UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, D. C. 20460 OFFICE OF PREVENTION, PESTICIDES AND TOXIC SUBSTANCES PC Code: 103001 DP Barcodes: D303453 MEMORANDUM March 1, 2005 Subject: EFED risk assessment for the Napropamide Reregistration Eligibility Document To: Susan Lewis, Branch Chief,/ Demson Fuller, Chemical Review Manager Reregistration Branch I Special Review and Reregistration Division ( 7508C)

From: James Breithaupt, Agronomist Fred Jenkins, Fisheries Biologist Environmental Risk Branch II Environmental Fate and Effects Division ( 7507C)

Through: Tom Bailey, Ph. D, Chief, ERB II, Environmental Fate and Effects Division ( 7507C)

In response to the " error only" comments submitted by the Napropamide registrant for the EFED Napropamide draft screening level ecological risk assessment, please see attached EFED's response to the comments. Also attached is the revised risk assessment based on these comments.

The issues regarding the registrant's comments involved the formulation and usage information, physical and chemical properties of napropamide, incorrect references to studies cited and to tables, and data that has not been submitted. Some of these comments were " substantive," meaning that EFED acknowledges the relevance of them but will not address them until the response to public comment period. Also, some comments were " error only" and were incorporated in the ecological risk assessment.

In regards to the formulations and use information comments submitted by the registrant, the registrant correctly noted that certain formulations ( 50 WP, 2 E, and 5 G) are not being supported at this time. EFED deleted from the risk assessment references to these. The remainder of the formulation and use comments were substantive and may be addressed after public comments have been received.

The use of specific chemical, physical, and environmental fate properties in computer modeling of environmental and drinking water exposure was also addressed by the registrant. EFED made changes in the document but did not rerun the modeling at this time. Substantive comments about modeling based on these correct properties may be addressed after public comment has been ii received.

Incorrect tables referenced and studies cited were accurately identified by the registrant and modified in the current document. This " error only" comment has been addressed.

EFED identified an uncertainty regarding the environmental persistence of napropamide based on the large difference in half lives between laboratory and field studies. The registrant states they will submit additional information to explain this discrepancy. This is a substantive comment that may be addressed at a later date..

Ecological effects data were not submitted for several algal and aquatic plant species, such as Lemna gibba, Skeletonema costatum, Anabaena flos aquae, and a freshwater diatom ( such as Navicula pelliculosa). The registrant intends to submit these studies in response to the Draft RED. This is a substantive comment and EFED will evaluate the studies once they are submitted. 1 ENVIRONMENTAL FATE AND EFFECTS SCIENCE CHAPTER For NAPROPAMIDE ( CAS#: 15299 99 7) Diethyl 2( 1 naphthyloxy) propanamide USEPA PC Code: 103001 Re registration Existing Uses: Nuts ( almond, pistachio, pecan, filbert, walnut) Berries/ small fruit ( blackberry, boysenberry, loganberry, raspberry, blueberry, strawberry, cranberry, currant, grape) Brassica and leafy vegetables ( broccoli, brussels sprouts, cabbage, cauliflower, asparagus) Citrus ( grapefruit, lemon, nectarine, orange, tangerine, tangelo) Stone fruit ( apricot, cherry, peach, plum, prune) Pome fruit ( apple, pear) Fruiting vegetables ( eggplant, pepper, tomato) Tropical fruit ( fig, kiwi fruit, persimmon, avocado, pomegranate) Additional crops ( artichoke, rhubarb, tobacco, sweet potato) Oil seed crops ( mint, olive) Trees/ ornamentals ( conifer, shade tree, ornamental tree, ground cover, herbaceous plants, woody shrubs, vines, lawns, turf, potting soil)

End Use Products: Devrinol ® 50 DF, 2 G, 10 G, 4 F ERB II Team: James Breithaupt, Agronomist Fred Jenkins, Fisheries Biologist Michelle Rau Embry, Ph. D., Ecotoxicologist Donna Randall, Senior Aquatic Biologist Environmental Fate and Effects Division ( 7507C)

Secondary Review: Dana Spatz, Risk Assessment Process Leader Environmental Fate and Effects Division ( 7507C)

Branch Chief Approval: Tom Bailey, Chief Environmental Risk Branch II Environmental Fate and Effects Division ( 7507C) 2 TABLE OF CONTENTS I. EXECUTIVE SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 A. Potential Risks to Non target Non endangered Organisms . . . . . . . . . . . . . . . . . . . . . . . 4 B. Potential Risks to Non target Listed and Endangered Organisms . . . . . . . . . . . . . . . . . . 5 C. Major Uncertainties and Data Gaps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 II. PROBLEM FORMULATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 A. Stressor Source and Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 1. Pesticide Type, Class, and Mode of Action . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2. Overview of Pesticide Usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 3. Chemical and Physical Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 a. Fate in the Terrestrial Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 b. Fate in the Aquatic Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 B. Assessment Endpoints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 1. Ecosystems Potentially at Risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 2. Measures of Ecological Effects for Nonlisted Species . . . . . . . . . . . . . . . . . . . . 18 3. Listed Species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 C. Conceptual Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 1. Flowable Napropamide Applied as a Ground Spray . . . . . . . . . . . . . . . . . . . . . 20 a. Terrestrial Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 b. Aquatic Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 2. Granular Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 a. Terrestrial Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 b. Aquatic Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 D. Key Uncertainties and Information Gaps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 E. Analysis Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 1. Specific Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 2. Planned Analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 a. Initial Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 b. Exposure in Terrestrial Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 c. Exposure in Aquatic Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 III. ANALYSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 A. Exposure Characterization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 1. Environmental Fate and Transport Characterization . . . . . . . . . . . . . . . . . . . . . 33 a. Fate in the Terrestrial Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 b. Fate in the Aquatic Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 2. Aquatic Resource Exposure Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 3. Terrestrial Organism Exposure Modeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 a. Granular Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 b. Spray Applications and Residues . . . . . . . . . . . . . . . . . . . . . . . . 42 4. Non Target Plant Exposure Modeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 B. Ecological Effects Characterization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 1. Evaluation of Aquatic and Terrestrial Ecotoxicity Studies . . . . . . . . . . . . . . . . . 45 2. Use of Probit Slope Response Relationship . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 3 3. Incident Data Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 IV. RISK CHARACTERIZATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 A. Risk Estimation  Integration of Exposure and Effects Data . . . . . . . . . . . . . . . . . . . . . 48 1. Non target Aquatic Animals and Plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 2. Non target Terrestrial Animals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 3. Non target Terrestrial and Semi Aquatic Plants . . . . . . . . . . . . . . . . . . . . . . . . 53 B. Risk Description  Interpretation of Direct Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 1. Risk to Aquatic Animals and Plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 2. Risk to Terrestrial Organisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 C. Threatened and Endangered Species Concerns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 1. Taxonomic Groups Potentially at Risk . . . . . . . . . . . . . . . . . . . . . . . . . 60 2. Probit Slope Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 3. Critical Habitats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 4. Indirect Effect Analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 D. Description of Assumptions, Uncertainties, Strengths, and Limitations . . . . . . . . . . . . . 63 1. Assumptions and Limitations Related to Exposure for Terrestrial Species . . . . . 63 a. Location of Wildlife Species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 b. Routes of Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 c. Residue Levels Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 d. Dietary Intake  Difference Between Laboratory and Field Conditions . . 64 e. Estimated Environmental Concentrations for Non Target Plants . . . . . . 64 f. Data Gaps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 2. Assumptions and Limitations Related to Exposure for Aquatic Species . . . . . . . 65 a. Uncertainties in PRZM EXAMS Modeling . . . . . . . . . . . . . . . . . . . . . . 65 b. Uncertainties in the Cranberry Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 3. Assumptions and Limitations Related to Effects Assessment . . . . . . . . . . . . . . . 67 a. Age Class and Sensitivity of Effects Thresholds . . . . . . . . . . . . . . . . . . . 67 b. Use of the Most Sensitive Species Tested . . . . . . . . . . . . . . . . . . . . . . . 67 c. Data Gaps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 4 I. EXECUTIVE SUMMARY Napropamide, also known by the trade name Devrinol ® , is a systemic, preemergent, surfaceapplied substituted amide herbicide used to control annual grassy and broadleaf weeds on a variety of food and non food crops. Napropamide is sold in flowable ( emulsifiable liquid, flowable concentrate, dry flowable), and granular formulations. This compound must be watered in to be effective.

Ground spray ( including some forms of chemigation) of napropamide will result in spray drift onto plants, soil, and water adjacent to a treated field. Based on fate properties, as demonstrated in laboratory studies, and application methods ( i. e., soil incorporation), it is expected that napropamide applied either as a flowable or granular formulation will be persistent in the terrestrial environment resulting in the potential for napropamide to reach the aquatic environment by runoff. Additionally, because laboratory dissipation studies demonstrate a halflife of approximately 446 days there is a potential for napropamide to accumulate in the soil with repeated applications. However, field dissipation studies, where napropamide was soil incorporated) indicate much faster dissipation rates on the order of 17 to 24 days. No explanation for the difference between the persistence predicted by the laboratory data ( stable in all studies except photodegradation) and the field data is evident. Although napropamide can photodegrade in water, this route of dissipation is expected to be impeded when soil incorporation occurs at time of application. In addition, any napropamide that reaches surface water will tend to partition to suspended soils and sediment, thereby reducing the amount available to undergo photolysis. Napropamide is not expected to be a bioaccumulative compound of concern based on submitted data. The major terminal degradate in terrestrial environments is carbon dioxide, but photodegradation in aquatic systems creates isomers of the parent compound.

A screening level assessment of risks to both terrestrial and aquatic organisms from labeled uses of napropamide was performed on geographical areas where the highest use rates and expected exposures are likely to occur. Because the label does not specifically require soil incorporation at the time of application, estimated environmental concentrations ( EECs) in the aquatic environment and for terrestrial and wetland/ riparian plants were determined assuming both soil incorporation and no soil incorporation at the time of application.

C. Potential Risks to Non target Non endangered Organisms For most crops the maximum label rate is either two applications of 4 pounds of active ingredient per acre ( lbs ai/ A), one application of 6 lbs ai/ A, and one application of 2 lbs. ai/ A. Risks to nontarget plants and mammals were determined for these rates in addition to risks to the aquatic environment from a 15 lb ai/ A application for cranberries. Risks to terrestrial and wetland/ riparian plants were determined from a rate 1 lb ai/ A, which represents the lowest average rate for a row crop such as tobacco. These estimates of risk included both the parent compound and the isomers that were formed by photodegradation in water. 5 Aquatic organism risks No acute risk levels of concern ( LOCs) were exceeded for freshwater or marine/ estuarine fish and invertebrates. Chronic risks to aquatic organisms could not be evaluated because there were no chronic data submitted. However, the Agency has determined that chronic toxicity data should be submitted because of the potential environmental persistence of napropamide which may cause chronic exposure to aquatic organisms. Chronic exposure is likely from the compound because the only apparent route of degradation in surface water is by sunlight. Laboratory data show a half life of 6.8 minutes for parent napropamide and 26 minutes for parent + Isomers I and II in clear, shallow, well mixed water. However, persistence is likely to be longer in surface water because of the presence of suspended sediment, shading, deeper water, and cloudy conditions. The half lives in laboratory studies indicate that napropamide is stable to hydrolysis and essentially stable to anaerobic aquatic metabolism and to anaerobic soil metabolism ( T 1/ 2> 51 days).

No LOCs were exceeded for aquatic plants based on a single green algae toxicity study. However, data were not submitted for several algal and aquatic plant species, such as Lemna gibba, Skeletonema costatum, Anabaena flos aquae, and a freshwater diatom ( such as Navicula pelliculosa). Therefore, EFED cannot fully assess the potential adverse effects of napropamide exposure to aquatic plants and algae.

Avian Risks No acute or chronic LOCs were exceeded for birds.

Mammalian Risks No acute LOCs were exceeded for mammals. Chronic LOCs were exceeded for mammals on all food types ( i. e., short grass, tall grass, broadleaf plants and small insects, fruits/ pods/ large insects) at all modeled application rates.

Terrestrial and Wetland/ Riparian Plants For spray chemigation, terrestrial and wetland/ riparian plant ( monocot and dicot) LOCs for seedling emergence in areas adjacent to a treated field were exceeded at all application rates evaluated ( 6, 4, 2, 1 lb ai/ A)

B. Potential Risks to Non target Listed and Endangered Organisms A screening level risk assessment was performed to determine, if any of the Agency's threatened and endangered ( i. e., " listed") species LOC criteria were exceeded for either direct or indirect effects indicating the need for further biological assessment to be undertaken. The following lists the results for potential direct effects. The Endangered Species section discusses these direct effects in addition to the indirect effects listed species LOC screening, a preliminary cooccurrence analysis, and a discussion of what further biological assessment needs to be undertaken to address listed species concerns. 6 Aquatic Listed Species There were no exceedances of listed acute LOC criteria for freshwater or estuarine/ marine fish or crustaceans, which is assumed to represent all aquatic invertebrates except mollusks. No direct mortality effects from napropamide are expected to these species.

For soil incorporation to 2 inches at time of application, there were no exceedances due to runoff and spray drift of the listed species acute LOC for mollusks for any of the labeled uses evaluated. For no soil incorporation at the time of application, there were no exceedances due to runoff and spray drift of the listed mollusk acute LOC for all crops and labeled uses except for scenarios representing use in the southeastern United States at typical maximum label rates. Florida citrus at an application rate of 4 lbs ai/ A applied twice a year with a 7 day interval between applications had an RQ = 0.053, listed species LOC = 0.05. The endangered species LOC was also exceeded for mollusks exposed to runoff following application to Georgia pecans at 4 lbs ai/ A applied twice a year with a 7 day interval between applications and 6 lbs ai/ A applied once a year ( RQ = 0.088 and 0.073, respectively). The Agency recognizes that there are no Federally listed estuarine/ marine mollusks but there are listed freshwater mollusks in southeastern states that overlap napropamide use.

Chronic risks could not be evaluated because there were no chronic data. However, the Agency has determined that chronic toxicity data should be submitted because of the potential environmental persistence of napropamide which may cause chronic exposure to aquatic organisms. Chronic exposure is likely from the compound because the only apparent route of degradation in surface water is by sunlight. Laboratory data show a half life of 26 minutes in clear, shallow, well mixed water. However, persistence is likely to be longer in surface water because of the presence of suspended sediment, shading, deeper water, and cloudy conditions. The half lives in laboratory studies indicate that napropamide is stable to hydrolysis and essentially stable to anaerobic aquatic metabolism and to anaerobic soil metabolism ( T 1/ 2> 51 days)

Avian Listed Species No acute RQs were calculated for birds exposed to napropamide via spray or granular application because the core acute toxicity studies demonstrated that the LC50 and LD50 were greater than the greatest dose tested ( highest dose tested in the acute dietary test was 7200 ppm; highest dose tested in the acute oral test was 4640 mg/ kg ). These results classify napropamide as practically nontoxic to birds. Therefore the maximum avian environmental dietary exposure concentration of napropamide ( 1796 ppb) ( See ELL FATE Model Appendix C) is not expected to cause significant acute toxicity to birds.

No chronic RQ values were calculated for birds because Chronic RQ values for birds were not calculated because decreased body weights measured in the core chronic toxicity study were deemed unrelated to napropamide exposure ( See Appendix E, Table 2). No direct effects from napropamide are expected to any listed bird species. 7 Mammalian Listed Species In mammalian laboratory studies, the highest residues expected on food items in the field are not expected to pose an significant acute risk to mammals( i. e., acute listed species LOCs are not exceeded). No acute direct effects from napropamide are expected to listed mammalian species.

Chronic LOCs, based on reduced parental and offspring body weight were exceeded for mammals on all food types ( i. e., short grass, tall grass, broadleaf plants and small insects, fruits/ pods/ large insects) for all the modeled use rates.

Terrestrial and Wetland/ Riparian Listed Plants For spray chemigation, listed terrestrial and wetland/ riparian plant ( monocot and dicot) LOCs for seedling emergence in areas adjacent to a treated field were exceeded at all application rates evaluated ( 6, 4, 2, 1 lb ai/ A).

C. Major Uncertainties and Data Gaps ° Data were not submitted for several algal and aquatic plant species, such as Lemna gibba, Skeletonema costatum, Anabaena flos aquae, and a freshwater diatom ( such as Navicula pelliculosa). Therefore, EFED cannot fully assess the potential adverse effects of napropamide exposure to aquatic plants and algae.

° Intervals between applications were not established on labels. The assumption of a 7 day interval used for modeling surface water concentrations and foliar dissipation may be too short of a time period resulting in an overestimate of residues in water and on food items.

° The extent of photodegradation in surface water is uncertain. While napropamide is persistent in the field, laboratory studies demonstrated rapid ( t 1/ 2 = 6.8 minutes for parent napropamide and 26 minutes for parent + Isomers I and II) aqueous photolysis in clear, shallow, well mixed water. In contrast, surface water in the natural environment usually contains suspended solids, significantly reducing sunlight penetration and subsequent napropamide degradation. Therefore, EECs in surface water may be underestimated.

° Currently, EFED cannot assess the chronic risk of napropamide to aquatic organisms because chronic toxicity data was not submitted to the Agency. However, the Agency has determined that chronic toxicity data should be submitted because of the potential environmental persistence of napropamide which may cause chronic exposure to aquatic organisms. Chronic exposure is likely from the compound because the only apparent route of degradation in surface water is by sunlight. Laboratory data show a half life of 26 minutes in clear, shallow, well mixed water. However, persistence is likely to be longer in surface water because of the presence of suspended sediment, shading, deeper water, and cloudy conditions. The halflives in laboratory studies indicate that napropamide is stable to hydrolysis and essentially stable to anaerobic aquatic metabolism and to anaerobic soil metabolism ( T 1/ 2> 51 days).

° No explanation for the difference between the persistence predicted by the laboratory data 8 O N O Napropamide structure ( molecular formula C17H21NO2) ( stable in all studies except photodegradation) and the field data has been put forth by the registrant ( photolysis was not considered a major route of dissipation since the product was soil incorporated). The fate of napropamide under field conditions remains an uncertainty.

° No foliar dissipation studies were submitted by the registrant. Therefore, EFED must use the default foliar half life of 35 days to determine foliar residues.

II. PROBLEM FORMULATION A. Stressor Source and Distribution Napropamide, also known by the trade name Devrinol ® , is a preemergent, surface applied substituted amide herbicide ( Figure 1) used to control annual grassy and broadleaf weeds on a variety of food and non food crops. Napropamide is sold in flowable ( emulsifiable liquid ( Devrinol ® 2 EC), flowable concentrate ( Devrinol ® F), dry flowable ( Devrinol ® 50 DF)), and granular ( Devrinol ® G) formulations. Commercial products are available in several different napropamide active ingredient concentrations, ranging from 2 to 50 percent.

1. Pesticide Type, Class, and Mode of Action Napropamide acts as a preemergent, systemic herbicide and is mobile in plant tissues. Napropamide is a substituted amide herbicides and this class of herbicides have no consistent pattern in their mechanisms of action. For napropamide, it is absorbed by developing weed plant roots, inhibiting their development and growth. Additionally, napropamide may inhibit shoot growth, by blocking the progression of dividing cells through the cell cycle into mitosis. Napropamide can be applied either in the spring for control of summer annuals or in the fall for winter annuals. 9 2. Overview of Pesticide Usage Non granular forms of napropamide are applied via several methods, including broadcast spray, band treatment, directed spray, strip treatment, soil broadcast, and chemigation. For napropamide to be effective in controlling target weeds, soil incorporation to a depth of 2 to 4 inches by mechanical tillage ( e. g., hand cultivator), irrigation, or rainfall must follow napropamide application within a few days for it to be present at the developing root depth. Watering in or chemigation may be the only choices for soil incorporation of napropamide in orchard and vineyard crops, cranberries and other permanent berry bush crops, shade and ornamental trees, shrubs, ground cover, and turf because root damage to these crops could occur from mechanical tillage. However, vegetable crops may allow for tillage, irrigation, chemigation, or rainfall incorporation methods into soil.

Approximately 448,000 pounds of napropamide were applied in 1997 according to the National Center for Food and Agriculture, and the majority was applied to tomatoes ( 23.5%), tobacco ( 20.7%), cranberries ( 11.8%), hot peppers ( 10.2%), and strawberries ( 8.9%). Together, these crops account for 75% of napropamide applied to food crops nationwide. Additionally, nonfood crop uses of napropamide include turf, trees, and ornamentals. According to the National Agriculture Statistics Service ( NASS), napropamide is used at the highest rates in North Carolina, Pennsylvania, Georgia, Florida, Kentucky, California, and Oregon.

Table 1 presents a detailed napropamide use characterization based on maximum labeled use rates. A number of labels do not explicitly limit the number of times napropamide can be applied per year ( Table 1). The highest labeled application rate is on cranberries ( 15 lbs ai/ A), assuming a single application per year. Ornamental and shade trees, conifers, herbaceous vines and shrubs, and ground cover application rates are potentially at least 12 lbs ai/ A total ( 6 lbs ai/ A with a 90 day interval between applications implying at least two applications per year). Maximum label rates for the remaining crops range from 2 lbs ai/ A to 8 lbs ai/ A. Maximum label rates for those crops where a majority of napropamide is used ( tomatoes, tobacco, cranberries, hot peppers, and strawberries) are two applications per year at 4 lbs ai/ A ( total 8 lbs ai/ A) or one application per year at 6 lbs ai/ A. Average napropamide use rates for eleven crops ( almonds, apples, blueberries, cranberries, grapes, oranges, pecans, peppers, strawberries, tobacco, tomatoes) were provided by the Office of Pesticide Programs' ( OPP's) Biological and Economic Analysis Division ( BEAD) and are presented in Table 2. Average application rates for these eleven crops range from 1.0 lb ai/ A for tobacco to 5.3 lbs ai/ A for cranberries. 10 Table 1. Use information for napropamide  maximum labeled use rates Crop Formulation Max App ( a) Rate ( lbs ai/ A) No. ( b)

App/ yr App interval ( days)( c)( d) Max load/ yr ( lbs ai/ A) App method ( e)

Nuts Almond, Pistachio DF 4 2 NS 8 B, C Pecan Filbert Walnut G 4 NS NS unknown B, C DF 4 2 NS 8 B, C Berries and Small Fruit Blackberry Boysenberry Loganberry Raspberry F1C 4 1 NA 4 B DF 4 NS NS unknown B, C, SB G 4 NS NS unknown B, C, SB Blueberry DF 4 NS NS NS B, C, SB G 4 NS NS NS B, C, SB Strawberries G 4 NS NS unknown B, C DF 4 NS NS unknown B, C Cranberries G 9 1 NA 9 B 15 NS NS unknown B Currants DF 4 NS NS unknown B, C Grapes G 4 NS NS unknown B, C DF 4 2 NS 8 B, C Brassica and Leafy Vegetables Broccoli, Brussels Sprouts Cabbage, Cauliflower Asparagus DF 2 NS NS unknown B, C, SB, SI, SPR Citrus Grapefruit F1C 4 1 NA 4 B G 4 NS NS unknown B, C DF 4 2 NS 8 B, C Lemon Nectarine Orange Tangerine Tangelo DF 4 2 NS 8 B, C G 4 NS NS unknown B, C DF 4 2 NS 8 B, C Stone Fruit Crop Formulation Max App ( a) Rate ( lbs ai/ A) No. ( b)

App/ yr App interval ( days)( c)( d) Max load/ yr ( lbs ai/ A) App method ( e)

11 Apricot Cherry Peach Plum Prune G 4 NS NS unknown B, C DF 4 2 NS 8 B, C Crop Formulation Max App ( a) Rate ( lbs ai/ A) No. ( b)

App/ yr App interval ( days)( c)( d) Max load/ yr ( lbs ai/ A) App method ( e)

12 Pome Fruit Apple Pear G 4 NS NS unknown B, C DF 4 2 NS 8 B, C Fruiting Vegetables Eggplant F1C 2 1 NA unknown SI DF 2 NS NS unknown B, C, SB Pepper Tomato EC 2 1 NA 2 BT, B, SI, ST Other Vegetables Artichoke Rhubarb DF 4 NS NS unknown B, C, SB Tropical Fruits Fig F1C 4 1 NA 4 B DF 4 2 NS 8 B, C Kiwi Fruit Persimmon Avacado DF 4 2 NS 8 B, C Pomegranate DF 4 NS NS unknown B, C Additional Crops Tobacco F1C 2 1 NA 2 BT, B, SI, ST DF 2 1 NA 2 B EC 2 1 NA 2 BT, B, SI, ST Sweet Potato DF 2 NS NS unknown S, B Crop Formulation Max App ( a) Rate ( lbs ai/ A) No. ( b)

App/ yr App interval ( days)( c)( d) Max load/ yr ( lbs ai/ A) App method ( e)

13 Oil Seed Crops Mint G 4 NS NS unknown B, C DF 4 NS NS unknown B, C Olives DF 4 2 NS 8 B, C Trees/ Ornamentals Conifer release Shade Trees/ Ornamental Trees G 6 NS 90 unknown B EC 6 1 NA 6 G, BT, SI, DS G 6 NS 90 unknown BT, B, IR Ground cover G 6 NS 90 unknown BT, B, IR EC 6 1 NA 6 B, SI, SPR Herbaceous plants/ woody shrubs / vines EC 6 1 NA 6 BT, B, DS, SI G 6 NS 90 unknown BT, B, SI, IR lawns & turf EC 6 1 NA 6 BT, B, DS, SI, SPR G 6 NS NS unknown BT, B, IR potting soil EC 6 1 NA 6 BT, B, SI, SPR ( a) App = Application ( b) No. = Number ( c) NA = not applicable ( d) NS = not specified on label ( e) Application method codes: B = broadcast C = chemigation SB = soil broadcast ST = strip treatment BT = band treatment G = ground SI = soil incorporation DS = directed spray IR = irrigation incorporation SPR = spray 14 Table 2. Napropamide average use rates Crop Average use rate ( lbs ai/ A per application) Average annual number of applications Almonds 3.2 1.0 Apples 3.0 2.0 Blueberries 2.0 1.0 Strawberries 2.6 1.0 Citrus ( orange) 3.0 1.0 Cranberries 5.3 NA Grapes 3.0 1.0 Pecans 4.0 3.0 Peppers 1.3 1.0 Tobacco 1.0 1.0 Tomatoes 1.6 1.0 Sources: USDA NASS, EPA proprietary data, NCFAP Years: 1998 2003 3. Chemical and Physical Properties A summary of fate properties for napropamide from laboratory studies is listed in Table 3. Based on fate properties, as demonstrated in laboratory studies, and application methods ( i. e., soil incorporation), it is expected that napropamide applied either as a flowable or granular formulation will be persistent in the terrestrial environment resulting in the potential for napropamide to reach the aquatic environment by runoff. Additionally, because laboratory dissipation studies demonstrate a half life of approximately 446 days there is a potential for napropamide to accumulate in the soil with repeated applications. However, field dissipation studies, where napropamide was soil incorporated) indicate much faster dissipation rates on the order of 17 to 24 days. No explanation for the difference between the persistence predicted by the laboratory data ( stable in all studies except photodegradation) and the field data is evident. Although napropamide can photodegrade in water, this route of dissipation is expected to be impeded when soil incorporation occurs at time of application. In addition, any napropamide that reaches surface water will tend to partition to suspended soils and sediment, thereby reducing the amount available to undergo photolysis. Napropamide is not expected to be a bioaccumulative compound of concern based on submitted data. The major terminal degradate in terrestrial environments is carbon dioxide, but photodegradation in aquatic systems creates isomers of the parent compound. 15 Table 3. Summary of Fate Properties of Napropamide Property Napropamide Data Physical state at room temperature solid Molecular weight 271.36 Vapor Pressure at 20

C ( millimeters mercury; mm Hg) 1.7 x 10 7 Henry's Law Constant at 20

C ( atm m3/ mol) 8.1 x 10 10 Water solubility at 20

C ( milligrams per liter; mg/ l) 74 Hydrolysis Stable ( MRID 41863201)

Direct Aqueous Photolysis ( half life, minutes) 6.8 minutes for parent napropamide, 26 minutes for napropamide plus Isomers I and II ( MRIDs 41575301, 43175301)

Soil Photolysis ( half life, days) Stable ( MRID 41863202)

Aerobic Soil Metabolism ( half life, days) 446 ( MRID 41105901)

Anaerobic Soil Metabolism ( half life, days) 51 ( a)

( MRIDs 00163271, 92125017)

Anaerobic Aquatic Metabolism ( half life, days) Essentially stable ( MRID 42699701)

Aerobic Aquatic Metabolism ( half life, days) NO DATA Kd ads / Kd des ( milliliters/ gram) 8.6/ 480 ( loam) 5.1/ 465 ( loamy sand) 3.4/ 1170 ( sandy loam) 14.8/ 674 ( silt loam) ( MRID 41575302)

Log octanol water partition coefficient ( log Kow) 3.4 Soil Dissipation ( half life, days) 17 ( MS) 17 24 ( CA) ( MRIDs 43742401, 43742402)

Sediment Dissipation ( half life, days) NO DATA Aquatic Dissipation ( half life, days) NO DATA Fish Accumulation ( BCF); concentration in tissue to exposure concentration in water 32 35 in edible tissues 90 % depuration by 7 days ( MRID 92125019) ( a) Half life is highly uncertain due to poor material balance at 90 days ( 60 days of anaerobic conditions). 16 a. Fate in the Terrestrial Environment Napropamide is expected to have moderate to low mobility in soil based upon batch equilibrium studies showing K ads values averaging 3.38 for a sandy loam, 5.12 for a loamy sand, 8.63 for a loamy sand, and 14.8 ml/ g for a silt loam soil. The soil K oc values for adsorption were 1170, 465, 480, and 674 ml/ g, respectively. Adsorption of napropamide to soil increases with increasing clay content, organic carbon content, and pH. Napropamide is not expected to volatilize from dry soil surfaces based upon its vapor pressure of 1.7 x 10 7 mm Hg.

Napropamide does photodegrade on soil with a half life of 28 days. The major degradate is carbon dioxide. However, it is important to note that napropamide must be incorporated into the soil within days of application in order to be efficacious, therefore, photodegradation on soil is not expected to be a major route of dissipation. Microbial degradation of napropamide in soil under aerobic laboratory conditions is very slow with an estimated half life of 446 days. This suggests that the chemical may accumulate in soil with repeated applications. However, terrestrial field dissipation half lives ranged from 17 to 24 days, dependent on application method, product formulation, and soil type.

b. Fate in the Aquatic Environment In water, napropamide is expected to adsorb to suspended solids and sediment. Napropamide is stable to hydrolysis at pH's 5, 7, and 9, but undergoes rapid direct photolysis in water with a half life of 6.8 minutes for parent napropamide. Identified degradates were Isomer I and Isomer II ( propionamide). The two isomers also degrade rapidly, as the total residue ( napropamide plus Isomers I and II) half life in the photodegradation in water study was only 26 minutes. Because of light attenuation, aqueous photolysis will be an important pathway only in shallow clear water bodies. Binding to suspended solids and sediment can also diminish the role photolysis plays in the degradation of napropamide. Neither volatilization from water nor bioconcentration are expected to be important fate processes based upon this compound's estimated Henry's Law constant of 8.1 x10 10 atm m3/ mole, and BCF ( 32 to 35 in edible fish tissue).

B. Assessment Endpoints Assessment endpoints are defined as " explicit expressions of the actual environmental value that is to be protected. " Two criteria are used to select the appropriate ecological assessment endpoints: 1) identification of the valued attributes of the environment that are considered to be at risk, and 2) the operational definition of assessment endpoints in terms of an ecological entity ( i. e., a community of fish and aquatic invertebrates) and its attributes ( i. e., survival and reproduction). Therefore, the selection of assessment endpoints is based on valued entities ( i. e., ecological receptors), the ecosystems potentially at risk, the migration pathways of pesticides, and the routes by which ecological receptors are exposed to pesticide related contamination. The selection of clearly defined assessment endpoints is important because they provide direction and boundaries in the risk assessment for addressing risk management issues of concern. 17 2. Ecosystems Potentially at Risk Ecosystems potentially at risk are expressed in terms of the selected assessment endpoints. The typical assessment endpoints for screening level pesticide ecological risks are reduced survival and reproductive and growth impairment for both aquatic and terrestrial animal species. A set of surrogate species is used to provide an estimation of ecological risk. Ecological relevance and sensitivity are essential for selecting test species and assessment endpoints that are scientifically defensible. Surrogate taxa include freshwater fish and invertebrates, estuarine/ marine fish and invertebrates, and amphibians. In the absence of toxicity data on aquatic phase amphibians, it is assumed that aquatic phase amphibians are approximately as sensitive as fish to the potential effects of a pesticide. Terrestrial animals used as test species include birds and mammals. The risk assessment assumes that reptiles and terrestrial phase amphibians are approximately as sensitive to pesticide induced effects as are birds. Potential effects to benthic organisms may also be evaluated if environmental fate data indicate that the assessed chemical may partition to the sediment or if sediment organisms are particularly sensitive species. Direct acute and direct chronic effects are considered for both aquatic and terrestrial animals. Although these endpoints are measured at the individual level, they provide insight about risks at higher levels of biological organization ( i. e., populations and communities). For example, pesticide effects on individual survivorship have important implications for both population level effects as well as habitat carrying capacity. Indirect effects on critical habitat are only considered in the risk characterization for the potential effects on endangered species, provided that the risk quotient demonstrates probable risk.

The screening assessment endpoint for plants in terrestrial and semi aquatic environments is the perpetuation of populations of non target species ( both crop and non crop species). Endpoints assessed include seedling emergence and vegetative vigor. Although it is recognized that the seedling emergence and vegetative vigor endpoints may not address all plant life cycle components, it is assumed that impacts at emergence and during active growth may impact individual competitive ability and reproductive success. Data on the formulated product ( as opposed to the active ingredient) are used to characterize plant exposure effects. If the maximum exposure rate results in an effect level that is less than 25% in a Tier I study, low risk is presumed and a Tier II study is not required. However, if the effect level is less than 25% but greater than 5% in a Tier I study, potential risk may still occur to endangered species that cannot be quantified.

The assessment endpoint for aquatic plants is the maintenance and growth of standing crop or biomass. Measurement endpoints focus on algal and vascular plant ( i. e., duckweed) growth rates and biomass measurements.

The ecological relevance of selecting the above mentioned assessment endpoints is three fold, and includes the following: 1) complete exposure pathways exist for the receptors; 2) the receptors are potentially sensitive to pesticides in the affected media and from residues on plants, seeds, insects, and other food sources; and 3) the receptors could inhabit areas where pesticides are applied or where runoff and/ or spray drift could impact sites containing available suitable 18 habitat.

2. Measures of Ecological Effects for Nonlisted Species Each assessment endpoint requires one or more " measures of ecological effect," which are defined as changes in the attributes of an assessment endpoint itself or changes in a surrogate entity or attribute in response to pesticide exposure. Ecological measurement endpoints for the screening level risk assessment are based on a suite of registrant submitted toxicity studies performed on a limited number of organisms in the following broad groupings:

° Birds ( mallard duck and bobwhite quail) used as surrogate taxa for terrestrial phase amphibians and reptiles ° Mammals ( laboratory rat) ° Freshwater fish ( bluegill sunfish and rainbow trout) used as a surrogate for aquatic phase amphibians ° Freshwater invertebrates ( water flea  Daphnia magna) ° Estuarine/ marine fish ( sheepshead minnow) ° Estuarine/ marine invertebrates ( Eastern oyster and mysid shrimp) ° Terrestrial plants ( corn, onion, ryegrass, wheat, buckwheat, cucumber, soybean, sunflower, tomato, and turnip) ° Algae and aquatic plants ( algae, diatoms, and duckweed)

Within each of these very broad taxonomic groups, an acute and chronic endpoint is selected from the available test data, as the data sets allow. A discussion of some toxicity data available for this risk assessment and the resulting measurement endpoints selected for each taxonomic group is included in Section III of this document. A summary of the assessment and measurement endpoints selected to characterize potential ecological risk associated with napropamide exposure is provided in Tables 15 17.

3. Listed Species Measures of Effect An evaluation of the potential for individual effects at exposure levels equivalent to the level of concern ( LOC) is made based on the median lethal dose estimate and dose response relationship established for the effects study corresponding to each taxonomic group for which the LOCs are exceeded. Proximity of endangered species habitats to areas that grow target crops or contain target weed populations are also evaluated. 19 Table 4. Summary of assessment and measurement endpoints Assessment Endpoint Measurement Endpoints 1. Abundance ( i. e., survival, reproduction, and growth) of individual birds 1a. Mallard duck acute oral LD50 1b. Bobwhite quail subacute dietary LD50 1c. Mallard duck chronic reproduction NOAEL 2. Abundance ( i. e., survival, reproduction, and growth) of individual mammal 2a. Laboratory rat acute oral LD50 2b. Laboratory rat chronic ( reproductive) NOAEC 3. Survival and reproduction of freshwater fish and invertebrates 3a. Rainbow trout acute LC50 3b. Freshwater fish chronic NOAEC ( weight & length)  NO STUDIES SUBMITTED 3c. Water flea acute EC50 3d. Water flea chronic NOAEC ( offspring)  NO STUDIES SUBMITTED 4. Survival and reproduction of estuarine/ marine fish and invertebrates 4a. Sheepshead minnow acute LC50 4b. Estuarine/ marine fish chronic NOAEC & LOAEC  NO STUDIES SUBMITTED 4c. Eastern oyster acute EC50 4d. Estuarine/ marine invertebrate chronic NOAEC & LOAEC  NO STUDIES SUBMITTED 5. Perpetuation of individuals and populations of non target terrestrial plants ( crops and non crop plant species) 5a. Monocot and dicot seedling emergence EC25 5b. Monocot and dicot vegetative vigor EC25 6. Survival of beneficial insects 6a. Honeybee acute contact LD50  NO DATA SUBMITTED 7. Maintenance and growth of aquatic plants from standing crop or biomass NO STUDIES SUBMITTED 7a. Algae and duckweed acute EC50 7b. Algae and duckweed NOAEC/ EC05 7a. Algae and duckweed EC50 and NOAEC/ EC05  INCOMPLETE DATA SET LD50 = Lethal dose to 50% of the test population NOAEC = No observed adverse effect concentration LOAEC  Lowest observed adverse effect concentration LC50 = Lethal concentration to 50% of the test population EC50/ EC25 = Effect concentration to 50%/ 25% of the test population 20 C. Conceptual Model A conceptual model ( CM), which summarizes graphically the results of the problem formulation for evaluating risks to ecological receptors following application of napropamide to an agricultural field ( i. e., orchards, vineyards, row crops) or to turf, is provided in Figure 2 for flowable napropamide ( i. e., dry flowable, and emulsifiable concentrate) applied as a ground spray and in Figure 3 for napropamide applied as a granular. The CMs are working hypotheses about how napropamide is likely to reach ( i. e., exposure pathways) and affect ecological entities ( i. e., attribute changes) of concern on and adjacent to a treated agricultural field. In order for a pesticide stressor to pose an ecological risk, it must reach an ecological receptor in biologically significant concentrations. The CMs outline specifically which measures of exposure ( e. g., foliar residue levels, water column concentrations), ecological receptors, and measures of effects or measurement endpoints will be used to estimate risks ( i. e., estimate the effects of exposure on assessment endpoints) from proposed reregistration uses of napropamide. Narrative descriptions of the risk hypotheses are provided in Section II. C. 1 for flowable napropamide applied as a ground spray and Section II. C. 2 for granular napropamide uses.

1. Flowable Napropamide Applied as a Ground Spray a. Terrestrial Environment Immediately following ground spraying without soil incorporation, the highest napropamide residue levels are expected to be located in the soil and on seeds and insects on the soil surface for a treated agriculture site and foliage, primarily short grasses, of treated turf sites. For application to an agricultural field, surface soil and seeds and insects on the soil surface are expected to contain the highest residues because except for the vines in vineyards and trees in orchards, plant material such as grasses, fruit, and foliage are expected to be non existent to limited on agricultural fields at the time of napropamide application as it is applied to bare soil as a pre emergence herbicide. However, at a turf site much of the applied pesticide may be intercepted by the foliage present instead of reaching soil directly. Later watering in either by irrigation or a rain event is expected to result in lower residues for these media at agricultural fields and turf sites. Napropamide is water soluble, such that residues on plants and insects should decrease due to wash off and residues in soil decrease with dispersion through the soil column. As no major degradates of napropamide have been observed to form in terrestrial environments, the focus of the assessment for these media is on the parent, napropamide.

Napropamide may reach off field terrestrial or riparian/ wetland vegetation environments in spray drift at the time of application. Following a rain event napropamide may also reach off field terrestrial or riparian/ wetland vegetation environments in sheet and channel flow runoff since napropamide is moderately persistent in terrestrial environments and relatively soluble in water. Because in terrestrial environments napropamide is moderately persistent and no major degradates form, the parent, napropamide is the focus of the assessment for off field terrestrial environments. 21 Potential emission of volatilized napropamide to the air is not expected to be a significant acute short range or long range dissipation route for this pesticide because of its low volatility in combination with its relatively fast photodegradation potential. On Figure 1 the dashed outline box around volatilization signifies that this source/ transport pathway is not considered a viable significant release mechanism for flowable napropamide following application to an agricultural field or turf site.

Ecological receptors of concern identified for consideration in the terrestrial environment include primary producers, represented by both upland and wetland/ riparian vegetation, and secondary and tertiary consumers, both vertebrates and invertebrates, representing common ecological functional feeding groups ( i. e., herbivores and insectivores). Herbivores as used here include animals that feed on foliage ( stems and leaves), seeds, and/ or fruit; the term granivore is sometimes used to identify animals that feed primarily on seeds. Omnivores ( i. e., consumers that feed on a mixed diet of animals and plants) are also potentially exposed but are not specifically included in the receptor list for a screening level risk assessment because exposure concentrations and risk levels will fall between the exclusive feeding groups. Food chain transfer through biomagnification or bioaccumulation of napropamide to higher trophic level predators ( e. g., carnivores) is not considered as a viable significant exposure pathway for napropamide since its octanol water partition coefficient is low, and is expected to be rapidly metabolized or eliminated.

Based on the above sources/ transport pathways, exposure media, and potential receptors of concern, specific questions or risk hypotheses formulated to characterize direct effects of flowable napropamide following application on agricultural fields and turf sites to selected assessment endpoints is provided below.

Terrestrial Environment Risk Hypotheses for Flowable Napropamide Uses ° A reduction in the number of terrestrial herbivore and insectivore vertebrates ( birds, mammals, reptiles, terrestrial phase amphibians) will occur if napropamide residues on seeds, insects, and foliage due to direct deposition or spray drift reach levels of concern for acute survival.

° A reduction in the number of upland plants will occur in areas adjacent to a field following napropamide application if soil concentrations of napropamide from spray drift alone or in concert with surface water runoff reach levels of concern for emergence of upland vegetation ( primarily grasses due to napropamide's specificity).

° A reduction in the number of upland plants will occur in areas adjacent to a field following napropamide application if spray drift concentrations reach levels of concern for vegetative vigor.

° A reduction in the number of riparian/ wetland plants will occur in areas adjacent to a field following napropamide application if soil concentrations of napropamide from spray drift alone or in concert with surface water runoff reach levels of concern for emergence of upland 22 vegetation ( primarily grasses due to napropamide's specificity).

° A reduction in the number of riparian/ wetland plants will occur in areas adjacent to a field following napropamide application if spray drift concentrations reach levels of concern for vegetative vigor.

b. Aquatic Environment Napropamide may reach aquatic environments in spray drift downwind of a field being treated. Following a rain event napropamide may also reach aquatic environments from areas of application in sheet and channel flow runoff since napropamide is moderately persistent in terrestrial environments and relatively soluble in water. Because in terrestrial environments napropamide is moderately persistent and no major degradates form, napropamide is the expected form to be present in runoff and soil erosion. Once napropamide reaches the aquatic environment, napropamide is expected to also be moderately persistent. While laboratory data support a 4.3 minute half life in clear, shallow, irradiated water, surface water usually has dissolved and suspended solids and/ or shading that slow the rate of degradation.

For the aquatic ecosystem ecological receptors include all aquatic life ( fish, amphibians, invertebrates, plants) and those terrestrial animals ( e. g., birds and mammals) that consume aquatic organisms.

Based on the above sources/ transport pathways, exposure media, and potential receptors of concern, specific questions or risk hypotheses formulated to characterize direct effects of flowable napropamide following application on agricultural fields and turf sites to selected assessment endpoints is provided below.

Aquatic Environment Risk Hypotheses for Flowable Napropamide Uses ° A reduction in the number of aquatic invertebrates and fish will occur in areas adjacent to a field following napropamide application if spray drift alone or in concert with runoff result in water concentrations that reach levels of concern for acute mortality.

° A reduction in aquatic plants will occur in areas adjacent to a field following napropamide application if spray drift alone or in concert with runoff result in water concentrations that reach levels of concern for algae population growth or macrophyte population growth. 23 2. Granular Applications a. Terrestrial Environment Immediately following granular applications without soil incorporation, granules are expected to be available at the soil surface on agriculture sites and on the surface of the turf at turf sites. Later watering in either by irrigation or a rain event of sufficient size is expected to result in the movement of napropamide down into the soil column.

Receptors of concern are the same as those discussed for flowable applications of napropamide and the terrestrial environment.

Based on the sources/ transport pathways, exposure media, and potential receptors of concern, specific questions or risk hypotheses formulated to characterize direct effects of granular napropamide following application on agricultural fields and turf sites to selected assessment endpoints is provided below.

Terrestrial Environment Risk Hypotheses for Granular Napropamide Uses A reduction in the number of birds or mammals will occur if granular concentrations of napropamide at the surface reach levels of concern for acute mortality from ingestion.

A reduction in the number of upland plants will occur in areas adjacent to a field following napropamide application if soil concentrations of napropamide from surface water runoff reach levels of concern for emergence of upland vegetation ( primarily grasses due to napropamide's specificity).

A reduction in the number of riparian/ wetland plants will occur in areas adjacent to a field following napropamide application if soil concentrations of napropamide from surface water runoff reach levels of concern for emergence of upland vegetation ( primarily grasses due to napropamide's specificity).

b. Aquatic Environment Following a rain event of sufficient size napropamide may also reach aquatic environments from areas of application in sheet and channel flow runoff since napropamide is moderately persistent in terrestrial environments and relatively soluble in water. Because in terrestrial environments napropamide is moderately persistent and no major degradates form, napropamide is the expected form to be present in runoff and soil erosion. Once napropamide reaches the aquatic environment, napropamide is expected to also be moderately persistent.

Receptors of concern are the same as those discussed for flowable applications of napropamide and the aquatic environment. 24 Based on the above sources/ transport pathways, exposure media, and potential receptors of concern, specific questions or risk hypotheses formulated to characterize direct effects of flowable napropamide following application on agricultural fields and turf sites to selected assessment endpoints is provided below.

Aquatic Environment Risk Hypotheses for Granular Napropamide Uses A reduction in the number of aquatic invertebrates and fish will occur in areas adjacent to a field following napropamide application if spray drift alone or in concert with runoff result in water concentrations that reach levels of concern for acute mortality from gill and dermal contact or reach levels of concern for chronic mortality, reproduction, or growth from gill and dermal contact.

A reduction in aquatic plants will occur in areas adjacent to a field following napropamide application if spray drift alone or in concert with runoff result in water concentrations that reach levels of concern for aquatic plant standing crop or biomass. 25 Stressor Napropamide applied as ground spray to an agricultural field Source/ Transport Pathways Volatilization / Wind Suspension Direct Deposition Spray Drift Runoff/ Erosion Leaching ( Infiltration/ Percolation Source/ Exposure Media Terrestrial Food Residues ( foliage,

fruit, insects Upland Foliage/ Soil Riparian/

Wetland Foliage/ Soil Water body Groundwater Exposure Route Ingestion Direct contact/

Root Uptake Direct contact/

Root Uptake Gill/ Integument Uptake Receptors Attribute Changes Terrestrial Vertebrates Birds, Mammals,

Reptiles, Terrestrial Phase Amphibians Terrestrial Upland Plants Individual Animals Reduced survival Reduced growth Reduced reproduction Aquatic Invertebrates Aquatic Vertebrates Aquatic Plants Wetland/

Riparian Plants Individual Plants Seedling emergence Vegetative vigor Individual vertebrates and invertebrates Reduced survival Reduced growth Reduced reproduction Bioaccumulation Plant population Reduced population growth Figure 3. Ecological Conceptual Model for Screening Level Risk Assessment of Napropamide Applied as a Ground Spray to an Agricultural Field or Turf Site 26 Stressor Napropamide applied as a granular to an agricultural field Source/ Transport Pathways Direct Deposition Runoff/ Erosion Leaching ( Infiltration/ Percolation Source/ Exposure Media Upland Soil Upland Soil Riparian/

Wetland Soil Water body Groundwater Exposure Route Ingestion Direct contact/

Root Uptake Direct contact/

Root Uptake Gill/ Integument Uptake Receptors Attribute Changes Terrestrial Vertebrates Birds, Mammals,

Reptiles, Terrestrial Phase Amphibians Terrestrial Upland Plants Individual Animals Reduced survival Reduced growth Reduced reproduction Aquatic Invertebrates Aquatic Vertebrates Aquatic Plants Wetland/

Riparian Plants Individual Plants Seedling emergence Vegetative vigor Individual vertebrates and invertebrates Reduced survival Reduced growth Reduced reproduction Bioaccumulation Plant population Reduced population growth Figure 4. Ecological Conceptual Model for Screening Level Risk Assessment of Napropamide Applied as a Granular Broadcast or In Furrow to an Agricultural Field or Turf Site 27 D. Key Uncertainties and Information Gaps The following uncertainties and information gaps were identified as part of the problem formulation:

° Data were not submitted for several algal and aquatic plant species, such as Lemna gibba, Skeletonema costatum, Anabaena flos aquae, and a freshwater diatom ( such as Navicula pelliculosa). Therefore, EFED cannot fully assess the potential adverse effects of napropamide exposure to aquatic plants and algae.

° The extent of photodegradation in surface water is uncertain. While napropamide is persistent in the field, laboratory studies demonstrated rapid ( t 1/ 2 = 4.3 minutes) aqueous photolysis in clear, shallow, well mixed water. In contrast, surface water in the natural environment usually contains suspended solids, significantly reducing sunlight penetration and subsequent napropamide degradation. Therefore, EECs in surface water may be underestimated.

° Currently, EFED cannot assess the chronic risk of napropamide to aquatic organisms because chronic toxicity data was not submitted to the Agency. However, the Agency has determined that chronic toxicity data should be submitted because of the potential environmental persistence of napropamide which may cause chronic exposure to aquatic organisms. Chronic exposure is likely from the compound because the only apparent route of degradation in surface water is by sunlight. Laboratory data show a half life of 26 minutes in clear, shallow, well mixed water. However, persistence is likely to be longer in surface water because of the presence of suspended sediment, shading, deeper water, and cloudy conditions. The halflives in laboratory studies indicate that napropamide is stable to hydrolysis and essentially stable to anaerobic aquatic metabolism and to anaerobic soil metabolism ( T 1/ 2> 51 days).

° No explanation for the difference between the persistence predicted by the laboratory data ( stable in all studies except photodegradation) and the field data has been put forth by the registrant ( photolysis was not considered a major route of dissipation since the product was soil incorporated). The fate of napropamide under field conditions remains an uncertainty.

° No foliar dissipation studies were submitted by the registrant. Therefore, EFED must use the default foliar half life of 35 days to determine foliar residues.

E. Analysis Plan Ecological risk assessment is a process that evaluates the likelihood that adverse ecological effects may occur or are occurring as a result of exposure to one or more stressors ( US EPA, 1992). This risk assessment examines the ecological risk of napropamide use, and attempts to determine at what level napropamide can be used to minimize deleterious effects on the environment. These negative effects include structural and/ or functional characteristics or components of ecosystems. In order to estimate the ecological risk associated with 28 napropamide use, use information, chemical and physical properties, fate/ transport data, and toxicity data were examined for all of the napropamide forms and application methods.

1. Specific Considerations a. Napropamide is applied in both liquid and granular forms. Therefore, the fate properties of both forms must be considered in this assessment b. Granular napropamide must be soil incorporated via irrigation or mechanical incorporation following application.

1. Risk to terrestrial animals resulting from direct exposure to napropamide granules through ingestion in the time period between application and soil incorporation must be considered 2. Incorporation depth and granular dissolution rate must be considered to properly assess exposure to terrestrial animals c. Napropamide applied as a liquid must be soil incorporated either through a rain event or irrigation.

1. Runoff following rain events or irrigation must be considered as an exposure route for aquatic organisms 2. Due to necessary watering in of napropamide, the timing of irrigation or a possible rain event after application must be considered.

d. Laboratory studies demonstrate a short napropamide half life in shallow, clear, well mixed water. However, deep water, suspended solids, and shading may increase the persistence of napropamide in surface water in the field.

e. Napropamide degradates of concern include naphthoxy propionic acid, 1 naphthol, and isomers I and II.

1. Naphthoxy propionic acid and 1 naphthol are only formed in minor amounts and will not be considered in half life calculations.

2. Isomers I and II occur in significant quantities as a result of aqueous photolysis. However, both degradates have short half lives in the aqueous environment. Additionally, these isomers are only formed in significant amounts as a result of aqueous photolysis that occurs in shallow, clear, well mixed water. True environmental conditions will most likely limit the formation of these isomers, and therefore they will no be considered in this assessment. 29 f. Napropamide is applied to numerous crops, and representative modeled surface water crop scenarios will address the geographical distribution of specific crops in the U. S. and the associated weather extremes.

2. Planned Analyses a. Fate and Exposure The environmental fate data indicate that napropamide is fairly persistent in the environment, with photolysis being the only major degradation pathway. Exposure will be examined for both granular and liquid forms, and napropamide levels will be estimated on foliar residue, in surface water, and on the soil surface ( from granular application only). In addition, exposure resulting from spray drift will be assessed. Maximum labeled application rates as well as average application rates will be examined.

1. Initial Considerations Methods used to determine exposure concentrations of a pesticide are dependent on its environmental fate and physicochemical properties, the application method, and the presence of reliable monitoring data that are considered representative of the proposed use sites. Initial factors considered for the exposure assessment are provided in Table 5 below.

Table 5. Factors that may affect the exposure to napropamide Consideration Napropamide specific data Conclusion Monitoring data Monitoring data available from USGS EECs from models will be compared to monitored values Degradation aerobic soil metabolism half life 446 days Napropamide can be persistent in the environment Isomer I and Isomer II Some exposure to these may occur in the aquatic environment from photodegradation in water Bioconcentration BCF values for napropamide are low ( 32 35X) Bioconcentration will not be modeled Application method Ground spray, granules, and chemigation Spray drift and runoff need to be considered in this assessment 2. Exposure in Terrestrial Systems Terrestrial wildlife exposure estimates are typically calculated for birds and mammals, emphasizing a dietary exposure route for uptake of pesticide active ingredients. These organisms are considered surrogates for terrestrial phase amphibians and reptiles. OPP primarily looks at the residues of pesticides on food items and assumes that organisms are exposed to a single 30 pesticide residue in a given exposure scenario for terrestrial organisms. For napropamide spray applications ( DF, EC forms), estimation of pesticide concentrations in wildlife food items focuses on quantifying possible dietary ingestion on residues on vegetative matter and insects. The residue estimates are based on a nomogram that relates food item residues to pesticide application rate ( Fletcher et al., 1994). The first tier nomogram uses the maximum predicted residues. Subsequent refinements may consider mean residues. However, maximum residue concentration is converted to daily oral dose based on fractions of body weight consumed daily as estimated from mammalian allometric relationships in EPA's Wildlife Exposure Factors Handbook. In all screening level assessments, the organisms are assumed to consume 100% of their diet as one food type.

Additionally, terrestrial exposure will be assessed based on the application of granular napropamide. Devrinol ® 10G is applied to numerous field crops, and there is potential exposure to terrestrial organisms via granule ingestion. This exposure is highly dependent on the timing and method of napropamide granule incorporation, which can occur through mechanical incorporation into soil, rainfall, or irrigation techniques. The length of time between application and subsequent incorporation will significantly affect exposure scenarios. Exposure of terrestrial animals ( birds and mammals) will be assessed using the LD 50/ ft2 index ( Felthousen, 1977). This index is based upon the assumption that ecological effects are expected to occur when the concentration of chemical per square foot of habitat is equal or exceeds the LD 50 value determined in laboratory studies.

3. Exposure in Aquatic Systems For aquatic organisms, such as plants, fish, aquatic phase amphibians, and invertebrates, OPP generally uses computer simulation models to estimate exposure to a pesticide active ingredient. These models calculated estimated environmental concentrations ( EECs) in surface water using environmental fate data. Monitoring data, if available, may also be used to determine EECs or to support the model's calculations. The PRZM EXAMS model is initially used to calculate highend estimates of surface water concentrations of pesticides in a generic pond. The User's Manual and PRZM EXAMS Model description available at the following url can be consulted for additional information: www. epa. gov/ oppefed1/ models/ water/ index. htm.

Although there are over 50 registered crop uses for napropamide, EFED only assessed 20 crop use scenarios for surface water exposure because they represent the crops and geographical areas where the highest use rates and exposures are expected. EFED chose to model twenty scenarios: almonds in California ( 2 application rates), citrus in Florida ( 2 application rates), citrus in California ( 2 application rates), berries in Oregon, apples in Pennsylvania ( 2 application rates), apples in North Carolina ( 2 application rates), pecans in Georgia ( 2 application rates), tomatoes in California, peppers in Florida, grapes in California ( 2 application rates), tobacco in North Carolina, turf in Pennsylvania, and cranberries in Michigan. A more detailed description of the models can be found in section III. No EECs are generated in instances where no toxicity was observed at concentrations above the active ingredient's water solubility or at or above the recommended limit concentration for a particular type of study. 31 b. Toxicity Aquatic and terrestrial non target toxicity endpoints ( animals and plants) are provided by the acute and, where appropriate, chronic toxicity data. These toxicity endpoints are compared with the estimated environmental concentrations of napropamide, based on fate properties, chemical type, exposure method, etc. For this assessment, the most sensitive toxicity endpoints for each surrogate taxa ( i. e., freshwater fish and invertebrates, estuarine/ marine fish and invertebrates, aquatic plants, terrestrial plants, birds, and mammals) will be used in Risk Quotient ( RQ) calculation with various exposure values ( see above).

Endangered species analysis will be performed using the EFED LOCATES Endangered Species Database to determine presence of endangered or threatened species in counties where all treated crops are grown. A species profile analysis will be performed to determine whether there are any potential risk scenarios to endangered species in those identified areas.

c. Risk Quotients and Levels of Concern Risk characterization integrates exposure and ecotoxicity data to evaluate the likelihood of adverse effects. For ecological effects, the Agency accomplishes this integration using the quotient risk method. Risk quotients ( RQs) are calculated by dividing exposure estimates by acute and chronic ecotoxicity values.

RQ = EXPOSURE / TOXICITY RQs are then compared to the Office of Pesticide Program's levels of concern ( LOCs) to assess potential risk to non target organisms and the need to consider regulatory action. Calculation of an RQ that exceeds the LOC indicates that a particular pesticide use poses a presumed risk to non target organisms. LOCs currently address the following categories of presumed risk: ° acute  potential for acute risk is high and regulatory action beyond restricted use classification may be warranted ° acute restricted  the potential for acute risk is high, but may be mitigated through restricted use classification ° acute endangered species  threatened and endangered species may be adversely affected ° chronic risk  the potential for chronic risk is high and regulatory action may be warranted. The ecotoxicity values used in the acute and chronic risk quotients are endpoints derived from required laboratory toxicity studies. Ecotoxicity endpoints derived from short term laboratory studies that assess acute effects are:

° LC 50  fish and birds ° LD 50  birds and mammals ° EC 50  aquatic plants and aquatic invertebrates 32 ° EC 25  terrestrial plants The NOAEC ( No Observable Adverse Effect Concentration) is the endpoint used to assess chronic effects. Table 6 gives formulas for calculating RQs and LOCs for various risk presumptions.

Table 6. Formulas for RQ calculations and LOC used for risk assessment of napropamide.

Risk Presumption RQ LOC Birds and Wild Mammals Acute Risk EEC1/ LC50 or LD50/ ft2* or LD50/ day2 0.5 Acute Restricted Use EEC/ LC50 or LD50/ ft2 or LD50/ day ( or LD50< 50 mg/ kg) 0.2 Acute Endangered Species EEC/ LC50 or LD50/ ft2 or LD50/ day 0.1 Chronic Risk EEC/ NOAEC 1.0 Aquatic Animals Acute Risk EEC3/ LC50 or EC50 0.5 Acute Restricted Use EEC/ LC50 or EC50 0.1 Acute Endangered Species EEC/ LC50 or EC50 0.05 Chronic Risk EEC/ NOAEC 1.0 Terrestrial and Plants Inhabiting Semi Aquatic Areas Acute Risk EEC4/ EC25 1.0 Acute Endangered Use EEC/ EC05 or NOAEC 1.0 Aquatic Plants Acute Risk EEC3/ EC50 1.0 Acute Endangered Species EEC/ EC05 or NOAEC 1.0 * mg/ ft2 1Abbreviation for Estimate Environmental Concentration ( ppm) on avian/ mammalian food items 2 mg of toxicant consumed/ day 3 EEC = ppm or ppb in water 4 EEC = lbs ai/ A 33 III. ANALYSIS A. Exposure Characterization 1. Environmental Fate and Transport Characterization a. Fate in the Terrestrial Environment Napropamide is expected to have moderate to low mobility in soil based upon batch equilibrium studies showing K ads values averaging 3.38 for a sandy loam, 5.12 for a loamy sand, 8.63 for a loamy sand, and 14.8 ml/ g for a silt loam soil. The K oc values for adsorption were 1170, 465, 480, and 674 ml/ g, respectively. Adsorption of napropamide increases with increasing clay content, organic carbon content, and pH. Napropamide is not expected to volatilize from dry soil surfaces based upon its vapor pressure of 1.7 x 10 7 mmHg.

Napropamide does photodegrade on soil with a half life of 28 days. The major degradate is carbon dioxide. However, it is important to note that napropamide must be incorporated into the soil in order to be efficacious, therefore, photodegradation on soil is not expected to be a major route of dissipation. Microbial degradation of napropamide in soil under aerobic conditions is very slow with an estimated half life of 446 days. This suggests that the chemical may accumulate in soil with repeated applications. The major volatile degradate detected was CO 2, which increased to 20 % of applied by 360 days ( end of study). The major non volatile detected was naphthoxy propionic acid ( NPA), which increased to 5.8 % by 90 days and declined to 1.5 % of applied by 270 days. Methyl napropamide, 4 nitro napropamide and 1,4 naphthoquinone were also identified in smaller amounts. Under anaerobic conditions, a half life of 51 days was calculated; however, this is considered highly uncertain due to poor material balance at 60 days under anaerobic conditions.

Half lives in terrestrial field dissipation studies were:

17.4 days for Devrinol ® 50 DF, broadcast applied twice as a spray ( 1 month interval) on a bareground plot of sandy loam soil in Mississippi, and 17.0 and 23.9 days for Devrinol ® 10 G, broadcast applied once on a bare ground plot of sandy loam soil in California ( two separate studies).

Napropamide was not detected below the 0 to 6 inch depth, indicating little potential for leaching. The degradates alpha naphthoxy propionic acid ( NPA) and desethyl napropamide were detected in these studies and, like parent napropamide, were not mobile.

The terrestrial field dissipation half lives are much shorter than what would be predicted by the laboratory data. No explanation for the difference between the persistence predicted by the laboratory data ( stable in all studies except photodegradation) and the field data has been put forth by the registrant ( photolysis was not considered a major route of dissipation since the 34 product was soil incorporated). The fate of napropamide under field conditions remains an uncertainty.

b. Fate in the Aquatic Environment In water, napropamide is expected to adsorb to suspended solids and sediment. Napropamide is stable to hydrolysis at pH's 5, 7, and 9, but undergoes rapid direct photolysis in water with a half life of 6.8 minutes. Identified degradates were Isomer One and Isomer Two ( propionamide), which comprised 20 and 27%, respectively, of the initial radioactivity at 10 minutes. The two isomers also degrade rapidly, as the total residue half life in the photodegradation in water study was only 26 minutes. The third degradate identified was a dimer, which comprised 9% of the initial radioactivity. Because of light attenuation, aqueous photolysis will be an important pathway only in shallow clear water bodies. Binding to suspended solids and sediment can also diminish the role photolysis plays in the degradation of napropamide.

Napropamide was stable in an anaerobic flooded soil system, comprising 82 % of the applied at 365 days. Naphthoxy propionic acid ( NPA) was the only identified degradate, and only reached 0.8 % of applied by 271 days. No other degradates were identified, although unidentified radioactivity comprised up to 10.3 % of the applied by 271 days. Bound residues reached a maximum of 13.1 % by 90 days, and declined to 9 % by 365 days. There was no significant volatilization of radioactivity. At the time of application, most of the radioactivity (~ 60 %) was associated with the water phase. By day 365, aqueous residues declined to 24 %, and soil residues increased, demonstrating that napropamide partitions to soil or sediment.

Neither volatilization from water nor bioconcentration are expected to be important fate processes based upon this compound's estimated Henry's Law constant of 8.1 x10 10 atm m3/ mole, and BCF ( 35 in edible tissue), respectively.

2. Monitoring Data The following napropamide monitoring studies were consulted.

Groundwater Napropamide was not detected in 8 well water samples from 5 counties in a well inventory study in California conducted from July 1, 1994 through June 30, 1995. California EPA; Sampling for pesticide residues in California Well water. 1995 update of the Well Inventory Data Base. CA Environ Prot Agency. Dept Pest Reg. EH95 06 ( 1995) peer reviewed Drinking Water Napropamide was not detected in finished drinking water in Florence, Italy, using water from the Arno River, surveyed from 1992 1995. Griffini O et al; Bull Environ Contam Toxicol 59: 202 9 ( 1997)  peer reviewed 35 Surface Water Napropamide was not detected in stormwater runoff within the Sacramento River Basin, California during a storm in January 1994( 1). Napropamide was not detected in Arno River water samples entering the drinking water treatment plant in Florence, Italy, collected from 1992 through 1995( 2). In a study conducted from April 1993 through April 1994, napropamide was detected in water samples from two tributary streams of the South Platte River, a small agricultural area in the Lonetree Creek Basin at a median concentration of < 0.01 ug/ l, but not detected in a small urban area in the Cherry Creek Basin in Colorado( 3). Napropamide was not detected in ten water runoff samples from nine golf courses around Singapore. ( 1) Domagalski J; J Amer Water Res Assoc 32: 953 64 ( 1996) ( 2) Griffini O et al; Bull Environ Contam Toxicol 59: 202 9 ( 1997) ( 3) Kimbrough RA et al; Environ Sci Technol 30: 908 16 ( 1996) ( 4) Wan HB et al; Bull Environ Contam Toxicol 56: 205 9 ( 1996) all peer reviewed.

3. Aquatic Resource Exposure Assessment Napropamide is a preemergent, surface applied herbicide used to control annual grassy and broadleaf weeds on a variety of food and non food crops. Napropamide is sold in emulsifiable liquid, flowable concentrate, dry flowable, and granular formulations, and is applied at the highest concentations to tomatoes, berries, tobacco, grapes, cranberries, peppers, nuts, pome fruits, and citrus crops, as well as turf, trees, and ornamentals.

EFED modeled surface water exposure using the Tier II model PRZM EXAMS for most labeled terrestrial crops, and a modified rice model for cranberry production. Using PRZM EXAMS, EFED modeled a variety of orchard, vineyard, and vegetable crops for which scenarios existed, use data were available, maximum application rates were highest, and geographical distribution of the crops were covered. Scenarios existed for many of the crops either directly or indirectly. For example, scenarios were available for tomatoes, tobacco, pepper, almonds, grapes, citrus, berries, and apples. Based on professional judgement, EFED made the assumption that the California almond scenario represented all fruit and nut crops in California. Since California almonds ( and other orchard crops) have the highest application rates on the label, this approach was protective.

The use data for napropamide from the National Center for Food and Agricultural Policy ( NCFAP) indicate that tomatoes, tobacco, cranberries, peppers, strawberries, and almonds account for 23.5, 20.7, 11.8, 15.3, 8.9, and 4.8 % of applied napropamide in the U. S in 1997 ( http:// www. ncfap. org/ database/ national/ default. asp ). With the exception of strawberries and cranberries, scenarios were available in PRZM EXAMS. Even though strawberries were not modeled, the other scenarios with higher application rates are expected to produce higher aquatic exposure. 36 The modeled surface water scenarios addressed the geographical distribution of specific crops in the U. S. and the associated weather extremes. For example, citrus was modeled both in California and Florida, and apples were modeled in North Carolina and Pennsylvania. Berries ( e. g. blackberries and raspberries) were modeled in Oregon ( Pacific Northwest). Pecans were modeled in Georgia, which created the highest estimates of water concentrations. Generally speaking, higher precipitation values create the need for higher application rates due to increased metabolism, runoff, and leaching.

Napropamide is only effective in preventing seed germination and must be incorporated or wetted in to achieve contact with seed. It is recommended to be applied in late fall prior to germination of winter weeds and in early spring prior to germination of spring/ summer weeds. EFED modeled the runoff into surface water using either the fall or spring application, and for orchard crops, assumed two applications 7 days apart. EFED also modeled using an assumption of no incorporation. These assumptions were made in order to assess upper bound concentrations should there be a runoff event shortly after application and before incorporation. For model inputs, see Table 7.

EFED modeled the cranberry use of napropamide using the Interim Rice Model ( Bradbury, 10/ 29/ 02) modified to represent cranberries. This model predicts the environmental aquatic exposure concentration ( EEC) of napropamide resulting from the application of napropamide to a cranberry field. Although this model has not been officially approved by EFED, its use for assessing aquatic exposure concentration resulting from use on cranberries is Division policy at this time.

The cranberry model assumes that napropamide is applied as a preemergent herbicide to a cranberry field, and that the field is flooded 0 4 hours after application ( See Table 8 for modeling inputs). The model calculates the surface water concentration of napropamide over time in the flooded field. The flood water in cranberry fields is typically held for several days before it is released into the surrounding freshwater or marine/ estuarine habitats.

Inputs for PRZM EXAMS and cranberry modeling are shown in Tables 7 and 8, respectively. The resulting estimated environmental concentrations ( EECs) from PRZM EXAMS are presented in Table 9, and EECs estimated for napropamide use on cranberries are presented in Table 10. 37 Table 7. Inputs for napropamide ecological effects EECs applied using ground equipment to terrestrial crops ( PRZM EXAMS)

MODEL INPUT VARIABLE1 INPUT VALUE COMMENTS Application Rate ( kg/ ha)

CA Almonds 4.48 6.72 Based on BEAD use data all values in lbs ai/ A FL Citrus 4.48 6.72 CA Citrus 4.48 6.72 OR Berry 4.48 OR Apple 4.48 6.72 PA Apple 4.48 6.72 NC Apple 4.48 6.72 PA Turf 4.48 6.72 CA Tomato 4.48 FL Pepper 4.48 CA Grape 4.48 6.72 GA Pecan 4.48 6.72 NC Tobacco 2.24 Maximum No. of Applications: CA almonds, OR, PA, NC apple, CA grape, GA pecan, FL and CA citrus, CA tomato and FL pepper at 6 lb ai/ A rates and OR berry, PA turf, NC tobacco 1 Based on BEAD use data Maximum No. of Applications: CA almonds, OR, PA, NC apple, CA grape, GA pecan, FL and CA citrus, CA tomato and FL pepper at 4 lb ai/ A rates 2 MODEL INPUT VARIABLE1 INPUT VALUE COMMENTS 38 Interval between applications 7 days for all crops with two applications assumed. Application interval is no included on the product labels.

Application Date( s) 3/ 1 FL citrus and pepper, GA pecan and NC tobacco 4/ 1 NC apple and PA turf 11/ 1 CA almonds, citrus, tomato, and grape, OR berry and apple, PA apple Application method Ground per labels Molecular Weight 271 g/ Mol Vapor pressure 1.7 x 10 7 Torr at 25 oC Application Efficiency ( Drinking Water) Per 2/ 8/ 02 Input Parameter Guidance for Ground Applications All non granular uses 0.99 Granular uses ( turf) 1.00 Spray Drift ( Drinking Water) Per 2/ 8/ 02 Input Parameter Guidance All non granular uses 0.01 Granular uses ( turf) 0.00 Kd ( ml/ g) 8 Average of values in MRID 41575302 Aerobic Soil Metabolic Halflife ( days) parent 1338 3X 446 day half life based on extractable residues in MRID 41105901 Incorporation depth ( cm) All uses 0.5 Assumes negligible incorporation Solubility ( mg/ L) 740 74 mg/ L at 20 oC Aerobic Aquatic Metabolic Half life ( days) Kbacw in EXAMS 0 No data Anaerobic Aquatic Metabolism half life ( days) Kbacs in EXAMS 0 Stable MRID 42699701 Photolysis Half life ( days) 0.018 26 minutes/ 1440 minutes/ day r2= 0.87, F= 121, p= 2.1 x 10 9 41575301 Include parent + Isomer I + Isomer II 39 1 Input parameters based on 2/ 8/ 02 Input Parameter Guidance Table 8. Inputs for Cranberry Modeling of Napropamide Use Input Value Comment( s)

Area ( ha) 1 assumed in Interim Rice Model Depth of sediment interaction ( cm) 1 assumed in Interim Rice Model Depth of floodwater ( m) 0.45 assumed in Cranberry modeling Volume = 4.551 * 106 L Soil bulk density ( g/ cm3) 1.3 assumed in Interim Rice Model Mass of soil = 130,000 kg/ ha Organic carbon content (%) 2 assumed in Cranberry modeling Time from application to flooding ( days) 90 assumed in Cranberry modeling Best professional judgement Length of flooding ( days) 5 assumed in Cranberry modeling Best professional judgement Application rate ( kg/ ha) 16.8 Maximum label rate for cranberries Half lives Aerobic soil metabolism 10,704 446 days MRID 41105901 Aerobic aquatic metabolism 21,408 446 Day aerobic soil metabolism * 2 no 162 4 data available Aqueous photolysis 0.433 26 minutes/ 60 minutes/ day r2= 0.87, F= 121, p= 2.1 x 10 9 41575301 Include parent + Isomer I + Isomer II Mobility Koc ( L/ Kg) 1,170 MRID 41575302 Lowest non sand Estimated Kd= 23.4 L/ kg 40 Table 9. Surface water EECs for napropamide ( all crops excluding cranberries)

EECs ( µ g/ L)

Scenario* Peak 4 day 21 day 60 day 90 day Annual Mean Overall Mean CA Almonds ( 4 lbs ai/ A x 2) 7d interval 34.9 23.8 8.8 4.0 2.7 0.8 0.3 CA Almonds ( 6lbs ai/ A x 1) 28.4 20.4 7.6 3.1 2.1 0.7 0.3 FL Citrus ( 4 lbs ai/ A x 2) 7d interval 74.4 49.2 15.9 6.0 5.5 1.4 0.9 FL Citrus ( 6 lbs ai/ A x 1) 54.1 35.3 10.9 4.7 3.9 1.1 0.6 CA Citrus ( 4lbs ai/ A x 2) 7d interval 8.0 5.5 1.9 0.7 0.5 0.2 0.1 CA Citrus ( 6 lbs ai/ A x 1) 6.0 4.1 1.4 0.5 0.4 0.1 0.1 OR Berry ( 4 lbs ai/ A x 1) 15.6 11.8 6.4 2.8 1.8 0.5 0.3 PA Apple ( 4 lbs ai/ A x 2) 7d interval 58.7 42.8 31.6 19.1 13.8 3.9 2.4 PA Apple ( 6 lbs ai/ A x 1) 45.1 30.7 22.6 13.2 9.6 2.8 1.7 NC Apple ( 4 lbs ai/ A x 2) 7d interval 45.0 32.3 12.7 5.0 3.9 1.0 0.6 NC Apple ( 6 lbs ai/ A x 1) 36.7 24.4 9.0 3.9 2.7 0.7 0.4 PA Turf ( 6 lbs ai/ A x 1) 26.3 18.6 7.0 2.5 1.7 0.4 0.2 CA Tomato ( 4 lbs ai/ A x 1) 21.8 16.3 7.7 3.2 2.2 0.7 0.4 FL Pepper ( 4 lbs ai/ A x 1) 64.5 41.6 16.2 9.0 6.1 1.5 0.7 CA Grape ( 4 lbs/ ai/ A x 2) 7d interval 16.6 12.4 5.2 2.1 1.4 0.5 0.3 CA Grape ( 6 lbs ai/ A x 1) 11.8 8.5 3.8 1.5 1.0 0.4 0.2 EECs ( µ g/ L)

Scenario* Peak 4 day 21 day 60 day 90 day Annual Mean Overall Mean 41 GA Pecan ( 4 lbs/ ai/ A x 2) 7d interval 123.3 79.7 26.0 11.0 7.5 1.9 1.0 GA Pecan ( 6 lbs/ ai/ A x 1) 102.6 70.0 24.5 10.2 6.8 1.7 0.8 NC Tobacco ( 2 lbs ai/ A x 1) 9.1 6.4 2.1 1.0 0.7 0.2 0.1 FL citrus ( 6 lbs ai/ A x 1) 2" incorporation 25.6 16.4 5.2 2.3 1.9 0.5 0.3 FL citrus ( 4 lbs ai/ A x 2) 2" incorporation 35.4 22.9 7.7 3.0 2.7 0.7 0.4 GA pecan ( 6 lbs ai/ A x 1) 2" incorporation 48.8 33.2 11.6 4.9 3.3 0.8 0.3 GA pecan ( 4 lbs ai/ A x 2) 2" incorporation 33.8 23.6 10.3 5.1 3.4 0.9 0.5 * All scenarios assume negligible incorporation unless otherwise noted Table 10. EECs in cranberry bog for napropamide used on cranberries at maximum rate ( 15 lbs ai/ A)

Time ( hours) Maximum EEC ( ppb)

0 5.172 1 1.043 2 0.210 3 0.042 4 0.009 4. Terrestrial Organism Exposure Modeling Terrestrial wildlife exposure estimates are typically calculated for birds and mammals, emphasizing a dietary exposure route for uptake of pesticide active ingredients. These exposures are considered as surrogates for terrestrial phase amphibians as well as reptiles. For exposure to terrestrial organisms, such as birds and mammals, pesticide residues on food items are estimated based on the assumption that organisms are exposed to a single pesticide residue in a given exposure scenario. The application method for napropamide is ground application only ( ground 42 spray, chemigation, and granular broadcast).

a. Granular Applications Napropamide is applied to numerous crops in granular form, and despite recommended soil incorporation methods, could pose significant risk to birds and mammals. Birds may be exposed to granular pesticides ingesting granules when foraging for food or grit, and mammalian species may be exposed to granular pesticides by ingesting the granules. They also may be exposed by other routes, such as by walking on exposed granules or drinking water contaminated by granules. The number of lethal doses ( LD 50) that are available within one square foot immediately after application ( LD 50/ ft2) is used as the risk quotient for granular products. Risk quotients are calculated for three separate weight classes of birds: 1000g ( e. g. waterfowl), 80g ( e. g. upland gamebird), and 20g ( e. g. songbird). Risk quotients are also calculated for three separate weight classes of mammals: 1000g, 35g, and 5g. Chronic risk assessments are not currently performed for granular pesticides on terrestrial organisms.

b. Spray Applications and Residues For napropamide spray applications, estimation of pesticide concentrations in wildlife food items focuses on quantifying possible dietary ingestion of residues on vegetative matter and insects. The residue estimates are based on a nomogram that relates food item residues to pesticide application rate. The estimated environmental concentrations ( EECs) are generated from a spreadsheet based model ( ELL FATE) that calculates the decay of a chemical applied to foliar surfaces for single or multiple applications. Further explanation and the results of the model are presented in Appendix C.

The terrestrial exposure assessment is based on the methods of Hoerger and Kenaga ( 1972) as modified by Fletcher et al. ( 1994). Terrestrial EECs for liquid formulations ( Table 9) were derived for representative major crops using current application rates and intervals between applications where applicable.

The EECs on food items may be compared directly with dietary toxicity data or converted to an oral dose, as is the case for small mammals. The screening level risk assessment for napropamide uses upper bound predicted residues as the measure of exposure. The predicted maximum residues of napropamide that may be expected to occur on selected avian or mammalian food items immediately following application are presented in Table 11. For mammals, the residue concentration is converted to daily oral dose based on the fraction of body weight consumed daily as estimated through mammalian allometric relationships. Maximum and average EECs were based on label use data, and typical rates were based on data provided in the USDA National Agriculture Statistics Service, " 2002 Census of Agriculture, Volume 1 Chapter 2: US State Level Data" at http:// www. nass. usda. gov/ census/ census02/ volume1/ us/ index2. htm. 43 Table 11. Estimated environmental concentrations of napropamide on avian and mammalian food items.

Application rate Estimated Environmental Concentration ( EEC) ( ppb)

Short grass Tall grass Broadleaf plants/ small insects Fruits/ pods/ large insects 4 lbs ai/ A x 2 ( 7d interval) 1796 823 1010 112 6 lbs ai/ A x 1 1440 660 810 90 2 lbs ai/ A x 1 480 220 270 30 1 lb ai/ A x 1* 240 110 135 15 * Average napropamide use rate on tobacco 5. Non Target Plant Exposure Modeling EFED used the TERRPLANT model to estimate risk to monocot and dicot terrestrial plants in areas adjacent to the treated field ( sheet runoff), wetland areas ( channelized runoff), and from spray drift.

EFED used a conservative first screen to estimate risk to terrestrial plants. This screening method used the maximum one application rate of the different types of uses ( orchards and vineyards at 6 lbs ai/ A, vineyards at 6 lbs ai/ A, and row crops at 2 and 4 lbs ai/ A), as well as the lowest average napropamide use rate of 1 lb ai/ A ( tobacco). The labels require incorporation by either wetting in or by mechanical means, but EFED modeled the risk to terrestrial plants assuming incorporation to 2 and 4 inches of depth to bracket potential exposure. These depths are specified in labels as being minimum depths to incorporate applied napropamide. Inputs for the TERRPLANT model are listed in Table 12.

Table 12. TERRPLANT modeling inputs for the napropamide plant risk quotient calculations.

Application Rate ( lb a. i./ acre) 6 lbs ai/ A 6 lbs ai/ A 4 lbs ai/ A 4 lbs ai/ A 2 lbs ai/ A 2 lbs ai/ A 1 lbs ai/ A 1 lbs ai/ A Runoff Value ( 0.01, 0.02, or 0.05 if chemical solubility < 10, 10 100, or > 100 ppm, respectively) 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 Minimum Incorporation Depth ( inches) 2 4 2 4 2 4 2 4 Seed Emerg Monocot EC05 or NOAEC ( lb a. i./ acre) 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 Seed Emerg Dicot EC05 or NOAEC ( lb a. i./ acre) 0.0088 0.0088 0.0088 0.0088 0.0088 0.0088 0.0088 0.0088 Veg Vigor Monocot EC05 or NOAEC ( lbs a. i./ acre) 0.33 0.33 0.33 0.33 0.33 0.33 0.33 0.33 Veg Vigor Dicot EC05 or NOAEC ( lb a. i./ acre) 0.01936 0.01936 0.01936 0.01936 0.01936 0.01936 0.01936 0.01936 44 Table 13. Napropamide terrestrial plant EECs for non target vascular plants using labeled spray application rates.

Crop/ scenario Application Adjacent Area Runoff Wetland Area Runoff Spray Drift EEC ( ppb) EEC ( ppb) EEC ( ppb)

6 lbs ai./ acre Ground Unincorp. 0.36 3.06 0.06 Ground Incorp. ( 2 in.) 0.12 0.65 0.06 Ground Incorp. ( 4 in.) 0.09 0.36 0.06 Aerial, Airblast, Spray Chemigation 0.48 2.10 0.30 4 lbs ai./ acre Ground Unincorp. 0.24 2.04 0.04 Ground Incorp. ( 2 in.) 0.08 0.43 0.04 Ground Incorp. ( 4 in.) 0.06 0.24 0.04 Aerial, Airblast, Spray Chemigation 0.3200 1.40 0.20 2 lbs ai./ acre Ground Unincorp 0.12 1.02 0.02 Ground Incorp. ( 2 in.) 0.04 0.22 0.02 Ground Incorp. ( 4 in.) 0.03 0.12 0.02 Aerial, Airblast, Spray Chemigation 0.16 0.70 0.10 1 lbs ai/ acre Ground Unincorp 0.06 0.51 0.01 Ground Incorp. ( 2 in.) 0.02 0.11 0.01 Ground Incorp. ( 4 in.) 0.01 0.06 0.01 Aerial, Airblast, Spray Chemigation 0.08 0.35 0.05 45 Table 14. EECs for granular napropamide formulation applications Crop/ scenario Application Adjacent Area Runoff Wetland Area Runoff EEC ( ppb) EEC ( ppb)

6 lbs ai./ acre Ground Unincorp. 0.30 3.00 Ground Incorp. ( 2 in.) 0.06 0.59 Ground Incorp. ( 4 in.) 0.03 0.30 4 lbs ai./ acre Ground Unincorp 0.20 2.00 Ground Incorp. ( 2 in.) 0.04 0.39 Ground Incorp. ( 4 in.) 0.02 0.20 2 lbs ai./ acre Ground Unincorp 0.10 1.00 Ground Incorp. ( 2 in.) 0.02 0.20 Ground Incorp. ( 4 in.) 0.01 0.10 1 lbs ai/ acre Ground Unicorp. 0.05 0.50 Ground Incorp. ( 2 in.) 0.01 0.01 Ground Incorp. ( 4 in.) 0.005 0.05 B. Ecological Effects Characterization 1. Evaluation of Aquatic and Terrestrial Ecotoxicity Studies In screening level ecological risk assessments, effects characterization describes the types of effects a pesticide can produce in an organism or plant. This characterization is based on registrant submitted studies that describe acute and chronic toxicity information for various aquatic and terrestrial animals and plants. In addition, other sources of information, including reviews of the open literature and the Ecological Incident Information System ( EIIS), are conducted to further refine the characterization of potential ecological effects.

Appendix E summarizes the results of the registrant submitted toxicity studies used to characterize effects for this risk assessment. Toxicity testing reported in this section does not represent all species of birds, mammals, or aquatic organisms. Only a few surrogate species for 46 both freshwater fish and birds are used to represent all freshwater fish ( 2000+) and bird ( 680+) species in the United States. Mammalian acute studies are usually limited to Norway or New Zealand rat or the house mouse. Estuarine/ marine testing is usually limited to a crustacean, a mollusk, and a fish. Also, neither reptiles nor amphibians are tested. The risk assessment assumes that avian and reptilian toxicities are similar. The same assumption is used for fish and amphibians.

Napropamide Toxicity Categories Napropamide is classified as practically non toxic to avian species on both an acute oral and subacute dietary basis; is practically non toxic to mammalian species on an acute oral basis; is moderately toxic to freshwater fish; is slightly toxic to freshwater invertebrates; is slightly toxic to estuarine/ marine fish; and is moderately toxic to estuarine/ marine invertebrates.

Tables 15  17 summarize the most sensitive ecological toxicity endpoints for aquatic organisms, terrestrial organisms, and aquatic and terrestrial plants, respectively. Discussions of the effects of napropamide on aquatic and terrestrial taxonomic groups are presented below.

Table 15. Summary of Napropamide Acute and Chronic Aquatic Toxicity Data Species Acute Toxicity Chronic Toxicity LC50 or EC50 ( mg ai/ L) MRID LOAEC/ LOAEC* ( mg/ L) MRID Rainbow Trout Oncorhynchys mykiss 6.4 115313 NO DATA NA Water Flea Daphnia magna 14.3 88064 57805 NO DATA NA Sheepshead Minnow Cyprinodon variegatus 14.0 416102 06 NO DATA NA Eastern Oyster Crassostrea virginica 1.4 416671 01 NO DATA NA Mysid Shrimp Americamysis bahia 4.2 416102 07 NO DATA NA * No chronic toxicity data required for aquatic organisms. Acute toxicity tests demonstrated acute toxicity > 1mg/ L ( 40 CFR 72 4) 47 Table 16. Summary of Napropamide Acute and Chronic Terrestrial Organism Toxicity Data Species Acute Toxicity Chronic Toxicity Oral Toxicity LD50 ( mg ai/ kg) MRID Subacute Dietary LC50 ( mg ai/ kg) MRID NOAEC ( mg ai/ kg) MRID Affected Endpoint s Mallard Duck Anas platyrhynchos > 4640 2296521 > 5620 258393 113820 10002 79548 and 79555 NA2 Laboratory Rat Rattus norvegicus > 5000 2306021 NA NA 303 40362902 growth & reproducti on 1 Accession number 2 The effect demonstrated on body weight was deemed not related to the toxicant effects of napropamide. This is because the effect was only demonstrated in the 3000 ppm males during the last two weeks of the study. The differences observed were slight, and appeared to be related to a slightly lighter initial body weight of the males in this group. Furthermore, there were no significant differences in mean body weight change between the control group and the 3000 ppm treatment group at any time during the course of the study. Therefore, EFED conclusion is that a LOAEC was not established in the study. Therefore, this NOEAC will not be used to calculate an RQ. 3mg ai/ kg diet Table 17. Summary of napropamide most sensitive plant toxicity endpoints.

Species Toxicity EC25 / EC05 NOAEC ( ppm) Affected Endpoint ( MRID)

Green alga Selenastrum capricornutum ( TGAI) 3.4 ( ppm) NA cell density ( 416102 10)

Terrestrial plants ( see Appendix E for a list of species) ( TEP) 2.1 0.095 ( lbs ai/ A) < 0.017 Percent emergence and dry weight 2. Use of Probit Slope Response Relationship The Agency uses the probit dose response relationship as a tool for providing additional information on the listed animal species acute levels of concern ( LOC). The acute listed species LOCs of 0.1 and 0.05 are used for terrestrial and aquatic animals, respectively. As part of the risk characterization, an interpretation of acute LOCs for listed species is discussed. This interpretation is presented in terms of the chance of an individual event ( i. e., mortality or immobilization) should exposure at the estimated environmental concentration actually occur for a species with sensitivity to napropamide on par with the acute toxicity endpoint selected for RQ calculation. To accomplish this interpretation, the Agency uses the slope of the dose response relationship available from the toxicity study used to establish the acute toxicity measurement 48 endpoints for each taxonomic group. The individual effects probability associated with the LOCs is based on the mean estimate of the slope and an assumption of a probit dose response relationship. In addition to a single effects probability estimate based on the mean, upper and lower estimates of the effects probability are also provided to account for variance in the slope. The upper and lower bounds of the effects probability are based on available information on the 95% confidence interval of the slope. A statement regarding the confidence in the applicability of the assumed probit dose response relationship for predicting individual event probabilities is also included. Studies with good probit fit characteristics ( i. e., statistically appropriate for the data set) are associated with a high degree of confidence. Conversely, a low degree of confidence is associated with data from studies that do not statistically support a probit dose response relationship. In addition, confidence in the data set may be reduced by high variance in the slope ( i. e., large 95% confidence intervals), despite good probit fit characteristics.

Individual effect probabilities are calculated based on an Excel spreadsheet tool IECV1.1 ( Individual Effect Chance Model Version 1.1) developed by Ed Odenkirchen of the U. S. EPA, OPP, Environmental Fate and Effects Division ( June 22, 2004). The model allows for such calculations by entering the mean slope estimate ( and the 95% confidence bounds of that estimate) as the slope parameter for the spreadsheet. In addition, the LOC ( 0.1 for terrestrial animals and 0.05 for aquatic animals) is entered as the desired threshold.

3. Incident Data Review A review of the EIIS database for ecological incidents involving napropamide was completed. There were two reported incidents. The first incident involved adverse effects on fish ( incident # 1000799 04). Napropamide and chlorpyrifos residues were identified in soil in the vicinity of a fish pond. The report deemed chlorpyrifos as a more probable reason for the incident than napropamide. This is because chlorpyrifos is very highly toxic to fish. Napropamide is only slightly to moderately toxic to fish. The second incident report involved damage to seven acres of planted douglas fir trees. The report determined that napropamide was unlikely the cause of the damage because it had only been applied once to the area. Additionally, oryzalin, which was used in the vicinity of the tree damage, was determined to be the likely candidate because its label specifically warned that this chemical could damage Douglas fir trees.

IV. RISK CHARACTERIZATION Risk characterization is the integration of exposure and effects characterization to determine the ecological risk from the use of napropamide and the likelihood of effects on aquatic life, wildlife, and plants based on varying pesticide use scenarios. The risk characterization provides an estimation and a description of the risk; articulates risk assessment assumptions, limitations, and uncertainties; synthesizes an overall conclusion; and provides the risk managers with information to make regulatory decisions. 49 A. Risk Estimation  Integration of Exposure and Effects Data Results of the exposure and toxicity effects data are used to evaluate the likelihood of adverse ecological effects on non target species. For the assessment of napropamide risks, the risk quotient ( RQ) method is used to compare exposure and measured toxicity values. Estimated environmental concentrations ( EECs) are divided by acute and chronic toxicity values. The RQs are compared to the Agency's levels of concern ( LOCs). These LOCs are the Agency's interpretive policy and are used to analyze potential risk to non target organisms and assess the need to consider regulatory action. These criteria are used to indicate when a pesticide's directed label use has the potential to cause adverse effects on non target organisms.

1. Non target Aquatic Animals and Plants Surface water concentrations resulting from napropamide application to selected crops were predicted with the Tier II models PRZ M EXAMS. Twenty scenarios were simulated: almonds in California ( 2 application rates), citrus in Florida ( 2 application rates), citrus in California ( 2 application rates), berries in Oregon, apples in Pennsylvania ( 2 application rates), apples in North Carolina ( 2 application rates), pecans in Georgia ( 2 application rates), tomatoes in California, peppers in Florida, grapes in California ( 2 application rates), tobacco in North Carolina, turf in Pennsylvania, and cranberries in Michigan.

Aquatic animals: Peak EECs were compared to acute toxicity endpoints for napropamide to derive acute RQs for fish and invertebrates ( freshwater and estuarine/ marine). No chronic studies were required for aquatic animals; therefore, no chronic RQ values could be calculated.

None of the acute fish ( freshwater and estuarine/ marine) or freshwater invertebrate RQs calculated for napropamide exceeded any LOC values ( endangered species LOC = 0.05). RQ values for napropamide are summarized in Table 18.

Although no RQs calculated for freshwater invertebrates exceeded the endangered species LOC, there remains an uncertainty as to whether current freshwater invertebrate toxicity tests are protective of freshwater mollusk species. Therefore, the Agency uses the estuarine/ marine mollusk RQ values as a surrogate for freshwater mollusks. There are potential exceedances for freshwater mollusks exposed to napropamide resulting from application to Florida citrus and Georgia pecans based on this surrogate data.

Endangered species RQ values were exceeded for estuarine/ marine invertebrates ( mollusks) exposed to napropamide in runoff following application to Florida citrus at an application rate of 4 lbs ai/ A applied twice a year with a 7 day interval between applications ( RQ = 0.053). The endangered species LOC was also exceeded for estuarine/ marine invertebrates ( mollusks) exposed to runoff following application to Georgia pecans at both application rates of 4 lbs ai/ A x 2 and 6 lbs ai/ A x 1 ( RQ = 0.088 and 0.073). There were no exceedances for estuarine/ marine crustaceans for any modeled scenarios. 50 Table 18. Acute risk quotients ( RQ) for freshwater and estuarine/ marine animals Crop scenario Application Peak EEC ( ppb) Acute RQ values Freshwater fish1 Estuarine/ Marin e fish 2 Freshwater Invertebrates 3 Estuarine/ Marine Invertebrates oyster 4 shrimp 5 CA Almond 4 lbs ai/ A x 2 34.9 0.005 0.002 0.002 0.025 0.008 6 lbs ai/ A x 1 28.4 0.004 0.002 0.002 0.020 0.007 FL Citrus 4 lbs ai/ A x 2 74.4 0.012 0.005 0.005 0.053 0.018 6 lbs ai/ A x 1 54.1 0.008 0.004 0.004 0.039 0.013 FL Citrus 2" incorp. 4 lbs ai/ A x 2 35.4 0.006 0.003 0.002 0.03 0.008 6 lbs ai/ A x 1 25.6 0.004 0.002 0.002 0.02 0.006 CA Citrus 4 lbs ai/ A x 2 8.0 0.001 0.001 0.001 0.006 0.002 6 lbs ai/ A x 1 6.0 0.001 0.000 0.000 0.004 0.001 OR Berry 4 lbs ai/ A x 1 15.6 0.002 0.001 0.001 0.011 0.004 PA Apple 4 lbs ai/ A x 2 58.7 0.009 0.004 0.004 0.042 0.014 6 lbs ai/ A x 1 45.1 0.007 0.003 0.003 0.032 0.011 NC Apple 4 lbs ai/ A x 2 45.0 0.007 0.003 0.003 0.032 0.011 6 lbs ai/ A x 1 36.7 0.006 0.003 0.003 0.026 0.009 GA Pecan 4 lbs ai/ A x 2 123.3 0.019 0.009 0.009 0.088 0.029 6 lbs ai/ A x 1 102.6 0.016 0.007 0.007 0.073 0.024 GA Pecan 2" incorp. 4 lbs ai/ A x 2 33.8 0.005 0.002 0.002 0.024 0.008 6 lbs ai/ A x 1 48.8 0.008 0.003 0.003 0.035 0.012 CA Tomato 4 lbs ai/ A x 1 21.8 0.003 0.002 0.002 0.016 0.005 FL Pepper 4 lbs ai/ A x 1 64.5 0.010 0.005 0.005 0.046 0.015 CA Grape 4 lbs ai/ A x 2 16.6 0.003 0.001 0.001 0.012 0.004 6 lbs ai/ A x 1 11.8 0.002 0.001 0.001 0.008 0.003 NC Tobacco 2 lbs ai/ A x 1 9.1 0.001 0.001 0.001 0.007 0.002 PA Turf 6 lbs ai/ A x 1 26.3 0.004 0.002 0.002 0.019 0.006 Exceedances are indicated in bold 1Rainbow Trout LC50 = 6400 ppb 2Sheepshead Minnow LC50 = 14,000 ppb 3Daphnia EC50 = 14,300 ppb 4 Eastern Oyster EC50 = 1400 ppb 5 Mysid Shrimp EC50 = 4200 ppb 51 Table 19. RQ calculations based on EECs in cranberry bog for napropamide used on cranberries at maximum rate ( 15 lbs. ai/ A) and most sensitive aquatic organism toxicity endpoints Time ( hours) Maximum ( ug/ L) RQ based on Freshwater fish LC50 of 6.4 ppm RQ based on Freshwater invertebrate LC50 of 14.3 ppm RQ based on Marine/ Estuarine fish LC50 of 14 ppm RQ based on Marine/ Estuarine invertebrate LC50 of 1.4 ppm RQ based on Plant EC50 of 3.4 ppm 0 5.172 0.79 * 0.36 * 0.37 * 3.64 * 1.5 *

1 1.043 0.17 * 0.07 ** 0.07 ** 0.71 * Below LOC of 1 2 0.210 Below LOC of 0.05 Below LOC of 0.05 Below LOC of 0.05 0.15 Below LOC of 1 3 0.042 Below LOC of 0.05 Below LOC of 0.05 Below LOC of 0.05 Below LOC of 0.05 Below LOC of 1 4 0.009 Below LOC of 0.05 Below LOC of 0.05 Below LOC of 0.05 Below LOC of 0.05 Below LOC of 1 RQ = EEC/ LC50 or EEC/ EC50 Exceedances are indicated in bold * Exceed Agency level of concern for risk to aquatic organisms including endangered species. ** Exceed Agency level of concern for risk to endangered species aquatic organisms. Note: Table 18 demonstrates that the concentration of napropamide degrades below the Agency level of concern for risk to aquatic organisms within 3 hrs. Therefore, flood water released into the surrounding aquatic habits is not expected to pose a significant risk to aquatic organisms in these habitats.

Aquatic plants: Peak EECs were compared to the acute EC 50 toxicity endpoint for green alga to derive acute non endangered species RQs.

There are no LOC exceedances for aquatic plants based on numerous napropamide application modeling scenarios.

Table 20. Acute risk quotients ( RQ) for aquatic plants Crop scenario Application Peak EEC ( ppb) Acute RQ value Green algae( EC50 = 3400 ppb)

CA Almond 4 lbs ai/ A x 2 34.9 0.010 6 lbs ai/ A x 1 28.4 0.008 FL Citrus 4 lbs ai/ A x 2 74.4 0.022 6 lbs ai/ A x 1 54.1 0.016 CA Citrus 4 lbs ai/ A x 2 8.0 0.002 6 lbs ai/ A x 1 6.0 0.002 OR Berry 4 lbs ai/ A x 1 15.6 0.005 52 PA Apple 4 lbs ai/ A x 2 58.7 0.017 6 lbs ai/ A x 1 45.1 0.013 NC Apple 4 lbs ai/ A x 2 45.0 0.013 6 lbs ai/ A x 1 36.7 0.011 GA Pecan 4 lbs ai/ A x 2 123.3 0.036 6 lbs ai/ A x 1 102.6 0.030 CA Tomato 4 lbs ai/ A x 1 21.8 0.006 FL Pepper 4 lbs ai/ A x 1 64.5 0.019 CA Grape 4 lbs ai/ A x 2 16.6 0.005 6 lbs ai/ A x 1 11.8 0.003 NC Tobacco 2 lbs ai/ A x 1 9.1 0.003 PA Turf 6 lbs ai/ A x 1 26.3 0.008 RQ = EEC/ EC50 2. Non target Terrestrial Animals The EEC values for terrestrial exposure were derived from the Kenaga nomograph, as modified by Fletcher et al., ( 1994), which is based on a large set of actual field residue data. Risk quotients are calculated using the most sensitive LC 50 and NOAEC for birds, LD 50 for mammals ( based on laboratory rat studies), and appropriate EEC values.

Birds: No acute RQs were calculated for birds exposed to napropamide via spray or granular application because the core acute toxicity studies demonstrated that the LC50 and LD50 were greater the greatest dose tested ( highest dose tested in the acute dietary test was 7200 ppm; highest dose tested in the acute oral test was 4640 mg/ kg ). These results classify napropamide as practically nontoxic to birds. Therefore the maximum avian environmental dietary exposure concentration of napropamide ( 1796 ppb) ( See ELL FATE Model Appendix C) is not expected to cause significant acute toxicity to birds.

No chronic RQ values were calculated for birds because decreased body weights measured in the core chronic toxicity study were deemed unrelated to napropamide exposure ( See Appendix E, Table 2).

Mammals: No acute RQs were calculated for mammals exposed to napropamide via spray or granular application because the core acute toxicity studies demonstrated that the LD 50 was greater the greatest dose tested ( highest dose tested in the acute dietary test was 5000 mg/ kg). These results classify napropamide as practically nontoxic to mammals. Therefore the maximum 53 mammalian environmental dietary exposure concentration of napropamide ( See ELL FATE Model Appendix C) is not expected to cause significant acute toxicity to mammals.

Chronic mammalian RQ values exceeded the LOC of 1.0 on all food types and at all napropamide maximum application rates. Additionally, chronic mammalian RQ values exceeded the LOC on grasses, broadleaf plants, and small insects at the lowest average napropamide use rate of 1 lb ai/ A ( tobacco). RQ values ranged from 1.00 to 59.86. Chronic mammalian RQ values are summarized in Table 21.

Table 21. Mammalian chronic RQ values for napropamide Application rate Mammalian Chronic Risk Quotients1 Short grass Tall grass Broadleaf plants/ small insects Fruits/ pods/ large insects 4 lbs ai/ A x 2 ( 7d interval) 59.86 27.43 33.67 3.74 6 lbs ai/ A x 1 48.00 22.00 27.00 3.00 2 lbs ai/ A x 1 16.00 7.33 9.00 1.00 1 lb ai/ A x 1 8.00 3.67 4.50 0.50 1Rat NOAEC = 30 mg/ kg/ diet 2Lowest average use rate ( tobacco) exceedances indicated in bold 3. Non target Terrestrial and Semi Aquatic Plants EFED used a conservative first screen to estimate risk to terrestrial plants. This screening method used the maximum one application rate of the different types of uses ( orchards and vineyards at 6 lbs ai/ A, vineyards at 6 lbs ai/ A, and row crops at 2 and 4 lbs ai./ A), as well as the lowest average use rate of 1 lb ai/ A for tobacco. The labels require incorporation by either wetting in or by mechanical means. EFED modeled the risk to terrestrial plants assuming incorporation to 2 and 4 inches of depth to bracket potential exposure. These depths are specified in labels as being minimum depths to incorporate applied napropamide.

EFED used the TERRPLANT model to estimate risk to monocot and dicot terrestrial plants in areas adjacent to the treated field ( sheet runoff), wetland areas ( channelized runoff), and from spray drift. For the highest application rates ( 2, 4, and 6 lbs. ai/ A), potential risk was predicted to non endangered and endangered terrestrial monocot and dicot plants living in both adjacent areas and wetlands. Also, spray drift risk to dicot plants was predicted from these application rates. ( Table 22).

The lowest average application rate of 1 lbs ai/ A pose a risk to primarily endangered species inhabiting living in both adjacent areas and wetlands. The only nonendangered plants risk is to species inhabiting adjacent wetlands. This risk is only posed by the chemigation application method and granular uses. 54 Table 22. Terrestrial Plant Risk Quotients ( RQs)

App rate Form App method Plant Type Adjacent Area Runoff RQ values Wetland Area Runoff RQ values Spray Drift RQ values non end. 1 end. 2 nonend 3 end 4 non end. 5 end. 6 6 lbs ai/ A liquid Ground Unincorp. Monocot 3.27 12.00 27.82 102.00 0.08 0.18 Dicot 2.27 40.91 19.32 347.73 0.10 3.10 Ground Incorp. ( 2 in.) Monocot 1.08 3.97 5.91 21.69 0.08 0.18 Dicot 0.75 13.53 4.11 73.93 0.10 3.10 Ground Incorp. ( 4 in.) Monocot 0.81 2.98 3.23 11.84 0.08 0.18 Dicot 0.57 10.17 2.24 40.37 0.10 3.10 Aerial, Airblast, Spray Chemigation Monocot 4.36 16.0 19.09 70.0 0.38 0.91 Dicot 3.03 54.55 13.26 238.64 0.49 15.50 granular Ground Incorp. ( 2 in.) Monocot 0.54 1.97 5.37 19.69 NA NA Dicot 0.37 6.71 3.73 67.11 NA NA Ground Incorp. ( 4 in.) Monocot 0.27 0.98 2.68 9.84 NA NA Dicot 0.19 3.36 1.86 33.55 NA NA Ground Unincorp. Monocot 2.73 10.00 27.27 100.00 NA NA Dicot 1.89 34.09 18.94 340.91 NA NA 4 lbs ai/ A liquid Ground Unincorp. Monocot 2.18 8.00 18.55 68.00 0.05 0.12 Dicot 1.52 27.27 12.88 231.82 0.07 2.07 Ground Incorp. ( 4 in.) Monocot 0.54 1.99 2.15 7.90 0.05 0.12 Dicot 0.38 6.78 1.50 26.91 0.07 2.07 Aerial, Airblast, Spray Chemigation Monocot 2.91 10.67 12.73 46.67 0.25 0.61 Dicot 2.02 36.36 8.84 159.09 0.33 10.33 granular Ground Unincorp. Monocot 1.82 6.67 18.18 66.67 NA NA Dicot 1.26 22.73 12.63 227.27 NA NA Ground Incorp. ( 2 in.) Monocot 0.36 1.31 3.58 13.12 NA NA Dicot 0.25 4.47 2.49 44.74 NA NA App rate Form App method Plant Type Adjacent Area Runoff RQ values Wetland Area Runoff RQ values Spray Drift RQ values non end. 1 end. 2 nonend 3 end 4 non end. 5 end. 6 55 Ground Incorp. ( 4 in.) Monocot 0.18 0.66 1.79 6.56 NA NA Dicot 0.12 2.24 1.24 22.37 NA NA 2 lbs ai/ A liquid Ground Unicorp. Monocot 1.09 4.00 9.27 34.00 0.03 0.06 Dicot 0.76 13.64 6.44 115.91 0.03 1.03 Ground Incorp. ( 2 in.) Monocot 0.36 1.32 1.97 7.23 0.03 0.06 Dicot 0.25 4.51 1.37 24.64 0.03 1.03 Ground Incorp. ( 4 in.) Monocot 0.27 0.99 1.08 3.95 0.03 0.06 Dicot 0.19 3.39 0.75 13.46 0.03 1.03 Aerial, Airblast, Spray Chemigation Monocot 1.45 5.33 6.36 23.33 0.13 0.30 Dicot 1.01 18.18 4.42 79.55 0.16 5.17 granular Ground Incorp. ( 2 in.) Monocot 0.18 0.66 1.79 6.56 NA NA Dicot 0.12 2.24 1.24 22.37 NA NA Ground Incorp. ( 4 in.) Monocot 0.09 0.33 0.89 3.28 NA NA Dicot 0.06 1.12 0.62 11.18 NA NA Ground Unincorp. Monocot 0.91 3.33 9.09 33.33 NA NA Dicot 0.63 11.36 6.31 113.64 NA NA App rate Form App method Plant Type Adjacent Area Runoff RQ values Wetland Area Runoff RQ values Spray Drift RQ values non end. 1 end. 2 nonend 3 end 4 non end. 5 end. 6 56 1 lb ai/ A liquid Ground Unincorp Monocot 0.55 2.00 4.64 17.00 0.01 0.03 Dicot 0.38 6.82 3.22 57.95 0.02 0.052 Ground Incorp. ( 2 in.) Monocot 0.18 0.66 0.99 3.61 0.01 0.03 Dicot 0.13 2.25 0.68 12.32 0.02 0.52 Ground Incorp. ( 4 in.) Monocot 0.14 0.50 0.54 1.97 0.01 0.03 Dicot 0.09 1.70 0.37 6.73 0.02 0.52 Aerial, Airblast, Spray Chemigation Monocot 0.73 2.67 3.18 11.67 0.06 0.15 Dicot 0.51 9.09 2.10 39.77 0.08 2.58 granular Ground Incorp. ( 2 in.) Monocot 0.09 0.33 0.89 3.28 NA NA Dicot 0.06 1.12 0.62 11.18 NA NA Ground Incorp. ( 4 in.) Monocot 0.04 0.16 0.45 1.64 NA NA Dicot 0.03 0.56 0.31 5.59 NA NA Ground Unincorp. Monocot 0.45 1.67 4.55 16.67 NA NA Dicot 0.32 5.68 3.16 56.82 NA NA exceedances are indicated in bold 1RQ = EEC / Seedling emergence EC25 2RQ = EEC / Seedling emergence EC05 or NOAEC 3RQ = EEC / Seedling emergence EC25 4RQ = EEC / Seedling emergence EC05 or NOAEC 5RQ = Drift EEC / Vegetative Vigor EC25 6RQ = DriftEEC / Vegetative Vigor EC05 or NOAEC 57 B. Risk Description  Interpretation of Direct Effects 1. Risk to Aquatic Animals and Plants Summary of major conclusions ° No LOCs were exceeded for freshwater fish, freshwater invertebrates, estuarine/ marine fish, and estuarine/ marine crustaceans at all napropamide application levels and in all evaluated scenarios.

° Although no RQs calculated for freshwater invertebrates exceeded the endangered species LOC, there remains an uncertainty as to whether current freshwater invertebrate toxicity tests are protective of freshwater mollusk species. Therefore, the Agency uses the estuarine/ marine mollusk RQ values as a surrogate for freshwater mollusks. There are potential exceedances for freshwater mollusks exposed to napropamide resulting from application to Florida citrus and Georgia pecans based on this surrogate data.

° Currently, EFED cannot assess the chronic risk of napropamide to aquatic organisms because chronic toxicity data was not submitted to the Agency. However, the Agency has determined that chronic toxicity data should be submitted because of the potential environmental persistence of napropamide which may cause chronic exposure to aquatic organisms. Chronic exposure is likely from the compound because the only apparent route of degradation in surface water is by sunlight. Laboratory data show a half life of 6.8 minutes for parent napropamide and 26 minutes for parent + Isomers I and II in clear, shallow, well mixed water. However, persistence is likely to be longer in surface water because of the presence of suspended sediment, shading, deeper water, and cloudy conditions. The half lives in laboratory studies indicate that napropamide is stable to hydrolysis and essentially stable to anaerobic aquatic metabolism and to anaerobic soil metabolism ( T 1/ 2> 51 days).

° EFED recognizes that there are no federally listed endangered estuarine/ marine invertebrates. However, " endangered" species acute LOCs were exceeded for estuarine/ marine mollusks for napropamide application to Florida citrus at a rate of 4lbs ai/ A twice a year ( 7 day interval between applications) and Georgia pecans at both application rates ( 4 lbs ai/ A x 2 and 6 lbs ai/ A x 1).

° The modeling of napropamide used in cranberry production indicates that risk to aquatic organisms is not likely to be significant. This is primarily because the maximum napropamide concentration ( 5172 ug/ L) in cranberry field flood water rapidly degrades ( within 3 hrs) to concentrations below the Agency's level of concern for acute risk to aquatic organisms ( Table 5). Thus, because flood water contaminated with napropamide is typically held in a cranberry field for several 58 days, the napropamide concentration released into the surrounding aquatic environment is not expected to be significant.

° No LOCs were exceeded for aquatic plants based on green alga toxicity data. Data were not submitted for several algal and aquatic plant species, such as Lemna gibba, Skeletonema costatum, Anabaena flos aquae, and a freshwater diatom ( such as Navicula pelliculosa). Therefore, EFED cannot fully assess the potential adverse effects of napropamide exposure to aquatic plants and algae.

With the exception of the aforementioned estuarine/ marine mollusk scenarios, napropamide use does not pose a calculated risk to aquatic animals.

2. Risk to Terrestrial Organisms Summary of major conclusions ° Acute RQ values for birds for both spray and granular napropamide applications were not calculated because the core acute toxicity studies demonstrated that the LC 50 and LD 50 were greater the greatest dose tested ( highest dose tested in the acute dietary test was 7200 ppm; highest dose tested in the acute oral test was 4640 mg/ kg ). These results classify napropamide as practically nontoxic to birds. Therefore the maximum avian environmental dietary exposure concentration of napropamide ( 1796 ppb) ( See ELL FATE Model Appendix C) is not expected to cause significant acute toxicity to birds.

° Chronic RQ values for birds were not calculated because decreased body weights measured in the core chronic toxicity study were deemed unrelated to napropamide exposure. The effect demonstrated on body weight was deemed not related to the toxicant effects of napropamide. This is because the effects was only demonstrated in the 3000 ppm males during the last two weeks of the study. The differences observed were slight, and appeared to be related to a slightly lighter initial body weight of the males in this group. Furthermore, there were no significant differences in mean body weight change between the control group and the 3000 ppm treatment group at any time during the course of the study. Therefore, EFED conclusion is that a LOAEC was not established in the study. Therefore, this NOEAC will not be used to calculate an RQ.

° Acute RQ values for mammals for both spray and granular napropamide applications were not calculated because the core acute toxicity studies demonstrated that the LD 50 was greater the greatest dose tested ( highest dose tested in the acute dietary test was 5000 mg/ kg). These results classify napropamide as practically nontoxic to mammals. Therefore the maximum mammalian environmental dietary exposure concentration of napropamide ( See 59 ELL FATE Model Appendix C) is not expected to cause significant acute toxicity to mammals.

° Chronic risk to mammals ( including threatened and endangered mammals) is possible from maximum labeled application rates of napropamide on all crops, as well as from the lowest average application rate of 1 lb ai/ A ( tobacco).

° There is potential risk to non endangered and endangered terrestrial plants living in both adjacent areas and wetlands at maximum and average use rates.