UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON D. C., 20460 OFFICE OF PREVENTION, PESTICIDES AND TOXIC SUBSTANCES October 25, 2005 PC Code: 109702 DP Barcode: D293412 MEMORANDUM Subject: Revised EFED Risk Assessment for the Reregistration Eligibility Decision ( RED) on Cypermethrin After 30 Day " Error Only" Comment Period To: Veronique LaCapra, Chemical Review Manager Yan Donovan, Chemical Review Manager Margaret Rice, Branch Chief Reregistration Branch II Special Review and Reregistration Division ( 7505C)

From: Miachel Rexrode, Ph. D., Fishery Biologist José Luis Meléndez, Chemist Environmental Risk Branch V Environmental Fate and Effects Division ( 7507C)

Through: Mah Shamim, Ph. D., Chief Environmental Risk Branch V Environmental Fate and Effects Division ( 7507C)

This memorandum summarizes the Environmental Fate and Effects Division's ( EFED) screening level Environmental Risk Assessment for the Reregistration Eligibility Decision ( RED) of Cypermethrin. This compound is a synthetic pyrethroid that is used as a broad spectrum insecticide for agricultural and non agricultural uses, as well as commercial/ industrial/ institutional/ non food areas. EFED has concluded that the available data on cypermethrin shows that the compound has very low mobility, moderate persistence and binds readily to soils and surfaces. An evaluation of environmental risk to aquatic and terrestrial organisms is included in the Executive Summary and the Risk Characterization chapters.

Outstanding Data Requirements and Data Gaps Environmental Fate:

The environmental fate database is substantially complete and consists mostly of acceptable studies. The database is sufficient to conduct a Tier 1 Risk Assessment of Terrestrial Food uses. At this time, no additional data are required. ii Ecological Effects:

Although the ecological database is fairly complete there are a few endpoints that must be addressed.

72 4 ( b) Life Cycle Aquatic Invertebrate, Freshwater: Adequate data were not submitted so the Agency extrapolated a NOAEC by using the acute to chronic ratio method. However, to confirm risk assessment assumptions data is needed.

The following sediment tests are needed by the Agency in order to better understand the potential acute and long term exposure risk of cypermethrin to benthic organisms. However, currently the Pyrethroid Working Group ( PWG) is completing these studies.

850.1735: Acute Sediment ( freshwater)  Test organism: Hyalella azteca and Chironomus tentans.  Duration: 10 days, endpoint is survival.

EPA/ 600/ R 99/ 064: Chronic Freshwater Sediment Testing  65 day test on Chironomus tentans  Survival.  Growth rate.  Reproduction (# eggs/ female, time to oviposition, proportion of females ovipositing, % hatch).

EPA/ 600/ R01/ 020: Chronic Estuarine/ Marine Sediment Testing  28 day test on Leptocheirus plumulosus,  Percentage of neonates that survive as adults.  Growth rate.  Reproduction (# eggs/ female, etc.).  Behavior.

71 4 ( a) Avian Reproduction Quail: Reproductive studies were tested at a maximum of 50 ppm while the criteria suggest that maximum testing be completed at 1,000 ppm. Although there were no treatment related effects at the exposure levels listed, including 50 ppm, expected exposure in cotton can be 66 ppm ( short grass).

Uncertainties:

Environmental Fate and Exposure There is a possible uncertainty related to the exposure levels estimated to the lettuce scenario. In the coastal southern California, lettuce is a year round crop so the application of cypermethrin may vary. According to the label, the maximum application rate is 0.6 lb a. i./ A/ season. The exposure scenarios modeled in this assessment assumed only one season per year. iii and a special run was performed with two applications per year. However, the exposure may be considerably higher if more than two seasons occur.

There is uncertainty with respect to the level of mitigation that a buffer zone of 150 ft plus a vegetative strip of 10 ft can provide. The estimation of spray drift was obtained from AgDRIFT ® ; however, there is no way to know how well the buffer zone will protect the bodies of water from runoff. In certain cases, the level of runoff is the most important factor, rather than the level of spray drift. Furthermore, for the California lettuce scenario, there is uncertainty in the level of spray drift because data from weather stations in proximity to the use areas indicate that the wind speed is generally at or above 10 mph during the application period ( late Summer). This is an assumption made in the Tier I calculation of AgDRIFT ® . It is noted, however, that the label instructions recommend applications at wind speeds of 3 10 mph ( but always at < 15 mph). The level of spray drift may have been underestimated only for the California lettuce scenario ( 3.9 % vs. 4.1 %).

Cypermethrin is a mixture of four diastereoisomers, each of which is present as a pair of enantiomers, resulting in eight isomers. Different ratios of the eight isomers have resulted in four different cypermethrin products ( alpha, beta, theta, and zeta cypermethrin) all of which have similar environmental fate properties, but slightly different toxicities depending upon the isomeric mixture of compounds. The cis: tran ratio of cypermethrin isomers was found to vary in different toxicity tests ( e. g., 48.8: 42.7, 55: 45, 53.6: 46.4, 54: 46). However the cis: trans ratio is close to a 50: 50 ratio suggesting that toxicity profiles should be accurate. An enhanced zeta cypermethrin is not under review with this cypermethrin risk assessment. This refined cypermethrin compound has an equivalent toxicity profile to the cypermethrin enantiomeric mixture but is more efficacious ( half the application rate of the enantiomeric mixture).

This aquatic exposure assessment represents a range of water concentrations expected from aerial applications, following the label instructions. The results of a simple spray drift and buffer zones analysis, with only one representative PRZM scenario, indicated that the concentrations resulting from actual applications of cypermethrin could be significantly higher depending upon actual application practices. Using stringent measures, will result in smaller EECs, while using other application parameters could result in higher EECs.

Ecological Effects:

There are uncertainties associated with cypermethrin exposure in the environment, especially regarding possible impact to aquatic ecosystems. Since cypermethrin is toxic to invertebrates ( aquatic insects, bivalves, shrimp, etc.) there is a question of sustaining functional diversity, genetic diversity, as well as population abundance in an aquatic system that has been exposed to cypermethrin drift and/ or runoff. Proponents for cypermethrin use argue that invertebrates are resilient and effected populations will reintroduce themselves in time. EFED feels that the degree of reintroduction of species that are keystone to an ecosystem is unknown and the impact of diminished invertebrate diversity on ecosystem integrity has not been adequately evaluated. The argument that aquatic systems usually sustain macroinvertebrate functional redundancy has also not been adequately substantiated and presents uncertainty as to the iv magnitude of pyrethroid toxic effects to various functional groups and the ultimate effect on aquatic ecosystem structure.

The Agency has not received sediment toxicity studies for cypermethrin that represent equilibrated spiked sediments. Therefore in order to complete the RED the risk assessors have relied upon the equilibrium partitioning approach for estimates of potential cypermethrin exposure to macroinvertebrates from the sediment/ pore water. The key limitation of the equilibrium partitioning approach that concerns the Agency is the magnitude of variation in toxicant uptake caused by biological factors such as feeding pathways ( Landrum, et. al., 1994; McGroddy et al., 1996; Bott and Standley 2000), organism life stage ( Leppanen and Kukkonen 1998), and population level effects versus individual responses ( Hallam et al., 1990). Because criteria are supposed to protect biota, inherent variations in biological uptake need to be considered.

EFED Label Recommendations i. Manufacturing Use Product:

This pesticide is toxic to fish and aquatic invertebrates. Do not discharge effluent containing this product into lakes, streams, ponds, estuaries, oceans, or other waters unless in accordance with the requirements of a National Pollutant Discharge Elimination System ( NPDES) permit and the permitting authority has been notified in writing prior to discharge. For guidance, contact your State Water Board or Regional Office of the EPA.

ii. End Use Product:

This pesticide is extremely toxic to fish and aquatic invertebrates. Do not apply directly to water, to areas where surface water is present or to intertidal areas below the mean high water mark. Do not apply when weather conditions favor drift from treated areas. Drift and runoff from treated areas may be hazardous to aquatic organisms in neighboring areas. Do not contaminate water when disposing of equipment washwaters or rinsate.

This product is highly toxic to bees exposed to direct treatment or residues on blooming crops or weeds. Do not apply this product or allow it to drift to blooming crops if bees are visiting the treatment area.

iii. Label statements for spray drift management:

The Agency has been working with the Spray Drift Task Force, EPA Regional Offices and State Lead Agencies for pesticide regulation and other parties to develop the best spray drift management practices. The Agency is proposing interim mitigation measures for aerial applications that should be placed on product labels/ labeling. The Agency has completed its evaluation of the new database submitted by the Spray Drift Task Force, a membership of U. S. pesticide registrants, and is developing a policy on how to appropriately apply the data and the AgDRIFT computer model to its risk assessments for pesticides applied by air, orchard airblast and ground hydraulic methods. After the policy is in place, the Agency may impose further v refinements in spray drift management practices to reduce off target drift and risks associated with aerial as well as other application types where appropriate.

Table I 1. Cypermethrin Table of Environmental Fate Data Requirements Guideline # Data Requirement MRID # Study Classification Are Additional Data Needed for Risk Assessment?

161 1 Hydrolysis 42620501 Acceptable no 161 2 Photodegradation in Water 42395701 Supplemental no 161 3 Photodegradation on Soil 42129001 Supplemental no 161 4 Photodegradation in Air No Data Waived no 162 1 Aerobic Soil Metabolism 42156601 Acceptable no 162 2 Anaerobic Soil Metabolism 42156602 Acceptable no 162 3 Anaerobic Aquatic Metabolism 44876105 Acceptable no 162 4 Aerobic Aquatic Metabolism 45920801 Acceptable no 163 1 Leaching Adsorption/ Desorption 42129003, 42129002 Acceptable no 163 2 Laboratory Volatility No Data Waived no 163 3 Field Volatility No Data Waived no 164 1 Terrestrial Field Dissipation 42459601 Acceptable no 164 2 Aquatic Field Dissipation 44876107 Supplemental no aquatic uses 164 3 Forestry Dissipation No Data N/ A no 165 4 Accumulation in Fish 42868203 Acceptable no vi Table I 2. Ecological Effects Data Requirements for Cypermethrin Guideline # Data Requirement Formulation MRID or Acc. Number Study Classification Are Additional Data Needed for Ecological Risk Assessment?

71 1 Avian Acute Oral Toxicity Technical Technical Technical 241598 44546024 90070 Acceptable Acceptable Invalid No 71 2 Avian Subacute Dietary Toxicity Technical Technical Technical Technical 90071 90072 44546025 44546026 Acceptable Acceptable Acceptable Acceptable No 71 4 Avian Reproduction Toxicity Technical Technical 90073 90074 Supplemental Supplemental Yes 72 1 Freshwater Fish LC50 Technical Technical Technical Technical Technical Technical Technical Technical Technical Technical Technical Formulation Formulation Formulation Metabolite ( 3 phenoxy benzoic acid) 62792 65812 44546028 44546030 41968209 41968208 44546027 44546029 241598 88948 41068004 65813 88947 89036 89037 89038 Acceptable Acceptable Acceptable Acceptable Acceptable Acceptable Acceptable Acceptable Acceptable/ Supplemental Invalid Supplemental Acceptable Supplemental Supplemental Acceptable Acceptable No Table I 2. Ecological Effects Data Requirements for Cypermethrin Guideline # Data Requirement Formulation MRID or Acc. Number Study Classification Are Additional Data Needed for Ecological Risk Assessment?

vii 72 2 Freshwater Invertebrate Acute LC50 Technical Technical Technical Technical Technical Technical Technical Technical Technical Technical Formulation Formulation Formulation Metabolite ( 3 phenoxy benzoic acid) 62793 44546032 44546031 42444601 44074401 44074402 44074406 41968210 43293501 44423501 62793 89040 88949 42444601 152739 89046 Acceptable Acceptable Acceptable Acceptable/ Supplemental Supplemental Supplemental Supplemental Invalid Supplemental Supplemental Supplemental Supplemental Supplemental Acceptable Acceptable Supplemental No 72 3( a) Estuarine/ Marine Fish LC50 Technical Technical Technical Technical Technical Technical 44546033 41968212 41968211 44546034 90075 41068003 Acceptable Acceptable Acceptable Acceptable Supplemental Supplemental No 72 3( b) Estuarine/ Marine Invertebrate ( Mollusk ) Technical 42444601 89049 Acceptable Acceptable No 72 3( c) Estuarine/ Marine Invertebrate ( Mysid) Technical Technical Technical Technical Unknown 42444601 44561210 42444601 44561209 41968213 Acceptable Acceptable Acceptable Acceptable Invalid No 72 3 ( d) Estuarine/ Marine Crustacean Technical Technical 89045 41068003 Supplemental Supplemental No Table I 2. Ecological Effects Data Requirements for Cypermethrin Guideline # Data Requirement Formulation MRID or Acc. Number Study Classification Are Additional Data Needed for Ecological Risk Assessment?

viii 72 4 ( a) Freshwater Fish Early Life Stage Technical 89039 Acceptable No 72 4 Aquatic Invertebrate Life Cycle ( Freshwater) Technical Unknown 428983 01 89047 Invalid Invalid Yes 72 4 Aquatic Invertebrate Life Cycle ( Marine) Chronic Toxicity Technical Technical Technical Technical 42444601 42725301 44546035 42898301 Acceptable Acceptable Acceptable Invalid No 72 5 Freshwater Fish Full Life Cycle No Data Submitted NA NA NA 72 7 Aquatic Field Study Formulation Formulation 155770 152737 Supplemental Supplemental No 141 1 Acute Honeybee Contact Toxicity Test Technical Technical Formulation 260647 44544208 260647 Acceptable Acceptable Acceptable No 141 2 Residues on Foliage Honeybee Toxicity Test Formulation 40274001 Acceptable No 141 4 Subacute Honeybee Feeding Toxicity Test Technical Technical Formulation 260647 44544208 260647 Acceptable Acceptable Acceptable No ix Preliminary Environmental Fate and Effects Assessment Science Chapter for the Reregistration Elegibility Decision of CYPERMETHRIN Prepared by:

Miachel Rexrode, Ph. D., Fishery Biologist Michael D. Hoffmann, Biologist José L. Meléndez, Chemist United States Environmental Protection Agency Office of Pesticide Programs Environmental Fate and Effects Division Environmental Risk Branch V Ariel Rios Building 1200 Pennsylvania Ave., NW Mail Code 7507C Washington, DC 20460 Reviewed by: Faruque Khan, Ph. D., Environmental Scientist Jean Holmes, RAPL Ronald Parker, Ph. D., Environmental Engineer Mah T. Shamim, Ph. D., Chief Environmental Risk Branch V  x Table of Contents I. Executive Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 A. Nature of Chemical Stressor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 B. Potential Risks to Non Target Organisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 C. Conclusions  Exposure Characterization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 D. Conclusions  Effects Characterization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 E. Uncertainties and Data Gaps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 II. Problem Formulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 A. Stressor Source and Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 1. Source and Intensity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2. Physical/ Chemical/ Fate and Transport Properties . . . . . . . . . . . . . . . . . . 8 3. Pesticide Type, Class, and Mode of Action . . . . . . . . . . . . . . . . . . . . . . . 9 4. Overview of Pesticide Usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 B. Receptors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 1. Aquatic Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2. Terrestrial Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 3. Ecosystems at Risk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 C. Assessment Endpoints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 D. Conceptual Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 1. Risk Hypotheses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 2. Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 E. Analysis Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 1. Preliminary Identification of Data Gaps and Methods . . . . . . . . . . . . . . 18 2. Measures to Evaluate Risk Hypotheses and Conceptual Model . . . . . . . 19 a. Measures of Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 b. Measures of Effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 c. Measures of Ecosystem and Receptor Characteristics . . . . . . . . 20 III. Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 A. Use Characterization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 B. Exposure Characterization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 1. Environmental Fate and Transport Characterization . . . . . . . . . . . . . . . 29 a. Summary of Empirical Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 b. Degradation and Metabolism . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 c. Transport and Mobility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 d. Bioaccumulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 e. Field Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 2. Measures of Aquatic Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 a. Aquatic Exposure Modeling . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 b. Aquatic Exposure Monitoring and Field Data . . . . . . . . . . . . . . 49 3. Measures of Terrestrial Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 a. Terrestrial Exposure Modeling . . . . . . . . . . . . . . . . . . . . . . . . . 50  xib Residue Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 C. Ecological Effects Characterization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 1. Aquatic Effects Characterization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 a. Aquatic Animals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 ( 1). Acute Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 ( 2). Chronic Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 ( 3). Sublethal Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 ( 4). Field Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 b. Plants Inhabiting Aquatic Areas . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 2. Terrestrial Effects Characterization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 a. Terrestrial Animals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 ( 1). Acute Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 ( 2). Chronic Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 ( 3). Sublethal Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 ( 4). Field Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 b. Terrestrial Plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 IV. Risk Characterization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 A. Risk Estimation  Integration of Exposure and Effects Data . . . . . . . . . . . . . . . . . 68 1. Non Target Aquatic Animals and Plants . . . . . . . . . . . . . . . . . . . . . . . . . . 69 a. Water Column Exposure  Acute and Chronic Risk . . . . . . . . . . 69 b. Sediment Exposure  Acute and Chronic Risk . . . . . . . . . . . . . . 71 c. Use of Buffer Zones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 d. Aquatic Plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 2. Non Target Terrestrial Animals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 a. Acute Risk to Mammals and Birds . . . . . . . . . . . . . . . . . . . . . . . 74 b. Chronic Risk to Mammals and Birds . . . . . . . . . . . . . . . . . . . . . 77 c. Risk to Terrestrial Invertebrates . . . . . . . . . . . . . . . . . . . . . . . . 80 3. Non target Plants Inhabiting Terrestrial and Semi Aquatic Areas . . . . . . . 80 B. Risk Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 1. Risks to Aquatic Organisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 a. Estimating Risk to Aquatic Systems . . . . . . . . . . . . . . . . . . . . . . 82 b. Aquatic Animals ( Water Column Exposure) . . . . . . . . . . . . . . . . 83 c. Aquatic Animals ( Sediment Exposure) . . . . . . . . . . . . . . . . . . . . 84 d. Aquatic Plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 e. Other Special Considerations for Evaluating Aquatic Risk . . . . . 85 f. Summary of Risk to Aquatic Systems . . . . . . . . . . . . . . . . . . . . . 86 2. Risks to Terrestrial Organisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 a. Terrestrial Animals ( Mammals and Birds) . . . . . . . . . . . . . . . . . 88 b. Non Target Terrestrial Insects . . . . . . . . . . . . . . . . . . . . . . . . . . 88 c. Terrestrial Plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 3. Review of Incident Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 a. Incidents Involving Aquatic Organisms . . . . . . . . . . . . . . . . . . . 90 b. Incidents Involving Terrestrial Organisms . . . . . . . . . . . . . . . . . . 90 4. Endocrine Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90  xii 5. Federally Threatened and Endangered ( Listed) Species Concerns . . . . . . . 91 a. Action Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 b. Taxonomic Groups Potentially at Risk . . . . . . . . . . . . . . . . . . . . 92 ( 1) Discussion of Risk Quotients . . . . . . . . . . . . . . . . . . . . . . 92 c. Critical Habitat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 C. Description of Assumptions, Limitations, Uncertainties, Strengths and Data Gaps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 1. Assumptions, Limitations, Uncertainties, Strengths and Data Gaps Related to Exposure For All Taxa . . . . . . . . . . . . . . . . . . . . 96 2. Assumptions, Limitations, Uncertainties, Strengths and Data Gaps Related to Exposure For Aquatic Species . . . . . . . . . . . . . . 97 3. Assumptions, Limitations, Uncertainties, Strengths and Data Gaps Related to Exposure For Terrestrial Species . . . . . . . . . . . . . . . . . . . . . 97 4. Assumptions, Limitations, Uncertainties, Strengths and Data Gaps Related to Effects Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 5. Assumptions, Limitations, Uncertainties, Strengths and Data Gaps Related to the Acute and Chronic . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 ACKNOWLEDGMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 V. Literature Cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 VI. Appendices A. Environmental Fate Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A1 B. Aquatic Exposure Model Output ( AGDISP Linked to PRZM/ EXAMS) . . . . . B1 C. TERRPLANT Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C1 D. T REX Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D1 E. Ecological Effects Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E1 F. The Risk Quotient Method and Levels of Concern . . . . . . . . . . . . . . . . . . . . . . F1 G. Detailed Risk Quotients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G1 H. Summary of Endangered/ Threatened Species . . . . . . . . . . . . . . . . . . . . . . . . . H1 I. Data Requirement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I1 J. Incident Reports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . J1 K. ECOTOX Literature Searches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . K1 L. Use Characterization Maps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . L1 M. Equilibrium Partitioning and Concentration in the Sediment . . . . . . . . . . . . . . M1 N. Environmental Fate and Monitoring Bibliography and Ecotoxicology Bibliography N1 O. Spray Drift/ Buffer Zone Analysis Raw Data . . . . . . . . . . . . . . . . . . . . . . . . . . O1 List of Tables Table 1. Physical and Chemical Properties of Cypermethrin . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Table 2. Taxonomic Groups and Test Species Evaluated for Ecological Effects in Screening Level Risk Assessments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10  xiii Table 3. Summary of Assessment and Measures of Effect for Cypermethrin ( TGAI). . . . . . . . 12 Table 4. Usage Rates for Cypermethrin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Table 5. Physical, Chemical and Environmental Fate Properties of Cypermethrin . . . . . . . . . . 28 Table 6a. Use Patterns of Cypermethrin for Cotton, Pecans and Lettuce . . . . . . . . . . . . . . . . . 35 Table 6b. PRZM/ EXAMS Inputs for Cypermethrin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Table 7. Cypermethrin Surface Water, Pore Water and Sediment EECs ( ppb or : g/ L) Obtained From PRZM/ EXAMS Cotton Crop Use . . . . . . . . . . . . . . . . . . . . . . 39 Table 8. Cypermethrin Surface Water, Pore Water and Sediment EECs ( ppb or : g/ L) Obtained From PRZM/ EXAMS Georgia Pecans Crop Use . . . . . . . . . . . . . . . . 40 Table 9a. Cypermethrin Surface Water, Pore Water and Sediment EECs ( ppb or : g/ L) Obtained From PRZM/ EXAMS California Lettuce Crop Use . . . . . . . . . . . . . 41 Table 9b. Cypermethrin Surface Water, Pore Water and Sediment EECs ( ppb or : g/ L) Obtained From PRZM/ EXAMS California Lettuce Two Crops per Year . . . . . 41 Table 10. Input Parameters Used in T REX v1.12 to Determine Terrestrial EECs for Cypermethrin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 Table 11. Peak Terrestrial EECs Estimated for Cypermethrin Using Kenaga Values . . . . . . . . 50 Table 12. Cypermethrin Toxicity Reference Values ( TRVs) (: g of active ingredient/ L) for Aquatic Organisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 Table 13. Cypermethrin Toxicity Reference Values ( TRVs) for Terrestrial Organisms . . . . . . . 65 Table 14. Acute RQs for Freshwater Fish, Freshwater Invertebrates, Estuarine/ Marine Fish and Estuarine/ Marine Invertebrates Exposed to Cypermethrin . . . . . . . . . . 70 Table 15. Chronic RQs for Freshwater Fish, Freshwater Invertebrates, Estuarine/ Marine Fish and Estuarine/ Marine Invertebrates Exposed to Cypermethrin . . . . . . . . . . 71 Table 16. Acute and Chronic RQs for Benthic Organisms Exposed to Cypermethrin . . . . . . . . 72 Table 17. Dose based Acute RQs and Dietary based Acute RQs for Birds Exposed to Cypermethrin Based on Upper Bound Residues as Calculated by TREX . . . . 76 Table 18. Dose based Acute RQs for Mammals Exposed to Cypermethrin Based on Upper Bound Residues as Calculated by TREX . . . . . . . . . . . . . . . . . . . . . . 77 Table 19. Dietary based Chronic RQs for Birds Exposed to Cypermethrin Based on Upper Bound Residues as Calculated by T REX . . . . . . . . . . . . . . . . . . . . . 78 Table 20. Dose based Chronic RQs and Dietary based Chronic RQs for Mammals Based on Upper Bound Residues as Calculated by T REX . . . . . . . . . . . . . . . . 79 Table 21. Number of Listed Species by Taxa per State for the Following Crops: Cotton, Pecans, Lettuce, Bulb Vegetables ( Onions, Garlic), Brassica, ( Brussel Sprouts, Broccoli, Cauliflower, Cabbage), Leafy Brassica, ( Collards, Kale, Mustard Greens, Spinach, Canola) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 Supplementary Table A. Spray Drift Scenarios . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 Supplementary Table B. Levels of Spray Drift Predicted by AgDrift ® for Buffer Zones from 0 to 200 ft with Low, Typical, and High End Drift Scenarios . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 Supplementary Table C. PRZM/ EXAMS Inputs for Cypermethrin Runs With NC Cotton . . . . 44 Supplementary Table D. Surface Water Concentrations, EECs ( ppb) for Ecological Risk  xiv Asssessment, Based on North Carolina Cotton ( Special Runs) . . . . . . . . . . . . . . . . . . . . . . . . . 46 Supplementary Table E. Surface Water Concentrations, EECs ( ppb) for Ecological Risk Asssessment, Based on North Carolina Cotton ( Buffer Zone Analysis) . . . . . . . . . . . . . . . . . . 46 Supplementary Table F. Pore Water Concentrations, EECs ( ppb) for Ecological Risk Assessment, Based on North Carolina Cotton . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 Supplementary Table G. Percent Reduction of the NC cotton Peak EEC for the Buffer Zones of 150 and 200 ft, to Observe if Substantial Additional Reduction is Obtained by Increasing the Buffer Zone Imposed by the Registrant's Label . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 Supplementary Table H. Acute Risk Quotients for Estuarine/ Marine Invertebrates Using Different Buffer Zones and Levels of Spray Drift. Peak Surface Water Concentrations, EECs ( ppb) for Ecological Risk Assessment, Based on NC cotton ( Surrogate Scenario for Estuarine/ Marine Environments). Use of Most Sensitive Species, Estuarine/ Marine Invertebrates ( Mysid shrimp) LC 50 = 0.00475 ppb ( special runs). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 Supplementary Table I. Acute Risk Quotients for Estuarine/ Marine Invertebrates Using Different Buffer Zones and Levels of Spray Drift. Peak Surface Water Concentrations, EECs ( ppb) for Ecological Risk Assessment, Based on NC cotton ( Surrogate Scenario for Estuarine/ Marine Environments). Use of Most Sensitive Species, Estuarine/ Marine Invertebrate ( Mysid Shrimp) LC 50 = 0.00475 ppb ( Buffer Zone Runs) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 List of Figures Figure 1 General Conceptual Model for a Screening Level Ecological Risk Assessment for Cypermethrin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Figure L 2 1997 Cypermethrin Application on All Crops. . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Figure L 3 1997 Cypermethrin Application on Cotton. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Figure L 4 1997 Cypermethrin Application on Lettuce. . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Figure L 5 1997 Cypermethrin Application on Pecans. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Figure 2 Cypermethrin and its Degradation Products. . . . . . . . . . . . . . . . . . . . . . . . . . . 33  1 I. Executive Summary A. Nature of Chemical Stressor Cypermethrin ( CAS number 52315 07 8) is a pyrethroid pesticide prepared from the esterification of 3 phenoxybenzaldehyde and 3( 2,2 dichlorovinyl) 2,2 dimethylcyclopropane carboxylic acid. It consists of a mixture of four diastereoisomers, each of which is present as a pair of enantiomers, resulting in eight geometrical and optical isomers. Cleavage at the ester moiety of cypermethrin results in two primary degradation products, 3( 2,2 dichloroethenyl) 2,2 dimethylcyclopropane carboxylic acid ( DCVA) and 3 phenoxybenzaldehyde, which degrades further to 3 phenoxybenzoic acid ( 3 PBA). Cypermethrin is used to control many pests, including those of cotton, fruit, and vegetable crops. It also has several non agricultural uses, such as for crack, crevice, and spot treatment to control insect pests in stores, warehouses, industrial buildings, houses, apartment buildings, greenhouses, laboratories, and on ships, railcars, buses, trucks, and aircraft. It may also be used in non food areas in schools, nursing homes, hospitals, restaurants, hotels, in food processing plants, and as a barrier treatment insect repellent for horses. Cypermethrin is usually formulated as an emulsifiable concentrate or wettable powder, and is usually applied by ground or aerial application as a foliar spray. Like all pyrethroids, cypermethrin is efficacious to insects by acting as a neural toxin that can result in muscle spasms, paralysis and death.

B. Potential Risks to Non Target Organisms Although difficult to model and quantify, urban uses of pyrethroids have the potential to impact aquatic systems. However, at this time the Agency is evaluating appropriate models that might be useful for future assessments of urban pesticide uses. Therefore, the Agency's Tier I screening level ( deterministic) risk assessment is focused on maximum proposed uses of cypermethrin on crops that are representative of all registered agricultural use patterns. The current assessment suggests that levels of cypermethrin residues in the environment, when compared with the most sensitive environmental endpoints, are likely to result in acute and chronic adverse effects to non target aquatic organisms ( both freshwater and estuarine/ marine). In addition, there is a potential for acute and chronic adverse effects to non target mammals, although the potential for risk for this group of organisms is more dependent upon specific crop exposure scenarios. To assess risks to aquatic organisms, six crop scenarios were evaluated with the Tier II aquatic model PRZM/ EXAMS: CA cotton, MS cotton, NC cotton, TX cotton, GA pecans, and CA lettuce ( head). To assess risks to terrestrial organisms, four crop uses were evaluated with the Tier I terrestrial model T REX: cotton, lettuce, pecans, and canola. Although the Agency does not calculate risk quotients for honey bees, a qualitative assessment is presented after reviewing toxicity test on beneficial insects. This assessment shows that cypermethrin has the potential for acute risk to bees and beneficial insects. Risks to aquatic and terrestrial plants were not assessed because data are not available and the Agency does not expect that the cypermethrin mode of action to be a phytotoxic concern. In addition, the Agency has not reviewed any incident data pertaining to phytotoxicity from cypermethrin or other pyrethroid exposure. Risk to aquatic invertebrates from exposure to cypermethrin residues in the sediment was estimated by using the equilibrium partitioning model that predicts pore water concentrations, based upon  2 hydrophobicity and concentrations of the chemical normalized to organic carbon ( OC) in the sediment ( De Toro et al. 1991). Sediment toxicity was predicted by comparing pore water concentrations with dissolved concentrations that caused toxicity in bioassays. Specific risks to non target organisms are summarized below.

Risk to Aquatic Organisms:

° Acute risks to aquatic organisms ( freshwater and estuarine/ marine fish and invertebrates, that include those organisms living in the water column and the benthos) are significant with RQs exceeding LOCs for acute risk, restricted use, and endangered species for all crop scenarios. The greatest acute risk ( i. e., highest RQ values exceeding the acute LOCs) among aquatic receptors evaluated is for estuarine/ marine invertebrates. Results of available field studies support these conclusions, demonstrating that adverse effects on aquatic ecosystems occurred following application of cypermethrin under conditions of recommended use.

° Chronic risks to aquatic organisms exceed the LOC for freshwater and estuarine/ marine invertebrates and fish. In addition, there are chronic exceedances for organisms living in or on the sediment for both freshwater and estuarine organisms.

Risk to Terrestrial Organisms:

° Acute risks to mammals are expected for listed species in the 15 g size range. The exposure route of concern is short grass for cypermethrin use on cotton. No other acute LOC criteria are exceeded. However, chronic risk criteria are exceeded for all modeled crop uses for several feeding strategies that include, mammals feeding on short grass, tall grass and broadleaf plants/ small insects.

° Cypermethrin exposure does not appear to present acute risk to avian species ( LOC criteria were not exceeded). Avian risks associated with chronic exposure can not be fully assessed at this time. Reproductive studies were tested at a maximum of 50 ppm while the criteria suggest that maximum testing be completed at 1000 ppm. Although there were no treatment related effects at the exposure levels listed, including 50 ppm, expected exposure in cotton can be 66 ppm ( short grass). However, LOC criteria are not exceeded for the other modeled crop uses.

° Cypermethrin exposure can present acute toxic risk to beneficial non target insects, such as honey bees, and to earthworms. This risk concern is extended to listed insects also.

Risk from Degradates:

° Results of acute toxicity studies in freshwater fish and invertebrates indicate that the cypermethrin degradate 3 phenoxy benzoic acid is much less toxic than the  3 parent compound. No information is available on the toxicity of other cypermethrin degradates. However, based on the assumption that cleavage of the ester bond in the parent compound results in biologically inactive degradates, these compounds should not present a significant risk to non target organisms.

C. Conclusions  Exposure Characterization The environmental fate and effects database is extensive and sufficient to support terrestrial food uses. Based on mostly valid studies, the behavior of cypermethrin in the environment can be predicted with reasonable certainty. The terrestrial field dissipation studies appear to corroborate the predictions of the laboratory studies. It appears that cypermethrin degradation is mainly the product of metabolic activity. Aerobic and anaerobic soil metabolism were found to be about 60 and 52 63 days, respectively. In contrast, the rates for aerobic and anaerobic aquatic metabolism were 9 10 and 14 17 days, respectively. All abiotic processes appeared to represent relatively insignificant dissipation mechanisms for cypermethrin. Cypermethrin appears to be stable to hydrolysis ( except in alkaline media at pH 9, t ½ .2 days) and in the presence of light ( photolysis in water was 36 days and on soil, 100 days, dark control corrected). The basic mechanism of degradation of cypermethrin is cleavage at the ester moiety, which results in two primary degradation products, 3( 2,2 dichloroethenyl) 2,2 dimethylcyclopropane carboxylic acid ( trans DCVA, max. 79% in pH 9 solution, and 34% in anaerobic aquatic metabolism study) and 3 phenoxybenzaldehyde, which is further oxidized to 3 phenoxybenzoic acid ( 3 PBA, max. 35% in aqueous photolysis study). Another degradation product was cyperamide. This product keeps a similar structure to that of the parent; however, it was observed only in one laboratory study, the soil photolysis study, at a maximum of 13.3%, which approaches the limit that EFED generally considers of concern ( 10% of the applied).

Cypermethrin is not likely to leach to ground water, as shown by an adsorption/ desorption batch equilibrium study ( Koc = 20,800  328,500 L/ Kg) and an aged leaching study. Cypermethrin shows a relatively low potential for volatilization from soil and water ( vapor pressure 2.5x10 9 mm Hg and Henry's Law constant 3.4x10 7 atm m3/ mol), relatively low solubility in water ( 0.0040 mg/ L, high soil/ water partitioning).

There are four field studies, two terrestrial and two aquatic. The terrestrial field dissipation studies were conducted in CA and LA ( bare soils), using the EC formulation. The calculated half lives of cypermethrin were 12.2 and 3.2 days, respectively. The degradate 3 phenoxybenzoic acid was detected through 3 days after the last application, while trans DCVA was detected only twice in the LA study only. There was no substantial leaching in either study. The supplemental aquatic field dissipation studies, conducted in rice plots in CA and LA, appeared to indicate a much higher persistence, with reported half lives of 181 and 126 days, respectively. Results of this study disagree with the laboratory studies, which yielded shorter halflives both under aerobic and anaerobic conditions; however, the reported half lives in the field study, included the sediment only.

Due to the relatively low mobility of cypermethrin, it is expected to reach adjacent bodies of water via spray drift or through runoff events accompanied by erosion, when it is applied to the  4 field. Once there, cypermethrin may be expected to remain adsorbed to suspended solids in the water column, or partition with the sediment phase, where it could persist ( the aerobic and anaerobic aquatic metabolism studies for cypermethrin indicate that the chemical is not persistent; however, field studies conducted on rice, with zeta cypermethrin, show high persistence in aquatic environments). If cypermethrin is applied repeatedly, it is possible that the chemical can accumulate in the sediment in ever larger amounts, with slow biodegradation. Generally cypermethrin is not expected to leach substantially into groundwaters.

Cypermethrin shows a moderate potential to bioaccumulate in fish, with maximum BCF of 468 for whole fish in a 28 day study. Depuration appeared to be moderately slow, with near 10 15% of the initial residues remaining after 21 days.

For more details about the environmental fate characteristics of this chemical and its degradation products, please, refer to section III. B. 1. Environmental Fate and Transport Characteristics.

Estimated environmental concentrations ( EECs) for cypermethrin calculated using the Tier II PRZM/ EXAMS models and employing maximum application rates, indicate that cypermethrin preferentially partitions to the sediment compartment in model water bodies. Three crop usage scenarios, which constitute over 90% of cypermethrin's total crop usage, were considered: cotton, lettuce and pecans. These model results suggest that the highest EECs are observed for cotton crops in North Carolina and Mississippi.

In order to evaluate the extent to which the buffer zone imposed by the registrant in its label ( for standard aerial applications) might mitigate the level of spray drift and how important it is a transport process to bodies of water close to treated areas, EFED conducted a brief buffer zone/ spray drift analysis of the NC cotton scenario as a representative one for the cotton scenarios. First, EFED ran PRZM/ EXAMS to compare the standard run with spray drift of 5% ( no buffer zone) vs a similar run with drift= 0%; comparison of the results indicated that the percent of the peak EEC that was attributable to spray drift was 9.6% for this scenario. It has a relatively small component of drift. Furthermore, various additional runs were performed, simulating aerial runs with buffer zones of up to 200 ft with three levels of drift ( high, low and typical). Acute risk quotient ( RQ) values were calculated for the most sensitive estuarine/ marine invertebrate species ( mysid shrimp), relative to buffer zones of 0 to 200 ft and the assigned spray drift values for the specific drift scenarios. The results for all scenarios yielded RQs that exceeded all LOCs. The low end drift scenario yielded lower levels of drift, as expected, and consequently lower EECs and RQs. The low end drift scenario, with buffer zones of 0 ft, yielded an RQ of a similar order of magnitude as the one produced by ground applications.

For the NC cotton scenario a buffer zone of 150 ft reduced the peak EECs ( and consequently the RQs) by about 4.4% for the low end drift scenario, 14.1% for the typical drift scenario and 18.9% for the high end drift scenario, compared to the equivalent conditions with no buffer zone. For the NC cotton scenario, the acute RQ for the typical drift scenario, with a buffer zone of 150 ft is approximately 990X the LOC of acute high risk for estuarine/ marine invertebrates. If the application is made under more stringent measures, and the low end drift  5 scenario is used, the RQ decreases slightly to about 918X the LOC of the acute high risk.

Ecological exposure can occur through several pathways. Terrestrial and avian species may inadvertently be exposed to cypermethrin as a result of its direct application to crops ( both dermal and inhalation pathways are possible) and from residues found on food items and in water. Cypermethrin exposure to aquatic organisms can result from spray drift from the target area as well as runoff and erosion of residues.

For the terrestrial assessment, EECs for cypermethrin were calculated using the Tier I model T REX for four crop scenarios: cotton, lettuce, pecans, and canola. The highest EECs were observed for cypermethrin application to cotton.

D. Conclusions  Effects Characterization Results of acute toxicity studies in freshwater fish, freshwater invertebrates ( e. g. daphnids, midge, amphipods, and gastropods), estuarine/ marine fish, and estuarine/ marine invertebrates ( e. g. shrimp and crustaceans), show that technical grade cypermethrin is very highly toxic on an acute basis. The lowest acute LC 50 values reported for freshwater fish, freshwater invertebrates and estuarine/ marine fish range from 0.39 : g a. i./ L in freshwater fish to 0.95 : g a. i./ L in sheepshead minnow. These results suggest that freshwater fish, freshwater invertebrates, and estuarine/ marine fish have a similar susceptibility to cypermethrin toxicity. For estuarine/ marine invertebrates, the lowest acute LC 50 value reported is 0.00475 : g a. i./ L, approximately 100 times lower than the LC 50 values reported for other aquatic animals, indicating that estuarine/ marine invertebrates are more sensitive to cypermethrin toxicity than other types of aquatic animals. Thus, estuarine/ marine invertebrates are expected to be the species at greatest risk for acute effects ( lethality). Cypermethrin is categorized as highly toxic in oysters ( 370 ppb).

Results of acute toxicity studies on cypermethrin formulations in freshwater fish and invertebrates show that cypermethrin formulations are also very highly toxic, with LC 50 values that are similar to those reported for technical grade cypermethrin. Acute toxicity studies on the cypermethrin degradate 3 phenoxy benzoic acid in freshwater fish ( LC 50 = 13.3  36.3 ppm) and invertebrates ( EC 50 = 89  111 ppm) show that the degradate is much less toxic than the parent compound.

Chronic toxicity studies are available for freshwater fish and estuarine/ marine invertebrates. Results in freshwater fish show a LOAEC for early life stage effects at 0.33 ug ai/ L ( NOAEC = 0.14 ug ai/ L), while chronic exposure to estuarine/ marine invertebrates produced NOAEC at 0.781 ng ai/ L.

In addition to lethality data, acute toxicity studies describe sublethal effects of cypermethrin in fish and invertebrates, including rapid and erratic swimming, partial/ complete loss of equilibrium, lethargy, immobilization, and darkened pigmentation. In most toxicity studies, acute NOAEC values for sublethal effects are approximately 2 to 3 fold lower than the corresponding LC 50 values. However, in rainbow trout and bluegill sunfish, the acute NOAEC values for sublethal effects are several orders of magnitude lower than the corresponding LC 50  6 values, indicating that sublethal effects can occur at exposure levels far below the concentrations that cause lethality.

Results of acute toxicity studies on birds suggest that cypermethrin is practically non toxic to slightly toxic to avian species ( LD 50 > 2,000 mg a. i./ kg body weight LC 50 > 2,634 mg a. i./ kg diet) on an acute basis. Chronic avian studies showed no adverse effects at 50 mg a. i./ kg diet ( the highest does tested) but the studies were incomplete because a LOAEC was not determined.( insufficient number of concentrations tested). Chronic risk to birds is inconclusive at this point in the risk assessment and the Agency suggests that the avian reproduction studies be repeated. Mammalian data suggest that cypermethrin is moderately toxic ( LD 50 = 247 mg/ kg body weight ) on an acute basis. A mammalian chronic study shows adverse effects ( decreased body weight and body weight gain) on adults and offspring ( NOAEC = 7.5 mg a. i./ kg/ day; 150 ppm). Results of available toxicity studies indicate that cypermethrin is highly toxic to honey bees ( LD 50 = 0.023  0.56 ug/ bee) and very toxic to earthworms ( LC50 = 26.09 ug/ cm2) on an acute contact basis. Thus, honey bees and other non target terrestrial invertebrates ( e. g. beneficial insects and listed insects) are expected to be at risk for acute effects ( lethality).

E. Uncertainties and Data Gaps The environmental fate database for cypermethrin is considered to be complete. However, monitoring data for cypermethrin in U. S. groundwater, drinking water, surface water, and sediment were not identified in searches of the National Drinking Water Contaminant Occurrence Database ( NCOD), National Water Quality Assessment Program ( NAWQA), or the Storage and Retrieval ( STORET) database.

Estimations regarding the spray drift fraction in the PRZM/ EXAMS model runs were based upon the assumption that the wind speeds at each site are generally below 10 mph. Meteorological data from the four cotton scenarios and the Georgia pecan scenario indicated that the assumption is generally true during the application season. However, for the coastal regions in California where lettuce is grown, the data suggest that this assumption may not be accurate for this particular scenario. As a consequence, slightly higher levels of spray drift were observed ( 3.9 % vs 4.1%) suggesting that the aquatic exposure may have been slightly underestimated. This brings a level of uncertainty to the calculated exposure only for the California lettuce scenario.

Data gaps for ecological effects have been identified as follows:

° No scientifically valid chronic toxicity studies for freshwater invertebrates were submitted by the registrant. Therefore, an NOAEC value was estimated for freshwater invertebrates based on an acute to chronic ratio method using data for estuarine/ marine invertebrates.

° No chronic toxicity studies for estuarine/ marine fish were submitted by the registrant for cypermethrin. Therefore, an NOAEC value was estimated for estuarine/ marine fish using an acute to chronic ratio method using data for freshwater fish.  7 ° No chronic toxicity studies for benthic organisms were submitted by the registrant for cypermethrin. Therefore, an NOAEC value was estimated for benthic organisms based on an acute to chronic ratio method using data for estuarine/ marine invertebrates.

° The available LC 50 value for benthic organisms is expressed in terms of sediment concentration of cypermethrin. To assess risk to benthic organisms in terms of pore water, a surrogate benthic organism LC 50 value for pore water was derived using the sediment LC 50 value and the average K oc value for cypermethrin ( 141,700). Sediment studies are to be submitted by the registrant,

. Avian Reproductive studies were tested at a maximum of 50 ppm while the criteria suggest that maximum testing be completed at 1,000 ppm. Although there were no treatment related effects at the exposure levels listed, including 50 ppm, expected exposure in cotton can be 66 ppm ( short grass).

° Risks to plants ( terrestrial plants and plants inhabiting aquatic and semi aquatic areas) were not evaluated because toxicity data on these receptors are not available. In addition, the Agency data base has not shown incidents of phytotoxicity that were conclusively connected to cypermethrin or other pyrethroid exposure. The neuraltoxic mode of action also precludes cypermethrin phytotoxicity.

II. Problem Formulation A. Stressor Source and Distribution 1. Source and Intensity Cypermethrin (( RS) a cyano 3 phenoxybenzyl ( 1RS, 3RS; 1RS, 3SR) 3( 2,2 dichlorovinyl) 2,2 dimethylcyclopropanecarboxylate) is considered a third generation pyrethroid, that is, more light stable and persistent in the environment than early pyrethroids like allethrin, phenothrin and resmethrin. Like all pyrethroids, cypermethrin has an effective " knockdown" action ( induction of temporary paralysis) for most flying insects and is a contact poison which can quickly penetrate the neural system. Cypermethrin is a mixture of four diastereoisomers, each of which is present as a pair of enantiomers, resulting in eight isomers. It is prepared by the esterification of 3 phenoxybenzaldehyde and 3( 2,2 dichlorovinyl) 2,2 dimethylcyclopropane carboxylic acid. Different ratios of the eight isomers have resulted in four different cypermethrin products ( alpha, beta, theta, and zeta cypermethrin) all of which have similar environmental fate properties, but slightly different toxicities depending upon the isomeric mixture of compounds. The major degradation products of cypermethrin in the environment are DCVA, 3 PBA, and 3 phenoxybenzaldehyde. However the available toxicity data suggest that degradates should not be considered as major stressor sources because of efficacious inactivity of the parent compound after the ester bond has been cleaved.  8 Agricultural uses of cypermethrin in the United States appear to be focused on controlling pests on three crops : cotton, lettuce and pecans, with the predominant use being cotton ( approximately 80% of the agricultural use of cypermethrin is for cotton crops). It is occasionally used alone or in conjunction with organophosphate pesticides to control budworm and bollworm populations on cotton, aphids and mites on pecans, and worms and aphids on lettuce.

There are also several non agricultural uses of cypermethrin. These uses include: pest management inside greenhouses, food processing, storage, dairy facilities ( non contact food uses only), animal kennels, commercial storage facilities, automobile and taxi services, wood treatment applications, and applications to drainage systems.

The wood treatment uses involve treatment of wood outside of structures, spot treatments and treatment of preconstruction lumber and logs. These uses appear not to involve substantial exposure to wildlife.

2. Physical/ Chemical/ Fate and Transport Properties Cypermethrin is expected to have little mobility in soil surfaces ( K OC $ 20,800 L/ Kg) and leaching into groundwater is not expected to be an important transport process. Volatilization is not expected to be an important transport process either, since cypermethrin has a relatively low vapor pressure and Henry's Law constant ( refer to Table 1). Cypermethrin is moderately persistent in the environment and degrades through a combination of biotic and abiotic mechanisms. Cypermethrin is relatively stable to hydrolysis at acidic and neutral pH levels, but degrades in a few days under alkaline conditions ( pH 9, t ½ . 2 days). Cypermethrin is more light stable than the first or second generation pyrethroids like allethrin and resmethrin, but still undergoes photolysis in water, with half lives of about a month or more in distilled water. The rate of photolysis appears to be enhanced in natural waters ( which contain photosensitizing agents like humic and fulvic acids), where the accelerated degradation results in half lives of a few days. Cypermethrin photodegrades on soil with a dark control corrected half life of around 100 days. Under both aerobic and anaerobic soil conditions, cypermethrin biodegrades relatively slowly in soils, with half lives on the order of about 2 months. In contrast, under aerobic and anaerobic aquatic metabolism conditions, the degradation rate is enhanced, with half lives of around 9 to 17 days. If released to water, cypermethrin partitions to sediment and may degrade slowly. Degradates observed in laboratory studies result from cleavage at the ester moiety of cypermethrin, which formed 3( 2,2 dichloro ethenyl) 2,2 dimethylcyclopropane carboxylic acid ( DCVA, max. 79% in pH 9 solution, and 34% in anaerobic aquatic metabolism study) and 3 phenoxybenzaldehyde ( max. 65% in pH 9 solution). The latter one is further oxidized to 3 phenoxybenzoic acid ( 3 PBA, max. 35% in aqueous photolysis study). Another product observed in the soil photolysis study only was cyperamide ( max. 13.3%). For more details about the environmental fate and transport of this chemical and its degradation products, please, refer to section III. B. 1. Environmental Fate and Transport Characteristics. The chemical and physical properties of cypermethrin are summarized in Table 1.  9 Table 1. Physical and Chemical Properties of Cypermethrin.

Property Value Reference Molecular weight 416.3 Laskowski ( 2002)

SMILES notation ClC( Cl)= CC1C( C)( C) C1C(= O) OC( C# N) c2cccc( Oc3ccccc3) c2 CAS number 52315 07 8 Laskowski ( 2002)

Water solubility 4.0x10 3 mg/ L Laskowski ( 2002)

Melting point 78 81 oC Tomlin 1994 Boiling point 200 oC at 9.3 Pa Tomlin 1994 Vapor pressure 2.5x10 9 mm Hg Laskowski ( 2002)

log Kow 6.54 Laskowski ( 2002)

Henry's Law constant 3.4x10 7 atm m3/ mol Laskowski ( 2002)

3. Pesticide Type, Class, and Mode of Action Cypermethrin is classified as a type II pyrethroid, with a cyano group at the " carbon position of the alcohol moiety. Cypermethrin has three optically active centers and is composed of 8 isomers. The insecticidal effect of pyrethroids is characterized by a rapid " knock down", or paralysis, of insects. In insects, the type II pyrethroids predominantly cause ataxia and uncoordinated movement. All pyrethroids act as axonic poisons, affecting both the peripheral and central nervous systems, and share similar modes of action. Pyrethroids, including cypermethrin, stimulate repetitive action in the nervous system by binding to voltage gated sodium channels, prolonging the sodium ion permeability during the excitatory phase of the action potential. This action leads to spontaneous depolarizations, augmented neurotransmitter secretion rate and neuromuscular block, which ultimately results in paralysis of the insect.

4. Overview of Pesticide Usage In the United States, the largest agricultural use of cypermethrin involves its application to cotton crops for the control of pests such as the budworm and bollworm. See section III. A. Use Characterization for additional details about pesticide usage. Also, refer to Appendix L for maps of cypermethrin use. The maximum seasonal application rate of cypermethrin ranges from 0.4 to 0.6 lbs a. i./ A. However, since insecticide resistance is a primary concern in the application of cypermethrin to agricultural crops, the maximum seasonal application rates are not always employed.

Cypermethrin is registered for several nonagricultural uses that include insect pest control products sold to the general public, protection of wood structures ( fences, decks, etc), control of pests in kennels, barns, automobile ( taxi) services, commercial storage facilities ( indoor and  10 outdoor use), eating establishments ( non food contact only), dairy facilities ( non food contact only), food stores or processing plants ( non food contact only), greenhouses, lawns, poultry processing facilities ( non food contact only), and swimming pool water systems. Although it is difficult to evaluate the potential for toxic exposure from non agricultural uses, monitoring of streams adjacent to urban areas ( sudivisions) has shown that toxic levels of pyrethroids, including cypermethrin can be found in sediments as a possible result of residue runoff from urban uses ( lawn care).

B. Receptors 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 exposure to a pesticide. Ecological measures of effect for the screening level risk assessment are based on a suite of registrant submitted toxicity studies performed on a limited number of organisms in broad groupings listed in Table 2.

Within each of these very broad taxonomic groups, an acute and/ or chronic endpoint is selected from the available test data. Additional ecological effects data for cypermethrin are available for honey bees ( Apis mellifera) and benthic organisms and have been incorporated into the risk characterization as an additional line of evidence. A complete discussion of all toxicity data available for this risk assessment and the resulting measures of effect selected for each taxonomic group are included in Appendix E.

Table 2. Taxonomic Groups and Test Species Evaluated for Ecological Effects in Screening Level Risk Assessments.

Taxonomic group Example( s) of representative species Birds a Mallard duck ( Anas platyrhynchos) Bobwhite quail ( Colinus virginianus)

Mammals Laboratory rat ( Rattus norvegicus)

Freshwater fish b Bluegill sunfish ( Lepomis macrochirus) Rainbow trout ( Oncorhynchus mykiss)

Freshwater invertebrates Water flea ( Daphnia magna)

Estuarine/ marine fish Sheepshead minnow ( Cyprinodon variegatus)

Estuarine/ marine invertebrates Eastern oyster ( Crassostrea virginica) Mysid shrimp ( Americamysis bahia)

Notes:

a Birds represent surrogates for reptiles. b Freshwater fish may be surrogates for amphibians ( aquatic phase).  11 1. Aquatic Effects For aquatic effects, registrant submitted studies on cypermethrin technical grade active ingredient ( TGAI) are available for acute and chronic exposure of freshwater fish, acute exposure of freshwater invertebrates, acute exposure of estuarine/ marine fish, and acute and chronic exposure of estuarine/ marine invertebrates. No scientifically valid studies on cypermethrin TGAI were submitted by the registrant for chronic exposure of freshwater invertebrates or estuarine/ marine fish. No toxicity studies on cypermethrin were submitted for algae or aquatic macrophytes.

Additional ecological effects data are available from registrant submitted studies of acute cypermethrin exposure to benthic organisms. Data from aquatic field studies using cypermethrin formulations were identified from registrant submitted studies and open literature studies obtained through the ECOTOX database.

In addition to studies on the parent compound, ecological effects data for the cypermethrin degradate 3 phenoxybenzoic acid are available for freshwater fish and invertebrates. However, cleavage of the ester bond in the parent compound makes the degradates less efficacious and also less of a toxicity risk to non target organisms. Registrant submitted studies on the effects of cypermethrin formulated products are also available for acute exposure of freshwater fish and invertebrates.

Acute and chronic laboratory tests on cypermethrin provide quantitative information regarding lethality, as well as sublethal measures of effect. Results of field studies on cypermethrin provide information on the potential effects on the abundance and diversity of aquatic organisms, especially aquatic invertebrates.

2. Terrestrial Effects For terrestrial effects, registrant submitted studies on cypermethrin TGAI are available for acute exposure to birds and mammals. Although avian reproduction studies are of limited use for this assessment, data on chronic exposure to mammals are available. Additional ecological effects data for cypermethrin are available for honey bees ( Apis mellifera) and earthworms; results of these studies have been incorporated into the risk characterization as an additional line of evidence. No toxicity studies on cypermethrin were submitted for plants inhabiting terrestrial areas. Toxicity data of terrestrial organisms to cypermethrin degradates were not submitted. However, since there is a decline in efficacy after the ester bond is cleaved in the parent compound, the Agency does not expect toxic concern from cypermethrin degradates.

3. Ecosystems at Risk Ecosystems potentially at risk are expressed in terms of the selected assessment measures of effect. The typical assessment measures of effect for screening level pesticide ecological risk assessments are reduced survival, and reproductive and growth impairment for both aquatic and terrestrial animal species. Aquatic animal species of potential concern include freshwater fish and  12 invertebrates, estuarine/ marine fish and invertebrates, and amphibians. Terrestrial animal species of potential concern include birds, mammals, and beneficial insects. For both aquatic and terrestrial animal species, direct acute and direct chronic exposures are considered. In order to protect threatened and listed species, all assessment endpoints are measured at the individual level. Although all endpoints for non endangered species are measured at the individual level, they provide insight about risks at higher levels of biological organization ( e. g. populations and communities). For example, pesticide effects on individual survivorship have important implications for both population rates of increase and habitat carrying capacity. The types of toxicity studies available for cypermethrin are summarized in Table 3.

In addition to guideline required studies, ecological effects data for cypermethrin are available for honey bees ( Apis mellifera), earthworms, and other invertebrates ( e. g., aquatic benthic organisms). Several field studies on the effects of cypermethrin on aquatic ecosystems are also available. Results of these additional studies have been incorporated into the risk characterization as an additional line of evidence.

The ecological relevance of selecting the above mentioned assessment measures of effect is as follows: 1) complete exposure pathways exist for these receptors; 2) the receptors may be potentially sensitive to pesticides in affected media and in residues on plants, seeds, and insects; and 3) the receptors could potentially inhabit areas where pesticides are applied, or areas where runoff and/ or spray drift may impact the sites.

Table 3. Summary of Assessment and Measures of Effect for Cypermethrin ( TGAI).

Assessment Endpoint Measure of Effect 1. Survival, reproduction, and growth of individuals and populations of birds. 1a. Bobwhite quail and mallard duck acute oral LD50. 1b. Bobwhite quail and mallard duck subacute dietary LC50. 1c. Bobwhite quail and mallard duck chronic reproduction > NOAEC.

2. Survival, reproduction, and growth of individuals and populations of mammals. 2a. Laboratory rat acute oral LD50. 2b. Laboratory rat 3 generation reproduction chronic NOAEC and LOAEC.

3. Survival and reproduction of individuals and communities of freshwater fish and invertebrates. 3a. Rainbow trout and bluegill sunfish acute LC50 ( guideline recommended species). Acute LC50 in several other species of freshwater fish 3b. Fathead minnow chronic ( early life) NOAEC and LOAEC. 3c. Water flea acute LC50 and EC50 ( guidelinerecommended species). Acute LC50 and EC50 in several other species of freshwater invertebrates. 3d. Field studies in aquatic ecosystems ( information regarding abundance, diversity, and recovery). Table 3. Summary of Assessment and Measures of Effect for Cypermethrin ( TGAI).

 13 4. Survival and reproduction of individuals and communities of estuarine/ marine fish and invertebrates. 4a. Sheepshead minnow acute LC50. 4b. Eastern oyster and mysid shrimp acute LC50 and EC50 ( guideline recommended species). Acute LC50 and EC50 in several other species of estuarine/ marine invertebrates, crustaceans, and molluscs. 4c. Mysid shrimp chronic NOAEC and LOAEC.

5. Survival of individuals and communities of freshwater benthic organisms. 5a. Midge and amphipod acute LC50.

6. Survival of terrestrial invertebrate populations ( beneficial insects and earthworms). 6a. Honeybee acute contact LD50. 6b. NOAEC in several beneficial insects. 6c. Earthworm acute contact LC50 LD50 = Lethal dose to 50% of the test population. LC50 ( EC50) = Lethal ( effective) concentration to 50% of the test population. NOAEC = No observed adverse effect concentration. LOAEC = Lowest observed adverse effect concentration.

C. Assessment Endpoints Assessment endpoints are defined as " explicit expressions of the actual environmental value that is to be protected." Defining an assessment endpoint involves two steps: 1) identifying the valued attributes of the environment that are considered to be at risk; and 2) operationally defining the assessment endpoint in terms of an ecological entity ( i. e., a community of fish and aquatic invertebrates) and its attributes ( i. e., survival and reproduction). Therefore, selection of the 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 pesticides. 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.

This ecological risk assessment considers maximum application rates of cypermethrin to fields that have vulnerable soils, maximum number of applications, and minimum intervals for uses on representative crops to estimate exposure concentrations. In addition, this assessment is not intended to represent a site or time specific analysis. Instead, this assessment is intended to represent high end exposures at a national level. Likewise, the most sensitive toxicity measures of effect are used from surrogate test species to estimate treatment related direct effects on acute mortality and chronic reproductive, growth and survival assessment endpoints. Toxicity tests are intended to determine effects of cypermethrin exposure on birds, mammals, fish, terrestrial and aquatic invertebrates, and plants. These tests include short term acute, subacute, and reproduction studies and are typically arranged in a hierarchical or tiered system that progresses from basic laboratory tests to applied field studies. The toxicity studies are used to evaluate the potential of a cypermethrin to cause adverse effects, to determine whether further testing is required, and to determine the need for precautionary label statements to minimize the potential  14 adverse effects to non target animals and plants ( CFR 40 § 158.202, 2002). A summary of measures of effects selected to characterize potential ecological risks associated with exposure to cypermethrin is provided in Table 3.

D. Conceptual Model 1. Risk Hypotheses Risk hypotheses are specific assumptions about potential adverse effects ( i. e., changes in assessment endpoints) and may be based on theory and logic, empirical data, mathematical models, or probability models ( US EPA 2004). For this assessment, the risk is stressor initiated, where the stressor is the release of cypermethrin to the environment. The following risk hypothesis is presumed for this screening level assessment:

The use of cypermethrin as an insecticide in agricultural settings involves situations where terrestrial and/ or aquatic animals may be exposed to the chemical. Based on information on persistence, mode of action, direct toxicity and potential indirect effects to trophic food webs, EFED assumes that cypermethrin has the potential to cause reduced survival and reproductive impairment to both terrestrial and aquatic animals.

In order for a chemical to pose an ecological risk, it must reach ecological receptors in biologically significant concentrations. An exposure pathway is the means by which a pesticide moves in the environment from a source to an ecological receptor. For an ecological exposure pathway to be complete, it must have a source, a release mechanism, an environmental transport medium, a point of exposure for ecological receptors, and a feasible route of exposure. In addition, the potential mechanisms of transformation ( i. e., which degradates may form in the environment, in which media, and quantity formed) must be understood, especially for a chemical whose metabolites/ degradates are of greater toxicological concern than the parent compound. The assessment of ecological exposure pathways, therefore, includes an examination of the source and potential migration pathways for constituents, and the determination of potential exposure routes ( e. g., ingestion, inhalation, dermal absorption).

Ecological receptors that may potentially be exposed to cypermethrin include terrestrial and semi aquatic wildlife ( i. e., mammals, birds, and reptiles), terrestrial plants and terrestrial plants in semi aquatic areas, and soil invertebrates. In addition to terrestrial ecological receptors, aquatic receptors ( e. g., freshwater and estuarine/ marine fish and invertebrates, and amphibians) may also be exposed to cypermethrin by its migration from the site of application to various watersheds and other aquatic environments via runoff and spray drift. Data from toxicity studies formed the basis for identifying potential endpoints, stressors, and ecological effects associated with uses of cypermethrin. Although, cypermethrin degradate exposure to aquatic and terrestrial organisms is also possible, the available data suggest that these residues are not expected to be toxic.  15 2. Diagram The conceptual model ( Figure 1) is a generic graphic depiction of the risk hypothesis. It includes the potential pesticide or stressor ( cypermethrin), the source of the pesticide and/ or transport pathways, exposure media, exposure point, biological receptor types, and attribute changes.

In the specific case of cypermethrin, the source and mechanism of release may include ground or aerial spray applications to agricultural crops. Surface runoff from the areas of application is assumed to depend on factors such as topography, irrigation, and rainfall events. Additional transport mechanisms include spray drift and wind erosion, which may potentially transport contaminants to the surrounding sites. In addition, direct deposition may result in contamination of food items that may be consumed by terrestrial organisms.

The major point of exposure for aquatic organisms is direct effects from the water column, as well as sediment and pore water ( gill/ integument uptake). However, indirect effects to aquatic organisms ( especially fish) can also occur through impact to various food chains. Cypermethrin exposure to terrestrial animals is expected through ingestion of food items such as grass, foliage, and small insects. An evaluation of aquatic or terrestrial plants was not conducted in this assessment because of the lack of data. However, a review of available incident reports submitted to the Agency did not find any reports noting toxicity to terrestrial or aquatic plants. In addition, incidents of phytotoxicity have not been reported for other synthetic pyrethroids.

The receptors identified in the conceptual model were identified through a preliminary iterative process of examining environmental fate and ecological effects data. Based on review of the available data, it is hypothesized that both aquatic and terrestrial receptors are at risk from cypermethrin exposure. For aquatic receptors, representative species are certain freshwater and estuarine/ marine fish and invertebrates. For terrestrial receptors, representative species are certain mammals. The attribute changes used to assess risk for aquatic and terrestrial receptors depends upon the type of test ( e. g. reduced survival, growth, or reproduction). Although the Agency does not currently assess quantitative risk to non target beneficial insects, results of laboratory studies are used for a qualitative evaluation.  16

Cypermethrin applied as ground/ aerial spray to an agricultural field Figure 1. Ecological Conceptual Exposure Model for Screening Level Risk assessment of Cypermethrin Applied to Agricultural Fields Volitilization/

Wind Suspension Leaching ( Infiltration/ Percolation)

Direct Deposition Spray Drift Runoff/ Erosion Terrestrial Food Residues ( foliage,

fruit, insects) Water column,

Sediment Groundwater Ingestion Gil/ Integument Uptake Terrestrial Vertebrates Birds, Mammals,

Reptiles Aquatic Invertebrates Aquatic Vertebrates Amphibians Individual Animals Reduced survival Reduced growth Individual Vertebrates Reduced survival Reduced growth Reduced reproduction Bioaccumulation Receptors Attribute Changes Exposure Point Source/ Exposure Media Source/ Transport Pathways  17 E. Analysis Plan This document characterizes risks associated with proposed label uses of cypermethrin. This initial analysis will be referred to as Tier I screening and is based on the deterministic or risk quotient ( RQ) method. As noted in the USEPA 1998, Part A Section 5.1.3, " Typically, the ratio ( or quotient) is expressed as an exposure concentration divided by an effects concentration". Therefore the RQ is the ratio of the estimated environmental concentration ( EEC) of a chemical to a toxicity test effect ( e. g., LC 50 ) for a given species. The RQ as an index of potential adverse effects is then compared to an Agency established Level of Concern ( LOC) in order to identify when the potential adverse effect is a concern to the Agency. These LOCs are the Agency's interpretive policy and are used to analyze potential risk to non target organisms and the need to consider regulatory action. Appendix D of this document summarizes the LOCs used in this risk assessment. Risks to aquatic species were based on estimated environmental concentrations ( EECs) using the Tier II model PRZM/ EXAMS with the help of AgDRIFT to estimate the levelof spray drift to prescribed buffer zones. For aquatic receptors, the main pathway of exposure is water column and sediment/ pore water as a result of drift and runoff from agricultural fields and other sites of application. Risks to aquatic species were based on estimated environmental concentrations ( EECs) in the water column, as well as the sediment/ pore water using the Tier II model PRZM/ EXAMS. Since cypermethrin like other pyrethroids binds to organic matter ( Koc = 141,700 mg/ L) and eventually accumulates in aquatic sediment, toxic exposure to organisms living in this media is a concern. However, the lack of appropriate sediment toxicity studies presents an uncertainty regarding a sediment risk assessment. Therefore, EFED has estimated cypermethrin sediment exposure to benthic organisms by calculating sediment and pore water exposure values using the PRZM/ EXAMS model. The assumptions for the model that pertain to these calculations are based on the equilibrium partitioning ( EqP) theory. This theory holds that a nonionic compound in the sediment partitions between sediment organic carbon, interstitial ( pore) water and benthic organisms ( Di Toro et al., 1991, U. S. Environmental Protection Agency, 2000c). At equilibrium, if the concentration in any one phase is known, then the concentration in the others can be predicted ( Appendix M). Since, EFED is assuming that benthic organisms are no more sensitive to toxic compounds that those organisms living in the water column, measures of effects used in calculating RQ values for sediment/ pore water exposure were derived from standard water column studies ( e. g., LC 50 , EC 50 ). EFED understands that the model generated sediment/ pore water values may be an overestimation or underestimation of actual exposure values noted in the laboratory or field. However, without adequate sediment toxicity studies this estimation approach appears prudent for a screening level assessment of the potential for toxic risk to aquatic benthic organisms ( Walter Berry, U. S. EPA Laboratory, Narragansett RI, personal communication). Residues in potential dietary sources for mammals and birds ( e. g., vegetation and insects) were estimated using the conceptual approach given in the Tier I model TREX Integration of effects and potential exposure provide an estimate of the risk to non target listed/ threatened and non listed animals and plants that could potentially impact the registration decision of cypermethrin under the Federal Insecticide, Fungicide and Rodenticide Act ( FIFRA), the Food Quality Protection Act, and the Listed Species Act.

1. Preliminary Identification of Data Gaps and Methods  18 The adequacy of the submitted data was evaluated relative to Agency guidelines. The following identified data gaps for ecological toxicity endpoints result in a degree of uncertainty in evaluating the ecological risk of cypermethrin.

° No scientifically valid chronic toxicity studies for freshwater invertebrates were submitted by the registrant for cypermethrin. Although this presents an uncertainty, the Agency has extrapolated a chronic NOAEC value based on an acute to chronic ratio method. Therefore, chronic toxicity data for freshwater invertebrates ( invertebrate life cycle) are needed to fully characterize effects to these animals.

° No chronic toxicity studies for estuarine/ marine fish were submitted by the registrant for cypermethrin. The Agency has extrapolated a chronic NOAEC value based on an acute to chronic ratio method.

° Risks to terrestrial plants and terrestrial plants in semi aquatic areas were not evaluated because toxicity data on these receptors are not available. However, there is no information in the incident data reported to EPA that would indicate that cypermethrin has phytotoxic properties. Since the neural toxic mode of action of this compound precludes toxic effects to plants, the Agency does not require phytoxicity studies for cypermethrin at this time.

. The potential exposure of cypermethrin residues in the sediment presents an uncertainty regarding direct toxicity to benthic macroinvertebrates. However, acute and chronic sediment toxicity studies are currently being conducted by the PWG for cypermethrin.  19 2. Measures to Evaluate Risk Hypotheses and Conceptual Model a. Measures of Exposure ° The major routes of dissipation of cypermethrin in the soil are photolysis and aerobic biodegradation. Cypermethrin is relatively stable to hydrolysis at pH 5 and 7, but degrades relatively quickly under alkaline conditions. Cypermethrin adsorbs strongly to soil surfaces and can generally be considered immobile in soils. Cypermethrin is unlikely to reach ground water, but can reach surface waters via spray drift and rainfall events that cause runoff accompanied by erosion. Once in the water, cypermethrin is expected to partition in the sediment.

C For agricultural uses, exposure concentrations for aquatic ecosystems assessments were estimated based on EFED's aquatic Tier II model PRZM/ EXAMS. A graphical user interface ( pe4v01. pl), developed by the EPA ( http:// www. epa. gov/ oppefed1/ models/ water), was used to facilitate inputting chemical and use specific parameters into the appropriate PRZM input files ( inp) and EXAMS chemical files. This approach employs PRZM, which simulates the processes in the agricultural field, such as runoff and erosion, on a daily time step. The runoff and erosion flux output data from PRZM are used as chemical loadings to EXAMS, which simulates surface water in order to predict the EECs. Six PRZM field ( crop) scenarios were modeled: GA Pecans, CA Lettuce, CA Cotton, MS Cotton, NC Cotton, and TX Cotton. These scenarios were selected to represent the major crop uses of cypermethrin in the United States ( see Appendix L, Use Maps). EECs for ecological risk assessment were determined using a pond modeling scenario which describes a generic scenario for the EXAMS component of the modeling exercise.

C The effect of buffer zones on the level of spray drift, and subsequently, the exposure to bodies of water adjacent to treated areas was investigated using the AgDRIFT ® model. The simulations were performed using AgDRIFT ® with spray drift levels for buffer zones of 150 ft. as prescribed by the label for aerial spray applications and 25 ft for ground applications ( for GA pecans). The levels of spray drift obtained from AgDRIFT ® were used as input values in PRZM/ EXAMS.

C Residues in potential dietary sources ( e. g., vegetation and insects) for mammals and birds were estimated using the conceptual approach given in the Tier 1 model T REX Version 1.1 ( T REX, 2004). This model provides estimates of concentrations ( maximum, or upper bound, and average) of chemical residues on the surfaces of different forage that may be sources of dietary exposure for avian, mammalian, reptilian, or terrestrial phase amphibian receptors. The surface residue concentration ( ppm) is estimated by multiplying the application rate ( pounds active ingredient per acre) by a value specific to each food item. The T REX model was run for four crop uses: cotton, lettuce, pecans, and canola. These scenarios were selected to represent a variety of crops and use sites in the continental US.

C The effect of spray drift and buffer zones on exposure to bodies of water adjacent to  20 treated areas was investigated using the AgDRIFT ® model. As a first step, the evaluation of spray drift as a possible predominant route of exposure for a North Carolina crop scenario ( NC cotton) was performed using the PRZM/ EXAMS model. Both crops were run with spray drift set to 0% ( to estimate the extent of spray drift for that crop scenario), compared to the default value of 5%. Furthermore, EFED bracketed the spray drift options by running a " high end" ( conservative), " typical," and a " low end" drift scenarios. The simulations were performed using AgDRIFT ® with spray drift levels for buffer zones of 0 to 200 ft. at the " low" end, " typical," and " high" end drift scenarios. The output values from AgDRIFT ® were used as input values in PRZM/ EXAMS.

b. Measures of Effect Measures of ecological effects are obtained from a suite of registrant submitted guideline studies conducted with a limited number of surrogate species. The test species are not intended to be representative of the most sensitive species but rather were selected based on their ability to thrive under laboratory conditions. Registrant submitted data are available for cypermethrin TGAI, the cypermethrin degradate 3 phenoxybenzoic acid, and cypermethrin formulated products. A complete summary of the measures of effect based on toxicity studies for different ecological receptors and measures of effect ( acute/ chronic) for cypermethrin ( TGAI) is given in Table 3, with study details provided in Appendix E. Examples of measures of acute effects ( e. g., lethality) include an oral LD 50 for mammals and LC 50 for fish and invertebrates. Examples of measures of chronic effects include NOAEC values for birds or mammals based on reproduction or developmental measurements.

A search of the open literature using EPA's Ecotoxicology database ECOTOX was conducted to identify studies o the following: ( 1) information to fill data gaps for chronic cypermethrin exposure to freshwater invertebrates and chronic estuarine/ marine fish, and ( 2) field studies on the effects of cypermethrin on aquatic and terrestrial populations. Search of the ECOTOX database did not identify chronic exposure studies in freshwater invertebrates and estuarine/ marine fish. Several aquatic field studies were identified; this literature is summarized and included as supporting lines of evidence for the risk characterization.

c. Measures of Ecosystem and Receptor Characteristics For the assessments using the Tier II aquatic model PRZM/ EXAMS and the Tier I terrestrial model T REX, the ecosystems that are modeled are intended to be generally representative of any aquatic or terrestrial ecosystem associated with areas where cypermethrin is used. The receptors addressed by the aquatic and terrestrial risk assessments for cypermethrin are summarized in Table 3. For aquatic assessments, fish and aquatic invertebrates in both freshwater and estuarine/ marine environments are represented. For terrestrial assessments, three different size classes of birds and mammals are represented, along with four potential foraging categories.

III. Analysis  21 A. Use Characterization The use rates and patterns of usage for cypermethrin on some important crops are shown in Table 4.

Table 4. Usage Rates for Cypermethrin 1.

Crop or Crop Group Maximum Single Application Rate ( lb a. i./ A) Maximum Number of Applications Minimum Application Interval ( days) Maximum Application Rate per Season ( lb a. i./ A/ season) PHI2 Cotton 0.1 6 3 0.6 14 Pecans 0.1 6 53 0.6 21 Lettuce, head 0.1 6 74 0.6 5 Bulb vegetables ( includes dry bulb onions, green onions, garlic, scallions) 0.1 5 7 0.5 7 Head and stem Brassica ( includes broccoli, Brussel sprouts, cauliflower, kohlrabi, cabbage) 0.1 6 7 0.6 1 Leafy Brassica ( includes broccoli Raab, Chinese cabagge, collards, kale, mustard greens, mustard spinach, canola) 0.1 4 7 0.4 1 ( 1). Data obtained from label for Ammo 2.5 EC ( EPA Reg. No. 279 3027) ( 2) PHI. Pre harvest interval is the minimum number of days which the pesticide can be applied prior to harvest. ( 3) Not provided on the label; estimated from use pattern data ( 4) Not provided on the label.

The dominant agricultural use of cypermethrin in the United States is related to its use in pest management of cotton crops ( 80% of the total cypermethrin use), with lesser amounts used for lettuce ( 11%), pecans ( 5%) and onions ( 4.8%). The crop use patterns maps in the United States obtained from the National Center for Food and Agricultural Use Policy Pesticide Use Database are provided in Appendix L. [ Note: Due to the clarity of the data included in Appendix L, selected figures ( Figures L 2 to L 5), were brought forward, and are shown at the end of this section.]  22 The 1997 estimated annual use of cypermethrin on all crops in the United States, obtained from the National Center for Food and Agricultural Policy National Pesticide Use Database ( NCFAP 2005) summarized by state, are provided in Figure L 1, along with a list of crop use patterns ( see Appendix L). The highest total application of cypermethrin was in the state of Georgia for 1997 ( 37% of national use). The 1997 estimated annual application rate of cypermethrin on all crops summarized by county is shown in Figure L 2, along with a list of crop use patterns. It provides similar information to that included in Figure L 1, but in another format. Greatest application rates were in the following regions; Upper Coastal Plain of Georgia, Inner Coastal Plain of North Carolina, Mississippi Valley, and the central coast of California.

Cotton An individual map of cypermethrin's use for cotton crop is shown in Figure L 3 ( presented at the end of this section). This map also illustrates the PRZM model scenarios used in the surface water exposure assessments as well as the NAWQA surface water stations throughout the country. Cypermethrin use on cotton is greatest in the state of Georgia. Cotton harvest data by county for 1997 for the United States were obtained from the National Agricultural Statistics Service ( NASS) and are shown in Figure L 6 ( Appendix L). Use of cypermethrin on cotton in 1997 by county where harvested is shown in Figure L 7 ( Appendix L). The greatest application of cypermethrin on cotton was in the Upper Coastal Plain region of Georgia; other regions of high cypermethrin application include the South Atlantic Inner Coastal Plain, Mississippi Valley, North Texas Plains, and the Central Valley of California.

The timing of cypermethrin applications varies from crop to crop based on planting date, harvesting schedule, crop maturity date, insect pressure and the type of insects to be controlled. Cotton crops are usually planted in the early spring and cypermethrin is frequently employed in order to control cotton bollworm and tobacco budworm, which may begin to infest the crop before the first bloom. Treatment is advised when 15 small larvae are found per 100 plant terminals, or 20% of squares are damaged ( Roof 2004). More often damage is noted following the first bloom ( usually occurring in early to mid summer depending upon planting date). It is advised that pyrethroid insecticides such as cypermethrin not be used on cotton prior to July 1 unless infestations are high, to reduce selection pressure for resistance in tobacco budworm and cotton bollworm ( Roof 2004).

Lettuce An individual map of cypermethrin's use for lettuce crop is shown in Figure L 4 ( presented at the end of this section). This map also illustrates the PRZM model scenario used in the surface water exposure assessment as well as the NAWQA surface water stations throughout the country. Cypermethrin use on lettuce is greatest in the state of California. In coastal southern California, lettuce is a year round crop, so the application of cypermethrin can vary. The major production areas for iceberg ( crisphead) lettuce ( Lactuca sativa) in California are the central coast ( Monterey, San Luis Obispo, San Benito, Contra Costa, and Santa Clara Counties), the southern coast ( Santa Barbara and Ventura Counties), the Central Valley ( Fresno, Kings, and Kern Counties), and the southern deserts ( Imperial and Riverside Counties) ( Jackson et. al. 1996). Production is highest in Monterey County, followed by Imperial County. Planting to harvest typically requires 70 to 80 days for midsummer planting and up to130 days for late fall planting. Lettuce is a cool season  23 crop with certain temperature requirements. The optimal growing temperatures are 73 /

F ( 23 /

C) during the day and 45 /

F ( 7 /

C) at night. Most California lettuce growing regions have daytime temperatures that range from 63 /

to 83 /

F ( 17 /

to 28 /

C) and night temperatures that range from 37 /

to 53 /

F ( 3 /

to 12 /

C). At the high end of the temperature range, lettuce may bolt, causing bitterness and loose, fluffy heads, and tipburn is also common. At temperatures near freezing, young plants are not damaged, but growth is stunted. Freezing can damage the outer leaves of mature lettuce, leading to decay in handling ( Jackson et. al. 1996).

Pecan An individual map of cypermethrin's use for pecan crop is shown in Figure L 5 ( presented at the end of this section). This map also illustrates the PRZM model scenario used in the surface water exposure assessments as well as the NAWQA surface water stations throughout the country. Cypermethrin use pecans is greatest in the state of Georgia. Aphids, mites and shuckworms are common pests for pecan crops. Hickory shuckworms are present throughout the season, but damaging numbers usually do not occur until June or later ( Gorsuch 2003). Georgia pecans become mature in October and are harvested from October through December. Applying cypermethrin too early in the season may kill beneficial insects such as lady beetles and lacewings which suppress mites and aphids. Therefore, applications early in the season should be avoided. Pecan aphids have been shown to become resistant to pyrethroids very rapidly. It is suggested that pyrethroids be used: ( 1) only late in the season ( to lessen the number of aphid generations exposed); ( 2) only if other materials fail to adequately suppress aphids or other pests; ( 3) in combination with an organophosphate material; ( 4) in no more than two consecutive sprays; and ( 5) not after the third week of September ( Gorsuch 2003).  24 Figure L 2: 1997 Cypermethrin Application on All Crops Caution: The pesticide use maps available from this site show regional scale patterns of use intensity within the United States and are not intended for making local scale estimates of pesticide use, such as for individual counties. The maps are based state level estimates of pesticide use rates for individual crops, which have been compiled by the National Center for Food and Agricultural Policy ( NCFAP) for 1995 1998, and on 1997 Census of Agriculture county crop acreage. Key limitations include: ( 1) state use coefficients represent an average for the entire state and consequently do not reflect the local variability of pesticide management practices found within many states and counties, and ( 2) the county level acreage are based on the 1997 Census of Agriculture and may not represent all crop acreage due to Census non disclosure rules. Please refer to Method for Estimating Pesticide Use for a detailed discussion of how the pesticide use data were developed. http:// ca. water. usgs. gov/ cgi bin/ pnsp/ pesticide_ use_ maps_ 1997. pl? map= W6011  25 Figure L 3: 1997 Cypermethrin Application on Cotton  26 Figure L 4: 1997 Cypermethrin Application on Lettuce  27 Figure L 5: 1997 Cypermethrin Application on Pecan  28 B. Exposure Characterization The chemical and physical, and environmental fate properties of cypermethrin are summarized in Table 5.

Table 5. Physical and Chemical and Environmental Fate Properties of Cypermethrin.

Property Value Reference Molecular weight 416.3 Laskowski ( 2002)

SMILES notation ClC( Cl)= CC1C( C)( C) C1C(= O) OC( C# N) c2cccc( Oc3ccccc3) c2 CAS number 52315 07 8 Laskowski ( 2002)

Water solubility 4.0x10 3 mg/ L Laskowski ( 2002)

Melting point 78 81 oC Tomlin 1994 Boiling point 200 oC at 9.3 Pa Tomlin 1994 Vapor pressure 2.5x10 9 mm Hg Laskowski ( 2002)

log Kow 6.54 Laskowski ( 2002)

Henry's Law constant 3.4x10 7 atm m3/ mol Laskowski ( 2002)

Hydrolysis half life: pH 5 pH 7 pH 9 stable stable 1.8 and 2.5 days cis/ trans DCVA ( max. 79% at 120 hr) and 3 phenoxybenzaldehyde ( max. 65% at 120 hr) MRID 42620501 Aqueous photolysis half life 36.2 days 3 PBA ( max. 35% at 35 days) MRID 42395701 Soil photolysis half life sandy loam 55 days cyperamide ( steadily increased to a max. of 13.3%) MRID 42129001 Aerobic soil metabolism half life 60.7 days 59.8 days cis/ trans DCVA ( max. 24% at 62 days, study duration 150 days) MRID 42156601 Anaerobic soil metabolism half life 53.3 days 63 days cis/ trans DCVA ( max. 33% 30 days after flooding), 3 PBA ( max. 26% at 60 days after flooding or end of study) MRID 42156602 Table 5. Physical and Chemical and Environmental Fate Properties of Cypermethrin.

Property Value Reference  29 Aerobic aquatic half life 8.9 days 10.1 days trans DCVA ( max. 49% at 30 days), cis DCVA ( max. 19% at 30 days), 3 PBA ( max. 42% at 30 days); study duration, 90 or 183 days. MRID 45920801 Anaerobic aquatic half life 13.8 days 16.5 days DCVA ( max. 34% at 71 days) MRID 44876105 Adsorption coefficient Koc ( L/ Kg)

  Aged Column Leaching Study 328,500 ( Sand) 134,900 ( Sandy loam) 82,600 ( Silty loam) 20,800 ( Clay loam)  Degradate cis/ trans DCVA found at up to 13.2% in the leachate MRID 42129003   MRID 42129002 Bioconcentration factor ( BCF) 161X edible portion 448X whole fish 883X non edible moderately slow depuration, with 10 15% of residues remaining after 21 days of depuration MRID 42868203 1. Environmental Fate and Transport Characterization The environmental fate data for cypermethrin was developed mostly with studies on cypermethrin; however, some studies were conducted on zeta cypermethrin. Both, cypermethrin and zeta Cypermethrin are expected to have similar fate in the environment.

a. Summary of Empirical Data Laboratory studies have indicated that cypermethrin degrades through a combination of biotic and abiotic reactions and is moderately persistent in the environment. Under acidic and neutral conditions this compound is relatively stable, but is readily hydrolyzed under alkaline conditions with a half life of approximately 2 days at pH 9. Cypermethrin is relatively stable to photolysis in laboratory studies using distilled water at pH 7, with a half life of approximately 36 days. Cypermethrin has been shown to biodegrade in aerobic and anaerobic soils with half lives on the order of about 2 months and in aerobic and anaerobic aquatic systems with half lives on the order of one to two weeks. Cypermethrin is considered immobile in soils and its potential to leach into groundwater is low. If released to water, cypermethrin will rapidly partition to the sediment compartment which acts as an environmental sink for this compound. Cypermethrin  30 bioaccumulates moderately in fish ( 448X in whole fish), with moderate depuration. Besides carbon dioxide, important transformation products observed in laboratory studies included trans DCVA, 3 phenoxybenzaldehyde, 3 PBA, and 3 cyperamide. Except for cyperamide, these transformation products result from the cleavage at the ester moiety of cypermethrin. They do not retain the basic structure of the parent. Cyperamide was observed in the lower end of the concentrations for which EFED requires identification ( max. 13.3%, only in the soil photolysis study). In terrestrial field dissipation studies cypermethrin does not appear to be very persistent in soils or leach substantially ( half lives 1 2 weeks). In supplemental aquatic field dissipation studies ( zeta cypermethrin), the chemical appears to persist in the sediment, with reported half lives of 126 and 181 days in LA and CA, respectively.

b. Degradation and Metabolism Cypermethrin labeled with 14C at the cyclopropyl and benzyl moieties was relatively stable at pH 5 and 7 buffered solutions, but degraded rapidly with half lives of approximately 2 days in pH 9 solutions. The major degradation products of the base catalyzed hydrolysis of cypermethrin were cis and trans DCVA ( maximum 79% at 120 hours or study duration) and 3 phenoxybenzaldehyde ( maximum 65% at 120 hours). Photolysis of cypermethrin in distilled water occurs slowly, but the rate of degradation appears to be enhanced in natural waters, which contain humic and fulvic acids. A photolysis half life of 36 days was observed for cypermethrin in pH 7 aqueous buffered solution exposed to sunlight in California from March to April. Shorter half lives on the order of less than 1 to 4 days were observed for cypermethrin dissolved in river water, seawater and distilled water with 1% humic acid exposed to sunlight ( Takahashi et al. 1985). The half life for thin films of cypermethrin in a sandy loam soil matrix was approximately 55 days; however, degradation was also observed in control samples and the dark control corrected half life is over 100 days. The only transformation product observed was cyperamide, at 13.3% at the end of the study ( 35 days). Cypermethrin degraded with a half life of approximately 60 days in a fine sandy loam soil maintained at 25 oC and held under aerobic conditions. Carbon dioxide and a mixture of cis and trans DCVA ( maximum 24% at 62 days in a 150 day study) were the major degradation products.

Under aquatic conditions, zeta cypermethrin degraded more rapidly ( 8.9 10.1 days in a supplemental aerobic aquatic study and 13.8 16.5 days in an anaerobic aquatic study). Degradation products under aerobic aquatic conditions included trans DCVA ( max. 49% at 30 days), cis DCVA ( max. 19% at 30 days) and 3 PBA ( max. 42% at 30 days, study duration 183 days). Under anaerobic conditions, the only degradation product was DCVA at 34% at 71 days ( study duration 90 days for benzyl label and 183 days for cyclopropyl label).

c. Transport and Mobility Cypermethrin is considered immobile in soil. Soil organic carbon adsorption coefficients ( K oc ) for cypermethrin ranged from approximately 21,000 to 385,000 L/ Kg in four soils ( sand, sandy loam, silty loam and clay). If released into water, cypermethrin rapidly partitions to the sediment column. The tendency to adsorb to soil and sediment along with the relatively low vapor pressure ( 2.5x10 9 mm Hg) and Henry's law constant ( 3.4x10 7 atm m3/ mol), indicates that  31 volatilization from water and soil will not be an important transport process. It can be concluded that the cypermethrin degradates 3 PBA and trans DCVA have a high potential for mobility as they were weakly sorbed to four soils tested. 3 PBA was slightly more sorbed ( K oc values ranging from 118 to 215) to the tested soils than was trans DCVA ( K oc values ranging from 18 to 48).

d. Bioaccumulation Cypermethrin shows a high potential for bioaccumulation in fish, with maximum BCFs of 161X for edible tissue, 833X for viscera, and 444X for whole fish ( for the cyclopropyl label) at 28 day ( last day of the study). A steady state may not have been reached after the study duration, therefore, the BCFs may be underestimated. Depuration appeared to be moderately slow, with near 10 15% of the initial residues remaining after 21 days.

e. Field Studies Terrestrial field dissipation studies conducted in Madera, CA and Cheneyville, LA indicated that the field dissipation half life of cypermethrin is approximately1 to 2 weeks.

Cypermethrin in the form of Ammo 2.5 EC was applied three times at 0.2 lb ai/ acre/ application to a bare silt loam soil ( 78 82% sand, 14 20% silt, 2 4% clay, 0.2 0.6% OM, pH 6.5 7.2) located in Madera, California and soil samples were analyzed for cypermethrin and potential degradates cis DCVA, trans DCVA, and 3 phenoxybenzoic acid. Cypermethrin was detected in 3 6" cores collected immediately after each application ( 18, 8, and 33 µ g/ kg), and on day 2 ( 20 µ g/ kg) and day 4 ( 29 µ g/ kg) following the third application. Cypermethrin was detected at 10 µ g/ kg in one 6 12" core collected 2 days after the final application, but it was not detected above a detection limit of 7 µ g/ kg in any soil cores collected below this depth. The degradate 3 phenoxybenzoic acid was detected in 0 3" cores collected immediately after the second application ( 8 µ g/ kg), immediately after the third application ( 17 µ g/ kg), and the following days after the third application: day 2 ( 25 µ g/ kg), day 4 ( 32 µ g/ kg), day 7 ( 25 µ g/ kg), day 14 ( 24 µ g/ kg), day 21 ( 8 µ g/ kg), and day 28 ( 7 µ g/ kg). It was not detected above a detection limit of 7 µ g/ kg in any soil cores collected below 3 inches. Potential degradates cis and trans DCVA were not detected above a detection limit of 7 µ g/ kg in any of the soil cores. An analysis of the cypermethrin concentration as a function of time yielded a field dissipation half life of 13 days.

Cypermethrin in the form of Ammo 2.5 EC was applied three times at 0.2 lb ai/ acre/ application to a bare loamy sand soil ( 30% sand, 64% silt, 6% clay, 0.7% OM, pH 7.0) located in Cheneyville, LA. The soil cores were analyzed for cypermethrin and potential degradates cis DCVA, trans DCVA, and 3 phenoxybenzoic acid. Based upon dissipation in the top 0 3" soil cores, the dissipation half life for cypermethrin was 5 days. Cypermethrin was not detected above a detection limit of 7 µ g/ kg in any cores collected below 3 inches. The degradate trans DCVA was detected in 0 3" cores collected on the following days after the third application: day 2 ( 16 µ g/ kg) and day 7 ( 8 µ g/ kg). The degradate 3 phenoxybenzoic acid was detected in 0 3" cores collected immediately after the second application ( 10 µ g/ kg), immediately after the third application ( 20 µ g/ kg), and 2 days after the 3rd application ( 44 µ g/ kg). The degradate cis DCVA was not detected above a detection limit of 7 µ g/ kg in any of the soil cores.  32 None of the analytes were detected above a detection limit of 7 µ g/ kg in any of the soil cores collected below 3 inches.

Cypermethrin is not used in aquatic sites; however, there are two supplemental studies conducted with zeta cypermethrin in California and Louisiana. The half lives were 181 days and 126 days, respectively. These half lives are not similar to those observed in the laboratory studies. Nevertheless, the reported half lives included the sediments only.  33 Figure 2. Cypermethrin and its Degradation Products O CN O O Cl Cl COOH Cl Cl DCVA O COOH O CHO Cypermethrin 3 Phenoxybenzoic acid ( 3 PBA or m PBA)

3 Phenoxybenzaldehyde O C O O Cl Cl O NH2 Cyperamide  34 2. Measures of Aquatic Exposure a. Aquatic Exposure Modeling Estimated environmental concentrations ( EECs) of cypermethrin in surface water were calculated using the Tier II aquatic model PRZM/ EXAMS. Certain subroutines of the graphical interface ( shell, pe4), enabled the determination of the pore water concentrations and the sediment concentrations. The levels of spray drift corresponding to the buffer zones imposed by the labels were obtained from AgDRIFT ® .

The Tier II approach employs PRZM ( Pesticide Root Zone Model; version 3.12 Beta compiled May 24, 2001) and EXAMS ( Exposure Analysis Modeling System; version 2.98.04 compiled November 12, 2002). PRZM simulates runoff and erosion from an agricultural field on a daily time step. The runoff and erosion flux output data from PRZM are used as chemical loadings to the EXAMS surface water program in order to predict the EECs. A graphical user interface ( pe4v01. pl) developed by the EPA ( http:// www. epa. gov/ oppefed1/ models/ water) was used to facilitate inputting chemical and use specific parameters into the appropriate PRZM input files ( inp) and EXAMS chemical files. The " write benthic pore water concentrations" and " write benthic sediment file" instructions of the interface were activated to obtain the pore water concentrations and the sediment concentrations. EXAMS is a model that has a set of process modules that link fundamental chemical properties to limnological processes that control the kinetics and transport of chemicals in aquatic systems. It provides facilities for steady state or long term evaluation of chronic chemical discharges, initial value approaches for studying shortterm contaminant releases, and full kinetic simulations that allow for monthly variation in mean climatological factors, and changes in contaminant loadings on daily time scales. It is fairly and relatively complex model that requires more input variables, ranging from hydro geological and weather data to pesticide physicochemical properties, mobility coefficients, and degradation rate constants in the aqueous and sediment phases.

The label of cypermethrin requires the following buffer zones: 25 ft for ground applications; 150 ft for aerial applications; and 450 ft for ultra low volume ( ULV) aircraft application. A vegetative filter strip is also required ( 10 ft) to protect any aquatic area from runoff. For aerial applications, spray should be released at the lowest height consistent with adequate pest control and flight safety. Applications more than 10 ft above the crop canopy are discouraged. Formation of very small droplets may be minimized by appropriate nozzle selection, by orientating nozzles away from the air stream as much as possible, and avoiding excessive boom pressure. The labels for cypermethrin recommend that the boom ( release) height be # 10 ft and the wind speed during application favors on target product deposition ( recommended wind speed 3 10 mph, but do not apply when wind speed exceeds 15 mph).

The spray drift program AgDRIFT ® was employed in the Tier I mode to refine the drift estimate in order to accommodate the label requirements of cypermethrin. The default value of spray drift assigned for aerial applications is 5%. Using the model, a spray drift value of 3.9% was obtained in the Tier I mode, using a buffer zone of 150 ft. This assumption in AgDRIFT ® is appropriate if the meteorology of the growing area is consistent with a wind speed of # 10 mph.  35 The wind speeds of Jackson, MS ( representative of the MS cotton scenario), Wilmington, NC ( representative of the NC cotton scenario), Bakersfield, CA ( representative of the CA cotton scenario), Austin and Lubbock, TX, ( representative of the TX cotton scenario) and Macon GA ( representative of the GA pecans scenario) were analyzed using the AgDRIFT ® database ( which contains data of numerous weather stations in the nation). In each case, the 75th percentile of the average wind speed is below 10 mph during the application period ( late Summer) and the assumption that the wind speed will be at or below 10 mph is generally justified for the selected crop scenarios. On the other hand, California lettuce is grown in several areas of the state, with the heavier growth in Monterey, San Luis Obispo and Santa Barbara counties. All three of these counties are coastal regions with varying wind speeds throughout the year. Data from surrogate weather stations located in San Francisco ( close to Monterey, to the North) and Los Angeles ( close to Santa Barbara) indicate that the assumption that wind speeds are usually below 10 mph during the application period may be inaccurate. Therefore, the assumption of a level of spray drift of 3.9% for the California lettuce scenario may not be too conservative. This brings an uncertainty to the level of spray drift only for the California lettuce scenario.

The GA pecans are different in that they are representative of ground applications. Applications to pecans are done usually by airblast. The Tier 1 Airblast mode of AgDRIFT ® was used to determine the level of spray drift. The vegetation type selected was " Dense ( Citrus, Tall Trees)." This composite orchard combines almonds, oranges, grapefruit, small grapefruit ( mist blower), and pecans. The level of spray drift was obtained for 25 ft buffer zone, using the " Toolbox" Aquatic Assessment, it was multiplied by 3, as per current guidelines, to obtain an approximation of the 90th percentile value [( 0.0074)( 3) = 0.0222 = 2.22% spray drift]. Since pecans can be very tall trees, to characterize the upperbound levels of spray drift that might be found in the field, the vegetation type " Sparse ( Young, Dormant)" was also calculated. It involves the most conservative scenario for airblast applications. For a buffer zone of 25 ft, the level of spray drift was 4.5%. This level of spray drift would be expected on pecans only under exceptionally conservative conditions.

The application rates and other use data for cypermethrin applied to cotton, pecans and lettuce are presented in Table 6a. Input parameters for the PRZM/ EXAMS modeling are listed in Table 6b. They were selected according to current guidelines for the selection of input parameters, except for the levels of spray drift, which were obtained as explained in the previous paragraphs.

Table 6a. Use Patterns of Cypermethrin for Cotton, Pecans and Lettuce. a Crop or Crop Group Maximum Single Application Rate ( lb a. i./ A) Maximum Number of Applications Minimum Application Interval ( days) Maximum Application Rate per Season ( lb a. i./ A/ season)

Cotton 0.1 6 3 0.6 Pecans 0.1 6 5 b 0.6 Lettuce, head 0.1 6 7 0.6 Table 6a. Use Patterns of Cypermethrin for Cotton, Pecans and Lettuce. a  36 a Data obtained from label for Ammo 2.5 EC ( EPA Reg. No. 279 3027) b Not specified on any active labels, but surmised from use information data.

Table 6b. PRZM/ EXAMS Inputs for Cypermethrin.

PARAMETER VALUE SOURCE Application date Cotton July 1st Lettuce August 1st Pecans August 1st Crop specific a Aerobic soil metabolism half life 62 days MRID 42156601 ( 90% C. L. on the mean, n = 2 observations)

Koc 141,700 MRID 42129003 ( mean value, n= 4)

Henry's Law Constant 3.4x10 7 atm m3/ mol Laskowski ( 2002)

Aerobic aquatic metabolism 11.3 days MRID 45920801 ( 90% C. L. on the mean, n = 2 observations)

Anaerobic aquatic metabolism 19.3 days MRID 44876105 ( 90% C. L. on the mean, n = 2 observations)

Aqueous photolysis half life 36.2 days MRID 42395701 Hydrolysis half life ( days) pH 5 pH 7 pH 9 stable stable 1.90 MRID 42620501 Molecular weight 416.3 Laskowski ( 2002)

Solubility ( WSOL) 0.04 ppm Laskowski ( 2002) ( solubility x 10)

Vapor pressure ( VP) 2.5x10 9 Laskowski ( 2002)

PLDKRT ( foliage pesticide rate constant) 0.13 days 1 Willis and McDowell ( 1987)

FEXTRC ( foliar extraction) 0.5 EFED Model Input Guidance, Version II ( 2002)

FILTRA ( filtration parameter; required if CAM set to 3) NA

CAM ( chemical application method) 2 Reflects foliar application IPSCND 1 Surface Applied Table 6b. PRZM/ EXAMS Inputs for Cypermethrin.

PARAMETER VALUE SOURCE  37 Application efficiency ( fraction) 0.99 for pecans 0.95 for other crops EFED Model Input Guidance, Version II ( 2002)

Spray drift ( fraction) 0.022 for pecans 0.039 for other crops Calculated with AgDRIFT ® ( Tier 1): pecans is applied by ground ( airblast) with a buffer zone of 25 ft, other crops aerially with a buffer zone of 150 ft a See overview of pesticide use section for more information For cotton, a starting application date of July 1st was chosen based on the crop emergence dates given in Tables 5 9 of the PRZM manual and the recommendation that pyrethroid insecticides not be used on cotton prior to July 1 unless infestations are high, to reduce selection pressure for resistance in tobacco budworm and cotton bollworm.

Lettuce is a year round crop in California, so the application timing of cypermethrin can vary ( Jackson et al. 1996). In the southern desert areas, iceberg lettuce is planted from mid September to mid November and the harvest occurs from early December to January and February. In the lettuce growing areas of the central coast, where temperatures are fairly uniform year round, lettuce is planted from late December to mid August for harvest from early April to November. Southern coastal areas have planting dates from November to August for harvest from April to December. In the Central Valley, iceberg lettuce is planted from early August to early September for harvest from late October to mid November. Other planting are made from early November to late December for harvest in April. For a midsummer planting, the harvest usually begins 70 80 days later. One advantage of winter or spring lettuce is that insect pressure is generally low, minimizing the need for pesticide applications.

Pecan aphids have been shown to become resistant to pyrethroids very rapidly and it is suggested that pyrethroids be used only in late season to lessen the number of aphid generations exposed ( Gorsuch 2003). The harvest date of pecans in Georgia begins in October. To accommodate the 21 day pre harvest interval for cypermethrin a starting application date of August 1 was selected.

Output from the PRZM/ EXAMS simulation is typically a series of estimated environmental concentrations ( EECs) corresponding to multiple years of meteorological data. Each value is an estimate of the peak concentrations corresponding to a specific averaging time ( e. g., 96 hours, 21 days, etc.).

The raw output files generated by PRZM/ EXAMS are summarized in Appendix B. Output values for each of the crop scenarios are described below.  38 Cotton There are three QCed PRZM scenarios for cotton crop usage : California, Mississippi and North Carolina. The Texas scenario is not a standard scenario, but was utilized in this assessment because of the high usage of cotton of this chemical. Each of these were modeled using the same application rates and use patterns shown in Table 4 and Table 6a. The California scenario is based on data from Fresno County in the Central Valley region using a Twisselman clay as the representative soil for this region. This soil is a fine, mixed, calcareous, thermic Typic Torriorthents of hydrologic group C. The Mississippi scenario arises from Yazoo County and uses a Loring silt loam as the representative soil. Loring silt loam is a fine silty, mixed, active, thermic, Qxyaquic Fragiudalfs of hydrologic group C. The representative soil in the North Carolina PRZM scenario is a Boswell fine sandy loam of hydrologic group D, characteristic of the Piedmont/ Coastal Plain region. The soil selected to simulate the Texas scenario is a Crockett fine sandy loam. Crockett fine sandy loam is a fine, smectitic, thermic Udertic Paleustalfs of hydrologic group C.

Since cotton growth requires a relatively long period of warm temperatures ( 190 210 days at temperatures of 60 ° F and above), it is typically planted in the spring with crop maturity occurring roughly 4 months after the planting date. While late season planting can occur up to June in many southern states, it is not advisable to begin planting after mid May because of the steep decline in yield ( the best yields usually occur with early season planting, optimal soil temperature and moisture and air temperature). Harvest typically occurs from September 1 through December. It is advisable to avoid applying pyrethroid insecticides on cotton crops prior to July 1 unless infestations are high, in order to avoid insect resistance later in the season ( Roof 2004).

The EECs in surface water, pore water and sediment for the cotton use scenarios are shown in Table 7.  39 Table 7. Cypermethrin Surface Water, Pore Water and Sediment EECs Obtained from PRZM/ EXAMS COTTON Crop Use. a Site Peak 21 day 60 day 90 day Surface Water ( ug/ L)

California 0.178 0.055 0.022 0.015 Mississippi 1.28 0.188 0.102 0.072 North Carolina 2.01 0.192 0.101 0.076 Texas 0.493 0.060 0.030 0.022 Pore Water ( ug/ L)

California 0.0044 0.0036 0.0024 0.0018 Mississippi 0.0280 0.0238 0.0164 0.0125 North Carolina 0.0304 0.0253 0.0179 0.0147 Texas 0.0073 0.0054 0.0038 0.0032 Sediment ( ug/ kg)

California 25.28 20.47 13.58 9.95 Mississippi 158.1 134.8 93.2 70.8 North Carolina 171.8 143.9 101.9 83.2 Texas 47.8 30.6 21.4 18.2 a 1 in 10 year probability The higher EECs observed in the North Carolina and Mississippi sites are due to meteorologic conditions and the characteristics of the fields at these two sites. The slope of the fields for the PRZM scenarios in North Carolina and Mississippi is 6% while the slope at the Texas and California sites is 2.5%. The larger slope leads to a greater value for the erosion equation topographic factor and hence greater erosion potential. Furthermore, an analysis of the PRZM output files indicated that the sites in North Carolina and Mississippi received greater rainfall than the sites located in California and Texas, resulting in greater erosion and runoff flux at these two sites. These factors lead to greater cypermethrin loadings into the model environmental pond employed in EXAMS, and hence higher EECs.

Pecans There is only one QCed PRZM scenario for pecans ( Georgia). The representative soil is a Greenville fine sandy loam of hydrologic Group C. The harvest date of pecans in Georgia usually begins in October, but pecans may be harvested any time after the shuck opens ( Georgia  40 Pecan Commission 2004). In the southeastern United States, September is the most critical month of the pecan growing season, because most of the kernel develops during this month. Late season pressure from aphids and other pests can reduce yields. It is recommended that pyrethroid insecticides not be used until late in the season, in order to avoid resistance and to avoid killing beneficial insects, such as lady beetles and lacewings which naturally suppress mites and aphids early in the season. The surface water, pore water and sediment EECs for the pecan scenario are shown in Table 8. Cypermethrin is applied to pecans by ground methods only. The level of spray drift for pecans was obtained from AgDRIFT ® , at the Tier 1 level, for airblast applications of dense trees, which is also representative of pecans. The level of spray drift obtained with a buffer zone of 25 ft ( imposed in the label) was multiplied by 3 to obtain an approximation of the 90th percentile of the deposition value ( according to current guidelines). The level of spray drift was 0.022 or 2.2%. It was used in this assessment. This level of spray drift is considered typical for airblast applications. Since pecans can be very tall trees, the level of spray drift was also explored with sparse and young, which is a more conservative scenario. The level of spray drift was 0.045 or 4.5%.