### -2 of 75- 

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



# N

O O N S H

CAS Registry Number: 16752-77-5 PC Code: 090301

Prepared by: Melissa Panger, Ph.D., Biologist Greg Orrick, Environmental Scientist Reviewed by: R. David Jones, Ph.D., Senior Agronomist Thomas Steeger, Ph.D., Senior Biologist Mark Corbin, Acting 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



### July 16, 2010

### -3 of 75- Table of Contents

1. Purpose....................................................................................................................................... 4 2. Problem Fo rm ulation ........................................................................................................ ......... 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.................................................................................... 13 3.4. Water Quality

............................................................................................................ ........ 17 4. Receptors.................................................................................................................................. 17 4.1. Effects to Aquatic Organisms ........................................................................................... 18 4.2. Effects to Terrestrial Organisms ....................................................................................... 20 4.3. Incident Databases Review............................................................................................... 23 4.4. Ecosystems Potentially at Risk ......................................................................................... 24 5. Assessment Endpoints ............................................................................................................. 25 6. Conceptual Model.................................................................................................................... 25 6.1. Risk Hypothesis ................................................................................................................ 26 6.2. Conceptual Diagram ......................................................................................................... 26 7. Analysis Plan .............................................................................................................. ............. 28 7.1. Stressors of Concern ......................................................................................................... 29 7.2. Measures of Exposure....................................................................................................... 29 7.3. Measures of Effect ............................................................................................................ 30 7.4. Integration of Exposure and Effects ................................................................................. 31 7.5. Deterministic and Probabilistic Assessment Methods...................................................... 32 7.6. Endangered Species Assessments..................................................................................... 32 7.7. Drinking Water Assessment ............................................................................................. 32 7.8. Preliminary Identification of Data Gaps........................................................................... 33 7.8.1. Fate............................................................................................................................. 33 7.8.2. Effects Data................................................................................................................ 35 8. References................................................................................................................................ 39 APPENDIX A: Registered Uses a nd Application Rates for Methom yl...................................... 47 APPENDIX B. Toxicity Data for Methomyl:.............................................................................. 57 APPENDIX C. Schematic for Assessing E xposure from Methomyl Scatter Bait Uses.............. 67 APPENDIX D. Major Environmental Degradates of Methomyl. ............................................... 68 APPENDIX E: Data Call-In Tables............................................................................................. 70

### -4 of 75- 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 methomyl, considering its currently registered uses. Methomyl is an N-methylcarbamate ins ecticide currently registered for use on a wide variety of sites including field, vegetable, and orchard crops; tu rf (sod farms only); livestock quarters; commercial premises; and refuse cont ainers. There are no residential uses for methomyl. Some formulations of methomyl are cl assified as “restricted use” pesticides and can only be applied by certified applicators. This document will provide a plan for analyzing data relevant to methomyl and for conducting environmen tal fate, ecological ris k, endangered species, and drinking water exposure assessments for its registered uses. Additionally, this problem formulation is intended to identify data gaps, uncertainties, and potential assumptions used to address those uncertainties relative to characte rizing the ecological risk associated with the registered uses of methomyl.

2. Problem Formulation

2.1. Nature of Regulatory Action

Under the F ederal 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 methomyl to dete rmine 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

Several ecological risk assessm ents for methom yl have been completed since it was first registered in 1968. The most encompassing asse ssment was for the Reregistration Eligibility

### -5 of 75- Decision (RED) process and was completed in 1998 (USEPA 1998 b ). The current risk assessment builds upon the 1998 risk assessment, whic h determined that acute and chronic risk quotients (RQ) exceeded risk levels of concern (LOC) for endangered/threatened birds (and, thus, reptiles and terrestrial- phase amphibians), mammals, and a quatic vertebrates (and, thus, aquatic-phase amphibians) and invertebrates.

The Agency consulted with the U.S. Fish a nd Wildlife Service in 1989 regarding methomyl impacts on some endangered specie s (USFWS 1989). As a result, the U.S. Fish and Wildlife Service issued a formal Biological Opinion that identified reasonable an d prudent measures and alternatives to mitigate effects of methomyl use on endangered species.

Subsequent to the RED, the registrant submitted several studies including, but not limited to, two predatory mite studies (MRID 451255-01, 451255-02); two aphid studies (MRID 451333-01, 451333-02); two earthworm studies (MRID 454592-01, 449693-01); and an acute oral and contact honey bee study (MRID 450930-01). These studies have been reviewed and will be incorporated into the risk assessment. The a ssessment will also build on the previous RED by incorporating open literatu re (from the ECOTOX search engine ) and assessing indirect effects, including those effects caused by the potential loss of food items ( e.g ., terrestrial and aquatic invertebrates).

On April 1, 2003, the Agency initiated formal c onsultation with the Natio nal Marine Fisheries Service relative to an effects determination regarding methomyl’s pot ential effects to 26 Environmentally Significant Units (ESUs) of Pa cific salmon and steelhead. That assessment determined that use of methomyl would have no effect (NE) on two ESU’ s based on lack of use in proximity to waters supporti ng these two ESUs and that methomyl was Likely to Adversely Affect (LAA) 24 ESUs both directly and indirectly based on effect s to the aquatic invertebrate prey base. In response to the Agency's effect s determination and consultation, NMFS issued a Biological Opinion (BO) in 2009 (NMFS, 2009). In the BO NMFS concluded that the use of methomyl is likely to jeopardize the continue d existence of 18 salmonid ESUs and destroy or adversely modify designated crit ical habitat for 16 species. To achieve the protections sought under the reasonable and prudent alternatives pr oposed by NMFS, the agency plans to implement several measures that would be accomplished by changes to pesticide labeling. These include buffers (that will vary depending on application rate, spray droplet size, and water body size), wind speed restrictions (applications will not be permitted when winds are >10 mph immediately prior to application); and soil mo isture restrictions (the pestic ide may not be applied when soil moisture is at field capacity or when a storm ev ent that could cause runoff is forecast to occur within 48 hours following application). Additiona lly, the Agency will require that incidents of fish mortality which occur within four days of application and in the vicinity of a methomyl application in the Pacific Northwes t be reported to the pesticide regi strant who is then required to submit the information to the Agency [under 6(a)(2)] (USEPA, 2010).

On July 20, 2007, the Agency submitted a risk assessment and effects determination to the United States Fish and Wildlife Servi ce for the California red-legged frog ( Rana aurora draytonii ) (CRLF) (and its designated cr itical habitat) relative to the use of methomyl in California. A LAA effects determination was made based on the potential for direct effects to both aquatic- and terrestrial-phase CRLF and the pot ential for indirect eff ects to prey taxa (for

### -6 of 75- both aquatic- and terrestrial-phase CRLF). Additionally, a ‘habitat modification’ effects determination was made for CRLF designated critical habitat based on the pot ential for effects to prey items for both aquatic- and terrestrial-phase CRLF.

2.2.2. Drinking Water Exposure Assessments

Drinking water exposure assessm ents conducted for methomyl and thiodicarb (which degrades into two methomyl molecules; USEPA 1997 a and 1997 b ; DP barcodes not reported) were conducted in May, 1997 in support of the 1998 RE D. The respective 1-in-10-year peak estimated drinking water concentrations (EDW C) of methomyl in surface water for the maximum use patterns of methomyl or thiodica rb were 99 μg/L or 151 μg/L. Non-targeted monitoring data indicated that me thomyl was detected in ground wa ter at concentrations up to 20 μg/L (the highest value was detected in drinki ng water in Suffolk County, New York) and in surface water at concentrations up to 1.9 μg/L (the highest value wa s detected in South Florida).

In 2007, the Agency conducted a surface wate r drinking water exposure assessment for thiodicarb and methomyl in whic h thiodicarb was assumed to rapidly degrade to methomyl. While exposure was estimated for applications of thiodicarb and/or methomyl, estimated concentrations represented methomyl only (USEPA 2007 a ; DP 339492). Monitoring data were not assessed. Resulting 1-in-10-year peak ED WCs for the maximum use patterns were 99 μg/L from use of methomyl, 86 μg/L from use of thiodicarb, and 69 μg /L from separate applications of both compounds on the same crop.

Most recently, a surface water dr inking water exposure assessment for use on lettuce alone was conducted in 2009 (USEPA 2009; DP 365917). The re sulting 1-in-10-year peak EDWC for the maximum use pattern was 220 μg/L. Assessment of the remaining labeled uses of methomyl is expected to be completed in 2010.

A cumulative human health risk assessment (C RA) for the N-methylcarba mate (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 methomyl and thiodicar b, presuming the risk mitigations proposed in the individual chemical REDs are implemented.

### -7 of 75- 3. Stressor Source and Distribution

Methom yl is registered for use on a wide variet y of sites including field, vegetable, and orchard crops; turf (sod farms only); livest ock quarters; commercial premises ; and refuse containers. As in previous ecological assessmen ts conducted by the Agency for methomyl, methomyl resulting from the degradation of thiodicarb will not be considered in the ecological risk assessment conducted as part of the Registra tion Review process. However, the potential simultaneous use of methomyl within the same areas as thiodicarb will be considered. Modeled exposure estimates resulting from methomyl use (and potentia lly any thiodicarb use in the vicinity) will reflect the predicted environmental fate of the parent alone since ther e are no degradates of toxicological concern for methomyl.

3.1. Mechanism of Action

Methomyl is an N-methylcarbamate insecticid e. Carbamate insecticides act by inhibiting acetylcholinesterase, thereby reducing the degr adation of the cholinergic neurotransmitter acetylcholine. As a result, intersynaptic con centrations of acetylcholine increase as the neurotransmitter accumulates leading to increased firing of the postsynaptic neurons. This may ultimately lead to convulsions, paralysis, and de ath of an organism exposed to the chemical.

3.2. Overview of Pesticide Use and Usage

Methomyl was first registered in the United States in 1968. Methom yl is currently registered for use on a wide variety of sites in cluding field, vegetable, and orch ard crops; turf (sod farms only); livestock quarters; commercial premises; and refuse containers (see Table 3.1 ). Seven end-use products containing methomyl are currently regi stered for use in the United States (see Table 3.2 ). Three of the end-use products are for agri cultural use and are labelled ‘restricted use’ (Methomyl 5G Granules, Lannate ® 

### LV and Lannate ® 

### SP), indicating that only certified pesticide applicators are legally allowed to apply the pr oduct. The other four end-use products are for scatter bait/bait station uses a nd are not labelled ‘restricted use’ . Low volume aerial applications (a minimum of 1 gallon of tank mixture/acre ) are allowed for a variety of non-orchard agricultural uses (see APPENDIX A ). For the purposes of this assessment ‘agricultural uses’ refer to all field and vegetable cr ops and sod farms. Orchard uses are analyzed separately from other agricultural uses because of their different use patterns.

### -8 of 75- TABLE 3.1. Summary of the Methomyl Us es Considered in Registration Review.
USE CATEGORY USES

Agricultural Alfalfa, anise, asparagus, barley, beans (succulent and dry), beets, Bermuda grass (pasture), blueberries, broccoli, broccoli raab, Brussels sprouts, cabbage, carrot, cauliflower, celery, chicory, Chinese br occoli, Chinese cabbage, collards (fresh market), corn, corn (sweet), corn (field an d popcorn), corn (seed), cotton, cucumber, eggplant, endive, garlic, horseradish, leafy green vegetables, lentils, lettuce (head and leaf), lupine, melons, mint, nonbearing nursery stock (field grown), oats, onions (dry and green), peanuts, peas, peppers, potato, pumpkin, radishes, rye, sorghum, soybeans, spinach, sugar beet , summer squash, sweet potato, tobacco, tomatillo, tomato, turf (sod farms only), wheat Orchard Apple, avocado, grapefruit, lemon, n ectarines, oranges, peaches, pears (northeastern U.S. only), pecans (southeastern U.S. only), pomegranates, tangelo, tangerine Non-Agricultural Bakeries, beverage plants, broiler houses, canneries, commercial dumpsters which are enclosed, commercial use sites (unspecified ), commissaries, dairies, dumpsters, fast food establishments, feedlots, food proce ssing establishments, hog houses, kennel, livestock barns, meat processing establis hments, poultry houses, poultry processing establishments, restaurants, supe rmarkets, stables, warehouses

### -9 of 75- Table 3.2. Currently Registered Methomyl End-Use Products.

FORMULATION EPA REG. NO. % ACTIVE METHODS OF APPLICATION USE RESTRICTIONS

LANNATE ® SP (There are 15 SLNs) 352-342 90% by weight Ground Aerial - Do not apply through any type of irrigation system - Do not apply by ground equipment within 25 ft, or by air within 100 feet of lakes, reservoirs, rivers, estuaries, commercial fish ponds, and natural, permanent streams, marshes, or ponds (increase buffer to 450 ft with ultra low volume application). - Use only in commercial and farm plantings (not for home plantings or for U-Pick operations). - Use of hand held application equipment is prohibited.
LANNATE ® LV

(There are 3 SLNs) 352-384 29% by weight (2.4 lbs a.i./gallon) Ground Aerial Chemigation - Overhead sprinkler chemigation is allowed for alfalfa, barley, succulent and dried beans, oats, onion, succulent peas, pota toes, rye, sweet corn (not in CA), sugar b eets, and wheat. Drip chemigation is allowed for onions. Refer to supplemental label, Special Local Need (SLN) label, or crop specific s ections of this label for direction for chemigation. Do not apply this product through any other type of irrigation systems, except those allowed by instructions provided in supplemental, SLN or this product label. - Do not apply by ground equipment within 25 ft, or by air within 100 feet of lakes, reservoirs, rivers, estuaries, commercial fish ponds, and natural, permanent streams, marshes, or ponds (increase buffer to 450 ft with ultra low volume application).

- Use only in commercial and farm plantings (not for home plantings or for U-Pick operations). - Use of hand held application equipment is prohibited. FARNAM DIE FLY TM 270-255 1% Scatter bait Bait station
STIMUKIL ® FLY BAIT 53871-3 1% Scatter bait Bait station Brush on paste
LURECTRON ®

SCATTERBAIT 7319-6 1% Scatter bait Bait station Paste GOLDEN
MALRIN ® RF-128 FLY KILLER 2724-274 1.1% Scatter bait Bait station - Not to be used inside or around homes, or any other place where children or pets are likely to be present. - Place scatterbait in areas inaccessible to livestock. Keep children and pets out of treated areas. Do not place scatte rbait around commercial dumpsters that are not enclosed. - Bait stations should be at least 4’ above ground and in areas not accessible to children, pets, and livestock. - Brush paste on outside of structures so that it is inaccessible to children, pets, and livestock. METHOMYL 5G GRANULES

(granular) 57242-2 5% Ground, banded application - Do not apply within 25 ft of lakes, reservoirs, rivers, estuaries, commercial fishponds, and natural, permanent streams, marshes or natural, permanent ponds. - Not for use in home plantings or U-Pick operations.

### -10 of 75- For agricultural and orchard uses, the maximum single application rate allo wed on the labels is 0.9 pounds of active ingredient per acre (lbs a.i. /A), which is the most common single maximum application rate for all agricultural uses (see Table 3.3 for a summary and APPENDIX A for a complete list of registered us es and application rates).

Table 3.3. Application Rates a nd Intervals for Methomyl Uses.

USES MAXIMUM SINGLE APPLICATION RATE (lbs ai/A) # APPLICATIONS/ CROP MINIMUM APPLICATION

INTERVAL

Alfalfa, lupine 0.9 5 5

Avocado 0.9 1 5

Grapefruit, lemon, oranges, tangerines, tangelo 0.9 3 5

Broccoli, Chinese broccoli, broccoli raab, cabbage, Chinese cabbage, cauliflower, horseradi sh, leafy green vegetables 0.9 8 2

Corn (field and popcorn), corn (seed), corn (sweet), corn 0.45 14 1

Cotton 0.675 2 3

Apples, nectarines, peach es, pomegranates 0.9 6 5

Garlic 0.45 6 5

Brussels sprouts, chicory, e ndive, escarole, lettuce (head), lettuce (leaf), spinach 0.9 8 2

Cucumber, eggplant, melons, pu mpkin, summer squash 0.9 6 5

Nonbearing fruit, grape, and nut nursery stock 0.9 5 5

Onions (green), onions (bulb), radishes 0.9 6 5

Potato, sweet potato 0.9 5 5

Bermuda grass (pasture) 0.9 1 5

Anise, asparagus, beans (succulent), beans (interplanted with nonbearing almonds, plums, prun es, peaches and walnuts), beets (table), carrots, celery, le ntils, peas (succulent), peppers, soybeans, soybeans (interpl anted with nonbearing almonds, plums, prunes, peaches and walnuts) 0.9 8 5

Sugar beet 0.9 5 5

Tomato, tomatillo 0.9 7 5

Sod farms 0.9 4 5

Barley, oats, rye, sorghum, wheat 0.45 4 5

Blueberries 0.9 4 5

Mint 0.9 2 5

Scatter bait 0.22 26 3 5

### -11 of 75- Maximum seasonal labeled application rate s (indicated on the label as maximum application rates per crop ) for agricultural uses range from 0.9 lbs a.i./A/crop [ i.e ., Bermuda grass (pasture), avocado, lentils, beans (interplanted with trees), sorghum, and soybeans (interplanted with trees)] to 7.2 lbs a.i./acre/crop [ i.e ., cabbage, lettuce (head), caulifl ower, broccoli raab, celery, and Chinese cabbage].

Several methomyl crops can be grown more th an one time per year in the United States ( i.e., they have multiple crop cycles). Therefore, for those methomyl uses that have more than one crop cycle per year, the maximum allowable yearly application rate will be higher than the maximum seasonal application rate. For perennial crops ( e.g ., alfalfa), the number of cuttings per year may be considered the number of crop cycles per year . The maximum number of times a crop can be grown in California will be used to represent other areas of the United States where multiple croppings can occur ( e.g., Texas and Florida). Considering the labeled applic ation rates and information from the Agency’s Office of Pestic ide Programs’ Biological and Economic Analysis Division (BEAD) on the number of times each crop for which methomyl is registered for use can be grown in California (USEPA, 2007), the maximum annual application rates for methomyl are 32.4 lbs a.i./acre/year (alfalfa) and 21.6 lbs a.i. /acre/year (broccoli raa b, cabbage, and Chinese cabbage) for agricultural crops; 5.4 lbs a.i./acre/year (peach es) for orchards; and 0.22 lbs a.i./acre/application for non-agri cultural uses (no maximum applic ation/acre/year is provided on the non-agricultural us e labels). Maximum annual applicatio n rates for other areas of the United States will differ to the degree that the number of crops per year in these areas differs from that in California. Additional information that identi fies the number of crops (for which methomyl is registered) per year that can be grown in areas outside of Cali fornia would help reduce the uncertainty associated with estimating maximum y early application rates at a national-level in the risk assessment conducted for Registration Review.

All orchard and most agricultural uses invol ve foliar application. The only granular agricultural/orchard use is for corn (which also has a foliar use). Since the maximum seasonal application rate for methomyl use on corn is th e same for the foliar and granular formulations and no spray drift is expected for granular use, the granular use is expe cted to yield equal or lower EECs when compared to the foliar use. Therefore, we will only evaluate foliar applications for corn in this assessment.

All non-agricultural and non-orchard outdoor uses for methomyl are limited to scatter baits and bait stations around agricultural ( e.g ., animal premises) and commercial structures and commercial dumpsters, where children or animals are not likely to contact the pesticide. The scatter bait can also be mixed with water to form a paste which can be brushed onto walls, window sills, and support beams. Since the bait st ation use involves placi ng the pesticide within the bait station and hanging the ba it station at least four feet o ff the ground (as stipulated on the labels), no spray drift or runoff is expected from this use.

For scatter bait uses that do not involve bait st ations, no off-site exposure via spray drift is expected from the scatter bait uses since they are granular (or a paste) . However, there is potential for off-site exposure via runoff from sc atter bait uses. The maximum application rate for the scatter bait use is 0.22 lbs a.i./A (0.0025 lbs a.i./500 ft 2 

### ). It is unlikely that applications would involve a full acre, however , since the outside use of the scatter bait is limited to areas

### -12 of 75- around structures and dumpsters. No minimum app lication interval or ma ximum application rate per year is provided on the scatter bait labels. Because there is poten tial exposure to the environment, the scatter bait uses that do not invo lve bait stations will be assessed in the risk assessment conducted for Registration Review.

According to the United States Geological Surv ey’s national pesticide usage data (based on information from 1999 to 2004), an average of 576,926 lbs of methomyl per year are applied nationally to agriculture in the United States (see Figure 3.1 ). Based on these data, approximately 21% of the average pounds of methomyl used per ye ar is applied to sweet corn, approximately 13% is applied to lettuce, and from 3% to 6% is applied to dry onions, peanuts, alfalfa hay, tomatoes, green beans, cucumbers and pickles, strawberries , and cotton. Based on a Screening Level Usage Analysis co nducted by the Agency (USEPA 2009 a ), using data from 2001 to 2007, there is an estimated 800,000 pounds of methomyl used per year [most of which is used on sweet corn (200,000 lbs), lettuce ( 100,000 lbs), onions (70,000 lbs) and tomatoes (50,000 lbs)].

FIGURE 3.1. Estimated, Annual, National , Agricultural Methomyl Usage (USGS 2010). [ The pesticide use maps available from this site show the average annual pesticide use intensity expressed as average weight (in pounds) of a pesticide applied to each s quare 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 Re search Institute based on information collected during 1999 through 2004

### -13 of 75- 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

Methomyl (S-methyl-N-(methylcarbamoyl)oxy)th ioacetimadate; CAS No. 16752-77-5; PC code 090301) is a registered pesticide as well as the prim ary degradate of another registered pesticide, thiodicarb. The dominant routes of dissipation of methomyl are metabolism, leaching, and runoff. Environmental fate and transport properties of methomyl are summarized in Table 3.4

. Because of its low affinity for adsorption (K OC 

### of 46 L/kg OC 

### ), methomyl is likely to dissipate rapidly through washoff from plant surfaces and through leaching and runoff from soil surfaces. Methomyl has fate characteristics, which are moderate persistence, high water solubility, and low sorption coefficient, that suggest transport to waters resources is likely. Methomyl’s persistence in water bodies is uncertain; however, the compound undergoes substantial hydrolysis only in alkaline water approximately pH 9 or above.

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

Parameter Value Source Physical/Chemical Parameters Molecular weight 162.2 g/mol (calculated) Solubility in water (25°C) 5.5 x 10 4 

### mg/L MRID 41402101 Vapor pressure (25°C) 5.4 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
Persistence in Water pH 2.09-7.11: >413 d pH 8.88: 14.6 d pH 7.40: 337 d pH 8.89: 16.1 d pH 7.67: 206 d pH 9.45: 4.77 d pH 7.92: 123 d pH 9.92: 1.66 d pH 8.42: 40.8 d Strathmann and Stone, 2002 (values calculated from rate constants) Hydrolysis half-life (25°C)

pH 5: no evidence of degradation pH 7: no evidence of degradation pH 9: 36 d MRID 00131249

Aqueous photolysis half-life 50 d (natural water) 4.9 d – stable (pH 7 buffer w/ 0-1000 M excess nitrate) MRID 43823305 B



### Persistence in Soil Flanagan silt loam: 44 d (109 d) MRID 00008568 Aerobic soil metabolism half-life of parent (of total residues A 

### ) Madera, CA loam: 12 d (25 d) MRID 43217901
Anaerobic soil metabolism halflife (of total residues A 

### ) Madera, CA loam: 14 d (47 d) MRID 43217902

Soil photolysis half-life 33 d MRID 00163745 Mobility Organic carbon-normalized adsorption coefficient (K OC 

### ) 46 ± 13 L/kg OC 

### (n=4) MRID 00161884

### -14 of 75- Parameter Value Source Field DissipationTerrestrial field dissipation halflife (from surface) 54 d (CA sandy loam cropped to cabbage); leached to deepest sample depth (60-90 cm) 4-6 d (MS loam cropped to cabbage); leached to 15-30 cm sample depth MRID 41623901/ 41623902 MRID 42288001/ 43217903 0.5 d (mint) Kiigemagi and Deinzer, 1979 Foliar degradation half-life

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

A Total residues include the parent compound and unextracted residues.

B These data are provisional, as the study is under review.



### 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 of 16 or 36 d) at pH 9 based on two studies. Methomyl degrades in clear water by indirect photolysis ( i.e. , oxidation from exposure to photoproducts of dissolved nutrients) that is moderate to rapid (half-life range of 5-50 d), depending on the nature of the dissolved oxidants. Biodegradation is moderate in soil and uncertain in water. In the presence of ferrous iron, methomyl is unstable. Field studie s show varying dissipation rates of the chemical in soils. Dissipation rates were related primarily to differences in soil moisture content, which may have affected the microb ial activity, and water inputs ( i.e. , rainfall and irrigation), which could have influenced leaching.

Chemical and Metabolic Degradation. A guideline hydrolysis study (MRID 00131249) conducted for 30 days did not show evidence of degradation by hydrolysis at pH 5 and 7 and only slow degradation in pH 9 buffe red solutions with a half-life of 36 days. Open literature data (Strathmann and Stone, 2002) confirm that me thomyl does not substantially degrade by hydrolysis at pH 5 and 7. However, hydrolysis was observed at pH 8.9 with a half-life of 16 days. The major hydrolysis degradate in the gu ideline study was methom yl oxime with up to 44% of the applied after 30 days (degradate names, structures, and reported amounts are in Table D.1 of Appendix D ).

Methomyl degrades by indire ct photolysis in water ( i.e. , oxidation from exposure to oxidant photoproducts of dissolved nutrients) at a variable rate depending on the nature of the dissolved oxidants, according to a study in review (half-lives of 4.9 to 50 d; degradates weren’t identified; MRID 43823305). There was no measureable degradation in the dark controls or in an irradiated system buffered at pH 7. In separate studies wi th poor material balances, the major degradates were acetonitrile, found at 55-68% of the applie d radioactivity 2-15 days after treatment (MRID 6161885), or methomyl oxime, found at up to 32% of the applied 14 days after treatment, and carbon dioxide, found at 56% of the applied at st udy termination, 56 days after treatment (MRID 22439). Methomyl degraded moderately by photoly sis on soil (half-life of 33 d; MRID 163745). Acetonitrile was the major photolysis degradate on soil, with a peak concentration of 40% of the applied at study terminati on, 30 days after treatment.

In two aerobic soil metabolism studies, methomyl degraded with half-lives of 44 days in a Flanagan silt loam and 12 days in a loam soil from Madera, Ca lifornia (MRID 8568, 43217901). The major degradate was 14 

### CO 2 

### (23% of the applied after 45 days in the silt loam soil, and 75%

### -15 of 75- of the applied at 3 months in the loam soil). Un extractable residues peaked at 26% of the applied 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 unextract ed, unidentified materi al as if it were parent (total residues method) are 109 and 25 days for the Flanagan an d Madera soils, respectiv ely. Methomyl oxime was a minor degradate accounting for  3% of the applied.

Under anaerobic conditions, methomyl degraded in lo am soil with a half-life of 14 days in static conditions (nitrogen atmosphere) and 13 days in dynamic conditions (flowing nitrogen atmosphere) following 14 days of aerobic inc ubation (MRID 43217902). 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 additi onal 23% after 60 days of anaer obic incubation. Unextracted residues peaked at 36% of the applied after 7 days of anaer obic incubation. More rapid degradation under anaerobic conditi ons may be catalyzed by the pr esence of dissolved (ferrous) iron (MRID 43708806; Smelt et al. , 1983; Bromilow et al. , 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



### 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, respect ively. However, results from these systems were uncertain due to low material balances from 14 to 102 days after treatment. 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 potentials and were neither completely aerobic nor an aerobic. Unextracted and unident ified residues in the sediment were a significant component of the radioactive residues in these experiments with up 16% in the Auchingilsie system and 20% in the Hinchingbr ooke system. The unextracted residues were decreasing with time at the end of the experiment in both systems indicating that these residues were still available. Half-lives estimated by combining the methomyl parent with the unextracted residues (total toxi c residues method) were 6.3 days for Auchingilsie and 7.4 days for Hinchingbrooke. Methomyl oxime was a maximum of 13% of th e applied at 2 days and did not persist. Acetonitrile was a maximum of 21% of the applied at 7 days in solution, and a maximum of 27% of the applied at 60-102 days in the volatile traps. Acetamide and carbonate accounted for up to 14% of the applied (at day 7) and 15% of the applied (at day 14), respectively. 14 

### CO 2 

### comprised 46% of the applied by study termination (day 102).

The only non-volatile degradate f ound in the laboratory studies was methomyl oxime. It was present at high concentrations in the alkaline hydrolysis st udy, one photolysis study, and the aerobic aquatic metabolism study, but was only a mi nor degradate in the soil metabolism studies (  3% of the applied at all test intervals).

Several studies showed that dissipation of methomyl is rapid on foliage (Willis and McDowell, 1987). Of the ten studies for methomyl identified in this review of fo liar dissipation, three

### -16 of 75- measured total residues on the leaves rather th an dislodgeable residues . 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 dissipa ted and volatilization 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 demons trated by soil thin-layer chromatography (TLC; R f 

### values 0.64-0.79; MRID 44306). A batch equilibrium study shows that methomyl has a low affinity to bind to soil (see Table 3.5 ), further indicating that the chemical will be mobile (MRID 161884). Methomyl binding (which is low) is si gnificantly correlated with soil organic carbon content, with a mean K OC 

### of 46 ± 13 L/kg OC



### .
TABLE 3.5. Summary of Soil Batch E quilibrium Parameters for Methomyl. A



### Soil Fraction of Organic Carbon Mean K d 

### K OC 

### K F 

### 1/n K FOC 

### Cecil sandy loam 0.012 0.79 65 0.73 0.85 61 Flanagan silt Loam 0.025 1.1 45 1.0 0.87 41 Keyport silt loam 0.043 1.6 36 1.4 0.86 32 Woodstown sandy loam 0.006 0.24 39 0.23 0.88 37

A K d is the soil-water partition coefficient. K OC is the organic carbon-normalized partition coefficient based on mean K d ’s. K F is the Freundlich coefficient. 1/n is the Freundlich exponent. K FOC is similar to K OC except based on Freundlich coefficients



### Methomyl is a highly soluble chemical in water (5.5 x 10 4 

### mg/L; MRID 41402101). Its vapor pressure (5.4 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 volat ilize (MRID 41209701).

Bioaccumulation. The low octanol/water partition coe fficient of 1.31 ± 0.02 (mean ± std. error; MRID 157991) suggests that the chemical will have a low tendency to accumulate in aquatic biota.

Field Dissipation. Two guideline terrestria l field dissipation studies ar e available for methomyl (MRID 41623901/41623902, 42288001/43217903). Dissipation half -lives from the surface soil of cropped cabbage fields ranged from 4-6 days in Mississippi to 54 days in California. Two factors may explain the differences in dissipation between the two sites. Soil moisture content, which may affect the level of biological activity, varied between the two sites (moisture contents ranged from 2.5% to 17% in the California soils and averaged 16% over th e first 15 days in the Mississippi soils). The Mississipp i site received more rainfall, which 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). Lannate L, a formulat ed product of methomyl, was applied in August 1992 to a site cropped in sweet corn in Cook County, Ge orgia. Monitoring continued until October 1994 when the study was terminat ed. The study was co nducted by DuPont in a highly vulnerable, high use area of Georgia. Methomyl was applied to the crop at 0.45 lbs

### -17 of 75- a.i./A 25 times over 63 da ys for a total of 11.25 lb s a.i./A. Although this rate represents 1.5x the maximum label rate per crop of sweet corn, the st udy was conducted to sup port a potential increase in the maximum label rate. Grou nd water was monitored monthly for a period of 27 months. Methomyl was not detected in ground water when detections occurred in 12-foot depth suction lysimeters at concentrations up to 0.943 μg/L . Out of the 156 samp les taken from six downgradient wells in this study, on ly six samples from five wells contained methomyl residues. Concentrations ranged fr om 0.110 to 0.428 μg/L, using a detection limit of 0.1 μg/L, at 62 and 117 days after the initial treatment (D AIT). Sampling continued for 789 (DAIT), but no detections were seen after 117 DAIT.

3.4. Water Quality

Thiodicarb and methomyl are no t identified as causes 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 April 22, 2010). 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.tm dl_pollutant_de tail?p_pollutant_group_id =885&p_pollutant_group_name=PESTICIDES , accessed April 22, 2010). More information on impaired water bodies and TMDLs can be found at http://www.epa.gov/owow/tmdl/ . The Agency invites subm ission 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/novem ber06/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 Docum ent (USEPA 2004), the risk assessment for methomyl relies on a surrogate species approach. Toxicological 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.

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 methomyl 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 methomyl on biotic communities from loss of species that are sensitive to the chemical and from changes in structure and functiona l characteristics of the affected communities. Open literature data from an ECOTOX run conducted on 3/17/07 for methomyl have been fully reviewed as part of this Problem Formulation. Information from an

### -18 of 75- up-dated ECOTOX run for methomyl will be evaluated for possible quantitative and/or qualitative inclusion in the risk assess ment in support of Registration Review.

A summary of the most sensitive data representing non-target orga nisms exposed to methomyl in aquatic and terrestrial habitats is provided in Section 4.1. A summary of ecological incidents associated with methomyl and a description of ecosystems potentially at risk are provided in Section 4.2.

4.1. Effects to Aquatic Organisms

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 4.1 ). A summary of all available ecotoxicity data for methomyl is provided in Appendix B . 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, an d estuarine/marine invert ebrates. No toxicity data from chronic exposure to methomyl are avai lable for the most acutely sensitive freshwater fish species, the channel catfish ( Ictalurus punctatus ) (LC 50 

### = 0.320 mg a.i./L). Therefore, an acute-to-chronic ratio (ACR) is used to calculate a chronic fr eshwater fish endpoint using acute and chronic data from the fathead minnow (for which both acute and chronic toxicity data are available). The most sensitive no observed adve rse effect concentration (NOAEC) and lowest observed adverse effect concentration (LOAE C) for freshwater fish [fathead minnows ( Pimephales promelas )] are 0.057 and 0.117 mg a.i./L, respec tively, based on reduced survival (MRID 131255). The ACR for fathead minnow, i.e . ACR = 26.3, 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 we t weight. Fish with deformed bodies and lethargy/erratic swimming were noted at 1.0 mg a.i./L. No other s ub-lethal 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 concentration.

For estuarine/marine invertebrates, the most acutely sensitive species tested is the northern pink shrimp ( Penaeus duorarum ) (LC 50 

### = 0.019 mg a.i./L). Since no toxicity data from chronic exposure to methomyl are available for the norther n pink shrimp, an ACR is used to calculate a chronic estuarine/marine endpoint using acu te and chronic data from mysid shrimp ( Americamysis bahia ) (for which both acute and chronic data are available). The most sensitive no observed adverse effect concentration ( NOAEC) and lowest obser ved adverse effect concentration (LOAEC) for mysid shrimp ar e 0.0291 and 0.0591 mg a.i./L, respectively, based

### -19 of 75- on reduced number of young per surviving female (MRID 450132-03). The ACR for mysid shrimp, i.e . ACR = 8.07, results in a NOAEC of 0.0024 mg a.i./L for the northern pink shrimp [(0.234 mg/L)/(0.029 mg/L) = (0.019 mg/L)/(x μ g/L)].

TABLE 4.1. 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 Fathead minnow LC 50 (1.5 mg/L) divided by the NOAEC (0.057 mg/L) yields an ACR of 26.3; ACR of 26.3 in turn divided into the channel catfish LC 50 (0.320 mg/L) yields an estimat ed chronic NOAEC (0.102 mg/L) for channel catfish.

1 Mysid shrimp LC 50 (0.234 mg/L) divided by the NOAEC (0.029 mg/L) yields an ACR of 8.07; ACR of 8.07 in turn divided into the northern pink shrimp LC 50 (0.019 mg/L) yields an estimated chronic NOAEC (0.0024 mg/L) for northern pink shrimp.



### An outdoor microcosm study (MRID 437444-02) was conducted with the formulated methomyl product Lannate L [24% a.i. (methomyl)] to eval uate the fate in tank water and hydrosoil and assess the effects on populations of phytoplankto n, zooplankton, macroinver tebrates, and bluegill sunfish ( Lepomis macrochirus ). Applications were performed over a period of 22 days (22 daily

### -20 of 75- applications) to 28 days (4 appli cations with a 7-day r eapplication interval); the total length of the study was 35 days. Treatment groups were de fined by the amount of test substance added at each application (0.48 or 0.048 g a.i.; test ve ssel volume = 5,900 L; nominal treatment concentrations were not provided) and by the interval be tween test substance applications [1 day (total of 22 applications), 3 days (total of 8 appl ications), or 7 days (tot al of 4 applications)]. Before the start of the study, each of the 56 tanks used in the study was stocked with bluegill sunfish and inoculated with aquatic plants and animals (invertebrates) from an untreated, preexisting pond on site, colonized by native invertebrates.

At the end of the study, phytoplankton showed no apparent methomyl-related effects. Zooplankton showed mixed results; the abunda nce of adult copepods 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. Bluegill survival wa s not affected in any of the microcosm treatment levels. Body length and body weight at harvest, however, were significantly reduced (up to 18.5%) at all methom yl treatment levels when compared with controls. The size reductions were attributed to a decrease in food resources, particularly cladocerans.

4.2. Effects to Terrestrial Organisms

Table 4.2 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. There are currently no methomyl vegetative vigor or seedling emergence toxicity data available for terrestrial plants.

An avian reproduction study was performed on methomyl with the northern bobwhite quail ( Colinus virginianus ). 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 ( Rattus norvegicus ), the NOAEL for parental systemic toxicity is 3.75 mg/kg-bw and the LOAEL is 30 mg/kg-bw based on decreased growth (body weight) and food consumption and altered hema tology parameters. The NOAEL for offspring toxicity is also 3.75 mg/kg-bw and the LOAEL is 30 mg/kg-bw base d on decreases in both survival (the mean number of live pups) and growth (mean body weights of offspring) (MRIDs: 43250701, 43769401).

### -21 of 75- TABLE 4.2. 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 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 lbs 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



### There are no acceptable terrestrial plant guidelin e toxicity studies available for methomyl, several efficacy studies that were conducted to test the effects of methomyl on a variety of target and non-target invert ebrate pests also supplied information on effects to plants after methomyl applications. Due to a lack of information on study design and data analyses, these efficacy studies are classified as ‘supplemen tal’ and are not adequate for pl ant (or terrestrial invertebrate) RQ calculation. None of the st udies showed any adverse effect s to plants at the highest treatment levels tested (most of which were at or above the maximum allowable single application rate for methomyl of 0.9 lbs a.i./a cre) and the NOAEC from the studies represented

### -22 of 75- the highest treatment rates examined (see Table 4.3 ). However, because none of the studies addressed potential risks to monocots, or e ffects on seedling emergence and some N-methyl carbamates are plant auxins a nd are used to thin fruit ( e.g ., carbaryl), risks to plants from the use of methomyl cannot be preclud ed using the available data.

TABLE 4.3. 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 MEASURED 2 ECOTOX NO./REFERENCE

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

≥ 3.6 lbs a.i./acre Yes Growth Injury 74745/Morale and Kurundkar (1989) Eggplant ( Solanum melongena )
≥ 1,000 ppm Yes Growth 89394/Sharma et al . (1997) Common Bean ( Phaseolus vulgaris ) ≥ 0.9 lbs a.i./acre Yes Injury 88838/Ghidiu (1988)

≥ 946 ml/acre Yes Growth 82231/Stansly and Cawley (1993)
≥ 0.9 lbs a.i./acre Yes Growth 82730/Schuster (1994) Bell pepper ( Capsicum annuum )
≥ 0.9 lbs a.i./acre Yes Biomass 82246/Zehnder and Speese (1992) Cabbage ( Brassica oleracea ) ≥ 0.9 lbs a.i./acre Yes Injury 88084/Edelson et al . (1999)

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

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

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

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

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

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

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

≥ 0.9 lbs a.i./acre Yes Injury 88062/Carson et al . (1999)
≥ 0.9 lbs a.i./acre Yes Injury 88089/Kund et al . (1999)
≥ 0.9 lbs a.i./acre Yes Injury 88089/Kund et al . (1999)
≥ 0.45 lbs a.i./acre Yes Injury 88269/Stansly et al . (1999) Tomato ( Solanum lycopersicum)

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

Wild celery ( Apium graveolens ) ≥ 0.9 lbs 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 Measured’ refers to the effect that was measured in the study. Because the NOAELs represent the highest level tested in each study, no adverse effects to plants were observed in any of the studies.

### -23 of 75- 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 February 17, 2010. A total of 10 incidents associated with methomyl use (not including those classified as ‘unlikely’ due to methomyl use) have been reported (8 involving terrestrial organisms – all birds -and 2 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, and possible in two incidents. Two of the incidents were the re sult of registered use, five were the result of misuse (intentional baiting); however, it is unknown if the other three in cidents resulted from misuse or registered uses. Specific deta ils 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. For methomyl, as of February 17, 2010, registrants have reported 7 minor fish and wildlife incidents, all of which occurred between 2000 and 2007. The number of individual organisms affected in these incidents was not specified. Unless additi onal information on these aggregated incidents become available, they will be assumed to be repr esentative of registered uses of methomyl 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 another of the incidents, which occurred in the British Virgin Islands and i nvolved the death of 13 gu lls and one cattle egret ( Bubulcus ibis ), was undetermined (Incident #: I1018980-10) . Oxamyl, which is classified as very highly toxic to birds on an acute exposure basi s, was also suspected in this incident. Two of the incidents occurred in France and involved th e registered use (in Fr ance) 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 spray of methom yl at a rate of 0.225 lbs a.i./acre. This incident, which was classified as ‘probable’, re sulted in the mortality of at least 52 finches. The other French incident (I006382-002; 1992) was also classified as ‘p robable’ and involved the registered use of methom yl (foliar spray) on cabbage. This incident involved the incapacitation of 31 birds and mort ality in 35 birds (finches and linnets) after the birds were observed drinking dew from the cabbage fiel d the day after methom yl application.

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

### -24 of 75- Aquatic Incidents

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; fenuron = 0.78 ppm; methomyl = 5.08 ppm; monur on = 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 concentrations of methom yl were found in water samples taken from the pond and pond-overflow area.

Due to limitations with data in the EIIS, a low number or lack of reported incidents in the database cannot be construed as evidence that additional incidents have not occurred. Incident reports for non-target plants and animals typically provide 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 reductions in state monitoring efforts due to lack of resources.

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.

### -25 of 75- 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

Assessm ent 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 a ). For methomyl, the ecological entities may include 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 m u 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 methomyl provides a wr itten description and visual representation of the predicted relationships betw een methomyl, 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 a ).

Based on the submitted environmental fate data, methomyl is not expected to volatilize or persist in soil or water; however, its persistence in acidic to pH neutral water is uncertain. The compound may potentially leach to ground water and move to surface water through runoff and spray drift. Methomyl is degraded mainly by metabolism and also slowly by photolysis in clear water and hydrolysis in alkali ne water approximately pH 9 or above. Due to its low K OW 

### value, methomyl is not expected to bioaccumulat e in aquatic or terrestrial food chains.

Based on previous ecological risk assessments for methomyl, there is the potential for risk for Federally listed threatened/endange red (hereafter referred to as “l isted”) birds (and, thus, reptiles and terrestrial-phase amphibians), listed and non-listed mammals, and aquatic vertebrates (freshwater and estuarine/marine) (and, thus, aq uatic-phase amphibians) and invertebrates. Because of the potential risk fo r direct effects to taxa (both listed and non-listed) described above, listed species in all taxa may potentially be affected indirectly due to alterations 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 conceptu al diagram discussed below.

### -26 of 75- 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 methomyl, 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, methomyl has the potential to reduce survival, reproduction, and/or growth in non-target terrestrial and aquatic organisms when used in accordance with the current labels. These non-target organisms include listed and non-listed species.

6.2. Conceptual Diagram

The environmental fate properties of methomyl i ndicate that runoff, spray drift and direct spray represent potential transport mechanisms to aquatic and terrestrial habitats where non-target organisms may be exposed. These transport mechanisms ( i.e ., sources) are depicted in the conceptual diagrams below ( Figures 6.1 and 6.2 ) along with the receptors of concern and the potential attribute changes in the receptors due to exposures of methomyl. Although methomyl may leach to ground water, it is not expected to persist long enough to contaminate the base flow of surface water bodies.

### -27 of 75- FIGURE 6.1. Conceptual Model for Met homyl Effects on Aquatic Organisms. Dotted Lines Indicate Exposure Pathways that Have a Low Likelihood of Contributing to Ecological Risk. 

### Stressor

Source

Receptors

Attribute Change Methomyl applied to use site

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 Community change Surface water/

Sediment Runoff

Aquatic Animals Invertebrates Vertebrates 

### Exposure Media

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

### -28 of 75- FIGURE 6.2. Conceptual Model for Methomyl Effects on Terrestrial Organisms . Dotted Lines Indicate Exposure Pathways that Have a Low Likelihood of Contributing to Ecological Risk.

7. Analysis Plan

In order to address th e risk hypot hesis, the potential for adverse effects on the environment will be estimated. The use, environmental fate, and ecological effects of methomyl will be characterized and integrated to assess the ri sks. Risk quotients (RQ) will be derived for methomyl by dividing estimated environmental concentrations (EEC) by the most sensitive endpoint from the relevant, availa ble toxicity data for 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. 

### Stressor

Source

Receptors

Attribute Change Methomyl applied to use site

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 / Amphibians

Ingestion

### -29 of 75- 7.1. Stressors of Concern

The residues of concern in this assessment will include methomyl and any degradates determined to be of toxicological concern. At this time, how ever, none of the degradates of methomyl are of toxicological concern. Modeled exposure es timates resulting from methomyl use (and potentially any local thiodicarb use) will reflect the predicted environmental fate of methomyl (and any residues of concern).

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 mixtur es of methomyl with other pesticides will be presented as part of the ecological risk assessmen t. It is expected th at the toxic effect of methomyl, in combination with other pesticides used in the environmen t, 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 methomyl and co -contaminant 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 methomyl exposures 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 ., field, vegetable, and orch ard crops; turf (sod farms only); livestock quarters; commercial premises; a nd refuse containers] as discussed in Section 3.2. Measures of exposure are based on aqua tic and terrestrial m odels that estimate environmental concentrations of methomyl using maximum labeled application rates and application methods that have th e greatest potential for off-site transport of the chemical. The models used to generate aquatic estimated envi ronmental concentrations (EEC) are the Pesticide Root Zone Model (PRZM) coupled with the EX posure Analysis Model System (EXAMS). The model used to produce terrestrial EECs on food items is T-REX. The mode l used to derive EECs relevant to terrestrial and wetla nd plants is TerrPlant. These models are parameterized using relevant reviewed registrant-submitted environmental fate data.

### -30 of 75- 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 methomyl that may occur in surfac e water bodies adjacent to application sites receiving methomyl thr ough 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 methomyl. 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 the effects to fish and aquatic-phase amphibians from chronic exposure. The 1-in-10-year 21-day mean is used for assessing the effects on aquatic invertebrates from chronic exposure.

For the scatter bait use pattern, the impervi ous and residential PRZM/EXAMS scenarios will post-processed to obtain EECs in accordance with the conceptual model described in APPENDIX C . The conceptual model includes the assu mption that 50% of the modeled area is impervious, and that 3% of the impervious area is treated.

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 methomyl 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.

### -31 of 75- Information on the potential effects of methomyl on non-target animal s is also collected from the Ecological Incident Information System (EIIS; USEPA 2007 c ). The EIIS is a database containing adverse effect (typic ally mortality) reports on non -target 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/ policy/pesticides/aim s/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 methomyl to birds is similar to te rrestrial-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 inte gration of exposure and ecological effect characterizations to determine the potential ecological risk from the use of methomyl and the likelihood of direct and indirect effects to non-target organisms in aquatic and terrestrial habitats. The exposure and effects data are integrated in order to evaluate pot ential adverse ecological effects on non-target species. For the assessment of me thomyl risks, the risk quotient (RQ) method is used to compare estimated exposure and measured toxicity values . Acute and chronic EECs are divided by acute and chronic toxicity values. Th e resulting RQs are then compared to the Agency’s Levels of

### -32 of 75- Concern (LOC) (USEPA 2004). Thes e criteria are used to indicat e when methomyl’s use, as directed on the labels, has the potential to cause a dverse direct or indirect effects to non-target organisms. In addition, incident data from EIIS , aggregate incident reports, and AIMS will be considered as part of the risk characterization.

7.5. Deterministic and Probabilistic Assessment Methods

The quantitative assessment of risk will primarily depend on the deterministic point estimatebased 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 deem ed 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 methomyl. 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 associ ated with the registration of methomyl 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 methomyl 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 methomyl. The drinking water assessment w ill incorporate model estimates of methomyl residues of concern, including methomyl and any degradates or predecessors determined of

### -33 of 75- toxicological concern, in surface and ground waters. In contrast to the approach for ecological assessment, all sources of methomyl and thio dicarb, which degrades to methomyl, will be considered. Whether exposure estimates will refl ect methomyl separately from thiodicarb or assess thiodicarb in methomyl equivalents will depend on the toxicity differential of the compounds. Concentrations of methomyl residues of concern in surface water will be estimated using PRZM/EXAMS (see description in Section 7.2 ). Ground water exposure estimates for methomyl residues of concern will be estimated using the Screening 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 fa te data requirements for methomyl are not sufficient for exposure assessment. The submitte d aqueous photolysis studi es either have poor material balances or did not analyze for transformation products of methomyl. Therefore, a guideline-compliant study is requested (s imilar to MRID 43823305 but that adequately characterizes the transformation products of methomyl).

The submitted aerobic aquatic metabolism (M RID 43325401) and anaerobic aquatic metabolism (MRID 73214) studies have poor material balances . Therefore, new studies are requested in order to describe the fate of methomyl in surf ace water bodies down gradient from terrestrial use sites. Two of the anaerobic systems are requested to be iron-poor, while a third anaerobic system is requested to be iron-rich. Methomyl is expect ed to be unstable in the presence of ferrous iron. Study of anaerobic systems with different concen trations of iron may result in additional information on the degradation kinetics of methomyl in these systems. Care should be taken to confirm the radioactivity in th e dosing solution and in day 0 systems as soon after dosing as possible. If these studies are to be useful in e xposure assessment, they must be able to quantify the degradation rate of methomyl in the pres ence of ferrous iron. All aerobic and anaerobic systems should be maintained at pH values below seven.

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 gap). Draft Data Call-In (DCI) tables for requested data are provided in APPENDIX E

.

### -34 of 75- TABLE 7.1. Environmental Fate Da ta Requirement Table for Methomyl.

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

8844 Unacceptable 835.2120 Hydrolysis 131249 Acceptable No. --

8844 Unacceptable 22439 (In review) A 161885 Unacceptable 835.2240 Aqueous photolysis

43823305 (In review) A Yes. A guideline-compliant study with a reasonable mass balance and characterization of photoproducts is requested.

835.2410 Soil photolysis 163745 Acceptable No. -- Fung and Uren, 1977 Unacceptable 8567 Supplemental 8568 Acceptable 8844 Unacceptable 9325 Unacceptable
133187/155756 Unacceptable 43217901 Acceptable 835.4100 Aerobic soil metabolism

45473401 (In review) A No. --

835.4200 Anaerobic soil metabolism 43217902 Acceptable No. --

835.4300 Aerobic aquatic metabolism 43325401 Supplemental Yes. A guideline-compliant study with a reasonable mass balance is requested.
835.4400 Anaerobic aquatic metabolism 73214 Unacceptable Yes. A guideline-compliant study of three acidic systems (two ferrous iron-poor, one ferrous iron-rich) with a reasonable mass balance is requested. 44306 Acceptable 161884 Acceptable Fung and Uren, 1977 Unacceptable 835.1230 835.1240 Adsorption/ desorption and leaching

Fung and Briner, 1977 Unacceptable No. --

8260 Unacceptable 9324 Unacceptable 9326 Unacceptable 133188 (8 844) Unacceptable 41623901/41623902 Acceptable Terrestrial field dissipation

42288001/43217903 Supplemental Storage stability 43708807 (In review) A
Reeves and Woodham, 1974 Upgradeable

Fung, 1976 Upgradeable 41623901/42288001 Upgradeable 43117401 Acceptable 835.6100

Analytical method in soil, sediment, and/or
water

43117402 (p. 78-95) Upgradeable Currently,

no. MRID 43117401 describes acceptable ELISA methods in soil, sediment, and water that have a range up to 5.0 ppb. The following submitted analytical methods are not acceptable ( i.e. , are upgradeable) without independent validation. Reeves and Woodham (1974) describe a method in soil, sediment, and water. Fung (1976) describes a method in soil and water. MRIDs 41623901 and 42288001 describe a similar method in soil. MRID 43117402 describes methods in water (p. 78-95) and in soil (p. 116- 119). Independent validation of

### -35 of 75- OCSPP Guideline Data Requirement Submitted Studies (MRID) Classification Data Gap? Comments

43117402 (p. 116-119) Upgradeable methods in soil that support field studies is necessary for study evaluation. However, due to the availability of alternative acceptable methods, additional data are not requested at this time. 40643001/40532201 Unacceptable 835.7100 Ground water monitoring 43568301 Acceptable No. --

850.1730 Fish bioconcentration 131251 Unacceptable No. Fish bioconcentration data are not needed for compounds with low K OW . 43708801 Supplemental 43708802 Supplemental 43708803 Supplemental 43708804 Supplemental Aquatic reservoir monitoring (Non-guideline)

43744401 Supplemental 158689 Acceptable Foliar dissipation (Non-guideline) 42271701 Acceptable (None)

Chlorination (Non-guideline) 46210701 Acceptable No. --

A The four studies currently in review are not expected to alter the identified data gaps. The aqueous photolysis studies in review (MRID 22439 and 43823305) preliminar ily appear unacceptable. The storage stability (MRID 43708807) and aerobic soil metabolism (MRID 45473401) studies in review have not been preliminarily classified. If MRID 45473401 is classified acce ptable, it could reduce exposure estimates in the assessments.



### 7.8.2. Effects Data

Although many subm issions have been made to pr ovide data on the eff ects of methomyl to aquatic and terrestrial organisms, data gaps still exist ( Tables 7.2-7.4 ). 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.

### -36 of 75- TABLE 7.2. 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 acute oral toxicity 00161886 Acceptable Yes *

45299802 Acceptable 45299801 Acceptable 850.2200 Avian sub-acute 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 for another N-methyl carbamate ( i.e
., thiodicarb), mallard ducks appear more sensitive than bobwhite quail on a chronic exposure basis. Therefore, chronic toxicity data for mallard ducks exposed to methomyl could result in a more sensitive avian chronic toxicity endpoint and this is, thus, identified as a data gap.

### -37 of 75- TABLE 7.3. 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

### -38 of 75- TABLE 7.4. 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* * Toxicity data for terrestrialplants and vascular and nonvascular 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 (OCSPP Guideline 850.2100) is required for passerine birds, as specified in 40 CFR Part 158 (Oct. 26, 2007). EFED recommends that the Pesticide Re-evaluation Divisi on (PRD) request submission of a passerine study protocol for review by the Agency prior to in itiation 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 (OCSPP 850.2300). Currently acceptable data for methomyl are only available for an upland game species (Bobwhite quail). Data from another N-methylcarbamate ( i.e ., thiodicarb) suggest that mallard ducks may be more sensitive than Bobwhite quail on a chroni c-exposure basis. The chronic toxicity data available for birds indicate that mallard duc ks (NOAEC = 500 mg a.i./kg-diet; LOAEC = 1,000 mg a.i./kg-diet, based on a reduction in number of eggs laid) (MRID 43313004) are more sensitive to thiodicarb than bobwhite quail (no reproductive eff ects seen at any concentration tested; highest concentration tested = 1,000 mg a.i./kg-diet) (MRID 43313003). Additionally, bobwhite quail appear more sens itive to methomyl than to th iodicarb based on chronic exposure (for methomyl, NOAEC = 150 mg a.i./kg-diet; L OAEC = 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

### -39 of 75- assume that mallard ducks may be more sensitiv e to methomyl than bobwhite quail on a chronic exposure basis. Therefore, since additional avia n reproduction data for methomyl could result in a more sensitive avian reproductive endpoint, and, t hus, could alter the estimated level of risk for birds (and by extension to terrestrial-phase amphi bians and reptiles) from the use of methomyl, 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.

Several efficacy studies that were conducted to test the effects of methomyl on a variety of target and non-target invert ebrate pests also supplied information on effects to plants after methomyl applications. Due to a lack of information on study design and data analyses, these efficacy studies are classified as ‘supplemen tal’ and are not adequate for pl ant (or terrestrial invertebrate) RQ calculation. None of the st udies showed any adverse effect s to plants at the highest treatment levels tested (most of which were at or above the maximum allowable single application rate for methomyl of 0.9 lbs a.i./a cre) and the NOAEC from the studies represented the highest treatment rates examined (see Table 4.3 ). However, because none of the studies addressed potential risks to monocots or eff ects on seedling emergence and some N-methyl carbamates are plant auxins that are used to thin fruit ( e.g ., carbaryl), risks to plants from the use of methomyl cannot be precluded using the available data. Tier I seedling emergence and vegetative vigor studies (OCSPP Guidelines 850.4100 and 850.4150) are, therefore, required. If toxicity data for terrestrial plants are not s ubmitted for methomyl, EFED will assume risk for terrestrial plants.

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 out door uses (40 CFR Part 158). Toxici ty data for both vascular and nonvascular aquatic plants (Tier I, OCSPP Gu idelines 850.4400 and 850.5400) are required but are not available for methomyl. Although, there is evid ence to suggest that meth omyl 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

Bromilow, R., G. Briggs, M. Williams, J. Smelt, L. Tuinstra , W. Traag. 1986. The Role of Ferrous Ions in the Rapid Degradation of Oxamyl, Methomyl and Aldicarb in Anaerobic Soils. Pestic. Sci ., 17:535-547.

### -40 of 75- 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 Quality and Safety: Chemistry, Toxicology, and Technology, Georg Thieme Publ., Stuttgart, West Germany, pp. 9-28.

Kiigemagi, U. and M. L. Deinzer. 1979. Dislodgable and total residues of methomyl on mint foliage. Bull. Environ. Contam. Toxicol. 22:517-521 in Willis, G. H. and L.L. McDowell. 1987. Pesticide persistence on foliage. Reviews of Environmental Contamination and Toxicology 100:21-73.

National Marine Fisheries Service (NMFS). 2009. Natio nal Marine Fisheries Service Endangered Species Act Section 7 Consultation Biological Opinion Environmental Protection Agency Registration of Pesticides Containing Carbaryl, Carbofuran, and Methomyl. NMFS. April, 20 2009.

Sheets, T. J., W. V. Campbell and R. B. Leidy. 1982. Fall armyworm control and residues of methomyl on coastal Bermuda grass. J. Agric. Food Chem. 30:532-536. in Willis, G. H. and L.L. McDowell. 1987. Pesticide persistence on foliage. Reviews of Environmental Contamination and Toxicology 100:21-73.

Smelt, J. H., A. Dekker, M. Leistra, and N. Houx. 198 3. Conversion of Four Carbamoyloximes in Soil Samples from Above and Below th e Soil Water Table. Pestic. Sci. 1983, 14(2):173-181.

Strathmann, T.J. and A.T. Stone. 2002. Reduction of th e Pesticides Oxamyl and Methom yl by FeII: Effect of pH and Inorganic Ligands. Environ. Sci. Technol. 36(4):653-661.

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 a . 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 b . Reregistration Eligibility Decision (RED): Me thomyl. EPA 738-R-98-021. U.S. Environmental Protection Agency, Office of Preventio n, Pesticides and Toxic Substan ces. December, 1998. Online at: http://www.epa.gov/oppsrrd1/REDs/0028red.pdf

U SEPA. 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. 2007. Kaul, M. Maximum Number of Crop Cycles Per Year in California for Methomyl Use Sites. U.S. Environmental Protection Ag ency, Office of Prevention, Pesticides, and Toxic Substances, Biological and Economic Analysis Branch. Feb. 28, 2007.

### -41 of 75- 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/ecoriskove rview.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. Jones, D. Refined Methom yl Surface Water Drinking Water Assessment for Lettuce Considering Alternative Application Practices to Reduce Drinki ng Water Exposure. DP Barcode 365917. U.S. Environmental Protection Agency, Of fice of Prevention, Pesticides an d Toxic Substances, Environmental Fate and Effects Division. Memorandum to the Special Review and Reregistration Division. Sep. 3, 2009.

USEPA. 2009 a . Methomyl (090301): Screening Level Usage Anal ysis. U.S. Environmental Protection Agency, Office of Prevention, Pesticides and Toxic Substances, Biological and Economic Analysis Division. Oct. 19, 2009.

USEPA. 2010. Letter to James Lecky, Director, Office of Protected Resources, National Marine Fisheries Service. From Richard Keigwin, Director, Pesticide Re-evaluatio n Division, Office of Pesticide Programs. May 14, 2010.

U.S.Fish and Wildlife Service.(USFWS) 1989. Final Biol ogical Opinion in Response to U. S. Environmental Protection Agency’s September 30, 1988, Request for Consultation on Their Pesticide Labeling Program. U. S. Department of Interior, Fish and Wildlife Service (EHC/BFA?9-89-1).

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.

USFWS/NMFS/NOAA.2004. 50 CFR Part 402. Joint Counterpart Endangered Species Act Section 7 Consultation Regulations; Final Rule. Federal Register Volume 69. Number 20.Pages 47731-47762. August 5, 2004.

U.S. Geological Survey (USGS). 2010. 2002 Pesticide Use Maps. U.S. Geological Survey, National WaterQuality Assessment (NAWQA) Progra m, Pesticide National Synthesis Program. Accessed on May 20, 2010. Online at: http://water.usgs.gov/nawqa/pnsp/usage/maps/compound_listing.php?year=02

W illis, G. H. and L.L. McDowell. 1987. Pesticide persistence on foliage. Reviews of Environmental Contamination and Toxicology , 100:21-73.

SUBMITTED ENVIRONMEN TAL FATE STUDIES: 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.

### -42 of 75- 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.

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.

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.

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.

42288001 Kennedy, C. 1991. Field Soil Dissipation of Lannate L Insecticide--a 1991 Study. Lab Project Number: AMR-1921-91: ML91-0242-DUP: 9100135. Unpublished study prepared by Morse Labs and Harris Environmental Tech nologies, Inc. 64 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.

### -43 of 75- 43217903 Kennedy, C. 1992. Field Soil Dissipation of Lannate L Insecticide: A 1991 Study: Supplement. Lab Project Number: AMR/1921/91: ML91/02420DUP: 9100135. Unpublished study prepared by Morse Lab., Inc.; Harris Environmental Technologies, Inc. 34 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.

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.

43823305 Armbrust, K. and D. Reilly. 1995. Indirect Photodegredation of Methomyl in Aqueous Solutions. Lab Project Number: AMR 2975-94. Unpublished study prepared by DuPont Agricultural Products. 103 p.

SUBMITTED EFFECTS STUDIES: 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).

### -44 of 75- 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.

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.

### -45 of 75- 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.

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.

### -46 of 75- 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.

### -47 of 75- APPENDIX A: Registered Uses and Application Rates for Methomyl.

USE PRODUCT MAX APPL. RATE MIN APP.INTERVAL 1 MAX APPL. RATE/ CROP MAX NO. OF APPL./ CROP MAX NO. OF CROPS/ YEAR* MAX APPL. RATE/ YEAR

Lannate LV Alfalfa LV
Lannate SP 0.9 lbs a.i./A 5 3.6 lbs a.i./A 10 9** 32.4 lbs a.i./A

Lannate LV Anise (Fennel) LV
Lannate SP 0.9 lbs a.i./A 5 4.5 lb a/A 10 2 9 lbs a.i./A

Lannate LV Apple (ground only) Lannate SP 0.9 lbs a.i./A 7 4.5 lbs a.i./A 5 1 4.5 lbs a.i./A

Lannate LV Asparagus LV
Lannate SP 0.9 lbs a.i./A 5 4.5 lbs a.i./A 8 1 4.5 lbs a.i./A

Lannate LV Avocado Lannate SP 0.9 lbs a.i./A 5 0.9 lbs a.i./A 2 1 0.9 lbs a.i./A

Lannate LV Barley LV
Lannate SP 0.45 lbs a.i./A 5 1.8 lbs a.i./A 4 1 1.8 lb a.i/.A

Lannate LV Beans, Succulent

LV (kidney, lima, mung, Navy, pinto, snap, wax, broad, fava, asparagus beans, blackeyed peas, cowpeas) Lannate SP 0.9 lbs a.i./A 5 4.5 lbs a.i./A 10 1 4.5 lb a.i/.A

Sweet Lupine, White Sweet Lupine, White Lupine, Grain Lupine Lannate SP 0.9 lbs a.i./A 5 4.5 lbs a.i./A 10 1 4.5 lbs a.i./A

Lannate LV Beans, Dry LV (same as succulent beans) Lannate SP 0.9 lbs a.i./A 5 4.5 lbs a.i./A 10 1 4.5 lb a.i/.A

Beans SLN (interplanted with nonbearing almonds, plums, prunes, peaches,and walnuts) (CA770431) Lannate SP 0.45 lbs a.i./A 5 0.9 lbs a.i./A 2 1 0.9 lb a.i/.A

Lannate LV Beets (table) Lannate SP 0.9 lbs a.i./A 5 3.6 lbs a.i./A 8 2 7.2 lb a.i/.A

Lannate LV Bermudagrass (pasture) Lannate SP 0.9 lbs a.i./A 5 0.9 lbs a.i./A 4 1 0.9 lb a.i/.A

Lannate LV Blueberries (ground only) Lannate SP 0.9 lbs a.i./A 5 3.6 lbs a.i./A 4 1 3.6 lbs a.i./A

Lannate LV Broccoli LV
Lannate SP 0.9 lbs a.i./A 2 6.3 lbs a.i./A 10 Imperial Valley : 1 Coastal Valleys : 3 San Joaquin Valley : 2 6.3 lbs a.i./A

18.9 lbs a.i./A

12.6 lbs a.i./A

### -48 of 75- USE PRODUCT MAX APPL. RATE MIN APP.INTERVAL 1 MAX APPL. RATE/ CROP MAX NO. OF APPL./ CROP MAX NO. OF CROPS/ YEAR* MAX APPL. RATE/ YEAR

Broccoli, Chinese SLN (CA-860059) Lannate SP 0.9 lbs a.i./A 5 4.5 lbs a.i./A 5 2 9 lbs a.i./A

Broccoli Raab SLN (CA-900034) Lannate SP 0.9 lbs a.i./A 5 7.2 lbs a.i./A 10 Imperial Valley : 1 Coastal Valleys : 3 San Joaquin Valley : 2 7.2 lbs a.i./A

21.6 lbs a.i./A

14.4 lbs a.i./A Lannate LV Brussels Sprouts

LV Lannate SP 0.9 lbs a.i./A 2 5.4 lbs a.i./A 10 1 5.4 lbs a.i./A

Lannate LV Cabbage LV
Lannate SP 0.9 lbs a.i./A 2 7.2 lbs a.i./A 15 3 21.6 lbs a.i./A

Lannate LV Carrot LV
Lannate SP 0.9 lbs a.i./A 5 6.3 lbs a.i./A 10 1 6.3 lbs a.i./A

Lannate LV Cauliflower LV
Lannate SP 0.9 lbs a.i./A 2 7.2 lbs a.i./A 10 Coastal Region : 2 San Joaquin Valley : 1 14.4 lbs a.i./A

7.2 lbs a.i./A Lannate LV Celery LV
Lannate SP 0.9 lbs a.i./A 5 7.2 lbs a.i./A 10 2.5 18 lbs a.i./A

Lannate LV Chicory Lannate SP 0.9 lbs a.i./A 5 1.8 lbs a.i./A 2 San Joaquin Valley : 2 Desert : 1 3.6 lbs a.i./A 1.8 lbs a.i./A Lannate LV Chinese Cabbage Lannate SP 0.9 lbs a.i./A 5 7.2 lbs a.i./A 10 3 21.6 lbs a.i./A

Lannate LV Collards LV (fresh market only) Lannate SP 0.9 lbs a.i./A 5 5.4 lbs a.i./A 8 3 16.2 lbs a.i./A

Lannate LV Corn (field and popcorn) Lannate SP 0.45 lbs a.i./A 5 2.25 lbs a.i./A 10 1 2.25 lbs a.i./A

Corn (seed) LV Lannate SP 0.45 lbs a.i./A 5 2.25 lbs a.i./A 10 1 2.25 lbs a.i./A Lannate LV Corn (sweet) LV
Lannate SP 0.45 lbs a.i./A 1 6.3 lbs a.i./A 28 3 18.9 lbs a.i./A

Corn LV Methomyl 5G Granules 0.15 lbs a.i./A NR 6.3 lbs a.i./A 10 3 18.9 lbs a.i./A

Lannate LV Cotton 2, LV
Lannate SP 0.675 lbs a.i./A 3 1.8 lbs a.i./A 8 1 1.8 lbs a.i./A

Lannate LV Cucumber LV
Lannate SP 0.9 lbs a.i./A 5 5.4 lbs a.i./A 12 1 5.4 lbs a.i./A

Lannate LV Eggplant Lannate SP 0.9 lbs a.i./A 5 4.5 lbs a.i./A 10 1 4.5 lbs a.i./A

Lannate LV Endive, Escarole Lannate SP 0.9 lbs a.i./A 5 4.5 lbs a.i./A 8 2 (less in desert) 9 lbs a.i./A

Lannate LV Garlic Lannate SP 0.45 lbs a.i./A 5 2.7 lbs a.i./A 6 1 2.7 lbs a.i./A

Lannate LV Grapefruit 3
Lannate SP 0.9 lbs a.i./A 5 2.7 lbs a.i./A 4 1 2.7 lbs a.i./A

Lannate LV Horseradish (ground Only) Lannate SP 0.45 lbs a.i./A 5 1.8 lbs a.i./A 4 1 1.8 lbs a.i./A

### -49 of 75- USE PRODUCT MAX APPL. RATE MIN APP.INTERVAL 1 MAX APPL. RATE/ CROP MAX NO. OF APPL./ CROP MAX NO. OF CROPS/ YEAR* MAX APPL. RATE/ YEAR

Lannate LV Leafy Green Vegetables (beet tops, dandelions, kale, mustard greens, parsley, Swiss chard, turnip greens) Lannate SP 0.9 lbs a.i./A 5 3.6 lbs a.i./A 8 4 14.4 lbs a.i./A

Lannate LV Lemon 3
Lannate SP 0.9 lbs a.i./A 5 2.7 lbs a.i./A 4 1 2.7 lbs a.i./A

Lannate LV Lentils Lannate SP 0.9 lbs a.i./A 5 0.9 lbs a.i./A 2 1 0.9 lbs a.i./A

Lannate LV Lettuce LV (head varieties) Lannate SP 0.9 lbs a.i./A 2 7.2 lbs a.i./A 15 Central Coast : 2 Central Valley : 2 Other Regions : 1 14.4 lbs a.i./A

14.4 lbs a.i./A

7.2 lbs a.i./A Lannate LV Lettuce LV (leaf varieties) Lannate SP 0.9 lbs a.i./A 2 3.6 lbs a.i./A 8 Desert : 1 Other Regions : 2 3.6 lbs a.i./A

7.2 lbs a.i./A Lannate LV Melons LV (cantaloupe, casaba, Santa Claus, Crenshaw, honeydew, honey balls, Persian, golden pershaw, mango melon, pinapple melon, snake, watermelon) Lannate SP 0.9 lbs a.i./A 5 5.4 lbs a.i./A 12 1 5.4 lbs a.i./A

Lannate LV Mint LV (peppermint, spearmint) Lannate SP 0.9 lbs a.i./A 5 1.8 lbs a.i./A 4 Peppermint: 1** Spearmint: 2** 1.8 lbs a.i./A

3.6 lbs a.i./A Lannate LV Nectarine 3 Lannate SP 0.9 lbs a.i./A 5 2.7 lbs a.i./A 3 1 2.7 lbs a.i./A

Nonbearing Fruit, Grape, and Nut Nursery Stock (field grown) SLN (CA-770308) Lannate SP 0.9 lbs a.i./A 5 4.5 lbs a.i./A 5 1 4.5 lbs a.i./A

Lannate LV Oats LV
Lannate SP 0.45 lbs a.i./A 5 1.8 lbs a.i./A 4 1 1.8 lbs a.i./A

Lannate LV Onions (green) Lannate SP 0.9 lbs a.i./A 5 5.4 lbs a.i./A 8 3 16.2 lbs a.i./A

Lannate LV Onions (dry bulb) Lannate SP 0.9 lbs a.i./A 5 3.6 lbs a.i./A 8 1 3.6 lbs a.i./A

Lannate LV Oranges 3
Lannate SP 0.9 lbs a.i./A 5 2.7 lbs a.i./A 4 1 2.7 lbs a.i./A

### -50 of 75- USE PRODUCT MAX APPL. RATE MIN APP.INTERVAL 1 MAX APPL. RATE/ CROP MAX NO. OF APPL./ CROP MAX NO. OF CROPS/ YEAR* MAX APPL. RATE/ YEAR

Lannate LV Peaches Lannate SP 0.9 lbs a.i./A 5 5.4 lbs a.i./A 6 1 5.4 lbs a.i./A

Lannate LV Peanuts Lannate SP 0.9 lbs a.i./A 5 3.6 lbs a.i./A 8 N/A N/A

Lannate LV Pears (Northeast only) Lannate SP 0.9 lbs a.i./A 5 1.8 lbs a.i./A 2 1 1.8 lbs a.i./A

Lannate LV Peas, succulent LV (pigeon peas, chick, garbanzo, dwarf peas, garden
peas, green peas, English peas, Field peas, edible pod peas) Lannate SP 0.9 lbs a.i./A 3 2.7 lbs a.i./A 6 1 2.7 lbs a.i./A

Lannate LV Pecans (Southeast only) Lannate SP 0.9 lbs a.i./A 5 6.3 lbs a.i./A 7 1 6.3 lbs a.i./A

Lannate LV Peppers LV (bell, hot, pimentos, sweet) Lannate SP 0.9 lbs a.i./A 5 4.5 lbs a.i./A 10 1 4.5 lbs a.i./A

Lannate LV Pomegranates Lannate SP 0.9 lbs a.i./A 5 1.8 lbs a.i./A 2 1 1.8 lbs a.i./A

Lannate LV Potato LV
Lannate SP 0.9 lbs a.i./A 5 4.5 lbs a.i./A 10 1 4.5 lbs a.i./A

Pumpkins SLN (CA910011) (San Joaquin, Stanislaus, Merced, Sacramento, and Riverside Counties) Lannate SP 0.9 lbs a.i./A 5 2.7 lbs a.i./A 3 1 2.7 lbs a.i./A

Radishes SLN (CA770495) Lannate SP 0.9 lbs a.i./A 5 1.8 lbs a.i./A 2 5 9 lbs a.i./A

Lannate LV Rye LV
Lannate SP 0.45 lbs a.i./A 5 1.8 lbs a.i./A 4 1 1.8 lbs a.i./A

Lannate LV Sorghum (except sweet sorghum) Lannate SP 0.45 lbs a.i./A 5 0.9 lbs a.i./A 2 1 0.9 lbs a.i./A

Lannate LV Soybeans LV
Lannate SP 0.45 lbs a.i./A 5 1.35 lbs a.i./A 3 1 1.35 lbs a.i./A

Soybeans SLN (interplanted with nonbearing almonds, plums, prunes, peaches,and walnuts) (CA770431) Lannate SP 0.45 lbs a.i./A 5 0.9 lbs a.i./A 2 1 0.9 lbs a.i./A

Lannate LV Spinach LV
Lannate SP 0.9 lbs a.i./A 5 3.6 lbs a.i./A 8 3 10.8 lbs a.i./A

Lannate LV Sugar Beet LV
Lannate SP 0.9 lbs a.i./A 5 4.5 lbs a.i./A 10 1 4.5 lbs a.i./A

Summer Squash LV Lannate LV 0.9 lbs a.i./A 5 5.4 lbs a.i./A 12 1 5.4 lbs a.i./A

### -51 of 75- USE PRODUCT MAX APPL. RATE MIN APP.INTERVAL 1 MAX APPL. RATE/ CROP MAX NO. OF APPL./ CROP MAX NO. OF CROPS/ YEAR* MAX APPL. RATE/ YEAR

(crookneck, straightneck, scallop, vegetable marrow, spaghetti, hyotan, cucuzza, hechima, Chinese okra, bitter melon, balsam pear, balsam apple, Chinese cucumber) Lannate SP

Sweet Potatoes SNL(Aerial only) (CA780136) Lannate SP 0.9 lbs a.i./A 5 2.7 lbs a.i./A 3 1 2.7 lbs a.i./A

Lannate LV Tangelo, Tangerine 3 Lannate SP 0.9 lbs a.i./A 5 2.7 lbs a.i./A 4 1 2.7 lbs a.i./A

Lannate LV Tobacco (except shade) Lannate SP 0.45 lbs a.i./A 5 2.25 lbs a.i./A 5 1 2.25 lbs a.i./A

Lannate LV Tomato Lannate SP 0.9 lbs a.i./A 5 6.3 lbs a.i./A 16 1 6.3 lbs a.i./A

Lannate LV Tomatillo Lannate SP 0.9 lbs a.i./A 5 4.5 lbs a.i./A 5 1 4.5 lbs a.i./A

Lannate LV Turf (sod farms only) Lannate SP 0.9 lbs a.i./A 5 3.6 lbs a.i./A 4 2 7.2 lbs a.i./A

Lannate LV Wheat LV
Lannate SP 0.45 lbs a.i./A 5 1.8 lbs a.i./A 4 1 1.8 lbs a.i./A

Farnam Die Fly (scatter bait) 1

Stimukil Fly Bait (scatter bait) NR

Lurectron Scatterbait (scatter bait; bait stations) 3 Feedlots (outside)

Golden Malrin Fly Killer (scatter bait) 0.22 lbs a.i./acre (4 ounces of product/500 ft 2 ) or 2 bait stations/500 ft 2

1 NR NR N/A

Dairies (outside) Farnam Die Fly (scatter bait) 0.22 lbs a.i./acre (4 ounces of product/500 ft 2 ) 1

Stables (outside) Farnam Die Fly (scatter bait) 0.22 lbs a.i./acre (4 ounces of product/500 ft 2 ) 1 NR NR N/A

### -52 of 75- USE PRODUCT MAX APPL. RATE MIN APP.INTERVAL 1 MAX APPL. RATE/ CROP MAX NO. OF APPL./ CROP MAX NO. OF CROPS/ YEAR* MAX APPL. RATE/ YEAR

Farnam Die Fly (scatter bait) 1

Stimukil Fly Bait (bait station) NR Broiler Houses (outside)

Golden Malrin Fly Killer (scatter bait) 0.22 lbs a.i./acre (4 ounces of product/500 ft 2 ) or 2 bait stations/500 ft 2 1 NR NR N/A

Hog Houses (outside) Farnam Die Fly (scatter bait) 0.22 lbs a.i./acre (4 ounces of product/500 ft 2 ) 1 NR NR N/A

Farnam Die Fly (scatter bait) 1

Stimukil Fly Bait (scatter bait) NR

Lurectron Scatterbait (scatter bait; bait stations; paste) 3 Livestock Barns (outside)

Golden Malrin Fly Killer (scatter bait) 0.22 lbs a.i./acre (4 ounces of product/500 ft 2 ) or 2 bait stations/500 ft 2

1 NR NR N/A

Farnam Die Fly (scatter bait) 1

Stimukil Fly Bait (bait station; scatter bait) NR

Lurectron Scatterbait (scatter bait; bait stations) 3 Meat Processing Establishments (outside)

Golden Malrin Fly Killer (scatter bait) 0.22 lbs a.i./acre (4 ounces of product/500 ft 2 ) or 2 bait stations/500 ft 2

1 NR NR N/A

### -53 of 75- USE PRODUCT MAX APPL. RATE MIN APP.INTERVAL 1 MAX APPL. RATE/ CROP MAX NO. OF APPL./ CROP MAX NO. OF CROPS/ YEAR* MAX APPL. RATE/ YEAR

Farnam Die Fly (scatter bait) 1

Stimukil Fly Bait (bait station; scatter bait) NR

Lurectron Scatterbait (scatter bait; bait stations) 3 Poultry Processing Establishments (outside)

Golden Malrin Fly Killer (scatter bait) 0.22 lbs a.i./acre (4 ounces of product/500 ft 2 ) or 2 bait stations/500 ft 2

1 NR NR N/A

Farnam Die Fly (scatter bait) 1

Stimukil Fly Bait (bait station; scatter bait) NR

Lurectron Scatterbait (scatter bait; bait stations) 3 Beverage Plants (outside)

Golden Malrin Fly Killer (scatter bait) 0.22 lbs a.i./acre (4 ounces of product/500 ft 2 ) or 2 bait stations/500 ft 2

1 NR NR N/A

Farnam Die Fly (scatter bait) 1 Canneries (outside)

Stimukil Fly Bait (scatter bait; bait station) 0.22 lbs a.i./acre (4 ounces of product/500 ft 2 ) or 2 bait stations/500 ft 2 NR NR NR N/A

### -54 of 75- USE PRODUCT MAX APPL. RATE MIN APP.INTERVAL 1 MAX APPL. RATE/ CROP MAX NO. OF APPL./ CROP MAX NO. OF CROPS/ YEAR* MAX APPL. RATE/ YEAR

Lurectron Scatterbait (scatter bait; bait stations) 3

Golden Malrin Fly Killer (scatter bait) 1

Farnam Die Fly (scatter bait) 1

Stimukil Fly Bait (bait station) NR

Lurectron Scatterbait (scatter bait; bait stations) 3 Food Processing Establishments (outside)

Golden Malrin Fly Killer (scatter bait) 0.22 lbs a.i./acre (4 ounces of product/500 ft 2 ) or 2 bait stations/500 ft 2

1 NR NR N/A

Farnam Die Fly (bait station) 0.22 lbs a.i./acre (2 bait stations/500 ft 2 ) Stimukil Fly Bait (bait station) 2 bait stations/500 ft 2 Stimukil Fly Bait (scatter bait) 0.22 lbs a.i./acre (4 ounces of product/500 ft 2 ) Stimukil Fly Bait (brush on) NR NR Commercial use Sites (unspecified)

Lurectron Scatterbait (scatter bait) 0.22 lbs a.i./acre (4 ounces of product/500 ft 2 ) 3 NR NR N/A

Stimukil Fly Bait (bait station) NR Kennels (outside)

Lurectron Scatterbait (bait station) 2 bait stations/500 ft 2
3 NR NR N/A

### -55 of 75- USE PRODUCT MAX APPL. RATE MIN APP.INTERVAL 1 MAX APPL. RATE/ CROP MAX NO. OF APPL./ CROP MAX NO. OF CROPS/ YEAR* MAX APPL. RATE/ YEAR

Golden Malrin Fly Killer (bait station) 4 bait stations/500 ft 2 1

Stimukil Fly Bait (bait station) NR

Lurectron Scatterbait (bait station) 2 bait stations/500 ft 2
3 Dumpsters (associated with above uses)

Golden Malrin Fly Killer (bait station) 4 bait stations/500 ft 2 1 NR NR N/A

Stimukil Fly Bait (bait station) NR

Lurectron Scatterbait (bait station) 2 bait stations/500 ft 2
3 Restaurants (outside)

Golden Malrin Fly Killer (bait station) 4 bait stations/500 ft 2 1 NR NR N/A

Stimukil Fly Bait (bait station) NR

Lurectron Scatterbait (bait station) 2 bait stations/500 ft 2
3 Supermarkets (outside)

Golden Malrin Fly Killer (bait station) 4 bait stations/500 ft 2 1 NR NR N/A

Stimukil Fly Bait (bait station) 2 bait stations/500 ft 2 NR Commissaries (outside)

Golden Malrin Fly Killer (bait station) 4 bait stations/500 ft 2 1 NR NR N/A

Stimukil Fly Bait (bait station) NR

Lurectron Scatterbait (bait station) 2 bait stations/500 ft 2
3 Bakeries (outside)

Golden Malrin Fly Killer (bait station) 4 bait stations/500 ft 2 1 NR NR N/A

### -56 of 75- USE PRODUCT MAX APPL. RATE MIN APP.INTERVAL 1 MAX APPL. RATE/ CROP MAX NO. OF APPL./ CROP MAX NO. OF CROPS/ YEAR* MAX APPL. RATE/ YEAR

Stimukil Fly Bait (scatter bait) NR Poultry houses

Lurectron Scatterbait (scatter bait; bait stations; paste) 0.22 lbs a.i./acre (4 ounces of product/500 ft 2 ) or 2 bait stations/500 ft 2 3 NR NR N/A

Stimukil Fly Bait (scatter bait) NR

Lurectron Scatterbait (scatter bait) 3 Commercial Dumpsters which are enclosed

Golden Malrin Fly Killer (scatter bait) 0.22 lbs a.i./acre (4 ounces of product/500 ft 2 )

1 NR NR N/A

Stables Golden Malrin Fly Killer (bait station) 4 bait stations/500 ft 2 1 NR NR N/A

Fast Food Establishments Golden Malrin Fly Killer (bait station) 4 bait stations/500 ft 2 1 NR NR N/A

Warehouses Golden Malrin Fly Killer (bait station) 4 bait stations/500 ft 2 1 NR NR N/A

LV Low volume aerial applications (a minimum of 1 gallon of tank mixture/acre) is allowed

1 5 days was used unless otherwise stated on the label.

2 Different rates depending on geographic region; the listed rates are for California.

3 Limited to use in CA, AZ, and HI

SLN = California Special Local Needs (FIFRA §24(c)) * Based on data regarding California agriculture provided in a memo from BEAD. ** For perennial crops, the number of cuttings per year was used.

### -57 of 75- APPENDIX B. Toxicity Data for Methomyl:

TABLE 1. Available T oxicity Data for Methomyl (Excluding Invalid Studies):

TAXON ENDPOINT FORMULATION MRID STUDYCLASSIFICATION 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 lbs a.i./acre Formulation (Methomyl ® 25WP) 45133302 Supplemental Supplemental (non-guideline, but scientifically sound) Wasp ( Aphidius 48-hr LC 50 = Formulation 45133301 Supplemental Supplemental

### -58 of 75- TAXON ENDPOINT FORMULATION MRID STUDYCLASSIFICATION COMMENTS

rhopalosiphi ) 0.00022 lbs a.i./acre (Methomyl ® 20L) (non-guideline, but scientifically sound) Mite (Typhlodromus pyri) 7-day LC 50 = 0.0114 lbs a.i./acre Formulation (Methomyl ® 20L) 45125501 Supplemental Supplemental (non-guideline, but scientifically sound) Mite (Typhlodromus pyri) 7-day LC 50 = 0.01115 lbs 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 TGAI (>99%) 131254 Acceptable LOAEC based on delayed reproduction

### -59 of 75- TAXON ENDPOINT FORMULATION MRID STUDYCLASSIFICATION COMMENTS

LOAEC = 0.001 mg a.i./L 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

### -60 of 75- Table 2. 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 620 400980-01 Supplemental Temp = 17 ̊ C pH = 8.5 Hardness = 40 mg/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 Lepomis macrochirus Bluegill sunfish 95

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

### -61 of 75- Species Compound (% a.i.) LC50 (96-h, μg

a.i./L) MRID Classification Notes:

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 560 400980-01 Supplemental Temp = 22 ̊ C pH = 7.4 Hardness = 40 mg/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 24

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

### -62 of 75- Species Compound (% a.i.) LC50 (96-h, μg

a.i./L) MRID Classification Notes:

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 760 400980-01 Supplemental Temp = 22 ̊ C pH = 7.4 Hardness = 40 mg/L fingerlings tested Ictalurus punctatus Channel catfish
24

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 Oncorhyncus mykiss Rainbow trout 95

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

### -63 of 75- Species Compound (% a.i.) LC50 (96-h, μg

a.i./L) MRID Classification Notes:

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 1600 400980-01 Supplemental Temp = 12 ̊ C pH = 7.2 Hardness = 40 mg/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 24

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

### -64 of 75- Species Compound (% a.i.) LC50 (96-h, μg

a.i./L) MRID Classification Notes:

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

### -65 of 75- Table 3. 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 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

### -66 of 75- LC50 (μg

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

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/A

### -67 of 75- APPENDIX C. Schematic for Assessing Ex posure from Methomyl Scatter Bait Uses.

For scatter bait uses, this assessment considers a 10-hectare plot that has 50% impervious and 50% pervious land cover and a 160,000 ft 2 

### commercial structure. If a 10-foot wide area around the structure is treated with sc atter bait, this results in 16,400 ft 2 

### being treated, which is 1.5% of the entire 10-hectare plot and 3% of the 5-he ctare impervious area (including the commercial structure). If the scatter bait is applied at the maximum single application rate of 0.25 lbs a.i./500 ft 2 

### , then a total of 8.2 lbs a.i. will be applied to the plot. This assessment approach is likely conservative for a typical scatter bait application because of the following assumptions: 1) the structure involved in the treat ment is a large, warehouse-type retailer; 2) th e treatment area includes an area surrounding the entire structure; 3) and the treatment area is 10 feet wide.

~1,038 ft

~1

, 038 f t ~ 734 f t ~ 734 f t

~ 400 f t

Pervious Land Cove r

Commercial Structure

Scatter Bait A pp lication Area ( 10 ft wide ) Im p ervious Land Cove r ~ 400 f t-68 of 75-APPENDIX D. Major Environmental Degradates of Methomyl.Table D.1. Chemical Names, Structures, and Maximum Reported Amounts of Methomyl’s Major Degradates.Code Name/SynonymChemical NameAChemical StructureStudy TypeMRIDMaximum%AR (day)Final %AR(study length)PARENTMethomylIUPAC:S-methyl (EZ)-N-(methylcarbamoyloxy)thioacetimidateCAS:Methyl N-[[(methylamino)carbonyl]oxy]ethanimidothioateCAS-no:16752-77-5Formula:C5H10N2O2SMW:162.21 g/molNOONSH(syn-methomyl displayed)MAJOR (>10%) DEGRADATESHydrolysis -pH 9 13124944(30) 44 (30)2243932(14) 12 (56)Aqueous photolysis161885 3 (0) 1 (15)8568 2.0 (15) 1.4 (45)432179012.3 (1) 0.2 (90)Aerobic soil45473401 3.0 (7) 0.9 (30)Anaerobic soil432179022.3 (1) 0.5 (74)MethomyloximeS-methyl-N-hydroxythioacetimidateFormula:C3H7NOSMW:105.16 g/molONSH(syn-methomyl oxime displayed)Aerobic aquatic 4332540113(2)<0.3 (29)Aqueous photolysis16188568(3) 66 (15)Soil photolysis 16374540(30) 40 (30)AcetonitrileMethyl cyanide; cyanomethaneFormula:C2H3NMW:41.05 g/molNAerobic aquatic 4332540121(7) in sol’n27(60) volatile<0.3 (29) in sol’n27 (102) volatileAcetamideEthanamide; acetic acid amideFormula:C2H5NOMW:59.07 g/molNH2OAerobic aquatic 4332540114(7) 0.6 (29)CarbonateCarbonateFormula:CO32-MW:60.01 g/molO-OOAerobic aquatic 4332540115(14) 5 (29)-69 of 75-Code Name/SynonymChemical NameAChemical StructureStudy TypeMRIDMaximum%AR (day)Final %AR(study length)Aqueous photolysis 2243956(56) 56 (56)856823(45) 23 (45)4321790175(90) 75 (90)Aerobic soil4547340161(30) 61 (30)Anaerobic soil4321790253(74) 53 (74)CarbondioxideCarbon dioxideFormula:CO2MW:44.01 g/molOOAerobic aquatic 4332540146(102) 46 (102)A. 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/

### -70 of 75- APPENDIX E: Data Call-In Tables.

The Environm ental Fate and Effects Division (EFE D) has completed a Data Call-In (DCI) table for the methomyl environmental fate and effects data gaps identified in Registration Review. The attached DCI table, which includes the gu ideline number and study t itle for required data, also provides a rationale for requi ring the data, an explanation of how the data will be used, and a brief description of how the data could im pact the Agency’s future decision-making.

Guideline Number: 835.2240 Study Title: Photodegradation in Water Rationale for Requiring the Data The Agency has a limited understanding of how met homyl behaves in clear, aquatic environments under irradiation. Depending on how quickly, to what extent, and to which transformation products the compound degrades, methomyl may or may not pose pot ential exposure concern in water. Submitted aqueous photolysis studies of methomyl were invalid (MRID 8844), had poor material balances (MRID 22439, 161885) or did not analyze for transfor mation products (MRID 43823305). Because methomyl photodegradation in water is not well understood, the Agency is requiring an OCSPP guideline-compliant aqueous photolysis study conducted similarly to MR ID 43823305 with quantification and identification of the transformation products as well as analysis of indirect photolysis resulting from the presence of dissolved oxidants. Practical Utility of the Data How will the data be used? Aqueous photolysis data will facilitate a better understanding of the fate of methomyl residues in water. If data indicate that photodegradation occurs rapi dly in shallow, clear, well-lit water and produces nontoxic transformation products, then the Agency coul d potentially determine that methomyl residues of concern do not persist in water under these conditions . If data indicate that photodegradation is not appreciable in shallow, clear, well-lit water or that th e transformation products are of similar or higher toxicity than the parent compound, then the Agency could conclude that methomyl residues of concern persist in water.

How could the data change the Agency’s decision or impact the Agency’s future decision-making? In the absence of the requested data, methomyl will be conservatively assumed stable to photolysis in water bodies. Risk assessment conclusions and associ ated labeled use precautions and/or restrictions could be made less restrictive if the required data indicate that methomyl is rapidly photodegraded to nontoxic transformation products or could be made mo re restrictive if the required data indicate that methomyl is photodegraded to transformation products more toxic than the parent compound.

Guideline Number: 835.4300 Study Title: Aerobic Aquatic Metabolism Rationale for Requiring the Data The Agency has a limited understanding of how met homyl behaves in aerobic aquatic environments once applied. Depending on how quickly, to what extent, and to which transformation products the compound degrades, methomyl may or may not pose potential exposure concern in water. An aerobic aquatic metabolism study of methomyl (MRID 43325401) was submitted to the Agency. However, the results of the study are uncertain due to poor material balances. Because methomyl degradation in water is not well understood, the Agency is requiring an OCSPP guide line-compliant aerobic aquatic metabolism study with systems maintained at pH values below seven.

### -71 of 75- Practical Utility of the Data How will the data be used? Aerobic aquatic metabolism data will facilitate a better understanding of the fate of methomyl 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 methomyl 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 methomyl 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, methomyl aerobic aquatic metabolism half-lives will be conservatively assumed two-fold greater than aerobic soil metabolism half-lives. If the required data indicate that methomyl in aerobic aqueous environmen ts is rapidly biodegraded, then risk assessment conclusions and associated labeled use precautions and/ or restrictions could be made less restrictive.

Guideline Number: 835.4400 Study Title: Anaerobic Aquatic Metabolism Rationale for Requiring the Data The Agency has a limited understanding of how met homyl behaves in anaerobic aquatic environments once applied. Depending on how quickly, to what extent, and to which transformation products the compound degrades, methomyl may or may not pose potential exposure concern in water. An anaerobic aquatic metabolism study of methomyl (MRID 00073214) was submitted to the Agency. However, the results of the study are uncertain due to poor materi al balances and the inability to detect methomyl in any sample including those collected on the day of treatment (likely due to rapid degradation in the presence of ferrous iron). Because methomyl degradation in anaerobic surface water systems is not well understood, the Agency is requiring an OCSPP guide line-compliant anaerobic aquatic metabolism study with three systems maintained at pH values below se ven, two of which that are iron-poor and one of which that is iron-rich. The radioactivity in the dosing solution should be confirmed as well as in the day 0 systems as soon after dosing as possible. Practical Utility of the Data How will the data be used? Anaerobic aquatic metabolism data w ill facilitate a better understanding of the fate of methomyl residues in water. If data indicate that degradation in anaerobic conditions occurs rapidly in acidic aquatic systems and produces nontoxic transformation products, then the Agency could pot entially determine that methomyl residues of concern do not persist in these systems. If data indicate that degradation is not appreciable in acidic aquatic systems or that the transf ormation products are of similar or higher toxicity than the parent compound, then the Agency could conc lude that methomyl residues of concern persist in acidic aquatic systems under anaerobic conditions. If data indicate that degradation rates in acidic, anaerobic aquatic systems are largely determined by the availability of ferrous iron, then the Agency could potentially refine its conclusions to consider additional environmental 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, methomyl anaerobic aquatic metabolism half-lives will be conservatively assumed two-fold greater than anaerobic soil metabolism half-lives. If the required data indicate that methomyl in anaerobic aquatic environmen ts is rapidly biodegraded to nontoxic degradation products, including in acidic, ferrous iron-poor conditions, then risk assessment conclusions and associated labeled use precautions and/or restrictions could be made less restrictive.

### -72 of 75- 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 “may affect” listed passer ine birds directly (and listed species from other taxa indirectly), and use of methomyl 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 methomyl 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 speci es (OCSPP 850.2300). Currently acceptable data for methomyl are only available for an upland game species (Bobwhite quail). Data from another N-methyl carbamate ( i.e ., thiodicarb) suggest that mallard ducks may be more sensitive than bobwhite quail on a chronic-exposure basis. The chroni c toxicity data available for birds indicate that mallard ducks (NOAEC = 500 mg a.i./kg-diet; LOAEC = 1,000 mg a.i./kg-diet, based on a reduction 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./kgdiet) (MRID 43313003). Additionally, Bobwhite qua il 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 Bobwhite quail on a chronic exposure basis. Since additional av ian reproduction data for methomyl could result in a lower avian reproductive endpoint, and, thus, could alter risk conclusions for birds from the use of methomyl, EFED recommends requesting th ese 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 and by extension to terrestrial-phase amphibians and reptiles from meth omyl exposure. If reproduction data are not submitted for mallard ducks, the risks to birds from chronic exposure will be assumed to be higher than

### -73 of 75- predicted when using the chronic toxi city endpoint from Bobwhite quail.

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 “may affect” listed birds, re ptiles, and terrestrial-phase amphibians directly (and listed species from other taxa indirectly), and use of methomyl 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 methomyl 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. None of these indicators are present for methomyl.

Several efficacy studies available for methomyl suppl y information on effects to plants after methomyl applications. None of the studies showed any adverse effects to plants at the highest treatment levels tested. However, because none of the studies address ed potential risks to monocots or effects on seedling emergence and some N-methyl carbamates are pl ant auxins that are used to thin fruit ( e.g ., carbaryl), risks to plants from the use of methomyl cannot be precluded using the available data. Tier I seedling emergence and vegetative vigor studies (OCSPP Gu idelines 850.4100 and 850.4150) are, therefore, required. 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 methomyl 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 use of methomyl. Therefore, use of methomyl 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 methomyl 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 uses (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 required as specified in 40 CFR Part 158 (OCSPP Guideline 850.4400).

### -74 of 75- 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. The data will reduce uncer tainties associated with th e current risk assessment for plants and will improve our understanding of the po tential effects of methomyl 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 dete rmining whether a “may affect” to Federally-listed threatened and endangered species 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 curre nt 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, th e Agency cannot determine the levels of methomyl 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 comp liance with the Endangered Species Act, and could result in use restrictions for methomyl which may otherwise 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 uses (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 (OCSPP Guideline 850.5400). 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. The data will reduce uncer tainties associated with th e current risk assessment for plants and will improve our understanding of the po tential effects of methomyl 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 dete rmining whether a “may affect” to Federally-listed threatened and endangered species 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 curre nt 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, th e Agency cannot determine the levels of methomyl

### -75 of 75- 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 th e label. The lack of these data will limit the flexibility the Agency and registrants have in comi ng into compliance with the Endangered Species Act, and could result in use restrictions for methomyl which may otherwise be avoided, or which are unnecessarily severe.