Risks of Carbaryl Use to the Federally-Listed
California Red Legged Frog
(Rana aurora draytonii)
Pesticide Effects Determination
Environmental Fate and Effects Division
Office of Pesticide Programs
Washington, D.C. 20460
October 19,2007
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Primary Authors
Kristina Garber, Biologist
R. David Jones, Ph.D., Senior Agronomist
Thomas Steeger, Ph.D., Senior Biologist
Reviewers
Melissa Panger, Ph.D., Biologist
Christopher Salice, Ph.D., Biologist
Branch Chief, Environmental Risk Branch 4
Elizabeth Behl
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Acknowledgement
The carbaryl chemical team would like to acknowledge the contribution of the California red-
legged frog Steering Committee in compiling detailed information on the threatened species.
Additionally, the Steering Committee has provided invaluable guidance toward achieving greater
consistency in format and content between chemicals being assessed. We acknowledge the
contribution of Ms. Michelle Thawley, Mr. Kurt Pluntke, Ms. Megan Thynge in providing the
Geographic Information System analysis used to define the potential overlap between California
red-legged frog and their designated critical habitat with the action area.
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Table of Contents
ACKNOWLEDGEMENT 3
TABLE OF CONTENTS 4
LIST OF FIGURES 6
LIST OF TABLES 6
1. EXECUTIVE SUMMARY 9
2. PROBLEM FORMULATION 17
2.1 Purpose 17
2.2 Scope 19
2.3 Previous Assessments 20
2.4 Stressor Source and Distribution 21
2.4.1 Environmental Fate and Transport Assessment 21
2.4.2 Mechanism of Action 28
2.4.3 Use Characterization 28
2.5 Assessed Species 32
2.5.1 Distribution 33
2.5.2 Reproduction 38
2.5.3 Diet 38
2.5.4 Habitat 39
2.6 Designated Critical Habitat 40
2.7 Action Area 41
2.8 Assessment Endpoints and Measures of Ecological Effect 49
2.8.1 Assessment Endpoints for the CRLF. 49
2.8.2 Assessment Endpoints for Designated Critical Habitat 50
2.9 Conceptual Model 52
2.9.1 Risk Hypoth eses 52
2.9.2 Diagram 53
2.10 Analysis Plan 57
2.10.1. Measures to Evaluate the Risk Hypothesis and Conceptual Model 58
3. EXPOSURE ASSESSMENT 62
3.1 Aquatic Exposure Assessment 62
3.1.1 Existing Water Monitoring Data for California 62
3.1.2. Modeling Approach 67
3.1.3. Aquatic Modeling Results 80
3.2. Terrestrial Exposure Assessment 82
3.2.1. Modeling Approach 82
3.2.2. Terrestrial Animal Exposure Modeling Results 84
3.2.3. Spray Drift Modeling 86
4. EFFECTS ASSESSMENT 90
4.1. Evaluation of Aquatic Ecotoxicity Studies for Carbaryl 91
4.1.1. Toxicity to Freshwater Fish 92
4.1.2. Toxicity to Aquatic-phase Amphibians 93
4.1.3. Toxicity to Freshwater Invertebrates 95
4.1.4. Toxicity to Aquatic Plants 97
4.1.5. Freshwater Field Studies 98
4.2. Evaluation of Terrestrial Ecotoxicity Studies for Carbaryl 99
4.2.1. Toxicity to Birds 101
4.2.2. Toxicity to Terrestrial-phase Amphibians 102
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4.2.3. Toxicity to Mammals 102
4.2.4. Toxicity to Terrestrial Invertebrates 102
4.2.5. Toxicity to Terrestrial Plants 103
5.1. Risk Estimation 104
5.1.1. Exposures in the Aquatic Habitat 105
5.1.2. Exposures in the Terrestrial Habitat Ill
5.2. Risk Description 116
5.2.1. Direct Effects 117
5.2.2. Indirect Effects (through effects to prey) 130
5.2.3. Indirect Effects (through effects to habitat) 135
5.2.4. Primary Constituent Elements of Designated Critical Habitat 136
5.2.5. Action Area 137
5.2.6. Description of Assumptions, Limitations, Uncertainties, Strengths and Data Gaps 147
5.2.7. Addressing the Risk Hypotheses 152
6. CONCLUSIONS 152
7. REFERENCES 154
Appendices
Appendix A. Uses Patterns for Carbaryl Used Estimation of Risk to the California Red-Legged Frog
Appendix B. Detailed uses of carbaryl in California during 2003-2005 (CDPR 2007)
Appendix C. Intersection of Carbaryl Use Area and California Red-legged frog Habitat
Appendix D. Input Files for Tier 2 Aquatic Exposure Modeling for the Carbaryl Red-legged Frog Assessment
Appendix E. Estimation of the fraction of the watershed area which receives application on impervious surfaces in
residential watersheds
Appendix F. Treated area estimate for perimeter gardens
Appendix G. Post-processing of PRZM/EXAMS outputs to develop EECs for Rights-of-Way
Appendix H. Example outputs from T-REX v. 1.3.1 and T-HERPS v. 1.0 (outputs for lawns)
Appendix I. ECOTOX Open Literature Reviews
Appendix J. The Risk Quotient Method and Levels of Concern
Appendix K. Estimation of the Likelihood of Individual Effects to the California Red-Legged Frog from the Use of
Carbaryl
Appendix L. Sensitivity Distribution Data
Appendix M. Product Formulations Containing Multiple Active Ingredients
Appendix N. List of citations accepted and rejected by ECOTOX criteria
Attachments
Attachment 1: Status and Life History of California Red-legged Frog
Attachment 2: Baseline Status and Cumulative Effects for the California Red-legged Frog
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List of Figures
Figure 1. Generalized degradation pathway of carbaryl 21
Figure 2. Historical Extent (2002) of carbaryl usage 30
Figure 3. Distribution of reported mass of carbaryl applied during 2003-2005 in California by crop group 31
Figure 4. Recovery Unit, Core Area, Critical Habitat, and Occurrence Designations for CRLF 37
Figure 5. CRLF Reproductive Events by Month 38
Figure 6. Initial action area for crops described by orchard/vineyard landcover which corresponds to potential
carbaryl use sites. This map represents the area potentially directly affected by the federal action 44
Figure 7. Initial action area for crops described by agricultural landcover which corresponds to potential carbaryl
lithium use sites. This map represents the area potentially directly affected by the federal action 45
Figure 8. Initial action area for crops described by residential landcover which corresponds to potential carbaryl use
sites. This map represents the area potentially directly affected by the federal action 46
Figure 9. Initial action area for crops described by pasture landcover which corresponds to potential carbaryl use
sites. This map represents the area potentially directly affected by the federal action 47
Figure 10. Initial action area for crops described by non-urban forest landcover which corresponds to potential
carbaryl use sites. This map represents the area potentially directly affected by the federal action 48
Figure 11. Conceptual model for potential effects of carbaryl on the aquatic phase of the California red-legged frog.
54
Figure 12. Conceptual model for the potential effects of carbaryl on the terrestrial phase of the California red-legged
frog 55
Figure 13. Conceptual model for the potential effects of carbaryl on aquatic components of the California red-legged
frog critical habitat 56
Figure 14. Conceptual model for the potential effects of carbaryl on terrestrial components of the California red-
legged frog critical habitat 57
Figure 15. Concentrations of carbaryl reported by NAWQA in CA surface waters from 1999-2005 64
Figure 16. Temporal Changes in Surface-water Insecticide Concentrations after the phase-out of diazinon and
chlorpyrifos (Phillips et al., 2007) 67
Figure 17. Fish sensitivity distribution based 96-h LC50 values from acute exposures of fish to carbaryl 93
Figure 18. Invertebrate sensitivity distribution based 48-h and 96-h LC50 values from acute exposures of
invertebrates to carbaryl 97
Figure 19. Final action area for crops described by orchard/vineyard landcover which corresponds to potential
carbaryl use sites. This map represents the area potentially directly and indirectly affected by the federal action. ..140
Figure 20. Final action area for crops described by agricultural landcover which corresponds to potential carbaryl
lithium use sites. This map represents the area potentially directly and indirectly affected by the federal action 141
Figure 21. Final action area for crops described by residential landcover which corresponds to potential carbaryl use
sites. This map represents the area potentially directly and indirectly affected by the federal action 142
Figure 22. Final action area for crops described by pasture landcover which corresponds to potential carbaryl use
sites. This map represents the area potentially directly and indirectly affected by the federal action 143
Figure 23. Final action area for crops described by non-urban forest landcover which corresponds to potential
carbaryl use sites. This map represents the area potentially directly and indirectly affected by the federal action.
*Within recovery units 144
List of Tables
Table 1. Carbaryl Effects Determination Summary for the California Red-legged Frog 12
Table 2. Carbaryl use-specific direct effects determinations1 for the Aquatic- and Terrestrial-phase CRLF (shading
added to indicate use where there is any LAA determination) 13
Table 3. Carbaryl use-specific indirect effects determinations1 based on indirect effects of aquatic-phase and
terrestrial-phase CRLF from effects to prey (shading added to indicate use where there is any LAA determination).
14
Table 4. Summary of Environmental Chemistry and Fate Parameters For Carbaryl 22
Table 5. Methods and rates of application of currently registered used of carbaryl in California 29
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Table 6. California Red-legged Frog Recovery Units with Overlapping Core Areas and Designated Critical Habitat.
35
Table 7. Carbaryl uses and their respective GIS landcovers used to depict the initial carbaryl action area for this
assessment 42
Table 8. Summary of Assessment Endpoints and Measures of Ecological Effects for Direct and Indirect Effects of
Carbaryl on the California Red-legged Frog 50
Table 9. Summary of Assessment Endpoints and Measures of Ecological Effect for Primary Constituent Elements of
Designated Critical Habitat 52
Table 10. Agency risk quotient (RQ) metrics and levels of concern (LOC) per risk class 61
Table 11. NAWQA 1999 -2005 data for carbaryl detections in CA surface waters with watersheds with different
landcover compositions. Data are distinguished by method of analysis 64
Table 12. PRZM scenario assignments and first application dates for the uses of carbaryl simulated for the aquatic
exposure assessment for the California CRLF Ecological Risk Assessment 69
Table 13. Carbaryl chemical input parameters for PE4 for carbaryl for the CRLF assessment 76
Table 14. Use patterns for the assessment of aquatic exposure from carbaryl to the CRLF 78
Table 15. One-in-ten-year carbaryl EECs for aquatic environments from the application of carbaryl to uses in
California 81
Table 16. Input parameters for foliar applications used to derive terrestrial EECs for carbaryl with T-REX 83
Table 17. Upper-bound Kenaga nomogram EECs for dietary- and dose-based exposures of the CRLF and its prey to
carbaryl 85
Table 18. Scenario and standard management input parameters for simulation of carbaryl in spray drift using
AgDisp with Gaussian far-field extension 87
Table 19. AgDrift Input parameters that vary with crop and formulation 88
Table 20. Distance from the edge of the treated field to get below LOC for crops with aerial or ground spray
application of carbaryl 89
Table 21. Summary of acute and chronic aquatic toxicity estimates using technical grade carbaryl 91
Table 22. Categories of Acute Toxicity for Aquatic Organisms 92
Table 23. Summary of acute and chronic toxicity data for terrestrial organisms exposed to carbaryl 100
Table 24. Categories for mammalian acute toxicity based on median lethal dose in mg per kilogram body weight
(parts per million) 100
Table 25. Categories of avian acute oral toxicity based on median lethal dose in milligrams per kilogram body
weight (parts per million) 100
Table 26. Categories of avian subacute dietary toxicity based on median lethal concentration in milligrams per
kilogram diet per day (parts per million) 101
Table 27. Rat acute 96-hr oral toxicity test data for formulated products of carbaryl 103
Table 28. Risk Quotient values for acute and chronic exposures directly to the CRLF in aquatic habitats 106
Table 29. RQ values for exposures to unicellular aquatic plants (diet of CRLF in tadpole life stage) 108
Table 30. Risk Quotient (RQ) values for acute and chronic exposures to aquatic invertebrates (prey of CRLF
juveniles and adults) in aquatic habitats 109
Table 31. Risk Quotient (RQ) values for exposures to aquatic plants (representing aquatic habitat) 110
Table 32. Acute and chronic, dietary-based RQs and dose-based RQs for direct effects to the terrestrial-phase CRLF.
RQs calculated using T-REX 112
Table 33. RQs for determining indirect effects to the terrestrial-phase CRLF through effects to potential prey items
(terrestrial invertebrates) 114
Table 34. Acute and chronic, acute dose-based RQs and chronic dietary-based RQs for prey items (small mammals)
of terrestrial-phase CRLF 115
Table 35. Likelihood of individual effect for each use of carbaryl for the aquatic-phase CRLF 118
Table 36. Revised dose-based RQs for 1.4 g CRLF consuming different food items. EECs calculated using T-
HERPS 122
Table 37. Revised dose-based RQs for 37 g CRLF consuming different food items. EECs calculated using T-
HERPS 123
Table 38. Revised dose-based RQs for 238 g CRLF consuming different food items. EECs calculated using T-
HERPS 124
Table 39. Revised acute dietary-based RQs for CRLF consuming different dietary items. EECs calculated using T-
HERPS 125
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Table 40. Revised chronic dietary-based RQs for CRLF consuming different dietary items. EECs calculated using T-
HERPS 127
Table 41. Carbaryl use-specific direct effects determinations1 for the CRLF (shading added to indicate use where
there is any LAA determination) 129
Table 42. Carbaryl use-specific indirect effects determinations1 based on effects to prey (shading added to indicate
use where there is any LAA determination) 134
Table 43. Down stream dilution factors used to determine extent of lotic action area for uses of carbaryl 138
Table 44. Quantitative results of spatial analysis of lotic aquatic action area relevant to carbaryl uses 138
Table 45. Spray drift distances used to determine extent of terrestrial action area for uses of carbaryl 139
Table 46. Overlap between CRLF habitat (core areas and critical habitat) and orchard/vineyard action area by
recovery unit (RU#) 145
Table 47. Overlap between CRLF habitat (core areas and critical habitat) and agricultural action area by recovery
unit (RU#) 145
Table 48. Overlap between CRLF habitat (core areas and critical habitat) and residential action area by recovery unit
(RU#) 146
Table 49. Overlap between CRLF habitat (core areas and critical habitat) and pasture action area by recovery unit
(RU#) 146
Table 50. Overlap between CRLF habitat (core areas and critical habitat) and forestry action area by recovery unit
(RU#) 146
Table 51. Carbaryl detections in air and precipitation samples taken in California 149
Table 52. l-in-10 year peak estimates of carbaryl concentrations in aquatic and terrestrial habitats resulting from
deposition of carbaryl at 0.756 ng/L carbaryl in rain 149
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1. Executive Summary
The purpose of this assessment is to evaluate potential direct and indirect effects on the
California red-legged frog (Rana aurora draytonii) (CRLF) arising from FIFRA regulatory
actions regarding use of carbaryl on agricultural and non-agricultural sites. In addition, this
assessment evaluates whether these actions can be expected to result in the destruction or
modification of the species' designated critical habitat. This assessment was completed in
accordance with the U.S. Fish and Wildlife Service (USFWS) and National Marine Fisheries
Service (NMFS) Endangered Species Consultation Handbook (USFWS/NMFS, 1998) and
procedures outlined in the Agency's Overview Document (U.S. EPA, 2004).
The CRLF was listed as a threatened species by USFWS 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 (USFWS 1996) in
California.
Carbaryl is registered for use as an insecticide on over 400 sites, including agriculture,
professional turf management and ornamental production, and residential settings. Carbaryl is
used on many agricultural sites including fruit and nut tree, fruit and vegetable, and grain crops
(including direct applications to water in rice production). Crops with the greatest annual use of
carbaryl include apples, pecans, grapes, alfalfa, oranges, and corn. Carbaryl is also used by
homeowners in residential settings for lawn care, gardening (vegetables and ornamentals), and
pet care (pet collars, powders and dips, in kennels, and on pet sleeping quarters). Carbaryl is
also used as an insecticide by nursery, landscape, and golf course industries on turf, annuals,
perennials, and shrubs. Additionally, carbaryl is used to thin fruit (inducing abscission of flower
buds) in orchards.
The environmental fate properties of carbaryl along with monitoring data identifying its presence
in surface waters and precipitation in California indicate that carbaryl has the potential to be
transported to non-target areas. In this assessment, transport of carbaryl from initial application
sties through runoff and spray drift are considered in deriving quantitative estimates of carbaryl
exposure to CRLF, its prey and its habitats.
Since CRLFs exist within aquatic and terrestrial habitats, exposure of the CRLF, its prey and its
habitats to carbaryl are assessed separately for the two habitats. Tier-II exposure models (PRZM
and EXAMS) are used to estimate high-end exposures to aquatic habitats resulting from runoff
and spray drift from different uses. The Tier-I Rice model is used to estimate high-end exposure
to aquatic habitats resulting from the direct application of carbaryl to rice production paddies.
Peak model-estimated environmental concentrations, resulting from different carbaryl uses,
range from 0.47 to 2579 |ig/L. These estimates are supplemented with analysis of available
California surface water monitoring data from U. S. Geological Survey's National Water Quality
Assessment (NAWQA) program and the California Department of Pesticide Regulation. The
maximum concentration of carbaryl reported by NAWQA from 1999-2005 for California surface
waters is 1.06 |ig/L. This value is three orders of magnitude less than the maximum model-
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estimated environmental concentration, but is within the range of environmental concentrations
estimated for different uses. The maximum concentration of carbaryl reported by the California
Department of Pesticide Regulation surface water database from 1999-2005 (0.31 |ig/L) is four
orders of magnitude less than the highest peak model-estimated environmental concentration.
To estimate carbaryl exposures to terrestrial-phase CRLF, its potential prey and its habitat
resulting from uses involving foliar applications, the T-REX model is used. To further
characterize exposures of terrestrial-phase CRLF to dietary and dose-based exposures of carbaryl
resulting from foliar applications, T-HERPS is used. AgDRIFT and AGDISP are also used to
estimate deposition of carbaryl on terrestrial habitats from spray drift.
The assessment endpoints for the CRLF include direct toxic effects on the survival, reproduction,
and growth of the CRLF itself, as well as indirect effects, such as reduction of the prey base
and/or modification of 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 toxicity information for
birds, which are used as a surrogate for terrestrial-phase amphibians. Given that the CRLF's prey
items and designated critical habitat requirements in the aquatic habitat are dependant on the
availability of freshwater aquatic invertebrates and aquatic plants, toxicity information for these
taxonomic groups is also discussed. In the terrestrial habitat, indirect effects due to depletion of
prey are assessed by considering effects to terrestrial insects, small terrestrial mammals and
frogs. Indirect effects due to modification of the terrestrial habitat could not be quantitatively
characterized since measurement endpoints were indiscreet (i.e, median effects concentrations
were less than the highest concentration tested) for terrestrial monocotyledenous and
dicotyledonous plants; however, indirect effects to the terrestrial habitat are qualitatively
characterized.
Carbaryl's primary mode of action as an insecticide is through inhibition of acetylcholine
esterase. Carbaryl is highly toxic to freshwater fish and very highly toxic to freshwater
invertebrates on an acute exposure basis. Toxicity categories for aquatic plants have not been
defined. If classification for animals were applied to aquatic plants, carbaryl would be classified
as moderately toxic to unicellular and vascular plants. The acute-to-chronic ratio (ACR)
adjusted no observed adverse effect concentrations (NOAECs) for the Atlantic salmon and
stonefly are 0.0068 and 0.0014 mg a.i./L, respectively. Carbaryl is practically nontoxic to birds
and moderately toxic to mammals on an acute exposure basis. Carbaryl is also very highly toxic
to honey bees on an acute exposure basis. Chronic exposures of mallard ducks to carbaryl in
reproduction studies indicate reproductive effects (decreased number of eggs) with a NOAEC of
300 mg/kg-diet/day. Chronic exposures of rats to carbaryl in a reproduction study indicate a
NOAEL for decreased pup survival of 75 mg/kg-diet/day. Plant toxicity testing with six
terrestrial plant species failed to provide a definitive toxicity endpoint at treatment levels
equivalent to a carbaryl application rate of to 0.8 lbs a.i./A (limit test EC25>0.8 lbs a.i./A);
however, carbaryl is used to thin fruit in orchards, and the chemical's structural similarity to the
plant auxin a-naphthalene acetic acid suggests it could affect terrestrial plants through its
potential activity as a plant auxin.
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Degradates of carbaryl include 1-naphthol. Comparison of available toxicity information for 1-
naphthol indicates roughly equivalent aquatic toxicity to that of the parent for the species tested;
however, 1-naphthol degrades more rapidly and is less mobile than the parent. There are no data
to indicate that 1-naphthol acts through the same mechanism of action as the parent compound.
Therefore, in this assessment, risks are determined based on carbaryl only.
Risk quotients (RQs) are derived as quantitative estimates of potential high-end risk. Acute and
chronic RQs are compared to the Agency's levels of concern (LOCs) for Federally-listed
threatened (listed) species to identify if carbaryl use within the action area has any direct or
indirect effect on the CRLF. Based on estimated environmental concentrations for the currently
registered uses of carbaryl, RQ values exceed the Agency's LOC for direct acute and chronic
effects on the CRLF; this represents a "may affect" determination. RQs exceed the LOC for
acute and chronic exposures to aquatic invertebrates and for acute exposures to terrestrial
invertebrates. Therefore, there is a potential to indirectly affect juvenile and adult CRLF due to
effects to the invertebrate prey base in aquatic and terrestrial habitats. The effects determination
for indirect effects to the CRLF due to effects to its prey base is "may affect." When considering
the prey of larger CRLF in aquatic and terrestrial habitats (e.g. frogs, fish and small mammals),
RQs for these taxa also exceed the LOC for acute and chronic exposures, resulting in a "may
affect" determination. RQ values for plants in aquatic habitats do not exceed the LOC, with the
exception of the direct application of carbaryl to water for use on rice. Risk of carbaryl use on
riparian and terrestrial vegetation cannot be discounted given the structural similarity of the
compound to a plant auxin, the chemical's use in abscission of flower buds in orchard crops and
reported ecological incidents involving terrestrial plants. Therefore, indirect effects to the CRLF
through effects to its habitat is a "may affect" determination.
All "may affect" determinations are further refined using available evidence to determine
whether they are "not likely to adversely affect" (NLAA) or "likely to adversely affect" (LAA)
the CRLF. Additional evidence is employed to distinguish between NLAA and LAA
determinations. This evidence includes available monitoring data and likelihood of individual
mortality analysis.
Refinement of all "may affect" determinations results in a "LAA" determination based on direct
effects to the CRLF, a "LAA" determination for indirect effects to the CRLF based on effects to
its prey and an "LAA" determination for indirect effects to the CRLF based on effects to its
habitat (Table 1). Use-specific determinations are defined in Tables 2 and 3. Consideration of
CRLF critical habitat indicates a determination of "habitat modification" for aquatic and
terrestrial habitats. The overall CRLF effects determination for carbaryl use is "LAA."
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Table 1. Carbaryl Effects Determination Summary for the California Red-legged Frog.
Assessment Endpoint
Effects
Determination1
Basis for Determination
Direct effects to CRLF
LAA
-Table 2 contains use specific determinations for acute and chronic exposures of the CRLF to carbaryl in aquatic and terrestrial habitats.
-Based on LOC exceedances, likelihood of individual effects analysis, and consideration of genus sensitivity distributions, there is potential for
mortality to CRLF based on acute exposures resulting from some uses of carbaryl.
-Consideration of LOC exceedances results in potential for reproductive effects in aquatic-phase CRLF resulting from chronic exposures from some
uses.
-Consideration of LOC exceedances in the context of refined exposure modeling results in potential for reproductive effects in terrestrial-phase
CRLF resulting from chronic exposures from some uses.
Indirect effects to
tadpole CRLF via
reduction of prey
(i.e., algae)
NE for all uses
except rice;
LAA for rice
-applications of carbaryl are not expected to affect this food source except for use on rice
-For rice, estimated exposure concentrations are 2X the level where 50% effects (to cell density) were observed in a laboratory study where algae
were exposed to carbaryl.
Indirect effects to
juvenile CRLF via
reduction of prey (i.e.,
invertebrates)
LAA
- Acute (RQ range: 0.3 - 1517) and chronic risk (RQ range: 6.2 - 5158) estimates for aquatic invertebrates and acute risk estimates for terrestrial
invertebrates (RQ range 2 - 293) indicate that all uses of carbaryl can potentially result in effects to invertebrates serving as prey to terrestrial-phase
CRLFs.
-Likelihood of individual mortality in aquatic and terrestrial invertebrates is 12-100% for all uses of uses.
- Table 3 contains use specific determinations.
Indirect effects to adult
CRLF via reduction of
prey
(i.e., invertebrates, fish,
frogs, mice)
LAA
-There is potential for effects to aquatic and terrestrial invertebrates due to acute and chronic exposures of carbaryl.
-Based on likelihood of individual analysis and species sensitivity distribution data for fish, and acute and chronic RQs, some uses of carbaryl have
the potential to indirectly affect the CRLF by influencing populations of fish and aquatic phase amphibians which serve as prey to the CRLF.
-The likelihood of individual mortality to mice ranges 20-100% for acute exposures to carbaryl. Acute and chronic exposures of carbaryl are likely
to affect mice.
-For some uses of carbaryl, chronic effects are possible for terrestrial-phase amphibians representing prey of CRLF.
-Overall, exposures of carbaryl have the potential to decrease populations of several types of prey of the CRLF, indicating that it is likely that uses of
carbaryl can adversely affect the CRLF through indirect effects to its prey.
- Table 3 contains use specific determinations.
Indirect effects to CRLF
via reduction of habitat
and/or primary
productivity
(i.e., plants)
LAA
-Based on RQs for unicellular and vascular plants inhabiting aquatic habitats, applications of carbaryl are not expected to affect these plants, except
in cases where there are direct applications to water for rice production.
-There are several reported incidents involving effects of carbaryl to plants.
- Carbaryl is used for fruit thinning, indicating that it has potential reproductive effects to plants; carbaryl is structurally related to the plant auxin a-
naphthalene acetic acid.
-Risks of carbaryl to riparian and terrestrial plants cannot be discounted.
-Risks of carbaryl to riparian and terrestrial plants cannot be quantified.
'LAA = likely to adversely affect; NLAA = not likely to adversely affect; NE = no effect
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Table 2. Carbaryl use-specific direct effects determinations1 for the Aquatic- and Terrestrial-phase CRLF
(shading added to indicate use where there is any LAA determination).
1 M-IM
Vt|iinlit- I'Iijm- ( Kl 1
1 rrrt">lrial Kl 1
Ai'lllr
(111<>¦ mi-
Ai'lllr
( hiMiiii
I Ionic lawn
M.AA
ni:
NLAA
l-'louor bods around buildings and lawns
NF
m:
NLAA
I.awns
I.AA
M.AA
Ornamentals
I.AA
M.AA
Parks, recreation areas, goll'courses, sod farms. commercial lawns
NF
m:
M.AA
Oranges, lemons, grapefruit. tangerines, etc.
I.AA
M.AA
Olives
I.AA
M.AA
Almonds, clieslnuls. pecans. filberts. walnuts, pistachio
I.AA
NLAA
Flowers and shrubs
XI.AA
m:
NLAA
Peaches, apricots, cherries, nectarines, plums, prunes
I.AA
NLAA
Asparagus
I.AA
NLAA
Apple, pear, crabapple. oriental pears
M.AA
NLAA
1oi|ual
M.AA
NLAA
Sweet corn
M.AA
NLAA
Cirapes. caneberries. blueberries
M.AA
NLAA
strawberries
I.AA
NLAA
Tomatoes, peppers, eggplant
M.AA
NLAA
peanuts
M.AA
m:
NLAA
Broccoli, caulillowor. cabbage, kohlrabi. Chinese cabbage, collards.
kale, mustard greens
I.AA
NLAA
Brussels sprouts and Hanover salad
I.AA
NLAA
Sweet potato
I.AA
NLAA
Field corn, popcorn
m:
m:
M.AA
Head and leal'lettuce, dandelion, endive, parsley, spinach. Swiss chard
I.AA
NLAA
sorghum
M.AA
m:
NLAA
Celery, prickly pear, garden beets, carrots
I .A A
NLAA
IIorseradish
I.AA
NLAA
Potato, parsnip, rutabaga, turnip (root)
I.AA
NLAA
radish
M.AA
m:
NLAA
Rice
I.AA
I.AA
NLAA
NLAA
Dry beans. I'rosh peas, dry peas, cow peas, southern peas (IVesh)
ni-
m:
NLAA
()kra
ne
m:
NLAA
Sugar beet
NLAA
NE
NLAA
NLAA
Alfalfa, birds foot trefoil, clover
NE
NE
NLAA
NLAA
Pasture
NE
NE
NLAA
NLAA
Grass for seed
NE
NE
NLAA
NLAA
Rangeland
NLAA
NE
NLAA
NLAA
Melon, cucumber, pumpkin, squash
NE
NE
NLAA
NLAA
Roses, herbaceous plants, woody plants
NLAA
NE
NLAA
NLAA
Rights-of-way. hedgerows, ditch banks, roadsides
M.AA
LAA
NLAA
NLAA
w asteland
LAA
LAA
NLAA
NLAA
Non-urban forests, tree plantations, Christmas trees, parks, rangeland
trees
NLAA
NE
NLAA
NLAA
Rural shelter bells
LAA
LAA
NLAA
NLAA
l icks, grasshoppers
M.AA
LAA
NLAA
LAA
*LAA = likely to adversely affect; NLAA = not likely to adversely affect; NE = no effect
Page 13 of 160
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Table 3. Carbaryl use-specific indirect effects determinations1 based on indirect effects of aquatic-phase and terrestrial-phase CRLF from effects to
prey (shading added to indicate use where there is any LAA determination).
Vt|inilit- lll\rllrhlalr-
1 i-nr-iiul
IllM-rlrhralrs
I Villli-i
Vt|lllllit' |lll!IM- nuns
illlll ll-ll
1 CIT(">lri:ll |>ll.lM' li nos
^iiiull M:iinniiiK
Willi-
( hiMiiii
Willi-
( hi'Miiic
Vt'ii 11*
( hiMiiii
Vnili-
( lininic
Homo lawn
NF
I.AA
I.AA
NI AA
ni:
NI AA
l-'louor bods around buildings and lawns
NF
ni:
I.AA
ni:
NF
NI AA
Fauns
NF
I.AA
NI AA
NI AA
Ornamonlals
NF
I.AA
I.AA
NI AA
Parks, recreation aroas. goU'coursos. sod larms.
commercial lawns
NF
I.AA
NI AA
NF
NI AA
Orangos. lomons. grapefruit. langorinos. olc.
NF
I .A A
NI AA
NI AA
Olives
NF
I.AA
NI AA
NI AA
Almonds, clioslnuls. pocans. lilberts. ualnuts.
pislacliio
NF
I.AA
NI AA
NI AA
Flowers and shrubs
NF
I.AA
NI AA
NF
NI AA
Peaches. apricols. cherries. noclarinos. plums, prunos
NF
I.AA
NI AA
NI AA
Asparagus
NF
I.AA
NI AA
NI AA
Applo. poar. crabapplo. orionlal poars
NF
I.AA
NI AA
NI AA
loqual
NF
FA A
NI AA
NI AA
Su ool corn
NF
I, A A
NI AA
NI AA
Cirapos. canoborrios. bluoborrios
NF
I.AA
NI AA
NI AA
strawberries
NF
I.AA
I.AA
NI AA
Tomaloos. poppors. oggplanl
NF
I.AA
NI AA
NI AA
poanuls
NF
I.AA
NI AA
NF
NI AA
Broccoli, caulillouer. cabbago. kohlrabi. Chinoso
cabbago. collards. kalo. muslard groons
NF
I.AA
NI AA
NI AA
Brussels sprouls and Ilanovor salad
NF
I.A A
I.AA
I.AA
NI AA
Sweet polalo
NF
I.AA
I.AA
NI AA
NI AA
Field corn, popcorn
NF
I.AA
I.AA
ni:
NF
NI AA
NI AA
Iload and leal'lettuce. dandelion, endive, parsley,
spinach. Su iss chard
NF
1 A A
FA A
I.AA
NI AA
sorghum
NF
I ,AA
I.AA
NI AA
NF
NI AA
Celery, prickly pear, garden heels, carrots
NF
I.AA
I.AA
NI AA
NI AA
Page 14 of 160
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I se
Algae
Aq usi tic InvertebI'iitcs
Acute
Chronic
Terrestrial
Invertebrates
(Acute)
Aquiitic-phiisc frogs
•¦lid tlsli
Acute
Ch ionic
Terrestriiil-phiise f rogs
Acute
Chronic
Sniiill Msimniiils
Acute
Horseradish
NE
LAA
LAA
LAA
NLAA
LAA
NLAA
LAA
LAA
Potato, parsnip, rutabaga, turnip (root)
NE
LAA
LAA
LAA
NLAA
LAA
NLAA
LAA
LAA
radish
NE
LAA
LAA
LAA
NLAA
NE
NLAA
LAA
LAA
Rice
LAA
LAA
LAA
LAA
LAA
LAA
NLAA
NLAA
LAA
Dry beans, fresh peas, dry peas, cow peas, southern
peas (fresh)
NE
NE
NE
NLAA
NLAA
LAA
Okra
NE
NE
NE
NLAA
NLAA
LAA
Sugar beet
NE
NLAA
NE
NLAA
NLAA
LAA
Alfalfa, birds foot trefoil, clover
NE
NE
NE
NLAA
NLAA
LAA
Pasture
NE
NLAA
NE
NLAA
NLAA
LAA
Grass for seed
NE
NE
NE
NLAA
NLAA
LAA
Ranneland
NE
NLAA
NE
NLAA
NLAA
LAA
Melon, cucumber, pumpkin, squash
NE
NE
NE
NLAA
NLAA
LAA
Roses, herbaceous plants, woody plants
NE
NLAA
NE
NLAA
NLAA
LAA
Righls-ol-waY. hedgerows, ditch banks, roadsides
NE
NLAA
LAA
NLAA
NLAA
LAA
wasteland
NE
NLAA
LAA
NLAA
NLAA
LAA
Non-urban I'oresls. tree plantations. Christmas trees,
parks, rangeland trees
NE
NLAA
NE
NLAA
NLAA
LAA
Rural shelter bells
NE
NLAA
LAA
NLAA
NLAA
LAA
l icks, grasshoppers
NE
NLAA
LAA
NLAA
LAA
LAA
'LAA = likely to adversely affect; NLAA = not
ikely to adversely affect; NE = no effect
Page 15 of 160
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When evaluating the significance of this risk assessment's direct/indirect and 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 area. In fact, given the assumptions of drift and downstream transport {i.e., attenuation
with distance), pesticide exposure and associated risks to the species and its resources are
expected to decrease with increasing distance away from the treated field or site of application.
Evaluation of the implication of this non-uniform distribution of risk to the species would require
information and assessment techniques that are not currently available. Examples of such
information and methodology required for this type of analysis 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 predictions of
individual effects to the proportion of the population extant within 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 aquatic- and 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 healthy
individuals at varying life stages. Such information could be used to establish biologically
relevant thresholds of effects 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 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 mortality,
growth or reproductive impairment immediately following exposure to the pesticide. The
degree to which repeated exposure events and the inherent demographic characteristics of the
prey population play into the extent to which prey resources may recover is not predictable.
An enhanced understanding of long-term prey responses to pesticide exposure would allow
for a more refined determination of the magnitude and duration of resource impairment, and
together with the information described above, a more complete prediction of effects to
individual frogs and potential modification to critical habitat.
Page 16 of 160
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2. Problem Formulation
Problem formulation provides a strategic framework for the risk assessment. By identifying the
important components of the problem, it focuses the assessment on the most relevant life history
stages, habitat components, chemical properties, exposure routes, and endpoints. The structure
of this risk assessment is based on guidance contained in U.S. EPA's Guidance for Ecological
Risk Assessment (U.S. EPA 1998), the Services' Endangered Species Consultation Handbook
(USFWS/NMFS 1998) and procedures outlined in the Overview Document (U.S. EPA 2004).
2.1 Purpose
The purpose of this endangered species assessment is to evaluate potential direct and indirect
effects on individuals of the federally threatened California red-legged frog (Rana aurora
draytonii) (CRLF) arising from FIFRA regulatory actions regarding use of carbaryl on root
crops, small fruits and berries, grapes, tree nuts, orchards, citrus, residential gardens (fruit and
vegetable), turf (commercial and residential), forage crops, forests and rangeland. Carbaryl is
also used as an insecticide on pets and for control of grasshoppers, adult mosquitoes, ticks and
fire ants. On orchards, carbaryl is also used to thin fruit. In addition, this assessment evaluates
whether these actions can be expected to result in the modification of the species' critical habitat.
Key biological information for the CRLF is included in Section 2.5, and designated critical
habitat information for the species is provided in Section 2.6 of this assessment. This ecological
risk assessment has been prepared as part of the Center for Biological Diversity (CBD) us. EPA
et al. (Case No. 02-1580-JSW(JL)) settlement agreement entered in the Federal District Court for
the Northern District of California on October 20, 2006.
In this endangered species assessment, direct and indirect effects to the CRLF and potential
modification to its critical habitat are evaluated in accordance with the methods (both screening
level and species-specific refinements, when appropriate) described in the Agency's Overview
Document (U.S. EPA 2004) and evaluated by the U. S. Fish and Wildlife Service (Williams and
Hogarth 2004).
In accordance with the Overview Document, provisions of the ESA, and the Services'
Endangered Species Consultation Handbook, the assessment of effects associated with
registrations of carbaryl are based on an action area. The action area is considered to be the area
directly or indirectly affected by the federal action, as indicated by the exceedance of Agency
Levels of Concern (LOCs) used to evaluate direct or indirect effects. It is acknowledged that the
action area for a national-level FIFRA regulatory decision associated with a use of carbaryl may
potentially involve numerous areas throughout the United States and its Territories. However,
for the purposes of this assessment, attention will be focused on relevant sections of the action
area including those geographic areas associated 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 for registration of carbaryl at the use sites described in this document to
affect CRLF individuals and/or result in the modification of designated CRLF critical habitat:
Page 17 of 160
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• "No effect";
• "May affect, but not likely to adversely affect"; or
• "May affect and likely to adversely affect".
Designated critical habitat identifies specific areas that have the physical and biological features,
(known as primary constituent elements or PCEs) essential to the conservation of listed species.
The PCEs for CRLFs are aquatic and upland areas where suitable breeding and non-breeding
aquatic habitat is located, interspersed with upland foraging and dispersal habitat (Section 2.6).
If the results of initial screening-level assessment methods 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 the FIFRA regulatory action regarding carbaryl
as it relates to this species and its designated critical habitat. If, however, direct or indirect
effects to individual CRLFs are anticipated and/or effects may impact the PCEs of the CRLF's
designated critical habitat, a preliminary "may affect" determination is made for the FIFRA
regulatory action regarding carbaryl.
If a determination is made that use of carbaryl within the action area(s) associated with the CRLF
"may affect" this species and/or its designated critical habitat, additional information is
considered to refine the potential for exposure and for effects to the CRLF and other taxonomic
groups upon which these species depend (e.g., aquatic and terrestrial vertebrates and
invertebrates, aquatic plants, riparian vegetation, etc.). Additional information, including spatial
analysis (to determine the overlay of CRLF habitat with carbaryl use) and further evaluation of
the potential impact of carbaryl on the PCEs is also used to determine whether modification 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 and/or the PCEs of its designated critical habitat. This information is presented as part of
the Risk Characterization in Section 5 of this document.
The Agency believes that the analysis of direct and indirect effects to listed species provides the
basis for an analysis of potential effects on the designated critical habitat. Because carbaryl is
expected to directly impact living organisms within the action area (defined in Section 2.7),
critical habitat analysis for carbaryl is limited in a practical sense to those PCEs of critical habitat
that are biological or that can be reasonably linked to biologically 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). Activities that may modify critical habitat are those that alter the PCEs and
jeopardize the continued existence of the species. Evaluation of actions related to use of carbaryl
that may alter the PCEs of the CRLF's critical habitat form the basis of the critical habitat impact
analysis. Actions that may affect the CRLF's designated critical habitat have been identified by
the Services and are discussed further in Section 2.6.
Page 18 of 160
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2.2 Scope
Carbaryl is a carbamate insecticide registered for control of a wide range of insect and other
arthropod pests on over 100 agricultural and non-crop use sites, including home and garden uses.
The chemical is also used to thin fruit in orchards.
The end result of the EPA pesticide registration process (the FIFRA regulatory action) is an
approved product label. The label is a legal document that stipulates how and where a given
pesticide may be used. Product labels (also known as end-use labels) describe the formulation
type (e.g., liquid or granular), acceptable methods of application, approved use sites, and any
restrictions on how applications may be conducted. Thus, the use or potential use of carbaryl in
accordance with the approved product labels for California is "the action" being assessed.
This ecological risk assessment is for currently registered uses of carbaryl 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.
This assessment quantitatively considers effects of exposures to carbaryl only. Carbaryl
degrades into one notable degradate, 1-naphthol. Available environmental fate data indicate that
1-naphthol degrades more rapidly and is less mobile than the parent. Toxicity data indicate that
1-naphthol is roughly equal to or less toxic than the parent compound depending on the species
tested. Since the degradate is no more toxic than the parent compound, the risk assessment
focused on carbaryl is considered protective for non-target species as the toxicity endpoints for
carbaryl are the most sensitive measured.
This assessment considers only the single active ingredient of carbaryl. However, the assessed
species and their environments may be exposed to multiple pesticides simultaneously.
Interactions of other toxic agents with carbaryl could result in additive effects, synergistic effects
or antagonistic effects. Evaluation of pesticide mixtures is beyond the scope of this assessment
because of the myriad factors that cannot be quantified based on the available data. Those
factors include identification of other possible co-contaminants and their concentrations,
differences in the pattern and duration of exposure among contaminants, and the differential
effects of other physical/chemical characteristics of the receiving waters (e.g. organic matter
present in sediment and suspended water). Evaluation of factors that could influence
additivity/synergism is beyond the scope of this assessment and is beyond the capabilities of the
available data to allow for an evaluation. However, it is acknowledged that not considering
mixtures could over- or under-estimate risks depending on the type of interaction and factors
discussed above. This assessment has however, analyzed the toxicity of formulated products
(including formulations involving more than one active ingredient) and determined that none of
the formulated products evaluated were more toxic than the technical grade active ingredient
data used for assessing both direct and indirect risks.
Page 19 of 160
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2.3 Previous Assessments
In March 2003, a revised environmental fate and ecological risk assessment was published in
support of the interim reregi strati on eligibility decision on carbaryl (USEPA 2004). The chapter
was revised to include additional ecological effect studies and to address concerns received
during the public comment phase of the reregi strati on process. The baseline risk assessment
concluded that for many of the registered uses of carbaryl, acute and chronic risk levels of
concern were exceeded for mammals and chronic risk levels of concern were exceeded for birds.
Citrus was the only use that exceeded the acute risk LOC for fish; however, most of the uses
exceeded the acute and chronic risk LOCs for aquatic invertebrates. Based on a single
acceptable study of green algae, none of the uses evaluated exceeded the acute risk LOC for
aquatic plants. No data were available to assess the risk of carbaryl to terrestrial plants; however
according to some labels, it may cause injury to tender foliage if applied to wet foliage or during
periods of high humidity and incident data suggested that both ornamental and agricultural crops
could be affected by carbaryl. Beneficial insects were sensitive to carbaryl and incident data
submitted subsequent to the publication of the ecological risk assessment indicate that a number
of bee kills have been associated with the use of carbaryl.
Although freshwater fish are typically used as surrogates for assessing the sensitivity of aquatic-
phase amphibians to chemicals, carbaryl has a relatively large amount of data available on the
effects of carbaryl on larval amphibians. These data were captured qualitatively in the baseline
assessment and the data indicate that across the species tested, amphibians are less sensitive to
carbaryl than fish. However, studies examining the interaction of carbaryl with aquatic
communities indicated that in some cases, carbaryl exposure could enhance the growth of larval
amphibians (tadpoles) through the elimination of zooplankton that compete with tadpoles for
food.
Because the Agency determined that carbaryl shares a common mechanism of toxicity with the
structurally-related N-methyl carbamate insecticides, a cumulative human health risk assessment
for the N-methyl carbamate insecticides was necessary before the Agency could make a final
determination of reregi strati on eligibility of carbaryl (USEPA 2007b).
As noted in the interim Reregi strati on Eligibility Decision (IRED) on carbaryl (USEPA 2004b),
EPA consulted with the U. S. Fish and Wildlife Service in 1989 regarding carbaryl impacts on
some endangered species (USFWS 1989). As a result, the U.S. Fish and Wildlife Service issued
a formal Biological Opinion which identified reasonable and prudent measures and alternatives
to mitigate effects of carbaryl use on endangered species.
EPA also consulted with the National Marine Fisheries Service concerning carbaryl effects on
endangered salmon and steelhead to determine the best processes to assess pesticide impacts on
endangered species. In its assessment, the Agency determined that the use of carbaryl may
affect 20 salmon and steelhead evolutionarily significant units (ESUs), may affect but is not
likely to adversely affect two ESUs and will have no effect on four ESUs (Turner 2003).
Page 20 of 160
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2.4 Stressor Source and Distribution
2.4.1 Environmental Fate and Transport Assessment
The following fate and transport description for carbaryl is consistent with the information
contained in the initial 2004 IRED (U.S. EPA, 2004b).
2.4.1.1 Hydrolysis
Carbaryl hydrolysis is strongly pH dependent. The compound is stable under acidic conditions
(pH 5) and degrades in neutral (pH 7) and alkaline (pH 9) systems with measured half-lives of 12
days and 0.13 days, respectively. The major degradation product was 1-naphthol which was
stable to further hydrolysis. (MRID 44759301; Figure 1). The registrant-submitted hydrolysis
data were used to generate the model input parameters.
Chapman and Cole (1982) measured half-lives of 14 days (pH 7.0) and 0.49 days (pH 8). Wolfe
et al. (1978) reported half-life values in natural pond waters of 30 days (pH 6.7) and 12 days (pH
7.2). They also estimated a minimum hydrolysis half-life in acidic conditions of 1600 days.
Armbrust and Crosby (1991) reported hydrolysis half-lives in filtered seawater of 1 day (pH 7.9)
and 0.96 day (pH 8.3).
OCONHCH3
OH
k
C02
Carbaryl
1 -naphthol
Carbon dioxide
Figure 1. Generalized degradation pathway of carbaryl.
2.4.1.2 Photolysis
The photolysis half-life is 45 hours in distilled water at pH 5.5. In filtered seawater, carbaryl
degraded rapidly to 1-naphthol under artificial sunlight (290-360 nm) with a half-life of 5 hours.
The degradation product, 1-naphthol, was degraded very rapidly with half-life of less than 1 hour
(Armbrust and Crosby, 1991). The data from the study submitted by the registrant (MRID
41982603) was used to generate the model input parameters.
Page 21 of 160
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Table 4. Summary of Environmental Chemistry and Fate Parameters For Carbaryl.
Parameter
Value
Reference
Selected Physical/Chemical Parameters
Molecular Weight
201.22 g/mol
Water Solubility
32 mg/L (ppm) at 20° C
Suntio, et al., 1988
Vapor pressure
1.36 10"7 mm Hg (25° C)
Ferrira and Seiber, 1981
Henry's Law Constant
1.28 x 10"8 atm m3 mol"1
Suntio, et al., 1988
Octanol/Water Partition Coefficient
(Kow)
229
Windholz et al., 1976
Persistence
Hydrolysis t1/2 pH 5
pH 7
pH 9
stable
12 days
3.2 hours
mrids 00163847, 44759301
Aqueous Photolysis t./2
21 days
mrid 41982603
Soil photolysis t./2
assumed stable
No valid data submitted
Aerobic Soil metabolism tlA
4 days in one sandy loam soil
mrid 42785101
Anaerobic Soil metabolism tlA
72 days
mrid 42785102
Aerobic Aquatic metabolismt'/i
4.9 days
mrid 43143401
Anaerobic Aquatic metabolism tlA
ti/2 = 72 days
mrid 42785102
Mobility/Adsorption-Desorption
Batch Equilibrium
K&c) =1.74 (207) - sandy loam
2.04 (249) - clay loam sediment
3.00 (211) - silt loam
3.52 (177) - silty clay loam
1/n values ranged from 0.78-0.84
mrid 43259301
Column Leaching
slightly mobile in columns (30-cm length) of
sandy loam, silty clay loam, silt loam, and loamy
sand soils
mrid 43320701
Field Dissipation
Forestry Dissipation
Foliar t1/2 = 21 days
Leaf Litter t1/2 = 75 days
Soil t1/2 = 65 days
MRID 43439801
2.4.1.3 Microbially-mediated processes
Carbaryl degrades fairly rapidly by microbial processes under aerobic conditions and more
slowly under anaerobic conditions. In a guideline study of aerobic soil metabolism, 11.2 mg/kg
carbaryl degraded with a half-life of 4.0 days in sandy loam soil incubated in the dark at 25°C
(MRID 42785101). The major degradate was 1-naphthol, which further degraded to non-
Page 22 of 160
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detectable levels within 14 days. In an aerobic aquatic metabolism study, 9.97 mg/L carbaryl
degraded with a half-life of 4.9 days in flooded clay-loam sediment in the dark at 2$ C (MRID
43143401). The major non-volatile degradate was 1-naphthol. Carbaryl degraded with a half-life
of 72.2 days in anaerobic aquatic sediment with an initial carbaryl concentration of about 10
mg/L; 1-naphthol was also identified as the major degradate. Minor degradates included 5-
hydroxy-l-naphthyl methylcarbamate, 4-hydroxy-l-naphthyl methylcarbamate, 1,5-
naphthalenediol, 1,4-naphthalenediol, l-naphthyl(hydroxymethyl)-carbamate, and 1,4-
naphthoquinone.
Liu, et al. (1981) studied carbaryl degradation in anaerobic and aerobic fermenters which were
spiked with a mixture of lake sediment, silt loam and domestic activated sludge and buffered to
pH 6.8. They reported abiotic degradation half-lives of 8.3 (aerobic) and 15.3 (anaerobic) days.
After correcting for abiotic controls, when carbaryl was used as the sole carbon source, they
found aerobic and anaerobic metabolism half-lives of 54 and 11.6 days, respectively. When
glucose and peptone were added co-metabolism aerobic and anaerobic metabolism, half-lives
were 7.6 and 6.1 days respectively.
A number of soil microorganisms have been identified which can degrade carbaryl, including:
Pseudomonas spp. (Chapalmadugu and Chaudhry, 1991; Larken and Day, 1986), Rhodoccus
spp. (Larkken and Day, 1986), Bacillus spp. (Rajagopal. et al., 1984), Arthrobacter spp. (Hayatsu
et al., 1999), and Achromobacter spp. (Karns et al., 1986). Some bacteria are capable of
complete degradation of carbaryl to CO2 (Chapalamadugu and Chaudhry, 1991) while, with
some species degradation of carbaryl stops at 1-naphthol. In soils it appears that a consortia of
bacteria are able to degrade parent and 1-naphthol completely to CO2. Proposed degradation
pathways proceed by using the methyl carbamate side chain as a carbon source, converting the
parent to 1-naphthol, which is then degraded through the intermediates salicylaldehyde, salicylic
acid, catechol, and gentisate to CO2 and water (Chapalamadugu and Chaudhry, 1991; Hayatsu et
al., 1999). Several studies have shown that bacteria isolated from soil exposed to carbofuran,
which is also a carbamate, can also degrade carbaryl indicating cross adaptation by
microorganisms allowing degradation of compounds with similar structure (Karns et al., 1986:
Chaudhry, et al., 1988). Carbaryl degradation utilizes enzyme systems which may or may not
degrade other carbamate compounds (Chapalamadugu and Chaudhry, 1991).
2.4.1.4 Mobility
Carbaryl is considered to be moderately mobile in soils. Based on batch sorption/ desorption
studies, the compound has Freundlich Kf values <3.52. Sorption is dependant on the soil organic
matter content and increases with increasing Koc.
Batch Adsorption/De sorption
Based on batch equilibrium experiments (MRID 43259301), carbaryl is mobile in soils. In silty
clay loam, sandy loam, loamy sand, and silt loam soils and clay loam sediment, mobility
decreased with increasing soil organic matter content. Kf values were 1.74 for the sandy loam
soil, 2.04 for the clay loam sediment, 3.00 for the silt loam soil, and 3.52 for the silty clay loam
soil. An adsorption Koc of 144 was estimated when a regression with a y-intercept was used.
Page 23 of 160
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When this model is used, there is a residual adsorption of 0.7 L kg"1 when there is no organic
matter present. This implies carbaryl has some ability to sorb directly to clay. This model has a
r2 of 0.94 and is significant at p<0.05. A model with no-intercept was also fit, and the Koc
calculated using this was 195; however, the r2 is only 0.81 and p = 0.069. Values of 1/n ranged
from 0.78-0.84; the closer this value is to 1, Kd is equivalent to Kf., relative to sorption. Sorption
showed significant hysteresis with Freundlich desorption constants (Kf(des)) values of 6.72 for
sandy loam soil, 6.78 for clay loam sediment, 6.89 for silt loam soil, and 7.66 for silty clay loam
soil. Values of 1/n ranged from 0.86-1.02. Literature data confirms that carbaryl is mobile.
Nkedi-Kizza and Brown (1998) reported Kf of 4.72 (1/n = 0.80) for soil with an organic content
of 590 mg/Kg. They found that sorption was lower on subsoils and attributed this to a lower
organic content. The Koc estimated using the no-intercept (195) was used for modeling as this is
how Koc is handled internally in both PRZM and EXAMS.
Column Leaching
In column leaching experiments (MRID 43320701), carbaryl residues were determined to be
slightly mobile in columns (30-cm length) of sandy loam, silty clay loam, silt loam, and loamy
sand soils treated with aged carbaryl residues. This disparity with the batch experiments may
possibly be explained by the relatively poor extraction recovery, by slow desorption kinetics and
by degradation during the aging period. Unextracted [14C] labeled residues in the soils prior to
leaching ranged from 19.0% of the recovered in the loamy sand soil to 39.7% in the silty clay
loam soil. The study author believed that 50% of the carbaryl applied to the soil had degraded
prior to leaching.
2.4.1.5 Field Dissipation
Studies of carbaryl dissipation in terrestrial, aquatic and forest environments have been
submitted by the registrant. In forest environments carbaryl was found to be moderately
persistent in soil (half-live = 65 days) and leaf litter (half-live = 75 days). However, the
submitted field and aquatic dissipation studies were determined to be unacceptable, and did not
provide useful information on movement and dissipation of carbaryl or its degradation products.
Field dissipation studies conducted in the 1960s and 1970s in terrestrial (Fiche/Master ID
000108961 and 00159337), aquatic (Fiche/Master ID 001439080, 0124378, 00159337,
00159338, 00159339) and forestry (Fiche/Master ID 00029738, 00159340, 00159341)
environments and submitted in the 1980's have been reexamined. When they were initially
reviewed they were not considered acceptable for a number of reasons including: sampling
frequency was not sufficient to allow calculation of dissipation rates, degradates were not
identified or quantified, soil, sediment and water were not sufficiently characterized, problems
with analytical method specificity and validity, insufficient sampling frequency and sampling
depth, lack of data on irrigation practices measured. These studies do not meet current levels of
scientific validity required to be considered acceptable and do not provide useful information on
field dissipation of carbaryl and its degradates. Scientifically valid field dissipation studies in
terrestrial, aquatic and forest environments are described below.
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Terrestrial Field Dissipation
Results of two field dissipation studies conducted in California and North Carolina were
submitted (MRID 41982605).
California site: Carbaryl dissipated with an observed initial half- life of <4 days from the upper
0.15 m of a plot of Sorrento silt loam soil planted to broccoli in California following five
applications at 2.24 kg a.i./ha/application (total 11.2 kg a.i./ha) of carbaryl; the applications, at 6-
10 day intervals, were made in March and April 1990. In the 0- to 0.15-m soil depth, carbaryl
was 0.673-1.25 |ig/g immediately following the first application, 1.51-2.38 |ig/g following the
second application, 2.03-2.21 |ig/g following the third application, 1.42-1.73 |ig/g following the
fourth application, and 0.603-1.06 |ig/g following the fifth application. Carbaryl was 0.065-0.212
|ig/g at 4 and 7 days after the final treatment, 0.068-0.097 |ig/g at 15 days, and <0.052 |ig/g at 33
and 61 days. In the 0.15- to 0.30-m soil depth, carbaryl was <0.05 |ig/g immediately after the
second, fourth, and fifth applications and <0.374 |ig/g immediately after the third application;
carbaryl was <0.015 |ig/g at all other sampling intervals. In the 0.30- to 0.45-m soil depth,
carbaryl was <0.038 |ig/g after each application, and <0.010 |ig/g at all other sampling intervals.
In the 0.45- to 0.90-m soil depths, carbaryl was sporadically detected at <0.026 |ig/g throughout
the application period, and was <0.010 |ig/g at all other sampling intervals. The formation and
decline of carbaryl degradates were not investigated.
North Carolina site: Carbaryl dissipated with an observed initial half-life of <7 days from the
upper 0.15 m of a plot of Norfolk sandy loam soil planted to sweet corn in North Carolina,
following one application at 7.11 kg a.i./ha of carbaryl on May 1, 1990. In the 0- to 0.15-m soil
depth, carbaryl was 3.72-7.30 |ig/g immediately after treatment, 0.145-0.379 |ig/g at 7 days,
0.036-0.105 |ig/g at 16 days, 0.017-0.043 |ig/g at 30 days, and <0.013 |ig/g at 62 days. Carbaryl
was sporadically detected at <0.015 ug/g in the 0.15- to 0.60-m soil depths, except carbaryl was
O.D6 ug/g in one of four samples from the 0.30- to 0.45-m depth at 7 days. Carbaryl was not
detected in the 0.60- to 0.90-m soil depths at any sampling interval. The formation and decline of
carbaryl degradates were not investigated. Rainfall plus irrigation totaled 53.1 mm through 7
days post-treatment (May 1-May 8, 1990), and 174 mm throughout the remainder of the study
(May I-July 2).
A freezer stability study was reportedly conducted, but the results past 90 days were not
submitted. There was apparently significant degradation within 90 days. Study samples were
analyzed as long as 8 months after collection, making the quality of the data highly questionable.
Degradates were not analyzed in either study. In the California study >80% of the applied
carbaryl apparently dissipated from the surface 15 cm between the final carbaryl application and
the next sampling interval (7 days after the final application). In the NC study > 90 % apparently
dissipated from the surface 15 cm between application and the next sampling event (7 days).
However, in both studies dissipation after 7 days suggested a half-life on the order of weeks. In
both studies rainfall and irrigation were less than evapotranspiration so the data can not be used
to assess the potential for carbaryl to leach into the subsurface. In the California study, irrigation
with water with a pH of 8.0 was applied 1-3 days after each pesticide application. Because
Page 25 of 160
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carbaryl hydrolysis is highly pH dependant (Ti/2 at pH 9 = 3.2 hours) this may have resulted in
an increase in the degradation rate, but higher pH irrigation waters are not uncommon in the
western United States. Carbaryl was not detected below the 0.90-m soil depth.
Aquatic Field Dissipation
Results of aquatic field dissipation studies conducted on rice in Texas and Mississippi were
submitted (MRID 43263001). The studies were evaluated and found to provide supporting data.
Frozen storage stability data were provided for only 6 months, although the water samples were
stored for up to 14 months and the soil samples were stored for up to 17.5 months prior to
analysis. In the six months of storage, carbaryl degraded an average of 34% in Texas water and
39% in water from Mississippi. The primary degradate, 1-naphthol, further degraded 50% in
water from Texas and 69% from Mississippi.
Carbaryl (1-naphthyl N-methylcarbamate) dissipated with observed half-lives of approximately
<1.5 days from the floodwater of plots of loam/sandy loam and clay loam/loam soils in Texas
and Mississippi which had been planted to rice, flooded, and then treated twice, at 5-day
intervals, at 1.65-1.81 kg a.i./ha/application with carbaryl (Sevin XLR Plus, 42.38%) ai F1C) in
June and July 1992. The plots were maintained with a 0.5- to 4.75-inch layer of irrigation water
through approximately 1 month after the second application, according to normal cultural
practices for rice growing. Carbaryl did not appear to leach below the 7.5-cm soil depth during
the study. In the floodwater, the degradate 1-naphthol dissipated to non-detectable concentrations
within 7-14 days after the second application; in the soil, 1-naphthol was not detected at any soil
depth at any sampling interval.
Forestry Field Dissipation
In a supplemental forestry field dissipation study (MRID 43439801) carbaryl was applied on a
pine forest site in Oregon. Carbaryl half-lives were found to be 21 days on foliage, 75 days in
leaf litter and 65 days in soil. At the time of treatment, the trees of primary interest (pine) were
3-8 feet tall. Carbaryl concentration was a maximum of 264 ppm in the pine foliage at 2 days
post-treatment, 28.7 ppm in the leaf litter at 92 days, 0.16 ppm in the upper 15 cm of litter-
covered soil at 62 days, and 1.14 ppm in the upper 15 cm of exposed soil at 2 days. Carbaryl
was detected in the leaf litter up to 365 days after treatment, and in the litter-covered soil up to
302 days after treatment. Carbaryl was <0.003 ppm in water and sediment from a pond and
stream located approximately 50 feet from the treated area.
Page 26 of 160
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2.4.1.6 Foliar Dissipation/Foliar Wash-off
Based on thirty acceptable studies (MRID 45860501), the mean foliar half-life of carbaryl was
determined to be 3.2 d. These studies were predominantly magnitude of residue studies used to
support the setting of tolerances for food as well as some other data from the open literature. A
set of criterion (described in detail in the EFED RED chapter, 2004b) for data quality and study
appropriateness were established to select those studies which were appropriate for making the
estimate. A value of 3.7 d was used for foliar degradation in estimating for terrestrial, aquatic
and drinking water exposure estimates. This value is the upper 90% confidence bound on the
mean value and is used as a model input parameter.
Two studies (Willis et al, 1988, Willis el al, 1996) were submitted by the registrant which could
be used to estimate the foliar wash-off rate which is an input parameter for PRZM. In the
absence of data, this parameter is usually set to 0.5. Wash-off coefficients estimated from these
two studies were 0.83 and 0.98 respectively with a mean of 0.91. In both these cases, the wash-
off coefficient was estimated from only two points, so no error could be estimated. The mean of
0.91 was used in the modeling.
2.4.1.7 Bioconcentration in Fish
Because of the low octanol/water partition coefficient, carbaryl is not expected to bioconcentrate
to a significant extent. Reported Kow values range from 65 to 229 (Bracha, and O'Brian, 1966;
Mount and Oehme, 1981; Windholz et al., 1976). A fish bioconcentration study (Chib, 1986,
Fiche/Master ID 00159342) suggested that bioconcentration factors (BCFs) were 14x in edible
tissue, 75x in visceral tissue and 45x in whole fish. Though the study does not meet current
acceptable standards, it does support the conclusion that significant bioconcentration is not
expected.
2.4.1.8 Atmospheric Transport
Potential transport mechanisms of carbaryl in air include spray drift, and secondary drift of
volatilized or soil-bound residues leading to deposition onto nearby or more distant ecosystems.
The magnitude of pesticide transport via secondary drift depends on the pesticide's ability to be
mobilized into air and its eventual removal through wet and dry deposition of gases/particles and
photochemical reactions in the atmosphere. A number of studies have documented atmospheric
transport and redeposition of pesticides from the Central Valley to the Sierra Nevada Mountains
(Fellers et al., 2004, Sparling et al., 2001, LeNoir et al., 1999, and McConnell et al., 1998).
Prevailing winds blow across the Central Valley eastward to the Sierra Nevada Mountains,
transporting airborne industrial and agricultural pollutants into Sierra Nevada ecosystems
(Fellers et al., 2004, LeNoir et al., 1999, and McConnell et al., 1998). Therefore,
physicochemical properties of the pesticide that describe its potential to enter the air from water
or soil (e.g., Henry's Law constant and vapor pressure), pesticide use, modeled estimated
concentrations in water and air, and available air monitoring data from the Central Valley and the
Sierra Nevada Mountains are considered in evaluating the potential for atmospheric transport of
carbaryl to habitat for the CRLF.
Page 27 of 160
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Carbaryl has been shown to be transported and deposited by atmospheric processes (Waite, et
al., 1995; Foreman, et al., 2000; Sanusi et al., 2000). As with all chemicals applied by aerial or
ground spray, spray drift can cause exposure to non-target organisms downwind. Vapor-phase
transport and particulate transport may carry the compound far from the area of application. In
the atmosphere, partitioning between particulate and gas phase is a function of temperature,
atmospheric transport distance and deposition are therefore a function of temperature. In general
though, given carbaryl's relatively rapid degradation, its potential for long-range atmospheric
transport is limited.
At this time, EFED does not have an approved model for estimating atmospheric transport of
pesticides and resulting exposure to aquatic organisms in areas receiving pesticide deposition
from the atmosphere. Potential mechanisms of transport of carbaryl to the atmosphere, such as
volatilization, wind erosion of soil, and spray drift, can only be discussed qualitatively. The
extent to which carbaryl will be deposited from the air to the action area is unknown. Potential
deposition of carbaryl in precipitation is discussed in section 5.2.6.1.3 of this assessment, but
based on the chemical's environmental fate characteristics wet deposition is expected to be
minimal.
2.4.2 Mechanism of Action
Carbaryl is an insecticide belonging to the N-methyl carbamate class of pesticides. Carbaryl is
a cholinesterase inhibitor that acts on animals on contact and upon ingestion by competing for
binding sites on the enzyme acetylcholine esterase, thus preventing the breakdown of the
neurotransmitter acetylcholine. The primary degradate, 1-naphthol does not inhibit acetyl
cholinesterase. Carbaryl is also used to thin fruit in orchards; its activity in the abscission of
flower buds may be related to its structural similarity to plant auxins, such as a-naphthalene
acetic acid.
2.4.3 Use Characterization
Carbaryl is nationally registered for over 115 uses in agriculture, professional turf management,
ornamental production, and residential settings (See Appendix A). Carbaryl also is registered for
use as a mosquito adulticide. Agricultural uses include tree fruit, nuts, fruit and vegetable, and
grain crops. Carbaryl is used by homeowners in residential settings for lawn care, gardening
(vegetables and ornamentals), and pet care (pet collars, powders, and dips, in kennels, and on pet
sleeping quarters). Carbaryl also is used by nursery, landscape, and golf course industries on turf,
annuals, perennials, and shrubs. Additionally, carbaryl is used to thin fruit in orchards to
enhance fruit size and enhance repeat bloom (http://www.umass.edu/fruitadvisor/NEAPMG/145-149.pdf ).
For assessment purposes, specific uses of carbaryl were grouped by similarity of crops and
application rates. Crop groups are given an alphabetic identification and a title. The crop groups
used in this assessment, as well as the specific uses which apply to the groups and their
application rate information are available in Table 5.
Page 28 of 160
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Table 5. Mel hods unci rates of application of currently registered used of carharyl in California.
( l op ( ¦ r<»|l|)
^lU'i ilii- uops im liiili-il in iliK
M;i\. tpp.
Kiilc
ill) ii.i. iitTt'i
M;i\. No. nl"
Vpplit'iiliiiii
lnlci\:il-
V |> |>lit:il ion
Mrlhoil
A: Home lawn
Home lawn
9.1
2
7
ground
B: Flower beds around
buildings
Flower beds around buildings and
lawns
8
25
3
Drop/broadcast
spreader
C: Lawns
Lawns
7.8
4
7
ground
D: Ornamentals
Ornamentals
7.8
4
7
ground
E: Parks
Parks, recreation areas, golf courses,
sod farms, commercial lawns
4
2
7
ground
F: Citrus
Oranges, lemons, grapefruit,
tangerines, etc.
16
1
NA
aerial
G: Olives
Olives
7.5
2
14
aerial
H: Almonds
Almonds, chestnuts, pecans, filberts,
walnuts, pistachio
5
3
7
aerial
I: Flowers
Flowers and shrubs
4.3
3
7
ground
J: Peaches
Peaches, apricots, cherries, nectarines,
plums, prunes
4
(5 dormant)
2
+ 1 dormant
15
aerial
K: Asparagus
Asparagus
Pre: 2
Post: 4
Pre: 3
Post: 1
Pre: 3
Post: NA
aerial
L: Apple
Apple, pear, crabapple, oriental pears
3
5
14
aerial
M: Loquat
loquat
3
5
14
aerial
N: Sweet corn
Sweet corn
2
8
3
aerial
O: Grapes
Grapes, caneberries, blueberries
2
5
7
aerial
P: Strawberries
strawberries
2
5
7
aerial
Q: Tomatoes
Tomatoes, peppers, eggplant
2
4
7
aerial
R: Peanuts
peanuts
2
4
7
aerial
S: Broccoli
Broccoli, cauliflower, cabbage,
kohlrabi, Chinese cabbage, collards,
kale, mustard greens
2
4
6
aerial
T: Brussels sprouts
Brussels sprouts and Hanover salad
2
4
6
aerial
U: Sweet potato
Sweet potato
2
4
7
aerial
V: Field corn
Field corn, popcorn
2
4
14
aerial
W: Lettuce, head
Head and leaf lettuce, dandelion,
endive, parsley, spinach, Swiss chard
2
3
7
aerial
X: Sorghum
sorghum
2
3
7
aerial
Y: Celery
Celery, prickly pear, garden beets,
carrots
2
3
7
aerial
Z: Horseradish
Horseradish
2
3
7
aerial
AA: Potato
Potato, parsnip, rutabaga, turnip (root)
2
3
7
aerial
AB: Radish
radish
2
3
7
aerial
AC: Rice
Rice
1.5
2
7
aerial
AD: Beans
Dry beans, fresh peas, dry peas, cow
peas, southern peas (fresh)
1.5
4
7
aerial
AE: Okra
Okra
1.5
4
6
ground
AF: Sugar beet
Sugar beet
1.5
2
14
aerial
AG: Alfalfa
Alfalfa, birds foot trefoil, clover
1.5
7
30
aerial
AH: Pasture
Pasture
1.5
2
14
aerial
AI: Grass for seed
Grass for seed
1.5
2
14
aerial
AJ: Rangeland
Rangeland
1
1
NS
aerial
AK: Melon
Melon, cucumber, pumpkin, squash
1
6
7
aerial
Page 29 of 160
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Crop Group
Specific crops included ill this
group
Max. App.
Rate
(lb a.i./acre)
Max. No. of
Apps.
Application
Intervals
(days)
Application
Method
AL: Roses
Roses, herbaceous plants, woody
plants
1
6
7
aerial
AM: Rights-of-way
Rights-of-way, hedgerows, ditch
banks, roadsides
1
2
14
aerial
AN: Wasteland
wasteland
1
2
14
aerial
AO: Non-urban forests
Non-urban forests, tree plantations,
Christmas trees, parks, rangeland trees
1
2
7
aerial
AP: Rural shelter belts
Rural shelter belts
1
2
7
aerial
AQ: Ticks
Ticks, grasshoppers
1
25
3
ground
As noted in the carbaryl IRED (USEPA 2004b), approximately 3.9 millions pounds of carbaryl
active ingredient are sold annually in the U. S.; with about half used in agriculture and half in
non-agricultural settings (per 1998 data). The amount of carbaryl usage in agriculture has
declined form an average of 1.9 million pounds of active ingredient per year from 1992 through
2001, to 1 to 1.5 million pounds of active ingredient in 2001. Figure 2 depicts the extent of
estimated annual carbaryl use nationally as of 2002. As of 2002, a total of 2,440,288 pounds of
carbaryl were applied annually; the highest (646,072 lbs) was applied to hay. Pecans (373,494
lbs) and apples (342,293 lbs) represented the second and third highest total pounds of carbaryl
applied.
CARBARYL - insecticide
2002 estimated annual agricultural use
Crops
Total
Percent
pounds applied
national use
other hay
646072
22.64
pecans
373494
13.09
apples
342293
11.99
citrus fruit
278504
9.76
soybeans
257502
9.02
corn
194981
6.83
grapes
112199
3.93
cherries
100890
3.54
peaches
70904
2.48
alfalfa hay
63449
2.22
Average annual use of
active ingredient
(pounds per square mile of agricultural
land in county)
~ no estimated use
~ 0.001 to 0.027
~ 0.028 to 0.094
~ 0.095 to 0.298
~ 0.299 to 1.031
¦ >=1.032
Figure 2. Historical Extent (2002) of carbaryl usage.
(Source htti>://ca.water.usgs.gov/i)nsi)/i)esticide use maps/show mai).i)hi)?vear=02&mai)=ni6006 )
Page 30 of 160
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From 2003-2005, the percentage of total carbaryl use in California was highest on oranges
(21.2% of total use), apples (8.2%), landscape maintenance (7.8%), rice (5.9%) olives (4.5%),
pistachios (4.4%), peaches (4.4%) and tomatoes (4.1%) (CDPR 2007a). The total annual average
for reported uses over this three year period was 211,645 lbs. Distribution of the carbaryl uses
from 2003-2005 on orchards and vineyards (including nuts and fruit), agricultural crops and non-
agricultural uses is depicted in Figure 3. Data are unavailable for residential uses of carbaryl,
since these data are not reported to the state. See Appendix B for more details on uses of
carbaryl in California over 2003-2005.
Figure 3. Distribution of reported mass of carbaryl applied during 2003-2005 in California by crop group.
Analysis of labeled use information is the critical first step in evaluating the federal action. The
current labels for carbaryl represent the FIFRA regulatory action; 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
modeling scenarios and inputs. A comprehensive list of current uses of carbaryl, along with the
methods and rates associated with applications of carbaryl is included in Appendix A. Uses that
could be modeled using the same application practices on the same scenario (for aquatic
exposure estimation) have been modeled as a group with one crop serving as a surrogate for the
group. The crop groups and their application practices are in Table 5. Rationales for the choices
of surrogates and groups are provided in Appendix A. Since only the use rates (i.e., pounds of
active ingredient applied, number of applications and reapplication interval) and not the scenario
(e.g., crop-specific soil types and application dates and weather data) are considered for
terrestrial exposure estimation, crop groupings need not be split out by scenario. Crop groups
(i.e. similar application rates) for terrestrial assessment are indicated by the code in parentheses
in Table 3. For spray drift assessment, since only the single application rate and the application
¦ orchards and vinyards
~ agricultural crops
~ non-agricultural uses
Page 31 of 160
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method (ground, air blast, or aerial) are considered, some of the terrestrial groupings can be
placed together. The groupings for spray drift assessment are in brackets.
For some use patterns, no limit was placed the maximum number of applications, the maximum
seasonal/annual rate or minimum application interval. Since these values are necessary for a use
pattern to be assessable, values for these two parameters must be assumed when they are not
specified on the label. If the minimum interval is not specified, three days has been used and
when maximum seasonal rate or number of application has not been specified, 25 applications
have been assumed. The use patterns, as assessed are in Table 5.
There are 13 use patterns for which carbaryl is registered that were not explicitly evaluated.
These are flax, home fruits and vegetables, cranberries, proso millet, lentils, soybeans, dry
southern peas, sunflower, tobacco, transplants, wheat, and adult mosquitoes. Cranberries, dry
southern peas, tobacco, and soybeans are not grown in California. Current carbaryl labels
specifically prohibit use on flax, home fruits and vegetables, oysters, proso millet, sunflowers,
and wheat in California. The transplants use pattern could not be evaluated because the label use
pattern could not be reduced to an aerial (pounds per acre) rate.
The mosquito adulticide use pattern was not evaluated separately because it is applied as an
aerosol. Since current assessment tools are expected to underestimate the distance aerosols will
actually drift, this use was not assessed separately. The absolute concentration at an any point in
the environment for this use pattern are not likely to exceed those for 1 lb-acre"1 application
patterns such as non-urban forests and wasteland, although the dispersion in the environment
may be greater as aerosols may have some increased propensity to drift as compared to non-
aerosol spray particles. Greater detail on the rationale for not considering these use patterns is
provided in Appendix A. Effects determinations associated with non-urban forests and
wasteland are assumed to be representative of carbaryl use as a mosquito adulticide.
The uses considered in this risk assessment represent all currently registered used according to a
review of all current labels. No other uses are relevant to this assessment. Any reported use,
such as may be seen in the CDPR PUR database, represent either historic uses that have been
cancelled, misreported uses, or misuse. Historical uses, misreported uses, and misuse are not
considered part of the federal action and, therefore, are not considered in this assessment.
2.5 Assessed Species
The CRLF was federally listed as a threatened species by USFWS effective June 24, 1996
(USFWS 1996). It is one of two subspecies of the red-legged frog and is the largest native frog
in the western United States (USFWS 2002). A brief summary of information regarding CRLF
distribution, reproduction, diet, and habitat requirements is provided in Sections 2.5.1 through
2.5.4, respectively. 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 designated by USFWS on April 13, 2006 (USFWS 2006;
71 FR 19244-19346). Further information on designated critical habitat for the CRLF is
provided in Section 2.6.
Page 32 of 160
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2.5.1 Distribution
The CRLF is endemic to California and Baja California (Mexico) and historically inhabited 46
counties in California including the Central Valley and both coastal and interior mountain ranges
(USFWS 1996). Its range has been reduced by about 70%, and the species currently resides in
22 counties in California (USFWS 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) (USFWS 2002).
Populations currently exist along the northern California coast, northern Transverse Ranges
(USFWS 2002), foothills of the Sierra Nevada (5-6 populations), and in southern California
south of Santa Barbara (two populations) (Fellers 2005a). Relatively larger numbers of CRLFs
are located between Marin and Santa Barbara Counties (Jennings and Hayes 1994). 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 (USFWS 1996). Occupied
drainages or watersheds include all bodies of water that support CRLFs (i.e., streams, creeks,
tributaries, associated natural and artificial ponds, and adjacent drainages), and habitats through
which CRLFs can move (i.e., riparian vegetation, uplands) (USFWS 2002).
The distribution of CRLFs within California is addressed in this assessment using four categories
of location including recovery units, core areas, designated critical habitat, and known
occurrences of the CRLF reported in the California Natural Diversity Database (CNDDB) that
are not included within core areas and/or designated critical habitat (see Figure 3). Recovery
units, core areas, and other known occurrences of the CRLF from the CNDDB are described in
further detail in this section, 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
management strategies. The recovery unit is primarily an administrative designation, and 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' historic and current range
and have been determined by USFWS 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 within the boundaries of the
recovery units. Additional information on CRLF occurrences from the CNDDB is used to cover
the current range of the species not included in core areas and/or designated critical habitat, but
within the recovery units.
Recovery Units
Eight recovery units have been established by USFWS for the CRLF. These areas are
considered essential to the recovery of the species, and the status of the CRLF "may be
considered within the smaller scale of the recovery units, as opposed to the statewide range"
(USFWS 2002). Recovery units reflect areas with similar conservation needs and population
statuses, and therefore, similar recovery goals. The eight units described for the CRLF are
delineated by watershed boundaries defined by US Geological Survey hydrologic units and are
Page 33 of 160
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limited to the elevational maximum for the species of 1,500 m above sea level. The eight
recovery units for the CRLF are listed in Table 3 and shown in Figure 3.
Core Areas
USFWS has designated 35 core areas across the eight recovery units to focus their recovery
efforts for the CRLF (see Figure 4). Table 6 summarizes the geographical relationship among
recovery units, core areas, and designated critical habitat. The core areas, which are distributed
throughout portions of the historic and current range of the species, represent areas that allow for
long-term viability of existing populations and reestablishment of populations within historic
range. These areas were selected because they: 1) contain existing viable populations; or 2) they
contribute to the connectivity of other habitat areas (USFWS 2002). Core area protection and
enhancement are vital for maintenance and expansion of the CRLF's distribution and population
throughout its range.
For purposes of this assessment, designated critical habitat, currently occupied (post-1985) core
areas, and additional known occurrences of the CRLF from the CNDDB are considered. Each
type of locational information is evaluated within the broader context of recovery units. For
example, if no labeled uses of carbaryl occur (or if labeled uses occur at predicted exposures less
than the Agency's LOCs) within an entire recovery unit, that particular recovery unit would not
be included in the action area and a "no effect" determination would be made for all designated
critical habitat, currently occupied core areas, and other known CNDDB occurrences within that
recovery unit. Historically occupied sections of the core areas are not evaluated as part of this
assessment because the USFWS Recovery Plan (USFWS 2002) indicates that CRLFs are
extirpated from these areas. A summary of currently and historically occupied core areas is
provided in Table 3 (currently occupied core areas are bolded). While core areas are considered
essential for recovery of the CRLF, core areas are not federally-designated critical habitat,
although designated critical habitat is generally contained within these core recovery areas. It
should be noted, however, that several critical habitat units are located outside of the core areas,
but within the recovery units. The focus of this assessment is currently occupied core areas,
designated critical habitat, and other known CNDDB CRLF occurrences within the recovery
units. Federally-designated critical habitat for the CRLF is further explained in Section 2.6.
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 occurrences of CRLFs outside of the currently occupied core areas
and designated critical habitat is considered in defining the current range of the CRLF. See:
http://www.dfg.ca.gov/bdb/html/cnddb info.html for additional information on the CNDDB.
Page 34 of 160
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Table 6. California Red-legged Frog Recovery Units with Overlapping Core Areas and Designated Critical
Habitat.
Recovery Unit1
(Figure 4)
Core Areas 2'7 (Figure 4)
Critical Habitat
Units J
Currently
Occupied
(post-1985) 4
Historically
Occupied 4
Sierra Nevada Foothills
and Central Valley (1)
(eastern boundary is the
1,500m elevation line)
Cottonwood Creek (partial) (8)
—
~
Feather River (1)
BUT-1A-B
¦/
Yuba River-S. Fork Feather River
(2)
YUB-1
¦/
NEV-16
Traverse Creek/Middle Fork
American River/Rubicon (3)
-
¦/
Consumnes River (4)
ELD-1
¦/
S. Fork Calaveras River (5)
—
¦/
Tuolumne River (6)
—
¦/
Piney Creek (7)
—
¦/
East San Francisco Bay
(partial)(16)
-
¦/
North Coast Range
Foothills and Western
Sacramento River Valley
(2)
Cottonwood Creek (8)
-
¦/
Putah Creek-Cache Creek (9)
-
¦/
Jameson Canyon - Lower Napa
Valley (partial) (15)
-
¦/
Belvedere Lagoon (partial) (14)
-
¦/
Pt. Reyes Peninsula (partial) (13)
-
¦/
North Coast and North
San Francisco Bay (3)
Putah Creek-Cache Creek (partial) (9)
-
¦/
Lake Berryessa Tributaries (10)
NAP-1
¦/
Upper Sonoma Creek (11)
-
¦/
Petaluma Creek-Sonoma Creek
(12)
-
¦/
Pt. Reyes Peninsula (13)
MRN-1, MRN-2
¦/
Belvedere Lagoon (14)
—
¦/
Jameson Canyon-Lower Napa
River (15)
SOL-1
¦/
South and East San
Francisco Bay (4)
—
CCS-1A6
East San Francisco Bay (partial)
(16)
ALA-1A, ALA-IB,
STC-1B
¦/
STC-1A6
South San Francisco Bay (partial)
(18)
SNM-1A
¦/
Central Coast (5)
South San Francisco Bay (partial)
(18)
SNM-1A, SNM-2C,
SCZ-1
¦/
Watsonville Slough- Elkhorn
Slough (partial) (19)
SCZ-2 5
¦/
Carmel River-Santa Lucia (20)
MNT-2
¦/
Estero Bay (22)
-
¦/
—
SLO-86
Arroyo Grande Creek (23)
—
¦/
Santa Maria River-Santa Ynez
River (24)
-
¦/
Diablo Range and Salinas
Valley (6)
East San Francisco Bay (partial)
(16)
MER-1A-B, STC-
1B
¦/
SNB-16, SNB-26
Santa Clara Valley (17)
-
¦/
V*7 X *11 r, , r)1 1
¦/
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Slough (partial)(19)
Carmel River-Santa Lucia
(partial)(20)
--
¦/
Gablan Range (21)
SNB-3
¦/
Estrella River (28)
SLO-1A-B
¦/
Northern Transverse
Ranges and Tehachapi
Mountains (7)
—
SLO-86
Santa Maria River-Santa Ynez
River (24)
STB-4, STB-5,
STB-7
¦/
Sisquoc River (25)
STB-1, STB-3
¦/
Ventura River-Santa Clara River
(26)
VEN-1, VEN-2,
VEN-3
¦/
LOS-16
Southern Transverse and
Peninsular Ranges (8)
Santa Monica Bay-Ventura Coastal
Streams (27)
--
¦/
San Gabriel Mountain (29)
—
¦/
Forks of the Mojave (30)
—
¦/
Santa Ana Mountain (31)
—
¦/
Santa Rosa Plateau (32)
—
¦/
San Luis Rey (33)
—
¦/
Sweetwater (34)
—
¦/
Laguna Mountain (35)
-
¦/
1 Recovery units designated by the USFWS (USFWS 2000, pg 49).
2 Core areas designated by the USFWS (USFWS 2000, pg 51).
3 Critical habitat units designated by the USFWS on April 13, 2006 (USFWS 2006, 71 FR 19244-19346).
4 Currently occupied (post-1985) and historically occupied core areas as designated by the USFWS (USFWS 2002, pg 54).
5 Critical habitat unit where identified threats specifically included pesticides or agricultural runoff (USFWS 2002).
6 Critical habitat units that are outside of core areas, but within recovery units.
7 Currently occupied core areas that are included in this effects determination are bolded.
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Legend
^ Recovery Unit Boundaries
| Currently Occupied Core Areas
| Critical Habitat
| CNDDB Occurence Sections
| County Boundaries q
45 90 180 Miles
_i i I i i i I
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'1'
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-Elkliorn 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*
3 5. LagunaMountain
* Core areas that were historically occupied by the California red-
legged frog are not included in the map
Figure 4. Recovery Unit, Core Area, Critical
Habitat, and Occurrence Designations for CRLF.
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2.5.2 Reproduction
CRLFs breed primarily in ponds; however, they may also breed in quiescent streams, marshes,
and lagoons (Fellers 2005a). According to the Recovery Plan (USFWS 2002), CRLFs breed
from November through late April. Peaks in spawning activity vary geographically; Fellers
(2005b) reports peak spawning 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 approximately 2000
to 6000 eggs ranging in size between 2 and 2.8 mm (Jennings and Hayes 1994). 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 associated with the larval stage (particularly
through predation by fish); however, predation 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 September (Jennings and Hayes 1994, USFWS 2002);
tadpoles have been observed to over-winter (delay metamorphosis until the following year)
(Fellers 2005b, USFWS 2002). Males reach sexual maturity at 2 years, and females reach sexual
maturity at 3 years of age; adults have been reported to live 8 to 10 years (USFWS 2002).
Figure 5 depicts CRLF annual reproductive timing.
Month
J
F
M
A
M
J
J
A
S
o
N
D
Young
Juveniles:
Tadpoles*
Breeding/Egg
Masses
Adults and
Juveniles
Figure 5. 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 and consuming diatoms, algae, and detritus (USFWS 2002). Tadpoles filter
and entrap suspended algae (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 and terrestrial habitats, and their diet differs greatly
from that of larvae. The main food source for juvenile aquatic- and terrestrial-phase CRLFs is
thought to be aquatic and terrestrial invertebrates found along the shoreline and on the water
surface. Hayes and 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 species were larval alderflies (Sialis cf. califomica), pillbugs (Armadilliadrium vulgare),
Page 38 of 160
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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 cannibalistic, and
consume fish. For larger CRLFs, over 50% of the prey mass may consists of vertebrates such as
mice, frogs, and fish, although aquatic and terrestrial invertebrates were the most numerous food
items (Hayes and Tennant 1985). For adults, feeding activity takes place primarily at night; for
juveniles feeding occurs during the day and at night (Hayes and Tennant 1985).
2.5.4 Habitat
CRLFs require aquatic habitat for breeding, but also use other habitat types including riparian
and upland areas throughout their life cycle. CRLF use of their environment varies; they may
complete their entire life cycle in a particular habitat or they may utilize multiple habitat types.
Overall, populations are most likely to exist where multiple breeding areas are embedded within
varying habitats used for dispersal (USFWS 2002). Generally, CRLFs utilize habitat with
perennial or near-perennial water (Jennings et al. 1997), and dense vegetation close to water and
shading water of moderate depth are habitat features that appear especially important for CRLF
(Hayes and Jennings 1988).
Breeding sites include streams, deep pools, backwaters within streams 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 near deep (0.7 m) still or slow moving
water surrounded by dense vegetation (USFWS 2002); however, the largest number of tadpoles
have been found in shallower pools (0.26 - 0.5 m) (Reis, 1999). Data indicate that CRLFs do
not frequently inhabit vernal pools, as conditions in these habitats generally are not suitable
(Hayes and Jennings 1988).
CRLFs also frequently breed in artificial impoundments such as stock ponds, although additional
research is needed to identify habitat requirements within artificial ponds (USFWS 2002). Adult
CRLFs use dense, shrubby, or emergent vegetation closely associated with deep-water pools
bordered with cattails and dense stands of overhanging vegetation
(http://www.fws.gov/endangered/features/rl frog/rlfrog.html#whereY
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 depends on moisture, composition of the plant community, and presence of
pools and backwater 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 riparian vegetation for up to 77 days (USFWS 2002).
During 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 debris, and agricultural features (UWFWS 2002). According to Jennings and Hayes
(1994), CRLFs also use small 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).
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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 USFWS (USFWS 2006; FR 51 19244-19346). A summary of the 34 critical
habitat units relative to USFWS-designated recovery units and core areas (previously discussed
in Section 2.5.1) is provided in Table 2.a.
'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 exist, 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 conservation 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 through
prohibition against destruction or adverse modification with regard to actions carried out, funded,
or authorized by a federal Agency. Section 7 requires consultation on federal actions that are
likely to result in the modification of critical habitat.
To be included in a critical habitat designation, the habitat must be 'essential to the conservation
of the species.' Critical habitat designations identify, to the extent known using the best
scientific and commercial data available, habitat areas that provide essential life cycle needs of
the species or areas that contain certain primary constituent elements (PCEs) (as defined in 50
CFR 414.12(b)). PCEs include, but are not limited to, space for individual and population
growth and for normal behavior; food, water, air, light, minerals, or other nutritional or
physiological requirements; cover or shelter; sites for breeding, reproduction, rearing (or
development) of offspring; and habitats that are protected from disturbance or are representative
of the historic geographical and ecological distributions of a species. The designated 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.
Please note that a more complete description of these habitat types is provided in Attachment 1.
Occupied habitat may be included in the critical habitat only if essential features within the
habitat may require special management or protection. Therefore, USFWS does not include
areas where existing management is sufficient 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 range would be inadequate to ensure the conservation of the
species. For the CRLF, all designated critical habitat 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 designating
critical habitat for the CRLF includes a special rule exempting routine ranching activities
associated with livestock ranching from incidental take prohibitions. The purpose of this
Page 40 of 160
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exemption is to promote the conservation of rangelands, which could be beneficial to the CRLF,
and to reduce the rate of conversion to other land uses that are incompatible with CRLF
conservation. Please see Attachment 1 for a full explanation on this special rule.
USFWS has established modification standards for designated critical habitat (USFWS 2006).
Activities that may modify critical habitat are those that alter the PCEs and jeopardize the
continued existence of the species. Evaluation of actions related to use of carbaryl that may alter
the PCEs of the CRLF's critical habitat form the basis of the critical habitat impact analysis.
According to USFWS (2006), activities that may affect critical habitat and therefore result in
effects to the CRLF include, but are not limited to the following:
(1) Significant alteration of water chemistry or temperature to levels beyond the tolerances
of the CRLF that result in direct or cumulative effects to individuals and their life-
cycles.
(2) Significant increase in sediment deposition within the stream channel or pond or
disturbance of upland foraging and dispersal habitat that could result in elimination or
reduction of habitat necessary for the growth and reproduction of the CRLF by
increasing the sediment deposition to levels that would affect their ability to complete
their life cycles.
(3) Significant alteration of channel/pond morphology 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 could also lead to increased sedimentation and degradation in water quality to
levels that are beyond the CRLF's tolerances.
(4) Elimination of upland foraging and/or aestivating habitat or dispersal habitat.
(5) Introduction, spread, or augmentation of non-native aquatic species in stream segments
or ponds used by the CRLF.
(6) 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 species provides the basis for an analysis of potential effects on the designated
critical habitat. Because carbaryl is expected to directly impact living organisms within the
action area, critical habitat analysis for carbaryl is limited in a practical sense to those PCEs of
critical habitat that are biological or that can be reasonably linked to biologically mediated
processes.
2.7 Action Area
For listed species assessment purposes, the action 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 carbaryl is likely to encompass considerable portions of the United States based on its 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 habitat
within the state of California. Deriving the geographical extent of this portion of the action area
Page 41 of 160
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is the product of consideration of the types of effects that carbaryl may be expected to have on
the environment, the exposure levels to carbaryl that are associated with those effects, and the
best available information concerning the use of carbaryl and its fate and transport within the
state of California.
The definition of action area requires a stepwise approach that begins with an understanding of
the federal action. The federal action is defined by the currently labeled uses for carbaryl. An
analysis of labeled uses and review of available product labels was completed. This analysis
indicates that the following uses are considered as part of the federal action evaluated in this
assessment: home lawns and gardens, parks, citrus, olives, almonds, flowers, peaches,
asparagus, apples, loquat, sweet and field corn, grapes, strawberries, tomatoes, eggplant, peanuts,
broccoli, Brussels sprouts, sweet potato, sorghum, celery, horseradish, potato, radish, rice, beans,
okra, sugar beets, alfalfa, pasture, grass for seed, rangeland, melons, roses, rights-of-way,
wasteland, non-urban forests, rural shelter belts and ticks.
After determination of which uses will be assessed, an evaluation of the potential "footprint" of
the use pattern is determined. This "footprint" represents the initial area of concern and is
typically based on available land cover data. Local land cover data available for the state of
California were analyzed to refine the understanding of potential carbaryl uses. The initial area
of concern is defined as all land cover types that represent the labeled uses described above. The
initial area of concern is represented by 1) agricultural landcovers, which are assumed to
represent vegetable and non-orchard fruit crops as well as ornamental crops; 2) orchard and
vineyard landcovers; (3) residential; (4) pasture; (5) non-urban forests. The specific uses which
correspond to each of these landcovers are depicted in Table 7. Maps representing the land cover
types that make up the initial areas of concern for these separate uses are depicted in Figures 6-
10. These maps represent the areas that may be directly affected by the federal action.
Table 7. Carbaryl uses and their respective GIS landcovers used to depict the initial carbaryl action area for
this assessment.
GIS Landcover
Uses
Orchard/vineyard
citrus, olives, almonds, chestnuts, pecans, filberts, walnuts, pistachios,
peaches, apricots, cherries, nectarines, plums, prunes, pears, crabapples,
oriental pears, apple, loquat, grapes
agricultural lands
asparagus, corn, strawberries, tomatoes, eggplant, peanuts, broccoli,
Brussels sprouts, sweet potato, corn, lettuce, dandelion, endive, parsley,
spinach, Swiss chard, sorghum, celery, horseradish, potato, parsnip,
rutabaga, turnip, radish, rice, dry beans, fresh peas, dry peas, cow peas,
southern peas, okra, sugar beet, alfalfa, birds foot trefoil, clover, melon,
cucumber, pumpkin, squash, grass for seed, rural shelter belts,
ornamentals, flowers, roses, peppers, cauliflower, cabbage, kohlrabi,
Chinese cabbage, collards, kale, mustard greens, Hanover salad
residential (urban)
flower beds around buildings, roses, home lawn, lawns, parks,
recreational areas, golf courses, sod farms, commercial lawns, rights-of-
way, hedgerows, ditch banks, roadsides, ticks, grasshoppers
pasture
pasture, rangeland
non-urban forests
Forestry, tree plantations, Christmas trees, parks, rangeland trees
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Once the initial area of concern is defined, the next step is to compare the extent of that area with
the results of the screening level risk assessment. In this assessment, transport of carbaryl
through runoff and spray drift is considered in deriving quantitative estimates of carbaryl
exposure to CRLF, its prey and its habitats.
Since this screening level risk assessment defines taxa that are predicted to be exposed through
runoff and drift to carbaryl at concentrations above the Agency's Levels of Concern (LOC),
there is need to expand the action area to include areas that are affected indirectly by this federal
action. Two methods are employed to define the areas indirectly affected by the federal action,
and thus the total action area. These are the down stream dilution assessment for determining the
extent of the affected lotic aquatic habitats (flowing water) and the spray drift assessment for
determining the extent of the affected terrestrial habitats. In order to define the final action areas
relevant to uses of carbaryl, it is necessary to combine areas directly affected, as well as aquatic
and terrestrial habitats indirectly affected by the federal action. It is assumed that lentic (standing
water) aquatic habitats (e.g. ponds, pools, marshes) overlapping with the terrestrial areas are also
indirectly affected by the federal action. The analysis of areas indirectly affected by the
federal action, as well as the determination of the final action area for carbaryl is described
in the risk discussion (Section 5.2.5). Additional analysis related to the intersection of the
carbaryl action area and CRLF habitat used in determining the final action area is described in
Appendix C.
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Compiled from California County boundaries (ESRI, 2002),
USDA National Agriculture Statistical Service (NASS.2002)
Gap Analysis Program Orchard/Vineyard Landcover (GAP)
National Land Cover Database (NLCD) (MRLC.2001)
Map created by U.S. Environmental Protection Agency,
Office of Pesticides Programs, Environmental Fate and
Effects Division. April 11, 2007.
Projection: Albers Equal Area Conic USGS,
North American Datum of 1983 (NAD 1983)
Figure 6. Initial action area for crops described by orchard/vineyard landcover which corresponds to
potential carbaryl use sites. This map represents the area potentially directly affected by the federal action.
Page 44 of 160
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Legend
Agricultural La rid cove
County Boundary
90 45 0
90 Miles
Compiled from California County boundaries (ESRI, 2002),
USDA National Agriculture Statistical Service (NASS.2002)
Gap Analysis Program Orchard/Vineyard Landcover (GAP)
National Land Cover Database (NLCD) (MRLC, 2001)
Map created by U.S. Environmental Protection Agency,
Office of Pesticides Programs, Environmental Fate and
Effects Division. April 11, 2007.
Projection: Albers Equal Area Conic USGS,
North American Datum of 1983 (NAD 1983)
Figure 7. Initial action area for crops described by agricultural landcover which corresponds to potential
carbaryl lithium use sites. This map represents the area potentially directly affected by the federal action.
Page 45 of 160
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Legend
County Boundary
Residential areas
90
45
0
90 Miles
Compiled from California County boundaries (ESRI.2002),
USDA National Agriculture Statistical Service (NASS.2002)
Gap Analysis Program Orchard/Vineyard Landcover (GAP)
National Land Cover Database (NLCD) (MRLC,2001)
Map created by U.S. Environmental Protection Agency,
Office of Pesticides Programs, Environmental Fate and
Effects Division. April 11, 2007.
Projection: Albers Equal Area Conic USGS,
North American Datum of 1983 (NAD 1983)
Figure 8. Initial action area for crops described by residential landcover which corresponds to potential
carbaryl use sites. This map represents the area potentially directly affected by the federal action.
Page 46 of 160
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Compiled from California County boundaries (ESRI.2002),
USDA National Agriculture Statistical Service (NASS.2002)
Gap Analysis Program Orchard/Vineyard Landcover (GAP)
National Land Cover Database (NLCD) (MRLC,2001)
Map created by U.S. Environmental Protection Agency,
Office of Pesticides Programs, Environmental Fate and
Effects Division. April 11, 2007.
Projection: Albers Equal Area Conic USGS,
North American Datum of 1983 (NAD 1983)
Figure 9. Initial action area for crops described by pasture landcover which corresponds to potential carbaryl
use sites. This map represents the area potentially directly affected by the federal action.
Page 47 of 160
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Compiled from California County boundaries (ESRI. 2002),
USDA National Agriculture Statistical Service (NASS.2002)
Gap Analysis Program Orchard/Vineyard Landcover (GAP)
National Land Cover Database (NLCD) (MRLC,2001)
Map created by U.S. Environmental Protection Agency,
Office of Pesticides Programs, Environmental Fate and
Effects Division. April 11, 2007.
Projection: Albers Equal Area Conic USGS,
North American Datum of 1983 (NAD 1983)
Figure 10. Initial action area for crops described by non-urban forest landcover which corresponds to
potential carbaryl use sites. This map represents the area potentially directly affected by the federal action.
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2.8 Assessment Endpoints and Measures of Ecological Effect
Assessment endpoints are defined as "explicit expressions of the actual environmental value that
is to be protected" (USEPA 1992). Selection of the assessment 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,. water bodies, riparian
vegetation, and upland and dispersal habitats), the migration pathways of carbaryl (e.g., runoff,
spray drift, etc.), and the routes by which ecological receptors are exposed to the pesticide (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 and/or
modification of its habitat. In addition, potential modification of 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 effect," defined as changes in the attributes of an assessment endpoint or
changes in a surrogate entity or attribute in response to exposure to a pesticide. Specific
measures of ecological effect are generally evaluated based on acute and chronic toxicity
information from registrant-submitted guideline tests that are performed on a limited number of
organisms. Additional ecological effects data from the open literature are also considered.
A complete discussion of all the toxicity data available for this risk assessment, including
resulting measures of ecological effect selected for each taxonomic group of concern, is included
in Section 4 of this document. A summary of the assessment endpoints and measures of
ecological effect selected to characterize potential assessed direct and indirect CRLF risks
associated with exposure to carbaryl is provided in Table 8.
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Table 8. Summary of Assessment Endpoints and Measures of Ecological Effects for Direct and Indirect
Effects of Carbaryl on the California Red-legged Frog.
Assessment Endpoint | Measures of Ecological Effects
Aquatic Phase
(eggs, larvae, tadpoles, juveniles, and adults)'1
1. Survival, growth, and reproduction of CRLF
individuals via direct effects on aquatic phases
la. Atlantic salmon LC50
lb. Atlantic salmon NOAECd
2. Survival, growth, and reproduction of CRLF
individuals via effects to food supply (i.e., freshwater
invertebrates, non-vascular plants)
2a. Stonefly acute EC50
2b. Stonefly chronic NOAECd
2c. Algae EC50
3. Survival, growth, and reproduction of CRLF
individuals via indirect effects on habitat, cover, and/or
primary productivity (i.e., aquatic plant community)
3a. Non-vascular plant acute EC50 (freshwater algae or
diatom, or ECOTOX non-vascular)
4. Survival, growth, and reproduction of CRLF
individuals via effects to riparian vegetation, required to
maintain acceptable water quality and habitat in ponds
and streams comprising the species' current range.
4a. Tier 1 vegetative vigor studies used qualitatively in
conjunction with incident data and the use of carbaryl to
intentionally affect the growth of plants.
Terrestrial Phase
(Juveniles and adults)
5. Survival, growth, and reproduction of CRLF
individuals via direct effects on terrestrial phase adults
and juveniles
5a. Mallard acute LD50
5b. Mallard subacute LC50
5b. Mallard chronic NOAEC
6. Survival, growth, and reproduction of CRLF
individuals via effects on prey (i.e., terrestrial
invertebrates, small terrestrial vertebrates, including
mammals and terrestrial phase amphibians)
6a. Honeybee acute contact LD50
6b. Most sensitive terrestrial mammal acute LD50
6c. Most sensitive terrestrial mammal chronic NOAEC
6d. Mallard acute LD50
6e. Mallard subacute LC50
6f. Mallard chronic NOAEC
7. Survival, growth, and reproduction of CRLF
individuals via indirect effects on habitat (i.e., riparian
vegetation)
7a. Tier 1 vegetative vigor studies used qualitatively in
conjunction with incident data and the use of carbaryl to
intentionally affect the growth of plants.
3 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.
b Birds are used as surrogates for terrestrial phase amphibians.
c Although the most sensitive toxicity value is initially used to evaluate potential indirect effects, sensitivity distribution is used (if
sufficient data are available) to evaluate the potential impact to food items of the CRLF.
d Estimated using acute-to-chronic ratio.
2.8.2 Assessment Endpoints for Designated Critical Habitat
As previously discussed, designated critical habitat is assessed to evaluate actions related to the
use of carbaryl 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 may jeopardize 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 listed species associated with the critical habitat) and those for which carbaryl effects data are
available.
Assessment endpoints and measures of ecological effect selected to characterize potential
modification to designated critical habitat associated with exposure to carbaryl are provided in
Table 9. Adverse modification to the critical habitat of the CRLF includes the following, as
specified by USFWS (2006) and previously discussed in Section 2.6:
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1. Alteration of water chemistry/quality including temperature, turbidity, and oxygen
content necessary for normal growth and viability of juvenile and adult CRLFs.
2. Alteration of chemical characteristics necessary 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 foraging and dispersal habitat.
4. Significant alteration of channel/pond morphology or geometry.
5. Elimination of upland foraging and/or aestivating habitat, as well as 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.
Measures of such possible effects by labeled use of carbaryl on critical habitat of the CRLF are
described in Table 9. 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 habitat are based on the modification standard established by
USFWS (2006).
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Table 9. Summary of Assessment Endpoints and Measures of Ecological Effect for Primary Constituent
Elements of Designated Critical Habitat.
Assessmelll l lldp.iinl I Measures "1 lll'iilii^kal riliil
.\(|ii:i 1 ic-Phust- PCI'.s
(A(|U;ilk liivi'dill^ ll;il>il;il ;iml A(|li;ilk \iin-l}reedill» ll;il>il;il)
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.
a. Most sensitive aquatic plant EC50
b. Tier 1 vegetative vigor studies used qualitatively in conjunction
with incident data and the use of carbaryl to intentionally affect
the growth of 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.*
a. Non-vascular plant acute EC50 (freshwater algae)
b. Tier 1 vegetative vigor studies used qualitatively in conjunction
with incident data and the use of carbaryl to intentionally affect
the growth of plants.
Alteration of other chemical characteristics necessary for
normal growth and viability of CRLFs and their food source.
a. Atlantic salmon acute LC50
b. Atlantic salmon chronic NOAEC**
c. Stonefly acute EC50
d. Stonefly chronic NOAEC**
Reduction and/or modification of aquatic-based food sources
for pre-metamorphs (e.g., algae)
a. Algae EC50
Terrestrial-Phase PC.Es
(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
a. Distribution of EC25 values for monocots (seedling emergence,
vegetative vigor)
b. Distribution of EC25 values for dicots (seedling emergence,
vegetative vigor)
c. Most sensitive food source acute EC5o/LC5o and NOAEC values
for terrestrial vertebrates (mammals) and invertebrates, birds or
terrestrial-phase amphibians, and freshwater fish.
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
Reduction and/or modification of food sources for terrestrial
phase juveniles and adults
Alteration of chemical characteristics necessary for normal
growth and viability of juvenile and adult CRLFs and their
food source.
• Physico-chemical water quality parameters such as salinity, pH, and hardness are not evaluated because these processes
are not biologically mediated and, therefore, are not relevant to the endpoints included in this assessment.
2.9 Conceptual Model
2.9.1 Risk Hypotheses
Risk hypotheses are specific assumptions about potential 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, 1998). For this assessment, the risk is stressor-linked, where the
stressor is the release of carbaryl to the environment. The following risk hypotheses are
presumed for this endangered species assessment:
• Labeled uses of carbaryl within the action area may directly affect the CRLF by causing
mortality or by affecting growth or fecundity;
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• Labeled uses of carbaryl within the action area may indirectly affect the CRLF by
reducing or changing the composition of food supply;
• Labeled uses of carbaryl within the action area may indirectly affect the CRLF and/or
modify 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;
• Labeled uses of carbaryl within the action area may indirectly affect the CRLF and/or
modify designated critical habitat by reducing or changing the composition of the
terrestrial plant community {i.e., riparian habitat) required to maintain acceptable water
quality and habitat in the ponds and streams comprising the species' current range and
designated critical habitat;
• Labeled uses of carbaryl within the action area may modify the designated critical habitat
of the CRLF by reducing or changing breeding and non-breeding aquatic habitat (via
modification of water quality parameters, habitat morphology, and/or sedimentation);
• Labeled uses of carbaryl within the action area may modify the designated critical habitat
of the CRLF by reducing the food supply required for normal growth and viability of
juvenile and adult CRLFs;
• Labeled uses of carbaryl within the action area may modify 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.
• Labeled uses of carbaryl within the action area may modify the designated critical habitat
of the CRLF by reducing or changing 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.
• Labeled uses of carbaryl within the action area may modify 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 stressor (carbaryl), release mechanisms, biological receptor types, and effects
endpoints of potential concern. The conceptual models for aquatic and terrestrial phases of the
CRLF are shown in Figures 11 and 12, and the conceptual models for the aquatic and terrestrial
PCE components of critical habitat are shown in Figures 13 and 14. Exposure routes shown in
dashed lines are not quantitatively considered because the resulting exposures are expected to be
so low as not to cause effects to the CRLF.
The environmental fate properties of carbaryl along with monitoring data identifying its presence
in surface waters, air and precipitation in California indicate that runoff, spray drift, volatilization
and limited atmospheric transport and deposition represent potential transport mechanisms of
carbaryl to the aquatic and terrestrial habitats of the CRLF. These transport properties {e.g.
sources) are depicted in the conceptual models below (Figures 11-14) along with the receptors
of concern and the potential attribute changes in the receptors due to exposures to carbaryl.
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Stressor
Source
Exposure
Media
Receptors
Attribute
Change
Figure 11. Conceptual model for potential effects of carbaryl on the aquatic phase of the California red-
legged frog.
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Stressor
Source
Exposure
Media
Carbaryl applied to use site
-|^Spraydrif^J-
-Dermal uptake/Ingestion
1
Runoff
Soil
Root
Terrestrial/riparian plants
grasses/forbs, fruit, seeds
(trees, shrubs)
uptake ^ |
Long range
atmospheric
transport
• Wet/dry deposition -4*-
Receptors
Red-legged Frog
Juvenile
Adult
Ingestion
-~Ingestion
-~ Ingestion ^
Mammals
Attribute
Change
Individual organisms
Reduced survival
Reduced growth
Reduced reproduction
Food chain
Reduction in prey
Habitat integrity
Reduction in primary productivity
Reduced cover
Community change
Figure 12. Conceptual model for the potential effects of carbaryl on the terrestrial phase of the California
red-legged frog.
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Figure 13. Conceptual model for the potential effects of carbaryl on aquatic components of the California
red-legged frog critical habitat.
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Stressor
Source
Exposure
Media and
Receptors
Carbaryl applied to use site
Spray drift |-
-Dermal uptake/Inge stion
I Runoff I
7
Terrestrial plants
grasses/forbs, fruit, seeds
(trees, shrubs)
Root uptake
Soil
V
¦ Wet/dry deposition
Long range
atmospheric
transport
T
Inge^ion
Attribute
Change
Red-legged Frog
Juvenile
Adult
~
Individual organisms
Reduced survival
Reduced growth
Reduced reproduction
Ingestion
Habitat
PCEs
±
Other chemical
characteristics
Adversely modified
chemical characteristics
^¦Ingestion
Ingestion
i ; [
~f MammalT]
Population
Reduced survival
Reduced growth
Reduced reproduction
Food resources
Reduction in food
sources
Community
Reduced seedling emergence or
vegetative vigor (Distribution)
Elimination and/or disturbance of
upland or dispersal habitat
Reduction in primary productivity
Reduced shelter
Restrict movement
Figure 14. Conceptual model for the potential effects of carbaryl on terrestrial components of the California
red-legged frog critical habitat.
2.10 Analysis Plan
In order to address the risk hypothesis, the potential for effects on the CRLF, its prey and its
habitat is estimated. In the following sections, the use, environmental fate, and ecological effects
of carbaryl are characterized and integrated to assess the risks. This was accomplished using a
risk quotient (ratio of exposure concentration to effects concentration) approach. Although risk
is often defined as the likelihood and magnitude of ecological effects, the risk quotient-based
approach does not provide a quantitative estimate of likelihood and/or magnitude of an effect.
However, as outlined in the Overview Document (USEPA 2004), the likelihood of effects to
individual organisms from particular uses of carbaryl is estimated using the probit dose-response
slope and either the level of concern (discussed below) or actual calculated risk quotient value.
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2.10.1. Measures to Evaluate the Risk Hypothesis and Conceptual Model
2.10.1.1. Measures of Exposure
The environmental fate properties of carbaryl along with monitoring data identifying its presence
in surface water, in air and in precipitation in California indicate that spray drift, volatilization,
atmospheric transport and subsequent deposition represent potential transport mechanisms of
carbaryl to the aquatic and terrestrial habitats of the CRLF. In this assessment, transport of
carbaryl through runoff and spray drift is considered in deriving quantitative estimates of
carbaryl exposure to CRLF, its prey and its habitats. Although volatilization of carbaryl from
treated areas resulting in atmospheric transport and deposition represent relevant transport
pathways leading to exposure of the CRLF and its habitats, adequate tools are unavailable at this
time to quantify exposures through these pathways. Therefore, volatilization, atmospheric
transport and wet and dry deposition from the atmosphere are only discussed qualitatively in this
assessment.
Measures of exposure are based on aquatic and terrestrial models that predict estimated
environmental concentrations (EECs) of carbaryl using maximum labeled application rates and
methods. The models used to predict aquatic EECs are the Pesticide Root Zone Model coupled
with the Exposure Analysis Model System (PRZM/EXAMS). The model used to predict
terrestrial EECs on food items was T-REX. These models were parameterized using relevant
reviewed registrant-submitted environmental fate data.
PRZM (v3.12beta, May 24, 2001) and EXAMS (v2.98.04, Aug. 18, 2002) are screening
simulation models coupled with the input shell pe4v01.pl (Aug.8, 2003) to generate daily
exposures and l-in-10 year EECs of carbaryl that may occur in surface water bodies adjacent to
application sites receiving carbaryl through runoff and spray drift. 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. The standard scenario used
for ecological pesticide assessments assumes application to a 10-hectare agricultural field that
drains into an adjacent 1-hectare water body, 2 meters deep (20,000 m3 volume) with no outlet.
PRZM/EXAMS was used to estimate screening-level exposure of aquatic organisms to carbaryl.
The measure of exposure for aquatic species is the l-in-10 year return peak or rolling mean
concentration. The l-in-10 year peak is used for estimating acute exposures of direct effects 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 l-in-10-year 60-day mean is used for
assessing chronic exposure to the CRLF and fish and frogs serving as prey items; the l-in-10-
year 21-day mean is used for assessing chronic exposure for aquatic invertebrates, which are also
potential prey items.
The Tier I Rice Model (Version 1.0) is used for estimating surface water exposure from the use
of carbaryl in rice paddies. This model relies on an equilibrium partitioning concept to provide
conservative estimates of environmental concentrations resulting from application of pesticides
to rice paddies. When a pesticide is applied to a rice paddy, the model assumes that it will
instantaneously partition between a water phase and a sediment phase (Orrick and Young 2007).
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Exposure estimates for 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 (version 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 95th percentile of
residue values from actual field measurements (Hoerger and Kenega, 1972). The Fletcher et al.
(1994) modifications to the Kenega nomograph are based on measured field residues from 249
published research papers, including information on 118 species of plants, 121 pesticides, and 17
chemical classes. These modifications represent the upper bound of the expanded data set. For
modeling purposes, direct exposures of the CRLF to carbaryl through contaminated food are
estimated using the EECs for the small bird (20 g) which consumes small insects. Dietary-based
and 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 were used because these categories represent the
largest RQs of the size and dietary categories in T-REX that are appropriate surrogates for the
CRLF and one of its prey items. Estimated exposures of terrestrial insects to carbaryl are bound
by using the dietary based EECs for small insects and large insects.
Birds are currently used as surrogates for terrestrial-phase CRLF. However, amphibians are
poikilotherms (body temperature varies with environmental temperature) while birds are
homeotherms (temperature is regulated, constant, and largely independent of environmental
temperatures). Therefore, amphibians 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 dietary intake basis, assuming similar caloric content of the food
items. Therefore, the use of avian food intake allometric equation as a surrogate to amphibians is
likely to result in an over-estimation of exposure and risk for reptiles and 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.
Two spray drift models, AGDISP and AgDRIFT were used to assess exposures of terrestrial
phase CRLF and its prey to carbaryl deposited in spray drift. AGDisp (version 8.13; dated
12/14/2004) (Teske and Curbishley, 2003) is used to simulate aerial and ground applications
using the Gaussian far-field extension. AgDrift (version 2.01; dated 5/24/2001) is used to
simulate spray blast applications to orchard crops.
2.10.1.2. Measures of Effect
Data identified in Section 2.8 are used as measures 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 USEPA, Office of Research and Development, and the
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National Health and Environmental Effects Research Laboratory's Mid-Continent Ecology
Division (ECOTOX, 2006).
The assessment of risk for direct effects to the CRLF makes the assumption that avian toxicity is
similar to terrestrial-phase CRLF. The same assumption is made for fish and aquatic-phase
CRLF. Aquatic invertebrates and algae represent potential prey of the CRLF in the aquatic
habitat. Aquatic plants and semi-aquatic plants represent habitat of CRLF. Terrestrial
invertebrates and small mammals represent potential prey of the CRLF in the terrestrial habitat.
The acute measures of effect used for animals in this assessment are the LD50, LC50 and EC50.
The acronym "LD" stands for "Lethal Dose", and LD50 is the amount of a material, given all at
once, that is estimated to cause the death of 50% of the test organisms. The acronym "LC" stands
for "Lethal Concentration" and LC50 is the concentration of a chemical that is estimated to kill
50% of the test organisms. The acronym "EC" stands for "Effective Concentration" and the
EC50 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. The acronym "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 (adverse) effects on test organisms. The NOAEC {i.e., "No-Observed-
Adverse-Effect-Concentration") is the highest test concentration at which none of the observed
effects were statistically different from the control. The NOEC is the No-Observed-Effects-
Concentration. For non-listed plants, only acute exposures are assessed {i.e., EC25 for terrestrial
plants and EC50 for aquatic plants).
2.10.1.3. Integration of Exposure and Effects
Risk characterization is the integration of exposure and ecological effects characterization to
determine the potential ecological risk from the use of carbaryl on fruits, nuts, vegetables and
ornamentals, and the likelihood of direct and indirect effects to CRLF in aquatic and terrestrial
habitats. The exposure and toxicity effects data are integrated in order to evaluate the risks of
ecological effects on non-target species. For the assessment of carbaryl risks, the risk quotient
(RQ) method is used to compare exposure and measured toxicity values. EECs are divided by
acute and chronic toxicity values. The resulting RQs are then compared to the Agency's levels
of concern (LOCs) (USEPA, 2004) (see Table 10). These criteria are used to indicate when
carbaryl's uses, as directed on the label, have the potential to cause direct or indirect effects to
the CRLF.
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Table 10. Agency risk quotient (RQ) metrics and levels of concern (LOC) per risk class.
Risk Class
Description
RQ
LOC
Aquatic Habitats
Acute Listed
Species
CRLF may be potentially affected by use by direct or indirect effects.
Peak EEC/EC501
0.05
Chronic Listed
Species
Potential for chronic risk to CRLF through direct or indirect effects. Indirect
effects represented by effects to invertebrates, which represent potential prey.
60-day EEC/NOEC
(CRLF)
21-day EEC/NOEC
(invertebrates)
1
Non-Listed
Potential for effects in non-listed plants.
Peak EEC/EC50
1
Terrestrial Habitats
Acute Listed
Species
CRLF may be potentially affected by use by direct or indirect effects.
Dietary EEC 2/LC50
Or
Dose EEC 2/LD50
0.1
Acute Listed
Species
Potential effects to terrestrial invertebrates. CRLF may be potentially
affected by use by direct or indirect effects.
EEC 2/LD50
0.05
Chronic Listed
Species
Potential for chronic risk to CRLF through direct or indirect effects. Indirect
effects represented by effects to small mammals, which represent potential
prey.
EEC 2/NOAEC
1
Non-Listed
Potential for effects in non-listed plants.
Peak EEC/EC25
1
1 LC5o or EC50.
2 Based on upper-bound Kenaga values.
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3. Exposure Assessment
3.1 Aquatic Exposure Assessment
3.1.1 Existing Water Monitoring Data for California
EFED finalized the Environmental Fate and Ecological Risk assessment for carbaryl in 2003
(USEPA 2003). The IRED document for carbaryl (USEPA 2004b) was published for comment
in 2004, and EFED completed a response to those comments in 2005 (USEPA 2005). Since that
time, additional carbaryl monitoring data were obtained and are summarized below. In addition,
data specific to California are described. These data include United States Geological Survey's
(USGS) National Water Quality Assessment (NAWQA) and the CDPR Surface Water Database.
In addition, observed trends in carbaryl concentrations in national surface waters are discussed.
3.1.1.1. National NAWQA Data (2000-2005)
In 2003, EFED reported that carbaryl was the second most widely detected insecticide in surface
water in the U. S. Geological Survey's (USGS) National Water Quality Assessment (NAWQA)
monitoring program (USGS 2007). Although this monitoring does not target specific chemicals,
carbaryl was detected in 46% of 36 NAWQA study units from 1991 - 1998. Much of the data in
the NAWQA database are amended with an "E" qualifier to indicate uncertainty found in the
analysis. Typically this uncertainty is because the concentration is beyond the limit of the
calibration curve for the analytical instrumentation; thus a high reported concentration is in fact
high; however, it is a less precise estimate than those concentration that lie within the calibration
curve. In the 2003 assessment of NAQWA data, 1,067 (21%) out of 5,198 surface water samples
had detections greater than the minimum detectable limit. The maximum reported carbaryl
concentration was 5.5 |ig/L across all sites. For samples with positive detections the mean
concentration was 0.11 |ig/L, with a standard deviation of 0.43 (J,g/L. In a summary of pesticide
occurrence and concentrations for 40 NAWQA stream sites within primarily agricultural basins,
carbaryl was detected in 11% of the samples (N = 1,001) with a maximum concentration of 1.5
Hg/L.
In a report released in 2006 summarizing pesticide results from NAWQA from 1992 - 2001
(USGS 2006), carbaryl is listed as one of the 14 most frequently detected pesticide compounds in
surface water and one of the 3 most frequently detected insecticides. Carbaryl was detected in
50% of urban samples over this time period. The majority of carbaryl concentrations detected
were low with 35% of the urban samples (and 70% of the detections) less than 0.1 |ig/L.
Detection frequencies in agricultural and mixed-land use streams were lower (10% and 17%,
respectively), and concentrations associated with those land uses were almost all less than 0.1
Hg/L-
For this assessment NAWQA carbaryl data in the USGS data warehouse from 1999 - 2005 were
specifically reviewed. A total of 11,732 samples were collected in US waters in that timeframe
and analyzed for carbaryl, with 29% of all samples reporting a detection greater than the
minimum detection limit. For samples with detections, the mean carbaryl concentration reported
was 0.058 (J,g/L. The maximum concentration reported was 33.5 p,g/L at a location associated
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with agricultural land (mean in agricultural areas: 0.094 (J,g/L). The detection frequency
associated with agricultural uses was lower (19%) than that associated with urban uses (50%).
The highest concentration reported in urban areas was 16 [j,g/L in Denver, CO (concentration
confirmed by Bret Bruce USGS South Platte). The higher detection frequency in urban streams
(versus agricultural or mixed land uses) is consistent with data summarized in the 2003
assessment. The concentrations detected in urban streams (mostly low concentrations, a few
detections in the multiple ppb range), is also consistent with earlier data. The relatively high
concentration reported associated with agricultural uses (33.5 (J,g/L), is unusual but not outside of
the range predicted by modeling.
3.1.1.2. NAWQA Data (1999-2005) for California
NAWQA monitoring data are available for carbaryl from California surface waters (USGS 2007)
(Table 1, Figure 15). Samples were analyzed for carbaryl using gas chromatography coupled
with mass spectroscopy (GCMS) and high pressure liquid chromatography (HPLC) techniques.
Although this monitoring does not target specific chemicals, carbaryl was detected in 41.6% of
all samples analyzed by GCMS and 28.3% of all samples analyzed by HPLC, with a maximum
concentration of 1.06 |ig/L. NAQWA data are defined by the landcover composition of the
watershed of the surface waters from which samples were taken. Available NAWQA data from
surface waters with watershed landcovers defined as agricultural, mixed, other and urban are
defined separately in Table 11.
Of the NAWQA monitoring data from California surface waters (including detected
concentrations, non-detections and estimated concentrations), none of the 1492 analyzed samples
contained levels of carbaryl sufficient to exceed the LOC for acute exposures to the CRLF (i.e.
12.5 |ig/L). Of the 1393 total samples analyzed by GCMS, 1.1 percent (15 samples) contained
levels of carbaryl sufficient to exceed the LOC for acute exposures to aquatic invertebrates (i.e.
0.255 |ig/L); while none of the 99 total samples analyzed by HPLC contained levels sufficient to
exceed the LOC for aquatic invertebrates.
Detections of carbaryl in water bodies with urban landcovers were 54.1-76.7%) of analyzed
samples. These detection rates were greater when compared to all other types of watershed
landcovers. Concentrations of carbaryl in waters with urban watersheds were sufficient to
exceed the LOC for acute exposures to aquatic invertebrates in 4.5% of samples analyzed by
GCMS (Table 11)
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Table 11. NAWQA 1999 - 2005 data for carbaryl detections in CA surface waters with watersheds with
different landcover compositions. Data are distinguished by method of analysis.
Statistics
Agricultural
Mixed
Other
Urban
Total
GCMS
Number of Samples
322
805
109
157
1393
% Detects1
47.2
39.0
25.7
54.1
41.6
Number of sites
14
20
15
13
62
Maximum Concentration (ju.g/L)
0.657
0.750
0.041
1.060
1.060
% Samples with concentrations sufficient to
0
0
0
0
0
exceed LOC for acute exposures to CRLF2
% Samples with concentrations sufficient to
exceed LOC for acute exposures to aquatic
invertebrates3
1.2
0.5
0
4.5
1.1
HPLC
Number of Samples
20
47
2
30
99
% Detects1
25.0
0
0
76.7
28.3
Number of sites
1
3
1
2
7
Maximum Concentration (ju.g/L)
0.222
<0.0628
<0.0284
0.1922
0.1922
% Samples with concentrations sufficient to
0
0
0
0
0
exceed LOC for acute exposures to CRLF2
% Samples with concentrations sufficient to
exceed LOC for acute exposures to aquatic
invertebrates3
0
0
0
0
0
'Method detection limit = 0.003 |xg/L
2Based on an LC50 of 220 ug I. for Atlantic salmon, the concentration required to exceed the acute exposure LOC of 0.05 is 11 ug I
3Based on an EC50 of 5.1 ug I. for stonefly, the concentration required to exceed the acute exposure LOC of 0.05 is 0.255 ug I
1.2
¦s 0.6
O 0.4
5/15/2000
9/27/2001 2/9/2003
Date
6/23/2004
X GCMS
¦ HPLC
Invert. LOC
11/5/2005
Figure 15. Concentrations of carbaryl reported by NAWQA in CA surface waters from 1999-2005.
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3.1.1.3. California Department of Pesticide Regulation Surface Water
Database
CDPR maintains a database of monitoring data of pesticides in CA surface waters. The sampled
water bodies include rivers, creeks, urban streams, agricultural drains, the San Francisco Bay
delta region and storm water runoff from urban areas. The database contains data from 51
different studies by federal (including the USGS NAWQA program), state and local agencies as
well as groups from private industry and environmental interests. Data are available from 1990-
2005 for 27 counties for several pesticides and their degradates. Data for carbaryl are included in
this database (CDPR 2007). Data included in this database are not necessarily related to targeted
monitoring efforts. For the purpose of this assessment, carbaryl monitoring data from 1999-2005
were accessed from the CDPR database and are discussed below.
From 1999-2005, 1641 samples from CA surface waters were analyzed for carbaryl. Of these,
carbaryl was detected in 0.6% (10 samples), with a maximum concentration of 0.31 |ig/L. These
samples included 83 different sites from 15 counties; including counties where CRLF core areas
and critical habitat are located. When considering all samples analyzed during this time period
(including non-detections), carbaryl was detected at concentrations sufficient to exceed the
invertebrate LOC {i.e., >0.255 |ig/L) in 1 sample, which represents 0.06% of samples.
Some data reported in this database are also reported by USGS in NAWQA; therefore, there is
some overlap between these two data sets. Unlike NAWQA data, the land use {e.g. agriculture,
urban) associated with the watershed of the sampled surface waters is not defined in the CDPR
database; therefore, the available data do not allow for a link of the general use pattern and the
individual data.
3.1.1.4. Environmental Monitoring of Carbaryl Applied in Urban Areas to
control the Glassy-Winged Sharpshooter in California (Walters et al., 2003)
The Environmental Monitoring Branch of CDPR conducted monitoring of carbaryl and other
selected insecticides to provide information on concentrations in various environmental media,
including surface water, resulting from ground applications to control glassy-winged
sharpshooter (Homalodisca coagulata) infestations in California. Carbaryl insecticide was
applied to plants in urban areas to control a serious insect pest, the glassy-winged sharpshooter,
newly introduced in California. To assure there were no impacts to human health and the
environment from the carbaryl applications, carbaryl was monitored in tank mixtures, air, surface
water, foliage and backyard fruits and vegetables. CDPR reported:
"There were three detections of carbaryl in surface water near application sites: 0.125 ppb (parts
per billion) from a water treatment basin; 6.94 ppb from a gold fish pond; and 1737 ppb in a rain
runoff sample collected from a drain adjacent to a sprayed site."
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DPR concluded that results from the five urban areas showed there were no significant human
exposures or impacts on the environment.
3.1.1.5. National trends in carbaryl concentrations in urban areas
This section discusses trends that have been observed in carbaryl concentrations in urban areas
since the announcement of the phase out of two other insecticides widely used in urban areas—
diazinon and chlorpyrifos. There was speculation that with diazinon and chlorpyrifos no longer
available, homeowners would use more carbaryl, and that carbaryl concentrations in streams in
urban areas would increase. The residential use of liquid broadcast formulations of carbaryl on
turf was restricted in 2005 to areas less of than 1000 ft2. Risk managers concluded that this
restriction may help reduce potential runoff of carbaryl in urban environments; however the
labels for granular formulations were not modified. How the carbaryl label changes impact the
extent of the area treated and how that would affect carbaryl concentrations in urban streams is
unclear at this time.
The timing of the phase-out decisions is important in understanding trends in pesticide
concentrations in the environment. On one hand, the date of the announcement of a phase out
initiates a multi-year process stipulating a "stop sale" date and some additional time for pesticide
applicators to use products they have purchased. On the other hand, the market and pesticide
applicators may react quickly to such an announcement. EPA announced the agreement to phase
out and eliminate all residential uses of the insecticide diazinon on December 5, 2000. The terms
of the four-year phase-out stipulated that technical registrants reduce the amount of diazinon
produced by 50% or more by 2003. As of December 31, 2004, it was unlawful to sell diazinon
outdoor, non-agricultural products in the United States (the "stop sale" date for all outdoor
diazinon home, lawn, and garden products). According to existing stocks provisions, it remained
legal for consumers to use products bearing labeling that allowed these uses after that date. On
June 8, 2000, EPA announced an agreement with pesticide registrants to phase out and cancel
nearly all indoor and outdoor residential uses of chlorpyrifos within 18 months, effectively
eliminating use by homeowners. Those uses that posed the most immediate potential risks to
children (home lawn, indoor crack and crevice treatments, uses in schools, parks) were canceled
first, ending as of December 12, 2001. The last remaining residential use, products used for pre-
construction termite control, was cancelled as of December 31, 2005.
Based on the studies described below, the longer term impact of the phase-out on carbaryl
concentrations in urban areas is not clear and may vary by region due to differences in pest
pressure and perhaps marketing of different products. Unlike the clear downward trend in
concentrations observed within a few years for the phased-out compounds (diazinon and
chlorpyrifos), the environmental outcome of this registration decision may take longer to discern.
However, based on the available data, there does not appear to be a steady upward trend to
carbaryl concentrations in urban areas following the phase-out of diazinon and chlorpyrifos.
In a poster, Embrey and Moran (2004), summarized data collected by the NAWQA program
over a decade in the Puget Sound Basin and included data on diazinon and carbaryl collected in
Thornton Creek. During the first cycle, the insecticide diazinon was often detected in samples
from Thornton Creek; some samples were at concentrations greater than 0.1 jag /L. Figure 16,
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which was taken from the poster, shows a decrease in diazinon detections and concentrations
following the announcement of the phase out in 2000. There is also an increase in carbaryl
detection frequency and concentrations in the years following the announcement of the phase out
of diazinon. The data also appear to show that carbaryl concentrations began to decline toward
the end of the study period in 2005, rarely exceeding 0.1 jag /L.
Figure 16. Temporal Changes in Surface-water Insecticide Concentrations after the phase-out of diazinon
and chlorpyrifos (Phillips et al., 2007).
A recently published paper by USGS scientists evaluated trends in concentrations of carbaryl in
the Northeast and Mid-West after the phase-out of diazinon and chlorpyrifos insecticides in
urban environments. They compared concentrations of these pesticides in samples collected
from 20 streams by the USGS between 1992 and 2004 and determined that 16 of these streams
met criteria established for assessing trends of carbaryl in urban streams. Sample collection and
analysis followed standard NAWQA procedures for collection and analysis. Using seasonal step
trend analysis they evaluated the data to identify trends in summer, fall/winter, and winter/spring.
Results showed a decrease in diazinon and chlorpyrifos concentrations following the
announcement of the phase out in 2000. In contrast, trends were not observed in carbaryl
concentrations in these regions during the same time period.
3.1.2. Modeling Approach
For this assessment, estimates of carbaryl concentrations in surface water were calculated using
PRZM version 3.12 dated May 24, 2001 and EXAMS version 2.98.04 dated July 18, 2002.
These models were run in the EFED PRZM EXAMS shell, PE4 version 1.2, dated October 15,
2002. The shell also processed the output from EXAMS to estimate the 1 in 10 year return
values reported here. For this modeling effort, PRZM scenarios designed to represent different
crops and geographic areas of California are used in conjunction with the standard pond
environment in EXAMS. Use-specific and chemical-specific parameters for the PE4 shell as well
as PRZM scenarios are described below. Two use patterns, peaches and asparagus had PRZM
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and EXAMS run outside the PE4 shell so that applications patterns could be split into different
times of the year. The Table20 processor, dated March 2, 1998 was used to analyze the output
from these two simulations. The rice use was modeled with the rice model rather than PE4. For
this model, the input parameters include a organic carbon content of 0.01 to translate Koc (Table
13) to Kd and application rate (Table 14). At table listing of the input files used for this
assessment is in Appendix D.
3.1.2.1. PRZM scenarios
Scenarios used for each use pattern as well as the date for the first application each year are in
Table 12. In general, a first application date of March 15 was used since it corresponds to the
beginning of spring growing season in central California. In cases where specific information for
a crop was available, a more appropriate date was selected. A justification for the scenario
selection and any use specific rationales for application date selections are provided below.
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Table 12. PRZM scenario assignments and first application dates for the uses of carbaryl simulated for the
aquatic exposure assessment for the California CRLF Ecological Risk Assessment.
Crop group'
Scenario
First Application Date
A: Home lawn
CAresidential no_irrig
CAImpervious
March 15
B: Flower beds around buildings
CAresidential no_irrig
March 15
C: Lawns
CaTurf no_irrig
March 15
D: Ornamentals
CANursery no_irrig
March 15
E: Parks
CaTurf no_irrig
March 15
F: Citrus
CAcitrus_NirrigC
April 1
G: Olives
CaTurf no_irrig
March 15
H: Almonds
CAalmond_NirrigC
March 15
I: Flowers
CANursery no_irrig
March 15
J: Peaches
CAfruit_NirrigC
March 15, December 15
K: Asparagus
CARowCrop no_irrig
January 1, June 15
L: Apple
CAfruit_NirrigC
March 15
M: Loquat
CAcitrus_NirrigC
March 15
N: Sweet corn
CAcornOP
June 15
O: Grapes
CAwinegrapes no_irrig
March 15
P: Strawberries
CAStrawberry_noplastic
no irrig
January 15
Q: Tomatoes
CAtomato_NirrigC
March 15
R: Peanuts
CARowCrop no_irrig
May 1
S: Broccoli
CAColeCrop no_irrig
January 15
T: Brussels sprouts
CAlettuceC
January 15
U: Sweet potato
CAPotato no_irrig
May 1
V: Field corn
CAcornOP
June 15
W: Lettuce, head
CAlettuceC
January 15
X: Sorghum
CAcornOP
June 15
Y: Celery
CARowCrop no_irrig
January 15
Z: Horseradish
CAColeCrop no_irrig
January 15
AA: Potato
CAPotato no_irrig
March 15
AB: Radish
CAonion_NirrigC
March 21
AC: Rice
NA (Rice model used)
NA
AD: Beans
CARowCrop no_irrig
May 1
AE: Okra
CAtomato_NirrigC
March 15
AF: Sugar beet
Casugarbeet_NirrigOP
January 1
AG: Alfalfa
Caalfalfa_NirrigOP
April 15
AH: Pasture
CARangelandHay
March 15
AI: Grass for seed
CaTurf no_irrig
February 15
AJ: Rangeland
CARangelandHay
February 15
AK: Melon
CAMelons No_irrig
March 15
AL: Roses
CANursery no_irrig
March 15
AM: Rights-of-way
Carightofway
October 1
AN: Wasteland
CAImpervious
January 15
AO: Non-urban forests
CAForestry
January 15
AP: Rural shelter belts
Carightofway
January 15
AQ: Ticks
CaTurf no_irrig
January 15
NA = not applicable
*For specific uses associated with each crop grouping, see Table 5.
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Home lawns (Group A): Estimating the aquatic exposure from the use of carbaryl on home lawns
involves the use of two scenarios, one for California residential turf and one for California
impervious surfaces. EECs are derived for both scenarios, and then combined by assuming that
50% of the watershed is treated lawn and the remainder is impervious surface. It is also assumed
that 1.68% of the impervious surface gets over-sprayed during treatment of the lawns. A detailed
description of the rationale for these values is provided in Appendix E.
Flower beds around buildings (Group B): The California Residential scenario was used with this
use pattern as it was thought that this scenario is most representative of flower beds around
buildings. The label indicates that a drop or broadcast spreader should be used for this use. It
was assumed that the dust from a dry application was approximately the same size distribution as
the droplets from a ground application, so applications were modeled as ground methods.
Because the use pattern is only for a six foot wide swath around buildings, it was assumed that
only 4.4% of the watershed was treated. A detailed description of the rationale for this value is
provided in Appendix F.
Lawns (Group C): This scenario is distinct from the home lawn scenario in that in could include
lawns other than residential lawns, so the more generic California turf scenario was used for this
simulation.
Ornamentals (Group D): The California Nursery scenario was specifically designed for
commercially grown outdoor ornamentals which would be included in this very general use
pattern. The use group also includes residential, public, and commercial gardens.
Parks (Group E): This group includes recreation areas, golf courses, sod farms, and commercial
lawns. The California turf scenario, which was specifically designed for sod farms, is most
representative of this group of uses and was specifically designed for sod farms in particular. The
use pattern that would produce the greatest EECs for parks could not be determined from labels.
Therefore, applications to parks were modeled using two approaches: with one application of 8
lb acre"1 and with two applications of 4 lb acre"1 applied 7 days apart. The second use pattern
gave the highest EEC's and is the one reported in Table 14.
Citrus (Group F): The California citrus scenario is a standard scenario that was specifically
designed to represent citrus in that state. The use pattern that would produce the greatest EECs
for citrus could not be determined from the label and was modeled to ways: with one application
of 16 lb acre"1 and with three applications of 7 lb acre"1 applied 14 days apart. The first use
pattern gave the highest EECs and is the one reported in Table 14. April 1 represents an early
season application of carbaryl to citrus crops and was the value used in the previous aquatic
exposure assessment (Jones 2003).
Olives (Group G): The California olive scenario was specifically designed for simulating that
crop in California.
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Almonds (Group H): The California almond scenario is a standard scenario that was specifically
designed to represent almonds in that state and on a national basis. Almonds serve as surrogate
for the other nut crops: almonds, chestnuts, pecans, filberts, walnuts, and pistachios.
Flowers (Group I): California Nursery scenario was specifically designed to represent
commercially grown, outdoor ornamentals, including flowers. Flowers serve as a surrogate for
the use of carbaryl on shrubs.
Peaches (Group J): The California fruit scenario is a standard scenario that was specifically
designed to represent deciduous fruit trees in that state, including the stone fruits. Peaches serve
as a surrogate crop for the other stone fruits in this assessment, including: apricots, cherries,
nectarines, plums, and prunes. There are two application seasons two peaches, during the
growing season and during the dormant season. Two applications of four lb acre"1 were made 15
days apart starting on March 15 with a dormant application of 5 lb acre"1 made on December 15.
Asparagus (Group K): The California row crop scenario is a generic scenario for vegetables that
are grown in the Coastal Valley other than leafy vegetables (lettuce scenario), and the cole crops
(cole crop scenario). Since asparagus is neither a leafy vegetable nor a cole crop, and is grown in
the Coastal Valley, the row crop scenario is appropriate for simulation of asparagus culture.
Asparagus is a perennial crop for which the stem is harvested. Multiple harvests, typically three,
will be made from the same field each year in the spring followed by period where the plant is
allowed to mature so that rhizomes can be filled to allow growth the following year. Spears are
allowed to grow about week after emergence before harvest. Fields can produce for years if they
are well maintained. Carbaryl has different application patterns during the harvest period and
after harvest during which vegetative growth is allowed. Three applications of 2 lb were made at
3-d intervals during harvest starting January 1, while a single application of 4 lb/acre was made
post-harvest on June 15.
Apple (Group L): The California fruit scenario is a standard scenario that was specifically
designed to represent deciduous fruit trees in that state, including the pome fruits. Apples serves
as a surrogate for the pome fruits other than loquat, including pears, oriental pears, and
crabapples.
Loquat (Group M): Loquats are an evergreen pome fruit and were thus simulated using the
California citrus scenario rather the California fruit scenario which is used for other pome fruits.
Sweet corn (Group N): Sweet corn was simulated using the California corn scenario designed for
the organophosphate cumulative assessment (USEPA 2006) as it was designed specifically for
corn in California. The first application date to sweet corn was June 15 after the start of ear
development.
Grapes (Group O): There are two grape scenarios for California, one scenario represents wine
grapes in Sonoma County and the other scenario represents California grapes in the Central
Valley for table and raisin grapes. Since the carbaryl labels do not specify grape type, the wine
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grape scenario was used as it produces higher EECs. Grapes serve as a surrogate for two other
berry crops: blueberries and caneberries.
Strawberries (Group P): The California no-plastic strawberry scenario was used for this
assessment. Strawberries can be a winter crop in coastal California, so a January 15 first
application date was used for these simulations, as this is also the rainy season in California.
Tomatoes (Group Q): The California tomato scenario was used for this assessment and was
designed for assessing tomatoes in California. Tomatoes serve as a surrogate for peppers.
Peanuts (Group R): The California row crop scenario was used for peanuts because it is a
legume similar to dry beans which is one of the crops the row crop scenario was designed to
represent. Peanuts are grown in sandier soils than that in the row crop scenario so these estimates
may be somewhat conservative. A first application date of May 1 is used as peanuts are a spring
crop and would be expected to have emerged by this date.
Broccoli (Group S): The California cole crop scenario was used for this assessment since
broccoli is a type of cole crop. Broccoli serves as surrogate for most of the cole crops and some
related vegetables, including: cauliflower, cabbage, kohlrabi, Chinese cabbage, collards, and
mustard greens. Broccoli and the other cole crops can be a winter crop in coastal California,
which is also the rainy season in California. Selection of an application date during the rainy
season is likely to result in more pesticide runoff and higher EECs. A January 15 first application
date was used for these simulations.
Brussels sprouts (Group T): The California lettuce scenario was used for simulating Brussels
sprouts since Brussel sprouts are a leafy vegetable crop with similar cultural practices as lettuce.
Brussels sprouts serve as surrogate for Hanover salad, which is also leafy vegetable crop.
Brussels sprouts can be a winter crop in coastal California, so a January 15 application date was
used for these simulations.
Sweet potato (Group V): The California potato scenario was used for simulating sweet potatoes
as they are both tuber crops with somewhat similar production practices. The first application
date was set to two weeks after the expected crop emergence on May 1.
Field corn (Group U): Sweet corn was simulated using the California corn scenario designed for
the organophosphate cumulative assessment (USPEA 2006) as it was designed specifically for
corn in California. Field corn also serves as a surrogate for popcorn. The first application date to
sweet corn was June 15, after the start of ear development.
Lettuce, head (Group W): The California lettuce scenario is a standard scenario that was
specifically designed to represent head lettuce in California and on a national basis. Head lettuce
serves as a surrogate for several leafy vegetables: leaf lettuce, dandelion, endive, parsley,
spinach, and Swiss chard. Lettuce is usually a winter crop in coastal California, so a January 15
first application date was used for these simulations.
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Sorghum (Group X): The California corn scenario was used for sorghum as it closely resembles
corn in agricultural management practices. Like corn, sorghum is a non-tillering grain that is
planted in and grown in rows. Grains grown in rows tend to a have higher (much higher)
tendency to generate eroded sediment, than the small grains, like wheat, that tiller extensively
and tend to cover the soil surface much more completely at maturity. Sorghum is grown in the
place of corn, in places where there is too little moisture, or it is not reliable enough, to grow
corn. The first application date to sweet corn was June 15 after the start of grain development.
Celery (Group Y): The California row crop scenario is a generic scenario for vegetables that are
grown in the Coastal Valley other than leafy vegetables (lettuce scenario), and the cole crops
(cole crop scenario). This scenario is specifically designed for celery. This group includes
several vegetable crops grown in the Coastal Valley of California: celery, prickly pear, garden
beets, and carrots. Celery is usually a winter crop in coastal California, so a January 15 first
application date was used for these simulations.
Horseradish (Group Z): The California cole crop scenario was used for horseradish because it is
in the same botanical family as the cole crops (Brassicaceae). It is expected that horseradish has
similar cultivation practices and environmental requirements as other members of the cole crop
group. January 15 was selected for an application date to derive conservative EECs.
Potato (Group AA): The California potato scenario was used for this assessment. This group
includes several other root and tuber vegetables: parsnip, rutabaga, salsify, and turnip (root).
Radish (Group AB): The California onion scenario, which is a standard scenario used for onions
in California serves a suitable scenario for radish as they are both bulb crops grown in the
Central Valley. The first application date was set to 15 days after emergence in the scenario on
March 21.
Rice (Group AC): As discussed above, rice was not modeled with PRZM and EXAMS but
rather, using the Tier I rice model. Therefore, no PRZM scenario was used.
Beans (Group AD): Beans, including fresh beans are one of the crops for which the California
row crop scenario was designed and has been used for that purpose in this assessment. This
group includes a variety of leguminous crops: dry beans, fresh peas, dry peas, cowpeas, and fresh
southern peas. A first application date of May 1 as beans is a spring crop and would be expected
to have emerged by this date.
Okra (Group AE): Okra is a bushy annual crop somewhat similar to tomatoes. The California
tomato scenario was used to simulate okra for this assessment.
Sugar beet (Group AF): The California sugar beet scenario was designed for assessing aquatic
exposure from sugar beet culture in California and has been used for that crop for these
simulations.
Alfalfa (Group AG): The California alfalfa scenario was designed for the organophosphate
cumulative assessment (USEPA 2006) and has been used to simulate alfalfa culture for these
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assessments. This group includes other surrogate forage crops, including: birdsfoot trefoil and
clover. Stands of alfalfa are maintained for as long as five years before replanting. Several
cuttings per year are taken from each alfalfa field and carbaryl can be applied once per cutting.
For this assessment, it was assumed there were 7 applications at 30 day intervals starting in April
15 which appears to be typical number of cuttings for California.
Pasture (Group AH): The California rangeland and hay scenario was used for this assessment
and was specifically designed for assessing rangeland, hay and pasture crops for CRLF
assessments.
Grass for seed (Group AI): The California turf scenario was thought to best represent this use
and was specifically designed for sod farms which grass grown for seed somewhat resembles.
The first application date was set to February 15 to reflect that grass will be dormant during the
winter months.
Rangeland (Group AJ): The California rangeland and hay scenario was used for this assessment
and was specifically designed for assessing rangeland, hay and pasture crops. The first
application date was set to February 15 to reflect that grass will be dormant during the winter
months.
Melon (Group AK): The California melon scenario was used for this assessment and was
specifically designed for assessing melons for CRLF assessments. This group represents other
cucurbits: cucumber, pumpkin, and squash.
Roses (Group AL): The California Nursery scenario was specifically designed the CRLF
assessment to represent commercially grown outdoor ornamentals including roses and other
flowers.
Rights-of-way (Group AM): The California rights-of-way scenario was specifically designed for
this use pattern for the CRLF. Rights-of-way serve as a surrogate for several other use patterns of
perennial vegetation that are along borders or paths: hedgerow, ditch banks, roadsides, CRP
acreage, and set-aside acreage. The application date was set for two weeks after the emergence
date in the scenario on October 1. A more detailed discussion of how the EECs were estimated
for the rights-of-way scenario is in Appendix G.
Wasteland (Group AN): Wasteland is a vague, poorly-defined use pattern which could be any
poorly maintained area which had some prior, now-abandoned usage. Since this use could
conceivably include abandoned parking lots, the California Impervious scenario was used to
represent wasteland for this assessment. The first application date of January 15 reflects the fact
that applications can be made at any time, including the rainy season, which occurs in January.
Applications made during the rainy season result in more runoff and thus, more conservative
EECs.
Non-urban forests (Group AO): Non-urban forests serves as surrogate for other maintained and
unmaintained groups of trees not used for fruit production. This group includes tree plantations,
Christmas trees, parks, and rangeland trees. Since urban forests are considered to be parks, this
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use pattern, along with its surrogates, covers any group of trees other than fruit trees. It does not
include those planted along the edge of fields (see rural shelter belt use pattern). The first
application date of January 15 was selected as a conservative application data because evergreen
forests may have pest pressure year round.
Rural shelter belts (Group AP): The California rights-of-way scenario was used to simulate rural
shelterbelts as this rural shelter belts are long and narrow with perennial vegetation similar to
rights-of-way. The first application date of January 15 was selected as a conservative application
data because evergreen forests may have pest pressure year round.
Ticks (Group AQ): The turf scenario was used to simulate carbaryl applications to treat ticks. It
is expected that turf and turf-like scenarios would serve as the most common type of land cover
to which this application would be made.
3.1.2.2. Input Parameters
Chemical-specific parameters
The input parameters used to describe the chemical properties of carbaryl are in Table 13. In
most cases these parameters were selected in accordance with guidance (Environmental Fate and
Effects Division, 2002). In some cases though, no guidance exists, e.g., selection of wash-off
ratios; in these cases, the method used to select the input parameter is described more thoroughly
below. Data quality descriptions for each parameter were derived as follows. The descriptor
"Excellent" is used to describe parameters which are very well know and had little or no error
associated with them (e.g. molecular weight) or when there is an abundance of high quality data
available. The descriptor "Very good" is used to describe parameters from high quality studies
and the study is generally reproducible (e.g. hydrolysis), or when there is substantial background
variability (e.g. aerobic soil metabolism) there are multiple high quality studies used to develop
the input parameter. The descriptor "Good" is used where the data is expected to be
reproducible, but is more uncertain than normal, or if metabolism parameters are based on two
high quality studies, or where there are multiple studies which are usable but not high quality.
The descriptor "Fair" is used to describe metabolism parameters based on a single study, or
where the data set is significantly flawed but still provide some usable information. The
descriptor "Poor" is used describe input parameters based on surrogate data.
In the previous modeling for aquatic exposure, soil-water partitioning used Kd values which were
keyed to soil texture. Since texture is usually only a factor of secondary importance, this method
of parameter selection would not be expected to result in great accuracy. In this assessment, an
organic carbon partition coefficient (Koc) was estimated by regressing the adsorption Kf values
against the organic carbon content. The Kf values were assumed to be linear, i.e., equal to Kd.
This will result in some underestimation of the binding (and overestimation of carbaryl mobility)
at low soil organic carbon contents, but greater accuracy over all scenarios. This is described in
more detail in the revised environmental fate and ecological risk assessment which was
published in support of the interim reregi strati on eligibility decision on carbaryl (USEPA 2004).
Page 75 of 160
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Metabolism was estimated from three single studies for aerobic soil, and anaerobic aquatic
metabolism. The aerobic soil and anaerobic aquatic metabolism half-lives were consequently
multiplied by three in keeping with current policy to account for the uncertainty caused by the
high background variability in these parameters. The aerobic aquatic metabolism value was set to
the upper confidence bound on the mean of three values.
In the original science chapter in support of the reregi strati on eligibility decision for carbaryl
(USEPA 2003), the foliar degradation half-life was set to 35 days based OPP policy for terrestrial
exposure assessments in the absence of measured foliar degradation rates. Current guidance is to
use a rate constant of zero for aquatic assessments in the absence of data. Bayer CropScience,
provided data (MRID 45860501) indicating that carbaryl degrades on foliage at substantially
faster rate than 35 d. The data discussed in the submission provided by the registrant was
reviewed and analyzed (Jones 2003b). Based on that analysis, a value of 3.71 days was used for
the foliar degradation half-life. This represents an upper 90% confidence bound on the mean from
30 foliar dissipation studies.
Table 13. Carbaryl chemical input parameters for PE4 for carbaryl for the CRLF assessment.
Parameter
Value
Quality
Molecular weight
201.22 gmol4
excellent
Solubility
32 mg L"1
good
Henry's Law Constant
1.28 x 10 "8 atm-m"3 mol"1
fair
Koc
196L kg4
good
Vapor Pressure
1.36 x 10"7 torr
good
Aerobic soil metabolism half-life
12 d
fair
Aerobic aquatic metabolism half-life
124.2 d
fair
Anaerobic aquatic metabolism half-life
216.6 d
fair
Hydrolysis half-life
pH 5 - assumed stable
pH 7 - 12 d
pH 9-0.133 d
good
Aqueous photolysis
21 d
good
Foliar Degradation Rate
0.187 d"1
excellent
Foliar Washoff Coefficient
3.70 cm"1
fair
As part of the data submitted for consideration in estimating the foliar degradation rate, the
registrant also submitted data which supported a revised estimate of the foliar washoff
coefficient. In the absence of data, current EFED policy recommends a washoff coefficient of
0.5, which represents the fraction of chemical that washes off with each 1 cm of rainfall. An
analysis of two relevant studies indicates that a wash-off coefficient of 0.91 is more appropriate.
However, the estimates for both studies were based on two point estimates, so no error term or
determination of variability in the data could be made. A more complete description of how the
Page 76 of 160
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studies were assessed is in the report titled Review and Estimation of Foliar Dissipation Half-life
of Carbaryl (DP Barcode D288376).
Use-specific parameters
Use-specific parameters include application methods and rates (Table 5). Application methods,
maximum rates per application and maximum number of applications per year are based on
current label directions (Table 14). For each simulated crop, the maximum single application
rate was simulated, with the maximum number of applications per year, with the minimum
application interval. In several cases, both a maximum number of applications and a maximum
seasonal rate were specified. In some of these cases, the maximum application rate multiplied by
the maximum number of applications was greater than the maximum seasonal application rate. In
these cases, the maximum seasonal rate was used to limit the number of applications. In general,
this approach produces the greatest aquatic exposure estimates for each crop. In cases, where it
was not clear that this would be the case, more than use scenario was modeled. These cases are
discussed in the crop-specific use pattern descriptions below.
Page 77 of 160
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Tabic 14. Ise pallerns for Hie assessment of aquatic exposure from carbanl lo Hie CRI.F.
( nip (. r<>111>
1 I'M M)1
M:i\. V|ip. Kiilc
ilhii.i. ;iuvi
Miix.
V |>|>lit:il ion
hilt'i'\iiK i«I;i\*i
A|i|ili>iiliMii McIIimiI
A: Home lawn
3
9.1
2
7
ground
B: Flower beds around buildings2
1
8
25
3
Drop/broadcast spreader
C: Lawns3
3
7.8
4
7
ground
D: Ornamentals4
1
7.8
4
7
ground
E: Parks
3
4
2
7
ground
F: Citrus
3
16
1
NA
aerial
G: Olives
3
7.5
2
14
aerial
H: Almonds
1
5
3
7
aerial
I: Flowers
1
4.3
3
7
ground
J: Peaches
1
4 (dormant=5)
2 + 1 dormant
15
aerial
K: Asparagus
1
Pre: 2; Post: 4
Pre:3; Post: 1
Pre:3; Post: NA
aerial
L: Apple
1
3
5
14
aerial
M: Loquat
3
5
14
aerial
N: Sweet corn
1
2
8
3
aerial
O: Grapes
1
2
5
7
aerial
P: Strawberries
1
2
5
7
aerial
Q: Tomatoes
1
2
4
7
aerial
R: Peanuts
1
2
4
7
aerial
S: Broccoli
1
2
4
6
aerial
T: Brussels sprouts
1
2
4
6
aerial
U: Sweet potato
1
2
4
7
aerial
V: Field corn
1
2
4
14
aerial
W: Lettuce, head
1
2
3
7
aerial
X: Sorghum
1
2
3
7
aerial
Y: Celery
1
2
3
7
aerial
Z: Horseradish
1
2
3
7
aerial
AA: Potato
1
2
3
7
aerial
AB: Radish
1
2
3
7
aerial
AC: Rice
1
1.5
2
7
aerial
AD: Beans
1
1.5
4
7
aerial
AE: Okra
1
1.5
4
6
ground
AF: Sugar beet
1
1.5
2
14
aerial
AG: Alfalfa
2
1.5
7
30
aerial
AH: Pasture
3
1.5
2
14
aerial
AI: Grass for seed
2
1.5
2
14
aerial
AJ: Rangeland
3
1
1
NS
aerial
AK: Melon
1
1
6
7
aerial
AL: Roses3
1
1
6
7
aerial
AM: Rights-of-way
1
1
2
14
aerial
AN: Wasteland
3
1
2
14
aerial
AO: Non-urban forests
3
1
2
7
aerial
AP: Rural shelter belts
3
1
2
7
aerial
AQ: Ticks
3
1
25
3
ground
^PSCND: condition for disposition of foliar pesticide after harvest. 1 = surface applied, 2 = complete removal, 3 = left alone.
2 uniform 6 ft band around building, water in lightly after application; 3does not include pre-plant dip of 1.2 lb/acre for sweet potatoes
4Labels do not provide information for aerial spray applications but do not restrict the products for aerial application. 5For specific uses
associated with each crop group see Table 5.
Page 78 of 160
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Each of the 112 use patterns of carbaryl in California has either been simulated, or has been
assigned a surrogate. Justifications for surrogate selection are provided in Appendix A.
Surrogate crops covered by each modeled scenario are listed in the use specific descriptions
below.
In most cases, at least one carbaryl label allowed aerial application to the crop. In some cases, the
label did not make reference to aerial application, but neither was the practice prohibited and it
was assumed that these products could legally be used as an aerial spray. An exception to this
was for uses in an around residential settings where aerial application was not assumed. For
aerial applications, the application efficiency and spray drift input parameters were set at 0.95
and 0.05, respectively, in accordance with current input parameter guidance (USEPA 2002). For
ground sprays, the application efficiency and spray drift input values were 0.99 and 0.01.
For all use patterns in this assessment except those applied to impervious surfaces, a foliar
application was assumed (This set with the CAM variable in PRZM; CAM =2). For applications
to uses with an impervious surface (home lawns and wasteland) a broadcast application was used
(CAM = 1). For foliar applications, the disposition of foliar pesticide after harvest, the IPSCND
variable, must also be set. The IPSCND variable has three possible values: 1- the pesticide is
surface applied; 2- the pesticide is completely removed; and 3- the pesticide is left alone. In most
agricultural crops, the pesticide is surface applied on the assumption the crop residue other than
the fruit or grain itself is left in the field. For evergreen trees and turf, a value of 3 was used as it
would be assumed the pesticide remains on the vegetation. In a few cases, e.g. sod farms, a value
of 2 was used as it would be expected that the foliar pesticide would be removed as the crop was
removed.
3.1.2.3. Post-Processing approach for rights-of-way and residential scenarios
In a standard PRZM scenario, it is assumed that an entire 10 ha field is composed only of the
identified crop, and that the field has uniform surface properties throughout the field. In a right-
of-way or residential area, this is not a reasonable assumption, since these areas contain both
impervious and pervious surfaces. Since the two surfaces have different properties (especially
different curve numbers influencing the runoff from the surfaces) and different masses of applied
carbaryl, the standard approach for deriving aquatic EECs is revised using the following
approach:
a. Aquatic EECs are derived for the pervious portion of the right-of-way and residential,
using the maximum use rates of carbaryl on the CA right-of-way and CA residential
scenarios, respectively. At this point, it is assumed that 100% of the area is composed of
pervious surface.
b. Aquatic EECs are derived for the impervious portions of the right-of-way and residential
area, using 1% and 5.68%, respectively, of the maximum use rates of carbaryl on the CA
impervious scenario. At this point, it is assumed that 100% of the areas are each
composed of impervious surface.
Page 79 of 160
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c. The daily aquatic EECs (contained in the PRZM/EXAMS output file with the suffix
"TS") are input separately into a Microsoft® Excel worksheet to post process the right-of-
way and residential EECs.
d. Daily aquatic EECs for the impervious surface are multiplied by 50%. Daily aquatic
EECs for the pervious surface are multiplied by 50%. The resulting EECs for impervious
and pervious surfaces are added together to get an adjusted EEC for each day of the 30-
year simulation period (Equation 1).
Equation 1: Revised EEC = (imperviousEEC * 50%)+(perviousEEC * 50%)
e. Rolling averages for the relevant durations of exposure (21-day, and 60-day averages) are
calculated. The l-in-10 year peak, 21-day and 60-day values are used to define the acute
and chronic EECs for the aquatic habitat.
In this approach, it is assumed that a right-of-way and a residential area are composed of equal
parts pervious and impervious surfaces (i.e. in step 4, the EECs of both surfaces are multiplied
by 50%)). For rights-of-way, this is more likely to be representative of a highway or road right-of-
way. It is likely that rights-of-way contain different ratios of the two surfaces. In general,
incorporation of impervious surfaces into the exposure assessment results in increasing runoff
volume in the watershed, which tends to reduce overall pesticide exposure (when assuming 1%
overspray to the impervious surface). For residential areas, the rational for the post-processing
approach is described in Appendix E.
3.1.3. Aquatic Modeling Results
PRZM/EXAMS EECs representing l-in-10 year peak, 21-day, and 60-day concentrations of
carbaryl in the aquatic environment are located in Table 15. The highest EECs are for the rice
use which is a reflection of the lower tier assessment used for that crop. The next highest EECs
are for Brussels sprouts which had a 1-in-ten year peak EEC of 166 |ig/L. In general, crops
grown in coastal scenarios had higher EECs than those in the Central Valley; and those where
application was made in the winter had higher EECs than those in the spring and summer.
Page 80 of 160
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Table 15. One-in-ten-year carbaryl EECs for aquatic environments from the application of carbaryl to uses
in California.
Crop (.roup
Peak
21 l)a\ l l (
(iiii/l.l
Ml l);i\ ll(
(.uti/l.)
V: Home lawn
14.6
8.7
5.25
B: Flowers around buildings
0.47
0.29
0.15
C: Lawns
25.4
19.0
12.4
D: Ornamentals
51.2
29.3
16.0
E: Parks 1
9.3
6.5
3.6
E Parks 2
10.0
6.3
3.7
F: Citrus 1
33.2
22.0
15.4
F: Citrus 2
44.7
25.2
11.8
G Olives
52.6
31.4
18.9
H: almonds
43.3
29.1
17.5
I: flowers
21.4
13.0
6.7
J: peaches
56.8
32.1
17.0
K: asparagus
47.2
26.5
13.4
L: apple
16.3
10.7
9.3
M: loquat
13.0
8.7
7.5
N: sweet corn
24.8
18.7
10.7
0: grapes
22.4
18.2
11.9
P: strawberries
100.2
72.7
39.7
Q: tomatoes
24.5
17.1
11.0
R: peanuts
12.9
9.0
5.6
S: broccoli
73.0
47.5
26.4
T: Brussels sprouts
166.8
108.3
55.8
U: sweet potatoes
49.7
32.0
19.6
V:corn
9.1
6.2
5.0
W: head lettuce
93.5
62.7
34.6
X: sorghum
11.4
7.4
4.1
Y: celery
37.9
22.4
11.6
Z: horse radish
71.8
43.2
22.8
AA: potato
42.0
24.2
12.5
AB: radish
13.3
8.6
4.8
AC: rice
2579
2579
2579
AD: dry beans
9.7
6.8
4.2
AE: okra
5.6
3.1
1.8
AF: sugar beet
13.6
9.6
5.4
AG: alfalfa
9.1
5.0
3.2
AH: pasture
10.9
7.8
4.3
AI: grass for seed
7.1
4.7
3.1
AJ: rangeland
12.8
7.7
2.6
AK: melons
7.2
5.4
4.0
AL: roses
14.9
8.9
4.7
AM: rights of way
19.0
12.2
7.6
AN: wasteland
68.0
40.0
26.1
AO: non-urban forests
11.5
8.2
4.2
AP: rural shelter belts
41.0
28.7
14.9
AQ: Ticks
17.7
15.1
13.2
'For specific uses associated with each crop group see Table 5.
Page 81 of 160
-------
An adjustment factor was applied to the EECs for the "flower beds around buildings" use pattern
to account for the portion of the watershed that is on the perimeter of buildings and could be
treated. This approach is modeled after an approach which has been previously used for
Fipronil® and naphthalene (Corbin, 2007; USEPA 2007). According to the 2000 United States
Census, the average lot size is Vi of an acre or 10,890 square feet and the typical house has a foot
print of 1000 square feet. If the house is square, there would be 31.6 ft on each side. If there is a
garden 3-feet wide all the way around the house, the total length of that garden would be 138.5
feet, and the total area of the garden would be 415 square feet. In the standard 10 ha (107,640 sq.
ft) watershed, there would be 58 houses or a total area of 24,070 sq feet of perimeter garden
which is equivalent 2.24% of the watershed. This Crop Area Factor was applied to the flower
beds around buildings use pattern (Pattern B) to calculate the EECs
3.2. Terrestrial Exposure Assessment
3.2.1. Modeling Approach
T-REX (version 1.3.1) is used to calculate dietary and dose-based EECs of carbaryl for the
terrestrial-phase CRLF and its potential prey (e.g. terrestrial invertebrates, small mammals)
inhabiting terrestrial areas. EECs used to represent exposure to CRLF are also used to represent
exposure values for frogs serving as potential prey of terrestrial-phase CRLF adults. T-REX
simulates a 1-year time period. A foliar dissipation half-life of 3.71 days is used based on data
reported by Jones 2003b. The Mineau scaling factor of 1.55 is used to improve interspecies
extrapolation of dose-based toxicity data for birds (surrogate for the CRLF) exposed to carbaryl
(Mineau et al. 1996). Specific input values, including number of applications, application rate
and application interval used in the analyses are located in Table 16. Use specific input values
are consistent with those used in aquatic exposure modeling (Table 14). An example output from
T-REX v. 1.3.1 is available in Appendix H.
For residential use of carbaryl on flowers around buildings, labels indicate a maximum
application rate equivalent to 8 lb a.i./A. The total number of applications per year is not
specified on the label. Therefore, with the 3-day reapplication interval, the maximum number of
applications possible per year is assumed to be 25.
Page 82 of 160
-------
Table 16. Input parameters for foliar applications used lo dome lerreslri;i1 EECs for earbanl w\ih T-REX,
( l ull (. I'<>111>
M;i\. V|i|i. U;ilr
illiii.i. iit'l't'i
Niimhrr nl'
;i|>|>litiili<>lMill
Vpplit'iilion
1 ini-i~\ nl i <1 ;i\-1
A: Home lawn
9.1
2
7
B: Flower beds around buildings2
8
25
3
C: Lawns3
7.8
4
7
D: Ornamentals4
7.8
4
7
E: Parks
4
2
7
F: Citrus
16
1
NA
G: Olives
7.5
2
14
H: Almonds
5
3
7
I: Flowers
4.3
3
7
J: Peaches
42
3
15
K: Asparagus
23
4
3
L: Apple
3
5
14
M: Loquat
3
5
14
N: Sweet corn
2
8
3
O: Grapes
2
5
7
P: Strawberries
2
5
7
Q: Tomatoes
2
4
7
R: Peanuts
2
4
7
S: Broccoli
2
4
6
T: Brussels sprouts
2
4
6
U: Sweet potato
2
4
7
V: Field corn
2
4
14
W: Lettuce, head
2
3
7
X: Sorghum
2
3
7
Y: Celery
2
3
7
Z: Horseradish
2
3
7
AA: Potato
2
3
7
AB: Radish
2
3
7
AC: Rice
1.5
2
7
AD: Beans
1.5
4
7
AE: Okra
1.5
4
6
AF: Sugar beet
1.5
2
14
AG: Alfalfa
1.5
7
30
AH: Pasture
1.5
2
14
AI: Grass for seed
1.5
2
14
AJ: Rangeland
1
1
NS
AK: Melon
1
6
7
AL: Roses
1
6
7
AM: Rights-of-way
1
2
14
AN: Wasteland
1
2
14
AO: Non-urban forests
1
2
7
AP: Rural shelter belts
1
2
7
AQ: Ticks
1
25
3
*For specific uses associated with each crop group see Table 5.
2The maximum application scenario for peaches is 2 seasonal applications of 4 lbs a.i./A with one dormant season application
of 5 lbs a.i./A. For modeling purposes, EECs were derived assuming 3 annual applications of 4 lbs a.i./A each.
3The maximum application scenario for asparagus is 3 preseason applications of 2 lbs a.i./A with one post season application of
4 lbs a.i./A. For modeling purposes, EECs were derived assuming 5 annual applications of 2 lbs a.i./A each.
Page 83 of 160
-------
3.2.2. Terrestrial Animal Exposure Modeling Results
For modeling purposes, exposures of the CRLF to carbaryl through contaminated food are
estimated using the EECs for the small bird (20 g) which consumes small insects. Dietary-based
and dose-based exposures of potential prey are assessed using the small mammal (15 g) which
consumes short grass. Upper-bound Kenaga 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 17).
T-REX reported, dietary-based EECs used for small and large insects are available in Table 17.
An example output from T-REX v. 1.3.1 is available in Appendix H.
Page 84 of 160
-------
Table 17. Upper-bound Kenaga nomogram EECs for dietary- and dose-based exposures of the CRLF and its
prey to carbaryl.
I.I.( x |.M ( l\l 1 1
¦ ml Irnv-lihil pliiiM'
l'.l'.( - I'nr l.ii ^i
l'.l'.( - Ilil -IILill lllilllllllills ||I|V\ 1
( r<>|> (.roup
jllipllihhill- m'I'\ ill!! ;i» |>l r\ i
IUTt">lri:il
I)m«I' ll.lM'll ll(
l)irl;ir\ IiiitiI ll(
ill\('llcl>r;ili'-
Dot ll.lM'll ll(
Diclurx Iiiim'iI
(III!! It!! Im l
i|>|iinr
i|||iiiii
(III!! Im I
l l ( (|>|>in i
A: Home lawn
1777
1560
173
2645
2774
B: Flower beds around buildings
2866
2516
280
4265
4473
C: Lawns
1635
1435
159
2432
2551
D: Ornamentals
1635
1435
159
2432
2551
E: Parks
781
686
76
1162
1219
F: Citrus
2460
2160
240
3661
3840
G: Olives
1237
1086
121
1841
1931
H: Almonds
1033
907
101
1537
1612
I: Flowers
888
780
87
1579
1386
J: Peaches
1160
575
64
971
1018
K: Asparagus
640
562
62
953
1000
L: Apple
498
437
49
741
777
M: Loquat
498
437
49
741
777
N: Sweet corn
708
622
69
1054
1106
O: Grapes
421
369
41
626
657
P: Strawberries
421
369
41
626
657
Q: Tomatoes
419
368
41
624
654
R: Peanuts
419
368
41
624
654
S: Broccoli
451
396
44
671
704
T: Brussels sprouts
451
396
44
671
704
U: Sweet potato
419
368
41
624
654
V: Field corn
332
291
32
494
518
W: Lettuce, head
413
363
40
615
645
X: Sorghum
413
363
40
615
645
Y: Celery
413
363
40
615
645
Z: Horseradish
413
363
40
615
645
AA: Potato
413
363
40
615
645
AB: Radish
413
363
40
615
645
AC: Rice
293
257
29
436
457
AD: Beans
314
276
31
468
491
AE: Okra
338
297
33
503
528
AF: Sugar beet
247
217
24
368
386
AG: Alfalfa
231
203
23
343
360
AH: Pasture
247
217
24
368
386
AI: Grass for seed
247
217
24
368
386
AJ: Rangeland
154
135
15
229
240
AK: Melon
211
185
21
313
329
AL: Roses
211
185
21
313
329
AM: Rights-of-way
165
145
16
246
258
AN: Wasteland
165
145
16
246
258
AO: Non-urban forests
195
171
19
291
305
AP: Rural shelter belts
195
171
19
291
305
AQ: Ticks
358
315
35
533
559
'For specific uses associated with each crop group see Table 5. 2A1so represent EECs for small terrestrial invertebrates.
Page 85 of 160
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3.2.3. Spray Drift Modeling
In order to determine terrestrial habitats of concern due to carbaryl exposures through spray drift,
it is necessary to estimate the distance spray applications can drift from the treated field and still
be greater than the level of concern. For this assessment, the level of concern for the most
sensitive endpoint and exposure duration is used. When this is expressed as an equivalent rate
per unit area, it is 5 x 10"4 lb a.i./A. This assessment used the AgDisp model. AgDisp (version
8.13; dated 12/14/2004) (Teske and Curbishley, 2003) It was used to simulate both aerial and
ground applications. For simulation requiring estimates of drift beyond 2400 ft, the Gaussian
farfield extension mode in AgDisp was used.
Scenario and management practice input parameters for AgDisp fall into three categories. First
are parameters for which there is current guidance. In all cases, there was no information from
carbaryl labels relevant to these parameters so they have been set to the default values
recommended by the current draft EFED Guidance for AgDisp (EFED 2005). Second are the
default input values for AgDisp that do not affect the results of these calculations, or are
reference variables whose value would only be changed under special circumstances. "Wind
speed" is an example of the former and "Height for wind speed measurement" is an example of
the latter. These parameters have 'NA' for not applicable in the quality column. Third are the
parameters for which no current guidance is available and the default value for AgDisp was used
for the input parameter for this set of simulations. The justification for these parameters is
"program default" in Table 18.
The quality column in Table 18 provides some qualitative characterization regarding the
confidence in the accuracy of that input parameter. When little or no information is available to
support the value of a particular input parameter, the characterization in the quality column is
poor. In many cases, when this occurs, the variable is set to a value that will produce drift values
greater than those than that would actually occur, so the results will likely be conservative and
protective. When the amount of information supporting a parameter value is typical, the
characterization is 'good' and the characterization is 'very good' or 'excellent' when several
measurements of high quality support the value for the parameter.
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Table 18. Scenario and standard management input parameters for simulation of carbaryl in spray drift
using AgDisp with Gaussian far-field extension.
Parameter
Value
Justification
Quality
Nozzle type1
Flat fan
Program default
Poor
Boom Pressure1
601b
Program default
Poor
Spray lines
20
Program default
Poor
Nozzles
42
None available
Poor
Droplet Size Distribution (DSD)
Fine to very fine
Default; draft guidance
NA
Swath Width
60 ft
Program default
good
Wind Speed
15 mph
Default; draft guidance
good
Wind direction
-90°
Default
NA
Air temperature
65° F
Program default
poor
Relative Humidity
50%
Program default
poor
Spray Material
Water
Program default
good
Fraction of active solution that is non-
0.1
Program default
poor
volatile
Fraction of additive solution that is
0.1
Program default
poor
non-volatile
Upslope angle
0°
Assume flat surface
good
Side slope angle
0°
Assume flat surface
god
Canopy type
none
Default from guidance
por
Surface roughness
0.0246 ft
Program default, none provided
poor
Transport
Oft
Program default
poor
Height for wind peed measurement
6.56 ft
Program default
Good
Maximum comp. Time
600 sec
Program default
NA
Maximum downwind distance
2608.24 ft
Program default
NA
Vortex decay rate OGE
0.03355
Program default
NA
Vortex decay rate IGE
1.25
Program default
NA
Aircraft drag coefficient
0.1
Program default
NA
Propeller efficiency
0.8
Program default
NA
Ambient pressure
29.91
Program default
NA
Ground reference
Oft
Program default
NA
Evaporation rate
84.76 (xg-(K-s)"1
Program default
NA
Specific Gravity (non-volatile)
1.0
Program default
poor
1 parameter for ground spray only
AgDrift input parameters that vary with the crop and application type are in Table 19. These use
patterns serve as surrogates for all the use patterns in the assessment. Surrogacy relations are
detailed in Appendix A. The ground spray for carbaryl is a foliar spray made directly to the plant
canopy. For this application, a height of 6 inches is the most appropriate as the spray is usually
made close to the ground surface; however, AgDisp does not produce reliable values for these
simulations when the spray height was set at less than 3 ft. The default release height of 15 ft is
used for aerial applications in the absence of other label directions. Spray volumes are the
minimum spray volumes from carbaryl labels for each crop. The non-volatile fraction, active
fraction and specific gravity were calculated from label information according to current
guidance (EFED 2005). The default V2 swath displacement was used with the aerial spray for
lettuce as it is standard practice for aerial sprays, but was not used with the ground sprays.
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Table 19. AgDrift Input parameters that vary with crop and formulation.
Crop Grouping
App method
Release
Height
Swath
Displacement
Spray
Volume
(Sal)
Non-
volatile
Fraction
Active
Fractio
n
Specific
Gravity of
Carrier
A: home lawn
Ground
4 ft
None
2.28
1
.43
1.089
B, D: parks
Ground
4 ft
None
2
1
.43
1.089
C: lawns 2
Ground
4 ft
None
2
0.98
0.42
1.089
F: citrus
Aerial
15 ft
Vi swath
10
0.4
0.17
1.089
G: olives
Aerial
15 ft
Vi swath
10
0.188
0.081
1.089
H: almonds
Aerial
15 ft
Vi swath
10
0.125
0.054
1.089
I: flowers
Aerial
15 ft
Vi swath
2
0.53
0.23
1.089
J: peaches
Aerial
15 ft
Vi swath
10
0.125
0.081
1.089
K: asparagus
Aerial
15 ft
Vi swath
2
.5
0.22
1.089
L: apple
Aerial
15 ft
Vi swath
10
0.075
0.032
1.089
N: sweet corn
Aerial
15 ft
Vi swath
2
0.25
0.11
1.089
O: grapes
Aerial
15 ft
Vi swath
10
0.05
0.022
1.089
AD: rice
Aerial
15 ft
Vi swath
2
0.19
0.081
1.089
AF: okra
Ground
4 ft
None
2
0.19
0.081
1.089
AL: rangeland
Aerial
15 ft
Vi swath
2
0.125
0.054
1.089
AR: ticks
Ground
4 ft
None
2
0.250
0.108
1.089
Carbaryl labels do not indicate a minimum volume for ground sprays, only to 'Apply in
sufficient volume for adequate coverage of all crops and sites.' For these simulations, a volume
of 2 gal/acre was used as this was the minimum recommendation for aerial application, since no
value for ground spray could otherwise be established. In most cases, it would be expected that a
larger volume would be used for ground sprays and this would be expected to reduce drift
distances. A volume of 2.28 rather than 2 gal/acre was used for home lawns as this was the
minimum volume that contained the application rate.
Table 20 presents the results of the AGDISP modeling and shows the minimum distance, for
selected surrogate crops, where the area-based concentration of carbaryl is below the LOC of
3.81 xlO"2 kg-ha"1. This value was estimated using TREX as the greatest single application rate
that would not exceed the RQ at the endangered species (listed species) level of concern of 0.1
for birds eating insects which is being used as a surrogate for terrestrial-phase CRLF. It is
important to note that this particular value is based on a study where no effect was seen for
mallard duck, so it only indicates that the toxicity is greater than the highest value measured in
the study. This makes these overestimates of the drift buffer needed for protection of the CRLF,
but shorter distances cannot be established as the level which an effect would be expected to
occur has not been established.
As would be expected, the distance from the aerial application to lettuce is considerably larger
than for the ground spray uses. Most drift events would be expected to have shorter distances due
to lower wind speed. In addition, a fine to very-fine spray has been assumed for the ground
sprays and ground equipment generally produces a coarser spray. However, there is no language
restricting the spray quality on the carbaryl labels so the fine to very spray was used as it is the
default in the absence of other label instructions.
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Table 20. Distance from the edge of the treated field to get below LOC for crops with aerial or ground spray
Use Pattern
App Rate (lb-acre"1)
Distance, 15 mph wind speed
A: Home lawn (ground)
9
2260 ft
B, D: parks (ground)
8
2205 ft
C: lawns 2 (ground)
7.8
2216 ft
F: Citrus (air)
16
10920 ft
G: olives (aerial)
7.5
7836 ft
H: almonds (aerial)
5
6184 ft
I: flowers (aerial)
4.3
6293 ft
K: asparagus (aerial)
4
6238 ft
L: apples (aerial)
3
4451 ft
N: sweet corn (aerial)
2
4827 ft
O: grapes (aerial)
2
3521 ft
AD: rice (aerial)
1.5
4159 ft
AF: okra (ground)
1.5
1725 ft
AL: rangeland (aerial)
1
3293 ft
AR: ticks (ground)
2
2159 ft
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4. Effects Assessment
This assessment evaluates the potential for carbaryl to affect the CRLF. As previously discussed
in Section 2.7, assessment endpoints for the CRLF include direct toxic effects on the survival,
reproduction, and growth of the CRLF itself, as well as indirect effects, such as reduction of the
prey base and/or modification of its habitat leading to effects on survival, growth or
reproduction. Direct effects to the CRLF in aquatic habitats are based on toxicity information for
freshwater vertebrates, including fish, which are generally used as a surrogate for amphibians, as
well as available amphibian toxicity data from the open literature. Direct effects to the CRLF in
terrestrial habitats are based on toxicity information for birds, which are generally used as a
surrogate for terrestrial-phase amphibians. Given that the CRLF's prey items and habitat
requirements are dependent on the availability of freshwater aquatic invertebrates and aquatic
plants, fish, frogs, terrestrial invertebrates and terrestrial mammals, toxicity information for these
organisms is also discussed. Acute (short-term) and chronic (long-term) toxicity information is
characterized based on registrant-submitted studies and a comprehensive review of the open
literature on carbaryl. A summary of the available freshwater ecotoxicity information, use of the
probit dose response relationship, and the incident information for carbaryl are provided in
Sections 4.1 through 4.4, respectively. A detailed summary of the available ecotoxicity
information for carbaryl formulated products is presented in Appendix M.
The available information indicates that aquatic organisms are more sensitive to the technical
grade (TGAI) than the formulated products of carbaryl (Section 4.3 and Appendix M);
therefore, the focus of this assessment is on the TGAI of carbaryl.
Toxicity endpoints are established based on data generated from guideline studies submitted by
the registrant, and from open literature studies that meet the criteria for inclusion into the
ECOTOX database maintained by EPA/Office of Research and Development (ORD) (U.S. EPA,
2004). Open literature data presented in this assessment were obtained from the 2003 carbaryl
IRED (U.S. EPA, 2004b) as well as information obtained from ECOTOX on December 14,
2006. The December 2006 ECOTOX search included all open literature data for carbaryl and 1-
naphthol {i.e., pre- and post-IRED). In order to be included in the ECOTOX database, papers
must meet the following minimum criteria:
• the toxic effects are related to single chemical exposure;
• the toxic effects are on an aquatic or terrestrial plant or animal species;
• there is a biological effect on live, whole organisms;
• a concurrent environmental chemical concentration/dose or application rate is reported;
and
• 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, open literature effects data that are more conservative than the registrant-submitted data
are considered. Studies relevant to carbaryl that were accepted by ECOTOX and/or OPPTS are
identified in Appendix N, as well as carbaryl studies that were rejected by ECOTOX and/or
OPPTS.
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Toxicity testing reported in this section does not represent all species of bird, mammal, or
aquatic organism. Only a few surrogate species for both freshwater fish and birds are used to
represent all freshwater fish (2000+) and bird (680+) species in the United States. For
mammals, acute studies are usually limited to Norway rat or the house mouse. Estuarine/marine
testing is usually limited to a crustacean, a mollusk, and a fish. Also, neither reptiles nor
amphibians are tested. The assessment of risk or hazard makes the assumption that avian and
reptilian toxicities are similar. The same assumption is used for fish and amphibians.
4.1. Evaluation of Aquatic Ecotoxicity Studies for Carbaryl
As described in the Agency's Overview Document (U.S. EPA, 2004), the most sensitive
endpoint for each taxon is evaluated. For this assessment, evaluated taxa relevant to the aquatic
habitat of the CRLF include freshwater fish, freshwater aquatic invertebrates, and freshwater
aquatic plants. Currently, no guideline tests exist for frogs. Therefore, surrogate species are
used as described in the Overview Document (U.S. EPA, 2004). In addition, aquatic-phase
amphibian ecotoxicity data from the open literature are qualitatively discussed. Table 21
summarizes the most sensitive ecological toxicity endpoints for the CRLF, its prey and its
habitat, based on an evaluation of both the submitted studies and the open literature, as
previously discussed. A brief summary of submitted and open literature data considered relevant
to this ecological risk assessment for the CRLF is presented below. Additional information is
provided in Appendix I
Table 21. Summary of acute and chronic aquatic toxicity estimates using technical grade carbaryl.
Species
Acute Toxicity
Chronic Toxicity
96-hr LC50
(mg/L)
MRID
NOEC/LOEC
(mg/L)
Affected
Endpoint
MRID
Atlantic Salmon
Salmo salar
0.220
40098001
0.00681
-
-
Fathead Minnow
Pimephales promelas
7.7
-
0.21 / 0.68
reduced
growth
TOUCAR05
Stonefly
Chloroperla grammatica
0.0017
400980-01
0.00052
Water flea
Daphnia magna
0.0056
-
0.0015 /0.0033
reproduction
00150901
Freshwater diatom
Navicula spp.
14-day
EC50=0.66
-
-
-
-
Duckweed
Lemna gibba
14-day
EC50=1.5
-
-
-
-
1 Estimated NOEC using acute to chronic ratio for fathead minnow.
2 Estimated NOEC using acute to chronic ratio for Daphnia magna
Acute toxicity to aquatic fish and invertebrates is categorized using the system shown in Table
22 (U.S. EPA, 2004). Toxicity categories for aquatic plants have not been defined. Based on
Page 91 of 160
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these categories, at most, carbaryl is classified highly toxic to freshwater fish and very highly
toxic to invertebrates on an acute exposure basis.
Table 22. Categories of Acute Toxicity for Aquatic Organisms.
LCS0 (^g/L)
Toxicity Category
< 100
Very highly toxic
> 100 - 1,000
Highly toxic
> 1,000 - 10,000
Moderately toxic
> 10,000 - 100,000
Slightly toxic
> 100,000
Practically nontoxic
4.1.1. Toxicity to Freshwater Fish
The available open literature information on carbaryl toxicity to aquatic-phase amphibians,
which is provided in Section 4.1.2, shows that acute and chronic ecotoxicity endpoints for
amphibians are generally less sensitive than fish. Therefore, endpoints based on freshwater fish
ecotoxicity data are assumed to be protective of potential direct effects to aquatic-phase
amphibians, including the CRLF. A summary of acute and chronic freshwater fish data,
including sub-lethal effects, is provided below.
4.1.1.1. Freshwater Fish: Acute Exposure (Mortality) Studies
On an acute exposure basis, technical grade (purity > 90%) carbaryl ranged in toxicity from
highly to slightly toxic (LC50 = 0.22 - 20 mg/L) to freshwater fish and to fish that spend a portion
of their life cycle in fresh water, such as the Atlantic salmon (Salmo salaf).
Acute, 96-h LC50 values are available for 19 studies, which include data for 17 species and 11
fish genera. A quantitative distribution is established for this set of data; including studies
classified acceptable or supplemental. The average of the Logio values of the LC50 values for a
species is calculated. Then, the average of the Logio values of the genera are calculated. A semi-
lognormal distribution is used to estimate the sensitivity distribution by considering the mean
and standard deviation of all genus mean values. A full description of the data and results used
to derive these distributions is included in Appendix L. The lower 95th percentile of the fish
distribution (472 |ig/L) indicates that the use of the lowest available toxicity value (220 |ig/L) is
likely a conservative estimate of the toxicity of carbaryl to freshwater vertebrates (Figure 17).
Page 92 of 160
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1
0.9 -
0.8 -
0.7 -
0.6 -
a
o
o 0.5 ¦
Q.
O
^ 0.4 -
0.3 ¦
0.2 ¦
0.1 -
0 -I—
100
Figure 17. Fish sensitivity distribution based 96-h LC50 values from acute exposures of fish to carbaryl.
4.1.1.2. Freshwater Fish: Chronic Exposure (Growth/Reproduction) Studies
Similar to the acute data, chronic freshwater fish toxicity studies are used to assess potential
direct effects to the CRLF because direct chronic toxicity guideline data for frogs do not exist.
Chronic exposure of fathead minnows {Pimephales promelas) to carbaryl resulted in reduced
survival and reproductive effects (NOEC = 0.210 mg/L) including reduced number of eggs per
female and reduced number of eggs spawned. However, since Atlantic salmon are the most
sensitive species on an acute exposure basis and no chronic toxicity data are available, an acute-
to-chronic ratio was used to estimate the chronic toxicity of carbaryl to Atlantic salmon. Based
on the information contained in the carbaryl IRED (USEPA 2004b), the 96-hr acute LC50 value
for fathead minnows is 7.7 mg/L. With an acute LC50 of 7.7 mg/L and a chronic NOEC of 0.21,
the acute-to-chronic ratio (ACR) for fathead minnow is 36.7 (7.7-KX21). When the ACR is
applied to the Atlantic salmon data, the resulting estimated NOAEC is 0.0068 mg/L.
With respect to ecological incidents involving fish reported in the Ecological Incident
Information System, a total of three fish-kill incidents were reported for carbaryl. Only one of
those incidents, report #B0000-501-92, could be credibly associated with a specific carbaryl use,
i.e., to control gypsy moth in New Jersey.
4.1.2. Toxicity to Aquatic-phase Amphibians
Available toxicity information on potential carbaryl-related mortality and sub-lethal effects to
aquatic-phase amphibians from the open literature is summarized below in Sections 4.1.2.1 and
4.1.2.2, respectively. Although useful for characterization purposes, amphibian specific data
were not considered useful for quantification of RQs for direct effects to the CRLF. Guideline
ecotoxicity studies for amphibians are not available.
Mean distribution
Lower distribution
Upper Distribution
X Mean Genus Values
x Ictalurus LC50 = 12,482
Lepomis LC50 = 8917
Pimephales LC50 = 7700
/
K.f/ Micropterus LC50 = 6400
/
>* Cyprinus LC50 = 5280
Pomoxis LC50 = 2600
Oncortiynchus LC50 = 1826
Salvelinus LC50 = 1439
'lit Salmo LC50 = 1255
-' Perca LC50 = 350
1000
10000
100000
Concentration (ppb)
Page 93 of 160
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The majority of data available on amphibians focused on the aquatic-phase larval (tadpole) stage
of frogs. Carbaryl ranged from moderately toxic (96-hr LC50 = 8.4 mg/L) to Southern leopard
frogs (Rana sphenocephalia) to slightly toxic (96-hr LC50 = 12.2 mg/L) to boreal toads (Bufo
boreas) on an acute exposure basis (Appendix I). In toxicity testing with formulated product
(purity = 50%) carbaryl was practically nontoxic to bullfrogs (Rana catesbeiana) with an LD50
greater than 4,000 mg/kg (MRID 00160000). The sensitivity of tadpoles to carbaryl exhibited
considerable intra- and interspecies variability. Depending on the stage of development, the
conditions of exposure, and which frog populations were sampled, frog susceptibility to carbaryl
varied. For example, the 96-hr LC50 for green frogs (Rana clamitans) roughly doubled when
temperature dropped from 27°C (LC50 = 11.3 mg/L) to 17°C (LC50 = 22 mg/L).
The U. S. Geological Survey Biological Resource Division's Columbia Environmental Research
Center has examined the effects of carbaryl on amphibians (Appendix I). These studies have
shown that frogs can exhibit considerable intraspecies (Boone and Bridges 1998) and
interspecies (Boone and Semlitsch 2002) variability in their response to carbaryl exposure.
Genetic factors and stage of development during which exposure took place can impact the
vulnerability of frogs. For example, frogs exposed during egg stage had lower weights than
corresponding control animals and nearly 18% of leopard frogs exposed to carbaryl during
development exhibited some type of developmental deformity (including visceral and limb
malformations). Additionally, environmental conditions such as temperature appear to impact
the sensitivity of frogs to carbaryl. In a 96-hr acute toxicity study, green frogs (Rana climitans)
had an LC50 of 22.0 mg/L at 17°C but at 27 °C the LC50 was roughly half (96-hr LC50 = 11.32
mg/L) (Boone and Bridges 1998).
Furthermore, in studies comparing the direct toxicity of carbaryl to Southern leopard frog (Rana
sphenocephala) larvae and fish, tadpoles were relatively tolerant (96-hr LC50 = 8.4) to carbaryl
compared to bluegill sunfish (96-hr LC50 = 6.2 mg/L), fathead minnow (96-hr LC50 = 5.21 mg/L)
and rainbow trout (LC50 = 1.88 mg/L). The study also reports the 96-hr LC50 (12.31 mg/L) for
the boreal toad (Bufo boreas); these data suggest that the surrogate fish species used to evaluate
the toxicity of carbaryl are protective for amphibians (Bridges et al. 2002).
Several studies have suggested that carbaryl exposure impairs predator avoidance behavior in
frogs (Bridges 1997; Bridges 1999), affects the length of time required for tadpoles to complete
metamorphosis into adults (Boone and Semlitsch 2002), and affected the weight of animals
undergoing metamorphosis. Carbaryl concentrations greater than 3.5 mg/L significantly affected
the time tadpoles spent being active where control animals exhibited greater sprint speeds and
were able to swim greater distances (Bridges 1997). Slower swimming speeds, altered activity
patterns and prolonged juvenile stages have been suggested as increasing the vulnerability of
frogs to predation (Bridges 1997; Bridges 1999; Relyea and Mills 2001) and/or that the threat of
predation renders the animals more susceptible to the direct toxicity of carbaryl (Relyea and
Mills 2001). While the Relyea and Mills paper indicates that carbaryl was 2 to 4 times more
lethal to gray treefrogs (Hyla versicolor) in the presence of a predator, the study is confounded
by the potential effects of water quality on mortality (Appendix I).
Increased vulnerability to predation assumes that only the prey species are incapacitated by
carbaryl. The Bridges (1999) study indicates however, the predators may also be impacted and
Page 94 of 160
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that gray treefrogs actually spent less time being active, but that the active times were primarily
spent foraging. However, in some cases, it is unclear whether the effects of carbaryl on
amphibians have been entirely adverse. For example, Southern leopard frogs exposed to
carbaryl at 5 mg/L exhibited a 20% increase in weight at metamorphosis (Bridges and Boone,
2003) and that at concentrations as high as 7 mg/L, Woodhouse's toad (Bufo woodhousii)
survival was roughly 30% higher than controls (Boone and Semlitsch, 2002). The increase in
weight of leopard frogs was attributed to the indirect effect of carbaryl in reducing zooplankton
that would normally have competed with tadpoles for phytoplankton. With zooplankton
numbers reduced by carbaryl treatments, phytoplankton increased thereby increasing the amount
of food available to tadpoles. However, aquatic-phase amphibians such as salamander that
forage on zooplankton would not likely benefit since their food source would be diminished.
Additionally, open literature suggests that the toxicity of carbaryl to amphibians is enhanced in
the presence of light (Zaga et al. 1998); the study reports that in the absence of simulated
sunlight, the 96-hr LC50 for larval African clawed frogs (Xenopus laevis) and gray treefrogs
(Hyla versiocolor) are 1.73 and 2.47 mg/L, respectively (Appendix I). In the presence of
simulated light, the number of mortalities was higher; however, the study did not provide revised
96-hr LC50 estimates for the combination of carbaryl plus simulated sunlight. The extent to
which sunlight can increase the sensitvity of aquatic-phase amphibians to carbaryl is uncertain.
On a chronic exposure basis, carbaryl has been shown to have the potential to affect amphibians.
Southern leopard frog tadpoles exposed to carbaryl during development exhibited developmental
deformities including both visceral and limb malformations when compared to less than 1% in
control tadpoles (Bridges, 2000). Although the length of the larval period was the same for all
experimental groups, tadpoles exposed throughout the egg stage were smaller than their
corresponding controls. However, in some cases, it is unclear whether the effects of carbaryl on
amphibians have been entirely adverse. For example, Southern leopard frogs exposed to
carbaryl at 5 mg/L exhibited a 20% increase in weight at metamorphosis (Bridges and Boone
2003) and that at concentrations as high as 7 mg/L, Woodhouse's toad (Bufo woodhousii)
survival was roughly 30% higher than controls (Boone and Semlitsch 2002).
None of the amphibian toxicity data reviewed in the open literature was considered sufficiently
robust to use quantitatively for risk assessment purposes. The available lines of evidence suggest
however, that both aquatic and terrestrial-phase amphibians are less sensitive to carbaryl than the
most sensitive fish discussed in the preceding sections. The open literature is useful in
characterizing potential indirect effects of carbaryl that may impact aquatic-phase amphibians,
particularly as they relate to reductions in zooplankton (Bridges and Boone 2003).
4.1.3. Toxicity to Freshwater Invertebrates
Freshwater aquatic invertebrate toxicity data are used to assess potential indirect effects of
carbaryl to the CRLF. Direct effects to freshwater invertebrates resulting from exposure to
carbaryl may indirectly affect the CRLF via reduction in available food. As discussed in
Attachment 1, 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 tadpoles
feeding exclusively in water and consuming diatoms, algae, and detritus (USFWS 2002). Post-
Page 95 of 160
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metamorphic terrestrial-phase CRLFs feed on aquatic and terrestrial invertebrates found along
the shoreline and on the water surface. Based on stomach content analysis, adults feed on a
variety of invertebrates with larger-sized frogs feeding on small fish, frogs, and small mammals
(Hayes and Tennant 1985).
A summary of acute and chronic freshwater invertebrate data, including published data in the
open literature since completion of the IRED (USEPA 2004b), is provided below in Sections
4.1.3.1 through 4.1.3.3,
4.1.3.1. Freshwater Invertebrates: Acute Exposure Studies
Technical grade carbaryl is very highly toxic to aquatic invertebrates with EC50 values ranging
from 0.0017 - 0.026 mg/L on an acute exposure basis. . Stoneflies (Isoroperla grammatica) are the
most sensitive freshwater invertebrate in an acute toxicity study (96-hr LC50=0.0017 mg/L). In
general, freshwater invertebrates exhibited the same sensitivity (EC50 range: 0.007 - 0.013
mg/L) to formulated end-use products (purity range: 44 - 81%). In studies examining the
toxicity of carbaryl to aquatic invertebrates in the presence of sediment, toxicity values were
more widely distributed (EC50 range 0.005 to > 2.5 mg/L) suggesting that a tendency of carbaryl
and its hydrolysis degradate 1-naphthol to partition to sediment may limit their bioavailability
and hence reduce toxicity under more natural exposure conditions.
Sensitivity distributions were developed for aquatic invertebrates using acute toxicity data in a
similar manner as described above for the freshwater fish distribution. Acute, EC50 values are
available for 12 studies, which include data for 9 species and 7 geniuses of aquatic invertebrates.
The lower 95th percentile of the invertebrate distribution (0.7 |ig/L) indicates that the use of the
lowest available toxicity value (1.7 |ig/L) is not as conservative as the value used for vertebrates
(Figure 18).
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1
Asellus EC50 = 280 x
X Mean Genus Values
- - Upper Distribution
¦ Lower distribution
Mean distribution
Procambarus EC50 = 1.8
0
¦x
1.0
10.0
100.0
1000.0
Concentration (ppb)
Figure 18. Invertebrate sensitivity distribution based 48-h and 96-h LC50 values from acute exposures of
invertebrates to carbaryl.
Studies have indicated that acute exposure to carbaryl impacts predator avoidance mechanisms in
invertebrates (Hanazato 1995), reduces overall zooplankton abundance (Havens 1995; Hanazato
1989), and may actually promote phytoplankton growth through reduced predation by
zooplankton (Bridges and Boone 2003). As discussed previously, though, while decreases in
zooplankton can benefit aquatic-phase amphibians that depend on phytoplankton, decreased
zooplankton can reduce growth and survival of those aquatic animals, such as salamanders, that
forage on zooplankton and that, in turn, serve as prey for adult CRLFs.
On a chronic exposure basis, carbaryl affected reproduction (NOEC = 0.0015 mg/L) in water
fleas (Daphnia magna). However, since stoneflies are the most sensitive invertebrate species on
an acute exposure basis and no chronic toxicity data are available, an acute-to-chronic ratio was
used to estimate the chronic toxicity of carbaryl to stoneflies. Based on the information
contained in the carbaryl IRED (USEPA 2004b), the 48-hr acute LC50value for Daphnia magna
is 0.0056 mg/L. With an acute LC50 of 0.0056 mg/L and a chronic NOEC of 0.0015, the acute-
to-chronic ratio (ACR) for D. magna is 3.73 (0.0056^-0.0015). When the ACR is applied to the
stonefly data (LC50 = 0.0017 mg/L), the resulting estimated NOAEC is 0.0005 mg/L.
4.1.4. Toxicity to Aquatic Plants
Aquatic plant toxicity studies are used as one of the measures of effect to evaluate whether
carbaryl may affect primary production. Primary productivity is essential for indirectly
4.1.3.2. Freshwater Invertebrates: Chronic Exposure Studies
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supporting the growth and abundance of the CRLF. In addition to providing cover, aquatic
plants harbor a variety of aquatic invertebrates that aquatic-phase CRLF eat.
Two types of studies are used to evaluate the potential of carbaryl to affect primary productivity.
Laboratory studies are used to determine whether carbaryl may cause direct effects to aquatic
plants. In addition, the threshold concentrations, described in Section 4.2, are used to further
characterize potential community level effects to CRLF resulting from potential effects to
aquatic plants. A summary of the laboratory data for aquatic plants is provided in Section
4.1.4.1
4.1.4.1. Toxicity to Freshwater Non-vascular Plants
Only two studies of the filamentous green algae Pseudokirchneriella subcaptitata were available
to assess the toxicity of carbaryl to aquatic plants. With technical grade carbaryl the
concentration inhibiting plant growth (in terms of number of algal cells) by 50% (IC50) was 1.27
mg/L. The most sensitive freshwater aquatic plant is the freshwater diatom Navicula with an
EC50 of 0.66 mg/L.
Carbaryl was roughly similar to the endpoint for formulated end-use product (IC50 = 3.2 mg/L).
In neither study were abnormalities in cell morphology or signs of phytotoxic effects observed.
As reported earlier, carbaryl use has been associated with increases in phytoplankton numbers.
Whether this is due to reduced predation by zooplankton as a result of their greater susceptibility
to carbaryl and/or a response to carbaryl's similarity to the plant auxin a-naphthalene acetic acid
is unclear.
4.1.4.1. Toxicity to Freshwater Vascular Plants
In a supplemental study (MRID 423721-02) with duckweed (Lemna gibbet), the 14-day EC50 was
1.5 mg/L based on reduced number of fronds. ECOTOX provided limited information on the
toxicity of carbaryl to aquatic plants. In a study by Peterson et al. 1994, a single concentration of
carbaryl (3.67 mg/L) resulted in 33% inhibition of L. gibba growth after 7-days static exposure
(Appendix I). Although the study suggests that carbaryl has an effect on vascular aquatic plant
growth, the study does not provide any information on dose response given that only a single
concentration was tested.
4.1.5. Freshwater Field Studies
Mesocosm studies with carbaryl provide measurements of primary productivity that incorporate
the aggregate responses of multiple species in aquatic communities. Because various aquatic
species vary widely in their sensitivity to carbaryl, the overall response of the aquatic community
may be different from the responses of the individual species measured in laboratory toxicity
tests. Mesocosm studies allow observation of population and community recovery from carbaryl
effects and of indirect effects on higher trophic levels. In addition, mesocosm studies, especially
those conducted in outdoor systems, incorporate partitioning, degradation, and dissipation,
factors that are not usually accounted for in laboratory toxicity studies, but that may influence the
magnitude of ecological effects.
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The baseline risk assessment science chapter in support of the reregi strati on eligibility decision
for carbaryl (USEPA 2003) reviewed several mesocosm studies of carbaryl and demonstrated
that overall the results of these studies are highly variable. Studying natural plankton
communities in enclosed mesocosms, Havens (1995) reports a decline in total zooplankton
biomass and individuals across the range of carbaryl treatments (0 - 100 ug/L). Furthermore, at
carbaryl concentrations greater than 20 |ig/L Daphnia were no longer found and at
concentrations above 50 |ig/L all cladocerans were eliminated, resulting in an increase in algal
biomass, representing a repartitioning of biomass from zooplankton to phytoplankton. Hanazato
(1995) exposed Daphnia ambigua to carbaryl and a kairomone released by the predator
Chaoborus (phantom midge) simultaneously. Daphnia developed helmets in response to the
kairomone, but not in response to carbaryl at 1-3 |ig/L. However, carbaryl enhanced the
development of high helmets and prolonged the maintenance period of the helmets in the
presence of the kairomone, suggesting that at low concentrations carbaryl can alter predator-prey
interactions by inducing helmet formation and vulnerability to predation in Daphnia. In related
mesocosms studies, exposure to carbaryl at 1 ppm killed all plankton species, including
Chaoborus larvae (Hanazato, 1989). However, this concentration is well above the maximum
EECs modeled for carbaryl, and it is unlikely that such high levels of this chemical would be
found under field conditions.
In some cases, mesocosms exposed to carbaryl exhibited transitory effects. In a study by Boone
et al. 2003 (Appendix I), carbaryl exposure significantly reduced chlorophyll concentrations 12-
day s after exposure; however, by the end of the study, there was no difference between carbaryl
treated and control groups. While these studies demonstrate that a range of factors, e.g.,
hyrdroperiod and larval density, can influence the effects of carbaryl alone or in combination
with other pesticides, e.g., atrazine, the sensitivity of the amphibians in these studies is less than
the surrogate fish species reported earlier.
4.2. Evaluation of Terrestrial Ecotoxicity Studies for Carbaryl
As described in the Agency's Overview Document (U.S. EPA, 2004), the most sensitive
endpoint for each taxon is evaluated. For this assessment, evaluated taxa include birds,
mammals, terrestrial invertebrates and terrestrial plants. Currently, no guideline tests exist for
frogs and thus, no toxicity data are currently required on amphibians. Therefore, surrogate taxa
(birds) were used as described in the Overview Document (U.S. EPA, 2004). Table 23
summarizes the most sensitive ecological toxicity endpoints for terrestrial-phase CRLF, based on
an evaluation of both the submitted studies and the open literature, as previously discussed. A
brief summary of submitted and open literature data considered relevant to this ecological risk
assessment for the CRLF are presented below. Additional information is provided in Appendix
I.
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Table 23. Summary of acute and chronic toxicity data for terrestrial organisms exposed to carbaryl
Species
Acute Toxicity
Chronic Toxicity
I - D511
(ppm)
MRID
5-day
lc50
(PPm)
MRID
NOEC/
LOEC
(PPm)
Affected
Endpoints
MRID
Mallard duck
Anas platyrhynchos
>2000
458206-01
>5000
00022923
300/600
decreased
number of
eggs
ACC263701
Honey bee
Apis mellifera
0.0011
05004151
--
--
--
--
--
Laboratory rat
Rattus norvegicus
301
00148500
--
--
75 / 300
decreased
pup
survival
447329-01
Similar to toxicity categories for aquatic organisms, categories of acute toxicity ranging from
"practically nontoxic" to "very highly toxic" have been established for terrestrial organisms
based on LD50 values (Table 24), and avian species based on LD50 values (Table 25). Subacute
dietary toxicity for avian species is based on the LC50 values (Table 26). Based on these
categories, carbaryl is practically nontoxic to birds and moderately toxic to mammals on an acute
exposure basis.
Table 24. Categories for mammalian acute toxicity based on median lethal dose in mg per kilogram body
LD5„ (mg a.i./kg)
Toxicity Category
<10
Very highly toxic
10-50
Highly toxic
51-500
Moderately toxic
501-2000
Slightly toxic
>2000
Practically non-toxic
Table 25. Categories of avian acute oral toxicity based on median lethal dose in milligrams per kilogram body
" v' ^
LD50 (ppm)
Toxicity Category
<10
Very highly toxic
10-50
Highly toxic
51-500
Moderately toxic
501-2000
Slightly toxic
>2000
Practically non-toxic
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Table 26. Categories of avian subacute dietary toxicity based on median lethal concentration in milligrams
LCso (ppm)
Toxicity Category
<50
Very highly toxic
50-500
Highly toxic
501-1000
Moderately toxic
1001-5000
Slightly toxic
>5000
Practically non-toxic
4.2.1. Toxicity to Birds
Carbaryl is practically nontoxic to birds on both an acute oral exposure (LD50 >2,000 mg/kg) and
subacute dietary exposure basis (LC50 >5,000 mg/kg of diet).
Acute oral toxicity estimates as low as 16 mg/kg and 56 mg/kg have been reported for starlings
(Sturnus vulgaris) and red-winged black birds (Agelaius phoeniceus), respectively (Schafer et al.
1983) and it is uncertain whether smaller passerine species may be more sensitive to the effects
of carbaryl. Although useful for characterization purposes, these data were not considered useful
for quantification of RQs for direct effects to the CRLF.
Exposure to carbaryl on a chronic basis resulted in adverse reproductive effects including
decreased number of eggs produced and decreased fertility (NOAEC = 300 mg/kg of diet).
A total of five incidents involving birds have been reported and entered into the Agency's
Ecological Incident Information System (EIIS) database. However, only two of the five appear
to be clearly attributable to carbaryl and only one of those two could be linked to a specific
registered use. The remaining incidents appear to have been associated with either intentional
poisoning or the co-occurrence of much more toxic pesticides. In one incident (1012817-001) a
single morning dove (Zenaida macroura) was discovered dead; the animal exhibited reduced
acetyl cholinesterase activity and had 2.4 mg/kg of carbaryl in its stomach contents. The report
suggests that birdseed around a feeder had become contaminated after carbaryl was applied to
the property owner's lawn. In a second incident (1000802-001), five blackbirds were discovered
dead. No residue analysis was conducted on the birds but carbaryl residues were detected in dead
squirrel found in the vicinity; acetyl cholinesterase activity was not reduced in the squirrel.
While these incidents do not provide substantial evidence that carbaryl is impacting birds in the
wild, they do emphasize the need to address the uncertainty regarding the sensitivity of passerine
species to carbaryl.
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4.2.2. Toxicity to Terrestrial-phase Amphibians
The EFED ecotoxicity database reports an LD50 of greater than 2000 mg/kg for terrestrial-phase
bullfrogs (R. catesbeiana).
4.2.3. Toxicity to Mammals
Carbaryl is moderately toxic (LD50 = 301 mg/kg) to mammals on an acute oral exposure basis
(Accession Number 00148500). Chronic exposure to carbaryl resulted in decreased second-
generation pup survival (NOEC = 75 mg/kg of diet; MRID 447329-01).
A total of two incidents were reported, one (1000802-001) involving a gray squirrel (Sciurus
carolinensis) and a second involving a hairytail mole (Parascalops breweri). In neither case was
information provided on the use of carbaryl that may have resulted in the deaths of these
animals.
4.2.4. Toxicity to Terrestrial Invertebrates
Carbaryl is highly toxic to honey bees (Apis mellifera) on an acute contact exposure basis (LD50
= 0.0011 mg/bee; Accession Number 05004151); however, acute contact toxicity testing of
carbaryl® SC indicates bees are less sensitive to the formulated product (LD50 = 0.0040 mg/bee).
Acute oral toxicity studies with carbaryl reveal that technical grade carbaryl (LD50 = 0.0001
mg/bee) is roughly ten times more toxic than the formulated soluble concentrate (Carbaryl® SC
LC50 = 0.0016 mg/bee). Carbaryl ranged from being moderately to highly toxic to predacious
insects, mites and spiders.
For RQ derivation, the LD50 for honeybees (1.1 |ig a.i./bee) is used. This toxicity value is
converted to units of |ig a.i./g (of bee) by multiplying by 1 bee/0.128 g thereby resulting in an
LD50 = 8.6 |ig a.i./g.
In a field study to examine the effects of carbaryl on bees when the chemical is used to thin fruit,
Carbaryl® SC applications to apple orchards at a rate of 0.8 lbs a.i./Acre did not have a
significant (P > 0.05) affect on bee mortality and/or behavior.
A total of 5 incidents related to carbaryl are reported in the EIIS database. Two of the reports
(1005855-001 and B0000-300-03) do not contain any data but rather reflect general concerns
expressed by the American Beekeeper Federation and the Honey Industry Council on the role of
pesticides in bee kills. The Honey Industry Council sited the specific use of carbaryl on alfalfa
during the day. In North Carolina (incident #1003826-021), a bee mortality was associated with
0.8 ppm carbaryl residues; however, in a second incident (#1003826-0090 in North Carolina, bee
mortality was more likely attributed to methyl parathion than carbaryl. Only in one incident
(1001611-002) was the use of carbaryl on a specific crop, i.e., asparagus in Washington, clearly
associated with carbaryl residues in dead bees. Subsequent to the publication of the ecological
risk assessment chapter in support of the reregi strati on eligibility decision on carbaryl, a number
of beekill incidents associated with the use of carbaryl have been identified. The majority of
these incidents (40+) had been reported in Washington State and were associated with a range of
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carbaryl uses. Additional incidents have been reported in Minnestota and were associated with
the use of carbaryl on poplar tree plantations.
4.2.5. Toxicity to Terrestrial Plants
In a Tier I vegetative vigor study involving 6 plant species (cabbage, cucumber, soybean, tomato,
onion and ryegrass), no effects to survival or dry weight were observed after a single treatment
of 0.8 lbs a.i./A (MRID 45784807).
4.3. Toxicity of formulated products containing carbaryl
As discussed previously, toxicity testing of carbaryl formulated product with aquatic animals has
indicated that none of the formulations tested were more toxic than the technical grade active
ingredient (Table 16). A review of formulated product testing conducted with rats indicates that
none of the formulated products (including those involving a second active ingredient, i.e.,
metaldehyde, were more toxic than the technical grade (Sevin® Technical LD50=614 mg/kg body
weight).
Table 27. Rat acute 96-hr oral toxicity test data for formulated products of carbaryl.
Formulated Product
Percent Active Ingredient
Rat Acute Oral LD50
(mg/kg body weight)
Sevin® Brand 85 Sprayable Insecticide
85% Carbaryl
>50
Sevin® Technical
99.45%
614
Sevin® XLR Plus Carbaryl Insecticide
44.1%
698.5
Sevin® Brand Granular Insecticide
7%
3240
Sevin® 5 Bait
5%
3129
Sevin® 10% Granules
10%
3620
Turf Pride Fertilizer with 2% Sevin®
2%
3129
Corry's Slug, Snail and Insect Killer
5% carbaryl
2% metaldehyde
>5000
Anderson's 8% Granular
8%
1750
GrubTo®x Lawn Grub and Insect Killer
4.6%
3129
Bonide® Slug, Snail and Sowbug Bait
5% carbaryl
2% metaldehyde
>5000
Sevin® 4% Plus Fertilizer
4%
5000
Sevin® Brand Granular Insecticide
6.3%
>5000
4.4. Evaluation of Aquatic Ecotoxicity Studies for 1-Naphthol
Acute toxicity testing of carbaryl's hydrolysis degradate 1-naphthol in fish shows that the
compound ranged from being moderately to highly toxic (LC50 range 0.75 - 1.6 mg/L). Chronic
exposure of fathead minnows to 1-naphthol reduced larval growth and survival (NOEC = 0.1
mg/L). No data are available on the acute or chronic toxicity of 1-naphthol to amphibians. For
freshwater invertebrates, 1-naphthol ranged from moderately to highly toxic (EC50 range: 0.2 -
3.3 mg/L).
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5. Risk Characterization
Risk characterization is the integration of the exposure and effects characterizations to determine
the potential ecological risk from varying carbaryl use scenarios within the action area and
likelihood of direct and indirect effects on the CRLF. The risk characterization provides an
estimation and description of the likelihood of effects; it articulates risk assessment assumptions,
limitations, and uncertainties; and synthesizes an overall conclusion regarding the effects
determination (i.e., "no effect," "likely to adversely affect," or "may affect, but not likely to
adversely affect") for the CRLF.
5.1. Risk Estimation
Risk is estimated by calculating the ratio of exposure to toxicity. This ratio is the risk quotient
(RQ), which is then compared to established acute and chronic levels of concern (LOCs) for each
category evaluated (Appendix J). For acute exposures to the CRLF and its animal prey in
aquatic habitats, as well as terrestrial invertebrates, the LOC is 0.05. For acute exposures to the
CRLF and mammals, the LOC is 0.1. The LOC for chronic exposures to CRLF and its prey, as
well as acute exposures to plants is 1.0.
Screening-level RQs are based on the most sensitive endpoints and modeled EECs in aquatic
systems from the following scenarios for carbaryl:
• Multiple applications to urban environments (home gardens, lawns, parks) at rates
equivalent to 4 to 9 lbs a.i./A.
• Applications to citrus with single applications up to 16 lbs a.i./A
• Applications to nurseries at 4.3 lbs a.i./A
• Multiple applications to peaches and asparagus at up to 4 lbs a.i/A) and a single dormant
application to peaches at 5 lbs a.i./A
• Multiple applications to orchards at up to 3 lbs a.i./A
• Multiple applications to vegetable crops, grapes, strawberries and peanuts at up to 2 lbs
a.i./A
• Multiple applications to rice at 1.5 lbs a.i./A
• Multiple applications to pasture, alfalfa, grass for seed, sugar beets, tomatoes and row
crops at 1.5 lbs a.i./A
• Multiple applications to rangeland, melons, roses, rights-of-way, wastelands, non-urban
forests and rural shelters at 1 lb a.i./A.
For developing RQs for the terrestrial-phase CRLF and its prey (e.g. terrestrial insects and
small mammals), exposures to carbaryl resulting from foliar applications of carbaryl are
modeled. These included applications to turf, outdoor ornamentals, olives, fruit and nut orchards,
vineyards, vegetables, grains, melons, trees and range/pasture lands. Maximum application rates
and numbers of application for each crop were modeled according to the list above.
While exposures of terrestrial plants inhabiting dry and semi-aquatic habitats, single maximum
applications of each use could be modeled, including applications involving foliar and soil-
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incorporation methods; however, no toxicity data are available with which to evaluate potential
risk.
5.1.1. Exposures in the Aquatic Habitat
5.1.1.1. Direct Effects to CRLF
For assessing acute risks of direct effects to the CRLF, l-in-10 year peak EECs in the standard
pond are used with the lowest acute toxicity value for fish. For chronic risks, l-in-10 year peak
60-day EECs and the lowest chronic toxicity value for fish are used. Resulting acute RQs exceed
the acute listed species LOC (0.05) across all of the uses modeled except applications to flowers
around buildings, ornamentals, parks, peaches, asparagus, dry beans, okra, alfalfa, grass for seed
and melons. RQs exceed the chronic risk LOC (1.0) for carbaryl applications to lawns,
ornamentals, citrus, olives, almonds, peaches, asparagus, apples, loquat, sweet corn, grapes,
strawberries, tomatoes, broccoli, Brussels sprouts, sweet potatoes, corn, head lettuce, celery,
horse radish, potatoes, rice, rights-of-way, wasteland and rural shelter belts (Table 28).
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Table 28. Risk Quotient values for acute and chronic exposures directly to the CRLF in aquatic habitats,
Crop Group1
Peak EEC (H&/L)
60-d EEC
(H«/L)
Acute
RQ2
Chronic
RQ5
A: Home lawn
14.6
5.25
0.073
0.77
B: Flowers around buildings
0.47
0.15
0.002
0.02
C: Lawns
25.4
12.4
0.123
1.824
D: Ornamentals
51.2
16
0.233
2.354
E Parks
10
3.7
0.045
0.54
F: Citrus 1
33.2
15.4
0.153
2.264
F: Citrus 2
44.7
11.8
0.203
1.744
G Olives
52.6
18.9
0.243
2.784
H: almonds
43.3
17.5
0.203
2.574
I: flowers
21.4
6.7
0.103
0.99
J: peaches
56.8
17
0.263
2.504
K: asparagus
47.2
13.4
0.213
1.974
L: apple
16.3
9.3
0.073
1.374
M: loquat
13
7.5
0.063
1.104
N: sweet corn
24.8
10.7
0.113
1.574
O: grapes
22.4
11.9
0.103
1.754
P: strawberries
100.2
39.7
0.463
5.844
Q: tomatoes
24.5
11
0.113
1.624
R peanuts
12.9
5.6
0.063
0.82
S broccoli
73
26.4
0.333
3.884
T Brussels sprouts
166.8
55.8
0.763
8.214
U sweet potatoes
49.7
19.6
0.233
2.884
V: Field corn
9.1
6
0.04
0.88
W: head lettuce
93.5
34.6
0.433
5.094
X: sorghum
11.4
4.1
0.053
0.60
Y: celery
37.9
11.6
0.173
1.714
Z: horse radish
71.8
22.8
0.333
3.354
AA: potato
42
12.5
0.193
1.844
AB: radish
13.3
4.8
0.063
0.71
AC: rice
2579
2579
11.73
3794
AD: dry beans
9.7
4.2
0.04
0.62
AE: okra
5.6
1.8
0.03
0.26
AF: sugar beet
13.6
5.4
0.063
0.79
AG: alfalfa
9.1
3.2
0.04
0.47
AF1: pasture
10.9
4.3
0.049
0.63
AI: grass for seed
7.1
3.1
0.03
0.46
AJ: rangeland
12.8
2.6
0.063
0.38
AK: melons
7.2
4
0.03
0.59
AL: roses
14.9
4.7
0.073
0.69
AM: rights of way
19
7.6
0.093
1.124
AN: wasteland
68
26.1
0.313
3.844
AO: non-urban forests
11.5
4.2
0.053
0.62
AP: rural shelter belts
41
14.9
0.193
2.194
AQ: Ticks
17.7
13.2
0.083
1.944
Based on 96-h LC50 = 0.220 mg/L for Atlantic salmon
3 exceeds listed species acute risk level of concern (RQ>0.05)
4 exceeds listed species chronic risk level of concern (RQ>1.0)
5 Based on Chronic NOEC of 0.0068 mg/L for Atlantic salmon
Page 106 of 160
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5.1.1.2 Indirect Effects to CRLF through effects to prey
For assessing risks of indirect effects of carbaryl to the aquatic-phase CRLF (tadpoles) through
effects to its diet, l-in-10 year peak EECs from the standard pond are used with the lowest acute
toxicity value for aquatic unicellular plants to derive RQs. Resulting RQs do not exceed the acute
risk LOC (RQ>1.0) for aquatic plants from carbaryl applications to any of the uses modeled
except rice (Table 29).
For assessing risks of indirect acute effects to the aquatic-phase CRLF through effects to prey
(invertebrates) in aquatic habitats, l-in-10 year peak EECs in the standard pond are used with the
lowest acute toxicity value for invertebrates. For chronic risks, l-in-10 year peak 21-day EECs
and the lowest chronic toxicity value for invertebrates are used to derive RQs. Acute and chronic
RQs exceed the LOCs (RQ>0.05 and RQ>1.0, respectively) for applications to all use groups
with the exception of carbaryl applications to flowers around homes; for this one use, the chronic
RQ value is below the chronic risk LOC (Table 30).
Fish and frogs also represent prey of CRLF. These RQs are represented by those used for direct
effects to the CRLF in aquatic habitats (Table 28). RQs exceed the acute risk LOC (0.05) across
all of the uses modeled except applications to flowers around buildings, ornamentals, parks,
peaches, asparagus, dry beans, okra, alfalfa, grass for seed and melons. RQs exceed the chronic
risk LOC (1.0) for carbaryl applications to lawns, ornamentals, citrus, olives, almonds, peaches,
asparagus, apples, loquat, sweet corn, grapes, strawberries, tomatoes, broccoli, Brussels sprouts,
sweet potatoes, corn, head lettuce, celery, horse radish, potatoes, rice, rights-of-way, wasteland
and rural shelter belts
5.1.2.3. Indirect Effects to CRLF through effects to habitat (plants)
For assessing risks of indirect effects of carbaryl to the aquatic-phase CRLF through effects to its
habitat, l-in-10 year peak EECs from the standard pond are used with the lowest acute toxicity
value for aquatic unicellular and vascular plants to derive 2 sets of RQs used to represent the
aquatic habitat. Resulting RQs do not exceed the acute risk LOC (RQ>1.0) for aquatic plants
from carbaryl applications to any of the uses modeled except rice (Table 31).
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Table 29. RQ values for exposures to unicellular aquatic plants (diet of CRLF in tadpole life stage)
Crop Group1
Peak EEC
(H«/L)
Indirect effects RQ
(unicellular plants)2
A: Home lawn
14.6
0.02
B: Flowers around buildings
0.47
<0.01
C: Lawns
25.4
0.04
D: Ornamentals
51.2
0.08
E Parks
10
0.02
F: Citrus 1
33.2
0.05
F: Citrus 2
44.7
0.07
G Olives
52.6
0.08
H: almonds
43.3
0.07
I: flowers
21.4
0.03
J: peaches
56.8
0.09
K: asparagus
47.2
0.07
L: apple
16.3
0.02
M: loquat
13
0.02
N: sweet corn
24.8
0.04
O: grapes
22.4
0.03
P: strawberries
100.2
0.15
Q: tomatoes
24.5
0.04
R: Peanuts
12.9
0.02
S: Broccoli
73
0.11
T: Brussels sprouts
166.8
0.25
U: Sweet potato
49.7
0.08
V: Field corn
9.1
0.01
W: Lettuce, head
93.5
0.14
X: Sorghum
11.4
0.02
Y: Celery
37.9
0.06
Z: Horseradish
71.8
0.11
AA: Potato
42
0.06
AB: Radish
13.3
0.02
AC: Rice
2579
3.913
AD: Beans
9.7
0.01
AE: Okra
5.6
0.01
AF: Sugar beet
13.6
0.02
AG: Alfalfa
9.1
0.01
AH: Pasture
10.9
0.02
AI: Grass for seed
7.1
0.01
A J: Rangeland
12.8
0.02
AK: Melon
7.2
0.01
AL: Roses
14.9
0.02
AM: Rights-of-way
19
0.03
AN: Wasteland
68
0.10
AO: Non-urban forests
11.5
0.02
AP: Rural shelter belts
41
0.06
AQ: Ticks
17.7
0.03
2 Based on EC50 = 0.66 mg/L for green algae
3 exceeds risk level of concern (RQ>1.0)
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Table 30. Risk Quotient (RQ) values for acute and chronic exposures to aquatic invertebrates (prey of CRLF
Crop Group1
Peak EEC (n#/L)
21-d EEC (ng/L)
Acute RQ2
Chronic RQ3
A: Home lawn
14.6
8.7
8.6"
17.4s
B: Flowers around buildings
0.47
0.29
0.34
0.6
C: Lawns
25.4
19
14.94
38.0s
D: Ornamentals
51.2
29.3
30.14
58.6s
E Parks
10
6.3
5.9"
12.6s
F: Citrus 1
33.2
22
19.54
44.0s
F: Citrus 2
44.7
25.2
26.3"
50.4s
G Olives
52.6
31.4
30.94
62.8s
H: almonds
43.3
29.1
25.5"
58.2s
I: flowers
21.4
13
12.64
26.0s
J: peaches
56.8
32.1
33.4"
64.2s
K: asparagus
47.2
26.5
27.8"
53.0s
L: apple
16.3
10.7
9.6"
21.4s
M: loquat
13
8.7
7.64
17.4s
N: sweet corn
24.8
18.7
14.64
37.4s
O: grapes
22.4
18.2
13.24
36.4s
P: strawberries
100.2
72.7
58.9"
145.4s
Q: tomatoes
24.5
17.1
14.44
34.2s
R: Peanuts
12.9
9
7.64
18.0s
S: Broccoli
73
47.5
42.9"
95.0s
T: Brussels sprouts
166.8
108.3
98.14
216.6s
U: Sweet potato
49.7
32
29.2"
64.0s
V: Field corn
9.1
6.2
5.44
12.4s
W: Lettuce, head
93.5
62.7
55.04
125.4s
X: Sorghum
11.4
7.4
6.1*
14.8s
Y: Celery
37.9
22.4
22.3"
44.8s
Z: Horseradish
71.8
43.2
42.2"
86.4s
AA: Potato
42
24.2
24.7"
48.4s
AB: Radish
13.3
8.6
7.8"
17.2s
AC: Rice
2579
2579
15174
5158s
AD: Beans
9.7
6.8
5.74
13.6s
AE: Okra
5.6
3.1
3.3"
6.2s
AF: Sugar beet
13.6
9.6
8.04
19.2s
AG: Alfalfa
9.1
5
5.44
10.0s
AH: Pasture
10.9
7.8
6.44
15.6s
AI: Grass for seed
7.1
4.7
4.24
9.4s
A J: Rangeland
12.8
7.7
7.54
15.4s
AK: Melon
7.2
5.4
4.24
10.8s
AL: Roses
14.9
8.9
8.8"
17.8s
AM: Rights-of-way
19
12.2
11.24
24.4s
AN: Wasteland
68
40
40.0"
80.0s
AO: Non-urban forests
11.5
8.2
6.8"
16.4s
AP: Rural shelter belts
41
28.7
24.1"
57.4s
AQ: Ticks
17.7
15.1
10.4"
30.2s
2 Based on 96-hLC50 = 0.0017 mg/L for Stonefly
3 Based on estimated chronic NOEC of 0.0005 mg/L for Stonefly
4 exceeds listed species acute risk level of concern (RQ>0.05)
5 exceeds listed species chronic risk level of concern (RQ>1.0)
Page 109 of 160
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Table 31. Risk Quotient (RQ) values for exposures to aquatic plants (representing aquatic habitat)
Crop Group1
Peak EEC
Indirect effects RQ
Indirect effects RQ
Oig/L)
(unicellular plants)2
(vascular plants)3
A: Home lawn
14.6
0.02
0.01
B: Flowers around buildings
0.47
<0.01
<0.01
C: Lawns
25.4
0.04
0.02
D: Ornamentals
51.2
0.08
0.03
E Parks
10
0.02
0.01
F: Citrus 1
33.2
0.05
0.02
F: Citrus 2
44.7
0.07
0.03
G: Olives
52.6
0.08
0.04
H: almonds
43.3
0.07
0.03
I: flowers
21.4
0.03
0.01
J: peaches
56.8
0.09
0.04
K: asparagus
47.2
0.07
0.03
L: apple
16.3
0.02
0.01
M: loquat
13
0.02
0.01
N: sweet corn
24.8
0.04
0.02
O: grapes
22.4
0.03
0.01
P: strawberries
100.2
0.15
0.07
Q: tomatoes
24.5
0.04
0.02
R: Peanuts
12.9
0.02
0.01
S: Broccoli
73
0.11
0.05
T: Brussels sprouts
166.8
0.25
0.11
U: Sweet potato
49.7
0.08
0.03
V: Field corn
9.1
0.01
0.01
W: Lettuce, head
93.5
0.14
0.06
X: Sorghum
11.4
0.02
0.01
Y: Celery
37.9
0.06
0.03
Z: Horseradish
71.8
0.11
0.05
AA: Potato
42
0.06
0.03
AB: Radish
13.3
0.02
0.01
AC: Rice
2579
3.914
1.724
AD: Beans
9.7
0.01
0.01
AE: Okra
5.6
0.01
<0.01
AF: Sugar beet
13.6
0.02
0.01
AG: Alfalfa
9.1
0.01
0.01
AH: Pasture
10.9
0.02
0.01
AI: Grass for seed
7.1
0.01
<0.01
A J: Rangeland
12.8
0.02
0.01
AK: Melon
7.2
0.01
<0.01
AL: Roses
14.9
0.02
0.01
AM: Rights-of-way
19
0.03
0.01
AN: Wasteland
68
0.10
0.05
AO: Non-urban forests
11.5
0.02
0.01
AP: Rural shelter belts
41
0.06
0.03
AQ: Ticks
17.7
0.03
0.01
For specific uses associated with each crop group see Table 5.
2 Based on EC50 = 0.66 mg/L for green algae
3 Based on EC50 =1.5 mg/L for duckweed
4 exceeds risk level of concern (RQ>1.0)
Page 110 of 160
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5.1.2. Exposures in the Terrestrial Habitat
5.1.2.1. Direct Effects to CRLF
As described above, to assess risks of carbaryl to terrestrial-phase CRLF, dietary-based and
dose-based exposures modeled in T-REX for a small bird (20g) consuming small invertebrates
are used. Acute, subacute and chronic effects are estimated using the lowest available toxicity
data for birds. EECs are divided by toxicity values to estimate acute and chronic dietary-based
RQs as well as dose-based RQs. The only acute and subacute avian studies that were deemed
acceptable for quantitative use indicated that that median lethal dose and median lethal
concentration exceeded the maximum level tested; therefore, all of the resulting acute dietary-
based and dose-based RQ values are less than the calculated value. Dose-based RQ values
exceed the acute risk to endangered species LOC (RQ>0.1) by factors ranging between 8 to
158X. Whether definitive median lethal doses would actually be high enough to remain below
the acute risk LOC is uncertain. Chronic RQ values exceed the chronic risk LOC for home
lawns, flower beds around buildings, parks, citrus, olives, almonds, flowers, peaches, asparagus,
apples sweet corn, tomatoes, and lettuce (Table 32).
Page 111 of 160
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Table 32. Acute and chronic, dietary-based RQs and dose-based RQs for direct effects to the terrestrial-phase
Crop (iniui)1
Auik-
Dose-
liiisid RQ"
l)k-l;ir\ -
liusi'd, iii'llli'
RQ!
I'lirunk RQ"
A: Home lawn
<9.044
<0.294
4.786
B: Flower beds around buildings
<15.84
<0.504
8.396
C: Lawns
<9.044
<0.294
4.786
D: Ornamentals
<9.044
<0.294
4.786
E: Parks
<4.324
<0.144
2.296
F: Citrus
<13.60
<0.434
7.206
G: Olives
<6.844
<0.224
3.626
H: Almonds
<3.024
<0.184
5.716
I: Flowers
<4.914
<0.164
2.606
J: Peaches
<3.624
<0.114
1.926
K: Asparagus
<3.54
<0.114
1.876
L: Apple
<2.15*
<0.09
1.466
M: Loquat
<2.754
<0.09
1.466
N: Sweet corn
<3.924
<0.124
2.076
O: Grapes
<2.334
<0.07
1.236
P: Strawberries
<2.334
<0.07
1.236
Q: Tomatoes
<8.04
<0.07
1.236
R: Peanuts
<8.04
<0.07
1.236
S: Broccoli
<2.494
<0.08
1.326
T: Brussels sprouts
<2.494
<0.08
1.326
U: Sweet potato
<8.04
<0.07
1.236
V: Field corn
<1.834
<0.06
0.976
W: Lettuce, head
<2.284
<0.07
1.21s
X: Sorghum
<2.284
<0.07
1.216
Y: Celery
<2.284
<0.07
1.216
Z: Horseradish
<2.284
<0.07
1.216
AA: Potato
<2.284
<0.07
1.216
AB: Radish
<2.284
<0.07
1.216
AC: Rice
<1.624
<0.05
0.86
AD: Beans
<1.744
<0.06
0.92
AE: Okra
<1.874
<0.06
0.99
AF: Sugar beet
<1.374
<0.04
0.72
AG: Alfalfa
<1.284
<0.04
0.68
AH: Pasture
<1.374
<0.04
0.72
AI: Grass for seed
<1.374
<0.04
0.72
A J: Rangeland
<0.854
<0.03
0.45
AK: Melon
<1.164
<0.04
0.62
AL: Roses
<1.164
<0.04
0.62
AM: Rights-of-way
<0.914
<0.03
0.48
AN: Wasteland
<0.914
<0.03
0.48
AO: Non-urban forests
<1.084
<0.03
0.57
AP: Rural shelter belts
<1.084
<0.03
0.57
AO: Ticks
<1.984
<0.06
1.056
2Based on LD50 >2000 ppm (for mallard duck)
3 Based on LC50 >5000 ppm (for mallard duck)
^Potentially exceeds acute listed species LOC (RQ>0.1)
5Based on NOAEC = 300 ppm (for mallard duck)
6Exceeds chronic listed species LOC (RQ>1.0)
Page 112 of 160
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5.1.2.2. Indirect Effects to CRLF through effects to prey
In order to assess the risks of foliar applications of carbaryl to terrestrial invertebrates, which are
considered prey of CRLF in terrestrial habitats, the honey bee is used as a surrogate for terrestrial
invertebrates. EECs (|ig a.i./g of bee) calculated by T-REX for small and large insects are
divided by the calculated toxicity value for terrestrial invertebrates, which is 8.6 |ig a.i./g of bee.
The resulting RQ values for large insect and small insect exposures bound the potential range of
exposures for terrestrial insects to carbaryl. For all uses, RQ values exceed the acute risk LOC
(RQ>0.05) for both large and small terrestrial insects (Table 33).
As described above, to assess risks of carbaryl to prey (small mammals) of larger terrestrial-
phase CRLF, dietary-based and dose-based exposures modeled in T-REX for a small mammal
(15g) consuming small invertebrates are used. Subacute and chronic effects are estimated using
the most sensitive mammalian toxicity data. EECs are divided by the toxicity value to estimate
acute and chronic dietary-based RQs as well as acute dose-based RQs. Across all uses, acute
dose-based RQ values exceed the listed species acute risk LOC; except for use on melons, rights-
of-way/wasteland, non-urban forests and rural shelter belts, rangeland and for uses to control
ticks, RQ values exceed the acute risk to non-listed species LOC as well for mammals
considered as potential prey items for the CRLF. Dietary-based chronic RQ values exceed the
chronic risk LOC for mammals considered as potential prey species for CRLF (Table 34).
An additional prey item of the adult CRLF is other species of frogs. In order to assess risks to
these organisms, dietary-based and dose-based exposures modeled in T-REX for a small bird
(20g) consuming small invertebrates are used. These are the same EECs, toxicity values and RQs
used to assess direct effects to the CRLF. Acute, dietary-based RQ values, dietary-based chronic
RQ values and dose-based RQ values exceed the LOC for listed species for all uses (Table 32).
Page 113 of 160
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Table 33. RQs for determining indirect effects to the terrestrial-phase CRLF through effects to potential prey
Crop group1
Small invertebrate RQ2'J
Large Invertebrate RQ2'J
A: Home lawn
181
20
B: Flower beds around buildings
293
33
C: Lawns
167
18
D: Ornamentals
167
18
E: Parks
80
9
F: Citrus
251
28
G: Olives
126
14
H: Almonds
105
12
I: Flowers
91
10
J: Peaches
67
7
K: Asparagus
65
7
L: Apple
51
6
M: Loquat
51
6
N: Sweet corn
72
8
O: Grapes
43
5
P: Strawberries
43
5
Q: Tomatoes
43
5
R: Peanuts
43
5
S: Broccoli
46
5
T: Brussels sprouts
46
5
U: Sweet potato
43
5
V: Field corn
34
4
W: Lettuce, head
42
5
X: Sorghum
42
5
Y: Celery
42
5
Z: Horseradish
42
5
AA: Potato
42
5
AB: Radish
42
5
AC: Rice
30
3
AD: Beans
32
4
AE: Okra
35
4
AF: Sugar beet
25
3
AG: Alfalfa
24
3
AH: Pasture
25
3
AI: Grass for seed
25
3
A J: Rangeland
16
2
AK: Melon
22
2
AL: Roses
22
2
AM: Rights-of-way
17
2
AN: Wasteland
17
2
AO: Non-urban forests
20
2
AP: Rural shelter belts
20
2
AQ: Ticks
37
4
'For specific uses associated with each crop group see Table 5.
2Based on LD50 = 8.6 |xg a.i./bee
3Exceeds LOC of 0.05.
Page 114 of 160
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Table 34. Acute and chronic, acute dose-based RQs and chronic dietary-based RQs for prey items (small
Crop Group1
Acute Dose-Based RQ2
Chronic Dietary-based RQ""'
A: Home lawn
3.683
34.024
B: Flower beds around buildings
6.453
55.94
C: Lawns
3.68
34.024
D: Ornamentals
3.68
34.024
E: Parks
1.763
16.264
F: Citrus
5.533
61.24
G: Olives
2.783
24.14
H: Almonds
2..323
20.24
I: Flowers
2.003
17.34
J: Peaches
1.473
13.624
K: Asparagus
1.443
13.334
L: Apple
1.123
9.714
M: Loquat
1.123
9.714
N: Sweet corn
1.593
13.84
O: Grapes
4.143
2.194
P: Strawberries
4.143
2.194
0: Tomatoes
0.943
8.184
R: Peanuts
0.943
8.184
S: Broccoli
1.013
8.804
T: Brussels sprouts
1.013
8.804
U: Sweet potato
0.943
8.184
V: Field corn
0.753
6.474
W: Lettuce, head
0.933
8.064
X: Sorghum
0.933
8.064
Y: Celery
0.933
8.064
Z: Horseradish
0.933
8.064
AA: Potato
0.933
8.064
AB: Radish
0.933
8.064
AC: Rice
0.663
5.724
AD: Beans
0.713
6.54
AE: Okra
0.763
6.604
AF: Sugar beet
0.563
4.834
AG: Alfalfa
0.523
4.504
AH: Pasture
0.563
4.834
AI: Grass for seed
0.563
4.834
A J: Rangeland
0.353
3.004
AK: Melon
0.473
4.114
AL: Roses
0.473
4.114
AM: Rights-of-way
0.373
3.224
AN: Wasteland
0.373
3.224
AO: Non-urban forests
0.443
4.064
AP: Rural shelter belts
0.443
4.064
AQ: Ticks
0.813
7.454
*For specific uses associated with each crop group see Table 5.
2 Based on LD50 = 301 ppm (for laboratory rat)
3exceeds acute listed species LOC (RQ>0.1)
4Exceeds chronic listed species LOC (RQ>1.0)
5Based on NOAEC = 75 ppm (for laboratory rat)
Page 115 of 160
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5.1.2.3. Indirect Effects to CRLF through effects to habitat (plants)
Insufficient data are available to characterize the toxicity of carbaryl to riparian and terrestrial
plants. A tier 1 vegetative vigor study is available for 6 species of terrestrial plants exposed to
carbaryl at levels below the maximum single application rate allowed for carbaryl. Since carbaryl
is used for fruit thinning, carbaryl has potential for reproductive effects to plants. No data are
available to assess potential reproductive effects of carbaryl on plants. Therefore, RQs could not
be quantified for describing risks of uses of carbaryl to riparian and terrestrial vegetation.
5.2. Risk Description
The risk description synthesizes an overall conclusion regarding the likelihood of impacts
leading to an effects determination (i.e., "no effect," "may affect, but not likely to adversely
affect," or "likely to adversely affect") for the CRLF.
If the RQs presented in the Risk Estimation (Section 5.1) show no indirect effects and LOCs for
the CRLF are not exceeded for direct effects, a "no effect" determination is made, based on use
of carbaryl within the action area. If, however, indirect effects are anticipated and/or exposure
exceeds the LOCs for direct effects, the Agency concludes a preliminary "may affect"
determination for the CRLF. Following a "may affect" determination, additional information is
considered to refine the potential for exposure at the predicted levels based on the life history
characteristics (i.e., habitat range, feeding preferences, etc.) of the CRLF and potential
community-level effects to aquatic plants. Based on the best available information, the Agency
uses the refined evaluation to distinguish those actions that "may affect, but are not likely to
adversely affect" from those actions that are "likely to adversely affect" the CRLF.
The criteria used to make determinations that the effects of an action are "not likely to adversely
affect" the CRLF include the following:
• Significance of Effect: Insignificant effects are those that cannot be meaningfully
measured, detected, or evaluated in the context 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:
o Harm includes significant habitat modification or degradation that results in death
or injury to listed species by significantly impairing behavioral patterns such as
breeding, feeding, or sheltering.
o Harass is defined as actions that create the likelihood of injury to listed species to
such an extent as to significantly disrupt normal behavior patterns which include,
but are not limited to, breeding, feeding, or sheltering.
• Likelihood of the Effect Occurring: Discountable effects are those that are extremely
unlikely to occur. For example, use of dose-response information to estimate the
likelihood of effects can inform the evaluation of some discountable effects.
Page 116 of 160
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• Adverse Nature of Effect: Effects that are wholly beneficial without any adverse effects
are not considered adverse.
A description of the risk and effects determination for each of the established assessment
endpoints for the CRLF is provided below.
5.2.1. Direct Effects
5.2.1.1. Aquatic-phase
Acute exposures
All modeled uses except applications to flowers around buildings, ornamentals, parks, peaches,
asparagus, dry beans, okra, alfalfa, grass for seed and melons exceed the acute risk to listed
species LOC by factors ranging 1 to 240X for direct effects to aquatic-phase CRLF. A "no
effect" determination is made for the uses that do not exceed the acute LOC. A "may affect"
determination is made based on potential acute mortality of aquatic-phase amphibians for all
carbaryl uses that exceed the LOC (See Table 28).
A source of uncertainty in the derivation of RQs is the estimation of exposure. As discussed
above (section 3.1.1.4) concentrations of carbaryl have been detected in California surface
waters; however, the detections (<1.06 |ig/L) were not at levels sufficient to exceed the LOC for
direct acute effects to the CRLF. Since the NAWQA monitoring data are not targeted to actual
carbaryl application times and/or sites, it is uncertain whether concentration in surface waters is
sufficient to exceed either acute or chronic risk LOCs for the CRLF.
An analysis of the likelihood of individual direct mortality (Appendix K) indicates that based on
the highest RQ value (12) for direct effects on the aquatic-phase CRLF and with a dose-response
slope of 4.62, the likelihood is 1 in 1. At the endangered species LOC, i.e., RQ=0.05, the
likelihood of individual mortality is 1 in 1.1 x 109' however, at an RQ of 0.3, the likelihood of
individual mortality increases to 1 in 127. Although many of the current uses are estimated to
exceed the acute risk to listed species LOC for aquatic-phase CRLF, the likelihood of individual
mortality may be is significantly lower for some of the uses.
Page 117 of 160
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Table 35. Likelihood of individual effect for each use of carbaryl for the aquatic-phase CRLF,
Crop Group1
Acute RQ
Likelihood of individual acute
effect (1 in....)
A: Home lawn
0.07
2.10E+07
B: Flowers around buildings
0.002
1.82E+35
C: Lawns
0.12
95300
D: Ornamentals
0.23
62.7
E: Parks 1
0.04
1.89E+10
E Parks 2
0.05
1.08E+09
F: Citrus 1
0.15
14200
F: Citrus 2
0.20
1610
G Olives
0.24
477
H: almonds
0.20
1610
I: flowers
0.10
5.21E+05
J: peaches
0.26
370
K: asparagus
0.21
1510
L: apple
0.07
2.10E+07
M: loquat
0.06
1.21E+08
N: sweet corn
0.11
2.11E+05
O: grapes
0.10
5.21E+05
P: strawberries
0.46
16.8
Q: tomatoes
0.11
2.11E+05
R: Peanuts
0.06
1.21E+08
S: Broccoli
0.33
76.6
T: Brussels sprouts
0.76
3.44
U: Sweet potato
0.23
627
V: Field corn
0.04
1.89E+10
W: Lettuce, head
0.43
22.1
X: Sorghum
0.05
1.08E+09
Y: Celery
0.17
5300
Z: Horseradish
0.33
76.6
AA: Potato
0.19
2320
AB: Radish
0.06
1.21E+08
AC: Rice
11.72
1
AD: Beans
0.04
1.89E+10
AE: Okra
0.03
1.01E+12
AF: Sugar beet
0.06
1.21E+08
AG: Alfalfa
0.04
1.89E+10
AH: Pasture
0.05
1.08E+09
AI: Grass for seed
0.03
1.01E+12
A J: Rang eland
0.06
1.21E+08
AK: Melon
0.03
1.01E+12
AL: Roses
0.07
2.10E+07
AM: Rights-of-way
0.13
47100
AN: Wasteland
0.31
107
AO: Non-urban forests
0.05
1.08E+09
AP: Rural shelter belts
0.19
2320
AQ: Ticks
0.08
4.97E+06
*For specific uses associated with each crop group see Table 5.
Consistent with the process identified in the Overview Document (USEPA 2004) evaluated by
the U.S. Fish and Wildlife Service and the National Marine Fisheries Service (Williams and
Hogarth 2004), the potential for carbaryl to result in direct acute mortality of aquatic-phase
CRLF is based on toxicity data for the most sensitive fish. However, if risk estimates were based
on available acute amphibian toxicity data for carbaryl (see section 4.1.2), only the RQ value for
Page 118 of 160
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rice would exceed the acute risk LOC. The determination would be that current uses of carbaryl,
with the exception of rice, have "no effect" on the aquatic-phase CRLF. Similarly, had the
assessment for indirect effects to CRLF based on effects to its forage base of other frogs been
based on amphibian toxicity data, a no effect determination would have been reached.
In order to characterize the conservativeness of the endpoint selected to represent direct effects to
aquatic-phase CRLF (e.g. Atlantic salmon LC50 = 220 |ig/L) a genus sensitivity distribution is
derived using the available acute toxicity data for freshwater fish. This distribution is described
in the effects characterization of this assessment. The lower 95th percentile of the fish
distribution (472 |ig/L) indicates that the use of the lowest available toxicity value (220 |ig/L) is
likely a conservative estimate of the toxicity of carbaryl to freshwater vertebrates. When
considering estimated aquatic exposure concentrations, use on carbaryl on rice is sufficient to
exceed the LOC for 100% of the fish sensitivity distribution. Estimated aquatic concentrations
resulting from uses on Brussels sprouts, strawberries, lettuce, broccoli, horseradish, wasteland
and peaches are at levels sufficient to exceed the LOC for 20-55% of fish species. Uses of
carbaryl on olives, ornamentals, sweet potatoes, asparagus, citrus, almonds, potato, rural shelter
belts, celery and lawns are sufficient to exceed the LOC for 5-20% of fish species. Estimates of
carbaryl concentrations in surface waters resulting from all other uses are sufficient to exceed the
LOC for <5% of fish species.
Based on the above information, the determination for acute direct effects to the aquatic-phase
CRLF is "LAA" for carbaryl uses on rice, Brussels sprouts, strawberries, lettuce, broccoli,
horseradish, wasteland, peaches, olives, ornamentals, sweet potatoes, asparagus, citrus, almonds,
potato, rural shelter belts, celery and lawns. The determinations for the remaining uses originally
designated as "may affect" are "NLAA."
Chronic exposures
All of the uses modeled except for home lawns, flowers around buildings, parks, flowers,
eggplant, peanuts, corn, sorghum, radish, dry beans, okra, sugar beets, alfalfa, pasture, grass for
seed, rangeland, melons, roses and non-urban forests exceed the chronic risk LOC for direct
effects to the aquatic-phase CRLF. A "No Effect" determination is made for the uses that do not
exceed the chronic LOC. For the remaining uses, the chronic risk LOC is exceeded by factors
ranging 1 - 379X (See Table 28). A "may affect" determination is made based on potential
chronic reproductive effects on aquatic-phase amphibians.
RQs for chronic exposures are based on the level where no effects were observed (the NOAEC)
in laboratory exposure tests. As discussed in section 4.1.1.2, chronic toxicity data are unavailable
for the most sensitive species (Atlantic salmon) used to assess acute risk. Therefore, an acute-to-
chronic ratio was used to estimate the NOAEC for carbaryl exposures to Atlantic salmon. This
same approach can be applied to approximate the lowest concentration where effects (LOAEC)
would be expected to be observed. Based on the information contained in the carbaryl IRED
(USEPA 2004b), the 96-hr acute LC50value for fathead minnows is 7.7 mg/L. With an acute
LC50 of 7.7 mg/L and a chronic LOAEC of 0.68, the acute to chronic ratio (ACR) for fathead
minnow is 11.3 (7.7-KX68). When the ACR is applied to the Atlantic salmon data, the resulting
estimated LOAEC is 0.0195 mg/L.
Page 119 of 160
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Direct comparison of 60-d EECs to this estimated LOAEC for the Atlantic salmon indicates that
EECs are sufficient to exceed this LOAEC for carbaryl uses on strawberries, broccoli, Brussels
sprouts, sweet potatoes, heat lettuce, horse radish, rice and wasteland. For these uses, the
determination is "LAA" for chronic effects to the CRLF in aquatic habitats.
For several uses the LOC is exceeded by RQs derived using the NOAEC but the EECs are
insufficient to exceed the ACR-derived LOAEC. These uses include: lawns, ornamentals, citrus,
olives, almonds, peaches, asparagus, apple, loquat, sweet corn, grapes, tomatoes, celery, potato,
rights-of-way, rural shelter belts and ticks. In this assessment, the NOAEC is used to derive RQs
representing risks of chronic exposures of the CRLF to carbaryl. There are two significant
uncertainties that prevent making a determination of "NLAA" for these uses. First, it is assumed
that the actual exposure concentration where effects are exhibited lies somewhere between the
NOAEC and the LOAEC. Given the uncertainty associated with the actual level where effects
occur, risks of chronic exposures of the CRLF to carbaryl cannot be discounted. Second, it has
been acknowledged in this assessment that 1-naphthol, which is a major degradate of
toxicological concern, is not included in the estimation of exposures. In an early life cycle study
involving fathead minnows exposed to 1-naphthol, the NOAEC was 0.102 mg/L, with the
LOAEC defined as 0.203 mg/L based on effects to larval survival and growth (MRID 457848-
04). This LOAEC is similar to the NOAEC (0.21 mg/L; MRID 406448-01) reported in a long
term study with fathead minnows exposed to carbaryl. There is uncertainty associated with the
extent of the exposure of the CRLF to 1-naphthol in the aquatic environment. Therefore, there is
uncertainty associated with the increased risk that could be attributed to these exposures. Based
on the LOC exceedances and the two uncertainties described above, the determination is "LAA"
for chronic effects to the CRLF in aquatic habitat resulting from carbaryl use on lawns,
ornamentals, citrus, olives, almonds, peaches, asparagus, apple, loquat, sweet corn, grapes,
tomatoes, celery, potato, rights-of-way, rural shelter belts and ticks.
5.2.1.2. Terrestrial-phase
Acute-dose based, indiscreet RQs potentially exceed the LOC, resulting in a "may affect"
determination for all uses. Acute, dietary-based RQs, which are also indiscreet, also potentially
exceed the LOC for several uses. Chronic, dietary based RQs, which are discreet, exceed the
LOC for the majority of carbaryl uses. In order to explore influences of amphibian specific food
intake equations on potential dose-based and dietary-based exposures of the terrestrial phase
CRLF to carbaryl, T-HERPS was used. Modeling with T-HERPS incorporates the same
application rates, intervals and number of applications for each use as defined for modeling using
T-REX (Table 16). Since applications of carbaryl for many uses result in exposures sufficient to
exceed the LOC for direct effects to the CRLF, this model was used to estimate EECs and
subsequent risks to the CRLF based on amphibian specific equations. These refined EECs and
RQs were used to distinguish "NLAA" and "LAA" determinations.
RQs are calculated for the terrestrial-phase CRLF on the basis of dose and diet. It should be
noted that although dietary-based RQ values are considerably lower than dose-based RQ values,
the former do not take into account that different-sized animals consume differing amounts of
food and that depending on the forage item, an animal has to consume varying amounts due to
Page 120 of 160
-------
differing nutrition levels in the food item. If dietary-based RQ values are adjusted to account for
differential food consumption, the adjusted RQ value would likely approximate the dose-based
RQ value.
Acute exposures
Refined dose based RQs for small sized (1.4 g) CRLF do not exceed the acute listed species
LOC for any use (Table 36), resulting in a no effect determination. Refined dose based RQs for
medium (37 g) and large (238 g) sized CRLF feeding on small and large insects, small
insectivore mammals and small terrestrial-phase amphibians do not exceed the acute listed
species LOC for any use, resulting in a no effect determination (Tables 37 and 38).
Refined dose-based RQs indicate that, for some carbaryl uses, there is potential for direct
mortality to medium (37 g) and large (238 g) sized CRLF feeding on small herbivore mammals
(Tables 37 and 38). Carbaryl is classified as practically nontoxic to birds on an acute oral
exposure basis with the acute oral LD50 (>2000 mg/kg bw) exceeding the maximum
concentration tested. All of the estimated RQ values are less than the calculated value, resulting
in uncertainty in whether or not the values should exceed the listed species LOC. Direct
comparison of the limit dose of the available avian acute oral test (2000 mg/kg-bw) to dose-
based EECs indicates that EECs are insufficient to reach this level (i.e. acute dose-based RQs are
less than 1). Therefore, EECs are insufficient to reach levels where less than 50% mortality was
observed in laboratory tests. The only exceptions to this are for medium sized CRLF consuming
small herbivore mammals in fields where carbaryl was applied to citrus and flowers and beds
around buildings. Overall, based on dose-based exposure estimates, the risk of acute mortality of
carbaryl to terrestrial-phase CRLF is low.
Refined dietary-based RQs indicate that, for some carbaryl uses, there is potential for direct
mortality to CRLF feeding on small insects or small herbivore mammals. RQs do not exceed the
acute LOC for CRLF feeding on large insects, small insectivore mammals and small terrestrial
phase amphibians (Table 39). Carbaryl is classified as practically nontoxic to birds on a subacute
dietary exposure basis with the subacute dietary LC50 (>5000 mg/kg diet) exceeding the
maximum concentration tested. All of the estimated RQ values are less than the calculated
value, resulting in uncertainty in whether or not the values should exceed the listed species LOC.
Direct comparison of the limit dose of the available avian acute oral test (5000 mg/kg-diet) to
acute dietary-based EECs indicates that EECs are insufficient to reach this level (i.e. acute
dietary-based RQs are less than 1). Therefore, EECs are insufficient to reach levels where less
than 50% mortality was observed in laboratory tests. Overall, based on dietary-based exposure
estimates, the risk of acute mortality of carbaryl to terrestrial-phase CRLF is low.
Based on the refined estimates of exposures to terrestrial-phase CRLF, the effects determinations
for acute effects resulting from all uses of carbaryl is "NLAA."
Page 121 of 160
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Table 36. Revised dose-based RQs for 1.4 g CRLF consuming different food items. EECs calculated using T-
HERPS.
( lop Croup1
Small
Insecls
Large Insecls
A: Home lawn
<0.03
<0.01
B: Flower beds around buildings
<0.05
<0.01
C: Lawns
<0.03
<0.01
D: Ornamentals
<0.03
<0.01
E: Parks
<0.01
<0.01
F: Citrus
<0.04
<0.01
G: Olives
<0.02
<0.01
H: Almonds
<0.02
<0.01
I: Flowers
<0.02
<0.01
J: Peaches
<0.01
<0.01
K: Asparagus
<0.01
<0.01
L: Apple
<0.01
<0.01
M: Loquat
<0.01
<0.01
N: Sweet corn
<0.01
<0.01
O: Grapes
<0.01
<0.01
P: Strawberries
<0.01
<0.01
Q: Tomatoes
<0.01
<0.01
R: Peanuts
<0.01
<0.01
S: Broccoli
<0.01
<0.01
T: Brussels sprouts
<0.01
<0.01
U: Sweet potato
<0.01
<0.01
V: Field corn
<0.01
<0.01
W: Lettuce, head
<0.01
<0.01
X: Sorghum
<0.01
<0.01
Y: Celery
<0.01
<0.01
Z: Horseradish
<0.01
<0.01
AA: Potato
<0.01
<0.01
AB: Radish
<0.01
<0.01
AC: Rice
<0.01
<0.01
AD: Beans
<0.01
<0.01
AE: Okra
<0.01
<0.01
AF: Sugar beet
<0.01
<0.01
AG: Alfalfa
<0.01
<0.01
AH: Pasture
<0.01
<0.01
AI: Grass for seed
<0.01
<0.01
AJ: Rangeland
<0.01
<0.01
AK: Melon
<0.01
<0.01
AL: Roses
<0.01
<0.01
AM: Rights-of-way
<0.01
<0.01
AN: Wasteland
<0.01
<0.01
AO: Non-urban forests
<0.01
<0.01
AP: Rural shelter belts
<0.01
<0.01
AQ: Ticks
<0.01
<0.01
'For specific uses associated with each crop group see Table 5.
Page 122 of 160
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Table 37. Revised dose-based RQs for 37 g CRLF consuming different food items. EECs calculated using T-
HERPS.
( lop Croup
Small
Insecls
large
Insecls
Small
herlmnre
mammals2
Small
insccli\orc
mammals
Small (erreslrial-
pliasc amphibian
A: Home lawn
<0.03
<0.01
<0.86
<0.06
<0.01
B: Flower beds around buildings
<0.05
<0.01
<1.39
<0.09
<0.01
C: Lawns
<0.03
<0.01
<0.80
<0.05
<0.01
D: Ornamentals
<0.03
<0.01
<0.80
<0.05
<0.01
E: Parks
<0.01
<0.01
<0.38
<0.02
<0.01
F: Citrus
<0.04
<0.01
<1.20
<0.07
<0.01
G: Olives
<0.02
<0.01
<0.60
<0.04
<0.01
H: Almonds
<0.02
<0.01
<0.50
<0.03
<0.01
I: Flowers
<0.01
<0.01
<0.43
<0.03
<0.01
J: Peaches
<0.01
<0.01
<0.32
<0.02
<0.01
K: Asparagus
<0.01
<0.01
<0.31
<0.02
<0.01
L: Apple
<0.01
<0.01
<0.24
<0.02
<0.01
M: Loquat
<0.01
<0.01
<0.24
<0.02
<0.01
N: Sweet corn
<0.01
<0.01
<0.34
<0.02
<0.01
O: Grapes
<0.01
<0.01
<0.20
<0.01
<0.01
P: Strawberries
<0.01
<0.01
<0.20
<0.01
<0.01
Q: Tomatoes
<0.01
<0.01
<0.20
<0.01
<0.01
R: Peanuts
<0.01
<0.01
<0.20
<0.01
<0.01
S: Broccoli
<0.01
<0.01
<0.22
<0.01
<0.01
T: Brussels sprouts
<0.01
<0.01
<0.22
<0.01
<0.01
U: Sweet potato
<0.01
<0.01
<0.20
<0.01
<0.01
V: Field corn
<0.01
<0.01
<0.16
<0.01
<0.01
W: Lettuce, head
<0.01
<0.01
<0.20
<0.01
<0.01
X: Sorghum
<0.01
<0.01
<0.20
<0.01
<0.01
Y: Celery
<0.01
<0.01
<0.20
<0.01
<0.01
Z: Horseradish
<0.01
<0.01
<0.20
<0.01
<0.01
AA: Potato
<0.01
<0.01
<0.20
<0.01
<0.01
AB: Radish
<0.01
<0.01
<0.20
<0.01
<0.01
AC: Rice
<0.01
<0.01
<0.14
<0.01
<0.01
AD: Beans
<0.01
<0.01
<0.15
<0.01
<0.01
AE: Okra
<0.01
<0.01
<0.16
<0.01
<0.01
AF: Sugar beet
<0.01
<0.01
<0.12
<0.01
<0.01
AG: Alfalfa
<0.01
<0.01
<0.11
<0.01
<0.01
AH: Pasture
<0.01
<0.01
<0.12
<0.01
<0.01
AI: Grass for seed
<0.01
<0.01
<0.12
<0.01
<0.01
AJ: Rangeland
<0.01
<0.01
<0.07
<0.01
<0.01
AK: Melon
<0.01
<0.01
<0.10
<0.01
<0.01
AL: Roses
<0.01
<0.01
<0.10
<0.01
<0.01
AM: Rights-of-way
<0.01
<0.01
<0.08
<0.01
<0.01
AN: Wasteland
<0.01
<0.01
<0.08
<0.01
<0.01
AO: Non-urban forests
<0.01
<0.01
<0.10
<0.01
<0.01
AP: Rural shelter belts
<0.01
<0.01
<0.10
<0.01
<0.01
AQ: Ticks
<0.01
<0.01
<0.17
<0.01
<0.01
'For specific uses associated with each crop group see Table 5.
2bold values potentially exceed the acute listed species LOC (0.10)
Page 123 of 160
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Table 38. Revised dose-based RQs for 238 g CRLF consuming different food items. EECs calculated using T-
HERPS.
( im|> (.roup
^iiiull lii-iil-
1 ill'!!r
In-lTl-
^iii;ill lici'hi\oiv
iiiiiiiiniiiK-
^liisill iiiMTli\Hir
^niiill U-riT*>iriiil
plisiM' iiinpliihisiii
A: Home lawn
<0.02
<0.01
<0.13
<0.01
<0.01
B: Flower beds around buildings
<0.03
<0.01
<0.22
<0.01
<0.01
C: Lawns
<0.02
<0.01
<0.12
<0.01
<0.01
D: Ornamentals
<0.02
<0.01
<0.12
<0.01
<0.01
E: Parks
<0.01
<0.01
<0.06
<0.01
<0.01
F: Citrus
<0.03
<0.01
<0.19
<0.01
<0.01
G: Olives
<0.01
<0.01
<0.09
<0.01
<0.01
H: Almonds
<0.01
<0.01
<0.08
<0.01
<0.01
I: Flowers
<0.01
<0.01
<0.07
<0.01
<0.01
J: Peaches
<0.01
<0.01
<0.05
<0.01
<0.01
K: Asparagus
<0.01
<0.01
<0.05
<0.01
<0.01
L: Apple
<0.01
<0.01
<0.04
<0.01
<0.01
M: Loquat
<0.01
<0.01
<0.04
<0.01
<0.01
N: Sweet corn
<0.01
<0.01
<0.05
<0.01
<0.01
O: Grapes
<0.01
<0.01
<0.03
<0.01
<0.01
P: Strawberries
<0.01
<0.01
<0.03
<0.01
<0.01
Q: Tomatoes
<0.01
<0.01
<0.03
<0.01
<0.01
R: Peanuts
<0.01
<0.01
<0.03
<0.01
<0.01
S: Broccoli
<0.01
<0.01
<0.03
<0.01
<0.01
T: Brussels sprouts
<0.01
<0.01
<0.03
<0.01
<0.01
U: Sweet potato
<0.01
<0.01
<0.03
<0.01
<0.01
V: Field corn
<0.01
<0.01
<0.03
<0.01
<0.01
W: Lettuce, head
<0.01
<0.01
<0.03
<0.01
<0.01
X: Sorghum
<0.01
<0.01
<0.03
<0.01
<0.01
Y: Celery
<0.01
<0.01
<0.03
<0.01
<0.01
Z: Horseradish
<0.01
<0.01
<0.03
<0.01
<0.01
AA: Potato
<0.01
<0.01
<0.03
<0.01
<0.01
AB: Radish
<0.01
<0.01
<0.03
<0.01
<0.01
AC: Rice
<0.01
<0.01
<0.02
<0.01
<0.01
AD: Beans
<0.01
<0.01
<0.02
<0.01
<0.01
AE: Okra
<0.01
<0.01
<0.03
<0.01
<0.01
AF: Sugar beet
<0.01
<0.01
<0.02
<0.01
<0.01
AG: Alfalfa
<0.01
<0.01
<0.02
<0.01
<0.01
AH: Pasture
<0.01
<0.01
<0.02
<0.01
<0.01
AI: Grass for seed
<0.01
<0.01
<0.02
<0.01
<0.01
AJ: Rangeland
<0.01
<0.01
<0.01
<0.01
<0.01
AK: Melon
<0.01
<0.01
<0.02
<0.01
<0.01
AL: Roses
<0.01
<0.01
<0.02
<0.01
<0.01
AM: Rights-of-way
<0.01
<0.01
<0.01
<0.01
<0.01
AN: Wasteland
<0.01
<0.01
<0.01
<0.01
<0.01
AO: Non-urban forests
<0.01
<0.01
<0.01
<0.01
<0.01
AP: Rural shelter belts
<0.01
<0.01
<0.01
<0.01
<0.01
AQ: Ticks
<0.01
<0.01
<0.03
<0.01
<0.01
'For specific uses associated with each crop group see Table 5.
2bold values potentially exceed the acute listed species LOC (0.10)
Page 124 of 160
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Table 39. Revised acute dietary-based RQs for CRLF consuming different dietary items. EECs calculated
using T-HERPS.
( | M|> < . I < >111> '
Mllllll IllTlls-
1 :ir«r lii-n is
Slllllll
lirrhixiHv
ill alum ;iK-
siniill
illoci'liMHV
¦¦¦:¦III¦¦¦:¦K
^iniill Iri n-li ijl
|iIi:it inn |>liil>i:iii
A: Home lawn
0.31
0.03
0.3"
0.02
0.01
B: Flower beds around buildings
<0.05
<0.06
<0.59
<0.04
<0.02
C: Lawns
<0.29
<0.03
<0.34
<0.02
<0.01
D: Ornamentals
<0.29
<0.03
<0.34
<0.02
<0.01
E: Parks
<0.14
<0.02
<0.16
<0.01
<0.01
F: Citrus
<0.43
<0.05
<0.51
<0.03
<0.01
G: Olives
<0.22
<0.02
<0.25
<0.02
<0.01
H: Almonds
<0.18
<0.02
<0.21
<0.01
<0.01
I: Flowers
<0.16
<0.02
<0.18
<0.01
<0.01
J: Peaches
<0.11
<0.01
<0.13
<0.01
<0.01
K: Asparagus
<0.11
<0.01
<0.13
<0.01
<0.01
L: Apple
<0.09
<0.01
<0.10
<0.01
<0.01
M: Loquat
<0.09
<0.01
<0.10
<0.01
<0.01
N: Sweet corn
<0.12
<0.01
<0.15
<0.01
<0.01
O: Grapes
<0.07
<0.01
<0.09
<0.01
<0.01
P: Strawberries
<0.07
<0.01
<0.09
<0.01
<0.01
Q: Tomatoes
<0.07
<0.01
<0.09
<0.01
<0.01
R: Peanuts
<0.07
<0.01
<0.09
<0.01
<0.01
S: Broccoli
<0.08
<0.01
<0.09
<0.01
<0.01
T: Brussels sprouts
<0.08
<0.01
<0.09
<0.01
<0.01
U: Sweet potato
<0.07
<0.01
<0.09
<0.01
<0.01
V: Field corn
<0.06
<0.01
<0.07
<0.01
<0.01
W: Lettuce, head
<0.07
<0.01
<0.08
<0.01
<0.01
X: Sorghum
<0.07
<0.01
<0.08
<0.01
<0.01
Y: Celery
<0.07
<0.01
<0.08
<0.01
<0.01
Z: Horseradish
<0.07
<0.01
<0.08
<0.01
<0.01
AA: Potato
<0.07
<0.01
<0.08
<0.01
<0.01
AB: Radish
<0.07
<0.01
<0.08
<0.01
<0.01
AC: Rice
<0.05
<0.01
<0.06
<0.01
<0.01
AD: Beans
<0.06
<0.01
<0.06
<0.01
<0.01
AE: Okra
<0.06
<0.01
<0.07
<0.01
<0.01
AF: Sugar beet
<0.04
<0.01
<0.05
<0.01
<0.01
AG: Alfalfa
<0.04
<0.01
<0.05
<0.01
<0.01
AH: Pasture
<0.04
<0.01
<0.05
<0.01
<0.01
AI: Grass for seed
<0.04
<0.01
<0.05
<0.01
<0.01
AJ: Rangeland
<0.03
<0.01
<0.03
<0.01
<0.01
AK: Melon
<0.04
<0.01
<0.04
<0.01
<0.01
AL: Roses
<0.04
<0.01
<0.04
<0.01
<0.01
AM: Rights-of-way
<0.03
<0.01
<0.03
<0.01
<0.01
AN: Wasteland
<0.03
<0.01
<0.03
<0.01
<0.01
AO: Non-urban forests
<0.03
<0.01
<0.04
<0.01
<0.01
AP: Rural shelter belts
<0.03
<0.01
<0.04
<0.01
<0.01
AQ: Ticks
<0.06
<0.01
<0.07
<0.01
<0.01
'For specific uses associated with each crop group see Table 5.
2bold values potentially exceed the acute listed species LOC (0.10)
Page 125 of 160
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Chronic exposures
Refined dietary-based RQs indicate that, for some carbaryl uses, there is potential for chronic
effects to CRLF feeding on small insects or small herbivore mammals. Chronic RQs for these
feeding groups are exceeded by factors ranging 1.05X to 9.82X. RQs do not exceed the acute
LOC for CRLF feeding on large insects, small insectivore mammals and small terrestrial phase
amphibians (Table 40). In the available chronic study where mallard ducks were exposed to
carbaryl, the NOAEC was 300 ppm, and the LOAEC was 600 ppm, based on decreased number
of eggs. Comparison of the LOAEC directly to chronic dietary-based EECs indicate that several
EECs are sufficient to exceed the concentration were reproductive effects were observed in the
laboratory. Some EECs are insufficient to exceed the LOAEC. As discussed above, it is assumed
that the actual exposure concentration where effects are exhibited lies somewhere between the
NOAEC and the LOAEC. Given the uncertainty associated with the actual level where effects
occur, risks of chronic exposures of the CRLF to carbaryl cannot be discounted. Therefore, for
all uses where the chronic RQ exceeds the LOC (Table x5), the effects determination for chronic
effects to the terrestrial phase CRLF is "LAA" based on potential reproductive effects. For all
uses where none of the chronic RQs for the CRLF exceed the LOC, the effects determination is
"NLAA" for chronic effects to the terrestrial-phase CRLF.
Page 126 of 160
-------
Table 40. Revised chronic dietary-based RQs for CRLF consuming different dietary items. EECs calculated
using T-HERPS.
( |M|> (.|M|||>
^iiiiill IiimtI-"
1 1 MM'tl
^iiiiill lici'liixMiv
milium ;iK-
^niiill iiiM'i'liMiiv
lll;lllllll;ll-
^niiill lilTi-lli;il
pliiiM' :iiii|iliiliiiin
A: Home lawn
5.20
0.58
6.09
0.38
0.18
B: Flower beds around
buildings
8.39
0.93
9.82
0.61
0.29
C: Lawns
4.78
0.53
5.60
0.35
0.17
D: Ornamentals
4.78
0.53
5.60
0.35
0.17
E: Parks
2.29
0.25
2.68
0.17
0.08
F: Citrus
7.20
0.80
8.43
0.53
0.25
G: Olives
3.62
0.40
4.24
0.27
0.13
H: Almonds
3.02
0.34
3.54
0.22
0.10
I: Flowers
2.60
0.29
3.04
0.19
0.09
J: Peaches
1.92
0.21
2.24
0.14
0.07
K: Asparagus
1.87
0.21
2.20
0.14
0.07
L: Apple
1.46
0.16
1.71
0.11
0.05
M: Loquat
1.46
0.16
1.71
0.11
0.05
N: Sweet corn
2.07
0.23
2.43
0.15
0.07
O: Grapes
1.23
0.14
1.44
0.09
0.04
P: Strawberries
1.23
0.14
1.44
0.09
0.04
Q: Tomatoes
1.23
0.14
1.44
0.09
0.04
R: Peanuts
1.23
0.14
1.44
0.09
0.04
S: Broccoli
1.32
0.15
1.55
0.10
0.05
T: Brussels sprouts
1.32
0.15
1.55
0.10
0.05
U: Sweet potato
1.23
0.14
1.44
0.09
0.04
V: Field corn
0.97
0.11
1.14
0.07
0.03
W: Lettuce, head
1.21
0.13
1.42
0.09
0.04
X: Sorghum
1.21
0.13
1.42
0.09
0.04
Y: Celery
1.21
0.13
1.42
0.09
0.04
Z: Horseradish
1.21
0.13
1.42
0.09
0.04
AA: Potato
1.21
0.13
1.42
0.09
0.04
AB: Radish
1.21
0.13
1.42
0.09
0.04
AC: Rice
0.86
0.10
1.00
0.06
0.03
AD: Beans
0.92
0.10
1.08
0.07
0.03
AE: Okra
0.99
0.11
1.16
0.07
0.03
AF: Sugar beet
0.72
0.08
0.85
0.05
0.03
AG: Alfalfa
0.68
0.08
0.79
0.05
0.02
AH: Pasture
0.72
0.08
0.85
0.05
0.03
AI: Grass for seed
0.72
0.08
0.85
0.05
0.03
AJ: Rangeland
0.45
0.05
0.53
0.03
0.02
AK: Melon
0.62
0.07
0.72
0.05
0.02
AL: Roses
0.62
0.07
0.72
0.05
0.02
AM: Rights-of-way
0.48
0.05
0.57
0.04
0.02
AN: Wasteland
0.48
0.05
0.57
0.04
0.02
AO: Non-urban forests
0.57
0.06
0.67
0.04
0.02
AP: Rural shelter belts
0.57
0.06
0.67
0.04
0.02
AQ: Ticks
1.05
0.12
1.23
0.08
0.04
'For specific uses associated with each crop group see Table 5.
2bold values potentially exceed the chronic listed species LOC (1.0)
Page 127 of 160
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5.2.1.3. Summary of determinations for direct effects of CRLF resulting from
Carbaryl exposures
When considering acute and chronic exposures to the CRLF in its aquatic and terrestrial habitats,
estimates of exposure are sufficient to be of concern for effects based on acute or chronic
exposures for the majority of carbaryl uses. The overall effects determination for the CRLF is
"LAA" for 36 of the 44 assessed use groups of carbaryl. For the remaining 8 use groups, the
effects determination is "NLAA" (Table 41)
Page 128 of 160
-------
Table 41. Carbaryl use-specific direct effects determinations1 for the CRLF (shading added to indicate use
where there is any LAA determination).
Crop Croup"
Aipialic-I'hase
CUM-
\ home l;i\\ n
13 llouci's hods around buildings
(' law us
I). oniauiciilals
I! nails
I' cuius
(l l'lIN OS
II almonds
I I'lou ci's
nc;idk>
K: asparagus
I. ;innk
M lounal
\ swccl CO I'll
() grancs
I' sir;iwhcrncs
O lonialocs
k IVanuls
S IJroccoli
T I jlllsscls snioills
I Swcci noialo
Y 1'icld com
W l.cllucc. hc;id
\ SiHuhiuu
^ CcIcia
/. I liirsci';idisli
\ \ l\>l;ili>
\Ii k;idisli
\( kicc
\l) I5c;iiis
\i: Oki.i
AF: Sugar beet
AG: Alfalfa
AH: Pasture
AI: Grass for seed
AJ: Rangeland
AK: Melon
AL: Roses
AM: Rights-of-way
AN: Wasteland
AO: Non-urban forests
AP: Rural shelter belts
AO: Ticks
Acule
\l. \ \
\i:
\ \
\ \
\i:
\ \
. \ \
\ \
\i. \ \
\ \
\ \
\i. \ \
\i. \ \
\i. \ \
\i. \ \
i. \ \
\i. \ \
\i. \ \
i. \ \
i. \ \
i. \ \
\i:
i. \ \
\i. \ \
i. \ \
i. \ \
i. \ \
\i. \ \
i. \ \
\i:
\i:
NLAA
NE
NE
NE
NLAA
NE
NLAA
NLAA
LAA
NLAA
LAA
NLAA
Chronic
\i:
\i:
\i
\i
\i
\i
\i
\i:
i. \ \
\i:
\i:
NE
NE
NE
NE
NE
NE
NE
LAA
LAA
NE
LAA
LAA
lei
resl rial-Phase
CUM-
Acule
\l.
\l.
\l.
\l.
\l
\l
\l
\l
\l
\l
\l.
\l
\l
\l
\l
\l
\l
\l
\l
\l
\l
\l
\l
\l
\l
\l
\l
\l
\l
\l
\l
NLAA
NLAA
NLAA
NLAA
NLAA
NLAA
NLAA
NLAA
NLAA
NLAA
NLAA
NLAA
Chronic
\l
I.
NLAA
NLAA
NLAA
NLAA
NLAA
NLAA
NLAA
NLAA
NLAA
NLAA
NLAA
LAA
1 LAA = likely to adversely affect; NLAA = not likely to adversely affect; NE = no effect
2For specific uses associated with each crop group see Table 5.
Page 129 of 160
-------
5.2.2. Indirect Effects (through effects to prey)
As discussed in section 2.5.3, the diet of tadpole CRLF is composed primarily of unicellular
aquatic plants and detritus. Juvenile CRLF consume primarily aquatic and terrestrial
invertebrates. The diet of adult CRLF is composed of aquatic and terrestrial invertebrates, fish,
frogs and mice. These prey groups are considered in determining indirect effects to the CRLF
caused by direct effects to its prey.
Unicellular plants
Based on RQs for algae (Table 29), applications of carbaryl are not expected to affect this food
source except for use on rice. Therefore, indirect effects of carbaryl to CRLF tadpoles by
reductions in phytoplankton are not expected based on the animal's diet during this life stage for
all of the use except rice. However, the use of carbaryl on rice "may affect" tadpoles through the
reduction in phytoplankton (RQ=2.0). Since EECs associated with use of carbaryl on rice exceed
the level where 50% reduction in algal cells were observed in the laboratory, the determination
for indirect effects to the CRLF due to effects to algae is "LAA."
Aquatic invertebrates
(RQ range: 0.3 - 1517) and chronic (RQ range: 0.6-5158) risk estimates for aquatic
invertebrates indicate that all uses of carbaryl can potentially result in effects to invertebrates
serving as prey to aquatic-phase CRLFs. Based on RQ exceedances of the acute or chronic LOC
for listed species, all carbaryl uses "may affect" the CRLF due to effects to aquatic invertebrates,
which compose its diet.
Based on an analysis of the likelihood of individual mortality using the highest RQ value for
aquatic invertebrates (carbaryl use on rice; RQ=1517) and a probit dose-response of 4.30, the
likelihood of individual mortality is 100%. At the lowest acute RQ value (i.e, RQ=0.3 for use on
flowers around building), the likelihood of individual mortality is 1 in 8.2.
When considering chronic exposures, EECs exceed the estimated NOAEC for stoneflies for all
uses except flowers around buildings.
In order to characterize the conservativeness of the endpoint selected to represent indirect effects
to the CRLF through direct effects to its aquatic prey (e.g. Stonefly EC50 =1.7 |ig/L) genus
sensitivity distributions are derived using the available acute toxicity data for freshwater fish and
invertebrates, respectively. These distributions are described in the effects characterization of
this assessment. The lower 95th percentile of the invertebrate distribution (0.69 |ig/L) indicates
that the use of the lowest available toxicity value (1.7 |ig/L) is not as conservative as the lower
95th percentile of the distribution. When considering the distribution, estimated aquatic
concentrations resulting from all uses except flowers around buildings are at levels sufficient to
exceed the LOC for >90% of invertebrate species. EECs for flowers around buildings exceeds
for approximately 50% of the distribution. When considering invertebrate sensitivity
distributions in the context of available monitoring data, the highest concentration of carbaryl
Page 130 of 160
-------
observed in California surface waters (1.06 |ig/L) is sufficient to exceed the invertebrate LOC for
approximately 65% of available geneses.
Based on acute and chronic RQ exceedances, likelihood of individual mortality analysis and
genus sensitivity distribution information for aquatic invertebrates, the determination for indirect
effects to the CRLF due to effects to aquatic invertebrates is "LAA" for all uses of carbaryl.
Terrestrial invertebrates
RQ values representing acute exposures to terrestrial invertebrates indicate that all uses of
carbaryl can potentially result in effects to invertebrates. Therefore, indirect effects are possible
to CRLF juveniles and adults, through decreases in prey. When considering the level where
carbaryl causes 50% mortality in honey bees, EECs are sufficient to exceed this level by factors
of 2x-293x (Table 33). Based on an analysis of the likelihood of individual mortality using the
lowest RQ value for terrestrial invertebrates (RQ=2) and a probit dose-response of 4.5 (default
value), the likelihood of individual mortality is 91%. All other RQ values result in an estimation
of approximately 100% likelihood of individual mortality in terrestrial invertebrates. Therefore,
the determination for indirect effects to the CRLF due to effects to terrestrial invertebrates is
"LAA" for all uses of carbaryl.
Fish and aquatic-phase amphibians
RQs representing direct exposures of carbaryl to aquatic-phase CRLF can also be used to
represent exposures of carbaryl to fish and frogs in aquatic habitats. Based on estimated
exposures resulting from use of carbaryl, acute (RQ range: 0.05 - 12) risk to fish and frogs
serving as prey to CRLF is possible across all of the uses evaluated except for use of carbaryl on
flowers around buildings, corn, dray beans, okra, alfalfa, grass for seed and melons. Based on an
analysis of the likelihood of individual acute mortality, RQ values of less than 0.4 represent less
than a 1 in 30 chance of prey mortality which is not considered significant. The low significance
of a 1/30 likelihood of acute mortality is based on the use of a conservative toxicity endpoint
(Atlantic salmon LC5o=220 (J,g/L) in estimating risks and the likelihood of alternative prey items
for the CRLF. Based on the species sensitivity distribution for fish, the lower 95th percentile of
the distribution is 472 (J,g/L. Thus it is likely that a number of less sensitive vertebrate prey items
would be available for consumption. Therefore, only carbaryl uses on ornamentals, strawberries,
Brussels sprouts, head lettuce and rice are determined to likely adversely affect the CRLF
through indirect effects on aquatic vertebrate prey items.
Chronic risks (RQ range: 1.1 - 379) to fish and frogs are possible for carbaryl uses on lawns,
ornamentals, citrus, olives, almonds, peaches, asparagus, apples, loquat, sweet corn, grapes,
strawberries, tomatoes, broccoli, Brussels sprouts, sweet potatoes, head lettuce, celery, horse
radish, potatoes, rice, rights-of-way, wasteland, rural shelter belts and for control of ticks (Table
28). These uses of carbaryl are determined to likely adversely affect the CRLF through indirect
chronic effects on aquatic vertebrate prey items.
Page 131 of 160
-------
Small terrestrial mammals
Acute dose-based RQ values (RQ range 0.37 - 6.5) representing carbaryl exposures to mice
(small mammals) indicate potential for indirect effects to CRLF from all uses of carbaryl
modeled through decreased availability of prey. Chronic dietary-based RQ values (RQ range 3 -
56) indicate chronic risk to small vertebrates serving as prey to terrestrial-phase CRLF for all
carbaryl uses (Table 34). Based on the highest dose-based RQ (RQ=6.5) for terrestrial
mammals, the likelihood of individual mortality is 100% (based on default slope of 4.5;
Appendix K). Even at the lowest RQ for mammals (RQ=0.35), the likelihood of individual
mortality is 20%. Therefore, the determination for indirect effects to the CRLF due to effects to
terrestrial mammals is "LAA" for all uses of carbaryl.
Small terrestrial-phase amphibians
In order to explore influences of amphibian-specific food intake equations on potential dose-
based and dietary-based exposures of amphibians (prey of CRLF) to carbaryl, T-HERPS is used.
The Pacific tree frog is used to represent the amphibian prey species. The weight of the animal
was assumed to be 2.3 g, and its diet was assumed to be composed of small and large insects.
Consideration of dose-based RQs calculated by T-HERPS for small (1.4g) and medium (37 g)
sized CRLF which consume small and large invertebrates (Tables 36 and 37), indicates that
amphibian specific EECs for frogs smaller and larger than the Pacific Tree frog are insufficient
to reach levels where no mortality was observed in a laboratory study with birds (surrogates for
terrestrial-phase frogs) {i.e. the RQs are <1). 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 39). Again, although dietary-based RQs potentially exceed the LOC,
EECs for frogs are insufficient to reach levels where no mortality was observed in a laboratory
study with birds {i.e. the RQs are <1). This indicates that mortality from acute carbaryl exposures
to terrestrial frogs representing CRLF prey is unlikely.
Chronic 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 40). Refined
dietary-based RQs indicate that, for some carbaryl uses, there is potential for chronic effects to
terrestrial frogs feeding on small insects. Chronic RQs are exceeded by factors ranging 1.05X to
8.4X. RQs do not exceed the chronic LOC for terrestrial frogs feeding on large insects, which
also compose the diet of prey of the CRLF. Since frogs would be expected to consume both
small and large insects, it seems likely that the actual EEC should fall somewhere between the
extreme EECs representing diets composed only of small insects and diets composed only of
large insects. Therefore, there is potential for estimates of exposure and s
In the available chronic study where mallard ducks were exposed to carbaryl, the NOAEC was
300 ppm, and the LOAEC was 600 ppm, based on decreased number of eggs. Comparison of the
LOAEC directly to chronic dietary-based EECs indicate that several EECs are sufficient to
exceed the concentration were reproductive effects were observed in the laboratory. Some EECs
are insufficient to exceed the LOAEC. As discussed above, it is assumed that the actual exposure
concentration where effects are exhibited lies somewhere between the NOAEC and the LOAEC.
Page 132 of 160
-------
Given the uncertainty associated with the actual level where effects occur, risks of chronic
exposures of the terrestrial prey frogs to carbaryl cannot be discounted.
Therefore, for all uses where the chronic RQ exceeds the LOC, the determination for indirect
effects to the CRLF due to chronic effects to terrestrial frogs representing its prey is "LAA." For
uses where the chronic RQs for the do not exceed the LOC, the determination is "NLAA" for
indirect effects to the CRLF due to chronic effects to frogs representing its prey.
Summary of indirect effects to the CRLF based on effects to prey
When considering indirect effects to the CRLF through effects to its prey, estimates of exposure
are sufficient to be of concern for effects based on decreased prey for several taxa of the CRLF's
prey for the majority of carbaryl uses. Although effects to the prey of the tadpole life stage are
not expected for the majority of carbaryl's uses (with the exception of use on rice), effects to the
prey of the juvenile and adult lifestages of the CRLF are of concern. The overall effects
determination for the CRLF based on indirect effects due to effects due to prey is "LAA" for all
uses of carbaryl (Table 42).
Page 133 of 160
-------
Table 42. Carbaryl use-specific indirect effects determinations1 based on effects to prey (shading added to
indicate use where there is any LAA determination).
Crop Group2
Algae
Aquatic
Invertebrates
Terrestrial
Invertebrates
(Acute)
Aquatic-phase frogs
and tlsh
Terrestrial-phase
frogs
Small Mammals
Acute
Chronic
Acute
Chronic
Acute
Chronic
Acute
Chronic
A: home lawn
NE
LAA
LAA
LAA
NLAA
NE
NLAA
LAA
LAA
LAA
B: flowers beds
around buildings
NE
LAA
NE
LAA
NE
NE
NLAA
LAA
LAA
LAA
C: lawns
NE
LAA
LAA
LAA
NLAA
LAA
NLAA
LAA
LAA
LAA
D: ornamentals
NE
LAA
LAA
LAA
LAA
LAA
NLAA
LAA
LAA
LAA
E: parks
NE
LAA
LAA
LAA
NLAA
NE
NLAA
LAA
LAA
LAA
F: citrus
NE
LAA
LAA
LAA
NLAA
LAA
NLAA
LAA
LAA
LAA
G: olives
NE
LAA
LAA
LAA
NLAA
LAA
NLAA
LAA
LAA
LAA
H: almonds
NE
LAA
LAA
LAA
NLAA
LAA
NLAA
LAA
LAA
LAA
I: flowers
NE
LAA
LAA
LAA
NLAA
NE
NLAA
LAA
LAA
LAA
J: peaches
NE
LAA
LAA
LAA
NLAA
LAA
NLAA
LAA
LAA
LAA
K: asparagus
NE
LAA
LAA
LAA
NLAA
LAA
NLAA
LAA
LAA
LAA
L: apple
NE
LAA
LAA
LAA
NLAA
LAA
NLAA
LAA
LAA
LAA
M: loquat
NE
LAA
LAA
LAA
NLAA
LAA
NLAA
LAA
LAA
LAA
N: sweet corn
NE
LAA
LAA
LAA
NLAA
LAA
NLAA
LAA
LAA
LAA
0: grapes
NE
LAA
LAA
LAA
NLAA
LAA
NLAA
LAA
LAA
LAA
P: strawberries
NE
LAA
LAA
LAA
LAA
LAA
NLAA
LAA
LAA
LAA
Q: tomatoes
NE
LAA
LAA
LAA
NLAA
LAA
NLAA
LAA
LAA
LAA
R: Peanuts
NE
LAA
LAA
LAA
NLAA
NE
NLAA
LAA
LAA
LAA
S: Broccoli
NE
LAA
LAA
LAA
NLAA
LAA
NLAA
LAA
LAA
LAA
T: Brussels sprouts
NE
LAA
LAA
LAA
LAA
LAA
NLAA
LAA
LAA
LAA
U: Sweet potato
NE
LAA
LAA
LAA
NLAA
LAA
NLAA
LAA
LAA
LAA
V: Field corn
NE
LAA
LAA
LAA
NE
NE
NLAA
NLAA
LAA
LAA
W: Lettuce, head
NE
LAA
LAA
LAA
LAA
LAA
NLAA
LAA
LAA
LAA
X: Sorghum
NE
LAA
LAA
LAA
NLAA
NE
NLAA
LAA
LAA
LAA
Y: Celery
NE
LAA
LAA
LAA
NLAA
LAA
NLAA
LAA
LAA
LAA
Z: Horseradish
NE
LAA
LAA
LAA
NLAA
LAA
NLAA
LAA
LAA
LAA
AA: Potato
NE
LAA
LAA
LAA
NLAA
LAA
NLAA
LAA
LAA
LAA
AB: Radish
NE
LAA
LAA
LAA
NLAA
NE
NLAA
LAA
LAA
LAA
AC: Rice
LAA
LAA
LAA
LAA
LAA
LAA
NLAA
NLAA
LAA
LAA
AD: Beans
NE
LAA
LAA
LAA
NE
NE
NLAA
NLAA
LAA
LAA
AE: Okra
NE
LAA
LAA
LAA
NE
NE
NLAA
NLAA
LAA
LAA
AF: Sugar beet
NE
LAA
LAA
LAA
NLAA
NE
NLAA
NLAA
LAA
LAA
AG: Alfalfa
NE
LAA
LAA
LAA
NE
NE
NLAA
NLAA
LAA
LAA
AH: Pasture
NE
LAA
LAA
LAA
NLAA
NE
NLAA
NLAA
LAA
LAA
AI: Grass for seed
NE
LAA
LAA
LAA
NE
NE
NLAA
NLAA
LAA
LAA
AJ: Rang eland
NE
LAA
LAA
LAA
NLAA
NE
NLAA
NLAA
LAA
LAA
AK: Melon
NE
LAA
LAA
LAA
NE
NE
NLAA
NLAA
LAA
LAA
AL: Roses
NE
LAA
LAA
LAA
NLAA
NE
NLAA
NLAA
LAA
LAA
AM: Rights-of-way
NE
LAA
LAA
LAA
NLAA
LAA
NLAA
NLAA
LAA
LAA
AN: Wasteland
NE
LAA
LAA
LAA
NLAA
LAA
NLAA
NLAA
LAA
LAA
AO: Non-urban
forests
NE
LAA
LAA
LAA
NLAA
NE
NLAA
NLAA
LAA
LAA
AP: Rural shelter belts
NE
LAA
LAA
LAA
NLAA
LAA
NLAA
NLAA
LAA
LAA
AQ: Ticks
NE
LAA
LAA
LAA
NLAA
LAA
NLAA
LAA
LAA
LAA
*LAA = likely to adversely affect; NLAA = not likely to adversely affect; NE = no effect. 2For specific uses associated with each crop group see Table 5.
Page 134 of 160
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5.2.3. Indirect Effects (through effects to habitat)
As discussed in section 2.5.4, the habitat of the CRLF varies during its life cycle, with the CRLF
surviving in aquatic, riparian and upland areas. Adults rely on riparian vegetation for resting,
feeding, and dispersal. 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).
Based on RQs for unicellular and vascular plants inhabiting aquatic habitats (Table 31),
applications of carbaryl are not expected to affect these plants, except in cases where
applications are made to rice. RQs for rice exceed the LOC for aquatic plants by a factor of
approximately 2, meaning that estimated exposure concentrations are twice the level where 50%
effects have been observed in laboratory tests involving aquatic plants exposed to carbaryl.
One available study is useful for defining the toxicity of carbaryl to riparian and terrestrial plants.
In this tier 1 vegetative vigor study, less than 25% effects to dry weight or survival were
observed when plants were treated with 0.8 lbs a.i./A of carbaryl (MRID 45784807). For some
uses, the potential concentrations of carbaryl in the environment exceed this application rate,
leaving uncertainty regarding whether or not the higher applications of carbaryl can result in
effects to riparian and terrestrial habitat.
According to the baseline ecological risk assessment chapter in support of the reregi strati on
eligibility decision for carbaryl (USEPA 2003), there are carbaryl labels stating that it may cause
injury to tender foliage if applied to wet foliage or during periods of high humidity. In addition,
carbaryl, which acts as an auxin (plant hormone), can be used for fruit thinning, which indicates
that it has potential for reproductive effects to plants.
The greatest number of incidents (11) for carbaryl has involved terrestrial plants. While the
majority of these incident reports have been associated with homeowner use of the product, some
agricultural crops, e.g., quince and olive, have reported losses resulting from spotting, low fruit
set and malformations in fruit shape.
Although aquatic RQs indicate that aquatic plants are unlikely to be affected by carbaryl use,
with the exception of use on rice, potential risks of carbaryl to riparian and terrestrial vegetation
cannot be discounted. Carbaryl is known to affect plants and is used to thin fruit in orchards
According to the carbaryl label (Sevin® 50WP; EPA Reg No. 769-972), the recommended rate
for thinning apples is 0.5 - 1 lbs a.i./A and is higher than the maximum rate tested in the
terrestrial plant studies; thus the likelihood of effects on terrestrial plants at the higher application
rate is uncertain; however, treatment at this rate is known to result in abscission of flowers.
Additionally, several incidents involving plant damage are associated with the use of carbaryl.
As a result, the extent of risk of carbaryl for plants cannot be quantified. Therefore, the
determination for indirect effects to the CRLF caused by effects to riparian and terrestrial plants
resulting from use of carbaryl is "likely to adversely affect."
Page 135 of 160
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5.2.4. Primary Constituent Elements of Designated Critical Habitat
5.2.4.1. Aquatic-Phase (Aquatic breeding habitat and aquatic non-breeding
habitat)
Two of the four assessment endpoints for the aquatic-phase primary constituent elements (PCEs)
of designated critical habitat for the CRLF are related to potential effects to aquatic and/or
riparian plants:
• 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.
• 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.
Due to potential effects to riparian vegetation caused by use of carbaryl, the determination is
"habitat modification."
The third aquatic-phase PCE is "alteration of other chemical characteristics necessary for normal
growth and viability of CRLFs and their food source." Carbaryl is not expected to alter the
chemical characteristics of the water such that growth and viability of the CRLF or their habitat
would not be a concern.
Another of the aquatic-phase PCE is: reduction and/or modification of aquatic-based food
sources for pre-metamorphs (e.g., algae). RQs do not exceed the LOC for algae for uses of
carbaryl, with the exception of use on rice. Therefore, for all carbaryl uses, except rice, this PCE
is not of concern.
5.2.4.2. Terrestrial-Phase (upland habitat and dispersal habitat)
Three of the four assessment endpoints for the terrestrial-phase PCEs of designated critical
habitat for the CRLF are related to potential effects to terrestrial plants:
• 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 drip line
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
• 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
Page 136 of 160
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• Alteration of chemical characteristics necessary for normal growth and viability of
juvenile and adult CRLFs and their food source.
Potential risk of carbaryl to terrestrial plants resulting in the determination of "habitat
modification."
The remaining terrestrial-phase PCE is "reduction and/or modification of food sources for
terrestrial phase juveniles and adults." RQs for terrestrial invertebrates, which represent a food
source for terrestrial phase CRLF, exceed the LOC. Therefore, the determination for this
endpoint is "habitat modification."
5.2.5. Action Area
5.2.5.1. Areas indirectly affected by the federal action
The initial action area for carbaryl was previously discussed in Section 2.7 and depicted in
Figures 6-10 of the problem formulation. In order to determine the extent of the action area in
lotic (flowing) aquatic habitats, the greatest ratios of the RQ to the LOC for any endpoint for
aquatic organisms for each use category is used to determine the distance downstream for
concentrations to be diluted below levels that would be of concern {i.e. result in RQs above the
LOC). For this assessment, this applies to RQs for acute exposures of carbaryl to aquatic
invertebrates. For all uses in a landcover category, the highest RQ/LOC ratio is used to define the
action area for that group of uses (Table 43). The total stream kilometers within the action area
that are estimated to be at levels of concern are defined in Table 44.
Page 137 of 160
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Table 43. Down stream dilution factors used to determine extent of lotic action area for uses of carbaryl.
Action area title
Uses
Down stream
dilution factor
(RQ/LOC ratio)
Specific use
group defining
down stream
dilution factor
Orchard/vineyard
citrus, olives, almonds, chestnuts, pecans,
filberts, walnuts, pistachios, peaches, apricots,
cherries, nectarines, plums, prunes, pears,
crabapples, oriental pears, apple, loquat,
grapes
660
Peaches
agricultural lands
asparagus, corn, strawberries, tomatoes,
eggplant, peanuts, broccoli, Brussels sprouts,
sweet potato, corn, lettuce, dandelion, endive,
parsley, spinach, Swiss chard, sorghum,
celery, horseradish, potato, parsnip, rutabaga,
turnip, radish, rice, dry beans, fresh peas, dry
peas, cow peas, southern peas, okra, sugar
beet, alfalfa, birds foot trefoil, clover, melon,
cucumber, pumpkin, squash, grass for seed,
rural shelter belts, ornamentals, flowers, roses,
peppers, cauliflower, cabbage, kohlrabi,
Chinese cabbage, collards, kale, mustard
greens, Hanover salad
30340
Rice
residential (urban)
flower beds around buildings, roses, home
lawn, lawns, parks, recreational areas, golf
courses, sod farms, commercial lawns, rights-
of-way, hedgerows, ditch banks, roadsides,
ticks, grasshoppers
336
Rights-of-way
pasture
pasture, rangeland
150
Rangeland
non-urban forests
Forestry, tree plantations, Christmas trees,
parks, rangeland trees
136
Forestry
Table 44. Quantitative results of spatial analysis of lotic aquatic action area relevant to carbaryl uses (in km).
Measure
Orchard/
vineyard
Agriculture
Residential
Pastu re
Forest
Total Streams in CA
332,962
Streams within initial area of concern
11,946
56,404
104,061
29,071
142,464
Downstream distance added
3,431
9,158
7,739
8,559
26,676
Streams in aquatic action area
15,377
65,562
111,800
37,630
169,140
When considering the terrestrial habitats of the CRLF, spray drift from use sites onto non-target
areas could potentially result in exposures of the CRLF, its prey and its habitat to carbaryl.
Therefore, it is necessary to estimate the distance from the application site where spray drift
exposures do not result in LOC exceedances for organisms within the terrestrial habitat. To
account for this, first, the carbaryl application rate which does not result in an LOC exceedance
is calculated for each terrestrial taxa of concern. AgDISP was then used to determine the
distance required to reach EECs not exceeding any LOCs. These values are defined for each use
in Table 45.
Page 138 of 160
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Table 45. Spray drift distances used to determine extent of terrestrial action area for uses of carbaryl.
Action area title
Uses
Spray drift
distance not
exceeding
LOC (in feet)
Specific use
group defining
spray drift
distance
Orchard/vineyard
citrus, olives, almonds, chestnuts, pecans, filberts,
walnuts, pistachios, peaches, apricots, cherries,
nectarines, plums, prunes, pears, crabapples,
oriental pears, apple, loquat, grapes
10920
citrus
agricultural lands
asparagus, corn, strawberries, tomatoes, eggplant,
peanuts, broccoli, Brussels sprouts, sweet potato,
corn, lettuce, dandelion, endive, parsley, spinach,
Swiss chard, sorghum, celery, horseradish, potato,
parsnip, rutabaga, turnip, radish, rice, dry beans,
fresh peas, dry peas, cow peas, southern peas,
okra, sugar beet, alfalfa, birds foot trefoil, clover,
melon, cucumber, pumpkin, squash, grass for
seed, rural shelter belts, ornamentals, flowers,
roses, peppers, cauliflower, cabbage, kohlrabi,
Chinese cabbage, collards, kale, mustard greens,
Hanover salad
6238
asparagus
residential (urban)
flower beds around buildings, roses, home lawn,
lawns, parks, recreational areas, golf courses, sod
farms, commercial lawns, rights-of-way,
hedgerows, ditch banks, roadsides, ticks,
grasshoppers
6293
turf
pasture
pasture, rangeland
3293
rangeland
non-urban forests
Forestry, tree plantations, Christmas trees, parks,
rangeland trees
3293
forestry
To understand the area indirectly affected by the federal action due to spray drift from
application areas of carbaryl, landcovers are considered as potential application areas. These
areas are "buffered" using ArcGIS 9.2. In this process, the original landcover is modified by
expanding the border of each polygon representing a field out to a designated distance, which in
this case, is the distance estimated where carbaryl in spray drift does not exceed any LOCs. This
effectively expands the action area relevant to terrestrial habitats so that it includes the area
directly affected by the federal action, and the area indirectly affected by the federal action.
5.2.5.2. Final action area
In order to define the final action areas relevant to uses of carbaryl, it is necessary to combine
areas directly affected, as well as aquatic and terrestrial habitats indirectly affected by the federal
action. This is done separately for the 5 categories of action areas (i.e. agricultural,
orchard/vineyard, residential, pasture and forests) using ArcGIS 9.2. Landcovers representing
areas directly affected by carbaryl applications are overlapped with indirectly affected aquatic
habitats (determined by down stream dilution modeling) and with indirectly affected terrestrial
habitats (determined by spray drift modeling). It is assumed that lentic (standing water) aquatic
habitats (e.g. ponds, pools, marshes) overlapping with the terrestrial areas are also indirectly
affected by the federal action. The result is the final action area for carbaryl uses (Figures 19-
23).
Page 139 of 160
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Legend
County Boundary
lotic aquatic action area
terrestrial and lentic action area
Compiled from California County boundaries (ESRI, 2002),
USDA National Agriculture Statistical Service (NASS.2002)
Gap Analysis Program Orchard/Vineyard Landcover (GAP)
National Land Cover Database (NLCD) (MRLC,2001)
Map created by U.S. Environmental Protection Agency,
Office of Pesticides Programs, Environmental Fate and
Effects Division. April 11, 2007.
Projection: Albers Equal Area Conic USGS,
North American Datum of 1983 (NAD 1983)
Figure 19. Final action area for crops described by orchard/vineyard landcover which corresponds to
potential carbaryl use sites. This map represents the area potentially directly and indirectly affected by the
federal action.
Page 140 of 160
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N
Legend
County Boundary
terrestrial and lentic action area
lotic aquatic action area
90 45
0
90 Miles
Compiled from California County boundaries (ESRI, 2002),
USDA National Agriculture Statistical Service (NASS.2002)
Gap Analysis Program Orchard/Vineyard Landcover (GAP)
National Land Cover Database (NLCD) (MRLC,2001)
Map created by U.S. Environmental Protection Agency,
Office of Pesticides Programs, Environmental Fate and
Effects Division. April 11, 2007.
Projection: Albers Equal Area Conic USGS,
North American Datum of 1983 (NAD 1983)
Figure 20. Final action area for crops described by agricultural landcover which corresponds to potential
carbaryl lithium use sites. This map represents the area potentially directly and indirectly affected by the
federal action.
Page 141 of 160
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Legend
County Boundary
terrestrial and lentic action area V
lotic aquatic action area
J
N
90 45
0
90 Miles
Compiled from California County boundaries (ESRI, 2002),
USDA National Agriculture Statistical Service (NASS.2002)
Gap Analysis Program Orchard/Vineyard Landcover (GAP)
National Land Cover Database (NLCD) (MRLC,2001)
Map created by U.S. Environmental Protection Agency,
Office of Pesticides Programs, Environmental Fate and
Effects Division. April 11, 2007.
Projection: Albers Equal Area Conic USGS,
North American Datum of 1983 (NAD 1983)
Figure 21. Final action area for crops described by residential landcover which corresponds to potential
carbaryl use sites. This map represents the area potentially directly and indirectly affected by the federal
action.
Page 142 of 160
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r
N
Legend
County Boundary
lotic aquatic action area ^
terrestrial and lentic aquatic action area
90 45 0
90 Miles
Compiled from California County boundaries (ESRI, 2002),
USDA National Agriculture Statistical Service (NASS.2002)
Gap Analysis Program Orchard/Vineyard Landcover (GAP)
National Land Cover Database (NLCD) (MRLC,2001)
Map created by U.S. Environmental Protection Agency,
Office of Pesticides Programs, Environmental Fate and
Effects Division. April 11, 2007.
Projection: Albers Equal Area Conic USGS,
North American Datum of 1983 (NAD 1983)
Figure 22. Final action area for crops described by pasture landcover which corresponds to potential
carbaryl use sites. This map represents the area potentially directly and indirectly affected by the federal
action.
Page 143 of 160
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N
J
Legend
County Boundary
lotic aquatic action area ^
terrestrial and lentic aquatic action area;
\
90 45 0
90 Miles
Compiled from California County boundaries (ESRI, 2002),
USDA National Agriculture Statistical Service (NASS.2002)
Gap Analysis Program Orchard/Vineyard Landcover (GAP)
National Land Cover Database (NLCD) (MRLC,2001)
Map created by U.S. Environmental Protection Agency,
Office of Pesticides Programs, Environmental Fate and
Effects Division. April 11, 2007.
Projection: Albers Equal Area Conic USGS,
North American Datum of 1983 (NAD 1983)
Figure 23. Final action area for crops described by non-urban forest landcover which corresponds to
potential carbaryl use sites. This map represents the area potentially directly and indirectly affected by the
federal action. *Within recovery units.
Page 144 of 160
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5.2.5.3. Overlap between CRLF habitat and final action area
In order to confirm that uses of carbaryl have the potential to affect CRLF through direct
applications to target areas and runoff and spray drift to non-target areas, it is necessary to
determine whether or not the final action areas for carbaryl uses overlap with CRLF habitats.
Spatial analysis using ArcGIS 9.2 indicates that lotic aquatic habitats within the CRLF core areas
and critical habitats potentially contain concentrations of carbaryl sufficient to result in RQ
values that exceed LOCs. In addition, terrestrial habitats (and potentially lentic aquatic habitats)
of the final action areas overlap with the core areas, critical habitat and available occurrence data
for CRLF (Tables 46-50). Thus, uses of carbaryl could result in exposures of carbaryl to CRLF
in aquatic and terrestrial habitats. Additional analysis related to the intersection of the carbaryl
action areas and CRLF habitat is described in Appendix C.
Table 46. Overlap between CRLF habitat (core areas and critical habitat) and orchard/vineyard action area
by recovery unit (RU#).
Measure
RU1
RU2
RU3
RU4
RU5
RU6
RU7
RU8
Total
CRLF habitat (km2)*
3654
2742
1323
3279
3650
5306
4917
3326
28,197
Overlapping area of CRLF
habitat and terrestrial/lentic
aquatic action area (km2)
126
285
27
218
76
354
906
745
2,736
% CRLF habitat overlapping
with terrestrial/lentic aquatic
Action Area
3%
10%
2%
7%
2%
7%
18%
22%
10%
# Occurrences overlapping with
terrestrial/lentic aquatic action
area (959 total)
0
0
2
53
11
4
23
4
97
*Area occupied by core areas and/or critical habitat.
Table 47. Overlap between CRLF habitat (core areas and critical habitat) and agricultural action area by
recovery unit (RU#). i
Measure
RU1
RU2
RU3
RU4
RU5
RU6
RU7
RU8
Total
CRLF habitat (km2)*
3654
2742
1323
3279
3650
5306
4917
3326
28,197
Overlapping area of CRLF
habitat and terrestrial/lentic
aquatic action area (km2)
447
289
189
1010
1571
1494
1940
616
7,555
% CRLF habitat overlapping
with terrestrial/lentic aquatic
Action Area
12%
11%
14%
31%
43%
28%
39%
19%
27%
# Occurrences overlapping with
terrestrial/lentic aquatic action
area (959 total)
0
0
18
141
208
48
70
3
488
*Area occupied by core areas and/or critical habitat.
Page 145 of 160
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Table 48. Overlap between CRLF habitat (core areas and critical habitat) and residential action area by
recovery unit (RU#). i
Measure
RU1
RU2
RU3
RU4
RU5
RU6
RU7
RU8
Total
CRLF habitat (km2)*
3654
2742
1323
3279
3650
5306
4917
3326
28,197
Overlapping area of CRLF
habitat and terrestrial/lentic
aquatic action area (km2)
2764
2154
1183
2614
3298
4168
3835
2895
22911
% CRLF habitat overlapping
with terrestrial/lentic aquatic
Action Area
76%
79%
89%
80%
90%
79%
78%
87%
81%
# Occurrences overlapping with
terrestrial/lentic aquatic action
area (959 total)
10
3
69
308
275
119
90
33
907
*Area occupied by core areas and/or critical habitat.
Table 49. Overlap between CRLF habitat (core areas and critical habitat) and pasture action area by
recovery unit (RU#).
Measure
RU1
RU2
RU3
RU4
RU5
RU6
RU7
RU8
Total
CRLF habitat (km2)*
3654
2742
1323
3279
3650
5306
4917
3326
28,197
Overlapping area of CRLF
habitat and terrestrial/lentic
aquatic action area (km2)
82
273
24
89
382
499
977
139
2465
% CRLF habitat overlapping
with terrestrial/lentic aquatic
Action Area
2%
10%
2%
3%
10%
9%
20%
4%
9%
# Occurrences overlapping with
terrestrial/lentic aquatic action
area (959 total)
0
0
2
26
79
22
48
1
178
*Area occupied by core areas and/or critical habitat.
Table 50. Overlap between CRLF habitat (core areas and critical habitat) and forestry action area by
recovery unit (RU#).
Measure
RU1
RU2
RU3
RU4
RU5
RU6
RU7
RU8
Total
CRLF habitat (km2)*
3654
2742
1323
3279
3650
5306
4917
3326
28,197
Overlapping area of CRLF
habitat and terrestrial/lentic
aquatic action area (km2)
3643
2222
1205
2665
3453
2782
4400
2315
22,688
% CRLF habitat overlapping
with terrestrial/lentic aquatic
Action Area
100%
81%
91%
81%
95%
52%
89%
70%
80%
# Occurrences overlapping with
terrestrial/lentic aquatic action
area (959 total)
5
3
33
205
240
78
68
10
642
*Area occupied by core areas and/or critical habitat.
Page 146 of 160
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5.2.6. Description of Assumptions, Limitations, Uncertainties, Strengths and Data
Gaps
5.2.6.1. Exposure Assessment
Aquatic exposure modeling of carbaryl
The standard ecological water body scenario (EXAMS pond) used to calculate potential aquatic
exposure to pesticides is intended to represent conservative estimates, and to avoid
underestimations of the actual exposure. The standard scenario consists of application to a 10-
hectare field bordering a 1-hectare, 2-meter deep (20,000 m3) pond with no outlet. Exposure
estimates generated using the EXAMS pond are intended to represent a wide variety of
vulnerable water bodies that occur 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 have higher peak EECs than the EXAMS pond.
These water bodies will be either smaller in size or have larger drainage areas. Smaller water
bodies have limited storage capacity and thus may overflow and carry pesticide in the discharge,
whereas the EXAMS pond has no discharge. As watershed size increases beyond 10-hectares, it
becomes increasingly unlikely that the entire watershed is planted with a single crop that is all
treated simultaneously with the pesticide. 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
carried and dissipated downstream.
The Agency acknowledges that there are some unique aquatic habitats that are not accurately
captured by this modeling scenario and modeling results may, therefore, under- or over-estimate
exposure, depending on a number of variables. For example, aquatic-phase CRLFs may inhabit
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 information
regarding the hydrology of these aquatic habitats to develop a specific alternate scenario for the
CRLF. As previously discussed in Section 2 and in Attachment 1, CRLFs prefer habitat with
perennial (present year-round) or near-perennial 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 representative of exposure to
aquatic-phase CRLFs. In addition, the Services agree that the existing EXAMS pond represents
the best currently available approach for estimating aquatic exposure to pesticides
(USFWS/NMFS 2004a).
In order to account for this uncertainty, available monitoring data were compared to
PRZM/EXAMS estimates of peak EECs for the different uses. As discussed above, several data
values were available from NAWQA for carbaryl concentrations measured in surface waters
receiving runoff from agricultural areas. The specific use patterns (e.g. application rates and
timing, crops) associated with the agricultural areas are unknown, however, they are assumed to
be representative of potential carbaryl use areas. Peak EECs resulting from different carbaryl
Page 147 of 160
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uses ranged 5.6 - 2579 |ig/L. The maximum concentration of carbaryl reported by NAWQA
(1999-2005) for California surface waters with agricultural watersheds (1.06 |ig/L) is three
orders of magnitude less than the maximum EEC, but within the range of EECs estimated for
different uses. The maximum concentration of carbaryl reported by the California Department of
Pesticide Regulation surface water database (1999-2005) (0.31 |ig/L) is roughly four orders of
magnitude lower than the highest peak EEC.
When considering 2000-2005 NAWQA monitoring data for California in the context of the
effects data, 1.1% of samples (15 out of 1393) contained concentrations of carbaryl at levels
(>0.085 |ig/L) sufficient to exceed the LOC for aquatic invertebrates. In CDPR surface water
monitoring data from 2000-2005, carbaryl was detected at concentrations sufficient to result in
RQ values that exceed the invertebrate acute risk LOC {i.e., >0.085 |ig/L) in a single sample.
Carbaryl was not detected at concentrations sufficient to exceed the direct effects acute risk LOC
(>12.5 |ig/L) in any of the samples (Figure 15).
Differences between modeled EECs and monitoring results are generally attributable to three
sources: 1) simulation modeling estimates are made using maximum label rates, monitoring data
reflects typical use, 2) modeled values represent a small static water body, the vast majority of
monitoring data is for streams and rivers which tend to be less vulnerable as high concentration
tend to be of short duration as they pesticide is carried downstream more rapidly; 3) simulation
modeling represents a small watershed near the area of application; 4) monitoring data usually
represents higher order streams with large basins and multiple land uses; 5: modeled values are 1
in 10 year exceedance values. Since most monitoring data is from one or two year studies at any
one site, it represents 1 in 2 year values. This is reflected in the simulation modeling as well. The
1 in 10 year peak EEC for carbaryl for lettuce was 93.5 |ig-L_1 while the 1 in 2 year EEC is 23.1
Terrestrial exposure modeling of carbaryl
As indicated above, only similar foliar applications are considered when assessing EECs for
terrestrial-phase CRLF and its prey (terrestrial invertebrates, small mammals and frogs), since T-
REX. not appropriate for modeling soil applications with incorporation. Several of the uses, e.g.
dormant applications to orchard crops and pre- versus post-emergent applications to asparagus,
utilize different application rates.
Deposition of carbaryl in precipitation
Carbaryl has been detected in precipitation samples in California (Table 51). Based on these
data, it is possible that carbaryl can be deposited on land in precipitation. Estimates of exposure
of the CRLF, its prey and its habitat to carbaryl included in this assessment are based only on
transport of carbaryl through runoff and spray drift from application sites. Current estimates of
exposures of CRLF and its prey to carbaryl through runoff and spray drift, which are already
sufficient to exceed the LOC, would be expected to be greater due to deposition in precipitation.
Page 148 of 160
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Location
Year
Sample
type
Maximum
Cone (jig/L)
Detection
frequency
(number
samples)
Sou rcc
San Joaquin Valley, CA
2002-
2004
Rain
0.756
68%
(n= 137)
Majewski et al. 2006
Monterey, CA
1987
Fog
4.0
100%
(n=5)
Schomburg el al. 1991
In an attempt to estimate the amount of carbaryl deposited into aquatic and terrestrial habitats,
carbaryl concentrations measured in rain samples taken in California (Majewski et al. 2005) were
considered in combination with California specific precipitation data and runoff estimates from
PRZM. Precipitation and runoff data associated with the PRZM scenarios used to model aquatic
EECs were used to determine relevant l-in-10 year peak runoff and rain events. The scenarios
included were: CA almond, CA lettuce, CA wine grape, CA row crop, CA fruit, CA nursery, and
CA onion. The corresponding meteorological data were from the following locations:
Sacramento, Santa Maria, San Francisco, Monterey County, Fresno, San Diego, and Bakersfield,
respectively.
To estimate concentrations of carbaryl in the aquatic habitat resulting from deposition in rain, the
daily PRZM-simulated volume of runoff from a 10 ha field is combined with an estimate of daily
precipitation volumes over the 1 ha farm pond relevant to the EXAMS environment. This
volume is multiplied by the maximum concentration of carbaryl in precipitation reported in
monitoring data, which is 0.756 |ig/L. The result is a daily mass load of carbaryl into the farm
pond. This mass is then divided by the volume of water in the farm pond (2.0 xl07L) to achieve
a daily estimate of carbaryl concentration in the farm pond, which represents the aquatic habitat.
From the daily values, the l-in-10 year peak estimate of the concentration of carbaryl in the
aquatic habitat is determined for each PRZM scenario (Table 52). There are several
assumptions associated with this approach, including: 1) the concentration of carbaryl in the rain
event is spatially and temporally homogeneous (e.g. constant over the 10 ha field and 1 ha pond
for the entire rain event); 2) the entire mass of carbaryl contained in the precipitation runs off of
the pond or is deposited directly into the pond; 3) there is no degradation of carbaryl between the
time it leaves the air and the time it reaches the pond.
Table 52. l-in-10 year peak estimates of carbaryl concentrations in aquatic and terrestrial habitats resulting
Mel Sialion
Scenario
( oncenlralion in aqualic
habilal (uii/l.)
Deposition on
Icrrcslrial habilal
(lbs a.i./A)
Sacramento
CA almond
0.141
0.0005
Santa Maria
CA lettuce
0.152
0.0004
San Francisco
CA wine grape
0.133
0.0004
Monterey Co.
CA row crop
0.122
0.0005
Fresno
CA fruit
0.055
0.0003
San Diego
CA nursery
0.102
0.0004
Bakersfield
CA onion
0.041
0.0002
Page 149 of 160
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To estimate deposition of carbaryl on the terrestrial habitat resulting from deposition in rain, the
daily volume of water deposited in precipitation on 1 acre of land is estimated. This volume is
multiplied by the maximum concentration of carbaryl in precipitation reported in monitoring
data, which is 0.756 |ig/L. The result is a mass load of carbaryl per acre (converted to units of lbs
a.i./A). From the daily values, the l-in-10 year peak estimate of the deposition of carbaryl on the
terrestrial habitat is estimated for each PRZM scenario (Table 52). In this approach, it is
assumed that the concentration of carbaryl in the rain event is spatially and temporally
homogeneous (e.g. constant over the 1 A of terrestrial habitat for the entire rain event).
Additional uses not considered in quantitative EEC derivation
As discussed in the use characterization (Section 2.4.3) here are 13 use patterns for which
carbaryl is registered that were not explicitly evaluated. These are flax, home fruits and
vegetables, cranberries, proso millet, lentils, soybeans, dry southern peas, sunflower, tobacco,
transplants, wheat, and adult mosquitoes. Greater detail on the rationale for not considering these
use patterns is provided in Appendix A.
Degradates
As previously discussed in the effects assessment, the toxicity of the primary degradate of
carbaryl, i.e., 1-naphthol, is assumed to equivalent to or less than the parent compound;
therefore, RQ values are not derived for exposures to this degradate.
As discussed in the screening-level ecological risk assessment of carbaryl (USEPA 2003), 1-
naphthol is subject to both biotic and abiotic routes of degradation and laboratory studies suggest
that the compound degrades more rapidly than the parent. Additionally, 1-naphthol is less
mobile than carbaryl; therefore, 1-naphthol is not expected to contribute significantly to exposure
relative to the parent compound.
Mixture Effects
This assessment considers only the single active ingredient of carbaryl. However, the assessed
species and its environments may be exposed to multiple pesticides simultaneously. Interactions
of other toxic agents with carbaryl could result in additive effects, synergistic effects or
antagonistic effects. Evaluation of pesticide mixtures is beyond the scope of this assessment
because of the myriad factors that cannot be quantified based on the available data. Those
factors include identification of other possible co-contaminants and their concentrations,
differences in the pattern and duration of exposure among contaminants, and the differential
effects of other physical/chemical characteristics of the receiving waters (e.g. organic matter
present in sediment and suspended water). Evaluation of factors that could influence
additivity/synergism is beyond the scope of this assessment and is beyond the capabilities of the
available data to allow for an evaluation. However, it is acknowledged that not considering
mixtures could over- or under-estimate risks depending on the type of interaction and factors
discussed above. This assessment has however, analyzed the toxicity of carbaryl formulated
product mixtures (carbaryl formulations involving more than one active ingredient; Appendix
Page 150 of 160
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M) and has determined that none of the formulated products evaluated were more toxic than the
technical grade active ingredient data used for assessing both direct and indirect risks in this
document.
5.2.6.2. Effects Assessment
Direct Effects
As previously discussed, direct effects to aquatic-phase CRLF are based on freshwater fish data,
which are used as a surrogate for aquatic-phase amphibians. While a limited amount of
amphibian data are available, these studies either failed to establish an LC50 value or did not
report measured concentration values, making them inappropriate for derivation of quantitative
RQ values. If RQs are developed based on the nominal concentration LC50 value for the African
clawed frogs exposed to carbaryl (96-hr LC50-1.73 mg/L; Zaga et al. 1998), estimated
concentrations in the aquatic habitat would be insufficient to exceed the LOC for direct effects to
the CRLF for all but four uses (strawberries, Brussel sprouts, head lettuce and rice).
Available data suggest that amphibians are considerably less sensitive to carbaryl than fish. To
the extent to that amphibians are less sensitive than the surrogate species used in this assessment,
the assessment is conservative.
Toxicity data for terrestrial-phase amphibians is not available for use in this assessment.
Therefore, avian toxicity data are used as a surrogate for terrestrial-phase CRLF. There is
uncertainty regarding the relative sensitivity of amphibians and birds to carbaryl. If birds are
substantially more or less sensitive than the CRLF, then risk would be over or under estimated,
respectively.
Sublethal Effects
Open literature is useful in identifying sublethal effects associated with exposure to carbaryl.
However, no data are available to link the sublethal measurement endpoints to direct mortality or
diminished reproduction, growth and survival that are used by OPP as assessment endpoints.
OPP acknowledges that a number of sublethal effects have been associated with carbaryl
exposure; however, at this point there are insufficient data to definitively link the measurement
endpoints to assessment endpoints.
Indirect Effects
Indirect effects on the aquatic-phase CRLF are estimated based on the most sensitive
invertebrate tested, i.e., Chloroperla grammatica. Other, less sensitive, aquatic invertebrates may
be part of the diet of the aquatic-phase CRLR. Therefore, risk to C. grammatica, may not be
equivalent to risk to organisms comprising the diet of the CRLF and its use in this assessment
may result in an overestimation of risk.
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5.2.7. Addressing the Risk Hypotheses
In order to conclude this risk assessment, it is necessary to address the risk hypotheses defined in
section 2.9.1. Based on the conclusions of this assessment, none of the hypotheses can be
rejected, meaning that the stated hypotheses represent concerns in terms of effects of carbaryl on
the CRLF.
6. Conclusions
Based on estimated environmental concentrations for the currently registered uses of carbaryl,
RQ values are above the Agency's LOC for direct acute and chronic effects on the CRLF; this
represents a "may affect" determination. RQs exceed the LOC for acute and chronic exposures
to aquatic invertebrates and for acute exposures to terrestrial invertebrates. Therefore, there is a
potential to indirectly affect juvenile and adult CRLF due to effects to the invertebrate forage
base in aquatic and terrestrial habitats. The effects determination for indirect effects to the CRLF
due to effects to its prey base is "may affect." When considering the prey of larger CRLF in
aquatic and terrestrial habitats (e.g. frogs, fish and small mammals), RQs for these taxa also
exceed the LOC for acute and chronic exposures, resulting in a "may affect" determination. RQ
values for plants in aquatic habitats do not exceed the LOC, with the exception of use on rice.
Risk of carbaryl use on riparian and terrestrial vegetation cannot be discounted due to lack of a
definitive toxicity endpoint, incident data indicating that nontarget effects on plants have been
recorded in the field and the known effects of carbaryl on abscission of flowers. Therefore,
indirect effects to the CRLF through effects to its habitat is a "may affect" determination.
Refinement of all "may affect" determinations results in a "LAA" determination based on direct
effects to the CRLF, a "LAA" determination for indirect effects to the CRLF based on effects to
its prey and an "LAA" determination for indirect effects to the CRLF based on effects to its
habitat. Consideration of CRLF critical habitat indicates a determination of "habitat
modification" for aquatic and terrestrial habitats. The overall CRLF effects determination for
carbaryl use is "LAA."
Based on the conclusions of this assessment, a formal consultation with the U. S. Fish and
Wildlife Service under Section 7 of the Endangered Species Act should be initiated. Attachment
2, which includes information on the baseline status and cumulative effects for the CRLF, can be
used during this consultation to provide background information on past US Fish and Wildlife
Services biological opinions associated with the CRLF.
When evaluating the significance of this risk assessment's direct/indirect and 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 area. In fact, given the assumptions of drift and downstream transport {i.e., attenuation
with distance), pesticide exposure and associated risks to the species and its resources are
expected to decrease with increasing distance away from the treated field or site of application.
Evaluation of the implication of this non-uniform distribution of risk to the species would require
Page 152 of 160
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information and assessment techniques that are not currently available. Examples of such
information and methodology required for this type of analysis 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 predictions of
individual effects to the proportion of the population extant within 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 aquatic- and 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 healthy
individuals at varying life stages. Such information could be used to establish biologically
relevant thresholds of effects 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 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 mortality,
growth or reproductive impairment immediately following exposure to the pesticide. The
degree to which repeated exposure events and the inherent demographic characteristics of the
prey population play into the extent to which prey resources may recover is not predictable.
An enhanced understanding of long-term prey responses to pesticide exposure would allow
for a more refined determination of the magnitude and duration of resource impairment, and
together with the information described above, a more complete prediction of effects to
individual frogs and potential modification to critical habitat.
Page 153 of 160
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7. References
Altig, R. and R.W. McDiarmid. 1999. Body Plan: Development and Morphology. In R.W.
McDiarmid and R. Altig (Eds.), Tadpoles: The Biology of Anuran Larvae. University of
Chicago Press, Chicago, pp. 24-51.
Alvarez, J. 2000. Letter to the U.S. Fish and Wildlife Service providing comments on the Draft
California Red-legged Frog Recovery Plan.
Armbrust, K. and D. Crosby. 1991. Fate of Carbaryl, 1-Naphthol, and Atrazine in Seawater.
Pac. Sci., 45: 314-20.
Bracha, P. and R. O'Brian, 1966. J. Econ. Entomol. 59:1255.
Orrick, G. and D. Young. 2007. Guidance for Tier I Estimation of Aqueous Pesticide
Concentrations in Rice Paddies. Internal EPA Memorandum dated May 8, 2007.
Chapalmadugu, S. and G. Rasul Chaudhry, 1991. Hydrolysis of Carbaryl by a Pseudomonas sp.
and Construction of a Microbial Consortium that Completely Metabolize Carbaryl. Appl.
Environ. Microbiol, 57:744-750.
Chapman, R.A. and C.M. Cole, 1982. Observations on the Influence of Water and Soil pH on
the Persistence of Insecticides. J. Environ. Sci. Hlth., B 17:487-504.
Chaudhry, G. R., A.N. Ali, and W.B. Wheeler, 1988. Isolation of a methyl parathion-degrading
Pseudomonas sp. that possesses DNA homologous to the opd gene from a
Flavobacterium sp. Appl. Environ. Microbiol., 54:288-293.
Chib, J., 1986. Sevin brand carbaryl insecticide: bioaccumulation and fate of carbaryl in bluegill
sunfish {Lepomis macrochirus): Project No. 801R10; File No. 34540. Unpublished study
by Union Carbide Agricultural Projects Co., Inc. and Analytical Biochemistry
Laboratory, Inc.
Corbin. Mark. 2007. Drinking Water Exposure Assessment for the Human Health Risk Assessment
for the Reregistration Decision Eligibility (RED) of Naphthalene. Internal EPA
memorandum to Karen Whitby, dated April 25, 2007. D339118.
Crawshaw, G.J. 2000. Diseases and Pathology of Amphibians and Reptiles in: Ecotoxicology of
Amphibians and Reptiles', ed: Sparling, D.W., G. Linder, and C.A. Bishop. SETAC Publication
Series, Columbia, MO.
Environmental Fate and Effects Division. 2005. General Instructions for Using AGDISP (v.8.13)
to Determine Distance Off Field Needed to Be Below the LOC (To Estimate Terrestrial
Action Area for Endangered Species/To Develop Potential Mitigation Measures -Buffers.
Internal EPA Draft Guidance, dated October 2005.
Page 154 of 160
-------
Embrey, S. and P. Moran. 2006. Quality of Streamwater in the Puget Sound Basin—A Decade of
Study and Beyond. U.S. Geological Survey, National Water-Quality Assessment
Program, Washington Water Science Center, Tacoma, WA. Poster online at:
http://wa.water.usgs.gov/projects/pugt/data/4-2006-poster.pdf.
Fellers, G. M., et al. 2001. Overwintering tadpoles in the California red-legged frog {liana aurora
draytonii). Herpetological Review 32(3): 156-157.
Fellers, G.M, L.L. McConnell, D. Pratt, S. Datta. 2004. Pesticides in Mountain Yellow-Legged Frogs
(Rana Mucosa) from the Sierra Nevada Mountains of California, USA. Environmental
Toxicology & Chemistry 23 (9):2170-2177.
Fellers, Gary M. 2005a. Rana draytonii Baird and Girard 1852. California Red-legged Frog. Pages 552-
554. In: M. Lannoo (ed.) Amphibian Declines: The Conservation Status of United States Species,
Vol. 2: Species Accounts. University of California Press, Berkeley, California, xxi+1094 pp.
(http://www.werc.usgs.gov/pt-reves/pdfs/Rana%20dravtonii.PDF')
Fellers, Gary M. 2005b. California red-legged frog, Rana draytonii Baird and Girard. Pages 198-201. In:
L.L.C. Jones, et al (eds.) Amphibians of the Pacific Northwest, xxi+227.
Ferreira, G.A. and J. N. Seiber. 1981. J. Agric. Food Chem., 29:93-99.
Fletcher, J.S., Nellessen, and T.G. Pfleeger. 1994. Literature Review and Evaluation of the EPA
Food-chain (Kenaga) Nomogram, an Instrument for Estimating Pesticide Residues on
Plants. Environ. Tox. Chem. 13:1383-1391.
Foreman, W.T., M. S. Majewski, D. A. Goolsby, F. W. Wiebe, and R. H. Coupe, 2000.
Pesticides in the Atmosphere of the Mississippi River Valley, Part II - Air. Sci. Total
Environ. 248:213-266.
Gilliom, Robert J., Jack E. Barbash, Charles G. Crawford, Pixie A. Hamilton, Jeffrey D. Martin,
Naomi Nakagaki, Lisa H. Nowell, Jonathan C. Scott, Paul E. Stackelberg, Gail P. Thelin,
and David M. Wolock. 2007. The Quality of Our Nations Waters: Pesticides in the
Nation's Streams and Ground Water, 1992-2001. Circular 1291, U. S. Department of
Interior, U. S. Geological Survey.
Hayatsu, M., M. Hirano, and T. Nagata, 1999. Involvement of Two Plasmids in the Degradation
of Carbaryl by Arthrobacter sp. Strain RC100. Appl. Environ. Microbiol., 65:1015-1019.
Hayes, M. P. and M. R. Jennings. 1988. Habitat correlates of distribution of the California red-
legged frog {Rana aurora draytonii) and the foothill yellow-legged frog {Rana boy Hi):
Implications for management. Pp. 144-158. In Proceedings of the symposium on the
management of amphibians, reptiles, and small mammals in North America. R. Sarzo,
K.E. Severson, and D.R. Patton, (technical coordinators). USDA Forest Service General
Technical Report RM-166.
Hayes, M.P. and M. M. Miyamoto. 1984. Biochemical, behavioral and body size differences between
Rana aurora aurora and R. a. draytonii. Copeia 1984(4): 1018-22.
Page 155 of 160
-------
Hayes M. P., and Tennant. 1985. Diet and feeding behavior of the California red-legged frog. The
Southwestern Naturalist 30(4): 601-605.
Hoerger, F. and E. E. Kenaga, 1972. Pesticide Residues on Plants: Correlation of Representative
Data as a Basis for Estimation of their Magnitude in the Environment. In F. Coulston and
F. Korte, eds., Environmental Quality and Safety: Chemistry, Toxicology, and
Technology, Georg Thieme Publ., Stuttgart, West Germany, pp. 9-28.
Jennings, M. R. and M. P. Hayes. 1985. Pre-1900 overharvest of California red-legged frogs (Rana
aurora draytonii): The inducement for bullfrog (Rana catesbeiana) introduction. Herpetological
Review 31(1): 94-103.
Jennings, M. R. and M. P. Hayes. 1994. Amphibian and reptile species of special concern in California.
Report prepared for the California Department of Fish and Game, Inland Fisheries Division,
Rancho Cordova, California. 255 pp.
Jones, R. David. 2003. Revised Estimate of Carbaryl Concentrations in Aquatic Environments.
Internal EPA Memorandum to Tony Britten, dated March 10, 2003. D288467.
Jones, R. David, 2003b. Review of "Estimation of Foliar Dissipation Half-life of CarbaryF
Submitted by Bayer Crop Science in Support of Their Response to Comments on the
EFED. Internal EPA Memorandum to Tony Britten, dated April 16, 2003. D288376.
Karns, J. S., W. W. Mulbry, J. O. Nelson and P. C. Kearney, 1986. Metabolism on Carbofuran
by a Pure Bacterial Culture. Pestic. Biochem. Physiol., 25:211-217.
Kupferberg, S. J., J. C. Marks and M. E. Power. 1994. Effects of variation in natural algal and detrital
diets on larval anuran (Hyla regilla) life-history traits. Copeia 1994:446-457
Kupferberg, S. 1997. Facilitation of periphyton production by tadpole grazing:
Functional differences between species. Freshwater Biology 37:427-439.
Larken, M. J. and M. J. Day, 1986. The metabolism of Carbaryl by Three Bacterial Isolates.
Pseudomonas spp. (NCIB 12042 & 12043) and Rhodococcus sp. (NCIB 12038) from
Garden Soil. J. Appl. Bacteriol., 60:233-242.
LeNoir, J.S., L.L. McConnell, G.M. Fellers, T.M. Cahill, J.N. Seiber. 1999. Summertime Transport of
Current-use pesticides from California's Central Valley to the Sierra Nevada Mountain Range,
USA. Environmental Toxicology & Chemistry 18(12): 2715-2722.
Majewski, M.S., Zamora, C., Foreman, W.T., and C.R. Kratzer. 2006. Contribution of
atmospheric deposition to pesticide loads in surface water runoff. United States
Geological Survey. Open-file Report 2005-1307. Available online at:
http://pubs.usgs.gov/of/2005/1307/.
Page 156 of 160
-------
Mineau, P., Collins, B.T., and A. Baril. 1996. On the use of scaling factors to improve
interspecies extrapolation of acute toxicity in birds. Regulatory Toxicology and
Pharmacology, 24: 24-29.
Mount, M. E. and F.W. Oehme. 1981. Residue Rev. 80:1-64.
McConnell, L.L., J.S. LeNoir, S. Datta, J.N. Seiber. 1998. Wet deposition of current-use pesticides in
the Sierra Nevada mountain range, California, USA. Environmental Toxicology & Chemistry
17(10): 1908-1916.
Rajagopal, B. S., V. R. Rao, G. Nagendrappa andN. Sethunathan, 1984. Metabolism of
Carbaryl and Carbofuran by Soil Enrichment and Bacterial Cultures. Can. J. Microbiol.
30:1458-1466.
Rathburn, G. B. 1998. Rana aurora draytonii egg predation. Herpetological Review 29(3): 165.
Reis, D. K. Habitat characteristics of California red-legged frogs (Rana aurora draytonii): Ecological
differences between eggs, tadpoles, and adults in a coastal brackish and freshwater system. M.S.
Thesis. San Jose State University. 58 pp.
Schomburg, C. J., D. E. Glotfelty, and J. N. Seiber, 1991. Pesticide occurrence and distribution
in fog collected near Monterey California. Environ. Sci. Technol. 25:155-160.
Seale, D.B. and N. Beckvar. 1980. The comparative ability of anuran larvae (genera: Hyla, Bufo
and Rana) to ingest suspended blue-green algae. Copeia 1980:495-503.
Suntio, L.R., et al. 1988. Rev. Environ. Contam. Toxicol., 103:1-59.
Sparling, D. W., G. M. Fellers, L. L. McConnell. 2001. Pesticides and amphibian population
declines in California, USA. Environmental Toxicology & Chemistry 20(7): 1591-1595.
Teske, Milton E., and Thomas B. Curbishley. 2003. AgDisp version 8.07 Users Manual. USDA
Forest Service, Morgantown, WV.
Turner, L. 2003. Effects Determination for Carbaryl for Pacific Anadromous Salmonids. Letter
(dated April 1, 2003) from Larry Turner to Arthur-Jean Williams, Chief, Environmental
Field Branch, Field and External Affairs Division
http://www.epa.gov/oppfeadl/endanger/litstatus/effects/carbaryl-memo.pdf
U.S. Environmental Protection Agency (U.S. EPA). 1998. Guidance for Ecological Risk
Assessment. Risk Assessment Forum. EPA/630/R-95/002F, April 1998.
US EPA. 2003. Environmental Fate and Ecological Risk Assessment for the Reregistration of
Carbaryl. Office of Pesticide Programs, United States Environmental Protection Agency,
Washington, DC.
Page 157 of 160
-------
USEPA. 2004. Overview of the Ecological Risk Assessment Process in the Office of Pesticide
Programs. Office of Prevention, Pesticides, and Toxic Substances. Office of Pesticide Programs.
Washington, D.C. January 23, 2004.
USEPA 2004b. Interim Reregistration Eligibility Decision Document for Carbaryl.
http: //www .epa. gov/oppsrrd 1 /REDs/carbarvl ired .pdf
US EPA. 2005. Response to Phase 5 Comments on the Interim Reregistration Eligibility Decision
(IRED) Document for Carbaryl. Internal EPA memorandum from R. David Jones and Thomas
Steeger to Anthony Britten. Document No. D291466.
USEPA. 2006. Organophosphate Cumulative Risk Assessment: 2006 Update. United States
Environmental Protection Agency, Office of Pesticide Programs.
http://www.epa.gov/pesticides/cumulative/2006-op/op_cra_main.pdf
USEPA. 2007. Ecological Risk Assessment for Current and Proposed Residential and Crop Uses
of Fipronil (PC Code 129121) D331595.
USEPA. 2007b. Revised NMC Cumulative Risk Assessment. Appendix HE. Drinking Water
Assessment. United States Environmental Protection Agency, Washington, DC.
U.S. Fish and Wildlife Service (USFWS). 1996. Endangered and threatened wildlife and plants:
determination of threatened status for the California red-legged frog. Federal Register
61(101):25813-25833.
USFWS. 1989. Final Biological Opinion in Response to U. S. Environmental Protection Agency's
September 30, 1988, Request for Consultation on Their Pesticide Labeling Program. U. S.
Department of Interior, Fish and Wildlife Service (EHC/BFA79-89-1).
USFWS. 2002. Recovery Plan for the California Red-legged Frog (Rana aurora draytonii). Region 1,
USFWS, Portland, Oregon, (http://ecos.fws.gov/doc/recoverv plans/2002/020528.pdf)
USFWS. 2006. Endangered and threatened wildlife and plants: determination of critical habitat for the
California red-legged frog. 71 FR 19244-19346.
USFWS. Website accessed: 30 December 2006.
http://www.fws.gov/endangered/features/rl frog/rlfrog.html#where
U.S. Fish and Wildlife Service (USFWS) and National Marine Fisheries Service (NMFS). 1998.
Endangered Species Consultation Handbook: Procedures for Conducting Consultation and
Conference Activities Under Section 7 of the Endangered Species Act. Final Draft. March 1998.
USFWS/NMFS. 2004. 50 CFR Part 402. Joint Counterpart Endangered Species Act Section 7
Consultation Regulations; Final Rule. FR 47732-47762.
U.S. Geological Survey. 2007. National water quality assessment program. Accessed 3 May
2007. http://water.usgs.gov/nawqa/.
Page 158 of 160
-------
Waite, D. T., R. Grover, N.D. Westcott, D.G. Irvine, L.A. Kerr and H. Sommerstad, 1995.
Atmospheric Deposition of Pesticides in a Small Southern Saskatchewan Watershed.
Environ. Toxicol, andChem., 14:1171-1175.
Walters, J.; Goh, K.S.; Li, L.; Feng, H.; Hernandez, J.; White, J., 2003, Environmental
Monitoring of Carbaryl Applied in Urban Areas to Control the Glassy-winged
Sharpshooter in California, Environmental Monitoring and Assessment, Vol. 83, No. 3,
March 2003, pp. 265 - 280.
Wassersug, R. 1984. Why tadpoles love fast food. Natural History 4/84.
Williams, S. and W. Hogarth. 2004 U. S. Fish and Wild Service and National Marine
Fisheries Service Evaluation of an Approach to Assessing the Ecological Risks of
Pesticide Products Developed by the Environmental Protection Agency. Letter (dated
January 26, 2004) to Susan B. Hazen, Principal Deputy Assistant Administrator, U. S.
Environmental Protection Agency.
Windholz M., S. Budavari, R. Blumetti, and E. Otterbein. 1976. The Merck Index: an
Encyclopedia of Chemicals, Drugs and Biologicals, 9th edn. Rahway, NJ, USA.
Wolfe, N. L., R. G. Zepp and D. F. Paris, 1978. Carbaryl, Propham and Chlorpropham: A
Comparison of the Rates of Hydrolysis and Photolysis with the Rate of Biolysis. Water
Research, 12:565-571.
Documents submitted for pesticide registration
MRID 00163847. Khasawinah, A. 1977. Hydrolysis of Carbaryl in Aqueous Buffer Solutions:
Project No. 111A12. Unpublished study prepared by Union Carbide Corp. in cooperation
with International Research and Development Corp. 23 p.
MRID 41982603. Das, Y. 1990. Photodegradation of l-Naphthyl-14C-Carbaryl in Aqueous
Solution Buffered at pH 5 Under Artificial Sunlight: Lab Project Number: 90060.
Unpublished study prepared by Innovative Scientific Services, Inc. 101 p.
MRID 41982605. Norris, F. 1991. A Terrestrial Field Soil Dissipation Study with Carbaryl: Lab
Project Number: EC-89-080: R088-076: R107-038. Unpublished study prepared by
Rhone-Poulenc, A&L Eastern Agricultural Labs and A&L Western Agricultural Labs.
250 p.
MRID 42785101. Miller, N. 1993. Metabolism of 14C-Carbaryl under Aerobic Soil Conditions:
Lab Project Number: EC-90-124. Unpublished study prepared by Rhone-Poulenc Ag Co.
in cooperation with Cook College, Center for Advanced Food Tech. 186 p.
Page 159 of 160
-------
MRID 42785102. Miller, N. 1993. Metabolism of 14C-Carbaryl under Anaerobic Aquatic Soil
Conditions: Lab Project Number: EC-90-125. Unpublished study prepared by Rhone-
Poulenc Ag Co. in cooperation with Cook College, Center for Advanced Food Tech. 260
P-
MRID 43143401. Misra, B. 1994. Aerobic Aquatic Metabolism of 14C-Carbaryl: Final Report:
Lab Project Number: ME/9200153: EC/92/227. Unpublished study prepared by
Pittsburgh Environmental Research Lab., Inc. 125 p.
MRID 43259301. Skinner, W. 1994. Soil Adsorption/Desorption of 14C-Carbaryl by the Batch
Equilibrium Method: Lab Project Number: 446W: 446W-1. Unpublished study prepared
by PTRL West Inc. 113 p.
MRID 43263001. Chancey, E. 1994. An Aquatic Field Dissipation Study with Carbaryl: Lab
Project Number: 930104: 44330: EC-92-186. Unpublished study prepared by Rhone-
Poulenc Ag Co.; CYAL, Inc.; South Texas Ag Research, Inc and Agvise, Inc. 436 p.
MRID 43320701. Skinner, W. 1994. Aged Leaching of 14C-Carbaryl in Four Soils: Lab Project
Number: 447W: 447W/1: EC/93/251. Unpublished study prepared by PTRL West, Inc.
147 p.
MRID 43439801. Norris, F. 1994. A Forestry Dissipation Study with Carbaryl: Lab Project
Number: 44555: US93S01R. Unpublished study prepared by Rhone-Poulenc Ag Co.;
Collins Agricultural Consultants, Inc.; and Colorado Analytical Research & Development
Corp. 976 p.
MRID 44759301. Carpenter, M. 1990. Hydrolysis of 14C-Carbaryl in Aqueous Solutions
Buffered at pH 5, 7, and 9: Carbaryl Insecticide: Lab Project Number: 38380.
Unpublished study prepared by Analytical Bio-Chemistry Laboratories, Inc. 83 p.
MRID 45784807. Christ, M. and J. Abedi. 2002. Effect on Vegetative Vigor of Non-Target
Terrestrial Plants (Tier I): Sevin XLR Plus (Carbaryl) Soluble Concentrate: 44.35% w/w:
Lab Project Number: 01YS32645: B003692. Unpublished study prepared by Aventis
CropScience. 71 p.
MRID 45860501. Holmsen, Jeffrey. 2003. Estimation of the Foliar Dissipation Half-life of
Carbaryl. Umpublished study submitted by Bayer CropScience Research Triangle Park,
NC. Bayer's Study Identification Number is 606YS.
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