# Problem Formulation for the Environmental Fate, Ecological Risk, Endangered Species, and Drinking Water Exposure Assessments in Support of the Registration Review of Thiodicarb

(3 EZ ,12 EZ )-3,7,9,13-tetramethyl-5,11-dioxa-2,8,14-trithia-4,7,9,12- tetraazapentadeca-3,12- diene-6,10-dione CAS Registry Number: 59669-26-0
PC Code: 114501

Prepared by: Melissa Panger, Ph.D., Biologist Greg Orrick, Environmental Scientist Reviewed by: Anita Pease, Senior Biologist R. David Jones, Ph.D., Senior Agronomist Elizabeth Behl, Branch Chief U. S. Environmental Protection Agency Office of Pesticide Programs Environmental Fate and Effects Division
Environmental Risk Branch IV 1200 Pennsylvania Ave., NW
Mail Code 7507P Washington, DC 20460



### August 31, 2009

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### Table of Contents

1. Purpose....................................................................................................................................... 4
2. Problem Fo rmulation ........................................................................................................ ......... 4 2.1. Nature of Regulatory Action.............................................................................................. . 4
2.2. Previous Assessments ..................................................................................................... .... 4 2.2.1. Ecological Risk Assessments....................................................................................... 4 2.2.2. Drinking Water Exposure Assessments....................................................................... 6
3. Stressor Source and Distribution ........................................................................................... .... 7
3.1. Mechanism of Action...................................................................................................... .... 7 3.2. Overview of Pesticide Use and Usage................................................................................ 7 3.3. Environmental Fate and Transport.................................................................................... 11 3.3.1. Mobility............................................................................................................... ....... 12 3.3.2. Degradation............................................................................................................ .... 13 3.3.3. Field Dissipation ...................................................................................................... .. 14
3.3.4. Bioaccumulation ........................................................................................................ 14
3.3.5. Environmental Fate and Transport of Methomyl....................................................... 15

3.4. Water Quality............................................................................................................ ........ 19 4. Receptors.................................................................................................................................. 19 4.1. Effects to Aquatic Organisms ........................................................................................... 20 4.2. Effects to Terrestrial Organisms ....................................................................................... 24
4.3. Incident Databases Review............................................................................................... 2 8 4.4. Ecosystems Potentially at Risk ......................................................................................... 31 5. Assessment Endpoints ............................................................................................................. 31 6. Conceptual Model.................................................................................................................... 31 6.1. Risk Hypothesis ................................................................................................................ 32 6.2. Conceptual Diagram ......................................................................................................... 32 7. Analysis Plan .............................................................................................................. ............. 34
7.1. Stressors of Concern ......................................................................................................... 35 7.2. Measures of Exposure....................................................................................................... 35
7.3. Measures of Effect ............................................................................................................ 36 7.4. Integration of Exposure and Effects ................................................................................. 37
7.5. Deterministic and Probabilistic Assessment Methods...................................................... 38 7.6. Endangered Species Assessments..................................................................................... 38 7.7. Drinking Water Assessment ............................................................................................. 38 7.8. Preliminary Identification of Data Gaps........................................................................... 39

7.8.1. Fate............................................................................................................................. 39
7.8.2. Effects Data for Thiodicarb ....................................................................................... 41 7.8.3. Effects Data for Methomyl ........................................................................................ 44
8. References................................................................................................................................ 48 APPENDIX A. Toxicity Data for Thiodicarb and Methomyl:.................................................... 58 APPENDIX B. Major Organic Environmental Degradates of Thiodicarb.................................. 73
APPENDIX C: Data Call-In Tables. ........................................................................................... 75

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### 1. Purpose

The purpose of this problem formulation is to pr ovide an understanding of what is known about the environmental fate and ecological effects of thiodicarb, considering its currently registered
uses. Thiodicarb is a restricted use carbamate in secticide registered for use on cole crops, cotton, a variety of leafy vegetables, soybeans, sweet corn, ornamentals (including trees), and non-crop areas (which include wastelands, roadsides, rights-of-way, grassways, shelter belts, and fencerows). This document will provide a plan fo r analyzing data relevant to thiodicarb and for conducting environmental fate, ecological risk, endangered species, and drinking water exposure assessments for its registered uses. Additionally, this problem formulation is intended to identify data gaps, uncertainties, and poten tial assumptions used to address those uncertainties relative to characterizing the ecological risk associated wi th the registered uses of thiodicarb.

2. Problem Formulation

2.1. Nature of Regulatory Action

Under the Federal Insecticide, F ungicide, and Rodenticide Act (FIF RA), all pesticid es distributed
or sold in the United States generally must be registered by the Environmental Protection Agency (EPA). In determining whether a pestic ide can be registered in the U.S., the Agency evaluates its safety to non-target species base d on a wide range of environmental and health effects studies. In 1996, FIFRA was amended by the Food Quality Protection Act, and the Agency was mandated to implement a new program for the periodic review of pesticides, i.e

., registration review ( http://www.epa.gov/oppsrrd1/registration_review/ ). The Registration Review program is intended to ensure that, as th e ability to assess risk evolves and as policies and practices change, all register ed pesticides continue to meet the statutory standard of no
unreasonable adverse effects to human health and the environment. Changes in science, public policy, and pesticide use practices will occur ov er time. Through the new Registration Review program, the Agency periodically reevaluates pestic ides to make sure that as change occurs, products in the marketplace can be used safely.

As part of the implementation of the new Regist ration Review program purs uant to Section 3(g) of the Federal Insecticide, Fungi cide and Rodenticide Act (FIFRA), the Agency is beginning its
evaluation of thiodicarb to de termine whether it continues to meet the FIFRA standard for registration. This problem formulation for the environmental fate, ecological risk, endangered species, and drinking water assessment chapter in support of the registration review will be posted in the initial docket which will open the public phase of the review process.

2.2. Previous Assessments

2.2.1. Ecological Risk Assessments

Thiodicarb was first registered in the United States in 1984 for use as an insecticide. Dozens of hazard and exposure assessments were conduc ted in the 1970s and 1980s in support of experimental use permits and proposed new uses ; however, risk was not quantified in these
assessments. FIFRA Section 3 new use assess ments were conducted in 1990 (record no.

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### 2588559) and 1994 (DP barcode 206596) for a proposed use on apples, the former of which was not completed due to lack of data at the time of the assessment. The latter assessment identified acute risk to mammals, aquatic invertebrates, a nd federally listed birds an d estuarine/marine fish,
as well as chronic risk to freshw ater invertebrates. Data were insufficient to assess chronic risk
to birds and fish and to assess risk to terrestr ial and vascular aquatic plants. No risk was identified for non-vascular aquatic plants. Chro nic risk to mammals and risk to terrestrial invertebrates were not quantified.

A national-level ecological risk assessment was co mpleted to support the re registration eligibility decision (RED) for thiodicarb in 1998 (USEPA 1998). Risk wa s evaluated using exposure estimates and ecological toxicity endpoints for th iodicarb as well as for the active ingredient degradate methomyl (PC code 090301). The RED indicated that the major concerns posed by
the use of thiodicarb are chronic risk to non-target avian, mammalian, and freshwater invertebrate organisms. More specifically, fo llowing the use of thiodicarb, the RED identified
chronic risk to terrestrial anim als and aquatic invertebrates from exposure to thiodicarb or to methomyl, chronic risk to fish from exposure to methomyl, acute risk to aquatic invertebrates from exposure to thiodicarb or to methomyl, and acute risk to terrestria l animals and fish from exposure to methomyl. Hazard ra ther than risk to terrestria l invertebrates was evaluated. Ecological risk mitigations identified in the thiodicarb RED included:

• Limiting the number of 1.0 lb a.i./A single appl ications per season to four for cole crops and to six for cotton;

• Establishing buffer zones for aerial, gr ound, and ultra low volume applications; and

• Adding label advisories promoting:

o Integrated Pest Management,

o Addressing the hazards to bees and other nontarget organisms,

o Addressing the potential for ground water contamination, and

o Requiring that the potential for surface water contamin ation via spray drift be
minimized.

More recently, FIFRA Section 3 new use asse ssments were conducted in 2006 and 2007 for proposed cotton seed treatments (DP barcode 32 5684) and soybean seed treatments (DP barcode 342879), respectively.

• The assessment of the proposed cotton seed tr eatment identified acute and chronic risk to aquatic invertebrates from exposure to methomyl and to birds and mammals from exposure to thiodicarb and/or methomyl.

• The assessment of the proposed soybean seed tr eatment identified acute and chronic risk to birds from methomyl, acute and chronic risk to mammals from thiodicarb and/or methomyl, acute risk to freshwater fish from methomyl, acute risk to aquatic
invertebrates from thiodicarb and/or meth omyl, and chronic risk to freshwater invertebrates from methomyl. No acute risk was identified to estuarine/marine fish; no
chronic risk was identified to freshwater or estuarine/marine fish; and no risk was identified for non-vascular aquatic plants. Ch ronic risk to estuarine/marine invertebrates and risk to vascular aquatic pl ants and terrestrial plants was not quantified due to lack of

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### data. Combined foliar and seed treatments to soybeans resulted in additional risk to all
assessed taxa than for seed treatment alone.

2.2.2. Drinking Water Exposure Assessments

The most recent drinking water exposure assess ments conducted specifically for thiodicarb were
Tier I and Tier II assessments conducted in May, 1997 in support of the 1998 RED (USEPA

1997 a and 1997 b ; DP barcodes not reported). The Tier II assessment reported the estimated drinking water concentrations (EDWC) of thiodi carb and methomyl in surface water listed in
Table 2.1 for the maximum use pattern of thiodicar b. No monitoring data were available for thiodicarb in ground or surface water; however, methomyl was detected in ground water at concentrations up to 20 μg/L (t he highest value was detected in drinking water in Suffolk County, New York) and in surface water at concentrations up to 1.9 μg/L (the highest value was detected in South Florida).

Table 2.1. Tier II EDWCs of thiodicarb and methomyl in surface water from maximum use patterns of thiodicarb in 1997 (USEPA 1997 b ).

Use (modeled rate) Active Ingredient Maximum (μg/L) 90-day mean (μg/L) 1-in-10-year annual mean (μg/L)

Thiodicarb 21 9 2.3 Cotton (6 applications @ 0.9 lbs a.i./A) Methomyl 151 120 26



### A drinking water assessment was recently cond ucted for thiodicarb and methomyl in which thiodicarb was assumed to rapidly degrade to methomyl. While exposure was estimated for applications of thiodicarb and/or methomyl, es timated concentrations represented methomyl only (USEPA 2007 a ; DP 339492). Monitoring data were not assessed. Resulting EDWCs for the maximum use pattern are listed in Table 2.2

.

Table 2.2. Tier II EDWCs of methomyl in su rface water from maximum use patterns of thiodicarb in 2007 (USEPA 2007 a ).

Use (modeled rate) Active Ingredient(s) Applied 1-in-10-year peak (μg/L) 1-in-10-year annual mean (μg/L) 30-year mean (μg/L)

Thiodicarb 86 2.0 1.4 Corn (10 applications @ 0.75 lbs a.i./A) Thiodicarb & methomyl A 69 2.1 1.5 A These EDWCs represent exposure to methomyl following separate applications of thiodicarb and methomyl on the same crop.



### A cumulative human health risk assessment (CRA) for the N -methyl carbamate (NMC) class of pesticides was completed in 2007 (USEPA 2007 b ). The NMC CRA concluded that there is a reasonable certainty that no harm to human hea lth will result from cumulative exposure to the NMC pesticides, including thiodicarb and methomyl , presuming the risk mitigations proposed in the individual chemical REDs are implemented.

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### 3. Stressor Source and Distribution

Thiodicarb is registered for use on a variety of agricultural, orname ntal, and non-agricultural areas. The parent compound degrades mainly to methomyl, which is also a pesticide active ingredient (PC Code 090301). Me thomyl is registered for use on a wide variety of sites including field, vegetable, and orchard crops ; turf (sod farms only); livestock quarters; commercial premises; and refuse containers. As in previous ecological assessments conducted by the Agency for thiodicarb, methomyl will be considered in the ecological risk assessment conducted as part of the Registra tion Review process only as the main degradate of thiodicarb rather than as a primary active ingredient or as a degradate of other pe sticide products. Modeled exposure estimates resulting from thiodicarb usage will reflect the predicted environmental fate of either thiodicarb and methomyl separately or together as methomyl e quivalents, depending on the toxicity differential of the compounds for asse ssed organisms. Potential simultaneous use of methomyl within the same areas as thiodicarb will be addressed in the ecological and endangered species risk assessments for the methomyl registra tion review rather than in the assessments for
the thiodicarb re gistration review.

The residues of concern for exposure and risk asse ssment will be reconsidered prior to analysis. In the absence of data or structural activity rela tionships indicating low t oxicity concerns for the major degradates of thiodicarb and methomyl, th ey will be assumed of equal toxicity as the
parent.

3.1. Mechanism of Action

Both thiodicarb and its degradate methomyl are N -methyl carbamate insecticides. Carbamate insecticides act by inhibiting acetylcholines terase and reducing the degradation of the neurotransmitter acetylcholine. As a result , intersynaptic concentrations of acetylcholine
increase as the neurotransmitter accumulates l eading to increased firing of the postsynaptic neurons. This may ultimately lead to convulsions, paralysis, and death of an organism exposed
to the chemical.

3.2. Overview of Pesticide Use and Usage

Thiodicarb was first registered in the U.S. in 1984. Thiodicarb is currently registered for use on broccoli, cabbage, cauliflower, cotton, a variety of leafy vegetables, soybeans, sweet corn, ornamentals and trees (except forest), and non-crop areas ( i.e ., wastelands, roadsides, rights-ofway, grassways, shelter belts, and fencerows). There are currently six thiodicarb products registered in the U.S.; one product is a techni cal grade for use in the manufacture of end-use products and five are end-use products (see Table 3.1 ). One of the products [AerisTM SeedApplied Insecticide/ Nematicide (264-1057)] cont ains two active ingred ients (thiodicarb and imidacloprid). All of the remaining thiodica rb products contain only one active ingredient (thiodicarb). All of the products are Re stricted Use Pesticides (RUP).

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### TABLE 3.1. Summary of Thiodicarb Products Registered in the U.S.

Product Name (EPA Reg. No.) Registrant Percent Active Ingredient Use

Larvin® Technical (264-343) Bayer CropScience Thiodicarb: 95% Formulation of insecticides

AerisTM Seed-Applied
Insecticide/Nematicide (264-1057) Bayer CropScience Thiodicarb: 24% Imidacloprid: 24%

EXP3 Seed Applied
Nematicide/Insecticide (264-1048) Bayer CropScience Thiodicarb: 34% Cotton Soybean

Larvin® 3.2 Thiodicarb

Insecticide/Ovicide (264-379) Bayer CropScience Thiodicarb: 34%

Larvin® DF Thiodicarb

Insecticide/Ovicide (264-378) Bayer CropScience Thiodicarb: 80%

Larvin® DF WSP Thiodicarb
Insecticide/Ovicide (264-530) Bayer CropScience Thiodicarb: 80% Broccoli Cabbage
Cauliflower

Cotton Leafy Vegetables Soybeans

Sweet Corn
Ornamentals

Trees Non-crop Areas



### Thiodicarb products include aque ous flowable, dry flowable c oncentrate (water dispersible granules), and flowable formulations. Accordin g to the labels, thiodicarb can be applied via ground [including irrigation systems (center pivot and solid set only)] and aerial equipment and as a seed treatment (cotton and soybean onl y). Thiodicarb can be used nationally ( i.e ., there are no geographic restrictions on where it can be used). The maximum single application rate allowed per use ranges from 0.09 lb a.i./acre (cotton seed treatment) to 1 lb a.i./acre (broccoli, cabbage, and cauliflowe r, foliar use) (see Table 3.2 ). The maximum application rate allowed per season ranges from 1.5 lb a.i./acre/season (leafy vegetables, foliar use) to 7.5 lb a.i./acre/season (sweet corn, foliar use). The maximum number of applications allowed per season, depending on the use, ranges from four (broccoli, cabbage , and cauliflower) to six (cotton, ornamentals and trees, and non-crop areas). The maximum number of applications allowed for leafy vegetables, sweet corn, and soybeans is not specified on the labels. The minimum application interval ranges from 1-day (sweet corn) to 14-day ( non-crop areas) depending on the use. The minimum application interval is not specified on the labels for broccoli, cabbage, cauliflower, leafy vegetables, or ornamentals and trees. Conserva tive assumptions will be made in the absence of
labeled directions.

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### TABLE 3.2. Summary of Thiodicarb Application Methods and Rates.

PRODUCT FORMULATION APPLICATION
METHOD USE MAX
SINGLE
APPL RATE (lb a.i./acre) MAX

NUMBER
OF APPL/
SEASON MAX APPL
RATE/
SEASON (lb a.i./acre) 1 MIN APPL
INTERVAL

Foliar Applications

Broccoli Cabbage

Cauliflower 1.0 4 4.0 Not stated

Cotton 0.90 6 5.4 (except in
CA and AZ = 1.8) 7-day (at 0.9 lb a.i./A rate)

Leafy Vegetables 2 0.75 NS 1.5 Not stated

Soybeans 0.75 NS 3.0 7-day (at 0.75 lb a.i./A rate)

Sweet Corn 0.75 NS 7.5 1-day

Ornamentals
and Trees 3 0.75 6 4.5 Not stated Larvin® 3.2 Aqueous flowable - Ground
- Aerial - Sprinkler irrigation system (center pivot and solid set only)

Non-crop
Areas 4 0.75 6 4.5 14-day

Larvin® DF Dry flowable concentrate (water dispersible granule) - Ground
- Aerial - No irrigation
systems

Larvin® DF

WSP Dry flowable concentrate (water dispersible granule) - Ground
- Aerial - No irrigation
systems Same as above

Seed Treatments

Cotton (delinted seed only) 0.09 5 1 (as a seed treatment) 5.4 (except in
CA and AZ = 1.8) Not applicable AerisTM Flowable Soil incorporated (>1 inch) Soybeans 0.125 6 1 (as a seed treatment) 3.0 Not applicable

Cotton (delinted seed only) 0.135 7 1 (as a seed treatment) 5.4 (except in
CA and AZ = 1.8) Not applicable EXP3 Flowable Soil incorporated (>1 inch) Soybeans 0.125 8 1 (as a seed treatment) 3.0 Not applicable

1 Maximum application rates are for seed treatments and foliar application combined.

2 Leafy vegetables include: Amaranth (Chinese spinach), arugula, cardoon, celer y, Chinese celery, celtuce, chervil, chrysanthemum, corn salad, cress, dandelion, dock (sorre l), endive (escarole), Florence fennel, lettuce (head, leaf), orach, parsley, purslane, radicchio, rhubarb, spinach, and Swiss chard.

3 Includes trees (except forest), sh rubs, herbaceous bedding plants, and no n-bearing fruit trees in commercial greenhouses, nurseries, and landscapes. Non-bearing fruit trees include citrus, nut crops, pome fruits, and stone
fruits.

4 Includes wastelands, roadsides, rights-of- way, grassways, shelter belts, and fencerows.

5 1 gallon of product = 2.5 lbs a.i.; the maximum application rate on the proposed label = 25.6 fl oz of product/hundredweight of seed; 18 lb seed/acre (from USEPA, 2006); 25.6 fl oz = 0.20 gallon; 0.20 x 2.5 lb = 0.50 lb a.i./hundredweight of seed; (18 lbs seed/acre)(0.50 lbs a.i./100 lbs seed) = 0.09 lbs a.i./acre.



### -9 of 83-6 1 gallon of product = 2.5 lb a.i.; the maximum application rate on the proposed label = 6.4 fl oz of product/hundredweight of seed; 100 lb seed/acre (from http://www.nsrl.uiuc.edu/ aboutsoy/production02.html ); 6.4 fl oz = 0.05 gallon; 0.05 x 2.5 lb = 0.125 lb a.i./acre.

7 1 gallon of product = 3.2 lbs a.i.; the maximum application rate on the proposed label = 30 fl oz of product/hundredweight of seed; 18 lb seed/acre (from USEPA, 2006); 30 fl oz = 0.234 gallon; 0.235 x 3.2 lb = 0.75 lb a.i./hundredweight of seed; (18 lbs seed/acre)(0.75 lbs a.i./100 lbs seed) = 0.135 lbs a.i./acre.

8 1 gallon of product = 3.2 lb a.i.; the maximum application rate on the proposed label = 5 fl oz of product/hundredweight of seed; 100 lb seed/acre (from http://www.nsrl.uiuc.edu/ aboutsoy/production02.html ); 5 fl oz = 0.039 gallon; 0.039 x 3.2 lb = 0.125 lb a.i./acre



### The three foliar-applied thiodicarb products ( i.e ., Larvin® 3.2 Thiodicarb Insecticide/Ovicide,
Larvin® DF Thiodicarb Insecticide/Ov icide, and Larvin® DF WSP Thiodicarb Insecticide/Ovicide) contai n the following label restri ctions and recommendations:

- Do not apply by ground within 25 ft or by air within 100 ft of lakes, reservoirs, rivers,

estuaries, commercial fish ponds, natural- permanent streams, marshes and naturalpermanent ponds - Increase buffer zone to 450 ft with ultra low volume applications (low spray volumes

only allowed on soybeans and only in MD, VA, NC, DE, SC, GA, AL, MS, LA, AR,
and MO - Spray Drift Restrictions: ≤ 10 ft application height

The two seed-treatment products ( i.e ., AerisTM Seed-Applied Insect icide/Nematicide and EXP3 Seed Applied Nematicide/Insecticide) contain the following label restrictions:

- For use only in commercial seed treatment equipment - Treated seed must be planted into the soil at a depth >1 inch

According to the United States Geological Survey’s (USGS) national pestic ide usage data (based on information from 1999 to 2004), an average of 211,945 lbs of thiodicarb per year are applied nationally to agriculture in the United States (see Figure 3.1 ). Based on these data, the majority of thiodicarb used in agricultu re is applied to soybeans (41 %), sweet corn (35%) and cotton (19%). The remaining thiodicarb uses combin ed represent <5% of th e average total pounds applied per year. Based on a Screening Level Usage Analysis conducted by the Agency, using data from 2000 to 2007, there is an estimated ~ 113,000 lb of thiodicarb used per year [most of which is used on sweet corn (60,000 lb), soybeans (30,000 lb), and cotton (10,000 lb)]. Estimates of non-agricultural usage of thiodicarb are not available.

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### FIGURE 3.1. Estimated, Annual, Nati onal, Agricultural Thiodicarb Usage. (from http://water.usgs.gov/nawqa/pnsp/usag e/maps/show_map.php?year=02&map=m8009 ) [ The pesticide use maps available from this site show the av erage annual pesticide use in tensity expressed as average weight (in pounds) of a pesticide applie d to each square mile of agricultural land in a county. The area of each map is based on state-level estimates of pesticide use rates for individual crops that were compiled by the CropLife Foundation, Crop Protection Research Institute based on information collected during 1999 through 2004 and on 2002 Census of Agriculture county crop acreage. The maps do not represent a specific year, but rather show typical use patterns over the five year period 1999 through 2004.].



### 3.3. Environmental Fate and Transport

Registrant-submitted data defini ng the physical-chemical and environmental fate characteristics of thiodicarb [(3 EZ ,12 EZ )-3,7,9,13-tetramethyl-5,11-di oxa-2,8,14-trithia-4,7,9,12- tetraazapentadeca-3,12-diene-6,10-dione] are summarized in Table 3.3 . These data indicate that
thiodicarb is semi-volatile in soil , readily soluble and, therefore, s lightly volatile in water, and moderately mobile to mobile in soil. The co mpound appears to be re adily degraded in the environment (mostly to methomyl), with the exception that it may persist in acidic water bodies. The persistence of thiodicarb in the environment is uncertain be cause acceptable aerobic soil

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### metabolism data are available for only one soil and the aerobic a quatic metabolism data requirement was waived. Thiodicarb, if not already degraded, may leach to ground water or move to surface water bodies through spray drif t and/or dissolved in runoff. The compound is not expected to bioaccumulate in aquatic or terrestrial organisms.

TABLE 3.3. General Chemical and Environm ental Fate Parameters of Thiodicarb.

Parameter Value Reference
Selected Physical-Chemical Parameters

Molecular mass 354.5 g/mol (calculated)
Vapor pressure (20°C) 4.3 x 10 -5 torr Worthing and

Hance 1991
Water solubility (25°C) 23.5 mg/L MRID 41482002
Henry’s law constant (20°C); K AW 8.53 x 10 -7 atm-m 3 /mol; 3.55 x 10 -5 (calculated)
Octanol-air partition coefficient (K OA ) 8.7 x 10 5 (calculated)
Octanol-water partition coefficient (K OW ) 30 MRID 41250004

Bioconcentration
Fish Bioconcentration Factor (35 d) 4.1X (edible) 7.1X (inedible) 5.7X (whole fish) MRID 42834002

Mobility
Organic carbon-norm alized Freundlich adsorption coefficients (K FOC ) 55 L/kg (sand) 289 L/kg (sandy loam) 321 L/kg (silt loam) 1006 L/kg (clay) MRID 41998501

Laboratory volatilization rate range 6.83-156 ppm of the applied / hr MRID 43222901

Persistence
Hydrolysis half-life (25°C) 78 d (pH 5) 32 d (pH 7) 0.48 d (pH 9) MRID 42342601

Aqueous photolysis half-life (25°C) 9.4 d MRID 41250008
Soil photolysis half-life (25°C) 44 d MRID 43463401
Aerobic soil metabolism half-life (25°C) 3.6 d (sandy loam; pH 5.4) MRID 42142601
Anaerobic aquatic metabolism half-life (25°C) 3 hr (sandy loam sediment, pH 5.9; pond water, pH 6.5) MRID 42142602

Field Dissipation

Terrestrial field di ssipation half-life; maximum leaching depth 18 d (WA sandy loam); detected below deepest sampling depth of 75-90 cm MRID 42203901



### 3.3.1. Mobility

Thiodicarb is readily soluble in water ( up to 23.5 mg/L at 25°C; MRID 41482002, FAO 2000). The compound is also moderately mobile to mob ile in soil, based on organic carbon-normalized Freundlich adsorption coefficients that range from 55 to 1006 L/kg (MRID 41998501; USEPA

2006 a ). These values are 13.8% lower than those us ed in all previous assessments because, in previous calculations, 50% rather than the standard 58% of or ganic matter was assumed organic

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### carbon. Surface water contamination may occur via spray drift and/or from the transport of
dissolved residues in runoff. Based on the mobilit y of thiodicarb and the higher mobility of its major degradate, methomyl (discussed in Section 3.3.5 ), ground water cont amination may also occur as a result of thiodicarb use. Rapid degr adation may result in methomyl accounting for the majority of any resi dues of concern.

Thiodicarb’s vapor pressure (4.3 x 10 -5 

### torr at 20oC; Worthing and Hance 1991) indica tes that the compound may be semi-volatile from soil. Howeve r, volatilization from so il is not expected to be a major route of environmental transport due to rapid degradation in soil. Thiodicarb is only slightly volatile from water due to its sol ubility in water and as indicated by its K AW 

### (calculated
to be 3.6 x 10 -5 

### ; 40 FR 26889, Jun. 25, 1975). Submitted environmental fate studies support the expectation of low volatilit y, as it was not observed.

3.3.2. Degradation

Thiodicarb degrades by both abiotic and biotic processes. The compound is readily hydrolyzed in alkaline water (half-life of 12 hours at pH 9), but persists in acidic to neutral water (half-lives of 32 days at pH 7 and 78 days at pH 5), with decreasing degradation as pH decreases (MRID 42342601). Major hydrolytic degradates include methomyl [(S-methyl ( EZ )-N- (methylcarbamoyloxy)thioacetimidate], at up to 66% of the radioactivity applied in the pH 9 study after one day, and methomyl oxime [S-methyl -N-hydroxythioacetimidate], at up to 77% of the applied radioactivity at te rmination of the pH 9 study ( 30 days after treatment).

The compound was moderately photolyzed in water (9.4-day half- life; MRID 41250008) and slowly photolyzed in soil (44-day half-life; MRID 43463401). Reported half-lives are 18-19% higher than previously reported values because they are adjusted for dark controls. Major photolysis degradates included methomyl (up to 47% of the applied in water at study termination, 23 days after treatment, and up to 16% of the applied to soil, 7 days after treatment), methomyl oxime in the soil study (up to 27% of the applied at study termination, 30 days after treatment), and acetonitrile in the aqueous study (up to 15% of the applied at study termination).

In an aerobic sandy loam soil (pH 5.4), thiodicarb was readily degraded with a half-life of 3.6 days (MRID 42142601). Because only one soil was test ed, there is high uncertainty in this value with respect to its representativeness of the di versity of soils in th e environment. Major degradates included methomyl (up to 80% of the applied, 7 days af ter treatment) and carbon dioxide (52% of the applied at study termination, 60 days after treatment).

In an anaerobic aquatic system, thiodicarb appear ed to rapidly degrade with an estimated halflife of 3.1 hours (MRID 42142602). This value is uncertain because >99% of the compound measured at application degraded in the first 4-hour interval. Methomyl and methomyl oxime were not major degradates in this study, as thio dicarb appeared to follow an alternative route of
transformation under anaerobic conditions. Two uni dentified degradates were quickly formed, Unknown 3 (up to 60% of the applied at 4 hours after treatment) and Unknown 4 (up to 29% of the applied at 2 days after treatment). The study author offered that thes e unidentified degradates were likely the monosulfone derivative of th iodicarb and a related compound; however, the
oxidation of thiodicarb to its monosulfone unde r anaerobic conditions is not expected and

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### sufficient information were not provided to suppo rt this transformation pathway. Studies with major unidentified degradates are typically not classified acceptable; however, this study was classified acceptable because reasonable attempts were made to identify the degradates. By study termination (14 days afte r treatment), the primary degradates had further degraded, yielding substantial amounts of the volatile co mpounds acetonitrile (at 73% of the applied) and carbon dioxide (at 16% of the applied).

The residues of concern for exposure and risk asse ssment will be reconsidered. In the absence of data or structural activity relati onships indicating low t oxicity concerns for the major degradates of thiodicarb and methomyl, they will be assumed of equal toxicity as the parent. Past
assessments of thiodicarb have included thiodica rb and methomyl as the only residues of concern
because the 1998 RED for thiodicarb stated that “residues of acetamide and acetonitrile resulting from the application of thiodica rb or methomyl are not [dietary food] residues of concern in animals” (USEPA 1998). Also, degradates of other carbamates for which some degradate toxicity data are available, su ch as oxamyl, are considered much less toxic than the parent compound and have not been included as residues of concern in relevant exposure and risk assessments (USEPA 2009). However, because eval uations of residues of concern for thiodicarb and methomyl have not been conducted regardin g drinking water or ecolo gical exposure, these evaluations will occur as part of registration review.

3.3.3. Field Dissipation

In a terrestrial field dissipation study conducte d in sandy loam soil in Washington, six weekly applications of thiodicarb were made at 1.12 kg a. i./ha/application (total 6.72 kg a.i./ha) in early autumn (MRID 42203901). Filter papers confirme d actual application ra tes of 81-95% of the nominal application rate. Recove ry efficiencies from fortified samples ranged from 50% to 80% of the applied for thiodicarb and 81% to 120% of the applied for methomyl. No other degradates were analyzed in the study. Thiodicarb was dete cted (at 3 ppb) at the lowest sampled soil depth (75-90 cm) immediately after the fifth applicatio n. Methomyl was detected (at 2 ppb) at the lowest soil depth immediately after the fourth application. Following the sixth application, thiodicarb dissipated with a half-life of 18 days; me thomyl dissipated with a half-life of 43 days. The dissipation half-life from this study is l onger than would be exp ected given the short biodegradation half-lives in the laboratory studies and underscores the need for additional aerobic soil and aerobic aquatic metabolism la boratory studies in or der to understand the variability in the compound’s environmental fate.

3.3.4. Bioaccumulation

Bioaccumulation in bluegill sunfish ( Lepomis macrochirus ) was studied for thiodicarb (MRID 42834002). Bluegill sunfish were continuously exposed under flow-through conditions to a mean thiodicarb concentration of 0.05 mg/L for 35 days. Consistent with the low octanol-water partition coefficient for thiodicarb (30), bioconcentration factors (BCF) were determined to be 4.1X for edible tissue, 7.1X for inedible tissue, and 5.7X for whole fish tissues, indicating that thiodicarb does not have the potential to bioaccumu late in aquatic organisms. Acetic acid was identified as a major radiolabeled compound in the fish tissues; it was 35% of the recovered

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### residues in fish tissues at day 21 and 22% at da y 35. After 28 days of depuration, 46-74% of the
accumulated residues were eliminated from the fish tissues.

An octanol-air partition coefficient (K OA 

### ) of 8.7 x 10 5 

### (log K OA 

### of 5.94) was calculated for thiodicarb using its solubility in water, vapor pressure, and octanol-wat er partition coefficient (K OW 

### ). Kelly and Gobas (2003) and Armitage and Gobas (2007) concluded that chemicals with a log K OW 

### >2 and a log K OA 

### >5 have the potential to biomagnify in terrestrial habitats. Because
the K OW 

### for thiodicarb is <2 and the compound is not expected to be persistent in most environmental compartments, thiodicarb is unlikely to biomagnify in terrestrial habitats.

3.3.5. Environmental Fate and Transport of Methomyl

Methomyl (S-methyl N-(methylcarbamoyl)oxy) thioacetimadate; CAS No. 16752-77-5) is a registered pesticide that is al so the primary degradate of thiodicarb. The compound is persistent in low pH environments and mobile (K OC 

### of 31.3 L/kg) in soil-water systems. The dominant routes of dissipation of methomyl are metabolis m, leaching, and photolysis in clear waters. Environmental fate and transport proper ties of methomyl are summarized in Table 3.4 . Sitespecific factors affecting the pe rsistence of methomyl include aerobicity, organic matter, soil moisture content, exposure to sunlight, pH, climate (especiall y rainfall), and crop management factors that influence leaching and runoff. Becau se of its low affinity for adsorption, methomyl is likely to dissipate rapidly from plant and so il surfaces. Methomyl has fate characteristics— moderate persistence, high water solubility, and low sorption coeffi cient— that suggest transport to waters resources is likely. Waters that are neutral to acidic are partic ularly vulnerable due to methomyl’s persistence in these environments.

TABLE 3.4. Summary of Environmental Fate and Transport Properties of Methomyl.

Parameter Value Source Molecular weight 162.2 g/mol (calculated) Solubility in water (20°C) 54.7 g/L MRID 41402101 Vapor pressure 5.6 x 10 -6 

### torr MRID 41209701 Henry’s law constant 2.1 x 10 -11 

### atm-m 3 

### /mol (calculated)

K OW 

### 1.31 MRID 00157991 stable @ pH = 5 1300 days @ pH = 7 13 days @ pH = 9 Strathmann and Stone, 2001, 2002 Hydrolysis half-life

stable @ pH = 5 stable @ pH = 7 30 days @ pH = 9 MRID 00131249

Aqueous photolysis half-life 4.0 d MRID 00161885 Soil photolysis half-life 34 d MRID 00163745 Flanagan silt loam: 43.9 d (109.2 d) MRID 00008568 Aerobic soil metabolism half-life of parent (of TTR) Madera, CA silt loam: 11.6 d (25.0 d) MRID 43217901
Anaerobic soil metabolism
half-life 14 d MRID 43217902

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### Parameter Value Source Aerobic aquatic metabolism half-life of parent (of TTR) Auchingilsie clay loam: 4.0 d (6.3 d) Hinchingbrooke silty clay loam: 4.6 d (7.4 d) MRID 43325401

Organic carbon-normalized adsorption coefficient (K OC 

### ) 31.3 L/kg MRID 00161884
DP barcode 339908 Terrestrial field dissipation half-life (from surface) 4-54 d MRID 00008844
MRID 00009324
MRID 00009326
MRID 41623901
MRID 41623902 0.5 d (mint) Kiigemagi and Deinzer, 1979 Foliar degradation half-life

2.5 d (Bermuda grass) Sheets et al., 1982

Laboratory studies i ndicate that methomyl is moderately persistent and mobile. There is no significant degradation by hydrolysis at lower pHs (neutral to acidic), and methomyl degrades at a moderate rate (with a half–life around 13 and 30 d) at pH 9 based on two studies. Methomyl photolyzes quickly in clear water (t 1/2 

### = 4 d) but more slowly in soils. It is moderately stable to aerobic soil metabolism but degrad es more rapidly under anaerobic conditions. In laboratory studies, methomyl does not readily adsorb to soil and has the potential to be mobile. Field studies show varying dissipation ra tes of the chemical in soils. Dissipation rates were related primarily to differences in soil moisture content, which may have affected the microbial activity, and rainfall/irrigation, which could have influenced leaching.

Chemical and Metabolic Degradation. A guideline hydrolysis study (MRID 00131249) conducted for 30 days showed that methomyl is st able to hydrolysis at pH 5 and 7 and slowly degrades in pH 9 buffered solutions (t 1/2 

### ≈ 30 d). However, open litera ture data (Strathmann and Stone, 2001, 2002) indicate that the de gradation rate at pH 7 is 1300 days and is 13 days at pH 9, while no measurable degradation was observed at pH 5. The major hydrolysis degradate in the guideline study is methomyl oxime with up to 44% of the applied after 30 days. In two trials, one each at 10 and 100 mg/L, methomyl degraded by photolysis in water with a mean half-life of
4.0 d ±1.2 d at one standard deviation. There was no measureable degradation in the dark control. The major degradate was acetonitrile, which was found at 70.1% of the initial measured radioactivity at the termination of the experiment at 15 days. Methomyl degraded more slowly on soils (t 1/2 

### = 32 d). As in water, ace tonitrile was the major photolysis degradate on soil with a peak concentration of 40% of the applied after 30 days at the termination of the study.

In two aerobic soil metabolism studies, methomyl degraded with half-lives of 34.9 days in a Flanagan silt loam and 11.6 days in a loam so il from Madera, CA. The major degradate was

14 

### CO 2 

### (22.5% of the applied after 45 days in the silt loam soil, and 75% of the applied at 3 months in the loam soil). Unextractable residues peaked at 26% of the ap plied after 45 days in
the silt loam soil and 25% of the applied in the loam soil. Half-lives for soil metabolism that treat the unextracted, unide ntified material as if it were pare nt (total toxic residues method) are 109 and 25 days for the Flanagan and Madera so ils, respectively. Methom yl oxime was a minor degradate accounting for ≤ 2% of the applied.

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### Under anaerobic conditions, methomyl degraded with a half-life of 14 days in static conditions (nitrogen atmosphere) and <7 days in dynamic conditions (flowing nitrogen atmosphere) on a loam soil following 14 days of aerobic incubation. In the dynamic system, the major degradate

was 14 

### CO 2 

### , which comprised 30% of the applied during the 14 days of aerobic incubation, and an additional 23% after 60 days of anaerobic incuba tion. Unextracted residues peaked at 36% of the applied after 7 days of anaerobic incuba tion. More rapid degr adation under anaerobic conditions may be catalyzed by the presen ce of dissolved (ferrous) iron (MRID 43708806, Smelt, 1983; Bromilow, 1986). The proposed chemical reaction is:

Fe 2+



### CH 3 

### -C=N-O-C=O ------------> CH 3 

### C / N | |

S-CH 3 

### NH-CH 3



### TABLE 3.5. Methomyl degradates identified in laboratory degradation studies with their
time and maximal fraction of occurrence. Degradate Hydrolysis Aqueous Photolysis Soil Photolysis Aerobic
Soil
Metabolism Aerobic Aquatic
Metabolism Methomyl oxime 44% @ 30 d; pH 9 1% @ 1 d < 2%
Acetonitrile 70.1% @ 15 d 40% @ 30 d 27% @ 102 d

Acetamide 27% @ 7 d

Carbon dioxide 46% @ 102 d

In a supplemental aerobic aquatic metabolis m study (MRID 43325401) with two water-sediment systems from Great Britain, methomyl degraded with half-lives of 4.0 and 4.6 days in an Auchingilsie clay loam and Hinc hingbrooke silty clay loam, resp ectively. Initial pH was 6.8 for the Auchingilsie system and 7.6 for Hinchingbrooke . As is typical for these experiments with water-sediment systems, they had mixed redox po tentials and were neither completely aerobic
nor anaerobic. Unextracted and unidentified residues in the sediment were a significant component of the radioactive re sidues in these experiments with up 16% in the Auchingilsie system and 20% in the Hinchingbrooke system. The unextracted residues were decreasing with time at the end of the experiment in both syst ems indicating that these residues were still available. Half-lives estimated by combining th e methomyl parent with the unextracted residues (total toxic residues method) were 6.3 days fo r Auchingilsie and 7.4 days for Hinchingbrooke. Acetonitrile averaged a maximum of 17% of the applied at 7 days, and acetamide accounted for up to 14% of the applied at day 7. After 102 da ys, volatilized acetonitril e totaled up to 27% of the applied and 14 

### CO 2 

### was up to 46% of the applied.

The only non-volatile degradate f ound in the laboratory studies was methomyl oxime. It was present at high concentrations in the alkaline hydrolysis study but was only a minor degradate in the aerobic soil metabolism, anaerobic soil meta bolism, and photolysis in water studies ( ≤ 3% of the applied at all test intervals).

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### Several studies showed that dissipation of methomyl is rapid on foliage (Willis and McDowell, 1987). Of the 10 studies for meth omyl identified in this revi ew of foliar dissipation, three
measured total residues on the leaves rather than dislodgeable residu es. One of these three studies had significant rainfall during the study. The remaining two remaining studies, one on mint and the other on Bermuda grass, had half-l ives of 0.5 and 2.5 days, respectively. Because these studies only had rainfall afte r the pesticide is mostly dissi pated and volatili zation is likely to be very small for methomyl (see next section) , the dominant route of foliar dissipation is likely
aerobic metabolism on the leaf surface.

Mobility. Methomyl is mobile in soils as demonstrated by soil TLC (R f 

### values 0.46-0.82 and 0.86-0.93, respectively) (MRID 44306). Results of the batch equilibrium studies show methomyl has a low affinity to bind to soil (see Table 3.6 ) further indicating that the chemical will be mobile (MRID 161884). Methomyl binding is significantly correlated with soil organic carbon content, with a K OC 

### of 31.3 Lkg based on linear regression of K d 

### with soil organic carbon content. Methomyl is a highly soluble chemical in water (54.7 g/L). Its vapor pressure (5.6 x

10 -6 

### torr) and Henry’s Law Constant (2.1 x 10 -11 

### atm-m 3 

### /mol) indicate that it has a low potential
to volatilize.

TABLE 3.6. Summary of Isotherm Parameters from Soil Batch Equilibrium Studies for Methomyl.

Soil Fraction of organic matter K d 

### Freundlich
Coefficient Freundlich Exponent Cecil sandy loam 0.021 0.6036 0.7303 0.852 Flanagan silt Loam 0.043 0.9031 1.006 0.873 Keyport silt loam 0.075 1.211 1.374 0.856 Woodstown sandy loam 0.011 0.2039 0.2337 0.880

Bioaccumulation. The low octanol/water partition coefficient of 1.31 ± .02 σ suggests that the chemical will have a low tendency to accumulate in fish.

Field Dissipation. Five terrestrial field dissipation studies are av ailable for methomyl. Although the studies were found acceptable, some have defici encies that increase the level of uncertainty in the results. Dissipation half-lives from th e surface soil ranged from 4 to 54 days. Such variations can be expected in th e terrestrial field dissi pation studies because of the large number of processes that occur simultaneously and the large number of variable s present in the field.

The moderate persistence of methomyl appears to be tied to the soil conditions. In a muck soil (52% organic matter content), no methomyl was detected 7 days after treatment. A quick dissipation in a soil with such hi gh organic matter content may be re lated to microbial activity or rapid permeability. Two other studies conducte d in sand and silt loam soils show extensive dissipation ( ≥ 82% of the applied) after 1-3 months, with the remaining radioactivity recovered in the upper 8-15 inches of soil. No dissipation ha lf-lives could be calcu lated in these studies because only a few sampling intervals are available.

In two recent studies conducted in cropped cabba ge fields, the dissipation half-life from the surface ranged from 4-6 days in Mississippi to 54 days in California. Two factors may explain

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### the differences in dissipation between the two sites. Soil moisture content, which may affect the level of biological activity, varied between the two sites (moistur e contents ranged from 2.5% to
17% in the California soils and av eraged 16% over the first 15 days in the Mississippi soils). The Mississippi site received more rainfall, whic h may have led to more leaching out of the
surface. In both studies most of the methomyl residues were found in the upper 30 cm of soil.

Prospective Ground Water Study. A small-scale prospective groun d-water monitoring study was conducted for methomyl (MRID 43 568301, MRID 435998 01). Lannate L, a pesticide product containing methomyl, was applied in August 1992 to a s ite cropped in sweet corn in Cook County, Georgia. Monitoring continued until October 1994 when the study was term inated. The study was conducted by DuPont in a highly vul nerable, high use area of Geor gia. Methomyl was applied to the crop at the maximum label rate of 0.45 lbs a.i./A 25 times over 63 days for a total of 11.25 lbs a.i./A. Although this rate represents 1.5x the ma ximum label rate per crop of sweet corn, the study was conducted to support an increase in the ma ximum label rate, a labe l change that was not subsequently proposed by the re gistrant. Ground water was mon itored monthly for a period of 27 months. Methomyl was not detect ed in ground water when detec tions occurred in 12-foot depth suction lysimeters at concentrations up to 0.943 ppb. Out of the 156 sa mples taken from six downgradient wells in this study, on ly six samples from five wells contained methomyl residues. Concentrations ranged from 0.110 to 0.428 ppb, usi ng a detection limit of 0. 1 ppb, at Days 62 and 117. Sampling continued for 78 9 days, but no dete ctions were seen after Day 117.

3.4. Water Quality

Thiodicarb and methomyl are not identified as causes of impairme nt for any water bodies listed as impaired under section 303(d) of the Clean Water Act (based on information provided at http://iaspub.epa.gov/tmdl_waters10/attains_ nation_cy.cause_detail_303d?p_cause_group_id=88

5 , accessed August 26, 2009). In addition, no Total Maximum Daily Loads (TMDL) have been developed for thiodicarb or methomyl (based on information provided at http://iaspub.epa.gov/tmdl_waters10/attains_ nation.tmdl_pollutant_de tail?p_pollutant_group_id =885&p_pollutant_group_name=PESTICIDES , accessed August 26, 2009). More information on impaired water bodies and TMDLs can be found at http://www.epa.gov/owow/tmdl/ . The Agency invites submission of water quality data for these pesticides. To the extent possible, data should conform to the quality standards in Appendix A of the OPP Standard Operating Procedure: Inclusion of Im paired Water Body and Other Water Quality Data in OPP’s Registration Review Risk A ssessment and Management Process (see: http://www.epa.gov/oppfead1/cb/ppdc/2006/november06/session1-sop.pdf ), in order to ensure they can be used quantitatively or qual itatively in pesticide risk assessments.

4. Receptors

Consistent with the process described in th e Overview Document (USEPA 2004), the risk assessment for thiodicarb relies on a surrogate sp ecies approach. Toxico logical data generated from surrogate test species, which are intended to be representative of broad taxonomic groups, are used to extrapolate the pot ential effects on a variety of species (receptors) included under these taxonomic groupings. Because the thiodicarb degradate methomyl is also a registered pesticide (PC Code: 090301), data are available to define the toxicity of this degradate of

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### concern to non-target organisms. To adequately capture the risk from thiodicarb use, the toxicity and potential exposure to non-target animals to thiodicarb and its degradate methomyl will be considered. The most sensitive endpoints from the available toxicity data for thiodicarb and methomyl will be used to quantify risk.

Acute and chronic toxicity data from studies submitted by pesticide registrants along with the available open literature are used to evaluate the potential direct and indirect effects of thiodicarb to aquatic and terrestrial receptors. This includes toxicity on the technical grade active ingredient, degradates, and when available, formulated products ( e.g. , “Six-Pack” studies). The open literature studies are identified th rough EPA’s ECOTOXicology (ECOTOX) database, which employs a literature search engine for lo cating chemical toxicity data for aquatic life, terrestrial plants, and wildlife. The evaluation of both sources of data ma y also provide insight
into the direct and indirect effects of th iodicarb and its degradate methomyl on biotic communities from loss of species that are sensitive to the chemical and from changes in structure and functional characteristics of the affected communities. A preliminary review of open
literature data from ECOTOX on th iodicarb was conducted as part of this Problem Formulation to help identify data gaps. A more complete review of the data from ECOTOX will be conducted for evaluation for possible quantitative and/or qualitative incl usion in this risk assessment. Open literature data from an ECOTOX run conducted on 9/30/04 for methomyl have been fully reviewed as part of this Pr oblem Formulation. Information from an up-dated ECOTOX run for methomyl will be evaluated fo r possible quantitative and/or qualitative
inclusion in this risk assessment.

A summary of the most sensitiv e data representing non-target or ganisms exposed to thiodicarb and methomyl in aquatic and terrestrial habitats is provided in Sections 4.1 and 4.2, respectively. A summary of ecological incidents associated with thiodicarb and methomyl and a description of ecosystems potentially at risk are prov ided in Sections 4.3 and 4.4, respectively.

4.1. Effects to Aquatic Organisms

Methomyl, based on the available toxicity data fo r thiodicarb and methomyl, is more toxic or equitoxic to aquatic animals than thiodicarb on both an acute and chronic exposure basis with the exception of some estuarine/marine animals [ i.e ., eastern oysters ( Crassostrea virginica ) and sheepshead minnows ( Cyprinodon variegatus )] (see below).

Thiodicarb

A summary of the most sensitive aquatic toxicity data for thiodicarb from registrant-submitted studies is provided in Table 4.1 . A summary of all submitted ecotoxicity data for thiodicarb is provided in Appendix A . Thiodicarb is classified as modera tely toxic to fres hwater fish, highly toxic to estuarine/marine fish, a nd very highly toxic to aquatic i nvertebrates (both freshwater and estuarine/marine) on an acute exposure basis. The EC 50 

### for non-vascular aquatic plants ( Selenastrum capricornutum ) is >8.3 mg a.i./L, with a NOAEC of 1.6 mg a.i./L based on percent inhibition of growth (MRID 42324801). There are cu rrently no thiodicarb toxi city data available for vascular aquatic plants.

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### Regarding chronic effects, the only data currently available for thiodicarb and aquatic organisms are for freshwater fish and freshwater invertebrates ( i.e ., there are currently no chronic data available for estuarine/marine fish or invertebrates). For freshwater fish, the most sensitive NOAEC is 0.025 mg a.i./L for the fathead minnow ( Pimephales promelas ) based on reduced larval growth (a 4% decrease in total length and 14.3% decrease in wet weight at the 0.053 mg a.i./L concentration) (MRID 44484101). The only chronic toxicity data available for freshwater invertebrates is for daphnids ( Daphnia magna ) (MRID 00100688). This study resulted in a NOAEC of 0.009 mg a.i./L based on reduced su rvival and a reduction in the number of young produced (LOAEC = 0.018 mg a.i./L).

TABLE 4.1. Summary of the Most Sensitive Endpoints from Submitted Aquatic Toxicity
Studies for Thiodicarb.
Species Taxa Represented Toxicity Value MRID # Classification Comment Bluegill sunfish ( Lepomis
macrochirus ) 96-hr LC 50 = 1.21 mg a.i./L 00044273 Acceptable A slope could not be
determined

Fathead
minnow ( Pimephales promelas ) Freshwater fish and aquatic-phase

amphibians NOAEC = 0.025 mg a.i./L 44484101 Supplemental The NOAEC is based
on reduced larval growth – total length (4%) and wet weight (14.3%); LOAEC =0.053 mg a.i./L; sublethal signs of toxicity were not
noted

48-hr EC 50 = 0.0053 mg a.i./L 00044276 Acceptable A slope could not be
determined Daphnid ( Daphnia

magna ) Freshwater
invertebrates NOAEC = 0.009 mg a.i./L 00100688 Acceptable The NOAEC is based
on reduced survival and total young produced; LOAEC = 0.018 mg a.i./L

96-hr LC 50 = 0.47 mg a.i./L 42738501 Acceptable Slope = 4.4 (3.1 – 5.8) Sheepshead

minnow ( Cyprinodon variegatus ) Estuarine/marine
fish No chronic data
available N/A N/A N/A

Eastern oyster ( Crassostrea

virginica ) EC 50 = 0.55 mg
a.i./L 42834001 Acceptable Shell deposition study; NOAEC = 0.12 mg a.i./L

96-hr LC 50 = 0.0285 mg a.i./L 41891007 Acceptable Slope = 5.1 (0.62- 9.6); NOAEC = 0.018 mg a.i./L Mysid ( Americamysis
bahia ) Estuarine/marine
invertebrates

No chronic data
available- N/A N/A N/A

Algae ( Selenastrum capricornutum ) Non-vascular aquatic plants NOAEC = 1.6 mg
a.i./L

96-hr EC 50 = >8.3 mg a.i./L 42324801 Acceptable LOAEC = 2.4 mg
a.i./L based on % inhibition of growth [max inhibition was 37% at the highest
concentration tested (8.3 mg a.i./L)] Vascular aquatic plants No data available N/A N/A N/A



### -21 of 83-

### Methomyl

Based on the available data, methomyl is characte rized as very highly toxic to freshwater fish and invertebrates (freshwater and estuarine/marine) and moderately toxic to estuarine/marine fish on an acute exposure basis (see Table 4.2 ). A summary of all available ecotoxicity data for methomyl is provided in Appendix A . No aquatic plant data are currently available for methomyl.

Regarding chronic exposure, toxicity data for methomyl are available for freshwater fish, estuarine/marine fish, freshwater invertebrates, and estuarine/marine inve rtebrates. The most
sensitive NOAEC and LOAEC for fres hwater fish [fathead minnows ( Pimephales promelas )] are 0.057 and 0.117 mg a.i./L, based on reduced surviv al (MRID 131255). Since no toxicity data from chronic exposure to methomyl are available for the most acutely sensitive freshwater fish species, the channel catfish ( Ictalurus punctatus) , an acute to chronic ra tio (ACR) is used to
calculate a chronic freshwater fish endpoint using acute and ch ronic data from the fathead
minnow. This results in a NOAEC of 0.012 mg a.i./L for the channel catfish [(1.5 mg/L)/(0.057 mg/L) = (0.320 mg/L)/(x mg/L)].

For estuarine/marine fish, an early life-stage toxicity study (MRID: 450132-02) with sheepshead minnows resulted in a NOAEC of 0.26 mg a.i./L , and a LOAEC of 0.49 mg a.i./L, based on both reduction in total length and wet weight. Fish with deformed bodi es and fish exhibiting lethargy and erratic swimming were noted at 1.0 mg a.i./L on days 4 through 16, but were not observed at any other time during the study. No other sub-le thal effects (other than length and weight reductions) were noted at any other time or concentration.

A 21-day life-cycle toxicity study of Daphnia magna resulted in a NOAEC of 0.0007 mg. a.i./L and a LOAEC of 0.001 mg a.i./L based on de layed reproduction (MRID 131254). The NOAEC and LOAEC are 0.0016 and 0.0035 mg a.i./L, resp ectively, based on the number of young produced. No other sub-lethal effects were noted at any other time or concentration.

In a 28-day life-cycle toxicity study, mysid ( Americamysis bahia ) neonates were exposed under flow-through conditions to methomyl at mean measured concentrations ranging from 14.5 to 253 μg/L (MRID: 450132-03). The most sensitive meas ure of toxicity was th e reduced number of young per surviving female, which resulted in a NOAEC of 0.0291 mg a.i./L and a LOAEC of 0.0591 mg a.i./L. Since no toxicity data from chronic exposure to methomyl were available for the most acutely sensitive estuarine/marine i nvertebrate species, the northern pink shrimp ( Penaeus duorarum ), an acute to chronic ratio (ACR) was used to calculate a chronic estuarine/marine endpoint using acute and chronic data from mysids. Th is resulted in a NOAEC of 0.0024 mg a.i./L for the Northern pink shri mp [(0.234 mg/L)/(0.029 mg/L) = (0.019 mg/L)/(x

μ g/L)].

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### TABLE 4.2. Summary of the Most Sensitive Endpoints from Submitted Aquatic Toxicity Studies for Methomyl.
Species Taxa Represented Toxicity Value MRID # Classification Comment

Channel catfish ( Ictalurus punctatus) 96-hr LC 50 = 0.320 mg a.i./L 40098001 Supplemental Slope = 4.2 (2.3 – 6.2)

Channel catfish ( Ictalurus punctatus) Freshwater fish and aquatic-phase

amphibians NOAEC = 0.012 mg a.i./L N/A N/A Based an acute to chronic ratio (ACR) 1 using acute and
chronic data from the
fathead minnow and
acute data from the
channel catfish.

48-hr EC 50 = 0.005 mg a.i./L 40098001 Supplemental A slope could not be
determined Daphnid ( Daphnia

magna ) Freshwater
invertebrates NOAEC = 0.0007 mg a.i./L 1312541 Acceptable The LOAEC is 0.001 mg a.i./L based on delayed reproduction.

96-hr LC 50 = 1.16 mg a.i./L 41441202 Acceptable Slope = 8.0 Sheepshead

minnow ( Cyprinodon variegatus ) Estuarine/marine
fish NOAEC = 0.260 mg a.i./L 45013202 Acceptable The LOAEC is 0.490 mg a.i./L based on reduced growth Eastern oyster ( Crassostrea

virginica ) EC 50 = >140 mg
a.i./L 42074601 Acceptable Shell deposition study; NOAEC = 0.12 mg a.i./L

96-hr LC 50 = 0.019 mg a.i./L 00009134 Acceptable A slope could not be
determined

Northern pink shrimp ( Penaeus
duorarum ) Estuarine/marine
invertebrates

NOAEC = 0.0024 mg a.i./L N/A N/A Based an acute to chronic ratio (ACR) 2 using acute and
chronic data from mysid and acute data
from the Northern pink shrimp Non-vascular aquatic plants No data available N/A N/A N/A

Vascular aquatic plants No data available N/A N/A N/A

1 (1.5 mg/L)/(0.057 mg/L) = (0.320 mg/L)/(x mg/L)

2 (0.234 mg/L)/(0.029 mg/L) = (0.019 mg/L)/(x μ g/L)



### An outdoor microcosm study (MRID 437444-02) was conducted with the formulated methomyl product Lannate ® 

### L [24% a.i. (methomyl)] to evaluate the fate in tank water and hydrosoil and assess the effects on populations of phytoplankto n, zooplankton, macroinver tebrates, and bluegill sunfish. Applications were performed over a period of 22 days (22 daily applications) to 28 days (4 applications with a 7-day r eapplication interval); the total length of the study was 35 days. Treatment groups were defined by the amount of test substance added at each application (0.48 or 0.048 g a.i.; test vessel volume = 5,900 L; nom inal treatment concentrations were not provided) and by the interval between test substance appli cations [1 day (total of 22 applications), 3 days (total of 8 applications), or 7 days (total of 4 applications)]. Each of the 56 tanks used in the study was stocke d with bluegill sunfish and inoc ulated with aquatic plants and animals (invertebrates) from an untreated, pre-existing pond on site, colonized by native
invertebrates.

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### At the end of the study, phytoplankton showed no apparent methomyl-related effects. Zooplankton showed mixed results; the abunda nce of adult copepodes and rotifers generally increased following methomyl applications, howev er, cladoceran abundance was reduced (to less than 1% of the abundance of the control group) in the methomyl-treated groups and their
numbers did not recover during the study period.

During the microcosm study, temporary declines in abundance were observed in mayflies and three genera of chironomids, however, the resu lts are difficult to assess because they are confounded by a low number of organisms and high degree of variability within measurement endpoints in each treatment gr oup, including the controls.

Although macroinvertebrate sensitiv ity in the microcosm study parall eled results from laboratory toxicity tests, the sensitivity of fish in the microcosm study was not consistent with what was observed in the laboratory acute toxicity test s. Maximum methomyl concentrations at the highest treatment levels in the microcosm study (706 μ g/L) were almost twice as high as the most sensitive bluegill LC 50 

### value from the submitted laboratory studies (370 μ g/L); however, bluegill survival was no t affected in any of the microcosm treatment levels. Body length and body weight at harvest, however, were signifi cantly reduced (up to 18.5%) at all methomyl treatment levels when compared with controls. The decrease in body length and weight was not strongly associated with the methomyl treatment levels, i.e ., none of the measurements displayed a graded dose-response across the treatment groups. The size reductions were , thus, attributed to a decrease in food resources, particularly cladocerans.

4.2. Effects to Terrestrial Organisms

Methomyl, based on the available toxicity data fo r thiodicarb and methomyl, is more toxic or equitoxic to terrestrial animals than thiodicarb on both an acute and chronic exposure basis (see below).

Thiodicarb

Table 4.3 summarizes the most sensitive terrestrial to xicity endpoints for thiodicarb based on an
evaluation of submitted studies. Thiodicarb is cl assified as practically nontoxic to birds and honey bees and highly toxic to mammals on an acute exposure basis. Although thiodicarb is practically nontoxic to h oney bees, it is likely that thiodicarb is more toxic to at least some terrestrial invertebrate taxa since it is an insecticide. In a submitted study on a parasitic wasp ( Aphidius rhopalosiphi ), the 48-hr LC 50 

### value is 0.001 lb product (Larvin® SC 375, 38% a.i.)/acre (which equals 0.0004 lb a.i./acre) (M RID 45565801). This suggests that this species may be more sensitive to thiodicarb than honey bees; however, the wasp endpoint will not be used to calculate RQs in the a ssessment since it involves a produc t not currently registered for use in the U.S. There are currently no thiodicar b toxicity data availabl e for terrestrial plants.

For chronic exposure, the NOAEC for birds is 500 mg/kg-diet based on a reduction in the number of eggs laid per hen at the 1,000 mg a.i./kg-diet concentration in mallard ducks ( Anas platyrhynchos ) (MRID 43313004). For mammals, the ch ronic endpoint is a NOAEL of 100

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### mg/kg-diet (5 mg/kg/day) base d on decreased fetal body weight and viability at the 300 mg a.i./kg-diet concentration in laboratory rats ( Rattus norvegicus ) (MRID 42381301).

TABLE 4.3. Summary of the Most Sensit ive Endpoints from Submitted Terrestrial Toxicity Studies for Thiodicarb.

Species Taxa Represented Toxicity Value MRID # Classification Comment

Bobwhite quail ( Colinus virginianus ) LD 50 = 2,023 mg/kg-bw 46478 Acceptable A NOAEL could
not be determined
because there was a reduction in weight gain al all treatment levels; slope = 4.1 (1.6 – 6.6)

Mallard duck ( Anas platyrhynchos ) LC 50 = >5,620 mg/kgdiet 46479 Acceptable NOAEC = 1,780 mg a.i./kg-diet (LOAEC = 5,620 mg a.i./kg-diet
based on reduction
in food consumption and body weight gain)

Mallard duck ( Anas platyrhynchos ) Birds, reptiles,
and terrestrialphase amphibians

NOAEC = 500 mg/kgdiet 43313004 Acceptable LOAEC = 1,000 mg a.i./kg-diet,
based on reduction in number of eggs
laid/hen

Laboratory rat
( Rattus norvegicus ) LD 50 = 39.1 mg a.i./kgbw 00025791 Acceptable None

Laboratory rat Mammals NOAEL = 100 mg a.i./kg-diet (5 mg a.i./kg/day)

LOAEL = 300 mg a.i./kg-diet (15 mg a.i./kg/day) 42381301 Acceptable NOAEL based on
decreased fetal body weight and viability

Honey bee ( Apis mellifera ) Terrestrial
invertebrates LD 50 = >25 μg a.i./bee 42528501 Acceptable Acute contact; NOAEL = 3.1 μg a.i./bee; highest mortality was 37% at the highest
concentration tested ( i.e ., 25 μg a.i./bee)



### -25 of 83-Species Taxa Represented Toxicity Value Classification MRID # Comment

Wasp ( Aphidius rhopalosiphi ) 48-hr LC 50 = 0.001 lb product (38% a.i.)/acre
= 0.0004 lb a.i./acre 45565801 Supplemental (not adequate for RQ calculation) Scientificallysound, but a nonguideline study and not adequate for RQ calculation (it involves a product not currently registered in the U.S; slope = 2.21 (1.59 – 2.83)

Terrestrial Plants No da ta available N/A N/A N/A



### Methomyl

Table 4.4 summarizes the most sensitive terrestrial to xicity endpoints for methomyl based on an evaluation of submitted studies. Methomyl is cla ssified as highly toxic to birds, mammals, and honey bees on an acute exposure basis. In a submitted study on a parasitic wasp ( Aphidius rhopalosiphi ), the 48-hr LC 50 

### value is 0.00022 lb a.i./acre (whi ch equals 0.0004 lb a.i./acre) (MRID 45565801). This suggests that this species, as with thiodicarb, may be more sensitive to methomyl than honey bees, however, the wasp endpoint will not be used to calculate RQs in the assessment since it involves a product (Methomyl® 25WP) not currently registered for use in the U.S. There are currently no me thomyl vegetative vigor or seed ling emergence toxicity data available for terrestrial plants.

An avian reproduction study was performed on meth omyl with the northern bobwhite quail. In this study, the LOAEC is 500 mg/kg-diet based on fewer eggs laid and eggs set and the NOAEC is 150 mg a.i./kg-diet (MRID: 41898602). In a 2-generation reproduction study with rats, the NOAEL for parental systemic toxicity is 3.75 mg /kg-bw and the LOAEL is 30 mg/kg-bw based on decreased body weight and food consumption and altered hematology parameters. The NOAEL for offspring toxicity is also 3.75 mg/kg-bw and the L OAEL is 30 mg/kg-bw based on decreases in both the mean number of live pups and mean body weights of offspring (MRIDs: 43250701, 43769401).

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### TABLE 4.4. Summary of the Most Sensit ive Endpoints from Submitted Terrestrial Toxicity Studies for Methomyl.

Species Taxa Represented Toxicity Value MRID # Classification Comment

LD 50 = 24.2 mg/kg-bw 0 0161886 Acceptable None

LC 50 = 1,100 mg/kgdiet 22923 Acceptable None

Bobwhite quail ( Colinus virginianus ) Birds, reptiles,
and terrestrialphase amphibians NOAEC = 150 mg/kgdiet 41898602 Acceptable LOAEC = 500 mg a.i./kg-diet, based
on reduction in number of eggs
laid/hen

Laboratory rat
( Rattus norvegicus ) LD 50 = 30 mg a.i./kgbw 42140101 Acceptable None

Laboratory rat ( Rattus norvegicus ) Mammals NOAEL = 75 mg a.i./kg-diet (3.75 mg a.i./kg/day)

LOAEL = 600 mg a.i./kg-diet (30 mg a.i./kg/day) 43250701,
43769401 Acceptable NOAEL based on
decreases in both
the mean number of live pups and mean body weights of offspring

LD 50 = 0.28 μg a.i./bee Acute oral; NOAEL = 0.09 μg
a.i./bee Honey bee ( Apis mellifera ) LD 50 = 0.16 μg a.i./bee 45093001 Acceptable

Acute contact; NOAEL = 0.08 μg
a.i./bee

Wasp ( Aphidius rhopalosiphi ) Terrestrial
invertebrates 48-hr LC 50 = 0.00022 lb
a.i./acre 45133301 Supplemental (not adequate for RQ calculation) Scientificallysound, but a nonguideline study and not adequate for RQ calculation (it involves a product not currently registered in the U.S.)

Terrestrial Plants No da ta available N/A N/A N/A



### Although there are no acceptable te rrestrial plant guideline studi es available for methomyl, several efficacy studies that were conducted to test the effects of me thomyl on a variety of invertebrate target and non-targ et pests also supplied informa tion on effects to plants after methomyl applications. Due to a lack of info rmation on study design and data analyses, these efficacy studies are classified as ‘supplemental’ and are not adequate for plant (or terrestrial invertebrate) RQ calculation, however, they are c onsidered scientifically valid. None of the studies showed any adverse effects to plants at the highest treatment levels tested (most of which

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### were at or above the maximum allowable single app lication rate for methomyl of 0.9 lb a.i./acre) (see Table 4.5 ).

TABLE 4.5. Measures of Effects to Plants fr om Methomyl Efficacy Studies that Included
Information on Effects to Plants.

PLANT SPECIES NOAEL HIGHEST

LEVEL
TESTED? 1 EFFECT 2 ECOTOX NO./REFERENCE

Alfalfa ( Medicago sativa ) ≥ 0.9 lb a.i./acre Yes Growth 88088/Laub et al . (1999)

≥ 3.6 lb a.i./acre Yes Growth Injury 74745/Morale and Kurundkar (1989) Auberine ( Solanum melongena )

≥ 1,000 ppm Yes Growth 89394/Sharma et al . (1997)

Bean ( Phaseolus vulgaris ) ≥ 0.9 lb a.i./acre Yes Injury 88838/Ghidiu (1988)

≥ 946 ml/acre Yes Growth 82231/Stansly and Cawley (1993)

≥ 0.9 lb a.i./acre Yes Growth 82730/Schuster (1994) Bell pepper ( Capsicum annuum )

≥ 0.9 lb a.i./acre Yes Biomass 82246/Zehnder and Speese (1992) Cabbage ( Brassica oleracea ) ≥ 0.9 lb a.i./acre Yes Injury 88084/Edelson et al . (1999)

Hybrid strawberry ( Fragaria x ananassa ) ≥ 0.9 lb a.i./acre Yes Photosynthesis 88792/Carson et al . (1986)

Lettuce ( Lactuca sativa ) ≥ 1 lb a.i./acre Yes Abundance 82237/Palumbo et al . (1991)

Peony ( Paeonia lactiflora ) ≥ 20.0 lb a.i./acre Yes Abundance 89251/Schmitt et al . (1974)

Peach ( Prunus persica ) ≥ 0.23 lb a.i./100 gallon Yes Injury 88091/Hull (1999)

Pigeonpea ( Cajanus cajan ) ≥ 0.53 lb a.i./acre Yes Abundance 82560/Giraddi et al . (2002)

Potato ( Solanum tuberosum ) ≥ 1.0 lb a.i./acre Yes Injury 77263/Raman and Palacios (1986)

≥ 0.45 lb a.i./acre Yes Injury 74169/Walgenbach et al . (1991)

≥ 0.9 lb a.i./acre Yes Injury 88062/Carson et al . (1999)

≥ 0.9 lb a.i./acre Yes Injury 88089/Kund et al . (1999)

≥ 0.9 lb a.i./acre Yes Injury 88089/Kund et al . (1999)

≥ 0.45 lb a.i./acre Yes Injury 88269/Stansly et al . (1999) Tomato ( Solanum sp.)

≥ 4.0 lb a.i./acre Yes Biomass 89472/McLeod (1972)

Wild celery ( Apium graveolens ) ≥ 0.9 lb a.i./acre Yes Injury 82728/Carson et al . (1994)

1 ‘Highest Level Tested’ refers to whether th e NOAEL represents the highest level tested.

2 ‘Effect’ refers to the effect that was measured in the study. Because th e NOAELs represent the highest level tested in each study, no adverse effects to pl ants were observed in any of the studies.



### 4.3. Incident Databases Review

Preliminary reviews of the Ecological Incident Information System (EIIS, version 2.1) and the Avian Incident Monitoring System (AIMS) 1 

### were conducted on June 5 and August 13 2009, respectively. There are currently no reported wildlife or plant incide nts involving thiodicarb
listed in the EIIS or AIMS databases. A total of 12 incidents associated with methomyl use,

1 http://www.abcbirds.org/abcprograms/ policy/pesticides/aims/aims/index.cfm



### -28 of 83-

### however, have been reported (8 involving terrestrial organism s – all birds -and 4 involving aquatic organisms – all fish). The reporte d incidents occurred be tween 1976 and 2006. The certainty in which these incidents were a resu lt of methomyl use was described as highly probable in two incidents, highly likely in two in cidents, probable in four incidents, possible in two incidents, and unlikely in two incidents. Three of the incident s were the result of registered use, five were the result of misu se (intentional baiting); however, it is unknown if the other four
incidents resulted from misuse or registered uses. Specific detail s of the incidents are described
below.

In addition to the incidents reco rded in EIIS and AIMS, additiona l incidents have been reported to the Agency in aggregated incident reports. Pesticide registrants re port certain types of incidents to the Agency as a ggregate counts of incidents occu rring per product per quarter. Ecological incidents reported in aggregate reports include those cat egorized as ‘minor fish and wildlife’ (W-B), ‘minor plant’ (P -B), and ‘other non-ta rget’ (ONT) incidents. ‘Other non-target’ incidents include reports of adve rse effects to insects and other terrestrial invertebrates. No aggregate incident reports have been submitted to the Agency for thiodicarb. For methomyl, registrants have reported 7 minor fish and wildlife incidents, all of which occurred between 2000
and 2007. The number of individuals involved in these incidents was not specified. Unless additional information on these aggregated incident s become available, they will be assumed to be representative of registered uses in the risk assessment.

Terrestrial Incidents

Five of the terrestrial incidents (one from New York, one from Maine, two from Florida, and one from Greece) were the result of in tentional baiting and involved mo rtality in the following birds: rock dove ( Columba livia ), egret (species not provided), crow ( Corvis sp.), red-tailed hawk ( Buteo jamaicensis ), American kestrel ( Falco sparverius ), Eleanora’s falcon ( Falco eleonorae ), and grackle ( Quiscalus spp .) [Incident #/Event ID: (EIIS) I009064-001, I011181-001, and I017139-001; (AIMS) 1841 and 1953]. The legality of use for one of the incidents, which occurred in the British Virgin Islands and involve d the death of 13 gulls and one cattle egret, was undetermined (Incident #: I1018980-10). Oxamyl, whic h is classified as very highly toxic to birds on an acute exposure basis, was also susp ected in this incident. Two of the incidents occurred in France and involved the register ed use (in France) of methomyl on cabbage (methomyl is also registered for use on cabbage in the United States). Incident # I006382-001 occurred in 1989 from a foliar spra y of methomyl at a rate of 0.225 lb a.i./acre. This incident, which was classified as ‘probable’, resulted in th e mortality of at least 52 finches. The other French incident (I006382-002; 1992) was also cl assified as ‘probabl e’ and involved the registered use of methom yl (foliar spray) on cabbage. This incident involved the incapacitation of 31 birds and mortality in 35 birds (finches a nd linnets) after the birds were observed drinking dew from the cabbage field the da y after methomyl application.

Aquatic Incidents

A fish kill occurred in a canal near Blythe , California on January 7, 1978 (Incident # B0000-501- 36). The treatment site is unknown, and it is unknow n if the kill was the result of misuse or registered use. Approximately 540 catfish ( Ictalurus spp .) and largemouth bass ( Micropterus

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### salmoides ) were killed in an area of standing water. Lannate ® 

### (methomyl), Thiodan ®


### (endosulfan), and parathion were suspected as bei ng the cause of the kill, but analyses of water and fish showed only endosulfan to be present. Water samples contained between 0.27 and 0.64 ppb endosulfan. Also, gills and liver contai ned 2500 and 1100 ppb endosulfan, respectively, and gills of largemouth bass contained 930 ppb endosul fan. This report was listed as ‘unlikely’ relative to methomyl being the cause of the in cident because only endosulfan was detected in water and fish residue samples indicate that e ndosulfan, and not methomyl, was responsible for
the fish kill.

In a report from the California Fish and Game Department (Incident # I000108-001), there was a large fish kill, i.e ., several thousand threadfin shad ( Dorosoma petenense ) and catfish ( Ictalurus

spp .), in the San Joaquin River near the town of Lathrop, California on October 16, 2001. The treatment site is unknown, and it is u nknown if the kill was the result of misuse or registered use. The certainty that the kill resulted from meth omyl was listed as ‘possible’. However, upon further review of the incident, it was acknowledg ed by California Fish and Game that un-ionized ammonia was the cause of the fish kill. Analys es of composited gill sa mples found the presence of several pesticides ( i.e ., dioxathion = 121.1 ppm; carbaryl = 1.75 ppm; carbofuran = 4.51 ppm; fenurin = 0.78 ppm; methomyl = 5.08 ppm; monu ron = 5.83 ppm). However, these pesticides were not detected in the water samples and no mention was made in the California Fish and Game report that these pesticides may have been important factors in the fish kill.

A fish kill incident occurred in Seminole County, Georgia, on June 16, 1992 (Incident # I00108- 001). The treatment site was corn, and it is unkno wn if the kill was the result of misuse or registered use. Also, the certainty that the kill resulted from methomyl was listed as ‘probable’. Upon further review of the incident report, it was assumed that runoff from a 200-acre plot of
sweet corn treated with fe rtilizer and insecticides k illed 125 bluegill, bowfin ( Amia calva ), and carp ( Cyprinus spp ). During a rainy two week period prior to the fish kill, the corn plot had been treated with 5 applicatio ns of methomyl (aerial, 1.5 pints/acre), 4 applica tions of chlorpyrifos, 4 applications of fertilizer, and 2 applications of borax. The suspected cause of the fish kill was methomyl, as Lannate ® 

### LV, toxicosis. Measured concentr ations of methomyl were found in water samples taken from the pond and pond-overflow area.

A fish kill involving an unknown number and speci es of fish occurred in Riverside County, California, on November 18, 1976 (B0000-216-19). Th e incident occurred after registered uses of endosulfan, mevinphos, and methomyl on lettuce; however, the report states it was ‘unlikely’ that methomyl caused the fish kill.

Due to limitations with data in the EIIS, a low number or lack of reported incidents in the
database cannot be used as evidence that addition al incidents have not oc curred. Incident reports for non-target plants and animals typically pr ovide information on mortality events only. Reports for other adverse effects, such as reduced growth or impaired reproduction, are rarely received. EPA’s changes in the registrant repo rting requirements of incidents may also account for the reduced number of repor ted incidents. Registrants are now only required to submit detailed information on ‘major’ incidents. Mi nor incidents are genera lly reported aggregately and are not included in EIIS. In addition, there ha ve been changes in state monitoring efforts due
to lack of resources.

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### 4.4. Ecosystems Potentially at Risk

The ecosystems at risk are often extensive in scop e; therefore, it may not be possible to identify specific ecosystems during the development of a nation-wide ecological risk assessment. However, in general terms, terrestrial ecosystem s potentially at risk could include the treated field and immediately adjacent areas that may r eceive drift or runoff. Areas adjacent to the
treated field could include cultiv ated fields, fencerows and hedgero ws, meadows, fallow fields or grasslands, woodlands, riparian habita ts and other uncultivated areas.

Aquatic ecosystems potentially at risk include wa ter bodies adjacent to, or down stream from, the
treated field and could include impounded bodies such as ponds, lake s and reservoirs, or flowing waterways such as streams or rivers. For uses in coastal areas, aquatic habitat also includes marine ecosystems, including estuaries.

5. Assessment Endpoints

Assessment endpoints represent the ac tual environmental value that is to be protected, defined by an ecological entity (species, community, or othe r entity) and its attri bute or characteristics (USEPA 1998). For thiodicarb, the ecological entities may incl ude the following: birds, mammals, terrestrial-phase amphibian s, reptiles, freshwater fish a nd invertebrates, aquatic-phase amphibians, estuarine/marine fish and invertebrate s, terrestrial plants, terrestrial invertebrates, and aquatic plants. The attributes for each of these entities include growth, reproduction, and
survival.

6. Conceptual Model

For a pesticide to pose an ecological risk, it mu st 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 recepto r. 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, an d a feasible route of exposure.

The conceptual model for thiodicarb provides a wr itten description and visual representation of the predicted relationships between thiodicarb (and its degradate me thomyl), 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).

Based on the submitted environmental fate data, thiodicarb is not expected to volatilize or persist in soil or alkaline water bodies, but may potentia lly leach to ground water and move to surface water through runoff and spray drift. Thiodica rb’s main degradate, methomyl, is also not expected to volatilize and may l each to ground water and move to surface water through runoff and base flow. Methomyl is degraded by meta bolism and photolysis in clear water. Due to relatively low BCF and K OW 

### values, thiodicarb and methomyl ar e not expected to bioaccumulate in aquatic or terrestrial food chains.

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### Based on previous ecological risk assessments for thiodicarb, there is the potential for acute and chronic risk from the exposure of aquatic invertebrates, fish, bi rds, and mammals to thiodicarb and to the subsequently formed active degradate, methomyl. Because of the potential risk for direct effects to taxa (both listed and non-listed) described above, listed sp ecies in all taxa may potentially be affected indirectly due to al terations in their habitat and prey items ( e.g ., food sources, shelter, and areas to reproduce). These preliminary conclusions are used to derive the risk hypothesis and conceptual diagram discussed below.

6.1. Risk Hypothesis

A risk hypothesis describes the predicted re lationship among the stre ssor, exposure, and assessment endpoint response along with the rationa le for their selection. For thiodicarb, the following ecological risk hypothesi s is being employed for this ecological risk assessment:

Based on the application methods, mode of ac tion, fate and transport, and the sensitivity of non-target aquatic and terre strial species, thiodicarb (and its degradate methomyl) has the potential to reduce survival, reproducti on, and/or growth in non-target terrestrial and aquatic organisms when used in accordan ce with the current labels. These nontarget organisms include Federally-listed threatened and endangered species as well as non-listed species.

6.2. Conceptual Diagram

The environmental fate properties of thiodicarb and its degradate methomyl indicate that runoff, spray drift and direct spray repr esent potential transport mechanis ms of thiodicarb and methomyl to aquatic and terrestrial habita ts where non-target organisms ma y be exposed. These transport mechanisms ( i.e ., sources) are depicted in the conceptual models below ( Figures 6.1 and 6.2 ) along with the receptors of con cern and the potential attribute ch anges in the receptors due to exposures of thiodicarb and its degradate methomyl. Although thiodi carb and methomyl may leach to ground water, neither compound is expected to persist long enough to contaminate the
base flow of surface water bodies.

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### Stressor

Source

Receptors

Attribute Change Thiodicarb applied to use site Thiodicarb degrading to methomyl

Spray drift

Fish/aquatic-phase amphibians Eggs

Larvae
Juveniles / Adults

Individual organisms
Reduced survival Reduced growth Reduced reproduction Food chain Reduction in algae Reduction in prey Habitat integrity Reduction in primary productivity
Reduced cover Surface water/

Sediment Runoff

Aquatic Animals
Invertebrates
Vertebrates 

### Exposure

Uptake/gills or integument

Ingestion Ingestion Long-range atmospheric

transport

Wet/dry deposition Soil Ground water

Uptake/gills or integument

Aquatic Plants

N on-vascular
Vascular Uptake/cell, roots, leaves Riparian plant
terrestrial

exposure pathways see

Figure 6.2 

### Media

Community change



### FIGURE 6.1. Conceptual Model for Thiodicarb and Methomyl Effects on Aquatic Organisms. Dotted Lines Indicate Exposure Pa thways that Have a Low Likelihood of Contributing to Ecological Risk.

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### Stressor

Source

Receptors

Attribute Change Thiodicarb applied to use site Thiodicarb degrading to methomyl

Direct application Spray drift

Birds / Terrestrial-phase amphibians / reptiles /

Terrestrial
invertebrat

Individual organisms
Reduced survival Reduced growth Reduced reproduction Food chain
Reduction in p re y Habitat integrity Reduction in primary productivity
Reduced cover Community change Terrestrial/riparian plants grasses/forbs, fruit, seeds (trees, shrubs) Runoff

Mammals 

### Exposure
Media Soil

Ingestion Ingestion

Ingestion Ingestion Dermal uptake/Ingestion Long-range atmospheric

transport

Root uptake
Wet/dry deposition

Birds /

A m phibian s Ingestion



### FIGURE 6.2. Conceptual Model for Thiodi carb and Methomyl Effects on Terrestrial Organisms.

7. Analysis Plan

In order to address the risk hypot hesis, the potential for adverse effects on the environment will be estimated. The use, environmental fate, a nd ecological effects of thiodicarb and methomyl will be characterized and integrated to assess th e risks. Exposure to thiodicarb and methomyl will reflect the predicted environmental fate of either each compound separately or together as methomyl equivalents, depending on the toxicity differential for assessed organisms. Risk quotients (RQs) will be derived for thiodica rb and/or methomyl by dividing estimated environmental concentrations (EEC) by the most sensitive endpoint from the relevant, available toxicity data for thiodicarb and/or methomyl.

This analysis plan will be re visited and may be revised dependi ng upon a full review of the data available in the open literature and the inform ation submitted by the public in response to the opening of the Registration Review docket.

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### 7.1. Stressors of Concern

The primary degradate of concern, methomyl, is cons idered to have attributes and effects similar to parent thiodicarb. Thus, the residues of conc ern in this assessment in clude both thiodicarb and methomyl. Modeled exposure estimates resul ting from thiodicarb usage will reflect the predicted environmental fate of either thiodicarb and methomyl separately or together as methomyl equivalents, depending on the toxici ty differential of the compounds for assessed organisms.

In its ecological risk assessments, the Agency does not routinely include an evaluation of mixtures of active ingredients, either those mi xtures of multiple activ e ingredients in product formulations or those in the applicator’s tank. In the case of the product formulations of active ingredients (that is, a registered product contai ning more than one active ingredient), each active ingredient is subject to an indi vidual risk assessment for regula tory decision regarding the active ingredient on a particular use site. If eff ects data are available for a formulated product containing more than one active ingredient, the da ta may be used qualitatively or quantitatively in accordance with the Agency’s Overview Document and the Services’ Evaluation Memorandum (USEPA 2004; U SFWS/NMFS 2004).

Available toxicity data for environmental mixtures of thiodicarb with other pesticides will be presented as part of the ecological risk assessmen t. It is expected th at the toxic effect of thiodicarb, in combination with ot her pesticides used in the environment, is likely to be a function of many factors including but not necessarily limited to: (1 ) the exposed sp ecies, (2) the co-contaminants in the mixture, (3) the ratio of thiodi carb and co-contaminan t concentrations, (4) differences in the pattern and duration of expos ure among contaminants, and (5) the differential effects of other physical/chemical charac teristics of the r eceiving waters ( e.g. organic matter present in sediment and suspended water). Quan titatively predicting the combined effects of all these variables on mixture toxicity to any given taxa with conf idence is beyond the capabilities of the available data and methodologies. However, a qualitative discussion of implications of the available pesticide mixture effects data on the confidence of risk assessment conclusions will be addressed as part of the uncertainty analysis.

7.2. Measures of Exposure

In order to estimate risks of thiodicarb exposur es in aquatic and terres trial environments, all exposure modeling and resulting risk conclusion s will be made based on maximum application rates for the currently registered uses [ i.e ., broccoli, cabbage, cauliflower, cotton, a variety of leafy vegetables, soybeans, sweet corn, ornamental s and trees (except fore st), and non-crop areas ( i.e ., wastelands, roadsides, rights-of-way, grassway s, shelter belts, and fencerows)] as discussed in Section 5. Measures of exposure are based on aquatic and terrestrial models that predict estimated environmental concentrations (EEC) of thiodicarb using maximum labeled application rates and application methods that have the gr eatest potential for off-s ite transport of the chemical. A method for estimating methomyl e xposure resulting from thiodicarb applications will be selected based on the available data. The models used to predict aquatic EECs are the
Pesticide Root Zone Mode l coupled with the EXposur e Analysis Model System (PRZM/EXAMS). The model used to predict te rrestrial EECs on food items is T-REX. The

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### model used to derive EECs relevant to terrestria l and wetland plants is Te rrPlant. These models are parameterized using relevant reviewed registrant-submitted environmental fate data.

PRZM (v3.12.2, May 2005) and EXAMS (v2.98.4.6, Ap ril 2005) are screening simulation models coupled with the graphical user interf ace, PE (v5.0, November 2006) to generate daily exposures and 1-in-10-year EECs of thiodicarb that may occur in surface water bodies adjacent to application sites receiving thiodicarb th rough runoff and spray drift. PRZM simulates pesticide application, movement and transforma tion on an agricultural field and the resultant pesticide loadings to a recei ving water body via runoff, erosion, and spray drift. EXAMS simulates the fate of the pestic ide and resulting concentrations in the water body. The standard watershed geometry used for ecological pestic ide assessments assumes application to a 10- hectare agricultural field that drains into an ad jacent 1-hectare water body that is 2 meters deep (20,000 m 3 

### volume) with no outlet. The composite model PRZM/EXAMS is used to estimate screening-level exposure of aquatic organisms to thiodicarb. The measure of exposure for aquatic species is the 1-in-10-year peak or rolling mean concentra tion. The 1-in-10-year peak is used for estimating acute exposures of direct effects to aquatic organisms. The 1-in-10-year 60- day mean is used for assessing chronic exposure to fish and aquatic-phase amphibians. The 1-in10-year 21-day mean is used for assessi ng aquatic invertebrate chronic exposure.

Exposure estimates for terrestrial an imals assumed to be in the target area or in an area exposed to spray drift are derived using the T-REX model (version 1.4.1, 10/08/2008). This model incorporates the Kenaga nomogr aph, as modified by Fletcher et al. (1994), which is based on a large set of actual field residue data. The upper limit values from the nomograph represent the

95 th 

### percentile of residue values from actual field measurements (Hoerger and Kenaga, 1972).
The Fletcher et al. (1994) modifications to the Kenaga nomograph are based on measured field residues from 249 published research papers, including information on 118 species of plants, 121 pesticides, and 17 chemical classe s. If terrestrial plant toxicity data are available, EECs for terrestrial plants inhabiting dry and wetland ar eas are derived using TerrPlant (version 1.2.2, 12/26/2006). This model uses estimates of pesticid es in runoff and in spray drift to calculate EECs. EECs are based upon solubility, applicati on rate and minimum incorporation depth.

The AgDRIFT spray drift model (v2.01; May 2001) is used to assess exposures of organisms to thiodicarb deposited on terrestrial habitats by spray drift.

7.3. Measures of Effect

Ecological effects data are used as measures of di rect and indirect effects to biological receptors. Data are obtained from registrant-submitted studies or from literature studies identified by ECOTOX. The ECOTOX database pr ovides more ecological effects da ta in an attempt to bridge existing data gaps. ECOTOX is a source for locati ng single chemical toxicity data and potential chemical mixture toxicity data for aquatic life, terrestrial plants, and wildlife. ECOTOX was created and is maintained by the USEPA, Office of Research and Development, and the National
Health and Environmental Effects Research Laboratory's Mid-Continent Ecology Division.

Information on the potential effects of thiodica rb (and its degradate methomyl) on non-target animals is also collected from the Ecologica l Incident Information System (EIIS; USEPA

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### 2007 c ). The EIIS is a database containing advers e effect (typically mortality) reports on nontarget organisms where such effects have been associated with the use of pesticides. Incidents reported in the aggreg ate incident reports and the Av ian Incident Monitoring System (AIMS) will also be searched. AIMS is a database administered by the American Bird Conservancy (it was partially funded by the EPA) . It contains publicly available data on reported avian incidents involving pesticides (http://www.abcbirds.org/abcprograms/po licy/pesticides/aims/aims/index.cfm).

Where available, sub-lethal effects observed in both registrant-submitted and open literature studies will be evaluated qualitatively. Such effects may include behavioral changes ( e.g. , lethargy and changes in colora tion). Quantitative assessments of risks, though, are limited to those endpoints that can be di rectly linked to the Agency’s assessment endpoints of impaired survival, growth and reproduction.

The assessment of risk for direct effects to non-target organisms makes the assumption that toxicity of thiodicarb and met homyl to birds is similar to terrestrial-phase amphibians and reptiles. The same assumption is made for fish and aquatic-phase amphibians.

The acute measures of effect used fo r animals in this assessment are the LD 50 

### , LC 50 

### and EC 50



### . LD stands for "Lethal Dose", and LD 50 

### is the amount of a material, given all at once, that is
estimated to cause the death of 50% of the test organisms. LC st ands for “Lethal Concentration”
and LC 50 

### is the concentration of a chemical that is estimated to kill 50% of the test organisms.
EC stands for “Effective Concentration” and the EC 50 

### is the concentration of a chemical that is estimated to produce a specific effect in 50% of the test organisms. Endpoints for chronic measures of exposure for listed and non-lis ted animals are the NOAEL/NOAEC and NOEC.
NOAEL stands for “No Observed-Adverse-Effect-Level ” and refers to the hi ghest tested dose of a substance that has been reported to have no harm ful (adverse) effects on test organisms. The NOAEC ( i.e. , “No-Observed-Adverse-Effect-Concentration” ) is the highest test concentration at
which none of the observed effects were statistically different fr om the control. The NOEC is
the No-Observed-Effects-Concentration. Fo r non-listed plants, only acute exposures are assessed ( i.e. , EC 25 

### for terrestrial plants and EC 50 

### for aquatic plants); for listed plants either the

NOAEC or EC 05 

### is used.

7.4. Integration of Exposure and Effects

Risk characterization is the integration of e xposure and ecological effects characterization to determine the potential ecological risk from the us e of thiodicarb and the likelihood of direct and indirect effects to non-target organisms in aquatic and terrestrial habitats. The exposure and toxicity effects data are integrated in order to evaluate the risks of a dverse ecological effects on non-target species. For the assessm ent of thiodicarb risks, the risk quotient (RQ) method is used to compare exposure and measured toxicity va lues. EECs are divided by acute and chronic toxicity values. The resulting RQ s are then compared to the Agen cy’s Levels of Concern (LOC) (USEPA 2004). These criteria are used to indi cate when thiodicarb’s use, as directed on the labels, has the potential to cause adverse direct or indirect effect s to non-target organisms. In addition, incident data from EIIS, aggregate incide nt reports, and AIMS will be considered as part of the risk characterization.

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### 7.5. Deterministic and Probabilistic Assessment Methods

The quantitative assessment of risk will primarily depend on the deterministic point-estimate based approach described in th e risk assessment. Depending on the risk manager’s need for additional information regarding risk, an effort will be made to further qualitatively describe risk using probabilistic tools that the Agency has developed. These tools have been reviewed by FIFRA Scientific Advisory Panels ( http://www.epa.gov/sc ipoly/sap/index.htm ) and have been deemed as appropriate means of refining asse ssments where deterministic approaches have
identified risks.

7.6. Endangered Species Assessments

Consistent with the Agency’s responsibility under the Endangered Species Act (ESA), the Agency will evaluate risks to Federally-listed th reatened and/or endangere d (listed) species from registered uses of thiodicarb. This assessm ent will be conducted in accordance with the Overview Document (USEPA 2004), provisi ons of the ESA, and the Services’ Endangered Species Consultation Handbook (USFWS/NMFS 1998).

The assessment of effects associat ed with the registration of th iodicarb is based on an action
area. The action area is considered to be the ar ea directly or indirectly affected by the federal action, as indicated by the exceedance of Agency Le vels of Concern (LOCs) used to evaluate
direct or indirect eff ects. The Agency’s approach to defi ning the action area under the provisions of the Overview Document (USEPA 2004) considers the results of the risk assessment process to establish boundaries for that action area with the understandi ng that exposures below the Agency’s defined LOCs constitute a no-effect threshold. For th e purposes of this assessment,
attention will be focused on the footprint of the action ( i.e ., the area where thi odicarb application occurs), plus all areas where offsite transport ( i.e ., spray drift, runoff, etc .) may result in potential exposure that exceeds the Agency’s LOCs. Specific measures of ecological effect that define the action area for listed species include any direct and indi rect effects and/or potential modification of its critical habitat, including reduction in survival, growth, and reproduction as well as the full
suite of sub-lethal effects availabl e in the effects literature. Ther efore, the action area extends to a point where environmental exposures are below any measured lethal or sub-lethal effect threshold for any biological entity at the whole organism, organ, tissue, and cellular level of organization. In situations where it is not po ssible to determine the threshold for an observed effect, the action area will be assumed to encompass the entire United States.

7.7. Drinking Water Assessment

A drinking water assessment will be conducted to support future human health risk assessments of thiodicarb. The drinking water assessment will incorporate model estimates of thiodicarb residues of concern, including methomyl and any ot her degradates to be determined, in surface and ground waters. In contrast to the approach for ecological assessment, all sources of thiodicarb and methomyl will be considered, incl uding direct applications of methomyl as a pesticide active ingredient. Whether exposure es timates will reflect thiodicarb separately from methomyl or as methomyl equivalents will depend on the toxicity differential of the compounds.
Concentrations of thiodicarb residues of con cern in surface water will be estimated using

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### -39 of 83- PRZM/EXAMS (see description in Section 7.2 ). Ground water exposure estimates for
thiodicarb residues of concern wi ll be estimated using the Sc reening Concentration in Ground Water (SCI-GROW) model (v.2.3, July 2003) followe d by a higher tier model if necessary. The drinking water assessment will also include a summary of available surface and ground water monitoring data.

7.8. Preliminary Identification of Data Gaps

7.8.1. Fate

The studies submitted to fulfill environmental fate data requirements for thiodicarb are sufficient for exposure assessment, with two exceptions. The aerobic aquatic metabolism data were waived in 1993 when aquatic uses were removed from the labels (DP barcode 186638+); however, this study is currently requ ested in order to describe the fate of thiodicarb in surface water bodies down gradient from terrestrial use si tes. Submission of an independent laboratory validation of the environmental chemistry method in soil is also necessary in order to evaluate
the submitted terrestrial field dissipation studies. Although not necessary for exposure assessment, submission of an environmental ch emistry method in water and an associated independent laboratory validation is also re quested in order to support enforcement and monitoring purposes at the federal, state, and local levels. Draft Data Call-In (DCI) tables for these data are provided in APPENDIX C

.

Table 7.1 identifies studies by MRID that offer data for each guideline requirement, as well as study classifications and whether or not furthe r data are needed in order to support risk assessment ( i.e. , whether there is a data ga p). It is notable that ma ny studies were submitted in the 1970s, prior to the publication of FIFRA GLP st andards. Most of these studies are expected
to be deficient relative to cu rrent standards and to not provide useful information for risk assessment. Therefore, reviews of these studies were not finalized where data requirements were met by other acceptable data. If a formal review is available for a study conducted prior to GLP standards, the study classification is provided.

### TABLE 7.1. Environmental Fate Data Requirement Table for Thiodicarb.

OPPTS
Guideline Data Requirement Submitted
Studies (MRID) Classification Data Gap? Comments

44300 (pre-GLP) A 835.2120 Hydrolysis

42342601 (same as 42142901) Acceptable No.
--

44 301 (pre-GLP) A 835.2240 Aqueous photolysis

41250008 Acceptable No. MRID 41250008 is acceptable with additional data submitted to the Agency in a letter dated Feb. 6, 1992 and
reviewed under DP barcode 175388.

44308 (pre-GLP) A 835.2410 Soil photolysis

43463401 Acceptable No.
--

44307 (pre-GLP) A 835.4100 Aerobic soil
metabolism 42142601 Acceptable No.
--

835.4200 Anaerobic soil
metabolism 44307 (pre-GLP) A No. Additional data are not expected to alter
risk conclusions.

835.4300 Aerobic aquatic
metabolism (none)
-- Yes. The data requirement was waived in 1993 because aquatic uses were deleted from the labels (DP barcode 186638+). The data are currently requested in order to support assessment of the terrestrial uses.

835.4400 Anaerobic aquatic
metabolism 42142602 Acceptable No.
--

44302 (pre-GLP) A

44306 (pre-GLP) A 835.1230
835.1240 Adsorption/ desorption and leaching 41998501 Acceptable No.
--

835.1410 Laboratory volatility 43222901 Acceptable No.
--

44306 (pre-GLP; upgradeable) A

44312 (pre-GLP) A

40643001 Supplemental Terrestrial field dissipation

42203901 Upgradeable 835.6100

Analytical method
in soil 44082 Upgradeable Yes. The submitted analytical method in soil has not been independently validated. The submitted terrestrial field dissipation studies are not acceptable without independent validation of the analytical
method in soil.

835.6200 Analytical method
in water (none)
-- Yes. An independently validated analytical method in water is requested.

44304 (pre-GLP) A

44309 (pre-GLP; upgradeable) A

44310 (pre-GLP) A

139426 (pre-GLP; unacceptable) A 850.1730 Fish
bioconcentration

42834002 Acceptable No.
--

A. “Pre-GLP” means that the study was conducted prior to FIFRA GLP standards and is not expected to provide useful information. If the data have been reviewed, the classification is added.



### -40 of 83-

### 7.8.2. Effects Data for Thiodicarb

Although many submissions have been made to pr ovide data on the effects of thiodicarb to aquatic and terrestrial organisms, data gaps still exist ( Tables 7.2-7.4 ). Data gaps include the following: avian acute oral t oxicity, early-life stage estuar ine/marine fish toxicity, estuarine/marine invertebrate life-cycle, terrestr ial plant, and vascular aquatic plant toxicity studies. These data gaps are discussed below.

TABLE 7.2. Available Ecologi cal Effects Data for Terrestrial Animals Exposed to Thiodicarb and Remaining Data Gaps.

Guideline Description MRID/
Accession Classification Data Gap? Comments

850.2100 Avian oral t oxicity 46478 Acceptable Yes *

46479 Acceptable 850.2200 Avian dietary toxicity

46480 Acceptable No

43313003 Acceptable No 850.2300 Avian reproduction

43313004 Acceptable No

850.3020 Honeybee acute contact toxicity 42528501 Acceptable No *Avian acute oral toxicity data
are not available for passerines, which are required
under the new 40 CFR Part 158. Therefore, this is identified as a data gap.



### -41 of 83-

### TABLE 7.3. Available Ecological Effects Data for Aquatic Animals Exposed to Thiodicarb and Remaining Data Gaps.

Guideline Description MRID/
Accession Classification Data Gap? comments

41605502 Acceptable

00044273 Acceptable 850.1075 Freshwater fish – Acute toxicity

41605501 Acceptable No

42738501 Acceptable 850.1075 Saltwater fish – Acute toxicity 41891005 Acceptable No

00100688 Supplemental

00044276 Acceptable

41605503 Acceptable 850.1010 Freshwater
invertebrates – Acute toxicity

43052801 Acceptable No

42342501 Supplemental

42917301 Acceptable

42834001 Supplemental

41891006 Supplemental

42738504 Acceptable

42738503 Acceptable

41891007 Acceptable

00044277 Supplemental 850.1025
850.1035 Saltwater invertebrates

– Acute toxicity

00044278 Supplemental No

850.1300 Freshwater
invertebrate – life cycle test 00100688 Acceptable No

850.1350 Saltwater invertebrates

– life cycle test None Not applicable Yes *

850.1400 Freshwater fish – early life stage test 44484101 Supplemental No

850.1400 Saltwater fish – early life stage test None Not applicable Yes * *Since the LC 50 values for the
most sensitive
estuarine/marine fish and invertebrate species tested are < 1 mg/L, an estuarine/marine invertebrate life cycle test and an estuarine/marine fish early life stage test are required
under the new 40 CFR Part 158. Therefore, these are identified as a data gaps.



### -42 of 83-

### TABLE 7.4. Available Ecologica l Effects Data for Plants Exposed to Thiodicarb and Remaining Data Gaps.

Guideline Description MRID Classification Data Gap? comments

850.4100 Terrestrial Plant toxicity: Tier I seedling

emergence None Not applicable Yes*

850.4225 Terrestrial Plant toxicity: Tier II seedling

emergence None Not applicable No**

850.4150 Terrestrial Plant toxicity: Tier I vegetative vigor None Not applicable Yes*

850.4250 Terrestrial Plant toxicity: Tier II vegetative vigor None Not applicable No**

850.5400 Aquatic Plant Growth: algae 42324801 Acceptable No

850.4400 Aquatic Plant Growth: vascular plants None Not applicable Yes * * Terrestrial plant toxicity data are required but are not
available for thi odicarb. Tier I vegetative vigor and seedling emergence studies are required. Additionally, toxicity data for vascular aquatic plants, which are required, are not currently
available.

Therefore, these studies are identified as a data gaps.

** Tier II studies may be required depending on the
results of the Tier I terrestrial plant studies.



### Avian Acute Oral Toxicity

Acceptable acute avian oral toxi city data were submitted for e xposures of bobwhite quail to thiodicarb; however, data are not available for passerines, wh ich are required under the new 40 CFR Part 158 (Oct. 26, 2007) data requirement s for conventional pesticides (72 FR 60934;

USEPA 2007 d ). The new Part 158 data requirements specify that acute avian oral toxicity data
be submitted for either a mallard duck or bobwhite quail and a passerine species. Therefore, an avian oral toxicity test (OPPTS Guideline 850.2100) is required for passerine birds, as specified in 40 CFR Part 158 (Oct. 26, 2007). EFED reco mmends that SRRD request submission of a passerine study protocol for review by the Agency pr ior to initiation of this study. If oral acute toxicity data are not submitted for passerines, EFED will assume acute risk for passerine species.

Chronic Toxicity Studies with Est uarine/Marine Fish and Invertebrates

Chronic toxicity data for thiodicar b are not available for estuarine/marine fish or invertebrates.
Since the LC 50 

### values for the most sensitive estuarine/marine fish and invertebrate species tested are < 1 mg/L, these data are required under the new 40 CFR Part 158 (Oct. 26, 2007). Although thiodicarb is expected to rapi dly degrade to methomyl in many aquatic environments, it is expected to be moderately persistent in lo w pH waters. Therefore, chronic exposure to estuarine/marine animals from registered uses of thiodicarb is possible. Therefore, an
estuarine/marine invertebrate life cycle toxicity test (O PPTS Guideline 850.1350) and an estuarine/marine fish early life stage toxicity test (OPPTS Guid eline 850.1400) are required. In
the absence of chronic thiodicarb toxicity data for estuarine/ma rine invertebrates and fish, the Agency will assume risks to estuarine/marine animals from the use of thiodicarb.

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### Terrestrial Plant and Vascul ar Aquatic Plant Studies

Aquatic (both vascular and non-vascular species) and terrestrial plant toxicity studies and associated risk analysis of plants are required for registration of pestic ides with outdoor uses (CFR Part 158). For terrestrial plants, Tier II studies (OPPTS Guidelines 850.4225 and 850.4250) are required when potential concerns are triggered ( i.e ., when there is some indication that there may be significant toxicity to plants). These indicators may be an herbicidal mode of action or statements on the label indicating toxi city to plants. Some thiodicarb labels ( i.e ., EPA Registration No. 264-379, 264-378, and 264-530) do contain the following statement:

“Horticultural varieties of many plants differ significantly in sensitivity to pesticides. Before making applications to plants not listed, it is recommended that a small portion of the crop be treated to determine its tolerance to this product. Plants stressed from heat, moisture or other fact ors are usually more sensitive to sprays. Phytotoxic reactions can be minimized by sp raying when stress is minimal such as early mornings or late evenings.”

The Agency confirmed with the registrant that th is label statement is included on the label as a general precaution and is not th e result of known phytotoxi c effects. Therefore, the requirement for Tier II plant studies for thiodicarb is not tr iggered by this label statement. Tier I seedling emergence and vegetative vigor studies (OPPTS Guidelines 850.4100 and 850.4150) are, however, required. If toxicity data for terrestrial plants are not submitted for thiodicarb, EFED will assume risk for terrestrial plants.

Additionally, toxicity data for vascular aquatic plants (Tier I, OPPTS Guideline 850.4400) are not currently available for thiodicarb. If toxi city data for vascular aquatic plants are not submitted for thiodicarb, EFED will assume risk for vascular aquatic plants.

7.8.3. Effects Data for Methomyl

Although many submissions have been made to pr ovide data on the eff ects of methomyl to aquatic and terrestrial organisms, data gaps still exist ( Tables 7.5-7.7 ). Data gaps include the following: avian acute oral toxi city, avian reproduction, terrestr ial plant, and aquatic plant toxicity studies. These data gaps are discussed below.

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### TABLE 7.5. Available Ecologi cal Effects Data for Terrestrial Animals Exposed to Methomyl and Remaining Data Gaps.

Guideline Description MRID/
Accession Classification Data Gap? Comments

850.2100 Avian oral toxi city 00161886 Acceptable Yes *

45299802 Acceptable

45299801 Acceptable 850.2200 Avian dietary toxicity

00022923 Acceptable No

850.2300 Avian reproduc tion 41898602 Acceptable Yes**

850.3020 Honeybee acute contact toxicity 45093001 Acceptable No *Avian acute oral toxicity data
are not available for passerines, which are required
under the new 40 CFR Part 158. Therefore, this is identified as a data gap.

** Data are required on waterfowl and upland game species. Currently acceptable data are only available for upland game species



### . Based on available data, mallard ducks appear more sensitive to methomyl than to thiodicarb
and more sensitive than bobwhite quail to methomyl on a chronic exposure basis. Therefore, chronic toxicity
data for mallard ducks and methomyl could result in a lower avian chronic toxicity endpoint and this is, thus, identified as a data gap.



### -45 of 83-

### TABLE 7.6. Available Ecologica l Effects Data for Aquatic Animals Exposed to Methomyl and Remaining Data Gaps.

Guideline Description MRID/
Accession Classification Data Gap? comments

850.1075 Freshwater fish – Acute toxicity 40098001 Supplemental No

850.1075 Saltwater fish – Acute toxicity 41441202 Acceptable No

40098001 Supplemental

00019977 Acceptable 850.1010 Freshwater
invertebrates – Acute toxicity 40094602 Acceptable No

00009134 Acceptable

41441201 Acceptable 850.1025
850.1035 Saltwater invertebrates

– Acute toxicity 42074601 Acceptable No

850.1300 Freshwater
invertebrate – life cycle test 00131254 Acceptable No

850.1350 Saltwater invertebrates

– life cycle test 45013203 Supplemental No

850.1400 Freshwater fish – early life stage test 00131255 Acceptable No

850.1500 Fish life cycle te st 43072101 Acceptable No

850.1400 Saltwater fish – early life stage test 45013202 Acceptable No None



### -46 of 83-

### TABLE 7.7. Available Ecologi cal Effects Data for Plants Exposed to Methomyl and Remaining Data Gaps.

Guideline Description MRID Classification Data Gap? comments

850.4100 Terrestrial Plant toxicity: Tier I seedling

emergence None Not applicable Yes*

850.4100 Terrestrial Plant toxicity: Tier 2 seedling

emergence None Not applicable No

850.4150 Terrestrial Plant toxicity: Tier I vegetative vigor None Not applicable Yes*

850.4150 Terrestrial Plant toxicity: Tier 2 vegetative vigor None Not applicable No

850.5400 Aquatic Plant Growth: algae None Not applicable Yes**

850.4400 Aquatic Plant Growth: vascular plants None Not applicable Yes** *Although data from Tier I terrestrial plant studies (unless there are known phytotoxic concerns) are required, methomyl is not expected to pose a risk to terrestrial plants. Therefore, we do not recommend requesting these data for methomyl at this time.

** Toxicity data for vascular and non-vascular aquatic plants, which are required, are not currently available. Therefore, these are identified as data gaps.



### Avian Acute Oral and Reproduction Toxicity

Acceptable acute avian oral toxi city data were submitted for e xposures of bobwhite quail and mallard duck to methomyl; however, data are not available for passerines, which are required under the new 40 CFR Part 158 (Oct. 26, 2007) data requirements for conventional pesticides (72 FR 60934; USEPA 2007 d ). The new Part 158 data requirements specify that acute avian oral toxicity data be submitted for either a mallard duck or bobwhite quail and a passerine species. Therefore, an avian oral toxicity test (OPPTS Guideline 850.2100) is required for passerine birds, as specified in 40 CFR Part 158 (Oct. 26, 2007). EFED recommends that SRRD request submission of a passerine study protocol for review by the Agency prior to initiation of this study. If oral acute toxicity data are not submitted for passerines, EFED will assume acute risk for passerine species.

Under the 40 CFR Part 158 (Oct. 26, 2007) data requirements for conventional pesticides avian reproduction data are required on waterfow l and upland game species (OPPTS 850.2300). Currently acceptable data for methomyl are only available for upland game species. The chronic toxicity data available for bi rds indicate that mallard ducks (NOAEC = 500 mg a.i./kg-diet; LOAEC = 1,000 mg a.i./kg-diet, based on a reduc tion in number of eggs laid) (MRID 43313004)
are more sensitive to thiodicarb than bobwhite quail (no reproductive effects seen at any concentration tested; highest concentration tested = 1,000 mg a.i./kg-diet) (MRID 43313003). Additionally, bobwhite quail appear more sensitive to methomyl than to thiodicarb based on chronic exposure (for methomyl , NOAEC = 150 mg a.i./kg-diet ; LOAEC = 500 mg a.i./kg-diet, based on fewer eggs laid and eggs set) (MRID 41898602). Therefore, based on available data, it is reasonable to assume that mallard ducks may be more sensitive to methomyl than to thiodicarb and that they may be more sensitive than bobw hite quail to methomyl on a chronic exposure

-47 of 83-

### basis. Therefore, since additional avian reprodu ction data for methomyl could result in a lower avian reproductive endpoint, and, thus, could alter risk conclusions for birds from the use of thiodicarb, we recommend requesting these data for methomyl at this time.

Terrestrial Plant Studies

Terrestrial plant toxicity studi es and associated risk analys is of plants are required for registration of pesticides with outdoor uses (CFR Part 158). Fo r terrestrial plants, Tier II studies are required when potential concerns are triggered ( i.e ., when there is some indication that there may be significant toxicity to plants). These indi cators may be an herbicidal mode of action or statements on the label indicating toxicity to plants. None of these indicators are present for methomyl. Furthermore, methomyl is registered for use on a variety of plants, it has been registered since 1968, and there ar e no terrestrial plant incident s reported for methomyl.

Additionally, several efficacy studies that were conducted to test the effects of methomyl on a variety of invertebrate target and non-target pests also supplied information on effects to plants after methomyl applications. None of the studies showed any adverse effects to terrestrial plants at the highest treatment levels tested (most of which were abov e the maximum allowable single application rate for methomyl) (see Section 4.2 ). Therefore, the availabl e data based on a lack of plant incidents and a lack of eff ects to plants in efficacy studies suggest that methomyl will not adversely affect terrestrial plants. We do not recommend requesting these data for methomyl at
this time.

Vascular and Non-vascular Aquatic Plant Studies

Aquatic plant toxicity studies and associated risk analysis of plants ar e required for registration of pesticides with outdoo r uses (CFR Part 158). Toxicity data for both vascular and non-vascular aquatic plants (Tier I, OPPTS Guidelin es 850.4400 and 850.5400) are required but are not available for methomyl. Although, there is evidence to suggest th at methomyl is not toxic to terrestrial plants (see above), such data are not available for aquatic plants. Therefore, we recommend requesting toxicity da ta on vascular and non- vascular aquatic plants for methomyl. If toxicity data for aquatic plants are not s ubmitted for methomyl, EFED will assume risk for aquatic plants.

8. References

Food and Agriculture Organization of the United Nations (FAO). 2000. Appendix 2. Parameters of pesticides that influence processes in the soil. In FAO Information Division Editorial Group (Ed.), Pesticide Disposal Series 8. Assessing Soil Contamination: A Reference Manual. Rome: Food & Agriculture Organization of
the United Nations. http://www.fao.org/DOCREP/003/X2570E/X2570E06.htm

Fletcher, J.S., J.E. Nellessen, and T.G. Pfleeger. 1994. Literature review and evaluation of the EPA food-chain (Kenaga) nomogram, an inst rument for estimating pesticide residues on plants. Environ. Tox. Chem.

13:1383-1391.

Hoerger, F. and E. E. Kenaga. 1972. Pesticide Residues on Plants: Correlation of Representative Data as a Basis for Estimation of their Magnitude in the Environment. In F. Coulston and F. Korte, eds., Environmental



### -48 of 83-Quality and Safety: Chemistry, Toxicology, and Technology, Georg Thieme Publ., Stuttgart, West Germany, pp. 9-28.

U.S.Department of Agriculture (USDA). 2007. National Ag ricultural Statistics Service. United States Department of Agriculture. http://www.nass.usda.gov/

U.S. Environmental Protection Agency (USEPA). 1997 a . Jones, R. D. Tier 1 Estimated Environmental Concentrations for Thiodicarb. DP barcode not reported. U.S. Environmental Protection Agency, Office of Prevention, Pesticides, and Toxic Substances, Speci al Review Section. Memorandum to Reregistration Section. May 7, 1997.

USEPA. 1997 b . Thurman, N. Tier 2 Estimated Environmental Concentrations for Thiodicarb and Methomyl. DP barcode not reported. U.S. Environmental Protection Agency, Office of Prevention, Pesticides, and Toxic Substances, Environmental Fate and Effects Division. Memorandum to Health Effects Division. May 29,

1997.

USEPA. 1998. Guidelines for Ecological Risk Assessment. Risk Assessment Forum, Office of Research and Development, Washington, D.C. EPA/630/R-95/002F. April 1998. http://cfpub.epa.gov/ncea/cfm/ recordisplay.cfm?deid=30759

USEPA. 1998. Registration Eligibility Decision (RED): Thiodicarb. U.S. Environmental Protection Agency, Office of Prevention, Pesticides, and Toxic Substan ces, Washington, DC. EPA 738-R-98-022. December,

1998. http://www.epa.gov/oppsrrd1/REDs/2675red.pdf

USEPA. 2002. Guidance for Selecting Input Parameters in Modeling the Environmental Fate and Transport of Pesticides, Version II. US Environmental Protection Agency, Washington DC. Online at: http://www.epa.gov/oppefed1/models water/input_guidance2_28_02.htm.

USEPA. 2004. Overview of the Ecological Risk Assessment Process in the Office of Pesticide Programs. U.S. Environmental Protection Agency, Of fice of Prevention, Pesticides and Toxic Substances, Office of Pesticide Programs, Washington DC. January 23, 2004.

USEPA. 2006 a . Standardized Soil Mobility Classification Guid ance. U.S. Environmental Protection Agency, Office of Prevention, Pesticides and Toxic Substances , Office of Pesticide Programs, Environmental Fate and Effects Division, Memorandum. April 21, 2006.

USEPA. 2007 a . Young, D. Refined Methomyl Surface Water Dr inking Water Assessment with Time Series and Regional PCA. DP barcode 339492. U.S. Environmental Protection Agency, Office of Prevention, Pesticides, and Toxic Substances, Environmental Fate and Effects Division. Memorandum to Health Effects Division and Special Review and Reregistration Division. May 16, 2007.

USEPA. 2007 b . Revised N-Methyl Carbamate Cumulative Risk Assessment. U.S. Environmental Protection Agency, Office of Pesticide Programs. Sep., 24, 2007.

USEPA. 2007 c . Ecological Incident Information System. http://www.epa.gov/espp/consultation/ecoriskoverview.pdf

USEPA. 2007 d . 40 CFR Part 158. Pesticides; Data Requiremen ts for Conventional Chemicals: Final Rule. 72 FR 60934. October 26, 2007.

USEPA. 2007 e . ECOTOXicology Database. Office of Res earch and Development National Health and Environmental Effects Research Laboratory’s (NHEERL’s) Mid-Continent Ecology Division (MED). http://cfpub.epa.gov/ecotox/

.

USEPA. 2009. Orrick, G. Refined Tier II Drinking Water Exposure Assessment for the Section 3 New Use Registration of Oxamyl on Sugar Beets. DP Barcode 351367. U.S. Environmental Protection Agency,



### -49 of 83-Office of Prevention, Pesticides and Toxic Substa nces, Environmental Fate and Effects Division. Memorandum to the Registration Division and Health Effects Division. Initial edition: Mar. 4, 2009; replaced: Mar. 25, 2009; replaced: May 11, 2009.

U.S. Fish and Wildlife Service (USFWS) and National Ma rine Fisheries Service (NMFS). 1998. Endangered Species Consultation Handbook: Procedures for Conducting Consultation and Conference Activities Under Section 7 of the Endangered Species Act. Final Draft. March 1998.

Worthing, C. R and R. J. Hance, editors. 1991. The Pesticide Manual: A World Compendium (9th edition). British Crop Protection Council, Surrey, UK. June, 1991.

SUBMITTED ENVIRONM ENTAL FATE STUDIES (Thiodicarb):

MRID:

41250004 Kurtz, A.; Asbury, C. (1976) Fundamental Studies of Structure-ac tivity in Pesticides...: Project No. 111A28: File No. 22018. Unpublished study prepared by Union Carbide Corp. 72 p.

41250008 Feung, C.; Blanton, C. (1987) Larvin: Photolysis of Thiodicarb in Aqueous Buffered Solutions: Project No. 804R14: File No. 40254. Unpublished study prepared by Rhone-Poulenc Ag Co. 30 p.

41482002 Seymour, R. (1988) Thiodicarb Solubility in Water: Lab Project No: 804C10: 40357. Unpublished study prepared by Rhone-Poulenc Ag Co. 9 p.

41998501 Cranor, W. (1991) Soil Adsorption/Desorption with 14 C-Thiodicarb: Lab Pr oject Number: 37453. Unpublished study prepared by ABC Laboratories. 350 p.

42142601 Feung, C.; Weisbach, P. (1991) Aerobic Soil Metabolism of Thiodicarb: Lab Project Number: EC-91- 142. Unpublished study prepared by Rhone-Poulenc Ag Co. 74 p.

42142602 Feung, C.; Weisbach, P. (1991) Metabolism of 14 C-Thiodicarb Under Anaerobic Aquatic Conditions: Lab Project Number: EC-91-155. Unpublished study prepared by Rhone-Poulenc Ag Co. 72 p.

42203901 Norris, F. (1991) A Terrestrial Field Soil Di ssipation Study with Thiodicarb: Lab Project Number: 41036: EC-89-036. Unpublished study prepared by Rhone-Poulenc Ag Co., Colorado Analytical Research and Devel. Corp. and A & L Eastern Agricultural Labs., Inc. 245 p.

42342601 Feung, C.; Weisbach, P. (1991) Hydrolysis of Thiodicarb in Aqueous Buffer Solutions: Amended Report: Lab Project Number: EC-91-143. Unpublished study prepared by Rhone-Poulenc Ag Co. 42

p.

42834002 Blasberg, J.; Hicks, S.; Stuerman, L. (1993) Uptake, Depuration, Bioconcentration, and Metabolism of ( 14 C)-Thiodicarb by Bluegill Sunfish (Lepomis macrochirus): Final Report: Lab Project Number: 40046. Unpublished study prepared by ABC Labs., Inc. 164 p.

43222901 Flynn, J. (1994) Laboratory Volatility of Thi odicarb from Soil: Lab Project Number: 41352: EC-93- 249. Unpublished study prepared by ABC Laboratories, Inc. 75 p.

43463401 Das, Y. (1989) Photodegradation of (Acetyl-1-( 14 C)) Thiodicarb on Soil un der Artificial Sunlight: Lab Project Number: 89120. Unpublished study prepared by Innovative Scientific Services, Inc. 97 p.

SUBMITTED ENVIRONM ENTAL FATE STUDIES (Methomyl):

MRID: 8568 Harvey, J., Jr. 1977. Degradation of 14C-Methomyl in Flanagan Silt Loam in Biometer Flasks. Unpublished study received Feb 28, 1977 under 352 -342; prepared in coop eration with Univ. of Delaware, Soil Testing Laboratory, submitted by E. I. du Pont de Nemours & Co., Wilmington, Del.;

CDL:096026-B.



### -50 of 83-8844 Harvey, J. 1964? Exposure of S-Methyl N-(methylcarbamoyl)oxy|-thioacetimidate in Sunlight, Water,
and Soil. Unpublished study received Dec 28, 1968 unde r 8F0671; submitted by E.I. du Pont de Nemours & Co., Inc., Wilmington, Del.; CDL:091179-V.

9324 Harvey, J., Jr. and H. L. Pease. 1971? Decomposition of Methomyl in Soil. Unpublished study received May 5, 1977 under 352-342; submitted by E.I. du Pont de Nemours & Co., Wilmington, Del.;

CDL:229711-D.

9326 E.I. du Pont de Nemours & Company. 1971. Methomyl Decomposition in Muck Soil--A Field Study. Unpublished study received May 5, 1977 under 352-342 ; CDL:229711-F.

44306 Khasawinah, A.M. and G. C. Holsing. 1976. UC 51762 Pesticide: Mobility on Soil Thin-Layer Chromatograms: File No. 22754. Unpublished study received Sep 10, 1980 under 264-341; submitted by Union Carbide Agricultural Products Co., Ambler, Pa.; CDL: 099602-J.

131249 Friedman, P. 19?? Hydrolysis of 1-14C-methomyl: Document No. AMR- 109-83. Unpublished study received Oct 3, 1983 under 352-366; submitted by E.I. du Pont de Nemours & Co ., Inc., Wilmington, DE; CDL:251424-B.

161884 Priester, T. 19?? Batch Equilibrium (Adsorption/desorption) and Soil Thin-layer Chromatography Studies with Methomyl: Document No. AMR-174-84. Unpublished.

161885 Harvey, J. 19?? Photolysis of [1-Carbon 14] Methomyl: Document No. AMR-121-83. Unpublished study prepared by E. I. du Pont de Nemours and Co., Inc. 14 p.

157991 Collins, R., and F. Kenny. 1986. Octanol-Water Partition Coefficient of Nudrin Insecticide. Code 5-8- 0-0. RIR-25-009-86. Unpublished study prepared by Shell Development Co

163745 Swanson, M. 1986. Photodegradation of [1-Carbon 14]Methomyl on Soil: Document No. AMR-611-
86. Unpublished study prepared by E.I. du Pont de Nemours and Co., Inc. 25 p.

41209701 Barefoot, A. C. and L. A. Cooke. 1989. Vapor Pressure of Methomyl. Laboratory Project ID AMR1268-88. Submitted by E. I. Du Pont de Nemours & Company. Wilmington, DE.

41402101 Hoffman, R. 1988. Determination of the Water Solubility of Methomyl, X1179: Lab Project Number: X1179.B. Unpublished study prepared by E. I. du Pont de Nemours and Co. 12 p.

41623901 Kennedy, S. 1989. Field Soil Dissipation of Lannate L Insecticide: Lab Project Number:
ML88/0078/DUP. Unpublished study prepared by Morse laboratories, Inc. 84 p.

41623902 Kennedy, S. 1989. Field Soil Dissipation of Lannate L insecticide: Lab Project Number:
ML88/0078/DUP. Unpublished study prepared by Morse Laboratories, Inc. 41 p.

43217901 Malik, N. and T. Zwick. 1990. Aerobic Metabolism of (1-carbon 14) Methomyl in Madera, California Soil: Final Report: Lab Project Number: SC890027: AMR/1543/89. Unpublished study prepared by Battelle Memorial Institute. 40 p.

43217902 Malik, N., and T. Zwick, 1990. Anaerobic Metabolism of (1-carbon 14) Methomyl in Madera, California Soil: Final Report: Lab Project Number: SC890028: AMR/1544/89. Unpublished study prepared by Battelle Memorial Institute. 45 p.

43325401 Mayo, B. 1994. Degradability and Fate of (1-(c arbon 14))Methomyl in Water/Sediment Systems: Lab Project Number: DPT/295/932544: AMR/2590/92. Unpublished study prepared by Huntingdon Research Centre, Ltd. 112 p.



### -51 of 83-43568301 Russell, Mark., Andrew M. Hiscock, and Jame s M. DeMartinis and Janet C. Ruhl. 1995. A SmallScale Prospective Groundwater Mo nitoring Study for Methomyl: Final Report: Lab Project Number: AMR/2311/92: ML92/0335/DUP: 423/04. Unpublished study prepared by Blasland, Bouck & Lee, Inc. and other facilities. Submitted by E. I. du Pont de Nemours and Company. 619 p.

43599801 Russell, M. and L. Bergstrom. 1995. Modeling of the Results from a Small-Scale Prospective Groundwater Study for Methomyl: Lab Project Number: 423.13: AMR 3405-95. Unpublished study prepared by Blasland, Bouck & Lee, Inc. and DuPont Agricultural Products. 136 p.

43708801 Naylor, M., D. Palmer, and H. Krueger. 1994. An Aquatic Residue Monitoring Study of Methomyl in and Around Apple Orchards in Michigan: Lab Project Numbers: 112-292: AMR 2278-92: 91-4-3722. Unpublished study prepared by DuPont Agricultural Products; Morse Labs.; and Wildlife Int'l. Ltd. 555 p.

43708802 Leva, S. 1995 . An Aquatic Residue Monitoring Study of Lannate L Insecticide in and Around Sweet
Corn Fields in Illinois. Unpublished study prepared by DuPont Agricultural Products; Morse Labs.; and Wildlife Int'l. Ltd. 584 p.

43708803 Armbrust, K. 1995. An Aquatic Residue Monitoring Study of Methomyl in and Around Cucurbit Fields in California: Lab Project Numbers: AMR 2469-92: 92195: ML93-0445-DUP. Unpublished study prepared by DuPont Agricultural Products; Morse Labs.; and ABC Labs., Inc. 432 p.

43708804 Leva, S. and S. McKelvey. 1995. An Aquatic Residue Monitoring Study of Methomyl in and Around Lettuce Fields in Florida: Lab Project Numbers: AMR 2512-92: ML93-0423-DUP: 112-333. Unpublished study prepared by DuPont Agricultural Pr oducts; Morse Labs.; and Wildlife Int'l, Inc. 475

p.

43744402 Samel, A. 1995. An Evaluation of the Effects and Fate of Methomyl Insecticide Exposure in Outdoor Microcosms: Lab Project Number: AMR 2389-92: ML93-0445-DUP: 112-299. Unpublished study prepared by Morse Labs and Wildlife International, Ltd. 877 p.

SUBMITTED EFFECTS STUDIES (Thiodicarb):

MRID:

44277 Vilkas, A.G.; Seminara, J. (1980) The Acute Toxicity of Larvin Thiodicarb Insecticide Fiddler Crab,~Uca pugilator~?: UCCES Pr oject No. 11504-25-03. (Unpublishe d study received Sep 10, 1980 under 264-341; submitted by Union Carbide Agricultural Products Co., Ambler, Pa.; CDL:099603-K)

44278 Vilkas, A.G.; Seminara, J. (1980) The Acute Toxi city of Larvin Thiodicarb Insecticide to the Grass Shrimp,~Palaemonetes~ ?~pugio~?: UCCES Project No. 11504-25-04. (Un published study received Sep 10, 1980 under 264-341; submitted by Union Carbide Agricultural Products Co., Ambler, Pa.; CDL:099603-L)

46478 Fink, R.; Beavers, J.B.; Brown, R.; et al. (1978) Final Report: Acute Oral LD50--Bobwhite Quail: Project No. 142-117. (Unpub- lished study received Sep 9, 1980 under 264-343; prepar ed by Wildlife International, Ltd. and Washington College, submitted by Union Carbide Agricultural Products Co., Inc., Ambler, Pa.; CDL:243243-C)

44270 Fink, R.; Beavers, J.B.; Grim es, J.; et al. (1978) Final Repor t: Eight-Day Dietary LC50--Mallard Duck: Project No. 142-116. (Un- pu blished study received Sep 10, 19 80 under 264-341; prepared by Wildlife International, Ltd., submitted by Union Carbide Agri- cultural Products Co., Indianapolis, Ind.; CDL:099603-C)

44271 Fink, R.; Beavers, J.B.; Grim es, J.; et al. (1978) Final Report: Eight-Day Dietary LC50--Bobwhite Quail: Project No. 142-115. (Unpub lished study received Sep 10, 1980 under 264-341; prepared by Wildlife International, Ltd., submitted by Union Carbide Agricultural Products Co., Ambler, Pa.;



### -52 of 83-CDL:099693-D)

46479 Fink, R.; Beavers, J.B.; Brown, R.; et al. (1978) Final Report: Eight-Day Dietary LC50--Mallard Duck: Project No. 142-116. (Unpublished study received Sep 9, 1980 under 264-343; prepared by Wildlife International, Ltd. and Washington College, submit- ted by Union Carbide Agricultural Products Co., Inc., Ambler, Pa.; CDL:243243-D)

46480 Fink, R.; Beavers, J.B.; Brown, R.; et al. (1978) Final Report: Eight-Day Dietary LC50--Bobwhite Quail: Project No. 142-115. (Unpub lished study received Sep 9, 1980 under 264-343; prepared by Wildlife International, Ltd. and Washington College, submit- ted by Union Carbide Agricultural Products Co., Inc., Ambler, Pa.; CDL:243243-E)

43313003 Pedersen, C. (1994) Thiodicarb Technical: Toxicity and Reproduction Study in Bobwhite Quail: Lab Project Number: 108/021/07: HWI/6375/108B. Unpublished study prepared by Bio- Life Associates, Ltd. 421 p.

43313004 Pedersen, C.; Solatycki, A. (1994) Thiodicarb Technical: Toxicity and Reproduction Study in Mallard Ducks: Lab Project Number: 108/022/08: HWI/6375/108B. Unpublished study prepared by Bio-Life Associates, Ltd. 590 p.

41605501 Bowman, J. (1990) Acute Flow-through Toxicity of Thiodicarb to Blue gill (Lepomis macrochirus): Final Report: Lab Project Number: 38365. Unpublished study prepared by Analytical Bio-chemistry Laboratories, Inc. 213 p.

41605502 Bowman, J. (1990) Acute Flow-through Toxicity of Thiodicarb to Rain bow Trout (Oncorhynchusmykiss): Final Report: Lab Project No: 38366. Unpublished study prepared by Analytical Biochemistry Laboratories, Inc. 207 p.

41605503 Burgess, D. (1990) Acute Flow-through Toxicity of Thiodicarb to Daphnia magna: Final Report: Lab Project Number: 38367. Unpub- lished study prepared by Analytical Bio-chemis try Laboratories, Inc. 89 p.

43052801 Blakemore, G.; Stratton, J.; Bussard, J. (1992) Acute Toxicity of LARVIN 3.2 (Thiodicarb) to Daphnia magna Under Flow-through Conditions: Lab Project Number: 39111. Unpublished study prepared by ABC Labs, Inc. 583 p.

41891005 Machado, M. (1991) Thiodicarb Technical--Acute Toxicity to Sheeps- head Minnow (Cyprino-don variegatus) under Flow-through Condi- tions: Lab Project Number: 91-4-3731: 10566. 1289. 6155. 505. Unpublished study prepared by Springborn Labs, Inc. 67 p.

41891006 Dionne, E. (1991) Thiodicarb Technical--Acute Toxicity to Eastern Oyster (Crassostrea virginica) under Flow-through Conditions: Final Report: Lab Project Number: 91-4-3738: 10566.1289.6154.504 Unpublished study prepared by Springborn Labs, Inc. 65 p.

41891007 Sousa, J. (1991) Thiodicarb Technical--Acute Toxicity to Mysid Shrimp (Mysidopsis bahia) under Flow-through Conditions: Final Report: Lab Project Number: 90-5-3342: 10566. 1289. 6153. 515. Unpublished study prepared by Springborn Labs, Inc. 53 p.

42342501 Dionne, E. (1991) Larvin 3.2--Acute Toxicity to Eastern Oyster (Crassostrea virginica) Under Flowthrough Conditions: Final Report: Lab Project Number: 91-3-3711: 10566.1090.6173.504. Unpublished study prepared by Springborn Labs, Inc. 65 p.

42738501 Sousa, J. (1992) Larvin 3.2--Acute Toxicity to Sheepshead Minnow (Cyprinodon variegatus) under Flow-Through Conditions: Final Report: Lab Project Number: 91-8-3897: 10566.0190.6174.505. Unpublished study prepared by Springborn Labs, Inc. 62 p.

42738502 Sousa, J. (1992) Larvin 80DF--Acute Toxicity to Sheepshead Minnow (Cyprinodon variegatus) under Flow-Through Conditions. Final Report: Lab Project Number: 91-9-3925: 10566.0190.6171.505. Unpublished study prepared by Springborn Labs, Inc. 64 p.



### -53 of 83-42738503 Sousa, J. (1992) Larvin 3.2--Acute Toxicity to Mysid Shrimp (Mysidopsis bahia) under Flow-Through Conditions: Final Report: Lab Project Number: 91-1-3634: 10566.1090.6172.515. Unpublished study prepared by Springborn Labs, Inc. 62 p.

42738504 Sousa, J. (1992) Larvin 80DF--Acute Toxicity to Mysid Shrimp (Mysidopsis bahia) under FlowThrough Conditions: Final Report: Lab Project Number: 91-8-3896: 10566.1090.6169.515. Unpublished study prepared by Springborn Labs, Inc. 64 p.

42834001 Dionne, E. (1993) Larvin 80DF--Acute Toxicity to Eastern Oyster (Crassostrea virginica) under FlowThrough Conditions: Final Report: Lab Project Number: 91-9-3920: 10566.1090.6170.504. Unpublished study prepared by Springborn Labs., Inc. 64 p.

42917301 Dionne, E. (1993) Larvin 80DF-Acute Toxicity to Eastern Oyster (Crassos trea virginica) Under FlowThrough Conditions: Amended Final Report: Lab Project Number: 10566.1090.6170.504: 91-9-3920. Unpublished study prepared by Springborn Labs, Inc. 65 p.

44273 Vilkas, A.G.; Seminara, J. (1980) The Acute Toxic ity of Larvin Thiodicarb Insecticide to the Bluegill Sunfish,~Lepomis macro~?- ?~chirus~Rafinesque: UCCES Project No. 11504-25-07. (Unpub- lished study received Sep 10, 1980 under 264-341; subm itted by Union Carbide Ag ricultural Products Co., Ambler, Pa.; CDL: 099603-G)

44484101 Sousa, J. (1997) Thiodicarb Technical--Early Life-Stage Toxicity Test with Fathead Minnow (Pimephales promelas): Final Report: Lab Project Number: 97-1-6867: 10566.0796.6404.120. Unpublished study prepared by Springborn Laboratories, Inc. 85 p. (Relates to L0000176)

42324801 Oldersma, H.; Hanstviet, A. (1991) Effect of Thiodicarb on the Growth of the Alga Selenastrum Capricornutum: Lab Project Number: R 90/457. Unpublished study prepared by Rhone-Poulenc. 29 p.

42528501 Petto, R. (1992) Acute Contac t LD50 of Thiodicarb to Honey Bees (Apis mellifera L.) (Hymenoptera, Apidae): Lab Project Number: 305201. Unpublished study prepared by RCC Umweltchemie GmbH & Co. KG. 20 p.

44276 Vilkas, A.G.; Browne, A.M. (1980) The Acute Toxicity of Larvin (Thiodicarb, UC51762) to the Water Flea~Daphnia magna~Straus: UCCES Project No. 11504-25. (Unpublished study received Sep 10, 1980 under 264-341; submitted by Union Carbide Agricultural Products Co., Ambler, Pa.; CDL:099603-J)

44309 Kuc, W.J. (1979) 14C-UC 51762, Bluegill Sunfish Lepomis macrochirus Bioconcentration Study: UCES Project No. 11504-20. (Un published study received Sep 10, 1980 under 264-341; submitted by Union Carbide Agricultural Products Co., Ambler, Pa.; CDL:099602-M)

44310 Kuc, W.J.; Jones, C.N. (1979) 14C-UC 51762, Ch annel Catfish, Ictalurus punctatus (Rafinesque) Bioconcentration Study: UCES Project No. 11504-20. (Unpublished study including published data, received Sep 10, 1980 under 264-341; submitted by Un ion Carbide Agricultural Products Co., Ambler, Pa.; CDL:099602-N)

100688 Booth, G.; Carter, M.; Price, R.; et al. (1982) The Acute and Chronic Toxicities of Larvin to Daphnia Magna Using a Static Renewal System. Final rept. (Unpublished study received May 4, 1982 under 264-341; submitted by Union Carbide Agricultural Pr oducts Co., Inc., Ambler, PA; CDL:247397-A)

45565801 Nienstedt, K. (2001) Larvin SC 375: Dose Resp onse Toxicity Test with the Parasitic Wasp, Aphidius Rhopalosiphi (Hymenoptera: Braconidae): Final Report: Lab Project Number: 1067.007.670: 31570. Unpublished study prepared by Springborn Laboratories (Europe) AG. 27 p.



### -54 of 83-SUBMITTED EFFECTS STUDIES (Methomyl):

MRID: 9061 Schneider, P.W., Jr. (1976) 96-Hou r LCI50^ to Bluegill Sunfish: Ha skell Laboratory Report No. 710- 76. (Unpublished study received Jun 21, 1979 under 352-342 ; submitted by E.I. du Pont de Nemours & Co., Wilmington, Del.; CDL:238781-A)

9134 Sleight, B.H., III (1973) Bioassay Report Submitted to E.I. DuPont de Nemours & Company, Newark, Delaware: Acute Toxicity of H- 7946, MR-581 to Grass Shrimp (Palaemenetes vulgaris), Pink Shrimp (Penaeus duorarum) and Mud Crab (Neopanope texa na). (Unpublished study received May 6, 1976 under 352- 342; prepared by Bionomics, Inc., submitted by E.I. du Pont de Nemours & Co., Wilmington, Del.; CDL:224073-AI).

9230 Bentley, R. (1973) Acute Toxicity of H-8385 to Grass Shrimp (Palaemonetes vulgaris) and Fiddler Crab (Uca pugilator). (Unpublished study received May 5, 1977 under 352-342; prepared by Bionomics, Inc., submitted by E.I. du Pont de Nemours & Co., Wilmington, Del.; CDL:229718-A)

19977 Goodman, N.C. (1978) 48-Hour LC50^2I to~Daphnia magna~: Haskell Laboratory Report No. 165- 78. (Unpublished study received May 22, 1978 under 352-342; submitted by E.I. du Pont de Nemours & Co., Wilmington, Del.; CDL:233993-B)

22923 Hill, E.F.; Heath, R.G.; Spann, J.W.; et al . (1975) Lethal Dietary Toxicities of Environmental Pollutants to Birds: Special Scientific Report--Wild life No. 191. (U.S. Dept. of the Interior, Fish and Wildlife Service, Patuxent Wildlife Re search Center; unpublished report)

115198 Tucker, R.; Crabtree, D. (1970) Handbook of Toxicity of Pesticides to Wildlife. By U.S. Fish and Wildlife Service, Denver Wildlife Research Center . Washington, DC: USFWS. (Resource publication no. 84; available from: Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402; published study; CDL:228345-M)

131254 Britelli, M.; Muska, C. (1982) Chronic Toxicity of Methomyl to Daphnia magna: Haskell Laboratory Report No. 46-82; MR No. 0581- 930. (Unpublished study received Oct 3, 1983 under 352-366; submitted by E.I. du Pont de Nemours & Co., Inc., Wilmington, DE; CDL:251426-B)

131255 Driscoll, R.; Muska, C. (1982) Early Life Stage Toxicity of Metho- myl to Fathead Minnow: Haskell Laboratory Report No. 528-82; MR No. 0581-930. (Unpublished study received Oct 3, 1983 under 352-366; submitted by E.I. du Pont de Nemours & Co., Inc., Wil- mington, DE; CDL:251426-C)

161886 Beavers, J. (1983) An Acute Oral Toxi city Study in the Bobwhite with H-15,000: Final Report: Project No.: 112-142. Unpublished study prepared by WIldlife International Ltd. 15 p.

40098001 Mayer, F.; Ellersieck, M. (1986) Manual of Acute Toxicity: Interpretation and Data Base 410 Chemicals and 66 Species of Fres h-Water Animals. US Fish & Wildlife Service; Resource Publica tion (160): 579 p.

40094602 Johnson, W.; Finley, M. (1980) Handbook of Acute Toxicity of Chemicals to Fish and Aquatic Invertebrates: Resource Publication 137. US Fish and Wildlife Service, Washington, D.C. 106 p.

41441201 Ward, T.; Boeri, R. (1989) Static Acute Toxic ity of Methomyl to the Mysid, Mysidopsis bahia: Lab Project Number: 8963-DU. Unpublished study prepared by EnviroSystems Div., Resource Analysts, Inc. 32 p.

41441202 Boeri, R.; Ward, T. (1989) Static Acute Toxicity of Methomyl to the Sheepshead Minnow, Cyprinodon variegatus: Lab Project Number: 8964-DU. Unpublished study prepared by EnviroSystems Div., Resource Analysts, Inc. 32 p.



### -55 of 83-41898602 Beavers, J.; Hawrot, R.; Lynn, S.; et al. (1991) H-17940: A One- Generation Reproduction Study with the Northern Bobwhite (Coli- nus virginianus): Lab Project No: 112/227. Unpublished study prepared by Wildlife International Ltd. 168 p.

42140101 Sarver, J. (1991) Acute Oral Toxicity Study with DPX-X1179-394 in Male and Female Rats: Lab Project Number: 9182-001. Unpub- lished study prepared by E. I. du Pont de Nemours and Co., Inc. 33

p.

43250701 Lu, C. (1983) Nudrin Two-Generation Reproduction Study in Rats: Lab Project Number: WRC RIR275. Unpublished study prepared by WIL Research Lab., Inc. 1144 p.

45125502 Adelberger, I. (2000) Methomyl 25 WP: A Dose/Response Test to Evaluate the Effects on the Predatory Mite, Typhlodromus pyri Scheuten (Acri, Phytoseiidae) in the Laboratory: Lab Project Number: 2914: 99342/01-NLTP. Unpublished study prepared by IFU Umweltanalytik GmbH. 33 p.

45133301 Schuld, M. (2000) Methomyl 20L: A Dose/Response Test to Evaluate the Effects on the Aphid Parasitoid Aphidius rhopalosiphi (Hymenoptera, Braconidae) in the Laboratory: Lab Project Number: 99205/01-NLAP: 2669. Unpublished study prepared by IFU Umweltanalytik GmbH. 39 p.

42074601 Ward, T. (1991) Acute Flow-through Mollusc Shell Deposition with DPX-X1179-394 (Methomyl): Lab Project Number: MR-8808-001. Unpublished study prepared by EnviroSystems, Inc. incoop. with Dupont Haskell Labs. 31 p.

45299801 Medlicott, B.; Harris, T. (2000) Methom yl (DPX-X1179) Technical: Avian Acute Dietary Toxicity Test with Northern Bobwhite (Colinus virginianus): Lab Project Number: DUPONT-4378: 00022. Unpublished study prepared by Genesis Laboratories, Inc. 51 p.

45299802 Medlicott, B.; Harris, T. (2000) Methom yl (DPX-X1179) Technical: Avian Acute Dietary Toxicity Test with the Mallard Duck (Anas platyrhynchos): Lab Project Number: DUPONT-4379: 00023. Unpublished study prepared by Genesis Laboratories, Inc. 51 p.

43072101 Strawn, T.; Rhodes, J.; Leak, T. (1993) Full Life-Cycle Toxicity of DPX-X1179-394 (Methomyl) to the Fathead Minnow (Pimephales promelas) Under Flow-Through Conditions: Final Report: Lab Project Number: 39293: HLO 47-93. Unpublished study prepared by ABC Laboratories, Inc. 3582 p.

43744402 Samel, A. (1995) An Evaluation of the Effects and Fate of Methomyl Insecticide Exposure in Outdoor Microcosms: Lab Project Number: AMR 2389-92: ML93-0445-DUP: 112-299. Unpublished study prepared by Morse Labs and Wildlife International, Ltd. 877 p.

43769401 Hurtt, M. (1995) Nudrin--Two Generation Reproduction Study in the Rat: Supplement No.1: Lab Project Number: RA274: WRC RIR-275: HLO 519-95. Unpublished study prepared by WIL Research Labs, Inc. 149 p.

44969301 Wachter, S. (1999) Methomyl Technical: Acute Toxicity to the Earthworm, Eisenia foetida Michaelsen. Unpublished study performed by Arbeitsgemeinschaft, GAB Biotechnologie GmbH & IFU Umweltanalytik GmbH Eutinger Stra β e 24, D-75223 Niefern-Öschelbronn, Germany. Sponsor: E. I. Du Pont de Nemours and Company, Wilmington, DE 19898.

45013202 Boeri, R.; Magazu, J.; Ward, T. (1998) Methomyl Technical: Flow-Through Early Life Stage Toxicity to the Sheepshead Minnow, Cyprinodon variegatus . Unpublished study performed by T.R. Wilbury Laboratories, Inc. Marblehead, MA.

45013203 Ward, T.; Magazu, J.; Boeri, R. (1999) Methomyl Technical: Flow-Through Chronic Toxicity to the Mysid, Americamysis bahia (Formerly Known as Mysidopsis bahia ). Unpublished study performed by T.R. Wilbury Laboratories, Inc. Marblehead, MA.



### -56 of 83-

### -57 of 83- 45093001 Schur, A. (2000) Methomyl Technical: Acute Oral and Contact Toxicity to the Honeybee, Apis mellifera L. Unpublished study performed by Arbeitsgemeinschaft, GAB Biotechnologie GmbH & IFU Umweltanalytik GmbH Eutinger Stra β e 24, Niefern-Öschelbronn, Germany.

45125501 Aldelberger, I. (2000) Methomyl 20L: A Dose/Response Test to Evaluate the Effects on the Predatory Mite, Typhlodromus pyri Scheuten (Acari, Phytoseiidae) in the Laboratory. Unpublished study performed by Arbeitsgemeinschaft, GAB Biotechnologie GmbH & IFU Umweltanalytik GmbH Eutinger Stra β e 24, D-75223 Niefern-Öschelbronn, Germany. Sponsor: E. I. Du Pont de Nemours and Company, Wilmington, DE 19898.

45133302 Schuld, M. (2000) Methomyl 25 WP: A Dose/Response Test to Evaluate the Effects on the Aphid Parasitoid Aphidius rhopalosiphi (Hymenoptera, Braconidae) in the Laboratory: Lab Project Number: 2915: 99342/01-NLAP. Unpublished study prepared by IFU Umweltanalytik GmbH. 38 p.

45459201 Ulf Luhrs (2001) Methomyl 20L: Effects on Reproduction and Growth of the Earthworm, Eisenia fetida (Savigny 1826), in Artificial Soil: Lab Pr oject Number: 6216022: 5503. Unpublished study prepared by Institut fur Biologische Analytik. 43 p.

### APPENDIX A. Toxicity Data for Thiodicarb and Methomyl:

TABLE 1. Submitted Toxicity Data for Thiodicarb (Excluding Invalid Studies):

TAXON ENDPOINT FORMULATION MRID STUDY
CLASSIFICATION COMMENTS

BIRDS Birds (Acute)

Bobwhite quail ( Colinus virginianus ) LD 50 = 2,023 mg a.i./kg-bw TGAI (99+%) 46478 (also, 00044269) Acceptable NOAEL could not be
determined because reductions in weight gain at all treatment levels; slope = 4.1 (1.6 – 6.6) Birds (Acute/Sub-Acute)

Mallard duck ( Anas platyrhynchos ) 96-hr LC 50 = >5,620 mg a.i./kg=diet TGAI (99+%) 46479 (also, 00044270) Acceptable NOAEC = 1,780 mg a.i./kgdiet (LOAEC = 5,620 mg a.i./kg-diet based on reduction in food consumption and body weight gain)

Bobwhite quail ( Colinus virginianus ) 96-hr LC 50 = >5,620 mg a.i./kg=diet TGAI (99+%) 46480 (also, 00044271) Acceptable No mortalities associated with treatment; NOAEC = 3160 mg a.i./kg-diet based on reduced food consumption at 5620 mg a.i./kg-diet Birds (Chronic)

Bobwhite quail ( Colinus virginianus ) NOAEC = 1,000 mg a.i./kg-diet

LOAEC = >1,000 mg a.i./kg-diet TGAI (94.6%) 43313003
and

43389201 Acceptable No reproductive effects seen at any concentration tested.

Mallard duck ( Anas platyrhynchos ) NOAEC = 500 mg a.i./kg-diet TGAI (94.6%) 43313004
and

43389202 Acceptable LOAEC = 1,000 mg a.i./kgdiet, based on reduction in number of eggs laid/hen

MAMMALS Mammals (acute) Laboratory rat
( Rattus norvegicus ) LD 50 = 39.1 mg a.i./kg-bw TGAI 00025791 Acceptable None

Mammals (Chronic)

Laboratory rat
( Rattus norvegicus ) NOAEL = 100 mg a.i./kg-diet (5 mg a.i./kg/day)

LOAEL = 300 mg a.i./kg-diet (15 mg a.i./kg/day) TGAI 42381301 Acceptable LOAEL based on decreased fetal body weight and viability



### -58 of 83-TAXON ENDPOINT FORMULATION STUDY

MRID COMMENTS CLASS-
IFICATION

TERRESTRIAL INVERTEBRATES

Honey bee ( Apis mellifera ) 48-hr LD 50 = >25 μg a.i./bee TGAI (99.95%) 4 2528501 Acceptable Acute contact; NOAEL = 3.1 μg a.i./bee; highest mortality was 37% at the highest concentration tested ( i.e ., 25 μg a.i./bee)

Wasp ( Aphidius rhopalosiphi ) 48-hr LC 50 = 1.2 g product/ha Formulation (Larvin® SC 375, 38% a.i.) 45565801 Supplemental (not adequate for RQ
calculation – not a product currently registered in the US) Scientifically sound, but a non-guideline study (48-hr exposure phase followed by 24-hr fecundity phase followed by 9-10 days observation); reduced number of eggs/female in all treatment groups (NOAEC <0.313 g product/ha); slope = 2.21 (1.59 – 2.83)

FRESHWATER FISH Freshwater Fish (Acute)

Rainbow trout ( Oncorhynchus mykiss ) LC 50 = 3.45 mg
a.i./L TGAI (94.5%) 41605502 Acceptable A slope could not be
determined

Bluegill sunfish ( Lepomis
macrochirus ) LC 50 = 1.21 mg
a.i./L TGAI (99%) 00044273 Acceptable A slope could not be
determined

Bluegill sunfish ( Lepomis
macrochirus ) LC 50 = 1.47 mg
a.i./L TGAI (99.95%) 41605501 Acceptabl e Slope = 6.48 (3.8 – 9.2)

Freshwater Fish (Chronic)

Fathead
minnow ( Pimephales promelas ) NOAEC = 0.025 mg a.i./L TGAI (98.9%) 44484101 Supplemental Early life-stage; only two replicates (instead of 4) were used; sub-lethal signs of toxicity were not reported; LOAEC = 0.053 mg a.i./L [based on reduced larval growth – total length (4%) and wet weight (14.3%)]

ESTUARINE/MARINE FISH Estuarine/Marine Fish (Acute) Sheepshead

minnow ( Cyprinodon variegates ) 96-hr LC 50 = 0.49 mg a.i./L Formulation (Larvin® 80DF, 81.1% a.i.) 42738502 Supplemental The NOAEC could not be determined; slope = 2.9 (1.8 – 3.9); formulation not currently registered in the U.S. Sheepshead

minnow ( Cyprinodon variegates ) 96-hr LC 50 = 0.47 mg a.i./L Formulation (Larvin® 3.2, 33.2% a.i.) 42738501 Acceptable NOAEC could not be determined; slope = 4.4 (3.1 – 5.8)

Sheepshead

minnow ( Cyprinodon variegates ) 96-hr LC 50 = 0.53 mg a.i./L TGAI (95.8%) 41891005 Acceptabl e Slope = 7.1 (4.4 – 9.8)



### -59 of 83-TAXON ENDPOINT FORMULATION STUDY

MRID COMMENTS CLASS-
IFICATION

FRESHWATER INVERTEBRATES

Freshwater Invertebrates (Acute) Daphnid ( Daphnia

magna ) 48-hr EC 50 = ~0.050 mg
a.i./L TGAI (97.3%) 00100688 Supplemental Raw data lacking

Daphnid ( Daphnia

magna ) 48-hr EC 50 = 0.0053 mg
a.i./L TGAI (99%) 00044276 Acceptable None

Daphnid ( Daphnia

magna ) 48-hr EC 50 = 0.027 mg a.i./L TGAI (99.95%) 4 1605503 Acceptable A slope could not be
determined

Daphnid ( Daphnia

magna ) 48-hr EC 50 = 0.0488 mg
a.i./L Formulation (Larvin® 3.2, 33% a.i.) 43052801 Acceptable A slope could not be
determined

Freshwater Invertebrates (Chronic) Daphnid ( Daphnia

magna ) NOAEC = 0.009 mg a.i./L TGAI (97.3%) 00100688 Acceptable Based on reduced survival and total young produced.

ESTUARINE/MARINE INVERTEBRATES Estuarine/Marine Invertebrate (Acute)

Eastern oyster ( Crassostrea

virginica ) 96-hr EC 50 = 1.1 mg a.i./L (shell deposition) Formulation (Larvin® 3.2, 33.2% a.i.) 42342501 Supplemental (not adequate for RQ calculation) The control oysters did not
meet the minimum new shell growth requirement of 2mm (reached 1.49 and 1.59 mm); a
NOAEC could not be
calculated

Eastern oyster ( Crassostrea

virginica ) 96-hr EC 50 = 0.55 mg a.i./L (shell deposition) Formulation (Larvin® 80DF, 81.1% a.i.) 42917301 (amended
report 42834001) Acceptable NOAEC = 0.12 mg a.i/.L

Eastern oyster ( Crassostrea

virginica ) 96-hr EC 50 = could not be
established (shell deposition) TGAI (95.8%) 41891006 Supplemental EC 50 was not established due to high percentage affected at
each concentration tested (43% to 71% for dosage levels 0.58 to 4.6 mg a.i./L); effects
were seen at all concentrations (no NOAEL); no raw data available to verify results Mysid ( Americamysis
bahia ) 96-hr LC 50 = 0.075 mg a.i./L Formulation (Larvin® 80DF, 81.1% a.i.) 42738504 Acceptable NOAEC could not be
determined

Mysid ( Americamysis
bahia ) 96-hr LC 50 = 0.10 mg a.i./L Formulation (Larvin® 3.2, 33.2% a.i.) 42738503 Acceptable NOAEC = 0.035 mg a.i./L; slope = 7.4 (4.7 – 10.2)

Mysid ( Americamysis
bahia ) 96-hr LC 50 = 0.0285 mg
a.i./L TGAI (94.5%) 41891007 Acceptable NOAEC = 0.018 mg a.i./L; slope = 5.1 (0.62 – 9.6)

Fiddler crab ( Uca pugilator ) 2.5 mg a.i./L Technical (99%) 44277 Supplemental Slope = 8.5 (3.1 – 13.9)

Grass shrimp ( Palaemonetes pugio ) 0.067 mg a.i./L Technical (99%) 44278 Supplemental Slope = 4.5 (2.1 – 6.8)



### -60 of 83-TAXON ENDPOINT FORMULATION STUDY

MRID COMMENTS CLASS-
IFICATION AQUATIC PLANTS Aquatic Plants (Non-Vascular)

Algae ( Selenastrum capricornutum ) 96-hr EC 50 = >8.3 mg a.i./L

NOAEC = 1.6 mg a.i./L TGAI (94.5%) 42324801 Acceptable LOAEC = 2.4 mg a.i./L based on % inhibition of growth [max inhibition was 37% at the highest concentration tested (8.3 mg a.i./L)]; ;
measured concentrations of thiodicarb ranged from 74 to
88% of nominal at test
initiation to 21 and 24% nominal at termination; methomyl went from 5.7 – 6.4% (study initiation) to 56 – 60% (at termination) of
nominal



### -61 of 83-

### TABLE 2. Available Toxicity Data for Methomyl (Excluding Invalid Studies):

TAXON ENDPOINT FORMULATION MRID STUDY
CLASSIFICATION COMMENTS

BIRDS Birds (Acute) Bobwhite quail ( Colinus virginianus ) LD 50 = 24.2 mg a.i./kg-bw TGAI 00161886 Acceptable None

Birds (Acute/Sub-Acute)

Mallard duck ( Anas platyrhynchos ) 96-hr LC 50 = 3,602 mg a.i./kg=diet TGAI 45299802 Acceptable None

Mallard duck ( Anas platyrhynchos ) 96-hr LC 50 = 2,883 mg a.i./kg=diet TGAI 22923 Acceptable None

Bobwhite quail ( Colinus virginianus ) 96-hr LC 50 = 5,080 mg a.i./kg=diet TGAI 45299801 Acceptable None

Bobwhite quail ( Colinus virginianus ) 96-hr LC 50 = 1,100 mg a.i./kg=diet TGAI 22923 Acceptable None

Ring-necked

Pheasant ( Phasianus

colchicus ) 96-hr LC 50 = 1,975 mg a.i./kg=diet TGAI 22923 Acceptable None

Birds (Chronic)

Bobwhite quail ( Colinus virginianus ) NOAEC = 150 mg a.i./kg-diet

LOAEC = 500 mg a.i./kg-diet TGAI 41898602 Acceptable LOAEC based on fewer eggs laid and fewer eggs set

MAMMALS Mammals (Acute) Rat ( Rattus

rattus ) LD 50 = 30 mg/kg-bw TGAI 42140101 Acceptable None

Mammals (Chronic)

Rat ( Rattus

rattus ) NOAEL = 3.75 mg/kg-bw

LOAEL = 30 mg/kg-bw TGAI 43250701,
43769401 Acceptable LOAEL is based on decreased body weight and food consumption and altered hematology parameters

TERRESTRIAL INVERTEBRATES Honey bee ( Apis mellifera ) 48-hr LD 50 = 0.28 μg a.i./bee TGAI 45093001 Accepta ble Acute oral study

Honey bee ( Apis mellifera ) 48-hr LD 50 = 0.16 μg a.i./bee TGAI 45093001 Acceptable Acute contact study

Wasp ( Aphidius rhopalosiphi ) 48-hr LC 50 = 0.00027 lb
a.i./acre Formulation (Methomyl ® 25WP) 45133302 Supplemental Supplemental (non-guideline, but scientifically sound)

Wasp ( Aphidius rhopalosiphi ) 48-hr LC 50 = 0.00022 lb
a.i./acre Formulation (Methomyl ® 20L) 45133301 Supplemental Supplemental (non-guideline, but scientifically sound)



### -62 of 83-TAXON ENDPOINT FORMULATION STUDY

MRID COMMENTS CLASS-
IFICATION
Mite (Typhlodromus pyri) 7-day LC 50 = 0.0114 lb
a.i./acre Formulation (Methomyl ® 20L) 45125501 Supplemental Supplemental (non-guideline, but scientifically sound)

Mite (Typhlodromus pyri) 7-day LC 50 = 0.01115 lb
a.i./acre Formulation (Methomyl ® 25WP) 45125502 Supplemental Supplemental (non-guideline, but scientifically sound)

Earthworms (Eisenia fetida) 28-day LC 50 = > 12 mg a.i./kg dry soil (no
mortalities at hoighest

treatment concentration) Formulation (Methomyl ® 20L) 45459201 Supplemental Supplemental (non-guideline, but scientifically sound)

Earthworms (Eisenia fetida) 14-day LC 50 = 23 mg a.i./kg dry soil TGAI 44969301 Supplemental Supplemental (non-guideline, but scientifically sound)

FRESHWATER FISH Freshwater Fish (Acute)

See Table 3 Freshwater Fish (Chronic)

Fathead
minnow ( Pimephales promelas ) NOAEC = 0.057 mg a.i./L

LOAEC = 0.117 mg a.i./L TGAI (>99%) 131255 Acceptable Early life-stage; LOAEC
based on reduced survival.

Fathead
minnow ( Pimephales promelas ) NOAEC = 0.076 mg a.i./L

LOAEC = 0.142 mg a.i./L TGAI (>99%) 43072101 Acceptable Full life-cycle; LOAEC based on reduced growth of the parental and F 1 generation fish

ESTUARINE/MARINE FISH Estuarine/Marine Fish (Acute) Sheepshead

minnow ( Cyprinodon variegates ) LC 50 = 1.16 mg
a.i./L TGAI (98.4%) 45013202 Acceptable None

Estuarine/Marine Fish (Chronic)

Sheepshead

minnow ( Cyprinodon variegates ) NOAEC = 0.260 mg a.i./L

LOAEC = 0.490 mg a.i./L TGAI (98.6%) 45013202 Acceptable LOAEC based on reduction in total length and wet weight.

FRESHWATER INVERTEBRATES

Freshwater Invertebrates (Acute)

See Table 4 Freshwater Invertebrates (Chronic)

Daphnid ( Daphnia

magna ) NOAEC = 0.0007 mg
a.i./L

LOAEC = 0.001 mg a.i./L TGAI (>99%) 131254 Acceptable LOAEC based on delayed reproduction



### -63 of 83-TAXON ENDPOINT FORMULATION STUDY

MRID COMMENTS CLASS-
IFICATION

ESTUARINE/MARINE INVERTEBRATES Estuarine/Marine Invertebrate (Acute) Northern pink shrimp ( Penaeus
duorarum ) LC 50 = 0.019 mg a.i./L TGAI (90%) 00009134 Acceptable None

Mysid ( Americamysis
bahia ) LC 50 = 0.234 mg a.i./L TGAI (98.4%) 41441201 Acceptable None

Grass shrimp ( Palaemonetes vulgaris ) LC 50 = 0.049 mg a.i./L TGAI (90%) 00009134 Acceptable None

Eastern oyster ( Crassostrea

virginica ) LC 50 = >140 mg
a.i./L TGAI (98.4%) 42074601 Accepta ble Shell deposition study

Mud crab ( Neopanope

texana ) EC 50 = 0.41 mg
a.i./L TGAI (90%) 00009134 Acceptable None

Estuarine/Marine Invertebrate (Chronic)

Mysid ( Americamysis
bahia ) NOAEC = 0.029 mg a.i./L

LOAEC = 0.59 mg a.i./L TGAI (98.6%) 45013203 Supplemental LOAEC based on reduced number of young per surviving female



### -64 of 83-

### Table 3. Summary of Acute Toxicity Va lues for Methomyl and Freshwater Fish

. Species Compound (% a.i.) LC50 (96-h,

μg a.i./L) MRID Classification Notes:

560 400980-01 Supplemental Temp = 17 ̊ C pH = 7.5 Hardness = 40 mg/L

640 400980-01 Supplemental Temp = 12 ̊ C pH = 6.0 Hardness = 40 mg/L

700 400980-01 Supplemental Temp = 12 ̊ C pH = 6.5 Hardness = 40 mg/L

1000 400980-01 Supplemental Temp = 12 ̊ C pH = 7.5 Hardness = 12 mg/L

1050 400980-01 Supplemental Temp = 12 ̊ C pH = 8.5 Hardness = 40 mg/L

1120 400980-01 Supplemental Temp = 12 ̊ C pH = 7.5 Hardness = 40 mg/L

1150 400980-01 Supplemental Temp = 12 ̊ C pH = 7.5 Hardness = 40 mg/L 99

1220 400980-01 Supplemental Temp = 12 ̊ C pH = 7.5 Hardness = 40 mg/L

29 1200 400980-01 Supplemental Temp = 12 ̊ C pH = 7.5 Hardness = 40 mg/L Salmo salar
Atlantic salmon

24 1400 400980-01 Supplemental Temp = 12 ̊ C pH = 7.5 Hardness = 40 mg/L

480 400980-01 Supplemental Temp = 17 ̊ C pH = 6.5 Hardness = 40 mg/L

600 400980-01 Supplemental Temp = 17 ̊ C pH = 7.5 Hardness = 40 mg/L Lepomis
macrochirus Bluegill sunfish 95

620 400980-01 Supplemental Temp = 17 ̊ C pH = 8.5 Hardness = 40 mg/L



### -65 of 83-Species Compound LC50 MRID Classification Notes: (% a.i.) (96-h,

μg a.i./L)

840 400980-01 Supplemental Temp = 17 ̊ C pH = 7.4 Hardness = 320 mg/L

860 400980-01 Supplemental Temp = 22 ̊ C pH = 7.4 Hardness = 40 mg/L

940 400980-01 Supplemental Temp = 17 ̊ C pH = 6.0 Hardness = 40 mg/L

1050 400980-01 Supplemental Temp = 20 ̊ C pH = 7.2 Hardness = 40 mg/L

1150 400980-01 Supplemental Temp = 17 ̊ C pH = 7.4 Hardness = 40 mg/L

1200 400980-01 Supplemental Temp = 17 ̊ C pH = 7.4 Hardness = 40 mg/L

2000 400980-01 Supplemental Temp = 12 ̊ C pH = 7.4 Hardness = 40 mg/L

670 400980-01 Supplemental Temp = 17 ̊ C pH = 7.4 Hardness = 44mg/L 29

670 400980-01 Supplemental Temp = 22 ̊ C pH = 7.4 Hardness = 40 mg/L

370 400980-01 Supplemental Temp = 20 ̊ C pH = 7.4 Hardness = 40 mg/L

430 400980-01 Supplemental Temp = 27 ̊ C pH = 7.4 Hardness = 40 mg/L

560 400980-01 Supplemental Temp = 17 ̊ C pH = 7.4 Hardness = 40 mg/L 24

560 400980-01 Supplemental Temp = 22 ̊ C pH = 7.4 Hardness = 40 mg/L



### -66 of 83-Species Compound LC50 MRID Classification Notes: (% a.i.) (96-h,

μg a.i./L)

600 400980-01 Supplemental Temp = 22 ̊ C pH = 7.4 Hardness = 40 mg/L

710 400980-01 Supplemental Temp = 20 ̊ C pH = 7.2 Hardness = 40 mg/L

1200 400980-01 Supplemental Temp = 17 ̊ C pH = 7.4 Hardness = 40 mg/L

1800 400980-01 Supplemental Temp = 12 ̊ C pH = 7.4 Hardness = 40 mg/L

2800 400980-01 Supplemental Temp = 22 ̊ C pH = 7.4 Hardness = 272 mg/L

degradate 462,000 00009061 Supplemental Test compound is a degradate of methomyl

1500 400980-01 Supplemental Temp = 12 ̊ C pH = 7.5 Hardness = 40 mg/L 99

2200 400980-01 Supplemental Temp = 12 ̊ C pH = 7.5 Hardness = 40 mg/L Salvelinus fontinalis
Brook trout

24 1220 400980-01 Supplemental Temp = 12 ̊ C pH = 7.5 Hardness = 40 mg/L

95 530 400980-01 Supplemental Temp = 22 ̊ C pH = 7.4 Hardness = 40 mg/L

320 400980-01 Supplemental Temp = 22 ̊ C pH = 7.4 Hardness = 40 mg/L

<560 400980-01 Supplemental Temp = 25 ̊ C pH = 7.4 Hardness = 40 mg/L swim-up fry tested Ictalurus

punctatus Channel catfish

24

760 400980-01 Supplemental Temp = 22 ̊ C pH = 7.4 Hardness = 40 mg/L fingerlings tested



### -67 of 83-Species Compound LC50 MRID Classification Notes: (% a.i.) (96-h,

μg a.i./L)

1800 400980-01 Supplemental Temp = 25 ̊ C pH = 7.4 Hardness = 40 mg/L yolk-sac fry tested

99 2800 400980-01 Supplemental Temp = 17 ̊ C pH = 7.4 Hardness = 45 mg/L

29 1500 400980-01 Supplemental Temp = 17 ̊ C pH = 7.2 Hardness = 46 mg/L Pimephales promelas
Fathead minnow

24 1800 400980-01 Supplemental Temp = 12 ̊ C pH = 7.2 Hardness = 40 mg/L

95 1250 400980-01 Supplemental Temp = 22 ̊ C pH = 7.2 Hardness = 40 mg/L Micropterus

salmoides Largemouth bass

24 760 400980-01 Supplemental Temp = 22 ̊ C pH = 7.2 Hardness = 40 mg/L

860 400980-01 Supplemental Temp = 17 ̊ C pH = 7.4 Hardness = 40 mg/L

1050 400980-01 Supplemental Temp = 12 ̊ C pH = 7.4 Hardness = 40 mg/L

1100 400980-01 Supplemental Temp = 12 ̊ C pH = 7.5 Hardness = 40 mg/L

1200 400980-01 Supplemental Temp = 12 ̊ C pH = 8.5 Hardness = 40 mg/L

1400 400980-01 Supplemental Temp = 12 ̊ C pH = 7.4 Hardness = 320 mg/L

1500 400980-01 Supplemental Temp = 12 ̊ C pH = 6.5 Hardness = 40 mg/L Oncorhyncus mykiss
Rainbow trout 95

1600 400980-01 Supplemental Temp = 12 ̊ C pH = 7.2 Hardness = 40 mg/L



### -68 of 83-Species Compound LC50 MRID Classification Notes: (% a.i.) (96-h,

μg a.i./L)

1700 400980-01 Supplemental Temp = 12 ̊ C pH = 7.4 Hardness = 40 mg/L

2000 400980-01 Supplemental Temp = 7 ̊ C pH = 7.4 Hardness = 40 mg/L

29 1200 400980-01 Supplemental Temp = 12 ̊ C pH = 7.4 Hardness = 40 mg/L

1200 400980-01 Supplemental Temp = 12 ̊ C pH = 7.2 Hardness = 40 mg/L

1300 400980-01 Supplemental Temp = 12 ̊ C pH = 7.4 Hardness = 40 mg/L Swim-up fry tested

1400 400980-01 Supplemental Temp = 12 ̊ C pH = 7.2 Hardness = 40 mg/L

1400 400980-01 Supplemental Temp = 12 ̊ C pH = 7.2 Hardness = 40 mg/L 1-day degradation

1400 400980-01 Supplemental Temp = 12 ̊ C pH = 7.2 Hardness = 40 mg/L 3-day degradation

1400 400980-01 Supplemental Temp = 17 ̊ C pH = 7.2 Hardness = 40mg/L

1500 400980-01 Supplemental Temp = 12 ̊ C pH = 7.2 Hardness = 40 mg/L 7-day degradation

2000 400980-01 Supplemental Temp = 12 ̊ C pH = 7.2 Hardness = 40 mg/L 24

2100 400980-01 Supplemental Temp = 10 ̊ C pH = 7.2 Hardness = 40 mg/L



### -69 of 83-Species Compound LC50 MRID Classification Notes: (% a.i.) (96-h,

μg a.i./L)

2300 400980-01 Supplemental Temp = 10 ̊ C pH = 7.2 Hardness = 40 mg/L

>2500 400980-01 Supplemental Temp = 12 ̊ C pH = 7.4 Hardness = 272 mg/L Flow-through test

3200 400980-01 Supplemental Temp = 12 ̊ C pH = 7.2 Hardness = 40 mg/L Yolk-sac fry

32,000 400980-01 Supplemental Temp = 10 ̊ C pH = 7.2 Hardness = 40 mg/L Eyed egg tested



### -70 of 83-

### Table 4. Summary of Acute Toxicity Values for Methomyl and Freshwater Invertebrates.

LC50 (μg

a.i./L) Species Compound (% a.i.) 48-h 96-h MRID Classification Notes:

95 88
-- 400980-01 Supplemental Temp = 22 ̊ C pH = 7.4 Hardness = 40 mg/L Chironomus

plumosus

Midge

24 32
-- 400980-01 Supplemental Temp = 20 ̊ C pH = 7.4 Hardness = 272 mg/L

95 8.8
– 400980-01 Supplemental Temp = 21 ̊ C pH = 7.4 Hardness = 272 mg/L

>99 31.7
– 19977 Acceptable Temp = 20 ̊ C pH = 6.8-8.6 Hardness = 92.8 mg/L Daphnia magna
Water flea

24 5.0
– 400980-01 Supplemental Temp = 20 ̊ C pH = 7.2 Hardness = 40 mg/L

99
-- 920 400980-01 Supplemental Temp = 17 ̊ C pH = 7.1 Hardness = 40 mg/L

-- 720 400980-01 Supplemental Temp = 17 ̊ C pH = 7.4 Hardness = 40 mg/L

-- 1050 400980-01 Supplemental Temp = 12 ̊ C pH = 7.4 Hardness = 274 mg/L Flow-through test

1050
-- 400980-01 Supplemental Temp = 12 ̊ C pH = 7.2 Hardness = 40 mg/L

1050
-- 400980-01 Supplemental Temp = 12 ̊ C pH = 7.2 Hardness = 40 mg/L 1- day degradation

750
-- 400980-01 Supplemental Temp = 12 ̊ C pH = 7.2 Hardness = 40 mg/L 3- day degradation Gammarus pseudolimnaeus
scud

24

340
-- 400980-01 Supplemental Temp = 12 ̊ C pH = 7.2 Hardness = 40 mg/L 7- day degradation



### -71 of 83-

### -72 of 83- LC50 (μg

a.i./L) Species Compound (% a.i.) 48-h 96-h MRID Classification Notes:

95
– 343 400980-01 Supplemental Temp = 7.0 ̊ C pH = 7.5 Hardness = 42 mg/L Isogenus sp.

Stonefly

24
– 29 400980-01 Supplemental Temp = 7.0 ̊ C pH = 7.5 Hardness = 42 mg/L

95
-- 69 400980-01 Supplemental Temp = 7.0 ̊ C pH = 7.5 Hardness = 40 mg/L Pteronarcella
badia Stonefly

24
-- 60 400980-01 Supplemental Temp = 7.0 ̊ C pH = 7.5 Hardness = 40 mg/L

95-98
– 34 400946-02 Acceptable Temp = 7.0 ̊ C pH = N/A
Hardness = N/A Skwala sp.

Stonefly

24
– 29 400946-02 Acceptable Temp = 7.0 ̊ C pH = N/A
Hardness = N/AAPPENDIX B. Major Organic Environmental Degradates of Thiodicarb.Table B1. Chemical Names, Structures, and Maximum Reported Amounts ofThiodicarb and Its Major Degradates.Code Name/SynonymChemical NameAChemical StructureStudy TypeMaximum%AR (day)Final %AR(study length)PARENTThiodicarbIUPAC:(3EZ,12EZ)-3,7,9,13-tetramethyl5,11-dioxa-2,8,14-trithia-4,7,9,12-tetraazapentadeca-3,12-diene-6,10-dioneCAS:dimethyl N,N′-[thiobis[(methylimino)carbonyloxy]]bis[ethanimidothioate]CAS-no:59669-26-0Formula:C10H18N4O4S3MW:354.5 g/molSNOONSNOONSMAJOR (>10%) DEGRADATESHydrolysis -pH 5Hydrolysis -pH 7Hydrolysis -pH 920(30)36(30)66(1)20 (30)36 (30)19 (30)Aqueous photolysis47(23)47 (23)Soil photolysis16(7)15 (30)Aerobic soil80(7)24 (60)Anaerobic aquatic7.2 (0)not detected (14)MethomylIUPAC:S-methyl (EZ)-N-(methylcarbamoyloxy)thioacetimidateCAS:methyl N-[[(methylamino)carbonyl]oxy]ethanimidothioateCAS-no:16752-77-5Formula:C5H10N2O2SMW:162.21 g/molNOONSHField studies1.68 ppm (14)0.028 ppm (213)Hydrolysis -pH 5Hydrolysis -pH 7Hydrolysis -pH 90.92 (30)3.1(30)77(30)0.92 (30)3.1 (30)77 (30)Aqueous photolysis1.7 (23)1.7 (23)Soil photolysis27(30)27 (30)Aerobic soil3.2 (0.5)0.24 (60)Anaerobic aquatic3.5 (0.17)not detected (14)MethomylOximeS-methyl-N-hydroxythioacetimidateFormula:C3H7NOSMW:105.16 g/molONSHField studiesnot analyzed-73 of 83--74 of 83-Code Name/SynonymChemical NameAChemical StructureStudy TypeMaximum%AR (day)Final %AR(study length)HydrolysisnotidentifiedAq. photolysis15(23)15 (23)Soil photolysisnot identifiedAerobic soil1.8 (60)1.8 (60)Anaerobic aquatic73(14)73 (14)AcetonitrileMethyl cyanide; cyanomethaneFormula:C2H3NMW:41.05 g/molNField studiesnot analyzedAcetamideEthanamide; acetic acid amideFormula:C2H5NOMW:59.07 g/molNH2O(all studies)not identified or analyzedBUnknown 3(not identified)(not identified)Anaerobic aquatic60(0.17)1.5 (14)Unknown 4(not identified)(not identified)Anaerobic aquatic29(2)0.67 (14)HydrolysisnotidentifiedAq. photolysis4.8 (23)4.8 (23)Soil photolysisnot identifiedAerobic soil52(60)52 (60)Anaerobic aquatic16(14)16 (14)CarbonDioxideCarbon dioxideFormula:CO2MW:44.01 g/molOOField studiesnot analyzedA. IUPAC and CAS chemical names were sourced from the Compendium of Pesticide Common Names(Copyright © 1995–2009 Alan Wood).Online at:http://www.alanwood.net/pesticides/B. Acetamide was identified as a major degradate of methomylin an aerobic aquatic metabolism study of methomyl (MRID 43325401).

### APPENDIX C: Data Call-In Tables.

The Environmental Fate and Effects Division (EFE D) has completed a Data Call-In (DCI) table
for the thiodicarb environmental fate and effects da ta gaps identified in re gistration review. The attached DCI table, which incl udes the guideline number and st udy title for required data, also provides a rationale for requiring the data, an ex planation of how the data will be used, and a brief description of how the data could im pact the Agency’s future decision-making.

Environmental Fate Data:

Guideline Number: 835.4300 Study Title: Aerobic Aquatic Metabolism Rationale for Requiring the Data The Agency has a limited understanding of how thio dicarb behaves in the environment once applied. Depending on how quickly, to what extent, a nd to which transformation products the compound degrades, thiodicarb may or may not pose potential exposure concern in water. Because thiodicarb degradation in water is not well unders tood, the Agency is requiring data. Practical Utility of the Data

How will the data be used? Aerobic aquatic metabolism data will facilitate a better understanding of th e fate of thiodicarb residues in water. If data indicate that degradation in aerobi c conditions occurs rapidly in water and produces nontoxic transformation products, then the Agency coul d potentially determine that thiodicarb residues of concern do not persist in water unde r aerobic conditions. If data indicate that degradation is not appreciable in water or that the transformation product s are of similar or higher toxicity than the parent compound, then the Agency could conclude that th iodicarb residues of concern persist in water under
aerobic conditions.

How could the data change the Agency’s decision or impact the Agency’s future decision-making? In the absence of the requested data, thiodicar b aerobic aquatic metabolism half-lives will be conservatively assumed two-fold greater than aerobic soil metabolism half-lives. If the required data indicate that thiodicarb in aerobic aqueous environm ents is rapidly biodegraded, then risk assessment conclusions and associated labeled use precautions and/ or restrictions could be made less restrictive.



### -75 of 83-

### Guideline Number: 835.6100 Study Title: Analytical Method (and Associated Independent Laboratory Validation) for Residues
in Soil Rationale for Requiring the Data Independently validated analytical methods for resi dues in soil, water, sediment, and plant material (environmental chemistry methods) submitted by the regist rant are used to evaluate analyses described in submitted environmental fate and ecological effects studies. Submitted analytical methods are also used by various Federal, State, Tribal, and local agenci es to detect and monitor residues that are or are suspected to be in environmental compartments due to outdoor uses and accidental releases. Independent laboratory validations for submitted analytical methods are necessary to confirm that the methods are
functional and to confirm the leve ls of detection and quantitation reported in registrant-prepared
validations.

An analytical method ( a.k.a. environmental chemistry method) for thiodicarb residues in soil was submitted by the registrant (MRID 44082). However, an independent validation of this method was not submitted with the method. Therefore, an independ ent laboratory validation of the submitted analytical method for thiodicarb residues in soil (MRID 44082) is required to support monitoring for thiodicarb
residues and to evaluate submitted environmental fate and ecological effects data. Alternatively, a stateof-the-art analytical method and in dependent laboratory validation may be submitted in lieu of validation of the previously submitted method. Practical Utility of the Data

How will the data be used? In the absence of independently validated enviro nmental chemistry methods , submitted environmental fate and ecological effects data may not be revi ewable and entities outside the Agency may lack chemical-specific methods for analyses in enviro nmental compartments. Independently validated environmental chemistry methods will be used to ev aluate submitted environm ental fate and ecological
effects data and will be made available for enforcemen t and monitoring purposes at the federal, state, and
local levels.

How could the data change the Agency’s decision, or impact the Agency’s future decision-making?
Risk assessment conclusions could be altered if th ey are not supported by either study data or environmental monitoring detections that are based on independently validated environmental chemistry methods. Furthermore, while not directly related to Agency decision-making, independently validated environmental chemistry methods are necessary to ensure the safety of those in proximity to releases of
thiodicarb residues in the environment.



### -76 of 83-

### Guideline Number: 835.6200 Study Title: Analytical Method (and Associated Independent Laboratory Validation) for Residues
in Water Rationale for Requiring the Data Independently validated analytical methods for resi dues in soil, water, sediment, and plant material (environmental chemistry methods) submitted by the regist rant are used to evaluate analyses described in submitted environmental fate and ecological effects studies. Submitted analytical methods are also used by various Federal, State, Tribal, and local agenci es to detect and monitor residues that are or are suspected to be in environmental compartments due to outdoor uses and accidental releases. Independent laboratory validations for submitted analytical methods are necessary to confirm that the methods are
functional and to confirm the leve ls of detection and quantitation reported in registrant-prepared
validations.

Use of thiodicarb may impact surface water quality due to runoff of rain water and drift of residues. This is especially true for poorly draining soils, erodible soil s, and soils with shallow ground water. Therefore, outside agencies may request analytical methods with which to monitor for thiodicarb residues in water
and in soil.

An independently validated environmental chemistr y method for thiodicarb residues in water has not been submitted by the registrant. If aerobic aquatic metabolism data indicate that thiodicarb is not transient in aerobic water bodies, a validated analytic method for residues in water should be available. Therefore, an environmental chemistry method for thiodicarb residues of concern in water and an independent laboratory validation of the method ar e required to support monitoring for thiodicarb residues and to evaluate newly submitted envi ronmental fate and ecological effects data. Practical Utility of the Data

How will the data be used? In the absence of independently validated enviro nmental chemistry methods , submitted environmental fate and ecological effects data may not be revi ewable and entities outside the Agency may lack chemical-specific methods for analyses in enviro nmental compartments. Independently validated environmental chemistry methods will be used to evaluate newly submitted environmental fate and ecological effects data and will be made availabl e for enforcement and monitoring purposes at the federal, state, and local levels.

How could the data change the Agency’s decision, or impact the Agency’s future decision-making?
Risk assessment conclusions could be altered if th ey are not supported by either study data or environmental monitoring detections that are based on independently validated environmental chemistry methods. Furthermore, while not directly related to Agency decision-making, independently validated environmental chemistry methods are necessary to ensure the safety of those in proximity to releases of
thiodicarb residues in the environment.



### -77 of 83-

### Thiodicarb Effects Data:

Guideline Number: 850.2100 Study Title: Avian Acute Oral Toxicity Test Rationale for Requiring the Data Acceptable acute avian oral toxicity data were s ubmitted for exposures of bobwhite quail to thiodicarb; however, data are not available for a passerine specie s, which is now required under the 40 CFR Part 158 (Oct. 26, 2007) data requirements for conventiona l pesticides. The new Part 158 data requirements specify that acute avian oral toxicity data be s ubmitted for either mallard duck or bobwhite quail and a passerine species. Therefore, an avian oral toxicity test is required for passerine birds, as specified in 40 CFR Part 158 (OPPTS Guideline 850.2100). A passerine st udy protocol must be submitted for review by the Agency prior to initiation of this study. Practical Utility of the Data

How will the data be used? Acute avian oral toxicity data for passerine species will be used to refine the screening-level assessment by determining whether there are differences in avia n species sensitivity to thiodicarb between passerines and upland game species. If oral acute toxicity data are not submitted for passerines, risk will be assumed for all passerine species.

How could the data impact the Agency’s future decision-making? If future endangered species risk assessments are pe rformed without these data, the Agency would have to assume that thiodicarb “may affect” listed passer ine birds directly (and listed species from other taxa indirectly), and use of thiodicarb and its formulated products may need to be restricted in areas where listed species could be exposed. The lack of these data will limit the flexibility the Agency and registrants have in coming into compliance with the Endangered Species Act and could result in use restrictions for thiodicarb use that are unnecessarily severe.

Guideline Number: 850.1350 Study Title: Estuarine/Marine Inv ertebrate Life Cycle Toxicity Test Rationale for Requiring the Data Chronic toxicity data for thiodicarb are not availabl e for estuarine/marine invertebrates. Since the LC 50 

### value for the most sensitive estuarine/marine invert ebrate species tested is < 1 mg/L, these data are required under the new 40 CFR Part 158 (Oct. 26, 2007). Although thiodicarb is expected to rapidly degrade to methomyl in many aquatic environments, it is expected to be moderate ly persistent in low pH waters. Therefore, chronic exposure to estuarine/ma rine animals from registered uses of thiodicarb is possible. Therefore, an estuarine/marine invertebra te life cycle toxicity test (OPPTS Guideline 850.1350) is required. Practical Utility of the Data

How will the data be used? Chronic toxicity data for estuarine/marine invertebra te species will be used to refine the screening-level assessment by determining whether there are potential risks to invertebrates inhabiting estuarine/marine
environments from the use of thiodicarb. If chronic toxicity data are not submitted for estuarine/marine invertebrates, risk will be assumed for all invertebrates in estuarine/marine environments potentially exposed to thiodicarb.

How could the data impact the Agency’s future decision-making? If future endangered species risk assessments are pe rformed without these data, the Agency would have to assume that thiodicarb “may affect” listed estuari ne/marine invertebrate species directly (and listed species from other taxa indirectly), and use of thiodi carb and its formulated products may need to be restricted in areas where listed species could be expo sed. The lack of these data will limit the flexibility



### -78 of 83-

### the Agency and registrants have in coming into compliance with the Endangered Species Act and could
result in use restrictions for thiodi carb use that are unnecessarily severe.

Guideline Number: 850.1400 Study Title: Estuarine/Marine Fish Early Life Stage Toxicity Test Rationale for Requiring the Data Chronic toxicity data for thiodicarb are not av ailable for estuarine/marine fish. Since the LC 50 

### value for the most sensitive estuarine/marine fish species tested is < 1 mg/L, these data are required under the new 40 CFR Part 158 (Oct. 26, 2007). Although thiodicarb is expected to rapidly degrade to methomyl in many aquatic environments, it is expected to be mode rately persistent in low pH waters. Therefore, chronic exposure to estuarine/marine animals from regist ered uses of thiodicarb is possible. Therefore, an estuarine/marine fish early life stage toxicity test (OPPTS Guideline 850.1400) is required. Practical Utility of the Data

How will the data be used? Chronic toxicity data for estuarine/marine fish species will be used to refine the screening-level assessment by determining whether there are potential risks to fish inhabiting estuarine/marine
environments from the use of thiodicarb. If chronic toxicity data are not submitted for estuarine/marine fish, risk will be assumed for all fish potentially expos ed to thiodicarb in estuarine/marine environments.

How could the data impact the Agency’s future decision-making? If future endangered species risk assessments are pe rformed without these data, the Agency would have to assume that thiodicarb “may affect” listed estuarine/marine fish species directly (and listed species from other taxa indirectly), and use of thiodicarb and its formulated products may need to be restricted in areas where listed species could be exposed. The lack of these data will limit the flexibility the Agency and registrants have in coming into compliance with the Endangered Species Act and could result in use restrictions for thiodicarb use that are unnecessarily severe.

Guideline Numbers: 850.4100 and 850.4150 Study Title: Terrestrial Plant Toxicity Tests (Tier I) Rationale for Requiring the Data Terrestrial plant toxicity studies and associated risk analysis of plants are required for registration of pesticides with outdoor uses (CFR Part 158). For terrestrial plants, Tier II studies are required when potential concerns are triggered ( i.e ., when there is some indication that there may be significant toxicity to plants). These indicators may be an herbicidal mode of action or statements on the label indicating toxicity to plants. Some thiodicarb labels ( i.e ., EPA Registration No. 264-379, 264-378, and 264-530) do contain the following statement:

“Horticultural varieties of many plants differ signi ficantly in sensitivity to pesticides. Before making applications to plants not listed, it is recommended that a small portion of the crop be treated to determine its tolerance to this product. Plants stressed from heat, moisture or other factors are usually more sensitive to sprays. Phytotoxic reactions can be minimized by spraying when stress is minimal such as early mornings or late evenings.”

The Agency confirmed with the registrant that this label statement is included on the label as a general precaution and is not the result of known phytotoxic effects. Therefore, the requirement for Tier II plant studies for thiodicarb is not triggere d by this label statement. Tier I seedling emergence and vegetative vigor studies (OPPTS Guidelines 850.4100 and 850.4150) are, however, required. In the absence of such data, risks to terrestrial plants from the use of thiodicarb will be assumed in the risk assessment.



### -79 of 83-

### Practical Utility of the Data

How will the data be used? Tier I vegetative vigor and seedling emergence data for terrestrial plants will be used to determine the potential for thiodicarb to affect non-target plant speci es in the terrestrial environment. In the absence of data specific for these plants, risk to terrestrial plants will be assumed.

How could the data impact the Agency’s future decision-making? If future endangered species risk assessments are pe rformed without these data, the Agency would have to presume risk to non-target terrestrial plants from us e of thiodicarb. Therefore, use of thiodicarb and its formulated products may need to be restricted in ar eas where listed species could be exposed. The lack of these data will limit the flexibility the Agency and re gistrants have in coming into compliance with the Endangered Species Act and could result in use restrictions for thiodicarb that are unnecessarily severe.

Guideline Number: 850.4400 Aquatic Plant Growth Tier I Study (Vascular Aquatic Plant) Rationale for Requiring the Data Aquatic (both vascular and non-vascular species) toxicity studies and associated risk analysis of plants are required for registration of pesticides with outdoor u ses (CFR Part 158). There are currently no data available to determine the levels of thiodicarb that could result in effects to aquatic vascular plants. Therefore, effects on non-target aquatic plants cannot be discounted, and the level of risk is unknown. Therefore, an aquatic vascular plant study is re quired as specified in 40 CFR Part 158 (OPPTS Guideline 850.4400). Practical Utility of the Data

How will the data be used? Data from Tier I aquatic plant toxicity studies will be used to estimate potential risks to aquatic plants
associated with uses of thiodicarb. The data will reduce uncertainties associated with the current risk assessment for plants and will improve our understanding of the potentia l effects of thiodicarb on aquatic plants. Because plants form the basis of most habitats and significantly contribute to overall environmental quality, a solid understanding of the potential risks to aquatic plants is essential for sound environmental management. The data will also be used in determining whether a “may affect” to Federally-listed threatened and endangered speci es is likely under the Endangered Species Act.

Additionally, the need for labeling language to mitig ate effects on non-target aquatic plant species is unknown. Results of this study woul d be used to determine if surface water exposure concentrations, due to run-off, are below levels of concern at the current label rates and to identify what, if any, label language is needed to mitigate identified risks.

How could the data impact the Agency’s future decision-making? Without aquatic plant growth data for thiodicarb, the Agency cannot determine the levels of thiodicarb that result in effects to vascular aquatic plants. Until these data are available, the registration decision will be
based on the information listed on the label. The lack of these data will limit the flexibility the Agency and registrants have in coming into compliance with th e Endangered Species Act, and could result in use restrictions for thiodicarb which may otherwi se be avoided, or which are unnecessarily severe.



### -80 of 83-

### Methomyl Effects Data:

Guideline Number: 850.2100 Study Title: Avian Acute Oral Toxicity Test Rationale for Requiring the Data Acceptable acute avian oral toxicity data were submitted for exposures of bobwhite quail and mallard ducks to methomyl; however, data are not available for a passerine species, which is now required under the 40 CFR Part 158 (Oct. 26, 2007) data requireme nts for conventional pesticides. The new Part 158 data requirements specify that acute avian oral toxicity data be submitted for either mallard duck or bobwhite quail and a passerine species. Therefore, an avian oral toxicity test is required for passerine birds, as specified in 40 CFR Part 158. A passerine st udy protocol must be submitted for review by the Agency prior to initiation of this study. Practical Utility of the Data

How will the data be used? Acute avian oral toxicity data for passerine species will be used to refine the screening-level assessment by determining whether there are differences in avia n species sensitivity to methomyl between passerines and upland game and waterfowl species. If oral acute toxicity data are not submitted for passerines, risk will be assumed for all passerine species.

How could the data impact the Agency’s future decision-making? If future endangered species risk assessments are pe rformed without these data, the Agency would have to assume that methomyl (as a degradate of thiodicar b) “may affect” listed passerine birds directly (and listed species from other taxa indirectly), and use of thiodicarb and its formulated products may need to be restricted in areas where listed species could be exposed. The lack of these data will limit the flexibility the Agency and registrants have in coming into compliance with the Endangered Species Act and could result in use restrictions for thiodicarb use that are unnecessarily severe.

Guideline Number: 850.2300 Study Title: Avian Reproduction Test (Mallard duck) Rationale for Requiring the Data Under the 40 CFR Part 158 (Oct. 26, 2007) data requirements for conventional pesticides avian reproduction data are required on waterfowl and upland game species (OPPTS 850.2300). Currently acceptable data for methomyl are only available for upland game species. The chronic toxicity data available for birds indicate that mallard ducks ( Anas platyrhynchos) (MRID 43313004) are more sensitive to thiodicarb than bobwhite quail ( Colinus virginianus ) (MRID 43313003). Additionally, bobwhite quail appear more sensitive to methomyl than to thiodicarb based on chronic exposure (MRID 41898602). Therefore, based on available data, it is reasonable to assume that mallard ducks may be more sensitive to methomyl than to thiodicarb and that they may be more sensitive than bobwhite quail to methomyl on a chronic exposure basi s. Therefore, since additional avian reproduction data for methomyl could result in a lower avian reproduc tive endpoint, and, thus, could alte r risk conclusions for birds from the use of thiodicarb, we recommend requesti ng these data for methomyl at this time. Practical Utility of the Data

How will the data be used? Reproduction data for mallard ducks will be used to reduce uncertainties associated with using data from a potentially-less sensitive species (bobwhite quail) to assess chronic risks to birds from methomyl exposure. If reproduction data are not submitted fo r mallard ducks, the risks to birds from chronic exposure will be assumed to be higher than predicte d when using the chronic toxicity endpoint from bobwhite quail.



### -81 of 83-

### How could the data impact the Agency’s future decision-making? If future endangered species risk assessments are pe rformed without these data, the Agency would have to assume that methomyl (as a degradate of thiodicar b) “may affect” listed birds directly (and listed species from other taxa indirectly), and use of thiodi carb and its formulated products may need to be restricted in areas where listed species could be expo sed. The lack of these data will limit the flexibility the Agency and registrants have in coming into compliance with the Endangered Species Act and could
result in use restrictions for thiodi carb use that are unnecessarily severe.

Guideline Number: 850.4400 Aquatic Plant Growth Tier I Study (Vascular Aquatic Plant) Rationale for Requiring the Data Aquatic (both vascular and non-vascular species) toxicity studies and associated risk analysis of plants are required for registration of pesticides with outdoor u ses (CFR Part 158). There are currently no data available to determine the levels of methomyl that could result in effects to aquatic vascular plants. Therefore, effects on non-target aquatic plants cannot be discounted, and the level of risk is unknown. Therefore, an aquatic vascular plant study is re quired as specified in 40 CFR Part 158 (OPPTS Guideline 850.4400). Practical Utility of the Data

How will the data be used? Data from Tier I aquatic plant toxicity studies will be used to estimate potential risks to aquatic plants from methomyl exposure (as a degradate of thiodicarb). The data will reduce uncerta inties associated with the current risk assessment for plants and will improve our understanding of the potential effects of thiodicarb use on aquatic plants. Because plants form the basis of most habitats and significantly contribute to overall environmental quality, a solid understanding of the potential risks to aquatic plants is essential for sound environmental management. The data will also be used in determining whether a “may affect” to Federally-listed threatened and endangered speci es is likely under the Endangered Species Act.

Additionally, the need for labeling language to mitig ate effects on non-target aquatic plant species is unknown. Results of this study woul d be used to determine if surface water exposure concentrations, due to run-off, are below levels of concern at the current label rates and to identify what, if any, label language is needed to mitigate identified risks.

How could the data impact the Agency’s future decision-making? Without aquatic plant growth data for methomyl, the Agency cannot determine the levels of thiodicarb that result in effects to vascular aquatic plants. Until these data are available, the registration decision will be
based on the information listed on the label. The lack of these data will limit the flexibility the Agency and registrants have in coming into compliance with th e Endangered Species Act, and could result in use restrictions for thiodicarb which may otherwi se be avoided, or which are unnecessarily severe.

Guideline Number: 850.5400 Aquatic Plant Growth Tier I Study (Non-vascular Aquatic Plant) Rationale for Requiring the Data Aquatic (both vascular and non-vascular species) toxicity studies and associated risk analysis of plants are required for registration of pesticides with outdoor u ses (CFR Part 158). There are currently no data available to determine the levels of methomyl that could result in effects to aquatic non-vascular plants. Therefore, effects on non-target aquatic plants cannot be discounted, and the level of risk is unknown. Therefore, an aquatic non-vascular plant study is required as specified in 40 CFR Part 158 (OPPTS Guideline 850.5400).



### -82 of 83-

### -83 of 83- Practical Utility of the Data

How will the data be used? Data from Tier I aquatic plant toxicity studies will be used to estimate potential risks to aquatic plants from methomyl exposure (as a degradate of thiodicarb). The data will reduce uncerta inties associated with the current risk assessment for plants and will improve our understanding of the potential effects of thiodicarb use on aquatic plants. Because plants form the basis of most habitats and significantly contribute to overall environmental quality, a solid understanding of the potential risks to aquatic plants is essential for sound environmental management. The data will also be used in determining whether a “may affect” to Federally-listed threatened and endangered speci es is likely under the Endangered Species Act.

Additionally, the need for labeling language to mitig ate effects on non-target aquatic plant species is unknown. Results of this study woul d be used to determine if surface water exposure concentrations, due to run-off, are below levels of concern at the current label rates and to identify what, if any, label language is needed to mitigate identified risks.

How could the data impact the Agency’s future decision-making? Without aquatic plant growth data for methomyl, the Agency cannot determine the levels of thiodicarb that result in effects to non-vascular aquatic plants. Until these data are available, the registration decision will
be based on the information listed on the label. The l ack of these data will limit the flexibility the Agency and registrants have in coming into compliance with the Endangered Species Act, and could result in use restrictions for thiodicarb which may otherwi se be avoided, or which are unnecessarily severe.