# Risks of Dicofol Use to Federally Threatened California Red-legged Frog (

Rana aurora draytonii )

Pesticide Effects Determination

Environmental Fate and Effects Division Office of Pesticide Programs Washington, D.C. 20460

June 15, 2009

1Primary Authors: Kristina Garber, Biologist Charles Peck, Environmental Scientist

Secondary Reviewers: Thomas Steeger, Senior Biologist R. David Jones, Se nior Agronomist

Branch Chief, Environmental Risk Assessment Branch 4: Elizabeth Behl

2Table of Contents

1.0 Executive Summary.................................................................................................. 10 2.0 Problem Formulation ............................................................................................... 18 2.1. Purpose................................................................................................................... 18 2.2. Scope...................................................................................................................... 20 2.3. Previous Assessments............................................................................................ 21 2.4. Stressor Source and Distribution ........................................................................... 22 2.4.1. Environmental Fate Assessment..................................................................... 22 2.4.2. Environmental Transport Assessment ............................................................ 26 2.4.3. Mechanism of Action...................................................................................... 28 2.4.4. Use Characterization....................................................................................... 28 2.5. Assessed Species.................................................................................................... 32 2.5.1. Distribution ..................................................................................................... 33 2.5.2. Reproduction................................................................................................... 35 2.5.3. Diet.................................................................................................................. 35 2.5.4. Habitat............................................................................................................. 36 2.6. Designated Critical Habitat.................................................................................... 37 2.7. Action Area............................................................................................................ 39 2.8. Assessment Endpoints and Measures of Ecological Effect ................................... 42 2.8.1. Assessment Endpoints for the CRLF.............................................................. 42 2.8.2. Assessment Endpoints for Desi gnated Critical Habitat.................................. 45 2.9. Conceptual Model.................................................................................................. 47 2.9.1. Risk Hypotheses.............................................................................................. 47 2.9.2. Diagram........................................................................................................... 48 2.10. Analysis Plan ....................................................................................................... 49 2.10.1. Measures of Exposure................................................................................... 50 2.10.2. Measures of Effect ........................................................................................ 52 2.10.3. Integration of Exposure and Effects ............................................................. 53 2.10.4. Data Gaps...................................................................................................... 53 3.0 Exposure Assessment................................................................................................ 54 3.1. Label Application Rates and Intervals................................................................... 54 3.2. Aquatic Exposure Assessment............................................................................... 56 3.2.1. Modeling Approach ........................................................................................ 56 3.2.2. PRZM Scenarios ............................................................................................. 58 3.2.3. Model Inputs ................................................................................................... 61 3.2.4. Model Results ................................................................................................. 63 3.2.5. Available Monitoring Data ............................................................................. 65 3.3. Aquatic Bioaccumulation Assessment................................................................... 66 3.3.1. Estimated BCF values..................................................................................... 67 3.3.2. Empirical BCF data......................................................................................... 67 3.3.3. Bioaccumulation modeling ............................................................................. 68 3.4. Terrestrial Animal Exposure Assessment.............................................................. 70 3.4.1. Modeling Approach ........................................................................................ 70 3.4.1. Field Studies.................................................................................................... 73 3.5. Accumulation of Dicofol Residues on Soil ........................................................... 74

33.6. Terrestrial Bioaccumulation Assessment............................................................... 76 4.0 Effects Assessment .................................................................................................... 77 4.1. Toxicity of dicofol to aquatic organisms ............................................................... 78 4.1.1. Toxicity of Dicofol to Freshwater Fish........................................................... 79 4.1.2. Toxicity of Dicofol to Fr eshwater Invertebrates............................................. 81 4.1.3. Toxicity of Dicofol to Aquatic Plants............................................................. 81 4.2. Toxicity of Dicofol’s Degrad ates to Aquatic Organisms ...................................... 81 4.2.1. Toxicity of Dicofol’s Degradates to Aquatic Animals ................................... 81 4.2.2. Toxicity of Dicofol’s Degradates to Aquatic Plants....................................... 82 4.3. Toxicity of dicofol to terrestrial organisms ........................................................... 83 4.3.1. Toxicity of Dicofol to Birds............................................................................ 84 4.3.2. Toxicity of Dicofol to Mammals .................................................................... 87 4.3.3. Toxicity of Dicofol to Te rrestrial Invertebrates.............................................. 87 4.3.4. Toxicity of Dicofol to Terrestrial Plants......................................................... 87 4.4. Toxicity of dicofol degradates to terrestrial organisms ......................................... 88 4.5. Incident Database Review for Dicofol................................................................... 88 5.0 Risk Characterization............................................................................................... 89 5.1. Risk Estimation...................................................................................................... 89 5.1.1. Exposures in the Aquatic Habitat ................................................................... 90 5.1.2. Exposures in the Terrestrial Habitat ............................................................... 96 5.1.3. Primary Constituent Elements of Designated Critical Habitat ....................... 98 5.2. Risk Description .................................................................................................. 100 5.2.1. Direct Effects ................................................................................................ 105 5.2.2. Indirect Effects (through effects to prey)...................................................... 113 5.2.3. Indirect Effects (through effects to habitat).................................................. 121 5.2.4. Primary Constituent Elements of Designated Critical Habitat ..................... 122 5.2.5. Area of Effects .............................................................................................. 122 5.2.6. Description of Assumptions, Li mitations and Uncertainties ........................ 126 5.2.7. Addressing the Risk Hypotheses .................................................................. 138 6.0 Risk Conclusions ..................................................................................................... 139 7.0 References................................................................................................................ 1 44

Appendices

Appendix A. Structures of dico fol and its major degradates Appendix B. Intersection of Dicofol Use Ar ea and California Red-legged frog Habitat Appendix C. The Risk Quotient Method and Levels of Concern Appendix D. Treated area estima te for outside building usage Appendix E. Example PRZM/EXAMS I nput Files and Output File Data Appendix F. DDT Characterization Appendix G. Outputs from KABAM v.1.0 Appendix H. Example output from T-REX v.1.4.1 Appendix I. List of citations accep ted and rejected by ECOTOX criteria Appendix J. Detailed spreadsheet of availa ble ECOTOX open literature for dicofol Appendix K. Summary of human he alth effects data for dicofol Appendix L. Sensitivity distributions for acute exposures of fish and birds to dicofol

4Appendix M. Example output from analysis of likelihood of individual mortality Appendix N. Example output from T-HERPS v.1.0 Appendix O. Use of fugacity approach to estimate exposures to small mammals consuming earthworms contaminated with dicofol from soil of treatment sites Appendix P. Ultra Low Volume Spray Drift Approach

Attachments

Attachment 1: Status and Life Hist ory of California Red-legged Frog Attachment 2: Baseline Status and Cumulativ e Effects for the California Red-legged Frog

List of Tables Table 1. Description of evidence supporting effects determination for dicofol use in California. Assessment endpoints include survival, growth and reproduction of CRLF individuals. ...................................................................................... 14 Table 2. Summary of effects determination for CRLF critical habitat based on uses of dicofol in California........................................................................................ 16 Table 3. Summary of dicofol envi ronmental fate properties. ........................................... 25 Table 4. Summary of dicofol degradates observed in submitted environmental fate studies for dicofol. Data represent % of total residue detected as specific degradate and study day residues were measured. .......................................................... 26 Table 5. Methods and rates of application of currently registered uses of dicofol in California 1 ....................................................................................................... 28 Table 6. Summary of California Department of Pesticide Registration (CDPR) Pesticide Use Reporting (PUR) data and calculat ed annual application rates (1999 - 2006) for currently registered dicofol uses. 1 ................................................... 32 Table 7. Assessment endpoints and measures of ecological effects for dicofol............... 44 Table 8. Summary of dicofol assessment endpoi nts and measures of ecological effect for primary constituent elements of designated critical habitat 1 . ......................... 46 Table 9. Dicofol uses and application in formation for the CRLF risk assessment 1 . ........ 55 Table 10. Summary of PRZM/EXAMS environmen tal fate data used for aquatic exposure inputs for o,p’ -dicofol. 1 .................................................................................. 61 Table 11. Summary of PRZM/EXAMS environmen tal fate data used for aquatic exposure inputs for p,p' -dicofol. 1 .................................................................................. 62 Table 12. Aquatic EECs ( μ g/L) for Dicofol Uses in California, Total o,p ’ and p,p ’ Isomers............................................................................................................ 63 Table 13. Aquatic EECs ( μ g/L) for Dicofol, Parent and De gradate Uses in California... 64 Table 14. Characteristics of model aquatic or ganisms used to derive BCF values. ......... 67

5Table 15. Estimated BCF values for pare nt dicofol in aquatic organisms........................ 67 Table 16. Concentrations of dicofol parent in tissues of aquatic organisms (estimated using KABAM)............................................................................................... 68 Table 17. Estimated Log Kow values of dicofol's residues of concern............................ 69

Table 18. Concentrations of dicofol total re sidues of concern in tissues of aquatic organisms (μg/kg-ww; estimated using KABAM). Concentrations were estimated using Log Kow values repres entative of the different dicofol residues of concern. ........................................................................................ 69 Table 19. Input parameters to T-REX used to generate dicofol EECs for terrestrial animals. ........................................................................................................... 70 Table 20. Upper-bound Kenega Nomogram EECs for Dietary- and Dose-based Exposures of the CRLF and its Prey to Single Applications of dicofol for Current Uses in California. ............................................................................. 72 Table 21. Dicofol EECs (ppm) for Indirect E ffects to the Terrestrial-Phase CRLF via Effects to Terrestrial Inve rtebrate Prey Items................................................. 73 Table 22. Freshwater toxicity profile for dicofol.............................................................. 79 Table 23. Categories of acute toxi city for aquatic organisms........................................... 79 Table 24. Acute toxicity data (96-h LC 50 ) for freshwater fish exposed to dicofol. .......... 80 Table 25. Chronic toxicity data for fre shwater fish exposed to dicofol............................ 80 Table 26. Estimated acute and chronic toxicity values (μg/L) for fish and daphnids exposed to dicofol and its degradates (as calculated by ECOSAR). .............. 82 Table 27. Terrestrial toxicity profile for dicofol............................................................... 83 Table 28. Categories of acute toxicity for avian and mammalian studies. ....................... 84 Table 29. Subacute dietary toxicity data (LC 50 ) for birds exposed to dicofol. ................. 84 Table 30. Chronic toxicity data fo r birds exposed to dicofol. .......................................... 85 Table 31. Acute and chronic RQs for aqua tic-phase CRLF resulting from AERIAL applications of dicofol. EECs are base d on parent and degradates of concern. ......................................................................................................................... 90 Table 32. Acute and chronic RQs for aqua tic-phase CRLF resulting from GROUND applications of dicofol. EECs are base d on parent and degradates of concern. ......................................................................................................................... 91 Table 33. Acute and chronic RQs for a quatic-phase CRLF resulting from ULV applications of dicofol. EECs are base d on parent and degradates of concern. ......................................................................................................................... 91 Table 34. Diet assumptions of small, medi um and large aquatic-phase CRLF used in KABAM.......................................................................................................... 92

6Table 35. Acute and chronic RQs for aquatic- phase CRLF exposed to dicofol (parent) through consumption of aquatic organi sms which have accumulated dicofol. ......................................................................................................................... 92 Table 36. Acute and chronic RQs for aquatic invertebrates resulting from AERIAL applications of dicofol. EECs are base d on parent and degradates of concern. ......................................................................................................................... 93 Table 37. Acute and chronic RQs for aquati c invertebrates resulting from GROUND applications of dicofol. EECs are base d on parent and degradates of concern. ......................................................................................................................... 94 Table 38. Acute and chronic RQs for aqua tic invertebrates resulting from ULV applications of dicofol. EECs are base d on parent and degradates of concern. ......................................................................................................................... 94 Table 39. Acute and chronic, dietary-based RQ s and dose-based RQs for direct effects of dicofol to the terrestrial-phase CRL F. RQs calculated using T-REX............. 96 Table 40. RQs for determining indirect eff ects to the terrestrial-phase CRLF through effects to potential prey items, specifically small terrestrial mammals consuming short grass..................................................................................... 98 Table 41. Risk estimation summary for dicofol - direct and indirect effects to the CRLF. ....................................................................................................................... 101 Table 42. Risk estimation summary for dicofol – PCEs of designated critical habitat for the CRLF....................................................................................................... 102 Table 43. Acute RQs and for aquatic-phase CRLF resulting from applications of dicofol. EECs are based on parent and degradates of concern................................... 106 Table 44. Acute and chronic RQs for aqua tic-phase CRLF resulting from AERIAL applications of dicofol. EECs ar e based on parent dicofol only. .................. 107 Table 45. Acute and chronic RQs for aqua tic-phase CRLF resulting from GROUND applications of dicofol. EECs are based on dicofol only.............................. 107 Table 46. Acute and chronic RQs for a quatic-phase CRLF resulting from ULV applications of dicofol. EECs ar e based on parent dicofol only. .................. 108 Table 47. Refined dose-based RQs 7 for 1.4 g CRLF consuming different food items. EECs calculated using T-HERPS. ................................................................ 109 Table 48. Revised dose-based RQs 7 for 37 g CRLF consuming different food items. EECs calculated using T-HERPS. ............................................................. 110 Table 49. Revised dose-based RQs 7 for 238 g CRLF consuming different food items. EECs calculated using T-HERPS. ................................................................ 111

Table 50. Revised acut e dietary-based RQs 7 for CRLF consuming different food items. EECs calculated using T-HERPS. ................................................................ 112 Table 51. Revised chronic dietary-based RQs 7 for CRLF consuming different food items. EECs calculated using T-HERPS. ................................................................ 113

7Table 52. Acute RQs and associated like lihood of individual effects for aquatic invertebrates resulting from applications of dicofol. EECs are based on parent and degradates of concern............................................................................. 114 Table 53. Acute and chronic RQs for aquatic invertebrates resulting from AERIAL applications of dicofol. EECs are based on dicofol only.............................. 115 Table 54. Acute and chronic RQs for aquati c invertebrates resulting from GROUND applications of dicofol. EECs are based on dicofol only.............................. 115 Table 55. Acute and chronic RQs for aqua tic invertebrates resulting from ULV applications of dicofol. EECs are based on dicofol only.............................. 116 Table 56. Acute RQs and likelihood of individua l mortality for fish and aquatic-phase amphibians resulting from applications of dicofol. EECs are based on parent and degradates of concern............................................................................. 117 Table 57. RQs 7 and associated likelihood of individual effects to terrestri al invertebrates due to dicofol exposures. .............................................................................. 118 Table 58. Acute dose-based RQs and associated likelihood of individual effects to small terrestrial mammals (consuming short gr ass) due to dicofol exposures....... 119 Table 59. Acute dose-based RQs 7 for terrestrial-phase frogs (prey) exposed to dicofol.120 Table 60. Acute dietary-based RQs for terres trial-phase frogs (prey) consuming small insects and likelihood of individual effects chance resulting from dicofol exposures. RQs calculated using T-HERPS. ................................................ 121 Table 61. Summary of CDPR pesticide use reporting by county for dicofol (annual pounds of dicofol applied from 1999 to 2006). ............................................ 124 Table 62. Single application rate not exceedi ng acute LOC for diet ary- and dose-based exposures of the CRLF to dicofol................................................................. 126 Table 63. Physicochemical and environmental fa te properties used as input for estimating overall persistence and long-range tran sport potential usi ng the OECD Tool. ....................................................................................................................... 132 Table 64. Overall persistence a nd characteristic travel di stances generated using the OECD Tool. .................................................................................................. 132 Table 65. Description of evidence supporting ef fects determination for dicofol use in California. Assessment endpoint is su rvival, growth and reproduction of CRLF individuals.......................................................................................... 140 Table 66. Summary of effects determination for CRLF critical habita t based on uses of dicofol in California...................................................................................... 142

List of Figures Figure 1. Chemical Structures for o,p' - and p,p' -dicofol. ................................................. 11 Figure 2. Estimated national agricultural use of dicofol for 2002. ................................... 30

8Figure 3. Recovery unit, core area, critical habitat, and occurrence designations for CRLF............................................................................................................... 34 Figure 4. CRLF reproductive events by month. ............................................................... 35 Figure 5. Initial area of concern for crops described by agricultural landcover which corresponds to potential di cofol use sites. This map represents the area potentially directly affect ed by the federal action........................................... 41 Figure 6. Conceptual model for dicofol e ffects on aquatic-phase of the CRLF. .............. 48 Figure 7. Conceptual model for dicofol eff ects on terrestrial phase of the CRLF............ 49 Figure 8. Summary of applications of dicofo l to cotton in 2004 from CDPR PUR data. 58 Figure 9. Concentration of total residues of dicofol in soil treated with dicofol for 30 years. X axis represents time in days. Soil modeled in PRZM using CA strawberries and CA fruit scenarios................................................................ 75 Figure 10. Concentration of total residues of di cofol in pore water of soil treated with dicofol for 30 years. X axis represents time in days. Soil modeled in PRZM using CA strawberries and CA fruit scenarios................................................ 75 Figure 11. Intersection between dicofo l use areas and CRLF habitat. ........................... 123 Figure 12. Genus sensitivity distribution for acute (96-h) exposures of fish to dicofol. 135 Figure 13. Species sensitivity distribution for su bacute exposures of birds to dicofol... 136

9

### 1.0 Executive Summary

The purpose of this assessment is to evaluate potential direct and i ndirect effects on the California red-legged frog (Rana aurora draytonii ) (CRLF) arising from Federal Insecticide, Fungicide, Rode nticide Act (FIFRA) regulatory actions regarding use of dicofol on agricultural and non-ag ricultural sites. In additi on, this assessment evaluates whether these actions can be expected to result in effects to the species’ designated critical habitat. This assessment was completed in accordance with the U.S. Fish and Wildlife Service (U.S. FWS) and National Marine Fisheries Service (NMFS) Endangered Species Consultation Handbook (U.S. FWS/NMFS 1998) and procedures outlined in the Agency’s Overview Document (U.S. EPA 2004).

The CRLF was listed as a threatened spec ies by U.S. FWS in 1996. The species is endemic to California and Baja California (Mexico) and inhabits both coastal and interior mountain ranges. A total of 243 streams or drainages are believed to be currently occupied by the species, with the greatest numbers in Monterey, San Luis Obispo, and Santa Barbara counties (U.S. FW S 1996) in California.

Dicofol is a broad-spectrum acaricide, insecticide, and miticide, initially registered as a pesticide in 1957. The current technical formul a containing dicofol was reregistered in 1998. The following uses of dicofol are consider ed as part of the federal action evaluated in this assessment: beans (dry, snap, and lima ), citrus (specifically, grapefruit, kumquats, lemons, limes, oranges, tangelos, and tang erines), cotton, cucu rbits (specifically, cantaloupes, cucumbers, melons, pumpki ns, watermelons, and winter and summer squash), grapes, hops, mint, pecans, peppe rs, pome fruits (specifically, apples, crabapples, pears, and quince), stone fruits (specifically, apricots, sweet and sour cherries, nectarines, peaches, plums, and prunes), strawberries, tomatoes, walnuts, bermudagrass, turf/ornamental uses (specifica lly, turf grasses, nursery stock, flowers, shade trees, woody shrubs and vines, and sod farms) and outside building surfaces (nonagricultural).

Dicofol is composed of two isomers, p,p '-dicofol and o,p' -dicofol (see Figure 1 ), that occur at a ratio of 4.5: 1 in formulated end-use products. Based on the available environmental fate data for dicofol, this ch emical and its degradat es are expected to persist with a half-life of up to 313 days, depending upon the specific environmental conditions. Major routes of dissipati on are hydrolysis under neutral and alkaline conditions and aerobic and anaero bic soil metabolism, with the o,p' -isomer degrading more quickly. Dicofol is classified as slightly mobile (Kashuba, et al. 2006). Leaching and photodegradation are not expected to be sign ificant routes of dissi pation of dicofol in the environment. Because of its low vapor pressure (3.9 x 10 -7 torr) and Henry’s Law Constant (1.4 x 10 -7 atm-m 3 /mol), low levels of volatilization are possible, but not expected.

10Figure 1. Chemical Structures for o,p' - and p,p' -dicofol.

Major degradates of dicofol are the o,p '- and p,p ' isomers of dichlorobenzophenone (DCBP); 1, 1-( p -ch1orophenyl-) 2,2-dichloroethanol (FW-152); dichlorobenzhydrol (DCBH); hydroxyl-dichlorobenzophenone (OH-D CBP); and chlorobenzoic acid (CBA). DCBP was identified in the hydrolysis, photolys is and metabolism studies while the other degradates were only presen t in metabolism studies. Ther e are currently no submitted studies addressing the environmental fate an d transport of these major degradates. However, the studies submitted in support of the aerobic soil metabolism indicate a large difference between half lives for dicofol alone (8.5 and 32 days for o,p '- and p,p '-dicofol, respectively) and the half lives for dicofol pl us its degradates (186 and 313 days for total
o,p '- and p,p '-dicofol, respectively).

In order to estimate aquatic exposure concentrations of di cofol and its degradates of concern, separate modeling runs were conducted for the o,p '- and p,p '-dicofol parent and
o,p '- and p,p '-dicofol and degradates. The EECs were then summed to derive an estimate for total parent and the total toxic residue. In this risk assessment, degradates of concern included: DCBP, FW-152, DCBH and OH-DCBP. It is assumed in this assessment that for aquatic animals, the degradates of con cern are of equal toxicity compared to the parent. Additionally, due to reported DDT contamination ( ≤ 0.1%) in dicofol products and the established toxicity and ecological risks of DDT, screening-leve l charaterization of DDT was also considered in this assessment (see Appendix F ).

Since CRLFs exist within aquatic and terrestrial habitats, exposure of the CRLF, its prey and its habitats to dicofol are assessed sepa rately for the two habitats. Tier-II aquatic exposure models (PRZM/EXAMS) are used to estimate high-end exposures of dicofol in aquatic habitats resulting from runoff and spray drift from different uses. Peak modelestimated environmental concentrations result ing from different dicofol uses range from 0.15 to 18.0 μg/L for the total parent ( o,p '- and p,p '-dicofol, respectively) and 0.38 to 59.6 μg/L for the total residues of concern (dic ofol and degradates). These estimates are supplemented with analysis of available Cali fornia surface water monitoring data from the California Department of Pesticid e Regulation. The maximum surface water concentration of dicofol reported in the Ca lifornia Department of Pesticide Regulation surface water database (0.27 μg/L) is roughl y 190 times lower than the highest peak model-estimated environmental concentration.

Based on available bioaccumulation data, dicofo l and its degradates have the potential to accumulate in aquatic organisms. KABAM (K OW (based) A quatic B ioA ccumulation M odel) v.1.0 is used to estimate potential bioaccumulation of dicofol residues in a

11freshwater aquatic food web and subsequent risks these residues pose to aquatic-phase CRLF via consumption of contaminated aquatic prey (i.e., aquatic inve rtebrates and fish).

In order to characteri ze the long range trans port potential (LRTP) of dicofol, the OECD P ov and LRTP Screening Tool was used. Thr ee chemicals known to move via long range transport, DDT, aldrin and endrin, were also modeled to provide a context for dicofol estimated LRTP. Modeling results indicate that dicofol has comparable or higher LRTP estimates than all three chemi cals with known potential to move via long range transport.

The T-REX model is used to estimate dicofo l exposures to terrestrial-phase CRLF, its potential prey, and its designa ted critical habita t resulting from uses involving foliar applications. T-HERPS is used to further characterize exposures of terrestrial-phase CRLF to dietary and dose-based exposures of dicofol resulting from foliar applications. AgDRIFT is also used to estimate deposition of dicofol on terrestrial and aquatic habitats from spray drift.

The effects determination assessment endpoints for the CRLF include direct toxic effects on the survival, reproduction, and growth of th e CRLF itself, as well as indirect effects, such as reduction of the prey base or effects to its habitat. Direct effects to the CRLF in the aquatic habitat are based on toxicity information for freshwater fish, which are generally used as a surrogate for aquatic-phase amphibians. In the terrestrial habitat, direct effects are based on toxi city information for birds, wh ich are used as a surrogate for terrestrial-phase amphibians. Given th at the CRLF’s prey items and designated critical habitat requirements in the aquatic habitat are dependant on the availability of freshwater aquatic invertebrates, toxicity information for these taxonomic groups is also discussed. In the terrestrial habitat, indirect effects due to depleti on of prey are assessed by considering effects to terrestrial insects, small terrestrial mammals, and frogs.

Dicofol is very highly toxic to freshwater fi sh and highly toxic to fr eshwater invertebrates on an acute exposure basis. The no observed adverse effect concentration (NOAEC) for chronic effects to the rainbow trout is 4.4 μg /L, with a lowest observed adverse affect concentration (LOAEC) of 7.9 μg/L based on reduction in growth. Available chronic toxicity data for aquatic i nvertebrates include a NOAEC of 19 μg/L, with a LOAEC of 33 μg/L based on reduction in growth. Dicofol is moderately toxic to birds on an acute oral and subacute dietary exposure basis, and slightly toxic to mammals on an acute oral exposure basis. Dicofol is classified as pr actically nontoxic to hone y bees on an acute contact exposure basis. Chronic exposures of the American kestrel to dicofol indicate effects to number of eggs laid at concentr ations greater than 40 ppm, with a LOAEC of 3 ppm based on decreased egg shell thickness. Chronic exposures of rats to dicofol indicate a NOAEC of 5 ppm, corresponding to a LOAEC of 25 pp m where reproductive effects were observed. The EC 50 for algae exposed to dico fol is greater than 5,000 but less than 10,000 μg/L. No data are available for quantitatively defining an endpoint to represent the effects of dicofol exposures to vascular plants.

Risk quotients (RQs) are derived as quantitativ e estimates of potenti al high-end risk. Acute and chronic RQs are compared to the Agency’s Levels of Concern (LOCs) for

1213 Federally-listed threatened (listed) species to identify if dicofol use within the action area has any direct or indirect effect on the CRLF and its designated critical habitat. For this assessment, RQs were based on EECs represen ting total residues of concern (dicofol, DCBP, FW-152, DCBH and OH-DCBP). Based on estimated environmental concentrations in the aquatic and terrestrial ha bitats resulting from all currently registered uses of dicofol, RQ values exceed the Agency ’s LOC for direct acute and chronic risk to the CRLF; this represents a “may affect” de termination. RQs exceed the LOC for risks to aquatic invertebrates, fish, aquatic-phase amphibians, terrestrial-phase amphibians and mammals. RQ values for terrestrial inverteb rates potentially exceed the LOC for this taxon. RQ values for non-vascular aquatic plants do not exceed the LOC. The effects determination for indirect effects to the CRL F due to effects on its prey base is “may affect.” Due to a lack of effects data for va scular plants exposed to dicofol, potential risk of dicofol to the designated critical ha bitat of the CRLF cannot be quantified and potential indirect effects to the CRLF through effects to its habitat cannot be discounted. Therefore, the determination for indirect eff ects to the CRLF through ef fects to its habitat is “may affect.” In addition, dicofol can potentially result in effects to the CRLF’s aquatic and terrestrial habitats based on potential impacts to its principal constituent elements (PCEs).

Refinement of all “may affect” determinations results in: a “LAA” determination based on direct effects to the aquatic and terrestri al-phase CRLF, indirect effects to the CRLF based on effects to its prey and indirect eff ects to the CRLF based on effects to its habitat (Table 1). Consideration of CRLF critical habitat indicates a determination of “habitat modification” for aquatic and terres trial designated critical habitats ( Table 2 ).Table 1. Description of evidence supporting effects determination for dicofol use in California. Assessment endpoints include survival, growth andreproduction of CRLF individuals.AssessmentEndpointEffectsDeterminationBasis for DeterminationDirect effects toCRLF-Acute RQs for aquatic-phase CRLF exceed the LOC for all usesof dicofol, except Bermudagrass and outside buildings.- Analysis of individual effects indicates that up to 1 in 2 individual CRLF could experience mortality after acute exposures todicofol in the aquatic habitat.- Chronic RQs for aquatic-phase CRLF exceed the LOC for all uses of dicofol, except Bermuda grass, turf and outside buildings.- Chronic EECs in the aquatic environment are abovelevels where growth effects were observed in fish.- Acute and chronic RQs for aquatic-phase CRLF consuming aquatic organisms contaminated with dicofol (resulting fromaccumulation) exceed LOCs.- Refined acute, dose-based RQs (derived using T-HERPS) for medium sized CRLF consuming small herbivore mammals exceedLOCs for all uses of dicofol.- Refined acute, dietary-based RQs (derived using T-HERPS) for CRLF consuming small insects and small herbivore mammalsexceed LOCs for several uses of dicofol.- Chronic dietary-based RQs for CRLF exceed LOCs for all uses of dicofol, for CRLF consuming any terrestrial food item (i.e.,insects, mammals and terrestrial-phase amphibians).- Chronic, dietary-based EECs are above levels where reduced number of eggs laid was observed in birds (i.e., EECs are >40ppm).Indirect effects totadpole CRLFvia reduction ofprey (i.e., algae)RQ values for algae are below theLOC for all uses of dicofol.Indirect effects tojuvenile CRLFvia reduction ofprey (i.e.,invertebrates)- Acute RQs for aquatic invertebrates exceed the LOC the majority of dicofol uses.- The likelihood of individual acute effects to aquatic invertebrates is≤3%. Based on this, indirect effects to the CRLF throughacute effects to aquatic invertebrates is discountable.- Chronic RQs for aquatic invertebrates do not exceed the LOC fordicofol use on cucurbits, peppers, tomatoes, Bermuda grass,ornamentals, turf and outside buildings.- Chronic RQs for aquatic invertebrates exceed the LOC for dicofol use on beans, citrus, cotton, grapes, hops, mint, pome fruits,stone fruits, strawberry, walnuts, and pecans.Indirect effects toadult CRLF viareduction of prey(i.e.,invertebrates,fish, frogs, mice)LAA- Acute RQs for aquatic invertebrates exceed the LOC the majority of dicofol uses.- The likelihood of individual acute effects to aquatic invertebrates is≤3%. Based on this, indirect effects to the CRLF throughacute effects to aquatic invertebrates is discountable.- Chronic RQs for aquatic invertebrates do not exceed the LOC fordicofol use on cucurbits, peppers, tomatoes, Bermuda grass,ornamentals, turf and outside buildings.- Chronic RQs for aquatic invertebrates exceed the LOC for dicofol use on beans, citrus, cotton, grapes, hops, mint, pome fruits,stone fruits, strawberry, walnuts and pecans.-Acute RQs for aquatic-phase amphibians and fish exceed the LOC for all uses of dicofol, except Bermuda grass and outsidebuildings.14AssessmentEndpointEffectsBasis for DeterminationDetermination- Use of dicofol on beans, citrus, cotton, hops, mint, pome fruits,strawberries, walnuts, and pecans results in >10% likelihood ofindividual mortality (from acute exposures) to fish and aquatic-phase amphibians.-Use of dicofol on cucurbits, grapes, pepper, stone fruits, tomatoes, Bermuda grass, ornamentals, turf, and outside buildings resultin <10% chance of effects to an individual fish and aquatic-phase amphibians representing prey of the CRLF.- Chronic RQs for fish and aquatic-phase amphibians exceed the LOC for all uses of dicofol, except Bermuda grass, turf, andoutside buildings.- Because the LD50used in deriving RQs for terrestrial invertebrates isnot quantified, RQs for acute exposures of small and largeterrestrial invertebrates to dicofolpotentiallyexceed the LOC of 0.05 for all uses.- Given that dicofol is intended for control of insects, it has the potential to impact non-targetinsects (other than honey bees).-For use of dicofol on grapes, mint, hops, peppers, tomatoes, cucurbits, ornamentals, turf and Bermuda grass, dicofol exposuresresult in a chance of individual mortality to <10% of terrestrialinsects. Therefore, indirecteffects to the CRLF through potentialeffects to terrestrial invertebrates resulting from these dicofol uses are considered discountable.- Use of dicofol on citrus, pome fruits, strawberries, walnuts, pecans, beans, cotton and stone fruits could potentially resultin≥10% of mortality to small invertebrates. Although there is uncertainty in the actual effects of these exposures to terrestrialinvertebrates, given that no LD50 was established, mortality to small insects resulting from dicofol applied to these crops hasthepotential to result in indirect effects to the CRLF.- RQ values representing acute exposures toterrestrial mammals exceed the LOC (0.1)for all uses of dicofol except: ornamentals,turf, outside buildings and Bermuda grass- Use of dicofol on citrus and pome fruits could potential result in 10.7% mortality to individual terrestrial mammals. Therefore,dicofol use on citrus and pome fruits could potentially result in indirect effects to the CRLF due to acute effects to terrestrialmammals. All other uses of dicofol result in≤2.0% mortality to small mammals resulting from acute exposures to dicofol.Therefore, indirect effects to the CRLF through potential effects to terrestrial mammals resulting from all dicofol uses, exceptcitrus and pome fruits, are considered discountable.- Chronic RQs exceed the LOC for terrestrialmammals for all uses of dicofol. ChronicEECs are sufficient to exceed the LOAECfor mammals where reproductive effects wereobserved. Therefore, chronic exposures of dicofol from all uses have the potentialto indirectly affect the CRLF via impacts to terrestrial mammals serving as potential prey items.- Acute and chronic exposures of small mammals to dicofol through consumption of contaminated earthworms from fields treatedwith dicofol have the potential to result in effects to mammals.- Acute, dose-based RQs for terrestrial-phase amphibians serving as preyto the CRLF do not exceed the LOC.- Acute, dietary-based RQs for terrestrial-phase amphibians exceed the LOC for several uses.- Analysis of the likelihood of individual mortality using acute dietary-based RQs for terrestrial amphibians indicates that all usesof dicofol result in≤2% chance of effects to an individual terrestrial amphibian representing prey of the CRLF. Therefore, theimpact of the indirect effects to terrestrial-phase CRLFs via acute effects on terrestrial amphibians is discountable for all uses ofdicofol.- Chronic, dietary-based RQs exceed the LOC by factors ranging 2x to 474x. Therefore, for all dicofol uses, there is potentialforindirect effects to the CRLF resulting fromchronic effects to terrestrial frogs.Indirect effects toCRLF via-Due to a lack of quantitative effects data for non-target plantsexposed to dicofol, potential risk of dicofol to the aquaticandterrestrial habitats of the CRLF cannot be quantified and effects of dicofol to plants cannot be discounted.1516AssessmentEndpointEffectsDeterminationBasis for Determinationreduction ofhabitat and/orprimaryproductivity(i.e., plants)-Qualitative data suggest that dicofol may result in phytotoxicity.-There is one reported incident involving effects of dicofol to plants.-Dicofol exposures to plants have the potential to cause indirect effects to aquatic phase CLRF through reduction of habitat.Table 2. Summary of effects determination for CRLF critical habitat based on uses of dicofol in California.AssessmentEndpointEffectsDeterminationBasis for DeterminationModification ofaquatic-phaseprimary constituentelementsDicofol has the potential to modify habitat based on the aquatic-phase PCEs.- Dicofol has the potential to directly affect the aquatic-phase CRLF (See Table1).- Dicofol has the potential to indirectly affect the aquatic-phase CRLF througheffects to its prey (see Table 1).-Effects of dicofol to plants making up the aquatic habitat of the CRLF cannot bediscounted.Modification ofterrestrial-phaseprimary constituentelementsHabitat EffectsDicofol has the potential to modify habitat based on the terrestrial-phase PCEs.- Dicofol has the potential to directlyaffect the terrestrial-phase CRLF (SeeTable 1).- Dicofol has the potential to indirectly affect the terrestrial-phase CRLF througheffects to its prey (see Table 1).-Effects of dicofol to plants making up the terrestrial habitat of the CRLF cannotbe discounted.Based on the conclusions of this assessment, a formal consultation wi th the U. S. Fish and Wildlife Service under Section 7 of the E ndangered Species Act shou ld be initiated. When evaluating the significance of this risk assessment’s direct, indirect, and adverse habitat modification effects determinations , it is important to note that pesticide exposures and predicted risks to the species and its resources ( i.e ., food and habitat) are not expected to be uniform across the action ar ea. In fact, given th e assumptions of drift and downstream transport ( i.e ., attenuation with distance) , pesticide exposure and associated risks to the species and its resour ces are expected to decrease with increasing distance away from the treated field or site of application. Evalua tion of the implication of this non-uniform distribution of risk to the species would require information and assessment techniques that are not currently ava ilable. Examples of such information and methodology required for this type of an alysis would include the following:

• Enhanced information on the density and distribution of CRLF life stages within specific recovery units and/or designated critical habitat within the action area. This information would allow for quantitative extrapolation of the present risk assessment’s pred ictions of individual effects to the proportion of the population extant with in geographical areas where those effects are predicted. Furthermore, such population information would allow for a more comprehensive evaluation of the significance of potential resource impairment to individuals of the species.

• Quantitative information on prey base requirements for individual aquaticand terrestrial-phase frogs. While existing information provides a preliminary picture of the types of food sources utilized by the frog, it does not establish minimal requirements to sustain health y individuals at varying life stages. Such informa tion could be used to establish biologically relevant thresholds of ef fects on the prey base, and ultimately establish geographical limits to those effects. This information could be used together with the density data discussed above to characterize the likelihood of adverse effects to individuals.

• Information on population responses of prey base organisms to the pesticide. Currently, methodologies are limited to predicting exposures and likely levels of direct mortalit y, growth or reproductive impairment immediately following exposure to the pesticide. The degree to which repeated exposure events and the inhe rent demographic ch aracteristics of the prey population play into the extent to which prey resources may recover is not predictable. An enha nced understanding of long-term prey responses to pesticide exposure would allow for a more refined determination of the magnitude and dur ation of resource impairment, and together with the information descri bed above, a more complete prediction of effects to individual frogs and potential modificati on to critical habitat.

17

### 2.0 Problem Formulation

Problem formulation provides a strategic framework for the risk assessment. By identifying the important components of th e problem, it focuses the assessment on the most relevant life history stages, habita t components, chemical properties, exposure routes, and endpoints. The structure of th is risk assessment is based on guidance contained in U.S. Environmental Protecti on Agency’s (EPA’s) Guidance for Ecological Risk Assessment (U.S. EPA 1998a), the Se rvices’ Endangered Species Consultation Handbook (U.S. FWS/NMFS 1998) and is consiste nt with procedures and methodology outlined in the Overview Document (U.S. EPA 2004) and reviewed by the U.S. Fish and Wildlife Service and National Marine Fisheries Service (U.S. FWS/NMFS 2004).

2.1. Purpose

The purpose of this endangered species assess ment is to evaluate potential direct and indirect effects on individuals of the fede rally threatened Calif ornia red-legged frog ( Rana aurora draytonii ) (CRLF) arising from FIFRA regul atory actions regarding use of dicofol on the following: beans (dry, snap, and lima), citrus (specifically, grapefruit, kumquats, lemons, limes, oranges, tangelos, and tangerines), cotton, cucurbits (specifically, cantaloupes, cu cumbers, melons, pumpkins, watermelons, and winter and summer squash), grapes, hops, mint, pecans, peppers, pome fruits (specifically, apples, crabapples, pears, and quince), stone fruits (specifically, apricots, sweet and sour cherries, nectarines, peaches, plums, and prunes), strawberries, tomatoes, walnuts, Bermuda grass, turf/ornamental uses (specifi cally, turf grasses, nursery stock, flowers, shade trees, woody shrubs and vines, and sod farms) and outside building surfaces (nonagricultural). In addition, this assessment evaluates whether use on these sites is expected to result in effects to the species’ designated critical habitat. This ecological risk assessment has been prepared consiste nt with a settlement agreement in the case Center for Biological Di versity (CBD) vs. EPA et al. (Case No. 02-1580-JSW(JL) entered in Federal District Court for the No rthern District of California on October 20, 2006.

In this assessment, direct and indirect effects to the CRLF and potential effects to its designated critical habitat are evaluated in accordance with the methods described in the Agency’s Overview Document (U.S. EPA 2004) . Screening-level methods include use of standard models such as GENEEC , PRZM-EXAMS, T-REX, TerrPlant, and AgDRIFT, all of which are described at le ngth in the Overview Document (U.S. EPA 2004). Use of such information is consis tent with the methodology described in the Overview Document (U.S. EPA 2004), which sp ecifies that “the assessment process may, on a case-by-case basis, incorporate additiona l methods, models, and lines of evidence that EPA finds technically appropriate for ri sk management objectives” (Section V, page 31 of U.S. EPA 2004).

In accordance with the Overview Document, provisions of the ESA, and the Services’ Endangered Species Consultation Handbook, the a ssessment of effects associated with registrations of dicofol is based on an action ar ea. The action area is the area directly or

18indirectly affected by the fe deral action. It is acknowledge d that the action area for a national-level FIFRA regulatory decision associated with a us e of dicofol may potentially involve numerous areas throughout the United St ates and its Territories. However, for the purposes of this assessment, attention wi ll be focused on relevant sections of the action area including those geographic areas as sociated with locations of the CRLF and its designated critical habitat within the state of California. As part of the “effects determination,” one of the following three conclusions will be reached regarding the potential use of dicofol in accordance with current labels:

• “No effect”;

• “May affect, but not likely to adversely affect”; or

• “May affect and likely to adversely affect”.

Designated critical habitat iden tifies specific areas that have the physical and biological features, known as primary constituent elements or PCEs, essential to the conservation of the listed species. The PCEs for CRLFs ar e aquatic and upland areas where suitable breeding and non-breeding aquati c habitat is locate d, interspersed with upland foraging and dispersal habitat.

If the results of initial screening-level assessment show no direct or indirect effects (no LOC exceedances) upon individual CRLFs or upon the PCEs of the species’ designated critical habitat, a “no effect” determination is made for use of dicofol as it relates to this species and its designated critical habitat. If, however, potential direct or indirect effects to individual CRLFs are anticipated or e ffects may impact the PCEs of the CRLF’s designated critical habitat, a preliminary “may affect” determination is made for the FIFRA regulatory action regarding dicofol.

If a determination is made that use of dicofo l within the action area(s) associated with the CRLF “may affect” this species or its designat ed critical habitat, a dditional information is considered to refine the potential for e xposure and for effects to the CRLF and other taxonomic groups upon which these species depend ( e.g. , aquatic and terrestrial vertebrates and invertebrates, aq uatic plants, riparian vegetation, etc .). Additional information, including spatial analysis (to de termine the geographical proximity of CRLF habitat and dicofol use sites) and further eval uation of the potential impact of dicofol on the PCEs is also used to determine whethe r effects to designated critical habitat may occur. Based on the refined information, the Agency uses the best available information to distinguish those actions that “may affect , but are not likely to adversely affect” from those actions that “may affect and are likely to adversely affect” the CRLF. This information is presented as part of the Ri sk Characterization in Section 5 of this document.

The Agency believes that the analysis of di rect and indirect effects to listed species provides the basis for an analysis of potential effects on the designated critical habitat. Because dicofol is expected to directly impact living organisms within the action area (defined in Section 2.7), critical habitat analysis for dicofol is limited in a practical sense to those PCEs of critical habitat that are biological or that can be reasonably linked to

19biologically-mediated processes ( i.e ., the biological resource requirements for the listed species associated with the critical habitat or important physical aspects of the habitat that may be reasonably influenced through biological processes). Activiti es that may modify critical habitat are those that alter the PCEs and appreciably diminish the value of the habitat. Evaluation of actions related to us e of dicofol that may alter the PCEs of the CRLF’s critical habitat form the basis of the cr itical habitat impact analysis. Actions that may affect the CRLF’s designated critical ha bitat have been identified by the Services and are discussed further in Section 2.6.

2.2. Scope

Dicofol is an organochlorine, broad-spectr um acaricide, insecticide, and miticide currently registered nationwide for applica tion to a variety of crops, including: beans (dry, snap, and lima), citrus (specifically, grapefruit, kumqu ats, lemons, limes, oranges, tangelos, and tangerines), cotton, cucurbit s (specifically, cantaloupes, cucumbers, melons, pumpkins, watermelons, and winter and summer squash), grapes, hops, mint, pecans, peppers, pome fruits (specifically, apples, crabapples, pears, and quince), stone fruits (specifically, apricots, sweet and sour cherries, nectarines, peaches, plums, and prunes), strawberries, tomatoes, walnuts, Bermuda grass, turf/ornamental uses (specifically, turf grasses, nur sery stock, flowers, shade trees, woody shrubs and vines, and sod farms) and outside building surfaces (non-agricultural). Application rates range from 0.4 – 3 lbs a.i./A with no more than one application per year fo r food crops. Dicofol may be applied as an aerial or ground spray. The current technical formula containing dicofol was reregistered in 1998. The term s of reregistration in cluded cancellation of residential uses, with remaining uses limited to one annual applica tion, and application rate reductions. The current labels for products containing dico fol comport with the changes implemented through reregistration and are being used to define parameters of the action being assessed in this ecological risk assessmen t and effects determination. Prior to 1990, dicofol contained approximately 10% DDT since DDT is an intermediate in the production of dicofol; however, refinements in the manufacturing process have reduced contamination in the current formul ation to less than 0.1 % DDT contamination.

The end result of the EPA pes ticide registration process ( i.e. , the FIFRA regulatory action) is an approved product la bel. The label is a legal do cument that stipulates how and where a given pesticide may be used. Pr oduct labels (also know n as end-use labels) describe the formulation type ( e.g. , liquid or granular), accepta ble methods of application, approved use sites, and any re strictions on how applications may be conducted. Thus, the use of dicofol in accordance with the appr oved product labels for California is “the action” relevant to this ecological risk assessment.

Although current registrations of dicofol allo w for use nationwide, this ecological risk assessment and effects determination addresses currently registered uses of dicofol in portions of the action area that are reasonably assumed to be biologically relevant to the CRLF and its designated critical habitat. Further discussion of the action area for the CRLF and its critical habitat is provided in Section 2.7.

20Major degradates of the two isomers of dicofol are the o,p '- and p,p ' isomers of dichlorobenzophenone (DCBP); 1, 1-(p-c h1orophenyl-) 2,2-dichloroethanol (FW-152); dichlorobenzhydrol (DCBH); hydroxyl-dic hlorobenzophenone (OH-DCBP); and chlorobenzoic acid (CBA). DCBP was id entified in the hydrol ysis, photolysis and metabolism studies while the others were only present in metabolism studies. The structures of dicofol and its major degradates are provided in Appendix A . There are currently no submitted studies addressing the environmental fate and transport of these major degradates. In addition, no empirical data are available to define the toxicities of these degradates to non-target organisms. In order to characterize the relative toxicities of these degradates to dicofol, the Ecosar 1 model was run. The resu lt indicates that the toxicities of DCBP, FW-152, DCBH and OH-DCBP are within an order of magnitude of dicofol (for a full description of the results, see Section 4.2). Theref ore, these degradates were considered to be of concern for this risk assessment. It is assumed in this assessment that for aquatic animals, total residues are of equal toxicity to that of the parent.

The Agency does not routinely include in its risk assessments an evaluation of mixtures of active ingredients, either those mixtures of multiple active ingredients in product formulations or those in the applicator’s ta nk. In the case of the product formulations of active ingredients (that is, a registered product containing more than one active ingredient), each active ingredient is subj ect to an individual risk assessment for regulatory decision regarding the active ingredient on a particular use site. If effects data are available for a formulated product contai ning more than one active ingredient, they may be used qualitatively or quantitatively in accordance with the Agency’s Overview Document and the Services’ Evalua tion Memorandum (U.S . EPA 2004; U.S. FWS/NMFS 2004).

Registered products that cont ain dicofol do not list any othe r active ingredients on their labels. However, as mentioned earlier, pr ior to 1990, dicofol contained approximately 10% DDT. Refinements in the manufacturing pr ocess have reduced contamination in the current formulation to less than 0.1 % DDT contamination. No other data on mixtures including dicofol are available.

2.3. Previous Assessments

In November 1998, EPA completed its Regi stration Eligibility Decision (RED) for dicofol. EPA concluded that the available fi eld data suggested that dicofol did not pose significant adverse effects on avian reproduction and did not present an unreasonable risk to ecosystems. However, based on laborat ory data, the potential for such effects appeared significant for certain species. Dicofol was found to be moderately to slightly toxic on an acute exposure basi s to terrestrial animals and pr actically non-toxic to honey bees on an acute contact exposur e basis. In laboratory stud ies dicofol was also shown to cause reproductive effects in avian and ma mmalian species. Dicofol was found to be highly toxic on an acute basis to both cold and warm water species of fish and freshwater

1 USEPA 2009. Ecological Structure Activity Relationships (ECOSAR) version 1.00a. Office of Pollution Prevention and Toxic. http://www.epa.gov/oppt/newchems/tools/21ecosar.htm

21invertebrates and was very highly toxic to estuarine/marine invertebrates. Additionally, laboratory studies showed that dicofol had so me potential to bioaccumulate in fish, but that dicofol residues depurated relatively qui ckly. Because of its apparent structural similarity to DDT, dicofol has been identified as a potential endocrine disrupter. However, based on the data available, no conclusions could be made regarding the potential for dicofol to act as an endocrine disrupter (USEPA, 1998b).

2.4. Stressor Source and Distribution

2.4.1. Environmental Fate Assessment

Based on the available environmental fate data for dicofol, this chemical is not expected to persist in the environment, with half -lives less than 90 days, depending upon the specific environmental conditions. However, studies submitte d on the fate of dicofol do not provide sufficient information to estimate persistence of dicofo l degradates in the environment. As a result, conservative esti mates for persistence of dicofol (considering the parent and major degradates) are as high as 313 days. The primary route of dissipation is soil metabolism and the primar y route of transport is surface runoff.

Dicofol occurs in formulated end-use products as two isomers, o,p '-dicofol and p,p '- dicofol, at a ratio of 1:4.5. Majo r degradates of dicofol include the o,p '- and p,p '-isomers of DCBP, FW-152, DCBH, OH-DCBP, and CBA.

22Table 3 lists the environmental fate properties of the dicofol isomers. The o,p '-isomer hydrolyzed with half-lives of 47 days, 0.33 days, and 0.006 days at pHs 5, 7 and 9, respectively (MRID 40042033). An aerobic so il metabolism study showed that the o,p '- isomer degraded with half-life of 8.5 da ys in a loam soil unde r slightly alkaline conditions (pH = 7.5, MRID 41094201). Parent plus major residue s degraded with a halflife of 186 days. An anaerobic soil metabolism study showed that the o,p '-isomer degraded with half-life of 6 days in a silt loam soil under slightly alkaline conditions (pH = 7.9, MRID 43908701). Adsorpti on data indicate that the o,p ’-isomer is not very mobile, with a majority of the o,p ’-dicofol remaining in the upper 2 inches of the soil columns. Less than 2.5% of o,p ’-dicofol was found in leachate (MRID 41509802).

The p,p '-isomer hydrolyzed with half-lives of 85 days, 2.8 days and 0.018 days at pHs 5, 7 and 9, respectively (MRIDs 40042032, 40460105) . An aerobic soil metabolism study showed that the p,p '-isomer degraded with a half-life of 32 days in a silt loam soil under slightly alkaline conditions (pH = 7.8, MRID 41050701). Parent plus major residues degraded with a half-life of 313 days. An anaerobic soil metabolism study showed that the p,p '-isomer degraded with half-life of less than 30 days in a silt loam soil under slightly alkaline conditions (pH = 7.8, MRID 40042039). Adsorption data indicate that the p,p ’-isomer is not very mobile (MRID 41509801) . A regression analysis between the K d and organic carbon content values in dicated a high r-squared value (0.98) and statistical significance (<0.01). To assess the appropriateness of the K oc model, the coefficient of variation for the K oc (CV = 19) was compared to the coefficient of variation for K d (CV = 58). Since the CV for the K oc was less than the CV for K d , the average K oc of 7,060 mL/g was used (Kashuba et al. 2006). For o,p’ -dicofol, the majority of dicofol remained in upper 2 inches of soil columns, with less than 2.5% of dicofol found in leachate.

Of the major dicofol degradates, DCBP was identified in the hydrolysis, photolysis and metabolism studies, while the other degradates were only present in metabolism studies.

Table 4 summarizes the maximum amount of the i ndividual degradates that were observed in submitted environmental fate studies for dicofol and when the maximum amount occurred. There are currently no submitted studies quantifying the environmental fate and transport ( e.g ., half-lives) of the major degradates of dicofol individually.

vailable registrant-sub A mitted data indicate that dicofol has potential to bioaccumulate in aquatic ecosystems. Dicofol has a octanol-water partitioning coefficient (K ow ) of 1.15 x 10 -6 (MRID 00141578). In a bioconcentration study, parent p,p' -dicofol residues in bluegill sunfish resulted in bi oconcentration factor s of 6,600 in fillet, 17,000 in viscera, and 10,000 in whole fish. The half-life of elimin ation (depuration) was estimated to be 33 days (MRID 265330).

23Based on the available fate data , the major routes of dissipa tion for dicofol are hydrolysis under neutral and alkaline conditions, and aerobic and anaerobic soil metabolism under slightly alkaline conditions (p H from 7.5 to 7.9), with the o,p '-isomer degrading more quickly. Dicofol can be classified as slightly mobile (Kashuba, et al. 2006) and has the potential to bioaccumulate in the environm ent. Leaching and photodegradation are not expected to be significant routes of dissipation. Based on dicofol’s vapor pressure (3.9 x 10 -7 torr), low levels of volatilitization are possible, but not expected. Dicofol can be expected to partition betw een the gas and particle phase s in the atmosphere, and is likely to exist largely in the particle phase , potentially contributi ng to its long-range transport. Given dicofol’s K ow and K oc values, it is anticipated that dicofol that enters surface water through soil erosion, runoff, or spray drift will have an a ffinity to reside in the sediment. Anaerobic soil metabolism studies indicate that dicofol will degrade relatively rapidly in sediment with a half-life less than 30 days. It is unclear how dicofol degradates would partition in the wate r column; however, estimates of the K ow values (9,120-77,625) and K oc values (1,933-8,950) 2 using EPISuite indicate a similar affinity for the sediment. As there are no data quant ifying the fate and transport of the dicofol degradates, two stressors will be examined in this assessment: the parent compound (both isomers of dicofol) and the total residues of concern (both isomers of dicofol and their degradates). Based on toxicity data, the degradate CBA will not be considered in the total residues of concern (see Section 4.2.1).

2 USEPA 2009. Estimation Program Interface (EPI) Su ite version 4.0. Office of Pollution Prevention and Toxics. http://www.epa.gov/oppt/exposure/pubs/episuitedl.htm

24Table 3. Summary of dicofol en vironmental fate properties.

Chemical/Fate Parameter Value
o,p ’-dicofol Value

p,p ’-dicofol MRID 1 Study Classification Molecular weight 370.5 g/mol Vapor pressure (20 ° C) 3.9x10 -7 torr Water solubility (25 ° C) 1.32 mg/L 00141704
00142595 Acceptable

Kow 1.15 x 10 6 00141578 Acceptable

Hydrolysis half-life pH 5 pH 7 pH 9 47 days
3.3 x 10 -1 days
6.3 x 10 -3 days 85 days 2.8 days
1.8 x 10 -2 days 40042033
40042032
40460105 Acceptable Acceptable Acceptable

Direct Aqueous Photolysis 2 half-life 27.5 days 244 days 40849702
40849701 Acceptable Acceptable

Soil Photolysis halflife 56 days 21 days 40042037
40042036 Supplemental Supplemental

Aerobic Soil Metabolism half-life 8.5 days (parent) 104.5 days (parent and major degradates) 32 days (parent) 313 days (parent and major degradates) 41094201
41050701 Acceptable Acceptable

Anaerobic Soil Metabolism half-life 6 days < 30 days 43908701
40042039 Acceptable Supplemental

Leaching & Adsorption/Desorption Majority of parent remained in upper 2 inches of soil columns. ≤ 2.5% of parent found in leachate. K oc =7,060 mL/g 41509802
41509801 Acceptable Acceptable

Terrestrial Field Dissipation half-life 3.7, 22 days 4.7, 72 days 41381801
42118601 Supplemental Supplemental 1. First MRID listed corresponds to data for o,p ’-dicofol, while the second MRID corresponds to data for p,p ’- dicofol. 2. Data corrected for dark control.

25Table 4. Summary of dicofol degrad ates observed in submitted enviro nmental fate studies for dicofol. Data represent % of total residue detected as specific degradate and study day residues were measured.

Fate Study Dicofol Isomer FW-152 1 DCBP 2 DCBH 3 OH-DCBP 4 CBA 5 MRID

o,p’ ND 53% Day 1 ND ND ND 40042033 Hydrolysis pH 7 p,p’ ND 50% Day 7 ND ND ND 40042032

o,p’ ND 26% Day 30 ND ND ND 40849702 Direct Aqueous Photolysis 1 p,p’ ND 7% Day 30 ND ND ND 40849701

o,p’ ND 29% Day 30 ND ND ND 40042036 Soil Photolysis p,p’ ND 25% Day 30 ND ND ND 40042037

o,p’ 31% Day 31 19% Day 275 12% Day 366 12% Day 92 14% Day 92 41094201 Aerobic Soil Metabolism p,p’ 45% Day 62 18% Day 275 ND 17% Day 275 ND 41050701

o,p’ 43% Day 30 <10% Day 1 15% Day 30 ND ND 43908701 Anaerobic Soil Metabolism p,p’ 38% Day 60 5.4% Day 0 6.4% Day 60 ND ND 40042039

ND = not detected

1 1,1-( p -ch1orophenyl-) 2,2-dichloroethanol
2 Dichlorobenzophenone
3 Dichlorobenzhydrol
4 Hydroxyl-dichlorobenzo-phenone

5 Chlorobenzoic acid

2.4.2. Environmental Transport Assessment

Potential transport mechanisms include runoff in soluble and soil-bound forms, spray drift, and atmospheric transport in soil-bound residues leading to de position into nearby or more distant ecosystems.

Dicofol is expected to have limited mobility in the environment and a low potential to migrate to groundwater. In soil column l eaching experiments in sand, sandy loam, and clay loam (MRID 41509802), 75 to 98% of the applied radioactivity of the o,p '-dicofol isomer remained in the upper 1 or 2 inches of the columns. Less than 3% of the applied radioactivity was in the leachate. Batch equilibrium studies on the p,p '-isomer resulted in organic carbon sorption coefficients of 7,060 mL/g oc , (MRID 41509801). Two supplemental leaching studies conducted on p,p '-dicofol suggest that the chemical does not significantly leach under the tes ting conditions (IDs GS0021002 and GS0021007).

26No data are available on the mobility of ag ed dicofol or on the mobility of the major degradates of dicofol. Based on the results of the terrestrial fiel d dissipation studies, it appears that dicofol metabolites are not very mobile under normal dicofol use conditions. Depending on soil, site and meteorological cond itions dicofol may be transported off-site in soil-bound erosion from runoff.

Although supplemental, two terrestrial field diss ipation studies confirm the results of the laboratory persistence and mobility studies. These studies suggest that dicofol does not persist in the field for long peri ods (on an order of several da ys to several weeks). In a dissipation study on cotton in Madera, Califor nia (MRID 41381801), dico fol residues had a DT 50 value (the length of time required for 50 % of the parent to dissipate from the surface 6-inches of the soil) of less than 7 days. In a second dissipation study on strawberries in Thermal, California (MRID 42118601), the rate of dissipation was slower (DT 50 s of 22 days for o,p '-dicofol and 72 days for p,p '-dicofol). Dicofol dissipated from the upper 6 inches in the Madera study site at a rate that was an order of magnitude faster than that of the Thermal site, despite the fact that the soils at the Thermal site had an alkaline pH more favorable to hydrolysis (8.4 at Thermal versus 6.2 at Madera) and a higher organic matter content (0.8% at Ther mal versus 0.2% at Madera). Greater amounts of irrigation were used in the cott on study (44.28 inches of water over the first 228 days in Madera versus 27.04 inches of water over 365 days). Results of these studies suggest that hydrolysis at the Madera site ma y have played a greater role than at the Thermal site, where metabolism appeared to be the dominant route of dissipation in the field. Neither dicofol nor its residues moved significantly below 6 inches in either study. The major degradates observed in these field studies, o,p ' and p,p '-DCBP, o,p '-DCBH, 4- CBA, and p,p '-FW 152. Analysis of the data indicat es that the half-lives for the major degradates, o,p ’-DCBP and p,p ’-DCBP, were between 29 an d 45 days, and 55 and 132 days, respectively.

A number of studies have documented atmospheric trans port and re-deposition of pesticides from the Central Valley to the Sierra Nevada Mountains (Fellers et al. 2004; Sparling et al. 2001; LeNoir et al. 1999; McConnell et al. 1998). Prevailing winds blow across the Central Valley eastward to the Sier ra Nevada Mountains, transporting airborne industrial and agricultural pollutants into the Sierra Nevada ecosystems (Fellers et al. 2004; LeNoir et al. 1999; McConnell et al. 1998). Several sections of critical habitat for the CLRF are located east of the Central Valley. The magnitude of transport via secondary drift depends on dicofol’s ability to be mobilized into air and its eventual removal through wet and dry deposition of part icles and photochemical reactions in the atmosphere. Therefore, physicochemical propert ies of dicofol that describe its potential to enter the air from water or soil, pesticide use data, modeled estimated concentrations in water and air, and available air monitoring da ta from the Central Valley and the Sierra Nevada Mountains are consider ed in evaluating the potential for atmospheric transport of dicofol to locations where it could impact the CRLF.

Because of its low vapor pressure and persistenc e in the air (estimated half-life > 2 days), the United Nations Economic Commission for Europe’s (UNECE) Convention on Longrange Transboundary Air Pollution has indicate d that dicofol has the potential for long

27range transport (Rasenberg et al. 2003). According to the repor t, “dicofol is expected to partition between the gas and particle phases in the atmosphere and is likely to exist largely in the particle phase.”

2.4.3. Mechanism of Action

According to the World Health Organizati on (WHO, 1996), dicofol produces stimulation of axonal transmission of nerve signals, believed to be related to inhi bition of ATPases in the central nervous system (CNS). The si gns of toxicity are consistent with CNS depression. However, the Insecticide Resi stance Action Committee (IRAC) has recently classified the mode of action for di cofol as unknown or uncertain (IRAC, 2008).

2.4.4. Use Characterization

Analysis of labeled use information is the critical first step in evaluating the federal action. The current labels for dicofol repres ent the FIFRA regulator y actions; therefore, labeled use and application rates specified on the label form the basis of this assessment. The assessment of use information is critical to the development of the action area and selection of appropriate m odeling scenarios and inputs.

Dicofol is an organochlorine, broad-spectr um acaricide, insecticide, and miticide currently registered nationwide for application on a vari ety of crops and non-agricultural

uses. Table 5 presents the uses and corresponding application rates and methods of application considered in this assessment. The reported application rates represent the maximum application rate used in any crop/ use site within each group. The information was extracted from existing product labe ls (EPA Registration Numbers 11603-26, 66222- 21, 66222-56, and 66222-95). Dicofol is used for non-residential purposes only.

Table 5. Methods and rates of ap plication of currently registered uses of dicofol in California 1

.

Use (Application Method) Max. Single Appl. Rate (lb a.i./A) Application Method(s)

Beans (dry, snap, lima) 1.5 ULV, Aircraft, Hi- and low-volume ground
sprayer
Citrus 2 3 ULV, Aircraft, Hi- and low-volume ground
sprayer

Cotton 1.5 ULV, Aircraft, Hi- and low-volume ground
sprayer
Cucurbits 3 0.625 ULV, Aircraft, Hi- and low-volume ground
sprayer Grapes 1.25 ULV, Aircraft and ground sprayer

Hops 1.165 ULV, Aircraft, Hi- and low-volume ground
sprayer Mint/Peppermint/Spearmint 1.25 ULV, Aircraft, Hi- and low-volume ground
sprayer

28Use (Application Method) Max. Single Appl. Rate (lb a.i./A) Application Method(s)

Pecans 2 ULV, Aircraft, Hi- and low-volume ground
sprayer Peppers 0.75 ULV, Aircraft, Hi- and low-volume ground
sprayer
Pome Fruits 4 3 ULV, Aircraft, Hi- and low-volume ground
sprayer
Stone Fruits 5 1.5 ULV, Aircraft and ground sprayer

Strawberries 2 ULV, Aircraft, Hi- and low-volume ground
sprayer

Tomatoes 0.75 ULV, Aircraft, Hi- and low-volume ground
sprayer Walnuts (English/black) 2 ULV, Aircraft, Hi- and low-volume ground
sprayer Bermuda grass 0.4 Hi- and low-volume ground sprayer

Turf grasses 0.5 Hi- and low-volume ground sprayer

Sod farms 0.5 Hi- and low-volume ground sprayer

Ornamentals 6 0.5 Hi- and low-volume ground sprayer

Outside building surfaces 0.5 Hi- and low-volume ground sprayer

1. Applications of dicofol are limited to no more than one per year on any one field. 2. Specifically: grapefruit, kumqua ts, lemons, limes, oranges, tangelos, and tangerines. 3. Specifically: cantaloupes, cucumbers, melons, pum pkins, watermelons, and winter and summer squash. 4. Specifically: apples, crabapples, pears, and quince. 5. Specifically: apricots, sweet and sour cherries, nectarines, peaches, plums, and prunes.
6. Specifically: nurseries, flowers, and shade trees.

Figure 2 below shows the estimated poundage of di cofol uses across the United States. The map was downloaded from a U.S. Ge ological Survey (USGS), National Water Quality Assessment Program (NAWQA) website ( http://water.usgs.gov/na wqa/pnsp/usage/maps/ ).

29Figure 2. Estimated national agricultural use of dicofol for 2002.

The Agency’s Biological and Economic An alysis Division (EPA/OPP/BEAD) provides an analysis of both national- and county-level usage inform ation (Kaul and Jones, 2006) using state-level usage data obtained from USDA-NASS 3 , Doane ( www.doane.com ; the full dataset is not provided due to its proprie tary nature) and the California’s Department of Pesticide Regulation Pesticide Use Reporting (CDPR PUR) database 4 . CDPR PUR is considered a more comprehensive source of usage data than USDA-NASS or EPA proprietary databases, and thus the usage da ta reported for dicofol by county in this California-specific assessment were genera ted using CDPR PUR data. Eight years (1999-2006) of usage data were included in this analysis. Data from CDPR PUR were obtained for every pesticide a pplication made on every use site at the section level (approximately one square mile) of the pub lic land survey system. EPA/OPP/BEAD summarized these data to the county level by s ite, pesticide, and unit treated. Calculating county-level usage involved summarizing across all applications made within a section and then across all sections within a county fo r each use site and for each pesticide. The county level usage data that were calculat ed include: average annual pounds applied,

3 United States Depart of Agriculture (USDA), Natio nal Agricultural Statistics Service (NASS) Chemical Use Reports provide summary pesticide usage statistic s for select agricultural use sites by chemical, crop and state. See http://www.usda.gov/nass/pubs/estindx1.htm#agchem

. 4 The California Department of Pesticide Regulation’s Pesticide Use Reporting database provides a census of pesticide applications in the state. See http://www.cdpr.ca.gov/docs/pur/purmain.htm.

30average annual area treated, and average and maximum application rate across all eight years. The units of area treated are also provided where available.

Eight years (1999-2006) of usage data from CDPR PUR were obtained for every difocol application made on every use site in Califor nia at the field level. Total annual pounds applied and total annual area treated were calculated at the county level by site and pesticide active ingredient. Pesticide usage was also aggregated across all observations for eight years for each chem ical-county-unit-treated combin ation. Because pesticide applications are made in diffe rent area units, the un its of area treated are provided where available. Years in which there is no reporte d use in a county are included as zeros in the calculation of the eight-year averages for pounds and area treated. Averages reflect years without use.

In California between 1999 and 2006, the major ity of dicofol applied was used on cotton (64%), with lesser percentages applied to beans (13%), citrus (6%), and grapes (5%). Overall usage of dicofol in California fell from 1999 to 2002 to roughly 182,000 lbs/year, then increased to 212,000 lbs/year in 2004, and decreased to 101,000 lbs in 2006. Approximately 20% of dicofol applied in Ca lifornia is used in the 20 counties that contain CRLF critical habitat ar eas. A summary of dicofol usage for all California use sites is provided below in Table 6 . These rates are consistent with the maximum application rates specified on the label and used in the mo deling analysis, depicted in Table 9 , with a few exceptions. For cucurbits, the maximum label application rate is 0.625 lbs dicofol/A, while the app lication rates depicted in th e CDPR PUR database were above this level. This can be attributed to an outlier reported for 1999 in San Joaquin County where 50 acres of squash were reporte dly treated with 2,815 lb s of dicfol. For tomatoes, the maximum label application rate is 0.75 lbs dicofol/A , while the CDPR PUR reported application rates are a bove this level. Data available in the CDPR PUR database for tomatoes is divided into two groups, tomato es and tomato processing. It appears that the use rates for tomato processing applicatio ns are increasing the values derived from the CDPR PUR database, as the statistical ap plication rates data for tomatoes all fall below the maximum label rate, while all of th e statistics for tomato processing are above the maximum label use rate. For Bermuda grass, the maximum label rate is 0.4 lbs dicofol/A. There was only one reported va lue for Bemuda grass in the CDPR PUR database for 0.48 lbs dicofol/A. Lastly, the maximum label application rate for ornamentals is 0.5 lbs dicofol/A. Outdoor flow ers, transplants, and plants in containers were grouped into this category. It’s unclear as to how th e area treated, reported in acres or square feet, was estimated in the database . As such, an underestimation in the area treated could result in an application rate higher than the maximum label rate. It should be noted that the uses considered in this ri sk assessment represent all currently registered uses according to a review of all current labels. No othe r uses are relevant to this assessment. Any other reported use, such as may be seen in the CDPR PUR database, represent either historic uses that have b een canceled, mis-reported uses, or mis-use. Historical uses, mis-reported uses, and misu se are not considered part of the federal action and, therefore are not cons idered in this assessment.

31Table 6. Summary of California Department of Pesticide Registration (CDPR) Pesticide Use Reporting (PUR) data and calculat ed annual application rates (199 9 - 2006) for currently registered dicofol uses. 1

Site Name Annual Average Pounds Avg App Rate (lbs ai/acre) Avg 95th% App Rate (lbs ai/acre) Avg 99th% App Rate (lbs ai/acre) Avg Max App Rate (lbs ai/acre) Beans (dry, snap, lima) 28,568 1.27 1.46 1.46 1.46 Citrus 2 13,427 2.26 2.70 2.70 2.70
Cotton 142,539 1.01 1.25 1.25 1.25
Cucurbits 3 6,853 0.77 1.26 1.26 1.26 Grapes 11,642 1.10 1.26 1.26 1.26 Mint/Peppermint/Spearmint 138 0.87 1.00 1.00 1.00 Peppers 184 0.66 0.71 0.71 0.71
Pome Fruits 4 1,769 1.64 1.89 1.89 1.89
Stone Fruits 5 7,676 1.34 1.55 1.55 1.55
Strawberries 1,327 1.01 1.36 1.36 1.36
Tomatoes 1,008 0.78 0.93 0.93 0.93 Walnuts (English/black) 7,013 1.75 2.00 2.00 2.00 Bermuda grass 90 0.48 0.48 0.48 0.48 Ornamentals 6 582 0.93 1.24 1.24 1.24 1. Dicofol was not applied to hops, pecans, turf, sod farms, or outside building surfaces from 1999-2006, according to the PUR database. 2. Specifically: grapefruit, lemons, oranges, tangelos, and tangerines. 3. Specifically: cantaloupes, cucumbers, melons, pum pkins, watermelons, and winter and summer squash. 4. Specifically: apples and pears. 5. Specifically: apricots, cherries, nectarines, peaches, plums, and prunes.
6. Specifically: outdoor flowers and plants.

2.5. Assessed Species

The CRLF was federally listed as a threaten ed species by U.S. FWS effective June 24, 1996 (U.S. FWS 1996). It is one of two subspecies of the red-legged frog and is the largest native frog in the western United St ates (U.S. FWS 2002). A brief summary of information regarding CRLF distribution, repr oduction, diet, and habitat requirements is provided below. Further information on the status, distribution, and life history of and specific threats to the CRLF is provided in Attachment 1.

Final critical habitat for the CRLF was de signated by U.S. FWS on April 13, 2006 (U.S. FWS 2006; 71 FR 19244-19346). Further informa tion on designated critical habitat for the CRLF is provided in Section 2.6.

322.5.1. Distribution

The CRLF is endemic to California and Baja California (Mexico) and historically inhabited 46 counties in California includi ng the Central Valley and both coastal and interior mountain ranges (U .S. FWS 1996). Its range has been reduced by about 70%, and the species currently resides in 22 c ounties in California (U.S. FWS 1996). The species has an elevational range of near sea level to 1,500 meters (5,200 feet) (Jennings and Hayes 1994); however, nearly all of the known CRLF populations have been documented below 1,050 meters (3,500 feet) (U.S. FWS 2002).

Populations currently exist al ong the northern California co ast, northern Transverse Ranges (U.S. FWS 2002), foothills of the Si erra Nevada (5-6 pop ulations), and in southern California south of Santa Barbara (two populations) (Fellers 2005a). Relatively larger numbers of CRLFs are located be tween Marin and Santa Barbara Counties (Jennings and Hayes 1994). A total of 243 st reams or drainages are believed to be currently occupied by the species, with the greatest numbers in Monterey, San Luis Obispo, and Santa Barbara counties (U.S. FWS 1 996). Occupied drainages or watersheds include all bodies of water that support CRLFs ( i.e ., streams, creeks, tributaries, associated natural and artificial ponds, a nd adjacent drainages), and habitats through which CRLFs can move ( i.e ., riparian vegetation, upl ands) (U.S. FWS 2002).

The distribution of CRLFs within California is addressed in this a ssessment using four categories of location including recovery units, core areas, designated critical habitat, and known occurrences of the CRLF reported in th e California Natural Diversity Database (CNDDB) that are not included within core areas and/or designated critical habitat ( Figure 3 ). Recovery units, core areas, and other known occurrences of the CRLF from the CNDDB are described in further detail in Attachment I, and designated critical habitat is addressed in Section 2.6. Recovery units are large areas defined at the watershed level that have similar conservation needs and mana gement strategies. The recovery unit is primarily an administrative designation, a nd land area within the recovery unit boundary is not exclusively CRLF habitat. Core areas are smaller areas within the recovery units that comprise portions of the species’ hi storic and current ra nge and have been determined by U.S. FWS to be important in the preservation of the species. Designated critical habitat is generally contained within the core areas, although a number of critical habitat units are outside the boundaries of core areas, but w ithin the boundaries of the recovery units. Additional information on CR LF occurrences from the CNDDB is used to cover the current range of the species no t included in core areas and/or designated critical habitat, but within the recovery units.

Other Known Occurrences from the CNDBB

The CNDDB provides location and natural history information on species found in California. The CNDDB serves as a repository for historical and current species location sightings. Information regarding known occurr ences of CRLFs outside of the currently occupied core areas and designated critical ha bitat is considered in defining the current

33range of the CRLF. See: http://www.dfg.ca.gov/bdb/html/cnddb_info.html for additional information on the CNDDB.

Recovery Units 1. Sierra Nevada Foothills and Central Valley 2. North Coast Range Foothills and Western Sacramento River Valley 3. North Coast and North San Francisco Bay 4. South and East San Francisco Bay 5. Central Coast 6. Diablo Range and Salinas Valley 7. Northern Transverse Ranges and Tehachapi Mountains 8. Southern Transverse and Peninsular Ranges

Core Areas

1. Feather River 2. Yuba River- S. Fork Feather River 3. Traverse Creek/ Middle Fork/ American R. Rubicon 4. Cosumnes River 5. South Fork Calaveras River* 6. Tuolumne River* 7. Piney Creek* 8. Cottonwood Creek 9. Putah Creek – Cache Creek* 10. Lake Berryessa Tributaries 11. Upper Sonoma Creek 12. Petaluma Creek – Sonoma Creek 13. Pt. Reyes Peninsula 14. Belvedere Lagoon 15. Jameson Canyon – Lower Napa River 16. East San Francisco Bay 17. Santa Clara Valley 18. South San Francisco Bay 19. Watsonville Slough-Elkhorn Slough 20. Carmel River – Santa Lucia 21. Gablan Range 22. Estero Bay 23. Arroyo Grange River 24. Santa Maria River – Santa Ynez River 25. Sisquoc River 26. Ventura River – Santa Clara River 27. Santa Monica Bay – Venura Coastal Streams 28. Estrella River 29. San Gabriel Mountain* 30. Forks of the Mojave* 31. Santa Ana Mountain* 32. Santa Rosa Plateau 33. San Luis Ray* 34. Sweetwater* 35. Laguna Mountain*

* Core areas that were historically occupied by the California red-legged frog are not included in the map Recovery Units 1. Sierra Nevada Foothills and Central Valley 2. North Coast Range Foothills and Western Sacramento River Valley 3. North Coast and North San Francisco Bay 4. South and East San Francisco Bay 5. Central Coast 6. Diablo Range and Salinas Valley 7. Northern Transverse Ranges and Tehachapi Mountains 8. Southern Transverse and Peninsular Ranges

Core Areas

1. Feather River 2. Yuba River- S. Fork Feather River 3. Traverse Creek/ Middle Fork/ American R. Rubicon 4. Cosumnes River 5. South Fork Calaveras River* 6. Tuolumne River* 7. Piney Creek* 8. Cottonwood Creek 9. Putah Creek – Cache Creek* 10. Lake Berryessa Tributaries 11. Upper Sonoma Creek 12. Petaluma Creek – Sonoma Creek 13. Pt. Reyes Peninsula 14. Belvedere Lagoon 15. Jameson Canyon – Lower Napa River 16. East San Francisco Bay 17. Santa Clara Valley 18. South San Francisco Bay 19. Watsonville Slough-Elkhorn Slough 20. Carmel River – Santa Lucia 21. Gablan Range 22. Estero Bay 23. Arroyo Grange River 24. Santa Maria River – Santa Ynez River 25. Sisquoc River 26. Ventura River – Santa Clara River 27. Santa Monica Bay – Venura Coastal Streams 28. Estrella River 29. San Gabriel Mountain* 30. Forks of the Mojave* 31. Santa Ana Mountain* 32. Santa Rosa Plateau 33. San Luis Ray* 34. Sweetwater* 35. Laguna Mountain*

* Core areas that were historically occupied by the California red-legged frog are not included in the map
Figure 3. Recovery unit, core area, critical ha bitat, and occurrence designations for CRLF.

342.5.2. Reproduction

CRLFs breed primarily in ponds; however, they may also breed in quiescent streams, marshes, and lagoons (Fellers 2005a). Accord ing to the Recovery Plan (U.S. FWS 2002), CRLFs breed from November through late Ap ril. Peaks in spawning activity vary geographically; Fellers (2005b) reports peak sp awning as early as January in parts of coastal central California. Eggs are fertilized as they are being laid. Egg masses are typically attached to emergent vegetation, such as bulrushes ( Scirpus spp.) and cattails ( Typha spp.) or roots and twigs, and float on or near the surface of the water (Hayes and Miyamoto 1984). Egg masses contain approx imately 2000 to 6000 eggs ranging in size between 2 and 2.8 mm (Jennings and Hayes 19 94). Embryos hatch 10 to 14 days after fertilization (Fellers 2005a) depending on water temperature. Egg predation is reported to be infrequent and most mortality is asso ciated with the larval stage (particularly through predation by fish); however, predatio n on eggs by newts has also been reported (Rathburn 1998). Tadpoles require 11 to 28 weeks to metamorphose into juveniles (terrestrial-phase), typically between May and Septembe r (Jennings and Hayes 1994, U.S. FWS 2002); tadpoles have been observed to over-winter (delay metamorphosis until the following year) (Fellers 2005b, U.S. FWS 2 002). Males reach sexual maturity at 2 years, and females reach sexual maturity at 3 y ears of age; adults have been reported to live 8 to 10 years (U.S. FWS 2002). Figure 4 depicts CRLF annual reproductive timing.

D N O S A J J M A M F J
Light Blue = Breeding/Egg Masses Green = Tadpoles (except those that over-winter) Orange = Young Juveniles Adults and juveniles can be present all year D N O S A J J M A J F M
Light Blue = Breeding/Egg Masses Green = Orange = Young Juveniles Adults and juveniles can be present all year Tadpoles (except those that over-winter)

Figure 4. CRLF reproductive events by month.

2.5.3. Diet

Although the diet of CRLF aquatic-phase larvae (tadpoles) has not been studied specifically, it is assumed that their diet is similar to that of other frog species, with the aquatic phase feeding exclusively in water an d consuming diatoms, algae, and detritus (U.S. FWS 2002). Tadpoles filt er and entrap suspended alg ae (Seale and Beckvar 1980) via mouthparts designed for effective grazing of periphyton (Wassersug 1984; Kupferberg et al. 1994; Kupferberg 1997; Altig and McDiarmid 1999).

Juvenile and adult CRLFs forage in aquatic an d terrestrial habitats, and their diet differs greatly from that of larvae. The main food source for juvenile aquatic- and terrestrial35phase CRLFs is thought to be aquatic a nd terrestrial invert ebrates found along the shoreline and on the water surface. Hayes a nd Tennant (1985) report, based on a study examining the gut content of 35 juvenile and adult CRLFs, that the species feeds on as many as 42 different invertebrate taxa, including Arachnida, Amphipoda, Isopoda, Insecta, and Mollusca. The most commonly observed prey sp ecies were larval alderflies ( Sialis cf. californica ), pillbugs ( Armadilliadrium vulgare ), and water striders ( Gerris sp). The preferred prey species, however, was the sowbug (Hayes and Tennant 1985). This study suggests that CRLFs forage primarily above water, although the authors note other data reporting that adults also feed under water, are canniba listic, and consume fish. For larger CRLFs, over 50% of the pr ey mass may consists of vertebrates such as mice, frogs, and fish, although aquatic and terrestrial invertebrates we re the most numerous food items (Hayes and Tennant 1985). For adults, feeding activity takes place primarily at night; for juveniles feeding o ccurs during the day and at ni ght (Hayes and Tennant 1985).

2.5.4. Habitat

CRLFs require aquatic habitat for breeding, but also use other ha bitat types including riparian and upland areas throughout their life cycle. CRLF use of their environment varies; they may complete their entire life cycl e in a particular habitat or they may utilize multiple habitat types. Overall, populati ons are most likely to exist where multiple breeding areas are embedded within varying ha bitats used for dispersal (U.S. FWS 2002). Generally, CRLFs utilize habitat with perennial or near-perennial water (Jennings et al. 1997). Dense vegetation close to water, shadin g, and water of moderate depth are habitat features that appear especially impor tant for CRLF (Hayes and Jennings 1988). Breeding sites include streams, deep pools, b ackwaters within str eams and creeks, ponds, marshes, sag ponds (land depressions between fault zones that have filled with water), dune ponds, and lagoons. Breeding adults have been found n ear deep (0.7 m) still or slow moving water surrounded by dense vegetation (U.S. FWS 2002); however, the largest number of tadpoles have been f ound in shallower pools (0.26 – 0.5 m) (Reis 1999). Data indicate that CRLFs do not frequently inhabit ve rnal pools, as conditions in these habitats generally are not suitable (Hayes an d Jennings 1988).

CRLFs also frequently breed in artificial impoundments such as stock ponds, although additional research is needed to identify habitat requirement s within artificial ponds (U.S. FWS 2002). Adult CRLFs use dense, shrubby, or emergent vegetation closely associated with deep-water pools bordered with cattail s and dense stands of overhanging vegetation ( http://www.fws.gov/endangered/feat ures/rl_frog/rlfrog.html#where ).

In general, dispersal and habitat use depends on climatic conditions, habitat suitability, and life stage. Adults rely on riparian vegetation for resting, feeding, and dispersal. The foraging quality of the riparian habitat de pends on moisture, composition of the plant community, and presence of pools and backwate r aquatic areas for breeding. CRLFs can be found living within streams at distances up to 3 km (2 miles) from their breeding site and have been found up to 30 m (100 feet) from water in dense ripari an vegetation for up to 77 days (U.S. FWS 2002).

36During dry periods, the CRLF is rarely found far from water, although it will sometimes disperse from its breeding habitat to forage and seek other suitable habitat under downed trees or logs, industrial debr is, and agricultural features (UWFWS 2002). According to Jennings and Hayes (1994), CRLFs also use sm all mammal burrows and moist leaf litter as habitat. In addition, CRLFs may also use large cracks in the bottom of dried ponds as refugia; these cracks may provide moisture for individuals avoiding predation and solar exposure (Alvarez 2000).

2.6. Designated Critical Habitat

In a final rule published on April 13, 2006, 34 separate units of critical habitat were designated for the CRLF by U.S. FWS (U.S. FWS 2006; FR 51 19244-19346). A summary of the 34 critical habitat units rela tive to U.S. FWS-desi gnated recovery units and core areas (previously discussed in Sect ion 2.5) is provided in Attachment 1.

‘Critical habitat’ is defined in the ESA as the geographic area occupied by the species at the time of the listing where the physical and biological features necessary for the conservation of the species exis t, and there is a need for special management to protect the listed species. It may also include areas outside the occupied area at the time of listing if such areas are ‘essential to the c onservation of the species.’ All designated critical habitat for the CRLF was occupied at the time of listing. Critical habitat receives protection under Section 7 of the ESA (Secti on 7) through prohibiti on against destruction or adverse modification with regard to act ions carried out, funde d, or authorized by a federal Agency. Section 7 requires consultation on federal actions that are likely to result in the destruction or adverse modification of critical habitat.

To be included in a critical habitat designation, the habitat must be ‘essential to the conservation of the species.’ Critical habi tat designations identify, to the extent known using the best scientific and commercial da ta available, habitat areas that provide essential life cycle needs of th e species or areas that contai n certain primary constituent elements (PCEs) (as defined in 50 CFR 414.12(b )). PCEs include, bu t are not limited to, space for individual and population growth and for normal behavior; food, water, air, light, minerals, or other nutritional or physiolo gical requirements; cove r or shelter; sites for breeding, reproduction, rearing (or developmen t) of offspring; a nd habitats that are protected from disturbance or are representative of the historic geographical and ecological distributions of a species. The de signated critical habitat areas for the CRLF are considered to have the following PCEs that justify critical habitat designation:

• Breeding aquatic habitat;

• Non-breeding aquatic habitat;

• Upland habitat; and

• Dispersal habitat.

Further description of thes e habitat types is provided in Attachment 1.

37Occupied habitat may be include d in the critical habitat only if essential features within the habitat may require special management or protection. Therefore, U.S. FWS does not include areas where existing management is su fficient to conserve the species. Critical habitat is designated outside the geographic area presently occupied by the species only when a designation limited to its present ra nge would be inadequa te to ensure the conservation of the species. For the CRLF, a ll designated critical ha bitat units contain all four of the PCEs, and were occupied by the CRLF at the time of FR listing notice in April 2006. The FR notice de signating critical habitat fo r the CRLF includes a special rule exempting routine ranching activities associated with live stock ranching from incidental take prohibitions . The purpose of this exemption is to promote the conservation of rangelands, which could be bene ficial to the CRLF, and to reduce the rate of conversion to other land uses that are incompatible with CRLF conservation. See Attachment I for a full explanation on this special rule.

U.S. FWS has established adverse modificatio n standards for designated critical habitat (U.S. FWS 2006). Activities that may destroy or adversely modify critical habitat are those that alter the PCEs and jeopardize th e continued existence of the species. Evaluation of actions related to use of dico fol that may alter the PCEs of the CRLF’s critical habitat form the basis of the critical habitat impact analysis. According to U.S. FWS (2006), activities that may affect critical habitat and therefore result in adverse effects to the CRLF include, but are not limited to the following:

(1) Significant alteration of water chemistr y or temperature to levels beyond the tolerances of the CRLF that result in direct or cumulative adverse effects to individuals and their life-cycles. (2) Alteration of chemical characteristics n ecessary for normal growth and viability of juvenile and adult CRLFs. (3) Significant increase in sediment deposition within the stream channel or pond or disturbance of upland fora ging and dispersal habitat that could result in elimination or reduction of habitat necessa ry for the growth and reproduction of the CRLF by increasing the sediment depos ition to levels that would adversely affect their ability to co mplete their life cycles. (4) Significant alteration of channel/pond mor phology or geometry that may lead to changes to the hydrologic functioning of the stream or pond and alter the timing, duration, water flows, and levels that would degrade or eliminate the CRLF and/or its habitat. Such an effect coul d also lead to increased sedimentation and degradation in water quality to levels that are beyond the CRLF’s tolerances. (5) Elimination of upland foraging and/or aes tivating habitat or dispersal habitat. (6) Introduction, spread, or augmentation of non-native aquatic species in stream segments or ponds used by the CRLF. (7) Alteration or elimination of the CRLF’ s food sources or prey base (also evaluated as indirect effects to the CRLF).

As previously noted in Section 2.1, the Agency believes that the analysis of direct and indirect effects to listed speci es provides the basis for an analysis of potential effects on the designated critical habitat. Because dico fol is expected to directly impact living

38organisms within the action area, critical habitat analysis for dicofol is limited in a practical sense to those PCEs of critical habitat that are biological or that can be reasonably linked to biological ly mediated processes.

2.7. Action Area

For listed species assessment purposes, the ac tion area is considered to be the area affected directly or indirectly by the federal action and not merely the immediate area involved in the action (50 CFR 402.02). It is recognized that the overall action area for the national registration of dico fol is likely to encompass considerable portions of the United States based on the large array of agri cultural uses. However, the scope of this assessment limits consideration of the overall action area to those portions that may be applicable to the protection of the CRLF and its designated critical ha bitat within the state of California. The Agency’s approach to defining the action area under the provisions of the Overview Document (U.S. EPA 2004) cons iders the results of the risk assessment process to establish boundaries for that action area with th e understanding that exposures below the Agency’s defined Levels of Concern (LOCs) constitute a no-effect threshold. For the purposes of this assessment, attention will be focused on the footprint of the action ( i.e ., the area where pesticide application occurs), plus all areas where offsite transport ( i.e. , spray drift, downstream dilution, etc .) may result in potential exposure within the state of California th at exceeds the Agency’s LOCs.

Deriving the geographical extent of this portion of the action area is based on consideration of the types of effects that dicofol may be expected to have on the environment, the exposure levels to dicofol that are associated with those effects, and the best available information concerning the use of dicofol and its fate and transport within the state of California. Specific measures of ecological effect for the CRLF that define the action area include any direct and indirect toxic effect to th e CRLF and any potential effects to its critical habita t, including reduction in surviv al, growth, and fecundity as well as the full suite of sublethal effects availa ble in the effects literature. Therefore, the action area extends to a point where envir onmental exposures are below any measured lethal or sublethal effect thre shold for any biological entity at the whole organism, organ, tissue, and cellular level of organization. In situations where it is not possible to determine the threshold for an observed effect, the action area is not spatially limited and is assumed to be the entire state of California.

The definition of action area requires a stepwise approach that begins with an understanding of the federal action. The federa l action is defined by the currently labeled uses for dicofol. An analysis of labeled us es and review of avai lable product labels was completed. Several of the curr ent labels are special local n eeds (SLN) labels for states other than California and several currently la beled uses on FIFRA section 3 labels are restricted to specific states other than Calif ornia and therefore, are excluded from this assessment. For those uses relevant to the CRLF, the analysis indicates that, for dicofol, the following agricultural uses are considered as part of the federal action evaluated in this assessment: beans (dry, snap, and lima), citrus (speci fically, grapefruit, kumquats, lemons, limes, oranges, tangelos, and tang erines), cotton, cucu rbits (specifically, cantaloupes, cucumbers, melons, pumpki ns, watermelons, and winter and summer

39squash), grapes, hops, mint, pecans, peppe rs, pome fruits (specifically, apples, crabapples, pears, and quince), stone fruits (specifically, apricots, sweet and sour cherries, nectarines, peaches, plums, and prune s), strawberries, tomato es, and walnuts. In addition, the following non-food and non-agricu ltural uses are considered: Bermuda grass, turf/ornamental uses (specifically, turf grasses, nursery stock, flowers, shade trees, woody shrubs and vines, and sod farms) and outside building surfaces (nonagricultural).

Following a determination of the assessed uses , an evaluation of th e potential “footprint” of dicofol use patterns ( i.e ., the area where pesticide application occurs) is determined. This “footprint” represents the initial area of concern, based on an analysis of available land cover data for the state of California. Th e initial area of concern is defined as all land cover types and the stream reaches with in the land cover areas that represent the labeled uses described above. A map represen ting all the land cover types that make up the initial area of concern for dicofol is presented in Figure 5 . In this figure, potential uses of dicofol on all field crops as well as orchards and vineyards are represented by the cultivated crops landcover data obtained from NLCD. In ad dition, potential use areas of dicofol on tree fruits and grapes are repres ented by the orchard and vineyard land cover data obtained from California GAP. Turf uses of dicofol are depicted as a derived NLCD class based on developed classes and the impervious surface layer with corrections applied. Additional information on the landcover data used to define the initial area of concern is provided in Appendix B

.

40Figure 5. Initial area of concern for crops descri bed by agricultural landcov er which corresponds to potential dicofol use sites. This map represents the area potentially directly affected by the federal action.

41Once the initial area of conc ern is defined, the next step is to define the potential boundaries of the action area by de termining the extent of offs ite transport via spray drift and runoff where exposure of one or more ta xonomic groups to the pesticide exceeds the listed species LOCs. As previously discus sed, the action area is defined by the most sensitive measure of direct and indirect eco logical toxic effects including reduction in survival, growth, reproduction, and the entire suite of sublethal effects from valid, peerreviewed studies.

Once the potential boundaries of the area of concern are defined, th e next step is to compare the extent of that area with the results of the screen ing-level risk assessment. In this assessment, transport of dicofol through erosion and spray drift is considered in deriving quantitative estimates of dicofol exposure to CRLF, its prey and its habitats. Since this screening-level risk assessment de fines taxa that are predicted to be exposed through runoff and drift to dicofol at concentrations above the Agency’s Levels of Concern (LOC), there is a need to expand the action area to include areas that are affected indirectly by this federal action. Because of the lack of a NOAEC in several chronic toxicity studies with birds, descri bed later in Section 4.3.1, the action area for dicofol is established as the en tire state of California. Additional analysis related to the intersection of the dicofol action area and CRLF habitat used in determining the action area is described in section 5.2.5 and in Appendix B

.

2.8. Assessment Endpoints and Me asures of Ecological Effect

Assessment endpoints are defined as “explicit expressions of the actual environmental value that is to be protected.” 5 Selection of the assessmen t endpoints is based on valued entities ( e.g. , CRLF, organisms important in the life cycle of the CRLF, and the PCEs of its designated critical habitat), the ecosystems potentially at risk ( e.g ., waterbodies, riparian vegetation, and upland a nd dispersal habitats), the mi gration pathways of dicofol ( e.g. , runoff, spray drift, etc.), and the routes by which ecological receptors are exposed to dicofol ( e.g. , direct contact, etc.).

2.8.1. Assessment Endpoints for the CRLF

Assessment endpoints for the CRLF include direct toxic effects on the survival, reproduction, and growth of the CRLF, as well as indirect effects, such as reduction of the prey base or effects to it s habitat. In addition, potential effects to critical habitat is assessed by evaluating potential effects to PCEs, which are components of the habitat areas that provide essential life cycle needs of the CRLF. Each assessment endpoint requires one or more “measures of ecological e ffect,” defined as changes in the attributes of an assessment endpoint or changes in a su rrogate entity or attr ibute in response to exposure to a pesticide. Specific measures of ecological effect ar e generally evaluated based on acute and chronic toxicity information from registrant-submitted guideline tests that are performed on a limited number of orga nisms. Additional ecological effects data from the open literature are also considered. It should be noted that assessment endpoints

5 U.S. EPA (1992). Framework for Ecological Risk Assessment. EPA/630/R-92/001.

42are limited to direct and indire ct effects associated with su rvival, growth, and fecundity, and do not include the full suite of sublethal effects used to define the action area. According the Overview Document (U.S. EPA 2004), the Agency relies on acute and chronic effects endpoints that are either direct measures of impairment of survival, growth, or fecundity or endpoint s for which there is a scientif ically robust, peer reviewed relationship that can quantif y the impact of the measured effect endpoint on the assessment endpoints of survival, growth, and fecundity.

A complete discussion of all the toxicity data available for this risk assessment, including resulting measures of ecologica l effect selected for each ta xonomic group of concern, is included in Section 4 of this document. A summary of the assessment endpoints and measures of ecological effectselected to characterize po tential assessed direct and indirect CRLF risks associated with exposure to dicofol is provided in Table 7

.

43Table 7. Assessment endpoints and measu res of ecological effects for dicofol. Assessment Endpoint Measures of Ecological Effects 3 Aquatic-Phase CRLF (Eggs, larvae, juveniles, and adults) 1 Direct Effects

1. Survival, growth, and reproduction of CRLF 1a. LC 50 = 53.0 μg/L, based on most sensitive acute exposure data available for fish 1b. NOAEC = 4.4 μg a.i./L, based on most sensitive chronic exposure data available for fish Indirect Effects and Critical Habitat Effects

2. Survival, growth, and reproduction of CRLF individuals via indirect effects on aquatic prey food supply ( i.e., fish, freshwater invertebrates, non-vascular plants) 2a. EC 50 = 140 μg/L, based on most sensitive acute exposure data available for aquatic invertebrates 2b. NOAEC = 19 μg a.i./L, based on most sensitive chronic exposure data available for aquatic invertebrates 2c. LC 50 = 53.0 μg/L, based on most sensitive acute exposure data available for fish 2d. NOAEC = 4.4 μg a.i./L, based on most sensitive chronic exposure data available for fish 2e. EC 50 > 5,000, <10,000 μg/L, based on available data for green algae 3. Survival, growth, and reproduction of CRLF individuals via i ndirect effects on habitat, cover, food supply, and/or primary productivity ( i.e., aquatic plant community) 3a. EC 50 > 5,000, <10,000 μg/L, based on available data for green algae

4. Survival, growth, and reproduction of CRLF individuals via effects to riparian vegetation No data are available to quantify an endpoint to represent effects of dicofol exposures to vascular plants.
Terrestrial-Phase CRLF (Juveniles and adults) Direct Effects

5. Survival, growth, and reproduction of CRLF individuals via direct effects on terrestrial phase adults and juveniles 4a. LD 50 = 265 mg a.i./kg bw, based on most sensitive acute oral exposure data available for birds 2 4b. LC 50 = 903 ppm, based on most sensitive subacute dietary exposure data available for birds 2 4c. NOAEC = 1 ppm, based on most sensitive chronic exposure data available for birds 2 Indirect Effects and Critical Habitat Effects

6. Survival, growth, and reproduction of CRLF individuals via effects on terrestrial prey ( i.e., terrestrial invertebrates, small mammals , and frogs) 5a. LD 50 >50 μg a.i./bee, based on most sensitive acute oral exposure data available for terrestrial invertebrates 5b. LD 50 = 587 mg/kg-bw, based on most sensitive acute oral exposure data available for mammals 5c. NOAEC = 5 ppm, based on most sensitive chronic exposure data available for mammals
5d. LD 50 = 265 mg a.i./kg bw, based on most sensitive acute oral exposure data available for birds 2 5e. LC 50 = 903 ppm, based on most sensitive subacute dietary exposure data available for birds 2 5f. NOAEC = 1 ppm, based on most sensitive chronic exposure data available for birds 2 7. Survival, growth, and reproduction of CRLF individuals via i ndirect effects on habitat ( i.e., riparian and upland vegetation) No data are available to quantify an endpoint to represent effects of dicofol exposures to vascular plants.

1 Adult frogs are no longer in the “aquatic phase” of the amphibian life cycle; however , submerged adult frogs are considered “aquatic” for the purposes of this assessment because exposure pathways in the water are considerably different that exposure pathways on land.
2 Birds are used as surrogates for terrestrial phase amphibians.
3 See Table 22 and Table 27 for citations and additional information.

442.8.2. Assessment Endpoints for De signated Critical Habitat

As previously discussed, designated critical ha bitat is assessed to evaluate actions related to the use of dicofol that may alter the PCEs of the CRLF’s critical habitat. PCEs for the CRLF were previously described in Section 2.6. Actions that may modify critical habitat are those that alter the PCEs and jeopardiz e the continued existence of the CRLF. Therefore, these actions are identified as assessment endpoints. It should be noted that evaluation of PCEs as assessment endpoints is limited to those of a biological nature ( i.e
., the biological resource requirements for the lis ted species associated with the critical habitat) and those for which dicofol effects da ta are available. Adverse modification to the critical habitat of the CRLF includes, but is not limited to, t hose listed in Section 2.6.

Measures of such possible effects by labele d use of dicofol on critical habitat of the CRLF are described in Table 8 . Some components of these PCEs are associated with physical abiotic features (e.g., presence and/or depth of a water body, or distance between two sites), which are not expected to be measurably altered by use of pesticides. Assessment endpoints used for the analysis of designated critical ha bitat are based on the adverse modification standard established by U.S. FWS (2006).

45Table 8. Summary of dicofol assessment endpoints and measures of ecological effect for primary constituent elements of designated critical habitat 1

. Assessment Endpoint Measures of Ecological Effect 3

Aquatic-Phase CRLF PCEs (Aquatic Breeding Habitat and Aquatic Non-Breeding Habitat) Alteration of channel/pond morphology or geometry and/or increase in sediment deposition within the stream channel or pond: aquatic habitat (including riparian vegetation) provides for shelter, foraging, predator avoidance, and aquatic dispersal for juvenile and adult CRLFs. No data are available to quantify an endpoint to represent effects of dicofol exposures to vascular plants.

Alteration in water chemistry/quality including temperature, turbidity, and oxygen content necessary for normal growth and viability of juvenile and adult CRLFs and their food source. 1e. EC 50 > 5,000, <10,000 μg/L, based on available data for green algae No data are available for assessing the effects of exposures of dicofol to vascular plants.

Alteration of other chemical characteristics necessary for normal growth and viability of CRLFs and their food source. 1a. LC 50 = 53.0 μg/L, based on most sensitive acute exposure data available for fish 1b. NOAEC = 4.4 μg a.i./L, based on most sensitive chronic exposure data available for fish 1c. EC 50 = 140 μg/L, based on most sensitive acute exposure data available for aquatic invertebrates 1d. NOAEC = 19 μg a.i./L, based on most sensitive chronic exposure data available for aquatic invertebrates 1e. EC 50 > 5,000, <10,000 μg/L, based on available data for green algae Reduction and/or modification of aquatic-based food sources for pre-metamorphs ( e.g., algae) 1e. EC 50 > 5,000, <10,000 μg/L, based on available data for green algae Terrestrial-Phase CRLF PCEs (Upland Habitat and Dispersal Habitat) Elimination and/or disturbance of upland habitat; ability of habitat to support food source of CRLFs: Upland areas within 200 ft of the edge of the riparian vegetation or dripline surrounding aquatic and riparian habitat that are comprised of grasslands, woodlands, and/or wetland/riparian plant species that provides the CRLF shelter, forage, and predator avoidance No data are available to quantify an endpoint to represent effects of dicofol exposures to vascular plants.

Elimination and/or disturbance of dispersal habitat: Upland or riparian dispersal habitat within designated units and between occupied locations within 0.7 mi of each other that allow for movement between sites including both natural and altered sites which do not contain barriers to dispersal No data are available to quantify an endpoint to represent effects of dicofol exposures to vascular plants.

Reduction and/or modification of food sources for terrestrial phase juveniles and adults 2a. LD 50 >50 μg a.i./bee, based on most sensitive acute exposure data available for terrestrial invertebrates 2b. LD 50 = 587 mg/kg-bw, based on most sensitive acute oral exposure data available for mammals 2c. NOAEC = 5 mg/kg-bw, based on most sensitive chronic exposure data available for mammals 2d. LD 50 = 265 mg a.i./kg bw, based on most sensitive acute oral exposure data available for birds 2 2e. LC 50 = 903 mg/kg-bw, based on most sensitive subacute dietary exposure data available for birds 2 2f. NOAEC = 1 mg/kg-bw, based on most sensitive chronic exposure data available for birds 2

46Assessment Endpoint Measures of Ecological Effect 3

Alteration of chemical characteristics necessary for normal growth and viability of juvenile and adult CRLFs and their food source. 3a. LD 50 = 265 mg a.i./kg bw, based on most sensitive acute oral exposure data available for birds 2 3b. LC 50 = 903 mg/kg-bw, based on most sensitive subacute dietary exposure data available for birds 2 3c. NOAEC = 1 mg/kg-bw, based on most sensitive chronic exposure data available for birds 2
1 Physico-chemical water quality parameters such as sa linity, pH, and hardness are not evaluated because these

processes are not biologically mediated and, therefore, are not relevant to th e endpoints included in this assessment. 2 Birds are used as surrogates for terrestrial phase amphibians. 3 See Table 22 and Table 27 for citations and additional information.

2.9. Conceptual Model

2.9.1. 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 (U.S. EPA 1998a). For this assessment, the risk is stressor-linked, where th e stressor is the release of dico fol to the environment. The following risk hypotheses are presumed fo r this endangered species assessment:

The labeled use of dicofol within the action area may:

• directly affect the CRLF by causing mortal ity or by adversely a ffecting growth or fecundity;

• indirectly affect the CRLF by reduci ng or changing the composition of food supply;

• indirectly affect the CRLF or affect designated critical habitat by reducing or changing the composition of the aquatic plant community in the ponds and streams comprising the species’ current range and designated critical habitat, thus affecting primary productivity and/or cover;

• indirectly affect the CRLF or affect designated critical habitat by reducing or changing the composition of the terrestrial plant community ( i.e ., riparian habitat) required to maintain acceptable water quali ty and habitat in the ponds and streams comprising the species’ current range and designated critical habitat;

• affect the designated critical habita t of the CRLF by reducing or changing breeding and non-breeding aquatic habitat vi a effects to water quality parameters, habitat morphology, and/or sedimentation;

• affect the designated cr itical habitat of the CRLF by reducing the food supply required for normal growth and viabili ty of juvenile and adult CRLFs;

• affect the designated critical habitat of the CRLF by reducing or changing upland habitat within 200 ft of the edge of the riparian vegetation necessary for shelter, foraging, and predator avoidance;

• affect the designated critical habita t of the CRLF by reducing or changing dispersal habitat within designated units and between occupied locations within

470.7 mi of each other that allow for movement between sites including both natural and altered sites which do not c ontain barriers to dispersal; or,

• affect the designated critical habitat of the CRLF by altering chemical characteristics necessary for normal growth and viability of juvenile and adult CRLFs.

2.9.2. Diagram

The conceptual model is a graphic representation of the structure of the risk assessment. It specifies the dicofol release mechanis ms, biological receptor types, and effects endpoints of potential concern. The conceptual models fo r aquatic and terrestrial exposures are shown in Figure 6 and in Figure 7 , respectively, which include the conceptual models for the aquatic and terrestrial PCE components of cr itical habitat. Exposure routes shown in dashed lines are not quantitatively considered because the contribution of those potential exposure r outes to potential risks to the CRLF and modification to designated critical habitat is expected to be negligible.

Stressor

Source

Receptors

Attribute Change Dicofol isomers, degradates, and DDT applied to use site

Spray drift

Fish/aquatic-phase amphibians **Piscivorous mammals and birds

Individual organisms Reduced survival Reduced growth Reduced reproduction Food chain Reduction in algae Reduction in prey Modification of PCEs related to prey availability Habitat integrity Reduction in primary productivity Reduced cover Communit y change Modif ication of PCEs related to habit at Surface water/ Sediment Runoff

Aquatic Animals Invertebrates Vertebrates Exposure Media

Uptake/gills or integument

Ingestion Ingestion Long range atmospheric

transport

Wet/dry deposition Soil Groundwater

Uptake/gills or integument

Aquatic Plants Non-vascular Vascular Uptake/cell, roots, leaves Riparian plant terrestrial exposure pathways see Figure 7

Figure 6. Conceptual model for dicofol e ffects on aquatic-ph ase of the CRLF.

48Stressor

Source

Receptors

Attribute Change Dicofol isomers, degradates, and DDT applied to use site

Direct application Spray drift

Birds/terrestrialphase amphibians/ reptiles/mammals

Terrestrial

insects

Individual organisms Reduced survival Reduced growth Reduced reproduction Food chain Reduction in prey Modification of PCEs related to prey availability Habitat integrity Reduction in primary productivity Reduced cover Community change Modification of PCEs related to habitat Terrestrial/riparian plants grasses/forbs, fruit, seeds (trees, shrubs) Runoff

Mammals/ Birds Exposure Media Soil

Ingestion Ingestion

Ingestion Ingestion Dermal uptake/Ingestion Long range atmospheric

transport

Root uptake Wet/dry deposition

Terrestrialphase amphibians

Ingestion

Figure 7. Conceptual model for dicofol e ffects on terrestrial phase of the CRLF.

2.10. Analysis Plan

In order to address the risk hypothesis, the potential for di rect and indirect effects to the CRLF, its prey, and its habitat is estimat ed. In the following sections, the use, environmental fate, and ecological effects of dicofol are char acterized and integrated to assess the risks. This is accomplished us ing a risk quotient (ratio of exposure concentration to effects concen tration) approach. Although ri sk is often defined as the likelihood and magnitude of adverse ecological effects, the risk quotient-based approach does not provide a quantitative estimate of likelihood and/or magnitude of an adverse effect. However, as outlin ed in the Overview Document (U.S. EPA 2004), the likelihood of effects to individual organisms from particul ar uses of dicofol is estimated using the probit dose-response slope and either the leve l of concern (discusse d below) or actual calculated risk quotient value.

492.10.1. Measures of Exposure

The environmental fate properties of dico fol along with available monitoring data indicate that runoff and spray drift are the principle potential transport mechanisms of dicofol to the aquatic and terrestrial habitats of the CRLF. In this assessment, transport of dicofol through runoff and spray drift is considered in derivi ng quantitative estimates of dicofol exposure to CRLF, its prey and its habitats. Because of its low vapor pressure and persistence in the air (T 1/2 > 2 days), dicofol has the poten tial for long range transport. It should be noted, however, that recent ambient air monitoring in agricultural communities in California does not indicate volatilization of dicofol (See Section 3.2.4.2).

Measures of exposure are based on aquatic and terrestrial models th at predict estimated environmental concentrations (EECs) of dicofol using maximum labeled application rates and methods of application. The models used to predict aquatic EECs are the Pesticide Root Zone Model coupled with the Exposur e Analysis Model System (PRZM/EXAMS). The model used to predict terrestrial EECs on food items is T-REX. The model used to derive EECs relevant to terrestrial and wetla nd plants is TerrPlant. These models are parameterized using relevant reviewed registrant-submitted environmental fate data. Additionally, the Generic Estimated Envir onmental Concentration Model (GENEEC2) was used to characterize the potential impacts due to the DDT manufacturing intermediate in dicofol (see Appendix F ).

PRZM (v3.12.2, May 2005) and EXAMS (v2.98.4.6, April 2005) are simulation models coupled with the input shell pe5.pl (Aug 2007) to generate daily exposures and 1-in-10 year EECs of dicofol that may occur in surf ace water bodies adjacent to application sites receiving dicofol through runoff and spray drif t. PRZM simulates pesticide application, movement and transformation on an agricultural field and the resultant pesticide loadings to a receiving water body via runoff, erosion and spray drift. EXAMS simulates the fate of the pesticide and resulting concentrations in the water body. Th e standard scenario used for ecological pesticide assessments assu mes application to a 10-hectare agricultural field that drains into an adjacent 1- hectare water body, 2-meters deep (20,000 m 3 volume) with no outlet. PRZM/EXAMS was used to es timate screening-level exposure of aquatic organisms to dicofol. The measure of expos ure for aquatic species is the 1-in-10 year return peak or rolling mean concentration. The 1-in-10 year peak is used for estimating acute exposures of direct eff ects to the CRLF, as well as indirect effects to the CRLF through effects to potential prey items, including : algae, aquatic invertebrates, fish and frogs. The 1-in-10-year 60-day mean is used for assessing chronic exposure to the CRLF and fish and frogs serving as prey items; the 1-in-10-year 21-day mean is used for assessing chronic exposure for a quatic invertebrates, which are also potential prey items.

GENEEC2 Version 2.0 is a screening-level mode l used in pesticide aquatic ecological risk assessments. Similar to PRZM/EXAM S, GENEEC2 uses the soil/water partition coefficient and degradation kine tic data to estimate runoff from a ten hectare field into a one hectare by two meter deep “standard” pond.

50Exposure estimates for the terrestrial-phase CRLF and terrestrial invertebrates and mammals (serving as potential prey) assumed to be in the target area or in an area exposed to spray drift are derived using the T-REX model (ver sion 1.3.1, 12/07/2006). This model incorporates the Kenega nomograph, as modified by Fletcher et al. (1994), which is based on a large set of actual field residue data. The upper limit values from the nomograph represented the 95 th percentile of residue values from actual field measurements (Hoerger and Kenega 1972). For modeling purposes, direct exposures of the CRLF to dicofol through contaminated fo od are estimated using the EECs for the small bird (20 g) which consumes small inse cts. Dietary-based a nd dose-based exposures of potential prey (small mammals) are assessed using the small mammal (15 g) which consumes short grass. The small bird ( 20g) consuming small insects and the small mammal (15g) consuming short grass are used because these categories represent the largest RQs of the size and dietary categorie s in T-REX that are appropriate surrogates for the CRLF and one of its prey items. Es timated exposures of te rrestrial insects to dicofol are bound by using the dietary based EEC s for small insects and large insects.

Birds are currently used as surrogates for te rrestrial-phase CRLF. However, amphibians are poikilotherms (body temperature varies w ith environmental temperature) while birds are homeotherms (temperature is regulated , constant, and larg ely independent of environmental temperatures). Therefore, am phibians tend to have much lower metabolic rates and lower caloric intake requirements than birds or mammals. As a consequence, birds are likely to consume more food than amphibians on a daily di etary intake basis, assuming similar caloric content of the food items. Therefore, the use of avian foodintake allometric equation as a surrogate to amphibians is likely to result in an overestimation of exposure and risk for reptiles an d terrestrial-phase amphibians. Therefore, T-REX (version 1.3.1) has been refined to the T-HERPS model (v. 1.0), which allows for an estimation of food intake for poikilotherms using the same basic procedure as T-REX to estimate avian food intake.

The spray drift model AgDRIFT is used to assess exposures of terrestrial phase CRLF and its prey to dicofol deposited on terrestrial habitats by spray drift. In addition to the buffered area from the spray drift analysis, th e downstream extent of dicofol that exceeds the LOC for the effects determination is also considered.

KABAM (K OW (based) A quatic B ioA ccumulation M odel) v.1.0 is used to estimate potential bioaccumulation of dicofol in fres hwater aquatic food webs and subsequent risks to mammals and birds via consumption of contaminated aquatic prey. In this case, exposures to birds are used as a surrogate for CRLF consuming aquatic organisms that have bioaccumulated dicofol a nd its degradates of concern.

Lastly, in order to characterize the long ra nge transport potential (LRTP) of dicofol and its degradates, the OECD P ov and LRTP Screening Tool was used. Three chemicals known to move via long range transport, DDT, aldrin and endrin, were also modeled to provide a context for the dicofol-estimated LRTP . It should be noted that OPP is not able to quantify the extent to which dicofol an d its degradates will undergo long-range

51atmospheric transport once it has been released from a treatment site and, as such, cannot quantify the amount of exposure that could potentially occur to nontarget an imals distant from the use sites.

2.10.2. Measures of Effect

Data identified in Section 4 are used as measur es of effect for direct and indirect effects to the CRLF. Data were obtained from registrant submitted studies or from literature studies identified by ECOTOX. The ECOTOXicology database (ECOTOX) was searched in order to provide more ecological effects data and in an attempt to bridge existing data gaps. ECOTOX is a source for locating single chemical toxicity data for aquatic life, terrestrial plants, and wildlife. ECOTOX was created and is maintained by the U.S. EPA, Office of Research and Development, and th e National Health and Environmental Effects Research Laboratory's Mid- Continent Ecology Division.

The assessment of risk for direct effect s to the terrestrial-phase CRLF makes the assumption that toxicity of dicofol to birds is similar to or less than the toxicity to the terrestrial-phase CRLF. The same assumption is made for fish and aquatic-phase CRLF. Algae, aquatic invertebrates, fish, and amphi bians represent potential prey of the CRLF in the aquatic habitat. Terrestrial invertebrates, small mammals, and terrestrial-phase amphibians represent potential pr ey of the CRLF in the terrestri al habitat. Aquatic, semiaquatic, and terrestrial plants represent habitat of CRLF.

The acute measures of effect used for animal s in this screening level assessment are the LD 50 , LC 50 and EC 50 . LD stands for "Lethal Dose", and LD 50 is the amount of a material, given all at once, that is estimated to cause the death of 50% of the test organisms. LC stands for “Lethal Concentration” and LC 50 is the concentration of a chemical that is estimated to kill 50% of the test organisms. EC stands for ‘Effective Concentration’ and the EC 50 is the concentration of a chemical that is estimated to produce a specific effect in 50% of the test organisms. Endpoints for chronic measures of exposure for listed and non-listed animals are the NOAEL/NOAEC and NOEC. NOAEL stands for ‘No Observed-Adverse-Effect-Level’ and refers to the highest tested dose of a substance that has been reported to have no harmful (advers e) effects on test organisms. The NOAEC ( i.e. , ‘No-Observed-Adverse-Effect -Concentration’) is the highe st test concentration at which none of the observed effects were statis tically different from the control. The NOEC is the No-Observed-Effects-Concentr ation. For non-listed plants, only acute exposures are assessed ( i.e. , EC 25 for terrestrial plants and EC 50 for aquatic plants).

It is important to note that the measures of direct and indirect eff ects to the CRLF and its designated critical habitat are associated with impacts to survival, growth, and fecundity, and do not include the full suite of sublethal effects used to define the action area. According the Overview Document (USE PA 2004), the Agency relies on effects endpoints that are either direct measures of impairment of survival, growth, or fecundity or endpoints for which there is a scientifically robust, peer reviewed relationship that can quantify the impact of the measured effect endpoint on the asse ssment endpoints of survival, growth, and fecundity.

522.10.3. Integration of Exposure and Effects

Risk characterization is the in tegration of exposure and ecolo gical effects characterization to determine the potential ecol ogical risk from agricultural and non-ag ricultural uses of dicofol, and the likelihood of di rect and indirect e ffects to CRLF in aquatic and terrestrial habitats. The exposure and toxicity effects da ta are integrated in order to evaluate the risks of adverse ecological effects on non-targ et species. For the assessment of dicofol risks, the risk quotient (RQ) method is used to compare expo sure and measured toxicity values. EECs are divided by acute and chroni c toxicity values. The resulting RQs are then compared to the Agency’s levels of concern (LOCs) (U.S. EPA 2004) (see Appendix C ).

For this endangered species assessment, listed species LOCs are used for comparing RQ values for acute and chronic exposures of di cofol directly to the CRLF. If estimated exposures directly to the CRLF of dicofol resulting from a particular use are sufficient to exceed the listed species LOC, then the effects determination for that use is ‘may affect’. When considering indirect effects to the CRLF due to effects to animal prey (aquatic and terrestrial invertebrates, fis h, frogs, and mice), the listed species LOCs are also used. If estimated exposures to CRLF prey of dicofol resulting from a particular use are sufficient to exceed the listed species LOC, then the effects determination for that use is a ‘may affect.’ If the RQ being considered also exceeds the non-listed species acute risk LOC, then the effects determination is an LAA. If the acute RQ is between the listed species LOC and the non-listed acute risk species LOC, then further lines of evidence ( i.e

. probability of individual effects, species se nsitivity distributions) are considered in distinguishing between a determ ination of NLAA and a LAA. When considering indirecteffects to the CRLF due to effects to algae as dietary items or plants as habitat, the nonlisted species LOC for plants is used because the CRLF does not have an obligate relationship with any particul ar aquatic and/or terrestria l plant. If the RQ being considered for a particular use exceeds the non-listed species LOC for plants, the effects determination is ‘may affect.’ Furt her information on LOCs is provided in Appendix C

. 2.10.4. Data Gaps

There are currently no submitted studies quantifying the environmental fate and transport of the major degradates of dicofol individua lly. Additionally, aerobi c and anaerobic soil metabolism studies were conducted using slightly alkaline (pH from 7.5 to 7.9) soil, so soil metabolism studies under acid ic soil conditions are missing. It should also be noted that a study on photodegradati on in air for dicofol and it s degradates has not been submitted.

No data are available for asse ssing the effects of exposures of dicofol to freshwater vascular plants. Genera lly, data for duckweed ( Lemna gibba ) are used to assess these effects.

53In addition, no data are available to quantify an endpoint to represent effects of dicofol exposures to riparian and terrestrial vegeta tion (vascular plants), which are generally represented by effects data for terre strial agricultural crop species.

Limited data are available to determine the toxicity of dicofol’s major degradates to aquatic or terrestrial organisms.



### 3.0 Exposure Assessment

Dicofol is formulated as a wettable powder and emulsifiable formulation. Application equipment includes: ground application, aerial application, and various sprayers (highand low-volume. Risks from ground boom and aer ial applications are expected to result in the highest off-target levels of dicofol due to generally higher spray drift levels. Ground boom and aerial modes of application te nd to use lower volum es of application applied in finer sprays than applications coin cident with sprayers and spreaders and thus have a higher potential for off-targ et movement via spray drift.

3.1. Label Application Rates and Intervals

Dicofol labels may be categorized into tw o types: labels for manufacturing uses (including technical grade dico fol and its formulated produc ts) and end-use products. While technical products, which contain dicofol of high purity, are not used directly in the environment, they are used to make formulated products, which can be applied in specific areas to control mites. The form ulated product labels legally limit dicofol’s potential use to only those sites th at are specified on the labels.

Currently registered agricultural and non-agri cultural uses of dicofol within California include: beans (dry, snap, and lima), citrus (specifically, grapefru it, kumquats, lemons, limes, oranges, tangelos, and tangerines), cotton, cucurbits (specifically, cantaloupes, cucumbers, melons, pumpkins, watermelons, a nd winter and summer squash), grapes, hops, mint, pecans, peppers, pome fruits (spe cifically, apples, crabapples, pears, and quince), stone fruits (specifically, apricots, sw eet and sour cherries, nectarines, peaches, plums, and prunes), strawberries, tomatoes, wa lnuts, Bermuda grass, turf/ornamental uses (specifically, turf grasses, nur sery stock, flowers, shade trees, woody shrubs and vines, and sod farms) and outside building surfaces (non-agricultural). The model scenarios and application input parameters for the uses incl uded in this risk asse ssment are summarized in Table 9

.

54Table 9. Dicofol uses and application in formation for the CRLF risk assessment 1

.

Crop Uses Represented by Scenario PRZM/EXAMS Scenario Application Rate (lbs a.i./acre) Number of Applications Application Interval Application Method

Beans (dry, green, lima) CA row crop RLF 1.5 1 Annually ULV, Aerial, ground

Citrus Grapefruit, kumquats, lemons, limes,
oranges, tangelos, tangerines CA citrus 3 1 Annually ULV, Aerial, ground

Cotton CA cotton 1.5 1 Annually ULV, Aerial, ground

Cucurbits Cantaloupes, cucumbers, melons, pumpkins, watermelons, winter and

summer squash CA melons RLF 0.625 1 Annually ULV, Aerial, ground

Grapes CA wine grapes RLF 1.25 1 Annually ULV, Aerial, ground

Hops OR hops 1.165 1 Annually ULV, Aerial, ground

Mint Mint, peppermint, spearmint OR mint 1.25 1 Annually ULV, Aerial, ground

Pecans CA almonds 2 1 Annually ULV, Aerial, ground

Peppers CA row crop RLF 0.75 1 Annually ULV, Aerial, ground

Pome fruits Apples, crabapples, pears, quince CA fruit 3 1 Annually ULV, Aerial, ground

Stone fruits Apricots, sweet and

sour cherries, nectarines, peaches, plums,
prunes CA fruit 1.5 1 Annually ULV, Aerial, ground

55Crop Uses Represented by Scenario PRZM/EXAMS Scenario Application Rate (lbs a.i./acre) Number of Applications Application Interval Application Method

Strawberries CA strawberries (non-plastic) 2 1 Annually ULV, Aerial, ground

Tomatoes CA tomato 0.75 1 Annually ULV, Aerial, ground

Walnuts CA almonds 2 1 Annually ULV, Aerial, ground Bermudagrass CA turf RLF 0.4 1 Annually Ground Turf grasses CA turf RLF 0.5 1 Annually Ground

Sod farm turf CA turf RLF 0.5 1 Annually Ground

Ornamentals Nurseries, ornamentals, flowers, shade trees CA nursery 0.5 1 Annually Ground

Outside building surfaces CA impervious RLF and CA turf RLF 0.5 1 Annually Ground

1. Uses assessed based on maximum label rates for registered dicofol products.

The labels for dicofol also specify that applications using ground equipment should not be made within 25 feet, or by air within 150 f eet, of lakes, reservoirs, rivers, permanent streams, marshes, natural ponds, estuaries, or commercial fish farm ponds. The spray drift buffer zone is 450 feet when ultra low volume application is made.

3.2. Aquatic Exposure Assessment

3.2.1. Modeling Approach

Aquatic exposures are quantitatively estimated for all of assessed uses using scenarios that represent high exposure sites for dicofol use in California. Each of these sites represents a 10-hectare field that drains into a 1-hectare pond that is 2 meters deep and has no outlet. Exposure estimates generated using the standard pond are intended to represent a wide variety of vul nerable water bodies that occu r at the top of watersheds including prairie pot holes, playa lakes, wetlands, vernal pools, man-made and natural ponds, and intermittent and first-order streams. As a group, there are factors that make these water bodies more or less vulnerable than the standard surrogate pond. Static water bodies that have larger ratios of drainage area to water body volume would be expected to have higher peak EECs than the standard pond. These water bodies will be either more shallow or have larger drainage areas (o r both). Shallow water bodies tend to have limited storage capacity, and thus, tend to overflow and carry pesticide in their discharge whereas the standard pond ha s no discharge. As waters hed size increases beyond 10 hectares, at some point, it becomes unlikely that the entire watershed is planted to a single crop and which is all concurrently treat ed with the pesticide. Headwater streams

56can also have peak concentrations higher than the standard pond, but these peaks in pesticide concentrations tend to persist for only short periods of time and are then carried downstream.

Crop-specific management practices for all of the assessed uses of dicofol were used for modeling, including application rates, buffer widths and re sulting spray drift values modeled from AgDRIFT and the first application date for each crop. The date of first application was developed based on several sources of information including data provided by EPA/OPP/BEAD, a summary of i ndividual applications from the CDPR PUR data, and Crop Profiles maintained by the USDA. A sample of the distribution of dicofol applications to cotton from the CDPR PUR data for 2004 used to pick an application date is shown in Figure 8 . More detail on the crop profiles and the previous assessments may be found at: http://www.ipmcenters.org/CropProfiles/

. In defining the date of application, available CDPR PUR data were analyzed to determine the time period when greater than 90% of applications took place. An initial first application date was then selected from the month at the beginning of this range. Then, the corresponding PRZM/EXAMS scenarios used in the modeling effort were examined and dates for crop emergence, maturation, and harvest were evaluated. As mites usually rely on leaves and fruit as food sources, the midpoint date between emergence and maturation was estimated. If the crop scenario indicated that the cr op was grown all year, a date of January 15 th was selected to result in a cons ervative EEC that would result from increased rainfall experienced in Califor nia during the winter months. If the PRZM/EXAMS midpoint date occurred within the time period of the CDPR PUR 90%, then the PRZM/EXAMS midpoint date was us ed as the date of first application. Otherwise, the initial CDPR PUR date was used. For example, according to the CDPR PUR data, 90% of the dicofol use on cott on was between May and August, and May 3 rd was selected as the initial date of first a pplication. In the PRZM/EXAMS scenario for California cotton, crop emergence occurs on May 1 st and crop maturation occurs on September 20 th , with a midpoint around July 11 th . As this midpoint lies within the range of the 90% data obtained from CDPR PUR, July 11 th was selected as th e first application date for modeling purposes.

570 500 1000 1500 2000 2500 3000 3500 4000 45005/3/20045/10/20045/17/20045/24/20045/31/20046/7/20046/14/20046/21/20046/28/20047/5/20047/12/20047/19/20047/26/20048/2/20048/9/20048/16/2004Pounds Applied

Figure 8. Summary of applications of dicofol to cotton in 2004 from CDPR PUR data.

Once the separate PRZM/EXAMS runs for o,p ’- and p,p ’-dicofol are finished, the daily EECs are summed to generate a total daily parent dicofol EEC. This was done to facilitate comparison of the various EECs to the appropriate endpoints, which were based on total dicofol. Average 21-day, 60-day, and annual EECs of these total daily dicofol EECs were calculated. Maximum values were then estimated for each year and 1-in-10 year return peak and rolling means for th e 21-day, 60-day, and annual concentrations were estimated for each scenario. The same analyses were conducted for the o,p ’- and p,p’ -dicofol and degr adate scenarios.

3.2.2. PRZM Scenarios

PRZM scenarios used to model aquatic exposur es resulting from app lications of specific uses are identified in Table 9

. In cases where a scenario does not exist for a specific use, it is necessary to assign a surrogate scenar io. Those surrogates are assigned to be most representative of the use being considered. Justifications for assi gnments of surrogates are defined below.

Row crop scenario

This scenario is intended to represent production of carrots, beans, peppers and other crops in CA, and is therefore, directly relevant to these uses.

58Citrus scenario

This scenario is intended to represent applica tions of pesticides to oranges, grapefruit, kumquats, lemons, limes, taneglos, and tanger ines in CA and is therefore, directly relevant to this use.

Cotton scenario

This scenario is intended to represent applications of pesticides to cotton in CA and is therefore, directly re levant to this use.

Melon scenario

This scenario is intended to represent ap plications of pesticides to cantaloupes, cucumbers, melons, pumpkins, watermelons, winter and summer squash in CA and is therefore, directly re levant to this use.

Wine grapes scenario

From 2002 to 2007, CA PUR data indicate that dicofol was used mostly on grapes grown for wine production, as opposed to grapes grow n for consumption, in 31 counties. This scenario is intended to represent applications of pesticides to wine grapes in CA and is therefore, directly re levant to this use.

Hops

This scenario, developed based on a hops vineyard in the Pacific Northwest, represents a vineyard located nort h of the area where hops are grown in CA Since the locations where hops are grown in CA are mostly in the no rthern part of the stat e, this scenario was deemed appropriate for m odeling hops grown in CA.

Mint

According to NASS data, mint (grown for o il) has been grown in Lassen, Shasta and Siskiyou Counties. These c ounties are located in norther n CA, bordering OR. Although this scenario represents a field located north of the area where mint is grown in CA, it was developed based on a mint fi eld in the Pacific Northwest. Since the locations where mint is grown in CA are in the northern pa rt of the state, this scenario was deemed appropriate for modeling mint grown in CA.

Almond scenario

This scenario is intended to represent alm ond production in CA and is therefore, directly relevant to this use. Walnuts and pecans are nut trees with similar practices and have been assigned to this scenario.

59Fruit scenario

The CA fruit scenario represents a deciduous fruit tree orchard in Fresno County, which is located in the Central Valley. This scenar io is intended to represent non-citrus fruit, including apples, crabapples, pe ars, quince, apricots, sweet a nd sour cherries, nectarines, peaches, plums, and prunes.

Strawberry scenario

This scenario is intended to represent applic ations of pesticides to strawberries, nontarped, in CA. While the majority of strawb erry growers use tarps, this scenario is considered a conservative appro ach and is therefore, direct ly relevant to this use.

Tomato scenario

This scenario is intended to represent applications of pesticides to tomatoes in CA and is therefore, directly re levant to this use.

Turf scenario

This scenario is intended to represent applic ations of pesticides to sod farms, parks, recreational fields, grass for seed, and golf c ourses in CA and is therefore, directly relevant to this use.

Nursery scenario

This scenario is intended to represent appli cations of pesticides in outdoor nurseries in CA and is therefore, direc tly relevant to this use.

Outside buildings

Two scenarios were used to assess this us e pattern: CA impervi ous and CA turf. The label indicates that to control clover mites, “thoroughly spray the outside walls, foundations, and windowsills and plants and lawn at the base of infested buildings.” For the 10-hectare scenario used in PRZM/EXAMS, it was assumed that a building was at the center of each hectare. Each building was assumed to be a square measuring 15,000 square feet, with turf on three sides of the bu ilding and impervious surface on one side. It was assumed a 10-foot swath was treated on the sides with turf and that the side with the impervious surface would be treated up to a he ight of three feet along the building wall. This results in approximately 3.75% of the watershed being treated. A detailed description of the rationale fo r this value is provided in Appendix D.

603.2.3. Model Inputs

The appropriate chemical-speci fic PRZM input parameters ar e selected from reviewed environmental fate data submitted by the registrant ( Table 3 ) and in accordance with EFED water model input parameter selec tion guidance (U.S. EPA 2002). The input parameters selected are similar to those used in the 1998 dicofol RED (U.S. EPA, 1998b). A summary of the chemical specific model inputs used in this assessment are provided in Table 10 and Table 11

.

Table 10. Summary of PRZM/EXAMS environmental fa te data used for aquatic exposure inputs for o,p’ -dicofol. 1

Fate Property Value (unit) MRID (or source) Comment

Molecular Weight 370.5 g/mole 00141704; 00142595

Henry’s constant 1.44 x 10 -7 atmm 3 /mol Estimated using VP, MW and solubility: HLC=VPxMW/Sol Vapor Pressure 3x10 -7 torr 00141704; 00142595

Solubility in Water 1.32 mg/L 00141704; 00142595

Photolysis in Water 27.5 days 40849702

Aerobic SoilMetabolism Halflives 25.5 days (parent) 313.5 days (total) 41094201 3x single value

Hydrolysis 3.3 x 10 -1 days 40042033 Aerobic Aquatic Metabolism (water column) 51 days (parent) 627 days (total) -- Assumed: 2x aerobic soil half-life Anaerobic Aquatic Metabolism (benthic) 0 d -- Assumed stable, no reviewed data

Koc 7,060 mL/g 41509802 ≤ 2.5% of parent found in leachate. Used value from p,p’ -dicofol. 1 – Inputs determined in accordance with EFED “Gui dance for Chemistry and Management Practice Input Parameters for Use in Modeling the Environmental Fate and Transport of Pesticides” dated February 28, 2002

61Table 11. Summary of PRZM/EXAMS environmental fa te data used for aquatic exposure inputs for p,p' -dicofol. 1

Fate Property Value (unit) MRID (or source) Comment

Molecular Weight 370.5 g/mole 00141704; 00142595

Henry’s constant 1.44 x 10 -7 atmm 3 /mol Estimated using VP, MW and solubility, HLC=VPxMW/Sol Vapor Pressure 3x10 -7 torr 00141704; 00142595

Solubility in Water 1.32 mg/L 00141704; 00142595

Photolysis in Water 244 days 40849701

Aerobic SoilMetabolism Halflives 96 days (parent) 939 days (total) 41050701 3x single value

Hydrolysis 2.8 days 40042032 Aerobic Aquatic Metabolism (water column) 192 days (parent) 1,878 days (total) 2x aerobic soil half-life

Anaerobic Aquatic Metabolism (benthic) 0 d Assumed stable, no reviewed data

K oc 7060 mL/g 41509801 Average K oc 1 – Inputs determined in accordance with EFED “Gui dance for Chemistry and Management Practice Input Parameters for Use in Modeling the Environmental Fate and Transport of Pesticides” dated February 28, 2002

For p,p' -dicofol, a regression analysis between the K d and organic carbon content values indicated a high r-squared value (0.98) and statistical significa nce (<0.01). To assess the appropriateness of the K oc model, a comparison of the coefficient of variation for the K oc. (CV = 19) was compared to the coefficient of variation for K d (CV = 58). Since the CV for the K oc was less than the CV for K d , the average K oc of 7060 mL/g was used (Kashuba et al. 2006). For o,p ’-dicofol, the majority of dicofol remained in upper 2 inches of soil columns, with less than 2.5% of dicofo l found in leachate. As a result, a K oc of 0 was used during modeling.

As depicted in Table 3 , the aerobic soil half-lives for the parent dicofol isomers were significantly less than the half-lives estimated for the total residues of parent and degradates of concern (8.5 vs. 104.5 days for o,p ’-dicofol and 32 vs 313 days for p,p ’- dicofol). As these values indicate a significant increase in persistence in the environment, separate model runs were conducted for the parent isomers and the parent plus degradate.

For the PRZM input “chemical application meth od” (CAM), a value of 2 was selected to represent foliar applications. For aerial ap plications, using the 150-foot buffer zone stipulated on the label, an application efficiency of 0.95 wa s derived using AgDrift, with

62a spray drift fraction of 0.039. For ground appl ications, using the 25-foot buffer zone stipulated on the label, an application efficiency of 0.99 wa s derived using AgDrift, with a spray drift fraction of 0.027. For ULV applications, using the 450-foot buffer zone required on the label, an application efficiency of 0.727 was derived using AgDrift, with a spray drift fraction of 0.109, for orchards ( e.g., citrus, pome fruit, and stone fruit), and an application efficiency of 0.72 was derived using AgDrift, with a spray drift fraction of 0.117, for other crops. It should be noted that if the buffer zone for ULV is not used, spray drift fractions increase to 0.5 for both orchards and crops. Parameters used in the derivation of the application efficiency and sp ray drift for ULV applications are discussed further in Appendix P

.
3.2.4. Model Results

The aquatic EECs for the various scenarios a nd application practices for the sum of the o,p' and p,p' isomers of dicofol and for total dicofol ( e.g., including degradates) are listed in Table 12 and Table 13 . Example PRZM/EXAMS outputs ar e available in Appendix E.

Table 12. Aquatic EECs ( μ g/L) for Dicofol Uses in California, Total o,p ’ and p,p ’ Isomers.

Crop/Application Represented Application Rate (lbs a.i./acre) Date of First Application Scenario Peak EEC 21-day
average

EEC 60-day
average

EEC
Beans Aerial 1.5 May-01 CA row crop RLF 3.24 0.46 0.18 Beans Ground 1.5 May-01 CA row crop RLF 2.25 0.32 0.12 Beans ULV 1.5 May-01 CA row crop RLF 9.72 1.38 0.53 Citrus Aerial 3.0 January-15 CA citrus 6.44 0.97 0.42 Citrus Ground 3.0 January-15 CA citrus 4.46 0.69 0.31 Citrus ULV 3.0 January-15 CA citrus 17.97 2.58 1.03 Cotton Aerial 1.5 July-11 CA cotton irrig 3.44 0.65 0.29 Cotton Ground 1.5 July-11 CA cotton irrig 2.46 0.52 0.25 Cotton ULV 1.5 July-11 CA cotton irrig 9.87 1.52 0.60 Cucurbit Aerial 0.625 June-23 CA melons RLF 1.34 0.19 0.07 Cucurbit Ground 0.625 June-23 CA melons RLF 0.93 0.13 0.05 Cucurbit ULV 0.625 June-23 CA melons RLF 4.03 0.57 0.21 Grape Aerial 1.25 June-11 CA wine grape 2.69 0.39 0.15 Grape Ground 1.25 June-11 CA wine grape 1.86 0.27 0.10 Grape ULV 1.25 June-11 CA wine grape 8.06 1.15 0.44 Hops Aerial 1.165 May-31 OR hops 2.51 0.38 0.17 Hops Ground 1.165 May-31 OR hops 1.74 0.27 0.13 Hops ULV 1.165 May-31 OR hops 7.54 1.09 0.43 Mint Aerial 1.25 June-04 OR mint 2.69 0.39 0.16 Mint Ground 1.25 June-04 OR mint 1.86 0.27 0.11 Mint ULV 1.25 June-04 OR mint 8.05 1.15 0.44 Pepper Aerial 2.0 May-11 CA row crop RLF 1.61 0.23 0.09 Pepper Ground 2.0 May-11 CA row crop RLF 1.12 0.16 0.06 Pepper ULV 2.0 May-11 CA row crop RLF 4.83 0.69 0.26 Pome Fruit Aerial 3.0 June-05 CA fruit 6.44 0.91 0.34 Pome Fruit Ground 3.0 June-05 CA fruit 4.46 0.63 0.24

63Crop/Application Represented Application Rate (lbs a.i./acre) Date of First Application Scenario Peak EEC 21-day
average

EEC 60-day
average

EEC
Pome Fruit ULV 3.0 June-05 CA fruit 17.97 2.55 0.96 Stone Fruit Aerial 1.5 May-08 CA fruit 3.24 0.46 0.18 Stone Fruit Ground 1.5 May-08 CA fruit 2.24 0.32 0.12 Stone Fruit ULV 1.5 May-08 CA fruit 9.05 1.29 0.48 Strawberry Aerial 2.0 January-15 CA strawberry (nonplastic) RLF 6.09 1.71 0.92 Strawberry Ground 2.0 January-15 CA strawberry (nonplastic) RLF 5.97 1.57 0.87 Strawberry ULV 2.0 January-15 CA strawberry (nonplastic) RLF 13.10 2.67 1.22 Tomato Aerial 0.75 June-07 CA tomato 1.61 0.23 0.09 Tomato Ground 0.75 June-07 CA tomato 1.12 0.16 0.06 Tomato ULV 0.75 June-07 CA tomato 4.83 0.69 0.26 Walnut/Pecan Aerial 2.0 June -08 CA almond 4.38 0.67 0.29 Walnut/Pecan Ground 2.0 June -08 CA almond 3.07 0.48 0.22 Walnut/Pecan ULV 2.0 June- 08 CA almond 12.97 1.87 0.73 Bermuda grass Ground 0.4 January-15 CA turf RLF 0.60 0.10 0.04 Ornamentals Ground 0.5 January-15 CA nursery 1.77 0.39 0.18 Turf/Sod Farm Ground 0.5 January-15 CA turf RLF 0.75 0.13 0.05 Outside Buildings 0.5 January-15 CA impervious RLF & CA turf RLF 0.15 0.025 0.01

Table 13. Aquatic EECs ( μ g/L) for Dicofol, Parent and De gradate Uses in California.

Crop/Application Represented Application Rate (lbs a.i./acre) Date of First Application Scenario Peak EEC 21-day
average

EEC 60-day
average

EEC
Beans Aerial 1.5 May-01 CA row crop RLF 20.55 18.42 17.76 Beans Ground 1.5 May-01 CA row crop RLF 18.09 16.58 16.11 Beans ULV 1.5 May-01 CA row crop RLF 36.51 30.74 28.77 Citrus Aerial 3.0 January-15 CA citrus 21.64 17.89 16.61 Citrus Ground 3.0 January-15 CA citrus 16.49 13.93 13.13 Citrus ULV 3.0 January-15 CA citrus 55.15 44.58 40.99 Cotton Aerial 1.5 July-11 CA cotton irrig 22.86 21.17 20.52 Cotton Ground 1.5 July-11 CA cotton irrig 20.46 19.39 18.93 Cotton ULV 1.5 July-11 CA cotton irrig 38.84 33.25 31.31 Cucurbit Aerial 0.625 June-23 CA melons RLF 7.81 7.01 6.74 Cucurbit Ground 0.625 June-23 CA melons RLF 6.78 6.23 6.01 Cucurbit ULV 0.625 June-23 CA melons RLF 14.82 12.44 11.63 Grape Aerial 1.25 June-11 CA wine grape 15.39 13.81 13.26 Grape Ground 1.25 June-11 CA wine grape 13.33 12.22 11.84 Grape ULV 1.25 June-11 CA wine grape 29.15 24.37 22.74 Hops Aerial 1.165 May-31 OR hops 22.70 21.27 20.47 Hops Ground 1.165 May-31 OR hops 21.03 20.11 19.45 Hops ULV 1.165 May-31 OR hops 33.88 29.41 27.99 Mint Aerial 1.25 June-04 OR mint 18.81 17.62 16.81 Mint Ground 1.25 June-04 OR mint 17.12 16.05 15.52 Mint ULV 1.25 June-04 OR mint 32.57 27.83 26.26 Pepper Aerial 2.0 May-11 CA row crop RLF 10.29 9.23 8.90 Pepper Ground 2.0 May-11 CA row crop RLF 9.05 8.32 8.09

64Crop/Application Represented Application Rate (lbs a.i./acre) Date of First Application Scenario Peak EEC 21-day
average

EEC 60-day
average

EEC Pepper ULV 2.0 May-11 CA row crop RLF 18.21 15.34 14.37 Pome Fruit Aerial 3.0 June-05 CA fruit 24.32 20.57 19.26 Pome Fruit Ground 3.0 June-05 CA fruit 18.69 16.08 15.18 Pome Fruit ULV 3.0 June-05 CA fruit 57.34 46.74 43.13 Stone Fruit Aerial 1.5 May-08 CA fruit 12.06 10.17 9.50 Stone Fruit Ground 1.5 May-08 CA fruit 9.20 7.91 7.44 Stone Fruit ULV 1.5 May-08 CA fruit 28.73 23.40 21.57 Strawberry Aerial 2.0 January-15 CA strawberry (nonplastic) RLF 42.51 39.77 39.11 Strawberry Ground 2.0 January-15 CA strawberry (nonplastic) RLF 41.13 37.81 37.41 Strawberry ULV 2.0 January-15 CA strawberry (nonplastic) RLF 59.64 52.07 50.05 Tomato Aerial 0.75 June-07 CA tomato 7.72 6.77 6.44 Tomato Ground 0.75 June-07 CA tomato 6.38 5.72 5.49 Tomato ULV 0.75 June-07 CA tomato 16.54 13.70 12.73 Walnut/Pecan Aerial 2.0 June- 08 CA almond 25.2 8 22.82 21.99 Walnut/Pecan Ground 2.0 June- 08 CA almond 21.8 8 20.20 19.64 Walnut/Pecan ULV 2.0 June-08 CA almond 47.7 5 40.25 37.70 Bermuda grass Ground 0.4 January-15 CA turf RLF 2.66 2.31 2.21 Ornamentals Ground 0.5 January-15 CA nursery 7.16 6.48 6.29 Turf/Sod Farm Ground 0.5 January-15 CA turf RLF 3.31 2.87 2.74 Outside Buildings 0.5 January-15 CA impervious RLF & CA turf RLF 0.38 0.31 0.29

3.2.5. Available Monitoring Data

A critical step in the process of characteriz ing EECs is comparing the modeled estimates with available surface water m onitoring data. Monitoring data for dicofol from the USGS NAWQA program ( http://water.usgs.gov/nawqa ) were not available. Surface water and sediment monitoring data from the California Department of Pesticide Regulation (CDPR) were available and are c onsidered in this assessment. No air monitoring data were located.

Dicofol

A study was conducted in 1993 (Domagalski 1996) that assessed the levels of dicofol in the San Joaquin River and its tributaries during the irri gation season. Water samples were collected at 22 sites with in the perennial reach of the San Joaquin River in the San Joaquin Valley. All sampling locations were selected downstream of the confluence of the San Joaquin River and the Salt Slough. Al l sites were sampled during two synoptic surveys that occurred during March and August 1993. A subset of these sites was sampled more frequently (twice-monthly or monthly) for the period of March through September 1993. The sampling sites with th e greatest frequency were the Central California Irrigation District Canal, Orestim ba Creek, the Spanish Grant Drain, and the Salt Slough. From the study, it appears that 79 samples were collected from March to September 1993. All samples collected between March and June of 1993 were below the

65level of detection (0.05 μg/L). From June to September, 33 samples had levels of dicofol above the detection limit, with the highest concentration of 2.5 μg/L from a sample collected at the Orestimba Creek site.

NAWQA monitoring data were not available for dicofol from California surface waters (USGS 2008).

CDPR maintains a database of monitoring data of pesticides in CA surface waters. The sampled water bodies include rivers, creeks, urban streams, agricu ltural drains, the San Francisco Bay delta region a nd storm water runoff from ur ban areas. The database contains data from 51 different studi es by federal (incl uding the USGS NAWQA program), state and local agencies as well as groups from private industry and environmental interests. Data are ava ilable from 1990-2006 for 46 counties for several pesticides and their degradates. Data for di cofol are included in this database (CDPR 2008).

From 1990-2006, 618 samples from surface waters were analyzed for dicofol in the CDPR database. Of these, dicofol was detect ed in 11 (1.8%) of the samples, with a maximum concentration of 0.27 μg/L. These sa mples included 131 different sites in 16 counties; including counties where CRLF core areas and critical habitat are located. Dicofol was not reported in the sediment sample s that were collected over this timeframe. It should be noted that these results are not from ta rgeted monitoring studies.

The Pesticides in Ground Water Data Base (U.S. EPA 1992) shows no detections of dicofol in limited sampling in several Stat es, including California, (1634 wells sampled between 1979 and 1991).

Dicofol Degradates

NAWQA monitoring data were availabl e for one degradate of dicofol, p,p’ -DCBP. Twenty samples of p,p' -DCBP were collected from 2003 to 2005, with a maximum estimated concentration of 0.69 μg/L (detec tion limit unknown). It should be noted that the original source of the p,p’ -DCBP detections (e.g., where the active ingredient came from) is unknown, as p,p' -DCBP is also a degradate of ch lorobenzilate, chloropropylate, and DDT.

The CDPR database did not contain monitoring data of dicofol degradates in surface water or sediment.

3.3. Aquatic Bioaccumulation Assessment

Available data on the octanol-w ater partition coefficient K ow = 1.15 x 10 6 , (MRID 00141580) and bioconcentration fact ors (BCFs) for dicofol indi cate that this pesticide may accumulate in aquatic food webs. KABAM v.1.0 was used to estimate concentrations of dicofol in tissues of a quatic organisms resulting from bioaccumulation. Available empirical and modeling estimates of bioaccumulation of dicofol in aquatic organisms are described below.

663.3.1. Estimated BCF values

In order to estimate BCF values for aquatic organisms accumulating dicofol, KABAM was run, using a K ow of 1.15 x 10 6 (log(K ow ) = 6.06) to represent the partitioning of dicofol to aquatic organisms. It was assume d that the concentratio n of dissolved oxygen in water was 10 mg/L (near saturation) and the water temperature was 20 o C. The body characteristics of organisms in the m odel trophic levels are depicted in Table 14 . The resulting BCF values for these tr ophic levels are depicted in Table 15 . Output files from KABAM are provided in Appendix G

.

Table 14. Characteristics of model aquatic organisms us ed to derive BCF values.

Trophic Level Wet Weight (kg) % lipids % Non-lipid organic matter % Water phytoplankton N/A 2.0% 8.0% 90.0% zooplankton 1.0E-07 3.0% 12.0% 85.0% benthic invertebrates 1.0E-04 3.0% 21.0% 76.0% filter feeders 1.0E-03 2.0% 13.0% 85.0% small fish 1.0E-02 4.0% 23.0% 73.0% medium fish 1.0E-01 4.0% 23.0% 73.0% large fish 1.0E+00 4.0% 23.0% 73.0%

Table 15. Estimated BCF values for pa rent dicofol in aquatic organisms.

Trophic Level Total BCF (μg/kg-ww)/(μg/L) Phytoplankton 55,112 Zooplankton 39,268 Benthic Invertebrates 42,884 Filter Feeders 28,188 Small Fish 55,170 Medium Fish 55,170 Large Fish 55,170

3.3.2. Empirical BCF data

In a 28-day laboratory BCF st udy with bluegill sunfish ( Lepomis macrochirus ) exposed
to p,p'- dicofol, a BCF of 10,000 was observed in whole fish. In this study, steady state was not reached. The estimated steady-state BCF for dicofol was 25,000, which is within a factor of 2.2 of the estimated BCF for fish ( Table 15 ). In this study, parent dicofol represented >94% of the radioactivity meas ured after the 28-day exposure, suggesting that metabolism of dicofol was minimal. FW-1 52 and OH-DCBH were detected in tissue samples, each comprising as much as 4.7% of the overall radioactivity measured at the time (MRID 265330).

In an early life stage test with the aquatic invertebrate, Hyalella azteca and the fathead minnow ( Pimephales promelas ), mean 28-day BCF values of 10,000 (±3000) and 3,700

67(±800), respectively, were obser ved (GS0021-017). As the dur ation of this study was insufficient to allow the test organisms to r each steady-state, it is expected that if the duration had been extended, observed BCF values would have increased.

In a full life cycle test with the fathead minnow, the highest observed BCF value was 43,000, which was observed in F 0 females after 296 days of exposure to dicofol (MRID 42628901). This value is within a factor of 1.3 of estimated BCF value for fish ( i.e
., 55,000).

3.3.3. Bioaccumulation modeling

KABAM was run in default mode (see user’s guide for full description), with a Log Kow = 6.06, a K OC = 7060 L/kg-oc (see Table 10 ) and surface water and pore water EECs of 0.26 and 0.066 μ g/L, respectively. These PRZM/EXAMS-generated EECs are based on the average of yearly average concentratio ns of dicofol parent from ULV dicofol applications to strawberries. These EECs were selected because they represent the highest annual EECs predicted for any use of dicofol and result in the highest predicted accumulation of dicofol in tissues of aquatic organisms. The average water temperature (13 o C) for this scenario was used to simulate the water temperature of the abiotic compartment of KABAM. It was assumed that metabolism of dicofol by aquatic organisms did not occur. This assumption is supported by the available BCF study with p,p' -dicofol, where parent dicofol represented >94% of the radioac tivity measured after the 28-day exposure and metabolism wa s minimal (MRID 265330). The resulting concentrations of dicofol in tissues of aquatic organisms are provided in Table 16 . Output files from KABAM are provided in Appendix G . These values are used to derive RQs based on dose-based and dietary-based exposur es of aquatic-phase CRLF to dicofol through consumption of contaminated aquatic prey (See section 5.1).

Table 16. Concentrations of dicofo l parent in tissues of aquatic or ganisms (estimated using KABAM).
Trophic level Total con centration (μg/kg-ww)
Phytoplankton 10,559 Zooplankton 11,838 Benthic Invertebrates 15,191 Filter Feeders 10,301 Small Fish 39,027 Medium Fish 82,949 Large Fish 290,605

KABAM’s predictions of bioaccumulation in a quatic systems are most sensitive to the K ow value of the assessed pesticide, with accumulation increasing as the K ow increases. No empirical data were available to define the K ow values of dicofol’s residues of concern, so EPISuite v.4.0 was used to estimate K ow values for the 4 degradates of concern ( Table 17 ). Review of the estimated K ow values of dicofol’s residues of concern indicates that dicofol transforms to residues that have lower K ow values, and thus lower

68accumulation potential in aquatic organisms. KABAM was used to estimate the bioaccumulation of dicofol’s total residue s of concern, by considering PRZM/EXAMS generated aquatic EECs for to tal residues and the Log K ow values of dicofol’s degradates of concern. KABAM was run again in de fault mode (see user’s guide for full description), with Log Kow = 3.96, 4.0, 4.44, 4.89, and 6.06 (measured), to represent the partitioning of OH-DCBP, DCBH , DCBP, FW-152 and dicofol, respectively in aquatic organisms. A K oc = 7060 L/kg-oc (see Table 10 ) and surface water and pore water EECs of 41 and 17 μ g/L, respectively. These EECs are based on the average of yearly average concentrations of dicofol parent derive d from ULV applications of dicofol to strawberries, as modeled using PRZM/EXAMS. As discussed earlier, these EECs were selected because they represent the highest annual EECs predicted for any use of dicofol and result in the highest predicted accumu lation of dicofol in tissues of aquatic organisms. The resulting concentrations of dicofol in tissues of aquatic organisms are provided in Table 18 . Output files from KABAM are provided in Appendix G . In reality, dicofol and its resi dues of concern would be s ubject to uptake by aquatic organisms. Therefore, the overall bioaccumula tion of dicofol’s total residues would be a mixture of dicofol and its 4 residues and woul d therefore fall betw een the tissue residue concentrations estimated for OH-DCBP and dicofol that are provided in Table 18

.

Table 17. Estimated Log Kow values of dicofol's residues of concern.
Chemical Log K ow *

Dicofol 5.81 DCBP 4.44 FW-152 4.89 DCBH 4.00 OH-DCBP 3.96 *Estimated using EPISuite v.4.0.

Table 18. Concentrations of dicofo l total residues of concern in tissu es of aquatic organisms (μg/kgww; estimated using KABAM). Concentrations were estimated using Log Kow values representative of the different dicofol residues of concern.

Trophic level Log Kow = 3.96 (OH-DCBP) Log Kow = 4.00 (DCBH) Log Kow = 4.44 (DCBP) Log Kow = 4.89 (FW-152) Log Kow = 6.06 (dicofol) Phytoplankton 1.7E+04 1.9E+04 5.2E+04 1.5E+05 1.7E+06 Zooplankton 1.3E+04 1.4E+04 3.9E+04 1.1E+05 1.9E+06 Benthic Invertebrates 1.4E+04 1.5E+04 4.2E+04 1.2E+05 2.4E+06 Filter Feeders 9.0E+03 9.9E+03 2.7E+04 7.9E+04 1.6E+06 Small Fish 1.8E+04 2.0E+04 5.5E+04 1.7E+05 6.2E+06 Medium Fish 1.8E+04 2.0E+04 5.8E+04 1.9E+05 1.3E+07 Large Fish 1.9E+04 2.1E+04 6.4E+04 2.4E+05 4.6E+07

693.4. Terrestrial Animal Exposure Assessment

3.4.1. Modeling Approach

T-REX (Version 1.4.1) is used to calculate di etary and dose-based EECs of dicofol for the CRLF and its potential prey ( e.g. small mammals and terrestrial insects) inhabiting terrestrial areas. EECs used to represent th e CRLF are also used to represent exposure values for frogs serving as potential prey of CRLF adults. T-REX simulates a 1-year time period.

Terrestrial EECs for dicofol were derived fo r the uses and corresponding application rates summarized in Table 19 . According to dicofol labels, only 1 application of dicofol is allowed per year on any one fi eld, so only 1 application per year was modeled for each use. One foliar dissipation half-life value specif ic to dicofol (6 days based on application to alfalfa in CA) is available in Willis a nd McDowell (1987). Because a single half-life value is insufficient to derive a foliar dissip ation half-life specific to dicofol, the EFED default foliar dissipation half-life of 35 days is used based on the work of Willis and McDowell (1987). This value falls within the range of observe d dissipation half-lives for dicofol measured in 3 studi es (9-61 days, see section 3.4.1 below). The maximum application rate for each use is modele d in T-REX and upper bound EECs are used for RQ calculations. An example output from T-REX is available in Appendix H

.

Table 19. Input parameters to T-REX used to generate dicofol EECs for terrestrial animals.

Use Application Rate (lbs a.i./A) Citrus, 1 Pome Fruits 2 3 Strawberries, Walnuts (English/black), Pecans 2 Beans, cotton, Stone Fruits 3 1.5 Grapes, mint 4 1.25 Hops 1.165 Peppers, Tomatoes 0.75
Cucurbits 5 0.625 Ornamentals, 6 Turf grasses, Sod farms, Outside building surfaces 0.5
Bermuda grass 0.4

1 grapefruit, lemons, oranges, tangelos, and tangerines
2 apples and pears
3 apricots, cherries, nectarines, peaches, plums, and prunes
4 mint, peppermint and spearmint
5 cantaloupes, cucumbers, melons, pumpkins, watermelons, and winter and summer squash
6 nurseries and flowers

For modeling purposes, exposures of the CRLF, as well as other fr og species serving as prey to the CRLF, to dicofol through contam inated food are estimated using the EECs for

70the small bird (20 g) which consumes sma ll insects. Dietary-based and dose-based exposures of potential prey ar e assessed using the small mammal (15 g) which consumes short grass. Upper-bound Kenega nomogram values reported by T-REX for these two organism types are used for derivation of EECs for the CRLF and its potential prey ( Table 20 ).

As indicated above, T-REX is also used to calculate EECs for terres trial insects exposed to dicofol. Dietary-based EECs calculated by T-REX for small and large insects (units of μg a.i./g) are used to bound an estimate of expo sure to terrestr ial insects. Available acute contact toxicity data for bees exposed to dicofo l (in units of μg a.i./b ee), are converted to μg a.i./g (of bee) by multiplying by 1 bee/0.128 g. Dietary-based EECs for terrestrial insects are later compared to the adjusted acute contact toxicity data for bees in order to derive RQs. Dietary-based EECs for small and large insects repor ted by T-REX as well as the resulting adjusted EECs are available in

71Table 21

.

Table 20. Upper-bou enega Nomogram E and Do of the CRLF e Applications of dicofol for Current Uses in Californ nd K ECs for Dietary- se-based Exposures and its Prey to Singl ia.

EECs for CRLF EECs for Prey (smal mals) l mam Use Dieta ry-based Dose-ba EC sed E Dietary-based Do se-based EEC (m EEC (ppm) (mg/kg-b w) EEC (ppm) g/kg-bw)
Citrus Fruits 2

, 1 Pome 405 4 61 720 686 Strawb s erries, Walnut (Engli cans sh/black), Pe 270 3 08 480 458 Beans , cotton, Stone Fruits 3 203 231 360 343 Grape s, mint 4 168 1 92 300 286 Hops 157 1 79 281 267 Peppers , Tomatoes 101 115 180 172 bits 5 84.4 96.1 Cucur 150 143 Ornam entals, Turf grasses, 6 Sod fa rms, Outside building surfac es 67.5 76.9 120 11 4 B ermuda g rass 54.0 61.5 96.0 91.5 1 grapefruit, lemons, oranges, tangelos, and tangerines 2 apples and pears 3 apricot ches, plums, and prunes s, cherries, nectarines, pea 4 mint, peppermint and spearmint 5 cantaloupes, cucumbers, melons, pumpkins, watermelons, and winter and summer squash 6 nurseries and flowers

72T able 21. Dicofol EECs (ppm) for Indirect Effects to the Terrestrial-Phase CRLF via Effects to Terrestrial Invertebrate Prey Items.

Use Small Insect EEC Large Insect EEC Citrus, 1 Pome Fruits 2 405 45.0 Strawberries, Walnuts (English/black), Pecans 270 30.0 Beans, cotton, Stone Fruits 3 203 22.5 Grapes, mint 4 169 18.8 Hops 157 17.5 Peppers, Tomatoes 101 11.3 Cucurbits 5 84.4 9.38 Ornamentals, 6 Turf grasses, Sod farms, Outside building surfaces 67.5 7.50 Bermuda grass 54.0 6.00
1 grapefruit, lemons, oranges, tangelos, and tangerines
2 apples and pears
3 apricots, cherries, nectarines, peaches, plums, and prunes
4 mint, peppermint and spearmi nt 5 cantaloupes, cucumbers, melons, pumpkins, watermelons, and winter and summer squash
6 nurseries and flowers

3.4.1. Field Studies

Comprehensive ecological monitoring studies of dicofol residues were conducted for three years in California cotton fields (1990-92; MRIDs 41785102, 41857301, and 42285503), Florida citrus groves (1989-91; MRIDs 41785103, 41845605, 42091501, and 42437301), and New York apples orch ards (1989-91; MRIDs 41845604, 42285501, and 42721301). Areas and crops selected had a prev ious history of heavy dicofol use and a high likelihood for exposure to non-target orga nisms. Application rates typified those most commonly used by the growers and not necessarily the maximum label rates.

Observed residue concentrations were va riable and declined exponentially after application. The highest mean concentr ations were typically found immediately following ap

e Florida c plication on the treated area, us ually on the treated crop foliage, except for itrus site. Residues of p,p' -dicofol on the non-crop area were typically 1 to 2 rders of magnitude below those found in th e crop areas. In the crop areas, the highest ean concentration of p,p' -dicofol measured were 97 ppm for foliage (New York), 78 ppm on grass (Florida) and 0.56 ppm for soil (New York). The highest mean concentration of p,p' -dicofol measured in the abiotic matrices for the non-crop area were 9.7 ppm for grass (Florida), 5.9 ppm on foliage (Florida), and 0.1 ppm for soil (California and Florida). Foliage residues in the crop ar eas declined from 3-year means of 92, 97 and 74 ppm immediately after application, to 0.05, 16 and 24 ppm 90 days later for cotton, orchards, and citrus, respectiv ely. Foliage residues in non-c rop areas declined from 3- year means of 0.6, 5.2, and 5.9 ppm immediately after appl ication to 0.09, 0.9, and 0.55 ppm after 90 days for cotton, orchards, and ci trus, respectively. Mean grass residues declined from 0.47, 5.1, and 9.7 ppm immedi ately after application, to 0.04, 0.08, and 0.54 ppm 90 days later for cotton, or chards, and citrus, respectively. th

o

m

73Residues of p,p' -dicofol were detected in the foliage of crops and dissipated with a halflife ranging of 9, 41, and 61 days for cotton, orchard, and citrus foliage respectively. Grass residues declined from 3-year means of 48 and 78 ppm immediately after application, to 0.15 and 2.3 ppm 90 days later for orchards and citrus, respectively. Dissipation half-lives of p,p' -dicofol on orchard and citrus grass were 12 and 21 days, respectively. The observed foliar dissipation ha lf-lives for dicofol are comparable to the 35-day default value used to re present the foliar dissipation half-life of dicofol in the TREX model.

3.5. Accumulation of Dicofol Residues on Soil

Because dicofol and its degradates are modera tely persistent in so il (aerobic soil halflives greater than 104 days) and do not have a tendency to leach from soil, a screening analysis was conducted to characte rize the levels of dicofol in the soil of a treated site after 30 years of applications.

Ground application to pome fru its was selected for the sc reening analysis, as it was expected to result in highest soil concentrations of dicofol compared to any other use (b o str levels of EECs in the aquatic exposure assessment. PRZM/EXAMS runs were conducted and total soil concentrations were estimated for the upper 10 cm soil horizon. As with the aquatic exposure assessment, both the o,p' - and p,p' isomers of dicofol were run separately and the results combined in a postprocessor. The 1-in-10-year peak concentrations in the soil for total dicofol were 11,952 and 7,770 mg/m 3 for pome fruits and strawberries, respectively. The 1-in-10- year peak concentrations in the pore water for total dicofol were 176 and 115 mg/m 3 for pome fruits and stra wberries, respectively. Annual average peak dicofol soil concentrations increased for the first fifteen years of the simulation, then reached a plateau at an averag e annual peak concentration in the soil at 10,170 and 6,600 mg/m 3 for pome fruits and strawberries, respectively, and in the pore water at 150 and 98 mg/m 3 for pome fruits and strawberries, respectively ( Figure 9 and Figure 10 ). ased on the highest application rate and app lication efficiency). Aerial application t awberries was selected for the screening analysis, as this scenario produced the highest

74Peak Dicofol Concentrat

14000 ions in Soil Over Time

8000

6000 8000 10000 12000Soil Conc (mg/m3) 10000 12000

0 2000 4000 6000

0 2000 4000

Figure 9. Concentration of total residues of dicofol in soil treated wi th dicofol for 30 years. X axis

represents time in days. Soil modeled in PRZM using CA strawberries an d CA fruit scenarios. Pome Fruit, Ground App Strawberry, Aerial App

Peak Dicofol Concentrations in Pore Water Over Time

0

Figure 10. Concentration of total res idues of dicofol in pore water of soil treated with dicofol for 30 years. X axis represents time in days. Soil mode led in PRZM using CA strawberries and CA fruit scenarios. 0 0 0 0 0 0 0 0 0

0 2000 4000 6000 8000 10000 12000 2 4 6 8 10 12 14 16 18 20Pore Water Conc (mg/m3) 0

Pome Fruit, Ground App Strawberry, Aerial App

753.6. Terrestrial Bioaccumul ation Assessment

ggs.

ppm for reptiles/amphi bians (Florida), 0.9 ppm for irds (Florida), and 0.26 ppm for fish (Florida ). Dicofol was found at a concentration of

compared with the nesting ccess for these species. Yearly geometric mean p,p' -dicofol residues ranged from can robin eggs in New lowest in ns for p,p' -FW152 residues

eans exceeded 0.03 ppm only in eggs of the eastern screech ppm). Yearly geometric means for p,p'

- residues ranged from 0.004 ppm (starlin g in California) to 0.1651 ppm (eastern The estimated octanol-air partition coefficient (K OA ) of 10 10 (EPIsuite v.4.0) suggests that bioaccumulation of dicofol in air breathing organisms is possible (Kelly et al . 2007). At this time, modeling tools are unavailable to quantify the bioaccumulation of dicofol in terrestrial organisms. However, relevant monitoring studies involving dicofol have been conducted.

Comprehensive ecological monitoring studies of dicofol residues were conducted for three years in California cotton fields (1990-92; MRIDs 41785102, 41857301, and 42285503), Florida citrus groves (1989-91; (MRIDs 41785103, 41845605, 42091501, and 42437301), and New York apples orchards (1989-91; (MRIDs 41845604, 42285501, and 42721301). Areas and crops selected had a previous history of heavy dicofol use and a high likelihood for exposure to non-target orga nisms. Application rates typified those most commonly used by the growers and not necessarily the maximum label rates. Dicofol residues were monitored in soil, plant foliage, fish, mammals, reptiles, amphibians, earthworms, birds, and bird e

In crop areas, the highest mean concentrations of p,p' -dicofol measured in the biotic matrices were 1.4 ppm for small mammals (Flo rida), 3.9 ppm for terrestrial invertebrates (California), and 3.8 ppm for re ptiles/amphibians (Florida). In non-crop areas, highest mean concentrations were 0.3 ppm for small mammals (New York), 0.76 ppm for terrestrial invertebrates (Flori da), 0.38 b 1-2 ppm in earthworms in New York.

Eggs were collected from thirteen avian species and were analyzed for residues and eggshell thickness (MRIDs 41764801, 41764802, 41845601, 41845602, 41845603, 42285501, 42285505, and 42721302). These data were

su 0 .0027 ppm (several species in California) to 0.46 ppm (Ameri Y ork). Yearly means were highest in New York (0.01-0.46 ppm), and C alifornia (<LOD to 0.02 ppm). Yearly geometric mea

r anged from 0.002 ppm (mourning dove in Califor nia) to 0.218 ppm ( eastern screech owl in Florida). Three year m

o wls in Florida and robins in New York (0.0947

CBP D screech owl in Florida). Three year means exceeded 0.03 ppm only in eggs of eastern screech owls in Florida and New York (0.1093 and 0.0648 ppm, respectively), New York robins (0.0374 ppm), and Florida mo ckingbirds (0.0431 ppm). Except for p,p' -FW152 concentrations in the eastern screech owl in Florida, geom etric mean metabolite residue concentrations were generally lower than for p,p' -dicofol. None of the yearly geometric means for dicofol, p,p' -FW152, or p,p' -DCBP exceeded 0.5 ppm.

76

### 4.0 Effects Assessment

This assessment evaluates the potential for dico fol to directly or indirectly affect the CRLF or modify its designated cr itical habitat. As discu ssed in Section 2.7, assessment endpoints for the CRLF effects determination in clude direct toxic effects on the survival, reproduction, and growth of CRLF, as well as indirect effects, such as reduction of the prey base or effects to its habitat. In ad dition, potential effects to critical habitat is assessed by evaluating effects to the PCEs, which are compon en ts of the critical habitat

reas that provide essential life cycle needs of the CRLF. Direct effects to the aquatics described in the Agency’s Overview Document (U.S. EPA 2004), the most sensitive

on data generate d from guideline studies bmitted by the registrant, and from open lite rature studies that meet the criteria for

ironmental chemical con centration/dose or a pplication rate is reported; and

n e registrant-submitted data are considered. The degree to which open literature data are uantitatively or qualitatively characterized fo r the effects determination is dependent on hether the information is releva nt to the assessment endpoints ( i.e. , maintenance of a phase of the CRLF are based on toxicity inform ation for freshwater fish, while terrestrialphase effects are based on avian toxicity data , given that birds are generally used as a surrogate for terrestrial-phase amphibians. Because the frog’s prey items and habitat requirements are dependent on the availability of freshwater fish and invertebrates, small mammals, terrestrial invertebrate s, and aquatic and terrestrial plants, toxicity information for these taxa are also discussed. Acute (s hort-term) and chronic (long-term) toxicity information is characterized based on registrant-submitted studies and a comprehensive review of the open literature on dicofol.

A endpoint for each taxon is used for risk estimat ion. For this assessment, evaluated taxa include aquatic-phase amphibians, freshwater fish, freshwater i nvertebrates, aquatic plants, birds (surrogate for terrestrial- phase amphibians), mammals, terrestrial invertebrates, and te rrestrial plants.

Toxicity endpoints are estab lished based

su inclusion into the ECOTOX database maintained by EPA/Office of Research and Development (ORD) (U.S. EPA 2004). In order to be included in the ECOTOX database, papers must meet the following minimum criteria:

o the toxic effects are related to single chemical exposure; 6

o the toxic effects are on an aquatic or terrestrial plant or animal species;

o there is a biological effect on live, whole organisms;

o a concurrent env

o there is an explicit duration of exposure.

Data that pass the ECOTOX screen are evaluated along with the registrant-submitted data, and may be incorporated qualitatively or quantitatively into this endangered species assessment. In general, effects data in the ope n literature that are more conservative tha th
q

w

The studies that have information on mixtures are listed in the bibliography as rejected due to the presence of mixtures. These studies are evaluated by EFED when applicable to the assessment; however, the data is not used quantitatively in the assessment. 6

77CRLF survival, reproduction, and growth ) id entified in Section 2.8. For example, ehavi fications are be qua ly e ecause quantitative relationships between modifica d species survival, reproduction, and/or growth are not availabl e. Although the effect s determination relies

re r r portant to note that the

ts s t sidered action dicofol.

fol ECOTOX database on 10/31/08 were considered Ci all open ture not considered as part of this they were either reject ed by the ECOTOX screen or accepted by t not used ( e.g. , the endpoint is less sensitive) are included in Appendix I

. include r reje ha those that were not eval endan ed s readsheet of th e available accepted ECOTO ll suite of lethal and sublethal endpoints is presented in

. ludes a s a d

nt-submitted and open lite rature toxicity info rmation, other sources including indi e conducted to further refi ne the characterization of potential ecological ciated with expos ure to dicofol. A summary of the available incident formation for dicofol is provided below.

in study reports, sublethal effects obs acute toxicity studies a this effects characterization. ublethal effects raise concern abo f dicofo l; however, it is not

to quantitatively link these effects to the selected assessment endpoints for the

F ( i.e. , survival, growth, and re dividuals and maintenance of ore, pot ffects on specific taxa are valuated qualitatively. De finitive endpoints, such as LC 50 s are used for quantifying
ent.

.1. endpoints such as b or modi likely to
t ions and re

e litative uction in valuated, b

on endpoints that a reproduction, it is im elevant to the asse ssm nt endpoi full suite of su nts of su bletha l endpoints potentially vival, growth, or

available in the effec endpoints) are con literature (regardle to defi ne the s of their sig area for nificance o the assessment

Toxicity data for dico for this assessment. assessment because ECOTOX bu available in the tations of l itera

Appendix I also ECOTOX screen and assessment. A detail data, including the fu s a rati onale fo ction of those
uate d as part o studies t f this t did not pass the gered species risk X open literature Appendix J p
Appendix K inc

In addition to registra of informatio ummary of the hum n health effect s data for icofol.

n, the probability of an System (EIIS), ar effects asso use of the acute prob it dose response relationship to establish vidual effect and re views of the Ecological Incident Information

in

It should be noted that where data were provided erved during re desc ribed in These s possible ut the effects o

listed CRL l habitat PCEs). Theref pr in oduction of critica ential sublethal e

e RQs in this assessm

4 Toxicity of dicofol to aquatic organisms

Table 22 summarizes the most sensitive aquatic toxicity endpoints for the CRLF, based on an evaluation of the available studies as prev iously discussed. Toxi city to aquatic fish and invertebrates is categorized using the system shown in Table 23 (U.S. EPA 2004).

78Table 22. Freshwater toxici ty profile for dicofol.
A ssessment Endpoint Species Toxicity Value Used in Risk Source (MRID) Comment

Assessment Acute Direct Toxicity to A Oncorhynchus clarkii LC 50 = 53.0 40098001 Slope not available

quatic-Phase CRLF (cutthroat trout) μg/L Chronic Direct Toxicity to Aquatic-Phase CRLF Oncorhynchus mykiss (rainbow trout) NOAEC ./ 42063001 LOAEC = 7.9 μg a.i./L based on dec = 4.4 L μg a.i reased length Indirect Toxicity to A A F ( Daphnia magna ) 50 = g/L 40042057 Slope not available quatic-Phase CRLF via (waterflea cute Toxicity to reshwater Invertebrates i.e. prey items) EC 140
μ

I A C F ( azteca (amphipod) OAE a.i./L S00 6 28-da 33 μg d on decreased surviv ndirect Toxicit

quatic-Phase CRLF via y to Hyalella

hronic Toxicity to reshwater Invertebrates i.e. prey items) N C = 19 G
μg 21- 01 y LOAEC = a.i./L, base

al

I A T A s acutus ) C 50 > 10,000 sh i 1 Effec and observ ndirect Toxicity to Scenedesmu quatic-Phase CRLF via (green alga oxicity to Non-vascular quatic Plants E 5,000, Kri

< μg/L mar naku 977 ts to biomass growth ed

I Aquatic-Phase CRLF via Toxicity to Vascular A No data are available to quantify an e ndpoint to represent effects of dicofol exposures to vascular plants. ndirect Toxicity to

quatic Plants

Table 23. Categories of acute toxicity for aquatic organisms.
LC 50 (mg/L) Toxicity Category < 0.1 Very highly toxic

> 0.1 - 1 Highly toxic

> 1 - 10 Moderately toxic

> 10 - 100 Slightly toxic > 100 Practically nontoxic

4.1.1. Toxicity of re ater Fish

l t ity data not availa for aq se a , ar d as a su to estim irect chro o ater toxicity data are also used to asses dir ts RL Effects to hwat er fish sulting sure affect the CRL F via reduction in available f ood. As discussed in Section 2.5.3, over 50% of the prey mass of the CRLF ma y consist of vertebrates such as mice,

ogs, and fish (Hayes and Tennant 1985). Dic ofol to F shw

Given that dicofo oxic are ble uatic-pha mphibians freshwater fish data the CRLF. Freshw e use fish rrogate ate d acute and s poten tial in nic risks t ect effec of dicofol to the C could indirectly F. fres re from expo to dicofol

fr

Available acute toxicity data for freshwater fish exposed to dicofol include 96-h LC 50 values ranging 53-603 μg /L ( Table 24 ). Therefore, dicofol is classified ( Table 23 ) as

79very highly to highly toxic to freshwater fish on an acute exposure basis. The most sensitive freshwater species tested is cutthroat trout, with a 96-hour LC 50 value of 53 μg/L (MRID: 400980-01), is used for derivi ng risk quotients fo r the CRLF and fish serving as prey to the adult CRLF.

Table 24. Acute toxicity data (96-h LC 50 ) for freshwater fish exposed to dicofol.

Species (common name) LC 50 value (μg/L) 95% confidence

interval (μg/L) Slope Source (MRID)

Oncorhynchus clarkii (cutthroat trout) 53.0 41-68 NA 40098001 O. clarkia (cutthroat trout) 158 100-250 NA 40098001 O. clarkii (cutthroat trout) 53.1 41.3-68.2 15.6 GS0021002 Salvelinus namaycush (lake trout) 86.9 53.1-142.0 NA GS0021001 S. namaycush (lake trout) 87 53-142 4009 8001 O. mykiss (rainbow trout) 124.3 95.0-181.0 3.8 41695401 Ictalu 10.8 40098001 rus punctatus (channel catfish) 360 290-447 Mic NA 40098001 ropterus salmoides (largemouth bass) 395 NA Pim ephales promelas (fathead minnow) 509 492-533 12.2 GS0021018 Lepomis macrochirus (bluegill sunfish) 510 420-640 10.3 GS0021004 Lepomis macrochirus (bluegill sunfish) 520 421-642 NA 40098001 Pim ephales promelas (fathead minnow) 603 577-631 NA ECOTOX # 12859 NA = not available

Several chronic studies are av ailable where freshwater fish were exposed to dicofol ( Table 25 ). Av ailable chronic st udies for rainbow trout ( Oncorhynchus mykiss ) and fathead m below. From these studies, the

mos ed growth, is a 95-day NOAEC value

f 4.4 μg/L (MRID: 42063001). This value is used for deriving risk quotients for the innows ( Pimephales promelas ) are described t sensitive chronic endpoint, based on de creas

o CRLF and fish serving as pr ey to the adult CRLF.

Table 25. Chronic toxicity data for freshwater fish exposed to dicofol. Species (c ommon name) Duration of Study (days) NOAEC (μg/L) LOAEC (μg /L) Observed S ource Effects (MRID) Oncorhynchus mykiss (rainbow trout) 95 4.4 7.9 Decreased length 42063001

Oncorhynchus mykiss (rain 99 4.6 9.1 Decreased th 43383902 bow trout) leng Pim ephales promelas 296 4.52 8.82 Impacted 42628901 (fathead minnow) reproduction Pimephales promelas (fathead minnow) 28 19 39 Decreased survival and growth GS0021-016

In an early life stage test with rainbow tr out, growth (length) was significantly reduced (4.8% compared to controls) in fish (at 35-days post-hatch) exposed to concentrations of 7.9 (±1.0) μg a.i./L. The resulting NOAEC for this study was 4.4 μg a.i./L (MRIDs

8042063001). In an additional early life stage test conducted with rainbow trout resulted in reduced growth (length was decreased 4.8% comp ared to controls) of fish (36-day old) exposed to 9.1 μg a.i./L dicofol. The resulting NOAEC for this study was 4.6 μg a.i./L (MRID 43383902).

I n an early life stage test with fathead mi nnows, survival and growth were significantly

(±3.8) μg a.i./L (GS0021-016). In a full life cycle study (296 days) with the fathead minnow, mean ha ccess of g was significan sed ./L trea t ared ecrease). Also, signif effect s to rep duction were o erved in the ion exposed to 8.82 μg , including d sed number s/pair, decrea f spawns per mating pair and decreas ed number of reproductive days per mati e resulting NOAEC for this study was 4.52 μg a.i./L (MRID 42628901).

of Dicofol to Freshwater Invertebrates

icofol is classified highly toxic to freshwat er invertebrates, based on an acute toxicity

-016).

s

his risk assessment ( i.e ., to derive RQ values for the degradates), but r to compare the relative toxicitites of dicofol and its major environmental decreased in fish exposed to concentrations of 39 (±6.3) μg a.i./L for 28 days. The resulting NOAEC for this study was 19 tching su the F 1

eneration tly de crea at 8.82 μg a.i ment comp to controls (13% d icant ro bs F 0 generat a.i./L ecrea of egg sed number o ng pair. Th

4.1.2. Toxicity

D study with Daphnia magna (MRID 40042057), where an EC 50 of 140 μg/L was observed.

Chronic toxicity data are available for the amphipod, Hyalella azteca . The NOAEC for this study was 19 (±2.2) μg a.i./L, based on a decrease in survival (70% mortality, compared to 0% in controls ) in animals exposed to 33 (± 2.2) μg a.i./L for 28 days (GS0021

4.1.3. Toxicity of Dicofol to Aquatic Plants

Data are available from the scientific lite rature involving exposures of dicofol to the green alga, Scenedesmus acutus . Based on observed decreases in biomass and growth rates, the EC 50 is estimated to lie between 5,000 and 10,000 μg/L (Krishnakumari 1977).

No data are available involving exposures of aquatic vascular plants to dicofol.

4.2. Toxicity of Dicofol’s Degradates to Aquatic Organisms

4.2.1. Toxicity of Dicofol’s Degradates to Aquatic Animal

Empirical data are not available for exposur e of aquatic animals to dicofol’s major degradates (DCBP, FW-152, DCBH, OH-DCBP and CBA). In order to characterize the relative toxicity of dicofol and its majo r degradates, ECOSAR v. 1.0 (USEPA 2009) was run to estimate acute LC 50 and chronic toxicity values for fish and aquatic invertebrates. ECOSAR predicted acute and chronic values fo r the parent and degradates are not used

uantitatively in t q rathe

81degradates. ECOSAR estimates of acute and chronic toxicity for fish and daphnids indicate that DCBP, FW-152, DC BH and OH-DCBP are similar ( i.e ., estimated LC 50 and chronic values are within an order of magnit ude) to that of dicofol. ECOSAR estimates cofol, with estimated LC 50 and chronic

96-h LC 50 chronic value 48-h LC 50 chronic value indicate that CBA may be of lesser toxi city than di values for CBA being several orders of magnitude greater than dicofol (Table 26 ).

Table 26. Estimated acute and chroni c toxicity values (μg/L) for fish and daphnids exposed to dicofol and its degradates (as calculated by ECOSAR).

Chemical Fish Fish Daphnid Daphnid

D icofol 1 274 9 8 21 DCBP 2 1391 171 1124 192 FW-152 1027 50 79 1 40 DC 42 231 BH 1 3037 139 2 OH-DCBP 1472 1088 206 3 8 CBA 2 88987 488560 844098 58244

1 Benzyl alcohol clas
2 Neutral organic clas
3 Phenols class s

s

C 5 e o 53 ted v falls wi thin this range. The ECOSAR estimated chronic value of 9 μg /L also falls within the range of availabl e NOAE ofol erte CO m nitude availabl pirical EC 50 e μg/L).

nt s of aqu onm FW d O Because the estimated acute and ity of CBA is several orders of magnitude less than that of dicofol and the A is not c onsidered to date of concern ent that for l residues are of equal tox acute toxicity data used t toxicity of the uatic animals are selected based on the most sensitive values available for hron data av exp fr sed to so used sent the chronic toxicity of the total organisms.

of Dicofol’s Degr

ata are available from the sc ientific literature involving separate exposures of DCBP nd DCBH to the green alga, Chlorella vulgaris . At concentrations of 1000 μg/L, ecreases in chlorophyll a and biomass were not observed compared to controls. At 0,000 μg/L, decreases in chlorophyll a a nd biomass were observed (Subba-Rao and lexander 1980). Ninety-six hour L ECOSAR estima 0 values for fish alue of 274 μg/L xposed to dic fol range -603 μg/L. The

Cs 4.4-19 μg/L for ated acute value is (48-h EC 50 = 140 fish exposed to dic 2 orders of mag . For aquatic inv lower than the b rates, the E

e em SAR esti valu

In this risk assessme as: dicofol, DCBP, , the total residue -152, DCBH an concern for H-D CBP. atic envir ents are defined

chronic toxic other degradates, CB this assessm the parent. The be a degra . It is assumed in icity compared to

total residues of aquatic animals, tota o represent the dicofol to aq dicofol exposures. C invertebrates expo

ese ic toxicity ai lable for to repre osures of eshwater fish and dicofol are al residues to th

4.2.2. Toxicity adates to Aquatic Plants

D

a d 1 A

82No data are available involving exposures of aquatic vascular plants to dicofol’s major degradat

4.3. Toxicity of dicofol to terrestrial organisms

Tabl s the most sensitiv e terrestrial toxicity e ndpoints for the CRLF, based

on a of registrant submit s and the scien re. Acute toxic nimals is catego sing the classificat ion system shown in Table 28 (U.S. EPA 2004). Toxicity categories fo r terrestrial plants have not been defined.

abl l. es.

e 27 summarize n evaluation ted studi e tific literatu ity to terrestrial a riz ed u

T e 27. Terrestrial toxici ty profile for dicofo

Endpoint Species Toxicity Value Used in Risk Assessment Source (MRID) Comment

Acut Terre Average body weight of 1135 g for this species fromTot e Direct Toxicity to strial-Phase CRLF pheasant ( Phasianus colchicus ) LD 50 = 265 mg a.i./kg bw 160000 Dunning 1984 used in REX. Slope data are n available. Ring-necked

Suba Terre cute Direct Toxicity to strial-Phase CRLF Japanese quail ( Coturnix japonica ) LC 50 = 905 ppm ECOTOX# 35240 Available slope is 5.92

Chro Terre ( Falco sparverius ) ppm 41934001 on
thickness. Body weight for

this species is 0.100 kg

from Dunning 1984. nic Direct Toxicity to

trial-Phase CRLF American kestrel NOAEC = 1 LOAEC = 3 ppm based 8% decrease in egg shell

s

Indirect Tox Terrestrial-Pha (via acute toxi prey item rat g g 40731204 No slope is available. icity to se CRLF
to mamm city alian s) Laboratory ( Rattus norve icus ) LD

m 50 = 587 /kg-bw

Indirect Tox Terre chron

mamm ms) L tory r NOAEC = 5
ppm .4 mg/kg/ ) 4160 LO m; based

on emic and ffects. icity to strial-Phase CRLF (via ic toxicity to

alian prey ite abora at (0 day 6601 AEC = 25 pp parental syst reproductive e

Indire Terre (via
acute ial invert y bee ( Apis mellifera ) D 50 >50 a.i./bee 0500 LD ent to >391 μg a.i./g of bee ct Toxicity to strial-Phase CRLF toxicity to terrestr ebrate prey items) Hone L μg 1991 50 is equival

Indire Terre Phase
terres No data are available to quantify this endpoint ct Toxicity to strial- and Aquatic- CRLF (via toxicity to trial plants)

83Table 28. Categories of acute toxicity for avian and mammalian studies.
Toxicity Category Oral LD 50 (mg/kg) Dietary LC 50 (ppm) Very highly toxic < 10 < 50 Highly toxic 10 - 50 50 - 500 Moderately toxic 51 - 500 501 - 1000 Slightly toxic 501 - 2000 1001 - 5000 Practically non-toxic > 2000 > 5000

4.3.1. Toxicity of Dicofol to Birds

An acute oral toxicity study with ring-necked pheasant ( Phasianus colchicus ) established an LD 50 of 265 (211-334) mg ai/kg bw (MRID 160000) . This indicates that dicofol is moderately toxic to avian species on an acute oral exposure basis.

Available subacute dietary toxicity data fo r birds exposed to dicofol include 8-day LC 50 values ranging 905-3010 ppm ( Table 29 ). Therefore, dicofol is classified ( Table 28 ) as

oderately to slightly toxic to birds on a subacute dietary exposure bas m

a is. Data are

vailable for 4 species of birds exposed to dicofol. The most sensitive species is the e of 905 ppm (ECOTOX # 35240). T eri qu r the C serving to the adult CRLF.

toxic a (LC 50 ) bird Japanese quail ( Coturnix japonica ), with an LC 50 valu

his value is used for d ving risk otient s fo RLF and frogs as prey

Table 29. Subacute dietary ity dat for s expo sed to dicofol.

Species (common name) 95% LC 50 va lue (ppm ) confidence interv al (μppm ) In of itial age test birds

(days) Slope Sour ce

Coturnix japonica (Japanese quail) 905 723-1140 C 35 1 5.92 E OTOX# 240 C. japonica 1237 979-1578 4.89 GS0021010 (Japanese quail) 7
C. japonica (Japanese quail) 1418 1232-1628 02 12 4.13 00 2923
C. japonica (Japanese quail) 1545 1360-1 7.95 GS0 739 14 021011
Anas platyr hynch (mallard duck) os 1651 1356-2 5.64 00022 029 10 923
C. japonica (Japa nese quail) 1746 1377-2255 21 5.37 GS0021012

Ph asianus colchicus (ring-necked pheasant) 2126 1892-2387 16 7.38 00022923
Colinus virginianus (bobwhite quail) 3010 2635-3424 15 4.31 00022923

84Several chronic studies are available where birds were exposed to dicofol ( Table 30 ). Available chronic studies include d data on American kestrel ( Falco sparverius ), eastern screech owls ( Otus asio ), ring doves ( Streptopelia risoria), mallard ducks ( Anas platyrhynchos ) and northern bobwhite quail ( Colinus virginianus ). From these studies, the most sensitive chronic toxicity endpoint is a NOAEC of 1 pp m based on reproductive effects to the American kestrel. This valu e is based on a LOAEC where effects to egg shells were observed. There is some uncerta inty in relying upon obs erved effects to egg shells to represent effects to reproduction of the CRLF, since the CRLF does not produce eggs with hardened shells. However, observe d effects in bird eggs caused by parental exposures to dicofol could resu lt in other effects to amphibian eggs that ar e unrelated to egg shell thickness but do affect th e compositi on of the egg coatings that regulate osmotic

alance in eggs. In addition, e ffects to other endpoints that di rectly relate to amphibians,

th e adult CRLF. Another consideration is that icofol produces similar effects in bird s as DDT/DDE. This endpoint has clear b including decreased numbers of eggs laid and feminization of male chicks were observed at 40 ppm. In the two studies where these effects were observed in birds, a NOAEC was not established, i.e ., effects were measured at all levels tested. Therefor e the available 1 ppm NOAEC is used for deriving risk quotie nts for the CRLF and terrestrial frogs ( e.g., the Pacific tree frog) serving as prey to d population level effects as demonstrated with bald eagles exposed to DDT.

Table 30. Chronic toxicity data for birds exposed to dicofol.

Species (common name) NOAEC (ppm) LOAEC (ppm) Observed Effects Source
Falco sparverius 1 3 (Am erican kestrel) Decreased egg shell thickness (8%) MRID 41934001 Otus asio (eastern screech owls) none 7.2 Decreased shell weight (11.7- 13.5%) and thickness (7.6-11%) of eggs Wienmeyer et al. 1989

Anas platyrhynchos (mallard duck) 10 40 Increased number of cracked eggs (12%) MRID 41231301 Streptopelia risoria (ring dove) none 40 Decreased egg-shell thickness and egg production, increased number of cracked eggs (11.2%) Schwarzbach et al . 1988

F (A

alco sparverius None 40

merican kestrel) increase in eggs lost, potential feminization of male chicks al. 1996 Decreased number of eggs laid, MacLellan et

Anas platyrhynchos (mallard duck) 10 none none GS0021-014

Colinus virginianus (northern bobwhite quail) 120 none none MRID 40042055

In a reproduction study with the American kestrel, eggshells were thinned by 8% in parent birds fed 3 ppm techni cal dicofol for up to 175 days . Shell weight was also reduced by 9% at concentra tions as low as 10 ppm. The resulting NOAEC for the study d

s nerations. Female birds in the first generation treated with 20 mg/kgwas 1 ppm (MRID 41934001). In a second study w ith captive American kestrels, paire females were given daily oral doses of 0, 5 an d 20 mg/kg-bw of dicofol. This study wa conducted over 2 ge

85bw (10.98%) compared to ontrols. Female birds in th e second generation treated with 5 mg/kg-bw had an increase

male ffspring with abnormal gonads. Histological examination of male gonads indicated a

osed to 40 ppm dicofol in a reproductive study. Observed effects at is level included significant re ductions in egg shell thickness (9% less than to controls),

a reproduction study with mallard ducks expos ed to technical grade dicofol, egg shell
stren f cracked eggs compared to

ont her effects were observed

ith nor thern bobwhite quail e xposed to technical grade dicofol, produced eggs with significantly redu ced shell thickness

c in number of eggs lost and a de crease in total number of eggs laid compared to controls. Female birds of the first and second genera tion treated with 5 mg/kg-bw produced

o thickened cortex and a significant increase in primordial germ cells present in male offspring of females treated with 5 mg/ kg-bw. The authors suggested that this histological evidence indicated femini zation of male offspring (MacLellan et al. 1996). As 5 mg/kg-bw was the lowest treatment le vel, a NOAEL could be established for this study. On a dietary exposure basis, a dose of 5 mg/kg- bw/day is approximately equivalent to 40 mg/kg-diet/day 7

. In a reproduction study with eas tern screech owls, birds were exposed to 7.2 ppm dicofol in feed. At this concentr ation, shell weight was reduced on average by 12-14% compared to controls. Also, egg shell thickness wa s reduced by 8-11% on average, compared to controls. Since only one treatment group wa s involved in this study, a NOAEC could not be determined (Wienmeyer et al. 1989).

Ring doves were exp th increased numbers of cracked eggs (14.3 more than cont rols), and decreased egg production (13% less than controls). In addition, 14.3% of clutches produced by the treated group contained only single eggs, as compared to 1.8% of clutches produced by the control group (Schwartzbach et al. 1988).

In gth was significantly redu ced (12% increase in number o rols) at 40 ppm, resulting in a NOAEC of 10 ppm. No ot c during this study (MRID 41231301). In anothe r reproductive study with mallard ducks, birds treated with 5 ppm and 10 ppm show ed no significant effects to reproduction compared to controls. Effects considered in this study included number of eggs laid, eggs cracked, eggs embryonated, survival of embryos and hatc hling survival. Egg shell thickness data were no t reported (GS0021-014).

n a reproduction study w I no significant effects to reproduction were observed relative to controls. Effects considered in this study included eggs laid, eggs cracked, egg shell thickness, eggs set, viable embryos, survival of embryos and hatc hling survival. The highest treatment level

f this study was 120 ppm (MRID 40042055). o

7 The available dose-based value (5 mg/kg-bw) is multiplied by the body weight (BW) of the bird (0.111 kg, from Dunning 1984) and then divided by the food intake rate. The food intake rate (FI, in kg/ day), is

lculated according to:

. )1993 (*0582.0 651.0 USEPA BW FI = ca

864.3.2. Toxicity of Dicofol to Mammals

Available acute toxicity data fo r the laboratory rat indicates that dicofol is slightly toxic to mammals on an acute oral exposure basis (LD 50 =587 mg/kg, MRID 40731204).

In a two-generation reproduction study, groups of laboratory rats (25/sex/group) were fed

ectively). For parental systemic toxicity, the NOAEC was 5 ppm (0.4

tive xicity, the NOAEC was 5 ppm (0.4 mg /kg-bw/day) and the LOAEC was 25 ppm

1 females, For offspring toxicity, the

dditional chronic toxicity data for mammals (rats and mice) exposed to dicofol were rted data corresponded to higher NOAEC , NOAEC = 5 ppm (0.4 mg/kg/day); MRID

bee; MRID 05001991). An acute oral LD 50 for ees has also been reported as >10 μg a. i./bee (MRID 05001991). In a study where a 1%

restrial Plants

an endpoint to represent effects of dicofol xposures to vascular plants . However, there are several studies available in the scientific literature to qualitatively desc ribe effects of dicofo l on vascular plants. diets containing dicofol (93.3%) at dose levels of 0, 5, 25, 125 or 250 ppm (equivalent to 0.4, 1.9, 9.5, or 18.9 mg/kg-bw/day for ma les and 0.4, 2.1, 10.5, or 20.5 mg/kg-bw/day for females, resp mg/kg-bw/day) and the LOAEC was 25 ppm (1 .9/2.1 mg/kg-bw/day for M/F) based upon histopathological changes in P and F 1 livers (hypertrophy of centrilobular hepatocytes with associated vacuolation) and F 1 ovaries (increased vacuol ation). For reproduc
to (1.9/2.1 mg/kg-bw/day in M/F), based on the ovarian vac uolation in the F which was judged to be an effect on reproduc tive physiology. NOAEC could be defined at 25 ppm (1.9/2.1 mg /kg-bw/day for M/F) and the LOAEC at 125 ppm (9.5/10.5 mg/kg-bw/day for M/F), based on decreased F 2 pup viability (increased numbers of stillborn pups, postnat al day 0-4 pup deaths, and total litter loss) (MRID 41606601).

A available in ECOTOX. However, all re po values than that used in this assessment ( i.e. 41606601). Therefore, these data were not considered further for this assessment.

4.3.3. Toxicity of Dicofol to Terrestrial Invertebrates

Dicofol is classified as practic ally nontoxic to honey bees ( Apis mellifera ) on an acute contact exposure basis (LD 50 >50 μg a.i./ b solution of a formulated product containing 18.5 % dicofol was applied directly to honey bee hives through saw cuts in the frame, no abnormal mortality was observed in worker bees (MRID 05009244).

For the purpose of this assessment, the acut e contact honey bee en dpoint is used to represent effects to terrestrial invertebrates. This toxicity value is converted to units of μg a.i./g (of bee) by multiplying by 1 bee/0.128 g resulting in an LD 50 >391 μg a.i./g.

4.3.4. Toxicity of Dicofol to Ter

There are no data are available to quantify

e

87In a study involving 15 types of or namental plants, dicofol app lied as a spray resulted in phytotoxicity to begonias. No effects were ob served to the other 14 ornamental plants

In a study involving the papaya ( Carica papaya ), 0.125% of a formulation including rowth and resulted in leaf burn (Sherman and Sanchez 1968).

r its egradates to terrestrial organisms.

June of 2000 in Tulare County that the observed plant damage was associated with exposure to dicofol was consid ered possible. The legality of the use was undetermin

dustry, and discharged pro cess wastewater into the unl ined wastewater pond. This included in the test, including antirrhinum, as ters, carnation, chrysanthemum, cineraria, coleus, cyclamen, dahlia, geranium, petunia, polyanthus, ,saintpau lia, violets and zinnia (Dennis and Edwards 1963).

When neanthe bella palm ( Chamaedorea elegans ) was exposed to dicofol, phytotoxicity was observed. Dicofol applied to 6 other sp ecies of plants did not cause phytotoxicity (Knauss 1971).

dicofol affected plant g

4.4. Toxicity of dicofol degradat es to terrestrial organisms

There are no data available from registrant-subm itted studies or in the scientific literature to evaluate the potential toxicity of dicofol degradates to terrestrial organisms. In addition, there are no models or tools available to estimate th e toxicity of dicofol o d

4.5. Incident Database Review for Dicofol

A search of the EIIS (Environmental Inci dent Information System) database for ecological incidents (run on February 24, 2009) id entified 1 incident associated with the use of dicofol. This incident involved plant damage to 10 acres of oranges treated directly with dicofol and chlorpyrifos. The incident occurred in of California. The certainty (like lihood)

ed (Incident # I013563-010).

In 1980, a wastewater pond maintained by the Tower Chemical Company (TCC) overflowed into an onsite drainage ditch wh ich flowed downstream into the Gourd Neck of Lake Apopka. Lake Apopka is the fourth largest freshwater lake (12,500 ha) in the state of Florida and has been designated as one of Florida's most polluted. From 1957 to 1981, TCC manufactured and stored various pest icides, used primarily in the citrus in discharge included dicofol, as much as 15% of DDT and its metabolites (DDD, DDE, and chloro-DDT), and sulfuric acid. Studies subsequent to the upset showed a dramatic decline in the American alli gator population duri ng the 1980s that cont inued into the mid to late 1990s (Guillette et al. 1994).

88

### 5 .0 Risk Characterization

Risk characterization is used to determine the fo and irec o the CRLF or for m ation to its designated l ha om the use of dicofol in CA. The risk characterizati on provides an e ion ( n 5.1 a des ion (Section 5.2) of the likelihood of adverse effects; articu late asse t assum ns, l ns, and uncertainties; and synthesi zes an overall conclusion regarding the likelihood of adverse effects to the CRLF or its designated cr itical habitat ( ‘no effect,’ ‘likely to adversely affect,’ or ‘may affe t not to ad ly affe

5.1. Risk Estimation

Risk is estimated by calculating the ratio of e re to ty. T atio is isk q Q), which is then compared to pr e-established acute and chronic levels of

c category evaluated ( dix C or ac posure the CRLF and its animal prey in aquatic habitats, as well as terrestrial in rates, the LOC is 0.05. For acute exposures to the CRLF and als, OC i The L for

c well as acute exposures to plants is 1.0.

R by calculating the ratio of

xposure to toxicity using 1-in-10 year EECs based on th e label-recommended dicofol

. terrestrial insects, small mammals and terr se are ated based on exposures resulting from a pplications of dicofol ( Table 20 and Risk characterization is the integration of the exposure and effect s characterizations. potential

critica r direct bitat fr /or ind t effects t odific stimat Sectio ) and cript s risk ssmen ptio imitatio i.e
., ct, bu likely verse ct’).

xposu toxici his r the r uotient (R oncern (LOCs) for each Appen ). F ute ex s to verteb

mamm the L s 0.1. OC hronic exposures to CRLF and its prey, a s
isks to the aquatic-phase CRLF and its prey are estimated

e usage scenarios summarized in Section 2.4.4 a nd the appropriate aquatic toxicity endpoint from Section 4.1. Risks to the terrestrial-phase CRL F and its prey ( e.g estrial-pha frogs) estim

89T able 21 ) and the appropriate toxicity endpoint from Section 4.4.

5.1.1.1. t Effects to Aquati L

Direct effects to the aquatic-phase CRLF are based on peak EECs of total dicofol r in the standard pond and the lowest a xicit e fo water In order to assess direct chronic risks to th e CRLF, 60-day EECs of total dicofol residues (including dicofol, DCBP, FW-152, DCBH , and OH-DCBP) and the lowest chronic toxicity value for freshw ater fish are used.

Acute and chronic RQs for the aquatic-pha se F res from U cations of dicofol are provided ble able and Table 33 respectively. For exposures involving dicofol s deg s of rn, RQ all uses of dicofol exceed the acute listed species (0.05 the tion of fol use on Bermuda grass and outside buildings. for c exp s to th LF

r fo ses, Ber grass, and outside buildings. Although RQs for aerial app lications are higher th an those for ground

a and aeria l applications, both

s aquatic-phase CRLF. 5.1.1. Exposures in the Aquatic Habitat

Direc c-Phase CR F

esidues cute to y valu r fresh fish.

CRL ulting aerial, ground and LV appli in Ta 31

, T 32

, and it radate conce s for LOC ), with excep dico RQs hronic osure e CR e all uses exceed the LOC (1.0)

sulting from r all u except muda turf

pplications, for all uses of dicofol that ha ve both ground ets of RQs exceed levels of concern for the

Table 31. Acute and chronic RQs for aquatic-phas e CRLF resulting from AERIAL applications of dicofol. EECs are based on pa rent and degradates of concern.

Use Peak EEC (μg/L) 60-day (μg/L) Acute RQ 1 Chronic RQ 2
Beans 17.77 15.47 0.34 3 3.5 4
Citrus 17.50 13.29 0.33 3 3.0 4
Cotton 18.02 16.27 0.34 3 3.7 4
Cucurbit 6.32 5.37 0.12 3 1.2 4 Grape 13.15 11.17 0.25 3 2.5 4 Hops 19.67 17.50 0.37 3 4.0 4
Mint 16.47 14 3 4 .56 0.31 3.3 Pep per 8.91 7.74 0.17 3 1.8 4
Pome Fruit 20.73 16.26 0.39 3.7 3 4
Stone Fruit 9.97 7.76 0.19 3 1.8 4
St rawberry 37.39 0.71 3 7.6 4 33.41
Tomato 6.30 5.16 12 3 1.2 4 0. Walnut/Pecan 20. 18.0 .39 3 .1 4 77 6 0 4
1 Based on 96-h LC 50 = 53 μ tthroat t AEC = 4.4 μg/ inbow tro endan pecies le ncern 5) onic risk level o rn (RQ> g/L for cu rout 2 Based on NO L for ra ut 3 Exceeds acute risk to gered s vel of co (RQ>0.0
4 Exceeds chr f conce 1.0)

90T able 32. Acute and chronic RQs for aquatic-phas e CRLF resulting from GROUND applications of icofol. EECs are based on pa rent and degradates of concern.
nic
2 d

Use Peak EEC (μg/L) 60-day (μg/L) Acute RQ 1 Chro RQ
Beans 15.87 14 .27 0.30 3 3.2 4
Citrus .53 5 3 12.99 10 0.2 2.4 4
Cotton 14.9 3 16.01 9 0.30 3.4 4
Cucurbit 5.52 4.77 1.1 4 0.10 3 Grape 11. 10.07 21 3 31 0. 2.3 4 Hops 18.35 16.69 0.35 3 3.8 4
Mint 15. 13.50 29 3 14 0. 3.1 4 Pepper 8.23 7.43 16 3 1. 4 0. 7 Pome Fruit 15. 12.25 29 3 40 0. 2.8 4
Stone Fruit 7.60 6.05 14 3 1. 4 0. 4 Strawberry 36. 32.15 69 3 36 0. 7.3 4
Tomato 5.2 4.41 10 3 2 0. 1.0 4
Walnut/Pecan 17. 16.02 34 3 94 0. 3.6 4 Bermuda grass 2.3 1.93 4 1 0.04 0.44 Ornamentals 6.09 5.25 11 3 1. 0. 2 4
Turf/Sod Farm 2.88 2.40 0.054 3 0.55 O utside Buildings 0.354 0.248 0.0067 0.056
1 Based on 96-h LC = 53 μg/L for cutthroat trout 50 2 Based on NOAEC = 4.4 μg/L for rainbow trout
3 Exceeds acute risk to endangered species level of concern (RQ>0.05)
4 Exceeds chronic risk level of concern (RQ>1.0)

able 33. Acute and chronic RQs for aquatic-ph ase CRLF resulting from ULV applications of T dicofol. EECs are based on pa rent and degradates of concern.

Use Peak EEC (μg/L) 60-day (μg/L) Acute RQ 1 Chronic RQ 2
Beans 31.80 25.26 0.60 3 5.7 4
Citrus 45.13 33.29 0.85 3 7.6 4
Cotton 31.57 25.23 0.60 3 5.7 4
C ucurbit 12.14 9.41 0.23 3 2.1 4 Grape 25.28 19.80 0.48 3 4.5 4 Hops 29.66 24.58 0.56 3 5.6 4
Mint 28.76 23.28 0.54 3 5.3 4 Pepper 15.88 12.61 0.30 3 2.9 4
Pome Fruit 3 4 48.90 36.56 0.92 8.3 St one Fruit 23.78 17.68 0.45 3 4.0 4 Strawberry 51.32 43.81 0.97 3 10 4
Tomato 13.70 10.35 0.26 3 2.4 4
Walnut/Pecan 40.15 31.59 0.76 3 7.2 4

1 Based on 96-h LC 50 = 53 μg/L for cutthroat trout
2 Based on NOAEC = 4.4 μg/L for rainbow trout
3 Exceeds acute risk to endangered species level of concern (RQ>0.05)
4 Exceeds chronic risk level of concern (RQ>1.0)

91A s discussed above in section 3.3, dicofol has the potential to accumulate in tissues of d

r to define the risks of aquatic-phase CRL F g lank lgae c invertebrates and fish, KABAM was used to d Q v r sm .4 g), um (37 g) and large (238 g) aquatic-phase CRLF. we sum are co ent with those incorporated into T-HERPS. Diet a tions assigned to each of these size classes are provided in Table 34 . The resultin alue he C re pro in T ceed the LO or ac se ba nd chronic, dietary-based exposures to the CRL F ingesting dicofol through consum of c inated aquatic prey (that have accumula ofol)

T t assumptions of small, medium and larg tic-ph LF u BAM
Diet aquatic organisms. Since aquatic-phase CRLF consume algae, aquatic invertebrates an fish, CRLF could be exposed to dicofol accumulate d in the tissues of these prey. In orde consumin

erive R phytop alu es fo ton (a all (1 ), benthi medi Body ight as ptions nsist
ssump g RQ v s for t RLF a vided able 35 . RQ values for all size classes ex C f ute-do sed a ption
ontam ted dic

.

able 34. Die e aqua ase CR sed in KA

. for:
Trophic leve l in diet small CRLF 1 small CRLF 2 ed LF 1 RLF large 1 large CRLF 2 m CR med C 2 CRLF phytoplankton 100.0% 0.0% .0% 0% 0.0% 0.0% 0 0. zooplankton 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% benthic invertebrates 0.0% 10 0. 0% 100.0% 0.0% 100.0% 0.0% filter feeders 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% small fish 0.0% 0.0% 0.0% 100.0% 0.0% 0.0%

m edium fish 0.0% 0.0% 0.0% 0.0% 0.0% 100.0% large fish 0.0% 0.0% 0.0% 0.0% 0.0% 0. 0%
Total 100.0% 100.0% 100.0 % 100.0% 100.0% 100.0%

Table 35. Acute and chronic RQs for aquatic-ph ase C xpose ofol throu c ion of aquatic organisms which have accum dicofo

Size Classes of CRLF se RQ 1 Acut Dieta ased Chronic, Dietary Ba 3 RLF e d to dic (parent) gh onsumpt ulated l.

Acute, Do Based e, ry RQ 2 B sed RQ

small CRLF 1 4 0.01 0.63 2 11 5

small CRLF 2 4 0.01 0.38 7 15 5

med CRLF 1 73 0.01 0.0 7 15 5

med CRLF 2 4 0.04 0.17 3 39 5

large CRLF 1 9 0.01 0.02 7 15 5

large CRLF 2 4 0.09 0.14 2 4 83 5

1 Based on LD 50 = 265 mg/kg-bw (for ring-nec ked pheasant) l)

concern (RQ>0.1) Exceeds chronic risk level of concern (RQ>1.0) 2 Based on LC 50 = 903 ppm (for Japanese quai
3 Based on NOAEC = 1 ppm (for American kestrel)
4 Exceeds acute risk to endangered species level of
5

92Indirect effects of dicofol to the aquatic-phase CRLF (t s) vi uction onvascular aquatic plants in its diet are based on peak EECs he st d pond the lowest toxicity value (EC 50 ) for aquatic non-va plan Q va enerate ing EECs representing total residues of dicofol ( ) a s tha 1 for ses, which is below the LOC (1.0) for non-vascular c pla

Indirect acute effects to the aquatic-phase CR ia ef ebr in aquatic habitats are based on p eak EECs of tota fol re in th dard p and the lowest acute toxicity value for freshwater tebrates. For chronic risks, 21-day E al dicofol residues and the lowest chronic toxicity value verteb used to derive RQs.

Acute and chronic RQs for the aquatic inve rt s res from al, ground and U ovided ble able and Table 38

r fol exceed the acute listed species LOC (0.05) for

a ermuda grass, ornamentals, turf and outside buildings. RQs for chroni c exposures to the CRLF from all uses of

icofol exceed LOC (1.0), except cucurbits, peppers, tomatoes, Bermuda grass, rnamentals, turf and outside buildings. 5.1.1.2. Indirect Effects to Aquatic-Phas e CRLF through effects to prey

adpole a red in n from t andar and scular ts . R lues g d us Table 12 re les n 0.0 all u aquati nts.

LF v fects to prey (invert ates) l dico si dues e stan ond inver ECs of tot for in rates are

ebrate ulting aeri 37

, LV applications of dicofol are pr in Ta 36

, T espectively. RQs for all uses of dico quatic invertebrates, with the exception of dicofol use on B

d

o

Table 36. Acute and chronic RQs for aquatic invert ebrates resulting from AERIAL applications of dicofol. EECs are based on pa rent and degradates of concern.

Use Peak EEC (μg/L) 21-day (μg/L) Acute RQ 1 Chronic RQ 2
Beans 17.77 16.16 0.13 3 0.85 Citrus 17.50 14.40 0.12 3 0.76 Cotton 18.02 16.81 0.13 3 0.88 Cucurbit 6.32 5.63 0.045 0.30 Grape 3 13.15 11.78 0.09 0.62 19.67 18.51 0.14 3 0.97 Hops
M int 16.47 15.58 0.12 3 0.82 Pepper 8.91 8.09 0.064 3 0.43 Pome Fruit 20.73 17.51 0.15 3 0.92 Stone Fruit 9.97 8.37 0.071 3 0.44 Strawberry 37.39 34.68 0.27 3 1.8 4
Tomato 6.30 5.49 0.045 0.29 Walnut/Pecan 20.77 18.80 0.15 3 0.99
1 Based on 48-h EC 50 = 140 μg/L for daphnid
2 Based on NOAEC = 19 μg/L for amphipod
3 Exceeds acute risk to endangered species level of concern (RQ>0.05)
4 Exceeds chronic risk level of concern (RQ>1.0)

93Table 37. Acute and chronic RQs for aquatic invert ebrates resulting from GROUND applications of dicofol.
Peak EEC 21-day Acute RQ 1 Chronic RQ 2 EECs are based on pa rent and degradates of concern.

Use (μg/L) (μg/L)
B eans 15.87 14.69 0.11 3 0.77 Citrus 12.99 10.87 0.093 3 0.57 Cotton 16.01 15.36 0.11 3 0.81 Cucurbit 5.52 4.98 0.04 0.26 Grape 11.31 10.39 0.081 3 0.55 Hops 18.35 17.45 0.13 3 0.92 Mint 15.14 14.22 0.11 3 0.75 Pepper 8.23 7.66 0.059 3 0.40 Pome Fruit 15.40 13.13 0.11 3 0.69 Stone Fruit 7.60 6.48 0.054 3 0.34 Strawberry 36.36 33.38 0.26 3 1.8 4
Tomato 5.22 4.65 0.037 0.24 Walnut/Pecan 17.94 16.52 0.13 3 0.87 Bermuda grass 2.31 2.02 0.016 0.11 Or namentals 6.09 5.51 0.044 0.29 Turf/Sod Farm 2.88 2.52 0.021 0.13 Outside Buildings 0.354 0.281 0.0025 0.015
1 Based on 48-h EC 50 = 140 μg/L for daphnid d on NOAEC = 19 μg/L for amphipod.
3 endangered species level o n (RQ>0.05 0) 2 Base Exceeds acute risk to
4 Exceeds chronic risk l f r conce ) evel of concern (RQ>1.

Table 38. Acute and chronic RQs for aquatic inv tes resultin ULV applicat d EECs are based on pa rent and degradat ncern.

Use EEC g/L) 2 (μ Acute RQ 1 onic Q 2 e rtebra g from ions of icofol. es of co
Peak

(μ 1-day g/L) Chr R Beans 31 .80 2 0.23 3 1.4 4 7.04 Citrus 45 .13 3 0.32 3 1.9 4 6.41 Cotton 31 .57 2 0.23 3 1.4 4 7.01 C 12.14 10.18 0.087 3 0.54

ucurbit G 8 21.29 0.18 3 1.1 4

rape 25.2 Hops 29.6 6 25.90 0.21 3 1.4 4
Mint 28.76 24.71 0.21 3 1.3 4 Pepper 15.88 13.49 0.11 3 0.71 Pome Fruit 48.90 39.92 0.35 3 2.1 4
Stone Fruit 23.78 19.38 0.17 3 1.0 4
S .31 0.37 3 2.4 4

trawberry 51.32 45
Tomato 13.70 11.2 7 0.10 3 0.59 40.15 33.92 0.29 3 1.8 4 W alnut/Pecan
1 Based on 48-h EC 50 = 140 μg/L for daphnid Based on NOAEC = 19 μg/L for amphipod Exceeds acute risk to endangered species level of concern (RQ>0.05)
4 Exceeds chronic risk level of concern (RQ>1.0) 2

3

94Fish and frogs also represent potential prey items of adult aquatic-phase CRLFs. RQs associated used to assess potential indirect effects to the CRLF based on a reduction in freshwater

sh and frogs as food items. As noted above, exposures involving dicofol and its

eff ects of dicofol to vascular aquatic plants, Q values for vascular aquatic plants cannot be derived. with acute and chroni c direct toxicity to the CRLF ( Table 31 and Table 32 ) are

fi degradates of concern (DCBP, FW-152, DCBH , and OH-DCBP), RQs for all uses of dicofol exceed the acute listed species LOC ( 0.05), with the excepti on of dicofol use on Bermuda grass and outside buildings. RQs for chronic exposures to the CRLF resulting from all uses exceed the LOC (1.0) for all us es, except Bermuda grass, turf and outside buildings.

5.1.1.3. Indirect Effects to Aquatic-Phas e CRLF through effects to habitat

Indirect effects to the CRLF vi a direct toxicity to aquatic plants are estimated using the most sensitive non-vascular and vascular plan t toxicity endpoints. RQ values generated for non-vascular plants using EECs repr esenting total resi dues of dicofol ( Table 12 ) are less than 0.01 for all uses, which is below the LOC of 1.0 for non-vasc ular aquatic plants. Since no data are available to quantify the R

955.1.2. Exposures in the T errestrial Habitat

5.1.2.1. Direct Effects to Terrestrial-Phase CRLF

acute risks to the terrestri al-phase CRLF are derive d by considering dose- T-RE a small bird (20 g) consumi all 0 ) and acute oral and subacute diet ary toxicity endpoints for avian otential direct chroni c risks of dic the terre strial-phase CRLF are derived considering dietary-based exposures m d in T-RE r a small bird (20g) all invertebrates and the low ailable chr oxicity data f rds. re divided by toxicity va lues to estim ronic diet Qs. Acute dose- (0.1 all uses of l, with RQs e ing factors ranging between 4.3 to for most uses, with the exceptio use on cuc ornamentals, turf and s exceed the LOC (1.0) for all uses of dicofol,

dicofol to X. Potential direct and dietary-based EECs modeled in X fo r ng sm invertebrates ( Table 2 species. P ofol to by odele X fo consuming sm est av onic t or bi EECs a ate ch ary-based R based RQs ( Table 39 ) exceed the LOC the LOC by ) for 32X. Acute dietary-based RQs exceed the dicofo xceed

LOC (0.1) n of urbits, Bermuda gra ss. Chronic dietary-based RQ by factors ranging 54 to 405X ( Table 39 ).

Table 39. Acute an the terrestrial-phas d chronic, dietary-based RQs and dose-based RQs for direct effects of e CRLF. RQs calculated using T-RE

Use Acute, Doseba sed 7 Acute, Dietary- Chronic, Dietarybased 8 based 9 Citrus, 1 Pome Fruits 2 3.2 10 0.45 10 405 11 Strawberries, Walnuts (English/black), 2.13 10 0.30 10 270 11 Pecans Beans, cotton, Stone Fruits 3 1.59 10 0.22 10 203 11 Grapes, mi nt 4 1.33 10 0.19 10 169 11 Hops 1.24 10 0.17 10 157 11 Peppers, To matoes 0.80 10 0.11 10 101 11
Cucurbits 5 0.66 10 0.09 84 11 Ornamentals, 6 Turf grasses, Sod farms, Outside building surfaces 0.53 10 0.07 67 11
Bermuda grass 0.43 10 0.06 54 11

1 grapefruit, lemons, oranges, tangelos, and tangerines
2 apple s and pears
3 apricots, cherries, nectarines, peaches, plums, and prunes
4 mint, peppermint and spearmint
5 cantaloupes, cucumbers, melons, pumpkins, watermelons, and winter and summer squash
6 nurseries and flowers
7 Based on LD 50 = 265 mg/kg-bw (for ring-necked pheasant)
8 Based on LC 50 = 903 ppm (for Japanese quail)
9 Based on NOAEC = 1 ppm (for American kestrel)
10 Exceeds acute risk to endangered species level of concern (RQ>0.1)
11 Exceeds chronic risk level of concern (RQ>1.0)

96s to Terrestrial- Phase CRLF through Effects to Prey

i tats, the honey bee is used as a surrogate for rrestrial invertebrates. EECs (μg a.i./g of bee) calculated by T-REX for small and large

inate, i.e ., the LD 50 value exceeds the

pressed as less than (<) values. For small insect

fol, RQ values potentia lly exceed the acute sk LOC (RQ> 5.1.2.2. Indirect Effect

In order to assess the ri sks of dicofol applications to terrestrial invertebrates, which are considered prey of CRLF in terrestrial hab
te i nsects are divided by the calc ulated toxicity value (LD 50 ) for terrestrial invertebrates, which is >391 μg a.i./g of bee. The resulti ng RQ values for large insect and small insect exposures bound the potential range of exposures for terrestrial insects to dicofol. Since the acute contact toxicity estimate is indeterm h ighest dose tested (LD 50 >50 μ g/bee) the resulting toxici ty value for terrestrial invertebrate is also indeterminate (LD 50 >391 μg a.i./g of bee). As such, RQ values based on these indeterminate values are ex

e xposures, RQ values range <1.04 to <0.138. For large insect exposures, RQ values range <0.115 to <0.0153. For all uses of dico ri 0.05) for terrestrial insects.

are used. Acute and chronic effects are

stimated using the most sensitive acute (rat LD 50 =587 mg/kg-bw) and chronic (rate

toxicity values and RQs used to assess direct effects to the CRLF. Acute dose-based RQs exceed the LOC (0.1) for all uses of dico fol, with RQs exceeding the LOC by factors

nging between 4.3 to 32X. Ac ute dietary-based RQs exceed ed the LOC (0.1) for most

cofol, by factors nging 54 to 405X ( Table 39 ). As described above, to assess risks of dicofol to prey (small mammals) of larger terrestrial-phase CRLF, dietar y-based and dose-based exposures modeled in T-REX for a small mammal (15g) consuming short grass

e NOAEC 5 mg/kg diet; 0.4 mg /kg-bw/day) mammalian toxicity data. EECs are divided by the toxicity values to estimate acute and ch ronic dietary-based RQs as well as acute dosebased RQs. Acute dose-based RQ values exceed the listed species acute risk LOC (RQ>0.1) for the majority of dicofol uses . Across all uses, chronic dose-based and dietary-based RQs exceed the chronic risk LOC (RQ>1.0) ( Table 40 ).

An additional prey item of the adult CRLF is other species of frogs. In order to assess risks to these organisms, dietary-based a nd dose-based exposures modeled in T-REX for a small bird (20g) consuming small inverteb rates are used. These are the same EECs,

ra uses, with the exception of use on cucurbits, ornamentals, turf and Bermuda grass. Chronic dietary-based RQs exceed the LOC ( 1.0) for all uses of di

ra

9740. RQs for determining indirect effects to the terrestrial-phase Table CRLF through effects to potential prey items, specifically small te rrestrial mammals consuming short grass.

Use Acute, dose-based 7 Chronic, dose-based 8 Chronic, dietary-based 9

Ci trus, 1 Pome Fruits 2 0.53 10 781 11 144 11
Str lish/black), Pecans 0.35 10 521 11 96 11 awberries, Walnuts (Eng Beans, cotto , Stone Fruits 3 0.27 10 390 11 72 11 n apes, mint 4 0.22 10 325 11 60 11 Gr
Ho ps 0.21 10 303 11 55 11
Pe ppers, Tomatoes 0.13 10 195 11 36 11
curbits 5 0.11 10 163 11 30 11 Cu Or bu namentals, 6 Turf grasses, Sod farms, Outside ilding surfaces 0.09 130 11 24 11

Be rmuda grass 0.07 104 11 19 11

1 gra 2 apples and pears
3 apri
4 m 5 c 6 n 7 B
8 B
9 B
10 E ies level of concern (RQ>0.1)
11 Exceeds chronic risk level of concern (RQ>1.0) pefruit, lemons, oranges, tangelos, and tangerines

cots, cherries, nectarines, peaches, plums, and prunes int, peppermint and spearmint antaloupes, cucumbers, melons, pumpkins, watermelons, and winter and summer squash urseries and flowers ased on LD 50 for laboratory rat = 587 mg/kg. ased on chronic NOAEL for laboratory rat = 0.4 mg/kg-bw. ased on chronic NOAEC for laboratory rat = 5 ppm. xceeds acute risk to endangered spec

5.1.2.3. Indirect Effects to Terrestrial- Phase CRLF through Effects to

lant toxicity e ndpoints. Since no data are av ailable to quantify the effects f dicofol to terrestrial plants, these RQ values cannot be derived and risk is presumed.

od sources for rrestrial-phase juveniles and adults. Becau se these endpoints are also being assessed lative to the potential for i ndirect effects to aquatic- a nd terrestrial-phase CRLF, the ffects determinations for indirect effects from the potential loss of food items are used as ination for poten tial effects to designated critical habitat. Habitat (plants)

Indirect effects to the CRLF via direct toxicity to terrestrial plants are estimated using the most sensitive p

o
5.1.3. Primary Constituent Elements of Designated Critical Habitat

For dicofol use, the assessment endpoints for designated critical hab itat PCEs involve a reduction and/or modification of food sources necessary for normal gr owth and viability of aquatic-phase CRLFs, and/ or a reduction and/or modifi cation of fo
te

re

e the basis of the effects determ

985.1.3.1. Aquatic-Phase

constituent elem gnated or the effects to aquatic and/or terrestria

• Alteration of c ediment ition within the stre channel or r shelter, fora g adult CRLFs. Alteration in water chemistry/quality oxygen content necessary for normal gro CRLFs and their food source.

• Reduction and/or modification of aquatic-b ased food sources for pre-metamorphs ( e.g., algae).

ck of data to quan tial eff o ay aff ect aquatic-phase PCEs d/or terrestr ial p

assessment.

The remaining aquatic-phase PCE is “altera ther chemical characteristics necessary for normal growth and viability of CR the impact of dicofol on this PCE ( i.e. , alterati freshwater fish and inverteb rate toxicity endp o vascular plants, are used as measures of effects. lculated in Section 5.1.1. Based on LOC exceedances for aquatic invertebrates to total residues of dicofol, PCEs of designated habitat related to effe chemical characteristics necessary for normal growth a nd viability of CRLFs and their food source.

5.1.3.2. Terrestrial-Phase

assessment endpoints for the terre fec

ance of upland nd areas with riparian etation or dripline surrounding aquatic a nd riparian habitat that are comprised

s and d predator avoida

ance of dispers l habitat: Upland or riparian dispersal

un its and between occupied lo cations within 0.7 mi of Three of the four assessment endpoints for the aquatic-phase primary ents (PCEs) of desi critical ha bitat f l plants: CRLF are related to potential

hannel/pond morphology or ge ometry and/or increase in s depos am pond: aquatic ha bitat (including riparian ing, predator avoidance, and aquatic vegetation) provides fo dispersal for juvenile and

• including temperature, turbidity, and wth and viability of j uvenile and adult

Based on a la tify poten l m ects of dicofol to aquatic and terrestrial of designated habitat plants, it is assumed that dicof related to effects on aquatic an later in the risk description of this lants. This assumption will be refined

on of o ti

LFs and their food source.” To assess on of food sour ces), acute and chronic ints, as well endpoi nts for aquatic nonRQs for these endpoints were ca acute and chronic exposures of fish and use of di cofol may affect aquatic-phase cts of alte ration of other

The first two strial-phase PCEs of designated critical s to terrestrial plants: habitat for the CRLF are related

• Elimination and/or disturb source of CRLFs: Upla
veg to poten tial ef t

habi tat; ability of habitat to support food in 20 0 ft of the edge of the

of gras slands, woodland CRLF shelter, forage, an

• Elimination and/or disturb habitat within designated , and/or wetl /r iparian plant species that provides the

nce

a

99each other that allow for movement be tween sites including both natural and altered sites which do not cont ain barriers to dispersal

on a lack of data to quantif strial plants, it is assumed that dicofol may affe abitat related to i ption wi

d terrestrial-phase PCE is “reducti on and/or modification of food sources for terrestrial phase juveniles and ad To assess and chronic toxicity endpoints for birds, mamm restrial invertebrates are used as measures of effects. RQs for these e ndpoints were calculated in Section 5.1.2. Based dances for acute and chronic expo restrial-phase P f food sources for terrestrial phase juveniles and adults.”

The fourth terrestrial-phase PCE is based on alteration of chemical characteristics necessary for normal growth and viability of ju source. Based on LOC exceedances for acute a nd chronic exposures of frogs to dicofol, may affect terrestrial-phase PCEs

r

.2. Risk Description

he risk description synthesizes an overall conclusion regarding the likelihood of adverse

pacts leading to an effects determination ( i.e ., “no effect,” “may affect, but not likely d

The direct and indirect effect LOCs are y affect the PCEs of the CRLF’s critical habitat. affect” ding d e 41 for direct and ted critical habitat for the CRLF. Based y potential effects of dicofol to terre ct terrestrial-phase PCEs of designated h effects on te rrestrial plants. Th of this assessment.

The thir s assum ll be refined later in the risk description

ults.” the impact of dicofol on this PCE, acute als, and ter

on LOC excee sures of frogs and mammals to dicofol, CEs of designated habitat related to use of dicofol may affect ter “reduction and/or modification o

venile and adult CRLFs and their food

use of dicofol of designated habitat related to effects of sary for normal growth and viability of alteration of other chemical cha CRLFs and their food source. acteristics neces

5

T im to adversely affect,” or “lik ely to adversely affect”) fo r the CRLF and its designate critical habitat.

exceed ed and dicofol ma Therefore, the Ag ency concludes a prel iminary “may determination for the FIFRA regulatory estimation results are provided in Tabl and in Table 42 for the PCEs of designa action regar icofol. A summary of the risk indirect effects to the CRLF

100fo l - direct and indirec

Assessment Endpoint LOC Exceedances? Descripti Table 41. Risk estimation summary for dico t effects to the CRLF.

on of Results of Risk Estimation

Aquatic-Phase CRLF (eggs, larvae, tadpo les, juveniles, and adults)

Direct Effects Survival, growth, and reproduction of CRLF individuals via direct effects on aquatic phases Yes Acute RQs exceed the LOC for exposures of aquatic-phase CRLF resu outside bui

Chronic RQ CRLF res es of dicofol, except use on Bermuda g , turf and outside buildings.

Acute and aquatic org accumulati lting from all uses of dicofol, except applications to ldings.

s exceed the LOC for exposures of aquatic-phase ulting from all us

rass

chronic RQs for aquatic-phase CRLF consuming

anisms contaminated with dicofol (resulting from on) exceed LOCs. Indirect Effects Survival, growth, and reproduction of CRLF individuals via effects to food supply ( i.e., freshwater invertebrates, non-vascular plants) yes RQ values be low the LOC for all uses.

Acute RQ invertebrat Bermuda g buildings.

Chronic R aquatic invertebrates resulting from the ma jority of dicofol uses, except atoes, Be rmuda grass, ornamentals, turf de buildings.

e RQs to outside buil h and aquatic-phase amphibians resulting.

Chronic RQs exceed the LOC fo r exposures of fish and aquatic-phase amphibians resulting from all uses of dicofol, except use on Bermuda grass, turf and outside buildings. for algae are

s exceed the LOC for exposures of aquatic es resulting from the ma jority of dicofol uses, except rass, ornamentals, turf and applications to outside

Qs exceed the LOC for exposures of

cucurbits, peppers, tom and applications to outsi

Acut for all uses of dicofol modeled, except applications dings exceed the LOC for exposures of fis

Indirect Effects Survival, growth, and reproduction of CRLF individuals via effects on habitat, cover, and/or primary productivity ( i.e., aquatic plant community) Undete rmined RQ values

No data are available to derive RQs representative of the effects of dicofol on vascular plants. for algae are be low the LOC for all uses.

Indirect Effects Un Survival, growth, and reproduction of CRLF individuals via effects to riparian determ

vegetation, required to maintain acceptable water quality and habitat in ponds and streams comprising the species’ current No data are effects of di ined available to derive RQs representative of the cofol on vascular plants.

101Assessment Endpoint LOC Excee D dances? escription of Results of Risk Estimation

range. Terrestrial-Phase CRLF (Juveniles an d adults)
Direct Effects Survival, growth, and reproduction of CRLF individuals via direct effects on terrestrial phase adults and juveniles Yes Acute and CRLF for all uses of chronic RQs exceed the LOC for terrestrial-phase dicofol.

Indirect Yes

Effects Survival, growth, and reproduction of CRLF individuals via effects on prey ( i.e., terrestrial invertebrates, small terrestrial mammals and terrestrial phase amphibians) For terrestr the LOC.

Acute RQs exceed the turf, outsid

Chronic RQ exceed the

Acute and the LOC for terrestrial-phase amphibians ial invertebrates, RQs for all uses potentially exceed

for small terrestrial mammals exposed to dicofol LOC for all uses of dicofol, except ornamentals, e building surfaces and Bermuda grass.

s for small terrestrial mammals exposed to dicofol LOC for all uses of dicofol.

chronic RQs exceed for all uses of dicofol.

Indirect Effects Survival, growth, and reproduction of CRLF individuals via effects on habitat ( i.e., riparian vegetation) Undetermined No data a e effects of di re available to derive RQs representative of th cofol on vascular plants.

Table 42. Risk estimation summary for dicofol – PC Es of designated critica l habitat for the CRLF.

Assessment Endpoint Habitat Effects? Description of Results of Risk Estim ation

Aquatic-Phase CRLF PCEs (Aquatic Breeding Habitat and Aquatic Non-Breeding Habitat) Alteration of channel/pond morphology or Undetermined No data are available to derive RQs rep geometry and/or increase in sediment resentative of the effects of dicofol on vascular plants. d eposition within the stream channel or pond: aquatic habitat (including riparian vegetation) provides for shelter, foraging, predator avoidance, and aquatic dispersal for juvenile and adult CRLFs. Alteratio includi g
content necess viability o their food s presentative

s. n in water chemistry/quality n temperature, turbidity, and oxygen ary for normal growth and ile and adult CRLFs and Undetermined No data are available to derive RQs re of the effects of dicofol on vascular plant

f juven

ource.

102Assessme Habitat Effects? Description of Results of Risk Estimation nt Endpoint

A lteration of other chemical characteristics necessary for normal growth and viability of Yes Acute and chronic RQ s for aquatic

C RLFs and their food source. dicofol (resulting from accumulation) -phase CRLF consuming aquatic organisms contaminated with exceed LOCs.

Acute RQs exceed the LOC for exposures of aquatic rity of dicofol ntals, turf and buildings.

Chronic RQs exceed the LOC for exposures of aquatic invertebrates resulting from the majority of dicofol uses, except cucurbits, peppers, tomatoes, Bermuda grass, ornamentals, turf and applications to outside buildings.

sures of fish from all s to outside

nic RQs exceed the LOC for exposures of fish and aquatic-phase amphibians resulting from all uses rass, turf and invertebrates resulting from the majo uses, except Bermuda grass, orname applications to outside

Acute RQs exceed the LOC for expo and aquatic-phase amphibians resulting uses of dicofol, except application buildings.

Chro

of dicofol, except use on Bermuda g outside buildings.Reduction and/or modification of aquaticbased food sources for pre-metamorphs (e.g., algae) Undetermined No data are available to derive RQs r of the effects of dicofol on vascular plant epresentative

s.

Terrestrial-Phase CRLF PCEs (Upland Habitat and Dispersal Habitat) Elimination and/or disturbance

abitat; ability of habitat to supp of upland

ort food urce of CRLFs: Upland areas within 200 of the edge of the riparian vegetation or ripline surrounding aquatic and riparian abitat that are comprised of grasslands, oodlands, and/or wetland/riparian plant ecies that provides the CRLF shelter, rage, and predator avoidance Undetermined No data are available to derive RQs representative of the effects of dicofol on vascular plants. h

so ft d h

w sp fo E h limination and/or disturbance of dispersal

abitat: Upland or riparian dispersal habitat ithin designated units and between ccupied locations within 0.7 mi of each ther that allow for movement between sites cluding both natural and altered sites hich do not contain barriers to dispersal Undetermined No data are available to derive RQs representative of the effects of dicofol on vascular plants.

w

o

o in

w R eduction and/or modification of food

urces for terrestrial phase juveniles and ults Yes For terrestrial inverteb rates, RQs for all uses potentially exceed the LOC.

Acute RQs for small terrestrial mammals exposed to dicofol exceed the LOC for all uses of dicofol, except ornamentals, turf, outside building surfaces so ad

103Assessment Endpoint Habitat Effects? Description of Results of Risk Estimation

an

Ch
to d Ber

ro s for s ammals exposed dico ceed th ses of dicofol.

Acute chronic RQs exceed the LOC for terrestrial-phase amphibians for all uses of dicofol. muda gras s.

mall terrestrial m

e LOC for all u nic RQ

fol ex

and

A of chemic aracteristics n for normal gro d viability of j and adult CRL d their od

s Ye Acute chroni he LOC for terrest hase CRLF l uses of dicofol.

For terrestrial inver r all uses poten xceed th

Acute for small terrestrial mammals exposed to dicofol exceed the C for all uses of dicofol, except ornamentals side building surfaces and B a grass.

Chro s for sm ammals exposed to dic ceed th r all uses of dicofol.

Acu chron eed the LOC for terrestrial-phase amphibians for all uses of dicofol. lteration al ch
ecessary wth an uvenile Fs an fo

ource. s and c RQs exceed t rial-p for al

tebra tes, RQs fo tially e e LOC.

RQs LO , turf, out ermud

nic RQ all terrestrial m ofol ex e LOC fo

te and ic RQs exc

Following a “may affect” determination, addition al information is considered to refine the potential for exposure at the predicted le vels based on the life history characteristics ( i.e. , habitat range, feeding prefer ences, etc.) of the CRLF. Based on the best available information, the Agency uses the refined ev aluation to distinguish those actions that

may affect, but are not likely to adversely a ffect” from those actions that are “likely to “ adversely affect” the CRLF and its designated critical habitat.

The criteria used to make determinations that the effects of an action are “not likely to adversely affect” the CRLF and its designated critical habitat include the following:

• Significance of Effect : Insignificant effects are those that cannot be meaningfully measured, detected, or evaluated in the c ontext of a level of effect where ‘take’ occurs for even a single individual. ‘Take’ in this context means to harass or harm, defined as the following:

 Harm includes significant habitat modification or degradation that results in death or injury to listed species by significantly impair ing behavioral patterns such as br eeding, feeding, or sheltering.

 Harass is defined as actions that create the likelihood of injury to listed species to such an extent as to si gnificantly disrupt normal behavior

104patterns which include, but are not limited to, breed ing, feeding, o sheltering. r

Likelihood of the Effect Occurring • : Discou nta ect thos e extremely unlikely to occur. Adverse Nature of Effect ble eff s are e that ar

• : Effects that holly icial t any rse ot considered adverse.

A description of the risk and effects determinat r each he es ed as ent endpoints for the CRLF and its designated critical habitat is provided below.

. Direct Effects

As discussed in the risk esti mation section, RQ all us dico cept da
g for aquatic-phase CRLFs exposed to total

r otal resi dues of dicofol to the aquatichase CRLF. The determination for all other us es of dicofol is ‘may effect’ for direct

Based on an analysis of the likelihood of i ndividual mo ons g th f acute RQs exceeding the LOC for aquatic-p RL 54-0 and u the probit dose-response of 4.5 (default assumption chan mor o CR ge f 8 individuals to 1 in 2 individuals ( Table 43 ). indic hat a ase CRLF could potentially be affe by ac xpos dico An e output calculating the analysis of the likelihood of i ndividual mo is provided in Appendix M

. are w be nef u witho adve effects are n

ion fo of t tablish sessm

5.2.1

5.2.1.1. Aquatic-Phase CRLF

s for es of fol, ex Bermu rass and outside buildings exceed LOCs

e in ation for use of dicofol on Bermuda grass and utside buildings is ‘no effect’ for direct effects of t sidues of dicofol. Therefore, the determ

o p effects of total residues of dicofol to the aquatic-phase CRLF.

rtality c Fs (0.0 iderin .97), e range o sing hase C

) , the ce of tality t This LF ran

rom 1 in 1.7x10 ates t quatic-ph ct ed ute e ures to fol. xample rtality

105Table 43. Acute RQs and fo r aquatic-phase CRLF resulting from applications of dicofol. EECs based on parent and degradates of concern. are

Use ULV application Ae ion Gro plica rial applicat und ap tion

Acute RQ 1 Chance of individual mortality

(1 in...) Acute RQ 1 nce ividua rtality in...) e RQ 1 Chance individu mortali

(1 in... Cha of ind l Acut

mo

(1 of al ty )
Beans 0.60 6 0.34 57 0.30 107 Citrus 0.85 3 0.33 66 0.25 297 Cotton 0.60 6 0.34 57 0.30 107 Cucurb it 0.23 491 0.12 58,519 0.10 294,319 Grape 0.48 13 0.25 297 0.21 84 Hops 0.56 8 0.37 38 0.35 50 Mint 0.54 9 0.31 91 0.29 129 Pepper 0.30 107 0.17 3,744 0.16 5853
Pome Fru it 0.92 2 0.39 30 0.29 129 Stone Fruit 0.45 17 0.19 1,706 0.14 16,417 Strawberry 0.97 2 0 .71 4 0.69 4
Tomato 0.26 236 0.12 58,519 0.10 294,319 Walnut/Pecan 0.76 3 0.39 30 0.34 57
Berm uda grass NA NA NA NA 0.044 1.94x10 9
Ornamentals NA NA NA NA 0.11 124,594 Turf/Sod Farm NA NA NA NA 0.054 1.71x10 8 Outside Buildings NA NA NA NA 0.0067 1.52x10 22

1 Based on 96-h LC 50 = 53 μg/L for cutthroat trout NA = not applicable

Chronic RQs for the majority of dicofol uses (all except Bermuda grass, turf and outside buildings) exceed the LOC (1.0) by factors of 1.1X to 10X, depending upon the use and

pplication method ( Table 31

- Table 33 ). EECs are sufficient to exceed a the LOAEC (7.9

i.e ., DCBP, FW152, DCBH and OH-DCBP) are equivalent to di cofol in toxicity to the aquatic-phase

RLF. This assumption adds uncertainty to the risk assessment as the actual toxicity of μg/L, based on growth effects) for the major ity of dicofol uses, with the exception of Bermuda grass, ornamentals, turf and outside buildings.

Exposures of aquatic-phase CRLF are to dicofo l are quantified in terms of total residues of dicofol. RQs are derived using the most sensitive toxicity data available for fish exposed to dicofol. It is assumed th at dicofol’s degradates of concern (

C dicofol’s degradates to the CRLF is unknown. If exposures involvi ng parent dicofol alone are considered, resulting acute RQs fo r the aquatic-phase CRLF exceed the listed species LOC (0.05) for all uses of dicofol, except Bermuda grass ornamentals, turf and outside buildings ( Table 44 - Table 46 ). Therefore, acute exposures to parent dicofol alone are sufficient to be of concern for mo rtality to the aquatic-phase CRLF. RQs for chronic exposures of the CRLF to parent dicofol alone do not exceed the LOC (1.0).

106Table 44. Acute and chronic RQs for aquatic-phas e CRLF resulting from AERIAL applications of dicofol. EECs are base d on parent dicofol only

. Peak EEC 60-day Acute Chronic

Crop (μg/L) (μg/L) RQ 1 RQ 2
Beans 3.25 0.18 0.061 3 0.040 Citrus 6.46 0.42 0.12 3 0.095 Cotton 3.48 0.29 0.066 3 0.066 Cucurbit 1.34 0.07 0.025 0.016 Grape 2.70 0.15 0.051 3 0.033 Hops 2.52 0.16 0.048 0.037 Mint 2.70 0.15 0.051 3 0.035 Pep per 1.61 0.09 0.030 0.020 Pome Fruit 6.46 0.34 0.12 3 0.077 St one Fruit 3.25 0.17 0.061 0.040 3 Strawberry 6.41 0.93 0.12 3 0.21
Tomato 1.61 0.09 0.030 0.020 Walnut/Pecan Ae rial 4.41 0.29 0.083 3 0.065
1 Based on 96-h LC 50 = 53 μg/L for cutthroat trout
2 Based on NOAEC = 4.4 μg/L for rainbow trout
3 Exceeds acute ri sk to endangere pecies LOC (RQ>0.05) d s

Tab as e CRLF resulting f ROUND ap of dic le 45. Acute and chro nic RQs for aquatic-ph ofol. EECs are ba sed on dicofol only rom G plicat ions

.

Cr Peak EEC (μg/L) 60-d (μg Acute RQ 1 onic Q 2 op ay /L) Chr R Be 2.26 0.1 0.043 8 ans 2 0.02 Ci 4.47 0.3 0.084 3 2

trus 2 0.07 Co 2.49 0.2 0.047 6 tton 5 0.05 Cu 0.0 0.018 1 curbit 0.93 5 0.01 G 1.87 0.10 0.035 023

rape 0.
H .74 0.1 0.033 8

ops 1 2 0.02
M .87 0.11 0.035 0.025

int 1
Pe 0.06 0.021 0.014

pper 1.12
Po 4.47 0.24 0.084 3 0.053 me Fruit St 0.028

one Fruit 2.25 0.12 0.042 Str 6.34 0.89 0.12 3 0.20 awberry
To 0.06 0.021 0.014 mato 1.12 3.09 0.22 0.058 3 0.050 Walnut/Pecan
B ermudagrass 0.60 0.04 0.011 0.0095 Ornamentals 1.78 0.18 0.034 0.041 Turf/Sod Farm 0.75 0.05 0.014 0.012 Outside Buidlings 0.152 0.010 0.0029 0.0023
1 Based on 96-h LC 50 = 53 μg/L for cutthroat trout
2 Based on NOAEC = 4.4 μg/L for rainbow trout
3 Exceeds acute risk to endangered species LOC (RQ>0.05)

107T able 46. Acute and chronic RQs for aquatic-ph ase CRLF resulting from ULV applications of dicofol. EECs are based on parent dicofol only.

Crop Peak EEC 60-day Acute Chronic (μg/L) (μg/L) RQ 1 RQ 2
Beans 9.75 0.1 0.52 0.18 3 2 18.02 1.03 0.34 3 0.23 Citrus Cotton 9.92 0.60 0.19 3 0.14 Cucurbit 4.04 0.21 0. 3 0. 076 04 8 Grape 8.08 0.43 0.15 3 0.1 0 Hops 7.56 0.43 0.1 0.14 3 0 Mint 8.07 0.44 0.1 0.15 3 0 Pepper 4.85 0.26 0 0.0 .091 3 59
Pom e Frui t 0.2 18.02 0.94 0.34 3 1 Stone Fruit 9.08 0.48 0.1 0.17 3 1 Straw berry 13.17 1.23 0.2 0.25 3 8
Tomato 4.85 0. 25 0. 0.05 091 3 8 Walnut/Pecan 13.02 0.72 0.1 0.25 3 6
1 Based on 96-h LC 50 = 53 μg/L for cutthroa

(RQ>0.05) t trout 2 Based on NOAEC = 4.4 μg/L for rainbow trout
3 e risk to endangered species LOC Exceeds acut

Aquatic EECs account for direct toxicity to the CRLF through contact with dicofol nd its degradates ncern are expected to partition to aquatic F can also be exposed to dicofol and its inated prey items. Acute and chronic RQ values enerated using KABAM ( Table 35 ) are above LOCs, indicat ing that exposure of

-REX calculated acute dose-based RQs, acute dietary-based RQs and chronic dietaryased RQs exceed their respective LOCs, resulting in a “may affect” determination for all ses. In order to explore in fluences of amphibian-specif ic food intake equations on otential dose-based and dietary-based exposures of the terrest rial-phase CRLF to dicofol, T-HERPS is used. Modeling with T- HERPS incorporates the same application rates, intervals and number of applications for each use as defined for modeling using TREX ( Table 19 ). Since applications of dicofol for all uses result in exposures sufficient to exceed the LOC for direct effects to the te rrestrial-phase CRLF, the T-HERPS model was used to estimate EECs and subsequent ri sks to the terrestrial-phase CRLF based on amphibian-specific equations. These refine d EECs and RQs were used to distinguish present in the water column. Given the high Log Kow of dicofol (>6) a of concern (>4) , dicofol and its residues of co se CRL organisms. Therefore, the aquatic-pha

sidues through consumption of contam re g aquatic-phase CRLF to dicofol through consum ption of aquatic organisms which have accumulated dicofol is of concern for the CRLF.

Based on the above information, for all uses of dicofol, except Bermuda grass and outside buildings, the effects determination for dire ct effects to the a quatic-phase CRLF is “LAA” based on potential acute mortality and ch ronic growth effects. The determination for use of dicofol on Bermuda grass and outside buildings is “no effect” for direct effects of total residues of dicofol to the aquatic-phase CRLF.

5.2.1.2. Terrestrial-Phase CRLF

T b

u p

108“NLAA” and “LAA” determinations. An example output from T-HERPS is available in Appendix N

.
RQs are calc d for the terrestrial CR t d t. I be noted that although dietary- base alu c y do er do not take into acco imals at depending on the forage item animal has to if g nu lev the food item. If di adjusted to acc fo r d ntia consum n, the ad would likely approximate the dose-based RQ value.

res

Refined dose-based RQs for small sized ( 1.4 F consuming insects do not e the acute listed species LOC (0.1) for dicofol ( Table 47 ).

Table 47. Refined dose-based RQs for 1.4 g CRLF consuming differe nt food items. EECs calculated using T-HERPS.
Use Small Insects Large Insects ulate -phase d RQ v L F on

es are he basis of onsider abl ose and die lower than t should se-based

consume RQ values, the form differing amo unt that d ifferent-sized a n , an unts of food and th consume varying amounts due to d ferin tr ition els in etarybased RQ values are ount iffere l food ptio justed RQ value

Acute exposu

g) CRL xceed

7

Citrus, 1 Pome Fruits 2 0.06 0.01 Strawberries, Walnuts (English/black), Pecans 0.04 <0.01 Beans, cotton, Stone Fruits 3 0.03 <0.01 Grapes, mint 4 0.02 <0.01 Hops 0.02 <0.01 Peppers, Tomatoes 0.01 <0.01 Cucurbits 5 0.01 <0.01 Ornamentals, 6 Turf grasses, Sod farms, Outside building surfaces 0.01 <0.01
Bermuda grass 0.01 <0.01

1 grapefruit, lemons, oranges, tangelos, and tangerines
2 apples and pears
3 apricots, cherries, nectarines, peaches, plums, and prunes
4 mint, peppermint and spearmint
5 cantaloupes, cucumbers, melons, pumpkins, watermelons, and winter and summer squash
6 nurseries and flowers
7 Based on LD 50 = 265 mg/kg-bw (for ring-necked pheasant)

R efined dose-based RQs for medium-sized (37 g) CRLF consuming small herbivorous

ammals exceed the acute listed species LOC ( 0.1) for all uses of dicofol. RQs exceed e LOC by factors of 2.3 to 16.9x. Based on an analysis of the likelihood of individual ortality considering the rang e of acute dose-based RQs fo r medium terrestrial-phase RLFs consuming small herbivore mammals (0.23-1.69), and using the default probit dose-response of 4.5, the chance of mortality to these CRLF range from 1 out of 491 individuals to 100%. RQs fo r medium-sized CRLF consuming insects and terrestrialphase amphibians do not exceed the acute listed species LOC ( Table 48 ). This indicates that medium-sized CRLF could potentially be affected by acute exposures to dicofol. m th

m C

109Table 48. Revised dose-based RQs 7 for 37 g CRLF consuming differe nt food items. EECs calculated using T-HERPS.

Use Insects Insects Mammals Insecti Mammals Am Small Large Small Herbivore Small

vore SmallTerrestrialphase phibians Citrus, 1 Pome Fruits 2 0.06 0.01 1.69 8 0.11 8 <0.01 Strawberries, Walnuts ( English/black), Pecans 0.04 <0.01 1.13 8 0.07 <0.01

Beans , cotton, St one Fruits 3 0.03 <0.01 0.85 8 0.05 <0.01 Grapes, mint 4 0.02 <0.01 0.71 8 0.04 <0.01 Hops 0.02 <0.01 0.66 8 0.04 <0.01 Peppers, Tomatoes 0.01 <0.01 0.42 8 0.03 <0.01 Cucurbits 5 0.01 <0.01 0.35 8 0.02 <0.01 Ornamentals, 6 Turf grasses , Sod farms, Outside building surfaces 0.01 <0.01 0.28 8 0.02 <0.01
Bermuda grass 0.01 <0.01 0.23 8 0.01 <0.01

1 grapefruit, lemons, oranges, tangelos, and tangerines
2 apples and pears
3 apricots, cherries, nectarines, peaches, plums, and prunes rmint 4 mint, peppermint and spea
5 cantaloupes, cucumbers, melons, pumpkins, wa termelons, and winter and summer squash

50 easant)
8 Exceeds acute endangered species LOC (RQ>0.1) 6 nurseries and flowers
7 Based on LD = 265 mg/kg-bw (for ring-necked ph

Refined dose-based RQs for large-sized ( 238 g) CRLF consuming small, herbivore mammals are exceeded for some uses of dicofol ( Table 49 ). Based on an analysis of the likelihood of individual mortality consider ing the range of acute dose-based RQs exceeding the LOC for large terrestrial-phase CRLFs consuming small herbivore mammals (0.10-0.26), and using th e default probit dose-respons e of 4.5, the chance of mortality to these CRLF range from 1 in 294,319 individuals to 1 in 236 individuals. RQs for large-sized CRLF consuming insects and terrestrial-phase amphibians do not exceed the acute listed species LOC ( Table 49 ). This indicates that large-sized terrestrialphase CRLF could potentially be affected by acu te exposures to dicofol resulting from several uses.

110T able 49. Revised dose-based RQs 7 for 238 g CRLF consuming different food items. EECs calculated

Use Small Insects Large Insects Small Herbivore Small Insecti llTerrestrialusing T-HERPS.

Sma

Mammals vore Mammals phase Amphibians Citrus, 1 Pome Fruits 2 0.04 <0.01 0.26 8 0.02 <0.01 Strawberries, Waln Pecans uts (English/black), 0.03 <0.01 0.18 8 0.01 <0.01
Beans, cotton, Stone Fruits 3 0.02 <0.01 0.13 8 0.01 <0.01 Grapes, mint 4 0.02 <0.01 0.11 8 0.01 <0.01 Hops 0.01 <0.01 0.10 8 0.01 <0.01 Peppe rs, Tomat oes 0.01 <0.01 0.07 <0.01 <0.01 Cucurbits 5 0.01 <0.01 0.05 <0.01 <0.01 Ornament ls, 6 Turf a Outside buil grasses, Sod farms,
g din surfaces 0.01 <0.01 0.04 <0.01 <0.01
Bermuda grass 0.01 <0.01 0.04 <0.01 <0.01

1 ons, orang grapefruit, lem
2 apples and pea es, tangelos, and tange

nes
and winter and summer squash rines

rs 3 apricots, cherries, nectarines, peaches, plums, and pru
4 mint, peppermint and spearmint
5 cantaloupes, cucumbers, melons, pumpkins, watermelons,
6 nurseries and flowers
7 Based on LD = 265 mg/kg-bw (for ring-necked pheasant) 50 8 Exceeds acute endange red species LOC (RQ>0.1)

R

m

efined acute dietary-based RQs for CRLFs consuming small insects and herbivorous ammals exceed the acute listed species LO C (0.1) for most uses of dicofol (the excepti . Based on an analysis of the

kelihood of individual mortality considerin g the range of acute dietary-based RQs ons include ornamentals, turf and Berm uda grass) li exceeding the LOC for terrestrial-phase CRLFs consuming small herbivore mammals (0.11-0.53), and using the prob it dose-response of 5.92 ( Table 27 ), the chance of mortality to these CRLF range from 1 in 1.4x10 8 individuals to 1 in 19 individuals. For CRLFs consuming large insects, terrestrial -phase amphibians and small insectivorous mammals, the acute LOC is not exceeded for any use ( Table 50 ). This indicates that

RLF could potentially be affected by acute exposures to dicofol. C

111Table 50. Re RLF consuming different food items. EECs lculated using T-HERPS.

-

s vised acute dietary-based RQs 7 for C

ca

Use Small Insects Large Insects Small Herbivore Mammals Small Insectivore Mammals Small Terrestrial phase Amphibian

s, 1 Pome Fruits 2 0.45 8 0.05 0.52 8 0.03 0.02 Citru Straw Pecans 0.30 8 0.03 0.35 8 0.02 0.01 berries, Walnuts (English/black),

Bean 0.01 s, cotton, Stone Fruits 3 0.22 8 0.02 0.26 8 0.02 Grap 0.01 es, mint 4 0.19 8 0.02 0.22 8 0.01 Hops 17 8 0.02 0.20 8 0.01 0.01 0. Peppers, Tomatoes 8 0.11 0.01 8 0.13 0.01 <0.01 Cucurbits 5 0. 0.01 0.01 <0. 09 0.11 8 01 Ornamentals, 6 Turf gras m Outside building surfaces ses, Sod far s, 0.07 0.01 0.09 0.01 <0.01

Berm rass 0.01 <0.01 01 uda g 0.06 0.07 <0.

1 grap mons, oranges, t s, and ta nes
2 appl ears
3 apri ries, nectarines es, plum prunes
4 mint nt and spearm
5 cant cumbers, me mpkins rmelon nter an er squa
6 nurs flowers
7 Bas C 50 = 905 ppm (f nese qua
8 Exc ute endangered sp OC (RQ>0.1) efruit, le angelo ngeri es and p cots, cher , peach s, and , peppermi aloupes, cu int lons, u p , wate s, and wi d summ sh eries and ed on L or Japa il) eeds ac ecies L

Chronic exposures

R chronic diet ased R r CR ceed hronic specie C ( ses of ol and all foo s pote y cons ( the a ble chr study r e American kestrel were exposed to d NOAEC s 1 ppm nd th e EC wa ppm, on de d

e ess. C arison e LOA directly hroni c dietary-based EECs all u suffic to effects were observed in the laboratory. ved effects to egg shells to represent ction of the CRLF, since the CRLF does not produce eggs with shells. other chronic studies with birds, decreased number of eg gs laid was observed in ring efined ary-b Qs fo L Fs ex the c listed s LO 1.0) for all u dicof for d item ntiall umed by the CRLF Table 51 ). In vaila onic whe icofol, the wa , a LOA s 3 based crea se ggshell thickn omp of th E C to c f ming food i indicate that EECs for oductive or CRLF consu all tems ses are ient exceed the concentration where repr There is some uncertainty in relying upon obser effects to reprodu In doves and American kestrel feed 40 ppm dicofol. EECs from all uses of dicofol for CLRF consuming small insects and small herbivore mammals are still sufficient to exceed this level where decreased number of o ffspring was observed in birds.

Based on the above information, for all uses of dicofol, the effects determination for chronic effects to the terre strial-phase CRLF is “LAA” based on potential reproductive effects.

112Table 51. Revised chro nic dietary-based RQs 7 for CRLF consuming di fferent food items. EECs calculated using T-HERPS.

Use Small Insects Insects S Herbivore Mammals In re Mammals llstrialase ibians Large mall Small sectivo Sma Terre ph Amph
Citru ruits 2 405 8 4 47 .1 8 s, 1 Pome F 5.0 8 4 8 30.0v 14 Straw Walnuts (English/black), Pecan 270v 3 31 8 berries,

s 0.0 8 6 8 1938 8 9.37
Bean , Stone Fruits 3 203 8 2 23 8 s, cotton 2.5 8 7 8 14.8 8 7.03 Grape 169 8 1 19 s, mint 4 8.8 8 8 8 8 12.4 8 5.86 Hops 157 8 1 18 8 7.5 8 4 8 11.5 8 5.46 Peppe 101 8 1 11 8 rs, Tomatoes 1.2 8 9 8 7.41 8 3.51 Cucu 84.4 8 9 98 8 rbits 5 .38 8 .8 8 6.18 8 2.93 Ornam f grasses, Sod farms, Outsi 67.5 8 7 79 8 entals, 6 Tur g surfaces de buildin .50 8 .1 8 4.94 8 2.34

Berm 54.0 8 6 63 8 uda grass .00 8 .3 8 3.95 8 1.87

1 grap s 2 appl
3 apr prunes 4 min ppermint and spearmint
5 can 6 nur 7 Based on NOAEC = 1 ppm (for American kestrel)
8 Exceeds chronic risk LOC .0) efruit, lemons, oranges, tangelos, and tangerine es and pears ots, cherries, nectarines, peaches, plums, and ic t, pe taloupes, cucumbers, melons, pumpkins, watermelons, and winter and summer squash series and flowers

(RQ>1

)

As discussed in Section 2.5.3, the diet of ta e CRL com prim of unicellular nonvascular aquatic plants and de tritus. Juvenile CRLF consume ily aquatic and terrestrial invertebrates. The diet of adult CRLF is com f aq d terrestrial invertebrates, fish, frogs and mice. These prey groups are considered in d indirect effects to the CRLF caused by direct effects to its prey.

.2.1. Algae (non-vascular plants

RQ values for algae are below the LOC for a es of ol. T sults in a “no

e ination for indi rect effects to t RLF d 5.2.2. Indirect Effects (through effects to prey

dpol F is posed arily primar posed o uatic an

etermining

5.2 )

ll us dicof his re ffect” determ he C due to exposures of algae to icofol.

1135.2.2.2. Aquatic Invertebrates

Based on an analysis of the lik elihood of ind rta ng a Qs f c invertebrates and a probit dose-response of 4 fault like of in ual mortality for each use is available in Table 52

. on t alysi uses o fol result in less than or equal to a 3% chance of ef to an i dual inve tes representing prey of the CRLF.

Table 52. Acute RQs and associated likelihood of indiv effects uatic ate r g from applications of dicofol. EECs are based on parent a rada ncern ULV application Ae pplicat pl ividual mo

e lity usi ) cute R or aquati .5 (d , the l ihood divid Based f his an s, all f dico

ects ndivi aquatic rtebra

idual for aq invertebr s esultin nd deg tes of co

. rial a ion Ground ap ication

Use Acute RQ 1 Likelihood of individual acute effect (%) Acut Like

indi acute effect ( A 1 Likelihood

individual acute effect e RQ 1 lihood of vidual

%) cute RQ of

(%)
Beans 0.23 3 0.2 0.13 3 <0. 1 0.11 3 <0.1 Citrus 0.32 3 1.3 0.12 3 <0.1 0.093 3 <0.1
Cotton 0.23 3 0.2 0.13 3 <0.1 0.11 3 <0.1
C ucurbit 0.087 3 <0.1 0.045 <0.1 0.039 <0.1 Grape 0.18 3 <0.1 0.094 3 <0.1 0.081 3 <0.1 Hops 0.21 3 0.1 0.14 3 <0.1 0.13 3 <0.1
Mint 0.21 3 0.1 0.12 3 <0.1 0.11 3 <0.1 Pepper 0.11 3 <0.1 0.064 3 <0.1 0.059 3 <0.1 Pome Fruit 0.35 3 2.0 3 3 0.15 <0.1 0.11 <0.1
St one Fruit 0.17 071 3 <0.1 0.054 3 <0.1 3 <0.1 0. Strawberry 0.37 3 2.6 0.27 3 0.5 0.26 3 0.4
Tomato 0.10 3 <0.1 0.045 <0.1 0.037 <0.1 Walnut/Pecan 0.29 3 0.8 0.15 3 <0.1 0.13 3 <0.1 Bermuda grass NA NA NA NA 0.016 <0.1 Ornamentals NA NA NA NA 0.044 <0.1 Turf/Sod Farm NA NA NA NA 0.021 <0.1 Outside Buildings NA NA NA NA 0.0025 <0.1

1 B ased on 48-h EC 50 = 140 μg/L for daphnid.
2 Based on NO
3 Exceeds acu

A = not applicable

cept cucurbits, peppers, tomatoes, Bermuda entals, turf and outside buildings ( Table 53 - Table 55 ). Chronic exposures of dicofol parent are insufficient to exceed the LOC (1.0). AEC = 19 μg/L for amphipod. te risk to endangered species LOC (RQ>0.05) N

Exposures of aquatic invertebrates to dicofol are quantified in terms of total residues of dicofol. RQs are derived using the most sensitive toxicity data available for aquatic invertebrates exposed to dicofol. It is a ssumed that dicofol’s degradates of concern (i.e

., DCBP, FW-152, DCBH and OH-DCBP) are equivale nt to dicofol in to xicity to aquatic invertebrates. This assumption adds uncertainty to the risk assessment, the toxicity of dicofol’s degradates to aquatic inverteb rates is unknown. If exposures involving dicofol only are considered, acute RQs for the aqua tic invertebrates CRLF exceed the listed ecies LOCs (0.05) for all dicofol uses, ex sp grass, ornam

114Table 53. Acute and chro c invert om AERI nic RQs for aquati n dicofol only. ebrates resulting fr AL applications o f dicofol. EECs are ba sed o
Crop Peak E L Acute
1 EC ) 21-day (μg/L) (μg/ RQ Chronic RQ 2
Bean s 3 3.25 0.46 0.02 0.024 Citrus 6. 46 .97 46 51 0 0.0 0.0 Cotton 3. 48 .64 25 34 0 0.0 0.0 Cucurbit 34 .19 10 10 1. 0 0.0 0.0 Grape 2. 70 38 19 0 0. 0.0 0.02 Hops 2. 52 .38 18 20 0 0.0 0.0 Mint 2. 70 .39 19 20 0 0.0 0.0 Pepper 61 .23 12 12 1. 0 0.0 0.0
Pome Fru it 46 90 46 8 6. 0. 0.0 0.04 Stone Fruit 3. 25 .46 23 24 0 0.0 0.0 Strawberry 6. 41 .76 46 2 1 0.0 0.09
Tomato 1. 61 23 12 12 0. 0.0 0.0 Walnut/P ecan Aerial 41 66 31 5 4. 0. 0. 0 0.03
1 Based on 48-h EC
2 50 = 1 /L for dap . = 19 for amph 40 μg hnid Based on NOAEC μg/L ipod.

Table 54. Acute and chr RQs for aquatic inver tes resu from G appl d a sed icofol onl
Peak EEC (μg/L) 21-day (μg/L) Acute RQ 1 Chronic RQ 2 onic t ebra lting ROUND ications of icofol. EECs are b on d y.
Crop

B eans 2.26 0.32 0.016 0.017 Citrus 4.47 0.69 0.032 0.036 Cotton 2.49 0.51 0.018 0.027 Cucurbit 0.93 0.13 0.0067 0.0069 Grape 1.87 0.27 0.013 0.014 Hops 1.74 0.27 0.012 0.014
M int 1.87 0.27 0.013 0.014 Pepper 1.12 0.16 0.0080 0.0084 Pome Fruit 4.47 0.63 0.032 0.033 St one Fruit 2.25 0.32 0.016 0.017 Strawberry 6.34 1.62 0.045 0.085 Tomato 1.12 0.16 0.0080 0.0083 Walnut/Pecan 3.09 0.48 0.02 2 0.025 Bermuda grass 0.60 0.10 0.0043 0.0054 Ornamentals 1.78 0.39 0.013 0.020 Turf/Sod Farm 0.75 0.13 0.0053 0.0067 Outside Buildings 0.152 0.025 0.0011 0.0013
1 Based on 48-h EC = 140 μg/L for daphnid. 50 2 Based on NOAEC = 19 μg/L for amphipod.

115Table 55. Acute and chronic RQs for aquatic inve rtebrates resulting from ULV applications of dicofol. EECs are ba sed on dicofol only.
Crop Peak EEC (μg/L) 21-day (μg/L) Acute RQ 1 Chronic RQ 2
Beans 9.75 1.38 0.070 3 0.073 Citrus 18.02 2.58 0.13 3 0.14 Cotton 9.92 1.49 0.071 3 0.079 Cucurbit 4.04 0.56 0.029 0.030 Grape 8.08 1.14 0.058 3 0.060 Hops 7.56 1.08 0.054 3 0.057 Mint 8.07 1.15 0.058 3 0.060 Pepper 4.85 0.69 0.035 0.036 Pome Fruit 18.02 2.52 0.13 3 0.13 Stone Fruit 28 0.06 7 9.08 1. 5 3 0.06 Strawberry 13.17 0.094 3 2.70 0.14
Tomato 4.85 0.68 0.035 0.036 Waln ut/Pecan 0. 3 13.02 1.85 093 0.097
1 Base d on 48-h EC 50 = 140 μg/L for daphnid. 9 μg/L for amphipod. (RQ 2 Based on NOAEC = 1
3 Exceeds acute risk to endangered species LOC >0.05)

C tal residues of dic r the ty of ol use but cucurbits, peppers, tomatoes, Bermuda grass entals, turf and outside buildings) are sufficient to exceed the LOC (1.0). For ULV ation cofol on, po ruit,

s walnuts/pecans, EECs ar e ient t ed th EC ( /L) for chronic effects to aquatic invertebrates.

Based on the above information, the imp CRLFs via acute effects on aquati c invertebrates is discountable for all uses of dicofol. T bits, peppers, tomatoes, Bermuda grass,

o and outside buildings) have the pot ential to result in chronic exposures
t especially when dicofol is applied via U

5.2.2.3. Fish and Aquatic-Phase Amphibians

Based on an analysis of the likelihood of i ndividual mortality cons idering the range of acute RQs exceeding the LOC for fish a nd aquatic-phase amphibians (0.05-0.71), and

sing the probit dose-response of 4.5 (defau lt assumption), likelihood of individual

lt in ss than a 10% chance of effects to an i ndividual fish and aquatic-phase amphibians representing prey of the CRLF.

hronic RQs based on to ofo l fo majori dicof s (all

, ornam app lic s of di to cott me f trawberries, and suffic o exce e LOA 33 μg

act of the indirect effects to aquatic-phase

he majority of dicofol uses (all but cucu r rnamentals, turf hat may result in effects to aquatic invertebra tes,

LV methods.

u mortality for each use is available in Table 56

. Based on this analysis, use of dicofol on beans, citrus, cotton, hops, mint, pome fruit, strawberries and walnuts/pecans results in greater than a 10% likelihood of individual mortality. All other uses of dicofol resu le

116Table 56. Acute RQs and likelihood of individual mortality for fish and aquatic-phase amphibians resulting from applications of dicofol. EECs are based on parent and degradates of concern. ULV application Aerial application Ground application

Use Acute RQ 1 Likelihood of individual

mortality (%) Acute RQ 1 Likelihood of individual

mortality (%) Acute RQ 1 Likelihood of individual mortality (%)
Beans 0.60 16 0.34 1.8 0.30 0.9 Citrus 0.85 38 0.33 1.5 0.25 0.3 Cotton 0.60 16 0.34 1.8 0.30 0.9 C ucurbit 0.23 0.2 0.12 <0.1 0.10 <0.1 Grape 0.48 7.6 0.25 0.3 0.21 0.1 Hops 0.56 13 0.37 2.6 0.35 2.0 Mint 0.54 11 0.31 1.1 0.29 0.8 Pep 0.30 0.9 0.17 0.1 per < 0.1 6 <0.1 Pome Fruit 0.92 44 0.39 0.29 3.3 0.8 Sto 45 5.9 0.19 <0.1 ne Fruit 0. 0.1 0. 14 Stra 0.71 23 wberry 0.97 48 25.2 0. 69 Tom 0.4 0.12 <0.1 0. <0.1 ato 0.26 10
Wa 0.76 30 0.39 1.8 lnut/Pecan 3.3 0. 34 Ber rass NA NA NA 0. <0.1 muda g NA 044 Orn NA NA NA NA 0. <0.1 amentals 11
Tur NA NA NA NA 0. <0.1 f/Sod Farm 054 Out 0.0 <0.1 side Buildings NA NA NA NA 067
1 Bas LC = 53 μg/L for cutthroat trout NA =

Chronic RQs for fish and aquatic-phase am or the majority of dicofol uses (all

exce ceed the LOC (1.0) by factors of 1.1X cient to exceed the LOAEC (7.9 μg/L, based on growth e ffects) for the majority of dicofol uses, with ntals, turf and outside buildings.

e acute risk LOC (RQ> ed on 96-h 50

not applicable

phibi ans f outside buildings) ex pt Bermuda grass, turf and to 10X, depending upon the use ( Table 31 - Table 33 ). EECs are suffi

the exception of Bermuda grass, or name

5.2.2.4. Terrestrial Invertebrates

As noted above, for small insect exposures, RQ values range < 1.04 to <0.138. For large insect exposures, RQ values range <0.115 to <0.0153. For all uses of dicofol, RQ values

otentially exceed th p 0.05) for terrestrial insects. Because the
te he

t LD 50 used in deriving RQs for terrestrial inve rtebrates is not quantified, RQs for acu exposures of small and large terr estrial invertebrates to dicofol potentially exceed t LOC of 0.05 for all uses.

Based on an analysis of the likelihood of i ndividual mortality cons idering the range of acute RQs potentially exceeding the LOC ( 0.05 to <1.04), and using the default probi dose-response of 4.5, the chance of mortality to terrestr ial invertebrates range from less than 0.1% to 53% ( Table 57 ). For use of dicofol on grapes, mint, hops, peppers, tomatoes, cucurbits, ornamentals, turf and Be rmuda grass, dicofol exposures result in a

117c hance of individual mortality to less than 10% of terrestrial insects. Therefore, indirect

s 7 and associated likelihood of individual effects to terrestrial invertebrates due to icofol exposures. effects to the CRLF through poten tial effects to terrestrial invertebrates resulting from these dicofol uses are considered discountab le. Use of dicofol on citrus, pome fruits, strawberries, walnuts, pecans, beans, cotton and stone fruits could potentially result in indirect effects to greater th an 10% of small invertebrates. Although there is uncertainty in the actual effects of these exposures to terrestrial invertebra tes, given that no LD 50 was established, mortality to small insects resul ting from dicofol applied to these crops has the potential to result in indirect effects to the CRLF, especially considering that dicofol is intended for control of insects.

Table 57. RQ d
Sma ll Insect Large Insect

Use RQ Likelihood of individual acute effect (%) RQ acute effect (%) Likelihood of individual

Citrus, 1 Pome Fruits 2 <1.04 <53.10 <0.12 <0.1 Strawberries, Walnuts (English/black), Pecans <0.69 <23.40 <0.08 <0.1
Beans, cotton, Stone Fruits 3 <0.52 <10.10 <0.06 <0.1

Gra pes, mint 4 <0.43 <4.95 <0.05 <0.1 Hops <0.40 <3.67 <0.04 <0.1 Peppers, Tomatoes <0.26 <0.42 <0.03 <0.1

Cucurbits 5 <0.22 <0.15 <0.02 <0.1 Ornamentals, 6 Turf grasses, Sod farms, Outside building surfaces <0.17 <0.1 02 1 <0. <0.

Berm <0.14 <0.1 .02 1 uda grass <0 <0. 1 gr es apefruit, lemons, oranges, tangelos, and tangerin 2 ap ples and pears 3 ap hes, plums, and prunes ricots, cherries, nectarines, peac 4 m nd spearmint int, pep permint a 5 ca melons, pumpkins, watermelons, and winter and s r squash ntaloupes , cucumbers, umme 6 nu rseries and flowers 7 Ba >391 μg a.i./g for honey bee sed on LD 50

RQ 0.1) for all uses of dicofol except: ornamentals, tu rf, outside buildings and Bermuda grass ( Table ). fol to terrestrial mammals. 5.2.2.5. M ammals

values representing acute exposures to te rrestrial mammals exceed the LOC (

58 Therefore, there is potential for acute effects of dico

118Based on an analysis of the likelihood of individual mortality using acute dose-based RQs for terrestrial mam mals and a probit dose-response of 4.5 (default value), the

kelihood of individual mortality for each use is available in Table 58

. Based on this

able 58. Acute dose-based RQs and associated like lihood of individual effects to small terrestrial

dose-based 7 individual acute eff li analysis, the majority of dicofol uses result in less than a 10% chance of effects to an individual terrestrial mammal representing pr ey of the CRLF. Only the highest RQ (from citrus and pome fruits) result in es timations of likelihood of individual effects which represents a significant indirect effect to the CRLF (10.7%). Th erefore, the impact of the indirect effects to terrestrial-phas e CRLFs via acute effects on small mammals is discountable for all uses of dicofo l, except citrus and pome fruits.

T mammals (consuming short grass) due to dicofol exposures.

Use Acute, Likelihood of

ect (%) Citrus, 1 Pome Fruits 2 0.53 10.7 Strawberries, Walnuts (English/black), Pecans 0.35 2.0 Beans, cotton, Sto ne Fruits 3 0.27 0.5 Grapes, mint 4 0.22 0.2 Hops 0.21 0.1 Peppers, To matoes 0.13 <0.1
Cu curbits 0.11 <0.1 5 Ornamentals, 6 T urf grasses, Sod farms, Outside building 0.09 <0.1 surfaces Bermuda grass 0.07 <0.1 1 grapefruit, lemons, oranges, tangelos, and tangerines 2 apples and pears ries, nectarines, peaches, plums, and 3 apricots, cher prunes
and winter and summer squash 4 mint, peppermint and spearmint ons, pumpkins, watermelons, 5 cantaloupes, cucumbers, mel 6 nurseries and flowers
7 aboratory rat = 587 mg/kg. Based on LD 50 for l

s fo r terrestrial mammals exceed the LOC (1.0) y factors of 19X to 781X, depending upon the use ( Table 40 ). EECs are sufficient to

ures of terrestrial animals to pesticides rough consumption of foliar surfaces of cr ops and insects on the treated site. The model ial animals resulting from ulated the pesticide in their D ose-based and dietary-based chronic RQ b exceed the LOAEC (25 ppm, based on reproductive effects) for all uses by factors of 4X or greater. Based on this information, chronic exposures of dicofol from all uses have the potential to indirectly affect the CRLF via impacts to terrestrial mammals serving as potential prey items.

he T-REX model is useful for assessing expos T th cannot be used to assess pesticide expos ures to terrestr ption of soil dwelling invertebrates wh ich have accum consum ti ssues. In order to explore the potential exposures of mammals to total residues of dicofol that have accumulated in earthworms inhabiting dicofol treatment sites, a simple fugacity approach was employed to estimate dicofol concentrations in earthworms and subsequent exposures to mammals consuming ear thworms. This approach is explained in detail in Appendix O

.
119Based on PRZM estimated dicofol concentrations of 10 and 0.16 g/m3 in soil and soil pore water, respectively ( Figure 9 and Figure 10 ), the estimated concentration of dicofol in earthworms is 2914 ppm. This transl ates to a dose -based EEC of 2778 mg/kg-bw,

hich exceeds the LD 50 for rats of 587 mg/kg-bw. If it is assumed that a 20g mammal

Table 59 7

consuming gs consuming w consumes only earthworms, its chronic diet ary based and dose-based exposures would be approximately 100X and 1000X, re spectively, above levels where reproductive effects were observed in rats (25 ppm, MRID 41606601). Therefore, acute and chronic exposures of small mammals to dicofo l through consumption of contaminated earthworms from fields treated with dicofol have the potential to result in effects to mammals.

5.2.2.6. Terrestrial-Phase Amphibians

In order to explore influen ces of amphibian-specific food intake equations on potential dose-based and dietary-based exposures of amph ibians (prey of CRLF) to dicofol, the THERPS model is used. The Pacific tree frog ( Hyla regilla ) is used to represent the amphibian prey species. The weight of the animal is assumed to be 2.3 g, and its diet is assumed to be composed of small and large insects. For frogs consuming small and large insects, the acute LOC (0.1) is not exceeded for dicofol ( Table 59 ).

. Acute dose-based RQs for terrestrial-phase frogs (prey) exposed to dicofol. Use Frogs Fro

Small Insects Large Insects Citrus, 1 Pome Fruits 2 0.04 <0.01 Strawberries, Walnuts (English/black), Pecans 0.04 <0.01 Beans, cotton, Stone Fruits 3 0.03 <0.01
Gr apes, mint 4 0.02 <0.01
Ho 0.02 <0.01 ps Peppers 0.01 <0.01 , Tomatoes Cucurbits 0.01 <0.01 5 Ornamentals, 6 Turf grasses, Sod farms, Outside building surfaces 0.01 <0.01 Bermuda grass 0.01 <0.01 1 grapefruit, lemons, oranges, tangelos, and tangerines 2 apples and pears 3 apricots, cherries, nectarines, peaches, plums, and prunes 4 mint, peppermint and spearmint 5 cantaloupes, cucumbers, melons, pumpkins, watermelons, and winter and summer squash 6 nurseries and flowers 7 Based on LD 50 = 265 mg/kg-bw (for ring-necked pheasant)

Acute dietary-based RQs for the CRLF, which do not account for the weight of the animal being assessed, can also be used to assess risks to the terrestrial frog prey ( Table 50 ). For frogs which consume small insects, RQs exceed the acute LOC (0.1) for the majority of dicofol uses, with the exception of use on cucurbits, orname ntals, turf, outside

120buildings and Bermuda grass. For frogs whic h consume large insects, the acute LOC is not exceeded for dicofol.

Based on an analysis of the li kelihood of individual mortal ity using acute dietary-based RQs for terrestrial amphibians and a prob it dose-response of 5.92, the likelihood of individual mortality for each use is available in Table 60

. Based on this analysis, all uses of dicofol result in ≤ 2% chance of effects to an individual terrest rial amphibian representing prey of the CRLF. Therefore, th e impact of the indirect effects to terrestrialphase CRLFs via acute effects on terrestrial amphibians is discountable for all uses of dicofol.

Table 60. Acute dietary-based RQs for terrestrial- phase frogs (prey) consuming small insects and likelihood of individual effects chance resulting from dicofol ex posures. RQs calculated using THERPS.

Use Acute, dietarybased RQ 7 Likelihood of individual acute effect (%) Citrus, 1 Pome Fruits 2 0.45 2.0 Strawberries, Walnuts (English/black), Pecans 0.30 0.1 Beans, cotton, Stone Fruits 3 0.22 <0.1 Grapes, mint 4 0.19 <0.1 Hops 0.17 <0.1 Peppers, Tomatoes 0.11 <0.1 Cucurbits 5 0.09 <0.1 Ornamentals, 6 Turf grasses, Sod farms, Outside building surfaces 0.07 <0.1 Bermuda grass 0.06 <0.1 1 grapefruit, lemons, oranges, tangelos, and tangerines 2 apples and pears 3 apricots, cherries, nectarines, peaches, plums, and prunes 4 mint, peppermint and spearmint 5 cantaloupes, cucumbers, melons, pumpkins, watermelons, and winter and summer squash 6 nurseries and flowers 7 Based on LC 50 = 903 ppm (for Japanese quail)

Chronic dietary-based RQs fo r the CRLF, which do not account for the weight of the animal being assessed, can also be used to assess risks to the terrestrial frog prey ( Table 51). Chronic RQs for the frog exceed the LOC (1.0) by factors ranging from 2X to 474X. Therefore, for all dicofol uses, there is poten tial for indirect effects to the CRLF resulting from chronic effects to terrestrial amphibians.

5.2.3. Indirect Effects (through effects to habitat)

quatic plants serve several important functio ns in aquatic ecosystems. Non-vascular quatic plants are primary producers and provide the autocht honous energy base for A

a aquatic ecosystems. Vascular plants provide structure as attachment sites and refugia for many aquatic invertebrates, fish, and juvenile organisms, such as fish and frogs. In

121addition, vascular plants also provide pr imary productivity and oxygen to the aquatic ecosystem. Rooted plants help reduce se diment loading and provide stability to nearshore areas and lower streambanks. In addition, vascular aquatic plants are portant as attachment site s for egg masses of CRLFs.

addition to providing habitat and cover for inve rtebrate and vertebrate prey items of the F, terr eta lso es s for LF ove predators through primary produ n. v n cover during dispersal. Ripari an vegetati s ta integrity of systems by pr ing b th sta erv a b fil sed nutrients, and contami efo re e w ed, rvi n

source.
to a lack fec , p l ri dico pla nno uan itative eff data st t plic of dicofol m ult i toto ever, due a lac deta vid , the relati tween effect serve app n ra dicofol cannot be defined. In addition, involving effects of dicofol to plants. Although effects of ofol on pla anno a ntified, effects of dicofol on plan not coun

5.2.4. P ary ituen men

As discussed e, ef of d l to co ng t uatic terre l habitats of the CRLF cannot be discounted. Also, exposures of dicofol to the CRLF and ave the potent aff CR The e, dic is likely to re s to the CRLF’s aquatic and terrestria itats d on nti al im acts to 8

5.2.5. Area of Effects

itial ar f conc for d fol wa n 2.7 d picted in Figure 5 of the problem formul n. A p depicting the overlap of this itial area of concern an RLF h tat is d ted in ure 1 ecaus the la f AEC in several chronic toxi cribed in Section 4.3.1), the on area for dicofol is establishe the en state o aliforn im

Terrestrial plants serve seve ral important habitat-related functions for the CRLF. In

CRL while foraging. Terrestrial plants also provi estrial veg tion a provid h elter de energy to the terrest the CR and c rial ecosystem r from

ctio Upland egetatio includ ing grassland and woodlands provides on help to main in the aquatic ovid ank and ermal bility, s ing as uffer to ter out iment, nants b re they ach th atersh and se ng as a energy

Due

ual of ef ts data otentia sk of fol to nts ca t be q tified. Q ects sugge hat ap a tions ay res ies n phy xicity, how

e to k of il pro ed in the available stud onship b there is one reported incident s ob d and licatio tes of

dic nts c t be qu ts can be dis ted.

rim Const t El e ts of Designated Critical Habitat

abov fects icofo plants mprisi he aq and stria

its prey h ial to ect the LF. refor ofol sult in effect l hab base pote p all PCEs.

The in ea o ern ico s previously discussed in S ectio an de atio ma in d C abi epic Fig 1 . B e of ck o a NO city studies with birds (des acti d as tire f C ia.

122Figure 11. Intersection between dico fol use areas and CRLF habitat.

Available pesticide use data from California indicate that dicofol has been used in

ounties which contain CRLF habitat. Out of 58 counties in California, 33 conta c in some

123124 portion of CRLF critical habitat or core area s. According to use data for 1999-2006, all o the 33 counties con f taining CRLF areas have re ported past uses of dicofol. From 1999- 2006, 8 of these counties had >1000 pounds of d n

Table 61. Summary of CDPR pesticide use reporting b fol (annual pounds of dicofol applied from 1999 to 2006).

County RLF at/cor

eas sent? 2001 2003 4 2005 icofol applied a

y county for di co nually ( Table 61 ).

Are C habit e 1999 2000 ar pre 2002 200 2006

FRESNO ye s 123,090 100,221 75,201 5 3 1,56 49,215 63,3 44 60,967 27,191
TULARE o 9,640 3 3 42,234 4 07 35,060 ,155 n 53,026 62,227 3 5,51 3,5 10
KINGS ye s 35,692 44,112 18,674 2 4 5,11 27,709 3 10 1,0 29,124 7, 807
MERCED ye s 23,932 25,490 19,746 1 0 7,07 18,552 2 07 7,7 19,666 22 ,032
KERN ye s 32,442 22,994 9,345 1 8 0,33 8,726 5,9 66 12,774 5, 828
STANISLA US ye s 17,860 23,376 1 4,536 1 5 3,81 11,925 1 22 3,8 7,120 5, 330 SAN JOAQ UIN ye s 22,647 15,153 3,379 4,895 3,527 5,5 82 4,839 5, 924
MADERA o 6,208 4,369 037 54 5,358 938 n 12,042 3,019 2, 2,4 4,
MONTERE Y yes 7,057 4,058 4,504 1,523 802 1,8 24 3,767 1, 825
IMPERIAL o ,103 371 65 2,138 2 n 8,439 2,916 3 2,271 2, 2,9 47
SUTTER o 3,071 500 46 1,580 905 n 2,514 3,590 4,067 2, 1,8 2,
RIVERSID E yes 5,996 2,466 1 ,913 2,046 3,140 2,6 94 586 1, 212
BUTTE ye s 829 1,545 4, 846 1,278 4,196 2,2 55 3,797 1, 102
YOLO 3 431 1 no 4,652 2,585 1,511 2,466 1,771 40 34
GLENN no 2,016 645 1,066 1,273 980 618 1,226 1,170
TEHAMA yes 1,219 1,529 1,128 2,356 2,159 42 277 29
SOLANO yes 2,353 496 1,210 1,294 833 368 663 184
COLUSA 479 no 1,766 224 233 770 403 1,775 756
SANTA BARBARA yes 487 1,670 797 349 162 636 1,311 571
SACRAMENTO yes 3,537 1,270 133 376 211 3 8 0
CONTRA STA CO yes 1,432 1,107 1,282 33 301 334 0 10
SAN LUIS OBISPO yes 1,881 1,495 198 56 4 149 3 324
SAN DIEGO yes 449 269 385 290 496 288 235 86
SONOMA yes 1,363 780 103 8 18 0 0 2
SANTA CLARA yes 76 12 7 26 179 395 840 543
ALAMEDA yes 1, 667 72 35 0 0 2 0 0
VENTURA yes 27 84 189 23 441 693 251 27
LOS ANGELE S yes 527 731 273 135 29 2 2 7
SAN BENI TO yes 813 416 55 0 0 50 0 195
SISKIYOU 149 no 0 0 0 0 8 494 874
YUBA yes 177 11 638 47 263 7 0 0
ORANGE yes 860 60 18 31 13 8 3 0
MENDOCI 0 NO no 604 161 0 2 0 0 6
AMADOR yes 92 16 30 0 629 0 0 0
SAN BERN RDINO no 211 149 86 45 29 5 5 5 A SHASTA yes 173 218 11 0 26 31 34 2
MODOC no 0 0 0 0 0 441 20 0
SANTA CRUZ yes 222 4 9 179 8 0 0 0County habitat/core 1999 2000 2001 2002 2003 2004 2005 2006 Are CRLF

areas present?
CALAVER 0 AS no 63 8 173 123 0 0 0
NAPA yes 154 0 53 0 8 0 65 0
EO yes 103 19 40 8 10 13 20 12 SAN MAT PLACER 0 no 42 125 1 0 1 0 1
LAKE 3 no 47 7 38 12 20 6 3
O yes 65 0 6 14 42 2 2 0 EL DORAD NEVADA yes 42 7 0 4 0 0 0 0
PLUMAS yes 12 0 0 0 0 0 0 0
MARIPOS 0 0 0 0 0 0 A no 0 6
SIERRA no 6 0 0 0 0 0 0 0
MARIN yes 2 0 0 0 0 0 0 0
SAN FRAN 0 CISCO no 2 0 0 0 0 0 0
HUMBOL 0 DT no 0 1 0 0 0 0 0 Total 372,704 328,533 212,033 182,430 185,981 211,738 193,809 100,862

In order to determine the extent of the lotic (flowing) aquatic habitat directly affected in aquatic, the greatest ratio of the RQ to the LOC for any endpoint for aquatic organisms is used to determine the distance downstream for concentrations to be diluted below levels that would be of concern ( i.e . result in RQs less than the LOC). For this assessment, this applies to RQs for acute exposures of total re sidues of dicofol to the aquatic-phase CRLF (and fish and aquatic-phase amphibians). The highest RQ (0.71) divided by the acute LOC (0.05) results in a ratio of 14.2. Th e maximum downstream distance from areas where dicofol are applied and dicofol is at concentrations that are of concern to the aquatic-phase CRLF is 155 km.

EECs and relevant RQs calculated by T-HER PS and T-REX apply to sites where dicofol is directly applied. Since dicofol can be transported through spray drift to non-target

reas beyond the treatment site, the CLRF and its prey located outside of direct treatment

here the LOC is exceeded is expected to e less than 161 feet for aeria l applications and 43 feet for ground applications. a areas can still be exposed to dicofol in non-targ et areas. Exposure a nd associated risks to the CRLF are expected to decrease with increas ing distance away fr om the treated field or site of application.

Based on acute effects data for the terrestrial-phase CRLF, spray drift deposition of dicofol as low as 0.18 lbs a.i./A would be su fficient to exceed the acute listed species LOC for the CRLF. This is based on the hi ghest acute RQ for terre strial phase CRLF and its prey, which is 1.69 based on risks to medium sized CRL F receiving dicofol through consumption of small herbivore mammals. For aer ial applications of dicofol to citrus and pome fruits, at the maximum application rate (3 lb a.i./A), spray drift is sufficient to exceed the LOC for as far as 161 feet fr om the edge of the treatment field (Table 62 ). Since 3 lb a.i./A represents the highest applic ation rate of dicofol, for all other uses of dicofol, the distance from the edge of the field w b

125Table 62. Single application rate not exceeding ac ute LOC for dietary- and dose-based exposures of the CRLF to dicofol. Distance from edge of field w here LOC is not exceeded (in feet) fo r single application of 3 lb a.i./ A 2, 3 CRLF

size 1 Based on dose or diet? Feeding Category Highest application rate

not exceeding LOC (lbs a.i./A)
Ground A erial medium Dose small herbivore mammals 0.18 43 161 all Diet Small herbivore mammals 0.55 16 43 all Diet Small insects 0.64 13 30 large Dose small herbivore mammals 1.1 10 10 medium Dose small insectivore mammals 2.9 3 0 small Dose small insect s >3 0 0 Dose m edium small insects >3 0 0 large Dose small insects >3 0 0 large Dose small insectivore mammals >3 0 0 Small Dose large insects >3 0 0 medium Dose large insects >3 0 0 large Dose large insects >3 0 0 all Diet large insects >3 0 0 medium Dose terrestrial-phase amphibians >3 0 0 all Diet Small insectivore mammals >3 0 0 all Diet Terrestrial-phase amphibians >3 0 0 large Dose terrestrial-phase amphibians >3 0 0 1. Small is defined as 1.4 g. Medium is defined as 37 g. Large is defined as 238 g. 2. Estimated using the terrestrial assessment of the Tier 1 version of AgDRIF T. Modeling assumed that applications

w ere done using ground and aerial methods, and assuming that the droplet size distribution was “ASAE very fine to fine” for ground applications (high boom) and "ASAE fine to medium" for aerial applications. 3. 3 lb a.i./A is the highest application of dicofol. Th is corresponds to applications to citrus and pome fruits.

5.2.6. Description of Assumptions, Limitations and Uncertainties

5.2.6.1. Exposure Assessment

Maximum Use Scenario

The screening-level risk assessment focuses on characterizing poten tial ecological risks resulting from a maximum use scenario, which is determined from labeled statements of maximum application rate and number of app lications with the shortest time interval between applications. The frequency at wh ich actual uses approach this maximum use scenario may be dependant on pest resistance , timing of applications, cultural practices, and market forces.

126Use Characterization Uncertainties

C ounty-level usage data were obtained from California’s Department of Pesticide

he standard ecological water body scenario (EXAMS pond) used to calculate potential d to represent conservative estimates, and to void underestimations of the actual exposur e. The standard sc enario consists of

have higher peak EECs than the EXAMS pond. These water bodies will be ither smaller in size or have larger drai nage areas. Smaller water bodies have limited

he Agency acknowledges that there are some unique aquati c habitats that are not

presentative f exposure to aquatic-phase CRLFs. In ad dition, the Services agree that the existing Regulation Pesticide Use Reporting (CDPR PU R) database. CDPR PUR documentation indicates that errors in the data may in clude the following: a misplaced decimal; incorrect measures, area treated, or units; and re ports of diluted pestic ide concentrations. In addition, it is possible that the data may c ontain reports for pesticide uses that have been cancelled. As with all pesticide usage da ta, there may be instances of misuse and misreporting. The Agency made use of the most current, verifiable information; in cases where there were discrepancies, the most conservative information was used.

Aquatic Exposure Modeling of Dicofol

T aquatic exposure to pesticides is intende

a application to a 10-hectare field bordering a 1-hectare, 2-meter deep (20,000 m3) pond with no outlet. Exposure estimates genera ted using the EXAMS pond are intended to represent a wide variety of vul nerable water bodies that occu r at the top of watersheds including prairie pot holes, playa lakes, wetlands, vernal pools, man-made and natural ponds, and intermittent and lower order streams. As a group, there are factors that make these water bodies more or less vulnerable than the EXAMS pond. Static water bodies that have larger ratios of pesticide-treated drainage area to water body volume would be expected to

e storage capacity and thus may overflow and carry pesticide in the discharge, whereas the EXAMS pond has no discharge. As waters hed size increases be yond 10-hectares, it becomes increasingly unlikely that the entire wa tershed is planted with a single crop that is all treated simultaneously with the pesticid e. Headwater streams can also have peak concentrations higher than the EXAMS pond, but they likely persist for only short periods of time and are then car ried and dissipated downstream.

T accurately captured by this modeling scenar io and modeling results may, therefore, under- or over-estimate exposure, depending on a number of variables. For example, aquatic-phase CRLFs may inha bit water bodies of different size and depth and/or are located adjacent to larger or smaller drainage areas than the EXAMS pond. The Agency does not currently have sufficient informa tion regarding the hydrol ogy of these aquatic habitats to develop a specific alternate scen ario for the CRLF. CRLFs prefer habitat with perennial (present year-round) or near-p erennial water and do not frequently inhabit vernal (temporary) pools because conditions in these habitats are generally not suitable (Hayes and Jennings 1988). Therefore, the EXAMS pond is assumed to be re

o EXAMS pond represents the best currently available approach for estimating aquatic exposure to pesticides (U.S. FWS/NMFS 2004).

127In general, the linked PRZM/EXAMS model produces estimated aquatic concentrations that are expected to be exceeded once within a ten-year period. The Pesticide Root Zone Model is a process or “simulation” model that calculates what happens to a pesticide in an agricultural field on a day-to -day basis. It considers factors such as rainfall and plant anspiration of water, as well as how and when the pesticide is applied. It has two major and chemical transport. Water movement is simulated by the use f generalized soil parameters, including fi eld capacity, wilting poin t, and saturation

ct ed to be exceeded in the environment pproximately 90 percent of the time. M obility input values are chosen to be

uenced substantially by rocesses governing sediment particle deliv ery to (and transport within) water bodies (i.e., se mpounds, soil erosion is usually a major source of

esticide loading into aquatic ecosystems. On ce in an aquatic ecosystem, processes such tr components: hydrology

o water content. The chemical transport com ponent can simulate pesticide application on the soil or on the plant foliage. Dissolved, adsorbed, and vapor-phase concentrations in the soil are estimated by simultaneously considering the processes of pesticide uptake by plants, surface runoff, erosion, decay, vola tilization, foliar wash-off, advection, dispersion, and retardation.

Uncertainties associated with each of these individual co mponents add to the overall uncertainty of the modeled concentratio ns. Additionally, model inputs from the environmental fate degradation studies are chosen to represent the upper confidence bound on the mean values that are not expe

a representative of conditions in the environment. The natural va riation in soils adds to the uncertainty of modeled values. Factors such as application date, crop emergence date, and canopy cover can also affect estimated c oncentrations, adding to the uncertainty of modeled values. Factors within the ambien t environment such as soil temperatures, sunlight intensity, antecedent soil moisture , and surface water temperatures can cause actual aquatic concentrations to differ for the modeled values.

The temporal and spatial distribution of pes ticides with persistent and bioaccumulative characteristics in aquatic ecosystems is expected to be infl
p diment dynamics). For these co
p as settling, resuspension, and burial of sedime nt particles can affect the distribution of pesticides in the water column-, pore wate r-, and suspended- and benthic-sediment compartments. Sediment dynamics can also influence pesticide bi oavailability within these compartments, due to pesticide so rption on particulate organic carbon and complexation with dissolved organic car bon. Currently, OPP’ s aquatic exposure modeling framework incorporates pesticide de livery to a standard pond from soil erosion and runoff using the Pesticide Root Zone M odel (PRZM). In this modeling framework, only the pesticide mass delivered from soil eros ion and runoff is considered for delivery to an aquatic ecosystem (i.e., the mass of soil and volume of runoff predicted by PRZM are not considered). Pesticide transport be tween the water column and the benthic region within the standard pond is modeled usi ng the Exposure Analysis Modeling System (EXAMS) based on a set of lumped parameters that are designed to reflect the combined effect of multiple transport processes (e.g ., diffusion, setting and resuspension). The current modeling framework does not consider pesticide burial in the benthic area, a process by which pestic ide is rendered permanently unava ilable for biological interaction due to accumulating sediment. Without consid eration of burial processes, the current

128modeling framework likely represents an effective screen for pesticide exposure

assessm ent in both lentic (static) and lotic (flowing water) systems.

sumed pesticide

sidues in wildlife dietary items. These resi due assumptions are believed to reflect a

pl ants in the case of grass and forage mpling.

was assumed that ingestion of food items in the field oc curs at rates commensurate

is comparable with onsumption during laboratory testing. In the screening process, exposure may be

pecies were not Unlike spray drift, tools are currently not av ailable to evaluate th e effectiveness of a vegetative setback on runoff and loadings. Th e effectiveness of vegetative setbacks is highly dependent on the condition of the vegetative strip. For example, a wellestablished, healthy vegetative setback can be a very effective means of reducing runoff and erosion from agricultural fields. Alte rnatively, a setback of poor vegetative quality or a setback that is channelized can be ineff ective at reducing loadings. Until such time as a quantitative method to estimate the effect of vegetative setbacks on various conditions on pesticide loadi ngs becomes available, the aq uatic exposure predictions are likely to overestimate exposure where h ealthy vegetative setbacks exist and underestimate exposure where poorly developed, channelized, or bare setbacks exist.

Terrestrial Exposure Modeling of Dicofol

The Agency relies on the work of Fletcher et al. (1994) for setting the as

re realistic upper-bound residue estimate, alth ough the degree to which this assumption reflects a specific percentile estimate is difficult to quantify. It is important to note that the field measurement efforts used to devel op the Fletcher estimates of exposure involve highly varied sampling techniques. It is entirely possible that much of these data reflect residues averaged over entire above ground

sa

It with those in the laboratory. Although th e screening assessment process adjusts dryweight estimates of food intake to reflect th e increased mass in fresh-weight wildlife food intake estimates, it does not allow for gross energy differences. Direct comparison of a laboratory dietary concentratio n- based effects threshold to a fresh-weight pesticide residue estimate would resu lt in an underestimation of field exposure by food consumption by a factor of 1.25 – 2.5 for most food items.

Differences in assimilative efficiency betw een laboratory and wild diets suggest that current screening assessment methods do not acc ount for a potentially important aspect of food requirements. Depending upon species and dietary matri x, bird assimila tion of wild diet energy ranges from 23 – 80%, and ma mmal’s assimilation ranges from 41 – 85% (U.S. EPA 1993). If it is assumed that labo ratory chow is formulated to maximize assimilative efficiency ( e.g ., a value of 85%), a potential for underestimation of exposure may exist by assuming that consumption of food in the wild

c underestimated because metabolic rates are not related to food consumption.

For the terrestrial exposure analysis of this risk assessment, a generic bird or mammal was assumed to occupy either the treated field or adjacent areas receiving a treatment rate on the field. Actual habitat requirements of any particular terrestrial s

129c onsidered, and it was assumed that species occupy, exclusively and permanently, the

sport

t are d. However, once in th fo rtition he g arti , ex ely particle phase, potentia buting to the long-range transport of dicofol. Partioning in the air st likely occur when the pesticide is applied via an aerial or ground spray, arly when -low v e spr Data latiliza from fo rfaces availab weve ee dis able residu ind at the

r dico cotton, cucumbers, and or was 52, an days, y. Fo parative purposes, DDT has ge of ves on from .8 days (W s and M ell

P is ble to y the extent to which dicofol and its degradates will o long-rang mospheric transport once it has been released from a treatm nt site, ism of transport will cons route of exposure for nontarget animals
-7 o Europe’s Air Pollution has indicated that ort (Rasenberg et al. 2003). According to n the gas and particle phases in the tmosphere and is likely to exist largely in the part icle phase.”

d ambient air in Lo mpoc (Santa Barbara County) for 31 is largest p r seed s. CDPR d the pesticides during the peak use period for most of the pesticides, between May 31 and August 3, 2000. Durin 10-week period ected 24-hour sa s, four ve days per we each of the fo ing locations, located in the t, west, southwes d central parts of the county. The University of California, performed the pr laboratory analysis, using a new method developed to analyze the pest icides used in L dicofol, the highest one-day ted as trace, meani ng the concentration was halfway between the tection limit and the estimated quantitation lim m 3 . Additionally, the 14-day and 10-we ir concentrations for dicofol were a sted as

., the concentration was halfway betw ethod detection l nd the itation lim f 1.37 ng/m 3 and 0.91 ng/m 3 , respectively). Collocated ollected du the last week of s to determine if any percentage ical concentrations were being mi ssed in the analysis of the prim amples modeled treatment area. Spray drift model predictions suggest that this assumption leads to an overestimation of exposure to spec ies that do not occupy the treated field exclusively and permanently.

Long Range Tran

Based on dicofol’s vapor pressure (3.9x10 -7 torr), low levels of volatility can potentially occur, bu not expecte e air dico l can be expe cted to pa between t as and p cle phases in the at m osphere isting larg in the lly c ontri would mo particul ultra olum ays. on vo tion liar su

were no t le. Ho r, thr lodge foliar e studies icate th half-life fo tivel fol on

r anges

n 3.2, 5. i d 15.6

r respec com a ra half -l clove 1.6 to 18 illi cDow 1987).

Although OP underg not a e at quantif

e this mechan titute a distant from use sites. B a sed on its vapor pressure (3.9x10 torr @ 20 C) and persistence air (half life =3.1 da ys), the United Nations Economic Commission for in the (UNECE) Convention on Long-range Transbounda ry dicofol has the potential for long-range transp the report, “dicofol is expected to partiti on betwee

a

Atmospheric Monitoring Data

In 2000, CDPR monitore pesticides and breakdown pr oducts, including dicofol (CDP R 2003). Lompoc County one of the roducers of flowe s in the United State monitore

g this , DPR coll mple consecuti

es ek at ur monitor northw t, an Davis imary specifically ompoc. For air concentration was lis de method it of 4 ng/ measured highest i.e. ek a lso li trace ( een the m imit a estimated quant samples were c it o ring ampling of the chem ary s

130a s particulates. In all of the samples analyzed, levels of dicofol were below detection

rotection Agency’s Environmental Justice Action Plan, CDPR conducted a pilot project focusing on pesticide air

concen e, predom inantly Hispanic, Fresno County farming

ommunity of Parlier, located in the San Joaquin Valley (C DPR 2006). Fruit orchards

nd sixty-eight ambient air sa mples were collected and analyzed for icofol. Dicofol was not detected in a ny of the 468, one-day concentration samples

6 ng/m out of 53 samples collected (Yeary et al. 1993). It is not clear hether the detection oc curred in California.

al by a constant flow of air (wind speed of 0.02 m/s) or water cean water circulation sp eed of 0.02m/s (Scheringer et al. 2006).

. A high TE value indicates an “optimal” ansport condition from the source region to remote depositional region. levels.

In 2006, as part of the California Environm ental P

trations in the low-incom

c and grape vineyards were the predominant crops in the area. CDPR and the Air Resources Board (ARB) collected samples of ambient air at three primary schools throughout the 2006 calendar year. During the sampling period, approximately 6 applications totaling 150 lbs of dicofol occurre d within five miles of Parlier in 2006. Four hundred a d collected (quantitation limit = 46.3 ng/m 3 ). It does not appear that particulate matter, collected during this study, was analyzed for dicofol concentrations; given that dicofol is expected to be associated with particulate matter suspended in th e air, the absence of detections may not accurately reflect the potential movement of dicofol.

The USGS publication, Pesticides in the Atmosphere (Majewski et al. 1995) reports an observed concentration for kelthane (dicofol) in th e air of 9.5 ng/m 3 . Additionally, a cited study in this reference reports one detected residential outdoor ambient air concentration of 3

w

Modeling of Long-Range Transport Potential

The “OECD Pov and LRTP Screening Tool” (v ersion 2.0) was utilized in evaluating the overall environmental persistence (Pov), th e long range transport potential (LRTP) and transfer efficiency (TE). The OECD Tool re quires estimated degradation half lives in soil, water and air, and partition coefficients between air and water and between octanol and water as chemical-specific input paramete rs to calculate metr ics of Pov and LRTP. Pov is derived from the degrada tion rate constants in soil, wa ter and air to provide overall degradation. The resulted P ov value represents the characteristic time for disappearance of a chemical after releases in various media have been stopped and the overall degradation rate is determined by the di sappearance of chemical from a medium (Scheringer et al ., 2006). The characteristic travel distance (CTD) represents the potential of a chemical to be transported over lo ng distances in air or water. In the OECD Tool, the CTD is the distance at which the concentration of chemical decrease to 37% due to transport of chemic (o

Transfer efficiency is a dimensionless metric of potential for atmospheric transport and deposition of parent compound in terrestrial a nd aquatic environments of a remote region (Wegmann et al. 2007). It is a ratio between the depositional flux (mo l/day) in remote region and emission flux from the source area
tr

131The OECD Tool w as used in evaluating the Pov and LRTP for 3 known PBT chemicals DT, aldrin and endrin) and the dicofol isom ers (both as the parent and parent plus

Table 63. Ph properties used as input for estimating overall persistence a using the OECD Tool. (D degradates) using chemical-specific degradation half-lives in soil, water, and air as well as two partition constants, the Kow and K AW
. Table 63 provides input parameters used in the OECD Tool.
ysicochemical and environmental fate nd long-range transpor t potential
N ame of Chemical Molecular Weight (g/mole) Log K ow a Log K Aw a Half life in Air (hrs) Half life Half life in Water in Soil (hrs) (hrs) p.p’ DDT b 345.5 6.39 -3.34 170 5500 17000 Aldrin b 364.9 4.94 -3.38 2.86 2670 3830 Endrin b 380.9 5.44 -3.11 12.72 78840 29070
o,p ’dicofol 370.5 6.06 -7.641 74.4 c 408 d 612 d

p,p ’-dicofol 370.5 6.06 -5.005 74.4 c 1536 d 2304 d
DCBP 251 4.44 e -4.359 e 103 e 1440 e 2880 e F W-152 336 4.89 e -7.187 e 57.1 e 4320 e 8640 e DCBH 253 4.0 e -6.404 e 25.1 e 900 e 1800 e3- and 4- OHDCBP 267 3.96 e -8.343 e 46.8 e 1440 e 2880 e

2 OH-DCBP 267 4.73 e -5.242 e 11.3 e 1440 e 2880 e a Maximum reported value b Input parameters for these chemical are based on the Reference chemicals data in the OECD Tool. c Half-life in air based on valu e re ported in Rasenberg et al. 2003 d The half-life in water based on PRZM/EXAM inputs e Maximum value derived in EPISuite for dicof ol degradates.

Although there are considerable uncertainties in the environm ental fate properties of th selected chemicals under consideration, the results ( Table 64 ) indicate that dicofol and its degradates have Pov and LRTP properties si milar to those of several known POPs ( p, DDT, aldrin and endrin).
Table 64. Overall persistence and characteristic travel distances generated using the OECD Tool. e

p’

Chemical Overall Persistence (Pov) (Days) Characteristic Travel Distance km (Miles) Transfer Efficiency (%)

p.p’ DDT 1010 2530 (1572) 5.17
Aldrin 225 206 (128) 0.003
Endrin 1556 515 (320) 0.04

o ,p’ -dicofol 37 2142 (1331) 9.45 p,p’ -dicofol 138 1467 (912) 3.39
DCBP 172 1381 (858) 2.24 FW-152 516 504 (313) 2.15 DCBH 108 238 (148) 0.663- and 4- OHDCBP 171 149 (93) 0.31 2 OH-DCBP 173 228 (142) 0.10

132Results from the OECD Tool do not indicate absolute load ing of pesticides in the environment but help to compare model esti mates for dicofol residues relative to known POP pesticides according to their Pov, TE, and CTD.

Annual Emission Amounts

There are two potential mechanisms that can result in transport of dicofol from an application area to the atmosphere with subsequent wet or dry deposition of the compound to areas distant from the initial site of application. These mechanisms include 1) drift of dicofol during spray treatments of fields and 2) wind erosion of soil containing sorbed dicofol.

From the CA PUR data, the average annual rate of dicofol applied between 1999 and

006 was 223,511 lbs. From the AGDRIFT an alysis, between 0.94% and 8.7% of the amount applied during aerial and ULV applicati on, respectively, is lost due to airborne

rift, or 2,101 to 19,450 lbs/year. Wet and dry deposition would result in removal of this irborne drift from the atmosphere; however, estimates of thes e removal processes timates for scavenging coefficients , particle size distri butions, and settling velocities, and are beyo nd the level of this analysis. As such, a conservative estimate would result in all of th e aerial drift, or 2,101 to 19,450 lbs/year, remaining for longrange transport.

As dicofol has an affinity to partition to pa rticulate matter, a potentially significant source of dicofol emissions from a field would be particulate matter from windblown soil erosion. The California Air Resources Board develo ped non-pasture agriculture particulate matter emission estimates for a number of counties in California (CARB 1997). These emission estimates were divided by the total number of acres harvested in each county (USDA 2009) and then multiplied by the average annual acres of dicofol applied in each county (from the CA PUR data), in order to estimate the annual particulate matter per county where dicofol was used. The average annual amount of particulate matter from nonpasture windblown agricultural emissions in counties where dicofol was applied was 2,677 tons/y ear. If 90% of the dicofol applied is integrated into the top 1 cm of the soil, th en the concentration of dico fol in the soil is 2.59 x 10 -8 lbs dicofol/cm 3 (0.9 x 223,511 lbs / [192,120 acres x 4.05 x 10 7 cm 2 /acre x 1 cm]). Assuming an average soil bulk density of 1.3 g/cm3, this equates to 9.03 x 10 -6 lbs dicofol/lb soil. Multiplying this concentration by the average amount of particulate matter from nonpasture windblown ag ricultural emissions results in 48 lbs/year of dicofol emitted via wind erosion.

ight volatilize 2

d

a require es

he average total annual amount of dicofol, not including that wh ich m T from the soil or wate surface, that is avai lable for long range tran sport is between 2,149 and 19,500 lbs/year, or between 1 and 9% of the dicofol applied. It is worth noting that despite these estimates, air monitoring re ported earlier showed only trace amounts of dicofol in the atmospheric samples collected.

133DDT, DDD, DDE

In assessing the impacts of dicofol on the red-legged frog, it was assumed that the impacts of DDT, DDD, and DDE would be a dditive to those seen for dicofol’s total residues of concern.

5.2.6.2. Effects Assessment

Age Class and Sensitivity of Effects Thresholds

It is generally recognized that test orga nism age may have a significant impact on the observed sensitivity to a toxicant. The acute toxicity data for fish are collected on juvenile fish between 0.1 and 5 grams. Aqua tic invertebrate acute testing is performed on recommended immature age classes ( e.g ., first instar for daphni ds, second instar for amphipods, stoneflies, mayflies, and third instar for midges).

Testing of juveniles may overe stimate toxicity at older age classes for pesticide active ingredients that act direc tly without metabolic transf ormation because younger age classes may not have the enzymatic systems asso ciated with detoxifyi ng xenobiotics. In so far as the available toxicity data may provide ranges of sensitivity information with respect to age class, this assessment uses th e most sensitive life-stage information as measures of effect for surrogate aquatic an imals, and is therefore, considered as protective of the CRLF.

Use of Surrogate Species Effects Data

Guideline toxicity tests and open literature da ta on dicofol are not available for frogs or any other aquatic-phase amphibian; therefore, freshwater fish are used as surrogate species for aquatic-phase amphibians. E ndpoints based on freshwat er fish ecotoxicity data are assumed to be protective of potential direct effects to a quatic-phase amphibians including the CRLF, and extrapolation of the risk conclusions from the most sensitive tested species to the aquatic-phase CRLF is likely to overestimate the potential risks to those species. Efforts are made to select th e organisms most likely to be affected by the type of compound and usage pattern; however , there is an inherent uncertainty in extrapolating across phyla. In addition, the Agency’s LOCs are intentionally set very low, and conservative estimates are made in the screening level risk assessment to account for these uncertainties.

In order to characterize the conservatism, of the endpoint se lected to represent direct effects to aquatic-phase CRLF ( i.e ., the 96-h LC for the cutthroat trout = 53 μg/L), a

eshwater fish ( Table 24 ). Data were considered useful for the distribution if they are lassified acceptable or supplem ental. Data for this dist ribution were collected from

gistrant-submitted studies as well as the ope n literature (as identified using ECOTOX). nce the data set was assembled, the av erage of the Log10 values of the LC 50 values for 50 genus sensitivity distribution was derived us ing the available acute toxicity data for fr

c

re O

134a species was cal culated. Then, the averag e of the Log10 values of the genera was alculated. A student’s t distri bution was used to derive a genus sensitivity distribution l of

he
ta of

Equation is n isaquatichase CRLF (LC 50 = 53 μg/L) is comparable to the lower 5% of the genus sensitivity ating that this e ndpoint is protective of the lower 5 th ercentile of freshwater fish species. c for with the mean and standard deviations of log-transformed acute toxicity data for al the available genera of fish. The degrees of freedom were equal to n-1, where n is t number of genera for which ther e are data available for the di stribution. In this case, da were available for 6 genera, so the distri bution was established with 5 degrees freedom. The t-statistic was calculated for pr obabilities ranging 0.05- 0.95 at intervals of 0.05. The log LC 50 value for a specific proportion (p) of genera is calculated by 1. The genus sensitivity distribution for 96-h LC 50 values for fish exposed to dicofol displayed in Figure 12 . Additional information relevant to this sensitivity distributio provided in Appendix L . The endpoint selected to repr esent direct effects to
p distribution (LC 50 = 49 μg/L), indic
p 

# ( ) STDEVtLCLogMean LCLog Equation p p 

### * .1 50 50 

### + =

0.5 0.6 0.7 0.8 0.9

1

Pimephales Lepomis

Micropterus

Ictalurus

0.4

0 0.1 0.2 0.3

10.0 100.0 1000.0 LC50 (ug/L)Proportion

Figure 12. Genus sensitivity distribution for ac ute (96-h) exposures of fish to dicofol.

order to characterize the conservatism of the endpoint se lected to represent direct ffects to terrestrial-phase CRLF ( i.e ., the subacute dietary toxicity endpoint for birds, C 50 for the Japanese quail = 903 ppm), a speci es sensitivity distribution was derived using the available subacute dietary toxicity data for birds ( Table 29 ). Data were considered useful for the distribution if they are classified acceptable or supplemental. In

e L Salvelinus Oncorhynchus

135Data fo gistrant-submitted studies as well as the pen literature (as identified using ECOTOX). Once the data set was assembled, the

ed subacute toxicity data for all of the available species within taxa. The egrees of freedom were equal to n-1, where n is the number of species for which there are data available for the distribution. In this case, data were available for 4 species, so the distribution was established with 3 degrees of freedom. The t-statistic was calculated for probabilities ranging 0.05-0.95 at intervals of 0.05. The log LC 50 value for a specific proportion (p) of genera is cal culated by Equation 1. The speci es sensitivity distribution for LC 50 values for birds exposed to dicofol is displayed in Figure 13 . Additional information relevant to this sensitivity distribution is provided in Appendix L . The Japanese quail toxicity endpoint selected to represent direct effects to terrestrial-phase CRLF is comparable to the lower 10% of the species sensitivity distribution. r this distribution were collected from re

o average of the log-transformed LC 50 values for a species was calculated. Unlike with the fish data, avian data were not averaged based on genera be cause no data were available for multiple species within the same genera. A student’s t distribution was used to derive a species sensitivity distribution for with the mean and standard deviations of logtransform d

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

1

100.0 1000.0 10000.0 LC50Proportion

Coturnix japonica Colinus virginianus

Phasianus colchicus

A nas platyrhynchos

Figure 13. Species sensitivity distribution fo r subacute exposures of birds to dicofol.

136Sublethal Effects

When assessing acute risk, the screening risk assessment relies on the acute mortality

e-by-case basis and only after careful consideration of the nature of the blethal effect measured and the extent and quality of available data to support

ffect in humans that similar to an effect produced by a na turally occurring estrogen, or other such endocrine effects as the Ad ministrator may designate.” Following the recommendations of its Endocrine Disruptor Screening and Testing Advisory Committee (EDSTAC), EPA determined that there were scientific ba ses for including, as part of the program, androgen and thyroid hormone systems, in addition to the estrogen hormone system. EPA also adopted EDSTAC’s recommendation that the Program include evaluations of potential effects in wildlife. When the a ppropriate screening and/ or testing protocols being considered under the Agency’s Endocri ne Disrupter Screen ing Program (EDSP) have been developed and vetted, dicofol may be subjected to additi onal screening and/or testing to better charact erize effects related to endocrine disruption.

Location of Wildlife Species

For the terrestrial exposure analysis of this risk assessment, a generic bird or mammal was assumed to occupy either the treated field or adjacent areas receiving a treatment rate on the field. Actual habitat requirements of any particular terrestrial species were not considered, and it was assumed that species occupy, exclusively and permanently, the modeled treatment area. Spray drift model predictions sugges t that this assumption leads to an overestimation of exposure to species that do not occupy the treated field exclusively and permanently. endpoint as well as a suite of sublethal respon ses to the pesticide, as determined by the testing of species response to chronic expos ure conditions and subsequent chronic risk assessment. Consideration of additional sublet hal data in the effects determination t is exercised on a cas

su establishing a plausible relationship between the measure of effect (sublethal endpoint) and the assessment endpoints. However, the fu ll suite of sublethal effects from valid open literature studies is considered for the purposes of defining the action area.

Potential for Endocrine Disruption

The extent to which dicofol may act on e ndocrine-mediated processes of non-target organisms, including CRLF is uncertain. EPA is required under the FFDCA, as amended by FQPA, to develop a screening program to determine whether certain substances (including all pesticide activ e and other ingredients) “may have an e is

137138 . i h i theses

In orde o u h is s m t, it is necess t s th s y e defined in section 2.9.1. Based on the conc lusions of this assessment, none of the hypoth a e je d eaning that th e stated hypotheses repr n terms c d t e o i cofol on the CRLF and its designated critical habitat 5.

r t

ese of

. 2.7

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### 6.0 Risk

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curren i sig ated critical habitat.

Based on the best available information, th to Adverse ination CRLF from the fol. Additionally, the Agency has CRLF desi conclus r n in tive y. Analysis r dicofol action area and C determ potential effects to designated critical habita

cum 

### Conclusions

its obligations under Section 7(

ailab

ly Affec

gnated critical habita

and in a)(2) of eci es risk asses sk s of dicof

e Agency makes a May Aff

for the

CRLF and its critica

determining use patte . The LAA determ

t is descr ed in Attachment 2 the En

sm ol to the CRLF and its d

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. Species ents the bes

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ions and ef

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RLF habitat used in ered sp e potentia

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, respec

Appendix B le to as

fects determ l r

or the

l t (LAA) deter

Table 66 l hab

rns that resu Table 65

ulative effects for the CRLF and is providTable 65.reproducDescripti dence snation for dicofol use inCalifornia. Assessment endpoint is survival, growth andtion oals.on of evif CRLF individuupportingeffects determiAssessmentEndpointEffectsBasis for DeterminationDeterminationDir toAnalysis of individual effects indicates that up to 1 in 2 individual CRLF could experience mortality after acute exposures todicofol in the aquatic habitat.- Chronic RQs for aquatic-phase CRLF exceed the LOC for all uses of dicofol, except Bermuda grass, turf and outside buildings.- Chronic EECs in the aquatic environment are abovelevels where growth effects were observed in fish.- Acute and chronic RQs for aquatic-phase CRLF consuming aquatic organisms contaminated with dicofol (resulting fromaccumulation) exceed LOCs.- Refined acute, dose-based RQs (derived using T-HERPS) for medium sized CRLF consuming small herbivore mammals exceeduming small insects and small herbivore mammalsceof dicofol.hrRLF consuming any terrestrial food item (i.e.,insechwas observed in birds (i.e., EECs are >40ect effectsCRLF-Acute RQs for aquatic-phase CRLF exceed the LOC for all usesof dicofol, except Bermudagrass and outside buildings.-LOCs for all uses of dicofol.- Refined acute, dietary-based RQs (derived using T-HERPS) for CRLF consex- Ced LOCs for several usesonic dietary-based RQs for CRLF exceed LOCs for all uses of dicofol, for Cts, mammals and terrestrial-phase amphibians).- Cppmronic, dietary-based EECs are above levels where reduced number of eggs laid).Indirect e totadpole CRLFvia reduction ofpreyRQffects(i.e., algae)values for algae are below theLOC for all uses of dicofol.Indirjuvevia rinvertebrates)- Acu- Theon this, indirect effects to the CRLF throughacute- Chrbits, peppers, tomatoes, Bermuda grass,orna- Chr, cotton, grapes, hops, mint, pome fruit,stone, and walnuts/pecans.ect effects tonile CRLFeduction ofprey (i.e.,te RQs for aquatic invertebrates exceed the LOC the majority of dicofol uses.likelihood of individual acute effects to aquatic invertebrates is≤3%. Basedeffects to aquatic invertebrates is discountable.onic RQs for aquatic invertebrates do not exceed the LOC fordicofol use on cucurmentals, turf and outside buildings.onic RQs for aquatic invertebrates exceed the LOC for dicofol use on beans, citrusfruit, strawberryIndirect effects toadul CRLF viaredu on of prey(i.e.,invertebrates,fish, frogs, mice)LAA- Acute RQs for aquatic invertebrates exceed the LOC the majority of dicofol uses.- The likelihood of individual acute effects to aquatic invertebrates is≤3%. Based on this, indirect effects to the CRLF throughacute effects to aquatic invertebrates is discountable.- Chronic RQs for aquatic invertebrates do not exceed the LOC fordicofol use on cucurbits, peppers, tomatoes, Bermuda grass,ornamentals, turf and outside buildings.- Chronic RQs for aquatic invertebrates exceed the LOC for dicofol use on beans, citrus, cotton, grapes, hops, mint, pome fruit,stone fruit, strawberry, and walnuts/pecans.-Acute RQs for aquatic-phase amphibians and fish exceed the LOC for all uses of dicofol, except Bermuda grass and outsidebuildings.tcti140AssessmentEffectsEndpointDeterminationBasis for Determination- Use of dicofol on beans, citrindividual mortality (from acut-Use of dicofol on cucurbits, gin <10% chance of effects to an- Chronic RQs for fish and aqoutside buildings.- Because the LD50used in deriterrestrial invertebrates to dicofus, cotton, hops, mint, pe exposures) to fish andrapes, pepper, stone fruiindividual fish and aquuatic-phase amphibiansving RQs for terrestrial iol potentiallyome fruit, strawberries aaquatic-phase amphibiant, tomatoes, Bermuda gratic-phase amphibians reexceed the LOC for allnvertebrates isnot quantn% d ofs.asbu esultprug andifim rged walnuts/pecans results in >10s, ornamentals, turf and outsideesenting prey of the CRLF.ses of dicofol, except Bermudaed, RQs for acute exposures of slikelihooildings rrass, turfall and laexceed thefor control of insects, itmint, hops, peppers, tommortality to <10% of tees resulting from these dime fruits, strawberries, wvertebrates. Although th50 was established, mortfects to the CRLF.exposures toterrestrial mmuda grasspome fruits could potentie fruits could potentiallyicofol result in≤2.0%he CRLF through potentidered discountable.for terrestrialmammalsve effects wereobservedia impacts to terrestrial msmall mammals to dicresult in effects to mastrial-phase amphibianrestrial-phase amphibiividual mortality usingf effects to an individurrestrial-phase CRLFseed the LOC by factorting fromchronic effecLOC of 0.05 for all usehas the potential to impaatoes, cucurbits, ornamrrestrialinsects. Therefofol uses are considerelnuts, pecans, beans,re is uncertainty in thity to small insects resmmals exceed the LOresult in 10.7% mortaesult in indirect effecortality to small maml effects to terrestrialr all uses of dicofol. CTherefore, chronic exmmals serving as poteol through consumptimals.serving as preyto thes exceed the LOC forcute dietary-based RQterrestrial amphibian ra acute effects on terranging 2x to 474x. Thto terrestrial frogs.s.ctnento suresreroentialcodaconti ltineees strialalule stheaCt: ntals,allia fore,rtsts strialmmr ofol.iamol ceptfohe AEC.pove ntialanti- Aofofonm eatedwiom- AresC- Aeranse- Andasesusesofoaleprimteviestoofdi- Cxcs rers poteforinultsnon-targetinsects (other than hoals, turf and Bermuda grass, dic, indirecteffects to the CRLF thdiscountable.tton and stone fruits could poteactual effects of these exposurting from dicofol applied to thes(0.1)for all uses of dicofol excepty to individual terrestrial mammto the CRLF due to acute effecals resulting from acute exposuammals resulting from all dicofronicEECs are sufficient to excesures of dicofol from all uses haal prey items.of contaminated earthworms froRLF do not exceed the LOC.veral uses.for terrestrial amphibians indicatresenting prey of the CRLF. Therial amphibians is discountable fefore, for all dicofol uses, there i- Given that dicofol is intended-For use of dicofol on grapes,result in a chance of individualeffects to terrestrial invertebrat- Use of dicofol on citrus, po≥10% of mortality to small ininvertebrates, given that no LDpotential to result in indirect ef- RQ values representing acuteturf, outside buildings and Ber- Use of dicofol on citrus anddicofol use on citrus and pommammals. All other uses of dTherefore, indirect effects to tcitrus and pome fruits, are cons- Chronic RQs exceed the LOCfor mammals where reproductito indirectly affect the CRLF vcute and chronic exposuresth dicofol have the potential tcute, dose-based RQs for tercute, dietary-based RQs for tnalysis of the likelihood of idicofol result in≤2% chancepact of the indirect effects tocofol.hronic, dietary-based RQs edirect effects to the CRLF resey bees).fol expough potally resuto terrecrops haornamels. Thereto terrees to dicuses, exd the LOthe potefields trthat allefore, ther all usesntialIndirect effects toCRLF via-Defetcohe aqandtercad entue to a lack of quantitativerestrial habitats of the CRLFfects data for non-targnnot be quantified anplantsexposed to diffects of dicofol to plafol, potential risk of dicofol to ts cannot be discounted.uatic141142AssessmentEndpointEffectsDeterminationBasis forDet ionerminatreduction ofhabitat and/orprimaryproductivity(i.e., plants)-Qu ive d uggest th cofol ma lt in phytoto y.o rte nv tsane t e te aR d t.alitat-There is-Dicofolata sne repoxposuresat did incident io plants havy resung effecotentialxicitof dicofol to plo cause indirectolvithe pts.ffects to aqutic phase CLF through reuction ofhabitaTable 66. of er n f F bi nnSummaryeffects detminatioor CRLcritical hatat based ouses of dicofol iCalifornia.AssessmentEndpointEffectsD oeterminatinBasi tes for DerminationModificataquatic-pprimary celementsc haquati Cion ofhaseonstituentDiofol has te potential tomodify habitt based on the ac-phase PEs.Tableoughnnot be- D59- Deff-Efdisic th o case C e).ic the p o ffhase rec rey (efe cofoleof th acoofol hasofol hasts to its pcts of diunted.e potential totential tseeTablto plantsdireindir59).makinctly affeectly ag up tht the aquatic-phect the aquatic-paquatic habitatRLF (SeCRLF the CRLF cModificatterrestrialprimary celementseco he po m y atrrestr Pion ofphaseonstituentHabitat EfftsDicfol has ttential toodifhabitbased on the teial-phaseCEs.eehroughcannot- DTa- Deff-Efbeic the p o tlcphase Sblic the p o ec ffec rey (efe cofol g e str at of t Fdi d.ofol hase 59).ofol hasts to its pcts of discounteotential totential tseeTablto plantsdirecindir59).makinyaffetly aup tht the terrestrialect the terrestrial-phterre ial habitCRLF (ase CRLF the CRL143 Based th the U. S. Fish and Wildlife Service under Section 7 of the Enda ngered Species Act should be initiated.

modific redicted

sks to the species and its resources ( i.e. , food and habitat) are not expected to be uniform across nuation with d expecte

. Evalua orm distribution of risk to the species would require

formation and assessment techniques that are not currently available. Examples of such

Enhanced information on the density and distri bution of CRLF life stages within specific ation

wou of the present risk assessment’s predictions of individual effects to the proportion of the popul ation extant within geographical areas where

a

mo he signifi cance of potential resource impairment to individuals of the species. trialpha sources utilized by the frog, it does not estab lish minimal requirements to sustain healthy individuals at varying life stages. Such inform ation could be used to establish biologically its to tho bove
to c

. Information on population responses of prey base organisms to the pesticide. Currently,

gro irment immediatel y following exposure to the pesticide. The degree to which repeated exposure events and th e inherent demographic characteristics of the table. An for and together with the information described above , a more complete prediction of effects to on the conclusions of this assessment, a formal consultation wi

When evaluating the significance of this risk assessment’s direct/indirect and habitat ation effects determinations, it is important to note that pesticide exposures and p ri the action area. In fact, given the assump tions of drift and downstream transport ( i.e. , atte istance), pesticide exposure and associat ed risks to the specie s and its resources are d to decrease with increasi ng distance away from the treated field or site of application tion of the implication of this non-unif in information and methodology required for this ty pe of analysis would include the following:

• recovery units and/or designated critical habita t within the action area. This inform ld allow for quantitative extrapolation

those effects are predicted. Furthermore, such population information would allow for re comprehensive evaluation of t

• Quantitative information on prey base requirements for individual aquatic- and terres se frogs. While existing information provide s a preliminary picture of the types of food

relevant thresholds of effects on the prey base, and ultimately establish geographical lim se effects. This information could be used together with the density data discussed a haracterize the likelihood of a dverse effects to individuals

• methodologies are limited to predicting exposur es and likely levels of direct mortality, wth or reproductive impa

prey population play into the extent to which pr ey resources may recover is not predic enhanced understanding of long-term prey responses to pesticide exposure would allow a more refined determination of the magn itude and duration of resource impairment,

individual frogs and potential m odification to critical habitat.144 

### 7.0 Re

lvarez, J. 2000. Letter to the U.S. Fish a nd Wildlife Service providi ng comments on the Draft

– 7- 

### ferences

A California Red-legged Frog Recovery Plan.

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California Department of Pesticide Regulation (CDPR). 2002. Pesticide Air Monitoring Result Conducted by California Air Resource s Board, 1986 - 2000. EH02-01. Kollman, W., s
California Department of Pesticide Regulation, May 2002.

CDPR. te of Department of Pesticide Regulation, March 2003.

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DPR. 2008. Surface Water Database. California E nvironmental Protection Agency, Department

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ellers, G. M., et al. 2001. Overwintering ta dpoles in the California red-legged frog ( Rana

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eNoir, J.S., L.L. McConnell, G.M. Fellers, T.M. Cahill, J.N. Seiber. 1999. Summertime Transport of Current-use pesticides from Calif ornia’s Central Valley to the Sierra Nevada Mountain Range,USA. Environmental T oxicology & Chemistry 18(12): 2715-2722.

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