2= 0.8905).

Nonlinear half-life in sediment: 22.1 days (r2= 0.9981).

Nonlinear half-life in the total system: 17.7 days (r2= 0.9979).

Major transformation products (total system): 

DM-TM (maximum 23.4% of applied at 30 days post-treatment).

CO2 (maximum 52.5% at 100 days).

Minor transformation products (total system): 

ph-CH3[DCMP] (maximum 6.5% of applied at 30 days).

DM-TMO (maximum 2.9% at 62 days).

TM-COOH (maximum 0.2% at 3-7 days).

Test system used: United Kingdom lake water-sandy loam sediment system.

Linear half-life in water: 9.3 days (r2= 0.9122).

Linear half-life in sediment: 30.9 days (r2= 0.9519).

Linear half-life in the total system: 25.4 days (r2= 0.9708).

Nonlinear half-life in water: 0.95 days (r2= 0.9157).

Nonlinear half-life in sediment: 38.5 days (r2= 0.9809).

Nonlinear half-life in the total system: 23.8 days (r2= 0.9739).

Major transformation products (total system): 

DM-TM (maximum 13.4% of applied at 30 days post-treatment).

CO2 (maximum 35.6% at 100 days).

Minor transformation products (total system): 

ph-CH3[DCMP] (maximum 2.6% of applied at 30 days).

DM-TMO (maximum 5.4% at 30 days).

TM-COOH (maximum 0.9% at 7 days).

Anaerobic Aquatic Metabolism (MRID 431281-01)

Study Classification

This study was classified as acceptable and fulfills the data requirements of EPA Pesticide 

Assessment Guidelines, Subdivision N/Section 162-3 on anaerobic aquatic metabolism.

Material and Methods

Air-dried, sieved (2 mm) sandy loam soil (70% sand, 18% silt, 12% clay. 0.8% organic matter. 
165

pH 7.1, CEC 7.0 meq/100 g) was weighed (10 g dry weight) into glass containers and mixed 

with 40 mL of a peptone solution (2.5 mg/mL) that had been treated with bubbling nitrogen gas 

for 60 minutes. The samples were mixed "thoroughly", the containers were sealed, and the soi1: 

water mixtures were incubated in the dark at 25 ±1 °C for 31 days. After the pre-incubation, the 

samples were treated a t 16.5 ppm (based on the soi1dry weight) with phenyl ring-labeled [U14C] tolclofos methyl (0-2.6-dichloro-p-tolyl 0.0-dimethyl phosphorothioate; radiochemical 

purity 99.6%, specific activity 30.0 mCi/mMol. Sumitomo Chemical Company) dissolved in 

acetonitrile. The individual treated soi1 samples were mixed "thoroughly" and transferred to 

glass incubation vessels equipped with inlet and outlet ports. The vessels were purged with 

nitrogen immediately post-treatment and a t approximately 2-week intervals; nitrogen gas was 

drawn through the sample vessel, then through ethylene glycol and 0.5 N NaOH trapping 

solutions. The inlet and out1et ports remained closed except during volatile collection.

"On each sample day of the volatile trap solutions, the incubation vessels and connections were 

rinsed with acetone. The samples were incubated in a temperature-controlled room at 25 ±1 °C in 

darkness. Duplicate vessels of the treated soi1: water solutions were collected for analysis at 0, 1, 

3, 7, 14, 30, 59, 62, 92, 120, 182, 282, and 364 days post-treatment. The pH and redox potential 

of the samples were measured a t the time of sampling. 

The soil: water solutions were analyzed according to the schemes presented in Figures 5 and 6 of 

the study report. After sampling, the samples were centrifuged, and the water and soi1 phases 

were separated. A1iquots of the water phase were analyzed for total radioactivity using LSC. The 

remaining water was partitioned three times against methylene chloride: aliquots of the 

combined methylene chloride extracts and of the extracted floodwater were analyzed using LSC. 

Additional aliquots of the methylene chloride solutions were washed with a saturated NaCl 

solution and fi1tered through a si1icone-treated' phase separator. The filtered solutions were 

concentrated a t 40 °C under reduced pressure; the concentrated solutions were diluted with 

methanol, filtered (0.5 μm) , and analyzed by reverse-phase HPLC using a Sumipax 00s-A212 

column coupled with a μ-Bondapak C-18 guard column, and eluted with a water: acetonitrile: 

methanol gradient : the column was equipped with UV (254 or 210 nm) and radioactive flow 

detection. Aliquots of the extracted flood water were freeze-dried. The residues were dissolved 

in methanol: water (4:1, v: v), and aliquots of the solutions were filtered (0.5 um) and analyzed 

by HPLC as described. All samples were co-chromatographed with non-labeled reference 

standards. Limits of detection were reported to be 0.00045 μg for LSC and 0.0045 μg for HPLC.

The soi1 fractions were extracted three times with acetone: water (5: 1, v: v) by shaking for 10 

minutes per extraction; after each extraction, the mixtures were centrifuged and the supernatant 

removed. The extracts were combined: and aliquots of the extracts were analyzed for total 

radioactivity using LSC. The acetone was removed from the extracts using a rotary evaporator at 

40 °C. The resulting aqueous solutions were partitioned three times against methylene chloride; 

the methylene chloride extracts from each solution were combined, and aliquots of the methylene 

chloride and aqueous phases were analyzed using LSC. Prior t o HPLC analysis, additional 

aliquots of the methy1ene chloride and aqueous phases were prepared as described with a 

saturated NaCl solution. The extracted aqueous solution was neutralized with a 0.5 N NaOH 

solution, and the resulting precipitate was separated from the solution by centrifugation; aliquots 

of the supernatant were analyzed using LSC, and the radioactivity in the precipitate ("humic 
166

substance”) was determined by difference (rather than direct analysis). Additional aliquots of the 

neutralized supernatants were prepared by freeze-drying prior t o HPLC analysis.

Identification of tolclofos methyl and DM-TM isolated by HPLC was also confirmed using 

LC/MS. I n addition, identification of tolclofos methyl and DM-TM was confirmed using twodimensional TLC on silica gel plates developed in chloroform: methanol (9: 1, v: v) in the first 

direction and either toluene: ethyl formate: formic acid (5:7: 1, v: v: v) or ethyl acetate: ethanol: 

water (4: 2: 1, v: v: v) in the second direction. Identification of DM-TM was also confirmed 

using one directional TLC on silica gel plates developed ethyl - acetate: ethanol :water (4: 2: 1, 

v:v: v) and 2-propanol : "ammonia water" :water (9: 1:2, v:v:v) . Identifications of ph-CH3, DCph-CH3 and p-cresol isolated by HPLC, were confirmed using one-dimensional TLC on si1ica 

gel p1ates developed chloroform: acetone (9: 1, v: v) , and/ two-dimensional TLC on silica gel 

plates developed in n- hexane : -acetone (5: 2, v: v) in the first direction and chloroform: acetone

(9:1, v:v) in the second direction. All compounds were co-chromatographed with reference 

standards. [14c] residues on the plates were visualized using autoradiography. 

The extracted' soils that contained >9.0% of the applied radioactivity were further extracted with 

0.5 N NaOH by shaking for 24 hours, then centrifuged. The NaOH extract was acidified; the 

resulting precipitate (humic acid) and supernatant (fulvic acid) were separated by centrifugation, 

the precipitate was dissolved in a 0.5 N NaOH solution, and aliquots of the NaOH solution and 

supernatant were analyzed by LSC. The extracted sediment (humin fraction) was air-dried and 

analyzed using LSC following combustion. Aliquots of the acetone rinses of the incubation 

vessels and connections were analyzed by LSC. Aliquots of the ethylene glycol trapping 

solutions were mixed with methanol and analyzed for total radioactivity using LSC. Aliquots of 

the NaOH trapping solutions were analyzed using LSC. Identification of [14C] residues in the 

NaOH solution as CO2 was confirmed by precipitation with Bariurn chloride. 

To confirm the production of 14 CH4 from 14C-ph-CH3 during degradation, an anci1lary 

experiment was conducted in which sieved sandy loam soil was weighed (20 g dry weight) into a 

glass container and mixed with 80 mL of peptone solution. The container was sealed with an 

open top screw cap that was equipped with a Teflon-1aminated si1icone disc, and the sample 

was incubated in the dark at 25 ± 1 oC for 5 days. After the pre-incubation, the soils were treated 

at 10 ppm (based on the soi1 dry weight) with phenyl ring labeled [U14C] 2, 6-dichloro-4-

methyl phenol (ph-CH3): radiochemical purity 100%, specific activity

I 41.6 mCi /mMol, Sumitomo Chemical Company) dissolve in benzene: n-hexane (1:1), then 

returned t o the incubation chamber. Aliquots of the water 1ayer were collected through the 

si1icone disc using a micro syringe without opening the sample container at 0, 2. 5, 12, 19, 26, 

33, and 54 days post-treatment: aliquots of the headspace gas were collected using a gastight 

syringe at 0, 19, 26, 33, and 54 days post-treatment. The water layer was fi1tered (0.5 μm) and 

analyzed by reverse-phase- HPLC: the columns previously described were eluted with water: 

methanol gradient. The headspace gases were analyzed using GC equipped with thermal 

conductivity detection.

Results
167

Phenyl r in g-1abeled [U14C] tolclofos methyl (O -2,6-dichloro-p- tolyl O,O-dimethyl 

phosphorothioate; radiochemical purity 99.5%3, at 16.5 ppm, degraded with a registrantcalculated ha1f-1ife o f 31 days (reviewer calculated for all data points= 47 days) in an anaerobic 

sandy loam soil : water mixture that was incubated in the dark at 25 ± 1 oC for 364 days. [14C] 

tolclofos methyl averaged 97.79% of the applied immediately post-treatment, 62.72% at 30 days, 

35.12%, at 59 days, 19.22% at 92 days, 5.15% at 120 days, and <l . 07% at 364 days (Tables 

XVII-2 and XX-2 of the report). Four degradates were identified in the soi1: water mixture:

O-2, 6-dichloro-p-tolyl O-methyl O-hydrogen phosphorothioate (DM-TM);

2, 6-dichloro-4-methyl phenol (ph-CH3);

4-methylphenol (p-cresol); and

2-chl oro-4-methylphenol (DC-ph-CH3).

DM-TM, the major degradate, increased steadily to a maximum average of 57.97% of the 

applied at 92 days post-treatment (54.08 and 3.89% in the water and soil, respectively), and was 

2.37% at 364 days. DC-ph-CH3, averaged a maximum 10.18% of the applied at 30 days posttreatment; ph-CH3 averaged a maximum 8.04% at 364 days; and p-cresol averaged a maximum 

of 4.67% at 14 days. A t 1east 21 other [14C] compounds were isolated from the soil or water; 

one of these I G-1 (B-1) averaged a maximum o f 1.71% o f the applied (0.07 ppm) in the water 

on day 120, and each of the remaining compounds averaged ≤1.0 6%.

Evolved 14CO and other [14C] volatiles trapped by NaOH totaled 21.93-24.02% and 6.47-0.54% 

of the applied respectively, at 364 days post-treatment (Table IV-1). [

14C] volatiles trapped by 

ethylene glycol totaled 1.22- 1.29% of the applied at 364 days post-treatment; and additional 

0.19-0.20% was recovered from the walls of the sample container (Table X – 1 of the study

report). Un-extracted [14C] residues averaged <5.0% of the applied through 120 days posttreatment; un-extracted [14C] residues averaged 7.85-8.69% at 182 through 364 days, during 

which time the ratio of fulvic acid to humic acid to humin ranged from 1:3.7: 1 to 1:6:l 

(TablesIV-2and XXIII of the study report). The distribution of [14C] residues between the soi1 

and water fractions was approximately 1: 1 through 3 days post-treatment, 1:3 at 62 through 120 

days, and 1: 1 at 364 days. Material balances were 95.00-99.55% of the applied through 30 days 

post-treatment, 77.52-96.42%) at 59 through 92 days, and 41.69-69.59% at 120 through 364 days 

(Table IV-1 of the study report). 

In an anci11ary experiment in which an anaerobic sandy 1oam soil: water mixture was treated at 

10 ppm with phenyl ring-labeled [U14C] 6-dichl oro-4-methyl phenol (ph-CH3); radiochemical 

purity 100%) and incubated in the dark at 25 ± 1 oC, the study authors demonstrated that 14CH4, 

which was not trapped by either the ethylene glycol or NaOH solutions was a major degradate 

during the anaerobic aquatic metabolism of tolclofos methyl , and its omission could account for 

the low material balance in the definitive experiment. At 364 days post-treatment, 14CH4 

comprised 57.02% of the applied radioactivity (Table XX V II of the study report).

Adsorption/desorption (MRID 422733-01)

Study Classification
168

This study was classified as supplemental for the data requirements of EPA Pesticide 

Assessment Guidelines, Subdivision N/Section 163- on un-aged adsorption/desorption. The 

study was classified as supplemental because concentrations of the amount of material adsorbed 

were obtained by subtraction. 

Material and Methods

To determine adsorption, duplicate 1 gram (dry weight) soil samples were shaken for 2 hours 

with 4, 10 ml test solutions of 0.019, 0.037, 0.201 and 0.391 μg/ml at 25 ± 1°C. The soil/water 

was centrifuged and aliquots of the supernatant were analyzed by LSC. The amount of material 

adsorbed was the amount of 14C in the supernatant minus the applied. The soil/water was then 

extracted and the soil residue was combusted to determine total radioactivity. 

To determine desorption, duplicate 1 gram (dry weight) soil samples were shaken 2 hours with 4, 

10 ml test solutions of 0.019, 0.037, 0.201, and 0.391 μg/ml at 25 ± 1°C. After adsorption 

equilibrium took place (2 hours) 5 of the 10 mL were replaced with fresh 0.01 M CaCl2 

containing no test substance. Duplicate 1 mL aliquots were analyzed by LSC. The soil/water 

suspensions were shaken for 1 hour to obtain the desorption equilibrium. The soil/water was then 

centrifuged and the supernatant was analyzed by LSC. The amount of material desorbed was the 

amount of 14C in the soil at desorption equilibrium from the soil at the adsorption equilibrium.

Results

(1) The Freundlich coefficients for adsorption (Kdads,)/(l/Nads) were 7.59/0.94,

25.17/0.95, 43.96/0.96, and 24.03/0.94 for the sandy loam soil (California), loamy sand soil (B7), silty clay loam soil (F-6) and the clay soil, respectively. The Koc, adsorption constants were 

1,649, 6,139, 3,209, and 3,482 for the above soils respectively;

(2) The Freundlich coefficients for desorption (Kddes)/(l/Ndes) were 11.83/0.98,

26.97/0.91, 58.96/0.99, and 29.26/0.95 for the sandy loam soil (California), loamy sand soil (B7), silty clay loam soil (F-6) and the clay soil, respectively. The Koc, desorption constants were 

2,572, 6,578, 4,304, and 4,241for the above soils respectively;

(3) The average recovery of the adsorption test system was 90.9 to 105.7% of the applied. The 

average recovery of desorption test system was 90.6 to 104.1% of applied;

(4) Little degradation of the test substance occurred during the adsorption/desorption 

experiment; 92.9 to 98.5% of the recovered 14C was unchanged starting material;

(5) The adsorption and desorption equilibrium were clearly reached after 2 and 1 hour 

respectively; and

(6) Less than 3% of the applied 14C was adsorbed to the test vessel so no correction factor was 

introduced into any equation.
169

Study Classification

This study was classified as supplemental for the data requirements of EPA Pesticide 

Assessment Guidelines, Subdivision N/Section 163- on un-aged adsorption/desorption. The 

study was classified as supplemental because adsorbed amount was derived by subtraction, mass 

balance data were not reported (reported only for one sample from each soil and was acceptable), 

desorption phase was not conducted, No analysis for transformation products was conducted for 

the samples but was conducted for the control which showed low degradation (degradation <5% 

of the applied in addition old data from previous study indicated that the level of transformation 

products was very low). 

The adsorption/desorption characteristics of [U-phenyl14C]-labelled (O-2, 6-dichloro-p-tolyl

O,O-dimethyl phosphorothioate (tolclofos methyl; radiochemical purity >99.6%) were studied in 

two U.S. soils: a loam soil [pH 6.9, organic carbon 1.2%] and a sand soil [pH 6.1, organic carbon 

0.64%], in a batch equilibrium experiment. The adsorption phase of the study was carried out by

equilibrating air-dried, sieved soil with [14C] tolclofos methyl at measured concentrations of 

0.54, 0.11, 0.021, and 0.004 mg/kg for the loam soil and 0.63, 0.12, 0.021, and 0.004 mg/kg for 

the sand soil. The test soils were equilibrated at 25 ± 1oC for 6 hours in the dark. The 

equilibrating solution used was 0.01M CaCl2 solution, with soil solution ratios of 1:15 (w: v) for 

the loam soil and 1:10 (w: v) for the sand soil. A desorption phase was not conducted.

Following the adsorption phase, the supernatant solutions were separated by centrifugation and 

analyzed for radioactivity using LSC. The supernatant and soil samples were not analyzed for 

parent or transformation products.

The experimental temperature employed during the study was reported to be maintained at 25 ± 

1oC; supporting details were not provided. The pH of the loam soil-solution was 6.45 before 

incubation and 6.44 after incubation, and the pH of the sand soil remained at 5.55 before and 

after incubation. HPLC analysis of the control sample solution phase showed that tolclofos 

methyl was stable, with <5% degradation. 

Mass balances at the end of the adsorption phase were not reported, and could not be determined 

due to insufficient data. Mass balances determined for single samples of the loam soil treated at 

0.54 and 0.021 ppm were 101.2-102.1% (20.5-27.4% in the adsorption supernatant extracts, 

71.3-76.7% in the soil extracts, and 3.4-4% in the post-extracted solids). Mass balances 

determined for single samples of the sand soil treated at 0.63 and 0.021 ppm were 96.9-103.2% 

(25.8-34.0% in the adsorption supernatant extracts, 62.0-75.9% in the soil extracts, and 0.9-1.4% 

in the post-extracted solids). 

The percent of the applied tolclofos methyl residues that were adsorbed to the test soils could not 

be determined from the available data.

Using the Standardized Soil Mobility Classification Guidance according to the Food and 

Agriculture Organization (FAO) of the United Nations adopted by USEPA and using reviewer 

calculated adsorption Koc values presented in Table 8 of this DER, tolclofos-methyl is 

characterized as being slightly mobile in the loam and sand soils. 
170

Adsorption Results (No desorption step)

Soil type: Loam Sand

Adsorption

Average Kd 52.27  10.86 26.92  6.84

Average Koc 4,284 4,206

Regression

Kd 38.08 18.93

r

2

0.9972 0.9963

p-value 3.30E-10 9.28E-10

Freundlich 

Regression 

Freundlich KF 32.39 16.26

p-value 7.36E-11 8.83E-09

r

2

0.9996 0.9987

1/n 0.90 0.89

p-value 1.67E-11 7.37E-10

Freundlich KFoc 2,655 2,541

Adsorption/desorption (MRID 422733-01)

Study Classification

This study was classified as supplemental for the data requirements of EPA Pesticide 

Assessment Guidelines, Subdivision N/Section 165-4 on bio-concentration in fish because the 

fish were not exposed to a constant concentration of pesticide and residues in the water were not 

characterized.

Materials and Methods

Bluegill sunfish (Lemnis macrochirus; average length and weight of 47 mm and 3.4 g, 

respectively) were held in culture tanks on a 16-hour daylight photo period for ≥14 days prior to 

the initiation of the study. Flow-through aquatic exposure system was prepared using two 100-L 

aquaria. Aerated well water was provided to each aquarium at a rate of 7.2-8.6 turnovers per day. 

The aquaria were immersed in a water bath and maintained at 22 ±2°C.

Bluegill sunfish (120) were placed in each aquarium, and one aquarium was continually treated 

with ring-labeled [14C] tolclofos-methyl (radiochemical purity >99%, specific activity 7,700 

dpm/μg, Sumitomo Chemical Company) at 0.03 ppm. The second aquarium served as an 

untreated control. Following a 28-day exposure period, the [14C] tolclofos-methyl treated water 

was replaced with untreated water for a 14-day depuration period. The treated water was 

sampled prior to introducing the fish, and then water samples and fish (6, 15, or 25) were taken 

from the treated and control aquaria after 4 hours and 1, 3, 7, 14, 21, and 28 days of exposure.

During the depuration period, water samples and [14C] tolclofos-methyl treated water and 

untreated fish were taken on days 1, 3, 7, 10, and 14.

Radioactivity in the water samples was quantified using LSC. The detection limit was 0.0004 

ppm.
171

Pooled samples (3 fish) of whole fish, edible tissues (body, muscle, kin, and skeleton) and nonedible tissues (fins, head, internal organs) were homogenized with dry ice and analyzed for total 

radioactivity using combustion and LSC. Reported recoveries of [14C] residues from whole fish, 

edible tissues, and non-edible tissues fortified with 0.55 μg of [14C] tolclofos-methyl ranged from 

95 to 101%. The detection limits for whole fish, edible tissues, and non-edible tissues were 

0.021, 0.019, and 0.021 ppm, respectively.

Additional samples of the edible and non-edible tissues from days 21 and 28 of the exposure 

period were separately homogenized with water, acidified to pH 1 with hydrochloric acid, and 

extracted three times with diethyl ether (MRID 00163642). Diethyl ether extracts were 

combined, dried over anhydrous sodium sulfate, and evaporated to dryness. The remaining 

residue was dissolved in hexane: methylene dichloride (85:15) and passed through a gel filtration 

column (Bio-Beads S-X3). Ten 10 mL fractions were collected. Fractions 4-10 were combined, 

concentrated by evaporation and analyzed by TLC on silica gel plates developed in toluene: 

acetic acid (91:13), toluene: ethyl acetate: formic acid (45:63:9), or toluene: ethyl acetate: 

isopropanol: acetic acid (32:48:20:12). Reference compounds were co-chromatographed with the 

samples and, following development, were visualized under UV light. Radioactive areas were 

detected by autoradiography. Degradate characterizations were also confirmed by GC using 

electron-capture detection. The extracted fish tissue and remaining aqueous phase (from diethyl 

ether extraction) were refluxed for 1 hour, and then extracted three times with ether. Ether 

extracts were combined, dried over anhydrous sodium sulfate, concentrated, and analyzed by

TLC, as described above. Un-extractable 14C residues remained in the fish tissue were 

quantified by combustion and LSC.

Results

Total 14C tolclofos-methyl residues accumulated in bluegill sunfish with maximum bioconcentration factors of 120, I, 300, and 770x in edible tissues (body, muscle, skin, skeleton), 

non-edible tissues (fins, head, internal organs), an d whole fish, respectively , during 28 days of 

exposure t o tolclofos-methyl residues at 0.012-0.037 ppm in a flow-through system (MRID 001 

63641). Maximum levels of [14C] residues were 3.2 ppm in edible tissues, 36 ppm in non-edible 

tissues, and 20 ppm in whole fish. After 28 days of exposure, tolclofos-methyl comprised 81.2 

and 38.8% of the radioactivity in the edible and non-edible tissues, respectively. After 14 days of 

depuration, [14C] residues in edible tissues, non-edible tissues, and whole fish were 0.043, 0.28, 

and 0.18 ppm, respectively.

Degradates detected in extracts from the edible and non-edible tissues include:

 O,O-dimethyl O-(2,6-dichloro-4-formylphenyl) phosphorothioate (TM-CHO);

 3 ,5-dichloro-4-hydroxybenzaldehyde (ph-CHO);

 3,5-dichloro-4-hydroxybenzoic acid (ph-COOH);

 O,O-dimethyl O-(2,6-dichloro-4-methylphenyl) phosphate (TMO);

 3,5-dichloro-4-hydroxybenzyl alcohol (ph-CH2OH); and seven unknowns (MRID 

00163642).
172

Independent Laboratory Validations (ILVs) for the Environmental Chemistry Method for 

determination of TM in soil (48341916 and 488421-02)

An analytical method (Analytical Procedure CLE 333/153-04R) was developed to detect and 

quantify residues of tolclofos-methyl in soil (Appendix 1, pp. 21-30). This study was conducted 

in accordance with Council Directive 91/414/EEC (1991) as amended by Commission Directive 

96/46/EC (1996), EU Guidance documents SANCO/825/00, rev. 6 (2000) and SANCO/3029/99, 

rev. 4 (2000), and in compliance with United Kingdom GLP Regulations (1999) and OECD 

Principles of GLP ENV/MC/CHEM(98)17 (1998; pp. 2, 9). Untreated (control), sieved (2-mm) 

soil (pH 4.9-5.5, organic matter 2.4%), characterized as a sandy loam (USDA), was obtained 

from Covance Laboratories Ltd. Environmental Fate Department and stored frozen (-20°C) prior

to use (p. 10; Appendix 5, p. 41). Soil moisture content was determined prior to fortification 

(Appendix 1, p. 26). Aliquots (50 g) of soil were weighed into 500-mL glass jars and fortified 

with tolclofos-methyl (purity 99.8%, Lot No.: 00404SG), in acetone, at 0.01 and 10.0 mg a.i./kg; 

five treated samples per fortification level (p. 11; Appendix 1, pp. 24, 26). Application solution 

volumes were 100 μL (5 μg a.i./mL) and 1 mL (500 μg a.i./mL) for the 0.01 and 10.0 mg a.i./kg 

test concentrations, respectively (p. 11). Two untreated soil samples were included as controls 

(Table 1, p. 17). Following fortification, water was added to yield a final volume of 100 mL, 

taking into account soil moisture content, and the sample allowed to stand 10 minutes (Appendix 

1, p. 26). The sample was then extracted once with acetone (200 mL) using mechanical shaking 

(interval not reported; Appendix 1, pp. 23, 26). Extract and soil were separated by filtration (No. 

1 filter paper) via Buchner funnel. An aliquot of the extract was treated with sodium chloride 

(10:1, v:w), shaken, then partitioned once with methylene chloride. The resulting aqueous phase 

was discarded and the retained organic phase filtered through sodium sulphate. The separatory

funnel and remaining filter cake were rinsed twice with ethyl acetate and the rinses added to the 

organic phase. The sample was concentrated to near dryness using rotary evaporation (30°C), 

then taken to dryness under nitrogen. Residues were reconstituted in cyclohexane:ethyl acetate 

(1:1, v:v), treated with sodium sulphate, decanted and an aliquot processed through gel 

permeation chromatography (GPC) under the following conditions: Bio-Beads S-X3 (200-400 

mesh), eluant cyclohexane:ethyl acetate (1:1, v:v), flow rate 5.0 mL/minute (Appendix 1, pp. 25-

26). The collected fraction (retention time not reported) was taken to dryness (rotary

evaporation, 30°C). Residues were reconstituted in toluene for GC/MS analysis with electron 

impact ionization in positive mode (EI+) and selected ion recording (SIR; Appendix 1, pp. 26-

27). Three ions were monitored; 265 as the primary quantitation ion, 267 and 250 as 

confirmation ions. Retention time for tolclofos-methyl was ca. 10.0 minutes (Appendix 4, pp. 

36-37, 39-40). 483 (p. 14). 

Quantitation ion. Overall recovery averaged 98 ± 12.4% (mean ± RSD, range 82-124%, n = 10) 

of the applied (Tables 1-3, pp. 17-19). Per fortification level, recoveries averaged (n = 5) 95 ± 

18.2% (82-124%) and 102 ± 2.5% (98-104%) at the 0.01 and 10 mg a.i./kg test concentrations, 

respectively. Analysis of unfortified control soil detected minor levels of residues (0.0014-

0.0028 mg/kg, <30% of LOQ) at the retention time of tolclofos-methyl, with no other significant 

interferences (Table 1, p. 17; Appendix 4, p. 38). Recoveries from fortified soil were corrected 

for mean residue level detected in the control samples (Table 1, p. 17). Detector responses for 
173

tolclofos-methyl were linear (r2= 0.997) over the range of 0.01-0.50 μg/mL (p. 13; Appendix 3, 

p. 33).

Confirmation ions. Results for both confirmation ions satisfied the study author's criteria that all 

mean recoveries were within the range of 70-110% and RSD values were <20% (pp. 11-12, 14; 

Tables 2-3, pp. 18-19).

Environmental Chemistry Method for determination of TM in Water (483419-17 and 

488421-01)

Multi-residue method F12 (Deutsche Einheitsverfahren zur Wasser-, Abwasser- und 

Schlammuntersuchung) of EU Guidance document SANCO/825/00 was used to detect and 

quantify residues of tolclofos-methyl in water (pp. 12, 17). This study was conducted in 

accordance with Commission Directive 96/46/EC (1996), EU Guidance documents 

SANCO/825/00, rev. 6 (2000) and SANCO/3029/99, rev. 4 (2000), and in compliance with 

Swiss GLP Ordinance RS 813.016.5 (2000; pp. 3, 10). Aliquots (1 L) of drinking (tap) water 

(pH 7.00, DOC 6.9 mg C/L) were fortified with tolclofos-methyl (purity 99.8%, Lot No.: 

00404SG), in acetone, at 0.1 and 1.0 μg/L; five treated samples per fortification level (pp. 13-14, 

16, 21; Appendix I, p. 38). Application solution volumes were 100 μL at both fortification 

levels, with a final co-solvent (acetone) concentration of 0.01% (p. 16). Two untreated water 

samples were included as controls (Table 1, p. 23). Each water sample was applied (flow rate 5-

10 mL/minute) to a C18 solid phase extraction (SPE) cartridge (Mega bond Elut, 2 g/12 mL) preconditioned with methanol and water (pp. 15, 17). The loaded SPE cartridge was dried under 

vacuum 1-2 minutes, then tolclofos-methyl was eluted (flow rate 5-10 mL/minute) with two 

volumes (10 mL x 2) of methylene chloride. Eluates were combined and filtered over anhydrous 

sodium sulphate, with the remaining filter cake then rinsed with methylene chloride. The sample 

was concentrated to near dryness using rotary evaporation (30-40°C), then taken to dryness 

under nitrogen. Residues were reconstituted in toluene for GC analysis with flame photometric 

detection (FPD, P-mode; pp. 17-18). GC retention time for tolclofos-methyl was ca. 13.1 

minutes (p. 18; Figures 1-2, pp. 26-27; Figures 4-5, pp. 29-30). As a confirmatory method, 

selected samples were analyzed by GC/MS with electron impact ionization in negative mode (EI-

), full-scan and selected ion monitoring (SIM; pp. 19, 22). GC/MS retention time for tolclofosmethyl was ca. 11.2 minutes (p. 19; Figures 6-7, pp. 31-32; Figures 9-11, pp. 34-36). For both 

analytical methods, the limit of detection (LOD) for tolclofos-methyl was estimated at ca. 

0.01μg/mL, based on lowest calibration standard, and the limit of quantitation (LOQ) established 

at 0.1 μg/L (pp. 21-22).

Primary GC analysis. Overall recovery averaged 90.8 ± 5.8% (mean ± RSD, range 81.8-100.1%, 

n = 10) of the applied (p. 21; Tables 1-2, p. 23; DER Attachment 2). Per fortification level, 

recoveries averaged (n = 5) 87.7 ± 4.8% (81.8-93.4%) and 93.8 ± 4.8% (89.1-100.1%) at the 0.1 

and 1.0 μg a.i./L test concentrations, respectively. Analysis of unfortified control water found no 

interferences at the retention time of tolclofos-methyl (Figure 3, p. 28). Correlation of detector 

responses for tolclofos-methyl was determined using a non-linear function (r2= 0.998) due to the 

range of the calibration curve at 0.01-1.0 μg/mL (p. 21; Table 3, p. 24).
174

Confirmatory GC/MS analysis. Results for tolclofos-methyl in drinking (tap) water using 

GC/MS analysis were consistent with those determined by the primary GC analysis method (p. 

22; Table 1, p. 23; Table 4, p. 25; Figure 8, p. 33).

Independent Laboratory Validations (ILVs) for the Environmental Chemistry Method for 

determination of TM in Water (483419-18 and 488421-03)

Multi-residue method F12 (Deutsche Einheitsverfahren zur Wasser-, Abwasser- und 

Schlammuntersuchung) of EU Guidance document SANCO/825/00 was used to detect and 

quantify residues of tolclofos-methyl in water (pp. 12, 17). This study was conducted in 

accordance with Commission Directive 96/46/EC (1996), EU Guidance documents 

SANCO/825/00, rev. 6 (2000) and SANCO/3029/99, rev. 4 (2000), and in compliance with 

Swiss GLP Ordinance RS 813.016.5 (2000; pp. 3, 10). Aliquots (1 L) of surface (river) water 

(pH 7.54, DOC and TOC 8.2 mg C/L) were fortified with tolclofos-methyl (purity 99.8%, Lot 

No.: 00404SG), in acetone, at 0.1 and 1.0 μg/L; five treated samples per fortification level (pp. 

13-14, 16, 21; Appendix I, p. 38). Application solution volumes were 100 μL at both 

fortification levels, with a final co-solvent (acetone) concentration of 0.01% (p. 16). Two 

untreated water samples were included as controls (Table 1, p. 23). Each water sample was 

applied (flow rate 5-10 mL/minute) to a C18 solid phase extraction (SPE) cartridge (Mega bond 

Elut, 2 g/12 mL) pre-conditioned with methanol and water (pp. 15, 17). The loaded SPE 

cartridge was dried under vacuum 1-2 minutes, then tolclofos-methyl was eluted (flow rate 5-10 

mL/minute) with two volumes (10 mL x 2) of methylene chloride. Eluates were combined and 

filtered over anhydrous sodium sulphate, with the remaining filter cake then rinsed with 

methylene chloride. The sample was concentrated to near dryness using rotary evaporation (30-

40°C), then taken to dryness under nitrogen. Residues were reconstituted in toluene for GC 

analysis with flame photometric detection (FPD, P-mode; pp. 17-18). GC retention time for 

tolclofos-methyl was ca. 13.1 minutes (p. 18; Figures 1-2, pp. 26-27; Figures 4-5, pp. 29-30). As 

a confirmatory method, selected samples were analyzed by GC/MS with electron impact 

ionization in negative mode (EI-), full-scan and selected ion monitoring (SIM; pp. 19, 22). 

GC/MS retention time for tolclofos-methyl was ca. 11.2 minutes (p. 19; Figures 6-7, pp. 31-32; 

Figures 9-11, pp. 34-36). For both analytical methods, the limit of detection (LOD) for 

tolclofos-methyl was estimated at ca. 0.01μg/mL, based on lowest calibration standard, and the 

limit of quantitation (LOQ) established at 0.1 μg/L (pp. 21-22).

Primary GC analysis. Overall recovery averaged 94.4 ± 10.3% (mean ± RSD, range 82.1-

107.4%, n = 10) of the applied (p. 21; Tables 1-2, p. 23; DER Attachment 2). Per fortification 

level, recoveries averaged (n = 5) 85.7 ± 4.2% (82.1-90.1%) and 103.1 ± 2.8% (100.4-107.4%) at 

the 0.1 and 1.0 μg a.i./L test concentrations, respectively. Analysis of unfortified control water 

found no interferences at the retention time of tolclofos-methyl (Figure 3, p. 28). Correlation of 

detector responses for tolclofos-methyl was determined using a non-linear function (r2= 0.9968) 

due to the range of the calibration curve at 0.01-1.0 μg/mL (p. 21; Table 3, p. 24).

Confirmatory GC/MS analysis. Results for tolclofos-methyl in surface (river) water using 

GC/MS analysis were consistent with those determined by the primary GC analysis method (p. 
175

22; Table 1, p. 23; Table 4, p. 25; Figure 8, p. 33).

II. Detailed Fate Properties Table

Detailed fate properties table for TM in biotic systems

Detailed fate properties table for TM in biotic systems

(1) Aerobic soil metabolism

Property/Description or Value

(a) MRID 001561-06 “Supplemental”; Two Soils (Viable & Sterilized)

Viable Soil 1 

t1⁄2= 48 days (t1⁄2= 239 days TTR)

Major degradates:

CO2: max= 17.0% @ 90 d

DM-TM: max= 11.0% @ 60 d declined to 3.7% @ 180 d

Minor degradates:

DM-TMO: max= 3.4% @ 180 d 

ph-CH3: max= 3.9-4.1% @ 60-180 d with no apparent decline

TMO: max= 0.9-1.3% @ 60-180 d with no apparent decline

TM-CH2OH; TM-COOH; TMO-CH2OH; TMO-COOH; phCH2OH; ph-COOH: max= 0.3-0.4% each @ 60-180 d

Unidentified: max= 4.6% @ 60-120 d declined to 4.0% @ 180 d

Others:

Organic volatiles: 19.6% @ 180 d

Bound residues: max 53.4% @ 120 d declined 50.8% @ 180 d

Sterilized Soil 1 

t1⁄2= 80 days (t1⁄2 was not calculated for the TTR)

Major degradates:

None

Minor degradates:

DM-TM: max= 0.4% @ 30 d 

DM-TMO: max= 0.8% @ 60 d 

ph-CH3: max= 3.1% @ 30 d

TMO: max= 0.2% @ 30 d

TM-CH2OH; TM-COOH; TMO-CH2OH; TMOCOOH; ph-COOH: max= 0.1-0.2% each @ 30 d

CO2: max= <0.1% @ 30 d

TMO-COOH & ph-CH2OH: <1% throughout

Unidentified: max= 2.0% @ 30 d

Others:

Organic volatiles: 0.2% @ 30 d

Bound residues: max 19.1% @ 30 d
176

Viable Soil 2 

t1⁄2= 44 days (210 days TTR)

Major degradates:

CO2: max= 22.9% @ 90 d

Minor degradates:

DM-TM: max= 4.9% @ 90 d declined to 0.9% @ 180 d

DM-TMO: max= 1.8% @ 14 d declined to 0.9% @ 180 d

ph-CH3: max= 2.6% @ 14-90 d declined to 0.9% @ 180 d

TMO: max= 0.6% @ 90 d declined to 0.3% @ 180 d

TM-CH2OH; TM-COOH; TMO-CH2OH; TMO-COOH; phCH2OH; ph-COOH: max= 0.2-0.4% each @ 14-120 d declined to 

0.3-<0.1% @ 180 d

Unidentified: max= 3.3% @ 180 d

Others:

Organic volatiles: 28.6% @ 180 d

Bound residues: max 46.6-47.0% @ 120-180 d

Sterilized Soil 2 

t1⁄2= 116 days (t1⁄2 was not calculated for the TTR)

Major degradates:

None

Minor degradates:

DM-TM: max= 2.1% @ 30 d 

DM-TMO: max= 0.4% @ 30 d 

ph-CH3: max= 2.8% @ 30 d

TMO: max= 0.2% @ 30 d

TM-CH2OH; TM-COOH; TMO-CH2OH; TMOCOOH; ph-COOH: max= 0.1-0.2% each @ 30 d

CO2: max= <0.1% @ 30 d

TMO-COOH & ph-CH2OH: <1% throughout

Unidentified: max= 1.7% @ 30 d

Others:

Organic volatiles: 0.4% @ 30 d

Bound residues: max 11.0% @ 30 d

(b) MRID 427032-01 “Acceptable”

Soil 3: t1⁄2= 79 days (Parent Alone); t1⁄2= 161 days (TTR)

Major degradates:

DM-TM: max= 18.5% @ 90 d declined to % 0.7% @ 365 d (t1⁄2= 56.7 days)

CO2: max= 33.3% @ 365 d

Minor degradates:

ph-CH3: max= 2.8% @ 121 d declined to % 1.4% @ 365 d

Oxidized, hydroxylated or methylated forms of the methyl ring (26 degradates)= 3.6% @ 271 d declining to 2.7% @ 365 d 

(identified degradates included: DM-TMO-COOH; DM-TMO; TMO-COOH, SM-TM; and ph-COOH

Others:

Organic volatiles: A total of 26% @ 365 d (18% Parent, 6% ME-ph-CH3 and 2% ph-CH3)

Bound residues: max 21.0% @ 271 d declining to % 19.0% @ 365 d

(c) MRID 483419-23 supplemented by 483419-25 “Supplemental”

Experimental duration: 112 days @ 10 oC

Soil 4 Soil 5 Soil 6

t1⁄2= 28 days; 

t1⁄2= 116 days (TTR)

t1⁄2= 23 days; 

t1⁄2= 169 days (TTR)

t1⁄2= 31days; 

t1⁄2= 165 days (TTR)

Major degradates:

CO2: max= 45.7% @ 90 d

Major degradates:

CO2: max= 27.3% @ 112 d 

Major degradates:

CO2: max= 20.4% @ 112 d 
177

Minor degradates (d= days; ND= No Detection):

DM-TM: max= 0.50% @ 28 d declined ND @ 112 d

ph-CH2OH: max= 0.29% @ 28 d declined ND @ 112 d 

ph-COOH: max= 0.77% @ 28 d declined to ND @112 d

TM-COOH: max= 1.67% @ 7 d declined to 0.23% @ 112 d

TMO: max= 0.37% @ 28 d declined to ND @ 112 d

DM-TMO: max= 0.19% @ 7 d declined to ND @ 112 d

Unknowns: max= 2.62% @ 7 d declined to 1.11% @ 112 d

Minor degradates 

Not identified: max= 6.7% @ 

14 d declined to 3.0% @ 112 d 

Unknowns: max= 2.9% @ 

7 d declined to 0.03% @ 112 d

Minor degradates 

Not identified: max= 12.2% 

@ 55 d declined to 9.3% @ 

112 d 

Unknowns: max= 3.9% 

@ 7 d declined to 0.15% @ 

112 d

Others:

Bound Residues: max= 44.0% @ 84 d declined to 41.9% @ 

112 d

Volatiles: max= 0.22% @ 112 d

Others:

max= 61.0% @ 84 d declined to 

54.5% @ 112 d

max= 0.21% @ 112 d

Others:

max= 52.2% @ 112 d

max= 0.22% @ 112 d

(d) MRID 483419-22: Test Substance: DM-TM (The major TM degradate) “Acceptable”

Experimental duration: 7 days @ 20 oC (Application rate 0.26 ppm)

Soil 8 Soil 11 Soil 12

t1⁄2= 1.18 days (28.3 hours) t1⁄2= 0.55 days (13.2 hours) t1⁄2= 0.26 days (6.3 hours)
178

Major degradates:

ph-CH3: max= 15.2% @ 0 d declined 

0.6% @ 7 d 

CO2: max= 18.9% @ 7 d

Minor degradates (ND= No Detection):

DM-TMO: max= 8.6% @ 0 d 

declined 0.1% @ 7 d

ph-COOH: max= 0.2% @ 0.3 d 

declined to ND @ 7 d

Unknowns: max= 3.2% @ 0d declined 

to 2.5% @ 7 d

Others:

Bound Residues: max= 73.6% @ 3 d 

declined to 73.2% @ 7 d

Organic volatiles: Not detected

Major degradates:

ph-CH3: max= 13.2% @ 0 d declined 

0.5% @ 7 d 

CO2: max= 22.8% @ 7 d

Minor degradates (ND= No Detection):

DM-TMO: max= 5.7% @ 0 d 

declined 0.5% @ 7 d 

ph-COOH: max= 0.3% @ 0 d 

declined to ND @ 7 d

Unknowns: max= 2.6% @ 0 d 

declined to 1.4 @ 7 d

Others:

Bound Residues: max= 78.6% @ 3 d 

declined to 68.6% @ 7 d

Organic volatiles: Not detected

Major degradates:

ph-CH3: max= 11.8% @ 0 d declined 

1.4% @ 7 d 

CO2: max= 19.9% @ 7 d

Minor degradates (ND= No Detection):

DM-TMO: max= 8.3% @ 0.3 d 

declined ND @ 7 d

ph-COOH: max= 1.0% @ 0.3 d declined 

to ND @ 7 d

Unknowns: max= 3.6% @ 0d declined 

to 2.0% @ 7 d

Others:

Bound Residues: max= 81.0% @ 0.7 d 

declined to 76.4% @ 7 d

Organic volatiles: Not detected

(e) MRID 483419-24 “Acceptable”

Experimental duration: 90 days @ 20 oC (Application rate 2 ppm= equivalent to 4.1 lbs a.i/A to a depth of 6”)

Parent Alone: t1⁄2= 17 days in Soil 7; t1⁄2= 16 days in Soil 8; t1⁄2= 16 days in Soil 9; and t1⁄2= 17 days in Soil 10

TTR: t1⁄2= 139 days in Soil 7; t1⁄2= 128 days in Soil 8; t1⁄2= 114 days in Soil 9; and t1⁄2= 98 days in Soil 10
179

Major degradates:

CO2: Soil 7: max= 36.9% @ 90 d; Soil 8: max= 40.9% @ 90 d; Soil 9: max= 39.6% @ 90 d; Soil 10: max= 42.6% @ 90 d

DM-TM: Soil 8: max= 13.3% @ 3 d declined non-detection @ 30 d

Minor degradates:

DM-TM: Soil 7: max= 1.1% @ 1 d declined to non-detection @ 15 d; Soil 9: max= 3.6% @ 7 d declined non-detection @ 30 d;

 Soil 10: max= 0.6% @ 15 d declined non-detection @ 30 d

ph-CH3: Soil 7: max= 1.3% @ 3 d declined to % 0.1% @ 90 d; Soil 8: max= 8.0% @ 3 d declined to % 0.5% @ 90 d;

 Soil 9: max= 2.9% @ 7 d declined to % 0.1% @ 90 d; Soil 10: max= 4.1% @ 7 d declined to % 1.4% @ 90 d

Others:

Bound Residues:

Soil 7: max= 63.6% @ 30 d declined to % 56.1 @ 90 d; Soil 8: max= 60.2% @ 15 d declined to 49.0% @ 90 d;

Soil 9: max= 55.9% @ 15 d declined to % 52.6% @ 90 d; Soil 10: max= 48.9% @ 30 d declined to 45.4% @ 90 d

Organic volatiles: In all soils: A total of 0.2 to 0.4% @ varied times from 3 to 90 d

Unknowns and Un-resolved: In all soils: max= 1.9% @ 3 d
180

(2) Aerobic and anaerobic soil

MRID 428183-01 “Acceptable”

This study was conducted for 92 days @ 25 oC (32 days in aerobic conditions followed by 60 days in anaerobic conditions. 

Application rate 16 ppm= equivalent to 32 lbs a.i/A to a depth of 6”).

Property/Description or Value

Aerobic phase (Incubated for 32 days)

t1⁄2= 53 days (Soil 3); Bound Residues are low

Anaerobic phase (Incubated for 60 days following the aerobic 

phase)

t1⁄2= 87 days (Soil 3); Bound Residues are low

Major degradates:

DM-TM: max= 12.6% @ 32 d

Minor degradates:

ph-CH3: max= 4.1% @ 21 d declined to 2% at 32 d

CO2: max= 4.1% @ 32 d

Many degradates: <0.8% including: DM-TMOCOOH; TMO; DM-TMO; 

TM-COOH, SM-TM; ph-COOH; ph-CH2OH

Others:

Volatiles: A total of 2.5% @ 32 d (mostly Parent)

Bound residues: 2.5% @ 32 d

Major degradates:

DM-TM: max= 31.2% @ 60 d

Minor degradates:

ph-CH3: max= 8.0% @ 42 d declining to % 2.9% @ 60 d

CO2: max= 3.3% @ 60 d; ph-Cresol: max= 5.1% @ 60 d

Many degradates: <0.8% including: DM-TMO-COOH; TMO; 

DM-TMO; TM-COOH, SM-TM; ph-COOH; ph-CH2OH; DCph-CH3+ 4 other unidentified degradates

Others:

Volatiles: A total of 5.1% @ 60 d (2.7% Parent)

Bound residues: 4.1% @ 60 d

(3) Anaerobic soil 

Property/Description or Value

MRID 001561-06 “Supplemental”

Parent Alone: t1⁄2= 36 days in Soil 1

TTR: t1⁄2= 107 days 

Parent Alone: t1⁄2= 57 days in Soil 2

TTR: t1⁄2= 161 days 
181

Major degradates:

None

Minor degradates:

CO2: max= 0.3% @ 60 d

DM-TM: max= 7.7% @ 60 d 

DM-TMO: max= 2.5% @ 60 d 

ph-CH3: max= 3.7% @ 60 d

TMO: max= 1.9% @ 60 d

TM-CH2OH; TM-COOH; TMO-CH2OH; ph-CH2OH; 

ph-COOH: max= 0.2-0.6% each @ 60 d

TMO-COOH: <1% throughout

Unidentified: max= 4.6% @ 60 d

Others:

Organic volatiles: 0.6% @ 60 d

Bound residues: max 39.0% @ 60 d

Major degradates:

None

Minor degradates:

CO2: max= 0.9% @ 60 d

DM-TM: max= 6.7% @ 30 d declined to 4.8% @ 60 d 

DM-TMO: max= 1.0-1.1% @ 30-60 d 

ph-CH3: max= 2.6-2.7% @ 14-60 d

TMO: max= 1.9% @ 60 d

TM-CH2OH; TM-COOH; TMO-CH2OH; ph-CH2OH; phCOOH: max= 0.2-0.7% each, mostly @ 60 d

TMO-COOH: max= 0.2% @ 60 d

Unidentified: max= 2.6% @ 60 d

Others:

Organic volatiles: 1.1% @ 60 d

Bound residues: max 31.0% @ 30-60 d
182

(4) Aerobic aquatic (Two; water: sediment systems)

MRID 483419-26 “Acceptable”

Systems: TM applied at a rate of 0.67 ppm to pond/lake water: sediment systems and incubated for 100 days @ 20 oC. 

Property/Description or Value

(a) Total System 1 

t1⁄2= 19 days (parent alone); t1⁄2= 49 days (TTR)

Major degradates:

DM-TM: max= 23.5% @ 30 d declined to no detect @100 d

CO2: max= 52.5% @ 100 d

Minor degradates :

ph-CH3: max= 6.5% @ 30 d declined to 1.1% @100 d

DM-TMO: max= 2.9% @ 62 d declined to no detect @100 d

TM-COOH: max= 0.2% @ 3-7 d declined to no detect @100 d

Unknowns: max= 2.2% @ 100 d

Others :

Volatiles: A total of 12.7 to 11.6 @ 62-100 d (Parent >95%)

Bound residues: 25.9% @ 62 d declined to 20.4% @100 d

(a) Total System 2 

t1⁄2= 26 days; t1⁄2= 65 days (TTR)

Major degradates :

DM-TM: max= 13.4% @ 30 d declined to 4.9% at 100 d

CO2: max= 35.6% @ 100 d

Minor degradates :

ph-CH3: max= 2.6% @30 d declined to 0.9% at 100 d

DM-TMO: max= 5.4% @30 d declined to 0.7% at 100 d

TM-COOH: max= 0.9% @7 d declined to no detect @100 d

Unknowns: max= 1.2% @30 d declined to 0.5% at 100 d

Others :

Volatiles: A total of 21.8% @ 100 d (Parent >95%)

Bound residues: 35.0% @76 d declined to 19.9% @100 d
183

(b) Water (Systems 1 & 2)

(Systems 1)

Major degradates :

DM-TM: max= 10.7 @30 d declined to no detect @100 d

Minor degradates :

ph-CH3: max= 0.5% @30 d declined to no detect @100 d

DM-TMO: max= 2.9% @62 d declined to no detect @100 d

TM-COOH: max= Not detected

Unknowns: max= 0.6-0.7% @1 and 100 d, No clear pattern

(Systems 2)

Major degradates :

None

Minor degradates :

DM-TM: max= 9.2% @62 d declined to 3.0% @100 d

ph-CH3: max= 1.0% @30 d declined to no detect @100 d

DM-TMO: max= 5.4% @30 d declined to 0.7% @100 d

TM-COOH: max= 0.9% @ 7 d declined to no detect @100 d

Unknowns: max= 1.2% @ application declined to no detect 

@100 d

(c) Sediment (Systems 1 & 2)

(Systems 1)

Major degradates :

DM-TM: max= 12.7% @30 d declined no detect @100 d

Minor degradates :

ph-CH3: max= 6.0% @30 d declined to 1.1 at 100 d

DM-TMO: max= Not detected

TM-COOH: max= 0.2% @7 d declined to no detect @100 d

Unknowns: max= 1.6% @100 d

(Systems 2)

Major degradates :

None

Minor degradates :

DM-TM: max= 4.5% @30 d declined to 1.9% @100 d

ph-CH3: max= 1.6% @30 d declined to 0.9% at 100 d

DM-TMO: max= Not detected

TM-COOH: max= Not detected

Unknowns: max= 0.9% @1 d declined to 0.2% @ 100 d
184

(5) Anaerobic aquatic Half-lives (one soil: water system)

MRID 431281-01 “Acceptable”

Important Note: Recovery of radiocarbon was more than 96% of the applied dose from Day 0 to Day 30, but decreased to 55% at 

Day 364 due to production of 14C-methane which could not be trapped by NaOH and ethylene glycol solutions. Production of 

14CH4from 14Cph-CH3 (2,6-Dichloro-4-methylphenol) under the same anaerobic aquatic soil conditions was confirmed in a 

separate study

Property/Description or Value

(a) Total System 3

t1⁄2= 47 days (parent alone); t1⁄2= 95 days (TTR)

Major degradates :

DM-TM: max= 58.0% @ 92 d declined to 2.4% @ 364 d

DC-ph-CH3: max= 10.2% @ 30 d declined to 1.8% @ 364 d

CO2: max= 23.5% @ 364 d

Minor degradates :

ph-CH3: max= 8.1% @ 364 d

p-Cresol: max= 4.7% @ 14 d declined to <0.1% @ 364 d

Other degradates: 5.7% @ 364 d

Others :

Volatiles: A total of 1.5% @ 282-364 days

CH4: max= 57.0% @ 364 d

Bound residues: 8.7% @ 364 days

(b) Water (system 3)

Major degradates :

DM-TM: max= 54.1% @ 92 d declined to 1.2% @ 364 d

Minor degradates :

DC-ph-CH3: max= 8.2% @ 30 d declined to 1.3% @ 364 d

ph-CH3: max= 6.8% @ 364 d

p-Cresol: max= 3.9% @ 14 d declined to <0.1% @ 364 d

Other degradates: 4.4-4.0% @ 282-364 d

(c) Soil (system 3)

Major degradates :

None

Minor degradates :

DM-TM: max= 4.6% @ 62 d declined to 1.2% @ 364 d

DC-ph-CH3: max= 2.0% @ 30 d declined to 0.5% @ 364 d

ph-CH3: max= 1.2% @ 364 d

p-Cresol: max= 0.8% @ 14 d declined to <0.1% @ 364 d

Other degradates: 1.9% @ 364 d
185

APPENDIX H. RESULTS FROM STIR AND SIP SCREENING TOOLS
186

Screening Tool for Inhalation Risk (STIR)

Input

Application and Chemical Information

Enter Chemical Name Tolclofos methyl

Enter Chemical Use seed treatment

Is the Application a Spray? (enter y or n) n

If Spray What Type (enter ground or air) ground

Enter Chemical Molecular Weight (g/mole) 301.12

Enter Chemical Vapor Pressure (mmHg) 1.38E-05

Enter Application Rate (lb a.i./acre) 0.02

Toxicity Properties

Bird

Enter Lowest Bird Oral LD50 (mg/kg bw) 2000 (>2000 mg kg/bw for finch)

Enter Mineau Scaling Factor

Enter Tested Bird Weight (kg) 0.012

Mammal

Enter Lowest Rat Oral LD50 (mg/kg bw) 5000 (> 5000 mg/kg bw for rat)

Enter Lowest Rat Inhalation LC50 (mg/L) 1.9

Duration of Rat Inhalation Study (hrs) 4

Enter Rat Weight (kg) 0.225

Output

Results Avian (0.020 kg )

Maximum Vapor Concentration in Air at Saturation 

(mg/m3) 2.24E-01

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 2.81E-02

Adjusted Inhalation LD50 5.49E+00

Ratio of Vapor Dose to Adjusted Inhalation LD50 5.12E-03 Exposure not Likely Significant

Maximum Post-treatment Spray Inhalation Dose 

(mg/kg) not applicable

Ratio of Droplet Inhalation Dose to Adjusted Inhalation 

LD50 not applicable not applicable

Results Mammalian (0.015 kg )

Maximum Vapor Concentration in Air at Saturation 

(mg/m3) 2.24E-01

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 3.53E-02

Adjusted Inhalation LD50 1.58E+02

Ratio of Vapor Dose to Adjusted Inhalation LD50 2.24E-04 Exposure not Likely Significant

Maximum Post-treatment Spray Inhalation Dose 

(mg/kg) not applicable

Ratio of Droplet Inhalation Dose to Adjusted Inhalation 

LD50 not applicable not applicable
187

Results of STIR Modeling for TM

Table 1. Inputs

Parameter Value

Chemical name Tolclofos methyl

Solubility (in water at 25oC; mg/L) 0.7

Mammalian LD50 (mg/kg-bw) 3500 (mouse)

Mammalian test species other

Body weight (g) of "other" mammalian species 20

Mammalian NOAEL (mg/kg-bw) 12.2 (mouse)

Mammalian test species other

Body weight (g) of "other" mammalian species 20

Avian LD50 (mg/kg-bw) 2000 (finch)

Avian test species other

Body weight (g) of "other" avian species 12

Mineau scaling factor 1.15

Mallard NOAEC (mg/kg-diet) 500

Bobwhite quail NOAEC (mg/kg-diet) 500

NOAEC (mg/kg-diet) for other bird species

Body weight (g) of other avian species

NOAEC (mg/kg-diet) for 2nd other bird species

Body weight (g) of 2nd other avian species

Table 2. Mammalian Results

Parameter Acute Chronic

Upper bound exposure (mg/kg-bw) 0.1204 0.1204

Adjusted toxicity value (mg/kg-bw) 1316.2111 4.5879

Ratio of exposure to toxicity 0.0001 0.0262

Conclusion*

Drinking water exposure 

alone is NOT a potential 

concern for mammals

Drinking water exposure 

alone is NOT a potential 

concern for mammals

Table 3. Avian Results

Parameter Acute Chronic

Upper bound exposure (mg/kg-bw) 0.5670 0.5670

Adjusted toxicity value (mg/kg-bw) 2159.2718 24.8063

Ratio of exposure to acute toxicity 0.0003 0.0229

Conclusion*

Drinking water exposure 

alone is NOT a potential

concern for birds

Drinking water exposure 

alone is NOT a potential 

concern for birds

*Conclusion is for drinking water exposure alone. This does not combine all routes of exposure. Therefore, when 

aggregated with other routes (i.e., diet, inhalation, dermal), pesticide exposure through drinking water may contribute to 

a total exposure that has potential for effects to non-target animals.
188