sr^
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Risks of Naled Use to Federally Threatened
California Red Legged Frog
(Rana aurora draytonii)
Pesticide Effects Determination
Environmental Fate and Effects Division
Office of Pesticide Programs
Washington, D.C. 20460
FEBRUARY 19, 2008
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Primary Authors
Jonathan Angier, PhD, Environmental Scientist
Carolyn Hammer, Environmental Scientist
Environmental Risk Branch II
Environmental Fate and Effects Division (7507C)
Secondary Review
Donna Randall, Senior Effects Scientist
Nelson Thurman, Senior Fate Scientist
Environmental Risk Branch II
Environmental Fate and Effects Division (7507P)
Dana Spatz, Acting Branch Chief,
Environmental Risk Branch II
Environmental Fate and Effects Division (7507P)
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Table of Contents
Table of Contents ii
List of Tables v
List of Figures vii
1.0 Executive Summary 8
2.0 Problem Formulation 16
2.1 Purpose 16
2.2 Scope 18
2.3 Previous Assessments 22
2.4 Stressor Source and Distribution 23
2.4.1 Environmental Fate Assessment 24
2.4.2 Environmental Transport Assessment 25
2.4.3 Pesticidal Mechanism of Action 27
2.4.4 Use Characterization 27
2.5 Assessed Species 35
2.5.1 Distribution 35
2.5.2 Reproducti on 41
2.5.3 Diet 41
2.5.4 Habitat 42
2.6 Designated Critical Habitat 43
2.7 Action Area 45
2.8 Assessment Endpoints and Measures of Ecological Effect 48
2.8.1 Assessment Endpoints for the CRLF 48
2.8.2 Assessment Endpoints for Designated Critical Habitat 51
2.9 Conceptual Model 54
2.9.1 Risk Hypotheses 54
2.9.2 Diagram 55
2.10 Analysis Plan 59
2.10.1 Exposure Analysis 59
2.10.2 Effects Analysis 61
2.10.3 Integration of Exposure and Effects 62
3.0 Exposure Assessment 64
3.1 Label Application Rates and Intervals 64
3.2 Aquatic Exposure Assessment 67
3.2.1 Conceptual Model of Exposure 67
3.2.2 Existing Monitoring Data 67
3.2.3 Modeling Approach 68
3.2.3.1 Model Inputs 69
3.2.3.2 Results 70
3.2.4 Additional Modeling Exercises Used to Characterize Potential Exposures . 76
3.2.4.1 Residential Uses (Impact of overspray and Impervious Surfaces) 76
3.2.4.2 Comparison of Modeled EECs with Available Monitoring Data 76
3.2.5 Modeling with Typical Usage Information 76
3.2.6 Summary of Modeling vs. Monitoring Data 76
3.3 Terrestrial Exposure 76
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3.3.1 Terrestrial Animal Exposure Assessment 76
3.4 Spray Drift Modeling 82
4.0 Effects Assessment 84
4.1 Evaluation of Naled and DDVP Aquatic Ecotoxicity Studies 86
4.1.1 Toxicity to Freshwater Fish 87
4.1.1.1 Freshwater Fish: Acute Exposure (Mortality) Studies 87
4.1.1.2 Freshwater Fish: Chronic Exposure (Early Life Stage and Reproduction)
Studies 89
4.1.2 Toxicity to Freshwater Invertebrates 91
4.1.2.1 Freshwater Invertebrates: Acute Exposure (Mortality) Studies 91
4.1.2.2 Freshwater Invertebrates: Chronic Exposure (Reproduction) Studies 92
4.1.3 Toxicity to Aquatic Plants 92
4.1.4 Probit Slope Information for Fish and Aquatic Invertebrates 94
4.2 Evaluation of Terrestrial Ecotoxicity Studies 94
4.2.1 Toxicity to Birds 96
4.2.1.1 Birds: Acute Exposure (Mortality) Studies 96
4.2.1.2 Birds: Subacute Dietary Exposure (Mortality and Growth) Studies 97
4.2.1.3 Birds: Chronic Exposure (Reproduction) Studies 98
4.2.2 Toxicity to Mammals 99
4.2.2.1 Mammals: Acute Exposure (Mortality) Studies 100
4.2.2.2 Mammals: Chronic Exposure (Reproduction) Studies 101
4.2.2.3 Mammals: Sublethal Effects and Open Literature Data 101
4.2.3 Toxicity to Terrestrial Plants 102
4.2.4 Toxicity to Terrestrial Insects 103
4.2.4.1 Insects: Acute Exposure (Mortality) Studies 103
4.3 Use of Probit Slope Response Relationship to Provide Information on the
Endangered Species Levels of Concern 104
4.4 Incident Database Review 105
4.4.1 Insects 105
4.4.2 Birds 105
4.4.3 Plants 106
4.4.4 Fish 106
4.5 Uncertainties Related to the Use of Incident Information from the Ecological
Incident Information System 107
5.0 Risk Characterization 109
5.1 Risk Estimation 109
5.1.1 Direct Effects to the CRLF 109
5.1.1.1 Aquatic-Phase CRLF 109
5.1.1.2 Terrestrial-Phase CRLF 114
5.1.2 Indirect Effects 116
5.1.2.1 Evaluation of Potential Indirect Effects via Reduction in Food Items ... 116
5.1.2.2 Evaluation of Potential Indirect Effects via Reduction in Habitat and/or
Primary Productivity (Freshwater Aquatic Plants) 123
5.1.2.3 Evaluation of Potential Indirect Effects via Reduction in Terrestrial Plant
Community (Riparian Habitat) 123
5.1.3 Modification to Critical Habitat 123
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5.2 Risk Description 123
5.2.1 Direct Effects to the CRI.I 124
5.2.2 Indirect Effects via Reduction in Food Items 132
5.2.3 Indirect Effects via Reduction in Habitat and/or Primary Productivity
(Freshwater Aquatic Plants) 132
5.2.4 Indirect Effects via Alteration in Terrestrial Plant Community (Riparian
Habitat) 132
5.2.4.1 Sensitivity of Forested Riparian Zones to Naled 132
5.2.4.2 Sediment Loading in the Watershed and the Potential for Naled to Affect
the CRLF via Effects on Riparian Vegetation 132
5.2.5 Modification to Critical Habitat 133
6.0 Uncertainties 136
6.1 Exposure Assessment Uncertainties 136
6.1.1 Modeling Assumptions 137
6.1.2 Impact of Vegetative Setbacks on Runoff 138
6.1.3 PRZM Modeling Inputs and predicted Aquatic Concentrations 139
6.2 Effects Assessment Uncertainties 139
6.2.1 Age Class and Sensitivity of Effects Thresholds 139
6.2.2 Extrapolation of Long-term Environmental Effects from Short-term
Laboratory Tests 140
6.2.3 Use of Threshold Concentrations for Community-Level Endpoints 140
6.3 Assumptions Associated with the Acute LOCs 140
7.0 References 141
APPENDIX A. Ecological Effects Data Submitted
APPENDIX B. PRZM Output Files
APPENDIX C. TREX and THERPS Output
APPENDIX D. Aquatic Risk Quotients Naled and DDVP
APPENDIX E. Naled Fate Properties
APPENDIX F. DDVP Fate Properties
APPENDIX G. Assessing Terrestrial Invertebrate Exposure to Pesticides
APPENDIX H. Naled ECOTOX Bibliography
APPENDIX I. LOC Tables
Attachments
Attachment 1. Life History of the CRLF
Attachment 2. Baseline Status and Cumulative Effects
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List of Tables
Table 1. Current Naled FIFRA Product Registrations Relevant for CRLF 18
Table 2 Physical/Chemical Properties of Naled 26
Table 3 Physical/Chemical Properties of DDVP 26
Table 4. Maximum Naled Use Rates and Management Practices by Crop Based on
Current Labels 28
Table 5. Total Pounds Applied in Each County for the Years 2002-2005 32
Table 6. Reported Uses and Annual Pounds (a.i.) Applied for 2002-2005 in California 33
Table 7. California Red-legged Frog Recovery Units with Overlapping Core Areas and
Designated Critical Habitat 37
Table 8. Summary of Assessment Endpoints and Measures of Ecological Effects for
Direct and Indirect Effects of Naled on the California Red-legged Frog 49
Table 9. Summary of Assessment Endpoints and Measures of Ecological Effect for
Primary Constituent Elements of Designated Critical Habitat 53
Table 10. Modeled Naled Uses 65
Table 11. Modeling Information for Runs Conducted with AgDrift and RICE Model. . 66
Table 12. PRZM-EXAMS Input Parameters for Naled (total toxic residues) 69
Table 13 Buffer Widths for Naled Uses, and Spray Drift Calculated from AgDrift 70
Table 14. Results from PRZM Model Runs 71
Table 15. Results from Other (non-PRZM) Model Runs 75
Table 16. Input Parameters for Foliar Applications Used to Derive Terrestrial EECs for
Naled with T-REX, Application Scenarios Used in TREX to get a Baseline
Risk Value for Each Use 77
Table 17. Upper-bound Kenega Nomogram EECs (ppm) for Dietary- and Dose-based
Exposures of the CRLF and its Prey to Naled 79
Table 18. Naled EECs (ppm) for Indirect Effects to the Terrestrial-Phase CRLF via
Effects to Terrestrial Invertebrate Prey Items 80
Table 19. DDVP EECs (ppm) for Indirect Effects to the Terrestrial-Phase CRLF via
Effects to Terrestrial Invertebrate Prey Items 80
Table 20. Mammalian EECs (ppm), as Modeled by T-REX to Assess Potential for
Indirect Effects to CRLF 81
Table 21. TerrPlant Inputs and Resulting EECs (lbs a.i./A) for Plants Inhabiting Dry and
Semi-aquatic Areas Exposed to naled via Runoff and Drift 82
Table 22. Selected endpoints (naled or DDVP) for direct (freshwater fish) and indirect
(aquatic invertebrates) effects to aquatic phase CRLF 86
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Table 23. Calculation methods for determination of chronic aquatic early life stage
toxicity values 90
Table 24. Aquatic Plants 93
Table 25. Selected toxicity endpoints for terrestrial organisms, including avian,
mammalian and invertebrates 95
Table 26. Acute Mammalian Toxicity for Technical Naled and DDVP 100
Table 27. Acute Aquatic RQ Values - Direct Effects to aquatic phase CRLF (PRZM). 110
Table 28. Chronic Aquatic RQ Values - Direct Effects to aquatic phase CRLF (PRZM)
113
Table 29. Avian Acute and Chronic RQ Values for Direct Effects to the Terrestrial-Phase
CRLF 115
Table 30. Aquatic Unicellular Plant RQ Values for Indirect Effects to the CRLF 116
Table 31. Acute and Chronic Aquatic Invertebrate RQ Values for Indirect Effects 118
Table 32. Acute Terrestrial Insect RQ Values for Indirect Effects to the CRLF 121
Table 33. Acute and Chronic RQ Values for Indirect effects, effects to Small Mammals
Ingesting Residues on Short Grass for Indirect Effects to the CRLF (prey)
(Modeled with T-REX) 122
Table 34 Terrestrial-Phase Amphibian Acute Dose-Based RQ Values for Direct Effects
to the CRLF from Ingestion of Residues on or in Prey Items 125
Table 35. Summary Table for Effects Determinations for Direct Effects to both Aquatic
and Terrestrial Phase CRLF 128
Table 36. Effects Determination Summary for Naled - Direct and Indirect Effects to
CRLF 133
Table 37. Effects Determination Summary for Naled-PCEs of Designated Critical
Habitat for the CRLF 134
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List of Figures
Figure 1. Naled Chemical Structure 24
Figure 2. Dichlorvos (DDVP) Chemical Structure 24
Figure 3. Recovery Unit, Core Area, Critical Habitat, and Occurrence Designations for
CRI.I 40
Figure 4. CRLF Reproductive Events by Month* 41
Figure 5. Initial area of concern, or "footprint" of potential use, for naled 47
Figure 6. Conceptual Model for Pesticide Effects on Aquatic Phase of the Red-Legged
Frog 57
Figure 7. Conceptual Model for Pesticide Effects on Terrestrial Phase of Red-Legged
Frog 57
Figure 8. Conceptual Model for Pesticide Effects on Aquatic Components of Red-Legged
Frog Critical Habitat 58
Figure 9. Conceptual Model for Pesticide Effects on Terrestrial Components of Red-
Legged Frog Critical Habitat 58
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1.0 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 naled use on agricultural and non-agricultural sites. In
addition, this assessment evaluates whether these actions can be expected to result in
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.
Naled is an organophosphate insecticide that acts as a potent cholinesterase (ChE)
inhibitor. Numerous application methods are employed for a vast array of naled uses.
These uses include crop and non-crop applications, such as: orchard uses, row crop uses,
vineyard uses, bedding plants uses, forestry uses, farming uses, residential uses, and
many others. Application methods include: aerial spray, ground spray, hand spray,
airblast, mist/fogging, and bait stations. Aerial and ground spray methods may use ultra-
low volume (ULV) nozzles which suspend the product in the air for a longer duration, in
order to intercept flying insects. Naled can be applied indoors, around structures, on
agricultural fields, in wetlands, urban areas, as an ambient atmospheric suspension -
essentially in any form anywhere, at any time of the year. Thus, there are no areas within
the state of California where naled may not be used, so potential exposure to insects and
other invertebrates, fish, and other wildlife exists statewide. Certain application
methods/usages (aerial spray or ground spray) are expected to result in greater and more
extensive (high-end) exposure than others (indoor uses, hand spray around structural
perimeters, bait stations) because of higher application rates and more widespread
applications. All outdoor uses are considered in this assessment; indoor uses are deemed
to have no effect on the CRLF.
Dichlorvos (DDVP) is a major toxic degredate of naled. This assessment estimates risk
from exposure to naled, and its degredate DDVP by evaluating "total naled residues of
concern" (naled plus DDVP). Because DDVP is also an active ingredient in other
pesticide products, and is also a degredate of pesticides other than naled, the presence of
DDVP in the environment in monitoring studies cannot be used as evidence of naled use.
The highest reported uses of naled in California from 2002-2005 were: Cotton
(representing about 38% of the total applied), Broccoli (~ 12%), Public Health (~ 11%),
Strawberry (—10%) and Sugarbeet (6%); all other uses individually comprised less than
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5% of total naled applied. During this period (2002-2005), at least 40 counties in
California reported naled use; however, since there are no specific labeled use restrictions
that would preclude naled use in any county, and given the variety of labeled usese, there
is no reason to assume that naled is not used in any of these counties.
Most widespread applications of naled are in (aerial or ground) spray form, typically with
ultrafine droplets or as mist or ULV. Degradation/dissipation of naled is rapid following
application. Initially much of the parent degrades to another toxic form, DDVP;
however, DDVP degrades rapidly as well. Total naled residues of concern degrade
rapidly under a wide variety of conditions (and mechanisms), so persistence is unlikely in
nearly any naturally-occurring environment. Potential exposure is instead determined
largely by spatial and temporal proximity to application sites, with long-range transport
an unlikely occurrence.
Atmospheric background levels (samples taken prior to application) of naled have been
detected; likely the result of other uses in the area, or drift from a neighboring airshed
with recent aerial use. Air samples obtained immediately after local spraying predictably
have much higher naled (and DDVP) concentrations. Deposition of naled residues in
nearby non-target environments is possible, but rapid dissipation makes it unlikely that
re-mobilization of residues would become a factor. However, spray drift re-deposition
directly onto water (or other sensitive non-target areas) could present substantial short-
term exposure. And while potential exposure to residues (naled and DDVP) resulting
from naled use is likely to be relatively brief, it may become magnified and extended
during high-use periods (especially if there are multiple uses and/or DDVP applications
in the same area). The potential for year-round, multiple, frequent uses indicate the
possibility of recurrent high-exposure episodes in certain areas. Thus, there is a 'window
of vulnerability' for naled exposure that corresponds with spatial and (especially)
temporal proximity to application sites; significant exposure events are probably of short
duration (during and soon after application) because of the transitory nature of naled (and
DDVP).
The very fine or finer droplet sizes typical of many naled applications (especially aerial)
make naled (and DDVP) potentially very mobile in the atmosphere -
degradation/dissipation/dilution are the primary limiting factors to off-site atmospheric
naled movement. Although moving air masses containing suspended fine naled spray
could conceivably transport naled residues far from application sites, because of the non-
persistence of naled residues any such exposure is likely limited to 1-2 days following
application. Thus, substantial long-range atmospheric transport is unlikely. However,
the impact of different uses occurring simultaneously within the same region could
potentially result in more extended (local) exposure durations.
Since CRLFs exist within aquatic and terrestrial habitats, exposure of the CRLF, its prey
and habitat primary constituent elements to naled are assessed separately for the two
habitats. Tier-II aquatic exposure models are used to estimate total naled residues in
aquatic habitats resulting from runoff and spray drift for different high-end application
rates and uses. Peak model-estimated aquatic environmental concentrations resulting
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from naled uses range from 0.02 to 32.8 micrograms per liter (|ig/L). Most of the aquatic
model scenarios (representations of a particular set of meteorological and hydrological
conditions for a given geographical area) yielded estimated environmental concentration
(EEC) values within similar ranges. EECs were consistently related to amounts applied
in a single application rather than total seasonal application; reflecting the transitory
nature of this chemical. Greater variations were seen as a result of differences in single
application amounts (maximum versus minimum) for a given use than were observed
between many of the modeled uses. Where both ground and aerial spray applications
were run (e.g., Walnut, Cabbage, Celery, Hops), aerial applications had consistently
higher EECs; other application methods (e.g., airblast) yielded somewhat lower EECs
than either aerial or ground spray.
The exposure estimates for vulnerable sites 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 (CDPR). There were no measurable detections of naled in either the
NAWQA or CDPR databases. A single detection of the degredate DDVP was found in
the CDPR database; however, since DDVP is used as the primary active ingredient in
other products, and can also be formed as a degredate of other registered pesticides,
DDVP detection alone cannot be used as evidence of naled use.
To estimate naled residues in on-field dietary items and exposure to the terrestrial-phase
CRLF, and its potential prey resulting from a range of naled application rates, the T-REX
model was used. Because T-REX does not track total toxic residues, two separate T-
REX runs were executed for each application scenario to capture the range in possible
naled and DDVP residues: one run was conducted at 100% of the application rate
(assuming 100% residue as naled), and one run at 20% of the application rate
(representing the maximum possible DDVP residue level from naled). For each run, the
resulting EECs were compared to their respective toxicity endpoints to generate estimates
of risk (i.e., 100% application run compared to naled toxicity, and the 20% application
run compared to DDVP toxicity). The RQ values generated from each model run were
not summed but rather used to bound the range of possible RQ values.
The T-HERPS model was used to refine dietary exposure estimates to terrestrial-phase
CRLFs, relative to screening exposure estimates based on birds in TREX. The TerrPlant
model was used to estimate naled exposures to plants in semi-aquatic and dry habitats,
resulting from run-off and spray drift.
The assessment endpoints for the CRLF include direct toxic effects on their survival,
reproduction, and growth, as well as indirect effects, such as reduction of the prey base or
modification of its habitat. Direct effects to the CRLF in the aquatic habitat are based on
toxicity information for freshwater fish, which are used as a surrogate here for aquatic-
phase amphibians. In the terrestrial habitat, direct effects are based on toxicity
information for birds, which are used here as a surrogate for terrestrial-phase amphibians.
Given that the CRLF's prey items and primary constituent elements (PCEs) of designated
critical habitat include or are dependant on the availability of freshwater aquatic
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invertebrates and aquatic plants, toxicity information for these taxonomic groups is also
discussed. In the terrestrial habitat, indirect effects to the CRLF and effects to PCEs of
designated critical habitat due to depletion of prey are assessed by considering effects to
terrestrial insects, small terrestrial mammals, and frogs. Indirect effects and effects to
PCEs of critical habitat due to modification of the terrestrial flora are characterized by
available data for terrestrial monocots and dicots.
Based on the available data, naled is classified as highly toxic to freshwater fish and very
highly toxic to freshwater invertebrates. As fish are used here as a surrogate for aquatic-
phase amphibians the classification for freshwater fish is assumed to also apply to
amphibians. Naled is classified as slightly toxic to birds on a sub-acute, dietary basis and
as moderately to highly toxic on an acute oral basis. As birds are used as surrogates here
for reptiles and terrestrial-phase amphibians the classification for birds is assumed to
apply to these taxa also. Naled is classified as highly toxic to insects and moderately
toxic to mammals, on an acute basis. The results of aquatic plant toxicity testing found
naled toxicity to range from 25 ppb a.i. for non-vascular aquatic plants up to 1,800 ppb
for vascular aquatic plants. There are no submitted terrestrial plant toxicity data for
naled. Plant toxicity data for naled and DDVP in the open literature are limited and
related to superficial plant damage.
Risk quotients (RQs), which are ratios of exposure estimates to appropriate toxicity
measurement endpoints, are used as estimates of potential risk in this assessment. Acute
and chronic RQs are compared to the Agency's levels of concern (LOCs) to identify
instances where naled use within the action area has the potential to affect the CRLF via
direct toxicity or indirectly based on effects to its food supply {i.e., freshwater
invertebrates, algae, fish, frogs, terrestrial invertebrates, and mammals) or habitat {i.e.,
aquatic plants and terrestrial upland and riparian vegetation), and the potential to affect
PCEs of its designated critical habitat. When a RQ is below its respective LOC, the
pesticide is determined to have "no effect" and where a RQ exceeds its respective LOC, a
potential to cause effects is identified. One or more exceedences is used to draw a
conclusion of "may affect." If a determination is made that naled use within the action
area "may affect" the CRLF and its designated critical habitat, additional information is
considered to refine the potential for exposure and effects, and the best available
information is used to distinguish those actions that "may affect, but are not likely to
adversely affect" (NLAA) from those actions that are "likely to adversely affect" (LAA)
the CRLF and its critical habitat.
Effects determinations for the assessment are summarized below:
• "No Effect" determination is made for the CRLF or its designated critical habitat
for indoor uses of naled as they will not result in exposure to the CRLF or its
designated critical habitat.
• "May effect but NLAA" for spot treatments (e.g., utility poles, refuse sites,
structural perimeters), and bait stations, because while there may be
exposure/effects at the sites of application, these sites are discrete and very
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limited in extent. No significant impact on CRLFs, their prey, or habitat is
expected.
• A "Likely to Adversely Affect" (LAA) determination is made for all other uses
due primarily to indirect effects to the aquatic and terrestrial invertebrate prey
base, and the mammalian and amphibian prey base. Depending on the use there
may be additional direct effects to the aquatic- and terrestrial-phase CRLF.
Modification to designated critical habitat from theses uses is also expected
primarily due to changes in food resources for juvenile and adult CRLFs (aquatic
and terrestrial invertebrates, small mammals, and amphibians). Insignificant
effects to terrestrial and aquatic plants of designated critical habitat are expected.
A summary of the risk conclusions and effects determinations for the CRLF and its
critical habitat is presented in Tables 1.1 and 1.2, respectively. Further details on the
results of the effects determination are included as part of the Risk Description in Section
5.2.
Table 1.1 Effects Determination Summary for Naled - Direct and Indirect Effects to
CRLF
Assessment Endpoint
Effects
Determination
Basis For Determination
Aquatic Phase
(eggs, larvae, tadpoles, juveniles, and adults)
Survival, growth, and
reproduction of CRLF
individuals via direct effects
on aquatic phases
LAA
Numerous uses are likely to adversely affect CRLF via
direct effects. For details, see Table 35 in the main
body of the document.
Survival, growth, and
reproduction of CRLF
individuals via effects to food
supply (i.e., freshwater
invertebrates, non-vascular
plants)
LAA
Numerous uses are likely to adversely affect CRLF via
effects to food supply, especially freshwater
invertebrates. Although naled and DDVP are not long
lived in the environment, if there was a massive aquatic
invertebrate kill the population would not likely
recover in sufficient time for CRLF individuals
dependent on these food sources to recover. For
details, see Table 35 of indirect effect in the main
body of the document.
Survival, growth, and
reproduction of CRLF
individuals via indirect effects
on habitat, cover, and/or
primary productivity (i.e.,
aquatic plant community)
NLAA
None of the uses are likely to adversely affect CRLF
via effects to riparian vegetation.
Neither upland nor aquatic vascular plants are expected
to be significantly impacted by naled use.
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.
NE
Neither upland nor aquatic vascular plants are expected
to be significantly impacted by naled use.
Terrestrial Phase
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Assessment Endpoint
Effects
Determination
Basis For Determination
(Juveniles and adults)
Survival, growth, and
reproduction of CRLF
individuals via direct effects
on terrestrial phase adults and
juveniles
LAA
Numerous uses are likely to adversely affect the
terrestrial phase CRLF via direct effects. For details,
see Table 35 in the main body of the doument
Survival, growth, and
reproduction of CRLF
individuals via effects on prey
(i.e., terrestrial invertebrates,
small terrestrial mammals and
terrestrial phase amphibians)
LAA
Numerous uses are likely to adversely affect CRLF via
effects on many prey items of the frog's diet.
Survival, growth, and
reproduction of CRLF
individuals via indirect effects
on habitat (i.e., riparian
vegetation)
NLAA
Few to none of the uses are likely to adversely affect
CRLF via indirect effects on habitat. Neither aquatic
nor terrestrial plants are expected to be significantly
impacted by naled use.
Table 1.2. Effects Determination Summary forNaled-PCEs of Designated Critical
Habitat for the CRLF
Assessment Endpoint
Effects
Determination
Basis For Determination
Aquatic Phase PCEs
(Aquatic Breeding Habitat and Aquatic Non-Breeding Habitat)
Alteration of channel/pond
morphology or geometry and/or
increase in sediment deposition
within the stream channel or pond:
aquatic habitat (including riparian
vegetation) provides for shelter,
foraging, predator avoidance, and
aquatic dispersal for juvenile and
adult CRLFs.
NE
No effects expected
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.
NE
No effects expected
Alteration of other chemical
characteristics necessary for normal
growth and viability of CRLFs and
their food source.
NE
No effects expected
Reduction and/or modification of
aquatic-based food sources for pre-
metamorphs (e.g., algae)
HM Not Likely
There are few to no uses that may alter the
availability of algal food sources. These uses
are not likely to occur in simultaneity with
the habitats of the pre-metamorphs and
therefore the effect is discountable.
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Assessment Endpoint
Effects
Determination
Basis For Determination
Terrestrial Phase PCEs
(Upland Habitat and Dispersal Habitat)
Elimination and/or disturbance of
upland habitat; ability of habitat to
support food source of CRLFs:
Upland areas within 200 ft of the
edge of the riparian vegetation or
dripline surrounding aquatic and
riparian habitat that are comprised of
grasslands, woodlands, and/or
wetland/riparian plant species that
provides the CRLF shelter, forage,
and predator avoidance
HM Not Likely*
(except for direct
application to
swamps under hot
and humid
conditions)
Due to lack of effects data for plants, effects
cannot be dismissed as No Effect. Toxic
effects to plants have been observed but the
expected environmental concentrations,
combined with the high uncertainty
associated with the biological significance of
observed phytotoxic results in discountable
effects for nearly all uses.
However, uses on swamps are an exception.
Typical use for swamps is for mosquito
control. The same environmental conditions
that lead to mosquito outbreaks are also
associated with plant damage. Based on
information contained in incident reports and
label warnings, effects to upland plants are
not expected under most conditions, with the
exception of hot and humid areas, such as
uses in swamps for mosquito control.
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
HM Not Likely
Due to lack of effects data for plants, effects
cannot be dismissed as No Effect. However,
based on information contained in incident
reports and label warnings, effects to upland
plants are not expected under most
conditions, with the exception of hot and
humid areas, such as uses in swamps for
mosquito control.
Reduction and/or modification of
food sources for terrestrial phase
juveniles and adults
HM
Based on likely effects to small mammals,
amphibians, and terrestrial invertebrates
reduction in food sources is expected.
Alteration of chemical characteristics
necessary for normal growth and
viability of juvenile and adult CRLFs
and their food source.
NE
No effects expected.
HM: Habitat Modification
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.
When evaluating the significance of this risk assessment's CRLF direct/indirect and
designated critical habitat 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. However, given the broad
scope of labeled uses, and since there are no areas within the state of California where
naled use is restricted, and it is not unlikely that multiple uses for (and applications of)
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naled will occur simultaneously within the same areas, there are no areas where potential
effects from naled use can be categorically discounted. Thus, there is no need to consider
such potentially mitigating effects as 'downstream dilution' or 'drift attenuation' (to areas
where naled is not used), as no region lies outside the bounds of potential naled use.
Characterizing 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 influence the recovery of prey
resources 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.
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2.0 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 is
consistent with procedures and methodology outlined in the Overview Document (U.S.
EPA 2004) and reviewed by the U.S. Fish and Wildlife Service and National Marine
Fisheries Service (USFWS/NMFS 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
naled on all registered uses. In addition, this assessment evaluates whether these actions
can be expected to result in the modification of the species' designated 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 consistent with a settlement agreement
in the case Center for Biological Diversity (CBD) us. EPA et al. (Case No. 02-1580-
JSW(JL)) settlement entered in the Federal District Court for the Northern District of
California on October 20, 2006.
In this assessment, direct and indirect effects to the CRLF and potential modification to
its designated critical habitat are evaluated in accordance with the methods described in
the Agency's Overview Document (U.S. EPA 2004). Screening level methods include
use of standard models such as PRZM-EXAMS, T-REX, TerrPlant, and AgDRIFT all of
which are described at length in the Overview Document. Additional refinements
include an analysis of California use reporting data, and the use of the T-HERPS model
to predict daily dietary intake specifically by the CRLF of naled residues in terrestrial
invertebrates and small mammal dietary items. Use of such information is consistent
with the methodology described in the Overview Document, which specifies that "the
assessment process may, on a case-by-case basis, incorporate additional methods,
models, and lines of evidence that EPA finds technically appropriate for risk management
objectives" (Section V, page 31 of U.S. EPA 2004).
In accordance with the Overview Document, provisions of the ESA, and the Services'
Endangered Species Consultation Handbook, the assessment of effects associated with
registrations of naled 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 exceedence of
Agency Levels of Concern (LOCs) used to evaluate direct or indirect effects. It is
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acknowledged that the action area for a national-level FIFRA regulatory decision
associated with a use of naled 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 use of naled in accordance with current labels:
• "No effect";
• "May affect, but not likely to adversely affect"; or
• "May affect and likely to adversely affect".
Designated critical habitat identifies specific areas that have the physical and biological
features, (known as primary constituent elements or PCEs) essential to the conservation
of the listed species. The PCEs for CRLFs 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 exceedences) 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 naled 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 naled.
If a determination is made that use of naled 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 geographical proximity of CRLF
habitat and naled use sites) and further evaluation of the potential impact of naled 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 total naled residues are expected to directly impact living organisms within the
action area (defined in Section 2.7), critical habitat analysis for naled is limited in a
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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 destroy or adversely modify critical habitat are those that
alter the PCEs and appreciably diminish the value of the habitat. Evaluation of actions
related to use of naled that may alter the PCEs of the CRLFs 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.
2.2 Scope
The end result of the EPA pesticide registration process {i.e., 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 naled in accordance with the approved product labels for
California is "the action" being assessed.
There are a total of nineteen registered products containing naled. This includes one
technical product (5481-478). Because this product is used only to formulate naled end
use products and is not registered for release to the environment, this action has no effect
on the CRLF or its critical habitat and will not be reviewed further. Of the remaining
eighteen registrations, thirteen are special local needs (SLNs) and five are Section 3
nationwide registrations; however, of the SLNs only three are registrations for use in
California. The other ten SLNs are not biologically relevant to the CRLF or its critical
habitat and are not reviewed further. Based on the three SLNs and five Section 3
registrations naled is currently registered for 87 different uses in California, which
includes both agricultural and non-agricultural uses.
Table 1 provides a complete listing of the five Section 3 end-use products and the three
SLNs registered for use in California. The table includes the formulation, the EPA
registration number, methods of application, and any relevant use restrictions.
Table 1. Current Naled FIFRA Product Registrations Relevant for CRLF
FORMULATION
Uses
USE RESTRICTIONS
Naled Technical
5481-478
For formulation of naled insecticide
products only.
Dibrom 8
Emulsive
5481-479
SLNs:
Alfalfa, almond (SLN-CA), beans,
peas, broccoli, cabbage, cauliflower,
Brussels sprouts, kale, collards,
cantaloupes, muskmelons, hops,
melons, celery, cotton (SLN-CA),
eggplant, peppers, grapes, oranges,
- Do not apply through any type of
irrigation system
- Do not apply by ground equipment within
25 ft, or by air within 150 feet, or by
airblast within 50-100 feet of lakes,
reservoirs, rivers, permanent streams,
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FORMULATION
Uses
USE RESTRICTIONS
CA000006
CA050011
Prokil Naled
Insecticide 10163-
46
lemons, grapefruit, tangerines, peaches,
safflower (CA), strawberries, sugar
beets, summer squash, Swiss chard,
walnuts, forest and shade trees,
ornamental shrubs and flowering
plants, greenhouse, vapor treatment of
roses and other ornamental plants, in
and around food processing plants,
loading docks, cull piles, refuse areas,
swamps and pastures, for reduction of
livestock pests in confined animal
feeding operations, containing dairy
and beef cattle, hogs, sheep, or horses.
For reduction of pests in rangelands.
Residential areas, municipalities, tidal
marshes, swamps, woodlands, and
agricultural areas. Livestock pastures,
including dairy cattle
marshes, or natural ponds; estuaries, and
commercial fish ponds, where wind is
blowing or gusting toward these areas.
- Do not cultivate within 10 feet of the
aquatic area so as to allow growth of a
vegetative filter strip to alleviate drift and
mitigate runoff.
Dibrom
Concentrate
5481-480
SLN: CA860005
Telephone or light poles, residential
areas, municipalities, tidal marshes,
swamps, woodlands, and agricultural
areas.
- Spray during periods when the wind
speed is between 1 and 15 mph at ground
level and when thermal activity is low.
- Do not apply when ambient temperature
is less than 50 degrees Fahrenheit.
- Do not apply when it is raining in the
treatment area.
Trumpet EC 5481-
481
Residential areas, municipalities, tidal
marshes, swamps, woodlands, and
agricultural areas.
- Spray during periods when the wind
speed is between 1 and 15 mph at ground
level and when thermal activity is low.
- Do not apply when ambient temperature
is less than 50 degrees Fahrenheit.
- Do not apply when it is raining in the
treatment area.
Fly Killer D 5481-
482
In and around dairy barns, livestock
barns, pig pens, poultry houses, feed
lots, cattle pens, garbage dumps,
outside meat packing establishments,
pens, docks, ramps, disposal areas and
cider mills. In and around food
processing plants, loading docks, cull
piles and refuse areas and cider mills.
Feed lots including dairy cattle, and
pastures including woodlands, swamps
-Do not apply directly to water, or to areas
where surface water is present or to
intertidal areas below the mean high water
mark
-Do not apply within 8 hours following
rainfall or irrigation, or in areas where
intense or sustained rainfall is forecasted to
occur within 24 hours
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Although current registrations of naled allow for use nationwide, this ecological risk
assessment and effects determination addresses currently registered uses of naled 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.
Indoor uses of naled will not result in exposure to the CRLF or its designated critical
habitat. Therefore, indoor uses1 of naled are determined to have 'Wo Effect" on the
CRLF and are not evaluated further in this assessment.
Naled Degredates:
There are several degredates of naled that are found in various amounts under different
conditions. The primary degredate of concern, DDVP, is considered to have attributes
and effects similar to parent naled, and can account for as much as 20% of applied parent
under certain conditions (MRIDs 41310702 and 42445103). Thus, DDVP degredate
residue levels are considered along with naled residue levels as 'total naled residues of
concern' in this assessment, and model results (exposure estimates) reflect the predicted
fate of both naled and DDVP resulting from naled usage. Although DDVP is a major
degredate of naled, this assessment does not evaluate the usage or impact of DDVP as a
primary active ingredient or as a degredate of other compounds. DDVP that is applied
separately as the active ingredient or degredate in other products is considered
independent of naled usage, and while DDVP may potentially be used simultaneously
(for different purposes) within the same areas as naled, this is not addressed in this risk
assessment.
Two other major degredates that form from naled are bromodichloroacetaldehyde
(BDCA) and dichloroacetic acid (DCAA). These may constitute as much as 77% and
26% of applied naled, respectively. However, the acute toxicity of these compounds
relative to naled and DDVP appears to be much lower and would therefore not add
significantly to estimates of acute risk from the use of naled. Additionally, these are not
considered likely to add to chronic risk estimates as compared to exposure from naled
and DDVP, as they degrade too rapidly to pose long-term exposure risk under likely field
conditions. Therefore, neither BDCA nor DCAA are directly considered in this
assessment. Other degredates either formed below 10% of applied naled and/or were not
considered particularly toxic compared to naled and DDVP and as such are not likely to
add significantly to risk estimates based on exposure to naled and DDVP.
Mixtures
The Agency does not routinely include, in its risk assessments, an evaluation of products
with mixtures of active ingredients, either those mixtures of multiple active ingredients in
product formulations or those in the applicator's tank. In the case of the product
formulations of active ingredients (that is, a registered product containing more than one
active ingredient), each active ingredient is subject to an individual risk assessment for
1 Indoor uses include: greenhouses and vapor treatment, indoor food processing facilities, and structural
interiors.
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regulatory decision regarding the active ingredient on a particular use site. If effects data
are available for a formulated product containing more than one active ingredient, they
may be used qualitatively or quantitatively in accordance with the Agency's Overview
Document and the Services' Evaluation Memorandum (U.S., EPA 2004; USFWS/NMFS
2004). However, there are currently no registered mixture products with naled.
Spot Treatments
The effects determination to the CRLF and its designated critical habitat is evaluated here
qualitatively for bait and other spot treatments. Spot treatments are not considered
quantitatively in this effects determination. Additionally, for reasons described in
following paragraphs, registered spot treatments are unlikely to contribute in a
meaningful way to effects or risk from other more spatially widespread uses which may
intersect in either space or time or both. Such spot treatments include outdoor baits
(roach, flies, etc.), hand-spray of structural exterior (e.g., perimeter treatments, loading
docks, refuse areas) treatments, or applications to utility poles.
Outdoor baits are contained in small vessels (mixed with sugar solution) and are unlikely
to result in direct or indirect exposure to the CRLF. Additionally, while the bait is likely
to impact both target insects (flies, roaches, etc.) and nontarget insects at the point of
treatment, effects to insect populations on a scale large enough to indirectly affect a
CRLF or its designated critical habitat are unlikely, and cannot be adequately measured
or detected. Thus, a determination of "May Effect" but NLAA is determined for these
uses as the effects are discountable.
Applications to utility poles or tree trunks entails applying very small amounts ("6 square
inches of material to each station" according to the label) at discrete spots (poles) within
large areas; total amounts applied per unit area will be very low. Since both target and
nontarget insects will be affected at treatment sites, there is a May Affect determination
for this use. However, as these uses are unlikely to result in significant impact on overall
local insect populations, a NLAA decision is appropriate for this use as the effects are
discountable. Spot treatments by hand spray along structural perimeters is also very
unlikely to result in significant impact to the CRLF, its prey, or its habitat, as this usage
does not favor surface runoff, widespread spray drift or substantial volatilization (only a
tiny fraction of land area is treated, and at ground level). A May Affect determination is
assumed for this usage because there will be some adverse effects on insects; but
ultimately a NLAA determination is made because any adverse effects will be limited to
sprayed areas (and overall insect populations should be relatively unaffected). Thus these
effects are discountable. Overall contributions from these additional uses should be
minor compared to the uses evaluated in this assessment; Agency expects that additional
loading within a catchment from these uses (indoor, bait stations, perimeter treatments,
etc.) should be minimal, even if such uses are concurrent with more widespread and
ubiquitous (modeled) uses. Similarly, the use of DDVP (toxic degredate of concern
resulting from naled use) as a separate active ingredient in other (non-naled) products is
not considered here, although any impact from DDVP directly resulting from naled use is
considered.
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Actual maximum allowable amounts applied as spot treatments by hand spray to
structural perimeters are not specified on the label(s); although this could be construed as
allowing unlimited usage for this purpose (and indeterminate total application rates), it is
unlikely that real usage for this purpose will result in significant adverse impact to the
CRLF. No quantitative estimation of exposure/effects resulting from this usage can be
performed; nevertheless, Agency believes that this usage should result in a NLAA
determination.
Exposure from nursery uses (bedding plants, foliage plants, outdoor nursery operations)
with label instructions to apply 0.9 lbs a.i./A "as needed" cannot be definitively
quantified or modeled. However, as most other (similar) uses that include multiple
applications at the same rate result in exceedences, and since presumably there can be an
almost indefinite number of seasonal applications for this use, a determination of LAA is
assumed. Preliminary data suggest that there will be numerous exceedences with as few
as 3 applications; unless there is firmer definition as to what constitutes "as needed" it
should be assumed that multiple applications will be made.
2.3 Previous Assessments
The most recent major naled registration-related documents produced by the Agency are
a 2002 Interim Reregisteration Eligibility Document (IRED) and a 1997 Reregisteration
Eligibility Document (RED). The 1997 RED was incorporated into the 2002 IRED. The
2002 IRED cited ecological risks and recommended the registrant adopt measures to
reduce ecological risk, beyond what had been implemented since 1999; these included
setbacks, buffers, application rate reductions, and application method restrictions for
some uses (see 2002 IRED for details). The conclusions are summarized below. For
details see the original RED and IRED documents
(http://epa.gov/oppsrrdl/REDs/naled ired.pdf and
http://www.epa.gov/pesticides/reregistration/REDs/naled_red.pdf).
Terrestrial Organisms
Birds and mammals will be exposed to naled through the consumption of insect and plant
food material containing naled residues and from direct exposure during application. The
level of concern (LOC) for acute risk to avian species is exceeded for use on almonds,
grapes, cotton, cole crops and seed alfalfa. The chronic avian LOCs are exceeded for
almonds, cole, citrus, and seed alfalfa. The LOC for acute and chronic risks to mammals
is exceeded for naled use on safflower, grapes, seed alfalfa, citrus, cole crops, and
almonds. The LOC for the mosquito use is only exceeded for acute risk to mammals.
There is potential for chronic risk to mammals because naled may be applied repeatedly
and because some of the use sites (citrus, grapes, and seed alfalfa) are high exposure sites
for mammals.
Data from an acute study shows naled to be highly toxic to honey bees. Data from foliar
residue studies showed a significant decrease in residual toxicity from 3 to 24 hours post
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treatment. Acute risk to bees is anticipated from the use of naled on blooming crops. The
extent of the hazard will vary with the application rate, weather conditions and the
formulation of the specific product.
Because no submitted data were available, terrestrial plants were not considered in
previous assessments. In this assessment plants will be considered qualitatively in the
absence of definitive quantitative toxicity data.
Aquatic Organisms
The acute and chronic LOC's for freshwater fish were not exceeded for any application
rate. However, acute and chronic LOC's were exceeded for freshwater invertebrates.
There are also potential risks to marine fish and invertebrates; however they are not of
major concern.
Aquatic plants will be exposed to naled through drift and runoff from treated areas (from
aerial and ground application) and through direct exposure of wetlands and aquatic
habitats from mosquito/black fly control applications. However, the level of concern for
risk to aquatic plants were exceeded only for cole crops and almonds.
Endangered Species
Endangered species LOCs for naled are exceeded for birds as follows: acute risks to
herbivorous birds from all uses except for mosquito control; acute risks to insectivorous
birds from the applications on almonds, cole crops and citrus; chronic risks to
herbivorous birds from the uses on almonds, cole crops, citrus and seed alfalfa; and
chronic risks to insectivorous birds from the use on almonds. Endangered species LOCs
for mammals are exceeded as follows: acute risks to herbivorous and insectivorous
mammals from all uses, including mosquito control. In addition, seed-eating mammals
are at risk from the almond use. Chronic risks are also a concern for herbivorous and
insectivorous mammals from all uses except for mosquito control. The chronic risk
exceedence for birds and mammals are based on maximum residues following one
application and do not include degradation or dissipation of naled in the environment. In
addition, endangered terrestrial invertebrates are expected to be at risk from all uses of
naled.
There are also risk concerns for endangered aquatic species. Endangered species acute
and chronic LOCs are exceeded for freshwater invertebrates from all uses. Naled's use
for mosquito control is only an acute risk to freshwater invertebrates. The acute LOC for
endangered freshwater fish is only exceeded for the uses on cole crops, citrus, and
almonds and to control horn flies. The acute LOC for endangered estuarine invertebrates
is exceeded for the use on cotton.
2.4 Stressor Source and Distribution
The chemical structure of naled is shown in Figure 1. Figure 2 depicts the chemical
structure of the degredate Dichlorvos (DDVP).
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Figure 1. Naled Chemical Structure
a—c—ch—
T
3r Br
Figure 2. Dichlorvos (DDVP) Chemical Structure
\
C—CH—O O—CH,
CI
2.4.1 Environmental Fate Assessment
Naled and its degredates are transformed largely by chemical hydrolysis and
biodegradation. Volatilization from soils and/or water and spray drift are likely the major
mode(s) of transport for naled and its bioactive degredate DDVP from application sites.
It is unclear to what extent transport of naled residues in the atmosphere results directly
from spray drift or from re-suspension in the atmosphere caused by volatilization of
deposited naled. It is likely that a substantial portion of airborne naled results from spray
drift, since it is typically applied as ultra-fine droplets or mist with the intent that it
remain suspended in the air as long as possible. It is probable that both factors contribute
to overall atmospheric transport, so it is best to consider in terms of 'total atmospheric
transport' rather than attempting to distinguish between volatilization and spray drift as
separate phenomena.
Under terrestrial, aquatic and forestry field conditions naled was observed to dissipate
rapidly with half-lives of less than 2 days in all three cases. The dissipation of DDVP
was also observed to be similarly rapid. While naled and DDVP are potentially mobile,
their degradation is very rapid; thus residues of naled and its degredate DDVP are not
likely to leach into ground water.
Substantial amounts of naled residues should be available for runoff to surface waters for
only one or two days post-application; rapid hydrolysis and even faster biodegradation
help quickly decrease the concentration of naled available for runoff. This should also be
the case for naled in the atmosphere; however, there are targeted studies (e.g., Tulare
County, CA, 1995) that indicate that measurable background levels of naled can be found
even in the absence of local naled use. This is likely due to the widespread and extensive
spray usage of naled, often applied aerially as very fine droplets or mist - which can
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enhance the probability of short-term atmospheric transport within catchments and to
neighboring catchments. Thus, it is more likely for naled to remain suspended in the
atmosphere, with frequent uses allowing detectable amounts to 'persist' over wide areas;
once adhered to soil, vegetation, or water, however, it will likely dissipate and degrade
fairly quickly. Generally, though, runoff may be the most likely mode of transport if rain
occurs soon after application - otherwise, atmospheric transport is probably dominant.
Naled and DDVP appear to have low bioaccumulation potential.
Major routes of possible transport of naled to surface waters are spray drift associated
with aerial or ground spray - especially for direct applications to water (swamps,
wetlands, saturated areas) for mosquito abatement. Although all labels clearly state "Do
not apply directly to water" there are specific exceptions made for certain treatments; in
particular, mosquito and fly control uses. For example, Trumpet EC insecticide label
states "Do not apply directly to water except when used over water as labeled for adult
mosquito, blackfly, or housefly control"; FLY KILLER D and DIBROM labels include
"swamps" as treatment sites for "adult mosquito, gnat, and housefly control". Thus, there
are uses where direct application to water must be considered.
The Agency has very little monitoring data on the concentrations of naled or its
degredates in surface water; a single detection of DDVP (0.242 |ig/L) in surface water
was reported in the Del Puerto Creek (a tributary to San Joaquin River) in Stanislaus
County, CA, 9/2003 (California Department of Pesticide Regulations (CDPR)). It is
unknown whether this detection reflected naled use as the source of DDVP. No
detections of parent naled were found in any local or national databases; however, it is
not known whether any water monitoring studies targeted specifically to naled use have
been conducted.
2.4.2 Environmental Transport Assessment
Potential transport mechanisms include pesticide surface water runoff, 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). Several
sections of critical habitat for the CLRF are located east of the Central Valley. 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 Nevadas are considered in evaluating the potential for
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atmospheric transport of naled to locations where it could impact the CRLF or its
designated critical habitat.
In general, deposition of drifting or volatilized pesticides is expected to be greatest close
to the site of application. Computer models of spray drift (AgDRIFT or AGDISP) are
used to determine if the exposures to aquatic and terrestrial organisms are below the
Agency's Levels of Concern (LOCs). If the limit of exposure that is below the LOC can
be determined using AgDRIFT or AGDISP, longer-range transport is not considered in
defining the action area. For example, if a buffer zone <1,000 feet (the optimal range for
AgDRIFT and AGDISP models) results in terrestrial and aquatic exposures that are
below LOCs, no further drift analysis is required. If exposures exceeding LOCs are
expected beyond the standard modeling range of AgDRIFT or AGDISP, the Gaussian
extension feature of AGDISP may be used. In addition to the use of spray drift models to
determine potential off-site transport of pesticides, other factors such as available air
monitoring data and the physicochemical properties of the chemical are also considered.
The physical/chemical properties of parent naled are shown in Table 2. Detailed
information on the fate and transport properties of naled can be found in Appendix E.
Table 2 Physical/Chemical Properties of Naled
PARAMETER
VALUE
SOURCE(S)
Molecular Weight
381
EXTOXNET
Henry's Law Constant
1E-4
Calculated
Vapor Pressure (torr)
2E-3
EXTOXNET
Solubility (mg/L)
1 mg/L
EXTOXNET
Koc
180
EXTOXNET
Hydrolysis (days)
pH 5=4
pH 7 = 0.642
pH 9 = 0.067
MRID 40034902,41354101
Aqueous Photolysis half-life (days)
4.4 - 4.7 days
MRID 41310702, 42445103
Aerobic Aquatic half-life (days)
--
No Valid Data Submitted
Anaerobic Aquatic half-life (days)
4.5
MRID 40618201,41354102,
42445101
Aerobic Soil half-life (days)
1
MRID 00085408
Soil Photolysis (days)
0.4
MRID 41310701, 42445104
Table 3 gives the relevant physical/chemical properties of the degredate DDVP. Detailed
information on the fate and transport properties of DDVP can be found in Appendix F.
Table 3 Physical/Chemical Properties of DDVP
PARAMETER
VALUE
SOURCE(S)
Molecular Weight
221
EXTOXNET
Henry's Law Constant
5E-8
Vapor Pressure (torr)
1.2E-2
Solubility (mg/L)
15600
Kd
0.3
MRID 41354105
26
-------
PARAMETER
VALUE
SOURCE(S)
Koc
37
MRID 41354105
Hydrolysis (days)
pH 5 = 11.6
pH 7 = 5.2
pH 9 = 0.88
MRID 41723101
Aqueous Photolysis half-life (days)
10
MRID 43326601
Aerobic Aquatic half-life (days)
--
No Valid Data Submitted
Anaerobic Aquatic half-life (days)
4.5
MRID 40618201,41354102,
42445101
Aerobic Soil half-life (days)
0.42
MRID 41723102 (X3 = 1.26
days)
Anaerobic Soil half-life (days)
6.3
MRID 43835701
Soil Photolysis (days)
0.65
MRID 43642501
2.4.3 Pesticidal Mechanism of Action
Naled is an organophosphate insecticide. It is a potent cholinesterase (ChE) inhibitor,
causing reversible inhibition of erythrocyte acetylcholinesterase (RBC ChE) as well as
plasma butyryl ChE by binding to the active site of the enzyme. Acetylcholinesterase is
an enzyme necessary for the degradation of the neurotransmitter acetylcholine (ACh) and
subsequent cessation of synaptic transmission. Inhibition of these enzymes results in the
accumulation of ACh at cholinergic nerve endings and continual nerve stimulation,
resulting in insect death. The naled degredate of concern, dichlorvos (DDVP), has an
identical mode of action.
2.4.4 Use Characterization
Analysis of labeled use information is the critical first step in evaluating the federal
action. The current label for naled represents 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.
Certain naled uses are not specifically incorporated into this risk assessment because it is
believed that they present minimal capacity to affect the overall risk conclusions (based
upon uses with much higher risk likelihood), and individually they are discountable.
Specifically, bait uses, indoor uses, hand spray applications, and utility pole applications
are not quantified here because either preliminary results from modeling yielded very low
environmental exposure concentrations (EECs), or it is understood that total exposure
resulting from these uses is likely to be very low and limited in scope. For example,
because of very low application "rates" and limited 'spot' treatments at designated areas
(i.e.: 6 square inches of diluted bait applied only to utility poles linearly at 200-foot
intervals; small containers of sugar water and naled bait placed around structural
perimeters), bait station applications will almost certainly have minimal effect on total
27
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environmental exposure (especially when compared to widespread spray applications that
may occur in the same area). Similarly, indoor uses should have little impact on the
exterior environment. Hand spray applications require much lower application rates than
aerial/ground spray, ULV, and airblast applications, and are used over much smaller
areas (as 'spot' treatments); thus their impact and contribution to total pesticide load
should be less as well. Any of these uses individually should result in negligible and
discountable effect on the CRLF.
Table 4 provides detailed information for each use site on the remaining end-use labels as
well as the pertinent SLNs.
Table 4. Maximum Naled Use Rates and Management Practices by Crop Based on Current Labels.
(Generalized Screening Level Portrayal Of Current Label Uses)
Current As Of - 05/31/2007
Use Site
Maximum
Application rate
Minimum
Rctrcatment
Interval
Maximum
No. of
Applications
Maximum
application
rate/season
Alfalfa
(SLN CA000006)
1.4 lbs a.i./A
7 days
3
4.2 lbs
a.i./A
Almond (ground only)
1.9 lbs a.i./A
1 (dormant or
dormant
delayed, only)
1.9 lbs
a.i./A
Beans, lima beans and Peas (dry
and succulent form)
Ground: 1.4 lbs
a.i./A
Aerial (CA only):
0.9 lbs a.i./A
7 days
5
4.2 lbs
a.i./A
Broccoli, cabbage (includes
tight head varieties of Chinese
cabbage), cauliflower, Brussels
sprouts, kale, and collards
1.9 lbs a.i./A
7 days
5
9.4 lbs
a.i./A
Cantaloupes, muskmelons
0.9 lbs a.i./A
7 days
—
1.9 lbs
a.i./A
Hops
0.9 lbs a.i./A
14 days
5
4.7 lbs
a.i./A
Melons
(grown for seed only)
0.9 lbs a.i./A
7 days
2
1.9 lbs
a.i./A
Celery
1.4 lbs a.i./A
7 days
5
7.0 lbs
a.i./A
Cotton
(Section 3 and SLN CA050011)
0.9 lbs a.i./A
7 days
4.7 lbs
a.i./A
1.4 lbs a.i./A
—
Eggplant, peppers
1.9 lbs a.i./A
7 days
5
5.6 lbs
a.i./A
Grapes
(ground only)
Airblast (CA
only): 0.9 lbs
a.i./A
5.6 lbs
a.i./A
Oranges, lemons, grapefruit,
tangerines
1.9 lbs a.i./A
7 days
5 (may only
apply to aerial
application?)
5.6 lbs
a.i./A
Peaches
(ground only)
1.9 lbs a.i./A
N/A
1 (dormant or
delayed
1.9 lbs
a.i./A
28
-------
Use Site
Maximum
Application rate
Minimum
Rctrcatment
Interval
Maximum
No. of
Applications
Maximum
application
rate/season
dormant)
Safflower (CA and AZ only)
2.1 lbs a.i./A
7 days
2
4.2 lbs
a.i./A
Strawberries
0.9 lbs a.i./A
7 days
5
4.7 lbs
a.i./A
Sugar beets
0.9 lbs a.i./A
7 days
5
4.7 lbs
a.i./A
Summer squash
1.9 lbs a.i./A
7 days
5
5.6 lbs
a.i./A
Swiss chard
(ground only with fine mist
spray)
0.9 lbs a.i./A
7 days
7
7.0 lbs
a.i./A
Walnuts
1.9 lbs a.i./A
7 days
4
3.8 lbs
a.i./A
Forest and shade trees,
ornamental shrubs and
flowering plants (ground only)
0.9 lbs a.i./A
Repeat as
necessary
Greenhouse, vapor treatment of
roses and other ornamental
plants
(hot plate application)
0.06 lb ai/10,000
cu ft. (label
incorrect, see letter
from RD)
4-7 days
2-4
Repeat as
necessary
In and around food processing
plants, loading docks, cull piles,
refuse areas.
(ground only)
0.1 lba.i.
5-7 days
As
necessary
Swamps and pastures
(Consult State Fish and Game
Agency before applying; this
application rate will kill shrimp,
do not apply to tidal or marsh
waters)
Aircraft: 0.23 lb
a.i./A
Mist or cold fog:
0.25 lb a.i./A
For reduction of livestock pests
in confined animal feeding
operations (e.g. corrals, holding
pens, feedlots) containing dairy
and beef cattle, hogs, sheep, or
horses
Aerial: 0.2 lb
a.i./A
Ground: 0.25 lb
a.i./A
7 days (may
only apply to
ground
applications?)
For reduction of pests in
rangelands
0.1 lb a.i./A
7 days
—
—
In and around dairy barns,
livestock barns, pig pens,
poultry houses, feed lots, cattle
pens, garbage dumps, outside
meat packing establishments,
pens, docks, ramps, disposal
areas and cider mills (space
spray only)
0.9 lbs ai/40
gallons water
0.06 lbs ai/2.5
gallons water
In and around food processing
plants, loading docks, cull piles
and refuse areas and cider mills
2.25 lbs ai/100
gallons water
0.06 lbs ai/2.5
gallons water
29
-------
Maximum
Minimum
Maximum
Maximum
Use Site
Application rate
Rctrcatment
No. of
application
Interval
Applications
rate/season
Telephone or light poles
1.14 lbs a.i./gallon
2-4 weeks
600 bait
Repeat spot
(ground hand-spray only)
of attractant; 6
stations/
applications
inches of material
square mile
until
(SLN CA860005)
per bait station
infestation
has been
eradicated
Residential areas,
0.1 lb a.i./A (label
24 hours
—
Dibrom 8
municipalities, tidal marshes,
rate is incorrect,
Emulsive:
swamps, woodlands, and
see letters from
0.22 lbs
agricultural areas
RD)
a.i./week
10.4 lbs
a.i./year
(180 oz. =
10.5 lbs
a.i./year)
Dibrom
Concentrate:
0.21 lb
a.i./week
10.73 lb
a.i./year
Trumpet EC
Insecticide:
0.171b
a.i./week
10.73 lb
a.i./year
More
frequent
treatments
may be
made, if
determined
necessary
by a state,
tribe, or
local health
or vector
control
agency.
30
-------
Maximum
Minimum
Maximum
Maximum
Use Site
Application rate
Rctrcatment
No. of
application
Interval
Applications
rate/season
Livestock pastures, including
0.1 lb a.i./A
7 days (label
—
0.22 lbs
dairy cattle
interval is
a.i./week
incorrect; see
10.4 lbs
letter from RD)
a.i./year
(180 oz. =
10.5 lbs
a.i./year)
More
frequent
treatments
may be
made, if
determined
necessary
by a state,
tribe, or
local health
or vector
control
agency.
Feed lots including dairy cattle,
Aircraft: 0.06 lbs
7 days (unless
—
—
and pastures including
a.i./A
monitoring
woodlands, swamps (direct
demonstrates
application to water is
Mist blower: 0.1
that mosquitoes
prohibited)
lbs a.i./A
have re-infested
the area)
The Agency's Biological and Economic Analysis Division (BEAD) provides an analysis
of both national- and county-level usage information using state-level usage data
obtained from USDA-NASS2, Doane (www.doane.com); the full dataset is not provided
due to its proprietary nature), and the California's Department of Pesticide Regulation
Pesticide Use Reporting (CDPR PUR) database3 . CDPR PUR is considered a more
comprehensive source of usage data than USDA-NASS or EPA proprietary databases,
and thus the usage data reported for naled by county in this California-specific
assessment were generated using CDPR PUR data. Usage data are presented for the
years 2002 to 2005 to calculate average annual usage statistics by county and crop for
naled, including pounds of active ingredient applied and base acres treated. California
State law requires that every commercial pesticide application be reported to the state and
made available to the public. The summary of naled usage for all use sites, including
both agricultural and non-agricultural, is provided below in Table 5 and Table 6.
2 United States Depart of Agriculture (USDA), National Agricultural Statistics Service (NASS) Chemical
Use Reports provide summary pesticide usage statistics for select agricultural use sites by chemical, crop
and state. See http://www.usda.gov/nass/pubs/estindxl,htm#agchem.
3 The California Department of Pesticide Regulation's Pesticide Use Reporting database provides a census
of pesticide applications in the state. See http://www.cdpr.ca.gov/docs/pur/purmain.htm.
31
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According to 2002-2005 CA PUR data, a total of 743,280 lbs of naled was applied in
California during that period. The dominant naled uses in California are represented by
use on Cotton (approximately 38% of total naled applied in CA from 2002 to 2005),
Broccoli (about 12% of total applied), for Public Health (including flying insect control)
(roughly 11% of total), Strawberry (—10%), and Sugarbeet (6%). All other uses
individually represented <5% of total. Fresno and King Counties had the highest naled
usage for this period (255,250 lbs and 106,305 lbs, respectively), followed by Monterey
County (88,629 lbs) and Sutter County (43,010). Lake, El Dorado, Tehama, and San
Francisco Counties reported the lowest amounts used, with the latter two counties
reporting zero lbs used from 2002-2005.
Table 5. Total Pounds Applied in Each County for the Years 2002-2005
Counties are sorted in descending order by the greatest pounds a.i. applied in 2005.
County
Sum of Total
Pounds 2002
Sum of Total
Pounds 2003
Sum of Total
Pounds 2004
Sum of Total
Pounds 2005
Fresno
61,737
75,847
36,749
80,916
Kings
22,173
15,957
20,274
47,901
Monterey
21,886
24,862
24,635
17,246
San Joaquin
7,674
8,177
6,776
13,397
Santa Barbara
2,989
7,636
9,223
12,219
Sutter
10,533
12,973
10,466
9,038
Butte
3,746
1,888
3,613
8,393
Imperial
725
2,217
4,480
5,518
Colusa
2,721
1,670
4,049
5,503
Stanislaus
4,818
5,101
10,730
3,847
Merced
8,911
5,272
3,491
3,445
San Bernardino
6,603
4,560
2,418
2,614
Ventura
930
1,852
1,637
1,992
Santa Cruz
1,268
1,862
2,399
1,896
Riverside
3,775
3,441
900
1,517
Tulare
4,956
1,825
1,793
1,465
San Luis Obispo
873
2,188
750
1,326
Santa Clara
1,323
530
427
1,017
Glenn
236
542
439
840
Shasta
0
0
0
814
Kern
2,215
2,104
1,476
787
Madera
66
1,135
683
595
Los Angeles
582
251
184
484
San Benito
450
407
288
138
Solano
0
0
0
134
Orange
41
23
615
127
Contra Costa
60
91
106
103
San Mateo
29
7
14
63
Sonoma
0
0
48
26
Amador
10
0
0
14
San Diego
462
270
69
1
Tehama
0
0
0
0
32
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County
Sum of Total
Pounds 2002
Sum of Total
Pounds 2003
Sum of Total
Pounds 2004
Sum of Total
Pounds 2005
San Francisco
0
0
0
0
Yuba
948
2,386
2,149
0
Alameda
1
3
1,569
0
Yolo
381
90
18
0
Lake
0
0
8
0
El Dorado
0
0
2
0
Calaveras
11
95
0
0
Sacramento
14
19
0
0
Grand Total
173,145
185,279
152,479
223,377
Table 6. Reported Uses and Annual Pounds (a.i.) Applied for 2002-2005 in
California
Site Name
Sum of
Total
Pounds
2002
Sum of
Total
Pounds
2003
Sum of
Total
Pounds
2004
Sum of
Total
Pounds
2005
Cotton
64,439
69,376
36,387
107,437
Public Health
15,409
18,814
18,499
26,600
Broccoli
9,223
26,350
24,315
25,850
Strawberry
13,604
19,213
19,653
19,528
Sugarbeet
10,291
11,605
9,409
13,217
Walnut
8,043
7,637
5,501
7,711
Animal Premise
11,105
10,194
1,984
3,558
Structural Pest Control
1,869
1,040
4,710
3,411
Bean, Dried
4,173
2,063
1,501
3,263
Alfalfa
8,357
2,687
7,623
3,151
Cauliflower
3,753
1,456
2,460
1,651
Cabbage
546
859
1,591
1,497
Landscape Maintenance
5,376
1,422
9,754
1,188
Bean, Succulent
1,183
553
327
1,090
Regulatory Pest Control
535
621
923
598
Collard
594
627
381
592
Almond
686
471
1,092
353
Squash
36
508
0
342
Kale
521
270
273
325
Grape, Wine
462
2,210
81
312
Peas
259
373
278
301
Grape
1,034
395
389
252
N-Grnhs Flower
720
1,725
896
223
Safflower
5,714
2,190
1,970
175
Pepper, Fruiting
619
451
207
148
Bean, Unspecified
167
125
41
130
Brussels Sprout
89
44
41
96
33
-------
Sum of
Sum of
Sum of
Sum of
Total
Total
Total
Total
Pounds
Pounds
Pounds
Pounds
Site Name
2002
2003
2004
2005
N-Outdr Flower
0
51
153
69
Pepper, Spice
0
78
192
63
Orange
2,563
271
1,168
55
Rights Of Way
9
0
0
45
Research Commodity
61
71
33
33
Lettuce, Head
1
0
0
24
Cantaloupe
0
227
0
22
N-Outdr Plants In Containers
14
16
80
9
N-Grnhs Plants In Containers
22
7
2
9
N-Grnhs Transplants
2
13
13
8
Squash, Summer
56
77
35
8
Bok Choy
0
0
0
7
N-Outdr Transplants
2
4
5
6
Peach
37
0
22
5
Chinese Cabbage (Nappa)
0
2
0
5
Celery
4
25
29
3
Eggplant
0
1
0
2
Pastureland
2
146
7
2
Vertebrate Control
0
0
0
0
Chicory
0
0
0
0
Sugarbeet (Forage - Fodder)
0
0
334
0
Tangerine
82
10
57
0
Citrus
23
0
50
0
Blackberry
0
0
10
0
Lemon
3
0
2
0
Cattle
48
717
0
0
Squash, Zucchini
0
211
0
0
Swiss Chard
39
37
0
0
Commodity Fumigation
40
32
0
0
Pistachio
0
2
0
0
Lettuce, Leaf
14
0
0
0
Chicken
7
0
0
0
Corn, Human Consumption
34
0
0
0
Cucumber
2
0
0
0
Dairy Equipment
1,074
0
0
0
Poultry
Not reported
0
0
0
Soil Fumigation/Preplant
30
0
0
0
Tangelo
40
0
0
0
Tomato
26
0
0
0
Uncultivated Non-Ag
105
0
0
0
Grand Total
173,145
185,279
152,479
223,377
* a zero indicates a value less than one.
34
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The available data for naled application spans only four years. This does not provide
sufficient data for a quantitative evaluation of trends and averages. The data above are
presented to give context to the wide variety of uses allowed on the naled label. The
appearance of an increase or decrease in naled usage for a particular crop should not be
used to make prediction for future use as pest pressures change not only year to year, but
even season to season. These data may be used to characterize risk.
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.
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
35
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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 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 7 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 3). Table 7 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 naled occur (or if labeled uses occur
at predicted exposures less than the Agency's LOCs) within an entire recovery unit, 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
36
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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 7 (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.
Table 7. California Red-legged Frog Recovery Units with Overlapping Core Areas and
Designated Critical Habitat
Recovery Unit1
(Figure 2.a)
Core Areas2'7 (Figure 2.a)
Critical Habitat
Units3
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
37
-------
Recovery Unit1
(Figure 2.a)
Core Areas2'7 (Figure 2.a)
Critical Habitat
Units3
Currently
Occupied
(post-1985)
4
Historically
Occupied 4
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)
--
Watsonville Slough- Elkhorn
Slough (partial)(19)
MNT-1
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)
~
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
38
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Recovery Unit1
(Figure 2.a)
Core Areas2'7 (Figure 2.a)
Critical Habitat
Units3
Currently
Occupied
(post-1985)
4
Historically
Occupied 4
(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.
39
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* Core areas that were historically occupied by the California red-legged frog are not included in the map
Figure 3. Recovery Unit, Core Area, Critical Habitat, and Occurrence Designations
for CRLF
Core Areas
1. Feather River
19.
Watsonville Slough-Elkhorn Slough
2. Yuba River- S. Fork Feather River
20.
Carmel River - Santa Lucia
3. Traverse Creek/ Middle Fork/ American R. Rubicon
21.
Gab lan Range
4. Cosumnes River
22.
Estero Bay
5. South Fork Calaveras River*
23.
Arroyo Grange River
6. Tuolumne River*
24.
Santa Maria River - Santa Ynez River
7. Piney Creek*
25.
Sisquoc River
8. Cottonwood Creek
26.
Ventura River - Santa Clara River
9. Putah Creek - Cache Creek*
27.
Santa Monica Bay - Venura Coastal Streams
10. Lake Berryessa Tributaries
28.
Estrella River
11. Upper Sonoma Creek
29.
San Gabriel Mountain*
12. Petaluma Creek - Sonoma Creek
30.
Forks of the Mojave*
13. Pt. Reyes Peninsula
31.
Santa Ana Mountain*
14. Belvedere Lagoon
32.
Santa Rosa Plateau
15. Jameson Canyon - Lower Napa River
33.
San Luis Ray*
16. East San Francisco Bay
34.
Sweetwater*
17. Santa Clara Valley
35.
Laguna Mountain*
18. South San Francisco Bay
* Core areas that were historically occupied by the California red-legged frog are not included in the map
CNDDB Occurence Sections
County Boundaries q
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
Legend
~ Recovery Unit Boundaries ^
5] Currently Occupied Core Areas
I Critical Habitat
40
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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.
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 4 depicts CRLF annual reproductive timing.
Figure 4. CRLF Reproductive Events by Month*
J FMAMJ JASOND
Light Blue =
Green = lat over-winter)
Orange = awusk;;,
* Adults and juveniles can be present all year
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
41
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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. californica), pillbugs (Armadilliadrium vulgare), and water striders (Gerris sp).
The preferred prey species, however, was the sowbug (Hayes and Tennant, 1985). This
study suggests that CRLFs forage primarily above water, although the authors note other
data reporting that adults also feed under water, are 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). Dense vegetation close to water, shading, and 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#where).
In general, dispersal and habitat use depends on climatic conditions, habitat suitability,
and life stage. Adults rely on riparian vegetation for resting, feeding, and dispersal. The
42
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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).
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 7.
"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
destruction or adverse modification of critical habitat.
To be included in a critical habitat designation, the habitat must be 'essential to the
conservation of the species.' Critical 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
43
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• Dispersal habitat.
Further 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 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 adverse modification standards for designated critical habitat
(USFWS 2006). Activities that may destroy or adversely modify critical habitat are those
that alter the PCEs and jeopardize the continued existence of the species. Evaluation of
actions related to use of naled 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 adverse 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 adverse 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 adversely
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).
44
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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 naled is expected to directly impact living
organisms within the action area, critical habitat analysis for naled 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 naled is likely to encompass considerable portions of the
United States based on the large array of agricultural and non-agricultural 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 is the product of consideration of the types of effects that naled
may be expected to have on the environment, the exposure levels to naled that are
associated with those effects, and the best available information concerning the use of
naled 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 naled. An analysis of labeled uses and review of available product labels was
completed. Several of the currently labeled uses are special local needs (SLN) uses or are
restricted to specific states and are excluded from this assessment. In addition, a
distinction has been made between food use crops and those that are non-food/non-
agricultural uses. For those uses relevant to the CRLF, the analysis indicates that, for
naled, the following agricultural uses are considered as part of the federal action
evaluated in this assessment:
• Beans
• almonds
• peas
• cabbage
• broccoli
• cauliflower
• Brussels sprouts
• collards
• kale
• cantaloupes
• muskmelons
• hops
• melons
45
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• celery
• cotton
• eggplant
• peppers
• grapes
• oranges
• lemon
• grapefruit
• tangerine
• peaches
• safflower
• strawberries
• sugar beets
• summer squash
• Swiss chard
• walnuts
In addition, the following non-food and non-agricultural uses are considered:
• forestry
• bedding plant
• foliage plants
• outdoor nursery operations
• areas outside of buildings
• forestry
• impervious surfaces
• parks
• rangeland
• recreational fields
• residential (including lawns)
• wetlands/stagnant water/saturated areas/vegetation in and around water bodies
The following indoor (and other) uses are not quantitatively assessed in this assessment
given that these uses are not expected to result in exposure to the CRLF:
commercial/institutional/industrial premises/equipment; household/domestic dwellings;
indoor premises; and baiting refuse/solid waste sites.
Following a determination of the assessed uses, an evaluation of the potential "footprint"
of naled use patterns is determined. This "footprint" represents the initial area of
concern, based on an analysis of available land cover data for the state of California.
The initial area of concern is defined as all land cover types and the stream reaches within
the land cover areas that represent the labeled uses described above. A map representing
all the land cover types that make up the initial area of concern for naled is presented in
Figure 5.
46
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Legend
Open water
EZZ3 Wetlands
Orchard/Vineyard
Cultivated crops
| Critical habitat
Currents occupied
CNDDB occurence
~ Recovery units
County boundaries
Naled Initial Area of Concern for agriculture, wetlands, and swamp uses
Compiled from California County boundaries (ESRI, 2002),
USQA National Agriculture Statistical Service (NASS, 20QZ)
Gap Anal/sis Program Orchard/Vineyard Uandcover (GAP)
National Land Cower Database (NLCD) (MRLC, 2001)
Map created by US Environmental Protection Agency, Office
of Pesticides Programs, Environmental Fate and Effects Division.
Projection: Albers Equal Area Conic USGS, North American
Datum of 1983 (NAD 1983).
Produced 1/2/2008
Figure 5. Initial area of concern, or "footprint" of potential use, for naled
47
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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. The screening level risk
assessment will define which taxa, if any, are predicted to be exposed at concentrations
above the Agency's Levels of Concern (LOC). The screening level assessment includes
an evaluation of the environmental fate properties of naled to determine which routes of
transport are likely to have an impact on the CRLF.
Atmospheric transport is likely a major transportation pathway for naled and the toxic
degredate of concern dichlorvos (DDVP), especially for airborne application methods
(spray, mist, ULV, airblast) that constitute the majority of naled applications. Runoff in
surface water is possible, specifically if rainfall occurs within 2 days of application.
Leaching to groundwater is unlikely - although DDVP is potentially mobile in soil, it is
insufficiently persistent to cause widespread or long-term groundwater contamination in
most conditions. In all cases, rapid dissipation/degradation of both naled and DDVP
make it likely that any potential exposures (air, soil, water) will be short-lived.
Subsequent to defining the action area, an evaluation of usage information was conducted
to determine areas where use of naled may impact the CRLF. This analysis is used to
characterize where predicted exposures are most likely to occur but does not preclude use
in other portions of the action area. A more detailed review of the county-level use
information was also completed, as described above.
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."4 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 naled
(e.g., runoff, spray drift, etc.), and the routes by which ecological receptors are exposed
to naled-related contamination (e.g., direct contact, etc).
2.8.1 Assessment Endpoints for the CRLF
Assessment endpoints for the CRLF include direct toxic effects on the survival,
reproduction, and growth of the CRLF, as well as indirect effects, such as reduction of
the prey base or 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
4FromU.S. EPA (1992). Framework for Ecological Risk Assessment. EPA/630/R-92/001.
48
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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 naled is provided in Table 8.
It should be noted here that the common naled degredate, DDVP, is toxic. Therefore, it is
necessary to capture the potential for risk from exposure to this compound. Because
DDVP is also a registered pesticide (PC Code: 084001) toxicity studies are available for
inclusion in the assessment. To adequately capture the risk from naled, a rapidly
degrading compound, the more toxic of the two pesticides were selected for each specific
measurement endpoint. For example, naled is more toxic to fish while DDVP is more
toxic to birds. Because the organism will potentially be exposed to both of these
chemicals, it is necessary to measure risk by comparing the modeled exposure values to
the most sensitive endpoint. The more toxic chemical was identified by comparing the
toxicity values with molar units.
Table 8. Summary of Assessment Endpoints and Measures of Ecological Effects for
Direct and Indirect Effects of Naled on the California Red-legged Frog
Moiisuivs of l-lcolo^iciil r.lTccis-"
Aquatic-Phase CRLF
(Eggs, larvae, juveniles, and adults"f
Direct Effects
1. Survival, growth,
and reproduction of
CRLF
la. Amphibian acute LC50 (ECOTOX) or most
sensitive fish acute LC50 (guideline or
ECOTOX) if no suitable amphibian data are
available
lb. Amphibian chronic NOAEC (ECOTOX) or
most sensitive fish chronic NOAEC (guideline
or ECOTOX)
lc. Amphibian early-life stage data
(ECOTOX) or most sensitive fish early-life
stage NOAEC (guideline or ECOTOX)
la. Naled, Lake trout 96-hr
LC50 =92 ppb
lb. Naled, Fathead minnow
35 Day NOAEC=2.9 ppb
Indirect Effects and Critical Habitat Effects
2. Survival, growth,
and reproduction of
CRLF individuals via
indirect effects on
aquatic prey food
supply (i.e., fish,
freshwater
invertebrates, non-
2a. Most sensitive fish, aquatic invertebrate,
and aquatic plant EC50 or LC50 (guideline or
ECOTOX)
2b. Most sensitive aquatic invertebrate and fish
chronic NOAEC (guideline or ECOTOX)
2a.
Naled, Lake trout 96-hr
LC50 =92 ppb
DDVP, Daphnia pulex 48-hr
LC50=0.066ppb
Naled, Freshwater Diatom
5 All registrant-submitted and open literature toxicity data reviewed for this assessment are included in
Appendix A.
49
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Assossmciil I'lnripoini
Moiisuivs of llcolo^iciil I'-IIVcls"
vascular plants)
(Navicula pelliculosa) 5 D
EC50=25 ppb
2b.
Naled, Fathead minnow 35 D
NOAEC=2.9ppb
Naled, Daphnia magna 21 D
NOAEC = 0.045ppb
Naled Estimated NOAEC
(using freshwater ACR)
=0.00017 ppb
3. Survival, growth,
and reproduction of
CRLF individuals via
indirect effects on
habitat, cover, food
supply, and/or primary
productivity (i.e.,
aquatic plant
community)
3 a. Vascular plant acute EC50 (duckweed
guideline test or ECOTOX vascular plant)
3b. Non-vascular plant acute EC50 (freshwater
algae or diatom, or ECOTOX non-vascular)
3a. Naled, Duckweed 14 D
EC50 >1800 ppb
3b. Naled, Freshwater
Diatom (Navicula
pelliculosa) 5 D EC50=25
ppb
4. Survival, growth,
and reproduction of
CRLF individuals via
effects to riparian
vegetation
4a. Distribution of EC25 values for monocots
(seedling emergence, vegetative vigor, or
ECOTOX)
4b. Distribution of EC25 values for dicots
(seedling emergence, vegetative vigor, or
ECOTOX)
4a. No data available
4b. No data available
Terrestrial-Phase CRLF
(Juveniles and adults)
Direct Effects
5. Survival, growth,
and reproduction of
CRLF individuals via
direct effects on
terrestrial phase adults
and juveniles
5a. Most sensitive birdb or terrestrial-phase
amphibian acute LC50 or LD50 (guideline or
ECOTOX)
5b. Most sensitive birdb or terrestrial-phase
amphibian chronic NOAEC (guideline or
ECOTOX)
5a.
Naled, Canada goose, 14 D
acute oral LD50=36.9
mg/kg-bw
DDVP, Mallard duck 14 D
acute oral LD50= 7.8 mg/kg
Naled, Japanese quail, 8 Day
dietary LC50=1327ppm
DDVP, Japanese quail 8D
dietary LC50=298ppm
5b.
Naled, Mallard duck
NOAEC=266 ppm
DDVP, Mallard duck 22 WK
NOAEC=15 ppm
Indirect Effects and Critical Habitat Effects
6. Survival, growth,
and reproduction of
CRLF individuals via
effects on terrestrial
prey (i.e.,terrestrial
invertebrates, small
6a. Most sensitive terrestrial invertebrate and
vertebrate acute EC50 or LC50 (guideline or
ECOTOX)0
6b. Most sensitive terrestrial invertebrate and
vertebrate chronic NOAEC (guideline or
ECOTOX)
6a. Naled, Rat acute-oral
LD50=92 mg/kg
Naled, Honey bee 48-hr
LD50=0.48 ng/bee or 3.75
ppm
DDVP, Rat acute-oral
50
-------
Assossmciil I'lnripoini
Moiisuivs of llcolo^iciil I'-IIVcls"
mammals, and frogs)
LD50=56mg/kg-bw
6b. Naled, Rat chronic
NOAEL=6 mg/kg
DDVP, Rat chronic
NOAEL=20 mg/kg-bw
7. Survival, growth,
and reproduction of
CRLF individuals via
indirect effects on
habitat (i.e., riparian
and upland vegetation)
7a. Distribution of EC25 for monocots (seedling
emergence, vegetative vigor, or ECOTOX
7b. Distribution of EC25 for dicots (seedling
emergence, vegetative vigor, or ECOTOX)
No data available
a 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.
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 naled that may alter the PCEs of the CRLFs 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. 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 naled effects data are
available.
Assessment endpoints and measures of ecological effect selected to characterize potential
modification to designated critical habitat associated with exposure to naled 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:
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.
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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 naled 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 adverse
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
Assessment Endpoint
Measures of Ecological Effect6
Aquatic Phase PCEs
(Aquatic Breeding Habitat and Aquatic Non-Breeding Habitat)
Alteration of channel/pond
morphology or geometry and/or
increase in sediment deposition
within the stream channel or pond:
aquatic habitat (including riparian
vegetation) provides for shelter,
foraging, predator avoidance, and
aquatic dispersal for juvenile and
adult CRLFs.
a. Most sensitive
aquatic plant EC50
(guideline or
ECOTOX)
b. Distribution of EC25
values for terrestrial
monocots (seedling
emergence, vegetative
vigor, or ECOTOX)
c. Distribution of EC25
values for terrestrial
dicots (seedling
emergence, vegetative
vigor, or ECOTOX)
a. Naled, Freshwater Diatom (Navicula
pelliculosa) 5 D EC50=25 ppb
b. No data available
c. No data available
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.7
a. Most sensitive EC50
values for aquatic plants
(guideline or ECOTOX)
b. Distribution of EC25
values for terrestrial
monocots (seedling
emergence or vegetative
vigor, or ECOTOX)
c. Distribution of EC25
values for terrestrial
dicots (seedling
emergence, vegetative
vigor, or ECOTOX)
a. Naled, Freshwater Diatom (Navicula
pelliculosa) 5 D EC50=25 ppb
b. No data available
c. No data available
Alteration of other chemical
characteristics necessary for normal
growth and viability of CRLFs and
their food source.
a. Most sensitive EC50
or LC50 values for fish
or aquatic-phase
amphibians and aquatic
invertebrates (guideline
or ECOTOX)
b. Most sensitive
NOAEC values for fish
or aquatic-phase
amphibians and aquatic
invertebrates (guideline
or ECOTOX)
2a.
Naled, Lake trout 96-hr LC50 =92 ppb
DDVP, Daphnia pulex 48-hr
LC50=0.066ppb
Naled, Freshwater Diatom (Navicula
pelliculosa) 5 D EC50=25 ppb
2b.
Naled, Fathead minnow 35 D
NOAEC=2.9ppb
Naled, Daphnia magna 21 D NOAEC =
0.045ppb
Naled Estimated NOAEC (using
freshwater ACR) =0.00017 ppb
8 All toxicity data reviewed for this assessment are included in Appendix A
9 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.
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Assessment Endpoint
Measures of Ecological Effect6
Reduction and/or modification of
aquatic-based food sources for pre-
metamorphs (e.g., algae)
a. Most sensitive
aquatic plant EC50
(guideline or
ECOTOX)
a. Naled, Freshwater Diatom (Navicula
pelliculosa) 5 D EC50=25 ppb
Terrestrial Phase PCEs
(Upland Habitat and Dispersal Habitat)
Elimination and/or disturbance of
upland habitat; ability of habitat to
support food source of CRLFs:
Upland areas within 200 ft of the
edge of the riparian vegetation or
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
a. Distribution of EC25
values for monocots
(seedling emergence,
vegetative vigor, or
ECOTOX)
b. Distribution of EC25
values for dicots
(seedling emergence,
vegetative vigor, or
ECOTOX)
c. Most sensitive food
source acute EC50/LC50
and NOAEC values for
terrestrial vertebrates
(mammals) and
invertebrates, birds or
terrestrial-phase
amphibians, and
freshwater fish.
a. No data available
b. No data available
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.
2.9 Conceptual Model
2.9.1 Risk Hypotheses
Risk hypotheses are specific assumptions about potential adverse effects (i.e., changes in
assessment endpoints) and may be based on theory and logic, empirical data,
mathematical models, or probability models (U.S. EPA, 1998). For this assessment, the
risk is stressor-linked, where the stressor is the release of naled to the environment. The
following risk hypotheses are presumed for this endangered species assessment:
• Labeled uses of naled within the action area may directly affect the CRLF by
causing mortality or by adversely affecting growth or fecundity;
• Labeled uses of naled within the action area may indirectly affect the CRLF by
reducing or changing the composition of food supply;
54
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• Labeled uses of naled 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 naled 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 naled 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 naled 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 naled 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 naled 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 naled 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 (naled), 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 Figure 6 and Figure 7, and the conceptual models for the
aquatic and terrestrial PCE components of critical habitat are shown in Figure 8 and
Figure 9. Exposure routes shown in dashed lines are not quantitatively considered
because the resulting exposures are expected to be so low as not to cause adverse effects
to the CRLF.
Figure 6 is a visual depiction of the Conceptual Model (CM) for the CRLF aquatic phase,
and Figure 8 represents the aquatic component of the CRLF habitat. The most likely
exposure routes are through spray drift/volatilization (limited-range atmospheric
transport) and runoff/erosion (surface transport). Infiltration into the soil is also possible,
55
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but rapid degradation of naled (and the major toxic degredate of concern, DDVP) make it
unlikely that significant amounts of the chemical(s) will enter groundwater. Similarly,
long-range atmospheric transport would appear possible because of several of the
application methods (aerial spraying of very fine droplets, ULV applications, airblast,
mist), but the non-persistence of naled and DDVP greatly decrease the likelihood of real
long-range transport. Indeed, all possible transport mechanisms are effectively limited by
rapid degradation/dissipation; however, multitudinous spray uses (crop and non-crop) and
the extent of land areas where spraying may occur, create conditions where naled/DDVP
can be detected in ambient atmospheric conditions - but this is more likely the result of
widespread spraying and movement of air masses than atmospheric persistence. The
same may be said for transport through runoff, but in this case the potentially impacted
areas are limited to those regions near where applications are made (assuming that any
air-transported material from distant application sites will be greatly 'diluted' by mixing
with intervening air masses, such that re-deposited chemical concentrations will be very
low). Thus, local atmospheric transport (spray drift/volatilization) is probably the
dominant exposure route, followed by runoff; other potential exposure routes should be
fairly negligible. The one notable exception, though, relates to spray applications directly
to water bodies. Although all labeled uses prohibit direct application to open water
bodies, there are specific uses (particularly, mosquito and fly control) where naled may
be applied to "swamps, stagnant water bodies, marshy areas, and vegetation alongside
surface waters." In these cases some naled is more likely to end up in surface water - but
even for these uses it is indicated that application should not be performed directly onto
open water bodies (presumably vegetated saturated areas are acceptable though).
Nevertheless, these areas may also serve as habitat for the CRLF aquatic phase.
Figure 7 depicts the CM for the CRLF terrestrial phase, and Figure 9 represents the CM
for the terrestrial component of the CRLF habitat. Likely exposure routes are similar to
those for the aquatic phase, for the same reasons as stated above. In this case, however,
the dominant terrestrial exposure route is likely to be direct application on-site; it is
expected that the highest terrestrial concentrations will be in those areas where naled is
applied directly to or above the land surface. Additionally, exposure can occur during
and immediately after application, so there is less attenuation than would result from the
time-lag required for conveyance to an off-site water body (that is, no degradation prior
to potential exposure - exposure can occur at 0 hours after application). This is highly
significant when assessing chemicals with low persistence.
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Figure 6. Conceptual Model for Pesticide Effects on Aquatic Phase of the Red-
Legged Frog
Figure 7. Conceptual Model for Pesticide Effects on Terrestrial Phase of Red-
Legged Frog
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Figure 8. Conceptual Model for Pesticide Effects on Aquatic Components of Red-
Legged Frog Critical Habitat
Figure 9. Conceptual Model for Pesticide Effects on Terrestrial Components of Red-
Legged Frog Critical Habitat
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2.10 Analysis Plan
In order to address the risk hypothesis, the potential for direct and indirect effects to the
CRLF, its prey, and its habitat is estimated. In the following sections, the use,
environmental fate, and ecological effects of naled are characterized and integrated to
assess the risks. This is accomplished using a risk quotient (ratio of exposure
concentration to effects concentration) approach. Although risk is often defined as the
likelihood and magnitude of adverse ecological effects, the risk quotient-based approach
does not provide a quantitative estimate of likelihood and/or magnitude of an adverse
effect. However, as outlined in the Overview Document (U.S. EPA, 2004), the
likelihood of effects to individual organisms from particular uses of naled is estimated
using the probit dose-response slope and either the level of concern (discussed below) or
actual calculated risk quotient value.
There are a number of labeled uses for naled not explicitly considered in this assessment.
There is no exposure pathway from indoor applications to the CRLF or its habitat and
therefore, indoor applications are determined to have No Effect on the CRLF. Agency
believes additional effects from other potential simultaneous uses occurring within the
same watershed - such as outdoor baits (Roach, Flies, etc.), hand-spray structural exterior
treatments, or applications to utility poles - that may be concurrent with widespread
aerial/ground spray operations will add negligibly to overall CRLF exposure and risk.
Outdoor baits are contained in small vessels (mixed with sugar solution) and are unlikely
to result in significant exposure to the CRLF; a determination of NLAA is assumed for
this use. Applications to utility poles or other inanimate objects entails applying very
small amounts ("6 square inches of material to each station" according to the label) at
discrete spots (poles) within large areas; total amounts applied per unit area will be very
low, so a NLAA determination is appropriate for this use. Spot treatments by hand spray
along structural perimeters is also very unlikely to result in significant impact to the
CRLF, its prey, or its habitat, as this usage does not favor surface runoff, widespread
spray drift or substantial volatilization (only a tiny fraction of land area is treated, and at
ground level); a NLAA determination is made for this use. Overall contributions from
these additional uses should be minor compared to the uses evaluated in this assessment;
Agency expects that additional loading within a catchment from these uses (indoor, bait
stations, perimeter treatments, etc.) should be minimal, even if such uses are concurrent
with more widespread and ubiquitous (modeled) uses. Similarly, the use of DDVP (toxic
degredate of concern resulting from naled use) as a separate active ingredient in other
(non-naled) products is not considered here, although any impact from DDVP
specifically associated with naled use is considered.
Exposure from nursery uses (bedding plants, foliage plants, outdoor nursery operations)
with label instructions to apply 0.9 lbs a.i./A "as needed" cannot be definitively
quantified or modeled due to vagueness of label language; a determination of LAA is
made because multiple applications (>3 per season) will result in several exceedences.
2.10.1 Exposure Analysis
59
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Direct effects to the aquatic phase CRLF will be assessed by comparing modeled surface
water exposure concentrations of naled and DDVP to acute and chronic (early life stage
hatching success and growth) effect concentrations for aquatic phase amphibians
(surrogate freshwater fish) from laboratory studies (see the Effects Analysis section
below). Effects to aquatic dietary food resources (fish, aquatic invertebrates, algae) of
the aquatic phase CRLF or effects to aquatic habitat that support the CRLF will also be
assessed by comparing modeled surface water exposure concentrations of total naled
residues to laboratory established effect levels appropriate for the taxa.
Surface water concentrations will be estimated using appropriate EFED aquatic exposure
models. Considering the wide variety of uses for naled, and the different application
methods (aerial spray, ground spray, hand spray, airblast, ULV, baiting) and settings
(application allowed in one form or another essentially throughout the entire state of
California) in which naled is applied, several models will be used for
estimating/predicting surface water naled concentrations. Ground spray applications are
to be modeled using PRZM-EXAMS and/or AgDRIFT, aerial spray with PRZM-
EXAMS, RICE Model, and/or AgDRIFT, and airblast modeled using AgDRIFT. Hand
spray and bait uses will not be modeled because they are not expected to contribute
significantly to total pesticide loading within a catchment or to independently adversely
affect the CRLF.
The method used to evaluate potential terrestrial exposure also considers 'total toxic
naled residues of concern' (naled + DDVP), but - because of differences between the
models (PRZM vs. T-REX) and how they process data - is estimated in a manner
different from that used in the aquatic exposure estimations. Specifically, the fate inputs
used for the PRZM-EXAMS aquatic exposure estimations reflect the characteristics of
both compounds (naled and DDVP), so the results should also represent aspects of both
chemicals. In practice, though, the important fate parameters of naled and DDVP are so
similar that changing the input values from one to the other does not appreciably alter the
aquatic model results; nevertheless, results presented in this document reflect combined
residues. To convert the PRZM-EXAMS EECs from |ig/L to |imoles/L, the relative
proportions of naled and DDVP (80% naled, 20% DDVP - based upon the highest
percent formation of DDVP observed in laboratory studies) were applied to the output
EEC values. In addition, correction was also made for differences in molecular weight.
Thus, the aquatic exposure estimations (in |imoles/L) should represent the relative
amounts of each compound that are likely to be found in the aquatic environment. The
method used to estimate relative terrestrial exposure to naled and DDVP (resulting from
naled use) is somewhat different. For these estimations, two separate T-REX model runs
were conducted for each application type/amount: one run was conducted assuming
100%) naled applied and 100%> of exposure as naled only (naled toxicity endpoints used),
and another run conducted assuming only 20% of chemical is applied (as DDVP),
corrected for molecular weight difference (with DDVP toxicity endpoints used). The
results of each set of 2 runs are compared (naled toxicity endpoints compared with DDVP
toxicity endpoints), and the most sensitive of the two is selected. Where results indicate
naled as the more sensitive endpoint, the assumption that 100% of terrestrial exposure is
to naled only is very conservative. However, when the DDVP endpoint is selected as the
60
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more sensitive, it may represent an under-estimation of true exposure to naled residues -
in this case, only 20% of total mass of applied chemical is considered. While this is
likely an over-estimation of actual DDVP exposure (since 20% conversion to DDVP is
the maximum observed, with most studies indicating a conversion of 12% or less), it fails
to account for the additional 80% of naled that is expected to be concurrent with 20%
DDVP. There is currently no acceptable method by which the Agency can evaluate
possible synergistic (or antagonistic) effects of simultaneous naled/DDVP exposure, but
it may be assumed that there is at least an additive effect - especially as both chemicals
have the same action (ChE inhibition). However, as potential additive effects cannot be
adequately quantified, it should simply be noted that for cases where DDVP terrestrial
exposure endpoints are used, there is less confidence that the most conservative possible
determination has been made.
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.
EECs for terrestrial plants inhabiting dry and wetland areas are derived using TerrPlant
(version 1.2.2, 12/26/2006). This model uses estimates of pesticides in runoff and in
spray drift to calculate EECs. EECs are based upon solubility, application rate and
minimum incorporation depth.
2.10.2 Effects Analysis
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 National Health and Environmental Effects
Research Laboratory's Mid-Continent Ecology Division.
The assessment of risk for direct effects to the terrestrial-phase CRLF makes the
assumption that toxicity of naled to birds is similar to or less than the toxicity to the
terrestrial-phase CRLF. The same assumption is made for fish and aquatic-phase CRLF.
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Algae, aquatic invertebrates, fish, and amphibians represent potential prey of the CRLF
in the aquatic habitat. Terrestrial invertebrates, small mammals, and terrestrial-phase
amphibians represent potential prey of the CRLF in the terrestrial habitat. Aquatic, semi-
aquatic, and terrestrial plants represent habitat of CRLF.
The acute measures of effect used for animals in this screening level assessment are the
LD50, LC50 and EC50. 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. LC stands for "Lethal Concentration" and LC50 is the concentration of a
chemical that is estimated to kill 50% of the test organisms. 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. NOAEL
stands for "No Ob served-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).
As previously discussed in Section 2.8.1 and 2.8.2, assessment endpoints for the CRLF
include direct toxic effects on survival, reproduction, and growth of the species itself, as
well as indirect effects, such as reduction of the prey base and/or modification of CRLF
habitat. Direct effects to the CRLF are based on toxicity information for freshwater fish
and birds, which are generally used as a surrogate for aquatic and terrestrial phase
amphibians, respectively. The open literature will be screened also for available
amphibian toxicity data. Indirect effects to the CRLF are assessed by looking at available
toxicity information relative to the CRLF's prey items and habitat requirements
(freshwater invertebrates, freshwater vertebrates, aquatic plants, terrestrial invertebrates,
terrestrial vertebrates, and terrestrial plants). Both guideline and open literature toxicity
data will be identified and evaluated for use in determining RQ values.
There are no submitted plant toxicity studies and no relevant plant toxicity studies were
found in the open literature for naled.
DDVP was found to be more toxic than naled to freshwater aquatic invertebrates on an
acute basis. There are minimal effects data for chronic DDVP exposure to freshwater
invertebrates, and there are acute and chronic data for saltwater invertebrates. These data
will be evaluated and compared to naled and DDVP freshwater aquatic invertebrate
toxicity endpoints.
2.10.3 Integration of Exposure and Effects
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Risk characterization is the integration of exposure and ecological effects characterization
to determine the potential ecological risk from agricultural and non-agricultural uses of
naled, 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 adverse ecological effects on non-target species. For the assessment of naled
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 Appendix
I).
For this endangered species assessment, listed species LOCs are used for comparing RQ
values for acute and chronic exposures of naled directly to the CRLF. If estimated
exposures directly to the CRLF of naled resulting from a particular use are sufficient to
exceed the listed species LOC, then the effects determination for that use is "may affect".
When considering indirect effects to the CRLF due to effects to animal prey (aquatic and
terrestrial invertebrates, fish, frogs, and mice), the listed species LOCs are also used. If
estimated exposures to CRLF prey of naled resulting from a particular use are sufficient
to exceed the listed species LOC, then the effects determination for that use is a "may
affect." If the RQ being considered also exceeds the non-listed species acute risk LOC,
then the effects determination is a LAA. If the acute RQ is between the listed species
LOC and the non-listed acute risk species LOC, then further lines of evidence (i.e.
probability of individual effects, species sensitivity distributions) are considered in
distinguishing between a determination of NLAA and a LAA. When considering indirect
effects to the CRLF due to effects to algae as dietary items or plants as habitat, the non-
listed species LOC for plants is used because the CRLF does not have an obligate
relationship with any particular aquatic and/or terrestrial plant. If the RQ being
considered for a particular use exceeds the non-listed species LOC for plants, the effects
determination is "may affect". Further information on LOCs is provided in Appendix C.
63
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3.0 Exposure Assessment
Naled is formulated as both a liquid (undiluted) and an emulsifiable concentrate.
Application equipment includes: ground spray application, aerial application, Ultra-Low
Volume (ULV), airblast, hand spray (spot treatments), and bait stations (mixed with
sugar water in open containers, or applied to poles, trees, etc. as gel). Risks from ground
boom and aerial applications are emphasized in this assessment because they are
expected to result in the highest off-target levels of naled due to generally higher spray
drift levels. Ground boom and aerial modes of application tend to use lower volumes of
application applied in finer sprays than other applications and thus have a higher potential
for off-target movement via spray drift.
3.1 Label Application Rates and Intervals
Label application rates and intervals are shown in Table 10. Crop types, scenarios, and
labeled application instructions are also shown in Table 10. Modeled application rates ,
intervals, application methods, and number of applications are given as well. Information
about runs performed using different aquatic exposure models (AgDrift, RICE Model) is
given in Table 11. Information provided in Table 11 is for model comparison purposes
only; results are not used in making risk determinations. Application rates and intervals
are highly variable, as this chemical has multitudinous uses: single application rates range
from 0.1 to 2.1 lb a.i./A, with intervals anywhere from 0-14 days.
All application rates/amounts cited here are "maximum rates" (except where noted) and
pertain to seasonal (not annual) application totals. This can be a significant distinction
for California, as there is often more than one crop cycle per year for some uses in this
region. However, since naled residues are very short-lived, repeated applications through
multiple crop cycles have negligible effects on resultant EEC values. Rather, the
application timing and amount applied in a single event have a much greater effect on
model results. Therefore, multiple crop cycles were not considered in this assessment;
but timing of applications was considered - application dates were assigned to each
scenario according to the part of the year when maximum application rates are likely and
also environmental impact greatest. In many cases, the highest aquatic exposure
estimates are obtained when both rainfall (initiating runoff) and spray drift are
contributing factors. This is most common for California in the spring and autumn
months; during summer there are typically fewer rain events, so essentially all
conveyance to water results solely from spray drift. In cases where applications can be
made throughout the year (or from spring through fall), an appropriate non-summer date
was selected for modeling; in other cases, maximum application rates are much more
likely only during summer, so a suitable summer application date was used. Application
dates are also given in Table 10.
64
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Table 10. Modeled Naled Uses.
PRZM Scenario
Uses
Covered
App.
Method(s)
App.
Rate(s)
(lbs
a.i./A)
# of
Apps.
App.
Intervals
(days)
Seasonal
Total
(lbs
a.i./A)
Application
Date
CA almond STD
almond,
walnut
Aerial
spray
1.9
2
8
3.8
Apr. 15
CA almond STD
almond,
walnut
Ground
spray
1.9
2
8
3.8
Apr. 15
CA citrus STD
orange,
lemon,
grapefruit,
tangerine
Aerial
spray
1.9
3
7
5.7
Apr. 15
orange,
Aerial
CA citrus STD
lemon,
grapefruit,
tangerine
spray
only*
(Ag Drift)
1.9
3
7
5.7
CA cole crop RLF
cabbage,
broccoli,
Aerial
spray
Mar. 15
("minimum"
application rate)
cauliflower,
collards,
kale
0.9
5
7
4.5
CA cole crop RLF
cabbage,
broccoli,
Ground
Mar. 15
("minimum"
cauliflower,
spray
0.9
5
7
4.5
application rate)
collards,
kale
cabbage,
broccoli,
Ground
spray
Mar. 15
CA cole crop RLF
cauliflower,
collards,
kale
1.9
5
7
9.5
cabbage,
broccoli,
Aerial
spray
Mar. 15
CA cole crop RLF
cauliflower,
collards,
kale
1.9
5
7
9.5
CA cotton STD
cotton
Aerial
spray
0.9
5
7
4.5
July 1
CA fruit STD
peaches
Ground
spray
1.9
1
1.9
June 1
CA grapes STD
grapes
Airblast*
(Ag Drift)
0.5
11
8
5.5
CA grapes STD
grapes
Ground
spray
0.5
11
8
5.5
May 1
Brussels
Aerial
spray
June 15
CA lettuce STD
sprouts,
Swiss chard
1.9
5
7
9.5
cantaloupes,
muskmelons,
May 15
CA melons RLF
melons,
eggplant,
summer
squash
Aerial
spray
1.4
4
7
5.6
65
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PRZM Scenario
Uses
Covered
App.
Method(s)
App.
Rate(s)
(lbs
a.i./A)
# of
Apps.
App.
Intervals
(days)
Seasonal
Total
(lbs
a.i./A)
Application
Date
CA Nursery
bedding
plant, foliage
plants,
outdoor
nursery ops.
Ground
spray only
0.9
"As
needed"
"As
needed"
Not
Modeled
(LAA
assumed)
CA row crop RLF
celery,
beans, peas
Ground
spray
1.4
5
7
7
Mar. 15
CA row crop RLF
celery,
beans, peas
Aerial
spray
1.4
5
7
7
Mar. 15
CA row crop RLF
peppers
Aerial
spray
1.9
3
7
5.7
Apr. 15
CA strawberry
(non plastic) RLF
strawberries
Aerial
spray
0.9
5
7
4.5
May 1
CA sugarbeet
sugar beets
Aerial
spray
0.9
5
7
4.5
May 1
CA wheat RLF
safflower
Aerial
spray
2.1
1
2.1
June 1
OR hops
hops
Aerial
spray
0.9
5
14
4.5
OR hops
hops
Ground
spray
0.9
5
14
4.5
May 1
CA forestry RLF
forestry
Aerial
spray
0.1
25
3
2.5
July 1
CA impervious
RLF
areas outside
bldgs.,
impervious
surfaces
Aerial
spray
0.1
25
3
2.5
Sep. 1
CA residential
RLF
residential
(including
lawns)
Aerial
spray
0.1
25
3
2.5
Sep. 1
CA turf RLF*
parks,
recreational
fields
CA rangeland hay
RLF
rangeland
Aerial
spray
1.1
25
3
2.5
Apr. 15
CA alfalfa
alfalfa
Aerial
spray
1.4
3
7
4.2
Mar. 15
* Not modeled - should be adequately represented (bounded) by residential/forestry/impervious
uses and other models (see below).
Table 11. Modeling Information for Runs Conducted with AgDrift and RICE Model.
Model Used
App. Rate(s)
App. Method(s)
Buffer
Uses Covered
(lbs a.i./A)
(feet)
AgDRIFT
1.9
Aerial spray
150-on label
orange
66
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Model Used
App. Rate(s)
(lbs a.i./A)
App. Method(s)
Buffer
(feet)
Uses Covered
(very fine)
lemon
grapefruit
tangerine
AgDRIFT
1.9
Ground spray
25 - on label
peaches
AgDRIFT
0.5
Airblast
50 - on label
grapes
AgDRIFT
0.9
Aerial spray
(very fine)
150 - on label
sugar beets
AgDRIFT
0.42
Aerial spray
(very fine)
10 - minimum
required,
from label
Horn flies
(rangeland)
AgDRIFT
0.25
Aerial spray
(very fine)
0 - applied
directly to water
(only allowable
non-buffer use)
Mosquitoes,
other flying insects
(swamp)
RICE MODEL
0.25
Aerial spray
applied directly to
water
Mosquitoes,
other flying insects
(swamp)
1 Uses assessed based on memorandum from SRRD
3.2 Aquatic Exposure Assessment
3.2.1 Conceptual Model of Exposure
The conceptual model of exposure envisions primarily aerial and ground spray
applications of very fine droplet size, allowing much of the chemical to remain suspended
aboveground for some time (as many applications are intended to control flying insects).
Thus, spray drift becomes a crucial component of exposure. Naled is expected to degrade
to the toxic degredate DDVP fairly quickly (< 1 day); however, the action and toxicity of
DDVP are such that it effectively functions much the same as parent naled.
Total toxic residues (naled + DDVP) are used to establish most chemical fate half-lives;
where degradation rates for DDVP were slower (hydrolysis, photolysis), the values for
DDVP were used as model inputs. Short half-lives for fate parameters obviate the need
to evaluate vadose zone storage and potential leaching to groundwater; terrestrial and
surface water environments are the dominant venues for potential non-target exposure.
Substantial amounts of naled and DDPV are likely available for runoff to surface waters
for only a few days post-application. Even though both these chemicals are mobile, they
have low persistence. If a runoff event occurs very soon (1-2 days) after an application
and if naled or DDVP is transported into surface water, naled will degrade rapidly (half-
life ~ 0.5 day) and DDVP will persist for slightly longer (half-life ~ 0.9 day). Therefore,
the impact of both of these chemicals on chronic surface water concentrations should be
minimal.
3.2.2 Existing Monitoring Data
There are no known targeted aquatic monitoring studies for naled in the U.S. Very few
have been identified internationally. Currently, only one known positive detection of
DDVP (degredate of naled, as well as a primary-use chemical and degredate of other
67
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compounds) in surface water has been reported in CA (2003); approximately 1600
samples were analyzed over a 13-year period (1992-2005).
Naled and DDVP have been detected in air monitoring studies, verifying that
atmospheric transport is a viable transmission mode for naled and DDVP. In a targeted
ambient air monitoring study in Tulare County, CA (June 1995), naled and DDVP were
both detected at elevated air concentrations following naled airblast application. Air
samples were collected before, during, and for 72 hours after application of naled to an
orange grove. Maximum air concentrations detected for naled and DDVP were 6.30
ug/m3 and 0.994 ug/m3, respectively. Moreover, naled was detected at measurable
concentrations (0.016 ug/m3) in samples taken prior to application, indicating that naled
residues can be carried across land catchments through the airshed. An earlier (non-
targeted) urban ambient air monitoring program in Tulare County in 1991 yielded lower
concentrations: 0.077 ug/m3 for naled and 0.059 ug/m3 for DDVP. However, model
results indicate that exposure risk is significantly greater for aerial (and ground) spray
applications than for orchard airblast, so these studies probably under-represent
atmospheric concentrations during and soon after spray applications. The relatively short
half-lives of both naled and DDVP help limit real mobility, but widespread and frequent
usage can allow background levels to persist in high-use areas during high-use periods
(such as during summer, when agricultural spraying is likeliest to occur simultaneously
and in proximity to other pest control operations).
3.2.3 Modeling Approach
Naled (and DDVP) aquatic exposure was assessed using the PRZM-EXAMS, AgDRIFT,
and RICE models. Spray applications (aerial and ground) were modeled with PRZM-
EXAMS and/or AgDRIFT, with the exception of mosquito/fly spraying directly onto
swamps, standing water, and riparian areas; this was the only usage also modeled with
the RICE model (all other uses require buffers around water bodies of 10-200 feet).
Because of the large number of potential uses for naled, uses were organized according to
application method, crop type, application rate, and usage pattern. A representative (or
surrogate) PRZM scenario was selected for each major use category, as appropriate. All
available appropriate scenarios were utilized, and paired with uses that included the
highest application rates for that category. Table 10 shows the crop type modeled, the
scenario appropriate for that crop, the label application rates, the label application
method(s), maximum number of applications per season (on label), the minimum labeled
interval allowed between applications, and the labeled maximum total amount that can be
used in one season. Model results are given in Tables 14 & 15.
Although all labels clearly state "Do not apply directly to water" there are specific
exceptions made for certain treatments; in particular, mosquito and fly control uses (e.g.,
Trumpet EC insecticide label states "Do not apply directly to water except when used
over water as labeled for adult mosquito, blackfly, or housefly control"; FLY KILLER D
and DIBROMlabels includes "swamps" as treatment sites for "adult mosquito, gnat, and
housefly control"). Thus, there are uses where direct application to water must be
modeled. For these applications, both the RICE and PRZM-EXAMS models were used.
68
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Since application is to be made directly onto or around water bodies, the PRZM-EXAMS
model was run with essentially the entire application amount considered as spray drift
deposited directly into the EPA 'standard pond' - 99% of applied naled was input as
spray drift in the model. Results from this PRZM-EXAMS method were consistent with
other uses (although, predictably, somewhat higher), while results from the RICE model
were an order of magnitude higher than all others. The results from the PRZM-EXAMS
model runs are used for making determinations in this assessment because it is believed
they are more accurate, since the RICE model does not consider the very rapid
degradation of naled/DDVP. The PRZM-EXAMS direct application to water modeling
method for mosquito/fly control was conducted for a single application at the maximum
rate (0.25 lb a.i./A) and for the maximum number of applications (25, at 3-day intervals)
at the maximum rate, as per label instructions.
3.2.3.1 Model Inputs
The PRZM-EXAMS model runs are intended to represent 'total naled residues' (naled +
DDVP), using the most conservative input values (naled or DDVP) where applicable:
naled input values for aerobic and anaerobic metabolic half-lives, DDVP for abiotic half-
lives and mobility inputs. Physical/chemical parameters for 'total naled residues' that
were used as inputs for the PRZM model runs are given in Table 12. However, since
both compounds appear to degrade/dissipate rapidly, it was often impractical to establish
a specific half-life for some parameters with any degree of certitude. The selection of
aerobic soil half-life of 3 days (3x single study showing half-life of about 1 day for
combined residues - MRID 00085408) was conservative insofar as degradation was too
rapid and data were inadequate to establish a time-series decay curve. In the absence of a
verifiable, suitable aerobic aquatic study, the naled aerobic soil half-life is multiplied by
two (as per Input Parameter Guidance Document). Specific inputs (application rates,
number of applications, application intervals) for each model run are listed in Table 10.
For all model input parameters, the most conservative reasonable estimate was used.
Test runs (not shown) of the PRZM-EXAMS model using different input parameters
(e.g., naled-only, DDVP-only) resulted in very little difference (<5%) in model output
values - not surprising, since both naled and DDVP degrade rapidly and have similar
physical/chemical properties (see Tables 2 & 3).
Table 12. PRZM-EXAMS Input Parameters for Naled (total toxic residues).
PARAMETER
VALUE
COMMENTS
Molecular Weight
381
Henry's Law Constant
5E-8
Vapor Pressure (torr)
1.2E-2
Solubility (mg/L)
15600
Koc
37
MRID 41354105
CAM
2
Spray
Application Efficiency
0.99 (ground)
0.95 (aerial)
Spray Drift
0.027 (ground)
0.12 (aerial)
0.227 (ULV)
CRLF guidelines
69
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PARAMETER
VALUE
COMMENTS
Hydrolysis (days)
pH 5 = 11.6
pH 7 = 5.2
pH 9 = 0.88
MRID 41723101
Aqueous Photolysis half-life (days)
10
MRID 43326601
Aerobic Aquatic half-life (days)
6
2X aerobic soil half-life
Anaerobic Aquatic half-life (days)
4.5
MRIDs 40618201, 41354102, 42445101
Aerobic Soil half-life (days)
3
MRID 00085408 - 3X single value of ~1 day
Since most naled uses entail spray applications of some type, often requiring ultra-fine
droplet sizes (with the intent that the chemical remain airborne), it is not sufficiently
protective to assume a default spray drift value of 1% for ground spray and 5% for aerial
spray. Naled labels contain instructions to include buffers of specific widths according to
type and method of application. The model AgDrift is used to obtain estimations of the
percentage of applied chemical that may be transported onto a nearby surface water body,
according to prescribed buffer width. Table 13 gives buffer widths for each major type of
naled use according to application method, and percentage of applied chemical that is
expected to reach a water body just beyond the buffer. Representative maximum
application rates, and AgDrift-estimated amounts 'applied' onto the water (as a result of
drift) are also shown. The spray drift percentages are then used instead of the PRZM
default values, and the PRZM-EXAMS model is run with the appropriate recalculated
spray drift percent input (see Table 13). For 'swamp' uses, it was assumed that
essentially all the applied chemical went directly into the water body, so a spray drift
input value of 0.99 (99%) in PRZM was used.
Table 13 Buffer Widths for Naled Uses, and Spray Drift Calculated from AgDrift.
ADDlication TvDe:
ADDlication
Method:
ADDlication
Rate (Ib/ac):
Buffer Width (ft):
% SDrav
Drift:
ADDlication
Estimate (lb/ac):
Ag. (e.g., citrus)
Air spray
1.9
150
12
0.229
Orchard
Ground
spray
1.9
25
2.7
0.051
Vineyard
Airblast
0.5
50
0.6
0.003
Ag (e.g.,
sugarbeets)
Air spray
0.9
150
12
0.108
Range (flies)
Air spray
0.42
10
22.7
0.095
3.2.3.2 Results
Results from PRZM model runs are shown in Table 14. Results for runs conducted using
the default spray drift settings (1% for ground, 5% for aerial) are shown, along with
results from the same scenarios using the AgDRIFT-derived spray drift estimates (in
bold). The bold numbers in Table 14 are used for calculating exposure and effects, and
for making determinations. Table 15 provides the results for runs conducted using
AgDrift and RICE Model; however, these data are presented merely for characterization
and comparison with PRZM model results and are neither used for making
determinations nor discussed further in the text.
All aquatic EECs presented here were also converted into units of micromolesper liter
(|imole/L). Since the initial EEC values were obtained using model inputs reflecting total
70
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naled residues (naled + DDVP), the unit conversion to micromoles also represents total
residues. The initial assumption is that 20% of naled is converted to DDVP - the
maximum amount converted in approved registrant studies. As this represents the upper
bound of expected transformation to DDVP, and DDVP is often more toxic than parent
naled, this assumption is conservative and should yield a high-end exposure value. The
conversions were calculated using the following formula:
["EEC" (micromoles/liter)] equals [(EEC (micrograms/liter) divided by molecular weight of naled) x 80%]
plus [(EEC (micrograms/liter) divided by molecular weight of DDVP) x 20%]
or
Hmole/L = ((EEC (ug/L) / 381)*0.8) + ((EEC (ug/L) / 221)*0.2)
Table 14. Results from PRZM Model Runs
PRZM
Scenario
Uses
Covered
App.
Method(s)
Peak
EEC
(PPb)
96
hour
EEC
DDb
11
Day
EEC
DDb
60
Day
EEC
DDb
Peak
EEC
(umol
es/L)
96 hour
EEC
(umolc/
L)
21 Dav
EEC
(umolc/
LI
60 Dav
EEC
(umolc/
L)
CA almond
STD
almond,
walnut
Aerial spray
6.29
3.54
1.73
0.62
0.019
0.011
0.005
0.002
CA
almond
STD
almond,
walnut
Air spray
(with 12%
spray drift)
16.2
11.54
6.51
2.42
0.049
0.035
0.020
0.007
CA almond
STD
almond,
walnut
ground
spray only
3.23
1.7
0.54
0.24
0.010
0.005
0.002
0.001
CA
almond
STD
almond,
walnut
Ground
spray (with
2.7% spray
drift)
4.79
3.27
1.76
0.76
0.014
0.010
0.005
0.002
CA citrus
STD
orange,
lemon,
grapefruit,
tangerine
Aerial spray
7.21
3.8
2.05
0.76
0.022
0.011
0.006
0.002
CA citrus
STD
orange,
lemon,
grapefrui
t,
tangerine
Air spray
(with 12%
spray drift)
17.54
12.22
8.5
3.29
0.053
0.037
0.026
0.010
CA cole
crop RLF
cabbage,
broccoli,
cauliflowe
r, collards,
kale
Aerial
spray
7.9
4.6
2.24
1.25
0.024
0.014
0.007
0.004
CA cole
crop RLF
cabbage,
broccoli,
cauliflow
er,
collards,
kale
Air (with
12% spray
drift)
11.69
8.6
6.29
3.77
0.035
0.026
0.019
0.011
71
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PRZM
Scenario
Uses
Covered
App.
Method(s)
Peak
EEC
(PPb)
96
hour
EEC
DDb
11
Day
EEC
DDb
60
Day
EEC
DDb
Peak
EEC
(umol
es/L)
96 hour
EEC
(umole/
L)
21 Dav
EEC
(umole/
LI
60 Dav
EEC
(umole/
L)
CA cole
crop RLF
cabbage,
broccoli,
cauliflowe
r, collards,
kale
Ground
spray only
6.11
3.55
1.38
0.73
0.018
0.011
0.004
0.002
CA cole
crop RLF
cabbage,
broccoli,
cauliflow
er,
collards,
kale
Ground
spray (with
2.7% spray
drift)
6.98
5.02
2.82
1.65
0.021
0.015
0.008
0.005
CA cole
crop RLF
cabbage,
broccoli,
cauliflowe
r, collards,
kale
ground
spray only
12.88
7.49
2.91
1.55
0.039
0.023
0.009
0.005
CA cole
crop RLF
cabbage,
broccoli,
cauliflow
er,
collards,
kale
Ground
spray (with
2.7% spray
drift)
14.71
10.59
5.94
3.49
0.044
0.032
0.018
0.010
CA cole
crop RLF
cabbage,
broccoli,
cauliflowe
r, collards,
kale
Aerial spray
16.66
9.69
4.72
2.64
0.050
0.029
0.014
0.008
CA cole
crop RLF
cabbage,
broccoli,
cauliflow
er,
collards,
kale
Air (with
12% spray
drift)
24.66
18.41
13.26
7.95
0.074
0.055
0.040
0.024
CA cotton
STD
cotton
Aerial spray
11.7
5.09
1.14
0.53
0.035
0.015
0.003
0.002
CA cotton
STD
cotton
Air spray
(with 12%
spray drift)
11.68
7.26
5.13
2.99
0.035
0.022
0.015
0.009
CA fruit
STD
peaches
Ground
spray
1.07
0.4
0.08
0.03
0.003
0.001
0.000
0.000
CA fruit
STD
peaches
Ground
spray (with
2.7% spray
drift)
3.35
2.18
0.74
0.26
0.010
0.007
0.002
0.001
CA grapes
STD
grapes
Airblast
0.02
NA
NA
NA
0.000
CA grapes
STD
grapes
Ground
spray
0.29
0.14
0.1
0.08
0.001
0.000
0.000
0.000
CA grapes
STD
grapes
Ground
spray (with
2.7% spray
0.93
0.64
0.48
0.43
0.003
0.002
0.001
0.001
72
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PRZM
Scenario
Uses
Covered
App.
Method(s)
Peak
EEC
(PPb)
96
hour
EEC
DDb
11
Day
EEC
DDb
60
Day
EEC
DDb
Peak
EEC
(umol
cs/L)
96 hour
EEC
(umolc/
L)
21 Dav
EEC
(umolc/
LI
60 Dav
EEC
(umolc/
L)
drift)
CA lettuce
STD
Brussels
sprouts,
Swiss
chard
Aerial spray
5.84
3.18
2.17
1.26
0.018
0.010
0.007
0.004
CA lettuce
STD
Brussels
sprouts,
Swiss
chard
Aerial
spray (with
12% spray
drift)
17.24
12.05
9.44
5.56
0.052
0.036
0.028
0.017
CA melons
RLF
cantaloup
es,
muskmelo
ns,
melons,
eggplant,
summer
squash
Aerial spray
4.15
2.13
1.32
0.57
0.012
0.006
0.004
0.002
CA melons
RLF
cantaloup
es,
muskmel
ons,
melons,
eggplant,
summer
squash
Aerial
spray (with
12% spray
drift)
12.61
8.58
6.06
2.83
0.038
0.026
0.018
0.009
CA row
crop RLF
beans,
peas,
celery
Ground
spray
6.52
3.88
1.57
0.69
0.020
0.012
0.005
0.002
CA row
crop RLF
beans,
peas,
celery
Ground
spray (with
2.7% spray
drift)
7.87
6.12
3.62
1.8
0.024
0.018
0.011
0.005
CA row
crop RLF
beans,
peas,
celery
Aerial Spray
7.49
5.3
2.95
1.51
0.023
0.016
0.009
0.005
CA row
crop RLF
beans,
peas,
celery
Aerial
Spray (with
12% spray
drift)
16.86
12.02
9.2
5.12
0.051
0.036
0.028
0.015
CA row
crop RLF
peppers
Aerial spray,
7.48
4.67
2.72
0.98
0.022
0.014
0.008
0.003
CA row
crop RLF
peppers
Aerial
spray (with
12% spray
drift)
17.49
12.48
8.94
3.52
0.053
0.037
0.027
0.011
CA
strawberry
strawberri
es
Aerial spray
9.08
4.68
1.71
0.99
0.027
0.014
0.005
0.003
73
-------
PRZM
Scenario
Uses
Covered
App.
Method(s)
Peak
EEC
96
hour
11
Day
60
Day
Peak
EEC
96 hour
EEC
21 Dav
EEC
60 Dav
EEC
(PPb)
EEC
DDb
EEC
DDb
EEC
DDb
(umol
es/L)
(umole/
L)
(umole/
L)
(umole/
L)
(non
plastic)
RLF
CA
strawberr
Aerial
8.52
6.02
4.72
2.88
0.026
0.018
0.014
0.009
strawberry
(non
plastic)
RLF
ies
spray (with
12% spray
drift)
CA wheat
safflower
Aerial spray
5.87
2.49
0.54
0.19
0.018
0.007
0.002
0.001
RLF
CA wheat
safflower
Aerial
22.46
9.28
2.39
0.84
0.067
0.028
0.007
0.003
RLF
spray (with
12% spray
drift)
OR hops
hops
Aerial spray
3.55
1.99
0.88
0.67
0.011
0.006
0.003
0.002
OR hops
hops
Aerial
spray (with
12% spray
drift)
7.1
5.04
3.08
2.57
0.021
0.015
0.009
0.008
OR hops
hops
Ground
spray
2.43
1.34
0.42
0.22
0.007
0.004
0.001
0.001
OR hops
hops
Ground
spray (with
2.7% spray
drift)
2.86
2.23
1
0.74
0.009
0.007
0.003
0.002
CA
Mosquito
* Aerial
6.78
4.72
2.64
0.97
0.020
0.014
0.008
0.003
rangeland
hay
es, Flies,
etc.
spray (with
22.7%
drift)
CA
Mosquito
* Aerial
10.46
7.79
4.17
3.15
0.031
0.023
0.013
0.009
forestry
es, Flies,
etc.
spray (with
22.7%
drift)
CA
Mosquito
* Aerial
10.28
7.55
4.62
3.32
0.031
0.023
0.014
0.010
impervious
es, Flies,
etc.
spray (with
22.7%
drift)
CA
Mosquito
* Aerial
3.5
2.7
2.42
2.33
0.011
0.008
0.007
0.007
residential
es, Flies,
etc.
spray (with
22.7%
drift)
CA
"swamp"
* Aerial
13.85
9.81
3.5
1.25
0.042
0.029
0.011
0.004
forestry RL
F (single
appl.)
spray (with
99% drift)
CA
"swamp"
* Aerial
32.78
26.46
25.17
24.84
0.098
0.080
0.076
0.075
forestry RL
F (25 apps,
spray (with
99% drift)
3-day
intervals)
74
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PRZM
Scenario
Uses
Covered
App.
Mcthod(s)
Peak
EEC
(PPb)
96
hour
EEC
DDb
11
Day
EEC
DDb
60
Day
EEC
DDb
Peak
EEC
(umol
es/L)
96 hour
EEC
(umole/
L)
21 Dav
EEC
(umole/
LI
60 Dav
EEC
(umole/
L)
CA
sugarbeet
sugar
beets
Ground
spray (with
2.7% spray
drift)
1.99
1.36
1.00
0.56
0.006
0.004
0.003
0.002
CA alfalfa
alfalfa
Aerial
spray (with
12% spray
drift)
14.39
10.44
7.22
3.00
0.043
0.031
0.022
0.009
Table 15. Results from Other (non-PRZM) Model Runs.
Model Used
Add. Rate(s) (lbs
a.i./A)
Add. Method(s)
Buffer (feet)
Uses Covered
Peak (DDb)
AgDRIFT
1.9
Aerial spray
(very fine)
150 - on label
orange, lemon,
grapefruit,
tangerine
4.17
AgDRIFT
1.9
Ground spray
25 - on label
peaches
2.84
AgDRIFT
0.5
Airblast
50 - on label
grapes
0.02
AgDRIFT
0.9
Aerial spray
(very fine)
150 - on label
sugar beets
6.07
AgDRIFT
0.42
Aerial spray
(very fine)
10 - minimum
required, from
label
Horn flies
(rangeland)
5.31
AgDRIFT
0.25
Aerial spray
(very fine)
0 - applied
directly to water
(only non-buffer
use allowed on
label)
Mosquitoes, other
flying insects
(swamp)
3.40
AgDRIFT
1.25
Aerial spray
(very fine)
1 - applied
directly to water
(only non-buffer
use allowed on
label)
Mosquitoes, other
flying insects
(swamp)
5.10
RICE
MODEL
0.25
Aerial spray
applied directly
to water
Mosquitoes, other
flying insects
(swamp)
239
75
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3.2.4 Additional Modeling Exercises Used to Characterize Potential
Exposures
3.2.4.1 Residential Uses (Impact of overspray and Impervious Surfaces)
Aerial and ground spray applications to residential areas (including impervious surfaces)
for flying insect (mosquitoes, flies, etc.) control were modeled in this assessment (see
Tables 14 & 15). Generally, these uses produced higher EECs when modeled in
residential and forested areas than when modeled for the same uses in crop-type
scenarios. However, these uses did not produce the highest calculated EECs in this
assessment - probably because application rates were lower than for some other (mostly
'agricultural') uses.
3.2.4.2 Comparison of Modeled EECs with Available Monitoring Data
There were insufficient monitoring data with which to compare modeling results.
3.2.5 Modeling with Typical Usage Information
A wide range of different uses, scenarios, and application rates was utilized in this
assessment. In addition to all model runs using maximum application rates (and
maximum number of applications, minimum application intervals), the cabbage, broccoli,
etc. usage (CA cole crop scenario) label directions state a 'minimum' application rate of
0.9 lb a.i./A. This permutation was also modeled, to give an idea (in the absence of hard
data) of what possible "typical" (or "minimum") usage might produce. The array of
model results presented here should roughly encompass the range of exposure values that
might be expected in a variety of settings for most naled uses. These results are shown in
Table 11.
3.2.6 Summary of Modeling vs. Monitoring Data
There were insufficient monitoring data with which to compare modeling results. A
comprehensive, targeted monitoring study of several years' duration would be required to
adequately compare monitoring and modeling data.
3.3 Terrestrial Exposure
3.3.1 Terrestrial Animal Exposure Assessment
T-REX (Version 1.3.1) is used to calculate dietary and dose-based EECs of naled and
DDVP for the CRLF and its potential prey (e.g. small mammals and terrestrial insects)
inhabiting terrestrial areas. EECs used to represent the CRLF are also used to represent
exposure values for frogs serving as potential prey of CRLF adults. T-REX simulates a 1-
year time period. For this assessment spray applications of naled are considered, as
discussed in below.
Terrestrial EECs for foliar formulations of naled were derived for the uses summarized
in.Table 17, Table 18, Table 19, Table 20, and Table 21. A foliar dissipation half-life
study was not available for naled or DDVP, however, naled studies indicate a field
dissipation half-life of greater than one day. Therefore, a foliar dissipation half life of 2
76
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days will be used as the input value for the TREX model. Since both chemicals exhibit
similar behavior in the environment, the same value will be used for naled and DDVP.
Use specific input values, including number of applications, application rate and
application interval are provided in Table 16. An example output from T-REX is
available in Appendix C.
In lieu of submitted data regarding foliar dissipation half-lives, a half-life of 2 days was
extrapolated from field dissipation studies (MRID # 40494101, 40976401, 40976402 and
41354107, 40304301 and 41354108). Initial screening revealed that the EEC value
calculated by the T-REX model is more sensitive to application rate and frequency than
to the number of applications. To adequately address the risk from all uses, they were
first grouped by the maximum allowable one time application rate then by the number of
applications and the application interval. The similar scenarios were grouped and
numbered 1 through 9, with Scenario 1 having the highest one-time application rate. The
table below (Table 16) includes the uses, rates, frequency and scenario number.
Table 16. Input Parameters for Foliar Applications Used to Derive Terrestrial
EECs for Naled with T-REX , Application Scenarios Used in TREX to get a Baseline
Risk Value for Each Use
Scenario
Scenario
Summary
Rate
(lbs
a.i./A)
# of
Applications
Application
Interval
(Days)
Uses
1
Safflower (2.1
lbs ai/a, 1
application)
2.1
1
7
Safflower
2
Cole crops,
tree nuts, citrus
(1.9 lbs ai/A, 1
application)
1.9
1
7
almond, broccoli, cabbage,
cauliflower, Brussels sprouts,
kale, and collards, eggplant,
peppers, oranges, lemons,
grapefruit, tangerines, peaches,
summer squash, walnuts
3
Alfalfa, row
crops, cotton
(1.4 lbs ai/A, 1
application)
1.4
1
7
alfalfa, beans, lima beans, and
peas, celery, cotton,
4
Melons, misc
food and non-
food plants
(0.9 lbs ai/A, 1
application)
0.9
1
7
Beans (aerial), cantaloupes,
muskmelons, hops, melons grown
for seed, grapes, strawberries,
sugar beets, Swiss chard, forest
and shade trees, ornamental
shrubs and flowering plants
5
Non-food
plants (0.9 lbs
ai/A, 52
applications, 7
day interval)
0.9
52
7
forest and shade trees, ornamental
shrubs and flowering plants
6
Non-food
plants (0.9 lbs
ai/A, 104
applications, 3
day interval)
0.9
104
3
forest and shade trees, ornamental
shrubs and flowering plants
77
-------
Scenario
Scenario
Summary
Rate
(lbs
a.i./A)
# of
Applications
Application
Interval
(Days)
Uses
7
Insect pests-
animal and
human health
concerns
(0.25 lbs ai/A,
2 applications,
7 day interval)
0.25
2
7
Swamps and pastures, for
reduction of livestock pests in
confined animal feeding
operations (0.2 aerial, 0.25 by
ground)
8
Insect pests-
animal and
human health
concerns
(0.1 lbs ai/A, 2
applications, 1
day interval)
0.1
2
1
in and around food processing
plants, loading docks, cull piles,
refuse areas, or reduction of
rangeland pests, residential areas,
municipalities, tidal marshes,
swamps, woodlands, and
agricultural areas, livestock areas
including dairy cattle
9
Insect pests-
animal and
human health
concerns
(0.1 lbs ai/A, 2
applications, 7
day interval)
0.1
2
7
in and around food processing
plants, loading docks, cull piles,
refuse areas, reduction of
rangeland pests, residential areas,
municipalities, tidal marshes,
swamps, woodlands, and
agricultural areas, livestock areas
including dairy cattle
The use scenarios were modeled using T-REX v. 1.3.1. The modeling results include
estimated environmental concentrations (EEC) based on dose or dietary concentrations.
T-REX is also used to calculate EECs for terrestrial insects exposed to naled. Dietary-
based EECs calculated by T-REX for small and large insects (units of a.i./g) are used to
bound an estimate of exposure to bees. Available acute contact toxicity data for bees
exposed to naled (in units of |ig a.i./bee), are converted to |ig a.i./g (of bee) by
multiplying by 1 bee/0.128 g. The EECs are later compared to the adjusted acute contact
toxicity data for bees in order to derive RQs. Because naled is highly toxic to terrestrial
invertebrates, it is unnecessary to consider the toxicity of DDVP, as it will not affect the
risk conclusion.
For modeling purposes, exposures of the CRLF to naled 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 (Table 17) and its potential prey (Table 18 and Table 19). .
The three tables below are the T-TEX results relevant to the terrestrial phase CRLF. The
first table includes dose, dietary and chronic based EEC values which will be compared
to avian toxicity data to calculate RQ values used to assess direct effects to the CRLF.
78
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Table 17. Upper-bound Kenega Nomogram EECs (ppm) for Dietary- and Dose-based
Exposures of the CRLF and its Prey to Naled
Scenario (20 g bird
consuming small
insects)
Scenario Summary
EEC Acute Dose
based frog (avian)
EEC Acute Dietary
and Chronic Dose
based frog (avian)
1
Safflower (2.1 lbs
ai/a, 1 application)
322.9
283.5
2
Cole crops, tree nuts,
citrus (1.9 lbs ai/A, 1
application)
292.1
256.5
3
Alfalfa, row crops,
cotton (1.4 lbs ai/A, 1
application)
215.3
189
4
Melons, misc food
and non-food plants
(0.9 lbs ai/A, 1
application)
138.4
121.5
5
Non-food plants (0.9
lbs ai/A, 52
applications, 7 day
interval)
151.8
133.3
6
Non-food plants (0.9
lbs ai/A, 104
applications, 3 day
interval)
214.1
188.0
7
Insect pests-animal
and human health
concerns (0.25 lbs
ai/A, 2 applications, 7
day interval)
41.84
36.73
8
Insect pests-animal
and human health
concerns (0.1 lbs ai/A,
2 applications, 1 day
interval)
26.25
23.05
9
Insect pests-animal
and human health
concerns (0.1 lbs ai/A,
2 applications, 7 day
interval)
16.73
14.69
The next table presents EEC values for small and large insects as part of the CRLF diet.
These values will be compared against terrestrial invertebrate toxicity data to assess if
insects, a prey item for the CRLF, will be adversely affected by naled use, thus indirectly
affecting the CRLF.
79
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Table 18. Naled EECs (ppm) for Indirect Effects to the Terrestrial-Phase CRLF via
Effects to Terrestrial Invertebrate Prey Items
Scenario
(Naled)
Scenario Summary
Rate
Number of
Applications
Small Insects
Large Insects
1
Safflower (2.1 lbs ai/a, 1
application)
2.1
1
283.50
31.50
2
Cole crops, tree nuts, citrus
(1.9 lbs ai/A, 1 application)
1.9
1
256.50
28.50
3
Alfalfa, row crops, cotton
(1.4 lbs ai/A, 1 application)
1.4
1
189.00
21.00
4
Melons, misc food and non-
food plants (0.9 lbs ai/A, 1
application)
0.9
1
121.50
13.50
5
Non-food plants (0.9 lbs ai/A,
52 applications, 7 day interval)
0.9
52
133.28
14.81
6
Non-food plants (0.9 lbs ai/A,
104 applications, 3 day
interval)
0.9
104
187.95
20.88
7
Insect pests-animal and human
health concerns
(0.25 lbs ai/A, 2 applications, 7
day interval)
0.25
2
36.73
4.08
8
Insect pests-animal and human
health concerns
(0.1 lbs ai/A, 2 applications, 1
day interval)
0.1
2
23.05
2.56
9
Insect pests-animal and human
health concerns
(0.1 lbs ai/A, 2 applications, 7
day interval)
0.1
2
14.69
1.63
Table 19. DDVP EECs (ppm) for Indirect Effects to the Terrestrial-Phase CRLF via
Effects to Terrestrial Invertebrate Prey Items
Scenario
(DDVP)
Scenario Summary
Rate
Number of
Applications
Small
Insects
Large
Insects
1
Safflower (2.1 lbs ai/a, 1
application)
0.24
1
32.83
3.65
2
Cole crops, tree nuts,
citrus (1.9 lbs ai/A, 1
application)
0.22
1
29.70
3.30
3
Alfalfa, row crops,
cotton (1.4 lbs ai/A, 1
application)
0.16
1
21.88
2.43
4
Melons, misc food and
non-food plants (0.9 lbs
ai/A, 1 application)
0.10
1
14.07
1.56
5
Non-food plants (0.9 lbs
ai/A, 52 applications, 7
day interval)
0.10
52
15.43
1.71
80
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Scenario
(DDVP)
Scenario Summary
Rate
Number of
Applications
Small
Insects
Large
Insects
6
Non-food plants (0.9 lbs
ai/A, 104 applications, 3
day interval)
0.10
104
21.76
2.42
7
Insect pests-animal and
human health concerns
(0.25 lbs ai/A, 2
applications, 7 day
interval)
0.03
2
4.25
0.47
8
Insect pests-animal and
human health concerns
(0.1 lbs ai/A, 2
applications, 1 day
interval)
0.01
2
2.67
0.30
9
Insect pests-animal and
human health concerns
(0.1 lbs ai/A, 2
applications, 7 day
interval)
0.01
2
1.70
0.19
The third table includes acute and chronic EEC values for small mammals, a part of the
CRLF diet. The EEC values will be compared to mammalian toxicity endpoints to assess
risk to the CRLF via indirect effects mediated by adverse effects to prey items.
Table 20. Mammalian EECs (ppm), as Modeled by T-REX to Assess Potential for
Indirect Effects to CRLF
Scenario (15 g
mammal eating
small insects)
Scenario Summary
Acute and Chronic Dose based
small mammals EEC
1
Safflower (2.1 lbs ai/a, 1 application)
480.53
2
Cole crops, tree nuts, citrus (1.9 lbs
ai/A, 1 application)
434.76
3
Alfalfa, row crops, cotton (1.4 lbs
ai/A, 1 application)
320.35
4
Melons, misc food and non-food
plants (0.9 lbs ai/A, 1 application)
205.94
5
Non-food plants (0.9 lbs ai/A, 52
applications, 7 day interval)
225.91
6
Non-food plants (0.9 lbs ai/A, 104
applications, 3 day interval)
318.57
7
Insect pests-animal and human health
concerns (0.25 lbs ai/A, 2
applications, 7 day interval)
62.26
8
Insect pests-animal and human health
concerns (0.1 lbs ai/A, 2 applications,
1 day interval)
39.06
9
Insect pests-animal and human health
concerns (0.1 lbs ai/A, 2 applications,
7 day interval)
24.90
81
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3.3 Terrestrial Plant Exposure Assessment
TerrPlant (Version 1.1.2) is used to calculate EECs for non-target plant species inhabiting
dry and semi-aquatic areas. Parameter values for application rate, drift assumption and
incorporation depth are based upon the use and related application method (Table 21). A
runoff value of 5% is utilized based on naled's solubility, which is classified by TerrPlant
as 15600 mg/L. For aerial and ground application methods, drift is assumed to be 5%
and 1%, respectively. EECs relevant to terrestrial plants consider pesticide
concentrations in drift and in runoff. These EECs are listed by use in Table 21. An
example output from TerrPlant v. 1.2.2 is available in Appendix F.
Table 21. TerrPlant Inputs and Resulting EECs (lbs a.i./A) for Plants Inhabiting Dry and
Semi-aquatic Areas Exposed to naled via Runoff and Drift
3.4 Spray Drift Modeling
Many naled uses, especially aerially-applied spray and ULV applications, are prone to
spray drift. This is consistent with many of the intended uses on flying insects, where it
is desirable that naled remain suspended in the atmosphere for a length of time sufficient
82
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to kill insects in flight. The real limit to naled/DDVP mobility in these cases is the rapid
degradation and dissipation of naled residues. However, considering the very fine droplet
sizes recommended for these uses, it is expected that some drift to non-target areas will
occur. For many of these types of uses, modeling was conducted using both the PRZM-
EXAMS model (with the spray drift fraction set for 5%) and the AgDrift model (with
appropriate buffer widths and application amounts - as per label instructions - included).
Results from both these models were very similar when compared for the same uses.
Ultimately, though, results from PRZM-EXAMS model runs where AgDRIFT-derived
percent spray drift values were substituted for the default values were used for making
effects determinations. Although there is an option to use the Gaussian extension to
predict the full distance that might be affected by a spray drift event, this should not be
necessary. Usage patterns allow that the same applications may be performed in
neighboring catchments at the same time essentially anywhere in California; considered
alongside the non-persistent characteristics of naled (which are not accounted for in the
Gaussian extension to the spray drift model), exposure in nearby areas will more likely be
higher as a result of local spraying than from long-range drift. Any potential
contributions from long-range drift should add negligibly to exposure resulting from local
spray applications
83
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4.0 Effects Assessment
The effects assessment characterizes the types of effects naled and it's degredate of
concern, DDVP, have on organisms when exposed at various levels. This
characterization is based on registrant-submitted toxicity studies and a comprehensive
review of the open literature on naled and DDVP toxicity and effects. Where data are
sufficient, acute probit dose- or concentration-response relationships are evaluated to
establish the probability of an individual effect (listed species) or the effect to a
proportion of exposed individuals (non-listed organisms). To further refine the
characterization of potential ecological effects associated naled use, reported incidents
from the Ecological Incident Information System (EIIS) are reviewed.
A summary of the available ecotoxicity information and probit dose- or concentration-
response relationships, and the incident information for naled technical grade active
ingredient (TGAI) and formulated product are provided in Sections 4.1 through 4.4,
respectively. A detailed summary of the available ecotoxicity information for naled and
DDVP TGAI and formulated product is presented in Appendix A.
Toxicity endpoints used to estimate risk are 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 ECOTOX.
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 for inclusion in that database are further screened
(U.S. EPA 2004), and then evaluated for scientific soundness and applicability to
estimating or characterizing risk along with the registrant-submitted data, and may be
incorporated qualitatively or quantitatively into this endangered species assessment.
Studies in ECOTOX were screened using a check list for ecological toxicity data outlined
by EPA (USEPA, 2004) and developed in conjunction with the Services. Criteria include
public literature studies with measurement endpoints commensurate with guideline
studies, maintaining proper organism survival in a control treatment, testing only with
healthy, unstressed organisms, and using appropriate testing procedures. Results from
studies, where the test descriptions did not contain sufficient information to evaluate
these fundamentals, were not used. The degree to which open literature data are
84
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quantitatively or qualitatively characterized is dependent on whether the information is
relevant to the direct and indirect assessment endpoints identified for this assessment
{i.e., maintenance of CRLF survival, reproduction, and growth) as identified in Section
2.8. For example, endpoints such as behavior modifications are likely to be qualitatively
evaluated, because quantitative relationships between modifications and reduction in
species survival, reproduction, and/or growth are not generally available.
Citations of all open literature not considered as part of this assessment are listed in
Appendix H for those rejected for inclusion in ECOTOX, for those that did not pass an
initial screen of the ECOTOX data (U.S. EPA 2004b), and for those that passed the initial
screen but were not used quantitatively (e.g., the endpoint is less sensitive and/or not
appropriate for use in this assessment). Also included is the rationale for why a specific
literature source was rejected for inclusion in ECOTOX, why it did not pass the
ECOTOX screen, or why it was not used, at least quantitatively, as part of this
endangered species risk assessment, respectively. The chemicals included in the CRLF
assessments were placed in a queue in preparation for the staggered deadlines. Because
DDVP is being assessed in the context that it is a degredate of naled, a formal OPP
ECOTOX run was not conducted for DDVP. However, the publicly accessible ECOTOX
database was surveyed for DDVP toxicity data and several studies were reviewed.
As described in the analysis plan, naled is rapidly converted to the toxic degredate
DDVP, and to assess the risk from naled uses exposure was estimated using a total
residues approach. For the aquatic phase CRLF assessment, the toxicity of naled and
DDVP are compared and the chemical that is most toxic to each taxa is used in the risk
equations. The comparison was performed by first determining, for each taxa, the most
sensitive endpoint for each chemical. Next for comparison, these values were normalized
to micromoles (i.e., 380.84 |ig of naled = 1 |imole of naled and 221 |ig of DDVP = 1
limole of DDVP). For terrestrial RQ calculations the EEC values are compared to both
the naled and DDVP toxicity endpoints as described in the Problem Formulation section.
Based on the available data, naled is classified as highly toxic to freshwater fish and very
highly toxic to freshwater invertebrates. Naled is classified as slightly toxic to birds on a
sub-acute, dietary basis. On an acute basis, naled is classified as moderately to highly
toxic to birds, reptiles, and terrestrial-phase amphibians. Naled is classified as highly
toxic to insects and moderately toxic to mammals, on an acute basis.
The results of aquatic plant toxicity testing found naled toxicity to range from 22 ppb a.i.
for non-vascular aquatic plants up to 1,800 ppb for vascular aquatic plants. There are no
submitted terrestrial plant toxicity data for naled.
85
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4.1 Evaluation of Naled and DDVP Aquatic Ecotoxicity Studies
As described in the Agency's Overview Document (U.S. EPA, 2004), the most sensitive
measurement endpoint for each taxa is used to calculate risk for an assessment endpoint.
For this assessment, evaluated taxa relevant to the aquatic habitat of the CRLF include
freshwater fish and freshwater aquatic invertebrates, and freshwater aquatic plants.
Freshwater fish are used as a surrogate species for aquatic-phase amphibians as described
in the Overview Document (U.S. EPA, 2004). Table 22 summarizes the most sensitive
aquatic organism toxicity endpoints (naled or DDVP, as appropriate) for the aquatic-
phase CRLF, its aquatic prey and its aquatic habitat, based on an evaluation of both the
submitted studies and the open literature for freshwater fish, invertebrates and plants as
discussed in Sections 4.1.1, 4.1.2 and 4.1.3, respectively.
Table 22. Selected endpoints (naled or DDVP) for direct (freshwater fish) and
indirect (aquatic invertebrates) effects to aquatic phase CRLF
Assessment
Endpoint
Measurement
Endpoint
Selected
Chemical
Selected Study Result
Species
Study
Duration and
Selected
Measurement
Endpoint
Toxicity
Value
Source and
Study
Classification
Survival and
reproduction
of freshwater
vertebrates
(fish, etc)
Most sensitive
acute
freshwater fish
LC50
Naled
Lake Trout
Salvelinus
namaycush
96-hr LC50
0.24
|imolcs/L
(92 ppb a.i.)
40098001
Supplemental
Most sensitive
freshwater fish
early life stage
NOAEC
Naled
Fathead
minnow
Pimephales
promelas
35-D NOAEC
0.0076
limoles
a.i./L (2.9
ppb a.i.)
42602201
Acceptable
Naled
Lake Trout
Salvelinus
namaycush
Estimate
0.00017
umoles/L
ACR
Survival and
reproduction
of freshwater
invertebrates
Most sensitive
acute
freshwater
aquatic
invertebrate
EC50
DDVP
Water flea
Daphnia
pulex
48-hr EC50
0.00030
|imolcs/L
(0.066 ppb)
40098001
Acceptable
Most sensitive
freshwater
aquatic
invertebrate
life cycle
NOAEC
Naled
Water flea
Daphnia
magna
21 D NOAEC
0.00012
|imolcs/L
(0.045 ppb)
42908801
Acceptable
D = day; hr = hour; ACR = acute-to-chronic ratio
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4.1.1 Toxicity to Freshwater Fish
Because this assessment considers total naled residues of concern (naled and DDVP),
toxicity values need to be expressed on an equivalent basis. Toxicity values expressed on
a mass basis were converted into a molar basis to allow them to be compared. To clarify
each of the toxicity values in text and tables, values are expressed both in terms of mass
(ug/L) and molar (umol/L).
4.1.1.1 Freshwater Fish: Acute Exposure (Mortality) Studies
Technical Grade Active Ingredient
Eleven scientifically sound freshwater fish acute toxicity tests with technical grade naled
were submitted (Appendix TBD). Eight species were tested and included: Bluegill
sunfish (Lepomis macrochirus)\ Channel catfish, Ictaluruspuncfatus; Cutthroat trout,
Oncorhynchus clarki; Fathead minnow, Pimephalespromelas; Lake trout, Salvelinus
namaycush; Largemouth bass, Micropterus salmoides; Rainbow trout, Oncorhynchus
mykiss; and Striped bass, Morone saxatilis.
The 96-hr LC50 values ranged from 92 ppb (0.24 |imoles/L) for the coldwater Lake trout
to 3,300 ppb (8.7 |imoles/L) for the warm water Fathead minnow. Naled is therefore
descriptively classified as very highly toxic to moderately toxic acutely to freshwater
fish.
The Lake trout study was classified as a supplemental study (i.e., scientifically sound but
deviates substantially from guideline test protocols) because although a solvent was used
in the stock solution to prepare treatments, two controls (one a solvent control and the
other a dilution water only control) were not tested. Only one control was tested and it is
not clear if it was a dilution water alone control or a solvent control. There was no
mortality in the control tested, and the solvent used was a typical solvent used in fish
toxicity tests, acetone, at levels below expected adverse effect levels. Considering the
impact to test results under the possible alternative control scenarios (e.g., assume solvent
control tested and that if a dilution control was tested it would have demonstrated
mortality or no mortality and vice versa), the greatest uncertainty is that the test result
may be an overestimate of toxicity. Given these conditions, and that a clear-cut
concentration response was exhibited the uncertainty introduced to risk estimates based
on using the supplemental study results were considered low.
Product Formulations
Seven product formulations containing naled were tested with freshwater fish; four were
tested with Bluegill sunfish, four were tested with Rainbow trout, and one with Atlantic
salmon. The 96-hr LC50 values range from 130 ppb (MRID#: 00263578 ) for Rainbow
trout to 4,000 ppb (MRID#: 00160741)for Bluegill sunfish. Formulations did not appear
to be more toxic than the TGAI. Therefore, TGAI study values will be used.
Desredate DDVP
Eleven scientifically sound studies with DDVP were submitted by registrants (Appendix
TBD). Species tested included Bluegill sunfish (L. macrochirus); Cutthroat trout (().
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clarki); Fathead minnow (P. promelas); Lake trout (S. namaycush); Mosquito fish
(Gambusia affinis); and Rainbow trout ((). mykiss). The 96-hr LC50 values range from
100 ppb DDVP (0.45 |imoles/L) for Rainbow trout to 11,600 ppb DDVP (52.5 |imoles/L)
for Fathead minnow.
There are no core studies available for the rainbow trout. Mayer and Ellersieck
(40098001) cite a 24-hour LC50 of 500 ppb for rainbow trout. The two 96-hour lake trout
LC50s of 187 ppb and 183 ppb showed 24-hour LC50s of 486 ppb and 667 ppb,
respectively. The studies are classified "supplemental" because they were not performed
using standard test species. Mayer and Ellersieck state (p. 9) the correlation coefficient (r)
between rainbow and lake trout for acute static LC50s is 0.99. Since the results are
comparable within the limits of the toxic category (i.e., highly toxic), the lake trout
studies will be substituted for the rainbow trout study. Since the LC50s are less than 1
ppm, dichlorvos is categorized as highly toxic to freshwater fish on an acute basis.
Two studies were performed with an emulsifiable concentrate formulation (42.3% ai).
Since the TEP and TGAI demonstrated similar toxicities (on an active ingredient basis), it
does not appear inerts in the EC formulation are toxic.
Naled versus DDVP Sensitivity
Five species of freshwater fish were tested with both naled and DDVP: Bluegill sunfish,
Cutthroat trout, Fathead minnow, Lake trout, and Rainbow trout. On a molar basis, three
of the five species tested (Cutthroat trout, Fathead minnow, and Lake trout) or 60% of the
species were 2 to 6 times more sensitive to the parent naled than to its degredate DDVP
(0.33, 8.7, and 0.24 |imoles/L versus 0.77, 52.5, and 0.83 |imoles/L, respectively). One
of the five species tested, the Rainbow trout, or 20% of the species was about as sensitive
to naled as to DDVP (0.42 versus 0.45 |imoles/L); and one of the five species, the
Bluegill sunfish, or 20% of the species was about 1.5 times more sensitive to DDVP than
to naled (3.9 versus 5.8 |imoles/L). Based on these results, 80% of the species tested
were as sensitive as or more sensitive to the parent naled than to the degredate DDVP.
Measurement Endpoint Selected
Based on the available naled and DDVP data, the most sensitive endpoint on a molar
basis is the Lake trout study with naled of 0.24 |imoles/L. Therefore, the measurement
endpoint selected for use in estimating direct effects to the CRLF and effects to fish from
total naled residues (naled + DDVP) in surface water was the Lake trout naled result of
0.24 |imoles/L (Table 22).
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4.1.1.2 Freshwater Fish: Chronic Exposure (Early Life Stage and
Reproduction) Studies
Technical Grade Active Ingredient
One fish early life stage toxicity study with the Fathead minnow was submitted (MRID:
42602201), with a resultant NOAEC and LOAEC for length of 2.9 and 6.3 ppb naled,
respectively (0.0076 and 0.0165 |imoles/L, respectively). Fathead minnow embryos
through hatching and early growth were exposed to nominal concentrations of naled at
2.2, 4.4, 8.7, 17, and 35 ppb a.i. for 35 days. Hatch was complete in 5 days in all
chambers and was unaffected by exposure to the test material. Compared to pooled
controls, larval survival at hatch and at the end of the test was unaffected by the
concentration of naled technical. The test was a flow-through design and mean measured
naled concentrations of the test solutions were about 70 to 80% of nominal
concentrations. They were 1.6, 2.9, 6.3, 13 and 27 ppb a.i., respectively. The
concentration of DDVP in solution was also measured and was observed to increase over
the exposure duration.
The increase in DDVP was likely due to naled degradation in the stock solution. If the
concentrations of naled and DDVP are combined, the mean measured concentration can
be considered "total naled equivalents" and the concentrations were therefore 1.7, 3.4,
6.9, 15, and 33 ppb naled equivalents. For this assessment, the measured naled
concentrations, rather than naled equivalents, are used.
The naled acute-to-chronic ratio (ACR) for freshwater fish based on the available acute
96-hr LC50 and early life stage NOAEC data for the Fathead minnow is 1448 (ACR =
4,200 ppb a.i./2.9 ppb a.i.). Such a large difference between the acute and chronic values
typically indicates that the chronic mode-of-action in fish differs from the acute mode-of-
action and may require some transformation or activation step. Given this ACR value,
the estimated NOAEC for Lake trout, the most acutely sensitive freshwater fish to naled,
is 0.06 ppb (0.00017 |imoles/L) Table 23.
Desredate DDVP
One scientifically sound freshwater fish early life stage with Rainbow trout was
submitted (MRID: 43788001) for the degredate DDVP with a post-hatch larval survival
NOAEC and LOAEC of 5.2 and 10.1 ppb DDVP, respectively (0.024 and 0.046
|imoles/L), This was also the most acutely sensitive test species to DDVP.
Naled versus DDVP Sensitivity
While naled and DDVP were both tested in fish early life tests, they were not tested with
the same fish species, naled was tested with Fathead minnow and DDVP with Rainbow
trout, preventing any direct comparison and conclusion regarding sensitivity of
freshwater fish to naled versus DDVP. Therefore, the sensitivity of early life stages to
naled as compared to DDVP was made indirectly using an estimated Rainbow trout
NOAEC for naled of 0.11 ppb (0.00029 |imoles/L) and a Fathead minnow NOAEC for
DDVP of 610 ppb (2.8 |imoles/L), calculated using naled and DDVP freshwater fish
ACR values, respectively ( Table 23 ). Based on these measured and estimated NOAEC
values, the Rainbow trout and Fathead minnow freshwater fish early life stages are
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estimated to be more sensitive to naled than the DDVP degredate (0.00029 and 0.076
limoles naled/L compared to 0.024 and 2.8 |imoles DDVP/L, respectively).
Table 23. Calculation methods for determination of chronic aquatic early life stage
toxicity values.
Chemical
Species
Value To Be Estimated
NOAEC-
ppb
umol/L
ACR
Naled
Lake trout
Naled Lake Trout early life stage
NOAEC (est)=Lake trout 96-hr
LC50/naled freshwater fish ACR=92
ppb/1448
0.06
0.00017
Naled
Rainbow
trout
Naled Rainbow trout early life stage
NOAEC (est)=naled Rainbow trout 96-hr
LC50/naled FW fish ACR=160ppb/1448
0.11
0.00029
Naled
Fathead
minnow
Naled fathead minnow NOAEC=2.9ppb
2.90
0.00762
Naled
ACR
Calculation
Naled FW fish ACR=Fathead minnow
96-hr LC50/Fathead minnow early life
stage NOAEC=3300ppb/2.9ppb
1448
DDVP
Fathead
minnow
DDVP Fathead minnow early life stage
NOAEC (est)= DDVP Fathead minnow
96-hr LC50/DDVP FW fish
ACR=11600/19
610.53
2.76
DDVP
ACR
Calculation
DDVP Freshwater fish ACR=Rainbow
trout DDVP 96-hr LC50/Rainbow trout
early life stage NOAEC=100ppb/5.2ppb
19
DDVP
Rainbow
Trout
DDVP Rainbow trout 96-hr LC50
5.2
0.024
Measurement Endyoint Selected
Of the naled and DDVP fish early life stage tests, on a molar basis the naled NOAEC
value of 0.0076 |imoles/L (2.9 ppb) for Fathead minnow was approximately 3.2 times
more sensitive than the DDVP NOAEC of 0.024 |imoles/L (5.2 ppb DDVP) for Rainbow
trout. Of these two values the more sensitive naled NOAEC of 0.0076 |imoles/L was
selected for determining risk estimates for total naled residues (Table 22).
The use of the Fathead minnow NOAEC may potentially underestimate risk to some
degree because it is not the most acutely sensitive species to naled. However given that
under environmental conditions the half-life for naled to DDVP is less than a day, long-
term exposure is likely to be to DDVP rather than the parent naled. In this case, the use
of the naled value may appropriately estimate risk given that it is more sensitive than the
DDVP fish early life stage value for Rainbow trout which was also the most acutely
sensitive fish species to DDVP.
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4.1.2 Toxicity to Freshwater Invertebrates
4.1.2.1 Freshwater Invertebrates: Acute Exposure (Mortality) Studies
Technical Grade Active Ingredient
Scientifically sound studies with naled and seven species of freshwater invertebrates, six
crustaceans and one aquatic insect, were submitted by registrants (Appendix A). Species
tested include the aquatic sowbug (Asellus brevicaudus), three species of water flea
{Daphnia magna, Daphniapulex, and Simocephalus serrulatus), two species of scud or
amphipods (Gammarus fasciatus and Gammarus lacustris), and a stonefly (Pteronarcys
californica). Acute toxicity values for naled range from 0.14 ppb a.i. (0.00037 |imoles/L)
for the 48-hr LC50 for the G. lacustris amphipod (MRID#:05009242)) to 41 ppb a.i.
(0.11 |imoles/L) for the 96-hr LC50 for the aquatic sowbug A. brevicaudus . Naled is
therefore descriptively classified as very highly toxic acutely to freshwater invertebrates.
Product Formulations
No available studies conducted with product formulations have been identified for naled
freshwater invertebrates.
Desredate DP VP
Scientifically sound studies with DDVP and five species of freshwater invertebrates, four
crustaceans and one aquatic insect, were submitted by registrants (Appendix TBD).
Species tested include two species of water flea (D. pulex and S. serrulatus), two species
of scud or amphipods {G. fasciatus and G. lacustris), and a stonefly (P. californica).
Acute toxicity values for DDVP range from 0.066 ppb (0.00030 |imoles/L) for the 48-hr
EC50 for the water flea/), pulex to 400,000 ppb (1,810 |imoles/L) for the 96-hr LC50 for
the amphipod G. fasciatus. The effect measured for the D. pulex study was
immobilization as a surrogate for mortality.
Naled versus DDVP Sensitivity
Five species of freshwater invertebrates were tested with both naled and DDVP: D. pulex,
G. fasciatus, G. lacustris, P. californica and S. serrulatus. On a molar basis, two of the
five species tested (G. fasciatus and G. lacustris, both amphipods) or 40% of the species
tested were 6 and 49 times more sensitive, respectively, to the parent naled than to its
degredate DDVP (0.037 and 0.00037 |imoles/L versus 1.81 and 0.0023 |imoles/L,
respectively). Alternatively, three of the five species (D. pulex, P. californica and S.
serrulatus) or 60% of the species tested were about 2.5 to 46 times more sensitive to
DDVP than to naled (0.00030, 0.00050 and 0.0012 |imoles/L versus 0.0011, 0.021 and
0.0029 |imoles/L, respectively).
Measurement Endpoint Selected
Based on the available naled and DDVP data, the most sensitive endpoint on a molar
basis is the 48-hr EC50 water flea D. pulex study with DDVP (0.00030 |imoles/L).
Therefore, the measurement endpoint selected for use in estimating effects to the
freshwater invertebrate fauna from total naled residues (naled + DDVP) in surface water
was the D. pulex naled result of 0.00030 |imoles/L (Table 22).
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4.1.2.2 Freshwater Invertebrates: Chronic Exposure (Reproduction)
Studies
Technical Grade Active Ingredient
One scientifically sound freshwater invertebrate life cycle study was submitted (MRID:
42908801). The species tested was the water flea D. magna and the 21-day NOAEC =
0.098 ppb (0.00026 |imoles/L) and LOAEC = 0.180 ppb (0.00047 |imoles/L). The most
sensitive effect was growth as measured by length.
Degredate DDVP
A freshwater aquatic invertebrate life-cycle study (MRID: 43890301- Ward and Davis,
1995) was submitted to support the mosquito larvicide use. The study resulted in a
chronic toxicity endpoint for waterflea (I), magna) NOAEC=0.0058 pbb (0.0000262
umoles/L), LOAEC=0.0122, based on egg production and growth (length and weight).
Naled versus DDVP Sensitivity
Daphnia magna was found to be ten times more sensitive to the degredate DDVP than to
the parent naled, on a molar mass adjusted basis.
Measurement Endpoint Selected
The DDVP D. magna NOAEC value of 0.0058 ppb (0.000026 |imoles/L), is the most
sensitive and therefore selected to determine estimates of reproductive risk for total naled
residues (Table 22).
4.1.3 Toxicity to Aquatic Plants
Technical Grade Active Ingredient
Four species of freshwater aquatic plants were tested for toxic effects of naled exposure:
the duckweed, lemna gibba; the green algae Selenastrum capricornutum\ the freshwater
diatom Naviculapelliculosa; and the cyanobacteria (formerly known as bluegreen algae)
Anabaena flos-aquae. Biomass or growth-based EC50 values for these species ranged
from 25 ppb a.i. (0.0656 |imoles/L) for the freshwater diatom N. pelliculosa, 46 ppb
(0.121 umoles/L) for the green algae S. capricornutum and >1,800 ppb a.i. (>4.73
|imoles/L) for the duckweed L. gibba.
To assess risk to endangered plant species, the NOAEC values, or EC05 where a NOAEC
could not be determined, are used as measurement endpoints, The NOAEC value for
Naviculapelliculosa= 4.2 ppb and the extrapolated EC05 for S. capricornutum= 4.2 ppb.
The NOAEC= 1,800 ppb for duckweed.
The most sensitive non-vascular freshwater plant is the freshwater diatom, Navicula
pelliculosa. Toxicity tests resulted in a 5-day EC50=25 ppb, based on cell density. The
initial measured concentrations of the test solutions were 4.2, 10.0, 16.0, 30.0, 53.0 and
110.0 ppb. These values indicate average recoveries between 72 and 92%. Because the
hydrolytic half-life of naled is 15.4 and 1.6 hours at pH 7 and 9, respectively, the results
are therefore based on these initially measured concentrations.
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In a Tier I 14-day toxicity study with the aquatic vascular plant duckweed (L. gibba), the
EC50 and NOAEC were determined to be >1800 ppb a.i. (>4.73 |imoles/L) and 1800 ppb
a.i. (4.73 |imoles/L), respectively, based on dry weight and frond production. At test
termination (14 days), naled was not detected in the test solutions but the degredate
DDVP was present at a concentration of 0.31 ppb (0.0014 |imoles/L). Plants exposed to
the test material were curled, and appeared smaller and chlorotic, and lacked root
development in comparison to the control plants but no significant difference in terms of
biomass or growth were detected.
Product Formulations
No scientifically sound freshwater aquatic plant testing was performed by registrants with
product formulations of naled.
Desredate DDVP
When registered, plant testing was not required for dichlorvos. The DDVP RED
identified available supplemental data (F.L. Mayer, 1986; 40228401) showing 48 hour
EC50 values of >100,000 ppb for green algae, 14,000 ppb for algae (species not given)
and 17,00-28,000 pbb for marine diatom.
Measurement Endpoint Selected
Aquatic plant toxicity data available for naled show it to be more toxic than DDVP, based
on the limited DDVP data. Therefore, naled toxicity endpoints are used to assess risk
from "total naled residues."
Table 24. Aquatic Plants
Assessment
Endpoint
Measurement
Endpoint
Selected Study Results
Species
Study Duration
and
Measurement
Endpoint
Toxicity
Value —
Source and
Study
Classification
Reduced
biomass and
growth rate
of aquatic
plants
Most sensitive
aquatic vascular
plant biomass and
growth rate
NOAEC(l) and
EC50
Duckweed
Lemna gibba
14-D EC50
>4.73
|imolcs/L
(>1800 ppb
a.i.)
42529601
Supplemental
14-D NOAEC
4.73
Hmoles/L8
1800 ppb a.i.
Most sensitive
aquatic nonvascular
plant biomass and
growth rate NOAEC
and EC50
Freshwater
diatom Navicula
pelliculosa
5-D EC50
0.066
|imolcs/L9
25.0 ppb
42529603
Acceptable
5-D NOAEC
4.2 ppb
D = day
(1) Where a NOAEC could not be determined, an EC05 may be used as a surrogate
8 1,800 ppb naled ^ 380.8 g naled/mole= 4.73 |imolcs/L
9 25 ppb naled ^ 380.8 g naled/mole=0.066 |imolcs/L
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4.1.4 Probit Slope Information for Fish and Aquatic Invertebrates
The statistical analysis of the most sensitive acute fish and invertebrate studies did not
generate a probit-slope value. Therefore, when characterizing the likelihood of risk
associated with the RQ values generated from the toxicity endpoints described above, the
default slope (4.5) for the Individual Effects Calculation model will be used. As
presented in the appendix, there were numerous fish and invertebrate studies, both with
technical grade naled and DDVP and product formulations. Most studies did not report
the slope of the dose-response curve. However, a review of the reported slopes indicates
a broad range and therefore, the default slope will be used as a best estimate.
Chemical
Species Name
Type
a.i.
96
Hr
LC50
(ppb)
96 Hr
LC50
jimols
Corr
A.I.
CL
Curve
slope
MRU) And
Classification
Naled
(Dibrom
8 EC)
Bluegill sunfish
Lepomis
macrochirus
Flow-
thru
58
240
0.63
139
0.127-
.357
4.26
00263578
Supplemental
Naled
(Orthp
Dibrom 8
EC)
Rainbow trout
Oncorhynchus
mykiss
Flow-
thru
58
130
0.34
75
0.12-
0.14
12.64
00263578
Supplemental
Naled
(Ortho
Fly Killer
D)
Rainbow trout
Oncorhynchus
mykiss
Flow-
thru
36
340
0.89
122
0.215-
1.64
3.0
00263580
Supplemental
Naled
(Ortho
Fly Killer
D)
Bluegill sunfish
Lepomis
macrochirus
Flow-
thru
36
1200
3.15
432
1.0-
1.3
6.44
00263580
Supplemental
4.2 Evaluation of Terrestrial Ecotoxicity Studies
As described in the Agency's Overview Document (U.S. EPA, 2004), the most sensitive
endpoint for each taxa is used to calculate risk for a taxa. For this assessment, evaluated
taxa relevant to the terrestrial habitat of the CRLF include birds as a surrogate for effects
to terrestrial-phase amphibians and reptiles, and small mammals, insects, and terrestrial
and riparian plants representing the CRLF critical habitat. Currently, no guideline tests
exist for direct effects to terrestrial-phase frogs. Therefore, birds are used as a surrogate
species for terrestrial-phase amphibians as described in the Overview Document (U.S.
EPA, 2004). Table 25 summarizes the most sensitive terrestrial organism toxicity
endpoints (naled or DDVP, as appropriate) for the terrestrial-phase CRLF, its terrestrial
prey and habitat, based on an evaluation of both the submitted studies and the open
literature for birds, mammals, plants, and insects as discussed in Sections 4.2.1, 4.2.2,
4.2.3, and 4.2.4, respectively.
Several studies were submitted on the toxic effects of naled exposure to terrestrial
organisms. Bird species tested include Mallard duck (Anasplatyrhynchos), Canada
goose (Branta Canadensis), Sharp-tailed grouse, Bobwhite quail (Colinus virginianus),
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Ring-necked pheasant, and Japanese quail (Coturnix japonica). Laboratory studies on
mice and rats were evaluated to assess indirect effects to the CRLF via toxicity to prey
items (i.e. small mammals). Finally, submitted toxicity studies of honey bee exposure to
naled are also used to evaluate indirect effects via prey items (insects).
Table 25. Selected toxicity endpoints for terrestrial organisms, including avian,
mammalian and invertebrates.
Assessment
Endpoint
Measurement
Endpoint
Selected Study Results
Chemical
Species
Study
Duration and
Measurement
Endpoint
Toxicity
Value
Source and
Study
Classification
Survival and
Reproduction
of Birds,
Reptiles and
Amphibians
Most sensitive
avian acute
oral toxicity,
LD50 (single-
dose)
Naled
Mallard duck
Anas
platyrhynchos
14-D LD50
36.90
mg/kg-bw
00160000
Acceptable
Most sensitive
acute avian
dietary toxicity
Naled
Japanese quail
Coturnix
japonica
8-D LC50
1327
mg/kg-diet
00022923
Acceptable
Most sensitive
avian
reproductive
toxicity
NOAEC
Naled
Mallard duck
Anas
platyrhynchos
22-WKS
NOAEC
266 mg/kg-
diet
44517902
Acceptable
Survival and
Reproduction
of Terrestrial
Mammals
Most sensitive
acute oral
toxicity, LD50
(single-dose)
Naled
Rat (female)
LD50
0.24
mmoles/kg-
bw (92
mg/kg-bw)
142660
Most sensitive
reproduction
NOAEL1
Naled
Rat
LD50
0.016
mmoles/L
(6 mg/kg-
bw/day)
146498
Survival of
Terrestrial
Invertebrates
and beneficial
insects
Most sensitive
acute contact
LD50 (|ig/bee)
Naled
Honey bee
Apis mellifera
48-hr LD50
0.0013
umoles/bee
(0.48
Hg/bee or
3.75
ppm10)
00036935
The most sensitive endpoint, parental systemic effects NOAEL= 6 mg/kg-bw/day will be used to calculate
a chronic RQ value.
10 See Appendix G for calculation
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Assessment
Endpoint
Measurement
Endpoint
Selected Study Results
Chemical
Species
Study
Duration and
Measurement
Endpoint
Toxicity
Value
Source and
Study
Classification
Survival and
Reproduction
of Birds,
Reptiles and
Amphibians
Most sensitive
avian acute
oral toxicity,
LD50 (single-
dose)
DDVP
Mallard duck
Anas
platyrhynchos
14-D LD50
0.035
mmoles/kg-
bw11
(7.8 mg/kg-
bw)
00160000
Acceptable
Most sensitive
acute avian
dietary toxicity
DDVP
Japanese quail
Coturnix
japonica
8-D LC50
1.35
mmoles/kg-
diet
(298 ppm)
0022923
Supplemental
Most sensitive
avian
reproductive
toxicity
NOAEC
DDVP
Mallard duck
Anas
platyrhynchos
22-WKS
NOAEC
0.023
mmoles/kg-
diet
(5 ppm)
44233401
Acceptable
Survival and
Reproduction
of Terrestrial
Mammals
Most sensitive
acute oral
toxicity, LD50
(single-dose)
DDVP
Rat (female)
Acute Oral
LD50
56 mg/kg-
bw
MRID#
0005467
(from DDVP
RED)
Most sensitive
reproduction
NOAEL1
DDVP
Rat
Acute Oral
LD50
2.30
mg/kg-bw
From DDVP
RED
Survival of
Terrestrial
Invertebrates
and beneficial
insects
Most sensitive
acute contact
LD50 (|ig/bee)
DDVP
Honey bee
Apis mellifera
48-hr LD50
0.495
ug/bee
MRID#
00036935
(Atkins et al
1975) (From
DDVP RED)
4.2.1 Toxicity to Birds
4.2.1.1 Birds: Acute Exposure (Mortality) Studies
Technical Grade Active Ingredient
The only available avian acute oral study is one published by the Fish and Wildlife
Service, US Department of Interior, 1970. In the study, three species of birds were
evaluated: mallard duck (Anasplatyrhynchos), Canada goose (Branta canadensis), and
sharp tailed grouse (Tympanuchusphasianellus). The resultant acute oral LD50 values
were 52.2, 36.9, and 64.9 mg/kg-bw, respectively (0.137, 0.097, and 0.170 mmoles/kg-
bw, respectively). (MRID: 00075226). For all species, signs of intoxication included
ataxia, goose-stepping, ataxia, tachypnea, salivation, tremors, loss of righting reflex,
violent wing-beat convulsions, and opisthotonos. Signs appeared as soon as 5 minutes
and mortalities usually occurred between 15 minutes and 3.5 hours after treatment;
11 7.8 mg DDVP/kg-bw / 220.98 g DDVP/mole DDVP= 0.035mmmoles/kg-bw
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however, one pheasant died between 2 and 3 days after treatment. Remission took up to
2 weeks. A treatment level as low as 22.2 mg/kg caused a mortality in Canada geese.
Desredate DDVP
Three species of birds were tested with DDVP and include the Bobwhite quail (Colinus
virginiaus), Mallard duck (A. platyrhynchos), and Ring-necked pheasantJ_Phasianus
colchicus) . The LD50 values ranged from 7.8 mg/kg-bw (0.035 mmoles/kg-bw) for the
Mallard duck to 11.3 mg/kg-bw (0.051 mmoles/kg-bw) for Ring-necked pheasant (MRID
for both results: 00075226 and Accession #: 224035).
Acute symptoms included goose stepping ataxia, use of wings to aid in balance, tremors,
and convulsions. The data are considered scientifically sound as supplementary data, but
do not fulfill core Guideline requirements for an avian acute oral study. This study does
not satisfy core data requirements because of lack of reporting on dose levels tested,
number of birds tested per level, mortality/dosage data, and study only tests one sex of
both mallards and pheasants. The data indicate that technical DDVP is highly toxic to
waterfowl and upland game species.
Naled versus DDVP Sensitivity
One species of bird was tested with both naled and DDVP, the Mallard duck. On a molar
basis the Mallard duck was approximately 4 times more sensitive to the degredate DDVP
than to the parent naled (0.035 mmoles/kg-bw versus 0.137 mmoles/kg-bw, respectively).
Although the other species tested with DDVP (Bobwhite quail and Japanese quail) did
not have naled counterparts, both of these species on a molar basis had LD50 values
lower than the three species tested with naled. Based on this data birds appear to be more
acutely sensitive to the degredate DDVP than to the parent naled.
Measurement Endpoint Selection
Based on the available naled and DDVP data, the most sensitive endpoint on a molar
basis is the LD50 Mallard duck study with DDVP (0.035 mmoles/kg-bw). Therefore,
this is the acute oral measurement endpoint selected for use in estimating effects to bird
fauna and the taxa for which they are a surrogate (i.e., amphibians and reptiles) DDVP
exposure. For naled exposure, the most sensitive acute oral value is for Canada goose.
(Table 25).
4.2.1.2 Birds: Subacute Dietary Exposure (Mortality and Growth) Studies
Technical Grade Active Ingredient
In a subacute study testing numerous pesticides in the diet, the effects of naled were
evaluated on four avian species: Bobwhite quail, Japanese quail, Ring-necked pheasant
(Phasianus colchicus), and Mallard duck. The resulting 5-day dietary LC50 values
ranged from 1,327 ppm (3.48 mmoles/kg-diet) for the Japanese quail to 2,724 ppm (7.15
mmoles/kg-diet) for the Mallard duck. The LC50 is defined as ppm naled (mmoles/kg-
diet) in an ad libitum diet expected to produce 50 percent mortality among 2- to 3-week-
old birds in 8 days comprising 5 days on treated diet followed by 3 days on untreated
diet.
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Product Formulations
Product formulation toxicity data is not available from either submitted studies or the
open literature.
Desredate DDVP
Three species of birds were tested with DDVP and include the Mallard duck, the
Japanese quail, and the Ring-necked pheasant (MRID: 00022923). The Mallard duck was
tested both with 5 day old birds and 16 day old birds. The LC50 values ranged from 298
ppm (1.35 mmoles/kg-diet) for the Japanese quail to >5,000 ppm (>22.63 mmoles/kg-
diet) for the 16 day old Mallard ducks. Based on the Mallard duck studies, even the
slight age difference between the birds appears to affect sensitivity to DDVP with the
younger 5 day old birds being more sensitive than the 16 day old birds (1,317 ppm versus
>5000 ppm, respectively).
Naled versus DDVP Sensitivity
Three species of birds were tested with both naled and DDVP, the Japanese quail, the
Ring-necked pheasant, and the Mallard duck On a molar basis the Ring-necked pheasant
and Japanese quail were approximately 2.6 times more sensitive to the degredate DDVP
than to the parent naled (2.57 and 1.35 mmoles/kg-diet versus 6.66 and 3.48 mmoles/kg-
diet, respectively). While the Ring-necked pheasant naled and DDVP tests both used 10
day old birds at test initiation, younger birds were tested with DDVP than naled for
Japanese quail (14 days old versus 17 days old, respectively) and may account for some
of the difference in sensitivity as discussed earlier, even slight differences in age were
noted to impact sensitivity. While the 5 day old Mallard duck DDVP test result was
lower than the 10 day old Mallard duck naled test result (5.96 mmoles/kg-diet versus 7.15
mmoles/kg-diet), the 14 day old Mallard duck DDVP test result was higher (>22.63
mmoles/kg-diet versus 7.15 mmoles/kg-diet). Based on data for these species, there is
some indication that birds of a similar age may be more sensitive to DDVP in the diet
than to naled.
Measurement Endpoint Selected
Based on the available naled and DDVP data, the most sensitive endpoint on a molar
basis is the LC50 Japanese quail study with DDVP (1.35 mmoles/kg-bw). Therefore, this
is the dietary measurement endpoint selected for use in estimating effects to bird fauna
and the taxa for which they are a surrogate (i.e., amphibians and reptiles) from DDVP
exposure. For naled exposure, the LC50=1327 ppm for Japanese quail will be used
(Table 25).
4.2.1.3 Birds: Chronic Exposure (Reproduction) Studies
Technical Grade Active Ingredient
Two studies on the toxic effects of naled to reproduction of birds were submitted. The
test species were the Northern bobwhite quail (MRID: 44517901) and the Mallard duck
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(MRID: 44517902). The more sensitive species was the Northern bobwhite quail, with a
LOAEC of 130 ppm a.i. (0.34 mmoles/kg-diet) and a NOAEC of < 130 ppm a.i. (<0.34
mmoles/kg-diet), based on significant reductions in body weight of males. At this
treatment level, the average weight of a male bird was 10 grams less than the control. The
results of the Mallard study, based on reductions in egg production (eggs laid, egg set,
etc.) and in percentage of eggs set and eggs laid were a LOAEC of 520 ppm a.i. (1.37
mmoles/kg-diet) and a NOAEC of 260 ppm a.i. (0.68 mmoles/kg-diet). The more
sensitive endpoint will be used to assess risk to the CRLF. The following reproductive
endpoints were measured in both studies: eggs laid, eggs cracked, eggs set, viable
embryos, live 3-week embryos, normal hatchlings, weights for 14-day-old survivors, egg
shell thickness, total food consumption, and initial and final body weights, by sex.
Degredate DDVP
Two species of birds were tested with DDVP and include the Mallard duck (MRID:
44233401) and the Northern bobwhite quail (MRID: 43981701). The Mallard duck was
more sensitive to DDVP than the Northern bobwhite quail. The NOAEC for the Mallard
duck, based on a reduction in eggshell thickness and a reduction in the # of eggs laid,
eggs set, viable embryos and live three-week embryos was 5 ppm (0.023 mmoles/kg-
diet) and the LOAEC was 15 ppm (0.068 mmoles/kg-diet). The NOAEC for the
Northern bobwhite quail, based on eggs laid, viable embryos, live three-week embryos,
normal hatchlings, 14-day old survivors, 14-day survivor weight, food consumption,
terminal adult male and female body weight was 30 ppm (0.136 mmoles/kg-diet) and the
LOAEC =100 ppm (0.453 mmoles/kg-diet).
Naled versus DDVP Sensitivity
Two species of birds were tested with both naled and DDVP, the Mallard duck and the
Northern bobwhite quail. On a molar basis the Mallard duck was approximately 30 times
more sensitive to the degredate DDVP than to the parent naled (0.023 versus 0.683
mmoles/kg-diet, respectively). While the Northern bobwhite quail test with naled did not
result in a definitive NOAEC, given that at the lowest dietary concentration tested (0.341
mmoles/kg-diet) the difference from the control was approximately 5 percent for male
body-weight, it appears that this species too is more sensitive to DDVP than to naled.
Measurement Endpoint Selected
Based on the available naled and DDVP data, the most sensitive endpoint on a molar
basis is the NOAEC from the reproduction test with the Mallard duck and DDVP (0.023
mmoles/kg-diet). Therefore, this is the dietary measurement endpoint selected for use in
estimating effects to bird fauna and the taxa for which they are a surrogate (i.e.,
amphibians and reptiles) from DDVP exposure. For naled exposure, the NOAEC for the
Mallard duck will be used. (Table 25).
4.2.2 Toxicity to Mammals
Data are available for a number of mammalian endpoints, including mortality from acute
oral, dermal or inhalation exposure, primary eye irritation, primary dermal irritation and
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dermal sensitization. EFED does not have quantitative methods to evaluate the risk from
inhalation, dermal or ocular exposures, the data are included for risk characterization
(Table 26).
Table 26. Acute Mammalian Toxicity for Technical Naled and DDVP
Naled
DDVP
Test
Results
Source
Result
Source
Acute Oral
LD50
Rat
Corn oil carrier:
325 mg/kg-b
(0.853 mmoles/kg-bw) (M);
230 mg/kg-b
(0.604 mmoles/kg-bw) (F)
Carboxymethyl-cellulose2 carrier:
191 mg/kg-bw
(0.502 mmoles/kg-bw) (M);
92 mg/kg-bw
(0.242 mmoles/kg-bw) (F)
00142660
Rat
80 mg/kg-bw
(0.362 mmoles/kg-bw) (M)
56 mg/kg-bw
(0.253 mmoles/kg-bw) (F)
00005467
Acute
Dermal
LD50
Rabbit
390 mg/kg-bw
(1.024 mmoles/kg-bw) (M)
360 mg/kg-bw
(0.945 mmoles/kg-bw) (F)
00146493
Rat
107 mg/kg-bw
(0.484 mmoles/kg-bw) (M)
75 mg/kg-bw
(0.339 mmoles/kg-bw) (F)
00005467
Acute
Inhalation
LC50
Rat
0.20 mg/L
(0.00053 mmoles/L) (M)
0.19 mg/L
(0.00050 mmoles/L) (F)
for 4 hr. exposure
00146494
> 0.198 mg/L
(>0.0090)
00137239
Primary eye
irritation1
Rabbit
Severe irritation
00074826
Mild irritant
00146921
Primary
dermal
irritation1
Rabbit
Corrosive (escharotic)
00074825
Mild irritant
00146920
Dermal
sensitization1
Guinea pig
Weakly positive
00074657
No study available
None
Data pertaining to eye irritation, dermal irritation and skin sensitization are not required to support the reregistration
of the TGAI. These data are presented for information purposes.
2 A preliminary study to a cytogenetics assay obtained somewhat lower oral LD50 values of 85.1 mg/kg/day for male
rats and 81.2 mg/kg/day for females using CMC as the vehicle (MRID 00142665).
4.2.2.1 Mammals: Acute Exposure (Mortality) Studies
Technical Grade Active Ingredient
The most sensitive acute oral rat LD50 value is 92 mg/kg-bw (0.242 mmoles/kg-bw).
The acute oral studies indicated that naled was more toxic when administered as an
aqueous suspension in 0.5% carboxymethylcellulose (CMC) than when administered as a
corn oil preparation. Acute mammalian toxicity data for naled and DDVP are presented
in Table 26 above.
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Degredate DDVP
Acute oral studies with DDVP resulted in LD50=56 mg/kg-bw (0.253 mmoles/kg-bw)
for females rats and 80 mg/kg-bw (0.362 mmoles/kg-bw) for males.
Naled versus DDVP Sensitivity
On a mass adjusted basis, the toxicity of DDVP and naled to rats is similar. Naled is
slightly more toxic, with an LD50=0.242 mmoles/kg-bw vs a DDVP LD50=0.253
mmoles/kg-bw.
Measurement Endpoint Selected
Both naled and DDVP acute oral endpoints, as identified above, will be used to estimate
indirect effects.
4.2.2.2 Mammals: Chronic Exposure (Reproduction) Studies
Technical Grade Active Ingredient
The most sensitive reproductive rat NOAEL = 6 mg/kg-bw. A two-generation
reproduction study was conducted with Sprague-Dawley-derived Charles River CD rats.
Naled was administered at doses of 0, 2, 6, or 18 mg/kg-bw/day by gavage. Systemic
effects were observed in adult male rats of both generations. Body weight gain was
depressed at the 18 mg/kg-bw/day dose for F0 males and at all dose levels for F1 males.
Reproductive indices were unaffected in both generations. Survival of pups was reduced
at 18 mg/kg-bw/day in the F1 and F2b generations. A consistent decrease in pup weight
was also noted during lactation in both generations. The NOAEL for parental systemic
effects was 6 mg/kg-bw/day. The LOAEL was 18 mg/kg-bw/day based on decreased
body weight gain in both generations. The reproductive toxicity NOAEL was 18 mg/kg-
bw/day, which was the highest dose tested (MRID 00146498).
The most sensitive endpoint, parental systemic effects NOAEL= 6 mg/kg-bw/day will be
used to calculate a chronic RQ value.
Depredate DDVP
The most sensitive reproductive rat parental/systemic NOAEL = 2.3 mg/kg-bw/day and
LOAEL=8.3 mg/kg-bw/day (MRID: 42483901- Revised Human Health Risk Assessment
for Dichlorvos March 26, 2002). The endpoint is based on decreased percent of females
with estrous cycle and increased percent of females with abnormal cycling. The
offspring NOAEL=2.3 mg/kg-bw/day, LOAEL=8.3 mg/kg-bw/day based on reduced
number of dams bearing litter, fertility index, pregnancy index and pup weight.
4.2.2.3 Mammals: Sublethal Effects and Open Literature Data
A 13-week inhalation study exposed male and female Fischer-344 rats to filtered air
(control group) or aerosols containing 0.2, 1, or 6 [j,g/L of naled for 6 hours/day, 5
days/week. Additional control and high-dose groups recovered for six weeks. Exposure
to the highest concentration of 6 [j,g/L resulted in clinical signs of toxicity manifested as
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tremors, salivation, nasal discharge, abnormal respiration and anogenital staining. The
clinical signs were consistent with cholinergic effects and the observed inhibition of ChE
activity. Brain ChE was inhibited at 6 (J,g/L, while plasma and RBC cholinesterases were
inhibited at 1 and 6 (^g/L. Only plasma ChE continued to be inhibited six weeks after
exposure to the high concentration. No other treatment-related effects were observed.
The NOAEL for ChE inhibition was 0.2 [j,g/L and the LOAEL was 1 ^ig/L based on
depression of plasma (25-30% throughout the study) and RBC (50-60% early in study
and 25-30%) at 13-weeks) ChE activities. The NOAEL for systemic toxicity was 1 [j,g/L
and the LOAEL was 6 [^g/L based on clinical signs of toxicity (MRID 00164224).
A 28-day dermal study conducted with male and female CD/Sprague-Dawley rats applied
naled to intact skin at dose levels of 0, 1, 20, or 80 mg/kg-bw/day for 6 hours/day, 5
days/week. Carboxymethylcellulose was the vehicle. The two highest doses were
extremely irritating to the skin and produced severe erythema and edema, necrosis and
exfoliation. After 28 days, histopathological findings in the skin included acute
ulcerative inflammation, necrosis and epidermal hyperplasia. Exposure to 20 and 80
mg/kg-bw/day also produced systemic toxicity. Body weight gain by males was
depressed despite increased food consumption. Plasma, RBC and brain cholinesterases
were inhibited by 20 and 80 mg/kg-bw/day. Other treatment-related findings were
confined to the 80 mg/kg-bw/day groups. Liver and adrenal weights of females were
increased and clinical chemistry changes were suggestive of mild renal effects. Both
sexes displayed increased blood urea nitrogen and decreased creatinine, total protein and
albumin. No treatment-related histopathological changes were observed other than those
of the skin. The NOAEL was 1 mg/kg-bw/day for dermal irritation, systemic toxicity and
ChE inhibition. The LOAEL was 20 mg/kg-bw/day based on the findings of dermal
irritation, reduced weight gain and ChE (60%> brain, approximately 50% plasma and
approximately 25% RBC) inhibition (MRID 00160750).
In a 28-day oral study rats (10/sex/dose level) received 0, 0.25, 1, 10 or 100 mg/kg/day of
naled by gavage. The 100 mg/kg-bw/day dose level produced mortality and marked
cholinergic signs. The 10 mg/kg/day dose produced mild cholinergic signs and 50%
reduction in plasma and brain ChE. The 1 mg/kg-bw/day dosage produced 15% plasma
ChE inhibition without clinical signs. Although this study was classified as
supplemental, it was adequate to establish a NOAEL of 1 mg/kg-bw/day and a LOAEL
of 10 mg/kg-bw/day based on cholinergic effects (MRID 00088871).
Sublethal endpoints will not be used to assess risk because the acute mortality endpoints
are more sensitive.
4.2.3 Toxicity to Terrestrial Plants
There are no submitted plant toxicity studies for naled. In lieu of registrant submitted
data, there are a number of alternatives to assessing plant toxicity. First, naled is foliarly
applied to agricultural crops. The label cautions that application under certain conditions
(humidity, etc) will result in crop damage and there are reported incidents that give
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validity to this warning. However, effects to plants include spots and burns and
significance of such an effect is unknown.
Koike et al. (1997) found that naled was associated with celery petiole damage that could
cause mature plants to be unmarketable. Affected plants exhibited sunken, brown to tan,
dry areas or lesions on the lower portions of petioles. Even with trimming to remove
damaged areas, when the lesions affect inner, young petioles the plants were not salable
for fresh market purposes. These problems were only observed on plants to which naled
was applied by ground spray, not by air.
In the absence of phytotoxicity data and given plant incidents, crop tolerance studies and
label warnings risk to plants from naled application must be assumed.
4.2.4 Toxicity to Terrestrial Insects
4.2.4.1 Insects: Acute Exposure (Mortality) Studies
Technical Grade Active Ingredient
Naled was shown to be highly toxic to honey bees (MRID 00036935, 00037799,
00060628, 05011163) and alfalfa leafcutter bees (0500083, 00060628) when bees were
exposed to direct treatment or to short-term (less than three hours) residues.
Treatments were made by hand to small plots of alfalfa (MRID: 00037799). Cages of
bees were placed in the plots prior to treatment. At intervals after treatment, foliage
samples from each plot were placed in cages and the cages were loaded with bees. Bees
were checked for mortality after 24 hours. At 1 lb a.i./A, both dibrom formulations
caused 100% mortality of bees treated during the application. All bees were dead within
30 minutes. Three hour residues of the WP formulation (1 lb a.i./A) caused 100%
mortality, while residues of the E formulation (same time and rate) caused 59% mortality.
24-hour residues were not toxic to honey bees.
Short-term residues were moderately to highly toxic to alkali bees (0500083, 00060628).
In all of the above studies which dealt with residues, data indicated a significant decrease
in residual toxicity from 3 to 24 hours post-treatment.
In another study (MRID: 05000837), field-weathered residue samples were obtained by
applying the recommended rates of various insecticides to 1/100-acre plots of alfalfa with
a hand sprayer at 25 gal/acre and 20 psi pressure. Sample foliages were collected from
each plot at desired post-application intervals, chopped and placed in various bee cages.
The experiments were conducted with four replicates and mortality was checked at 24
hours. Experimental conditions for various bees were described as follows:
A) Honey bees: 50-100 bees/cage were fed sugar syrup and held at 78 degrees
Fahrenheit
B) Alkali bees and alfalfa leafcutter bees: 10-15 alkali bee/cage or 20-30
leafcutter bees/cage were fed with honey syrup at 88 degrees Fahrenheit.
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Susceptibility of three most important bee pollinators to 25 common insecticides were
compared. The typical pattern of susceptibility is in descending order from alfalfa
leafcutter bee > alkali bee > honey bee in 17 of the 25 insecticides tested. For naled, the
order was the same.
Naled was determined to be highly toxic to honey bees in a laboratory acute contact
toxicity test (MRID: 00036935). A bell-jar vacuum duster is used to apply the pesticide,
mixed with a pyrolite dust diluent. Dosages of dust were weighed, bees were aspirated
into dusting cages and treated, and bees were then transferred into holding cages.
Observations are recorded at 12, 24, 48, 72, and 96 hours. When test bees were exposed
to direct treatment, LD50 was determined to be 0.480 micrograms per bee, with a
reported slope value of 18.18.
Desredate DDVP
Results of a honey bee (Apis mellifera) acute contact study using the TGAI for DDVP
resulted in an acute LD50= 0.495 ug/bee. An analysis of the results indicate that DDVP
is categorized as being highly toxic to bees on an acute contact basis. A study of the
toxicity of residues on foliage to honey bees using the typical end-use product was
required for DDVP in the 1987 Standard to support the terrestrial non-food and domestic
outdoor sites. The study submitted showed residues of Dichlorvos 4E applied at 0.5 lb
ai/A were practically nontoxic to honey bees at three hours post treatment.
Naled versus DDVP Sensitivity
Based on the limited toxicity data available for DDVP and naled, honey bee is more
sensitive to naled than to DDVP and toxic residues of both quickly dissipate as
demonstrated in the foliage study above.
Measurement Endyoint Selected
Naled toxicity endpoints will be used to estimated risk to terrestrial insects from exposure
to total naled residues.
4.3 Use of Probit Slope Response Relationship to Provide Information on the
Endangered Species Levels of Concern
The statistical analysis of the most sensitive bird and mammal studies did not generate a
probit-slope value. Therefore, when characterizing the likelihood of risk associated with
the RQ values generated from the toxicity endpoints described above, the default slope
(4.5) for the Individual Effects Calculation model will be used. As presented in the
appendix, there were numerous studies, with naled and DDVP. Most studies did not
report the slope of the dose-response curve. However, a brief review of reported slopes
indicates a broad range, and therefore use of the default slope is the best estimate.
For terrestrial insects, a probit-slope value of 18.2 is reported. This value will be used to
characterize the likelihood of risk to individuals with the Individual Effects Calculation
model.
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4.4 Incident Database Review
4.4.1 Insects
1005855-001
On August 26, 1997 the American Beekeeping Federation, Inc. submitted a report to the
U.S. EPA to let EPA know about the ongoing problem of bees being killed by the
pesticides in the United States, one of which was naled. Purpose was to be aware of the
severity of the bee kill situation and which may not be overlooked while revising or
significantly changing the pesticide labels. The incidents included took place between
January 1 and June 16, 1997.
1005980-002
Beekeepers observe damage to their beehive caused by a pesticide, initially identified as
naled formulations. Because of conflict between needing to move the bees out of harm's
way and collection of bees by officials it is difficult to collect bees in order to file a report
of loss in sufficient time, especially given that residues quickly dissipate.
1003870-001
A private citizen who lives on a narrow finger of land surrounded by Newport and
Synepuxent Bay, complained about the aerial spraying of the area with Dibrom (Naled).
No data of any kind were reported. The report provides subjective observations by the
citizen of the eradication of dragonflies, butterflies, praying mantis, honey bees and other
insects and birds associated with water. This is a revision of the incident reported earlier
as #1003750-001.
4.4.2 Birds
1003062-001
To comply with 6(a)2 regulations, Valent Corp. reported a complaint (neither state nor
county identified) that a bird died as the result of exposure to Naled. The symptom was
marked as "respiratory arrest" and no other information was provided.
B0000-506-03
A citizen of Minoa, NY, reported the death of approximately 60 pheasants on his farm, to
a State agency that was not identified in the file item. He made the following
(approximate) statement: "Despite his request to the Onondaga Health Dept. that they
not spray (Dibrom 14, 1.5 oz/acre) the road in front of his house, his property was
sprayed on July 14(12:15 AM, and a second pass was made at 12:35). Over the next
couple of days birds died. Symptoms began within 6 hours and included limping ,
followed by leg paralysis and death. He felt birds dying after day 1 did so because they
stopped eating. Dead by July 19 were 60 pheasants and 3 turkeys. Also dying were
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several barn swallows nesting on his barn. The portion of his flock that was left indoors
were not exposed to the spray and they were unaffected."
Health Department officials took birds for analysis but seemed interested in bacterial
causes and discounted the possibility of pesticides as a factor.
4.4.3 Plants
1002969-055
The product caused defoliation of cotton plant. Injury was attributed to fertilizer burn or
tank contamination.
1012366-025
To comply with 6(a)2 requirements, Dow reported a complaint from Fresno, CA, that
LORSBAN 4E damaged a total of 751 acres of cotton. There were 4 growers who had 9
fields ranging from 34 acres to 155 acres. One applicator sprayed aerially the various
fields with Lorsban @ 1 qt/acre, Dibrom @ 1 pt/acre, and Britz Buffer @3.2 oz/acre; the
Britz Buffer is a petroleum distillate and contains no pesticide. Different varieties of
cotton were used by the various growers. Some of the fields were sprayed in the
morning, and some in the afternoon or evening. There is reason to think that spraying in
the morning caused less damage than spraying in the afternoon; whether the effect of
temperature alone was the operative factor is not known, but in all cases the temperatures
were in the 60s in the morning and in the high 90s in the afternoon. Symptoms of
damage were burned leaves and dropped bolls, and the yield losses ranged from 250- to
470-pounds/acre.
1007467-021
Celery was damaged by product Dibrom showing celery skin burn.
4.4.4 Fish
B0000-501-32
A fish kill took place in Snodgrass Slough, Sacramento County, on September 2, 1977.
Approximately 6000-7000 fish were killed, of which approximately 75% were game fish.
A field of tomatoes adjacent to the area of the fish loss had been sprayed with Dibrom
and Toxaphene. Analyses of water samples showed no Dibrom but a low level of
toxaphene (six days after the event took place).
1014341-015
This is a spreadsheet report from the Washington State Department of Agriculture. It is
in table format with minimal data to make a judgement. The report only gives the year of
the incident, not the month. Kill magnitude was unknown.
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4.5 Uncertainties Related to the Use of Incident Information from the
Ecological Incident Information System
Incident data are used in risk assessments to provide evidence that the risk predictions
from the screening level assessment are supported by actual effects in the field. Incident
reports submitted to EPA since approximately 1994 have been tracked by assignment of
incident numbers in an Incident Data System (IDS), microfiched, and then entered to a
second database, the Ecological Incident Information System (EIIS). Additionally, there
is an on-going effort to enter information to EIIS on incident reports received prior to
establishment of current databases. Incident reports are not received in a consistent
format (e.g., states and various labs usually have their own formats), may involve
multiple incidents involving multiple chemicals in one report, and may report on only
part of a given incident investigation (e.g., residues).
Incidents entered into EIIS are categorized into one of several certainty levels regarding
the likelihood that a particular pesticide is associated with the incident: highly probable,
probable, possible, unlikely, or unrelated. In brief, "highly probable" incidents usually
require carcass residues and/or clear circumstances regarding the exposure. "Probable"
incidents include those where residues were not available and/or circumstances were less
clear than for "highly probable." "Possible" incidents include those where multiple
chemicals may have been involved and it is not clear what the contribution was of a given
chemical. The "unlikely" category is used, for example, where a given chemical is
practically nontoxic to the category of organism killed and/or the chemical was tested for
but not detected in samples. "Unrelated" incidents are those that have been confirmed to
be not pesticide-related.
Incidents entered into the EIIS are also categorized as to use/misuse. Unless specifically
confirmed by a state or federal agency to be misuse, or there was very clear misuse such
as intentional baiting to kill wildlife, incidents are not typically considered misuse.
The number of documented kills in EIIS is believed to be a small fraction of total
mortality caused by pesticides. Mortality incidents must be seen, reported, investigated,
and have investigation reports submitted to EPA to have the potential for entry into the
database. Incidents often are not seen, due to scavenger removal of carcasses, decay in
the field, or simply because carcasses may be hard to see on many sites and/or few people
are systematically looking. Poisoned animals may also move off-site to less conspicuous
areas before dying. Incidents may not get reported to appropriate authorities capable of
investigating the incident for a variety of reasons including the finder may not know of
the importance of reporting incidents, may not know who to call, may not feel they have
the time or desire to call, or may hesitate to call because of their own involvement in the
kill. Incidents reported may not get investigated if resources are limited or may not get
investigated thoroughly, with residue analyses, for example. Also, if kills are not
reported and investigated promptly, there will be little chance of documenting the cause,
since tissues and residues may deteriorate quickly. Reports of investigated incidents
often do not get submitted to EPA, since reporting by states is voluntary.
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Furthermore, the database relies heavily on registrant-submitted incident reports, and
registrants are currently only required to submit detailed information on 'major'
ecological incidents, while 'minor' incidents are reported aggregately.
Based on the 40 CFR (§159.184 Toxic or adverse effect incident reports), an ecological
incident is considered 'major' if any of the following criteria are met:
Fish or wildlife:
(A) Involves any incident caused by a pesticide currently in Formal Review for
ecological concerns.
(B) Fish: Affected 1,000 or more individuals of a schooling species or 50 or more
individuals of a non-schooling species.
(C) Birds: Affected 200 or more individuals of a flocking species, or 50 or more
individuals of a songbird species, or 5 or more individuals of a predatory species.
(D) Mammals, reptiles, amphibians: Affected 50 or more individuals of a
relatively common or herding species or 5 or more individuals of a rare or solitary
species.
(E) Involves effects to, or illegal pesticide treatment (misuse) of a substantial tract
of habitat (greater than or equal to 10 acres, terrestrial or aquatic).
Plants:
(A) The effect is alleged to have occurred on more than 45 percent of the acreage
exposed to the pesticide.
All other ecological incidents are considered 'minor' and only need to be aggregately
reported. 'Minor' incidents reported by the registrants are not included in the EIIS
database. Therefore, for example, an incident could affect 900 fish, 150 birds, 45
mammals, and 40% of an exposed crop and not be included in the EIIS database [unless
is it reported by a non-registrant (e.g., an incident submitted by a state agency - which
are not systematically collected)]. Therefore, because the number of documented kills in
EIIS is believed to be a small fraction of total mortality caused by pesticides, absence of
reports does not necessarily provide evidence of an absence of incidents.
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5.0 Risk Characterization
Risk characterization is the integration of the exposure and effects characterizations to
determine the potential ecological risk from naled uses and potential of direct and indirect
effects on the CRLF and its designated critical habitat. 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 I). 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 is 1.0
for chronic exposures to CRLF and its prey, as well as acute exposures to plants.
Risk to the aquatic-phase CRLF is estimated by calculating the ratio of exposure to
toxicity using l-in-10 year EECs based on the label-recommended naled usage scenarios
summarized in Table 10 and the appropriate aquatic toxicity endpoint from Table 22.
Risks to the terrestrial-phase CRLF and its prey (e.g. terrestrial insects, small mammals
and terrestrial-phase frogs) are estimated based on exposures resulting from applications
of naled (Table 17 through Table 20) and the appropriate toxicity endpoint from Table 25
and Table 26. Exposures are also derived for terrestrial plants, as discussed in Section
3.3 and summarized in Table 21, based on the highest application rates of naled use
within the action area.
5.1.1 Direct Effects to the CRLF
5.1.1.1 Aquatic-Phase CRLF
Direct acute effects to the aquatic-phase CRLF are based on modeled peak EECs in a
small surface water body and the lowest acute toxicity value for freshwater fish. Direct
chronic risks to the CRLF are calculated using modeled 60-day EECs and the lowest
chronic toxicity value for freshwater fish. As discussed in detail in Section 3.1, surface
water EECs were modeled for 27 specific use scenarios which model directly or
indirectly all registered agricultural and non-agricultural uses except indoor and spot
treatment uses. Table 10 provides a list of the 27 scenarios and the uses they cover,
PRZM scenario used, the number of applications, application rate, application method,
and modeled spray drift percentage.
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Screening-level RQs are based on the most sensitive endpoints and modeled EECs in
aquatic systems from the following scenarios for naled:
• CA almond STD
• CA row crop RLF
• CA cole crop RLF
• CA lettuce STD
• CA melons RLF
• OR hops
• CA cotton STD
• CA grapes STD
• CA citrus STD
• CA fruit STD
• CA wheat RLF
• CA strawberry (non plastic) RLF
• CA sugarbeet OP
• CA forestry RLF
• CA Nursery
• CA impervious RLF
• C A turf RLF
• CA rangeland hay RLF
• CA residential RLF
• CA alfalfa OP
Surface water EECs for the 27 scenarios (63 uses) and toxicity values used in RQ
calculations, and RQ values for direct effects to the CRLF are provided in Table 27
for acute effects and
Table 28 for chronic effects. Resulting acute RQs range from <0.05 (stone fruit, hops,
grapes, sugar beets, and alfalfa) up to 0.41 (control flying insects in swamps, at 25
applications) and therefore some uses exceed the acute LOC (0.05) for direct effects to
the CRLF. Chronic RQ values range from 0.1 (peaches) up to 9.8 ("swamp"). RQs
exceed the chronic risk LOC (1.0) for 14 of the 27 naled scenarios (41 out of 63 uses) (
Table 28).
Table 27. Acute Aquatic RQ Values - Direct Effects to aquatic phase CRLF (PRZM)
Uses
Covered
PRZM
Scenario
App.
Method(s)
Peak EEC
Acute RQ
Values
Preliminary
Risk
Determination
(MA or NE)
Probability
of
Individual
Effect
ppb
umoles/L
Mosquitoes,
Flies, etc.
"swamp" (no
buffer)
CA
forestry RLF
(25 apps, 3-day
intervals)
Aerial
(with 99%
drift)
32.8
0.098
0.41
MA
1 in 24.6
CA
forestry RLF
(single appl.)
Aerial
(with 99%
drift)
13.8
0.042
0.17
MA
1 in 3300
110
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Uses
Covered
PRZM
Scenario
App.
Method(s)
Peak EEC
Acute RQ
Values
Preliminary
Risk
Determination
(MA or NE)
Probability
of
Individual
Effect
ppb
umoles/L
Mosquitoes,
Flies, etc.
(with
buffers)
CA forestry
Aerial
(with
22.7%
drift)
10.46
0.031
0.13
MA
1 in 29,900
CA impervious
Aerial
(with
22.7%
drift)
10.28
0.031
0.13
MA
1 in 29,900
CA
rangelandhay
Aerial
(with
22.7%
drift)
6.78
0.020
0.08
MA
1 in 2.51 E 6
CA residential
Aerial
(with
22.7%
drift)
3.5
0.011
0.04
NE
1 in 1.94 E 9
cabbage,
broccoli,
cauliflower,
collards, kale
CA cole crop
RLF (1.9)
Aerial
(with 12%
spray drift)
24.7
0.074
0.31
MA
1 in 90.6
CA cole crop
RLF (0.9)
Aerial
(with 12%
spray drift)
11.69
0.035
0.15
MA
1 in 9,560
CA cole crop
RLF (1.9)
Ground
spray (with
2.7% spray
drift)
14.7
0.044
0.18
MA
1 in 2,490
CA cole crop
RLF (0.9)
Ground
spray (with
2.7% spray
drift)
6.98
0.021
0.09
MA
1 in 7.91 E 6
safflower
CA wheat RLF
Aerial
(with 12%
spray drift)
22.5
0.067
0.28
MA
1 in 156
orange,
lemon,
grapefruit,
tangerine
CA citrus STD
Aerial
(with 12%
spray drift)
17.5
0.053
0.22
MA
1 in 648
beans, peas,
celery,
peppers
CA row crop
RLF
(1.9)
Aerial
(with 12%
spray drift)
17.5
0.053
0.22
MA
1 in 648
CA row crop
RLF
(1.4)
Aerial
(with 12%
spray drift)
16.9
0.051
0.21
MA
1 in 874
CA row crop
RLF
(1.4)
Ground
spray (with
2.7% spray
drift)
7.87
0.024
0.10
MA
1 in 2.94 E 5
Brussels
sprouts,
Swiss chard
CA lettuce
STD
Aerial
(with 12%
spray drift)
17.2
0.052
0.22
MA
1 in 648
Ill
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Uses
Covered
PRZM
Scenario
App.
Method(s)
Peak EEC
Acute RQ
Values
Preliminary
Risk
Determination
(MA or NE)
Probability
of
Individual
Effect
ppb
umoles/L
almond,
walnut
CA almond
STD
Aerial
(with 12%
spray drift)
16.2
0.049
0.20
MA
1 in 1,210
CA almond
STD
Ground
spray (with
2.7% spray
drift)
4.79
0.014
0.06
MA
1 in 5.22 E 7
cantaloupes,
muskmelons,
melons,
eggplant,
summer
squash
CA melons
RLF
Aerial
(with 12%
spray drift)
12.6
0.038
0.16
MA
1 in 5850
cotton
CA cotton STD
Aerial
(with 12%
spray drift)
11.68
0.035
0.15
MA
1 in 9560
strawberries
CA strawberry
(non plastic)
RLF
Aerial
(with 12%
spray drift)
8.52
0.026
0.11
MA
1 in 1.25 E 5
hops
OR hops
Aerial
(with 12%
spray drift)
7.1
0.021
0.09
MA
1 in 7.91 E 5
OR hops
Ground
spray (with
2.7% spray
drift)
2.86
0.009
0.04
NE
1 in 6.33 E10
peaches
CA fruit STD
Ground
spray (with
2.7% spray
drift)
3.35
0.010
0.04
NE
1 in 6.33 E 9
grapes
CA grapes
STD
Ground
spray (with
2.7% spray
drift)
0.93
0.003
0.01
NE
1 in 8.86 E18
sugar beets
CA sugarbeet
Ground
spray (with
2.7% spray
drift)
1.992
0.006
0.02
NE
1 in 9.6 E13
alfalfa
CA alfalfa
Aerial
(with 12%
spray drift)
14.393
0.043
0.18
MA
1 in 2,490
(Lake Trout, 96-hr LC50=0.24 umoles/L)
Values in Bold exceed the LOC
Probability of Individual Effect is based on default slope=4.5
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Table 28. Chronic Aquatic RQ Values - Direct Effects to aquatic phase CRLF
(PRZM)
Uses
Covered
PRZM Scenario
App. Method(s)
60 Day
EEC
Chronic
RQ
Values
Preliminary
Risk
Determination
(MA or NE)
umoles/L
Mosquitoes,
flies, etc.
"swamp"
(no buffers)
CA forestry RLF
(25 apps, 3-day
intervals)
Aerial (with 99% drift)
0.075
9.8
MA
CA forestry RLF
(single appl.)
Aerial (with 99% drift)
0.004
0.5
NE
Mosquitoes,
flies, etc.
(with
buffers)
CA forestry
Aerial (with 22.7% drift)
0.009
1.2
MA
CA impervious
Aerial (with 22.7% drift)
0.010
1.3
MA
CA rangelandhay
Aerial (with 22.7% drift)
0.003
0.4
NE
CA residential
Aerial (with 22.7% drift)
0.007
0.9
NE
cabbage,
broccoli,
cauliflower,
collards,
kale
CA cole crop RLF
(1.9)
Aerial (with 12% spray drift)
0.024
3.1
MA
CA cole crop RLF
(0.9)
Aerial (with 12% spray drift)
0.011
1.5
MA
CA cole crop RLF
(1.9)
Ground spray (with 2.7% spray drift)
0.010
1.4
MA
CA cole crop RLF
(0.9)
Ground spray (with 2.7% spray drift)
0.005
0.7
NE
safflower
CA wheat RLF
Aerial (with 12% spray drift)
0.003
0.3
NE
orange,
lemon,
grapefruit,
tangerine
CA citrus STD
Aerial (with 12% spray drift)
0.010
1.3
MA
beans, peas,
celery,
peppers
CA row crop RLF
(1.4)
Aerial (with 12% spray drift)
0.011
1.4
MA
CA row crop RLF
(1.9)
Aerial (with 12% spray drift)
0.015
2.0
MA
CA row crop RLF
(1.4)
Ground spray (with 2.7% spray drift)
0.005
0.7
NE
Brussels
sprouts,
Swiss chard
CA lettuce STD
Aerial (with 12% spray drift)
0.017
2.2
MA
almond,
walnut
CA almond STD
Aerial (with 12% spray drift)
0.007
1.0
MA
CA almond STD
Ground spray (with 2.7% spray drift)
0.002
0.3
NE
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Uses
Covered
PRZM Scenario
App. Method(s)
60 Day
EEC
Chronic
RQ
Values
Preliminary
Risk
Determination
(MA or NE)
umoles/L
cantaloupes,
muskmelons,
melons,
eggplant,
summer
squash
CA melons RLF
Aerial (with 12% spray drift)
0.009
1.1
MA
cotton
CA cotton STD
Aerial (with 12% spray drift)
0.009
1.2
MA
strawberries
CA strawberry
(non plastic) RLF
Aerial (with 12% spray drift)
0.009
1.1
MA
hops
OR hops
Aerial (with 12% spray drift)
0.008
1.0
NE
OR hops
Ground spray (with 2.7% spray drift)
0.002
0.3
NE
peaches
CA fruit STD
Ground spray (with 2.7% spray drift)
0.001
0.1
NE
grapes
CA grapes STD
Ground spray (with 2.7% spray drift)
0.001
0.2
NE
sugar beets
CA sugarbeet
Ground spray (with 2.7% spray drift)
0.002
0.2
NE
alfalfa
CA alfalfa
Aerial (with 12% spray drift)
0.009
1.2
MA
LOAEC 0.0165 |imolcs/L (Fathead Minnow NOAEC= 0.0076 |imolcs/L )
Values in bold exceed the LOC
5.1.1.2 Terrestrial-Phase CRLF
For RQs for the terrestrial-phase CRLF, exposures to total naled residues resulting from
ground and aerial applications of naled are modeled. Uses were modeled according to the
list in Table 16 which portrays use groupings according to similarity in application rate,
number of applications and application intervals which are key model inputs for
estimating residues on dietary items on the site of application in TREX.
To assess risks of naled to terrestrial-phase CRLF, dietary-based and dose-based
exposures are used, as modeled in T-REX. The dose-based exposures of concern in
TREX used as a surrogate for direct effects to terrestrial-phase CRLF are those for a
small bird (20g) consuming small invertebrates. Dose-based risks to the CRLF are
expected to decrease with increasing size of the animal. Acute and chronic dietary-based
RQ values are calculated by dividing dietary-based EECs by the lowest available acute
and chronic toxicity data, respectively, for birds. Acute dose-based RQ values are
calculated by dividing dose-based. EECs by the most acutely sensitive toxicity value for a
bird. Additionally, because T-REX does not track total toxic residues two separate T-
REX runs were executed for each application scenario to capture the range in possible
naled and DDVP residues, one run was made at 100% of the application rate—assumes
100% residue as naled, and one run at 20% of the application rate—which represents the
maximum possible DDVP residue level from naled. For each run, the resulting EECs
were compared to their respective toxicity endpoints to generate estimates of risk (i.e.,
114
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100% application ran compared to naled toxicity, and the 20% application run compared
to DDVP toxicity).
For all modeled use scenarios, the acute dose-based RQs for both naled and DDVP
exposure assumptions exceed the acute LOC (0.1). The dietary-based acute RQs,
assuming 100% naled exposure, exceed the acute LOC (0.1) for all scenarios except
insect pest control for animal and human health concerns. Under the assumption of
exposure to DDVP residues (20% of applied rate), the acute LOC (0.1) is exceeded only
for the safflower, cole crop, tree nuts, and citrus. While EFED does not have
methodologies to sum the RQ values resulting from the two model runs for each scenario,
the RQ values cannot be considered separately from one another. At any time in the
environment, organisms will be exposed to naled alone or both naled and DDVP
simultaneously. Both compounds have the same mode of action of on target pests.
Therefore, the risk estimate is more likely equal to or slightly less than the sum of the
RQs for the DDVP and naled T-REX runs and it is critical to not to evaluate the results
separately but rather in combination.
The chronic RQ values exceed the chronic LOC (1.0) for all scenarios except insect pest
control for animal and human health concern when assuming residues are present
primarily as DDVP for long-term exposure. Assuming long-term exposure to 100%
naled residues the RQs for safflower and the cole crop scenario are equal to the LOC.
(Table 29).
Table 29. Avian Acute and Chronic RQ Values for Direct Effects to the Terrestrial-
Phase CRLF
TREX Scenario (20g bird
consuming small insects)
Avian—RQ
Acute Dose Based
Acute Dietary
Chronic Dietary
DDVP
Naled
DDVP
Naled
DDVP
Naled
Safflower (2.1 lbs ai/a, 1
application)
9.2
17
0.11
0.21
6.6
1.0
Cole crops, tree nuts, citrus
(1.9 lbs ai/A, 1 application)
8.4
15
0.10
0.19
5.9
1.0
Alfalfa, row crops, cotton
(1.4 lbs ai/A, 1 application)
6.2
11
0.07
0.14
4.4
0.7
Melons, misc food and non-food
plants (0.9 lbs ai/A, 1
application)
0.40
7.2
0.05
0.09
2.8
0.5
Non-food plants (0.9 lbs ai/A, 52
applications, 7 day interval)
4.3
7.9
0.05
0.10
3.1
0.5
Non-food plants (0.9 lbs ai/A,
104 applications, 3 day interval)
6.1
11
0.07
0.14
4.4
0.7
Insect pests-animal and human
health concerns
(0.25 lbs ai/A, 2 applications, 7
day interval)
1.2
2.2
0.01
0.03
0.8
0.1
Insect pests-animal and human
health concerns
(0.1 lbs ai/A, 2 applications, 1
day interval)
0.75
1.4
0.01
0.02
0.5
0.1
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TREX Scenario (20g bird
consuming small insects)
Avian~RQ
Acute Dose Based
Acute Dietary
Chronic Dietary
I) I) VP
Naled
DDVP
Naled
DDVP
Naled
Insect pests-animal and human
health concerns
(0.1 lbs ai/A, 2 applications, 7
day interval)
0.48
0.87
0.01
0.01
0.3
<0.1
5.1.2 Indirect Effects
5.1.2.1 Evaluation of Potential Indirect Effects via Reduction in Food
Items
Effects to Aleal Food Resources for the Aquatic-Phase CRLF
For assessing risks of indirect effects of naled to the larval aquatic-phase CRLF
(tadpoles) through effects to its diet, l-in-10 year peak surface water EECs are divided by
the lowest acute toxicity value for aquatic plants to derive plant RQs. Resulting
unicellular plant RQs exceed the LOC (1) for aquatic plants for uses on swamps,
assuming 25 applications a year and cole crops where the application is applied aerially at
1.91b a.i./A(Table 30).
Table 30. Aquatic Unicellular Plant RQ Values for Indirect Effects to the CRLF.
Uses
Covered
PRZM
Scenario
App. Method(s)
Peak EEC
Nonlisted Plant
RQ
(EC50=0.066
umoles/L) (Vascular
Aq plants RQ values
will be lower, as the
EC50>1800 ppb)
PPb
umoles/L
Mosquitoes,
flies, etc.
"swamp" (no
buffers)
CA forestryRLF (25
apps, 3-day intervals)
Aerial (with 99%
drift)
32.8
0.098
1.5
CA forestryRLF (single
appl.)
Aerial (with 99%
drift)
13.8
0.042
0.63
Mosquitoes,
flies, etc. (with
buffers)
CA forestry
Aerial (with 22.7%
drift)
10.46
0.031
0.5
CA impervious
Aerial (with 22.7%
drift)
10.28
0.031
0.5
CA rangelandhay
Aerial (with 22.7%
drift)
6.78
0.020
0.3
CA residential
Aerial (with 22.7%
drift)
3.5
0.011
0.2
116
-------
Uses
Covered
PRZM
Scenario
App. Method(s)
Peak EEC
Nonlisted Plant
RQ
(EC50=0.066
umoles/L) (Vascular
Aq plants RQ values
will be lower, as the
EC50>1800 ppb)
PPb
umoles/L
cabbage,
broccoli,
cauliflower,
collards, kale
CA cole crop RLF
(1.9)
Aerial (with 12%
spray drift)
24.7
0.074
1.1
CA cole crop RLF
(0.9)
Aerial (with 12%
spray drift)
11.69
0.035
0.53
CA cole crop RLF
(1.9)
Ground spray (with
2.7% spray drift)
14.7
0.044
0.67
CA cole crop RLF
(0.9)
Ground spray (with
2.7% spray drift)
6.98
0.021
0.32
safflower
CA wheat RLF
Aerial (with 12%
spray drift)
22.5
0.067
1.0
orange, lemon,
grapefruit,
tangerine
CA citrus STD
Aerial (with 12%
spray drift)
17.5
0.053
0.8
beans, peas,
celery, peppers
CA row crop RLF
Aerial (with 12%
spray drift)
17.5
0.053
0.8
CA row crop RLF
Aerial Spray (with
12% spray drift)
16.9
0.051
0.8
CA row crop RLF
Ground spray (with
2.7% spray drift)
7.87
0.024
0.4
Brussels sprouts,
Swiss chard
CA lettuce STD
Aerial (with 12%
spray drift)
17.2
0.052
0.8
almond, walnut
CA almond STD
Aerial (with 12%
spray drift)
16.2
0.049
0.7
CA almond STD
Ground spray (with
2.7% spray drift)
4.79
0.014
0.2
cantaloupes,
muskmelons,
melons,
eggplant,
summer squash
CA melons RLF
Aerial (with 12%
spray drift)
12.6
0.038
0.6
cotton
CA cotton STD
Aerial (with 12%
spray drift)
11.68
0.035
0.5
strawberries
CA strawberry (non
plastic) RLF
Aerial (with 12%
spray drift)
8.52
0.026
0.4
hops
OR hops
Aerial (with 12%
spray drift)
7.1
0.021
0.3
OR hops
Ground spray (with
2.7% spray drift)
2.86
0.009
0.1
peaches
CA fruit STD
Ground spray (with
2.7% spray drift)
3.35
0.010
0.2
grapes
CA grapes STD
Ground spray (with
2.7% spray drift)
0.93
0.003
<0.1
sugar beets
CA sugarbeet
Ground spray (with
2.7% spray drift)
1.992
0.006
<0.1
117
-------
Uses
Covered
PRZM
Scenario
App. Method(s)
Peak EEC
Nonlisted Plant
RQ
(EC50=0.066
umoles/L) (Vascular
Aq plants RQ values
will be lower, as the
EC50>1800 ppb)
PPb
umoles/L
alfalfa
CA alfalfa
Aerial (with 12%
spray drift)
14.393
0.043
0.7
Effects to Aquatic Invertebrate Food Resources for the CRLF
For assessing risks of indirect effects to the CRLF through acute effects to prey
(invertebrates) in aquatic habitats, l-in-10 year peak surface water EECs were compared
to the lowest acute toxicity value for freshwater invertebrates. For chronic risks to
aquatic invertebrates, l-in-10 year peak 21-day surface water EECs were compared to the
lowest chronic toxicity value for freshwater invertebrates. Acute and chronic RQs for
aquatic invertebrates for all 27 modeled scenarios are presented in Table 31. Acute and
chronic RQs exceed the acute and chronic LOCs (0.05 and 1.0, respectively) for all
scenarios modeled. The acute RQs range from 9.3 (grapes) to 328 (mosquito use). The
chronic RQ values for aquatic invertebrates range from 23.3 up to 630 (Table 31).
Table 31. Acute and Chronic Aquatic Invertebrate RQ Values for Indirect Effects
Uses
Covered
PRZM
Scenario
App.
Method(s)
Peak EEC
Acute
RQ
Value
Aq
Inverts
21d Peak
EEC
Chronic
RQInverts
ppb
umoles/L
ppb
umole/L
Mosquitoes,
flies, etc.
"swamp"(no
buffers)
CA
forestry RLF
(25 apps, 3-
day
intervals)
Aerial
(with 99%
drift)
32.8
0.098
328
25.2
0.076
2923
CA
forestry RLF
(single appl.)
Aerial
(with 99%
drift)
13.8
0.042
139
3.5
0.011
423
Mosquitoes,
flies, etc.
(with
buffers)
CA forestry
Aerial
(with
22.7%
drift)
10.46
0.031
105
4.17
0.013
500
CA
impervious
Aerial
(with
22.7%
drift)
10.28
0.031
103
4.62
0.014
538
CA
rangelandhay
Aerial
(with
22.7%
drift)
6.78
0.02
68
2.64
0.008
308
CA
residential
Aerial
(with
3.5
0.011
35
2.42
0.011
423
118
-------
22.7%
drift)
cabbage,
CA cole crop
Aerial
24.7
0.074
247
13.3
0.04
1538
broccoli,
RLF
(with 12%
cauliflower,
collards,
spray
drift)
kale
CA cole crop
RLF
Aerial
(with 12%
spray
drift)
11.69
0.035
117
6.29
0.019
731
CA cole crop
Ground
14.7
0.044
147
5.94
0.018
692
RLF
spray
(with
2.7%
spray
drift)
CA cole crop
Ground
6.98
0.021
70
2.82
0.008
308
RLF
spray
(with
2.7%
spray
drift)
safflower
CA wheat
RLF
Aerial
(with 12%
spray
drift)
22.5
0.067
225
2.39
0.007
269
orange,
CA citrus
Aerial
17.5
0.053
176
8.5
0.026
1000
lemon,
STD
(with 12%
grapefruit,
spray
tangerine
drift)
beans, peas,
CA row crop
Aerial
17.5
0.053
175
8.94
0.027
1038
celery,
RLF
(with 12%
peppers
spray
drift)
CA row crop
Aerial
16.9
0.051
169
9.2
0.028
1077
RLF
(with 12%
spray
drift)
CA row crop
Ground
7.87
0.024
79
3.62
0.011
423
RLF
spray
(with
2.7%
spray
drift)
Brussels
CA lettuce
Aerial
17.2
0.052
173
9.44
0.028
1077
sprouts,
Swiss chard
STD
(with 12%
spray
drift)
almond,
CA almond
Aerial
16.2
0.049
162
6.51
0.02
769
walnut
STD
(with 12%
spray
drift)
CA almond
Ground
4.79
0.014
48
1.76
0.005
192
STD
spray
(with
2.7%
119
-------
spray
drift)
cantaloupes,
CA melons
Aerial
12.6
0.038
126
6.06
0.018
692
muskmelons,
RLF
(with 12%
melons,
eggplant,
spray
drift)
summer
squash
cotton
CA cotton
STD
Aerial
(with 12%
spray
drift)
11.68
0.035
117
5.13
0.015
577
strawberries
CA
strawberry
(non plastic)
RLF
Aerial
(with 12%
spray
drift)
8.52
0.026
85
4.72
0.014
538
hops
OR hops
Aerial
(with 12%
spray
drift)
7.1
0.021
71
3.08
0.009
346
OR hops
Ground
spray
(with
2.7%
spray
drift)
2.86
0.009
29
1
0.003
115
peaches
CA fruit
STD
Ground
spray
(with
2.7%
spray
drift)
3.35
0.01
34
0.74
0.002
77
grapes
CA grapes
STD
Ground
spray
(with
2.7%
spray
drift)
0.93
0.003
9.3
0.48
0.001
38
sugar beets
CA
sugarbeet
Ground
spray
1.992
0.006
20
1
0.003
115
alfalfa
CA alfalfa
Aerial
14.393
0.043
144
7.22
0.022
846
Acute RQ Value Aq Inverts (Daphniapulex) 0.0003 uumoles/L
Chronic RQInverts (Daphnia magna) NOAEC 0.00012 |imolcs/L (0.045 ppb)
Effects to Freshwater Fish and Aquatic-Phase Amphibian Dietary Resources for CRLF
Freshwater fish and frogs also represent prey items of the CRLF. Acute and
chronic RQs for these are the same acute and chronic RQs calculated for direct
effects to the aquatic-phase CRLF (Table 27and
Table 28, respectively). The chronic LOC for effects to populations of aquatic fish and
amphibians is 1.0 like that for the aquatic-phase CRLF. The level for acute effects for
population level effects to these dietary resources are above the presumed acute restricted
LOC of 0.1.
120
-------
Terrestrial Invertebrate Dietary Resources for the CRLF
In order to assess the risks from direct application or contact of naled to terrestrial
invertebrates, which are considered prey of terrestrial-phase CRLF, the honey bee is used
as a surrogate for terrestrial invertebrates. Naled residuals on insects, EECs (|ig a.i./g of
insect or ppm), calculated by T-REX for small and large insects due to on-site
applications are divided by the most sensitive adjusted (Appendix E) dermal contact
toxicity value for the honey bee, {i.e., acute LC50 = acute LD50 0.0128 g/bee = 0.048
ug/bee 0.0128 g/bee = 3.75 ppm). The acute RQ values, which range from 0.44 up to
76, exceed the insect acute LOC (0.05) for all modeled scenarios. These exceedances
refer to on-site residues exposures for terrestrial insects and would be expected to decline
with distance from the site of application.
Table 32. Acute Terrestrial Insect RQ Values for Indirect Effects to the CRLF
Use Scenario
Small
Insect
Residues
(ppm)
Acute RQ Value
(honey bee LC50
= 3.75 ppm)
Large
Insect
Residue
(ppm)s
Acute RQ Value
(honey bee LC50
= 3.75 ppm)
1 Safflower
(2.1 lbs ai/A, 1 application)!
284
76
31.5
8.4
2 Cole crops, tree nuts, citrus
(1.9 lbs ai/A, 1 application
256
68
28.5
7.6
3 Alfalfa, row crops, cotton
(1.4 lbs ai/A, 1 application)
189
50
21.0
5.6
4 Melons, misc. food and non-
food plants (0.9 lbs ai/A, 1
application)
122
32
13.5
3.6
5 Non-food plants (0.9 lbs ai/A,
52 applications, 7 day interval)
133
36
14.8
4.0
6 Non-food plants (0.9 lbs ai/A
104 applications, 3 day interval)
188
50
20.9
5.6
7 I nsect pests-animal and human
health concerns (0.25 lbs ai/A, 2
applications, 7 day interval)
36.7
9.8
4.1
1.1
8 Insect pests-animal and human
health concerns (0.1 lbs ai/A, 2
applications, 1 day interval)
23.0
6.2
2.6
0.7
9 Insect pests-animal and human
health concerns (0.1 lb ai/A, 2
applications, 7 day interval)
14.7
3.9
1.6
0.44
Effects to Small Mammal Dietary Resources for the Terrestrial-Phase CRLF
To assess risks of naled to small mammalian prey of larger terrestrial-phase CRLF,
dietary-based and dose-based exposures to small mammals are used, as modeled in
TREX. The dose-based exposures of concern in TREX are those for a small mammal
(20g). Acute and chronic dietary-based RQ values are calculated by dividing dietary-
based EECs by the most sensitive mammalian acute and chronic toxicity data,
121
-------
respectively. Acute and chronic dose-based RQ values are calculated by dividing dose-
based EECs by the most sensitive acute and chronic toxicity value, respectively, for a
mammal. Additionally, because T-REX does not track total toxic residues, two separate
T-REX runs were executed for each application scenario to capture the range in possible
naled and DDVP residues, one run was made at 100% of the application rate—assumes
100% residue as naled, and one run at 20% of the application rate—which represents the
maximum possible DDVP residue level from naled. For each run, the resulting EECs
were compared to their respective toxicity endpoints to generate estimates of risk (i.e.,
100% application run compared to naled toxicity, and the 20% application run compared
to DDVP toxicity). Acute and chronic dietary- and dose-based RQs for small mammals
are listed in Table 33 for residues on short grass.
Acute dose based RQs for naled (100%) residues on short grass exceed the acute
restricted LOC (0.2) for all modeled scenarios except for insect pest control for animal
and human health concerns at the two lowest applications. Chronic RQs exceed the
chronic LOC (1.0) for all modeled scenarios. Acute-dose based RQs for DDVP residues
exceeds the acute restricted LOC (0.2) for all modeled scenarios except the insect pest
control for animal and human health concerns, and the melon, misc. food and non-food
plant scenarios. Chronic dose-based RQs for DDVP residues exceed the chronic LOC
(1.0) for all modeled scenarios except the insect pest control for animal and human heal
concerns.
Table 33. Acute and Chronic RQ Values for Indirect effects, effects to Small
Mammals Ingesting Residues on Short Grass for Indirect Effects to the CRLF
(prey) (Modeled with T-REX)
Use
Dose-based
Dietary-based
Scenario
Acute RQs1'2
Chronic RQs3'4
Chronic RQs3'5
Naled
DDVP
Naled
DDVP
Naled
DDVP
Safflower
2.4
0.45
36
11
5.6
1.3
(2.1 lbs ai/A, 1 application)
Cole crops, tree nuts, citrus (1.9 lbs ai/A, 1
2.2
0.41
33
10
5.1
1.2
application)
Alfalfa, row crops, cotton (1.4 lbs ai/A, 1
1.6
0.30
29
7.3
3.7
0.85
application)
Melons, misc. Food and non-food plants
1.0
0.19
16
4.7
2.4
0.54
90.9 lbs ai/A, 1 application)
Non-food plants (0.9 lbs ai/A, 52
1.1
0.21
17
5.2
2.6
0.60
applications, 7 day interval)
Non-food plants (0.9 lbs ai/A, 104
1.6
0.30
24
7.3
3.7
0.84
applications, 3 day interval)
Insect pests-animal and human health
0.31
0.06
4.7
1.4
0.73
0.16
concerns (0.25 lbs ai/A, 2 applications, 7
day interval)
Insect pests-animal and human health
0.19
0.04
3.0
0.90
0.46
0.10
concerns (0.1 lb ai/A, 2 applications, 1 day
interval)
Insect pests-animal and human health
0.12
0.02
1.9
0.60
0.29
0.07
concerns (0.1 lb ai/A, 2 applications, 7 day
122
-------
Use
Dose-based
Dietary-based
Scenario
Acute RQs1'2
Chronic RQs3'4
Chronic RQs3'5
Naled
I) I) VP
Naled
DDVP
Naled
DDVP
interval)
Values in bold exceed the non-listed species LOC (0.2), while the italicized values exceed the listed
species LOC (0.1).
2
Adusted acute oral LD50 for 15 g mammal = 202 mg/kg-bw/d
3
Values in bold exceed the chronic LOC (1.0)
4
Adjusted reproduction NOAEC for 15 g mammal =13.2 mg/kg-bw/d
Reproduction NOAEC = 90 ppm
Effects to the Terrestrial-Phase Amphibians Dietary Resources of the CRLF
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 (Table 29). Acute,
dietary-based RQ values, dietary-based chronic RQ values and dose-based RQ values
exceed LOC for listed species for all uses
5.1.2.2 Evaluation of Potential Indirect Effects via Reduction in Habitat
and/or Primary Productivity (Freshwater Aquatic Plants)
No effects to aquatic plants are expected.
5.1.2.3 Evaluation of Potential Indirect Effects via Reduction in
Terrestrial Plant Community (Riparian Habitat)
There is uncertainty regarding effects to terrestrial plants. There have been a few
reported instances of plant damage, typically from direct application. The label also
cautions about potential damage to crops if naled is applied under certain conditions.
These conditions may co-incide with increases in pest pressure, such as mosquitos, and
therefore the spraying swamps and wetlands may result in indirect effects to the CRLF
via reduction in terrestrial plant communities.
5.1.3 Modification to Critical Habitat
Based on effects to prey items, modifications to critical habitat are expected. As
described above, the possibility for risk exists for terrestrial and aquatic phase
amphibians, small mammals, and terrestrial and aquatic invertebrates.
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 show no indirect effects and LOCs for the
CRLF are not exceeded for direct effects, a "no effect" determination is made, based on
123
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use of naled 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:
• 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.
• 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.
• 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 to the CRLF
Refinement of Terrestrial-Phase CRLF Acute Risks from Ingestion of Residues
Before concluding which naled uses are LAA and which are NLAA, a refinement of the
risks posed to the terrestrial-phase CRLF from ingestion of residues on small insects was
performed. This refinement was performed because the avian acute dose-based RQ
124
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values in Table 29, used as screening surrogates for terrestrial-phase amphibians, likely
overestimate risks to amphibians. Overestimation is due to the higher energy
requirements of birds over amphibians of the same body weight, which results in a higher
daily food intake rate value and a resultant higher dose-based exposure for birds than
would occur for an amphibian of the same body weight. The THERPS model refines the
dose-based RQ values based on using a dietary intake rate of an amphibian, rather than a
dietary intake rate of an avian. Results of the analysis performed with THERPS are
presented in Table 34. When an acute dose-based RQ exceeds the listed species acute
LOC (0.1) when calculated with TREX, the likelihood of the risk should be considered in
light of the results of the THERPS model.
TREX results for acute-dose-based RQ values based on avian dietary intake rates and
ingestion of residues on small insects exceeded the acute LOC (0.1) for all modeled
scenarios under both the assumption of 100% of the residues are in the form of naled and
the assumption that 20% of the residues are in the form of its degredate DDVP (Table
29). However, taking into account the lower dietary intake rate of amphibians (for 1.4
and 37g amphibians) the acute-dose-based values for ingestion of small insects lower
significantly. All of the insect pest control for animal and human health concern
scenarios drop below acute LOCs (0.1) for both naled and DDVP residues. The
safflower scenario, cole crops, tree nuts, and citrus scenario, alfalfa, row crops, and
cotton scenario, and the non-food plant scenario at 104 applications exceed the listed
species acute LOC (0.1) for both the 100% naled residue and 20% DDVP residue
assumptions. The melons, misc. food and non-food plant scenario at 1 application and
the non-food plant scenario at 52 applications exceed the listed acute species LOC (0.1) if
it is assumed that 100% of the residue on small insects is naled but does not exceed if it is
assumed that the organisms are exposed to only 20% of application rate as DDVP
residues. As naled rapidly degrades, the assumption that residues are present as 100%
naled will be conservative. The DDVP values should not be considered the lower bound
but rather the two values summed together would represent a sort of upper bound (100%
naled plus simultaneous exposure to 20% DDVP).
Table 34 Terrestrial-Phase Amphibian Acute Dose-Based RQ Values for Direct
Effects to the CRLF from Ingestion of Residues on or in Prey Items
Small Insects1
Use Scenario
DDVP
Chance of
Individual
Mortality
(lin )
Naled
Chance of
Individual
Mortality
(lin )
Safflower
(2.1 lbs ai/A, 1 application)
0.16
8,850
0.30
107
Cole crops, tree nuts, citrus
(1.9 lbs ai/A, 1 application)
0.15
9,560
0.27
190
Alfalfa, row crops, cotton
(1.4 lbs ai/A, 1 application)
0.11
125,000
0.20
1,210
Melons, misc. food and non-food plants (0.9 lbs
ai/A, 1 application)
0.07
< 1 in a
million
0.13
29,900
Non-food plants (0.9 lbs ai/A, 52 applications,
7 d interval)
0.08
< 1 in a
million
0.14
16,400
125
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Small Insects1
Use Scenario
DDVP
Chance of
Individual
Mortality
(lin )
Naled
Chance of
Individual
Mortality
(lin )
Non-food plants (0.9 lbs ai/A, 104 applications,
3 day interval)
0.11
125,000
0.20
1,210
Insect pests-animal and human health concerns
(0.25 lbs ai/A, 2 applications, 7 day interval)
0.02
< 1 in a
million
0.04
< 1 in a
million
Insect pests-animal and human health concerns
(0.1 lbs ai/A, 2 applications, 1 day interval)
0.01
< 1 in a
million
0.02
< 1 in a
million
Insect pests-animal and human health concerns
(0.1 lbs ai/A, 2 applications, 7 day interval)
<0.01
< 1 in a
million
0.02
< 1 in a
million
' Based on the daily food ingestion rate for an amphibian which is 1.4g or 37 g. Values for large frogs
(238g) were slightly lower.
TREX is not a bioaccumulation model. Because CRLF ingest small mammals another
refinement included in the THERPS model was a conservative12 bioaccumulation model
for residues in small herbivorous and insectivorous mammals13. The bioaccumulation
model assumes that the animal ingests 100% of its daily intake instantaneously and that
there is no metabolism or elimination of the pesticide residues before being consumed.
Additionally, the diet of the herbivorous small mammal is modeled as short grass, which
has the highest chemical residues after a pesticide exposure of any of the plant residues
modeled. This scenario is highly improbable but also not relevant for naled and its
degredate DDVP as they are such a short-lived chemicals, are rapidly metabolized, and
have low bioaccumulation potential and are therefore not likely to be bioavailable for a
secondary poisoning type exposure once consumed by the small mammal. Therefore this
refinement was not included for naled.
Consideration of Dose-Based Versus Dietary-Based Results
There are distinct differences in results between acute dose-based RQ values and dietary-
based RQs for the same exposure pathways evaluated in this assessment. This is due in
part to differences in exposure techniques between acute oral dosing tests and dietary
tests. Additionally, there are limitations to both methods. The dose-based approach
assumes that the uptake and absorption kinetics of a gavage toxicity study approximate
the absorption associated with uptake from a dietary matrix. Toxic response is a function
of duration and intensity of exposure. Absorption kinetics across the gut and enzymatic
activation/deactivation of a toxicant may be important and are likely variable across
chemicals and species. For many compounds a gavage dose represents a very short-term
high intensity exposure, where as dietary exposure may be of a more prolonged nature.
The dietary-based approach assumes that animals in the field are consuming food at a rate
similar to that of confined laboratory animals. Energy content in food items differs
between the field and the laboratory and so do the energy requirements of wild and
12 For chemicals with low bioaccumulation potential.
13 Prey mammals were assumed to be 35 grams (wet weight), which is the high-end body weight of a deer
mouse.
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captive animals. Given the fate characteristics of naled and its degredate DDVP and its
mode of action, dietary-based results are considered to be more characteristic of exposure
and risks in the wild.
Consideration of the Probability of Individual Acute Effects
While the acute RQ for mortality effects, for the aquatic-phase and/or terrestrial-phase
CRLF, for any use may exceed the listed species LOC, the probability of individual
effects was low enough in some cases that the likelihood of measuring such an effect was
considered improbable. For each aquatic acute RQ below 0.5, the probability of
individual acute mortality for the aquatic-phase CRLF is in Table 27.
For terrestrial effects, the acute endangered LOC is 0.1. Using the default slope of 4.5, at
this LOC the probability of individual mortality from acute effects is 1 in 294,000.
Because slope data are not available for terrestrial organisms, the default slope is used to
estimate the probability. Therefore, any use with an RQ value of 0.1 or greater, will be
assumed to have a probability of 1 in <294,000. In the absence of other evidence,
exceedence of the terrestrial listed species LOC (0.1) will lead to an LAA determination
for such a use.
Direct Effects Determination Conclusions
For each use modeled, a conclusion for or against direct effects to the aquatic-phase
CRLF were based on consideration of whether the listed species acute LOC (0.05) was
exceeded and whether the chronic LOC was exceeded. Additionally for each use
modeled, a conclusion for or against direct effects to the terrestrial-phase CRLF was
based on whether the listed species acute LOC (0.1) was exceeded and, if exceeded, the
probability of individual mortality effects, and whether the chronic LOC was exceeded.
Also considered is the chronic EEC as compared to the chronic LOAEC for avian
species. The direct effects determination for both the aquatic-phase and terrestrial-phase
of the CRLF for each modeled use is summarized in Table 35.
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Table 35. Summary Table for Effects Determinations for Direct Effects to both
Aquatic and Terrestrial Phase CRLF
Use
Aquatic-Phase
Terrestrial- Phase
Effects
Determ.
Reason
Effects
Determ.
Reason*
Alfalfa
LAA
The listed species acute and
chronic RQs exceed LOCs.
The probability of an
individual acute mortality is 1
in 2500. The chronic exposure
concentration is below the
LOEC for an effect on growth.
Based on best judgment
chronic effects are considered
discountable and insignificant,
respectively, but acute effects
are not.
LAA
Naled: dose and dietary acute
RQs exceed LOC ; DDVP:
dose-based acute, chronic
RQs exceed LOC
Almond and
walnut (ground
only)
NLAA
The chronic LOC is not
exceeded (RQ=0.3) and while
acute RQs exceed the listed
species acute LOC, the
probability of an individual
acute mortality is low (<1 in a
million) such that based on
best judgment acute direct
effects are considered
discountable.
LAA
All RQs exceed except
chronic naled (0.96)
Almond and
walnut (aerial)
LAA
The chronic RQ (1) is equal to
the LOC. Additionally, the
listed species acute LOC is
exceeded and the probability
of an individual acute
mortality is 1 in 1,210
Beans, lima
beans and peas
(dry and
succulent form),
celery, and
peppers
Ground
spray
applications:
NLAA
The chronic LOC is not
exceeded; however, the listed
species acute LOC is exceeded
and the probability of an
individual acute mortality is 1
in 290,000. Based on best
judgment acute effects are
considered discountable.
LAA
Naled: dose and dietary acute
RQs exceed LOC ; DDVP:
dose acute, chronic RQs
exceed LOC
Aerial spray
applications:
LAA
Acute and chronic RQs exceed
LOCs are exceeded and the
probability of an individual
acute mortality is >1 in 900
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Use
Aquatic-Phase
Terrestrial- Phase
Effects
Determ.
Reason
Effects
Determ.
Reason*
Brassica
(broccoli,
cabbage,
cauliflower,
Brussels sprouts)
Ground
spray
seasonal
max 4.5 lbs
ai/A:
NLAA
The chronic LOC is not
exceeded. While the listed
species acute LOC is exceeded
the probability of an individual
acute mortality is low (<1 in a
million) such that based on
best judgment acute direct
effects are considered
discountable.
LAA
All exceed except chronic
naled (0.96)
Ground
spray
seasonal
max of 9.5
lbs a.i./A
applications:
LAA
The listed species acute and
chronic LOCs are exceeded,
the probability of an individual
acute mortality is 1 in 2500.
Aerial
spray:
LAA
Acute and chronic RQs exceed
LOCs. Labels restricting
application to a seasonal max
of 4.5 lbs ai/A have a
probability of an individual
acute mortality o 1 in 9,600
and chronic levels are at or
above concentrations reducing
growth.
Cantaloupes,
muskmelons,
melons, summer
squash, and
eggplant
LAA
Listed species acute and
chronic RQs exceed LOC and
the probability of an individual
acute mortality is 1 in 5800.
The chronic exposure
concentration is below the
LOEC for an effect on growth,
such that based on best
judgment chronic effects are
considered insignificant.
LAA
Naled: acute dose and dietary
RQs exceed LOC ; DDVP:
chronic RQs exceed LOC
Grapes
NE
Neither acute or chronic RQs
exceed LOCs are exceeded
NLAA
Naled: acute dose and dietary
RQs exceed LOC; DDVP:
chronic RQs exceed LOC.
Although several RQs exceed
the LOC, it is unlikely to find
suitable frog habitat in
ecological areas that support
this type of crop. Hops and
grapes require high mineral,
well draining soil, whereas
the CRLF is more likely to be
found near soils of the
opposite hydrologic profile.
Therefore, terrestrial acute
effects from use on grapes is
discountable.
Hops (aerial)
NLAA
Acute RQs exceed LOC and
NLAA
Naled: acute dose and dietary
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Use
Aquatic-Phase
Terrestrial- Phase
Effects
Determ.
Reason
Effects
Determ.
Reason*
the chronic RQ (1.0) is equal
to the LOC. The probability of
an individual acute mortality is
<1 in 791,000. Based on best
judgement, acute and chronic
effects are considered
discountable and insignificant,
respectively.
RQs exceed LOC; DDVP:
chronic RQs exceed LOC.
Although several RQs exceed
the LOC, it is unlikely to find
suitable frog habitat in
ecological areas that support
this type of crop. Hops and
grapes require high mineral,
well draining soil, whereas
the CRLF is more likely to be
found near soils of the
opposite hydrologic profile.
Therefore, terrestrial acute
effects from use on hops is
discountable.
Hops (ground)
NE
Neither acute nor chronic RQs
exceed LOCs are exceeded.
NLAA
Naled: acute dose and dietary
RQs exceed LOC ; DDVP:
chronic RQs exceed LOC
Oranges,
lemons,
grapefruit,
tangerines
LAA
Acute and chronic RQs exceed
LOCs are exceeded and the
probability of an individual
acute mortality is 1 in 650
LAA
All RQs exceed except
chronic naled (0.96)
Peaches
NE
Neither acute or chronic RQs
exceed LOCs are exceeded
LAA
All RQs exceed except
chronic naled (0.96)
Safflower
LAA
The chronic LOC is not
exceeded but the listed species
acute LOC is exceeded and the
probability of an individual
acute mortality is 1 in 156
LAA
All RQs exceed LOCs
Strawberries
NLAA
The listed species acute and
chronic RQs exceed LOCs.
The probability of an
individual acute mortality is 1
in 125,000. The chronic
exposure concentration is
below the LOEC for an effect
on growth, such that based on
best judgment chronic effects
are considered insignificant.
LAA
Naled: acute dose and dietary
RQs exceed LOC ; DDVP:
chronic RQs exceed LOC.
Strawberries can tolerate high
moisture soil profiles and
therefore may be located near
low-lying areas that are also
ideal for the CRLF.
Strawberries are also grown
close to the ground, where
residues are more readily
accessible to the CRLF.
Sugar beets
NE
Neither acute or chronic RQs
exceed LOCs
LAA
Naled: acute dose and dietary
RQs exceed LOC ; DDVP:
chronic RQs exceed LOC
Swiss chard
LAA
Acute and chronic LOCs are
exceeded and the probability
of individual acute mortality is
1 in 650
LAA
Naled: acute dose and dietary
RQs exceed LOC ; DDVP:
chronic RQs exceed LOC
Cotton
LAA
The listed species acute and
chronic RQs exceed LOCs.
The probability of an
individual acute mortality is 1
LAA
Naled: dose and dietary acute
RQs exceed LOC; DDVP:
dose acute, chronic RQs
exceed LOC
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Use
Aquatic-Phase
Terrestrial- Phase
Effects
Determ.
Reason
Effects
Determ.
Reason*
in 9,600. The chronic
exposure concentration is
below the LOEC for an effect
on growth, such that based on
best judgment chronic effects
are considered insignificant.
Feed lots
including dairy
cattle, and
pastures
including
woodlands,
swamps
Buffers and
no direct
application
over water:
NLAA
Listed species acute and
chronic LOCs are exceeded
and the probability of an
individual acute mortality is 1
in 29,900. The chronic
exposure concentration is
below the LOEC for an effect
on growth, such that based on
best judgment chronic effects
are considered insignificant.
NLAA
The only LOC exceedences
are TREX generated acute
dose-based. Effects are
considered insignificant.
Direct
application
over water
single
application
LAA
The chronic LOC is not
exceeded but the acute LOC is
exceeded the probability of
individual mortality of 1 in
3,300.
Direct
application
over water
25
applications:
LAA
Acute and chronic RQs exceed
LOCs are exceeded with a
probability of individual acute
mortality on order of 1 in 25.
For reduction of
pests in
rangelands
NLAA
The chronic RQs do not
exceed LOC. The listed
species acute LOC is exceeded
but the probability of an
individual acute mortality is
low (<1 in a million) such that
based on best judgment acute
direct effects are considered
discountable.
NLAA
The only LOC exceedences
are TREX generated acute
dose-based. Effects are
considered insignificant.
Forest and shade
trees,
ornamental
shrubs and
flowering plants
NLAA
Acute and chronic RQs exceed
LOCs. The probability of an
individual acute mortality 1 in
29,900. The chronic exposure
concentration is below the
LOEC for an effect on growth,
such that based on best
judgment chronic effects are
considered insignificant.
NLAA
Naled: acute dose and dietary
RQs exceed LOC; DDVP:
chronic RQs exceed LOC.
Exceedences are based on 52
applications, at 7 day
intervals. This is a worst case
scenario and therefore may
not be likely. Effects to
CRLF from this use are
discountable.
Greenhouse,
vapor treatment
of roses and
other ornamental
plants
NE
Neither acute nor chronic RQs
exceed LOCs.
NLAA
The only LOC exceedences
are TREX generated acute
dose-based. Effects are
considered insignificant.
Effects are also discountable
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Use
Aquatic-Phase
Terrestrial- Phase
Effects
Determ.
Reason
Effects
Determ.
Reason*
as use within greenhouse and
vapor treatment are unlikely
to co-occur with the CRLF or
its habitat.
*"Naled" and "DDVP" refer to the way the terrestrial modeling was approached. The parent and degredate
were modeled separately, hence generating separate RQ values but the values are considered together. In
the table, 'naled' and 'DDVP' refers to RQ values when the model input assumed 100% naled application
rate and naled toxicity and 20% application rate, as DDVP compared to DDVP toxicity endpoints,
respectively. As stated above, LOC exceedences are associated with probabilities too high to be
discountable (based on default slope).
5.2.2 Indirect Effects via Reduction in Food Items
Based on LOC exceedences for multiple food items (aquatic invertebrates, terrestrial
invertebrates, and mammals) all uses are likely to adversely affect the CRLF indirectly,
via prey mediated effects.
5.2.3 Indirect Effects via Reduction in Habitat and/or Primary Productivity
(Freshwater Aquatic Plants)
Freshwater plants are not likely to be adversely affected by naled use. Two uses
(safflower and swamps) exceed the LOC.
5.2.4 Indirect Effects via Alteration in Terrestrial Plant Community
(Riparian Habitat)
Effects to terrestrial plants could not be quantified. While effects to terrestrial plants may
affect the CRLF via habitat modification, they are not likely to adversely affect the CRLF
based on the type and extent of damage as observed in crop studies and incident reports.
5.2.4.1 Sensitivity of Forested Riparian Zones to Naled
The impact of naled on forested riparian zones should be negligible and discountable,
since nearly all naled uses result in little or no effect to vegetation - the one exception is a
single borderline exceedence (1.02) only for non-vascular aquatic plants for a single use
(safflower) at the maximum application rate. Therefore, Agency assumes NLAA for
riparian vegetation.
5.2.4.2 Sediment Loading in the Watershed and the Potential for Naled to
Affect the CRLF via Effects on Riparian Vegetation
Similarly, naled use should not result in significant increase in stream sediment loading,
since it is not expected to affect riparian vegetation (see section 5.2.4.2, above).
Increased sediment loading is the direct result of loss of vegetation and increased erosion;
in the absence of vegetation diminution, there should not be significant increase in
sediment loading.
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5.2.5 Modification to Critical Habitat
All uses of naled are likely to adversely affect the CRLF via habitat modification,
especially via effects to terrestrial invertebrates, aquatic invertebrates, small amphibians,
mammals, and unicellular aquatic plants.
Table 36. Effects Determination Summary for Naled - Direct and Indirect Effects to
CRLF
Assessment Endpoint
Effects
Determination
Basis For Determination
Aquatic Phase
(eggs, larvae, tadpoles, juveniles, and adults)
Survival, growth, and
reproduction of CRLF
individuals via direct effects
on aquatic phases
LAA
Numerous uses are likely to adversely affect CRLF via
direct effects. For details, see Table 35 above
Survival, growth, and
reproduction of CRLF
individuals via effects to food
supply (i.e., freshwater
invertebrates, non-vascular
plants)
LAA
Numerous uses are likely to adversely affect CRLF via
effects to food supply, especially freshwater
invertebrates. Although naled and DDVP are not long
lived in the environment, a massive aquatic
invertebrate kill will not recovery in sufficient time for
CRLF individuals dependent on these food sources to
recover.
Survival, growth, and
reproduction of CRLF
individuals via indirect effects
on habitat, cover, and/or
primary productivity (i.e.,
aquatic plant community)
NLAA
Few to none of the uses are likely to adversely affect
CRLF via effects to riparian vegetation.
Neither upland nor aquatic vascular plants are expected
to be significantly impacted by naled use. For details,
see table X above.
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.
NE
Neither upland nor aquatic vascular plants are expected
to be significantly impacted by naled use.
Terrestrial Phase
(Juveniles and adults)
Survival, growth, and
reproduction of CRLF
individuals via direct effects
on terrestrial phase adults and
juveniles
LAA
Numerous uses are likely to adversely affect the
terrestrial phase CRLF via direct effects. For details,
see Table 35 above.
Survival, growth, and
reproduction of CRLF
individuals via effects on prey
(i.e., terrestrial invertebrates,
small terrestrial mammals and
terrestrial phase amphibians)
LAA
Numerous uses are likely to adversely affect CRLF via
effects on many prey items of the frog's diet.
Survival, growth, and
reproduction of CRLF
individuals via indirect effects
NLAA
None of the uses are likely to adversely affect CRLF
via indirect effects on habitat. Neither aquatic nor
terrestrial plants are expected to be significantly
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on habitat (i.e., riparian
impacted by naled use.
vegetation)
Table 37. Effects Determination Summary for Naled- PCEs of Designated Critical
Habitat for the CRLF
Assessment Endpoint
Effects
Determination
Basis For Determination
Aquatic Phase PCEs
(Aquatic Breeding Habitat and Aquatic Non-Breeding Habitat)
Alteration of channel/pond
morphology or geometry
and/or increase in sediment
deposition within the stream
channel or pond: aquatic
habitat (including riparian
vegetation) provides for
shelter, foraging, predator
avoidance, and aquatic
dispersal for juvenile and adult
CRLFs.
NE
No effects expected
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.
NE
No effects expected
Alteration of other chemical
characteristics necessary for
normal growth and viability of
CRLFs and their food source.
NE
No effects expected
Reduction and/or modification
of aquatic-based food sources
for pre-metamorphs (e.g.,
algae)
HM Not
Likely
There are few to no uses that may
alter the availability of algal food
sources. These uses are not likely to
occur in simultaneity with the
habitats of the pre-metamorphs and
therefore the effect is discountable.
Terrestrial Phase PCEs
(Upland Habitat and Dispersal i
Habitat)
Elimination and/or disturbance
of upland habitat; ability of
habitat to support food source
HM Not
Likely*
(except for
Due to lack of effects data for plants,
effects cannot be dismissed as No
Effect. Toxic effects to plants have
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Assessment Endpoint
Effects
Determination
Basis For Determination
ofCRLFs: 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
direct
application to
swamps under
hot and humid
conditions)
been observed but the expected
environmental concentrations,
combined with the high uncertainty
associated with the biological
significance of observed phytotoxic
effects results in discountable effects
for nearly all uses.
However, uses on swamps are an
exception. Typical use for swamps is
for mosquito control. The same
environmental conditions that lead to
mosquito outbreaks are also
associated with plant damage. Based
on information contained in incident
reports and label warnings, effects to
upland plants are not expected under
most conditions, with the exception
of hot and humid areas, such as uses
in swamps for mosquito control.
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
HM Not
Likely
Due to lack of effects data for plants,
effects cannot be dismissed as No
Effect. However, based on
information contained in incident
reports and label warnings, effects to
upland plants are not expected under
most conditions, with the exception
of hot and humid areas, such as uses
in swamps for mosquito control.
Reduction and/or modification
of food sources for terrestrial
phase juveniles and adults
HM
Based on likely effects to small
mammals, amphibians, and terrestrial
invertebrates reduction in foods
sources is expected.
Alteration of chemical
characteristics necessary for
normal growth and viability of
juvenile and adult CRLFs and
their food source.
NE
No effects expected.
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
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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. Characterizing 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 influence the recovery of prey
resources 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.
6.0 Uncertainties
6.1 Exposure Assessment Uncertainties
DDVP is a major toxic degredate of concern that is produced from naled. Although it is
assessed as part of 'total toxic residues' as a component of naled use, other uses of DDVP
(as a primary active ingredient in other products, and as a degredate of other compounds)
are not considered, even though their use may also occur simultaneous with naled use
within the same catchment(s). Similarly, relatively minor uses of naled, and those
thought to pose less exposure risk, are not considered even if they occur within the same
area at the same time. Thus, there may be some underestimation of actual exposure to
naled total toxic residues within a catchment; however, Agency believes that other
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conservative assumptions included in this assessment should more than compensate for
any potential underestimations arising from these situations.
6.1.1 Modeling Assumptions
There are intrinsic limitations to all models used by EFED for evaluating potential
exposure. For example, use of the PRZM-EXAMS aquatic exposure model does not
readily allow for assessment of several aspects of application methods that might affect
transport from application sites to nearby water bodies. Default spray drift
approximations (5% for aerial applications; 1% for ground spray applications) in PRZM
may not be suitable for this chemical, as much of it is meant to be applied aerially with
very small droplet sizes (Dv < 60 um). In addition, many aerial applications are intended
to intercept airborne targets (e.g., mosquitoes, flies) rather than as applications to foliage
or soil; the intent is to allow the chemical to remain in the atmosphere long enough to
eradicate flying insects in and around the target area. This may allow greater proportions
(> 5%) of the applied chemical to drift away from the target area and be deposited into
nearby water bodies, which is why AgDRIFT-derived spray drift values were used
instead. The AgDRIFT model does allow selection of droplet size for aerial applications;
however, the smallest droplet size available (Dv ~ 140 um) is still greater than the
recommended droplet size (Dv < 60 um) indicated on the label. Thus, there may still be
underestimation of aquatic exposure risk. Agency nevertheless assumes that theses
models are sufficiently protective overall.
Some of the modeling assumptions that were made for this assessment were deliberately
simplified, due to time constraints, limited site-specific information, ease of use, and the
need to have a method that can be applied to many different chemicals (e.g., as for other
CRLF assessments). However, if further refinements are to be made, some of these
assumptions may need to be revisited and addressed.
An example of an important simplifying assumption that may require future refinement is
the assumption of uniform runoff characteristics throughout a landscape. It is well
documented that runoff characteristics are highly non-uniform and anisotropic, and
become increasingly so as the area under consideration becomes larger. The assumption
made for estimating the aquatic Action Area (based on predicted in-stream dilution) was
that the entire landscape exhibited runoff properties identical to those commonly found in
agricultural lands in this region. However, the vastly different runoff characteristics of
undeveloped (especially forested) areas, which exhibit the least amount of surface runoff
but the greatest amount of groundwater recharge, suburban/residential areas, which are
dominated by the relationship between impermeable surfaces (roads, lots) and
grassed/other areas (lawns) plus local drainage management, urban areas, that are
dominated by managed storm drainage and impermeable surfaces, and agricultural areas
dominated by Hortonian and focused runoff (especially with row crops), should be
considered in a refined assessment incorporating modeled stream flow generation. As the
zone around the immediate (application) target area expands, there will be greater
variability in the landscape; in the context of a risk assessment, the runoff potential that is
assumed for the expanding area will be a crucial variable (since dilution at the outflow
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point is determined by the size of the expanding area). Thus, it important to know at least
some approximate estimate of types of land use within that region. Runoff from forested
areas ranges from 45 - 2,700% less than from agricultural areas; in most studies, runoff
was 2.5 to 7 times higher in agricultural areas (e.g., Okisaka et al., 1997; Karvonen et al.,
1999; McDonald et al., 2002; Phuong and van Dam 2002). Differences in runoff
potential between urban/suburban areas and agricultural areas are generally less than
between agricultural and forested areas. In terms of likely runoff potential (other
variables - such as topography and rainfall - being equal), the relationship is generally as
follows (going from lowest to highest runoff potential):
Three-tiered forest < agro forestry < suburban < row-crop agriculture < urban.
There are, however, other uncertainties that should serve to counteract the effects of the
aforementioned issue. For example, the dilution model considers that 100% of the
agricultural area has the chemical applied, which is almost certainly a gross over-
estimation. Thus, there will be assumed chemical contributions from agricultural areas
that will actually be contributing only runoff water (dilutant); so some contributions to
total contaminant load will really serve to lessen rather than increase aquatic
concentrations. In light of these (and other) confounding factors - such as rapid
degradation of naled residues - Agency believes that this model gives us the best
available estimates under current circumstances.
6.1.2 Impact of Vegetative Setbacks on Runoff
"Buffer" or "setback" restrictions apply for most naled spray uses (25 feet for ground
spray applications, 150 feet for aerial spray, 50-100 feet for airblast, 10 feet minimum for
other applications), which should serve to lessen the amount of drift that is deposited onto
surface waters. However, PRZM assumes that the 'edge-of-field' runoff/erosion
concentrations are delivered directly into the EXAMS "pond" without an intervening
buffer. Theoretically, a buffer should provide additional protection to an adjacent surface
water body by attenuating runoff through interception, flow retardation, and by providing
conditions presumably conducive to increased degradation/dissipation of the applied
chemical. Thus, it would be expected that water concentrations be lower in the presence
of a vegetated (interceptive) buffer - and that the PRZM-EXAMS results would therefore
be over-estimating water concentrations. Given the current uncertainty regarding the
effectiveness of such buffers on runoff water quality, and the variability of such
(putative) effectiveness according to physical/chemical properties of different chemicals,
it may be most conservative and protective to assume there is an absence of buffer
between application site and nearby water body.
Other exposure models (e.g., AgDRIFT) do allow for inclusion of setbacks of varying
widths (distance from field to water body). In this case, the predicted exposure
concentrations should account for the presence of such setbacks; and predicted surface
water concentrations do indeed decrease with increasing setback distances. However,
when the required setbacks (on label) are used in the AgDRIFT model, the results are
consistent with those obtained from the PRZM-EXAMS model, using the same
application rates, settings, and techniques. This indicates that either the PRZM-EXAMS
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model incorporates some measure of attenuation that is (incidentally?) consistent with a
setback, or that both the PRZM and AgDRIFT models are similarly estimating exposure.
Inclusion of buffer setbacks are specifically incorporated into the PRZM-EXAMs model
by first using the AgDRIFT model to estimate the amount of spray drift expected to reach
a water body beyond the designated buffer width. Then, the percent spray drift obtained
from AgDRIFT is used instead of the default PRZM spray drift input values. However,
the application efficiency associated with any given application remains the same. Thus,
a model run may include 12% spray drift onto a nearby water body and an on-site
application efficiency of 95% - for a total application amount equivalent to 107% of what
had actually been applied. Although in this case (naled applications in California) this
inconsistency has little or no impact on the resulting PRZM-EXAMS EECs because most
or all of the exposure in these scenarios is caused by spray drift (with almost no
contribution from surface runoff), in cases where runoff processes are significant there
may be an over-estimation of aquatic exposure.
6.1.3 PRZM Modeling Inputs and predicted Aquatic Concentrations
A specific limitation of the PRZM model for this assessment is evident in the relative
effects of runoff and spray drift, as they are processed in the model. For example, in
many of the CRLF scenarios, the associated meteorological files exhibit very little
rainfall during those months (June-August) when certain pest pressures are assumed to be
greatest. During this period, the predicted surface water concentrations are solely
determined by the spray drift function; changing the initial application date within this
period (summer) results in absolutely no change in the predicted concentrations. In
contrast, if the same parameters are run with only the application date changed, there can
be as much as an order of magnitude higher aquatic concentrations in surface water - the
result of rainfall initiating runoff into the water body, combined with the spray drift
inputs. Since spraying may occur during non-summer months (as California can have
more than one 'crop cycle' - or 'season' - in a year), it is conservative and protective to
model some of these uses in other months; provided, of course, that they still fall within
the period that is appropriate for the given application.
6.2 Effects Assessment Uncertainties
6.2.1 Age Class and Sensitivity of Effects Thresholds
It is generally recognized that test organism age may have a significant impact on the
observed sensitivity to a toxicant. For guideline tests, young (and theoretically more
sensitive) organisms are used. Testing of juveniles may overestimate toxicity at older age
classes for active ingredients of pesticides which act directly (without metabolic
transformation) on the organism, because younger age classes often have not developed
enzymatic systems associated with the detoxification of xenobiotics. When the available
toxicity data provides a range of sensitivity information with respect to age class, the risk
assessors use the most sensitive life-stage information as measures of effect.
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6.2.2 Extrapolation of Long-term Environmental Effects from Short-term
Laboratory Tests
Length of exposure and concurrent environmental stressors (e.g., urban expansion,
habitat modification, and predators) will likely affect the response of the CRLF to naled.
Because of the complexity of an organism's response to multiple stressors, the overall
"direction" of the response is unknown. Additional environmental stressors may decrease
or increase the sensitivity to the herbicide. Timing, peak concentration, and duration of
exposure are critical in terms of evaluating effects, and these factors will vary both
temporally and spatially within the action area. Overall, the effect of this variability may
result in either an overestimation or underestimation of risk.
6.2.3 Use of Threshold Concentrations for Community-Level Endpoints
6.3 Assumptions Associated with the Acute LOCs
The risk characterization section of this assessment includes an evaluation of the potential
for individual effects. The individual effects probability associated with the acute RQ is
based on the assumption that the dose-response curve fits a probit model. It uses the mean
estimate of the slope and the LC50 to estimate the probability of individual effects.
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