UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON D. C., 20460 OFFICE OF PREVENTION, PESTICIDES AND TOXIC SUBSTANCES February 16, 2006 PC Code 069001; Case No. 2580 DP Barcode: D324663 MEMORANDUM SUBJECT: Revised Pyrethrins RED Chapter After Additional 60 Day Comment Period, Phase 5 FROM: Miachel Rexrode, Ph. D., Senior Aquatic Biologist José Luis Meléndez, Chemist Environmental Risk Branch V Environmental Fate and Effects Division ( 7507C)

THROUGH: Jean Holmes, DVM, Acting Chief Environmental Risk Branch V Environmental Fate and Effects Division ( 7507C)

TO: Cathryn O'Connell, Risk Manager Reviewer Tom Myers, Review Manager # 52 Special Review and Reregistration Division ( 7508C)

This memo summarizes the revised Environmental Fate and Effects Division's ( EFED) screening level Environmental Risk Assessment for the Reregistration Eligibility Decision of Pyrethrins. The Pyrethrins are a broad spectrum insecticide used in four major sectors: agricultural settings, commercial/ industrial/ institutional/ food & non food/ mosquito abatement, domestic home and garden, and pet care. Pyrethrins are a mixture of naturally occurring insecticides derived from the flowers of Chrysanthemum cinerariaefolium and Chrysanthemum cineum. The six individual pyrethrins are pyrethrin 1, pyrethrin 2, cinerin 1, cinerin 2, jasmolin 1, and jasmolin 2. The technical grade active ingredient ( FEK 99) is commonly referred to as pyrethrum extract, which is the sum of Pyrethrins I ( the esters of chrysanthemic acid  pyrethrin 1, cinerin 2 and jasmolin 1) and Pyrethrins II ( the esters of pyrethric acid  pyrethrin 2, cinerin 2, and jasmolin 2), also called " the pyrethrins", and this mixture constitutes 45 to 55% of pyrethrum extract. The product pyrenone crop spray, a formulation that contains pyrethrins, piperonyl butoxide and inert ingredients, was used as a test material in many of the ecological effects laboratory studies. There are many other formulation types, such as aerosol, combustible coil, dust, emulsifiable concentrate, ready to use liquid, shampoo, and wettable powder. All six pyrethrins have the same backbone molecular structure with different substituents at two sites. Since all the structures at the two sites are similar, they are expected to have similar environmental fate properties. Risk to Aquatic and Terrestrial Organisms The Agency evaluated potential pyrethrin exposure to aquatic and terrestrial organisms by considering maximum and typical application rates. The conclusions from this risk assessment are as follows:

Agricultural Uses:

Model generated exposure values suggests that maximum rates can result in acute risk to fish and aquatic invertebrates ( freshwater and estuarine/ marine) with triggers that included restrictive use and endangered species concern ( although estuarine/ marine endangered invertebrate was triggered, EFED realizes that at this time there are no listed species under this category). Evaluating chronic risk from this exposure scenario showed that LOC triggers were exceeded for estuarine/ marine invertebrates, while fish ( freshwater and estuarine/ marine) and freshwater invertebrates may not be at chronic risk from pyrethrin exposure in the water column.

Typical application rate appears to have the potential to reduce risk to aquatic systems. Evaluation of four crop scenarios using the TGAI ( ID potatoes, PA tomatoes, CA onions, OR snap beans) suggests that LOCs for freshwater and estuarine/ marine fish and invertebrates should not be exceeded if typical application rate is used.

The Agency also assessed the maximum and typical rates for a pyrethrin formulation with PBO but only evaluated acute exposure to aquatic organisms. The calculated EECs show that acute risk from the maximum formulation rate appeared to be higher than risk calculated only from the TGAI. This evaluation showed that acute risk from the formulation was about 2 7X greater for freshwater and estuarine/ marine fish and about 10X greater for estuarine/ marine invertebrates. However, the typical formulation rate appears to reduce the risk ( freshwater and estuarine/ marine fish and freshwater invertebrates), but this reduction in exposure still presents the potential for acute high, acute restrictive, and chronic risk to estuarine/ marine invertebrates species.

Mosquito Abatement:

The maximum rate showed that there did not appear to be the potential for acute risk to freshwater fish and invertebrates or esrtuarine/ marine fish but there was the potential for acute LOCs being exceeded for estuarine/ marine invertebrates. However, this risk to estuarine/ marine invertebrates appeared to be eliminated if the boom height is set at 150 ft and the droplet size at 40 um.

The Agency also evaluated the typical rate and found that potential acute risk to estuarine/ marine invertebrates could be eliminated with a boom height of 75ft and a 50 um droplet size.

Down the Drain The Agency evaluated the pharmacological uses of pyrethrin in a Down the Drain model and found that aquatic LOCs were not exceeded for freshwater or estuarine/ marine organisms.

Risk to Terrestrial Organisms In this screening level risk assessment, the Agency did not find acute and chronic risks to listed or non listed mammalian and avian species. Although the Agency does not conduct a quantitative risk assessment for beneficial insects, acute toxicity studies with honey bees show that pyrethrins are highly toxic, both on a contact basis, and an acute oral basis. This also suggests that pyrethrins are toxic to nontarget beneficial insects, as well as listed insect species.

Risks to Endangered Species The acute level of concern ( LOC) is exceeded for endangered and/ or threatened species of freshwater fish and invertebrates that live in the water column and are associated with the agricultural uses of pyrethrins. Based on a probit slope analysis to calculate the chance of an individual event corresponding to the freshwater fish, the estimated individual mortality associated with the calculated RQ values ( 0.05 to 0.54) range from 1 in 3.34 x 1014 to 1 in 4.17 x 108 . For the freshwater invertebrate, the estimated individual mortality associated with the calculated RQ values ( 0.05  0.24) range from 1 in 1.0 x 1016 to 1 in 8.44 x 109.

The acute level of concern ( LOC) is exceeded for endangered and/ or threatened species of estuarine/ marine fish and invertebrates that live in the water column and are associated with the agricultural and mosquito abatement uses of pyrethrins. For estuarine/ marine fish, the estimated individual mortality associated with the calculated RQ values ( 0.05 to 0.17) is 1.0 X 1016. For estuarine/ marine invertebrates for agriculture and mosquito abatement uses, the probit slope analysis was completed for both active ingredient and formulated product. Based on the default slope estimate of 4.5, the corresponding chance of individual mortality for estuarine/ marine invertebrates following exposure to the formulation is 1 in 4.17 x 108; and based on the slope estimate of 4.1, the corresponding chance of individual mortality for estuarine/ marine invertebrates following exposure to the technical grade active ingredient is 1 in 2.08 x 107.

The listed species acute LOC is exceeded for sediment dwelling estuarine/ marine invertebrates that live near the agricultural areas. However, there are no listed estuarine/ marine invertebrates, so this risk concerns only applies to non listed species.

The Agency is also concerned for endangered terrestrial invertebrates such as beneficial insects, as well as listed species.

Outstanding Data Requirements and Data Gaps Environmental Fate: The environmental fate database for the pyrethrins was completed with a representative pyrethrin: pyrethrin 1. However, the toxicity testing was done with the mixture of compounds. As indicated earlier, pyrethrin consists of a mixture of six compounds that are structurally related, which have the same backbone molecular structure, but different substituents at two key sites of the molecule. These different substituents are not expected to substantially change the fate and transport properties of the chemicals. The general chemistry of the molecule is dictated by the ester link located near the center of the structure. The environmental fate database is substantially complete, but it consists mostly of supplemental studies. At this time, the database has been considered sufficient for a Tier I assessment; however, should additional refinements be needed, additional data may be required.

Ecological Effects: The ecological effects toxicity database is complete and adequate to conduct a Tier I risk assessment. Most of the studies were classified as Core and were conducted with the technical grade active ingredient ( FEK 99) and a formulated product ( pyrenone crop spray). Further ecological effects data are needed on pyrethrin because of its phytotoxic effects on plants and potential risk to benthic organisms.

There were no chronic studies with the technical grade active ingredient or the formulation for estuarine / marine invertebrates or fish. Pyrethrins are acutely toxic to estuarine / marine invertebrates and fish at levels below 1ppm ( EC 50 / LC 50 s are less than 1 ppm) and the chemical may be applied directly to water for mosquito abatement use. These factors trigger a data requirement for submission of chronic studies with estuarine / marine fish and invertebrates. However, using the acute to chronic ratio estimation method, it does appear that chronic risk will be a concern to invertebrates in estuarine/ marine environments ( water column and sediment). Under guideline § 72 4 ( a) and ( b), EFED is requesting submission of a life cycle study with an estuarine/ marine invertebrate ( e. g., mysid shrimp) and fish early life stage study with an estuarine/ marine fish ( e. g., sheepshead minnow).

No data were submitted to evaluate the effects of pyrethrin exposure to terrestrial or aquatic. However the Agency does not consider pyrethrin or the other pyrethroids as being phytotoxic for the following reasons: 1) the compound is used as a spray on agricultural crops with no phytotoxic effects; 2) the neural toxic mode of action precludes phtotoxic concerns; 3) the Agency is not aware of any incidents involving plants and cypyrethrin alone. The Agency is not requiring plant toxicity data at this time.

Since pyrethrins can bind to particulate and sediment and are highly toxic to aquatic invertebrates, EFED has a concern for acute and chronic risk to benthic organisms. Therefore, EFED is requesting that a whole sediment acute test with the freshwater organism, Chironomus ripirians ( Guideline number 850.1735) and the marine water organism, Leptocheirus plumulosus ( Guideline number 850.1740) be submitted to fully evaluate potential risk to benthic organisms.

Additionally, no chronic avian toxicity data were submitted, but the Agency is not requesting these data at this time.

Uncertainties: There is uncertainty with respect to the environmental fate studies that were deemed supplemental. Some problems were found in these studies and there is uncertainty associated with the use of these end points. Furthermore, the terrestrial field dissipation study was waived and the results of the laboratory study could not be corroborated with real life situations in the field. The fact that a single chemical ( pyrethrin 1) was chosen as a surrogate compound or representative for the other six pyrethrins may be a source of some uncertainty. The uncertainties associated with pyrethrin exposure in the environment are mainly focused on the possible impact to aquatic ecosystems. Since pyrethrin is highly toxic to fish and invertebrates, there is a question of sustaining functional diversity in a system that has been exposed to toxic drift or runoff. Proponents for the use of pyrethrin in agricultural settings argue that invertebrates are resilient and affected populations will reintroduce themselves in time. EFED believes that the degree of reintroduction of species that are keystone to an ecosystem is uncertain, and the impact of diminished invertebrate diversity on ecosystem integrity has not yet been adequately evaluated. In addition to a direct impact on invertebrate diversity, EFED is also concerned with the indirect effects of food chain alterations that could influence fish populations that are dependent upon aquatic invertebrates Although pyrethrins bind and accumulate in sediments, EFED did not have sediment monitoring or toxicity data to adequately evaluate this potential risk to benthic organisms. However, this uncertainty was addressed by using model derived exposure values for sediment and pore water. The estimated environmental concentrations ( EECs) that were used to calculate RQ values were the pore water output of the PRZM/ EXAMS model, while the effects data were standard worst case water column test ( e. g., EC50 daphnia). Although the sediment systems is assumed to adsorbed a large portion of the chemical over a short period of time, EFED chose to use the resulting concentrations in pore water that are at equilibrium with sediment loads for the EECs. However, EFED also realizes that there is uncertainty regarding the amount of sorbed pesticide that may contribute to the toxicity of organisms that feed directly on the sediment itself. Therefore, the assumed risk to benthic organisms has the potential to be greater than originally surmised.

EFED Label Recommendations Manufacturing Use: 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. Do not discharge effluent containing this product to sewer systems without previously notifying the local sewage treatment plant authority. For guidance contact your State Water Board or Regional Office of the EPA. Do not contaminate water when disposing of equipment washwaters

End Use Products: This product is toxic to fish and aquatic invertebrates. This product may contaminate water through drift of spray in wind or via runoff events. Use care when applying in areas adjacent to any body of water. 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 target area. Do not contaminate water when disposing of equipment wash waters or rinsate.

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 data base 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 refinements in spray drift management practices to reduce off target drift and risks associated with aerial as well as other application types where appropriate.

The results of this risk assessment indicate that for many of the crop scenarios the level of spray drift is an important component of the concentrations observed in adjacent bodies of water. Since pyrethrin was found to be highly toxic to various aquatic animals, the risk managers have to pay special attention to the labels statements placed to the pyrethrin products.

For mosquito abatement, application directions in the label are insufficient to accurately estimate aquatic exposures that result from application of pyrethrin for controlling mosquitoes. Limitations ( as opposed to recommendations) on product labels for key parameters such as droplet size, wind speed, release height, application interval, and number of applications allowed per year are not specified. This exposure assessment represents the water concentrations expected from a typical, low level aerial application. Concentrations resulting from actual application of pyrethrin for mosquito control could be significantly higher than modeled concentrations if applicators used different application parameters. Tables A and B show the Ecological Effects and Environmental Fate Data Requirements for Pyrethrin Table A. Ecological Effects Data Requirements for Pyrethrin.

Guideline number Data requirement Are further data needed? Study ID # Study classificationa 71 1 Avian oral LD50 No 420109 01 Core 71 2 Avian dietary LC50 No 419688 01 419688 02 Core 71 4 Avian reproduction No No data No data 72 1 Freshwater fish LC50 No 430823 01 430823 02 430823 03 430823 04 Core Core Core Core Core Core 72 2 Freshwater invertebrate acute LC50 No 430823 05 430823 06 Core Core 72 3( a) Estuarine/ marine fish LC50 No 430823 07 430823 08 Core Core 72 3( b) Estuarine/ marine mollusk LC50 No 430823 09 430823 10 Core Core 72 3( c) Estuarine/ marine shrimp LC50 No 430823 11 430823 12 Core Core 72 4( a) Freshwater fish early life stage No 432527 01 Core 72 4( a) Estuarine/ marine fish early lifestage Yes No data No data 72 4( b) Freshwater Aquatic invertebrate life cycle No 432527 02 Core 72 4( b) Estuarine/ marine invertebrate lifecycle Yes No data No data 72 5 Freshwater fish full life cycle No No data No data 122 1( a) Seed germination/ seedling emergence ( Tier I) No No data No data 122 1( b) Vegetative vigor ( Tier I) No No data No data 122 2 Aquatic algal growth No No data No data 123 2 Duckweed ( Lemna gibba) No No data No data Table A. Ecological Effects Data Requirements for Pyrethrin.

Guideline number Data requirement Are further data needed? Study ID # Study classificationa 123 1( a) Seed germination/ seedling emergence ( Tier II) No No data No data 123 1( b) Vegetative vigor ( Tier II) No No data No data 123 2 Aquatic plant growth No No data No data 144 1 Honey bee acute contact LD50 No 419688 03 Atkins et al., 1967 Stevenson, 1968 Stevenson, 1978 Core Supplemental Supplemental Supplemental 141 2 Honey bee residue on foliage No N/ A N/ A 850.1735 Whole sediment acute, freshwater Yes N/ A N/ A 850.174 Whole sediment acute, marine Yes N/ A N/ A aCore: study satisfies guideline; Supplemental: study is scientifically sound, but does not satisfy guideline Table B. Environmental Fate Data Requirements for Pyrethrin.

Guideline # Data Requirement Are further data needed? MRID #' s Study Classification 161 1 835.2120 Hydrolysis no 43188201, 43567502 Core 161 2 835.2240 Photodegradation in Water no 43096601, 43567601 Supplemental 161 3 835.2410 Photodegradation on Soil no 43096602 Supplemental 161 4 835.2370 Photodegradation in Air no NA Waived 162 1 835.4100 Aerobic Soil Metabolism no 43499803 Supplemental 162 2 835.4200 Anaerobic Soil Metabolism no 43499802 Supplemental 162 3 835.4400 Anaerobic Aquatic Metabolism no NA Not Required 162 4 835.4300 Aerobic Aquatic Metabolism no 43499801 Supplemental 163 1 835.1240 835.1230 Leaching Adsorption/ Des orption no 43096603 Core 163 2 835.1410 Laboratory Volatility no 43096604 Core 163 3 835.8100 Field Volatility no NA Waived 164 1 835.6100 Terrestrial Field Dissipation no 42745501 Waived1 164 2 835.6200 Aquatic Field Dissipation no 43818501 Waived1 164 3 835.6300 Forestry Dissipation no NA Not Required 165 4 850.1730 Accumulation in Fish no 43302301, 43884102 Core Table B. Environmental Fate Data Requirements for Pyrethrin.

Guideline # Data Requirement Are further data needed? MRID #' s Study Classification 165 5 850.1950 Accumulation   Aquatic Nontarget Organisms no NA Waived 166 1 835.7100 Groundwater   Small Prospective no NA Waived1 201 1 840.1100 Droplet Size Spectrum no NA Not Required2 202 1 840.1200 Spray Drift Field Evaluation no NA Not Required2 1. Waived based on its low persistence and mobility and other environmental fate characteristics. 2. The registrant is a member of the Spray Drift Task Force and the data requirement is covered by the data produced by this coalition. Preliminary Science Assessment for the Reregistration Eligibility Decision ( RED) Document for Case 2580: PYRETHRIN Prepared by: Jerry L. Ellis, Jr., Biologist José L. Meléndez, Chemist Miachel Rexrode, Ph. D., Fishery Biologist 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: Jean Holmes, RAPL Mah T. Shamim, Ph. D., Chief Environmental Risk Branch V  1 Table of Contents Table of Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 I. Executive Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 A. Risks to Non target Organisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 B. Nature of Chemical Stressor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 C. Conclusions  Exposure Characterization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 D. Conclusions  Effects Characterization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 II. Problem Formulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 A. Stressor Source and Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1. Physical Chemical and Fate and Transport Properties . . . . . . . . . . . . . . . . . . 6 2. Mode of Action . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3. Overview of Pesticide Usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 B. Receptors: Ecological Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 C. Assessment Endpoints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 D. Conceptual Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 1. Risk Hypotheses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2. Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 E. Analysis Plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 1. Develop Assessment Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 2. Identification of Data Gaps and Methods for Conducting Assessment . . . . . 15 3. Measures to Evaluate Risk Hypotheses and Conceptual Model . . . . . . . . . . 16 a. Measures of Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 b. Measures of Effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 III. Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 A. Use Characterization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 B. Exposure Characterization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 1. Environmental Fate and Transport Characterization . . . . . . . . . . . . . . . . . . . 23 2. Measures of Aquatic Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 a. Aquatic Exposure Modeling for Agricultural Crops . . . . . . . . . . . . . 33 b. Aquatic Exposure Modeling for Mosquito Abatement . . . . . . . . . . . 45 c. Aquatic Exposure " Down the Drain" Assessment . . . . . . . . . . . . . . 57 d. Aquatic Exposure Monitoring ( Field Data) . . . . . . . . . . . . . . . . . . . . 59 3. Measures of Terrestrial Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59 4. Non Target Plant Exposures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 C. Ecological Effects Characterization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 1. Aquatic Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 a. Aquatic Animals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 b. Aquatic Plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 2. Terrestrial Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68  2 a. Terrestrial Animals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 b. Terrestrial Plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 IV. Risk Characterization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 A. Risk Estimation  Integration of Exposure and Effects Data . . . . . . . . . . . . . . . . . . 60 1. Non target Aquatic Animals and Plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 a. Fish and Aquatic Invertebrates  Agricultural Uses and Mosquito Abatement Uses and Down the Drain . . . . . . . . . . . . . . . . . . . . 70 b. Sediment Organisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 2. Non target Terrestrial Animals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 a. Mammals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 b. Birds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 c. Insects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 3. Non target Terrestrial and Semi aquatic Plants . . . . . . . . . . . . . . . . . . . . . . 91 B. Risk Description  Interpretation of Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 1. Estimating Risks to Aquatic Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92 2. Estimating Risks to Terrestrial Organisms ( Mammals and Birds) . . . . . . . . . 95 3. Review of Incident Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 a. Incidents Involving Aquatic Organisms . . . . . . . . . . . . . . . . . . . . . . . 97 b. Incidents Involving Terrestrial Organisms . . . . . . . . . . . . . . . . . . . . . 97 4. Endocrine Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 5. Threatened and Endangered Species Concerns . . . . . . . . . . . . . . . . . . . . . . . 99 a. Taxonomic Groups Potentially at Risk . . . . . . . . . . . . . . . . . . . . . . 100 b. Action Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 c. Indirect Effects Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 d. Critical Habitat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 C. Description of Assumptions, Uncertainties, Strengths, and Limitations . . . . . . . . . 103 1. Assumptions and Limitations Related to Exposure For All Taxa . . . . . . . . 103 2. Assumptions and Limitations Related to Exposure For Aquatic Species . . 103 3. Assumptions and Limitations Related to Exposure For Terrestrial Species . 103 4. Assumptions and Limitations Related to Effects Assessment . . . . . . . . . . . 105 5. Assumptions Associated With the Acute LOCs . . . . . . . . . . . . . . . . . . . . . 106 V. Literature Cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 ACKNOWLEDGMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 VI. Appendices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Appendices Page Number APPENDIX A. Environmental Fate Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 APPENDIX B. Aquatic Exposure Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 APPENDIX C. T REX Model and Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134 APPENDIX D. TerrPlant Model and Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137 APPENDIX E. Ecological Effects Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138 APPENDIX F. Risk Quotient Method and Levels of Concern . . . . . . . . . . . . . . . . . . 151  3 APPENDIX G. Literature Cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153 APPENDIX H. Summary of Endangered/ Threatened Species . . . . . . . . . . . . . . . . . . 154 APPENDIX J. Data Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175 APPENDIX K. Ecotoxicity and Environmental Fate Bibliography . . . . . . . . . . . . . . . 182 APPENDIX L. Mosquito Abatement Modeling Using AGDISP v. 8.07 . . . . . . . . . . 189 APPENDIX N. T REX Output File for Typical Application Rate.......................... 388 APPENDIX O. AgDRIFT ® and PRZM/ EXAMS Input and Output Files for Drift and Buffer Zones Analysis.. ........................................................ 392 APPENDIX P. Equilibrium Partitioning Model and Risk Estimation for Benthic Organisms........................... ........................................................ 448 APPENDIX Q. EPIWIN Output Files and " Down the Drain" Output Files..................................... ........................................................ 452  1 I. Executive Summary A. Risks to Non target Organisms The Agency's screening level risk assessment for pyrethrin, is focused on maximum and typical application rates for agricultural, and mosquito abatement uses. Consideration was also given for pharmacological uses in a " Down the Drain" scenario.

For terrestrial organisms, the level of concern was not exceeded for acute or chronic risk to listed or non listed mammals or birds. Although EFED does not conduct risk assessments on non target terrestrial insects, toxicity studies show that pyrethrins are toxic to the honey bee on an acute contact and oral basis.

Risk to Aquatic Organisms ( Maximum and Typical Application Rates)

° Agricultural Uses: Maximum application of pyrethrin to various crops can result acute and chronic risks to aquatic organisms: freshwater and estuarine/ marine fish and invertebrates ( including sediment dwelling organisms). This screening level assessment shows the potential for exceeding LOCs for acute risk, restricted use, and endangered species, as well as chronic risk.

° The greatest risk ( i. e., highest exceedance of LOCs) among aquatic receptors evaluated was for aquatic invertebrates ( both freshwater and estuarine/ marine).

° Typical application rates appear to reduce risk to aquatic organisms. The LOCs for freshwater and estuarine/ marine fish and invertebrates should not be exceeded under this exposure scenario.

Mosquito abatement: In general maximum application showed that the major acute risk concern was for estuarine/ marine invertebrates. However, the acute risk to estuarine/ marine invertebrates appears to be eliminated if boom height is set at 150ft and the droplet size set at 40 um. Acute risk to freshwater fish and invertebrates or estuarine/ marine fish does not appear to be an ecological concern from mosquito abatement use ( maximum or typical application rate).

° The typical application rate reduced residue exposure to aquatic areas by about 20  50%. The risk to the most vulnerable aquatic organisms ( estuarine/ marine invertebrates) could be eliminated if boom height is set at a minimum boom height of 75ft and a corresponding droplet size of 50 um.

° Down the Drain: The Agency evaluated the possible exposure to aquatic systems from the pharmacological uses of pyrethrin. The Down the Drain assessment ( various processing scenarios of wastewater through treatment plants) showed that expected pyrethrin residues should not exceed the LOCs for freshwater and estuarine/ marine fish or invertebrates.  2 ° Pyrethrins have generally effective " knockdown" potential but their toxicity is usually enhanced through the use of synergist like piperonyl butoxide ( PBO). In order to be inclusive, EFED has addressed potential aquatic risk from the PBO formulation. Risk quotients were calculated using the technical grade active ingredient for the agricultural uses and formulated product ( PYRENONE ®

Crop Spray, EPA Registration No. 432 1033 ) for the mosquito abatement uses. However, EFED also calculated potential risk from PBO formulation use on agricultural crops, which showed that acute risk to freshwater and estuarine/ marine fish and invertebrates could increase up to 10X for all crop scenarios. Piperonyl butoxide, as a synergist, is used to enhance the pesticidal properties of the active ingredients by competitive inhibition of detoxifying enzymes ( cytochrome P450).

° Acute and chronic risk estimates for birds and small mammals associated with the agricultural uses The acute and chronic levels of concern ( LOCs) were not exceeded for listed or non listed mammals or birds.

° Toxicity and risk concerns about degradates of pyrethrins Although toxicity studies on the degradates were not provided, an evaluation of the structures indicate that they are the result of the rupture of the ester bridge of the parent, resulting in a carboxylic acid ( chrysanthemic acid), and an alcohol ( that subsequently can be degraded to an acid as well). The resulting molecules have lost their pyrethroid toxicological activity, therefore, in this assessment, they were not considered of concern. Furthermore, the available data indicated that chrysanthemic acid was formed at low levels except under hydrolytic conditions at pH 9.

B. Nature of Chemical Stressor Pyrethrin is a mixture of naturally occurring insecticides derived from the flowers of Chrysanthemum cinerariaefolium and Chrysanthemum cineum. The six individual pyrethrins are pyrethrin 1, pyrethrin 2, cinerin 1, cinerin 2, jasmolin 1, and jasmolin 2. These compounds are esters of a carboxylic acid and a cyclopentenolone ( chrysanthemic acid and pyrethric acid) and three cyclopentenolones ( pyrethrolone, cinerolone, and jasmolone). The technical grade active ingredient ( FEK 99) is commonly referred to as pyrethrum extract, which is the sum of Pyrethrins I ( the esters of chrysanthemic acid  pyrethrin 1, cinerin 1, and jasmolin 1) and Pyrethrins II ( the esters of pyrethric acid  pyrethrin 2, cinerin 2, and jasmolin 2), also called " the pyrethrins", and this mixture constitutes 45 to 55% of pyrethrum extract. In the US, the pyrethrum extract is standardized as 45 55% w/ w total pyrethrins, as indicated earlier. The typical proportion of Pyrethrins I to II is 1: 14, while the ratio of pyrethrin: cynerins: jasmolins is 71: 21: 7 ( Tomlin 1997).

Pyrethrins are used as insecticides in agriculture, pet care, domestic home and garden, and commercial/ industrial/ institutional settings, and for mosquito abatement. The final formulation and application method depends upon the market sector for which pyrethrins are being used. Pyrethrins are non systemic insecticides that work by physical contact to the insect or by ingestion, and they have a slight repellent effect. The toxicity of pyrethrins is due to their action on the sodium channel  3 of nerve cells. The formulated pyrethrins pesticide mixture usually contain a synergist, such as piperonyl butoxide, piperonyl sulfoxide, or sesamex. These compounds enhance the insecticidal activity of the pesticide by preventing some enzymes in the organism from breaking down the pyrethrins.

According to the Master Label there are 19 formulation types and 45 application equipment types for pyrethrin products for agricultural purposes. There are 17 formulation types for pet care, 16 formulation types for domestic/ home and garden, and 20 formulation types for commercial/ industrial/ institutional settings. Equipment types for agricultural crops include such examples as fixed wing aircraft, and helicopter.

Since it is difficult to evaluate the environmental fate properties of a mixture, pyrethrin 1 was selected as a surrogate for all the pyrethrins to generate the environmental fate data. As indicated earlier, the six compounds have similar molecular structure, but with different substituents at two sites. The individual chemical structures of all six pyrethrins are shown in Figure 1 of Appendix A. Since the chemicals are structurally very similar, they are expected to have similar environmental fate properties. However, the toxicity testing was done with the mixture of compounds. FEK 99 was used to estimate risk to non target organisms that are associated with the agricultural crop scenarios. Toxicity data on the formulated product, PYRENONE ® Crop Spray ( EPA Registration No. 432 1033), were used to evaluate risk to non target organisms in the scenarios that involve direct application to water ( such as the mosquito abatement use).

C. Conclusions  Exposure Characterization Based on the data obtained with pyrethrin 1, which was chosen as a surrogate for all the six pyrethrins, the following conclusions were derived for these compounds: Pyrethrins are considered to be persistent in certain environments and short lived in other environments. They are stable to hydrolysis under neutral and acidic conditions ( pH 5 & 7) but quickly photodegrade in shallow clear water. Pyrethrins adsorb strongly to soil surfaces and are generally considered immobile in soils ( K oc range 12,400 to 37840); therefore, the potential to leach into groundwater is considered low. They could reach surface water via spray drift or runoff events accompanied by erosion where they quickly adsorb to suspended solids in the water column, and partition into the sediment. Sediments are likely to be an environmental sink for any non degraded pyrethrins since they appear to persist under anaerobic conditions. Biodegradation under aerobic conditions occurs fairly rapidly with half lives of a few days Hydrolysis under alkaline conditions is also an important route of dissipation for pyrethrins in water ( half life at pH 9 14 17 hours); however, this reaction appears to be relatively slow under neutral or acidic conditions. Volatilization is not expected to be an important transport process since pyrethrins tend to have relatively low vapor pressure and Henry's Law constant.

An evaluation of the structures of the degradation products of pyrethrins, indicate that they are the result of the rupture of the ester bridge of the parent, resulting in a carboxylic acid ( chrysanthemic acid), and an alcohol ( that could subsequently be degraded to an acid as well). The available data indicated that chrysanthemic acid was formed in small amounts except under hydrolytic conditions at pH 9 and the degradation products were deemed of low concern. In the majority of the studies  4 multiple degradates at very low concentrations were observed, but not characterized. The only other significant isomer observed in the aqueous photolysis study was designated ( E) isomer of pyrethrin 1.

The bioconcentration factor for 14C residues in edible tissues of fish was found to be 127X. The predominant species present in the tissues were parent pyrethrin and chrysanthemic acid.

The effect of spray drift, and the use of buffer zones in reducing exposure to bodies of water adjacent to treated areas was investigated. The first step was to determine if spray drift was the predominant mode for transport of pyrethrins to surface water. Four crop scenarios were selected for this evaluation which represented a wide range of geographical locations within the continental US. PRZM/ EXAMS model was run with the spray drift set to 0% and the results were compared to the runs where the spray drift was set at 5%. For ID potato and CA grapes, the percent of the peak EEC attributable to spray drift was very high ( 88.5 and 94.5%, respectively), for FL citrus and GA peaches, the percent of the peak EEC related to spray drift appeared to be more moderate ( 44.9 and 47.6%, respectively). The next step was the buffer zone analysis, where the choice of crop scenarios was narrowed down to GA peaches and ID potatoes. AgDRIFT ® model was used to run a " high end" ( conservative) and a " low end" ( best case) drift scenario. Two sets of spray drift values were generated: using a spray volume of 10 gal./ A for orchards and 2 gal./ A for other crops, each with buffer zones of 0, 50, 100, 150 ft. The resulting spray drift values were used as inputs in PRZM/ EXAMS for the two crop scenarios. As expected, the low end ( best case) drift scenario resulted in substantially lower EECs. Using the endpoint for the most sensitive species, RQs were calculated for the GA peaches which also represented orchards. The magnitude of the exceedance for the high end drift scenario with 50 ft. buffer zone was about 3.6 times higher compared to the low end drift scenario with 150 ft. buffer zone. For the ID potatoes ( representative of other crops), the magnitude of the exceedance of the RQs was about 25 times higher for the high end scenario with a 50 ft. buffer zone compared with the low end drift scenario with a 150 ft. buffer zone. The results of the ground application and the low end drift scenario with a 150 ft. buffer zone yielded RQs of similar order of magnitude.

For the mosquito adulticide use, pyrethrins are applied as very small droplets to create a mist which remains suspended over the field to more efficiently target the mosquitoes. Therefore, they are susceptible to drift towards an adjacent body of water. To determine the deposition of the pesticide to adjacent water bodies, the computer model AGDISP [ AGricultural DISPersal ( computer) model ( AGDISP)] was used. The results from AGDISP were subsequently used as input parameters in PRZM/ EXAMS to model the degradation and partitioning in sediment for water bodies of various depths ( 6 in, 1 ft., 1 m, and 2 m) that may be exposed to drift from the mosquito adulticide. It was found that the shallow pond shows the lower concentration, possibly due to partitioning of the chemical with the sediment. Variables that have a high impact on the aquatic EECs are the boom height ( the higher the boom height, the levels of deposition), the droplet size ( the smaller droplets, the lower the levels of deposition), the wind speed ( too low wind speeds favor higher deposition), and obviously the application rate ( it appears that for many of the products the maximum application rate is lower than the maximum application rate stated in the Master Label [ 0.0025 lb a. i./ A vs 0.008 lb a. i./ A]). The interval between applications and the number of applications are expected to have  5 also an effect on the EECs ( similar to an agricultural application).

D. Conclusions  Effects Characterization The ecological effects laboratory studies were conducted with the technical grade active ingredient ( FEK 99) for agricultural uses and the formulated product, PYRENONE ® Crop Spray ( EPA Registration No. 432 1033) for mosquito abatement uses.

For aquatic species, pyrethrins are shown to be very highly toxic on an acute basis to both freshwater and estuarine/ marine fish and invertebrates ( based on the TGAI and formulation). Acute studies, conducted with the formulation, showed slightly more toxic endpoints compared to studies with the TGAI. Chronic toxicity studies ( using the TGAI) with freshwater organisms show that the most sensitive endpoint for fish is growth ( length and dry weight) and reproduction for invertebrates. The chronic NOAEC for freshwater fish and invertebrates was 1.9 and 0.86 : g/ L, respectively. No data were submitted to evaluate the chronic risk to estuarine/ marine fish or invertebrates. However, the acute to chronic ratio method was used to estimate NOAECs for estuarine/ marine fish ( NOAEC estimate of 5.9 ppb) and invertebrates ( NOAEC estimate of 0.10 ppb). Since pyrethrins tend to partition into the sediment compartment, toxicity data for the sediment dwelling organisms are needed.

The TGAI was the test substance used in the bird and laboratory rat toxicity tests. Pyrethrins appear to be practically non toxic to avian species on an acute oral and dietary basis. Chronic avian risk was extrapolated by using surrogate data ( pyrethrin Bobwhite quail NOAEC = 125 mg/ kg/ diet) and suggest minimal chronic risk to avian species. Toxicity studies with rats suggest that pyrethrins can be categorized as slightly toxic to small mammals on an acute oral basis. Acute toxicity studies with honey bees show that pyrethrins are highly toxic on both a contact and an oral basis.

Although there were no aquatic or terrestrial plant data submitted to the Agency does not consider pyrethrin or the other pyrethroids as being phytotoxic for the following reasons: 1) the compound is used as a spray on agricultural crops with no phytotoxic effects; 2) the neural toxic mode of action precludes phtotoxic concerns; 3) the Agency is not aware of any incidents involving plants and pyrethrin alone ( incidents that were reported for terrestrial ornamental plants were inconclusive and suggest that inerts in the formulation or other circumstances related to application may have caused the problem. The Agency is not aware of any reported incidents of pyrethrin phytotoxicity on agricultural crops).

II. Problem Formulation A. Stressor Source and Distribution Pyrethrins are nonvolatile hydrocarbons produced by certain species of the chrysanthemum plant ( genus Chrysanthemum) and have been used as insecticides since the1800' s. The plant species with the most toxic content that can be efficiently used for industrial purposes are C. cinerariaefolium and C. coccineum which are grown mainly in Australia and East Africa. The active insecticidal  6 components are collectively known as pyrethrins and consist of six esters. Although the ground flowers can be used as a dust, a more concentrated and efficacious pyrethrin product is possible through solvent extraction. Pyrethrin containing dusts and extracts usually have an active ingredient content of about 30%. However, after filtration and reextraction the concentration can reach 90 100% ( Matsumura, 1985). These compounds are contact poisons which can quickly penetrate the neural system. Although the pyrethrins have an effective " knockdown" action ( induction of temporary paralysis) they do not necessarily have high killing properties by themselves. These compounds are moderately persistent under certain environmental conditions but are quickly metabolized under other conditions such as in the presence of sunlight ( photolysis). However, in order to delay the metabolic action ( inhibition of microsomal enzymes) so that a lethal dose is assured, organophosphates, carbamates, or synergists ( such as piperonyl butoxide) may be added to the pyrethrins ( Ecobichon and Donald, 1991). Pyrethrin compounds have been used primarily to control human lice, mosquitoes, cockroaches, beetles, and flies. Some pyrethrin compounds used to control insects in horticultural crops, are only 0.3% to 0.5% pyrethrins, and are used at rates of up to 50 lb/ A. Other pyrethrin compounds may be used in grain storage and in poultry pens and on dogs and cats to control lice and fleas.

Natural pyrethrins have their limitations for use on a large scale for agricultural purposes because of their cost and instability in sunlight. Therefore, in recent decades, many synthetic pyrethrin like compounds were developed and are referred to as synthetic pyrethroids. These compounds are stable in sunlight ( lower reactivity of side chains) and are generally effective against most agricultural insect pests when used at the very low rates. The synthetic pyrethroids have evolved over a period of time and can be divided into four generations.

The formulated products of pyrethrin usually contain a synergist, such as pyperonyl butoxide, pyperonyl sulfoxide, or sesamex. These compounds enhance the insecticidal activity of pyrethrin. The Agency does not routinely include, in its screening risk assessments, an evaluation of more than one active ingredient. In the case of product formulations of active ingredients, each active ingredient is subject to an individual risk assessment for regulatory decision. It is noted, however, that some formulations of pyrethrin contain up to 60% PBO, with only about 5 to 6% pyrethrin. It is not clear if pyperonyl butoxide would have an effect in the solubility or on other physicochemical characteristics of pyrethrin or on its environmental fate characteristics. This remains as an uncertainty.

1. Physical Chemical and Fate and Transport Properties The pyrethrins are moderately persistent under certain environmental conditions and are very unstable under other conditions. In soil and water, pyrethrins are degraded by a combination of abiotic and biotic processes, and the rate of these reactions influences the amount of chemical that is ultimately available to aquatic and terrestrial organisms. Pyrethrins are not highly volatile and inhalation is not likely to be a major exposure pathway for mammals and birds. Pyrethrins are considered unstable in the presence of sunlight and are quickly photodegraded. If released to water, photolysis in shallow sunlit surface waters may occur rapidly, with a half life on the order of several hours to about a day. Biodegradation under aerobic conditions also occurs fairly rapidly with half lives on the order of days.  7 On the other hand, pyrethrins are stabe to hydrolysis under acidic and neutral environments ( pH 5 & 7). Pyrethrins adsorb strongly to soil surfaces and are generally considered immobile in soils, showing a low potential to leach into groundwater, but a high potential to reach surface water in runoff events accompanied by erosion. Pyrethrins are expected to adsorb to suspended solids and sediment in the water column, and sediment is likely to be an environmental sink for any non degraded pyrethrins since they appear to persist under anaerobic conditions ( half life > 80 days).

The degradation products of pyrethrin are the result of the rupture of the ester bridge of the parent, resulting in a carboxylic acid and an alcohol. No data about possible degradates related to the cyclopentene ring are available. The major degradate observed in many of the studies was chrysanthemic acid which was observed at a maximum of 4.0% in the aerobic soil metabolism study, 7.0% in the sediment phase of the anaerobic aquatic metabolism study, 8.4% and 8.1% in the aqueous and sediment phases respectively in the aerobic aquatic metabolism study. The only exception was observance of this degradate at a maximum of 64.5% in a hydrolysis study at pH 9 which is an unlikely environmental condition. Although, based on the octanol water coefficient, pyrethrins are expected to bioaccumulate in the organic compartment, a fish bioaccumulation study showed low bioaccumulation potential due to metabolism of the parent compound to chrysanthemic acid. Pyrethrin is stable in the anaerobic aquatic environment, however, a relatively minor degradate, chrysanthemum dicarboxylic acid, was detected at a maximum of 14.2% of the applied at 364 days. In the majority of the studies multiple degradates at very low concentrations were observed, but not characterized. The only other significant isomer observed in the aqueous photolysis study was designated ( E) isomer of pyrethrin 1.

2. Mode of Action The pyrethroids ( including pyrethrin) share similar modes of action, resembling that of DDT, and are considered axonic poisons that affect both the peripheral and central nervous system. It is now well established that severe neurological symptoms of poisoning with pyrethroids and DDT in mammals and insects are the result of modification of Na+ channel activity ( cellular pores through which sodium ions are permitted to enter the axon to cause excitation) ( Matsumura, 1985). Advanced electrophysiological experiments using voltage clamp and patch clamp, together with ligand binding and ionic flux experiments, have unveiled unique actions of pyrethroids of keeping the Na+ channel in the open state for an extremely long period, sometimes as long as several seconds. This modification of Na+ channel properties leads to hyperactivity of the nervous system. Pyrethroids have also been shown to suppress GABA and glutamate receptor channel complexes and voltage activated Ca 2+ channels, but the toxicological significance of these actions is uncertain. Relative to physiological responses, researchers have designated two types of pyrethroids, Type I ( e. g., pyrethrins, S bioallethrin, resmethrin, pyrethrin) and Type II ( e. g., cypyrethrin, deltamethrin, fenvalerate). Type I pyrethroids' action is mainly associated with compounds that cause nerve excitation symptoms typified by the appearance of repetitive firing of axons in the peripheral nervous system and a negatively correlated temperature reversible knockdown property ( similar to DDT) ( Clark and Matsumura, 1987). Pyrethrins are non systemic insecticides that work by physical contact to the insect or by ingestion, and they have a slight repellent effect.  8 The paralyzing effects caused by pyrethrins usually cannot occur without a synergist. For example, the synergist compound in PYRENONE ® Crop Spray ( EPA Reg. No. 432 1033) is piperonyl butoxide, and it blocks the metabolic pathway that would breakdown pyrethrin before the toxic effect occurs. Products that contain pyrethrins are primarily used as a knock down agent on the insects and the addition of a synergist does contribute to the killing efficiency of a formulation ( Casida and Quistad, 1995).

3. Overview of Pesticide Usage Pyrethrins ( CAS number 8003 34 7) are a group of naturally occurring insecticides effective against a broad range of pests used in four major sectors: agricultural, commercial/ industrial/ institutional/ food & non food/ mosquito abatement, domestic home and garden, and pet care. Some of these sectors are not currently assessed by EFED because they do not involve exposure to wildlife or to drinking waters. There are six naturally occurring pyrethrins derived from the flowers of Chrysanthemum cinerariaefolium and Chrysanthemum cineum: pyrethrin 1, pyrethrin 2, cinerin 1, cinerin 2, jasmolin 1 and jasmolin 2.

The final formulation type depends upon the end use, examples include aerosol, combustible coil, dust, emulsifiable concentrate, ready to use liquid, shampoo, and wettable powder. Pyrethrins are often mixed with other insecticides or used in conjunction with synergists such as piperonyl butoxide or sesamex. Recent statistics on agricultural uses of numerous pesticides across the United States during the 1990' s are recorded in the National Center for Food and Agricultural Policy's National Pesticide Use Database available from USGS ( 2004; http:// ca. water. usgs. gov/ pnsp/ use92/) and NFCAP ( 2002; http:// www. ncfap. org/ database/ default. htm); however, these databases do not include data or maps on uses of pyrethrins [ refer to Section III. A. for additional information about Use Characterization]. As indicated earlier, natural pyrethrins have their limitations for use on a large scale for agricultural purposes because of their cost and instability in sunlight.

B. Receptors: Ecological Effects Table 1 gives examples of taxonomic groups and test species evaluated for ecological effects in screening level risk assessments. Within each of these very broad taxonomic groups, an acute and/ or chronic endpoint is selected from the available toxicity data ( see Section 2( C)). Additional ecological effects data on honey bees ( Apis mellifera) 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 measurement endpoints selected for each taxonomic group are included in Appendix E.  9 Table 1. Taxonomic groups and test species evaluated for ecological effects in screening level risk assessments.

Taxonomic group Example( s) of representative species Birdsa Mallard duck ( Anus platyrhynchos) Bobwhite quail ( Colinus virginianus)

Mammals Laboratory rat Freshwater fishb Bluegill sunfish ( Leopomis 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)

Terrestrial plantsc Monocots   corn ( Zea mays) Dicots   soybean ( Glycine max)

Aquatic plants and algae Duckweed ( Lemna gibba) Green algae ( Selenastrum capricornutum)

aBirds may be surrogates for amphibians ( terrestrial phase) and reptiles. bFreshwater fish may be surrogates for amphibians ( aquatic phase). cFour species of two families of monocots, of which one is corn; six species of at least four dicot families, of which one is soybeans.

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 migration pathways of pesticides, and the routes by which ecological receptors are exposed to pesticide related contamination. The selection of clearly defined assessment endpoints is important because they provide direction and boundaries in the risk assessment for addressing risk management issues of concern.

A summary of the assessment and measurement endpoints selected to characterize potential ecological risks associated with exposure to pyrethrins is provided in Table 2.  10 This ecological risk assessment considers maximum application rates on vulnerable soils, maximum number of applications ( as well as single applications), and minimum intervals between application for uses on representative crops to estimate exposure concentrations. 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 endpoints 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 pesticide 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 pesticide to cause adverse effects, to determine whether further testing is required, and to determine the need for precautionary label statements to minimize the potential adverse effects to non target animals and plants ( 40 CFR § 158.202, 2002).

Table 2. Summary of assessment and measurement endpoints.

Assessment Endpoint Measurement Endpoint 1. Abundance ( i. e., survival, reproduction, and growth) of birds. 1a. Bobwhite quail acute oral LD50. 1b. Bobwhite quail and mallard duck subacute dietary LD50. 1c. Bobwhite quail and mallard duck chronic reproduction NOAEC and LOAEC.

2. Abundance ( i. e., survival, reproduction, and growth) of mammals. 2a. Laboratory rat acute oral LD50. 2b. Laboratory rat developmental and 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. 3b. Rainbow trout chronic ( early life) NOAEC and LOAEC. 3c. Water flea ( and other freshwater invertebrates) acute EC50. 3d. Water flea chronic ( life cycle) NOAEC and LOAEC.

4. Survival and reproduction of individuals and communities of estuarine/ marine fish and invertebrates. 4a. Sheepshead minnow acute LC50. 4b. Estimated chronic NOAEC and LOAEC values based on the acute to chronic ratio for freshwater fish. 4c. Eastern oyster and mysid shrimp acute LC50. 4d. Mysid shrimp chronic ( life cycle) NOAEC and LOAEC. 4e. Estimated NOAEC and LOAEC values for mollusks based on the acute to chronic ratio for mysids.

5. Perpetuation of individuals and populations of non target terrestrial and semi aquatic species ( crops and non crop plant species). 5a. Monocot and dicot seedling emergence and vegetative vigor EC25 values.

6. Survival of beneficial insect populations. 6a. Honeybee acute contact LD50.

7. Abundance ( i. e., survival, reproduction, and growth) of earthworm populations. 7a. Acute and subchronic earthworm LC50 values. Table 2. Summary of assessment and measurement endpoints.

Assessment Endpoint Measurement Endpoint  11 8. Maintenance and growth of individuals and populations of aquatic plants from standing crop or biomass. 8a. Algal and vascular plant ( i. e., duckweed) EC50 values for growth rate and biomass measurements.

LD 50 = Lethal dose to 50% of the test population. NOAEC = No observed adverse effect concentration. LOAEC = Lowest observed adverse effect concentration. LC 50 = Lethal concentration to 50% of the test population. EC 50 / EC 25 = Effect concentration to 50/ 25% of the test population.

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 ( EPA 1998a). For this assessment, the risk is stressor initiated, where the stressor is the release of pyrethrin to the environment. The following risk hypothesis is presumed for this screening level assessment:

The use of pyrethrins for agricultural purpuses and vector control ( as a mosquito adulticide) involve situations where terrestrial and/ or aquatic animals may be exposed to the chemical. Based on pyrethrins' persistence, mode of action, direct toxicity and potential indirect effects to trophic food webs, the Agency assumes that this compound has the potential to cause reduced survival, and reproductive impairment to both terrestrial and aquatic organisms.

Adequate protection is defined as protection of growth, reproduction, and survival of aquatic and terrestrial ecological populations, and individuals of threatened and endangered species, as needed.

2. Diagram The conceptual model ( shown in Figure 1 for agricultural uses and 1b for mosquito abatement uses) is a generic graphic depiction of the risk hypothesis. It includes the potential pesticide or stressor ( pyrethrins), the source of the pesticide and/ or transport pathways, exposure media, exposure point, biological receptor types, and attribute changes.

In the specific case of pyrethrin, the source and mechanism of release of pyrethrins may include ground or aerial spray applications to agricultural crops, or ground or aerial applications of the chemical as a mosquito adulticide. Note that in both cases, the conditions of applications are very different. 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.  12 The major point of exposure for aquatic organisms, is direct contact with contaminated water ( gill/ integument uptake), while for terrestrial animals, it is likely that they will eat certain food items contaminated with pyrethrins, such as grass, foliage, and small insects. For plants, it is direct contact.

The representative aquatic receptors are certain freshwater and estuarine/ marine fish, invertebrates, and, in certain cases, aquatic plants. The representative terrestrial receptors are certain mammals, birds, and, in certain cases, terrestrial plants. It should be noted, that these species do not cover all the possible species in the animal and plant kingdoms. For example, no reptiles are represented in this scheme.

The attribute changes depend on the type of test ( eg. reduced survival, growth, or reproduction, and for plants, seedling emergence and vegetative vigor).  13  14  15 E. Analysis Plan 1. Develop Assessment Design For aquatic receptors, the main pathway of exposure is through direct contact with surface water contaminated with runoff from agricultural fields and spray drift. Risks to aquatic species were based on estimated environmental concentrations ( EECs) using the Tier 2 model PRZM/ EXAMS, and for adulticide uses, with the help of AGDISP. Residues in potential dietary sources for mammals and birds ( e. g., vegetation, insects, fruits/ pods, and seeds) were estimated using the Tier 1 model T REX.

2. Identification of Data Gaps and Methods for Conducting Assessment The adequacy of the submitted data was evaluated relative to Agency guidelines. The following identified data gaps for ecological fate and effects endpoints result in a degree of uncertainty in evaluating the ecological risk of pyrethrins.

° Chronic data for estuarine / marine fish and invertebrates were not submitted by the registrant for pyrethrins. Therefore, chronic risks could not be calculated for these particular taxa; however based on an acute to chronic ratio method done by EFED, NOAECs were estimated for these species. In the absence of data, the estimated NOAECs suggest that chronic risk quotients for estuarine/ marine invertebrates exceed the level of concern. However, pyrethrins do not pose a risk concern for estuarine/ marine fish. Chronic toxicity data for estuarine / marine fish and invertebrates ( fish early life cycle and invertebrate life cycle) are needed to fully characterize effects to these animals.

° No field study data were identified to estimate pyrethrin residues on plants and provide estimates of foliar dissipation half lives. Therefore, in the terrestrial exposure assessment a half life of 1 14days was used to represent dissipation of pyrethrins on plant surfaces.

° Risks to terrestrial and semi aquatic plants were not evaluated because toxicity data on these receptors were not available. However, there are significant incidence data reported that provides evidence of possible phytotoxicity of the pyrethrin compounds and formulated products. Toxicity data are needed for terrestrial and aquatic plants to fully understand the extent of phytotoxicity of products that contain pyrethrins.

° Chronic risks to birds were not evaluated because toxicity data on avian species were not available.

° Inhalation and dermal pathways for terrestrial mammals and birds were not evaluated because these routes of exposure are considered to be minimal compared to the dietary ingestion pathways. Uncertainties associated with exposure pathways for  16 terrestrial animals are discussed in Section 4( C)( 3).

° Risks to semiaquatic wildlife via consumption of pesticide contaminated fish were not evaluated. However, given that bioaccumulation of pyrethrins is low, ingestion of fish by piscivorous wildlife ( such as bears) is not likely to be of concern.

C Exposure to birds and small mammals ( up to 1000 g) via ingestion of grasses, plants, fruits/ pods, seeds, and insects was considered. Risk to mammals of large body weights ( such as wolves or bears) were not evaluated because the toxic endpoints from laboratory tests with the surrogate mammal ( laboratory rat) are based on small body weight.

° In the absence of sediment toxicity and exposure data, a screening method developed by the Office of Water ( OW), that relies on equilibrium partitioning ( EqP) of the chemicals, was used to estimate the risk quotients for sediment dwelling organisms. Pyrethrin degrades with an aerobic soil half life of about 10 days; however, it is relatively persistent under anaerobic conditions in the aquatic environments. Nondegraded pyrethrins are likely to bind to sediment and be available to sediment dwelling organisms for extended periods of time. To estimate the exposure to pyrethrins in sediment, EFED calculated the pore water concentrations using PRZM/ EXAMS. Furthermore, using the OW methodology, toxicity data for the water column invertebrates were used to estimate the toxicity and associated risk to benthic organisms.

° Surrogates were used to predict potential risks for species on which the Agency does not have data ( e. g., birds as surrogates for reptiles and terrestrial phase amphibians and fish as surrogate species for aquatic phase amphibians). It was assumed that use of surrogate effects data is sufficiently conservative to apply the broad range of species within taxonomic groups. If other species are more or less sensitive to pyrethrins, and its associated degradates, risks may be under or overestimated, respectively.

° The pyrethrins label supports a minimum interval between applications of one day, although a three day interval is recommended for typical uses. Most EECs were estimated using the more protective assumption of a one day interval for each of 10 applications ( high pest pressure). There were a few selected crops that were modeled using the same number of applications, but with the three day interval to represent exposure based on typical use ( normal pest pressure).

3. Measures to Evaluate Risk Hypotheses and Conceptual Model a. Measures of Exposure C The major routes of dissipation of pyrethrins in the environment are photolysis ( both in water  17 and soil) and to a lesser degree, aerobic soil metabolism. The pyrethrins are relatively stable under hydrolytic conditions at pH 5 and 7, and under anaerobic conditions. Pyrethrins adsorb strongly to soil surfaces and are generally considered immobile in soils. The degradation products of pyrethrin are considered of low concern. Pyrethrins are unlikely to reach ground waters, but they can reach surface waters via spray drift and rainfall events that cause runoff accompanied by erosion. Once in the water, they are expected to partition in the sediment where they may persist for a long period of time.

C For agricultural uses, exposure concentrations for aquatic ecosystems assessments were estimated based on EFED's aquatic Tier 2 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 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 EXAMS, which simulates surface water in order to predict the EECs. Thirteen PRZM field scenarios were modeled: GA Peaches, FL Citrus, CA Wheat, OR Snapbeans, IL corn, ME Potato, MS Cotton, PA Tomato, ND Wheat, CA Onion, NC Apple, ID Potato, MN Alfalfa, and CA Grapes. These scenarios were selected to represent a variety of crops and sites in the continental US. EECs for ecological risk assessment were determined using a Mississippi Pond modeling scenario which describes a generic scenario for the EXAMS component of the modeling exercise.

C For agricultural scenarios, a subset of the selected scenarios were analyzed with the typical application rate and number of applications. Priority was provided to vegetable crops.

C For the mosquito adulticide use, pyrethrins are applied as very small droplets to create a mist which remains suspended over the field to more efficiently target the mosquitoes. Therefore, they are susceptible to drift towards an adjacent body of water. To determine the deposition of the pesticide to adjacent water bodies, the computer model AGDISP [ AGricultural DISPersal ( computer) model ( AGDISP v. 8.08)] was used. The outputs of interest from AGDISP are the application efficiency ( fraction of the material that deposits in the target area under the aircraft), and the downwind deposition ( fraction of the material that deposits in the designated area or the standard pond). These results were subsequently used as input parameters in PRZM/ EXAMS to model the degradation and partitioning in sediment for water bodies of various depths ( 6 in, 1 ft., 1 m, and 2 m) that may be exposed to drift from the mosquito adulticide. Furthermore, the analysis was performed using boom height of 75 ft and 150 ft ( which were found to by typical for adulticide applications), and droplet sizes of 40 and 50 : m, and the maximum application rate supported by the PJV in the Master Label ( 0.008 lb a. i./ A), and a typical application rate ( of 0.0025 lb a. i./ A).

C Analysis of the most conservative scenario ( 1 day interval between applications, which is the interval for high pest pressure) was performed for 13 crops; however, three crops were selected and run with a less conservative scenario, which will be nominated typical scenario ( 3 days interval, designated as the interval between applications for normal pest pressure).  18 A comparison of the results was provided. These crops represented the range of EECs that were observed among the 13 crops run originally with 1 day interval between applications.

C The effect of spray drift and buffer zones on exposure to bodies of water adjacent to 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 number of crops scenarios was performed using the PRZM/ EXAMS model. Representative crops were run in PRZM/ EXAMS with spray drift set to 0% ( to detect the extent of spray drift for that crop scenario), and 1% ( to simulate ground application). EFED bracketed the spray drift options by running a " high end" ( conservative) and a " low end" ( best case) drift scenarios. The simulations were performed using AgDRIFT ® with spray drift levels for buffer zones of 0, 50, 100, and 150 ft. at the " low" end and " high" end drift scenarios. The output values from AgDRIFT ® were used as input values in PRZM/ EXAMS.

C Screening level RQs for sediment dwelling organisms were estimated with an extrapolation method recommended by the Office of Water ( USEPA). This was based on the Agency Equilibrium Partitioning Sediment Guidelines ( ESG) under the Clean Water Act [ CWA Section 304( a)( 2)]. After consultation with the OW, EFED adopted the equilibrium partitioning ( EqP) sediment method to be used when sediment toxicity and exposure data are not available. This extrapolation method is useful for estimating potential sediment exposure values, as well as sediment toxicity values that can be used in a screening level risk assessment. The EqP theory holds that a nonionic chemical in sediment partitions between sediment organic carbon, interstitial ( pore) water and benthic organisms. At equilibrium, if the concentration in any phase is known, then the concentration in the other phases can be predicted through the organic/ carbon soil partition coefficient. The EECs are calculated from the pore water concentration ( an output from PRZM/ EXAMS) through the K OC . In the absence of sediment toxicity data, the endpoints are extrapolated from the water column invertebrate toxicity tests.

C Residues in potential dietary sources for mammals and birds ( e. g., vegetation, insects) were estimated using the conceptual approach given in the Tier 1 model T REX Version 1.4 ( TREX 2004).

C To estimate exposure related to releases of pyrethrins to domestic wastewater treatment, the Agency relied on the Office of Pollution Prevention and Toxics ( OPPT) model, Exposure and Fate Assessment Screening Tool ( E FAST) ( USEPA, 1999). From this model, the Agency used the " Down the Drain" module, which is designed for releases to domestic wastewater treatment. It is suitable for all sources of pyrethrins that could potentially be exposed through a " down the drain" scenario. The model provides screening level estimate concentrations of chemicals in surface waters that may result from household uses and disposal of consumer products into wastewater using a few simple input parameters ( production volume and fraction of the chemical removed during wastewater treatment).

b. Measures of Effect  19 Measures of effect are generally based on the results of a toxicity study, although monitoring data may also be used to provide supporting lines of evidence for the risk characterization. A complete summary of the measures of effect based on toxicity studies for different ecological receptors and effect endpoints ( acute/ chronic) is given in Table 2. In the absence of chronic data for estuarine/ marine fish and invertebrates, the acute to chronic ratio method can be used to estimate NOAECs for these animals. 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 a NOAEL for birds or mammals based on reproduction or developmental endpoints, and an EC 50 for plants based on growth rate or biomass measurements.

III. Analysis A. Use Characterization Pyrethrins ( CAS number 8003 34 7) are a group of naturally occurring insecticides effective against a broad range of pests. There are no statistics regarding the use of pyrethrins in the National Center for Food and Agricultural Policy pesticide database ( NCFAP) ( NCFAP, 2003). According to the manufacturer label, there are four main sectors of use for pyrethrins: 1) agriculture 2) pet care 3) domestic home and garden; and 4) commercial, industrial, institutional, food & non food, mosquito abatement.

The major focus of this environmental assessment is on agricultural uses and mosquito abatement. It is acknowledged that, as indicated earlier, natural pyrethrins have their limitations for use on a large scale for agricultural purposes because of their cost and instability in sunlight. The agricultural preharvest applications to field crops are divided into several cropping groups which are summarized in Table 3. It is noted that this does not include the greenhouse, domestic, or commercial uses. According to the Master Label, the same use rate applies to all the crops. In 2000, more than 200,000 lb of pyrethrin were sold, of which around 6% was used for terrestrial non food uses, and around 1% was used for outdoor recreation ( including mosquito abatement).

For uses on crops, the following assumptions were made: application rate of 0.05 lbs a. i. A, 10 applications, and a 1 day interval or 3 day interval. For mosquito abatement uses, the following assumptions were made: application rate of 0.008 lbs a. i./ A ( from the label), 26 applications, and a 4 day interval. The mosquito abatement use covers a longer time period in order to approximate a period when mosquito abatement would be warranted.  20 Table 3. The following crops appear in the master label for pyrethrin. a The maximum application rate appears in the first row.

Maximum application rate: 0.050 lb a. i./ A Maximum seasonal application rate 0.500 lb a. i./ A/ season Maximum number of applications: 10 Minimum application intervals: 1 day ( under extreme pressure), 3 days ( under normal pressure)

Crop Group 1: Root and Tuber Vegetables ( root crop vegetables): arracacha, arrowroot, Chinese artichoke, Jerusalem artichoke, fodder beet, garden beet, sugar beet, edible burdock, edible canna, carrot, cassava, celeriac, chayote, turnip rooted chervil, chicory, chufa, dasheen, ginger, ginseng, horseradish, leren, turnip rooted parsley, parsnip, potato, radish, oriental radish, rutabaga, salsify, black salsify, Spanish salsify, skirret, sweet potato, tanier, taro, turmeric, turnip, yam bean, and true yam.

Crop Group 2: Leaves of Root and Tuber Vegetables: fodder beet, garden beet, sugar beet, edible burdock, carrot, cassava, turnip rooted chervil, chicory, dasheen, parsnip, radish, oriental radish, rutabaga, salsify, black salsify, Spanish salsify, tanier, taro, turnip, and true yam.

Crop Group 3: Onion ( root crop vegetables): green onions, scallion onions, spring onions, shallot, garlic, leek, great headed garlic, dry bulb onion, potato onion, tree onion, and welsh onion.

Crop Group 4: Leafy Vegetables ( leafy and stem vegetables, except brassica vegetables): leafy amaranth, arugula, cardoon, celery, Chinese celery, celtuce, chervil, edible leaved Chrysanthemum, garland Chrysanthemum, salad corn, garden cress, upland cress, dandelion, dock, endive, Florence fennel, sea kale, head lettuce, leaf lettuce, orach, parsley, garden purslane, winter purslane, radicchio, rhubarb, spinach, Chinese spinach, New Zealand spinach, vine spinach, Swiss chard, and Tampala.

Crop Group 5: Cole Crops ( leafy and stem vegetables, brassica leafy group): broccoli, Chinese, broccoli, raab broccoli, cabbage, Chinese cabbage, bok choy, Chinese mustard cabbage, Chinese napa cabbage, cauliflower, , collards, kale, kohlrabi, mustard greens, mustard spinach, and rape greens.

Crop Group 6: Legume Vegetables ( succulent or dried seed and pod vegetables): bean, adzuki bean, broad bean, dry bean, kidney bean, lablab bean, lima bean, moth bean, mung bean, navy bean, pink bean, pinto bean, rice bean, runner bean, snap bean, tepary bean, urd bean, wax bean, yardlong bean, catjang, chickpea, cowpea, edible gum, jackbean, lentil, grain lupin, pea, blackeyed pea, crowder pea, dry pea, dwarf pea, edible pod pea, English pea, field pea, garden pea, green pea, pigeon pea, snow pea, Southern pea, succulent pea, sugar snap pea, soybean, swordbean.

Crop Group 7: Foliage of Legume Vegetables ( seed and pod vegetables): dry bean, lima bean, snap bean, cowpea, grain lupin, field pea, pigeon pea, soybean. Table 3. The following crops appear in the master label for pyrethrin. a The maximum application rate appears in the first row.

Maximum application rate: 0.050 lb a. i./ A Maximum seasonal application rate 0.500 lb a. i./ A/ season Maximum number of applications: 10 Minimum application intervals: 1 day ( under extreme pressure), 3 days ( under normal pressure)

 21 Crop Group 8: Fruiting Vegetables ( except cucurbits): chili, eggplant, groundcherry, pepino, pepper, bell pepper, nonbell pepper, nonbell sweet pepper, tomatillo, tomato.

Crop Group 9: Cucurbit Vegetables: balsam apple, balsam pear, cantaloupe, chayote, cucumber, Chinese cucumber, West Indian gherkin, edible gourd, melon, citron melon, muskmelon, pumpkin, squash, Summer squash, Winter squash, watermelon, Chinese waxgourd.

Crop Group 10: Citrus Fruits: calamondin, citrus citron, citrus, citrus hybrids, grapefruit, kumquat, lemon, lime, satsuma mandarin, sour orange, sweet orange, pummelo, tangelo, tangerine.

Crop Group 11: Pome Fruits: apple, crabapple, loquat, mayhaw, pear, Oriental pear, quince.

Crop Group 12: Stone Fruits: apricot, sweet cherry, tart cherry, nectarine, peach, plum, chickasaw plum, damson plum, Japanese plum, prune plum.

Crop Group 13: Berries: blackberry, blueberry, currant, elderberry, gooseberry, huckleberry, loganberry, black and red raspberry, canaberry.

Crop Group 14: Tree Nuts: almond, beech nut, Brazil nut, butternut, cashew, chestnut, chinquapin, filbert, hickory nut, macadamia nut, pecan, pistachio, walnut black, English walnut.

Crop Group 15: Cereal Grains: barley, buckwheat, corn, field corn, pod corn, pop corn, sweet corn, millet, pearl millet, proso millet, oat, rice, wild rice, rye, grain sorghum, teosinte, tricale, wheat, vavilovi wheat, wild einkorn wheat, wild emmer wheat.

Crop Group 16: Forage, Fodder and Straw of Cereal Grains: barley, field corn, pod corn, pop corn, sweet corn, millet, pearl millet, proso millet, oat, rice, wild rice, rye, forage sorghum, grain sorghum, teosinte, tricale, wheat, vavilovi wheat, wild einkorn wheat, wild emmer wheat. Table 3. The following crops appear in the master label for pyrethrin. a The maximum application rate appears in the first row.

Maximum application rate: 0.050 lb a. i./ A Maximum seasonal application rate 0.500 lb a. i./ A/ season Maximum number of applications: 10 Minimum application intervals: 1 day ( under extreme pressure), 3 days ( under normal pressure)

 22 Crop Group 17: Grass Forage, Fodder, and Hay: alkali sacaton, alkakigrass, Arizona cottontop, bahiagrass, beachgrass, spike bentgrass, Bermudagrass, blowoutgrass, gluegrass, silky bluegrass, Australian bluestern, big bluestern, caucasian bluestern, Díaz bluestern, little bluestern, sand bluestern, silver bluestern, South African bluestern, yellow bluestern, plains bristlegrass, bromegrass, broomsedge, Buffalograss, buffelgrass, annual Canarygrass, reed Canarygrass, caribgrass, carpetgrass, broadleaf carpetgrass, centipedegrass, marshhay cordgrass, crabgrass, curly mesquite, dallisgrass, pine dropseed, sand dropseed, tall dropseed, fescue, feather fingergrass, creeping foxtail, meadow, Eastern gamagrass, grass, galleta grass, grama grass, muhly grass, pasture grass, St. Augustine grass, wildrye grass, zoysia grass, tufted hairgrass, hardinggrass, Indiangrass, junegrass, limpograss, lovegrass, maidencane, mannagrass, foxtail millet, Japanese millet, molassesgrass, napiergrass, needlegrass, sand oat, slender oat, wild oat, tall oat, oniongrass, pangolagrass, panicgrass, paspalum, polargrass, quackgrass, redtop, reedgrass, rhodesgrass, multiflower false rhodesgrass, Indian ryegrass, Italian ryegrass, perennial ryegrass, prairie sandreed, sixweeks threeawn, sloughgrass, smilograph, forage sorghum, green sprangletop, Sudangrass, sunolgrass, tanglehead, Timothy, alpine Timothy, spike trisetum, vaseygrass, perennial veldtgrass, velvetgrass, wheatgrass, bluebunch wheatgrass, crested wheatgrass, fairway wheatgrass, intermediate wheatgrass, pubescent wheatgrass, Siberian wheatgrass, slender wheatgrass, streambank wheatgrass, tall wheatgrass, thickspice wheatgrass, Western wheatgrass, hooded windmillgrass.

Crop Group 18: Nongrass Animal Feeds: alfalfa, arrowleaf balsamroot, clover, alsike clover, alyce clover, arrowleaf clover, ball clover, berseem clover, bigflower clover, crimson clover, hop clover, lappa clover, Persian clover, red clover, rose clover, seaside clover, strawberry clover, striate clover, sub clover, sweet clover, true clover, white clover, whitetip clover, crownvetch, kudzu, lespedeza, lupine, forage lupine, sweet lupine, mustard, sainfoin, trefoil, velvetbean, vetch, milk vetch.

Crop Group 19: Herbs and Spices: allspice, anise, anise hyssop ( mint), star anise, annatto, balm, basil, borage, burnet, camomile, caper, caraway, black caraway, cardamom, cardamom amomum, cassia, catnip, celery seed, chervil, chive, Chinese chive, cinnamon, clary, clove, coriander, costmary, culantro, cumin, curry, dill, dillweed, fennel, Florence fennel, fenugreek, grains of paradise, horehound, hyssop, juniper berry, lavender, lemongrass, lovage, mace, pot marigold, marjoram ( oregano), mustard, nasturtium, nutmeg, parsley, pennyroyal, black pepper, white pepper, poppy, rosemary, rue, saffron, sage, Summer savory, Winter savory, sweet bay, tansy, tarragon, thyme, vanilla, wintergreen, woodruff, wormwood. Table 3. The following crops appear in the master label for pyrethrin. a The maximum application rate appears in the first row.

Maximum application rate: 0.050 lb a. i./ A Maximum seasonal application rate 0.500 lb a. i./ A/ season Maximum number of applications: 10 Minimum application intervals: 1 day ( under extreme pressure), 3 days ( under normal pressure)

 23 Subtropical Fruits: acerola, avocado, banana, carob bean, cherimoya, date, durian, feijoa, fig, guava, kiwifruit, lychee, mango, papaya, passionfruit, pineapple, pomegranate.

Oriental Vegetable: acerola, Chinese artichoke, atemoya, balsam pear, mung bean, yardlong bean, Chinese broccoli, Chinese cabbage, bok choy, napa, coriander ( cilantro), dasheen, ginger, ginseng, melon, citron, Oriental radish, rambutan, Chinese spinach, starfruit ( carambola), Chinese waxgourd.

Miscellaneous Crops: asparagus, coffee, tea, grapes, strawberry, cranberry, hops, sesame, jojoba, safflower, sunflower, okra, sugarcane, cotton.

aPHI = 0 days (" wait until the material applied is dry"); for cotton PHI is 14 days ( of seed harvest); do not wet plants to point of runoff or drip.

B. Exposure Characterization 1. Environmental Fate and Transport Characterization The physical and chemical properties and some environmental fate properties of the pyrethrins are summarized in Table 4 ( certain references were obtained from the TOXNET database).

Table 4. Summary of environmental chemistry and fate properties of pyrethrins.

Parameter Value Reference/ Commentsa Selected Physical/ Chemical Parameters PC code 069001 CAS No. 8003 34 7 Pyrethrum, 121 21 1 pyrethrin 1, 121 29 9 pyrethrin 2, 25402 06 6 cinerin 1, 121 20 0 cinerin 2, 4466 14 2 jasmolin 1, 1172 63 0 jasmolin 2 Table 4. Summary of environmental chemistry and fate properties of pyrethrins.

Parameter Value Reference/ Commentsa  24 Physical state Clear pale viscous liquid Budavari, S. ( ed.). The Merck Index   An Encyclopedia of Chemicals, Drugs, and Biologicals. Whitehouse Station, NJ: Merck and Co., Inc., 1996, 1369. Lewis, R. J., Sr. ( Ed.). Hawley's Condensed Chemical Dictionary. 13th Ed. New York, NY: John Wiley & Sons, Inc. 1997. 273, 942 Odor Faint: Dried flowers Reported by the registrant Stability Stable at room temperatures for over three years when stored in the absence of light in steel drums Reported by the registrant. Table 4. Summary of environmental chemistry and fate properties of pyrethrins.

Parameter Value Reference/ Commentsa  25 Chemical name pyrethrin 1: ( Z)( S) 2 methyl 4 oxo 3( penta 2,4 dienyl) cyclo pent 2 enyl ( 1R) trans 2,2 dimethyl 3( 2 methylprop 1 enyl) cyclopropanecarboxylate pyrethrin 2: ( Z)( S) 2 methyl 4 oxo 3( penta 2,4 dienyl) cyclo pent 2 enyl ( E)( 1R) trans 3( methoxy carbonylprp enyl) 2,2 dimethylcyclopropanecarboxylate cinerin 1: ( Z)( S) 3( but 2 enyl) 2 methyl 4 oxocyclopent 2 enyl ( 1R) trans 2,2 di methyl 3( 2 methyl prop 1 enyl) cyclopropanecarboxylate cinerin 2: ( Z)( S) 3( but 2 enyl) 2 methyl 4oxocyclopent 2 enyl ( E)( 1R) trans 3( 2 methoxycarbonylprop 1 enyl) 2,2 dimethyl cyclopropanecarboxylate jasmolin 1: ( Z)( S) 2 methyl 4 oxo 3( pent 2 enyl) cyclopent 2 enyl ( 1R) trans 2,2 dimethyl 3( 2 methylprop 1enyl) cyclopropanecarboxylate jasmolin 2: ( Z)( S) 2 methyl 4 oxo 3( pent 2 enyl) cyclopent 2 enyl ( 1R) trans 3( 2 methoxycarbonylprop 1 enyl) 2,2 dimethylcyclopropanecarboxylate Table 4. Summary of environmental chemistry and fate properties of pyrethrins.

Parameter Value Reference/ Commentsa  26 Chemical formula C 21 H 25 O 3, C 21 H 25 O 5,

C 20 H 25 O 3, C 22 H 30 O 5, C 21 H 28 O 3 , C 22 H 28 O 5 Molecular weight 328.4 g/ mol pyrethrin 1 372.4 g/ mol pyrethrin 2 316.4 g/ mol cinerin 1 360.4 g/ mol cinerin 2 330.5 g/ mol jasmolin 1 357.7 g/ mol jasmolin 2 Water solubility pyrethrin 1: 0.2 ppm pyrethrin 2: 9.0 ppm cinerin 1: Insoluble cinerin 2: Insoluble jasmolin 1: 0.03 ppm jasmolin 2: 0.09 ppma Estimated values from EPISUITE. a Other values from HSDB 2001 ( Hazardous Substances Data Bank, as cited in Pyrethrins and Pyrethroids, Chapter 4. Chemical and Physical Information)

Solubilities Soluble in alcohol, ether, diethyl ether, kerosene, carbon tetrachloride, nitromethane, and ethylene dichloride Budavari, S. ( ed.). The Merck Index   An Encyclopedia of Chemicals, Drugs, and Biologicals. Whitehouse Station, NJ: Merck and Co., Inc., 1996, 1369 Density pyrethrin 1: 1.5192 g/ cm3 @ 18 ° C Pyrethrum: 0.84  0.86 g/ cm3 ( 25% pale extract) 0.975 g/ cm3, range 0.97  0.98 g/ cm3 Lide, DR ( ed.). CRC Handbook of Chemistry and Physics. 81st Edition. CRC Press LLC, Boca Raton: FL 2000, p. 3  137. Tomlin, C. D. S. ( Ed.). The Pesticide Manual   World Compendium, 11th Ed., British Crop Protection Council, Surrey, England 1997 1057. Reported by the registrant. Table 4. Summary of environmental chemistry and fate properties of pyrethrins.

Parameter Value Reference/ Commentsa  27 Boiling point 146  148 ° C at 2x10 3 mm Hg, 146  150 ° C at 5x10 4 mm Hg, and 170 ° C at 0.1 mm Hg for pyrethrin 1 196  198 ° C at 7x10 3 mm Hg, 192  193 ° C at 7x10 3 mm Hg, 200 ° C at 0.1 mm Hg for pyrethrin 2 136  138 ° C at 8x10 3 mm Hg for cinerin 1 182  184 ° C at 0.001 mm Hg for cinerin 2 Partially from: Budavari, S. ( ed.). The Merck Index   An Encyclopedia of Chemicals, Drugs, and Biologicals. Whitehouse Station, NJ: Merck and Co., Inc., 1996, 1369. Reported by the registrant.

Vapor pressure ( 25 ° C) pyrethrin 1: 2.03x10 5 mm Hg pyrethrin 2: 3.98x10 7 mm Hg cinerin 1: 1.1x10 6 mm Hga cinerin 2: 4.6x10 7 mm Hga jasmolin 1: 4.8x10 7 mm Hga jasmolin 2: 1.9x10 7 mm Hga. Tomlin, C. D. S. ( Ed.). The Pesticide Manual   World Compendium, 11th Ed., British Crop Protection Council, Surrey, England 1997 1057, 1058 Estimated value from EPISUITEa Henry's Law constant pyrethrin 1: 7.7x10 7 Atm m3/ mola pyrethrin 2: 7.4x10  10 Atm m3/ mola cinerin 1: 9.6x10 7 Atm m3/ mola cinerin 2: 9.2x10 10 Atm m3/ mola jasmolin 1: 1.3x10 6 Atm m3/ mola jasmolin 2: 1.2x10  9 Atm m3/ mola Estimated value from EPISUITEa Table 4. Summary of environmental chemistry and fate properties of pyrethrins.

Parameter Value Reference/ Commentsa  28 log K OW pyrethrin 1: 5.9 pyrethrin 2: 4.3 Tomlin, C. D. S. ( Ed.). The Pesticide Manual   World Compendium, 11th Ed., British Crop Protection Council, Surrey, England 1997 1057, 1058 Persistence Hydrolysis t 1/ 2 pH 5 pH 7 pH 9 Stable Stable 14 days MRID 43188201 pH 5 pH 7 pH 9 Stable Stable 17 days Major degradate chrysanthemic acid ( 54  64%) at 21 days MRID 43567502 Photolysis t 1/ 2 in water 11.8 hours, for the combination of pyrethrin and the ( E) Isomer of pyrethrin 1 (@ 55.7% at 2 hours) MRID 43567601 Photolysis t 1/ 2 on soil < 24 hours, numerous minor degradation products MRID 43096602 Soil metabolism aerobic t 1/ 2 24  25 ° C 9.5 days ( total) 3.2 days ( bi phasic initial halflife MRID 43499803 Soil metabolism anaerobic t 1/ 2 NA N/ A Aquatic metabolism aerobic t 1/ 2 10.5 days MRID 43499802 Aquatic metabolism anaerobic t 1/ 2 86 days MRID 43499801 Mobility/ Adsorption Desorption Table 4. Summary of environmental chemistry and fate properties of pyrethrins.

Parameter Value Reference/ Commentsa  29 Batch equilibrium   unaged soil type classification K ads K oc MRID 43096603 S Immob 198 3784 7 SL Immob 268 1247 2 Average K OC = 35,170 SiL Immob 430 7417 5 SiClL Immob 310 1619 0 Laboratory volatility Limited volatility, # 0.002 : g/ cm2° hour; after 30 days, volatilized residues totaled a maximum of ~ 16% of which ~ 9% was CO 2 , ~ 0.3% was pyrethrin, ~ 10% chrysanthemic acid, and ~# 2.4 of two other degradates. MRID 43096604 Field Dissipation Terrestrial field dissipation 1  2 days MRID 42745501 Aquatic field dissipation Study is not valid MRID 43818501 Bioaccumulation Accumulation in fish, maximum BCF 873X viscera 127X edible tissues predominant species were parent and chrysanthemic acid MRID 43302301, 43884102 Pyrethrin is a naturally occurring substance that contains six esters that are biologically active. Pyrethrin 1 was chosen as a surrogate chemical to represent all six pyrethrin. All of the environmental fate studies were performed with pyrethrin 1.  30 General Stereochemistry of the Pyrethrins R =  CH3 ( for cinerin),  CH2CH3 ( for jasmolin) or  CH= CH2 ( for pyrethrin)

R'=  CH3 ( for pyrethrins I),  CO2CH3 ( for the pyrethins II)

As noted, all the pyrethrins have the same backbone structure, with the exception of variations in the substitutions in the external or outermost groups. Due to the fact that all the pyrethrins have very similar structures, the environmental fate studies were conducted and well characterized with only one of the pyrethrins: pyrethrin 1.

Except for the interaction with polarized light, enantiomers have identical physico/ chemical properties. However, diastereoisomers could have somewhat different basic properties. In this case the differences are in the substituents at two sites. The substituents at  R are expected to have low reactivity, with the ethene being slightly more reactive. In any case, the driving fate reaction is the breaking of the ester bond which is away from  R. On the other hand, in the case of  R', we have two different moieties. The methyl moiety will be relatively unreactive, while the acetyl group ( ester bond) will be susceptible to hydrolysis, resulting in an acid and an alcohol. It is noted from the Table 4 that the water solubility of the various pyrethrins varies due to some structure variations among them, however, since the environmental fate of only pyrethrin 1 was characterized, its solubility was used in the models. This may add some uncertainty to the assessment. Nevertheless, we do not expect major differences in the overall biotic and abiotic degradation of the pyrethrins.

In general, the environmental fate and transport data base of pyrethrin 1 is adequate to characterize the environmental fate, drinking water, and ecological exposure of the pyrethrins. It is unlikely that the submission of additional data would change the environmental fate assessment substantially. There are no mobility and little persistence data for the degradates of pyrethrin 1. In addition, studies using radiolabeling on the cyclopentene side of the ester linkage were not conducted and cold analysis was not performed in the cyclopropyl labeled studies. Consequently, there was no analysis of potential degradates containing the cyclopentene ring originating from the cleavage of the carboxylate ester linkage.

Degradation and Metabolism Cyclopropane ring labeled [ 1 14C] pyrethrin [ pyrethrin 1], at a nominal concentration of 0.4 ppm, was relatively stable in sterile aqueous pH 5 and pH 7 buffer solutions that were incubated in the dark at 25 ± 1 /

C for 30 days. In pH 9 solutions, pyrethrin 1 hydrolyzed with a calculated half life of 14 days and 17 days. The major degradation product identified was chrysanthemic acid at up to 64% of the applied at 21 days.

In an aqueous photolysis experiment, pyrethrin 1 isomerized to the ( E) isomer of pyrethrin 1 ( which reached a maximum 50.7  55.7% of the applied amount at 2 hours post treatment ) with an observed half life of  31 approximately 1 hour in sterile aqueous 0.01 M buffer solutions ( pH 7) that were irradiated with sunlight in Irvine, California ( 33 ° 41' N, 117 ° 15' W) at 25 ° C for 71 hours, between 11 AM on October 7 and 10 AM on October 10, 1993. The overall calculated half life of dissipation of pyrethrin 1 and its ( E) isomer was 11.8 hours. In a soil photolysis study, [ 14C] Pyrethrin [ pyrethrin 1] photodegraded with an observed half life of < 24 hours ( registrant reported 12.9 hours) in sandy loam soil that was treated at 9.0  9.6 ppm and irradiated with natural sunlight in California at 24+ 2 ° C for 24 hours in mid November. In contrast, the dark control samples degraded with a reported half life of 82.9 hours.

The reported half life of 14C pyrethrin 1 applied at a nominal application rate of 1 ppm, in an aerobic sandy loam soil adjusted to 75% of field capacity and incubated in the dark at 25 ± 1 ° C for up to 181 days was 9.5 days. The degradation was reported as biphasic [ half lives were 3.2 days ( 0  14 day data) and 23.5 days ( 14  59 day data)]. Chrysanthemic acid was a minor identified metabolite. Another band ( which appears to consist of multiple peaks) could not be identified.

[ 14C] pyrethrin 1 degraded with a half life of 10.5 days ( r2 = 0.96) in flooded sandy loam soil incubated at 25 ± 1 ° C for up to 30 days in an aerobic aquatic dissipation study. In an anaerobic aquatic dissipation study the half life of pyrethrin 1 was 86 days.

It is noted that in all the studies, the material was radiolabeled in the cyclopropane ring. As a result, mostly the degradate that would be observed is chrysanthemic acid. Material radiolabeled in the cyclopentenolone ring would result in different degradation products; however, the first step in the degradation of pyrethrin 1 is the rupture of the ester bridge, resulting in a carboxylic acid, and an alcohol. The resulting molecules have lost their pyrethroid toxicological activity; therefore, in this assessment, they were not considered of concern. Furthermore, the available data show that chrysanthemic acid does not reach high levels except upon hydrolysis at pH 9. In the majority of the studies multiple degradates at very low concentrations were observed, but not characterized. The only significant isomer observed in the aqueous photolysis study was the ( E) isomer of pyrethrin 1; however, the half life of pyrethrin 1 was reported for the photolysis of pyrethrin 1 plus the isomer ( as if it was parent) in the calculation ( the resulting half life was less than one day).

The figure that follows shows the structures of the expected degradation products of the various pyrethrins. All six of them are expected to be more soluble and mobile than their respective parent compounds, specially the acids. Based on the information from pyrethrin 1, chrysanthemic acid appeared to be short lived and pyrethric acid and chrysanthemum dicarboxylic acid would be expected to behave similarly. The E isomer of pyrethrin 1 was shown in the photolysis on soil study to be short lived as well, therefore, it is of low concern.  32 Fig. 2. Structures of Degradation Products of the Pyrethrins Soil Sorption and Mobility Based on batch equilibrium experiments, [ 14C] pyrethrin 1 was determined to be immobile in sand, sandy loam, silt loam, and silty clay loam soil: calcium chloride solution slurries ( 1: 100, w: v). The respective Koc values in were 37,847, 12,472, 74,175, and 16,190.

Field Dissipation EFED has waived the Terrestrial Field Dissipation Study ( § 164 1) data requirement. EFED believes that a new study will not substantially change the environmental fate assessment. The parent degrades rapidly and the ultimate degradate is CO2, and bound residues in soil. It appears that formed metabolites are of no significant environmental concern, as indicated earlier. The proposed use rate is low ( single application rate of 0.050 lb a. i./ acre, seasonal application rate of 0.50 lbs a. i./ acre). The degradates such as chrysanthemic acid may not reach sufficiently high levels to pose a toxicological concern. Based on data from the laboratory studies, at the current application rate, in field use conditions the peak degradates' concentrations are likely to be below 0.01 ppm.

A study, providing marginally supplemental data ( bare ground soils in CA, GA, and MI) appears to indicate that dissipation in the field is very rapid (~ 1 2 days). The test substance was pyrethrum extract ( mixture of pyrethrins I and pyrethrins II). The results appear to confirm what would be expected from the laboratory studies.  33 2. Measures of Aquatic Exposure Pyrethrins applied aerially could contaminate shallow surface water through spray drift, or runoff and erosion events which might occur shortly after application. In shallow, sunlit, surface water bodies, the primary route of dissipation could be aqueous photolysis ( t ½ = 11.8 hours); however, pyrethrins are also expected to rapidly adsorb to suspended solids and accumulate into the sediments. In aquatic environments, pyrethrins are moderately persistent under aerobic metabolism ( t ½ = 10.5 days), but more persistent under anaerobic conditions ( t ½ = 86.1 days); pyrethrins are hydrolytically stable at pH 5 and 7, but have a hydrolysis half life of about 14 days at pH 9. Given the fate of this chemical, and assuming the sediments are relatively anoxic, there is potential for pyrethrin to persist in the sediments where it might pose a risk to sediment dwelling organisms. Based on its octanol/ water partition coefficient ( KOW = 794,000), pyrethrin would be expected to bioaccumulate substantially. However, pyrethrin 1 accumulated only moderately in fish ( 127x for the edible tissues, 873x for the nonedible tissues, and 471x for whole fish). It appears that fish have the ability to metabolize low concentrations of pyrethrin to water soluble degradates which are then excreted. Depuration was rapid; by day 1, 77% of the accumulated [ 14C] residues were eliminated from the edible tissues, 66% from the nonedible tissues, and 68% from the whole fish.

Acute studies on aquatic organisms show that pyrethrins are very highly toxic to freshwater fish ( 96 hour LC50= 3.2 : g/ L) and aquatic invertebrates ( daphnid 48 hour EC50 = 6.7 : g/ L) at levels well below the water solubility of this chemical.

a. Aquatic Exposure Modeling for Agricultural Crops Modeling of Agricultural Crops: To determine aquatic ecological risks associated with agricultural uses of pyrethrins, estimated environmental concentrations ( EECs) in surface water were modeled using the Tier II model PRZM ( Pesticide Root Zone Model, version 3.12 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. With this aquatic model, it is assumed that the receiving body of water, the EXAMS standard pond, is adjacent to the treated field, the direction of the spray drift is towards the pond and both the runoff and the spray drift mix quickly in the pond, also, there is no flow in the pond. These assumptions of PRZM/ EXAMS apply in all cases in this report.

The following 13 PRZM field scenarios were modeled: ID potato, ME potato, CA onion, OR snapbeans, PA tomato, FL citrus, NC apple, GA peaches, ND wheat, IL corn, MN alfalfa, CA grapes, MS cotton. The Master Label provides all the crops on which pyrethrin can be applied. They are divided into crop groups which agree with EPA's classification procedures. There are 19 crop groups plus three additional special crop groups ( Suptropical Fruits, Oriental Vegetables, and Miscellaneous Crops), with crops that could not be categorized along with the others. Probably hundreds of crops are listed in the Master Label ( refer to Table 3 for a sinopsis of the agricultural crops listing). The 13 crop or field scenarios were selected with PRZM/ EXAMS to represent, not only this wide variety of crops, but the ample geographical regions of the continental US. The 13 crop scenarios represent the Crop Groups 1, 3, 7, 8, 10, 11, 12, 15, 16, 18, and Miscellaneous  34 Crops ( cotton).

EECs for ecological risk assessment were determined using a Mississippi Pond modeling scenario which describes a generic scenario for the EXAMS component of the modeling exercise. Table 5 summarizes the input parameter values used to run PRZM/ EXAMS. The three critical application variables required for this assessment are the ( 1) maximum application rate; ( 2) number of applications per year, and ( 3) interval between applications. The maximum application rate of 0.05 lbs a. i./ A, maximum number of applications ( 10), and minimum interval between applications ( 1 day, which applies when there is extreme pest pressure) was used for modeling all crop uses, based on the product label ( Table 3). In addition, for selected crops, runs were made with the interval between applications of 3 days ( normal pest pressure). The variability in the EECs for the different standard scenarios reflect effects of the environmental setting of the scenario including soil properties and weather, rather than the agricultural characteristics and chemical properties which are consistent across scenarios. For certain crop scenarios, additional special runs were performed in which the value of spray drift was set at 0% to determine if spray drift is an important component of the EECs for those crops ( by comparison with the standard run).

Table 5. Input variables and parameter values for PRZM/ EXAMS.

Input Variable Parameter Value Source Molecular weight Pyrethrin 1: 328.4 g/ mol Water solubility ( 20 ° C) 2.0 ppm Maximum solubility, Tomlin, C. D. S., Pesticide manual ( TOXNET)

10x available value as per EFED Model Input Guidance, Version II ( 2002)

Vapor pressure Pyrethrin 1: 2.03 x 10 5 mm Hg Tomlin, C. D. S., Pesticide manual ( TOXNET)

Henry's Law constant Pyrethrin 1: 7.7 x 10 7 atm m3/ mol Estimated value from EPISUITE Hydrolysis t ½ , pH 7 ( 25 ° C) pH 5: stable pH 7: stable pH 9: 17 days MRID 43567502 Spray drift fraction 0.05 EFED Model Input Guidance, Version II ( 2002)

Application efficiency 0.95 EFED Model Input Guidance, Version II ( 2002)

Aerobic soil metabolism t ½ ( 3 times available value) 28.5 days MRID 43499803 Aerobic aquatic metabolism t ½ ( 3 times available value) 31.5 days MRID 43499802 Anaerobic aquatic metabolism t ½ 86 days MRID 43499801 Table 5. Input variables and parameter values for PRZM/ EXAMS.

Input Variable Parameter Value Source  35 Direct aqueous photolysis t ½ 0.5 day MRID 43567601 Koc 35,170 Average Value. MRID 43096603, EFED Model Input Guidance, Version II ( 2002)

PLDKRT ( foliage pesticide half life) 0 days EFED Model Input Guidance, Version II ( 2002)

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

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

PLVKRT ( pesticide decay rate on plant foliage) 0/ day EFED Model Input Guidance, Version II ( 2002)

IPSCND ( condition for disposition of foliar pesticide after harvest) 3 PRZM Version 3.0 User's Manual ( Carsel 1998)

CAM ( chemical application method) 2 PRZM Version 3.0 User's Manual ( Carsel 1998)

UPTKF ( plant uptake factor) 0 EFED Model Input Guidance, Version II ( 2002)

DAIR ( diffusion coefficient for pesticide in the air) 0 PRZM Version 3.0 User's Manual ( Carsel 1998)

ENPY ( enthalpy of vaporization of pesticide) Not reported

Benthic layer 5 cm EXAMS Default CROP MANAGEMENT Standard scenarios ID potato, ME potato, CA onion, OR snapbeans, PA tomato, FL citrus, NC apple, GA peaches, ND wheat, IL corn, MN alfalfa, CA grapes, MS cotton Application rate ( kg a. i./ ha/ application) All scenarios: 0.056 For TYPICAL APPLICATION RATE: ID potato 0.0224 PA tomato 0.0067 CA onion 0.0146 OR snap beans 0.0235 Product label  Typical data obtained from various sources and provided to EFED by BEAD, Table 5. Input variables and parameter values for PRZM/ EXAMS.

Input Variable Parameter Value Source  36 Number of applications All scenarios: 10 For TYPICAL APPLICATION RATE: ID potato 1 PA tomato 2 CA onion 2 OR snap beans 5 Product label  No data were available on number of applications for beans; therefore, the EFED used a conservative value of 5.

Interval between applications ( days) a All scenarios: 1 For TYPICAL APPLICATION RATE, and selected crops, 3 Product label Date of first application All scenarios: 1 June Pyrethrin can be applied at any time of the year, when there is pest pressure.

Application type and depth of incorporationa ( cm) Aerial/ 0.0/ 1 day Interval between applications ( days) a The Agency has modeled the maximum and typical application rates for pyrethrin ( Table 6). The range of peak daily EECs ( maximum rate) for all 13 scenarios is 0.35 2.77 : g/ L, while for typical application rate can result in peak daily EEC's of 0.0017  0.056 ug/ L. Special runs with 3 day intervals between applications were also considered by the Agency and show that the standard scenario with the highest EECs is Illinois Corn. The modeled values for maximum application rate show that the scenarios with the highest EEC's were Maine Potatoes, Pennsylvania Tomatoes, and the Mississippi Cotton.

Table 6. Surface water EECs from PRZM/ EXAMS ( ppb) for ecological risk assessment based on pyrethrins use on several crops.

Crop App. rate ( kg/ ha) No. of app./ int between applicat. ( days) Peak 96 Hour 21 Day 60 Day 90 Day Annual IL corn 0.056 10/ 1 2.766 1.410 0.598 0.374 0.314 0.158 ME potato 0.056 10/ 1 1.353 0.817 0.387 0.284 0.250 0.146 MS cotton 0.056 10/ 1 1.906 0.982 0.411 0.279 0.232 0.087 PA tomato 0.056 10/ 1 1.514 0.742 0.336 0.204 0.181 0.089 Table 6. Surface water EECs from PRZM/ EXAMS ( ppb) for ecological risk assessment based on pyrethrins use on several crops.

Crop App. rate ( kg/ ha) No. of app./ int between applicat. ( days) Peak 96 Hour 21 Day 60 Day 90 Day Annual  37 ND wheat 0.056 10/ 1 0.683 0.366 0.228 0.134 0.112 0.058 CA onion 0.056 10/ 1 0.777 0.462 0.248 0.125 0.097 0.038 NC apple 0.056 10/ 1 0.607 0.371 0.233 0.131 0.114 0.056 OR snapbeans 0.056 10/ 1 0.452 0.340 0.186 0.102 0.083 0.042 ID potato 0.056 10/ 1 0.366 0.293 0.165 0.085 0.067 0.033 MN alfalfa 0.056 10/ 1 0.362 0.292 0.163 0.083 0.066 0.032 FL citrus 0.056 10/ 1 0.401 0.296 0.175 0.092 0.073 0.028 GA peaches 0.056 10/ 1 0.656 0.424 0.189 0.096 0.073 0.031 CA grapes 0.056 10/ 1 0.348 0.279 0.149 0.071 0.055 0.021 SPECIAL RUNS WITH 3 DAY INTERVAL BETWEEN APPLICATIONS ( 3 days, normal pest pressure)

IL corn 0.056 10/ 3 2.402 1.168 0.501 0.334 0.285 0.151 ID potato 0.056 10/ 3 0.208 0.140 0.122 0.080 0.065 0.033 CA onion 0.056 10/ 3 0.392 0.229 0.156 0.092 0.071 0.028 TYPICAL APPLICATION RATE, NUMBER OF APPLICATIONS, AND INTERVAL BETWEEN APPLICATIONS Crop App. Rate ( Kg a. i./ ha) No of app./ interval between app. Peak 96 Hour 21 Day 60 Day 90 Day Annual ID potato 0.0224 1/( N/ A) 0.052 0.024 0.007 0.003 0.003 0.001 Table 6. Surface water EECs from PRZM/ EXAMS ( ppb) for ecological risk assessment based on pyrethrins use on several crops.

Crop App. rate ( kg/ ha) No. of app./ int between applicat. ( days) Peak 96 Hour 21 Day 60 Day 90 Day Annual 1 Curry, K. K, and Brookman, D. J. " Pyrethrins Master Label" An unpublished document sponsored by the Pyrethrin Joint Venture c/ o Consumer Specialty Products Association, Inc., Report No. PJV 03 01, 84 p., no MRID.

2 AgDRIFT ® is a computer program provided by the Agency's OPP, as a product of the Cooperative Research and Development Agreement ( CRADA), between the EPA's Office of Research and Development, and the Spray Drift Task Force ( SDTF, a coalition of pesticide registrants formed to develop a comprehensive database of off target drift information in support of pesticide registration requirements).

 38 PA tomato 0.0067 2/ 3 0.033 0.017 0.008 0.005 0.004 0.002 CA onion 0.0146 2/ 3 0.042 0.022 0.008 0.004 0.003 0.001 OR snap beans 0.0235 5/ 3 0.094 0.056 0.038 0.021 0.017 0.009 Effect of Spray Drift and Buffer Zones: The extent to which spray drift may be an important component of the concentration of pyrethrin reaching bodies of water adjacent to treated areas after their application, was investigated. There are numerous pyrethrin labels. The Pyrethrin Joint Venture, however, provided a document entitled " Pyrethrins Master Label," 1 which summarizes all the uses of pyrethrin, application types and equipment, specific restrictions, etc. Pyrethrin can be used on hundreds of crops as shown in Table 3. According to the Master Label there are 19 formulation types, and 45 application equipment types for pyrethrin products used for agricultural purposes. Equipment types include examples such as fixed wing aircraft, and helicopter.

The Master Label gives no indication that there are buffer zones established between the treated areas and adjacent bodies of water to minimize the level of spray drift. The following restrictions are found:

C " Aerial applications: do not apply less than two gallons of diluted solution per acre to field crops or less than 10 gallons of diluted solution per acre to orchard crops."

C " Do not wet plants to point of runoff or drip."

C " Do not apply directly to water, or to areas where surface water is present, or to intertidal areas below the mean high water mark." The label does not establish a range of droplet sizes, boom height, or wind speed.

Traditionally, the EFED has used a default level of spray drift for aerial applications of 5%. It would be useful to compare this value to the data from AgDRIFT ® 2. A cursory review of the AgDRIFT ® data indicates that the " standard" level of 5% spray drift is adequate for ASAE Coarse to Very Coarse and ASAE Medium to  39 Coarse sprays, but the level may be an underestimation for ASAE Fine to Medium and ASAE Very Fine to Fine sprays.

EFED selected two scenarios, GA peaches and ID potatoes. Both crops yielded relatively low EECs. Furthermore, one crop scenario ( GA peaches) is representative of orchards, and the other ( ID potatoes) is representative of other agricultural crops and these scenarios are located in opposite sides of the nation. First, EFED ran PRZM/ EXAMS for these crops ( plus two other selected crops) with the same standard input parameters as the original runs, except that the spray drift level was set to 0% instead of 5%. It is noted that of the 13 scenarios ran by EFED, some will be driven by runoff, while others will be driven by spray drift, depending on weather conditions, soil type and porosity, site slope, interception, and other factors.

Table 7 provides the peak EECs for theoretical applications where spray drift is 0%. It is noted that for FL citrus and GA peaches, the peak EECs decreased by almost a half, while for ID potato, and CA grapes, the peak EECs decreased substantially more. For all these crop scenarios, spray drift is an important component of the peak EEC. By comparison of the EECs generated with the standard run ( 5% drift) and the special run ( 0%) drift, the percentage of the peak EEC attributable to spray drift can be calculated ( see Table 6b). This percentage is around 45% for FL citrus and GA peaches, and > 88% for ID potato and CA grapes. Therefore, drift is an important component of the peak EECs for the four selected crops.

Table 7. Surface water EECs from PRZM/ EXAMS ( ppb) for ecological risk assessment based on pyrethrins use on selected crops, compared to same crops with Spray Drift set to 0%. The regular runs are presented for comparison purposes only.

Crop Peak EEC STANDARD RUNS, WITH SPRAY DRIFT SET TO 5%

ID potato 0.366 FL citrus 0.401 GA peaches 0.656 CA grapes 0.348 SPECIAL RUNS WITH SPRAY DRIFT SET TO 0%, Concentration / % attributable to spray drift ID potato 0.042 / 88.5 FL citrus 0.221 / 44.9 GA peaches 0.344 / 47.6 CA grapes 0.021 / 94.0 Second, for the two selected scenarios, standard PRZM/ EXAMS runs were performed simulating ground applications, for comparative purposes. Then, since pyrethrin yielded RQs that exceeded the levels of concern for certain aquatic organisms, a number of PRZM/ EXAMS models were run, to anticipate the possible effect of buffer zones of up to 150 ft. The level of spray drift was determined with the help of AgDRIFT ® . Since the Master Label for pyrethrin does not indicate most of the conditions for the aerial applications ( except for  40 spray volume), EFED bracketed the options by running a " high end" ( worst case) and a " low end" ( best case) scenarios. Essentially, they are described as follows:

Table 8. Drift Scenarios High End Drift Scenario Low End Drift Scenario high release height, 15 ft low release height, 8 ft high wind speed, 15 mph low wind speed, 3 mph small droplets, ASAE Very Fine droplets ( DV0.5 = 81.52 : m) large droplets, ASAE Medium to Coarse droplets ( DV0.5 = 340.86 : m)

The estimation of the level of spray drift is considered a Tier II Aerial calculation in AgDRIFT ® ; however, all possible AgDRIFT ® parameters were kept at their default levels for simplicity. Two sets of values were generated using a spray volume of 10 gal. ( spray volume for orchards), and 2 gal. ( spray volume for other crops), with buffer zones of 0, 50, 100, 150 ft. The output value of concern is the spray drift fraction. These results are summarized in Table 6c, and the inputs/ outputs of AgDRIFT ® and PRZM/ EXAMS appear in Appendix O.

Table 9 presents the EECs for two selected crops with modeled standard ground and aerial applications, theoretical aerial application with no spray drift ( partial results also presented in Table 7), and modeled aerial runs with buffer zones and high end ( worst case) drift scenario and low end ( best case) drift scenario. As expected, the low end scenario resulted in substantially lower EECs. It was noted also that for both crops, the levels of spray drift also decreased, in some cases substantially with the low end drift scenario. The results of the ground application and the low end drift scenario with a large buffer zone yielded EECs of the same order of magnitude. For example, the peak EEC of the low end ( best case) drift scenario of the ID potato ( 0.087 ppb, buffer zone 100 ft) was similar to the peak EEC of the same crop applied by ground methods ( 0.082 ppb).

Table 9. Surface water EECs ( ppb) for ecological risk assessment based on pyrethrin use on GA peaches and ID potatoes, and buffer zones of 50, 100, and 150 ft. Results using average KOC = 35,170 Crop Peak EEC ( ppb) 21 day EEC ( ppb) 60 day EEC ( ppb)

Standard Aerial Run, With Spray Drift Set To 5%

Georgia Peaches 0.656 0.189 0.096 Idaho Potatoes 0.366 0.165 0.085 Special Run, With Spray Drift Set To 1%, Ground Application Georgia Peaches 0.421 0.078 0.042 Idaho Potatoes 0.082 0.038 0.020 Table 9. Surface water EECs ( ppb) for ecological risk assessment based on pyrethrin use on GA peaches and ID potatoes, and buffer zones of 50, 100, and 150 ft. Results using average KOC = 35,170 Crop Peak EEC ( ppb) 21 day EEC ( ppb) 60 day EEC ( ppb)

 41 Special Run, With Spray Drift Set To 0%

Georgia Peaches 0.344 0.054 0.028 Idaho Potatoes 0.042 0.006 0.004 High end, release height 15 ft, wind speed 15 mph, very fine droplets Buffer Zone 0 ft, 24.0% spray drift for GA peaches/ 31.2% spray drift for ID potatoes Georgia peaches 1.681 0.747 0.359 Idaho Potatoes 2.259 1.002 0.514 Buffer Zone 50 ft, 16.8% spray drift for GA peaches/ 23.1% spray drift for ID potatoes Georgia peaches 1.436 0.535 0.259 Idaho Potatoes 1.673 0.743 0.381 Buffer Zone 100 ft, 12.7% spray drift for GA peaches/ 18.4% spray drift for ID potatoes Georgia Peaches 1.164 0.415 0.202 Idaho Potatoes 1.333 0.596 0.304 Buffer Zone 150 ft, 10.2% spray drift for GA peaches/ 15.4% spray drift for ID potatoes Georgia Peaches 0.998 0.341 0.168 Idaho Potatoes 1.116 0.497 0.255 Low end, release heigh 8 ft, wind speed 3 mph, medium to coarse droplets Buffer Zone 0 ft, 2.8% spray drift for GA peaches/ 3.0% spray drift for ID potatoes Georgia peaches 0.519 0.126 0.065 Idaho Potatoes 0.223 0.101 0.052 Buffer Zone 50 ft, 1.4% spray drift for GA peaches/ 1.5% spray drift for ID potatoes Georgia Peaches 0.431 0.087 0.046 Idaho Potatoes 0.115 0.053 0.028 Buffer Zone 100 ft, 1.1% spray drift for GA peaches/ 1.1% spray drift for ID potatoes Table 9. Surface water EECs ( ppb) for ecological risk assessment based on pyrethrin use on GA peaches and ID potatoes, and buffer zones of 50, 100, and 150 ft. Results using average KOC = 35,170 Crop Peak EEC ( ppb) 21 day EEC ( ppb) 60 day EEC ( ppb)

 42 Georgia Peaches 0.413 0.079 0.042 Idaho Potatoes 0.087 0.041 0.021 Buffer Zone 150 ft, 0.9% spray drift for GA peaches/ 0.8% spray drift for ID potatoes Georgia Peaches 0.400 0.073 0.039 Idaho Potatoes 0.067 0.031 0.016 Based on 1 in 10 year exceedance probability ( 0.10). Peak EEC's provided with three decimal points for information only.

Equilibrium Partitioning and Concentration in the Sediment: The pyrethrins are lipophilic compounds that can adsorb readily to particulate and sediment, thus possibly limiting its exposure to aquatic life in the water column but increasing toxic exposure in the benthos. Sediment can act as a reservoir for lipophilic persistent compounds. The sediment and particulate likely adsorb a high percentage of pyrethrin, as indicated by its high KOC. Therefore, coupled with pyrethrin's persistence in anaerobic environments, sediment bound pyrethrin could present a toxicity risk for benthic aquatic life and aquatic ecosystems in general. Exposure to this sediment can result in a direct impact to aquatic life through respiration, ingestion, dermal contact, as well as indirect impact through alterations of the food chain.

Under the Clean Water Act ( CWA Section 304( a)( 2) the Environmental Protection Agency ( EPA) and the States are expected to develop programs for protecting the chemical, physical, and biological integrity of the nation's waters. In order to meet the objectives of the CWA, EPA has periodically issued ambient water quality criteria ( WQC). However, toxic contaminants in bottom sediments of lakes, rivers, wetlands, and coastal waters create potential for environmental degradation even if water column contamination values are low and comply with EPA's water quality criteria. In order to evaluate this possible concern the USEPA's Office of Water ( OW) also calculates Equilibrium Partitioning Sediment Guidelines ( ESG).