Risks of Triclopyr 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
October 19,2009
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Primary Authors:
Christina Wendel, Biologist
Tiffany Mason, Environmental Engineer
Andrew Shelby, Environmental Scientist
Benjamin Carr, Biologist
Environmental Risk Branch II
Environmental Fate and Effects Division (7507C)
Secondary Review:
William P. Eckel, PhD, Senior Scientist
Environmental Risk Branch II
Environmental Fate and Effects Division (7507P)
Jean Holmes, Senior Scientist
Environmental Risk Branch II
Environmental Fate and Effects Division (7507P)
Branch Chief, Environmental Risk Assessment Branch II:
Tom Bailey, PhD, Branch Chief
Environmental Fate and Effects Division (7507P)
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Table of Contents
1.0 Executive Summary 10
2.0 Problem Formulation 18
2.1 Purpose 18
2.2 Scope 20
2.3 Previous Assessments 21
2.4 Stressor Source and Distribution 23
2.4.1 Environmental Fate Assessment 23
2.4.2 Mechanism of Action 29
2.4.3 Use Characterization 29
2.5 Assessed Species 34
2.5.1 Distribution 34
2.5.2 Reproduction 37
2.5.3 Diet 37
2.5.4 Habitat 38
2.6 Designated Critical Habitat 39
2.7 Action Area 41
2.8 Assessment Endpoints and Measures of Ecological Effect 44
2.8.1 Assessment Endpoints for the CRLF 45
2.8.2 Assessment Endpoints for Designated Critical Habitat 47
2.9 Conceptual Model 49
2.9.1 Risk Hypotheses 49
2.9.2 Diagram 49
2.10 Analysis Plan 51
2.10.1 Measures to Evaluate the Risk Hypothesis and Conceptual Model 52
2.10.1.1 Measures of Exposure 52
2.10.1.2 Measures of Effect 54
2.10.1.3 Integration of Exposure and Effects 55
2.10.1.4 Data Gaps 55
3.0 Exposure Assessment 57
3.1 Label Application Rates and Intervals 57
3.2 Aquatic Exposure Assessment 59
3.2.1 Modeling Approach 59
3.2.2 Model Inputs 60
3.2.3 Results 61
3.2.4 Existing Monitoring Data 64
3.2.4.1USGSNAWQA Surface Water Data 64
3.2.4.2 USGS NAWQA Groundwater Data 64
3.2.4.3 California Department of Pesticide Regulation (CDPR) Data 64
3.2.4.4 Atmospheric Monitoring Data 64
3.3 Terrestrial Animal Exposure Assessment 64
3.4 Terrestrial Plant Exposure Assessment 66
4.0 Effects Assessment 68
4.1 Evaluation of Aquatic Ecotoxicity Studies 71
4.1.1 Toxicity to Freshwater Fish 72
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4.1.1.1 Freshwater Fish: Acute Exposure (Mortality) Studies 72
4.1.1.2 Freshwater Fish: Chronic Exposure (Early Life Stage and Reproduction)
Studies 73
4.1.1.3 Freshwater Fish: Sublethal Effects and Additional Open Literature
Information 73
4.1.1.4 Aquatic-phase Amphibian: Acute and Chronic Studies 73
4.1.2 Toxicity to Freshwater Invertebrates 73
4.1.2.1 Freshwater Invertebrates: Acute Exposure (Mortality) Studies 74
4.1.2.2 Freshwater Invertebrates: Chronic Exposure (Reproduction) Studies 74
4.1.2.3 Freshwater Invertebrates: Sublethal Effects and Open Literature Data.... 74
4.1.3 Toxicity to Aquatic Plants 74
4.1.3.1 Aquatic Plants: Laboratory Data 74
4.1.3.2 Freshwater Field Studies 75
4.2 Toxicity of Triclopyr to Terrestrial Organisms 75
4.2.1 Toxicity to Birds 77
4.2.1.1 Birds: Acute Exposure (Mortality) Studies 77
4.2.1.2 Birds: Chronic Exposure (Growth, Reproduction) Studies 78
4.2.1.3 Terrestrial-phase Amphibian Acute and Chronic Studies 78
4.2.2 Toxicity to Mammals 78
4.2.2.1 Mammals: Acute Exposure (Mortality) Studies 79
4.2.2.2 Mammals: Chronic Exposure (Growth, Reproduction) Studies 79
4.2.3 Toxicity to Terrestrial Invertebrates 79
4.2.3.1 Terrestrial Invertebrates: Acute Exposure (Mortality) Studies 79
4.2.3.2 Terrestrial Invertebrates: Open Literature Studies 79
4.2.4 Toxicity to Terrestrial Plants 80
4.3 Use of Probit Slope Response Relationship to Provide Information on the
Endangered Species Levels of Concern 82
4.4 Incident Database Review 82
4.4.1 Terrestrial Incidents 83
4.4.2 Plant Incidents 83
4.4.3 Aquatic Incidents 87
5.0 Risk Characterization 88
5.1 Risk Estimation 88
5.1.1 Exposures in the Aquatic Habitat 88
5.1.1.1 Direct Effects to Aquatic-Phase CRLF 88
5.1.1.2 Indirect Effects to Aquatic-Phase CRLF via Reduction in Prey (non-
vascular aquatic plants, aquatic invertebrates, fish, and frogs) 91
5.1.1.3 Indirect Effects to CRLF via Reduction in Habitat and/or Primary
Productivity (Freshwater Aquatic Plants) 95
5.1.2 Exposures in the Terrestrial Habitat 97
5.1.2.1 Direct Effects to Terrestrial-phase CRLF 97
5.1.2.2 Indirect Effects to Terrestrial-Phase CRLF via Reduction in Prey
(terrestrial invertebrates, mammals, and frogs) 100
5.1.2.3 Indirect Effects to CRLF via Reduction in Terrestrial Plant Community
(Riparian and Upland Habitat) 103
5.1.3 Primary Constituent Elements of Designated Critical Habitat 104
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5.1.3.1 Aquatic-Phase (Aquatic Breeding Habitat and Aquatic Non-Breeding
Habitat) 104
5.1.3.2 Terrestrial-Phase (Upland Habitat and Dispersal Habitat) 105
5.2 Risk Description 106
5.2.1 Direct Effects Ill
5.2.1.1 Aquatic-Phase CRLF Ill
5.2.1.2 Terrestrial-Phase CRLF Ill
5.2.2 Indirect Effects (via Reductions in Prey Base) 118
5.2.2.1 Algae (non-vascular plants) 118
5.2.2.2 Aquatic Invertebrates 119
5.2.2.3 Fish and Aquatic-phase Frogs 119
5.2.2.4 Terrestrial Invertebrates 120
5.2.2.5 Mammals 121
5.2.2.6 Terrestrial-phase Amphibians 122
5.2.3 Indirect Effects (via Habitat Effects) 123
5.2.3.1 Aquatic Plants (Vascular and Non-vascular) 123
5.2.3.2 Terrestrial Plants 124
5.2.4 Modification to Designated Critical Habitat 125
5.2.4.1 Aquatic-Phase PCEs 125
5.2.4.2 Terrestrial-Phase PCEs 126
5.2.5 Spatial Extent of Potential Effects 127
5.2.5.1 Spray Drift 127
5.2.5.2 Downstream Dilution Analysis 129
5.2.5.3 Overlap between CRLF habitat and Spatial Extent of Potential Effects 129
6.0 Uncertainties 131
6.1 Exposure Assessment Uncertainties 131
6.1.1 Maximum Use Scenario 131
6.1.2 Aquatic Exposure Modeling of Triclopyr 131
6.1.3 Potential Groundwater Contributions to Surface Water Chemical
Concentrations 133
6.1.4 Usage Uncertainties 134
6.1.5 Terrestrial Exposure Modeling of Triclopyr 134
6.1.5.1 Granular Composition Uncertainty 135
6.1.6 Spray Drift Modeling 135
6.2 Effects Assessment Uncertainties 136
6.2.1 Age Class and Sensitivity of Effects Thresholds 136
6.2.2 Use of Surrogate Species Effects Data 136
6.2.3 Sublethal Effects 136
6.2.4 Location of Wildlife Species 137
7.0 Risk Conclusions 138
8.0 References 144
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List of Tables
Table 1-1 Effects Determination Summary for Triclopyr Use and the CRLF 13
Table 1-2 Effects Determination Summary for Triclopyr Use and CRLF Critical Habitat
Impact Analysis 15
Table 1-3 Triclopyr Use-specific Direct Effects Determinations for the CRLF 16
Table 1-4 Triclopyr Use-specific Indirect Effects Determinations Based on Effects to
Prey 16
Table 2-1 Summary of Triclopyr Acid Environmental Fate Properties 27
Table 2-2 Triclopyr Uses Assessed for the CRLF 29
Table 2-3 Summary of California Department of Pesticide Registration (CDPR) Pesticide
Use Reporting (PUR) Data from 1999 to 2006 for Triclopyr Uses 33
Table 2-4 Assessment Endpoints and Measures of Ecological Effects 46
Table 2-5 Summary of Assessment Endpoints and Measures of Ecological Effect for
Primary Constituent Elements of Designated Critical Habitat 48
Table 3-1 Triclopyr Uses, Scenarios, and Application Information for the CRLF risk
assessment 58
Table 3-2 Summary of PRZM/EZAMS Environmental Fate Data Used for Aquatic
Exposure Inputs for Triclopyr Endangered Species Assessment for the CRLF
60
Table 3-3 Aquatic EECs (ug/L) for Triclopyr Uses in California 62
Table 3-4 Input Parameters for Foliar and Granular Applications Used to Derive
Terrestrial EECs for Triclopyr with T-REX 65
Table 3-5 Upper-bound Kenega Nomogram EECs for Dietary- and Dose-based
Exposures of the CRLF and its Prey to Triclopyr (Foliar Applications) 66
Table 3-6 EECs (mg a.e./ft2) for Direct and Indirect Effects to the Terrestrial-Phase
CRLF (Granular Applications) 66
Table 3-7 EECs (ppm) for Indirect Effects to the Terrestrial-Phase CRLF via Effects to
Terrestrial Invertebrate Prey Items (Foliar Applications) 66
Table 3-8 TerrPlant Inputs and Resulting EECs for Plants Inhabiting Dry and Semi-
aquatic Areas Exposed to Triclopyr (acid equivalent) via Runoff and Drift
(Foliar and Granular Applications) 67
Table 4-1 Freshwater Aquatic Toxicity Profile for Triclopyr (TEA and BEE expressed as
the acid equivalent) 71
Table 4-2 Categories of Acute Toxicity for Fish and Aquatic Invertebrates 72
Table 4-3 Terrestrial Toxicity Profile for Triclopyr (TEA and BEE expressed as the acid
equivalent) 76
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Table 4-4 Categories of Acute Toxicity for Avian and Mammalian Studies 77
Table 4-5 Non-target Terrestrial Plant Seedling Emergence and Vegetative Vigor
Toxicity (Tier II) Data 81
Table 5-1 Summary of Direct Effect RQs for the Aquatic-phase CRLF 89
Table 5-2 Summary of RQs Used to Estimate Indirect Effects to the CRLF via Effects to
Non-Vascular Aquatic Plants (diet of CRLF in tadpole life stage and habitat of
aquatic-phase CRLF) 91
Table 5-3 Summary of Acute and Chronic RQs Used to Estimate Indirect Effects to the
CRLF via Direct Effects on Aquatic Invertebrates as Dietary Food Items (prey
of CRLF juveniles and adults in aquatic habitats) 93
Table 5-4 Summary of RQs Used to Estimate Indirect Effects to the CRLF via Effects to
Vascular Aquatic Plants (habitat of aquatic-phase CRLF) 96
Table 5-5 Summary of Dietary-based Acute RQs Used to Estimate Direct Effects to the
Terrestrial-phase CRLF (Foliar applications) From T-REX 98
Table 5-6 Summary of Dose-based Acute RQs Used to Estimate Direct Effects to the
Terrestrial-phase CRLF (Foliar applications) From T-REX 99
Table 5-7 Summary of Chronic RQs Used to Estimate Direct Effects to the Terrestrial-
phase CRLF (Foliar applications) From T-REX 99
Table 5-8 Summary of LD50/ft2 Used to Estimate Direct Effects to the Terrestrial-phase
CRLF (Granular applications) From T-REX 99
Table 5-9 Summary of Acute and Chronic RQs Used to Estimate Indirect Effects to the
Terrestrial-phase CRLF via Direct Effects on Small Mammals as Dietary
Food Items (Foliar applications) 101
Table 5-10 Summary of LD50/ft2 Used to Estimate Indirect Effects to the Terrestrial-
phase CRLF via Direct Effects on Small Mammals as Dietary Food Items
(Granular applications) 102
Table 5-11 RQs Plants Inhabiting Dry and Semi-aquatic Areas Exposed to Triclopyr
(acid equivalent) via Runoff and Drift (Foliar applications) 104
Table 5-12 RQs Plants Inhabiting Dry and Semi-aquatic Areas Exposed to Triclopyr
(acid equivalent) via Runoff and Drift (Granular applications) 104
Table 5-13 Risk Estimation Summary for Triclopyr - Direct and Indirect Effects to CRLF
107
Table 5-14 Risk Estimation Summary for Triclopyr - PCEs of Designated Critical
Habitat for the CRLF 109
Table 5-15 Upper-bound Kenega Nomogram T-HERPS EECs (mg/kg-diet) for Dietary-
based Exposures of the CRLF and its Prey to Triclopyr, the weights of small
herbivore and insectivore mammals are 15g and 35g (Foliar applications). 112
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Table 5-16 Upper-bound Kenega Nomogram T-HERPS EECs (mg/kg-bw) for Dose-
based Exposures of the CRLF and its Prey to Triclopyr, the weights of small
herbivore and insectivore mammals are 15g (Foliar applications) 113
Table 5-17 Upper-bound Kenega Nomogram T-HERPS EECs (mg/kg-bw) for Dose-
based Exposures of the CRLF and its Prey to Triclopyr, the weights of small
herbivore and insectivore mammals are 35g (Foliar applications) 113
Table 5-18 Refined Acute Dietary-based RQs for CRLF consuming different food items
(RQs calculated using T-HERPS), the weights of small herbivore and
insectivore mammals are 15g and 35g (Foliar applications) 114
Table 5-19 Refined Acute Dose-based RQs for CRLF consuming different food items
(RQs calculated using T-HERPS), the weights of small herbivore and
insectivore mammals are 15g (Foliar applications) 115
Table 5-20 Refined Acute Dose-based RQs for CRLF consuming different food items
(RQs calculated using T-HERPS), the weights of small herbivore and
insectivore mammals are 35g (Foliar applications) 115
Table 5-21 Refined Chronic Dietary-based RQs for CRLF consuming different food
items (RQs calculated using T-HERPS), the weights of small herbivore and
insectivore mammals are 15g and 35g (Foliar applications) 117
Table 5-22 Summary of AgDRIFT Predicted Terrestrial Spray Drift Distances 128
Table 7-1. Effects Determination Summary for Triclopyr Use and the CRLF 139
Table 7-2. Effects Determination Summary for Triclopyr Use and CRLF Critical Habitat
Impact Analysis 141
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List of Figures
Figure 2-1 Triclopyr Use in Total Pounds per County 32
Figure 2-2 Recovery Unit, Core Area, Critical Habitat, and Occurrence Designations for
CRLF 36
Figure 2-3 CRLF Reproductive Events by Month 37
Figure 2-4. Initial area of concern, or "footprint" of potential use, for Triclopyr 43
Figure 2-5 Conceptual Model for Pesticide Effects on Terrestrial Phase of the CRLF .. 50
Figure 2-6 Conceptual Model for Pesticide Effects on Aquatic Phase of the CRLF 51
Figure 5-1 Overlap Map: CRLF Habitat and Triclopyr Initial Area of Concern 130
Appendices
Appendix A Ecological Effects Data
Appendix B Multi-ai Product Analysis
Appendix C RQ Method and LOCs
Appendix D Spatial Summary of Triclopyr
Appendix E T-REX Example Output
Appendix F T-HERPS Example Output
Appendix G TerrPlant Example Output
Appendix H Bibliography of Excluded ECOTOX Open Literature Data
Appendix I Bibliography of ECOTOX Open Literature Data Reviewed for Triclopyr
Appendix J Rice Model
Appendix K PRZM/EXAMS
Appendix L Chemical Structure of Triclopyr
Appendix M HED Effects Table
Appendix N Spreadsheet of ECOTOX Open Literature Data
Appendix O Incident Data
Appendix P Chemical Properties for TEA and BEE
Appendix Q PRZM/EXAMS Runs at Mitigated Rate
Attachment I. Status and Life History of the California Red-legged Frog
Attachment II. Baseline Status and Cumulative Effects for the California Red-legged
Frog
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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 Federal
Insecticide, Fungicide, Rodenticide, Act (FIFRA) regulatory actions regarding use of
triclopyr 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 (U.S. FWS) and National Marine Fisheries Service (NMFS) Endangered
Species Consultation Handbook (U.S. FWS/NMFS 1998) and procedures outlined in the
Agency's Overview Document (U.S. EPA 2004).
The CRLF was listed as a threatened species by U.S. FWS in 1996. The species is
endemic to California and Baja California (Mexico) and inhabits both coastal and interior
mountain ranges. A total of 243 streams or drainages are believed to be currently
occupied by the species, with the greatest numbers in Monterey, San Luis Obispo, and
Santa Barbara counties (U.S. FWS 1996) in California.
Triclopyr [((3,5,6-trichloro-2-pyridinyl)oxy)acetic acid] is a systemic non-selective
herbicide used to control broadleaf weeds and woody plants. It is a member of the
pyridinyloxyacetic acid chemical family, and the picolinic acid group, whose mode of
action is growth regulation, resulting in abnormal growth of plants. Triclopyr acid is
formulated as a manufacturing use product, and there are currently no pesticide uses for
triclopyr acid itself. Triclopyr acid is formulated into two end use products; triclopyr
butoxyethyl ester (triclopyr BEE, [((3,5,6-trichloro-2-pyridinyl)oxy)-2-butoxyethyl
ester]) and triclopyr triethylamine salt (triclopyr TEA, [((3,5,6-trichloro-2-
pyridinyl)oxy)acetic acid triethylamine)]). As a result, there are three PC codes
associated with triclopyr. For triclopyr acid the PC code is 116001, for triclopyr
triethylamine salt (TEA) the PC code is 116002, and for triclopyr butoxyethyl ester
(BEE) the PC code is 116004. Formulation types registered include emulsifiable
concentrate, liquid, and granular. Currently, labeled uses of triclopyr include rice,
waterways, pasture, wetlands, orchard stump treatments, ornamentals, forests, rights-of-
way, commercial and industrial outdoor premises and lawns, and residential outdoor
premises and lawns. All of these uses are considered as part of the federal action
evaluated in this assessment.
Both triclopyr TEA and BEE active ingredients are formulated from triclopyr acid, and
they both rapidly degrade back to triclopyr acid within an aqueous environment.
Triclopyr TEA rapidly dissociates in water to the triclopyr acid/anion and
triethanolamine. Triclopyr BEE rapidly hydrolyzes in the environment to the triclopyr
acid/anion and butoxyethanol. Both triethanolamine and butoxyethanol are also rapidly
dissipated by microbial degradation. In pHs > 5 the triclopyr acid will dissociate
completely leaving the triclopyr anion as the moiety that is predominantly present.
Therefore, triclopyr anion will be the predominant moiety present in the environment
when products containing either triclopyr BEE or triclopyr TEA are used. For this
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assessment, the direct and indirect effects of triclopyr (acid, TEA, and BEE) on the CRLF
will be examined in terms of the triclopyr acid equivalent incorporating both triclopyr
TEA and BEE.
In the environment the triclopyr acid/anion is somewhat persistent, and is mobile. For
triclopyr the predominant degradation pathway in water is photodegradation, and the
predominant degradation pathway in soil is microbial degradation to the major degradate
3,5,6-trichloro-2-pyridinol (TCP), which is both persistent and mobile. Triclopyr acid is
non-volatile (vapor pressure 1.26xlO"6 mm Hg) and highly soluble (water solubility of
440 mg/L [WSSA, 1989]). It is stable to hydrolysis and anaerobic aquatic metabolism,
and does not bioaccumulate in aquatic organisms. In lab studies triclopyr acid
photodegrades rapidly (less than 1 day) with TCP as the major degradate, whereas in
field studies (aquatic conditions) it photodegrades in less than 5 days. In aerobic soil
triclopyr acid degrades in 8-18 days to TCP and 3,5,6-trichloro-2-methoxypyridine
(TMP), ultimately degrading to carbon dioxide.
The degradation products TCP and TMP were recovered in the terrestrial field dissipation
studies, with TCP found at higher concentrations than TMP in both the bare and
vegetated soil plots. In the forestry studies, TCP was generally limited to the upper 30
cm of the soil, with sporadic detections in deeper soil depths. Based on these
observations it appears that TCP is persistent and mobile in the field. However, the TCP
endpoints (in terms of acid equivalency) are not more sensitive than the lowest triclopyr
endpoints, and as a result, TCP is not considered to be of toxicological concern and will
not be further evaluated in this assessment.
Since CRLFs exist within aquatic and terrestrial habitats, exposure of the CRLF, its prey
and its habitats to triclopyr acid are assessed separately for the two habitats. Tier-II
aquatic exposure models are used to estimate high-end exposures of triclopyr in aquatic
habitats resulting from runoff and spray drift from different uses. Peak model-estimated
environmental concentrations resulting from different triclopyr uses range from 5.26 to
2500 |ig/L. In addition to the Tier IIPRZM/EXAMS model, the Tier I Rice model was
used for all of the uses where triclopyr was applied directly to water. Both of these
methods were very conservative due to assumptions made regarding application intervals
and the number of allowable applications per year since these values were not explicitly
defined on the labels. For further information on how these were determined, please see
Section 3.2.
These estimates are usually 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). The NAWQA database did not have any samples containing triclopyr for
groundwater or surface water. The CDPR collected samples of triclopyr from surface
water in six California counties from March 1993 to March 2006. Out of 583 samples,
102 samples contained triclopyr. The highest concentration detected was 14.5 ppb. This
value is approximately 167 times less than the maximum model-estimated environmental
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concentration (2500 ppb). The mean concentration for all counties was found to be 1.7
ppb.
To estimate triclopyr exposures to the terrestrial-phase CRLF, and its potential prey
resulting from uses involving triclopyr applications, the T-REX model is used for both
foliar and granular uses. The AgDRIFT model is also used to estimate deposition of
triclopyr on terrestrial and aquatic habitats from spray drift. The TerrPlant model is used
to estimate triclopyr exposures to terrestrial-phase CRLF habitat, including plants
inhabiting semi-aquatic and dry areas, resulting from uses involving foliar triclopyr
applications. The T-HERPS model is used to allow for further characterization of dietary
exposures of terrestrial-phase CRLFs.
The effects determination assessment endpoints for the CRLF include direct toxic effects
on the survival, reproduction, and growth of the CRLF itself, as well as indirect effects,
such as reduction of the prey base or modification of its habitat. Direct effects to the
CRLF in the aquatic habitat are based on toxicity information for freshwater fish, which
are generally used as a surrogate for aquatic-phase amphibians. In the terrestrial habitat,
direct effects are based on toxicity information for birds, which are used as a surrogate
for terrestrial-phase amphibians. Given that the CRLF's prey items and designated
critical habitat requirements in the aquatic habitat are dependant on the availability of
freshwater aquatic invertebrates and aquatic plants, toxicity information for these
taxonomic groups is also discussed. In the terrestrial habitat, indirect effects due to
depletion of prey are assessed by considering effects to terrestrial insects, small terrestrial
mammals, and frogs. Indirect effects due to modification of the terrestrial habitat are
characterized by available data for terrestrial monocots and dicots.
Risk quotients (RQs) are derived as quantitative estimates of potential high-end risk.
Acute and chronic RQs are compared to the Agency's levels of concern (LOCs) to
identify instances where triclopyr use within the action area has the potential to adversely
affect the CRLF and its designated critical habitat via direct toxicity or indirectly based
on direct 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). When RQs for each particular type of effect are below
LOCs, the pesticide is determined to have "no effect" on the CRLF. Where RQs exceed
LOCs, a potential to cause adverse effects is identified, leading to a conclusion of "may
affect." If a determination is made that use of triclopyr 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.
Similarly for critical habitat, additional information is considered to refine the potential
for exposure and effects to distinguish those actions that do or do not result in
modification of its critical habitat.
Based on the best available information, the Agency makes a May Affect, and Likely to
Adversely Affect determination for the CRLF based on the direct and indirect
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effects to the aquatic and terrestrial-phase CRLF from the use of triclopyr
Additionally, the Agency has determined that there is the potential for modification of
CRLF designated critical habitat from the use of triclopyr. A summary of the risk
conclusions and effects determinations for the CRLF and its critical habitat is presented
in Table 1-1 and Table 1-2. Use-specific determinations for direct and indirect effects to
the CRLF are provided in Table 1-3 and Table 1-4. Further information on the results of
the effects determination is included as part of the Risk Description in Section 5.2.
Table 1-1 Effects Determination Summary for Triclopyr Use and the CRLF
Assessment
Endpoint
Effects
Determination 1
Basis for Determination
Survival, growth,
and/or reproduction
of CRLF
individuals
LAA
LAA
Potential for Direct Effects
Aquatic-phase (Eggs, Larvae, and Adults):
The aquatic phase amphibian acute LOCs for listed species (0.05) are exceeded
for most uses of triclopyr in California. The chance of individual mortality for
which the RQs exceed the LOG (0.05) range from approximately 1 in 2.51* 106
(<1%) at an RQ of 0.08 (Ornamental sod farm, turf) to 1 in 1 (100%) at an RQ of
9.62 (Lakes/ponds/reservoirs). The chronic RQs for most uses of triclopyr
exceed the chronic species LOG (1.0), and range from 131.58
(Lakes/ponds/reservoirs) to 0.21 for (Ornamental lawns and turf).
Terrestrial-phase (Juveniles and Adults):
Acute dietary-based RQs exceed the acute listed species LOG (0.1) for all uses of
triclopyr except rice. The chance of individual mortality for which the RQs
exceed the LOG (0.1) range from approximately 1 in 1.21*103 (<1%) at anRQ
0.20 (Douglas-Fir, Forest/Shelterbelt) to approximately 1 in 1.03 (100%) at an
RQ of 2.70 (Agricultural Uncultivated Areas).
For refined dose-based RQs for CRLFs of varying weights (1.4g, 37g, and 238g)
the chance of individual mortality for which the RQs exceed the LOG (0.1) range
from approximately 1 in 2.94*105 (<1%) at an RQ of 0.10 (Agricultural
Uncultivated Areas, small insectivore mammals weighing 15g, 238g CRLF) to
approximately 1 in 1 (100%) at anRQ of 10.3 (Agricultural Uncultivated Areas,
small herbivore mammals weighing 15g, 37g CRLF), and from approximately 1
in 9.56* 103 (<1%) at an RQ 0.15 (Forest Tree/Pest Management, small insects
238 g CRLF) to approximately 1 in 1 (100%) at an RQ of 16.61 (Agricultural
Uncultivated Areas, small herbivore mammals weighing 35g, 37g CRLF). These
ranges of RQs is relevant to all sizes of CRLF consuming small insects, and
small herbivore and insectivore mammals (mammals weighing 15g or 35g), for
uses in which there were exceedances.
Refined chronic dietary-based RQs for CRLFs consuming small insects exceed
the chronic species LOG (1.0) for all foliar application uses of triclopyr except
rice. Refined chronic dietary-based RQs for CRLFs consuming small herbivore
mammals (either 15g or 35g) exceed the chronic species LOG (1.0) for all foliar
application uses of triclopyr. Refined chronic dietary-based RQs for CRLFs
consuming large insects, small insectivore mammals (either 15g or 35g), and
small terrestrial-phase amphibians (weighing 2.3g) exceed the chronic species
LOG (1.0) for foliar uses of triclopyr with application rates greater than or equal
to 8 Ib ae/A.
For granular uses of triclopyr the resulting LD50/ft2s for all granular application
uses of triclopyr exceed the Agency's acute endangered species LOG of 0.1 for
birds weighing 20 and IQOg, ranging from 2.05 (Commercial/Industrial Lawns)
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Assessment
Eiulpoint
Effects
Determination 1
Basis for Determination
LAA
LAA
to 0.32 (Ornamental Lawns and Turf) for 20g birds, and 1.04
(Commercial/Industrial Lawns) to 0.16 (Ornamental Lawns and Turf) for lOOg
birds. The probability of individual effect at the endangered species LOG (0.1)
ranges from 1 in 1.09 (92%) at anRQ of 2.05 (Commercial/Industrial Lawns) to
1 in 1.88 (53%) at anRQ of 1.04 (Ornamental Lawns and Turf) for birds
weighing 20g. For birds weighing 100 g LD50/ft2 the probability of individual
effect at the endangered species LOC (0.1) ranges from 1 in 7.70*101 (1.3%) at
an RQ of 0.32 (Commercial/Industrial Lawns) to 1 in 5.85* 103 (0.02%) at an RQ
of 0.16 (Ornamental Lawns and Turf).
Potential for Indirect Effects
Aquatic prey items, aquatic habitat, cover and/or primary productivity
LOCs for non-vascular plants are exceeded for most uses of triclopyr. The non-
vascular plant RQs range from 35.71 for lakes/ponds/reservoirs to 0.08 for
ornamental lawns and turf.
LOCs for vascular plants are exceeded for many uses of triclopyr. The vascular
plant RQs range from 2.91 for lakes/ponds/reservoirs to 0.01 for ornamental
lawns and turf.
LOCs for aquatic invertebrates are exceeded for most uses of triclopyr. The acute
RQs range from 10.00 (Lakes/ponds/reservoirs) to 0.02 (Ornamental lawns and
turf). Population reduction in aquatic invertebrate prey items for the CRLF from
application of triclopyr ranges from 100% (Lakes/ponds/reservoirs) to < 0.1%
(Ornamental lawns and turf). The chronic RQs range from 0.10 for
lakes/ponds/reservoirs to <0.01 for ornamental lawns and turf.
For fish/and aquatic-phase amphibians most uses of triclopyr exceed the acute
and chronic LOCs for listed species (acute, 0.05 and chronic, 1.0). The RQs
range from 0.02 (Ornamental lawns and turf) to 9.62 (Lakes/ponds/reservoirs).
The chronic RQs range from 131.58 (Lakes/ponds/reservoirs) to 0.21 for
(Ornamental lawns and turf).
Terrestrial prey items, riparian habitat
RQs could not be calculated for terrestrial invertebrates as the toxicity endpoint
was not a definitive value. But because the calculated terrestrial small insect
EEC's exceed the highest levels tested, there is a potential indirect impact to the
terrestrial-phase CRLF from a reduction of invertebrate food items.
For small terrestrial mammals, the acute dose-based RQs exceed the acute risk
LOC (0.1) for all foliar application uses of triclopyr ranging from 10.7
(Agricultural Uncultivated Areas) to 0.11 (Rice). Both dietary and dose-based
chronic RQs exceed the chronic risk LOC (1.0) for all foliar application uses of
triclopyr ranging from 1222.9 (Agricultural Uncultivated Areas) to 13.1 (Rice)
[Dose-based] and 141 (Agricultural Uncultivated Areas) to 1.51 (Rice) [Dietary-
based]. Population reduction in small mammal prey items for the CRLF from
application of triclopyr ranges from 100% (agricultural uncultivated areas) to
0.0008% (rice) for foliar applications of triclopyr.
For granular uses of triclopyr the resulting LD50/ft2s for all granular application
uses of triclopyr exceed the Agency's acute endangered species LOC of 0.1 for
mammals weighing 15g and 35g, ranging from 0.83 (Commercial/Industrial
Lawns) to 0.42 (Ornamental Lawns and Turf) for mammals weighing 15g, and
0.44 (Commercial/Industrial Lawns) to 0.22 (Ornamental Lawns and Turf) for
mammals weighing 35g. Population reduction in small mammal prey items for
14
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Assessment
Eiulpoint
Effects
Determination 1
Basis for Determination
the CRLF from application of triclopyr ranges from 36% (Commercial/Industrial
Lawns) to 0.15% (Ornamental Lawns and Turf) for granular applications of
triclopyr to mammals weighing 15g and 35g.
The refined acute RQs (dietary- and dose-based) for small terrestrial-phase
amphibians did not exceed the listed species LOG (0.1) for any use of triclopyr.
However, the refined chronic dietary-based RQs exceed the chronic species LOG
(1.0) for small terrestrial-phase amphibians (weighing 2.3g) for foliar uses of
triclopyr with application rates greater than or equal to 8 Ib ae/A. Reduction in
amphibian prey items, specifically other frogs may potentially be affected from
chronic exposure of triclopyr as the result of triclopyr use.
The RQs for non-target terrestrial monocots and dicot plants inhabiting semi-
aquatic areas exceed the Agency's risk to terrestrial plant LOG (1.0) for all uses
of triclopyr both foliar (aerial and ground) and granular applications. RQs for
non-target terrestrial monocots and dicot plants inhabiting upland dry areas
exceed the Agency's risk to terrestrial plant LOG (1.0) for all uses of triclopyr
except rice both foliar (aerial and ground) and granular applications. Aerial
foliar applications of triclopyr result in spray drift RQ exceedances for dicot non-
target species for all uses of triclopyr. Aerial foliar applications of triclopyr
result in spray drift RQ exceedances for monocots for all uses except rice uses.
Ground foliar applications result in spray drift RQ exceedances for both
monocots and dicots for all uses except rice.
1 No effect (NE); May affect, but not likely to adversely affect (NLAA); May affect, likely to adversely
affect (LAA)
Table 1-2 Effects Determination Summary for Triclopyr Use and CRLF Critical
Habitat Impact Analysis
Assessment
Endpoint
Effects
Determination l
Basis for Determination
Modification of
aquatic-phase PCE
Habitat
Modification
Due to aquatic vascular and terrestrial plant communities being reduced from a
majority of use sites, there is potential for alteration of channel/pond morphology
or geometry and/or increase in sediment deposition within the stream channel or
pond. These plant communities provide shelter, foraging, predator avoidance,
and aquatic dispersal for juvenile and adult CRLFs. In addition, there is potential
for 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.
LOCs are exceeded for terrestrial riparian plants and for aquatic vascular plants
from exposure to triclopyr from spray drift. LOCs for non-vascular plants are
exceeded for many uses of triclopyr.
Modification of
terrestrial-phase
PCE
Habitat
Modification
The use of triclopyr at all sites may create the following effects to PCE:
elimination and/or disturbance of upland habitat; ability of habitat to support
food source of CRLFs, elimination and/or disturbance of dispersal habitat,
reduction and/or modification of food sources for terrestrial phase juveniles and
adults, and alteration of chemical characteristics necessary for normal growth
and viability of juvenile and adult CRLFs and their food source.
The RQs for non-target terrestrial monocots and dicot plants inhabiting semi-
aquatic areas exceed the Agency's risk to terrestrial plant LOG (1.0) for all uses
of triclopyr both foliar (aerial and ground) and granular applications. RQs for
15
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Assessment
Eiulpoint
Effects
Determination 1
Basis for Determination
non-target terrestrial monocots and dicot plants inhabiting upland dry areas
exceed the Agency's risk to terrestrial plant LOG (1.0) for all uses of triclopyr
except rice both foliar (aerial and ground) and granular applications. Aerial
foliar applications of triclopyr result in spray drift RQ exceedances for dicot non-
target species for all uses of triclopyr. Aerial foliar applications of triclopyr
result in spray drift RQ exceedances for monocots for all uses except and rice.
Ground foliar applications result in spray drift RQ exceedances for both
monocots and dicots for all uses except rice.
The use of triclopyr on most use sites will exceed the refined acute dietary- and
dose-based LOG and chronic LOG for prey food items of small mammals, and
invertebrates (foliar and granular applications). Food sources for the CRLF are
reduced, and the CRLF is indirectly affected from this reduction.
Habitat Modification or No effect (NE)
Table 1-3 Triclopyr Use-specific Direct Effects Determinations1 for the CRLF
Use(s)
Agricultural Uncultivated Areas (Max. Foliar)
Forest Tree/Pest Management (Median Foliar)
Douglas-Fir (Forest/Shelterbelt) (Median Foliar)
Rice (Min Foliar)
Commercial/Industrial Lawns (Max. Granular)
Ornamental Lawns and Turf (Min Granular)
Aquatic Habitat
Acute
LAA
LAA
LAA
LAA
LAA
NLAA
Chronic
LAA
LAA
LAA
LAA
LAA
NLAA
Terrestrial Habitat
Acute
LAA
LAA
LAA
NLAA
LLA
LAA
Chronic
LAA
LAA
LAA
LAA
LAA
LAA
1 NE = No effect; NLAA = May affect, but not likely to adversely affect; LAA = Likely to adversely affect
Table 1-4 Triclopyr Use-specific Indirect Effects Determinations1 Based on Effects
to Prey
Use(s)
Agricultural Uncultivated Areas
(Max. Foliar)
Forest Tree/Pest Management
(Median Foliar)
Douglas-Fir (Forest/Shelterbelt)
(Median Foliar)
Rice (Min Foliar)
Commercial/Industrial Lawns
(Max. Granular)
Ornamental Lawns and Turf
(Min Granular)
Algae
LAA
LAA
NLAA
LAA
NLAA
NLAA
Aquatic Invertebrates
Acute
LAA
LAA
LAA
LAA
LAA
NLAA
Chronic
NLAA
NLAA
NLAA
NLAA
NLAA
NLAA
Terrestrial
Invertebrates
(Acute)
LAA
LAA
LAA
LAA
LAA
LAA
Aquatic-phase
frogs and fish
Acute
LAA
LAA
LAA
LAA
LAA
NLAA
Chronic
LAA
LAA
LAA
LAA
LAA
NLAA
Terrestrial-phase
frogs
Acute
LAA
LAA
LAA
NLAA
LAA
LAA
Chronic
LAA
LAA
LAA
LAA
N/A
N/A
Small Mammals
Acute
LAA
LAA
LAA
NLAA
LAA
LAA
Chronic
LAA
LAA
LAA
LAA
N/A
N/A
1 NE = No effect; NLAA = May affect, not likely to adversely affect; LAA = Likely to adversely affect
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 direct/indirect and adverse
habitat modification effects determinations, it is important to note that pesticide
exposures and predicted risks to the species and its resources (i.e., food and habitat) are
not expected to be uniform across the action area. In fact, given the assumptions of drift
and downstream transport (i.e., attenuation with distance), pesticide exposure and
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associated risks to the species and its resources are expected to decrease with increasing
distance away from the treated field or site of application. Evaluation of the implication
of this non-uniform distribution of risk to the species would require information and
assessment techniques that are not currently available. Examples of such information and
methodology required for this type of analysis would include the following:
• Enhanced information on the density and distribution of CRLF life stages
within specific recovery units and/or designated critical habitat within the
action area. This information would allow for quantitative extrapolation
of the present risk assessment's predictions of individual effects to the
proportion of the population extant within geographical areas where those
effects are predicted. Furthermore, such population information would
allow for a more comprehensive evaluation of the significance of potential
resource impairment to individuals of the species.
• Quantitative information on prey base requirements for individual aquatic-
and terrestrial-phase frogs. While existing information provides a
preliminary picture of the types of food sources utilized by the frog, it
does not establish minimal requirements to sustain healthy individuals at
varying life stages. Such information could be used to establish
biologically relevant thresholds of effects on the prey base, and ultimately
establish geographical limits to those effects. This information could be
used together with the density data discussed above to characterize the
likelihood of adverse effects to individuals.
• Information on population responses of prey base organisms to the
pesticide. Currently, methodologies are limited to predicting exposures
and likely levels of direct mortality, growth or reproductive impairment
immediately following exposure to the pesticide. The degree to which
repeated exposure events and the inherent demographic characteristics of
the prey population play into the extent to which prey resources may
recover is not predictable. An enhanced understanding of long-term prey
responses to pesticide exposure would allow for a more refined
determination of the magnitude and duration of resource impairment, and
together with the information described above, a more complete prediction
of effects to individual frogs and potential modification to critical habitat.
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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. Environmental Protection Agency's (EPA's) Guidance for Ecological
Risk Assessment (U.S. EPA 1998), the Services' Endangered Species Consultation
Handbook (U.S. FWS/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 (U.S. FWS/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
triclopyr on rice, waterways, pasture, wetlands, orchard stump treatments, ornamentals,
forests, rights-of-way, commercial and industrial outdoor premises and lawns, and
residential outdoor premises and lawns. In addition, this assessment evaluates whether
use on these sites is expected to result in modification of the species' designated critical
habitat. This ecological risk assessment has been prepared consistent with a settlement
agreement in the case Center for Biological Diversity (CBD) vs. EPA et al. (Case No. 02-
1580-JSW(JL) settlement entered in 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, Tier I Rice Model, T-REX, TerrPlant,
and AgDRIFT all of which are described at length in the Overview Document.
Additional refinements include the use of the T-HERPS model to predict concentrations
of triclopyr granules in terrestrial invertebrates food items for terrestrial-phase CRLFs
and mammals. Use of such information is consistent with the methodology described in
the Overview Document (U.S. EPA 2004), 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 triclopyr is based on an action area. The action area is the area directly or
indirectly affected by the federal action, as indicated by the exceedance of the Agency's
Levels of Concern (LOCs). It is acknowledged that the action area for a national-level
FIFRA regulatory decision associated with a use of triclopyr may potentially involve
numerous areas throughout the United States and its Territories. However, for the
18
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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 triclopyr 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.
If the results of initial screening-level assessment methods show no direct or indirect
effects (no LOG exceedances) upon individual CRLFs or upon the PCEs of the species'
designated critical habitat, a "no effect" determination is made for use of triclopyr as it
relates to this species and its designated critical habitat. If, however, potential direct or
indirect effects to individual CRLFs are anticipated 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 triclopyr.
If a determination is made that use of triclopyr within the action area(s) associated with
the CRLF "may affect" this species 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 triclopyr use sites) and further evaluation of the potential impact of triclopyr
on the PCEs is also used to determine whether modification of 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
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 triclopyr is expected to directly impact living organisms within the action area
(defined in Section 2.7), critical habitat analysis for triclopyr is limited in a practical
sense to those PCEs of critical habitat that are biological or that can be reasonably linked
to biologically mediated processes (i.e., the biological resource requirements for the listed
species associated with the critical habitat or important physical aspects of the habitat that
may be reasonably influenced through biological processes). Activities that may modify
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critical habitat are those that alter the PCEs and appreciably diminish the value of the
habitat. Evaluation of actions related to use of triclopyr that may alter the PCEs of the
CRLF's critical habitat form the basis of the critical habitat impact analysis. Actions that
may affect the CRLF's designated critical habitat have been identified by the Services
and are discussed further in Section 2.6.
2.2 Scope
Triclopyr is a systemic non-selective herbicide used to control broadleaf weeds and
woody plants. It is a member of the pyridinyloxyacetic acid chemical family, and its
mode of action is growth regulation, resulting in abnormal growth of plants. Formulation
types that are registered include emulsifiable concentrate, liquid, and granular. Currently,
the labeled uses of triclopyr include rice, waterways, pasture, wetlands, orchard stump
treatments, ornamentals, forests, rights-of-way, commercial and industrial outdoor
premises and lawns, and residential outdoor premises and lawns. All of these uses are
considered as part of the federal action evaluated in this assessment.
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 triclopyr in accordance with the approved product labels for
California is "the action" relevant to this ecological risk assessment.
Although current registrations of triclopyr allow for use nationwide, this ecological risk
assessment and effects determination addresses currently registered uses of triclopyr 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.
Triclopyr acid is formulated as a manufacturing use product which is then formulated int
two end use products; triclopyr butoxyethyl ester (triclopyr BEE) and triclopyr
triethylamine salt (triclopyr TEA). Both triclopyr TEA and BEE active ingredients
rapidly degrade back to triclopyr acid within an aqueous environment. Triclopyr TEA
rapidly dissociates in water to the triclopyr acid/anion and triethanolamine. Triclopyr
BEE rapidly hydrolyzes in the environment to the triclopyr acid/anion and butoxyethanol.
Both triethanolamine and butoxyethanol are also rapidly dissipated by microbial
degradation, and thus are not being evaluated any further in this assessment. Triclopyr
acid forms the degradation products; 3,5,6-trichloro-2-pyridinal (TCP) and 3,5,6-
trichloro-2-methoxypyridine (TMP) as a result of microbial degradation in aerobic soil.
TMP is considered a minor degradate and TCP, although a major degradate, is not of
toxicological concern since (in terms of acid equivalency) it is not more sensitive than the
lowest triclopyr endpoints. As a result, neither TCP nor TMP will be further evaluated in
this assessment.
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The Agency does not routinely include, in its risk assessments, an evaluation of mixtures
of active ingredients, either those mixtures of multiple active ingredients in product
formulations or those in the applicator's 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
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; U.S.
FWS/NMFS 2004).
An analysis of the available open literature and acute mammalian toxicity data for
multiple active ingredient products relative to the single active ingredient (triclopyr) is
provided in Appendix B. The resulting analysis of the LD50 values and associated 95%
confidence intervals (CIs) that are available for multiple active ingredient products
containing triclopyr, found that toxicity of these compounds was not significantly
different than the single active ingredient products of triclopyr alone. Therefore, the
assessment is based on the toxicity of the single active ingredient of triclopyr.
As discussed in USEPA (2000) a quantitative component-based evaluation of mixture
toxicity requires data of appropriate quality for each component of a mixture. In this
mixture evaluation an LD50 with associated 95% Confidence Interval (CI) is needed for
the formulated product. The same quality of data is also required for each component of
the mixture. In the case of triclopyr, only one product (EPA Reg. No. 71085-29) has a
definitive LD50 value with an associated 95% CI. In the case of EPA Reg No. 71085-29,
the toxicity can be attributed to propanil (the other active ingredient in the formulated
product). When the LD50 (1750 mg/kg) for this product and its confidence interval
(1239-4450 mg/kg) are adjusted for the percent propanil (36.5%), the adjusted LD50
value of 639 mg/kg (CI: 452-1624 mg/kg), the adjusted confidence interval falls within
the confidence interval for the propanil technical (868-1343 mg/kg), Appendix B.
Given that the active would not be expected to have similar mechanisms of action,
metabolites or toxicokinetic behavior it is also reasonable to conclude that an assumption
of dose-addition would be inappropriate. Consequently, an assessment of triclopyr's
potential effect on the CRLF when it is co-formulated with other active ingredients can
be based on the toxicity of triclopyr.
2.3 Previous Assessments
Triclopyr TEA was first registered on May 8, 1979 as an herbicide on non-crop areas and
forestry use for the control of broadleaf weeds and woody plants. Triclopyr BEE was
subsequently registered on June 11, 1980 for use on the same sites. Both formulations
were registered for use on turf sites in 1984. On April 16, 1985, triclopyr BEE was
registered for use on rangeland and permanent grass pastures. Most recently (January 11,
1995), triclopyr TEA was registered for use on rice to manage many hard to control
broadleaf weed species.
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At the time of the Reregi strati on Eligibility Decision (RED, 1998) an application for
registration on aquatic use sites was pending. A Data Call-In Notice (DCI) was issued in
August 1991 requiring the submission of product chemistry, residue chemistry,
ecological and environmental fate data for both triclopyr TEA and BEE and toxicological
data for TEA.
A Reregi strati on Eligibility Decision (RED) on triclopyr was issued in October 1998.
This RED largely addressed the human health issues required by the Food Quality
Protection Act but some ecological issues were raised as well. EPA worked with the
registrant to define mitigation measures including label improvements to reflect lower
maximum application rates and to implement spray drift management practices that
would reduce calculated risks to non-target organisms. The highest application rate (12
Ibs ae/A) used to calculate RQs would no longer be permitted. Rather, maximum
application rates of 1-9 Ibs ae/A would be used dependent on the type of site. Despite
more restrictive application rates, the LOG was still exceeded for mammals (chronic),
fish (BEE; acute) aquatic plants (BEE) and terrestrial plants.
The risks associated with a toxic metabolite of triclopyr, 3,5,6-trichloro-2-pyridinol
(TCP), had not been fully characterized at the time of the RED. TCP data gaps were
indicated and required for early life stage fish and aerobic aquatic metabolism. A TCP
early life stage fish study has been submitted and rated as invalid. A TCP aerobic aquatic
metabolism study has not been submitted.
In May 2004 the Agency completed an Effects Determination for 3 threatened or
endangered Pacific anadromous salmon and steelhead based on triclopyr BEE uses in
California forestry applications. That Effects Determination concluded that triclopyr
BEE would have no effect on 1 ESU and was Not Likely to Adversely Affect the other 2
ESUs from registered uses on Forestry in California. In spite of the NLAA and No Effect
findings, EPA initiated formal consultation with the National Marine Fisheries Service
consistent with a Consent Decree in the litigation brought by the Californians for
Alternatives to Pesticides (CATs v. EPA).
The Agency also completed an Effects Determination for 26 threatened and endangered
Pacific anadromous salmon and steelhead in December 2004 based on all registered uses
of triclopyr BEE in the Pacific Northwest and California, consistent with a court order in
WTC v. EPA (Case No. l:04-Cv-00126-Ckk, 2004). The results of that endangered
species risk assessment showed that the use of triclopyr BEE may affect and was likely to
adversely affect 16 Evolutionary Significant Units (ESUs) and may affect but is not likely to
adversely affect 10 ESUs of Pacific salmon and steelhead when used according to labeled
application directions
(http://www.epa.gov/oppfead 1 /endanger/litstatus/effects/#trifluralin). The National
Marine Fisheries Service has indicated it will review EPA's determinations regarding
effects of triclopyr to the Pacific salmon and steelhead, and complete consultation with
issuance of a Biological Opinion in November 2010.
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2.4 Stressor Source and Distribution
2.4.1 Environmental Fate Assessment
Triclopyr TEA rapidly dissociates in water to the triclopyr acid/anion and
triethanolamine. Triclopyr BEE rapidly hydrolyzes in the environment to the triclopyr
acid/anion and butoxyethanol. Both triethanolamine and butoxyethanol are rapidly
dissipated by microbial degradation. Triclopyr acid is a weak acid which will dissociate
completely to the triclopyr anion at pHs > 5 (dissociation constant pKa 2.93). Therefore,
the triclopyr anion will be the predominant moiety present in the environment when
products containing either triclopyr BEE or triclopyr TEA are used. In the environment
triclopyr acid/anion is somewhat persistent, and is mobile. For triclopyr the predominant
degradation pathway in water is photodegradation, and the predominant degradation
pathway in soil is microbial degradation to the major degradate 3,5,6-trichloro-2-
pyridinal (TCP), which is both persistent and mobile, but (in terms of acid equivalency) it
is not more sensitive than the endpoints used to evaluate ecological risk in this
assessment (see Table 4-1 and Table 4-3, and Appendix A for endpoints).
Triclopyr TEA is a non-volatile, very soluble salt (vapor pressure < IxlO"8; solubility
4.12xl05 mg/L at pH 7). Triclopyr BEE is non-volatile (vapor pressure 3.6xlO"6 mm Hg)
and shows relatively low solubility (6.8 ppm). The primary degradation pathway for
triclopyr TEA is dissociation to the triclopyr acid and triethanolamine. Triethanlamine is
then degraded by aerobic microbial processes to CC>2 (soil half-life 5.6-13.7 days)
(MRID 43837501). It is stable in aquatic conditions with a half-life 14-18 days and then
proceeds to rapid degradation (MRID 43837503). Triethanolamine is stable to
degradation under anaerobic aquatic conditions (half-life > 2 years). Because of the rapid
microbial degradation under aerobic conditions, it is not expected that volatilization,
photodegradation, or bioaccumulation in fish will contribute significantly to the
dissipation of triethanolamine (MRID 41219101).
Triclopyr TEA will not persist as the salt under normal environmental conditions. In
measurements of conductance of a solution of triclopyr TEA in water as a function of
time, triclopyr TEA dissolved and dissociated completely to the acid within one minute.
As a result, triclopyr TEA will be looked at with respect to the triclopyr acid.
The primary degradation pathway for triclopyr BEE is hydrolysis to triclopyr acid and 2-
butoxyethanol, with hydrolysis occurring more rapidly at higher pHs (MRID 134174). 2-
Butoxyethanol is then rapidly degraded by microbial processes (aerobic soil and aquatic)
to 2-butoxyacetic acid (half-lives of 0.9 hrs - 1.4 hrs in soil; half-life of 0.6-3.4 days in a
sediment/water mixture), with the final degradate as CO2 (MRID 43799101). 2-
Butoxyethanol and 2 butoxyacetic acid are somewhat more persistent under anaerobic
aquatic conditions (half-lives of 1.4 and 73.3 days respectively in an anaerobic
sediment/water mixture) with the final degradate as CC>2 (MRID 43799103). It is not
expected that volatilization will contribute significantly to the dissipation of 2-
butoxyethanol. Because of the rapid microbial degradation, it is not expected that
23
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photodegradation or bioaccumulation in fish will contribute significantly to the
dissipation of butoxyethanol.
Triclopyr BEE will persist in the environment as the ester for only a limited duration.
Triclopyr BEE hydrolyzed quickly to triclopyr acid in natural waters (pH 6.7; half-life of
0.5 days; MRID 134174). Supplemental information indicates that triclopyr BEE
degrades to triclopyr acid with a half-life of about three hours when applied to silty clay
loam, silt loam, and sandy loam soils. In all three soils, less than 3.2% of the applied
triclopyr BEE in a terrestrial field dissipation study was detected at 1.1 days, while total
triclopyr (BEE plus triclopyr) half-life was 10.6 days (MRID 43837503). Since triclopyr
BEE also degrades relatively quickly to triclopyr acid, the acid will be focused on in the
assessment.
Both triclopyr BEE and triclopyr TEA may produce TCP which is relatively mobile and
persistent and has the potential to reach groundwater. Triclopyr and TCP do not adsorb
to soil and sediment particles, and may be transported in surface waters; information from
two aquatic field dissipation studies conducted on rice indicate that following application
of triclopyr, TCP can persist in flood waters. However, toxicity data for the degradate
indicates that when converted to the acid equivalent TCP is less toxic than the most
sensitive endpoint for triclopyr, and as a result, TCP is not being further evaluated in this
assessment (see Table 4-1, Table 4-3, and Appendix A for more information regarding
the endpoints).
Based on laboratory studies, triclopyr acid is stable to hydrolysis (MRID 41879601) and
anaerobic aquatic metabolism (MRID 151967), and it degrades slowly under aerobic
aquatic conditions (MRID 40479101). Triclopyr acid does not bioaccumulate in aquatic
organisms. It appears that aqueous photolysis is a predominant degradation mechanism
in aquatic media. Photodegradation of triclopyr acid was less than 1 day in sterile
solutions and approximately 1 day in natural water (MRID 41732201, MRID 42411804).
The major photodegradation products observed were 5-chloro-3,6-dihydroxy-2-
pyridinoloxyacetic acid in sterile solutions and oxamic acid in natural river water.
In soil, the predominant degradation mechanism for triclopyr acid is biotic metabolism.
Triclopyr acid degraded in aerobic soil with half-lives of 8 to 18 days to intermediate
degradates 3,5,6-trichloro-2-pyridinol (TCP) and 3,5,6-trichloro-2-methoxypyridine
(TMP); the ultimate degradate is carbon dioxide (MRID 40346304). TCP was also
observed as a minor degradate in the aerobic aquatic metabolism study. Based on
adsorption/desorption studies, triclopyr acid and its major degradate TCP are expected to
be very mobile in soils. Freundlich Kads for triclopyr were 0.165-0.975 mL/g (MRID
40749801). In the field dissipation studies, low concentrations of triclopyr were found in
soil depths of up to 45 cm; however, triclopyr did not persist (MRID 43955901, MRID
43033401).
Triclopyr acid degraded in 7.6 days to 10.6 days in field dissipation studies (MRID
43955901, MRID 43033401). TCP was detected up to 36 weeks after treatment in
vegetated soil; it represented a considerable amount (0.131 ppm) at 63 weeks (last test
24
-------
interval) in bare soil. In the forestry studies, TCP was generally limited to the upper 30
cm of the soil, with sporadic detections in deeper soil depths (MRID 43033401).
Although, these observations appear to represent TCP as persistent and mobile in the
field, it is not being assessed in this document since toxicity data for the degradate
indicates that when converted to the acid equivalent TCP is less toxic than the most
sensitive endpoint for triclopyr that are used to evaluate ecological risk (see Table 4-1,
Table 4-3, and Appendix A for more information regarding the endpoints). Table 2-1 lists
the environmental fate properties of triclopyr acid, along with the major and minor
degradates detected in the submitted environmental fate and transport studies.
Below is a schematic showing the relationship between triclopyr acid, TEA, BEE, and
their degradates. For chemical properties of TEA and BEE, please see Appendix P.
25
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C
Direct Aqueous Photolysis
c
Triclopyr Acid
c
TEA
)C
BEE
Triclopyr Acid
Triclopyr anion
C
Aerobic Soil Metabolism
Aerobic / Anaerobic Aquatic Metabolism
C
p-chloro-3,6-dihydroxy-2-pyridinyloxyacetic acid
Oxamic acid
)C
IMP
TCP
26
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Table 2-1 Summary of Triclopyr Acid Environmental Fate Properties
Study
Molecular Weight
Aqueous Solubility
(25o C)
Vapor Pressure
(25o C)
Henry's Law
constant
Hydrolysis
Direct Aqueous
Photolysis
Soil Photolysis
Aerobic Soil
Metabolism
Anaerobic Aquatic
Metabolism
Aerobic Aquatic
Metabolism
Kd-ads / Kd-des
(mL/g)
KOC- ads / Koc_des
(mL/g)
Terrestrial Field
Dissipation
Aquatic Field
Dissipation
Value (units)
256.47 g/mol
440 mg/L
1.26xlO-6torr
9.66 x 10"' atm m3 mol"1
Stable at pH 5, 7, 9
8-9 hours (natural light)
1.7 days (In river water)
No acceptable data
8 days in silty clay loam soil at 25 °C
18 days in silt loam soil at 25 °C
Stable (1300 days)
142 Days in silty clay soil at 24° - 26° C
0.975 in Kalkasda Sand
0.571 in Londo sandy loam
0. 165 in Commerce silty loam
0.733 in Mahoun clay loam
134 in Kalkasda Sand (% OC 0.73)
25 in Londo sandy loam (% OC 2.25)
25 in Commerce silty loam (% OC 0.67)
53 in Mahoun clay loam (% OC 1.38)
7.6 to 10.6 days
Lake: Triclopyr 3.6 days (30 ° C)
Aquatic Plants: Triclopyr 3.4 days (30 ° C)
Crayfish: Triclopyr 11.5 days (30 ° C)
Clam Tissue: Triclopyr 1.5 days (30 ° C)
Major Degradates
Minor Degradates
NA
NA
NA
NA
No degradates reported
5-Chloro-3,6-dihydroxy-2-
pyridinyloxyacetic acid and
oxamic acid (combined = 48% )
Oxamic acid (16%)
No acceptable data
TCP (26.4%)
3,5,6-trichloro-2-methoxypyridine
(7.8%)
CO2 (79.3%)
TCP (26%)
TCP ( < 5% )
Treated soil: TCP (2%)
Treated soil: CO2 (28.3%)
Supernatant: TCP (12.24%)
Supernatant: Unidentified
residues (3.4%)
No degradates reported
No degradation products reported.
Source/
MRID
http://toxnet.nl
m.nih.sov
http://toxnet.nl
m. nih.gov
http://toxnet.nl
m. nih.gov
Estimated by
Calculation
(VP*MWX?
60*solubility)
MRID
41879601
MRID
41732201 &
42411804
MRID
41732201 &
42411804
No acceptable
data
MRID
40346304
MRID
151967
MRID
40479101
MRID
40749801
MRID
40749801
MRID
43955901
43033401
MRID
41714304
Study Status
NA
NA
NA
NA
Acceptable
Acceptable
Supplemental
Soil Photolysis
Acceptable
Acceptable
Acceptable
Acceptable
Acceptable
Acceptable
Acceptable
NA: Not Applicable
27
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2.4.2 Environmental Transport Assessment
Potential transport mechanisms expected to be the major routes of exposure for triclopyr
include pesticide spray drift, runoff, and direct application.
AIR
Triclopyr is applied by broadcast to the paddy water surface using ground or aerial
equipment, suggesting that there is a possibility of drift. Likewise, triclopyr is applied by
broadcast using ground or aerial equipment to a variety of other agricultural and non-
agricultural sites. Triclopyr is relatively non-volatile, as indicated by its vapor pressure
(1.26 x 10"6torr) and Henry's Law Constant (9.66 x 10"7 atm m3 mol"1). These properties
indicate that long range transport of triclopyr is unlikely.
In general, deposition of drifting pesticides is expected to be greatest close to the site of
application. A computer model of spray drift (AgDRIFT) is used to determine potential
exposures to aquatic and terrestrial organisms via spray drift. The distance of potential
impact away from the use sites is determined by the distance required to fall below the
LOG for the use with the greatest application rate, greatest number of applications per
season, and the least amount of time between applications. For triclopyr, this use would
be agricultural uncultivated areas.
WATER/RICE
Triclopyr is applied directly to water for its use on rice, thus exposure in water is
expected, especially if rice paddies and receiving waters are used as CRLF habitat.
Monitoring data indicate that triclopyr is frequently detected in receiving waters.
Exposure due to runoff is determined using PRZM/EXAMS. Again, the greatest
application rate, greatest number of applications per season, and the least amount of time
between applications is used to determine the maximum amount of triclopyr that would
be expected in run off. An additional factor taken into account is the crop scenario which
incorporates meteorological data that is specific to the date of application. In addition to
the physical-chemical properties of a compound, the season in which a crop is grown can
also determine the probability of runoff as well as the quantity of chemical found in the
runoff.
SOIL
The SCI-GROW model (Screening Concentration in Ground Water Program (SCI-
GROW) VERSION 2.3 was used to predict the maximum chronic and acute
concentration of triclopyr derived from shallow ground water based on the maximum
application rate of 20 Ib ae/A, 17 times per year. The screening concentration was found
to be 132 ppb. However, all of the aquatic uses have much larger concentrations (2500
ppb) and all of the aquatic uses have EECs greater than the LOG (See Section 3.0). As a
result, base flow is a potential route of exposure for triclopyr, but is more than a
magnitude less than the concentrations due to direct aquatic application.
28
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2.4.2
Mechanism of Action
BEE is rapidly hydrolyzed to the triclopyr acid when absorbed by plants. Triclopyr acid
readily penetrates foliage, and is readily absorbed by plant roots. The mode of action is
growth regulation, resulting in abnormal growth. Specifically, the primary action appears
to involve cell wall plasticity and nucleic acid metabolism, similar to that of endogenous
auxins (lAAs). Triclopyr is believed to acidify the cell wall by stimulating the activity of
a membrane-bound ATPase proton pump. In high concentrations, triclopyr and other
auxin type herbicides reduces cell division and growth. Also, auxin type herbicides cause
chlorosis (yellowing of leaves due to lack of chlorophyll), and leaves to curl up^end
(known as epinasty). Due to triclopyr's mechanism and mode of action it is considered to
be less effective if not given at least four hours to dry.
2.4.3
Use Characterization
Analysis of labeled use information is the critical first step in evaluating the federal
action. The current label for triclopyr 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.
Table 2-2 presents the uses and corresponding application rates and methods of
application considered in this assessment.
Table 2-2 Triclopyr Uses Assessed for the CRLF1
Use (Application Method)
AGRICULTURAL FALLOW/IDLELAND
AGRICULTURAL RIGHTS-OF-
WAY/FENCEROWS/HEDGEROWS
AGRICULTURAL UNCULTIVATED AREAS
AGRICULTURAL/FARM PREMISES
AGRICULTURAL/FARM
STRUCTURES/BUILDINGS AND EQUIPMENT
AIRPORTS/LANDING FIELDS
AQUATIC AREAS/WATER
CHRISTMAS TREE PLANTATIONS
COMMERCIAL STORAGES/WAREHOUSES
PREMISES
COMMERCIAL/INDUSTRIAL LAWNS
Max.
Single
Appl. Rate
(lb ae/A)
12
4.5
9
20
2
20
1.5
20
12
NA
6
20
9
Max.
Number of
Application
per Year
1
1
17
17
17
17
17
17
17
NA
17
17
2
Interval
Between
Application
(Day)
0
0
21
21
21
21
21
21
21
NA
21
21
21
Application
Method
Aircraft
Ground
Aircraft
Ground
Ground
Aircraft
Ground
Aircraft
Ground
Ground
Aircraft
Ground
Ground spray
Injection
Ground
Ground
29
-------
Use (Application Method)
COMMERCIAL/INSTITUTIONAL/INDUSTRIAL
PREMISES/EQUIPMENT (OUTDOOR)
CONIFER RELEASE
DOUGLAS-FIR (FOREST/SHELTERBELT)
DRAINAGE SYSTEMS
FENCEROWS/HEDGEROWS
FOREST TREE MANAGEMENT/FOREST PEST
MANAGEMENT
FOREST TREES (ALL OR UNSPECIFIED)
GOLF COURSE TURF
HOUSEHOLD/DOMESTIC DWELLINGS
OUTDOOR PREMISES
INDUSTRIAL AREAS (OUTDOOR)
INTERMITTENTLY FLOODED AREAS/WATER
LAKES/PONDS/RESERVOIRS (WITH HUMAN
OR WILDLIFE USE)
NONAGRICULTURAL RIGHTS-OF-
WAY/FENCEROWS/HEDGEROWS
NONAGRICULTURAL UNCULTIVATED
AREAS/SOILS
ORCHARDS (non-food stump treatment)
ORNAMENTAL AND/OR SHADE TREES
ORNAMENTAL HERBACEOUS PLANTS
ORNAMENTAL LAWNS AND TURF
ORNAMENTAL NONFLOWERING PLANTS
ORNAMENTAL SOD FARM (TURF)
ORNAMENTAL WOODY SHRUBS AND VINES
PASTURES
PAVED AREAS (PRIVATE
ROADS/SIDEWALKS)
Max.
Single
Appl. Rate
(lb ae/A)
1.5
12
3.2
6
1.5
12
20
3
8
6
20
12
12
12
20
6
NA
NA
12
20
12
20
9
6
0.53
0.76
2
0.53
9
1.5
6
4.5
9
12
20
Max.
Number of
Application
per Year
17
17
17
17
17
1
17
2
17
17
17
17
17
1
17
17
NA
NA
1
17
1
17
17
17
17
1
17
17
4
2
17
1
17
1
17
Interval
Between
Application
(Day)
21
21
21
21
21
0
21
30
21
21
21
21
21
0
21
21
NA
NA
0
21
0
21
21
21
21
0
21
21
21
21
21
0
21
0
21
Application
Method
Spreader
Ground
Aircraft
Ground
Injection
Sprayer
Aircraft
Ground
Aircraft
Ground
Aircraft
Ground
Aircraft
Ground
Ground
Ground
Aircraft
Ground
Aircraft
Ground
Aircraft
Ground
Aircraft
Ground
Aircraft
Ground
Ground
Aircraft
Ground
Package
applicator
Spreader
Ground
Package
applicator
Ground
Spreader
Aircraft
Ground
Aircraft
Ground
Aircraft
Ground
30
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Use (Application Method)
RANGELAND
RECREATION AREA LAWNS
RESIDENTIAL LAWNS
RICE
SWAMPS/MARSHES/WETLANDS/STAGNANT
WATER
Max.
Single
Appl. Rate
(lb ae/A)
4.5
9
12
1.5
9
1.5
0.38
NA
NA
Max.
Number of
Application
per Year
1
17
17
2
2
2
2
NA
NA
Interval
Between
Application
(Day)
0
21
21
28
21
28
21
NA
NA
Application
Method
Aircraft
Ground
Ground
Spreader
Ground
Spreader
Aircraft
Ground
Aircraft
Ground
*Note: The values above are very conservative. See Section 3.2 on how the intervals and maximum applications per
year were derived.
NA: Not applicable. These uses have a maximum allowable concentration of 2.5 ppm. Therefore, application rates
are dependant on volume of the body of water.
Provided below, Figure 2-1 shows the estimated poundage of triclopyr uses across the
United States. The map was downloaded from a U.S. Geological Survey (USGS),
National Water Quality Assessment Program (NAWQA) website.
-------
TRICLOPYR - herbicide
2002 estimated annual agricultural use
Average annual use of
active ingredient
(pounds per square mile of agricultural
land in county)
D no estimated use
D 0.001 to 0.026
D 0.027 to 0.083
D 0.084 to 0.23
D 0.231 to 0.691
• >= 0.692
Crops
pastureland
rice
other hay
sod harvested
blueberries
Total
Pounds Applied
1080479
151144
100670
2540
10
Percent
National Use
80.94
11.32
7.54
0.19
0.00
Figure 2-1 Triclopyr Use for Agricultural Uses in Total Pounds per County
The Agency's Biological and Economic Analysis Division (BEAD) provides an analysis
of both national- and county-level usage information (County-Level Usage for
Strychnidin; Strychnin, Triclopyr, butoxyethyl ester; Triclopyr, triethalamine salt;
Diflubenzuron; Trifluralin; Thiobencarb; Chlorpyrifos; Vinclozolin; Iprodione in
California in Support of a Red Legged Frog Endangered Species Assessment, June 08,
2009) using state-level usage data obtained from USDA-NASS1, 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)
1 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.htnrfagchem.
32
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database2 . 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
triclopyr by county in this California-specific assessment were generated using CDPR
PUR data. Eight years (1999-2006) of usage data were included in this analysis. Data
from CDPR PUR were obtained for every pesticide application made on every use site at
the section level (approximately one square mile) of the public land survey system.
BEAD summarized these data to the county level by site, pesticide, and unit treated.
Calculating county-level usage involved summarizing across all applications made within
a section and then across all sections within a county for each use site and for each
pesticide. The county level usage data that were calculated include: average annual
pounds applied, average annual area treated, and average and maximum application rate
across all eight years. The units of area treated are also provided where available.
The usage data reported by CDPR PUR summarizing triclopyr's usage for all California
use sites is provided below in Table 2-3. The uses range from commercial and industrial
non-agricultural uses to agricultural uses, residential uses, and forestry uses, and water
uses. The uses considered in this risk assessment represent all currently registered uses
according to a review of all current labels. No other uses are relevant to this assessment.
Any reported use other than currently registered uses represent either historic uses that
have been canceled, mis-reported uses, or mis-use. Historical uses, mis-reported uses,
and misuse are not considered part of the federal action and, therefore, are not considered
in this assessment.
Table 2-3 Summary of California Department of Pesticide Registration (CDPR)
Pesticide Use Reporting (PUR) Data from 1999 to 2006 for Triclopyr Uses
Site Name
BUILDINGS/NON-AG OUTDROOR
CHRISTMAS TREE
COUNTY AGCOMM
DITCH BANK
FOREST, TIMBERLAND
INDUSTRIAL SITE
LANDSCAPE MAINTENANCE
N-GRNHS FLOWER
N-GRNHS PLANTS IN CONTAINERS
N-GRNHS TRANSPLANTS
N-OUTDR FLOWER
N-OUTDR PLANTS IN CONTAINERS
N-OUTDR TRANSPLANTS
Average
Annual
Ibs ae/A
Applied 2
0.01
0.81
0.00
1.36
1.08
0.69
0.85
1.01
0.22
0.11
1.03
0.87
1.27
Average
Application
Rate
(Ibs ae/A)2
0.0
1.9
0.0
1.4
0.8
0.8
1.2
1.5
0.2
0.2
0.9
1.0
1.7
Maximum
Application Rate
(Ibs ae/A)1
12
6.0
12
20
8.0
12
12
0.53
0.53
6.0
0.53
0.53
6.0
2 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.
33
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Site Name
ORCHARD FLOOR
PASTURELAND
PUBLIC HEALTH
RANGELAND
RECREATION AREA
REGULATORY PEST CONTROL
RICE
RICE, WILD
RIGHTS OF WAY
STORAGE AREA/BOX
STRUCTURAL PEST CONTROL
TURF/SOD
UNCULTIVATED AG
UNCULTIVATED NON-AG
VERTEBRATE CONTROL
WATER (INDUSTRLIAL)
WATER AREA
Average
Annual
Ibs ae/A
Applied 2
1.60
0.69
0.00
0.54
1.98
2.73
0.14
0.70
2.04
0.98
0.00
0.95
0.86
1.12
0.39
0.50
2.10
Average
Application
Rate
(Ibs ae/A)2
1.6
0.7
0.0
0.7
2.2
2.7
0.2
0.7
1.8
1.0
0.0
0.6
1.0
1.0
0.2
0.5
2.7
Maximum
Application Rate
(Ibs ae/A)1
9.0
9.0
12
9.0
12
20
0.38
0.38
20
12
20
12
20
20
20
9.0
9.0
1-Based on data supplied by BEAD (cite transmittal memo of data).
2- The average annual pounds applied and average application rate was calculated as the weighted average
of the average application rate for one county or average annual pounds applied for one county. The values
reflect the average annual pounds applied to that site across all counties and the average application rate for
that site across all counties.
2.5 Assessed Species
The CRLF was federally listed as a threatened species by U.S. FWS effective June 24,
1996 (U.S. FWS 1996). It is one of two subspecies of the red-legged frog and is the
largest native frog in the western United States (U.S. FWS 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 I.
Final critical habitat for the CRLF was designated by U.S. FWS on April 13, 2006 (U.S.
FWS 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 (U.S. FWS 1996). Its range has been reduced by about 70%,
34
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and the species currently resides in 22 counties in California (U.S. FWS 1996). The
species has an elevational range of near sea level to 1,500 meters (5,200 feet) (Jennings
and Hayes 1994); however, nearly all of the known CRLF populations have been
documented below 1,050 meters (3,500 feet) (U.S. FWS 2002).
Populations currently exist along the northern California coast, northern Transverse
Ranges (U.S. FWS 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 (U.S. FWS 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) (U.S. FWS 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
Attachment I). Recovery units, core areas, and other known occurrences of the CRLF
from the CNDDB are described in further detail in Attachment I, and designated critical
habitat is addressed in Section 2.6. Recovery units are large areas defined at the
watershed level that have similar conservation needs and 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 U.S. FWS to be important in the preservation of the
species. Designated critical habitat is generally contained within the core areas, although
a number of critical habitat units are outside the boundaries of core areas, but 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.
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.
35
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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
Southern Transverse and Peninsular Ranges
Legend
I I Recover/ Unit Boundaries
/ >,, < Currently Occupied Core Areas
^B Critical Habitat
*_^l CNDDB Occurence Sections
County Boundaries g 45
Core Areas
1. Feather River
Yuba River- S. Fork Feather River
Traverse Creek/ Middle Fork/ American R. Rubicon
Cosumnes River
South Fork Calaveras River*
Tuolumne River*
Piney Creek*
Cottonwood Creek
Putah Creek - Cache Creek*
9.
10. Lake Berryessa Tributaries
11. Upper Sonoma Creek
12. Petaluma Creek— Sonoma Creek
13. Pt. Reyes Peninsula
14. Belvedere Lagoon
15. Jameson Canyon - Lower Napa River
16. East San Francisco Bay
17. Santa Clara Valley
18. South San Francisco Bay
* Core areas that were historically occupied by the California red-legged frog are not included in the map
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
Watsonville Slough-Elkhorn Slough
Carmel River — Santa Lucia
Gablan Range
Estero Bay
Arroyo Grange River
Santa Maria River - Santa Ynez River
Sisquoc River
Ventura River - Santa Clara River
Santa Monica Bay - Venura Coastal Streams
Estrella River
San Gabriel Mountain*
Forks of theMojave*
Santa Ana Mountain*
Santa Rosa Plateau
San Luis Ray*
Sweetwater*
Laguna Mountain*
Figure 2-2 Recovery Unit, Core Area, Critical Habitat, and Occurrence
Designations for CRLF
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2.5.2 Reproduction
CRLFs breed primarily in ponds; however, they may also breed in quiescent streams,
marshes, and lagoons (Fellers 2005a). According to the Recovery Plan (U.S. FWS 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,
U.S. FWS 2002); tadpoles have been observed to over-winter (delay metamorphosis until
the following year) (Fellers 2005b; U.S. FWS 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 (U.S. FWS 2002). Figure 2-3 depicts CRLF annual reproductive
timing.
J
F
M
A
M
J
J
A
S
0
N
D
Light Blue =
Green = '.i ," • •_> v ~ those that over-winter)
Orange = •,,'<.',,'••.
Adults and juveniles can be present all year
Figure 2-3 CRLF Reproductive Events by Month
2.5.3 Diet
Although the diet of CRLF aquatic-phase larvae (tadpoles) has not been studied
specifically, it is assumed that their diet is similar to that of other frog species, with the
aquatic phase feeding exclusively in water and consuming diatoms, algae, and detritus
(U.S. FWS 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 andMcDiarmid 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
37
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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
(Stalls cf californicd)., 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 (U.S. FWS 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 (U.S. FWS 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 (U.S.
FWS 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://ecos.fws.gov/speciesProfile/SpeciesReport.do?spcode=D02D).
In general, dispersal and habitat use depends on climatic conditions, habitat suitability,
and life stage. Adults rely on riparian vegetation for resting, feeding, and dispersal. The
foraging quality of the riparian habitat depends on moisture, composition of the plant
community, and presence of pools and backwater aquatic areas for breeding. CRLFs can
be found living within streams at distances up to 3 km (2 miles) from their breeding site
and have been found up to 30 m (100 feet) from water in dense riparian vegetation for up
to 77 days (U.S. FWS 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
38
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trees or logs, industrial debris, and agricultural features (U.S. FWS 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 U.S. FWS (U.S. FWS 2006; FR 51 19244-19346). A
summary of the 34 critical habitat units relative to U.S. FWS-designated recovery units
and core areas (previously discussed in Section 2.5.1) is provided in Attachment I.
'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 (Section 7) 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
• Dispersal habitat.
Further description of these habitat types is provided in Attachment I.
Occupied habitat may be included in the critical habitat only if essential features within
the habitat may require special management or protection. Therefore, U.S. FWS does not
include areas where existing management is sufficient to conserve the species. Critical
39
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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 the Final Rule (FR)
listing notice in April 2006 (71 FR 19243, 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 I for a full explanation on this special rule.
U.S. FWS has established adverse modification standards for designated critical habitat
(U.S. FWS 2006). Activities that may destroy or adversely modify critical habitat are
those that alter the PCEs and jeopardize the continued existence of the species.
Evaluation of actions related to use of triclopyr that may alter the PCEs of the CRLF's
critical habitat form the basis of the critical habitat impact analysis. According to U.S.
FWS (2006), activities that may affect critical habitat and therefore result in adverse
effects to the CRLF include, but are not limited to the following:
(1) Significant alteration of water 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) 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 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.
(4) 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.
(5) Elimination of upland foraging and/or aestivating habitat or dispersal habitat.
(6) Introduction, spread, or augmentation of non-native aquatic species in stream
segments or ponds used by the CRLF.
(7) Alteration or elimination of the CRLF's food sources or prey base (also
evaluated as indirect effects to the CRLF).
As previously noted in Section 2.1, the Agency believes that the analysis of direct and
indirect effects to listed species provides the basis for an analysis of potential effects on
the designated critical habitat. Because triclopyr is expected to directly impact living
organisms within the action area, critical habitat analysis for triclopyr 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.
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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 triclopyr is likely to encompass considerable portions of the
United States based on the large array of 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. The Agency's approach to defining the action area under the provisions of
the Overview Document (U.S. EPA 2004) considers the results of the risk assessment
process to establish boundaries for that action area with the understanding that exposures
below the Agency's defined Levels of Concern (LOCs) constitute a no-effect threshold.
For the purposes of this assessment, attention will be focused on the footprint of the
action (i.e., the area where pesticide application occurs), plus all areas where offsite
transport (i.e., spray drift, downstream dilution, etc.) may result in potential exposure
within the state of California that exceeds the Agency's LOCs.
Deriving the geographical extent of this portion of the action area is based on
consideration of the types of effects that triclopyr may be expected to have on the
environment, the exposure levels to triclopyr that are associated with those effects, and
the best available information concerning the use of triclopyr and its fate and transport
within the state of California. Specific measures of ecological effect that define the
action area include any direct and indirect toxic effect and any potential modification of
its critical habitat, including reduction in survival, growth, and fecundity as well as the
full suite of sublethal effects available in the effects literature. Therefore, the action area
extends to a point where environmental exposures are below any measured lethal or
sublethal effect threshold for any biological entity at the whole organism, organ, tissue,
and cellular level of organization. In situations where it is not possible to determine the
threshold for an observed effect, the action area is not spatially limited and is assumed to
be the entire state of California.
The definition of action area requires a stepwise approach that begins with an
understanding of the federal action. The federal action is defined by the currently labeled
uses for triclopyr. 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. The only food use crop for triclopyr is on rice. The remainder of
triclopyr uses, relevant to the CRLF, includes agricultural, non-agricultural, and non-food
uses which can be found in Table 2-2.
Following a determination of the assessed uses, an evaluation of the potential "footprint"
of triclopyr use patterns (i.e., the area where pesticide application occurs) is determined.
This "footprint" represents the initial area of concern, based on an analysis of available
land cover data for the state of California. The initial area of concern is defined as all
land cover types and the stream reaches within the land cover areas that represent the
41
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labeled uses described above. A map representing all the land cover types that make up
the initial area of concern for triclopyr is presented in Figure 2-4.
The uses represented by triclopyr are depicted by the following land cover types:
cultivated crops (21%), developed/high intensity (16%), developed/low intensity (2.6%),
developed/open space (6.5%), forest (16%), orchards/vineyards (6.5%), pasture/hay
(6.5%), wetlands (6.5%), and open water (8%). Cultivated crops are areas used for the
production of annual crops, such as corn, soybeans, vegetables, and cotton. This class
also includes all land being actively tilled. Developed/high intensity areas are where
people reside, or work in high numbers. The impervious surfaces account for 80-100%
of the total cover. Developed/low intensity areas include a mixture of constructed
materials and vegetation with impervious surfaces accounting for 20-40% of total cover.
Developed/open space includes areas with a mixture of constructed materials, but mainly
vegetation in the form of lawn grasses. Impervious surfaces account for lass than 20% of
total cover. Forest represents deciduous, evergreen, and mixed vegetation. These areas
are dominated by trees that are generally greater than 5 meters tall, and greater than 20%
of total vegetation cover. Orchards/vineyards represent areas used for the cultivation of
crops, such as fruits and nuts, which grow on vines or trees. Lastly, pasture/hay
represents areas of grasses, legumes, or grass-legume mixtures planted for livestock
grazing or the production of seed or hay crops. Typically, pasture/hay vegetation
accounts for greater than 20% of total vegetation. More information regarding which
specific uses are represented for each land cover types can be found in Appendix D.
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Potential Triclopyr Use - Initial Area of Concern
Legend
CA counties
I:;:;:; I decid and conif
I developed open
I developed low
I developed meet
developed high
water
| wetland woody
wetland emergent
, Pasture
Orchard vineyard use
Cultivated
i Kilometers
0 2040 80 120 160
Compiled from California County boundaries (ESRI, 2002),
US DA, Gap Analysis Program Orchard)'Vineyard Landcover (GAP)
National LandCoverOafabase (NLCD) (MRLC, 2001)
Map created by US Environmental Protection Agency, Office
of Pesticides Programs, Environmental Fate and Effects Cwision.
Projection: Albers Equal Area Conic USGS, North American
Datum Of 1983 (NAD 1985.
8/2009
Figure 2-4. Initial area of concern, or "footprint" of potential use, for Triclopyr
43
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Once the initial area of concern is defined, the next step is to define the potential
boundaries of the action area by determining the extent of offsite transport via spray drift
and runoff where exposure of one or more taxonomic groups to the pesticide exceeds the
listed species LOCs.
As previously discussed, the action area is defined by the most sensitive measure of
direct and indirect ecological toxic effects including reduction in survival, growth,
reproduction, and the entire suite of sublethal effects from valid, peer-reviewed studies.
However, due to the widespread use of triclopyr throughout the state of California, the
initial area of concern only includes agricultural uses and not the residential or other non-
agricultural uses in California. As a result the initial area of concern may be an
underestimation of the actual usage of triclopyr in California, therefore, in order to
incorporate all of the uses of Triclopyr within California, the initial area of concern is the
entire state of California.
The AgDRIFT model (Version 2.01) is used to define how far from the initial area of
concern an effect to a given species may be expected via spray drift. The spray drift
analysis for triclopyr using the most sensitive endpoint (Sunflower - vegetative vigor)
suggests that a maximum spray drift distance of at least 1000 feet was derived. Further
detail on the spray drift analysis is provided in Section 5.2.5.1.
In addition to the buffered area from the spray drift analysis, the final action area also
considers the downstream extent of triclopyr that exceeds the LOG (discussed in Section
5.2.5.2).
An evaluation of usage information was conducted to determine the area where use of
triclopyr 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. These data suggest that triclopyr has historically been used on a wide variety
of agricultural and non-agricultural uses in all 58 counties in California. As a result, since
triclopyr has both agricultural and non-agricultural uses, it is applied in 58 of 58 counties,
and has a buffer zone greater than 1,000 feet, with such widespread use the action area is
the entire state of California.
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."3 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., waterbodies,
riparian vegetation, and upland and dispersal habitats), the migration pathways of
triclopyr (e.g., runoff, spray drift, etc.), and the routes by which ecological receptors are
exposed to triclopyr (e.g., direct contact, etc.).
3 U.S. EPA (1992). Framework for Ecological Risk Assessment. EPA/630/R-92/001.
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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
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. It should be noted
that assessment endpoints are limited to direct and indirect effects associated with
survival, growth, and fecundity, and do not include the full suite of sublethal effects used
to define the action area. According to the Overview Document (U.S. EPA 2004), the
Agency relies on acute and chronic effects endpoints that are either direct measures of
impairment of survival, growth, or fecundity or endpoints for which there is a
scientifically robust, peer reviewed relationship that can quantify the impact of the
measured effect endpoint on the assessment endpoints of survival, growth, and fecundity.
A 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 4.0 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 triclopyr is provided in Table 2-4.
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Table 2-4 Assessment Endpoints and Measures of Ecological Effects
Assessment Endpoint
Measures of Ecological Effects4
Aquatic-Phase CRLF
(Eggs, larvae, juveniles, and adults)3
Direct Effects
1. Survival, growth, and reproduction of
CRLF
la. Bluegill sunfish (Lepomis macrochirus) LCso
Ib. Rainbow 1m\A(Oncorhynchus mykiss) NOAEC
Indirect Effects and Critical Habitat Effects
1. Survival, growth, and reproduction of
CRLF individuals via indirect effects on
aquatic prey food supply (i.e., fish,
freshwater invertebrates, non-vascular plants)
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)
4. Survival, growth, and reproduction of
CRLF individuals via effects to riparian
vegetation
2a. Bluegill sunfish (L. macrochims) LC50
2b. Rainbow Trout (O. mykiss) NOAEC
2c. Water Flea (Daphnia magna) EC50
2d. Water Flea (D. magna) NOAEC
2e. Freshwater diatom (Navicula pelliculosa) ECso
3a. Duckweed (Lemna gibba) EC50
3b. Freshwater diatom (N. pelliculosa) ECso
4a. Onion (Allium cepa) EC2s (seedling emergence)
4b. Alfalfa (Medicago sativa) EC2s (seedling emergence)
4c. Onion (A. cepa) EC25 (vegetative vigor)
4d. Sunflower (Helianthus annus) EC2s (vegetative vigor)
Terrestrial-Phase CRLF
(Juveniles and adults)b
Direct Effects
5. Survival, growth, and reproduction of
CRLF individuals via direct effects on
terrestrial phase adults and juveniles
5a. Northern Bobwhite Quail (Colinus virginianus) LCso
5b. Northern Bobwhite Quail (C. virginianus) LD50
5c. Mallard Duck (Anas platyrhynchos) NOAEC
Indirect Effects and Critical Habitat Effects
6. Survival, growth, and reproduction of
CRLF individuals via effects on terrestrial
prey (i.e., terrestrial invertebrates, small
mammals , and frogs)
7. Survival, growth, and reproduction of
CRLF individuals via indirect effects on
habitat (i.e., riparian and upland vegetation)
6a. Northern Bobwhite Quail (C. virginianus) LC50
6b. Northern Bobwhite Quail (C. virginianus) LD50
6c. Laboratory Rat (Rattus norvegicus) LD50
6d. Honey Bee (Apis mellifera) LD50
6e. Mallard Duck (A. platyrhynchos) NOAEC
6f. Laboratory Rat (R. norvegicus) NOAEL
7a. Onion (A. cepa) EC25 (seedling emergence)
7b. Alfalfa (M. sativa) EC25 (seedling emergence)
7c. Onion (A. cepa) EC25 (vegetative vigor)
7d. Sunflower (H. annus) EC25 (vegetative vigor)
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.
4 Citations for all registrant-submitted and open literature toxicity data reviewed for this assessment are
included in Appendix A.
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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 triclopyr that may alter the PCEs of the CRLF's critical habitat. PCEs for
the CRLF were previously described in Section 2.6. Actions that may modify critical
habitat are those that alter the PCEs and jeopardize the continued existence of the CRLF.
Therefore, these actions are identified as assessment endpoints. It should be noted that
evaluation of PCEs as assessment endpoints is limited to those of a biological nature (i.e.,
the biological resource requirements for the listed species associated with the critical
habitat) and those for which triclopyr effects data are available. Adverse modification to
the critical habitat of the CRLF includes, but is not limited to, those listed in Section 2.6.
Measures of such possible effects by labeled use of triclopyr on critical habitat of the
CRLF are described in Table 2-5. 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 U.S. FWS (2006).
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Table 2-5 Summary of Assessment Endpoints and Measures of Ecological Effect for
Primary Constituent Elements of Designated Critical Habitat3
Assessment Endpoint
Measures of Ecological Effect
Aquatic-Phase CRLFPCEs
(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.
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.
Alteration of other chemical characteristics necessary
for normal growth and viability of CRLFs and their
food source.
Reduction and/or modification of aquatic-based food
sources for pre-metamorphs (e.g., algae)
la. Duckweed (Lemna gibba) EC50
Ib. Freshwater diatom (Navicula pelliculosa) ECso
Ic. Onion (Allium cepa) EC2s (seedling emergence)
Id. Alfalfa (Medicago sativa) EC2s (seedling emergence)
le. Onion (A. cepa) EC25 (vegetative vigor)
If. Sunflower (Helianthus annus) EC25 (vegetative vigor)
2a. Duckweed (Lemna gibba) EC50
2b. Freshwater diatom (Navicula pelliculosa) EC50
2c. Onion (Allium cepa) EC25 (seedling emergence)
2d. Alfalfa (Medicago sativa) EC25 (seedling emergence)
2e. Onion (A. cepa) EC25 (vegetative vigor)
2f. Sunflower (Helianthus annus) EC25 (vegetative vigor)
3a. Bluegill sunfish (L. macmchirus) LC50
3b. Rainbow Trout (O. mykiss) NOAEC
3c. Water Flea (Daphnia magna) EC50
3d. Water Flea (D. magna) NOAEC
4a. Freshwater diatom (Navicula pelliculosa) EC50
4b. Duckweed (Lemna gibba) EC50
Terrestrial-Phase CRLFPCEs
(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
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.
5a. Onion (A. cepa) EC25 (seedling emergence)
5b. Alfalfa (M. sativa) EC25 (seedling emergence)
5c. Onion (A. cepa) EC25 (vegetative vigor)
5d. Sunflower (H. annus) EC25 (vegetative vigor)
5e. Northern Bobwhite Quail (C. virginianus) LC50
5f. Northern Bobwhite Quail (C. virginianus) LD50
5g. Laboratory Rat (Rattus norvegicus) LD50
5h. Honey Bee (Apis mellifera) LD50
5i. Mallard Duck (A. platyrhynchos) NOAEC
5j. Laboratory Rat (R. worveg/cMs) NOAEL
1 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.
48
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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 triclopyr to the environment.
The following risk hypotheses are presumed for this endangered species assessment:
The labeled use of triclopyr within the action area may:
• Directly affect the CRLF by causing mortality or by adversely affecting growth or
fecundity;
• Indirectly affect the CRLF by reducing or changing the composition of food
supply;
• Indirectly affect the CRLF 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;
• Indirectly affect the CRLF 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;
• 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);
• Modify the designated critical habitat of the CRLF by reducing the food supply
required for normal growth and viability of juvenile and adult CRLFs;
• 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;
• 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; or
• 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 triclopyr release mechanisms, biological receptor types, and effects
endpoints of potential concern. The conceptual models for terrestrial and aquatic
exposures are shown in Figure 2-5 and Figure 2-6, respectively, which include the
49
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conceptual models for the aquatic and terrestrial PCE components of critical habitat.
Exposure routes shown in dashed lines are not quantitatively considered because the
contribution of those potential exposure routes to potential risks to the CRLF and
modification to designated critical habitat is expected to be negligible.
Stressor
Source
Exposure
Media
Triclopyr applied to use site
+
1
Y . In
I Runoff \
Long range
atmospheric
transport
Terrestrial/riparian plants
grasses/forbs, fruit, seeds
(trees, shrubs)
• Wet/dry deposition
Ingestion
. Ingestion
Ingestion
Receptors
1
I
Birds/terrestrial-phase
amphibians/
reptiles/mammals
Attribute
Change
1
Individual organisms
Reduced survival
Reduced growth
Reduced reproduction
j_ Ingestion
Mammals/
Birds
Food chain
Reduction in prey
Modification of PCEs
related to prey
availability
Habitat integrity
Reduction in primary productivity
Reduced cover
Community change
Modification of PCEs related to habitat
Figure 2-5 Conceptual Model for Pesticide Effects on Terrestrial Phase of the
CRLF
50
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Stressor
Source
Exposure
Media
Triclopyr applied
1...
Spray drift | | Runoff | 1 SoM
1 1
Surface water/
to use site
t
ong range
mospheric
ransport
I
Uptake/gills
or integument
Receptors
Uptake/gills
or integument
Aquatic Animals
Invertebrates
Vertebrates
Uptake/cell,
roots, leaves
Aquatic Plants
Non-vascular
Vascular
Fish/aquatic-phase
amphibians
"Piscivorous
mammals and birds
Attribute
Change
1
Individual organisms
Reduced survival
Reduced growth
Reduced reproduction
Food chain
Reduction in algae
Reduction in prey
Modification of PCEs
related to prey
availability
Habitat integrity
Reduction in primary productivity
Reduced cover
Community change
Modification of PCEs related to
habitat
** Route of exposure includes only ingestion of aquatic fish and invertebrates
Figure 2-6 Conceptual Model for Pesticide Effects on Aquatic Phase of the CRLF
2.10 Analysis Plan
In order to address the risk hypotheses, 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 triclopyr 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 triclopyr is estimated using the
probit dose-response slope and either the level of concern (discussed below) or actual
calculated risk quotient value.
51
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2.10.1 Measures to Evaluate the Risk Hypothesis and Conceptual Model
2.10.1.1 Measures of Exposure
The environmental fate properties of triclopyr along with available monitoring data
indicate that runoff and spray drift are the principle potential transport mechanisms of
triclopyr to the aquatic and terrestrial habitats of the CRLF. In this assessment, transport
of triclopyr through runoff and spray drift is considered in deriving quantitative estimates
of triclopyr exposure to CRLF, its prey and its habitats. Triclopyr is not expected to
volatilize once applied to soil due to its Henry's Law Constant (9.66 x 10"7 atm m3 mol"1)
and its vapor pressure (1.26 x 10"6 atm3/mol). As a result, atmospheric transport is not
expected to be a likely route of exposure for triclopyr. See Section 3.2.4 for an
explanation of existing monitoring data.
Measures of exposure are based on aquatic and terrestrial models that predict estimated
environmental concentrations (EECs) of triclopyr using maximum labeled application
rate and method of application. The models used to predict aquatic EECs are the
Pesticide Root Zone Model coupled with the Exposure Analysis Model System
(PRZM/EXAMS). The model used to predict terrestrial EECs on food items is T-REX.
The model used to derive EECs relevant to terrestrial and wetland plants is TerrPlant.
These models are parameterized using relevant reviewed registrant-submitted
environmental fate data.
PRZM (v3.12.2, May 2005) and EXAMS (v2.98.4.6, April 2005) are screening
simulation models coupled with the input shell pe5.pl (Aug 2007) to generate daily
exposures and l-in-10 year EECs of triclopyr that may occur in surface water bodies
adjacent to application sites receiving triclopyr through runoff and spray drift. PRZM
simulates pesticide application, movement and transformation on an agricultural field and
the resultant pesticide loadings to a receiving water body via runoff, erosion and spray
drift. EXAMS simulates the fate of the pesticide and resulting concentrations in the
water body. The standard scenario used for ecological pesticide assessments assumes
application to a 10-hectare agricultural field that drains into an adjacent 1-hectare water
body, 2-meters deep (20,000 m3 volume) with no outlet. PRZM/EXAMS was used to
estimate screening-level exposure of aquatic organisms to triclopyr. The measure of
exposure for aquatic species is the l-in-10 year return peak or rolling mean concentration.
The l-in-10 year peak is used for estimating acute exposures of direct effects to the
CRLF, as well as indirect effects to the CRLF through effects to potential prey items,
including: algae, aquatic invertebrates, fish and frogs. The l-in-10-year 60-day mean is
used for assessing chronic exposure to the CRLF and fish and frogs serving as prey
items; the l-in-10-year 21-day mean is used for assessing chronic exposure for aquatic
invertebrates, which are also potential prey items.
The EFED Tier 1 Rice Model (vl.O) is a screening simulation model which generates a
maximum exposure value for rice paddies based upon the maximum rate of application to
the surface of the paddy water (10 cm), the volume of water in the paddy, and an
assumption of instantaneous partitioning into 1 cm sediment through sorption to the soil
52
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calculated using the average laboratory Kd value. The Tier 1 Rice Model does not take
into consideration movement or transformation on or in the agricultural rice paddy, or the
resultant pesticide loadings to a receiving water body via paddy release water, erosion
and spray drift. This model was used to estimate conservative screening-level exposure
of aquatic organisms to triclopyr. In the Tier 1 Rice Model, the measure of acute
exposure for triclopyr is considered to be the concentration on the day of application.
Exposure estimates for the terrestrial-phase CRLF and terrestrial invertebrates and
mammals (serving as potential prey) assumed to be in the target area or in an area
exposed to spray drift from foliar applications and granules from granular applications
are derived using the T-REX model (version 1.3.1, 12/07/2006). This model incorporates
the Kenega nomograph, as modified by Fletcher et al. (1994), which is based on a large
set of actual field residue data. The upper limit values from the nomograph represented
the 95th percentile of residue values from actual field measurements (Hoerger and
Kenega 1972). For modeling purposes, direct exposures of the CRLF to triclopyr
through contaminated food are estimated using the EECs for the small bird (20 g) which
consumes small insects. Dietary-based and dose-based exposures of potential prey (small
mammals) are assessed using the small mammal (15g) which consumes short grass. The
small bird (20g) consuming small insects and the small mammal (15g) consuming short
grass are used because these categories represent the largest RQs of the size and dietary
categories in T-REX that are appropriate surrogates for the CRLF and one of its prey
items. Estimated exposures of terrestrial insects to triclopyr are bound by using the
dietary based EECs for small insects and large insects.
Birds are currently used as surrogates for terrestrial-phase CRLF. However, amphibians
are poikilotherms (body temperature varies with environmental temperature) while birds
are homeotherms (temperature is regulated, constant, and largely independent of
environmental temperatures). Therefore, amphibians tend to have much lower metabolic
rates and lower caloric intake requirements than birds or mammals. As a consequence,
birds are likely to consume more food than amphibians on a daily dietary intake basis,
assuming similar caloric content of the food items. Therefore, the use of avian food
intake allometric equation as a surrogate to amphibians is likely to result in an over-
estimation of exposure and risk for reptiles and terrestrial-phase amphibians. Therefore,
T-REX (version 1.3.1) has been refined to the T-HERPS model (v. 1.0), which allows for
an estimation of food intake for poikilotherms using the same basic procedure as T-REX
to estimate avian food intake.
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.
Spray drift model AgDRIFT is used to assess exposures of terrestrial phase CRLF and its
prey to triclopyr deposited on terrestrial habitats by spray drift. In addition to the
buffered area from the spray drift analysis, the downstream extent of triclopyr that
exceeds the LOG for the effects determination is also considered.
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2.10.1.2 Measures of Effect
Data identified in Section 2.8 are used as measures of effect for direct and indirect effects
to the CRLF. Data were obtained from registrant submitted studies or from literature
studies identified by ECOTOX. The ECOTOXicology database (ECOTOX) was searched
in order to provide more ecological effects data and in an attempt to bridge existing data
gaps. ECOTOX is a source for locating single chemical toxicity data for aquatic life,
terrestrial plants, and wildlife. ECOTOX was created and is maintained by the U.S. EPA,
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 triclopyr to birds is similar to or less than the toxicity to the
terrestrial-phase CRLF. The same assumption is made for fish and aquatic-phase CRLF.
Algae, aquatic invertebrates, fish, and 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 LCso 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 ECso for aquatic plants).
It is important to note that the measures of effect for direct and indirect effects to the
CRLF and its designated critical habitat are associated with impacts to survival, growth,
and fecundity, and do not include the full suite of sublethal effects used to define the
action area. According the Overview Document (USEPA 2004), the Agency relies on
effects endpoints that are either direct measures of impairment of survival, growth, or
fecundity or endpoints for which there is a scientifically robust, peer reviewed
relationship that can quantify the impact of the measured effect endpoint on the
assessment endpoints of survival, growth, and fecundity.
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2.10.1.3 Integration of Exposure and Effects
Risk characterization is the integration of exposure and ecological effects characterization
to determine the potential ecological risk from agricultural and non-agricultural uses of
triclopyr, 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 triclopyr 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) (U.S. EPA
2004) (see Appendix C).
For this endangered species assessment, listed species LOCs are used for comparing RQ
values for acute and chronic exposures of triclopyr directly to the CRLF. If estimated
exposures directly to the CRLF of triclopyr resulting from a particular use are sufficient
to exceed the listed species LOG, 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 triclopyr resulting from a particular
use are sufficient to exceed the listed species LOG, then the effects determination for that
use is a "may affect." If the RQ being considered also exceeds the non-listed species
acute risk LOG, then the effects determination is a LAA. If the acute RQ is between the
listed species LOG and the non-listed acute risk species LOG, 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 LOG 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 LOG for plants, the
effects determination is "may affect". Further information on LOCs is provided in
Appendix C.
2.10.1.4 Data Gaps
No acceptable toxicity studies have been submitted to the Agency, nor were any
acceptable studies found in the open literature for the chronic effects of the degradate
TCP on avian, aquatic-phase amphibian species, or terrestrial-phase amphibian species.
There are three multi-ai products, in which triclopyr is mixed with another chemical;
TAILSPIN (EPA Reg. No. 34704-958) triclopyr (16.1% ai) with Fluroxypyr (5.6 % ai),
GF-1249 (EPA Reg. No. 62719-528) triclopyr (22.2% ai) with Picloram (potassium salt,
4.07 % ai), and RICEPYR (EPA Reg. No. 71085-29) triclopyr (3.8% ai) with Propanil
(36.5% ai), Appendix B. In the case of triclopyr, only one product (EPA Reg. No.
71085-29) has a definitive LD50 value with an associated 95% CI, and the toxicity can be
attributed to propanil (the other active ingredient in the formulated product). The other
two products (EPA Reg. No. 34704-958 and 62719-528) no definitive LD50 values are
available with an associated 95% CI. There is an LD50 value of 1847 mg/kg (410 mg/kg
55
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adjusted for active ingredient triclopyr) available for EPA Reg. No. 62719-528, however
it is not considered to be a definitive number by HED, as no confidence intervals are
available for the LD50 (see Appendix B). Therefore, no definitive statement of toxicity
can be made for the other two products regarding if they pose any toxic risk greater or
less than triclopyr alone. The best available information, and definitive endpoints from
one of the three multi-ai products, suggests that the assessment based on triclopyr alone is
adequate to understand risk to non-target receptors.
56
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3.0 Exposure Assessment
Triclopyr is formulated as an emulsifiable concentrate, liquid, and granular. Application
equipment and methods include ground application, aerial application, injection, hand
held sprayers, and spreaders for granular applications. Risks from ground boom and
aerial applications are expected to result in the highest off-target levels of triclopyr 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 applications coincident with
sprayers and spreaders and thus have a higher potential for off-target movement via spray
drift.
3.1 Label Application Rates and Intervals
Triclopyr labels may be categorized into two types: labels for manufacturing uses
(including technical grade triclopyr and its formulated products) and end-use products.
While technical products, which contain triclopyr of high purity, are not used directly in
the environment, they are used to make formulated products or used for research. The
formulated product labels legally limit triclopyr's potential use to only those sites that are
specified on the labels.
Mitigation from the 1998 RED stated changes to the labels to reflect the following:
• 2 Ibs ae/A per year on pasture and rangeland and all sites where cattle can be
grazed.
• 6 Ibs ae/A per year for forestry applications.
• 8 Ibs ae/A per year for all other use sites of triclopyr BEE
• 9 Ibs ae/A per year for all other use sites of triclopyr TEA
However, the label information provided by BEAD, as described in the Use
Characterization (Section 2.4.3), represents the values used for this assessment. As a
result, the maximum application rates used in the modeling may be more conservative
than that reflected by the maximum application rates represented in the mitigation from
the 1998 RED.
Currently registered agricultural and non-agricultural uses of triclopyr within California
include rice, waterways, pasture, wetlands, orchard stump treatments, ornamentals,
forests, rights-of-way, commercial and industrial outdoor premises and lawns, and
residential outdoor premises and lawns. Mitigation from the 1998 RED stated changes to
the labels, and recommended a maximum application rate of 9 Ibs ae/A down from the 20
Ibs ae/A. However, these have not been implemented on the labels, and therefore, the
maximum application rate on the current registered labels is used. Currently registered
agricultural and non-agricultural uses of triclopyr within California are listed in Table
2-2. The uses being assessed are summarized in Table 3-1 below.
When determining how to model the use of triclopyr on rice, the crop profile provided by
NSF Center for Integrated Pest Management (October 1998) was referred to. It helped
determine how rice is treated, cultivated, and the conditions that exist during the
production of rice. Rice production in California begins with land preparation (leveling
57
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for proper stand establishment, weed control and drainage), and is followed by fertilizer
and insect control application. Once the land has been properly prepared, it is flooded
with water and the seed is applied by airplane into the water. The rice is grown primarily
in a continuously flooded, flow-through system. Weed control begins within days of
planting and continues until the canopy closes over. Occasional "clean-up" operations are
required for weeds after the canopy closes. Per NSF, triclopyr is applied between the
third to fifty-fifth days for the early variety, and the third to sixty-fifth for the late variety.
Table 3-1 Triclopyr Uses, Scenarios, and Application Information for the CRLF
risk assessment1
Scenario
CA forestry
RLF
CA forestry
RLF
CA forestry
RLF
CA forestry
RLF
CA forestry
RLF
CA fruit STD
CA
impervious
RLF
CA
impervious
RLF
CA
impervious
RLF
CA
impervious
RLF and CA
residential
RLF
CA
impervious
RLF and CA
residential
RLF
CA Nursery
CA Nursery
CA rangeland
hay RLF
CA rangeland
hay RLF
Uses Represented by Scenario
DOUGLAS-FIR (FOREST/SHELTERBELT)
CONIFER RELEASE
CHRISTMAS TREE PLANTATIONS, CONIFER
RELEASE, FOREST TREES (ALL OR
UNSPECIFIED), FOREST TREE
MANAGEMENT/FOREST PEST
MANAGEMENT
CHRISTMAS TREE PLANTATIONS, FOREST
TREES (ALL OR UNSPECIFIED), CONIFER
RELEASE
FOREST TREE MANAGEMENT/FOREST PEST
MANAGEMENT, FOREST TREES (ALL OR
UNSPECIFIED)
ORCHARDS (non-food stump treatment)
AIRPORTS/LANDING FIELDS,
COMMERCIAL/INSTITUTIONAL/INDUSTRIAL
PREMISES/EQUIPMENT (OUTDOOR)
PAVED AREAS (PRIVATE
ROADS/SIDEWALKS), DRAINAGE SYSTEMS,
INDUSTRIAL AREAS (OUTDOOR),
NONAGRICULTURAL RIGHTS-OF-
WAY/FENCEROWS/HEDGEROWS
COMMERCIAL STORAGES/WAREHOUSES
PREMISES, PAVED AREAS (PRIVATE
ROADS/SIDEWALKS), DRAINAGE SYSTEMS,
INDUSTRIAL AREAS (OUTDOOR)
AGRICULTURAL RIGHTS-OF-
WAY/FENCEROWS/HEDGEROWS
NONAGRICULTURAL RIGHTS-OF-
WAY/FENCEROWS/HEDGEROWS
ORNAMENTAL HERBACEOUS PLANTS,
ORNAMENTAL NONFLOWERING PLANTS
ORNAMENTAL AND/OR SHADE TREES,
ORNAMENTAL WOODY SHRUBS AND VINES
AGRICULTURAL/FARM
STRUCTURES/BUILDINGS AND EQUIPMENT
AGRICULTURAL/FARM PREMISES
Application
Rate
(Ib ae/A)
1.5
3.2
6
6
6
9
12
12
20
4.5
9
20
0.53
6
1.5
2
Number of
Applications
17
17
17
17
17
17
17
1
17
1
17
17
17
17
17
17
Application
Interval
21
21
21
21
21
21
21
0
21
0
21
21
21
21
21
21
Application
Method
Sprayer
Aircraft
Ground Spray
Injection
Aircraft
Ground
Ground
Aircraft
Ground
Aircraft
Ground
Ground
Package
applicator
Aircraft
Ground
Aircraft
Aircraft
58
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Scenario
CA rangeland
hay RLF
CA rangeland
hay RLF
CA rangeland
hay RLF
CA rangeland
hay RLF
CA Rangeland
Hay V2 RLF
CA residential
RLF
CA residential
RLF
CA residential
RLF
CA turf RLF
CA turf RLF
CA turf RLF
CA turf RLF
CA turf RLF
C A turf RLF
Rice Model
NA
NA
NA
NA
Uses Represented by Scenario
AGRICULTURAL FALLOW/IDLELAND,
NONAGRICULTURAL UNCULTIVATED
AREAS/SOILS
AGRICULTURAL FALLOW/IDLELAND
AGRICULTURAL/FARM PREMISES
AGRICULTURAL/FARM
STRUCTURES/BUILDINGS AND EQUIPMENT,
AGRICULTURAL UNCULTIVATED AREAS,
NONAGRICULTURAL UNCULTIVATED
AREAS/SOILS
PASTURES, RANGELAND
RECREATION AREA LAWNS, RESIDENTIAL
LAWNS
RESIDENTIAL LAWNS
HOUSEHOLD/DOMESTIC DWELLINGS
OUTDOOR PREMISES, RECREATION AREA
LAWNS
ORNAMENTAL LAWNS AND TURF
COMMERCIAL/INDUSTRIAL LAWNS,
ORNAMENTAL LAWNS AND TURF
ORNAMENTAL SOD FARM (TURF)
COMMERCIAL/INDUSTRIAL LAWNS
ORNAMENTAL SOD FARM (TURF)
GOLF COURSE TURF
RICE
AQUATIC AREAS/WATER,
INTERMITTENTLY FLOODED
AREAS/WATER, LAKES/PONDS/RESERVOIRS
(WITH HUMAN OR WILDLIFE USE)
AQUATIC AREAS/WATER,
INTERMITTENTLY FLOODED AREAS/WATER
SWAMPS/MARSHES/WETLANDS/STAGNANT
WATER
LAKES/PONDS/RESERVOIRS (WITH HUMAN
OR WILDLIFE USE),
SWAMPS/MARSHES/WETLANDS/STAGNANT
WATER
Application
Rate
(lb ae/A)
12
12
20
20
4.5
9
1.5
9
12
0.76
1.5
1.5
9
9
12
0.38
NA
NA
NA
NA
Number of
Applications
i
i
17
17
1
17
2
2
17
1
17
2
2
4
17
2
NA
NA
NA
NA
Application
Interval
0
0
21
21
0
21
28
21
21
0
21
21
21
21
21
21
NA
NA
NA
NA
Application
Method
Aircraft
Ground
Ground
Ground
Aircraft
Ground
Spreader
Ground
Ground
Spreader
Spreader
Spreader
Ground
Ground
Ground
Aircraft
Ground
Aircraft
Ground
Aircraft
Ground
1 Uses assessed based on memorandum from SRRD dated April 14, 2009.
NA: Not applicable. These uses have a maximum allowable concentration of 2.5 ppm. Therefore, application rates
are dependant on volume of the body of water
3.2 Aquatic Exposure Assessment
3.2.1 Modeling Approach
Aquatic exposures are quantitatively estimated for all of assessed uses using scenarios
that represent high exposure sites for triclopyr use. Each of these sites represents a 10
hectare field that drains into a 1-hectare pond that is 2 meters deep and has no outlet.
Exposure estimates generated using the standard pond are intended to represent a wide
variety of vulnerable water bodies that occur at the top of watersheds including prairie
59
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pot holes, playa lakes, wetlands, vernal pools, man-made and natural ponds, and
intermittent and first-order streams. As a group, there are factors that make these water
bodies more or less vulnerable than the standard surrogate pond. Static water bodies that
have larger ratios of drainage area to water body volume would be expected to have
higher peak EECs than the standard pond. These water bodies will be either shallower or
have large drainage areas (or both). Shallow water bodies tend to have limited additional
storage capacity, and thus, tend to overflow and carry pesticide in the discharge whereas
the standard pond has no discharge. As watershed size increases beyond 10 hectares, at
some point, it becomes unlikely that the entire watershed is planted to a single crop,
which is all treated with the pesticide. Headwater streams can also have peak
concentrations higher than the standard pond, but they tend to persist for only short
periods of time and are then carried downstream.
Crop-specific management practices for all of the assessed uses of triclopyr were used for
modeling, including application rates, number of applications per year, application
intervals, and the first application date for each crop. The date of first application was
developed based on several sources of information including data provided by BEAD, a
summary of individual applications from the CDPR PUR data, and Crop Profiles
maintained by the USDA. More detail on the crop profiles may be found at:
http://www.ipmcenters.org/CropProfiles/
3.2.2 Model Inputs
Triclopyr is an herbicide applied to a wide variety of agricultural and non-agricultural use
sites. Triclopyr's environmental fate data used for generating model parameters is listed
in Table 2-2. The input parameters for PRZM and EXAMS are in Table 3-2.
Table 3-2 Summary of PRZM/EZAMS Environmental Fate Data Used for Aquatic
Exposure Inputs for Triclopyr Endangered Species Assessment for the CRLFl
Fate Property
Value (unit)
MRID (or source)
Molecular Weight
Henry's Law constant
Vapor Pressure
Solubility in Water
Photolysis in Water
Aerobic Soil Metabolism Half-lives
Hydrolysis
Aerobic Aquatic Metabolism (water
column)
256.47 g/mol
9.66 x 10"7 atm m3 mol"1
1.26xl(Ttorr
http ://toxnet.nlm. nih. gov
Calculated
http ://toxnet.nlm. nih. gov
http ://toxnet.nlm. nih. gov
440 mg/L
0.375 days (Assuming 24 hours of MRID 41732201
daylight) MRID 42411804
0.75 days (Adjusted for 12 hours of
daylight)
MRID 40346304 (per Input
Parameter Guidance)
0 (Stable) MRID 41879601
28.39 days
426 days
MRID 40479101 (per Input
Parameter Guidance)
60
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Fate Property
Value (unit)
MRID (or source)
Anaerobic Aquatic Metabolism
(benthic)
Koc
Application rate and frequency
Application intervals
Chemical Application Method (CAM)
Application Efficiency
Spray Drift Fraction
0 (stable)
59.25 (average)
Various (see Table 3.3)
Various (see Table 3.3)
1-ground (preplant), aerial (bare)
2-ground (foliar), aerial (foliar)
5- granular (at plant)
8- soil injection
0.99 (ground)
0.95 (aerial)
0.01 (ground)
0.05 (aerial)
MRID 151967
MRID 40749801 (per Input
Parameter Guidance)
Per Label Instructions
Per Label Instructions
Input Parameter Guidance
Input Parameter Guidance
Input Parameter Guidance
1 - Inputs determined in accordance with EFED "Guidance for Chemistry and Management Practice Input
Parameters for Use in Modeling the Environmental Fate and Transport of Pesticides" dated February 28,
2002
For the direct water applications and for rice, the model used to predict aquatic EECs is
the EFED Tier 1 Rice Model (vl.O, May 8, 2007). Using the Tier 1 Rice Model, aquatic
exposures are quantitatively estimated for rice use with conservative, maximum values
that represent high exposure sites for triclopyr use. Each of these sites represents a rice
paddy (or water body) holding a 10 cm water depth. When a pesticide is applied to the
rice paddy (or water body), the model assumes that it will instantaneously partition
between a water phase and a sediment phase based on the partition coefficients of the
chemical. The formula of the Tier I Rice Model vl.O is as follows:
m
m
0.00105 + 0.00013^,
d
and, if appropriate:
Kd = 0.01K,
oc
where:
Cw = water concentration [|ig/L]
mai' = mass applied per unit area [kg/ha]
Kd = water-sediment partitioning coefficient [L/kg]
Koc = organic carbon partitioning coefficient [L/kg]
3.2.3
Results
The aquatic EECs for the various scenarios, models used (PRZM/EXAMS, and the Tier I
Rice Model), and application practices are listed in Table 3-3. The maximum non-
agricultural and agricultural application rate/interval/applications per year were
61
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calculated, along with the median use application rate/interval/applications per year, and
minimum use application rate/interval/applications per year. See Appendix J and K for a
summary of the outputs for the Rice Model and PRZM/EXAMS, respectively. Peak
EECs ranged from 5.26 to 2500 |ig/L for use on ornamental lawns and turf and
lakes/ponds/reservoirs/swamps/marshes respectively.
Since some of the application data needed for modeling was not stated on the labels,
assumptions were made by EFED analysts regarding the maximum number of
applications allowed per season, and/or the interval between applications. The
assumptions were as follows:
• For the application intervals that were not stated, the most conservative
(minimum) known application interval was used (21 days). Twenty-one days was
chosen because it was the minimum known interval that was registered.
• If the maximum number of applications was not stated, the most conservative
(maximum) known number of applications was used (17 applications). Seventeen
applications were chosen because 365 days per year divided by 21 days per
application results in 17 applications allowed per year.
Table 3-3 Aquatic EECs (ug/L) for Triclopyr Uses in California
Crops Represented
DOUGLAS-FIR (FOREST/SHELTERBELT)
CONIFER RELEASE
CHRISTMAS TREE PLANTATIONS, CONIFER
RELEASE, FOREST TREES (ALL OR
UNSPECIFIED), FOREST TREE
MANAGEMENT/FOREST PEST
MANAGEMENT
CHRISTMAS TREE PLANTATIONS, FOREST
TREES (ALL OR UNSPECIFIED), CONIFER
RELEASE
FOREST TREE MANAGEMENT/FOREST PEST
MANAGEMENT, FOREST TREES (ALL OR
UNSPECIFIED)
ORCHARDS (non-food stump treatment)
AIRPORTS/LANDING FIELDS,
COMMERCIAL/INSTITUTIONAL/INDUSTRIAL
PREMISES/EQUIPMENT (OUTDOOR)
PAVED AREAS (PRIVATE
ROADS/SIDEWALKS), DRAINAGE SYSTEMS,
INDUSTRIAL AREAS (OUTDOOR),
NONAGRICULTURAL RIGHTS-OF-
WAY/FENCEROWS/HEDGEROWS
COMMERCIAL STORAGES/WAREHOUSES
PREMISES, PAVED AREAS (PRIVATE
ROADS/SIDEWALKS), DRAINAGE SYSTEMS,
INDUSTRIAL AREAS (OUTDOOR)
AGRICULTURAL RIGHTS-OF-
WAY/FENCEROWS/HEDGEROWS
NONAGRICULTURAL RIGHTS-OF-
WAY/FENCEROWS/HEDGEROWS
ORNAMENTAL HERBACEOUS PLANTS,
ORNAMENTAL NONFLOWERING PLANTS
ORNAMENTAL AND/OR SHADE TREES,
ORNAMENTAL WOODY SHRUBS AND VINES
Date of
First
Application
l-Jan
1-Jan
2-Jan
1-Jan
2-Jan
1-Apr
2-Jan
2-Jan
2-Jan
2-Jan
2-Jan
1-Apr
1-Apr
Peak
EEC
44.0
127.7
194.7
534.6
337.9
148.4
3479.0
1363.0
5802.0
250.1
1319.2
2929.6
34.0
415.3
382.6
21-day
average
EEC
40.4
116.6
176.5
491.9
309.8
131.0
3141.0
1242.0
5244.0
226.9
1200.2
2666.9
30.2
376.2
338.4
60-day
average
EEC
35.5
107.6
136.9
426.3
286.0
109.7
2864.0
1006.5
4770.0
190.7
1098.5
2442.3
23.9
308.5
268.7
62
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Crops Represented
AGRICULTURAL/FARM
STRUCTURES/BUILDINGS AND EQUIPMENT
AGRICULTURAL/FARM PREMISES
AGRICULTURAL FALLOW/IDLELAND,
NONAGRICULTURAL UNCULTIVATED
AREAS/SOILS
AGRICULTURAL FALLOW/IDLELAND
AGRICULTURAL/FARM PREMISES
AGRICULTURAL/FARM
STRUCTURES/BUILDINGS AND EQUIPMENT,
AGRICULTURAL UNCULTIVATED AREAS,
NONAGRICULTURAL UNCULTIVATED
AREAS/SOILS
PASTURES, RANGELAND
RECREATION AREA LAWNS, RESIDENTIAL
LAWNS
RESIDENTIAL LAWNS
HOUSEHOLD/DOMESTIC DWELLINGS
OUTDOOR PREMISES, RECREATION AREA
LAWNS
ORNAMENTAL LAWNS AND TURF
COMMERCIAL/INDUSTRIAL LAWNS,
ORNAMENTAL LAWNS AND TURF
ORNAMENTAL SOD FARM (TURF)
COMMERCIAL/INDUSTRIAL LAWNS
ORNAMENTAL SOD FARM (TURF)
GOLF COURSE TURF
RICE
AQUATIC AREAS/WATER,
INTERMITTENTLY FLOODED
AREAS/WATER, LAKES/PONDS/RESERVOIRS
(WITH HUMAN OR WILDLIFE USE)
AQUATIC AREAS/WATER,
INTERMITTENTLY FLOODED AREAS/WATER
SWAMPS/MARSHES/WETLANDS/STAGNANT
WATER
LAKES/PONDS/RESERVOIRS (WITH HUMAN
OR WILDLIFE USE),
SWAMPS/MARSHES/WETLANDS/STAGNANT
WATER
Date of
First
Application
l-Apr
1-Apr
l-Apr
1-Apr
l-Apr
1-Apr
1-Apr
1-Apr
1-Feb
1-Feb
1-Feb
2-Jan
2-Jan
2-Jan
2-Jan
2-Jan
2-Jan
NA
NA
NA
NA
NA
Peak
EEC
77.3
103.1
87.8
64.6
990.2
990.2
32.9
394.8
75.0
415.0
1499.4
5.3
34.6
20.8
124.8
165.1
270.0
763.0
763.0
2500.0
2500.0
2500.0
2500.0
21-day
average
EEC
70.0
93.7
81.2
60.6
908.2
908.2
30.4
354.8
69.1
376.3
1317.2
4.7
31.7
18.9
113.1
154.6
245.9
763.0
763.0
2500.0
2500.0
2500.0
2500.0
60-day
average
EEC
65.0
87.1
66.5
49.9
793.9
793.9
24.9
321.9
61.7
309.0
1171.6
4.0
28.6
15.7
94.3
133.8
219.5
763.0
763.0
2500.0
2500.0
2500.0
2500.0
NA: (Not Applicable). This information is not necessary in order to determine the EEC.
It is important to note for those uses modeled using PRZM/EXAMS, the calculated EECs
would increase by 25% when the half-life for the aquatic photolysis study is calculated to
reflect 12 hours of continuous sunlight (0.75 days). In the modeling shown above, 0.375
days was used as the aquatic photolysis study half-life; however, this value assumes 24
hours of daylight when adjusting the 8 hour value to days, (i.e., for the use on outdoor
industrial areas would increase the peak EEC from 5802 ppb to 7782 ppb).
Likewise, it is important to note that when the mitigation from the 1998 RED are
implemented on the labels for triclopyr the maximum application rate would be 9 Ibs
ae/A as opposed to 20 Ibs ae/A as modeled above. This will decrease the calculated
EECs by approximately 50%. (i.e., for the use on outdoor industrial areas, the peak EEC
would decrease from 5802 ppb (or 7782 ppb as mentioned above) to 2808 ppb). When
looking at Section 5.0, although there may be a decrease in EECs, the determinations for
63
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the direct effects, indirect effects, and effects to aquatic plants remain the same. Please
see Appendix Q.
3.2.4 Existing Monitoring Data
Whenever it is available, monitoring data are included in assessments in OPPs pesticide
ecological risk assessments in order to better characterize the modeled. In this
assessment, monitoring data were sought from the following sources: the USGS
NAWQA program (http://water.usgs.gov/nawqa), the California Department of Pesticide
Regulation (CDPR), and the California Air Review Board.
3.2.4.1 USGS NAWQA Surface Water Data
The USGS has not looked for any samples containing triclopyr. Therefore, no surface
water data are available.
3.2.4.2 USGS NAWQA Groundwater Data
The USGS has not collected any samples looking for triclopyr. Therefore, no ground
water data are available.
3.2.4.3 California Department of Pesticide Regulation (CDPR) Data
The California Department of Pesticide Regulation (CDPR) has been collecting surface
water data on triclopyr for many years. Samples were taken in six California counties
from March 1993 to March 2006. Out of 583 samples, 102 samples contained triclopyr.
The median concentration of positive samples was 0.65 ppb and the mean concentration
was 1.7 ppb. The highest detected concentration of 14.5 ppb was recorded on June 21,
2001 at Colusa Basin Drain #5 in Colusa County, which is in the main rice-growing
region of California. Triclopyr concentrations were consistently elevated at this site
through the months of June and July, 2001 with an average concentration of 3.5 ppb.
This is probably due to the use of triclopyr on rice, as the same location is also the most
contaminated for other rice herbicides (for example, propanil, thiobencarb and molinate).
Colusa County is one of four leading counties for rice production in California. The Rice
Model predicted a concentration of 763.00 ppb. This is about twenty times larger than
the observed peak in Colusa Basin Drain #5, and shows that the Tier 1 Rice model is
conservative. Due to the relatively short aqueous photolysis half-life, concentrations in
rice paddies probably decline quickly before canopy closure.
3.2.4.4 Atmospheric Monitoring Data
The California Air Review Board has not conducted ambient air monitoring for triclopyr.
Therefore, no atmospheric monitoring data are available.
3.3 Terrestrial Animal Exposure Assessment
T-REX (Version 1.3.1) is used to calculate dietary and dose-based EECs of triclopyr 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
64
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values for frogs serving as potential prey of CRLF adults. T-REX simulates a 1-year time
period. For this assessment, foliar and granular applications of triclopyr are considered,
as discussed below.
Terrestrial EECs for foliar formulations of triclopyr were derived for the uses
summarized in Table 3-4. Given that no data on interception and subsequent dissipation
from foliar surfaces is available for triclopyr, a default foliar dissipation half-life of 35
days is used based on the work of Willis and McDowell (1987). Use specific input
values, including number of applications, application rate and application interval are
provided in Table 3-4. Since mitigation from the 1998 RED has not been implemented
yet, the current label application rates are used to calculate risk to terrestrial organisms.
The current maximum application rate for foliar application is 20 Ibs ae/A, and the
mitigated maximum application rate for foliar application would be 9 Ibs ae/A. The
current median foliar application rate is 8 Ibs ae/A, therefore, to assess the difference in
exceedances the 8 Ibs ae/A will be used to compare to the recommended mitigated
maximum application rate. An example output from T-REX is available in Appendix E.
Table 3-4 Input Parameters for Foliar and Granular Applications Used to Derive
Terrestrial EECs for Triclopyr with T-REX
Use (Application method)
Agricultural Uncultivated Areas (Max. Foliar)
Forest Tree/Pest Management (Median Foliar)
Douglas-Fir (Forest/Shelterbelt) (Median Foliar)
Rice (Min. Foliar)
Commercial/Industrial Lawns (Max. Granular)
Ornamental Lawns and Turf (Min. Granular)
Application rate
(Ibs ae/A)
20
8
1.5
0.38
1.5
0.76
Number of Applications
17
17
17
2
17
1
T-REX is also used to calculate EECs for terrestrial insects exposed to triclopyr. Dietary-
based EECs calculated by T-REX for small and large insects (units of a.e./g) are used to
bound an estimate of exposure to terrestrial insects. Available acute contact toxicity data
for bees exposed to triclopyr (in units of jig a.e./bee), are converted to jig a.e./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.
For modeling purposes, exposures of the CRLF to triclopyr 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 Kenega nomogram values
reported by T-REX for these two organism types are used for derivation of EECs for the
CRLF and its potential prey (Table 3-5). Dietary-based EECs for small and large insects
reported by T-REX as well as the resulting adjusted EECs are available in Table 3-7. An
example output from T-REX v. 1.3.1 is available in Appendix E.
For granular uses of triclopyr the LD50/ft2 is used to estimate risk to the CRLF both
directly and indirectly (via prey items). The LDso/ft2 is the amount of a pesticide
estimated to kill 50% of exposed animals in each square foot of an applied area.
65
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Although a square foot does not have a defined ecological relevance, risk presumably
increases as the number of LD50/ft2 increases (USEPA 1992). The LD50/ft2 is calculated
using a toxicity value (the adjusted LDso) and the EC (mg a.e./ft2), and is compared to the
Agency's LOG. For broadcast granular applications the mg a.e./ft2 is calculated by the
following formula: (application rate* % a.i. * 453,590 mg/lb)/43,560 ft2 acre"1. Results
are presented in terms of the acid equivalent. Estimated EECs for broadcast granular
application for both direct and indirect effects to the CRLF are presented in Table 3-6.
Table 3-5 Upper-bound Kenega Nomogram EECs for Dietary- and Dose-based
Exposures of the CRLF and its Prey to Triclopyr (Foliar Applications)
Use
Agricultural Uncultivated Areas
Forest Tree/Pest Management
Douglas-Fir (Forest/Shelterbelt)
Rice
EECs for CRLF
(Avian, 20 g)
Dietary-based
EEC (ppm)
7929
3171
595
85
Dose-based EEC
(mg/kg-bw)
9030
3612
677
97
EECs for Prey
(small mammals, 15 g)
Dietary-based
EEC (ppm)
14095
5638
1057
151
Dose-based EEC
(mg/kg-bw)
13439
5376
1008
144
Table 3-6 EECs (mg a.e./ft) for Direct and Indirect Effects to the Terrestrial-Phase
CRLF (Granular Applications)
Use
Commercial/Industrial Lawns (Max.)
Ornamental Lawns and Turf (Min.)
EECs for CRLF
(mg a.e./ft2)
15.62
7.91
Table 3-7 EECs (ppm) for Indirect Effects to the Terrestrial-Phase CRLF via
Effects to Terrestrial Invertebrate Prey Items (Foliar Applications)
Use
Agricultural Uncultivated Areas
Forest Tree/Pest Management
Douglas-Fir (Forest/Shelterbelt)
Rice
Small Insect
7930
3171
595
85
Large Insect
881
352
66
9.5
3.4 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 3-8).
A runoff value greater than 1,000 feet is utilized based on triclopyr's solubility, which is
classified in TerrPlant as 440 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 3-8.
Since mitigation from the 1998 RED has not been implemented yet, the current label
application rates are used to calculate risk to terrestrial organisms. The current maximum
66
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application rate for foliar application is 20 Ibs ae/A, and the mitigated maximum
application rate for foliar application would be 9 Ibs ae/A. The current median foliar
application rate is 8 Ibs ae/A, therefore, to assess the difference in exceedances the 8 Ibs
ae/A will be used to compare to the recommended mitigated maximum application rate.
An example output from TerrPlant v. 1.2.2 is available in Appendix G.
Table 3-8 TerrPlant Inputs and Resulting EECs for Plants Inhabiting Dry and
Semi-aquatic Areas Exposed to Triclopyr (acid equivalent) via Runoff and Drift
(Foliar and Granular Applications)
Use
Agricultural
Uncultivated Areas
(Max.)
Forest Tree/Pest
Management (Median)
Forest Tree/Pest
Management (Median)
Douglas-Fir
(Forest/Shelteibelt)
(Median)
Rice (Min)
Rice (Min)
Commercial/Industrial
Lawns (Max)
Ornamental Lawns and
Turf (Min)
Application
rate
(Ibs ae/A)
20
8
8
1.5
0.38
0.38
1.5
0.76
Application
method
Foliar - ground
Foliar - ground
Foliar - aerial
Early Spring -
sprayer
Ratoon - ground
Ratoon - aerial
Granular -
spreader
Granular -
spreader
Drift
Value
(%)
1
1
5
5
1
5
0
0
Spray drift
EEC
(Ibs a.e./A)
0.2
0.08
0.4
0.075
0.0038
0.019
0
0
Dry area
EEC
(Ibs a.e./A)
1.2
0.48
0.8
0.15
0.228
0.038
0.075
0.038
Semi-
aquatic
area EEC
(Ibs a.e./A)
10.2
4.08
4.4
0.825
0.1938
0.209
0.75
0.38
67
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4.0 Effects Assessment
This assessment evaluates the potential for triclopyr to directly or indirectly affect the
CRLF or modify its designated critical habitat. As previously discussed in Section 2.7,
assessment endpoints for the CRLF effects determination include direct toxic effects on
the survival, reproduction, and growth of 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 effects to the PCEs, which are
components of the critical habitat areas that provide essential life cycle needs of the
CRLF. Direct effects to the aquatic-phase of the CRLF are based on toxicity information
for freshwater fish, while terrestrial-phase effects are based on avian toxicity data.
Because the frog's prey items and habitat requirements are dependent on the availability
of freshwater fish and invertebrates, small mammals, terrestrial invertebrates, and aquatic
and terrestrial plants, toxicity information for these taxa are also discussed. Acute (short-
term) and chronic (long-term) toxicity information is characterized based on registrant-
submitted studies and a comprehensive review of the open literature on triclopyr.
As described in the Agency's Overview Document (U.S. EPA 2004), the most sensitive
endpoint for each taxon is used for risk estimation. For this assessment, evaluated taxa
include aquatic-phase amphibians, freshwater fish, freshwater invertebrates, aquatic
plants, birds (surrogate for terrestrial-phase amphibians), mammals, terrestrial
invertebrates, and terrestrial plants.
Toxicity endpoints are established based on data generated from guideline studies
submitted by the registrant, and from open literature studies that meet the criteria for
inclusion into the ECOTOX database maintained by EPA/Office of Research and
Development (ORD) (U.S. EPA 2004). Open literature data presented in this assessment
were obtained from ECOTOX information obtained on June 30, 2009. In order to be
included in the ECOTOX database, papers must meet the following minimum criteria:
(1) the toxic effects are related to single chemical exposure;5
(2) the toxic effects are on an aquatic or terrestrial plant or animal species;
(3) there is a biological effect on live, whole organisms;
(4) a concurrent environmental chemical concentration/dose or application
rate is reported; and
(5) there is an explicit duration of exposure.
Data that pass the ECOTOX screen are evaluated along with the registrant-submitted
data, and may be incorporated qualitatively or quantitatively into this endangered species
assessment. In general, effects data in the open literature that are more conservative than
the registrant-submitted data are considered. The degree to which open literature data are
quantitatively or qualitatively characterized for the effects determination is dependent on
5 The studies that have information on mixtures are listed in the bibliography as rejected due to the
presence of mixtures. These studies are evaluated by EFED when applicable to the assessment; however,
the data is not used quantitatively in the assessment.
68
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whether the information is relevant to the assessment endpoints (i.e., maintenance of
CRLF survival, reproduction, and growth) 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 available. Although the effects determination relies
on endpoints that are relevant to the assessment endpoints of survival, growth, or
reproduction, it is important to note that the full suite of sublethal endpoints potentially
available in the effects literature (regardless of their significance to the assessment
endpoints) are considered to define the action area for triclopyr.
A detailed spreadsheet of the available ECOTOX open literature data for Triclopyr (acid,
TEA, and BEE), including the full suite of lethal and sublethal endpoints is presented in
Appendix N. The endpoints from the studies were classified as being more or less
sensitive (toxic) than the registrant studies. After review of these open literature studies,
there were no studies that could be used quantitatively or qualitatively within the
assessment.
Citations of all open literature that were not considered as part of this assessment because
they were either rejected by the ECOTOX screen (excluded from ECOTOX entirely, not
acceptable for ECOTOX, or efficacy papers examining the target species) are included in
Appendix H. Open literature toxicity data for 'target' terrestrial plant species, which
include efficacy studies, are not currently considered in deriving the most sensitive
endpoint for terrestrial plants. Efficacy studies do not typically provide endpoint values
that are useful for risk assessment (e.g., NOAEC, EC50, etc.), but rather are intended to
identify a dose that maximizes a particular effect (e.g., EC 100). Therefore, efficacy data
and non-efficacy toxicological target data are not included in the ECOTOX open
literature summary table provided in Appendix N. The list of citations including
toxicological and/or efficacy data on target plant species not considered in this
assessment is provided in Appendix H. Also included is a rationale for rejection of those
studies that did not pass the ECOTOX screen and those that were not evaluated as part of
this endangered species risk assessment for Triclopyr (acid, TEA, and BEE). Citations of
all open literature data, including studies accepted by ECOTOX but not used (e.g., the
endpoint is less sensitive), studies that have been reviewed accepted by ECOTOX but not
OPP, and those studies that are more sensitive and used or not used within the assessment
are found in Appendix I.
In addition to registrant-submitted and open literature toxicity information, other sources
of information, including use of the acute probit dose response relationship to establish
the probability of an individual effect and reviews of the Ecological Incident Information
System (EIIS), are conducted to further refine the characterization of potential ecological
effects associated with exposure to triclopyr. A summary of the available aquatic and
terrestrial ecotoxicity information, use of the probit dose response relationship, and the
incident information for triclopyr are provided in Sections 4.1 through 4.4, respectively.
The major degradate of triclopyr is 3,5,6-trichloro-2-pyridinol (TCP), which is both
persistent and mobile. Toxicity data for the degradate indicates that when converted to
69
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the acid equivalent TCP is less toxic than the most sensitive endpoint for triclopyr.
Therefore, in terms of the acid equivalent TCP is not of toxicological concern and is not
evaluated in this assessment. However, since there is a difference in toxicity between
triclopyr forms (Acid, TEA, BEE, and TCP) for species, Appendix A shows a
comparison of the toxicity of triclopyr in terms of the acid equivalent for each of the
Triclopyr forms as well as the degradate TCP. A detailed summary of the available
ecotoxicity information for all triclopyr degradates and formulated products are also
presented in Appendix A.
The Agency does not routinely include, in its risk assessments, an evaluation of mixtures
of active ingredients, either those mixtures of multiple active ingredients in product
formulations or those in the applicator's 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
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 quantitatively6' 7. Triclopyr has three registered products
that contain multiple active ingredients. They are: TAILSPIN (EPA Reg. No. 34704-
958) triclopyr (16.1% ai) with Fluroxypyr (5.6 % ai), GF-1249 (EPA Reg. No. 62719-
528) triclopyr (22.2% ai) with Picloram (potassium salt, 4.07 % ai), and RICEPYR (EPA
Reg. No. 71085-29) triclopyr (3.8% ai) with Propanil (36.5% ai) (see Appendix B).
Only one product (EPA Reg. No. 71085-29) has a definitive LD50 value with an
associated 95% CI. In the case of EPA Reg No. 71085-29, the toxicity can be attributed
to propanil (the other active ingredient in the formulated product). When the LD50 (1750
mg/kg) for this product and its confidence interval (1239-4450 mg/kg) are adjusted for
the percent propanil (36.5%), the adjusted LD50 value of 639 mg/kg (CI: 452-1624
mg/kg), the adjusted confidence interval falls within the confidence interval for the
propanil technical (868-1343 mg/kg). For EPA Reg. No. 34704-958 and 62719-528 no
definitive LD50 values are available with an associated 95% CI. There is an, LD50 value
of 1847 mg/kg (410 mg/kg adjusted for active ingredient triclopyr) available for EPA
Reg. No. 62719-528, however it is not considered to be a definitive number by HED, as
no confidence intervals are available for the LD50 (see Appendix B). Therefore, no
definitive statement of toxicity can be made for the other two products regarding if they
pose any toxic risk greater or less than triclopyr alone. The results of available toxicity
data for mixtures of triclopyr with other pesticides are presented in Appendix B.
Given that the active would not be expected to have similar mechanisms of action,
metabolites or toxicokinetic behavior it is also reasonable to conclude that an assumption
of dose-addition would be inappropriate. Consequently, an assessment of triclopyr's
potential effect on the CRLF when it is co-formulated with other active ingredients can
be based on the toxicity of triclopyr.
6 Overview of the Ecological Risk Assessment Process in the Office of Pesticide Programs, Environmental
Protection Agency (January 2004) (Overview Document).
7 Memorandum to Office of Prevention, Pesticides and Toxic Substance, US EPA conveying an evaluation
by the U.S. Fish and Wildlife Service and National Marine Fisheries Service of an approach to assessing
the ecological risks of pesticide products (January 2004).
70
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4.1 Evaluation of Aquatic Ecotoxicity Studies
Table 4-1 summarizes the most sensitive aquatic toxicity endpoints for the CRLF, based
on an evaluation of both the submitted studies and the open literature, as previously
discussed. A brief summary of submitted and open literature data considered relevant to
this ecological risk assessment for the CRLF is presented below. Additional information
and a complete list of all toxicity data available is provided in Appendix A.
Table 4-1 Freshwater Aquatic Toxicity Profile for Triclopyr (TEA and BEE
expressed as the acid equivalent)
Assessment
Endpoint
Species
Toxicity Value Used
in Risk Assessment
(expressed as ae)
Describe effect
(i.e. mortality,
growth,
reproduction)
Citation
MRID#
(Author &
Date)
Study
Classification
Direct Toxicity to Aquatic-Phase CRLF
Acute
Chronic
Bluegill sunfish
(Lepomis
macrochirus)
Rainbow Trout
(Oncorhynchus
mykiss)
96hLC50 = 0.26
mgae/L
(BEE)
NOAEC = 0.019
LOAEC = 0.034
mgae/L
(BEE)
Mortality
Growth
(larval weight/
length)
42917901
Woodburn
etal. 1993
43230201
Weinberg et
al. 1994
Acceptable
Acceptable
Indirect Toxicity to Aquatic-Phase CRLF
via Acute
Toxicity to
Freshwater
Invertebrates
(i.e. prey items)
via Chronic
Toxicity to
Freshwater
Invertebrates
(i.e. prey items)
via Acute
Toxicity to
Freshwater Fish
(i.e. prey items)
via Chronic
Toxicity to
Freshwater Fish
(i.e. prey items)
via Toxicity to
Non-vascular
Aquatic Plants
via Toxicity to
Non-vascular
Aquatic Plants
via Toxicity to
Vascular Aquatic
Plants
Water Flea
(Daphnia magnd)
Water Flea
(Daphnia magnd)
Bluegill sunfish
(Lepomis
macrochirus)
Rainbow Trout
(Oncorhynchus
mykiss)
Freshwater diatom
(Navicula
pelliculosa)
Freshwater diatom
(Navicula
pelliculosa)
Duckweed
(Lemna gibba)
48hEC50 = 0.25
mgae/L
(BEE)
21-dNOAEC = 25
21-d LOAEC = 46.2
mgae/L
(TEA)
96hLC50 = 0.26
mgae/L
(BEE)
NOAEC = 0.019
LOAEC = 0.034
mgae/L
(BEE)
5dEC50 = 0.07
mgae/L
(BEE)
5dNOEAC = 0.0014
mgae/L
(BEE)
14dEC50 = 0.86
mgae/L
(BEE)
Mortality
Growth and
Reproduction
(total # of young &
mean brood size)
Mortality
Growth
(larval weight/
length)
Growth
(cell counts &
% inhibition)
Growth
(cell counts &
% inhibition)
Growth and
Reproduction
(# Fronds)
43442603
Weinberg et
al. 1994
00151959,
42090411,
92189013
Gerisch
1982
42917901
Woodburn
etal. 1993
43230201
Weinberg et
al. 1994
42721102
Hughes
1993
42721102
Hughes
1993
42719101
Milazzo et
al. 1993
Acceptable
Acceptable
Acceptable
Acceptable
Acceptable
Acceptable
Supplemental
71
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via Toxicity to
Vascular Aquatic
Plants
Duckweed
(Lemna gibba)
14d NOAEC
< 0.111 mgae/L
(BEE)
Growth and
Reproduction
(# Fronds)
42719101
Milazzo et
al. 1993
Supplemental
Toxicity to aquatic fish and invertebrates is categorized using the system shown in Table
4-2 (U.S. EPA 2004). Triclopyr falls in the range of "highly toxic" for freshwater fish
and invertebrates on an acute exposure basis. Toxicity categories for aquatic plants have
not been defined.
Table 4-2 Categories of Acute Toxicity for Fish and Aquatic Invertebrates
LCSO (ppm)
<0.1
>0.1-1
>1 -10
> 10 - 100
>100
Toxicity Category
Very highly toxic
Highly toxic
Moderately toxic
Slightly toxic
Practically nontoxic
4.1.1 Toxicity to Freshwater Fish
Given that no scientifically valid triclopyr toxicity data are available for aquatic-phase
amphibians, freshwater fish data were used as a surrogate to estimate direct acute and
chronic risks to the CRLF. Freshwater fish toxicity data were also used to assess
potential indirect effects of triclopyr to the CRLF. Effects to freshwater fish resulting
from exposure to triclopyr may indirectly affect the CRLF via reduction in available
food. As discussed in Section 2.5.3, over 50% of the prey mass of the CRLF may consist
of vertebrates such as mice, frogs, and fish (Hayes and Tennant 1985).
A summary of acute and chronic freshwater fish data, including data from the open
literature, is provided below in Sections 4.1.1.1 through 4.1.1.3.
4.1.1.1 Freshwater Fish: Acute Exposure (Mortality) Studies
Freshwater fish data are used as a surrogate to estimate direct acute risks to the CRLF.
Effects to freshwater fish from direct exposure to triclopyr could also indirectly affect the
CRLF from reduction in available food.
Triclopyr is classified as highly toxic to freshwater fish on an acute exposure basis. The
most sensitive freshwater species tested was the bluegill sunfish, (Lepomis macrochims),
which exhibited a 96-hr LC50 value of 0.26 mg ae/L (triclopyr BEE, TGAI, MRID
4217901). The rainbow trout (Oncorhynchus mykiss) exhibited a 96-hr LCso value of
0.47 mg ae/L (triclopyr BEE, TGAI, MRID 42884501). Registrant submitted studies for
acute freshwater fish are available for both the bluegill sunfish and the rainbow trout for
triclopyr acid (as TGAI), triclopyr TEA (formulation), triclopyr BEE (both TGAI and
formulation), and TCP (as TGAI). The most sensitive endpoints for the bluegill sunfish
range from 155 mg ae/L (triclopyr TEA, formulated product, MRID 00049637) to 0.26
mg ae/L (triclopyr BEE, TGAI, MRID 4217901). The most sensitive endpoints for the
rainbow trout range from 117 mg/L (triclopyr acid, TGAI, MRID 00049637) to 0.47 mg
ae/L (triclopyr BEE, TGAI, MRID 42884501). The degradate TCP for both the bluegill
sunfish and rainbow trout are more toxic than the parent(s) triclopyr acid and triclopyr
TEA, 16.1 mg ae/L (MRID 41829003) and 1.9 mg ae/L (TCP, TGAI, MRID 41829004).
72
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However, for use in evaluating direct effects to aquatic-phase CRLFs, in terms of acid
equivalence, it is not the most sensitive freshwater fish endpoint; as a result toxicity to
non-target organisms is calculated using triclopyr acid equivalence alone.
4.1.1.2 Freshwater Fish: Chronic Exposure (Early Life Stage and
Reproduction) Studies
The rainbow trout exhibited a chronic toxicity NOAEC of 0.019 mg ae/L, and a LOAEC
of 0.034 mg ae/L based on growth effects (larval weight/length) (triclopyr BEE, TGAI,
MRID 43230201). No other registrant submitted studies are available for the rainbow
trout for triclopyr acid, triclopyr TEA or TCP. There is only one other chronic exposure
study available. The fathead minnow exhibited a NOAEC > 32.2 mg ae/L and a LOAEC
< 50.2 mg ae/L based on growth effects (length) (triclopyr TEA, formulated product,
MRID 00151958).
4.1.1.3 Freshwater Fish: Sublethal Effects and Additional Open
Literature Information
There are numerous studies found within the ECOTOX database, however they are not
integrative in the measurements of growth and/or reproduction, not scientifically valid or
more sensitive than registrant-submitted data. Potential sublethal effects on fish are
evaluated qualitatively and not used as part of the quantitative risk characterization of
triclopyr to the CRLF. Further details on ECOTOX studies are provided in Appendix I,
which also contains the rejection codes and other information as to why studies from
ECOTOX were not used.
4.1.1.4 Aquatic-phase Amphibian: Acute and Chronic Studies
Studies are found in ECOTOX that used aquatic-phase amphibians as study organisms.
However, the studies contain numerous flaws and as a result they are not used in this risk
assessment. In particular there are concerns with the husbandry of the organisms (i.e., the
amount of individuals per treatment replicate), the lack of detailed information within the
published literature especially in regards to the controls and the chemical solutions that
are used within the experiments, and there is also some concern with the testing methods
used, specifically with the Frog Embryo Teratogenesis Assay-Xenopus (FETAX). Some
of the studies also contained numerous other variables (i.e., pH, food levels, etc) that
make it difficult to determine the actual cause of any effects seen. Appendix I contains
information as to why these studies and others from ECOTOX are not used within the
assessment.
4.1.2 Toxicity to Freshwater Invertebrates
Freshwater aquatic invertebrate toxicity data are used to assess potential indirect effects
of triclopyr to the CRLF. Effects to freshwater invertebrates resulting from exposure to
triclopyr may indirectly affect the CRLF via reduction in available food items. As
discussed in Section 2.5.3, the main food source for juvenile aquatic- and terrestrial-
phase CRLFs is thought to be aquatic invertebrates found along the shoreline and on the
water surface, including aquatic sowbugs, larval alderflies and water striders.
73
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A summary of acute and chronic freshwater invertebrate data, including data published in
the open literature, is provided below in Sections 4.1.2.1 through 4.1.2.3.
4.1.2.1 Freshwater Invertebrates: Acute Exposure (Mortality) Studies
Triclopyr is classified as highly toxic to freshwater invertebrates on an acute exposure
basis based on acceptable studies on the water flea (Daphnia magna). This species
exhibited a 48-hr EC50 value of 0.25 mg ae/L (triclopyr BEE, TGAI, MRID 43442603)
for BEE. Registrant submitted studies for acute freshwater invertebrates are available for
Daphnia magna for triclopyr acid (as TGAI), triclopyr TEA (formulation), triclopyr BEE
(both TGAI and formulation), and TCP (as TGAI). The most sensitive endpoints for the
Daphnia magna range from 346 mg ae/L (triclopyr TEA, formulated product, MRID
00151956) to 0.25 mg ae/L (triclopyr BEE, TGAI, MRID 43442603). The degradate
TCP for Daphnia magna are more toxic than the parent(s) triclopyr acid and triclopyr
TEA, 13.4 mg ae/L (TCP, TGAI, MRID 41829003). However, for use in evaluating
indirect effects to aquatic-phase CRLFs, in terms of acid equivalence, it is not the most
sensitive freshwater invertebrate endpoint; as a result, toxicity to non-target organisms is
calculated using triclopyr acid equivalence alone.
4.1.2.2 Freshwater Invertebrates: Chronic Exposure (Reproduction)
Studies
Chronic toxicity studies show that the water flea (Daphnia magna) exhibited a 21-d
NOAEC of 25 mg ae/L and a LOAEC of 46.2 mg ae/L based on the total number of
young and mean brood size (triclopyr TEA, formulated, MRID 00151959, 42090411, and
92189013). No other registrant submitted chronic toxicity studies using triclopyr acid,
triclopyr BEE or the degradate TCP are available.
4.1.2.3 Freshwater Invertebrates: Sublethal Effects and Open
Literature Data
For freshwater invertebrates, none of the acute or chronic toxicity values reported
through ECOTOX are more sensitive than the registrant-submitted data on Daphnia
magna using any form of triclopyr expressed as the acid equivalent.
4.1.3 Toxicity to Aquatic Plants
Aquatic plant toxicity studies are used as one of the measures of effect to evaluate
whether triclopyr may affect primary production and the availability of aquatic plants as
food for CRLF tadpoles. Primary productivity is essential for indirectly supporting the
growth and abundance of the CRLF.
Two types of studies are used to evaluate the potential of triclopyr to affect aquatic
plants. Laboratory and field studies are used to determine whether triclopyr may cause
direct effects to aquatic plants. A summary of the laboratory data and freshwater field
studies for aquatic plants is provided in Sections 4.1.3.1 and 4.1.3.2
4.1.3.1 Aquatic Plants: Laboratory Data
Both the vascular and non-vascular aquatic plant studies that include the most sensitive
species are Tier II toxicity tests. The freshwater diatom (Naviculapelliculosa) is the
74
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most sensitive non-vascular plant with a 5d ECso of 0.07 mg ae/L and a NOAEC of
0.0014 mg ae/L based on cell counts and percent inhibition (triclopyr BEE, TGAI, MRID
42721102). The vascular plant Lemna gibba is the most sensitive vascular plant with a
14d ECso of 0.86 mg ae/L based on the number of fronds (triclopyr BEE, TGAI, MRID
42719101).
Registrant submitted studies for non-vascular aquatic plants are available for triclopyr
acid (as TGAI), triclopyr TEA (formulation), triclopyr BEE (both TGAI and
formulation), and TCP (as TGAI). Toxicity endpoints are available for three species of
non-vascular plants: green algae (Kirchneria subcapitata), blue-green algae (Anabeana
flos-aquae), and the freshwater diatom (Naviculapelliculosd). The most sensitive
endpoints for the green algae (Kirchneria subcapitata), is the 5d ECso which range from
29.8 mg /L (triclopyr acid, TGAI, MRID) to 2.5 mg ae/L (triclopyr BEE, formulated,
MRID 41633704 and 42090422). The degradate TCP endpoint for green algae is more
toxic than the parent(s) triclopyr acid, triclopyr TEA, and triclopyr BEE with a 5d ECso
of 2.3 mg ae/L (MRID 45312001), and NOAEC (as EC05) of 0.84 mg ae/L based on
yield. This endpoint is not lower than the most sensitive non-vascular aquatic plant
endpoint that is used to estimate indirect effects of triclopyr on non-target aquatic plants.
The most sensitive endpoint for the blue-green algae (Anabeana flos-aquae), is the 5d
EC50 which range from 4.1 mg ae/L (7d EC50, triclopyr TEA, formulated, MRID
41633706) to 1.42 mg ae/L (triclopyr BEE, TGAI, MRID 42721101). The degradate
TCP is not more toxic than the parent(s) triclopyr TEA or BEE with a 5d ECso of 2.3 mg
ae/L (TCP, TGAI, MRID 45312003). For the freshwater diatom (Naviculapelliculosd)
the most sensitive endpoints (5d EC50) range from 10.6 mg ae/L (4d EC50, triclopyr TEA,
formulated, MRID 41633708) to 0.07 mg ae/L (triclopyr BEE, TGAI, MRID 42721102).
Registrant submitted studies for Lemna gibba, the vascular aquatic plant, are available for
triclopyr TEA (formulation), and triclopyr BEE (TGAI), Appendix A. The most
sensitive endpoint for Lemna gibba, the 14d ECso, range from 6.1 mg ae/L (triclopyr
TEA, formulated, MRID 41633709) to 0.86 mg ae/L (triclopyr BEE, TGAI, MRID
42719101. There are no valid registrant submitted studies for the degradate TCP for
vascular aquatic plants.
4.1.3.2 Freshwater Field Studies
There are no submitted field studies.
4.2 Toxicity of Triclopyr to Terrestrial Organisms
Table 4-3 summarizes the most sensitive terrestrial toxicity endpoints for the CRLF based
on an evaluation of both the submitted studies and the open literature. A brief summary
of submitted and open literature data considered relevant to this ecological risk
assessment for the CRLF is presented below.
75
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Table 4-3 Terrestrial Toxicity Profile for Triclopyr (TEA and BEE expressed as the
acid equivalent)
Assessment
Endpoint
Species
Toxicity Value Used
in Risk Assessment
(expressed as ae)
Describe
effect
(i.e. mortality,
growth,
reproduction)
Citation
MRID#
(Author &
Date)
Study
Classification
Direct Toxicity to Terrestrial-phase CRLF
Acute
Dose-based
Acute
Dietary-based
Chronic
Northern Bobwhite
Quail
(Colinus virginianus)
Northern Bobwhite
Quail
(Colinus virginianus)
Mallard Duck
(Anas platyrhynchos)
21dLD50 = 529
mg ae/kg-bw
(BEE)
8dLC50 = 2934ppm
(Acid)
NOAEC = 100 ppm
LOAEC = 200 ppm
(Acid)
Mortality
Mortality
# of 14d old
survivors
41902002
Campbell &
Lynn 1991
40346403
Dow
Chemical
1976
00031250
Beavers &
Fink 1980
Acceptable
Acceptable
Acceptable
Indirect Toxicity to Terrestrial-phase CRLF
via acute
toxicity to
mammalian
prey items
via chronic
toxicity to
mammalian
prey items
via acute
toxicity to
terrestrial
invertebrate
prey items
via acute
toxicity to
terrestrial
prey items
via acute
toxicity to
terrestrial
prey items
via chronic
toxicity to
terrestrial
prey items
Indirect
Toxicity to
Terrestrial-
and Aquatic-
Phase CRLF
Rat
(Rattus norvegicus)
Rat
(Rattus norvegicus)
Honeybee
(Apis mellifera)
Northern Bobwhite
Quail
(Colinus virginianus)
Northern Bobwhite
Quail
(Colinus virginianus)
Mallard Duck
(Anas platyrhynchos)
Dicot
Seedling Emergence
Alfalfa
(Medicago sativa)
LD50 = 572
mg ae/kg-bw
(M&F)
(TEA)
NOAEL = 5
mg ae/kg-bw
LOAEL = 25
mg ae/kg-bw
(Acid)
48hLD50>72
ug ae/bee
(BEE)
21dLD50 = 529
mg ae/kg-bw
(BEE)
8dLC50 = 2934 ppm
(Acid)
NOAEC = 100 ppm
LOAEC = 200 ppm
(Acid)
EC25 = 0.045 Ib ae/A
NOAEC = 0.0026
Ib ae/A
(BEE)
Mortality
Reproductive
Toxicity
2-generation
study -
Offspring
Mortality
(26% at
highest dose)
Mortality
Mortality
# of 14d old
survivors
parameter:
emergence
00031940
Henck et al.
1979
43545701
Vedula et al
1995
41219109
Dingledine
1985
41902002
Campbell &
Lynn 1991
40346403
Dow Chemical
1976
00031250
Beavers &
Fink 1980
43650001
Schwab 1995
Acceptable
Acceptable
(HED 2002)
Acceptable
Acceptable
Acceptable
Acceptable
Acceptable
76
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Assessment
Endpoint
(via toxicity
to terrestrial
plants)
Species
Dicot
Vegetative Vigor
Sunflower
(Helianthus annus)
Monocot
Seedling Emergence
Onion (Allium cepa)
Monocot
Vegetative Vigor
Onion (Allium cepa)
Toxicity Value Used
in Risk Assessment
(expressed as ae)
EC25 = 0.005 Ib ae/A
NOAEC = 0.0028
Ib ae/A
(TEA)
EC25 = 0.053 Ib ae/A
NOAEC = 0.0021
Ib ae/A
(BEE)
EC25 = 0.063 Ib ae/A
NOAEC < 0.063
Ib ae/A
(BEE)
Describe
effect
(i.e. mortality,
growth,
reproduction)
parameter:
shoot length
parameter:
shoot weight
parameter:
shoot weight
Citation
MRID#
(Author &
Date)
43129801
Schwab 1993
Study
Classification
43650001
Schwab 1995
43650001
Schwab 1995
Acceptable
Acceptable
Acceptable
Acute toxicity to terrestrial animals is categorized using the classification system shown
in Table 4-4 (U.S. EPA 2004). Triclopyr falls in the range of "Slightly toxic" for birds on
an acute oral and dietary exposure basis, and mammals on an acute oral exposure basis.
Toxicity categories for terrestrial plants have not been defined.
Table 4-4 Categories of Acute Toxicity for Avian and Mammalian Studies
Toxicity Category
Very highly toxic
Highly toxic
Moderately toxic
Slightly toxic
Practically non-toxic
Oral LD50
< 10 mg/kg
10-50 mg/kg
51 -500 mg/kg
501 -2000 mg/kg
> 2000 mg/kg
Dietary LCSO
< 50 ppm
50 - 500 ppm
501 - 1000 ppm
1001 - 5000 ppm
> 5000 ppm
4.2.1 Toxicity to Birds
As specified in the Overview Document, the Agency uses birds as a surrogate for
terrestrial-phase amphibians when amphibian toxicity data are not available (U.S. EPA
2004). No terrestrial-phase amphibian data are available for triclopyr; therefore, acute
and chronic avian toxicity data are used to assess the potential direct effects of triclopyr
to terrestrial-phase CRLFs.
4.2.1.1 Birds: Acute Exposure (Mortality) Studies
Avian toxicity data are used as a surrogate to estimate direct acute risks to the CRLF.
Effects to birds from direct exposure to triclopyr could also indirectly affect the CRLF
from reduction in available food (that is, other terrestrial amphibians as prey).
Triclopyr is classified as being slightly toxic to practically non-toxic on an acute oral
exposure basis. The most sensitive species was the northern bobwhite quail with an acute
oral 21-d LD50 value of 529 mg ae/kg-bw (triclopyr BEE, TGAI, MRID 41902002). The
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mallard duck has an acute oral 14-d LD50 value of 1418 mg ae/kg-bw (triclopyr TEA,
formulation, MRID 40346501), and triclopyr is classified as practically non-toxic on an
acute oral exposure basis. There is an avian acute oral registrant submitted study
available for the mallard duck using triclopyr acid. For triclopyr acid, the mallard duck
acute oral LD50 value is 1698 mg/kg-bw (triclopyr acid, TGAI, MRID 40346401). The
degradate TCP is not more toxic than the parent (triclopyr BEE) for the northern
bobwhite quail; the acute oral 8-d LDso value being > 2585 mg ae/kg-bw (TCP, TGAI,
MRID 41829001). No registrant submitted studies are available for triclopyr acid or
triclopyr TEA for the northern bobwhite quail, and no registrant submitted studies are
available for triclopyr BEE or the degradate TCP for the mallard duck.
The most sensitive species is the northern bobwhite quail with a subacute dietary 8-d
LC50 value of 2934 ppm (triclopyr acid, TGAI, MRID 40346403). The mallard duck has
a subacute dietary 8-d LC50 value > 3885 ppm (Triclopyr BEE, TGAI, MRID 41905501).
Registrant submitted studies for avian subacute dietary are available for both the northern
bobwhite and mallard duck for triclopyr acid (as TGAI, northern bobwhite quail only),
triclopyr TEA (formulation), triclopyr BEE (TGAI), and TCP (as TGAI, mallard duck
only). The most sensitive endpoints for the northern bobwhite quail subacute dietary 8-d
LC50 range from 5189 ppm (triclopyr TEA, formulation, MRID 40346503) to 2934 ppm
(triclopyr acid, TGAI, MRID 40346403). The most sensitive endpoints for the mallard
duck subacute dietary 8-d LCso range from > 3885 ppm (Tirlcopyr BEE, TGAI, MRID
41905501) to > 4465 ppm (triclopyr TEA, formulation, MRID 40346502). There are no
degradate subacute dietary registrant submitted studies for the northern bobwhite quail.
But the degradate TCP is not more toxic than the parent(s) triclopyr TEA or triclopyr
BEE on a subacute dietary basis for the mallard duck; the 8-d LCso being > 7265 ppm
(TCP, TGAI, MRID 41829002).
4.2.1.2 Birds: Chronic Exposure (Growth, Reproduction) Studies
The mallard duck is the most sensitive species with a NOAEC of 100 ppm, and a
LOAEC value of 200 ppm based on the number of 14-d old survivors (triclopyr acid,
TGAI, MRID 00031250). No other registrant submitted chronic toxicity studies using
triclopyr TEA, triclopyr BEE, or the degradate TCP are available.
4.2.1.3 Terrestrial-phase Amphibian Acute and Chronic Studies
There are no terrestrial-phase amphibian acute or chronic studies submitted or available
in the open literature.
4.2.2 Toxicity to Mammals
Mammalian toxicity data are used to assess potential indirect effects of triclopyr to the
terrestrial-phase CRLF. Effects to small mammals resulting from exposure to triclopyr
may indirectly affect the CRLF via reduction in available food. As discussed in Section
2.5.3, over 50% of the prey mass of the CRLF may consist of vertebrates such as mice,
frogs, and fish (Hayes and Tennant 1985). See the HED Table from the mammalian
toxicity endpoints for Triclopyr (acid, TEA, and BEE) from the most recent HED Human
Health Risk Assessment completed in 2002 (Appendix M).
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4.2.2.1 Mammals: Acute Exposure (Mortality) Studies
Triclopyr is classified as being slightly toxic to mammals on an acute oral basis. This is
based on an acute oral LD50 value of 572 mg ae/kg-bw (triclopyr TEA, formulation,
MRTD 00031940). Registrant submitted studies for acute oral rats are available for
triclopyr acid (as TGAI), triclopyr TEA (formulation), triclopyr BEE (TGAI), and TCP
(as TGAI). The acute oral LD50 values range from 572 mg ae/kg-bw (Male & Female,
triclopyr TEA, formulation, MRID 00031940) to 630 mg /kg-bw (Female, triclopyr acid,
TGAI, MRID 00031940). The degradate TCP is not more toxic than the parent(s)
triclopyr acid, triclopyr TEA or triclopyr BEE, with an LD50 value of 1026 mg ae/kg-bw
(Male, TCP, TGAI, MRID 00064938).
4.2.2.2 Mammals: Chronic Exposure (Growth, Reproduction) Studies
In the 2-generation reproductive toxicity study for rats, the offspring NOAEL is 5 mg
ae/kg-bw and the LOAEL is 25 mg ae/kg-bw (triclopyr acid, TGAI, MRID 43545701).
The LOAEL is based on an increased incidence of F2 pups with exencephaly and
ablepharia. Parental systemic toxicity resulted in a NOAEL of 5 mg ae/kg-bw, and a
LOAEL of 25 mg ae/kg-bw based on increased incidence of proximal tubular
degeneration in male and female PI and P2 rats. HED determined that triclopyr is not a
mutagen, and has not been classified in terms of carcinogenicity (HED 2002). Triclopyr
has been classified as a Group D chemical, and is unable to be classified as to human
carcinogenicity, based on marginal evidence of tumors in female rates and mice and
benign adrenal pheochromocytomas in male rats (HED 2002). No other registrant
submitted chronic toxicity studies using triclopyr TEA, triclopyr BEE, or the degradate
TCP are available.
4.2.3 Toxicity to Terrestrial Invertebrates
Terrestrial invertebrate toxicity data are used to assess potential indirect effects of
triclopyr to the terrestrial-phase CRLF. Effects to terrestrial invertebrates resulting from
exposure to triclopyr may indirectly affect the CRLF via reduction in available food.
4.2.3.1 Terrestrial Invertebrates: Acute Exposure (Mortality) Studies
Triclopyr is classified as moderately toxic to honeybees based on acute contact. The
honeybee acute contact study resulted in a 48h LDso > 72 ug ae/bee (triclopyr BEE,
TGAI, MRID 41219109). Mortality at the highest dose tested (72 ug ae/bee) at 48 hours
was 26% compared to 6% observed in the negative controls and the second highest dose
tested (43 ug ae/bee), indicating that the mortality seen is most likely treatment related
(MRID 41219109). Registrant submitted studies for honeybee acute contact exposure is
also available for triclopyr acid. For triclopyr acid, the honeybee acute contact 48h
is > 100 ug/bee (triclopyr acid, TGAI, MRID 40356602). There are no registrant
submitted studies using triclopyr TEA or the degradate TCP.
4.2.3.2 Terrestrial Invertebrates: Open Literature Studies
There are no terrestrial invertebrate studies available in the open literature.
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4.2.4 Toxicity to Terrestrial Plants
Terrestrial plant toxicity data are used to evaluate the potential for triclopyr to affect
riparian zone and upland vegetation within the action area for the CRLF. Impacts to
riparian and upland (i.e., grassland, woodland) vegetation may result in indirect effects to
both aquatic- and terrestrial-phase CRLFs, as well as modification to designated critical
habitat PCEs via increased sedimentation, alteration in water quality, and reduction in
upland and riparian habitat that provides shelter, foraging, predator avoidance and
dispersal for juvenile and adult CRLFs.
Plant toxicity data from both registrant-submitted studies and studies in the scientific
literature are reviewed for this assessment. Registrant-submitted studies are conducted
under conditions and with species defined in EPA toxicity test guidelines. Sub-lethal
endpoints such as plant growth, dry weight, and biomass are evaluated for both monocots
and dicots, and effects are evaluated at both seedling emergence and vegetative life
stages. Guideline studies generally evaluate toxicity to ten crop species. These tests are
conducted on herbaceous crop species only, and extrapolation of effects to other species,
such as the woody shrubs and trees and wild herbaceous species, contributes uncertainty
to risk conclusions.
Commercial crop species have been selectively bred, and may be more or less resistant to
particular stressors than wild herbs and forbs. The direction of this uncertainty for
specific plants and stressors, including triclopyr, is largely unknown. Homogenous test
plant seed lots also lack the genetic variation that occurs in natural populations, so the
range of effects seen from tests is likely to be smaller than would be expected from wild
populations.
Tier I results for triclopyr observed that all species tested showed greater than 25%
inhibition for seedling emergence (MRID 41734301) and vegetative vigor (MRID
41784401), which resulted in the need for Tier II testing for all ten species (six dicots and
four monocots) using triclopyr (both TEA and BEE, reported in terms of acid equivalent).
In seedling emergence studies, the most sensitive dicot species is alfalfa (Medicago
saliva) with an EC25 of 0.045 Ib ae/A, and a NOAEC of 0.0026 Ib ae/A (triclopyr BEE,
formulated MRID 43650001), and the most sensitive monocot species is the onion
(Allium cepa) with an EC25 of 0.053 Ib ae/A, and a NOAEC of 0.0021 Ib ae/A (triclopyr
BEE, formulated MRID 43650001). The most sensitive parameter for the alfalfa seedling
emergence study is percent emergence (MRID 43650001), and the most sensitive
parameter for the onion seedling emergence study is shoot weight (MRID 43650001). In
the vegetative vigor studies, the most sensitive dicot species is the sunflower (Helicmthus
annus) with an EC25 of 0.005 Ib ae/A, and a NOAEC of 0.0028 Ib ae/A (triclopyr TEA,
formulated, MRID 43129801), and the most sensitive monocot species is the onion
(Allium cepa) with an EC25 of 0.063 Ib ae/A, and a NOAEC < 0.063 Ib ae/A (triclopyr
BEE, formulated MRID 43650001). The most sensitive parameter for the sunflower is
shoot length (MRID 43129801), and the most sensitive parameter for the onion is shoot
weight (MRID 43650001).
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Registrant submitted studies for non-target terrestrial plants are only available for
triclopyr TEA and triclopyr BEE as formulated products (Garlon 3 A and Garlon 4). No
registrant submitted studies are available for triclopyr acid, or the degradate TCP. For the
vegetative vigor studies, the most sensitive dicot species, the sunflower, EC25'S range
from 0.005 Ib ae/A (triclopyr TEA, formulated, MRID 43129801) to 0.006 Ib ae/A
(triclopyr BEE, formulated MRID 43650001). The most sensitive monocot species, the
onion, EC25 ranges from 0.063 Ib ae/A (triclopyr BEE, formulated MRID 43650001) to
0.114 Ib ae/A (triclopyr TEA, formulated, MRID 43129801). The most sensitive
parameters for the sunflower vegetative vigor studies are shoot length (TEA), and shoot
weight (BEE), and the most sensitive parameter for the onion vegetative vigor studies is
shoot weight (both TEA and BEE). For the seedling emergence studies, the most
sensitive dicot species is alfalfa for triclopyr BEE, and the soybean for triclopyr TEA,
with EC25's that range from 0.045 Ib ae/A (triclopyr BEE, formulated MRID 43650001)
to > 0.23 Ib ae/A (triclopyr TEA, formulated, MRID 43129801). The most sensitive
parameter for the alfalfa seedling emergence study is percent emergence (MRID
43650001), and the most sensitive parameter for the soybean seedling emergence study is
shoot length (MRID 43129801). For the seedling emergence studies the most sensitive
monocot species is the onion for triclopyr BEE, and barley for triclopyr TEA, with EC2s's
that range from 0.053 Ib ae/A (triclopyr BEE, formulated MRID 43650001) to > 0.23 Ib
ae/A (triclopyr TEA, formulated, MRID 43129801). The most sensitive parameter for
the onion seedling emergence study is shoot weight (MRID 43650001), and the most
sensitive parameter for the barley seedling emergence study is shoot length (MRID
43129801).
The results of the Tier II seedling emergence and vegetative vigor toxicity tests on non-
target plants are summarized below in Table 4-5.
Table 4-5 Non-target Terrestrial Plant Seedling Emergence and Vegetative Vigor
Toxicity (Tier II) Data
Crop
Dicot
Monocot
Species
Seedling Emergence
Alfalfa
(Medicago saliva)
Vegetative Vigor
Sunflower
(Helianthus annus)
Seedling Emergence
Onion (Allium cepa)
Vegetative Vigor
Onion (Allium cepa)
Toxicity Value Used in
Risk Assessment
(expressed as ae)
EC25 = 0.045 Ib ae/A
NOAEC = 0.0026 Ib ae/A
(BEE)
EC25 = 0.005 Ib ae/A
NOAEC = 0.0028 Ib ae/A
(TEA)
EC25 = 0.053 Ib ae/A
NOAEC = 0.0021 Ib ae/A
(BEE)
EC25 = 0.063 Ib ae/A
NOAEC < 0.063 Ib ae/A
(BEE)
Most
sensitive
parameter
emergence
shoot length
shoot weight
shoot weight
Slope
NA.
N.A.
N.A.
0.705
Citation
MRID#
(Author & Date)
43650001
Schwab 1995
43129801
Schwab 1993
43650001
Schwab 1995
43650001
Schwab 1995
Comment
Acceptable
Acceptable
Acceptable
Acceptable
N.A., Not Available
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4.3 Use of Probit Slope Response Relationship to Provide Information on the
Endangered Species Levels of Concern
The Agency uses the probit dose response relationship as a tool for providing additional
information on the potential for acute direct effects to individual listed species and
aquatic animals that may indirectly affect the listed species of concern (U.S. EPA 2004).
As part of the risk characterization, an interpretation of acute RQ for listed species is
discussed. This interpretation is presented in terms of the chance of an individual event
(i.e., mortality or immobilization) should exposure at the EEC actually occur for a species
with sensitivity to triclopyr on par with the acute toxicity endpoint selected for RQ
calculation. To accomplish this interpretation, the Agency uses the slope of the dose
response relationship available from the toxicity study used to establish the acute toxicity
measures of effect for each taxonomic group that is relevant to this assessment. The
individual effects probability associated with the acute RQ is based on the mean estimate
of the slope and an assumption of a probit dose response relationship. In addition to a
single effects probability estimate based on the mean, upper and lower estimates of the
effects probability are also provided to account for variance in the slope, if available.
Individual effect probabilities are calculated based on an Excel spreadsheet tool IECV1.1
(Individual Effect Chance Model Version 1.1) developed by the U.S. EPA, OPP,
Environmental Fate and Effects Division (June 22, 2004). The model allows for such
calculations by entering the mean slope estimate (and the 95% confidence bounds of that
estimate) as the slope parameter for the spreadsheet. In addition, the acute RQ is entered
as the desired threshold.
A probit slope value for acute freshwater fish, freshwater invertebrate, and avian toxicity
tests are not available; therefore, the effect probability is calculated based on a default
slope assumption of 4.5 with upper and lower 95% confidence intervals of 2 and 9
(Urban and Cook, 1986).
4.4 Incident Database Review
A review of the EIIS for ecological incidents involving triclopyr (the acid, TEA and BEE
forms) was completed on August 25, 2009. The results of this review for terrestrial,
plant, and aquatic incidents are discussed below in Sections 4.4.1 through 4.4.3,
respectively. A complete list of the incidents involving triclopyr including associated
uncertainties is included as Appendix O.
Of the total of 63 incidents listed for triclopyr, 43 were listed under triclopyr acid (PC
code 116001), 13 incidents listed for triclopyr TEA (PC code 116002), and 7 incidents
listed for triclopyr BEE (PC code 116004). Of the 43 incidents listed for triclopyr acid
(PC code 116001), under further examination it was determined that 25 of those involved
triclopyr TEA formulation (1 aquatic and 24 plant incidents), 9 involved triclopyr BEE
formulation (1 aquatic and 8 plant incidents) and the remaining 9 incidents (1 aquatic,
and 8 plant incidents) were unable to be further classified into formulation.
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4.4.1 Terrestrial Incidents
No terrestrial incidents were reported within the EIIS database for triclopyr, triclopyr
TEA or triclopyr BEE.
4.4.2 Plant Incidents
From a total of 41 plant incidents listed for triclopyr (PC code 116001), 8 were not able
to be classified into the formulation of triclopyr (TEA or BEE) (1014409-009,1007875-
001,1007834-039,1003377-027,1014404-019,1014404-018,1013883-026 and 1012786-
005).
Two incidents were the result of the registered use of triclopyr (1014409-009 and
1007875-001). One incident was in Washington, and although the use was not reported, it
was likely residential. Triclopyr was listed as a possible cause, since it was alleged that
Glyphosate, 2,4-D and triclopyr drifted in to a garden, and the drift/over spray was
confirmed by lab results. However, no analysis was submitted, and the state sent a
warning letter regarding the incident (1014409-009). The other incident involved the
registered use of triclopyr on pastures in Wisconsin (1007875-001). Garden and
ornamental plants of homes bordering 55 treated acres allegedly were injured by drift
(physical) and drift due to volatilization of triclopyr. The pesticides involved included
triclopyr and 2,4-D which are both active ingredients in the product Crossbow (in both
TEA and BEE formulations), therefore they were both classified as the probable cause of
the incident.
Two incidents were the result of accidental misuse of triclopyr for the municipal
operation and railroad right-of-way uses (1007834-039 and 1003377-027). Triclopyr was
listed as the probable cause of the incident in which $500,000 damage was sustained to
grape vineyards after Garlon application to weeds alongside Highway 111 in CA
(accidental misuse of a municipal operation use), adjacent to the vineyards (1007834-
039). The accidental misuse of triclopyr on a railroad right-of-way, in CA resulted in an
incident in which owners of grapevines adjacent to the railroad noted damage to their
crops (1003377-027). Almonds also were documented as having plant damage, as a
result of triclopyr residues being detected on the plants, triclopyr was classified as being
the highly probable cause of the incident (1003377-027).
In the misuse incident of triclopyr in Washington during fencerow application within a
residential area, triclopyr and 2,4-D were likely the probable cause of dying shrubs in an
adjacent yard. Exposure potentially occurred as a result of spray drift (1014404-019).
Three incidents of undetermined legality (two in Washington and one in France) resulted
in damage to non-target trees including ornamentals, cypress and poplars (1014404-018,
1013883-026 and 1012786-005). One of the Washington incidents alleges that triclopyr
may be the possible cause of damage to poplar trees and other ornamentals in a
residential yard, however, it is not clear whether this was a direct application or as the
result of spray drift of the pesticide (1014404-018). The other Washington incident found
that triclopyr may be the highly probable cause of dying cypress tress along a fence-line
as residues of triclopyr and 2,4-D were found within the plants (1013883-026). The other
incident of undetermined legality occurred in France, and found that Garlon D 12
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(triclopyr and 2,4-D) were the possible cause of 10 damaged ornamental trees where the
symptoms were listed as "phytotoxic" (1012786-005).
Incidents identified under triclopyr (PC code 116001), and further classified as being
triclopyr TEA includes 24 incidents to plants (1003147-001,1006846-003,1006846-002,
1006846-001,1004846-001,1008639-001,1007340-707,1002507-001,1008571-027,
1009262-093,1009262-094,1008003-001,1008188-001,1008188-003,1008188-002,
1009513-001,1008884-001,1009969-006,1009513-002,1009513-003,1012366-048,
1016962-005,1015748-035, and 1006871-001). There were a total of 16 incidents
resulting in damage to rice from registered applications of triclopyr TEA to agricultural
areas or to rice. From the registered applications of triclopyr TEA (Grandstand R) on
agricultural areas, four incidents resulted in a reduced yield of the rice, which listed
triclopyr TEA as the probable cause of the incident in TX and AR (1003147-001,
1006846-003,1006846-002, and 1006846-001). A total of 12 incidents from the
registered use of triclopyr TEA (Grandstand R) on rice resulted in alleged damage to the
crop (1004846-001,1008639-001,1008003-001,1008188-001,1008188-003,1008188-
002,1009513-001,1009969-006,1009513-002,1009513-003,1016962-005, and 1015748-
035). The likelihood of triclopyr TEA being responsible for the damage seen to the rice
crops varied from being the possible (1008639-001,1008003-001,1008188-001,1008188-
003,1008188-002,1016962-005, and 1015748-035) to the probable cause (1004846-001,
1009513-001,1009969-006,1009513-002, and 1009513-003). For triclopyr use on rice
damage and symptoms of the rice crop included twisting and knotting up in the rice
(1004846-001), overall crop injury and decreased yield (1008639-001,1008188-002,
1016962-005,1015748-035), root fish-hooking and dead tellers, with a decreased yield
(1008003-001), root twisting and color change (1008188-001), color change alone
(1008188-003), fish-hooking on roots, aborted tillers, and reduced stand (1009513-001),
twisted roots and tillers falling off (1009513-002), visible tip burn and damage to the rice
tillers (1009513-003), and other symptoms included rice tip burn, aerial roots, crooked
neck on roots (1009969-006). The other two incidents which resulted in damage to rice
included accidental misuse of triclopyr on rice, in which spray drift resulted in 124 acres
of trees affected (1008884-001), and one of undetermined legality of triclopyr use on rice
where the rice crop was damaged, tip burn was visible after 10 days application
(1012366-048).
The registered home use of triclopyr TEA (as Garlon 3 A) was a probable cause of injury
seen on a cotton field that neighbored the application use site, as drift likely occurred
when the product was sprayed along the fence line (1002507-001). The registered
home/lawn use of triclopyr TEA (as Weed-B-Gon), was a probable cause of two
incidents that resulted in damage to lawns after treatment with the product (1009262-093
and 1009262-094). Accidental misuse of triclopyr TEA as Brush-B-Gon (home/lawn
use), was identified as the probable cause of damage to an entire St. Augustine lawn, as
the lawn was sprayed directly to control weeds which was against stated label language
(1008571-027). Accidental right-of-way misuse of triclopyr TEA (as Garlon 3 A),
formulated in a mixture with Tordon (Picloram) was applied to an electric power line
right-of-way, a rain event (1.5 inches) occurred the next evening moving product (via
runoff) into an adjacent soybeans field which resulted in cupped leaves and absent plants
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(1006871-001). The undetermined agricultural area use of triclopyr TEA was the
possible cause of damage seen to ornamentals that were treated directly with Ortho
Brush-B-Gon (1007340-707).
Incidents identified under triclopyr (PC code 116001), and further classified as being
triclopyr BEE includes 8 incidents to plants (1004712-001,1004721-001,1003581-001,
1015921-002,1001944-001,1005413-001,1008077-001, and 1005082-001). The
registered right-of-way use of triclopyr BEE (as Garlon 4) near a planted field was the
probable cause of tomato crop growth regulatory type injury and damage seen in FL
(1004712-001 and 1004721-001). The registered pasture use of triclopyr BEE was a
possible cause of alleged damage to a vineyard (over a three-year period) (1008077-001).
The damage reported to the vines included severe stunting, death of shoot tios and entire
shoots which resulted in low fruit, shot berries, withering and dead clusters and loss of
crop yield (grapes), and budding grape plants (1008077-001). Accidental misuse of
triclopyr BEE (as Garlon 4) on an agricultural area (pastureland) next to a vineyard, was
the probable cause of brown/dead leaves, decreased growth and several dead vines,
approximately 21 rows of grapevines were affected via spray drift (1003581-001).
Another accidental misuse of triclopyr BEE (Garlon 4) in combination with Tordon K
(Picloram) on a right-of-way in OK with a wind speed between 10-16.1 mph, was the
possible cause of damage to hundreds of trees (including oak, walnut, hickory, pecan,
sassafras, redbud, dogwood, black cherry, Chinese chestnut, apple, pear, and sycamore)
in a neighboring property (1001944-001). However, the Oklahoma State Department of
Agriculture investigated the incident, and found no herbicidal effect to the trees
(1001944-001). An accidental road right-of-way misuse was the probable cause of
damage to several wine grape fields that were adjacent to the application site (1005413-
001). The day of application the weather was windy, and the potential for spray drift
increased. The accidental misuse of triclopyr BEE in a rose tree nursery was the probable
cause of damage to roses seen after a malfunction occurred with the equipment used for
pesticide application (1005082-001). An undetermined legality use of triclopyr BEE on
an agricultural area was a possible cause of the mortality seen in hundreds of trees from
overspray of products (Spike 20P, Remedy, and Grazon P+D Herbicide), the chemicals
suspected include Picloram, 2,4-D, Triisopropylamine, Tebuthiuron and triclopyr BEE
(1015921-002). In addition to the deaths of the trees, the plaintiff alleges that the
contamination of the land and water resources have diminished the property's use for deer
hunting and fishing (1015921-002).
There were a total of 13 plant incidents listed for triclopyr TEA (PC code 116002), and
included 1012701-001,1010624-001,1010927-035,1010927-036,1010927-037,1010927-
038,1010927-039,1013636-030,1013550-006,1016962-008,1016962-043,1016680-001,
and 1017837-003. The registered rangeland use of triclopyr TEA was a possible cause of
damage seen to potatoes and tomatoes, as compost that was distributed by Washington
State University, was found to contain TORDON 22X an herbicide that was used on
fields where the hay was harvested to feed cattle (1010624-001). The concentration
found in the home gardens was of the order of 0.01 ppb Picloram, however triclopyr TEA
was also listed as a possible cause in the product Confront in which triclopyr TEA is
mixed with Clopyralid (1010624-001). The registered use of triclopyr TEA (Grandstand)
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on rice was the probable cause of damage seen to rice crop in three incidents (1010927-
035,1010927-036 and 1010927-037), and possible cause of damage to rice in one incident
(1013636-030). Damage to rice included tip burn, yellowing and white-spots, burned
down tillers and necrotic spots on the leaf were observed (1010927-035), burn on the rice
shortly after application (1010927-036), and low yield and dead plants (1010927-037).
The registered use of triclopyr TEA to rice, broadleaf weeds, and curly indigo was used
in combination with Stam M-4 (Propanil), and was the possible cause of injury (tillers
erupting from the stalk), and a decreased yield of rice (1016962-043). The registered
right-of-way use of triclopyr TEA (Garlon 3 A) and DMA 4 (2,4-D) were a possible cause
of mortality seen in nursery trees and greenhouse annuals, Leaf tissue samples of tree
showed 0.017 ppm of 2-4-D but no detectable triclopyr (1017837-003). The accidental
misuse of triclopyr TEA associated with application to rice was the probable cause of
damage to rice, as application of triclopyr TEA occurred earlier than label
recommendations (15 days apart instead of 20,1010927-038) or late in the season
(1010927-039) which resulted in damage to the rice crop. Accidental misuse of triclopyr
associated with its use on rice was the probable cause of damage to part of an alfalfa field
from spray drift during aerial application to rice (1013550-006). Undetermined legality
of triclopyr TEA use on rice was the possible cause of "various damage" to the 2003 rice
crop experienced by a farming business in TX (1016962-008). The undetermined legality
of triclopyr TEA right-of-way use was the possible cause of 13 acres of vineyards
damaged as the result of overspray of a combination of chemicals including (triclopyr
TEA, Sulfometuron, 2,4-D, and Hexazinone, 1016680-001).
There were a total of 7 plant incidents listed for triclopyr BEE (PC code 116004), and
included: 1012209-003,1013550-004,1011622-003,1016940-015,1013645-010,1010927-
014, and 1013550-007. The registered use of triclopyr BEE on grass was the possible
cause of damage to 18 acres of Bermuda grass, however one month earlier 2,4-D was
applied with little success followed by Remedy (triclopyr BEE), therefore it was unclear
which chemical is responsible for the damage seen (1013550-004). The registered use of
triclopyr BEE on parks to control weeds was a probable cause of spray drift to a grape
vineyard, olive trees and ornamental plants, and resulted in the refusal of the grapes at a
winery as the pesticide was not approved for use on grapes (1016940-015). The product
label prohibits Garlon 4 from being sprayed as mists and prohibits permitting direct
contact with grapes, tobacco, vegetable crops, and broad leaf plants (1016940-015).
Registered use of triclopyr BEE on a tree farm/plantation was the probable cause f
damage seen to 1.5 acres of beans, 3 oak trees, and some grape vines, a result of probable
spray drift (1013550-007). Damage seen to the beans included chlorosis and cupping, the
grapes were chlorotic, and some of the oak leaves turned brown (1013550-007).
Accidental misuse of triclopyr BEE during municipal operation use was a probable cause
in damage to tomato plants adjacent to the application site as a result of probable drift
(1011622-003). The result was the cupping and curling of the plants, and the Court's
finding was in favor of the tomato farmer. Garlon and Remedy (triclopyr BEE) are
registered for a number of uses but they do not include tomatoes (1011622-003).
Accidental misuse of triclopyr BEE resulting from the use of improper equipment to
transfer the chemical from the sprayer (a rubber hose was used instead of plastic tubing, a
problem since Remedy (BEE) can penetrate the inner lining of rubber hosing), was a
86
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probable cause in mortality seen to soybeans after application of a different herbicide,
Round Up (1010927-014). Triclopyr BEE was applied to mesquite trees, and when the
operator transferred chemicals, it was not done the correct way (1010927-014). A Dow
submitted a letter, dated June 15, 2001 (identified as 1011622-001) but it had no
additional information. Misuse of triclopyr BEE that was used to control blackberries
was a probable cause in the crop loss and herbicide exposure symptoms seen in a grape
vineyard on a neighboring farm (1012209-003). Samples were taken from the vineyard
and found positive, indicating that some of the pesticides had drifted onto the grape vines
causing damage valued at $84,380 (1012209-003). The misuse of triclopyr BEE (as
GARLON 4) from application to a road right-of-way, and was the probable cause of
severe damage sustained by two vineyards (1013645-010). Both soil and foliage samples,
were then collected (although no data was supplied) and the ensuing analyses established
that GARLON 4 had drifted onto the vineyards and was responsible for the damage that
had been sustained (1013645-010).
4.4.3 Aquatic Incidents
There were a total of three reported aquatic incidents under triclopyr (PC code 116001).
Two were further classified, one as triclopyr TEA (1008883-001) and the other as
triclopyr BEE (1005004-001), while the third could not be further (1000925-001). For
triclopyr TEA an incident of undetermined legality occurred in LA where triclopyr was
classified as the possible cause of an allegation that 45,000 pounds of catfish had been
destroyed in a catfish farm after an adjacent rice field had been sprayed with Grandstand
R (triclopyr TEA) with Stam M-4 (Propanil) at the rate of 3.0 Ibs/gallon (1008883-001).
The manager of the catfish farm contends that the spray drift of Grandstand R had killed
the fish as the consequence of oxygen starvation, a distance of 70 ft (1008883-001).
There were no analyses made to support the allegation which is presumed to have been
based on the herbicidal action of Grandstand R that might kill the plankton in the fish
pond (1008883-001). The second reported aquatic incident involves the accidental
misuse of triclopyr BEE, in AR. It was reported that aerial drift of Garlon 4 (triclopyr
BEE) contaminated an adjacent pond which resulted in damage to some aquatic
vegetation (1005004-001). Triclopyr is listed as a probable cause of this incident. The
third reported aquatic incident from the registered use of triclopyr on railroad right-of
way likely resulted in a fish kill of approximately 23000 fish below a railroad crossing
and above a low retention dam on Blueston River, WV (1000925-001). The suspected
route of exposure was via spray drift, and in addition to triclopyr, 2,4-D was also listed in
the report as being a highly probable cause for incident.
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5.0 Risk Characterization
Risk characterization is the integration of the exposure and effects characterizations.
Risk characterization is used to determine the potential for direct and/or indirect effects to
the CRLF or for modification to its designated critical habitat from the use of triclopyr in
CA. The risk characterization provides an estimation (Section 5.1) and a description
(Section 5.2) of the likelihood of adverse effects; articulates risk assessment assumptions,
limitations, and uncertainties; and synthesizes an overall conclusion regarding the
likelihood of adverse effects to the CRLF or its designated critical habitat (i.e., "no
effect," "likely to adversely affect," or "may affect, but not likely to adversely affect").
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 pre-established acute and chronic levels of
concern (LOCs) for each category evaluated (Appendix C). For acute exposures to the
CRLF and its animal prey in aquatic habitats, as well as terrestrial invertebrates, the LOG
is 0.05. For acute exposures to the terrestrial CRLF and mammals, the LOG is 0.1. The
LOG for chronic exposures to CRLF and its prey, as well as acute exposures to plants is
1.0.
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 triclopyr usage
scenarios summarized in Table 3-3 and the appropriate aquatic toxicity endpoint from
Table 4-1. 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 triclopyr (Table 3-5 and Table 3-7) and the appropriate toxicity endpoint
from Table 4-3. Exposures are also derived for terrestrial plants, as discussed in Section
3.4 and toxicity summarized in Section 4.2.4, based on the highest application rates of
triclopyr use within the action area.
5.1.1 Exposures in the Aquatic Habitat
5.1.1.1 Direct Effects to Aquatic-Phase CRLF
Direct effects to the aquatic-phase CRLF are based on peak EECs in the standard pond
and the lowest acute toxicity value for freshwater fish. In order to assess direct chronic
risks to the CRLF, 60-day EECs and the lowest chronic toxicity value for freshwater fish
are used. The resulting RQs for the majority of triclopyr uses exceed the Agency's acute
and chronic LOC's (0.05 and 1.0) for freshwater fish (surrogates for the aquatic-phase
CRLF) (Table 5-1). The acute RQs exceed the Agency's LOC for listed species (0.05),
and range from 9.62 (Lakes/ponds/reservoirs) to 0.02 (ornamental lawns and turf) (Table
5-1). A probit slope value for the bluegill sunfish acute toxicity test is not available
therefore; the probability of individual effect was estimated based on the default slope of
4.5. The estimated probability of an individual effect from triclopyr use at the
endangered species LOC (0.05) ranges from 1 in 1 with a 95% CI of 1 in 1 to 1 in 1 for
88
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lakes/ponds/reservoirs to 1 in 2.51 x 106 with a 95% CI of 1 in 70.8to 1 in 3.64 x 1022 for
ornamental sod farm (turf) for acute aquatic-phase amphibian RQs. The estimated
probability of individual effect of triclopyr ranges from approximately 100%
(lakes/ponds/reservoirs) to 3.98 x 105 % (ornamental sod farm-turf). The chronic RQs
exceed the Agency's LOG (1.0), and range from 131.58 (Lakes/ponds/reservoirs) to 0.21
(ornamental lawns and turf) (Table 5-1). Results are presented in Table 5-1. An example
PRZM/EXAM and Rice model output are available in Appendix K and J, respectively.
Based on the potential for both acute and chronic effects (Table 5-1) triclopyr may
directly affect the aquatic-phase of the CRLF.
Table 5-1 Summary of Direct Effect RQs for the Aquatic-phase CRLF
Use
DOUGLAS-FIR (FOREST/SHELTERBELT)
CONIFER RELEASE
CHRISTMAS TREE PLANTATIONS, CONIFER
RELEASE, FOREST TREES (ALL OR
UNSPECIFIED), FOREST TREE
MANAGEMENT/FOREST PEST
MANAGEMENT
CHRISTMAS TREE PLANTATIONS, FOREST
TREES (ALL OR UNSPECIFIED), CONIFER
RELEASE
FOREST TREE MANAGEMENT/FOREST PEST
MANAGEMENT, FOREST TREES (ALL OR
UNSPECIFIED)
ORCHARDS (non-food stump treatment)
AIRPORTS/LANDING FIELDS,
COMMERCIAL/INSTITUTIONAL/INDUSTRIAL
PREMISES/EQUIPMENT (OUTDOOR)
PAVED AREAS (PRIVATE
ROADS/SIDEWALKS), DRAINAGE SYSTEMS,
INDUSTRIAL AREAS (OUTDOOR),
NONAGRICULTURAL RIGHTS-OF-
WAY/FENCEROWS/HEDGEROWS
COMMERCIAL STORAGES/WAREHOUSES
PREMISES, PAVED AREAS (PRIVATE
ROADS/SIDEWALKS), DRAINAGE SYSTEMS,
INDUSTRIAL AREAS (OUTDOOR)
AGRICULTURAL RIGHTS-OF-
WAY/FENCEROWS/HEDGEROWS
NONAGRICULTURAL RIGHTS-OF-
WAY/FENCEROWS/HEDGEROWS
ORNAMENTAL HERBACEOUS PLANTS,
ORNAMENTAL NONFLOWERING PLANTS
ORNAMENTAL AND/OR SHADE TREES,
ORNAMENTAL WOODY SHRUBS AND VINES
Peak
EEC
(Hg/L)b
44.02
127.70
194.70
534.60
337.90
148.40
3479.00
1363.00
5802.00
250.06
1319.20
2929.60
34.04
415.30
60-Day
EEC
(Hg/L)b
35.50
107.60
136.90
426.30
286.00
109.68
2864.00
1006.50
4770.00
190.69
1098.53
2442.28
23.95
308.50
Direct
Acute
RQ
0.17
0.49
0.75
2.06
1.30
0.57
13.38
5.24
22.32
0.96
5.07
11.27
0.13
1.60
Probability of Individual
Effect at
RQC
1 in 3.74 x 103
(1 in 16.2 to 1 in 4.62 x 1011)
26.7%
1 in 12.2
(1 in 3.73 to 1 in 377)
8.2%
1 in 3.48
(1 in 2.49 to 1 in 7.67)
28.7%
1 in 1.09
(1 in 1.36 to 1 in 1)
91.7%
1 in 1.44
(1 in 1.69 to 1 in 1.18)
69.4%
1 in 7.35
(1 in 3.20 to 1 in 71.4)
13.6%
1 in 1
(1 in 1.01 to 1 in 1)
100%
1 in 1
(1 in 1.08 to 1 in 1)
100%
1 in 1
(1 in 1 to 1 in 1) 100%
1 in 2. 14
(1 in 2.06 to 1 in 2.29)
46.7%
1 in 1
(1 in 1.09 to 1 in 1)
100%
1 in 1
(1 in 1.02 to 1 in 1)
100%
1 in 2.99 x 104
(1 in 26.2 to 1 in 1.31 x 1015 )
0.003%
1 in 1.22
(1 in 1.52 to 1 in 1.03)
82.0%
Direct
Chronic
RQ
1.87
5.66
7.21
22.44
15.05
5.77
150.74
52.97
251.05
10.04
57.82
128.54
1.26
16.24
89
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Use
AGRICULTURAL/FARM
STRUCTURES/BUILDINGS AND EQUIPMENT
AGRICULTURAL/FARM PREMISES
AGRICULTURAL FALLOW/IDLELAND,
NONAGRICULTURAL UNCULTIVATED
AREAS/SOILS
AGRICULTURAL FALLOW/IDLELAND
AGRICULTURAL/FARM PREMISES
AGRICULTURAL/FARM
STRUCTURES/BUILDINGS AND EQUIPMENT,
AGRICULTURAL UNCULTIVATED AREAS,
NONAGRICULTURAL UNCULTIVATED
AREAS/SOILS
PASTURES, RANGELAND
RECREATION AREA LAWNS, RESIDENTIAL
LAWNS
RESIDENTIAL LAWNS
HOUSEHOLD/DOMESTIC DWELLINGS
OUTDOOR PREMISES, RECREATION AREA
LAWNS
ORNAMENTAL LAWNS AND TURF
COMMERCIAL/INDUSTRIAL LAWNS,
ORNAMENTAL LAWNS AND TURF
ORNAMENTAL SOD FARM (TURF)
COMMERCIAL/INDUSTRIAL LAWNS
ORNAMENTAL SOD FARM (TURF)
GOLF COURSE TURF
RICE
Peak
EEC
(Hg/L)b
382.60
77.28
103.14
87.78
64.62
990.20
990.20
32.91
394.80
75.02
415.02
1499.38
5.26
34.65
20.80
124.83
165.10
270.00
763.00
763.00
60-Day
EEC
(Hg/L)b
268.70
65.05
87.12
66.49
49.93
793.90
793.90
24.93
321.90
61.68
309.03
1171.65
4.04
28.60
15.69
94.34
133.80
219.50
763.00
763.00
Direct
Acute
RQ
1.47
0.30
0.40
0.34
0.25
3.81
3.81
0.13
1.52
0.29
1.60
5.77
0.02
0.13
0.08
0.48
0.64
1.04
2.93
2.93
Probability of Individual
Effect at
RQC
1 in 1.29
(1 in 1.58 to 1 in 1.07)
77.5%
1 in 107
(1 in 6.76 to 1 in 7.91 x 105)
0.93%
1 in 27.3
(1 in 4.69 to 1 in 5.83 x 103)
3.66%
1 in 57.1
(1 in 5.73 to 1 in 8.07 x 104)
1.75%
1 in 297
(1 in 8.75 to 1 in 3.33 x 107)
0.34%
1 in 1
(1 in 1.14 to 1 in 1)
100%
1 in 1
(1 in 1.14 to 1 in 1)
100%
1 in 2.99 x 104
(1 in 26.2 to 1 in 1.31 x 1015)
33.4%
1 in 1.26
(1 in 1.56 to 1 in 1.05)
79.4%
1 in 129
(1 in 7.09 to 1 in 1.53 x 106)
77.5%
1 in 1.22
(1 in 1.562 to 1 in 1.03)
82.0%
1 in 1
(1 in 1.07 to 1 in 1)
100%
No Exceedance
1 in 2.99 x 104
(1 in 26.2 to 1 in 1.31 x 1015 )
33.4%
Iin2.51xl06
(1 in 70.8 to 1 in 3.64 x 1022)
3.98xl05%
1 in 13.2
(1 in3.82tol in 485)
7.58%
1 in 5.22
(1 in 2.86 to 1 in 24.7)
19.2%
1 in 1.88
(1 in 1.95 to 1 in 1.78)
53.2%
1 in 1.29
(1 in 1.58 to 1 in 1.07)
77.5%
1 in 1.29
(1 in 1.58 to 1 in 1.07)
77.5%
Direct
Chronic
RQ
14.14
3.42
4.59
3.50
2.63
41.78
41.78
1.31
16.94
3.25
16.26
61.67
0.21
1.51
0.83
4.97
7.04
11.55
40.16
40.16
90
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Use
AQUATIC AREAS/WATER, INTERMITTENTLY
FLOODED AREAS/WATER,
LAKES/PONDS/RESERVOIRS (WITH HUMAN
OR WILDLIFE USE)
AQUATIC AREAS/WATER, INTERMITTENTLY
FLOODED AREAS/WATER
SWAMPS/MARSHES/WETLANDS/STAGNANT
WATER
LAKES/PONDS/RESERVOIRS (WITH HUMAN
OR WILDLIFE USE),
SWAMPS/MARSHES/WETLANDS/STAGNANT
WATER
Peak
EEC
(Hg/L)b
2500.00
2500.00
2500.00
2500.00
60-Day
EEC
(Hg/L)b
2500.00
2500.00
2500.00
2500.00
Direct
Acute
RQ
9.62
9.62
9.62
9.62
Probability of Individual
Effect at
RQC
1 in 1
(1 in 1 to 1 in 1)
100%
1 in 1
(1 in 1 to 1 in 1)
100%
1 in 1
(1 in 1 to 1 in 1)
100%
1 in 1
(1 in 1 to 1 in 1)
100%
Direct
Chronic
RQ
131.58
131.58
131.58
131.58
a RQs associated with acute direct toxicity to the CRLF are also used to assess potential indirect effects to the CRLF based on a
reduction in freshwater fish and frogs as food items.
b The highest EEC based on maximum application rate per use (see Table 3-3).
0 A probit slope value for the acute blue-gill sunfish toxicity test is not available; therefore, the effect probability was calculated
based on a default slope assumption of 4.5 with upper and lower 95% confidence intervals of 2 and 9 (Urban and Cook, 1986).
RQ < acute endangered species LOG of 0.05.
A The most sensitive species used to determine the acute direct effects (surrogate species) was the Bluegill Sunfish (96h LC50 = 260
ppb). The most sensitive species used to determine the chronic direct effects (surrogate species) was the Rainbow Trout (NOAEC
= 19 ppb).
5.1.1.2 Indirect Effects to Aquatic-Phase CRLF via Reduction in Prey (non-
vascular aquatic plants, aquatic invertebrates, fish, and frogs)
a) Non-vascular Aquatic Plants
Indirect effects of triclopyr to the aquatic-phase CRLF (tadpoles) via reduction in non-
vascular aquatic plants in its diet are based on peak EECs from the standard pond and the
lowest toxicity value (EC50) for aquatic non-vascular plants. The Agency's risk to
aquatic plants LOG (1.0) is exceeded for numerous uses of triclopyr. The aquatic non-
vascular plant RQs range from 35.71 (lakes/ponds/reservoirs) to 0.08 (ornamental lawns
and turf). Results are presented in Table 5-2. An example PRZM/EXAM and Rice
model output are available in Appendix K and J, respectively. Based on the aquatic
non-vascular plant LOC exceedances, triclopyr may indirectly affect the CRLF via
reduction in non-vascular plants as food items.
Table 5-2 Summary of RQs Used to Estimate Indirect Effects to the CRLF via
Effects to Non-Vascular Aquatic Plants (diet of CRLF in tadpole life stage and
habitat of aquatic-phase CRLF)
Use
DOUGLAS-FIR (FOREST/SHELTERBELT)
CONIFER RELEASE
CHRISTMAS TREE PLANTATIONS, CONIFER RELEASE, FOREST TREES
(ALL OR UNSPECIFIED), FOREST TREE MANAGEMENT/FOREST PEST
MANAGEMENT
CHRISTMAS TREE PLANTATIONS, FOREST TREES (ALL OR
UNSPECIFIED), CONIFER RELEASE
FOREST TREE MANAGEMENT/FOREST PEST MANAGEMENT, FOREST
TREES (ALL OR UNSPECIFIED)
ORCHARDS (non-food stump treatment)
EEC (ng/L)b
44.02
127.70
194.70
534.60
337.90
148.40
RQ
0.63
1.82
2.78
7.64
4.83
2.12
91
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Use
AIRPORTS/LANDING FIELDS,
COMMERCIAL/INSTITUTIONAL/INDUSTRIAL PREMISES/EQUIPMENT
(OUTDOOR)
PAVED AREAS (PRIVATE ROADS/SIDEWALKS), DRAINAGE SYSTEMS,
INDUSTRIAL AREAS (OUTDOOR), NONAGRICULTURAL RIGHTS-OF-
WAY/FENCEROWS/HEDGEROWS
COMMERCIAL STORAGES/WAREHOUSES PREMISES, PAVED AREAS
(PRIVATE ROADS/SIDEWALKS), DRAINAGE SYSTEMS, INDUSTRIAL
AREAS (OUTDOOR)
AGRICULTURAL RIGHTS-OF-WAY/FENCEROWS/HEDGEROWS
NONAGRICULTURAL RIGHTS-OF-WAY/FENCEROWS/HEDGEROWS
ORNAMENTAL HERBACEOUS PLANTS, ORNAMENTAL
NONFLOWERING PLANTS
ORNAMENTAL AND/OR SHADE TREES, ORNAMENTAL WOODY
SHRUBS AND VINES
AGRICULTURAL/FARM STRUCTURES/BUILDINGS AND EQUIPMENT
AGRICULTURAL/FARM PREMISES
AGRICULTURAL FALLOW/IDLELAND, NONAGRICULTURAL
UNCULTIVATED AREAS/SOILS
AGRICULTURAL FALLOW/IDLELAND
AGRICULTURAL/FARM PREMISES
AGRICULTURAL/FARM STRUCTURES/BUILDINGS AND EQUIPMENT,
AGRICULTURAL UNCULTIVATED AREAS, NONAGRICULTURAL
UNCULTIVATED AREAS/SOILS
PASTURES, RANGELAND
RECREATION AREA LAWNS, RESIDENTIAL LAWNS
RESIDENTIAL LAWNS
HOUSEHOLD/DOMESTIC DWELLINGS OUTDOOR PREMISES,
RECREATION AREA LAWNS
ORNAMENTAL LAWNS AND TURF
COMMERCIAL/INDUSTRIAL LAWNS, ORNAMENTAL LAWNS AND
TURF
ORNAMENTAL SOD FARM (TURF)
COMMERCIAL/INDUSTRIAL LAWNS
ORNAMENTAL SOD FARM (TURF)
GOLF COURSE TURF
RICE
AQUATIC AREAS/WATER, INTERMITTENTLY FLOODED
AREAS/WATER, LAKES/PONDS/RESERVOIRS (WITH HUMAN OR
WILDLIFE USE)
AQUATIC AREAS/WATER, INTERMITTENTLY FLOODED
AREAS/WATER
SWAMPS/MARSHES/WETLANDS/STAGNANT WATER
LAKES/PONDS/RESERVOIRS (WITH HUMAN OR WILDLIFE USE),
SWAMPS/MARSHES/WETLANDS/STAGNANT WATER
EEC (ng/L)b
3479.00
1363.00
5802.00
250.06
1319.20
2929.60
34.04
415.30
382.60
77.28
103.14
87.78
64.62
990.20
990.20
32.91
394.80
75.02
415.02
1499.38
5.26
34.65
20.80
124.83
165.10
270.00
763.00
763.00
2500.00
2500.00
2500.00
2500.00
RQ
49.70
19.47
82.89
3.57
18.85
41.85
0.49
5.93
5.47
1.10
1.47
1.25
0.92
14.15
14.15
0.47
5.64
1.07
5.93
21.42
0.08
0.49
0.30
1.78
2.36
3.86
10.90
10.90
35.71
35.71
35.71
35.71
* LOG exceedances (RQ > 1) are bolded and shaded.
RQ = use-specific peak EEC/ [Navicula pelliculosa EC50 = 70 ppb].
b) Aquatic Invertebrates
Indirect acute effects to the aquatic-phase CRLF via effects to prey (invertebrates) in
aquatic habitats are based on peak EECs in the standard pond and the lowest acute
toxicity value for freshwater invertebrates. For chronic risks, 21-day EECs and the lowest
chronic toxicity value for invertebrates are used to derive RQs. Acute RQs exceed the
Agency's acute risk to listed species LOG (0.05) for freshwater invertebrates for a
majority of triclopyr uses (Table 5-3). The acute RQs exceed the Agency's LOG for
listed species (0.05), and range from 10.00 (Lakes/ponds/reservoirs) to 0.02 (ornamental
lawns and turf) (Table 5-3). A probit slope value for Daphnia magna acute toxicity test
92
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is not available, therefore, the probability of individual effect was estimated based on the
default slope of 4.5. The estimated probability of an individual effect from triclopyr use
at the endangered species LOG (0.05) ranges from 1 in 1 with a 95% CI of 1 in 1 to 1 in 1
for lakes/ponds/reservoirs to 1 in 2.51 x 106 with a 95% CI of 1 in 70.8to 1 in 3.64 x 1022
for ornamental sod farm (turf) for acute aquatic invertebrate RQs. The estimated
probability of individual effect of triclopyr ranges from approximately 100%
(lakes/ponds/reservoirs) to 3.98 x 105 % (ornamental sod farm-turf). Chronic RQs do not
exceed the Agency's chronic risk to species LOG (1.0) for freshwater invertebrates for
any triclopyr use (Table 5-3). The chronic RQs range from 0.10 (lakes/ponds/reservoirs)
to < 0.01 (ornamental lawns and turf). The Results are presented in Table 5-3.
A summary of the acute and chronic RQ values for exposure to aquatic invertebrates (as
prey items of aquatic-phase CRLFs) is provided in Table 5-3. Example PRZM/EXAM
and Rice model outputs are available in Appendix K and J, respectively. Based on acute
risk to listed species LOC exceedances for aquatic invertebrates, the probability of
effect, triclopyr may indirectly affect the CRLF via reduction in freshwater
invertebrates prey items.
Table 5-3 Summary of Acute and Chronic RQs Used to Estimate Indirect Effects to
the CRLF via Direct Effects on Aquatic Invertebrates as Dietary Food Items (prey
of CRLF juveniles and adults in aquatic habitats)
Use
DOUGLAS-FIR (FOREST/SHELTERBELT)
CONIFER RELEASE
CHRISTMAS TREE PLANTATIONS, CONIFER RELEASE,
FOREST TREES (ALL OR UNSPECIFIED), FOREST TREE
MANAGEMENT/FOREST PEST MANAGEMENT
CHRISTMAS TREE PLANTATIONS, FOREST TREES (ALL
OR UNSPECIFIED), CONIFER RELEASE
FOREST TREE MANAGEMENT/FOREST PEST
MANAGEMENT, FOREST TREES (ALL OR
UNSPECIFIED)
ORCHARDS (non-food stump treatment)
AIRPORTS/LANDING FIELDS,
COMMERCIAL/INSTITUTIONAL/INDUSTRIAL
PREMISES/EQUIPMENT (OUTDOOR)
PAVED AREAS (PRIVATE ROADS/SIDEWALKS),
DRAINAGE SYSTEMS, INDUSTRIAL AREAS (OUTDOOR),
NONAGRICULTURAL RIGHTS-OF-
WAY/FENCEROWS/HEDGEROWS
COMMERCIAL STORAGES/WAREHOUSES PREMISES,
PAVED AREAS (PRIVATE ROADS/SIDEWALKS),
DRAINAGE SYSTEMS, INDUSTRIAL AREAS (OUTDOOR)
AGRICULTURAL RIGHTS-OF-
WAY/FENCEROWS/HEDGEROWS
Peak
EEC
(Hg/L)
44.02
127.70
194.70
534.60
337.90
148.40
3479.00
1363.00
5802.00
250.06
21-Day
EEC
(Hg/L)
40.37
116.60
176.50
491.90
309.80
131.00
3141.00
1242.00
5244.00
226.89
Indirect
Acute
RQ
0.18
0.51
0.78
2.14
1.35
0.59
13.92
5.45
23.21
1.00
Probability of
Individual Effect at
RQC
1 in 2.49 x 103
(1 in 14.7 to 1 in 9.76 x 1010)
0.04%
1 in 10.6
(1 in 3. 58 to 1 in 2.36 x 102)
9.43%
1 in 3. 19
(1 in 2.41 to 1 in 6.03)
31.3%
lin 1.07 x 10J
(1 in 1.34 to 1 in 1)
93.5%
1 in 1.39
(1 in 1.66 to 1 in 1.14)
71.9%
1 in 6.61
(1 in 3.09 to 1 in 5 1.1)
15.1%
1 in 1
(1 in 1.01 to 1 in 1)
100%
1 in 1
(1 in 10.08 to 1 in 1)
100%
1 in 1
(1 in 1 to 1 in 1)
100%
lin 2
(1 in 2 to 1 in 2)
50%
Indirect
Chronic
RQ
<0.01
<0.01
0.01
0.02
0.01
0.01
0.13
0.05
0.21
0.01
93
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NONAGRICULTURAL RIGHTS-OF-
WAY/FENCEROWS/HEDGEROWS
ORNAMENTAL HERBACEOUS PLANTS, ORNAMENTAL
NONFLOWERING PLANTS
ORNAMENTAL AND/OR SHADE TREES, ORNAMENTAL
WOODY SHRUBS AND VINES
AGRICULTURAL/FARM STRUCTURES/BUILDINGS AND
EQUIPMENT
AGRICULTURAL/FARM PREMISES
AGRICULTURAL FALLOW/IDLELAND,
NONAGRICULTURAL UNCULTIVATED AREAS/SOILS
AGRICULTURAL FALLOW/IDLELAND
AGRICULTURAL/FARM PREMISES
AGRICULTURAL/FARM STRUCTURES/BUILDINGS AND
EQUIPMENT, AGRICULTURAL UNCULTIVATED AREAS,
NONAGRICULTURAL UNCULTIVATED AREAS/SOILS
PASTURES, RANGELAND
RECREATION AREA LAWNS, RESIDENTIAL LAWNS
RESIDENTIAL LAWNS
HOUSEHOLD/DOMESTIC DWELLINGS OUTDOOR
PREMISES, RECREATION AREA LAWNS
ORNAMENTAL LAWNS AND TURF
COMMERCIAL/INDUSTRIAL LAWNS, ORNAMENTAL
LAWNS AND TURF
ORNAMENTAL SOD FARM (TURF)
COMMERCIAL/INDUSTRIAL LAWNS
ORNAMENTAL SOD FARM (TURF)
GOLF COURSE TURF
1319.20
2929.60
34.04
415.30
382.60
77.28
103.14
87.78
64.62
990.20
990.20
32.91
394.80
75.02
415.02
1499.38
5.26
34.65
20.80
124.83
165.10
270.00
1200.17
2666.94
30.16
376.20
338.40
69.97
93.71
81.19
60.58
908.20
908.20
30.44
354.80
69.14
376.34
1317.17
4.74
31.70
18.87
113.10
154.60
245.90
5.28
11.72
0.14
1.66
1.53
0.31
0.41
0.35
0.26
3.96
3.96
0.13
1.58
0.30
1.66
6.00
0.02
0.14
0.08
0.50
0.66
1.08
1 in 1
(1 in 1.08 to 1 in 1)
100%
1 in 1
(1 in 1.02 to 1 in 1)
100%
lin 1.64 x 104
(1 in 22.8 to 1 in 1.3 Ix 1014)
0.006%
1 in 1.19
(1 in 1.49 tol in 1.02)
84.0%
1 in 1.25
(1 in 1.55 to 1 in 1.05)
80%
1 in 90.6
(1 in 6.47 to 1 in 4.26 x 105)
1.10%
1 in 24.6
(1 in 4.56 to 1 in 4.06 x 103)
4.07%
1 in 49.8
(1 in 5. 53 to 1 in 4.91 x 104)
2.01%
1 in 236
(1 in 8.27 to 1 in 1.43 x 107)
0.42%
1 in 1
(1 in 1.13 to 1 in 1)
100%
1 in 1
(1 in 1.13 to 1 in 1)
100%
1 in 2.99 x 104
(1 in 26.2 to 1 in 1.31 x 1015)
33.4%
1 in 1.23
(1 in 1.53 to 1 in 1.04)
81.3%
1 in 107
(1 in 6.76 to 1 in 7.91 x 105)
0.93%
1 in 1.19
(1 in 1.49 to 1 in 1.02)
84.0%
1 in 1
(1 in 1.06 to 1 in 1)
100%
No Exceedances
lin 1.64 xlO4
(1 in 22.8 to 1 in 1.31 x 1014)
61.0%
lin 2.51 xlO6
(1 in 70.8 to 1 in 3.64 x 1022)
3.98 x 105%
1 in 11.4
(1 in 3.66 to 1 in 2.97 x 102 )
8.77%
1 in 4. 80
(1 in 2.78 to 1 in 19.2)
20.8%
1 in 1.79
(1 in 1.90 to 1 in 1.62)
55.9%
0.05
0.11
<0.01
0.02
0.01
<0.01
<0.01
<0.01
<0.01
0.04
0.04
<0.01
0.01
<0.01
0.02
0.05
<0.01
<0.01
<0.01
<0.01
0.01
0.01
94
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RICE
AQUATIC AREAS/WATER, INTERMITTENTLY FLOODED
AREAS/WATER, LAKES/PONDS/RESERVOIRS (WITH
HUMAN OR WILDLIFE USE)
AQUATIC AREAS/WATER, INTERMITTENTLY FLOODED
AREAS/WATER
SWAMPS/MARSHES/WETLANDS/STAGNANT WATER
LAKES/PONDS/RESERVOIRS (WITH HUMAN OR
WILDLIFE USE),
SWAMPS/MARSHES/WETLANDS/STAGNANT WATER
763.00
763.00
2500.00
2500.00
2500.00
2500.00
763.00
763.00
2500.00
2500.00
2500.00
2500.00
3.05
3.05
10.00
10.00
10.00
10.00
1 in 1.25
(1 in 1.55 to 1 in 1.05)
80.0%
1 in 1.25
(1 in 1.55 to 1 in 1.05)
80.0%
1 in 1
(1 in 1 to 1 in 1)
100%
1 in 1
(1 in 1 to 1 in 1)
100%
1 in 1
(1 in 1 to 1 in 1)
100%
1 in 1
(1 in 1 to 1 in 1)
100%
0.03
0.03
0.10
0.10
0.10
0.10
* = LOG exceedances (acute RQ > 0.05; chronic RQ > 1.0) are bolded and shaded.
Acute RQ = use-specific peak EEC / [Daphnia Magna EC50 = 250 ppb].
Chronic RQ = use-specific 21 -day EEC / [Daphnia Magna NOAEC 25000 ppb].
c) Fish and Frogs
Fish and frogs also represent potential prey items of adult aquatic-phase CRLFs. RQs
associated with acute and chronic direct toxicity to the CRLF (Table 5-1) are used to
assess potential indirect effects to the CRLF based on a reduction in freshwater fish and
frogs as food items. The resulting RQs for the majority of triclopyr uses exceed the
Agency's acute and chronic LOC's (0.05 and 1.0) for freshwater fish (surrogates for the
aquatic-phase CRLF) (Table 5-1). The acute RQs exceed the Agency's LOG for listed
species (0.05), and range from 9.62 (Lakes/ponds/reservoirs) to 0.02 (ornamental lawns
and turf) (Table 5-1). The estimated probability of individual effect of triclopyr ranges
from approximately 100% (lakes/ponds/reservoirs) to 3.98 x 105% (ornamental sod farm-
turf), Table 5-1. The chronic RQs exceed the Agency's LOG (1.0), and range from
131.58 (Lakes/ponds/reservoirs) to 0.21 (ornamental lawns and turf), Table 5-1. Based
on the acute and chronic indirect effects, the probability of individual effect, and
effects to non-listed plant species which serve as habitat for freshwater fish and
frogs, triclopyr may indirectly affect the CRLF via reduction in freshwater fish and
frogs as food items.
5.1.1.3 Indirect Effects to CRLF via Reduction in Habitat and/or Primary
Productivity (Freshwater Aquatic Plants)
Indirect effects to the CRLF via direct toxicity to aquatic plants are estimated using the
most sensitive non-vascular and vascular plant toxicity endpoints. Because there are no
obligate relationships between the CRLF and any aquatic plant species, the most sensitive
EC50 values, rather than NOAEC values, were used to derive RQs. The Agency's risk to
vascular aquatic plants LOG (1.0) is exceeded for numerous uses of triclopyr. The
vascular aquatic plant RQs range from 2.91 (lakes/ponds/reservoirs) to 0.01 (ornamental
lawns and turf). Results are presented in Table 5-4. An example PRZM/EXAM and Rice
model output are available in Appendix K and J, respectively. Based on the aquatic
95
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plant LOC exceedances, triclopyr may indirectly affect the CRLF via reduction in
vascular aquatic plants.
Table 5-4 Summary of RQs Used to Estimate Indirect Effects to the CRLF via
Effects to Vascular Aquatic Plants (habitat of aquatic-phase CRLF)a
Use
DOUGLAS-FIR (FOREST/SHELTERBELT)
CONIFER RELEASE
CHRISTMAS TREE PLANTATIONS, CONIFER RELEASE, FOREST TREES (ALL OR
UNSPECIFIED), FOREST TREE MANAGEMENT/FOREST PEST MANAGEMENT
CHRISTMAS TREE PLANTATIONS, FOREST TREES (ALL OR UNSPECIFIED), CONIFER
RELEASE
FOREST TREE MANAGEMENT/FOREST PEST MANAGEMENT, FOREST TREES (ALL
OR UNSPECIFIED)
ORCHARDS (non-food stump treatment)
AIRPORTS/LANDING FIELDS, COMMERCIAL/INSTITUTIONAL/INDUSTRIAL
PREMISES/EQUIPMENT (OUTDOOR)
PAVED AREAS (PRIVATE ROADS/SIDEWALKS), DRAINAGE SYSTEMS, INDUSTRIAL
AREAS (OUTDOOR), NONAGRICULTURAL RIGHTS-OF-
WAY/FENCEROWS/HEDGEROWS
COMMERCIAL STORAGES/WAREHOUSES PREMISES, PAVED AREAS (PRIVATE
ROADS/SIDEWALKS), DRAINAGE SYSTEMS, INDUSTRIAL AREAS (OUTDOOR)
AGRICULTURAL RIGHTS-OF-WAY/FENCEROWS/HEDGEROWS
NONAGRICULTURAL RIGHTS-OF-WAY/FENCEROWS/HEDGEROWS
ORNAMENTAL HERBACEOUS PLANTS, ORNAMENTAL NONFLOWERING PLANTS
ORNAMENTAL AND/OR SHADE TREES, ORNAMENTAL WOODY SHRUBS AND VINES
AGRICULTURAL/FARM STRUCTURES/BUILDINGS AND EQUIPMENT
AGRICULTURAL/FARM PREMISES
AGRICULTURAL FALLOW/IDLELAND, NONAGRICULTURAL UNCULTIVATED
AREAS/SOILS
AGRICULTURAL FALLOW/IDLELAND
AGRICULTURAL/FARM PREMISES
AGRICULTURAL/FARM STRUCTURES/BUILDINGS AND EQUIPMENT,
AGRICULTURAL UNCULTIVATED AREAS, NONAGRICULTURAL UNCULTIVATED
AREAS/SOILS
PASTURES, RANGELAND
RECREATION AREA LAWNS, RESIDENTIAL LAWNS
RESIDENTIAL LAWNS
HOUSEHOLD/DOMESTIC DWELLINGS OUTDOOR PREMISES, RECREATION AREA
LAWNS
ORNAMENTAL LAWNS AND TURF
COMMERCIAL/INDUSTRIAL LAWNS, ORNAMENTAL LAWNS AND TURF
ORNAMENTAL SOD FARM (TURF)
COMMERCIAL/INDUSTRIAL LAWNS
ORNAMENTAL SOD FARM (TURF)
GOLF COURSE TURF
RICE
AQUATIC AREAS/WATER, INTERMITTENTLY FLOODED AREAS/WATER,
LAKES/PONDS/RESERVOIRS (WITH HUMAN OR WILDLIFE USE)
AQUATIC AREAS/WATER, INTERMITTENTLY FLOODED AREAS/WATER
SWAMPS/MARSHES/WETLANDS/STAGNANT WATER
LAKES/PONDS/RESERVOIRS (WITH HUMAN OR WILDLIFE USE),
SWAMPS/MARSHES/WETLANDS/STAGNANT WATER
EEC
(HS/L)
44.02
127.70
194.70
534.60
337.90
148.40
3479.00
1363.00
5802.00
250.06
1319.20
2929.60
34.04
415.30
382.60
77.28
103.14
87.78
64.62
990.20
990.20
32.91
394.80
75.02
415.02
1499.38
5.26
34.65
20.80
124.83
165.10
270.00
763.00
763.00
2500.00
2500.00
2500.00
2500.00
RQ*
0.05
0.15
0.23
0.62
0.39
0.17
4.05
1.58
6.75
0.29
1.53
3.41
0.04
0.48
0.44
0.09
0.12
0.10
0.08
1.15
1.15
0.04
0.46
0.09
0.48
1.74
0.01
0.04
0.02
0.15
0.19
0.31
0.44
0.44
2.91
2.91
2.91
2.91
a RQs used to estimate indirect effects to the CRLF via toxicity to non-vascular aquatic plants are
summarized in Table 5-2
* = LOC exceedances (RQ > 1) are bolded and shaded.
RQ = use-specific peak EEC / [Lemna gibba EC50 = 860 ppb].
96
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5.1.2 Exposures in the Terrestrial Habitat
5.1.2.1 Direct Effects to Terrestrial-phase CRLF
As previously discussed in Section 3.3, potential direct effects to terrestrial-phase CRLFs
are based on foliar and granular applications of triclopyr.
Potential direct acute effects to the terrestrial-phase CRLF are derived by considering
dose- and dietary-based EECs modeled in T-REX for a small bird (20 g) consuming
small invertebrates (Table 3-5) and acute oral and subacute dietary toxicity endpoints for
avian species. Acute effects are estimated using the lowest available toxicity data for
birds. EECs are divided by toxicity values to estimate acute dietary and dose-based RQs
(Table 5-5 and Table 5-6, respectively). The Northern bobwhite quail was the most
sensitive to triclopyr on a subacute dietary basis (LC50 = 2934 ppm), and acute dietary
basis (LD50 = 529 mg ae/kg-bw). These endpoints were selected to serve as a surrogate
for the CRLF. Resulting acute dietary-based RQs for all foliar application uses of
triclopyr except rice exceed the Agency' s acute endangered species LOG of 0.1 for the
CRLF (Table 5-5). The acute dose-based RQs exceed the Agency's acute endangered
species LOG of 0.1 for the CRLF for all foliar application uses of triclopyr (Table 5-6).
An example T-REX output is available in Appendix E.
The probability of individual effect at the endangered species LOG (0.1) ranges from 1 in
1.03 with a 95% CI of 1 in 1.24 to 1 in 1 (for Agricultural Uncultivated Areas) to 1 in
1.21*103 with a 95% CI of 1 in 12.3 to 1 in 6.33*109 (for Douglas-Fir, Forest/Shelterbelt)
for dietary-based acute RQs. For dose-based acute RQs the probability of individual
effect at the endangered species LOG (0.1) ranges from 1 in 1 with a 95% CI of 1 in 1 to
1 in 1 (for Agricultural Uncultivated Areas) to 1 in 297 with a 95% CI of 1 in 8.75 to 1 in
3.33*107 (for Rice). The effect probability was calculated based on a default slope
assumption of 4.5 with upper and lower 95% confidence intervals of 2 and 9 (Urban and
Cook, 1986).
Potential direct chronic effects of triclopyr to the terrestrial-phase CRLF are derived by
considering dietary-based exposures modeled in T-REX for a small bird (20g) consuming
small invertebrates. Chronic effects are estimated using the lowest available toxicity data
for birds. EECs are divided by toxicity values to estimate chronic dietary-based RQs
(Table 5-6). Chronic reproductive effects for the Mallard duck were observed with a
NOAEC of 100 ppm. The chronic dietary-based RQs for the terrestrial-phase CRLF
exceed the Agency's chronic LOG of 1.0 for all foliar application uses of triclopyr except
Rice (Table 5-7). The probability of individual effect probit slope analysis is not
applicable for chronic endpoints. The recommended mitigated maximum foliar
application rate of 9 Ibs ae/A would still result in exceedances of the Agency's acute and
chronic endangered species LOG of 0.1 and 1.0 (respectively) for the CRLF (Table 5-5 to
Table 5-7).
For granular uses of triclopyr the LDso/ft2 is used to estimate risk to the CRLF both
directly and indirectly (via prey items). Estimated EECs for broadcast granular
97
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application for direct effects to the CRLF are presented in Table 3-6. The LD50/ft2 is
calculated using a toxicity value (the adjusted LD50) and the EEC (mg a.e./ft2), and is
compared to the Agency's LOG. Results are presented in terms of the acid equivalent.
The adjusted LD50s are separated out by weight class of birds (20, 100 and lOOOg), and
are presented in Table 5-8. However, the weight range of adult CRLFs is 1.4 - 238 g,
therefore the applicable weight ranges for the CRLF is 20 and 100 g, and birds weighing
lOOOg were omitted. Resulting LDso/ft2s for all granular application uses of triclopyr
exceed the Agency' s acute endangered species LOG of 0.1 for birds weighing 20 and
lOOg (Table 5-8). After calculation of the LD50/ft2 additional refinement to determine
risks associated with granular application can be preformed by identifying the number of
granules it would take to reach the LDso in birds (surrogates for terrestrial-phase
amphibians). However, due to limitations associated with the granular formulations (as
fertilizers), the needed information concerning the weight of one granule was not
available, and therefore further characterization was unable to be completed for the
granular applications of triclopyr.
The probability of individual effect at the endangered species LOG (0.1) ranges from 1 in
1.09 with a 95% CI of 1 in 1.36 to 1 in 1 (for Commercial/Industrial Lawns) to 1 in 1.88
with a 95% CI of 1 in 1.95 to 1 in 1.78 (for Ornamental Lawns and Turf) for birds
weighing 20 g. For birds weighing 100 g LD50/ft2 the probability of individual effect at
the endangered species LOG (0.1) ranges from 1 in 77.0 with a 95% CI of 1 in 6.20 to 1
in 2.37* 105 (for Commercial/Industrial Lawns) to 1 in 5.85*103 with a 95% CI of 1 in
17.9 to 1 in 2.53*1012 (for Ornamental Lawns and Turf). The effect probability was
calculated based on a default slope assumption of 4.5 with upper and lower 95%
confidence intervals of 2 and 9 (Urban and Cook, 1986). Based on the potential for
both acute and chronic effects (Table 5-5 to Table 5-8) triclopyr may directly affect
the terrestrial-phase of the CRLF.
Table 5-5 Summary of Dietary-based Acute RQs* Used to Estimate Direct Effects to
the Terrestrial-phase CRLF (Foliar applications) From T-REX
Use
Application Rate (Ib a.e./acre)
Agricultural Uncultivated
(20 Ib ae/acre; 17 times/yr; 21 day intervals) (Max. Foliar)
Forest Tree/Pest Management
(8 Ib ae/acre; 17 times/yr; 21 day intervals) (Median Foliar)
Douglas-Fir (Forest/Shelterbelt)
(1.5 Ib ae/acre; 17 times/yr; 21 day intervals) (Median Foliar)
Rice
(0.38 Ib ae/acre; 2 times/yr; 21 day intervals) (Min Foliar)
Dietary-
based
Acute RQ1
2.70
1.08
0.20
0.03
Probability of Individual
Effect at RQa
1 in 1.03
(1 in 1.24 to linl)
97%
1 in 1.79
(1 in 1.90 to 1 in 1.62)
56%
linl.21*103
(1 in 12.3 to Iin6.33*109)
0.83%
No exceedance
* = LOG exceedances (Acute RQ > 0. 1) are bolded and shaded.
1 Based on Northern Bobwhite Quail LC50 = 2934 ppm.
a A probit slope value for the acute avian toxicity test is not available; therefore, the effect probability was calculated based
on a default slope assumption of 4.5 with upper and lower 95% confidence intervals of 2 and 9 (Urban and Cook, 1986).
98
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Table 5-6 Summary of Dose-based Acute RQs* Used to Estimate Direct Effects to
the Terrestrial-phase CRLF (Foliar applications) From T-REX
Use
Application Rate (Ib a.e./acre)
Agricultural Uncultivated
(20 Ib ae/acre; 17 times/yr; 21 day intervals) (Max. Foliar)
Forest Tree/Pest Management
(8 Ib ae/acre; 17 times/yr; 21 day intervals) (Median Foliar)
Douglas-Fir (Forest/Shelterbelt)
(1.5 Ib ae/acre; 17 times/yr; 21 day intervals)
(Median Foliar)
Rice
(0.38 Ib ae/acre; 2 times/yr; 21 day intervals) (Min. Foliar)
Dose-based
Acute RQ1
23.7
9.5
1.8
0.25
Probability of Individual Effect at RQa
linl
(1 in 1 to 1 inl)
100%
1 inl
(1 in 1.03 to linl)
100%
linl. 14
(95% CI: 1 in 1.44 to 1 in 1.01)
88%
1 in 297
(95% CI: 1 in 8.75 to 1 in 3.33*107)
0.34%
* = LOG exceedances (Acute RQ > 0. 1) are bolded and shaded.
1 Based on Northern Bobwhite Quail LD50 = 529 mg/kg-bw.
a A probit slope value for the acute avian toxicity test is not available; therefore, the effect probability was calculated based on a
default slope assumption of 4.5 with upper and lower 95% confidence intervals of 2 and 9 (Urban and Cook, 1986).
Table 5-7 Summary of Chronic RQs* Used to Estimate Direct Effects to the
Terrestrial-phase CRLF (Foliar applications) From T-REX
Use
(Application Rate)
Agricultural Uncultivated
(20 Ib ae/acre; 17 times/yr; 21 day intervals) (Max. Foliar)
Forest Tree/Pest Management
(8 Ib ae/acre; 17 times/yr; 21 day intervals) (Median Foliar)
Douglas-Fir (Forest/Shelterbelt)
(1 .5 Ib ae/acre; 17 times/yr; 21 day intervals) (Median Foliar)
Rice
(0.38 Ib ae/acre; 2 times/yr; 21 day intervals) (Min. Foliar)
Dietary-based Chronic RQ1
79.3
31.7
6.0
0.85
* = LOG exceedances (Chronic RQ > 1 ) are bolded and shaded.
1 Based on Mallard duck NOAEC = 100 ppm.
Table 5-8 Summary of LD50/ft * Used to Estimate Direct Effects to the Terrestrial-
phase CRLF (Granular applications) From T-REX
Use
Application Rate (Ib a.e./acre)
Commercial/Industrial Lawns
(1.5 Ib ae/acre; 17 times/yr; 21 day intervals)
(Max. Granular)
Ornamental Lawns and Turf
(0.76 Ib ae/acre; 17 times/yr; 21 day intervals)
(Min. Granular)
Size
class
(g)
20
100
20
100
Adjusted LD50
(mg/kg bw)
381.11
485.17
381.11
485.17
LD50/ft2
2.05
0.32
1.04
0.16
Probability of Individual Effect at
LD50/ft2a
linl. 09
(linl. 36 to linl)
92%
Iin77
(1 in 6.2 to Iin2.37*105)
1.3%
linl. 88
(1 in 1. 95 to 1 in 1.78)
53%
Iin5.85*103
(Iinl7.9tolin2.53*1012)
0.02%
99
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* = LOG exceedances (Acute RQ > 0.1) are bolded and shaded.
LD50/ft2 = EEC (mg a.e./ ft2)/ (Adj. LD50 / bw (kg) assessed animal).
a A probit slope value for the acute avian toxicity test is not available; therefore, the effect probability was calculated based on a
default slope assumption of 4.5 with upper and lower 95% confidence intervals of 2 and 9 (Urban and Cook, 1986).
5.1.2.2 Indirect Effects to Terrestrial-Phase CRLF via Reduction in Prey
(terrestrial invertebrates, mammals, and frogs)
a) Terrestrial Invertebrates
In order to assess the risks of triclopyr to terrestrial invertebrates, which are considered
prey of CRLF in terrestrial habitats, the honey bee is used as a surrogate for terrestrial
invertebrates. The toxicity value for terrestrial invertebrates is calculated by multiplying
the lowest available acute contact LDso of > 72 jig a.e./bee by 1 bee/0.128g, which is
based on the weight of an adult honey bee. EECs (jig a.e./g of bee) calculated by T-REX
for small and large insects are divided by the calculated toxicity value for terrestrial
invertebrates, which is > 562.5 jig a.e./g of bee (ppm) to calculate RQs. However, the
toxicity data are not definitive endpoints and as a result RQs were not calculated. There
are no additional acceptable terrestrial invertebrate data from registrant submitted studies
or from the open literature by which to calculate RQ values. Because the calculated
terrestrial small insect EEC's exceed the highest concentrations of triclopyr tested,
(agricultural uncultivated areas 7930 ppm small insects and 881 ppm large insects),
it is determined that triclopyr may affect the CRLF indirectly via reduction in
terrestrial invertebrate prey items.
b) Mammals
Risks associated with ingestion of small mammals by large terrestrial-phase CRLFs are
derived for dietary-based and dose-based exposures modeled in T-REX for a small
mammal (15g) consuming short grass. Acute and chronic effects are estimated using the
most sensitive mammalian toxicity data (LD50 = 572 mg ae/kg-bw, NOAEL = 5 mg
ae/kg-bw and NOAEC =100 mg ae/kg-diet). EECs are divided by the toxicity value to
estimate acute and chronic dose-based RQs as well as chronic dietary-based RQs (Table
5-9). Acute and chronic-dose based and chronic dietary-based RQs exceed the Agency's
acute and chronic endangered species LOG (0.1 acute and 1.0 chronic) for all foliar
application uses of triclopyr (Table 5-9). The recommended mitigated maximum foliar
application rate of 9 Ibs ae/A would still result in exceedances of the Agency's acute and
chronic LOG of 0.1 and 1.0 respectively (Table 5-9).
The probability of individual effect at the acute endangered species LOG (0.1) ranges
from 1 in 1 (95%CI: 1 in 1.02 to 1 in 1) for Agricultural uncultivated areas to 1 in
1.25*105(95%CI: 1 in 3.62*10^0 1 in 3.19*1017) for rice. An example T-REX output
is available in Appendix E. The effect probability was calculated based on a default
slope assumption of 4.5 with upper and lower 95% confidence intervals of 2 and 9
(Urban and Cook, 1986). Population reduction in small mammal prey items for the
CRLF from application of triclopyr ranges from 100% (agricultural uncultivated areas) to
100
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0.0008% (rice) for foliar applications of triclopyr. The probability of individual effect
probit slope analysis is not applicable for chronic endpoints.
For granular uses of triclopyr the LD50/ft2 is used to estimate risk to the CRLF indirectly
(via prey items). Estimated EECs for broadcast granular application for direct effects to
the CRLF are presented in Table 3-6. The LD50/ft2 is calculated using a toxicity value
(the adjusted LDso) and the EEC (mg a.e./ft2), and is compared to the Agency's LOG.
Results are presented in terms of the acid equivalent. The adjusted LD50s are separated
out by weight class of mammals (15, 35 and lOOOg), and are presented in Table 5-10.
However, the weight range of adult CRLFs is 1.4-238 g, therefore they can potentially
only consume mammals that weigh 15 and 35 g depending on the size of the CRLF,
mammals weighing lOOOg were omitted. Resulting LD50/ft2s for all granular application
uses of triclopyr exceed the Agency's acute endangered species LOG of 0.1 for mammals
weighing 15 and 35g (Table 5-10). An example T-REX output is available in Appendix
E.
The probability of individual effect at the endangered species LOG (0.1) ranges from 1 in
2.79 with a 95% CI of 1 in 2.3 to 1 in 4.29 (for Commercial/Industrial Lawns) to 1 in
2.22* 101 with a 95% CI of 1 in 4.43 to 1 in 2.87* 103 (for Ornamental Lawns and Turf)
for mammals weighing 15 g. For mammals weighing 35 g LD50/ft2 the probability of
individual effect at the endangered species LOG (0.1) ranges from 1 in 1.84*10* with a
95% CI of 1 in 4.20 to 1 in 1.5*103 (for Commercial/Industrial Lawns) to 1 in 6.48* 102
with a 95% CI of 1 in 1.06*10* to 1 in 6.14*108 (for Ornamental Lawns and Turf). The
effect probability was calculated based on a default slope assumption of 4.5 with upper
and lower 95% confidence intervals of 2 and 9 (Urban and Cook, 1986). Population
reduction in small mammal prey items for the CRLF from application of triclopyr ranges
from 36% (Commercial/Industrial Lawns) to 0.15% (Ornamental Lawns and Turf) for
granular applications of triclopyr to mammals weighing 15 and 35g.
HED determined that triclopyr was not a mutagen, and but triclopyr has been classified as
a Group D chemical (HED 2002). As a Group D chemical triclopyr is unable to be
classified as to human carcinogenicity, based on marginal evidence of tumors in female
rates and mice and benign adrenal pheochromocytomas in male rats (HED 2002,
Appendix M. Based on the acute and chronic LOC exceedances of triclopyr on small
mammal prey (Table 5-9), triclopyr may indirectly affect the CRLF via reduction in
small mammal prey items.
Table 5-9 Summary of Acute and Chronic RQs* Used to Estimate Indirect Effects
to the Terrestrial-phase CRLF via Direct Effects on Small Mammals as Dietary
Food Items (Foliar applications)
Use
(Application Rate)
Agricultural Uncultivated Areas
(20 Ib ae/acre; 17 times/yr; 21 day intervals)
(Max. Foliar)
Chronic RQ
Dose-based
Chronic RQ1
1222.9
Dietary-
based
Chronic RQ2
141
Acute RQ
Dose-based
Acute RQ3
10.7
Probability of % Effect at
Acute RQa
1 inl
(1 in 1.02 to 1 inl)
100%
101
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Forest Tree/Pest Management
(8 Ib ae/acre; 17 times/yr; 21 day intervals)
(Median Foliar)
Douglas-Fir (Forest/Shelterbelt)
(1.5 Ib ae/acre; 17 times/yr; 21 day intervals)
(Median Foliar)
Rice
(0.38 Ib ae/acre; 2 times/yr; 21 day intervals)
(Min. Foliar)
489.2
91.7
13.1
56.4
10.6
1.51
4.3
0.80
0.11
1 inl
(1 in 1. 11 to 1 inl)
100%
1 in 3. 02
(1 in 2. 36 to 1 in 5.22)
33%
linl.25*105
(1 in 3.62*10' to
Iin3.19*1017)
0.0008%
* = LOG exceedances (acute RQ > 0. 1 and chronic RQ > 1 ) are bolded and shaded.
1 Based on dose-based EEC and triclopyr ae rat NOAEL = 5 mg/kg-bw.
Based on dietary -based EEC and triclopyr ae rat NOAEC =100 mg/kg-diet.
3 Based on dose-based EEC and triclopyr ae rat acute oral LD50 = 572 mg/kg-bw.
a A probit slope value for the acute mammalian toxicity test is not available; therefore, the effect probability was calculated based on a
default slope assumption of 4.5 with upper and lower 95% confidence intervals of 2 and 9 (Urban and Cook, 1986).
Table 5-10 Summary of LD50/ft * Used to Estimate Indirect Effects to the
Terrestrial-phase CRLF via Direct Effects on Small Mammals as Dietary Food
Items (Granular applications)
Use
Application Rate (Ib a.e./acre)
Commercial/Industrial Lawns
(1.5 Ib ae/acre; 17 times/yr; 21 day intervals)
(Max. Granular)
Ornamental Lawns and Turf
(0.76 Ib ae/acre; 17 times/yr; 21 day intervals)
(Min. Granular)
Size
class
GO
15
35
15
35
Adjusted LD50
(mg/kg bw)
1257.16
1017.18
1257.16
1017.18
LDjo/ft2
0.83
0.44
0.42
0.22
Probability of % Effect at
LD50/ft2a
1 in 2.79
(1 in 2. 3 to 1 in 4.29)
36%
1 in 1.84*10'
(1 in 4.20 to linl.5*103)
5.4%
Iin2.22*10'
(Iin4.43tolin2.87*103)
4.5%
1 in6.48*102
(1 in 1.06*10' to Iin6. 14 *108)
0.15%
* = LOG exceedances (Acute RQ > 0.1) are bolded and shaded.
LD50/ft2 = EEC (mg a.e./ ft2)/ (Adj. LD50 / bw (kg) assessed animal).
a A probit slope value for the acute avian toxicity test is not available; therefore, the effect probability was calculated based on a default
slope assumption of 4.5 with upper and lower 95% confidence intervals of 2 and 9 (Urban and Cook, 1986).
c) Frogs
An additional prey item of the adult terrestrial-phase CRLF is other species of frogs. In
order to assess risks to these organisms, dietary-based and dose-based exposures from
foliar applications modeled in T-REX for a small bird (20g) consuming small
invertebrates are used. For granular application, the LD50/ft2 is used to estimate risk to
the CRLF. See Section 5.1.2.1 and associated tables (Table 5-5 to Table 5-8) for results.
The acute dietary-based RQs for all foliar application uses of triclopyr except rice exceed
the Agency's acute endangered species LOG of 0.1 for the CRLF (Table 5-5). The acute
dose-based RQs exceed the Agency's acute endangered species LOG of 0.1 for the CRLF
for all foliar application uses of triclopyr (Table 5-6). The chronic dietary-based RQs
exceed the Agency's chronic LOG of 1.0 for all foliar application uses of triclopyr except
rice (Table 5-7). The LDso/ft2 Analysis of granular applications of triclopyr exceed the
Agency's acute endangered LOG of 0.1 for all granular applications of triclopyr to both a
20 and 100 g bird, surrogate species for the terrestrial-phase CRLF (Table 5-8). The
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recommended mitigated maximum foliar application rate of 9 Ibs ae/A would still result
in exceedances of the Agency's acute and chronic endangered species LOG of 0.1 and 1.0
(respectively) for the CRLF (Table 5-5 through Table 5-7). Based on the acute and
chronic LOC exceedances, triclopyr may indirectly affect the CRLF via reduction in
frogs as prey items.
5.1.2.3 Indirect Effects to CRLF via Reduction in Terrestrial Plant
Community (Riparian and Upland Habitat)
Potential indirect effects to the CRLF resulting from direct effects on riparian and upland
vegetation are assessed using RQs from terrestrial plant seedling emergence and
vegetative vigor EC25 data as a screen. Triclopyr is a systemic herbicide that is used to
control broadleaf weeds and woody plants. The endpoints used for the assessment of
effects to non-target Terrestrial plants were: for dicots the vegetative vigor endpoint is
EC25 = 0.005 Ib ae/A (Sunflower), and the seedling emergence endpoint is EC25 = 0.045
Ib ae/A (Alfalfa), and for monocots the vegetative vigor endpoint is EC25 = 0.063 Ib ae/A
(Onion), and the seedling emergence endpoint is EC2s = 0.053 Ib ae/A (Onion).
The RQs for non-target terrestrial monocots and dicot plants inhabiting semi-aquatic
areas exceed the Agency's risk to terrestrial plant LOC (1.0) for all uses of triclopyr both
foliar (aerial and ground) and granular applications (Table 5-11 and Table 5-12). RQs for
non-target terrestrial monocots and dicot plants inhabiting upland dry areas exceed the
Agency's risk to terrestrial plant LOC (1.0) for all uses of triclopyr except rice both foliar
(aerial and ground) and granular applications (Table 5-11 and Table 5-12). Aerial foliar
applications of triclopyr result in spray drift RQ exceedances for non-target dicot species
for all uses of triclopyr (Table 5-11). Aerial foliar applications of triclopyr result in spray
drift RQ exceedances for monocots for all uses except rice (Table 5-11). Ground foliar
applications result in spray drift RQ exceedances for both monocots and dicots for all
uses except rice (Table 5-11). There were no spray-drift LOC exceedances for non-target
monocot or dicot plants from granular application of triclopyr (Table 5-12). An example
output from TerrPlant v. 1.2.2 is provided in Appendix G. The recommended mitigated
maximum foliar (ground and aerial) application rate of 9 Ibs ae/A would still result in
exceedances of the Agency's terrestrial plant LOC of 1.0 for indirect effects to the
terrestrial-phase CRLF (Table 5-11). RQs for non-target terrestrial monocots and dicot
plants inhabiting semi-aquatic and upland dry areas would still result in exceedances in
the terrestrial plant LOC (1.0) (Table 5-11). Aerial and ground foliar applications would
also still result in spray drift RQ exceedances for non-target terrestrial monocots and
dicot plants (Table 5-11) Based on LOC exceedances on non-target terrestrial
plants, triclopyr may indirectly affect the CRLF via reduction in terrestrial plants.
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Table 5-11 RQs* Plants Inhabiting Dry and Semi-aquatic Areas Exposed
Triclopyr (acid equivalent) via Runoff and Drift (Foliar applications)
to
Use
Agricultural
Uncultivated Areas
(Max)
Forest Tree/Pest
Management
(Median)
Forest Tree/Pest
Management
(Median)
Douglas-Fir
(Forest/Shelterbelt)
(Median)
Rice (Min)
Rice (Min)
Application
rate
(Ibs ae/A)
20
8
8
1.5
0.38
0.38
Application
method
Early Spring -
sprayer
Ratoon - ground
Ratoon - aerial
Drift
Value
(%)
1
1
5
5
1
5
Group
Monocot
Dicot
Monocot
Dicot
Monocot
Dicot
Monocot
Dicot
Monocot
Dicot
Monocot
Dicot
Spray drift
RQ
(Ibs ae/A)
3.77
40.00
1.51
16.00
7.55
80.00
1.42
15.00
<0.1
0.76
0.36
3.80
Dry area
RQ
(Ibs ae/A)
22.64
26.67
9.06
10.67
15.09
17.78
2.83
3.33
0.43
0.51
0.72
0.84
Semi-aquatic
area RQ
(Ibs ae/A)
192.45
226.67
76.98
90.67
83.02
97.78
15.57
18.33
3.66
4.31
3.94
4.64
* = LOG exceedances (plant RQ > 1 ) are bolded and shaded.
Table 5-12 RQs* Plants Inhabiting Dry and Semi-aquatic Areas Exposed to
Triclopyr (acid equivalent) via Runoff and Drift (Granular applications)
Use
Commercial/Industrial
Lawns (Max)
Ornamental Lawns and
Turf (Min)
Application
rate
(Ibs ae/A)
1.5
0.76
Application method
Granular — spreader
Drift
Value
(%)
1
1
Group
Monocot
Dicot
Monocot
Dicot
Spray
drift RQ
(Ibs ae/A)
<0.1
<0.1
<0.1
<0.1
Dry area
RQ
(Ibs ae/A)
1.42
1.67
0.72
0.84
Semi-aquatic
area RQ
(Ibs ae/A)
14.15
16.67
7.17
8.44
* = LOG exceedances (plant RQ > 1 ) are bolded and shaded.
5.1.3 Primary Constituent Elements of Designated Critical Habitat
5.1.3.1 Aquatic-Phase (Aquatic Breeding Habitat and Aquatic Non-Breeding
Habitat)
Three of the four assessment endpoints for the aquatic-phase primary constituent
elements (PCEs) of designated critical habitat for the CRLF are related to potential
effects to aquatic and/or terrestrial plants:
• Alteration of channel/pond morphology or geometry and/or increase in sediment
deposition within the stream channel or pond: aquatic habitat (including riparian
vegetation) provides for shelter, foraging, predator avoidance, and aquatic
dispersal for juvenile and adult CRLFs.
• Alteration in water chemistry/quality including temperature, turbidity, and
oxygen content necessary for normal growth and viability of juvenile and adult
CRLFs and their food source.
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• Reduction and/or modification of aquatic-based food sources for pre-metamorphs
(e.g., algae).
Based on the risk estimation for potential effects to aquatic and/or terrestrial plants
provided in Sections 5.1.1.2, 5.1.1.3, and 5.1.2.3, triclopyr may affect aquatic-phase
PCEs of designated critical habitat related to effects on aquatic and/or terrestrial
plants.
Reduction of aquatic based food sources may occur from most use sites.
Because reduction of aquatic based food sources may occur from most use sites, triclopyr
may be likely to indirectly affect the CRLF. Likewise, due to triclopyr's ability to reduce
aquatic non-vascular plants used as food source and habitat for CRLF, triclopyr may be
likely to indirectly affect the CRLF. Since there are LOG exceedances on non-target
terrestrial dicot plants from spray drift at the minimum application rate for aerial
applications, triclopyr may indirectly affect the CRLF via reduction in terrestrial plants.
As a result, due to aquatic vascular and terrestrial plant communities being reduced from
most use sites, there is potential for alteration of channel/pond morphology or geometry
and/or increase in sediment deposition within the stream channel or pond and for
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.
The remaining aquatic-phase PCE is "alteration of other chemical characteristics
necessary for normal growth and viability of CRLFs and their food source." To assess
the impact of triclopyr on this PCE (i.e., alteration of food sources), acute and chronic
freshwater fish and invertebrate toxicity endpoints, as well endpoints for aquatic non-
vascular plants are used as measures of effects. RQs for these endpoints were calculated
in Sections 5.1.1.1 and 5.1.1.2. Based on LOC exceedances for acute and chronic
freshwater fish, acute invertebrates, and non-vascular plants, triclopyr may affect
aquatic-phase PCEs of designated habitat related to effects of alteration of other
chemical characteristics necessary for normal growth and viability of CRLFs and
their food source.
5.1.3.2 Terrestrial-Phase (Upland Habitat and Dispersal Habitat)
The first two assessment endpoints for the terrestrial-phase PCEs of designated critical
habitat for the CRLF are related to potential effects to terrestrial plants:
• Elimination and/or disturbance of upland habitat; ability of habitat to support food
source of CRLFs: Upland areas within 200 ft of the edge of the riparian
vegetation or 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
• 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
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The risk estimation for terrestrial-phase PCEs of designated habitat related to potential
effects on terrestrial plants is provided in Section 5.1.2.3. These results will inform the
effects determination for modification of designated critical habitat for the CRLF. There
were LOG exceedances for non-target monocot and dicot plants inhabiting semi-aquatic
areas for all applications (foliar and granular) of triclopyr. There were also LOG
exceedances for monocot and dicot plants inhabiting dry (upland-areas) for all foliar and
ground applications except the minimum use (Rice and Ornamental Lawns &Turf,
respectively). All foliar applications except ground rice application resulted in Spray-
drift LOG exceedances for all non-target dicot plants. For non-target monocot plants all
uses of triclopyr except Rice (either ground or aerial) resulted in Spray-drift LOG
exceedances. There were no spray-drift LOG exceedances for non-target monocot or
dicot plants from granular application of triclopyr. The buffer determined from
AgDRIFT (Section 5.2.5.1) yielded a buffer of at least 1,000 feet. Therefore, any plants
within a 1,000 foot radius from the application site may potentially be affected. Based
on these results, triclopyr may affect the first and second terrestrial-PCEs.
The third terrestrial-phase PCE is "reduction and/or modification of food sources for
terrestrial phase juveniles and adults." To assess the impact triclopyr on this PCE, acute
and chronic toxicity endpoints for birds, mammals, and terrestrial invertebrates are used
as measures of effects. RQs for these endpoints were calculated in Section 5.1.2.2.
Based on acute and chronic risk LOC exceedances for direct effects to the CRLF, as
well as indirect effects to the CRLF prey items of small mammals, and other frogs,
and because the calculated small insect EECs are greater than the highest levels
tested in the terrestrial invertebrate study (Section 5.2.2.4 for terrestrial
invertebrates, Section 5.2.2.5 for mammals, and 5.2.2.6 for frogs), triclopyr may
result in Habitat Modification of the first three terrestrial-phase PCEs.
The fourth terrestrial-phase PCE is based on alteration of chemical characteristics
necessary for normal growth and viability of juvenile and adult CRLFs and their food
source. Direct acute and chronic RQs for terrestrial-phase CRLFs are presented in
Section 5.2.1.2. Due to LOC exceedances for aquatic, terrestrial and semi-aquatic
plants, which modify the water chemistry to conditions for which the CRLF is
adapted, triclopyr may result in Habitat Modification of the fourth terrestrial-phase
PCE.
5.2 Risk Description
The risk description synthesizes an overall conclusion regarding the likelihood of adverse
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 and its designated
critical habitat.
Based on the RQs presented in the Risk Estimation (Section 5.1) a preliminary effects
determination is may affect for the CRLF and critical habitat. The direct and indirect
effect LOCs are exceeded and effects may modify the PCEs of the CRLF's critical
habitat, the Agency concludes a preliminary "may affect" determination for the FIFRA
regulatory action regarding triclopyr. A summary of the risk estimation results are
106
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provided in Table 5-13 for direct and indirect effects to the CRLF and in Table 5-14 for
the PCEs of designated critical habitat for the CRLF.
Table 5-13 Risk Estimation Summary for Triclopyr - Direct and Indirect Effects to
CRLF
Assessment Endpoint
LOC
Exceedances
(Y/N)
Description of Results of Risk Estimation
Aquatic Phase
(eggs, larvae, tadpoles, juveniles, and adults)
Direct Effects
Survival, growth, and reproduction of CRLF
individuals via direct effects on aquatic phases
Yes
The aquatic phase amphibian acute and chronic LOCs for listed
species (0.05) are exceeded for most uses of triclopyr in California.
The acute RQs range from 9.62 for lakes/ponds/reservoirs to 0.02 for
ornamental lawns and turf).
The chronic RQs range from 131.5 8 for lakes/ponds/reservoirs to 0.21
for ornamental lawns and turf.
Indirect Effects
Survival, growth, and reproduction of CRLF
individuals via effects to food supply (i.e.,
freshwater invertebrates, non-vascular plants)
Yes
LOCs for aquatic invertebrates are exceeded for most uses on an acute
basis, and some uses on a chronic basis. The acute RQs range from
10.00 for lakes/ponds/reservoirs to 0.02 for ornamental lawns and turf).
The chronic RQs range from 0.10 for lakes/ponds/reservoirs to <0.01
for ornamental lawns and turf.
LOCs for non-vascular plants are exceeded for most uses. The RQs
range from 35.71 for lakes/ponds/reservoirs to 0.08 for ornamental
lawns and turf.
Indirect Effects
Survival, growth, and reproduction of CRLF
individuals via effects on habitat, cover,
and/or primary productivity (i.e., aquatic plant
community)
Yes
RQs for vascular aquatic plants exceed the Agency's LOC (1.0) for
some uses. These range from 2.91 for lakes/ponds/reservoirs to 0.02
for ornamental lawns and turf.
Indirect Effects
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.
Yes
RQs for non-target terrestrial monocot and dicot plants inhabitating
semi-aquatic and upland dry areas exceed the Agency's LOC for most
uses. Spray driftRQs formonocots range from <0.1 to 7.55. Spray
drift RQs for dicots range from 0.76 to 80.00.
Terrestrial Phase
(Juveniles and adults)
Direct Effects
Survival, growth, and reproduction of CRLF
individuals via direct effects on terrestrial
phase adults and juveniles
Yes
The subacute dietary-based RQs exceed the acute LOC (0.1) for all
foliar application uses of triclopyr except rice, ranging from 2.7
(Agricultural Uncultivated Areas) to 0.03 (Rice). The acute dose-based
RQs exceed the acute endangered species LOC (0.1) for all foliar
application uses of triclopyr, ranging from 23.7 (Agricultural
Uncultivated Areas) to 0.25 (Rice). The chronic dietary-based RQs
exceed the chronic LOC (1.0) for all foliar application uses of triclopyr
except rice, ranging from 79.3 (Agricultural Uncultivated Areas) to
0.85 (Rice). For granular uses of triclopyr the resulting LD50/ft s for all
granular application uses of triclopyr exceed the Agency's acute
endangered species LOC of 0.1 for birds weighing 20 and lOOg and
range from 2.05 (Commercial/Industrial Lawns) to 0.16 (Ornamental
Lawns and Turf).
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Assessment Endpoint
LOC
Exceedances
(Y/N)
Description of Results of Risk Estimation
Indirect Effects
Survival, growth, and reproduction of CRLF
individuals via effects on prey (i.e., terrestrial
invertebrates, small terrestrial mammals and
terrestrial phase amphibians)
Yes
For terrestrial invertebrates, the calculated small insect EEC range
from 7930 to 85 ppm, exceeds the terrestrial invertebrate toxicity
estimate 562.5 for all uses except Rice. Therefore, risk cannot be
precluded for these species due to the lack of definitive data.
For small terrestrial mammals, the acute dose-based RQs exceed the
acute risk LOC (0.1) for all foliar application uses of triclopyr ranging
from 10.7 (Agricultural Uncultivated Areas) to 0.11 (Rice). Both
dietary and dose-based chronic RQs exceed the chronic risk LOC
(1.0) for all foliar application uses of triclopyr ranging from 1222.9
(Agricultural Uncultivated Areas) to 13.1 (Rice) [Dose-based] and
141 (Agricultural Uncultivated Areas) to 1.51 (Rice) [Dietary-based].
For granular applications of triclopyr the resulting LD50/ft2s for all
granular application uses of triclopyr exceed the Agency's acute
endangered species LOC of 0.1 for mammals weighing 15 and 35g.
For terrestrial-phase amphibians the subacute dietary-based RQs
exceed the acute LOC (0.1) for all foliar application uses of triclopyr
except ornamental herbaceous/non-flowering plants and rice, ranging
from 2.7 (Agricultural Uncultivated Areas) to 0.03 (Rice). The acute
dose-based RQs exceed the acute endangered species LOC (0.1) for
all foliar application uses of triclopyr, ranging from 23.7 (Agricultural
Uncultivated Areas) to 0.25 (Rice). The chronic dietary-based RQs
exceed the chronic LOC (1.0) for all foliar application uses of
triclopyr except rice, ranging from 79.3 (Agricultural Uncultivated
Areas) to 0.85 (Rice). For granular uses of triclopyr the resulting
LD50/ft2s for all granular application uses of triclopyr exceed the
Agency's acute endangered species LOC of 0.1 for birds weighing 20
and lOOg, ranging from 2.05 (Commercial/Industrial Lawns) to 0.32
(Ornamental Lawns and Turf) for 20 g birds, and 1.04
(Commercial/Industrial Lawns) to 0.16 (Ornamental Lawns and Turf)
for 100 g birds.
Indirect Effects
Survival, growth, and reproduction of CRLF
individuals via effects on habitat (i.e., riparian
vegetation)
Yes
RQs for vascular aquatic plants exceed the Agency's LOC (1.0) for
some uses. These range from 2.91 for lakes/ponds/reservoirs to 0.02
for ornamental lawns and turf.
The RQs for non-target terrestrial monocots and dicot plants
inhabiting semi-aquatic areas exceed the Agency's risk to terrestrial
plant LOC (1.0) for all uses of triclopyr both foliar (aerial and ground)
and granular applications. RQs for non-target terrestrial monocots
and dicot plants inhabiting upland dry areas exceed the Agency's risk
to terrestrial plant LOC (1.0) for all uses of triclopyr except rice both
foliar (aerial and ground) and granular applications. Aerial foliar
applications of triclopyr result in spray drift RQ exceedances for dicot
non-target species for all uses of triclopyr. Aerial foliar applications
of triclopyr result in spray drift RQ exceedances for monocots for all
uses except rice. Ground foliar applications result in spray drift RQ
108
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Assessment Endpoint
LOC
Exceedances
(Y/N)
Description of Results of Risk Estimation
exceedances for both monocots and dicots for all uses except rice.
Table 5-14 Risk Estimation Summary for Triclopyr - PCEs of Designated Critical
Habitat for the CRLF
Assessment Endpoint
Habitat Modification
(Y/N)
Description of Results of Risk Estimation
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.
Yes
LOCs are exceeded for terrestrial riparian plants and for
aquatic vascular plants from exposure to triclopyr from
spray drift.
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.
Yes
LOCs are exceeded for terrestrial riparian plants and for
aquatic plants from exposure to triclopyr from spray drift.
Alteration of riparian and vascular plants may result in
alteration of temperature, turbidity, and oxygen content.
Alteration of other chemical characteristics
necessary for normal growth and viability of
CRLFs and their food source.
Yes
LOC is exceeded for indirect effects on terrestrial phase
CRLF from most triclopyr applications.
Reduction and/or modification of aquatic-based
food sources for pre-metamorphs (e.g., algae)
Yes
LOCs for non-vascular plants are exceeded for most uses.
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
Yes
AgDrift model was used to evaluate potential distances
beyond which exposures would be expected to be below
LOC. The buffer needed for exposures to be below the
LOC is approximately 1000 ft for both aerial and ground
applications based on monocot and dicot non-target
plants.
Elimination and/or disturbance of dispersal
habitat: Upland or riparian dispersal habitat
within designated units and between occupied
locations within 0.7 mi of each other that allow
for movement between sites including both
natural and altered sites which do not contain
barriers to dispersal
Effects are expected to non-target terrestrial plants over
1000 ft from use site from aerial application.
Yes
Reduction and/or modification of food sources
for terrestrial phase juveniles and adults
Yes
Acute dietary-based RQs for birds (surrogate terrestrial-
phase CRLF) exceed the endangered species LOC for all
foliar application uses of triclopyr except rice. Acute dose-
based RQs for small mammals and birds (surrogate
terrestrial-phase CRLF) exceed the endangered species
LOC for all foliar application uses of triclopyr.
Chronic dietary and dose-based RQs for small mammals
and birds (surrogate terrestrial-phase CRLF) exceed the
109
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Assessment Endpoint
Alteration of chemical characteristics necessary
for normal growth and viability of juvenile and
adult CRLFs and their food source.
Habitat Modification
(Y/N)
Yes
Description of Results of Risk Estimation
endangered species LOG for all foliar application uses of
triclopyr, except dose-based birds.
For granular uses of triclopyr the resulting LD50/ft2s for all
granular application uses of triclopyr exceed the Agency's
acute endangered species LOG of 0.1 for birds weighing
20 and lOOg, ranging from 2. 05 (Commercial/Industrial
Lawns) to 0.32 (Ornamental Lawns and Turf) for 20 g
birds, and 1.04 (Commercial/Industrial Lawns) to 0.16
(Ornamental Lawns and Turf) for 100 g birds.
All aerial applications of triclopyr for dicots and all uses
except Rice for monocots result in spray drift exceedances
for non-target terrestrial plants inhabiting semi-aquatic and
upland dry areas.
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. 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 and its designated critical habitat.
The criteria used to make determinations that the effects of an action are "not likely to
adversely affect" the CRLF and its designated critical habitat include the following:
• Significance of Effect: Insignificant effects are those that cannot be meaningfully
measured, detected, or evaluated in the 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.
• 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 and its designated critical habitat is provided in Sections 5.2.1
through 5.2.3.
110
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5.2.1 Direct Effects
5.2.1.1 Aquatic-Phase CRLF
The aquatic-phase considers life stages of the frog that are obligatory aquatic organisms,
including eggs and larvae. It also considers submerged terrestrial-phase juveniles and
adults, which spend a portion of their time in water bodies that may receive runoff and
spray drift containing triclopyr.
Triclopyr is considered "toxic" to the freshwater fish, which are surrogates for the aquatic
phase CRLF. The aquatic animal acute LOCs for listed species (0.05) were exceeded for
most of the triclopyr uses. The acute RQ's ranged from 9.62 for lakes/ponds/reservoirs to
0.02 for ornamental lawns and turf. The chronic RQ's ranged from 131.58 for
lakes/ponds/reservoirs to 0.21 for ornamental lawns and turf.
There were a total of three aquatic animal incidents that were reported for triclopyr, and
the certainty of triclopyr being responsible was possible, probable and highly probable.
The California Department of Pesticide Regulation (CDPR) has been collecting surface
water data on triclopyr for many years. Samples were taken in six California counties
from March 1993 to March 2006. Out of 583 samples, 102 samples contained triclopyr.
The median concentration of positive samples was 0.65 ppb and the mean concentration
was 1.7 ppb. The highest detected concentration of 14.5 ppb was recorded on June 21,
2001 at Colusa Basin Drain #5 in Colusa County, which is an area that is known for
growing rice. Triclopyr concentrations were consistently elevated at this site through the
months of June and July, 2001 with an average concentration of 3.5 ppb. This may be
due to the use of triclopyr on rice. Colusa County is one of four leading counties for rice
production in California. The Rice Model predicted a concentration of 763.00 ppb. This
is a little more than a magnitude larger, and shows how conservative the model is.
Because there are LOC exceedances from registered uses of triclopyr to the CRLF
surrogate species (freshwater fish), verified non-target incidents resulting from
triclopyr use, and because triclopyr's presence has been observed in monitored
surface water in California, the Agency concludes that triclopyr May Affect and is
Likely to Adversely Affect (LAA) the CRLF.
5.2.1.2 Terrestrial-Phase CRLF
The RQs representing acute dietary-based exposures exceed the Agency's LOC (0.1) for
all foliar application uses of triclopyr except rice (Section 5.1.2.1). The RQs ranged from
2.7 (Agricultural Uncultivated Areas) to 0.03 (Rice) (Table 5-5). The acute dose-based
RQs exceed the acute endangered species LOC (0.1) for all foliar application uses of
triclopyr, ranged from 23.7 (Agricultural Uncultivated Areas) to 0.25 (Rice) (Table 5-6).
The chronic dietary-based RQs exceed the chronic LOC (1.0) for all foliar application
uses of triclopyr except rice, and ranged from 79.3 (Agricultural Uncultivated Areas) to
0.85 (Rice) (Table 5-7). These RQs were derived using the T-REX model, which
111
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estimates exposures that are specific to food intake equations for birds. RQs generated for
birds are used as surrogates to represent RQs for the terrestrial-phase CRLF. For
granular uses of triclopyr the resulting LDso/ft2s for all granular application uses of
triclopyr exceed the Agency's acute endangered species LOG of 0.1 for birds weighing
20 and lOOg, ranging from 2.05 (Commercial/Industrial Lawns) to 0.32 (Ornamental
Lawns and Turf) for 20 g birds, and 1.04(Commercial/Industrial Lawns) to 0.16
(Ornamental Lawns and Turf) for 100 g birds (Table 5-8). The LDso/ft2 is calculated
using a toxicity value (the adjusted LD50) and the EEC (mg a.e./ft2), and is compared to
the Agency's LOG. Based on these exceedances to the terrestrial-phase CRLF, a "May
Affect" determination was made
The T-HERPS model was therefore employed as a refinement tool to explore amphibian-
specific food intake on potential exposures to the terrestrial phase CRLF. The T-HERPS
model incorporates the same inputs as T-REX with equations adjusted for poikilotherm
food intake. The dietary-based and dose-based EECs generated by T-HERPS are found
in Table 5-15 to Table 5-17. An example output from T-HERPS is available in Appendix
F.
Table 5-15 Upper-bound Kenega Nomogram T-HERPS EECs (mg/kg-diet) for
Dietary-based Exposures of the CRLF and its Prey to Triclopyr, the weights of
small herbivore and insectivore mammals are 15 g and 35 g (Foliar applications).
Scenario
Agricultural Uncultivated Areas
(20 Ib ae/acre; 17 times/yr; 21 day
intervals) (Max-Foliar)
Forest Tree/Pest Management
(8 Ib ae/acre; 17 times/yr; 21 day
intervals) (Median-Foliar)
Douglas-Fir (Forest/Shelteibelt)
(1.5 Ib ae/acre; 17 times/yr; 21 day
intervals) (Median-Foliar)
Rice
(0.38 Ib ae/acre; 2 times/yr; 21 day
intervals) (Min-Foliar)
Weight of
mammals
(herbivore &
insectivore)
15g
35g
15g
35g
15g
35g
15g
35g
Small
Insects
7928.69
7928.69
3171.48
3171.48
594.65
594.65
85.15
85.15
Large
Insects
880.97
880.97
352.39
352.39
66.07
66.07
9.46
9.46
Small
Herbivore
Mammals
13438.93
9288.10
5375.57
3715.24
1007.92
696.61
144.32
99.74
Small
Insectivore
Mammals
839.93
580.51
335.97
232.20
62.99
43.54
9.02
6.23
Small
Terrestrial
Phase
Amphibians
275.21
275.21
110.09
110.09
20.64
20.64
2.96
2.96
112
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Table 5-16 Upper-bound Kenega Nomogram T-HERPS EECs (mg/kg-bw) for Dose-
based Exposures of the CRLF and its Prey to Triclopyr, the weights of small
herbivore and insectivore mammals are 15 g (Foliar applications).
Scenario
Agricultural Uncultivated Areas
(20 Ib ae/acre; 17 times/yr; 21 day
intervals) (Max-Foliar)
Forest Tree/Pest Management
(8 Ib ae/acre; 17 times/yr; 21 day
intervals) (Median-Foliar)
Douglas-Fir (Forest/Shelterbelt)
(1.5 Ib ae/acre; 17 times/yr; 21 day
intervals) (Median-Foliar)
Rice
(0.38 Ib ae/acre; 2 times/yr; 21 day
intervals) (Min-Foliar)
CRLF
Size (g)
1.4
37
238
1.4
37
238
1.4
37
238
1.4
37
238
Small
Insects
308.04
302.74
198.41
123.22
121.10
79.37
23.10
22.71
14.88
3.31
3.25
2.13
Large
Insects
34.23
33.64
22.05
13.69
13.46
8.82
2.57
2.52
1.65
0.37
0.36
0.24
Small
Herbivore
Mammals
N/A
5448.21
846.99
N/A
2179.29
338.80
N/A
408.62
63.52
N/A
58.51
9.10
Small
Insectivore
Mammals
N/A
340.51
52.94
N/A
136.21
21.17
N/A
25.54
3.97
N/A
3.66
0.57
Small
Terrestrial
Phase
Amphibians
N/A
10.51
6.89
N/A
4.20
2.75
N/A
0.79
0.52
N/A
0.11
0.07
Table 5-17 Upper-bound Kenega Nomogram T-HERPS EECs (mg/kg-bw) for Dose-
based Exposures of the CRLF and its Prey to Triclopyr, the weights of small
herbivore and insectivore mammals are 35 g (Foliar applications).
Scenario
Agricultural Uncultivated Areas
(20 Ib ae/acre; 17 times/yr; 21 day
intervals) (Max-Foliar)
Forest Tree/Pest Management
(8 Ib ae/acre; 17 times/yr; 21 day
intervals) (Median-Foliar)
Douglas-Fir (Forest/Shelterbelt)
(1.5 Ib ae/acre; 17 times/yr; 21 day
intervals) (Median-Foliar)
Rice
(0.38 Ib ae/acre; 2 times/yr; 21 day
intervals) (Min-Foliar)
CRLF
Size (g)
1.4
37
238
1.4
37
238
1.4
37
238
1.4
37
238
Small
Insects
308.04
302.74
198.41
123.22
121.10
79.37
23.10
22.71
14.88
3.31
3.25
2.13
Large
Insects
34.23
33.64
22.05
13.69
13.46
8.82
2.57
2.52
1.65
0.37
0.36
0.24
Small
Herbivore
Mammals
N/A
8786.04
1365.90
N/A
3514.41
546.36
N/A
658.95
102.44
N/A
94.35
14.67
Small
Insectivore
Mammals
N/A
549.13
85.37
N/A
219.65
34.15
N/A
41.18
6.40
N/A
5.90
0.92
Small
Terrestrial
Phase
Amphibians
N/A
10.51
6.89
N/A
4.20
2.75
N/A
0.79
0.52
N/A
0.11
0.07
Acute Exposures
Refined acute dietary-based RQs for CRLFs consuming small insects and small herbivore
mammals exceed the acute listed species LOG (0.1) for all uses of triclopyr except rice
(mammals weighing 15g or 35g) (Table 5-18). The acute dietary-based RQs for CRLFs
consuming large insects exceed the acute listed species LOC (0.1) for all foliar uses with
application rate greater than or equal to 8.0 Ib ae/A. The acute dietary-based RQs for
CRLFs consuming small insectivore mammals exceed the acute listed species LOC (0.1)
for all foliar uses with an application rate greater than or equal to 1.5 Ib ae/A for CRLFs
113
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consuming 15g mammals and greater than 8 Ib ae/A for CRLFs consuming 35g
mammals. No acute dietary-based LOCs were exceeded for CRLFs consuming small
terrestrial-phase amphibians for any triclopyr use. The recommended mitigated maximum
foliar application rate of 9 Ibs ae/A would still result in exceedances of the Agency's
acute endangered species LOG of 0.1 for the refined dietary-based RQs for CRLFs
consuming small and large insects, small herbivore (weighing 15g and 35g), and small
insective mammals (weighing 15g only) (Table 5-18). Therefore, there is still potential
for direct effects to the terrestrial-phase CRLF even at the mitigated maximum
application rate.
Table 5-18 Refined Acute Dietary-based RQs* for CRLF consuming different food
items (RQs calculated using T-HERPS), the weights of small herbivore and
insectivore mammals are 15 g and 35 g (Foliar applications).
Scenario
Agricultural Uncultivated Areas
(20 Ib ae/acre; 17 times/yr; 21 day
intervals) (Max-Foliar)
Forest Tree/Pest Management
(8 Ib ae/acre; 17 times/yr; 21 day
intervals) (Median-Foliar)
Douglas-Fir (Forest/Shelterbelt)
(1.5 Ib ae/acre; 17 times/yr; 21 day
intervals) (Median-Foliar)
Rice
(0.38 Ib ae/acre; 2 times/yr; 21 day
intervals) (Min-Foliar)
Weight of
mammals
(herbivore &
insectivore)
15g
35g
15g
35g
15g
35g
15g
35g
Small
Insects
2.70
2.70
1.08
1.08
0.20
0.20
0.03
0.03
Large
Insects
0.30
0.30
0.12
0.12
0.02
0.02
<0.01
<0.01
Small
Herbivore
Mammals
4.58
3.17
1.83
1.27
0.34
0.24
0.05
0.03
Small
Insectivore
Mammals
0.29
0.20
0.11
0.08
0.02
0.01
<0.01
<0.01
Small
Terrestrial
Phase
Amphibians
0.09
0.09
0.04
0.04
0.01
0.01
0.01
<0.01
Refined dose-based RQs for CRLF of varying weights (1.4g, 37g and 238g) consuming
small insects exceed the acute endangered species LOG (0.1) for all foliar uses of
triclopyr with an application rate greater than or equal to 8.0 Ib ae/A for all weights of
CRLF (Table 5-19 and Table 5-20). There are no exceedances in the acute endangered
species LOG (0.1) for any uses of triclopyr for any weight class of CRLF consuming
either large insects or small terrestrial-phase amphibians (weighing 2.3g) (Table 5-19 and
Table 5-20). CRLF weighing 1.4g are too small to consume small mammals or small
terrestrial-phase amphibians. Medium-sized CRLFs weighing 37g consuming small
herbivore mammals (both 15g and 35g mammals) exceed the acute endangered species
LOG (0.1) for all foliar uses of triclopyr (Table 5-19 and Table 5-20). Medium-sized
CRLFs weighing 37g consuming small insectivore mammals (both 15g and 35g
mammals) exceed the acute endangered species LOG (0.1) for all uses of triclopyr with
an application rate greater than and equal to 8.0 Ib ae/A (Table 5-19 and Table 5-20).
Large-sized CRLFs weighing 238g consuming small herbivore mammals (both 15 g and
35 g mammals) exceed the acute endangered species LOG (0.1) for all uses of triclopyr
except rice (Table 5-19 and Table 5-20). Large-sized CRLFs weighing 238 g consuming
small insectivore mammals (both 15g and 35g mammals) exceed the acute endangered
114
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species LOG (0.1) for the maximum application of triclopyr only (20 Ib ae/A) (Table
5-19 and Table 5-20). The recommended mitigated maximum foliar application rate of 9
Ibs ae/A would still result in exceedances of the Agency's acute endangered species LOG
of 0.1 for the refined dose-based RQs for CRLF of varying weights (Table 5-19 and
Table 5-20). Refined dose-based RQs resulted in exceedances of the Agency's LOG with
CRLFs of varying weights (1.4g, 37g and 238g) consuming consuming small insects,
Medium (37g) and large (238g) sized CRLFs consuming small herbivore mammals
(weighing both 15g and 35g), and large (238g) sized CRLFs consuming small insectivore
mammals (weighing 15g only). Therefore, there is still potential for direct effects to the
terrestrial-phase CRLF even at the mitigated maximum application rate.
Table 5-19 Refined Acute Dose-based RQs* for CRLF consuming different
items (RQs calculated using T-HERPS), the weights of small herbivore and
insectivore mammals are 15 g (Foliar applications).
food
Scenario
Agricultural Uncultivated Areas
(20 Ib ae/acre; 17 times/yr; 21 day
intervals) (Max-Foliar)
Forest Tree/Pest Management
(8 Ib ae/acre; 17 times/yr; 21 day
intervals) (Median-Foliar)
Douglas-Fir (Forest/Shelteibelt)
(1.5 Ib ae/acre; 17 times/yr; 21 day
intervals) (Median-Foliar)
Rice
(0.38 Ib ae/acre; 2 times/yr; 21 day
intervals) (Min-Foliar)
CRLF
Size (g)
1.4
37
238
1.4
37
238
1.4
37
238
1.4
37
238
Small
Insects
0.58
0.57
0.38
0.23
0.23
0.15
0.04
0.04
0.03
0.01
0.01
0.01
Large
Insects
0.06
0.06
0.04
0.03
0.03
0.02
<0.01
<0.01
<0.01
<0.01
<0.01
<0.01
Small
Herbivore
Mammals
N/A
10.30
1.60
N/A
4.12
0.64
N/A
0.77
0.12
N/A
0.11
0.02
Small
Insectivore
Mammals
N/A
0.64
0.10
N/A
0.26
0.04
N/A
0.05
0.01
N/A
0.01
<0.01
Small
Terrestrial
Phase
Amphibians
N/A
0.02
0.01
N/A
0.01
0.01
N/A
<0.01
<0.01
N/A
<0.01
<0.01
*RQs exceeding the Listed LOG (0.10) are bolded and shaded
Table 5-20 Refined Acute Dose-based RQs* for CRLF consuming different
items (RQs calculated using T-HERPS), the weights of small herbivore and
insectivore mammals are 35 g (Foliar applications).
food
Scenario
Agricultural Uncultivated Areas
(20 Ib ae/acre; 17 times/yr; 21 day
intervals) (Max-Foliar)
Forest Tree/Pest Management
(8 Ib ae/acre; 17 times/yr; 21 day
intervals) (Median-Foliar)
Douglas-Fir (Forest/Shelterbelt)
(1.5 Ib ae/acre; 17 times/yr; 21 day
intervals) (Median-Foliar)
CRLF
Size (g)
1.4
37
238
1.4
37
238
1.4
37
238
Small
Insects
0.58
0.57
0.38
0.23
0.23
0.15
0.04
0.04
0.03
Large
Insects
0.06
0.06
0.04
0.03
0.03
0.02
<0.01
<0.01
<0.01
Small
Herbivore
Mammals
N/A
16.61
2.58
N/A
Small
Insectivore
Mammals
N/A
1.04
0.16
N/A
6.64 0.42
1.03
N/A
1.25
0.19
0.06
N/A
0.08
0.01
Small
Terrestrial
Phase
Amphibians
N/A
0.02
0.01
N/A
0.01
0.01
N/A
<0.01
<0.01
115
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Rice
(0.38 Ib ae/acre; 2 times/yr; 21 day
intervals) (Min-Foliar)
1.4
37
238
0.01
0.01
<0.01
<0.01
<0.01
<0.01
N/A
0.18
0.03
N/A
0.01
<0.01
N/A
<0.01
<0.01
*RQs exceeding the Listed LOG (0. 10) are bolded and shaded
A probit slope value for the acute avian toxicity test was not available; therefore, the
effect probability was calculated based on a default slope assumption of 4.5 with upper
and lower 95% confidence intervals of 2 and 9 (Urban and Cook, 1986). For all uses
with RQs that exceed the endangered species LOCs the probability of individual effects
were conducted to determine the probability that one individual could be impacted by
exposure to triclopyr. Using the refined acute dietary-based RQs for CRLF consuming
different food items (both 15g and 35g mammals) the chance of individual mortality for
which the RQs exceed the LOC (0.1) range from approximately 1 in 1.25*105 (95 % CI:
1 in 3.62*10* to 1 in 3.19*1017) (<1%) at an RQ 0.11 (Forest Tree/Pest Management,
small insectivore mammals weighing 15g) to approximately 1 in 1 (95 % CI: 1 in 1.10 to
1 in 1) (100%) at an RQ of 4.58 (Agricultural Uncultivated Areas, small herbivore
mammals weighing 15g) (Table 5-18). This range of RQs is relevant to CRLF
consuming small and large insects, and small herbivore and insectivore mammals for
uses in which there were LOC exceedances. This range is not relevant to CRLF
consuming small terrestrial-phase amphibians modeled for any use scenario since there
was no LOC exceedance.
Using the refined acute dose-based RQs for CRLF consuming different food items the
chance of individual mortality for which the RQs exceed the LOC (0.1) range from
approximately 1 in 2.94* 105 (95 % CI: 1 in 4.4* 101 to 1 in 8.86*1018) (<1%) at an RQ of
0.10 (Agricultural Uncultivated Areas, small insectivore mammals weighing 15g, 238 g
CRLF) to approximately 1 in 1 (95 % CI: 1 in 1.02 to 1 in 1) (100%) at an RQ of 10.3
(Agricultural Uncultivated Areas, small herbivore mammals weighing 15g, 37g CRLF)
(Table 5-19). This range of RQs is relevant to all sizes of CRLF consuming small
insects, and small herbivore and insectivore mammals (mammals weighing 15g), for uses
in which there were exceedances. This range is not relevant to CRLF (of any size)
consuming large insects or small terrestrial-phase amphibians modeled for any use
scenario since there were no LOC exceedances.
Using the refined acute dose-based RQs for CRLF consuming different food items the
chance of individual mortality for which the RQs exceed the LOC (0.1) range from
approximately 1 in 9.56* 103 (95 % CI: 1 in 2.01 *101 to 1 in 1.65*1013) (<1%) at anRQ
0.15 (Forest Tree/Pest Management, small insects 238g CRLF) to approximately 1 in 1
(95 % CI: 1 in 1.01 to 1 in 1) (100%) at an RQ of 16.61 (Agricultural Uncultivated Areas,
small herbivore mammals weighing 35g, 37g CRLF) (Table 5-20). This range of RQs is
relevant to all sizes of CRLF consuming small insects, and small herbivore and
insectivore mammals (mammals weighing 35g), for uses in which there were LOC
exceedances. This range is not relevant to CRLF (of any size) consuming large insects or
small terrestrial-phase amphibians modeled for any use scenario since there were no LOC
exceedances.
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Chronic Exposures
Refined chronic dietary-based RQs for CRLFs consuming small insects using the T-
HERPS model exceed the chronic species LOG (1.0) for all foliar application uses of
triclopyr except rice (Table 5-21). Refined chronic dietary-based RQs for CRLFs
consuming small herbivore mammals (either 15g or 35g) exceed the chronic species LOG
(1.0) for all foliar application uses of triclopyr (Table 5-21). Refined chronic dietary-
based RQs for CRLFs consuming large insects, small insectivore mammals (either 15g or
35g), and small terrestrial-phase amphibians (weighing 2.3g) exceed the chronic species
LOG (1.0) for foliar uses of triclopyr with application rates greater than or equal to 8 Ib
ae/A (Table 5-21). The recommended mitigated maximum foliar application rate of 9 Ibs
ae/A would still result in exceedances of the Agency's chronic LOG of 1.0 for the refined
dietary-based RQs for CRLFs consuming small and large insects, small herbivore and
insective mammals (weighing 15g and 35g), and small terrestrial-phase amphibians
(Table 5-21). Therefore, there is still potential for direct effects to the terrestrial-phase
CRLF even at the mitigated maximum application rate.
Table 5-21 Refined Chronic Dietary-based RQs* for CRLF consuming different
food items (RQs calculated using T-HERPS), the weights of small herbivore and
insectivore mammals are 15 g and 35 g (Foliar applications).
Scenario
Agricultural Uncultivated Areas
(20 Ib ae/acre; 17 times/yr; 21 day
intervals) (Max-Foliar)
Forest Tree/Pest Management
(8 Ib ae/acre; 17 times/yr; 21 day
intervals) (Median-Foliar)
Douglas-Fir (Forest/Shelterbelt)
(1.5 Ib ae/acre; 17 times/yr; 21 day
intervals) (Median-Foliar)
Rice
(0.38 Ib ae/acre; 2 times/yr; 21 day
intervals) (Min-Foliar)
Weight of
mammals
(herbivore &
insectivore)
15g
35g
15g
35g
15g
35g
15g
35g
Small
Insects
79.29
79.29
31.71
31.71
5.95
5.95
0.85
0.85
Large
Insects
8.81
8.81
3.52
3.52
0.66
0.66
0.09
0.09
Small
Herbivore
Mammals
134.39
92.88
53.76
37.15
10.08
6.97
1.44
1.00
Small
Insectivore
Mammals
8.40
5.81
3.36
2.32
0.63
0.44
0.09
0.06
Small
Terrestrial
Phase
Amphibians
2.75
2.75
1.10
1.10
0.21
0.21
0.03
0.03
*RQs exceeding the Listed LOG (1 .0) are bolded and shaded
In the available chronic study where Mallard duck were exposed to triclopyr, the NOAEC
was 100 ppm and the LOAEC was 200 ppm, based on effects to the number of 14-day
old survivors. In comparing the LOAEC to the refined dietary-based EECs for CRLF
small insects and small herbivore mammals indicate that the EECs for all uses except rice
exceed the concentration where reproductive effects were observed within the laboratory.
For CRLF consuming large insects or small insectivore mammals (15g or 35g mammals)
and an application rate of triclopyr greater than or equal to 8 Ib ae/A, exceed the
concentration where reproductive effects were observed within the laboratory. CRLFs
consuming small terrestrial-phase amphibians exceed the concentration where
reproductive effects were observed in the lab at the maximum application rate (20 Ibs
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ae/A) only. All other uses except those previously listed have EECs which do not exceed
the LOAEC. Therefore, for some CRLF feeding categories, triclopyr EECs are at levels
were reproductive effects were observed in birds, which serve as surrogates for the
CRLF. The recommended mitigated maximum foliar application rate of 9 Ibs ae/A
would still result in exceedances of the Agency's acute and chronic LOG of 0.1 and 1.0
respectively, indicating that there is still potential for direct effects to the terrestrial-phase
CRLF at the recommended mitigated maximum application rate.
Based on the lines of evidence, and on these refined acute and chronic risk quotients
(RQs) and their exceedances of the Agency's LOC a May Affect and Likely to
Adversely Affect (LAA) determination is made for triclopyr use in California.
5.2.2 Indirect Effects (via Reductions in Prey Base)
5.2.2.1 Algae (non-vascular plants)
As discussed in Section 2.5.3, the diet of CRLF tadpoles is composed primarily of
unicellular aquatic plants (i.e., algae and diatoms) and detritus. Indirect effects of
triclopyr to the aquatic-phase CRLF (tadpoles) via reduction in non-vascular aquatic
plants in its diet are based on peak EECs from the standard pond and the lowest acute
toxicity value for aquatic non-vascular plants. The Agency's LOC (1.0) is exceeded for
many uses of triclopyr in California. The aquatic non-vascular plant RQs range from
35.71 (lakes/ponds/reservoirs) to 0.08 (ornamental lawns and turf). Results are presented
in Table 5-2.
The fate characteristics indicate that triclopyr acid/anion is expected to be persistent in
aquatic environments. As a result, the primary food source for the aquatic-phase CRLF
(non-vascular aquatic plants) is expected to be affected.
One of the aquatic incidents that were reported involved impacts to aquatic vegetation.
An accidental misuse of triclopyr BEE, in AR, reported that aerial drift of Garlon 4
(triclopyr BEE) contaminated an adjacent pond which resulted in damage to some aquatic
vegetation (1005004-001). The California Department of Pesticide Regulation (CDPR)
has been collecting surface water data on triclopyr for many years. Samples were taken in
six California counties from March 1993 to March 2006. Out of 583 samples, 102
samples contained triclopyr. The median concentration of positive samples was 0.65 ppb
and the mean concentration was 1.7 ppb. The highest detected concentration of 14.5 ppb
was recorded on June 21, 2001 at Colusa Basin Drain #5 in Colusa County, which is an
area that is known for growing rice. Colusa County is one of four leading counties for
rice production in California. The Rice Model predicted a concentration of 763.00 ppb.
This is a little more than a magnitude larger, and shows how conservative the model is.
Because of non-vascular LOC exceedance from registered uses of triclopyr, the
presence of aquatic incident data, and because triclopyr's presence has been
observed in monitored surface water in California, the Agency concludes that there
is a potential of indirect impact to the aquatic-phase of the CRLF from reduction of
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food items (algae). Therefore, triclopyr May Affect and is Likely to Adversely
Affect (LAA) the CRLF.
5.2.2.2 Aquatic Invertebrates
The potential for triclopyr to elicit indirect effects to the CRLF via effects on freshwater
invertebrate food items is dependent on several factors including: (1) the potential
magnitude of effect on freshwater invertebrate individuals and populations; and (2) the
number of prey species potentially affected relative to the expected number of species
needed to maintain the dietary needs of the CRLF. Together, these data provide a basis
to evaluate whether the number of individuals within a prey species is likely to be
reduced such that it may indirectly affect the CRLF.
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.
Indirect acute effects to the aquatic-phase CRLF via effects to prey (invertebrates) in
aquatic habitats are based on peak EECs in the standard pond and the lowest acute
toxicity value for freshwater invertebrates. The acute RQs exceed the Agency's LOG for
listed species (0.05), for a majority of triclopyr uses, and range from 10.00
(Lakes/ponds/reservoirs) to 0.02 (ornamental lawns and turf) (Table 5-3). The estimated
probability of individual effect of triclopyr ranges from approximately 100%
(lakes/ponds/reservoirs) to 3.98 x 105 % (ornamental sod farm-turf), Table 5-3. Chronic
RQs do not exceed the Agency's chronic risk to species LOG (1.0) for freshwater
invertebrates for any triclopyr use, and range from 0.10 (lakes/ponds/reservoirs) to <0.01
(ornamental lawns and turf) (Table 5-3).
The California Department of Pesticide Regulation (CDPR) has been collecting surface
water data on triclopyr for many years. Samples were taken in six California counties
from March 1993 to March 2006. Out of 583 samples, 102 samples contained triclopyr.
The median concentration of positive samples was 0.65 ppb and the mean concentration
was 1.7 ppb.
Because of aquatic invertebrates LOC exceedances from registered uses of triclopyr,
and because triclopyr's presence has been observed in monitored surface water in
California, the Agency concludes that there is a potential indirect impact to the
aquatic-phase of the CRLF from a reduction of aquatic invertebrates (aquatic phase
amphibian food items). As a result, it is determined that triclopyr May Affect and is
Likely to Adversely Affect (LAA) the CRLF.
5.2.2.3 Fish and Aquatic-phase Frogs
As discussed in Section 2.5.3, the diet of CRLF also includes small fish and other
aquatic-phase frogs. Direct effects to the aquatic-phase CRLF are based on peak EECs in
the standard pond and the lowest acute toxicity value for freshwater fish. In order to
assess direct chronic risks to the CRLF, 60 day EECs and the lowest chronic toxicity
value for freshwater fish are used. The resulting RQs for the majority of triclopyr uses
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exceed the Agency's acute and chronic LOC's (0.05 and 1.0) for freshwater fish
(surrogates for the aquatic-phase CRLF) (Table 5-1). The acute RQs exceed the
Agency's LOG for listed species (0.05), and range from 9.62 (Lakes/ponds/reservoirs) to
0.02 (ornamental lawns and turf) (Table 5-1). The estimated probability of individual
effect of triclopyr ranges from approximately 100% (lakes/ponds/reservoirs) to 3.98 x 105
% (ornamental sod farm-turf), Table 5-1. The chronic RQs exceed the Agency's LOG
(1.0), and range from 131.58 (Lakes/ponds/reservoirs) to 0.21 (ornamental lawns and
turf), Table 5-1.
There were a total of three aquatic animal incidents that were reported for triclopyr, and
the certainty of triclopyr being responsible was possible, probable and highly probable.
These were the only reported aquatic incidents, and may be represent only a small portion
of potential impacts to non-target aquatic organisms as some effects may impair other
functions resulting in decreased survival (i.e. harder to escape predation). The California
Department of Pesticide Regulation (CDPR) has been collecting surface water data on
triclopyr for many years. Samples were taken in six California counties from March 1993
to March 2006. Out of 583 samples, 102 samples contained triclopyr. The median
concentration of positive samples was 0.65 ppb in the Colusa Basin and the mean
concentration was 1.7 ppb. This may be due to the use of triclopyr on rice. Colusa
County is one of four leading counties for rice production in California. The Rice Model
predicted a concentration of 763.00 ppb. This is a little more than a magnitude larger,
and shows how conservative the model is.
Because there are LOC exceedances from registered uses of triclopyr to the CRLF
surrogate species (freshwater fish) in California, verified non-target incidents
resulting from triclopyr use, and because triclopyr's presence has been observed in
monitored surface water in California, the Agency concludes that there is a
potential indirect impact to the aquatic-phase of the CRLF from a reduction of
aquatic phase amphibian food items. Therefore, triclopyr May Affect and is Likely
to Adversely Affect (LAA) the CRLF.
5.2.2.4 Terrestrial Invertebrates
When the terrestrial-phase CRLF reaches juvenile and adult stages, its diet is mainly
composed of terrestrial invertebrates. Terrestrial invertebrate toxicity data is used to
assess potential indirect effects of triclopyr to the terrestrial-phase CRLF. Effects to
terrestrial invertebrates resulting from exposure to triclopyr may also indirectly affect the
CRLF via reduction in available food.
Because the LDso was not definitive, and there was little incidence of mortality, RQs
were not calculated. However, EECs were compared to the highest concentration tested
100 jig/bee). All of estimated EEC's the level tested for all uses except rice for small
insects and all of the uses greater than 17 applications per year with 21 day intervals at 8
Ib ae/acre per application for large insects; therefore, a preliminary "May Affect"
determination was made. However, the calculated EEC's for Agricultural uncultivated
areas (7930 ppm small insects and 881 ppm large insects, Table 3-6) were 14.1 and 1.56
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times the level of triclopyr tested (>72 ug ae/bee, 562.5 ppm). Without a definitive
toxicity endpoint value, we cannot preclude risk to terrestrial invertebrate prey items.
Therefore, because the calculated terrestrial small insect EEC's exceed the highest
levels tested, the Agency concludes that there is a potential indirect impact to the
terrestrial-phase CRLF from a reduction of invertebrate food items and therefore
triclopyr is Likely to Adversely Affect (LAA) the CRLF.
5.2.2.5 Mammals
Life history data for terrestrial-phase CRLFs indicate that large adult frogs consume
terrestrial vertebrates, including mice. Small mammals can make up to 50% of the CRLF
food intake. Acute and chronic dose-based and chronic dietary-based RQs exceed the
Agency's acute and chronic risk LOCs (0.1 acute, 1.0 chronic) for all foliar application
uses of triclopyr (Table 5-9). The acute RQs range from 10.7 (Agricultural Uncultivated
Areas) to 0.11 (Rice), and the chronic RQs range from 1222.9 (Agricultural Uncultivated
Areas) to 13.1 (Rice) [Dose-based] and 141 (Agricultural Uncultivated Areas) to 1.51
(Rice) [Dietary-based]. The probability of individual effect at the acute endangered
species LOC (0.1) ranges from 1 in 1 (95%CI: 1 in 1.02 to 1 in 1) for Agricultural
uncultivated areas to 1 in 1.25*105(95% CI: 1 in 3.62*10^0 1 in 3.19 *1017) for rice.
The effect probability was calculated based on a default slope assumption of 4.5 with
upper and lower 95% confidence intervals of 2 and 9 (Urban and Cook, 1986).
Population reduction in small mammal prey items for the CRLF from application of
triclopyr ranges from 100% (agricultural uncultivated areas) to 0.0008% (rice) for foliar
applications of triclopyr. The probability of individual effect probit slope analysis is not
applicable for chronic endpoints. The dose-based and dietary-based EECs are well above
the levels mortality was documented at for all uses of triclopyr except rice (acute
endpoint), and all uses of triclopyr (chronic endpoint). Because environmental exposure
levels are estimated to be much higher than the level which may cause acute effects to
mammals, the CRLF may be indirectly affected by acute exposure of its mammal food
source to triclopyr. The recommended mitigated maximum foliar application rate of 9 Ibs
ae/A would still result in exceedances of the Agency's acute and chronic LOC of 0.1 and
1.0 respectively, indicating that there is still potential for indirect effects to the terrestrial-
phase CRLF via reduction in prey at the recommended mitigated maximum application
rate.
For granular uses of triclopyr the resulting LD50/ft2s for all granular application uses of
triclopyr exceed the Agency's acute endangered species LOC of 0.1 for mammals
weighing 15g and 35g, ranging from 0.83 (Commercial/Industrial Lawns) to 0.42
(Ornamental Lawns and Turf) for mammals weighing 15g, and 0.44
(Commercial/Industrial Lawns) to 0.22 (Ornamental Lawns and Turf) for mammals
weighing 35g (Table 5-10). The LD50/ft2 is calculated using a toxicity value (the adjusted
LDso) and the EEC (mg a.e./ft2), and is compared to the Agency's LOC. The probability
of individual effect at the endangered species LOC (0.1) ranges from 1 in 2.79 with a
95% CI of 1 in 2.3 to 1 in 4.29 (for Commercial/Industrial Lawns) to 1 in 2.22*101 with a
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95% CI of 1 in 4.43 to 1 in 2.87*103 (for Ornamental Lawns and Turf) for mammals
weighing 15 g. For mammals weighing 35g LD50/ft2 the probability of individual effect
at the endangered species LOG (0.1) ranges from 1 in 1.84*101 with a 95% CI of 1 in
4.20 to 1 in 1.5*103 (for Commercial/Industrial Lawns) to 1 in 6.48* 102 with a 95% CI of
1 in 1.06*!©1 to 1 in 6.14*108 (for Ornamental Lawns and Turf). The effect probability
was calculated based on a default slope assumption of 4.5 with upper and lower 95%
confidence intervals of 2 and 9 (Urban and Cook, 1986). Population reduction in small
mammal prey items for the CRLF from application of triclopyr ranges from 36%
(Commercial/Industrial Lawns) to 0.15% (Ornamental Lawns and Turf) for granular
applications of triclopyr to mammals weighing 15g and 35g.
As a Group D chemical triclopyr is unable to be classified as to human carcinogenicity,
based on marginal evidence of tumors in female rates and mice and benign adrenal
pheochromocytomas in male rats (HED 2002, Appendix M). Reproductive and sublethal
effects (increased incidence of F2 pups with exencephaly and ablepharia) were observed
in chronic mammalian studies, and resulted in RQ values that exceeded the LOG (1.0) for
all uses (both chronic dose- and dietary-based). The chronic dose-based RQs ranged
from 1222.9 (Agricultural uncultivated area, maximum application rate) to 13.1 (Rice,
minimum application rate), and the chronic dietary-based RQs ranged from 141
(Agricultural uncultivated area, maximum application rate) to 1.51 (Rice, minimum
application rate) (Table 5-9). The acute dose-based RQs ranged from 10.7 (Agricultural
uncultivated area, maximum application rate) to 0.11 (Rice, minimum application rate)
(Table 5-9). Triclopyr's toxicity, when combined in the diet is lower than the gavage
(dose) based treatment, indicating that the toxicity may be reduced in combination with
the diet. Chronic exposure from triclopyr is likely.
Based on effects to small mammals from both foliar and granular uses, there is a
potential indirect impact to the CRLF via reduction in small mammal prey items,
and therefore triclopyr May Affect and is Likely to Adversely Affect (LAA) the
CRLF.
5.2.2.6 Terrestrial-phase Amphibians
Terrestrial-phase adult CRLFs also consume frogs. RQ values representing direct
exposures of triclopyr to terrestrial-phase CRLFs are used to represent exposures of
triclopyr to frogs in terrestrial habitats. The T-HERPS model was therefore employed as a
refinement tool to explore amphibian-specific food intake on potential exposure to
terrestrial-phase amphibian food items for the CRLF. The T-HERPS model incorporates
the same inputs as T-REX with equations adjusted for poikilotherm food intake. As
described in Section 5.2.1.2, the refined acute RQs (dietary- and dose-based) for small
terrestrial-phase amphibians did not exceed the listed species LOG (0.1) for any use of
triclopyr. However, the refined chronic dietary-based RQs exceed the chronic species
LOG (1.0) for small terrestrial-phase amphibians (weighing 2.3g) for foliar uses of
triclopyr with application rates greater than or equal to 8 Ib ae/A (Table 5-19). Reduction
in amphibian prey items, specifically other frogs may potentially be affected from
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chronic exposure of triclopyr as the result of triclopyr use. Other items in the prey base
all had RQs that exceeded the listed species LOG for numerous uses of triclopyr. The
recommended mitigated maximum foliar application rate of 9 Ibs ae/A would still result
in exceedances of the Agency's acute and chronic LOG of 0.1 and 1.0 respectively,
indicating that there is still potential for direct effects to the terrestrial-phase CRLF at the
recommended mitigated maximum application rate.
Based on this evidence, a May Affect and is Likely to Adversely Affect (LAA)
determination is made for indirect effects via reductions in prey base of the
terrestrial-phase CRLF based on foliar application alone.
5.2.3 Indirect Effects (via Habitat Effects)
5.2.3.1 Aquatic Plants (Vascular and Non-vascular)
Aquatic plants serve several important functions in aquatic ecosystems. Non-vascular
aquatic plants are primary producers and provide the autochthonous energy base for
aquatic ecosystems. Vascular plants provide structure as attachment sites and refugia for
many aquatic invertebrates, fish, and juvenile organisms, such as fish and frogs. In
addition, vascular plants also provide primary productivity and oxygen to the aquatic
ecosystem. Rooted plants help reduce sediment loading and provide stability to
nearshore areas and lower streambanks. In addition, vascular aquatic plants are important
as attachment sites for egg masses of CRLFs.
Potential indirect effects to the CRLF based on impacts to habitat and/or primary
production were assessed using RQs from freshwater aquatic vascular and non-vascular
plant data. Indirect effects of triclopyr to the aquatic-phase CRLF (tadpoles) are present
in the reduction of non-vascular aquatic plants in the aquatic-phase CRLFs diet. The
Agency's LOG (1.0) for non-vascular plants is exceeded for most uses of triclopyr in
California. The non-vascular aquatic plant RQs range from 35.71 for
lakes/ponds/reservoirs to 0.08 for ornamental lawns and turf.
Indirect effects of triclopyr to the aquatic-phase CRLF (tadpoles) are also found via the
reduction in vascular aquatic plants in the aquatic-phase CRLFs diet. The Agency's LOG
(1.0) for vascular plants is exceeded for many uses of triclopyr in California. The acute
RQs range from 2.91 for lakes/ponds/reservoirs to 0.01 for ornamental lawns and turf
(Table 5-4).
An analysis of the fate characteristics of triclopyr indicates that triclopyr is expected to be
persistent in aquatic environments. As a result, the primary food source for the aquatic-
phase CRLF (both vascular and non-vascular aquatic plants) is expected to be adversely
affected.
One of the aquatic incidents that were reported involved impacts to aquatic vegetation.
An accidental misuse of triclopyr BEE, in AR, reported that aerial drift of Garlon 4
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(triclopyr BEE) contaminated an adjacent pond which resulted in damage to some aquatic
vegetation (1005004-001).
Because of the non-vascular aquatic plant LOC exceedances for registered uses of
triclopyr, and verified non-target incidents resulting from triclopyr use, the Agency
concludes that there is a potential of indirect impact to the aquatic-phase of the
CRLF from reduction of food items (algae). Therefore, triclopyr May Affect and is
Likely to Adversely Affect (LAA) the CRLF.
5.2.3.2 Terrestrial Plants
Terrestrial plants serve several important habitat-related functions for the CRLF. In
addition to providing habitat and cover for invertebrate and vertebrate prey items of the
CRLF, terrestrial vegetation also provides shelter for the CRLF and cover from predators
while foraging. Terrestrial plants also provide energy to the terrestrial ecosystem through
primary production. Upland vegetation including grassland and woodlands provides
cover during dispersal. Riparian vegetation helps to maintain the integrity of aquatic
systems by providing bank and thermal stability, serving as a buffer to filter out sediment,
nutrients, and contaminants before they reach the watershed, and serving as an energy
source.
The RQs for non-target terrestrial monocots and dicot plants inhabiting semi-aquatic
areas exceed the Agency's risk to terrestrial plant LOC (1.0) for all uses of triclopyr both
foliar (aerial and ground) and granular applications (Table 5-11 and Table 5-12). RQs for
non-target terrestrial monocots and dicot plants inhabiting upland dry areas exceed the
Agency's risk to terrestrial plant LOC (1.0) for all uses of triclopyr except rice both foliar
(aerial and ground) and granular applications (Table 5-11 and Table 5-12). Aerial foliar
applications of triclopyr result in spray drift RQ exceedances for non-target dicot species
for all uses of triclopyr (Table 5-11). Aerial foliar applications of triclopyr result in spray
drift RQ exceedances for monocots for all uses except rice (Table 5-11). Ground foliar
applications result in spray drift RQ exceedances for both monocots and dicots for all
uses except rice (Table 5-11). There were no spray-drift LOC exceedances for non-target
monocot or dicot plants from granular application of triclopyr (Table 5-12).
The recommended mitigated maximum foliar (ground and aerial) application rate of 9 Ibs
ae/A would still result in exceedances of the Agency's terrestrial plant LOC of 1.0 for
indirect effects to the terrestrial-phase CRLF (Table 5-11). RQs for non-target terrestrial
monocots and dicot plants inhabiting semi-aquatic and upland dry areas would still result
in exceedances in the terrestrial plant LOC (1.0) (Table 5-11). Aerial and ground foliar
applications would also still result in spray drift RQ exceedances for non-target terrestrial
monocots and dicot plants (Table 5-11). Thus, indicating that there is still potential for
indirect effects to the terrestrial-phase CRLF via habitat degradation at the recommended
mitigated maximum application rate.
There were a total of 60 incidents that have been reported for triclopyr for non-target
plants, listed under triclopyr (unknown triclopyr - 8), TEA (37), and BEE (15). Some of
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these incidents are the result of spray drift or overspray of triclopyr onto non-target plants
within the vicinity of the application site, at least 15 of 60, (1014404-019,1014404-018,
1014409-009,1007875-001,1007834-039,1002507-001,1008884-001,1003581-001,
1008077-001,1013550-006,1012209-003,1011622-003,1016940-015,1013645-010, and
1013550-007). The incidents involve registered uses, accidental misuses, misuses, and
those of undetermined legality, with triclopyr ranging from being possibly responsible to
highly probably responsible for the incidents.
Based on LOC exceedances in spray drift RQs for both monocots and dicots, RQ
exceedances for both monocots and dicots inhabiting semi-aquatic and upland dry
habitats, and verified non-target incidents resulting from triclopyr use, triclopyr
May Affect and is Likely to Adversely Affect (LAA) the CRLF indirectly via habitat
degradation through reduction in terrestrial plants.
5.2.4 Modification to Designated Critical Habitat
5.2.4.1 Aquatic-Phase PCEs
Three of the four assessment endpoints for the aquatic-phase primary constituent
elements (PCEs) of designated critical habitat for the CRLF are related to potential
effects to aquatic and/or terrestrial plants:
• Alteration of channel/pond morphology or geometry and/or increase in sediment
deposition within the stream channel or pond: aquatic habitat (including riparian
vegetation) provides for shelter, foraging, predator avoidance, and aquatic
dispersal for juvenile and adult CRLFs.
• Alteration in water chemistry/quality including temperature, turbidity, and
oxygen content necessary for normal growth and viability of juvenile and adult
CRLFs and their food source.
• Reduction and/or modification of aquatic-based food sources for pre-metamorphs
(e.g., algae).
Conclusions for potential indirect effects to the CRLF via direct effects to aquatic and
terrestrial plants are used to determine whether modification to critical habitat may occur.
LOCs are exceeded for terrestrial riparian plants and for aquatic plants from exposure to
triclopyr from spray drift. Alteration of riparian and vascular plants may result in
alteration of temperature, turbidity, and oxygen content.
Aquatic non-vascular plants used as a food source and habitat for CRLF may be
potentially affected from many triclopyr uses. A reduction in these aquatic based food
sources may occur from most use sites. Likewise, due to aquatic vascular and terrestrial
plant communities being reduced from most use sites, there is potential for alteration of
channel/pond morphology or geometry and/or increase in sediment deposition within the
stream channel or pond.
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The remaining aquatic-phase PCE is "alteration of other chemical characteristics
necessary for normal growth and viability of CRLFs and their food source." Other than
impacts to algae as food items for tadpoles (discussed above), this PCE is assessed by
considering direct and indirect effects to the aquatic-phase CRLF via acute and chronic
freshwater fish and invertebrate toxicity endpoints as measures of effects.
Based on acute LOC exceedances for aquatic plants triclopyr will result in habitat
modification based on effects to aquatic-phase PCEs of designated critical habitat
related to effects of alteration of other chemical characteristics necessary for normal
growth and viability of CRLFs and their food source. Therefore, triclopyr is likely
to result in habitat modification.
5.2.4.2 Terrestrial-Phase PCEs
Two of the four assessment endpoints for the terrestrial-phase PCEs of designated critical
habitat for the CRLF are related to potential effects to terrestrial plants:
• Elimination and/or disturbance of upland habitat; ability of habitat to support food
source of CRLFs: Upland areas within 200 ft of the edge of the riparian
vegetation or drip line surrounding aquatic and riparian habitat that are comprised
of grasslands, woodlands, and/or wetland/riparian plant species that provides the
CRLF shelter, forage, and predator avoidance.
• Elimination and/or disturbance of dispersal habitat: Upland or riparian dispersal
habitat within designated units and between occupied locations within 0.7 mi of
each other that allow for movement between sites including both natural and
altered sites which do not contain barriers to dispersal.
There is a potential for habitat effects via impacts to terrestrial plants (Section
5.2.3.2) from triclopyr use (both aerial and ground applications).
The risk estimation for terrestrial-phase PCEs of designated habitat related to potential
effects on terrestrial plants is provided in Section 5.1.2.3. These results will inform the
effects determination for effects to designated critical habitat for the CRLF.
The third terrestrial-phase PCE is "reduction and/or modification of food sources for
terrestrial phase juveniles and adults." To assess the impact of triclopyr on this PCE,
acute and chronic toxicity endpoints for terrestrial invertebrates, mammals, and
terrestrial-phase frogs are used as measures of effects. There is potential for habitat
effects via indirect effects to terrestrial-phase CRLFs via reduction in prey base
(Section 5.2.2.4 for terrestrial invertebrates, Section 5.2.2.5 for mammals, and 0 for
frogs.
The fourth terrestrial-phase PCE is based on alteration of chemical characteristics
necessary for normal growth and viability of juvenile and adult CRLFs and their food
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source. Direct acute and chronic RQs for terrestrial-phase CRLFs are presented in
Section 5.2.1.2. There is potential for habitat effects via direct (Section 5.2.1.2) and
indirect effects (Sections 5.2.2.4, 5.2.2.5, and 5.2.2.6) to terrestrial-phase CRLFs
from triclopyr use. Triclopyr use may result in habitat effects based on effects to
terrestrial PCEs related to alteration of chemical characteristics necessary for
normal growth and viability.
5.2.5 Spatial Extent of Potential Effects
An LAA effects determination applies to those areas where it is expected that the
pesticide's use will directly or indirectly affect the CRLF or its designated critical habitat.
To determine this area, the footprint of triclopyr's use pattern is identified, using land
cover data that correspond to triclopyr's use pattern. Areas of potential exposure also
include areas beyond the initial area of concern (e.g, use footprint) that may be impacted
by runoff and/or spray drift. The identified direct/indirect effects and/or modification to
critical habitat are anticipated to occur only for those currently occupied core habitat
areas, CNDDB occurrence sections, and designated critical habitat for the CRLF that
overlap with the initial area of concern plus at least 1,000 feet from its boundary for
terrestrial uses. Since the aquatic uses are applied directly to water, a boundary cannot be
established. It is assumed that non-flowing waterbodies (or potential CRLF habitat) are
included within this area.
In addition to the spray drift buffer, a downstream dilution extent analysis is usually
performed to represents the maximum continuous distance of downstream dilution from
the edge of the initial area of concern. However, since triclopyr acid has direct water
body applications, these streams flow will reach the CRLF habitat, and potentially affect
either the CRLF or modify its habitat. These lotic aquatic habitats within the CRLF core
areas and critical habitats potentially contain concentrations of triclopyr acid sufficient to
result in LAA determination or modification of critical habitat.
The determination of the buffer distance and downstream dilution for spatial extent of the
effects determination is described below.
5.2.5.1 Spray Drift
In order to determine terrestrial and aquatic habitats of concern due to triclopyr exposures
through spray drift, it is necessary to estimate the distance that spray applications can
drift from the treated area and still be present at concentrations that exceed levels of
concern. An analysis of spray drift distances was completed using AgDrift.
For triclopyr use relative to the terrestrial-phase CRLF, the results of the screening-level
risk assessment indicate that spray drift using the most sensitive endpoints for terrestrial
plants exceeds the 1,000 foot range of the AgDrift model.
The AgDISP model was run in ground mode and aerial mode (for non-cropland use only)
with the following settings beyond the standard default settings.
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• 20 gal/acre spray volume rate (label specific)
• Very fine to fine spectrum (default value)
• No canopy
• Nonvolatile fraction of 0.491.
• Volatile fraction 0.119.
In order to characterize the spatial extent of the effects determination that is relevant to
the CRLF (i.e. NLAA versus LAA), an analysis was conducted using the most sensitive
non-endangered plant £€25 of 0.005 Ibs ae/acre (Sunflower, Vegetative Vigor) and a
NOAEC of 0.0028 Ib ae/acre. Typically the NOAEC is used when there is an obligate
relationship between the species being assessed and endangered plants (or other taxa).
However, there is no obligate relationship between the CRLF and any endangered plant;
therefore the LAA/NLAA determination is based on the area defined by the non-listed
species LOG (i.e., EEC/ECso).
The estimated buffer distance identifies those locations where terrestrial landscapes can
be impacted by spray drift deposition alone (no runoff considered) at concentrations
above the LOG for terrestrial plants. The LOG was compared to the highest RQ for aerial
applications at 12.0 Ibs ae/acre. The maximum distance for the aerial use of triclopyr at
12.0 Ibs ae/acre is at least 1,000 feet.
An aquatic analysis was not performed because triclopyr is applied directly to water. As
a result, there would not be an aquatic buffer distance established.
A summary of the terrestrial buffer analyses are listed below in Table 5-22.
Table 5-22 Summary of AgDRIFT Predicted Terrestrial Spray Drift Distances
Terrestrial Assessment
Tier I Ground Application
Risk
Class
Non-
Listed
Plants
Listed
Plants
Risk Description
Potential for
effects to non-
target, non-listed
plants from
exposures
Potential for
effects to non-
target, listed
plants from
exposures
App.
Rate (Ib
ae/acre)
20
Toxicity Value
Used
EC25 = 0.005 Ib
ae/A Sunflower
(Vegetative Vigor)
NOAEC= 0.0028
Ib ae/A Sunflower
(Vegetative Vigor)
Initial Avg
Cone.
(PPt)
0.0003
0.0001
Non-volatile
Rate (Ib/a)
Does not
apply
Min. Spray
Volume
Rate (gal/a)
Does not
apply
Active
Rate (Ib
ae/a)
Does not
apply
Distance
(feet)
> 1,000
> 1,000
Tier I Aerial Application
Risk Risk
Class Description
Potential for
effects to non-
Non- target, non-
Listed listed plants
Plants from exposures
App.
Rate (Ib
ae/acre)
12
Toxicity Value
Used
EC25 = 0.005 Ib
ae/A Sunflower
(Vegetative Vigor)
Initial Avg
Cone.
(PPt)
0.0003
Non-volatile
Rate (Ib/a)
Does not
apply
Min. Spray
Volume
Rate (gal/a)
Does not
apply
Active
Rate (Ib
ae/a)
Does not
apply
Distance
(feet)
> 1,000
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Listed
Plants
Potential for
effects to non-
target, listed
plants from
exposures
NOAEC= 0.0028
Ib ae/A Sunflower
(Vegetative Vigor)
0.0001
> 1,000
Tier II Aerial Application
Risk
Class
Non-
Listed
Plants
Listed
Plants
Risk
Description
Potential for
effects to non-
target, non-
listed plants
from exposures
Potential for
effects to non-
target, listed
plants from
exposures
App.
Rate (Ib
ae/acre)
12
Toxicity Value
Used
EC25 = 0.005 Ib
ae/A Sunflower
(Vegetative Vigor)
NOAEC= 0.0028
Ib ae/A Sunflower
(Vegetative Vigor)
Initial Avg
Cone.
(PPt)
0.0003
0.0001
Non-volatile
Rate (Ib/a)
0.491
Min. Spray
Volume
Rate (gal/a)
20
Active
Rate (Ib
ae/a)
0.119
Distance
(feet)
> 1,000
> 1,000
5.2.5.2 Downstream Dilution Analysis
In order to determine the downstream extent of exposure in streams and rivers where the
EEC could potentially be above levels that would exceed the most sensitive LOG, the
greatest ratio of aquatic RQ to LOG would be estimated. However, due to having direct
applications to water for triclopyr acid, it was determined that a downstream dilution
analysis is not applicable in this case since it can be applied to any location within the
water body. It is not just being transported as runoff across the landscape, into non-
impacted water. The water body may be directly impacted already; therefore, possibly
increasing the concentration downstream and not diluting it.
5.2.5.3 Overlap between CRLF habitat and Spatial Extent of Potential
Effects
An LAA effects determination is made to those areas where it is expected that the
pesticide's use will directly or indirectly affect the CRLF or its designated critical habitat
and the area overlaps with the core areas, critical habitat and available occurrence data
for CRLF.
For triclopyr, the use pattern in the following land cover classes (cultivated crops,
developed high/low intensity areas, open space, wetlands, open water, pasture/hay,
forests, and orchards/vineyards) also includes areas beyond the initial area of concern that
may be impacted by runoff and/or spray drift overlaps with CRLF habitat. Appendix D
provides maps of the initial area of concern, along with CRLF habitat areas, including
currently occupied core areas, CNDDB occurrence sections, and designated critical
habitat. It is expected that any additional areas of CRLF habitat that are located at least
1000 ft (to account for offsite migration via spray drift for terrestrial uses) outside the
initial area of concern may also be impacted and are part of the full spatial extent of the
LAA/modification of critical habitat effects determination. The effects area only includes
those areas where predicted exposure and habitat overlap. See Figure 5-1 for a visual of
where the CRLF habitat and the use of triclopyr may overlap.
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Potential Triclopyr Use and CRLF Habitat Overlap
Legend
CA counties
^^| potential use overlap
CNDDB occurrence sections
^^| Critical habitat
Core areas
i Kilo meters
0 1530 60 90 120
Compiled from California County boundaries (ESRI. 2002),
US DA Gap Analysis Program Orchard/Vineyard Landcover (GAP)
National Land Cover 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).
9/2009
Figure 5-1 Overlap Map: CRLF Habitat and Triclopyr Initial Area of Concern
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6.0 Uncertainties
6.1 Exposure Assessment Uncertainties
6.1.1 Maximum Use Scenario
The screening-level risk assessment focuses on characterizing potential ecological risks
resulting from a maximum use scenario, which is determined from labeled statements of
maximum application rate and number of applications with the shortest time interval
between applications. The frequency at which actual uses approach this maximum use
scenario may be dependant on pest resistance, timing of applications, cultural practices,
and market forces.
6.1.2 Aquatic Exposure Modeling of Triclopyr
The standard ecological water body scenario (EXAMS pond) used to calculate potential
aquatic exposure to pesticides is intended to represent conservative estimates, and to
avoid underestimations of the actual exposure. The standard scenario consists of
application to a 10-hectare field bordering a 1-hectare, 2-meter deep (20,000 m3) pond
with no outlet. Exposure estimates generated using the EXAMS pond are intended to
represent a wide variety of vulnerable water bodies that occur at the top of watersheds
including prairie pot holes, playa lakes, wetlands, vernal pools, man-made and natural
ponds, and intermittent and lower order streams. As a group, there are factors that make
these water bodies more or less vulnerable than the EXAMS pond. Static water bodies
that have larger ratios of pesticide-treated drainage area to water body volume would be
expected to have higher peak EECs than the EXAMS pond. These water bodies will be
either smaller in size or have larger drainage areas. Smaller water bodies have limited
storage capacity and thus may overflow and carry pesticide in the discharge, whereas the
EXAMS pond has no discharge. As watershed size increases beyond 10-hectares, it
becomes increasingly unlikely that the entire watershed is planted with a single crop that
is all treated simultaneously with the pesticide. Headwater streams can also have peak
concentrations higher than the EXAMS pond, but they likely persist for only short
periods of time and are then carried and dissipated downstream.
The Agency acknowledges that there are some unique aquatic habitats that are not
accurately captured by this modeling scenario and modeling results may, therefore,
under- or over-estimate exposure, depending on a number of variables. For example,
aquatic-phase CRLFs may inhabit water bodies of different size and depth and/or are
located adjacent to larger or smaller drainage areas than the EXAMS pond. The Agency
does not currently have sufficient information regarding the hydrology of these aquatic
habitats to develop a specific alternate scenario for the CRLF. CRLFs prefer habitat with
perennial (present year-round) or near-perennial water and do not frequently inhabit
vernal (temporary) pools because conditions in these habitats are generally not suitable
(Hayes and Jennings 1988). Therefore, the EXAMS pond is assumed to be representative
of exposure to aquatic-phase CRLFs. In addition, the Services agree that the existing
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EXAMS pond represents the best currently available approach for estimating aquatic
exposure to pesticides (U.S. FWS/NMFS 2004).
In general, the linked PRZM/EXAMS model produces estimated aquatic concentrations
that are expected to be exceeded once within a ten-year period. The Pesticide Root Zone
Model is a process or "simulation" model that calculates what happens to a pesticide in
an agricultural field on a day-to-day basis. It considers factors such as rainfall and plant
transpiration of water, as well as how and when the pesticide is applied. It has two major
components: hydrology and chemical transport. Water movement is simulated by the use
of generalized soil parameters, including field capacity, wilting point, and saturation
water content. The chemical transport component can simulate pesticide application on
the soil or on the plant foliage. Dissolved, adsorbed, and vapor-phase concentrations in
the soil are estimated by simultaneously considering the processes of pesticide uptake by
plants, surface runoff, erosion, decay, volatilization, foliar wash-off, advection,
dispersion, and retardation.
The Tier 1 Rice Model used to calculate potential aquatic exposure to pesticides is
intended to represent conservative screening estimates, and to avoid underestimations of
the actual exposure. The standard scenario consists of application to a 10 centimeter rice
paddy. This model represents peak concentrations for rice paddies after partitioning into
sediment. The Tier 1 Rice Model produces estimated aquatic concentrations that are
expected to be exceeded to be peak concentrations. It does not consider factors beyond
initial concentration assumed instantaneous partitioning. Chemical transport is not
factored into the Tier 1 Rice Model results.
Uncertainties associated with each of these individual components add to the overall
uncertainty of the modeled concentrations. Additionally, model inputs from the
environmental fate degradation studies are chosen to represent the upper confidence
bound on the mean values that are not expected to be exceeded in the environment
approximately 90 percent of the time. Mobility input values are chosen to be
representative of conditions in the environment. The natural variation in soils adds to the
uncertainty of modeled values. Factors such as application date, crop emergence date,
and canopy cover can also affect estimated concentrations, adding to the uncertainty of
modeled values. Factors within the ambient environment such as soil temperatures,
sunlight intensity, antecedent soil moisture, and surface water temperatures can cause
actual aquatic concentrations to differ for the modeled values.
Unlike spray drift, tools are currently not available to evaluate the effectiveness of a
vegetative setback on runoff and loadings. The effectiveness of vegetative setbacks is
highly dependent on the condition of the vegetative strip. For example, a well-
established, healthy vegetative setback can be a very effective means of reducing runoff
and erosion from agricultural fields. Alternatively, a setback of poor vegetative quality
or a setback that is channelized can be ineffective at reducing loadings. Until such time
as a quantitative method to estimate the effect of vegetative setbacks on various
conditions on pesticide loadings becomes available, the aquatic exposure predictions are
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likely to overestimate exposure where healthy vegetative setbacks exist and
underestimate exposure where poorly developed, channelized, or bare setbacks exist.
In order to account for uncertainties associated with modeling, available monitoring data
were compared to PRZM/EXAMS estimates of peak EECs for the different uses. The
NAWQA database did not have any samples containing triclopyr for both groundwater
and surface water. The CDPR collected samples of triclopyr from surface water in six
California counties from March 1993 to March 2006. Out of 583 samples, 102 samples
contained triclopyr. The highest concentration detected was 14.5 ppb. This value is
approximately 167 times less than the maximum model-estimated environmental
concentration (2500 ppb). The mean concentration for all counties was found to be 1.7
ppb. Although, the specific use patterns (e.g. application rates and timing, crops)
associated with the agricultural areas and reflected in the monitoring data are unknown,
however, they are assumed to be representative of potential triclopyr use areas.
The monitoring data available are below the Tier 1 Rice Model predictions by an order of
magnitude. Rice Model prediction estimated triclopyr to be in the surface waters at peak
concentrations of 763 ppb.
6.1.3 Potential Groundwater Contributions to Surface Water Chemical
Concentrations
Although the potential impact of discharging ground water on CRLF populations is not
explicitly delineated, it should be noted that, in some areas of the country, ground water
could provide a source of pesticide to surface water bodies - especially low-order
streams, headwaters, and ground water-fed pools. This is particularly likely if the
chemical is persistent and mobile, the pesticide is applied to highly permeable soils
overlying shallow unconfmed ground water, and rainfall is sufficient to drive the
chemical through the soil to ground water. Soluble chemicals that are primarily subject
to photolytic degradation will be very likely to persist in ground water, and can be
transportable over long distances. Similarly, many chemicals degrade slowly under
anaerobic conditions (common in aquifers) and are thus more persistent in ground water.
Under the right hydrologic conditions, this ground water may eventually be discharged to
the surface - often supporting stream flow in the absence of rainfall. Continuously
flowing low-order streams in particular are sustained by ground water discharge, which
can constitute 100% of stream flow during base flow (no runoff) conditions. Thus, it is
important to keep in mind that pesticides in ground water may impact surface water
quality during base flow conditions with subsequent impact on CRLF habitats. However,
many smaller streams in CA are net dischargers of water to ground water that go dry
during portions of the year and are not supplied by base flow from ground water.
Although concentrations in a receiving water body resulting from ground water discharge
cannot be explicitly quantified, it should be assumed that significant attenuation and
retardation of the chemical will have occurred prior to discharge. Nevertheless, where
triclopyr is applied to highly permeable soils over shallow ground water where there is a
net recharge to adjacent streams, ground water could still be a consistent source of
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chronic background concentrations in surface water, and may also add to surface runoff
during storm events (as a result of enhanced ground water discharge typically
characterized by the 'tailing limb' of a storm hydrograph).
6.1.4 Usage Uncertainties
County-level usage data were obtained from California's Department of Pesticide
Regulation Pesticide Use Reporting (CDPR PUR) database. Eight years of data (1999 -
2006) were included in this analysis because statistical methodology for identifying
outliers, in terms of area treated and pounds applied, was provided by CDPR for these
years only. No methodology for removing outliers was provided by CDPR for 2001 and
earlier pesticide data; therefore, this information was not included in the analysis because
it may misrepresent actual usage patterns. CDPR PUR documentation indicates that
errors in the data may include the following: a misplaced decimal; incorrect measures,
area treated, or units; and reports of diluted pesticide concentrations. In addition, it is
possible that the data may contain reports for pesticide uses that have been cancelled.
The CPDR PUR data does not include home owner applied pesticides; therefore,
residential uses are not likely to be reported. As with all pesticide usage data, there may
be instances of misuse and misreporting. The Agency made use of the most current,
verifiable information; in cases where there were discrepancies, the most conservative
information was used.
6.1.5 Terrestrial Exposure Modeling of Triclopyr
The Agency relies on the work of Fletcher et al. (1994) for setting the assumed pesticide
residues in wildlife dietary items. These residue assumptions are believed to reflect a
realistic upper-bound residue estimate, although the degree to which this assumption
reflects a specific percentile estimate is difficult to quantify. It is important to note that
the field measurement efforts used to develop the Fletcher estimates of exposure involve
highly varied sampling techniques. It is entirely possible that much of these data reflect
residues averaged over entire above ground plants in the case of grass and forage
sampling.
It was assumed that ingestion of food items in the field occurs at rates commensurate
with those in the laboratory. Although the screening assessment process adjusts dry-
weight estimates of food intake to reflect the increased mass in fresh-weight wildlife food
intake estimates, it does not allow for gross energy differences. Direct comparison of a
laboratory dietary concentration- based effects threshold to a fresh-weight pesticide
residue estimate would result in an underestimation of field exposure by food
consumption by a factor of 1.25 - 2.5 for most food items.
Differences in assimilative efficiency between laboratory and wild diets suggest that
current screening assessment methods do not account for a potentially important aspect of
food requirements. Depending upon species and dietary matrix, bird assimilation of wild
diet energy ranges from 23 - 80%, and mammal's assimilation ranges from 41 - 85%
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(U.S. EPA 1993). If it is assumed that laboratory chow is formulated to maximize
assimilative efficiency (e.g., a value of 85%), a potential for underestimation of exposure
may exist by assuming that consumption of food in the wild is comparable with
consumption during laboratory testing. In the screening process, exposure may be
underestimated because metabolic rates are not related to food consumption.
For the terrestrial exposure analysis of this risk assessment, a generic bird or mammal
was assumed to occupy either the treated field or adjacent areas receiving a treatment rate
on the field. Actual habitat requirements of any particular terrestrial species were not
considered, and it was assumed that species occupy, exclusively and permanently, the
modeled treatment area. Spray drift model predictions suggest that this assumption leads
to an overestimation of exposure to species that do not occupy the treated field
exclusively and permanently.
6.1.5.1 Granular Composition Uncertainty
The granular formulations of triclopyr cannot be further refined to determine the number
of granules it would take birds (surrogate for the terrestrial-phase CRLF) to reach the
LD50 as they are incorporated into fertilizers. No information can be provided regarding
the specific amount or size of a single granule of triclopyr as the liquid form of triclopyr
is mixed with the fertilizer product. An approximate range of granule sizes, and the
percent active ingredient within each product was obtained from the registrant, but due to
the chemical formulation of the fertilizers it is not possible to obtain more information
regarding the weight of one granule for further characterization of terrestrial exposure of
birds (surrogates for the terrestrial-phase CRLF) in relation to granular applications of
triclopyr.
6.1.6 Spray Drift Modeling
Although there may be multiple triclopyr applications at a single site, it is unlikely that
the same organism would be exposed to the maximum amount of spray drift from every
application made. In order for an organism to receive the maximum concentration of
triclopyr from multiple applications, each application of triclopyr would have to occur
under identical atmospheric conditions (e.g., same wind speed and - for plants - same
wind direction) and (if it is an animal) the animal being exposed would have to be present
directly downwind at the same distance after each application. Although there may be
sites where the dominant wind direction is fairly consistent (at least during the relatively
quiescent conditions that are most favorable for aerial spray applications), it is
nevertheless highly unlikely that plants in any specific area would receive the maximum
amount of spray drift repeatedly. It appears that in most areas (based upon available
meteorological data) wind direction is temporally very changeable, even within the same
day. Additionally, other factors, including variations in topography, cover, and
meteorological conditions over the transport distance are not accounted for by the
AgDRIFT model (i.e., it models spray drift from aerial and ground applications in a flat
area with little to no ground cover and a steady, constant wind speed and direction).
Therefore, in most cases, the drift estimates from AgDRIFT may overestimate exposure
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even from single applications, especially as the distance increases from the site of
application, since the model does not account for potential obstructions (e.g., large hills,
berms, buildings, trees, etc.). Furthermore, conservative assumptions are often made
regarding the droplet size distributions being modeled ('ASAE Very Fine to Fine' for
orchard uses and 'ASAE Very Fine' for agricultural uses), the application method (e.g.,
aerial), release heights and wind speeds. Alterations in any of these inputs would change
the area of potential effect.
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. The acute toxicity data for fish are collected on
juvenile fish between 0.1 and 5 grams. Aquatic invertebrate acute testing is performed on
recommended immature age classes (e.g., first instar for daphnids, second instar for
amphipods, stoneflies, mayflies, and third instar for midges).
Testing of juveniles may overestimate toxicity at older age classes for pesticide active
ingredients that act directly without metabolic transformation because younger age
classes may not have the enzymatic systems associated with detoxifying xenobiotics. In
so far as the available toxicity data may provide ranges of sensitivity information with
respect to age class, this assessment uses the most sensitive life-stage information as
measures of effect for surrogate aquatic animals, and is therefore, considered as
protective of the CRLF.
6.2.2 Use of Surrogate Species Effects Data
Guideline toxicity test data for triclopyr are not available for frogs or any other aquatic-
phase amphibian; therefore, freshwater fish are used as surrogate species for aquatic-
phase amphibians. Although no data are available for triclopyr, the available open
literature information on triclopyr is not applicable for use within the assessment as the
quality of the experiments is not scientifically sound. Therefore, endpoints based on
freshwater fish ecotoxicity data are assumed to be protective of potential direct effects to
aquatic-phase amphibians including the CRLF, and extrapolation of the risk conclusions
from the most sensitive tested species to the aquatic-phase CRLF is likely to overestimate
the potential risks to those species. Efforts are made to select the organisms most likely
to be affected by the type of compound and usage pattern; however, there is an inherent
uncertainty in extrapolating across phyla. In addition, the Agency's LOCs are
intentionally set very low, and conservative estimates are made in the screening level risk
assessment to account for these uncertainties.
6.2.3 Sublethal Effects
When assessing acute risk, the screening risk assessment relies on the acute mortality
endpoint as well as a suite of sublethal responses to the pesticide, as determined by the
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testing of species response to chronic exposure conditions and subsequent chronic risk
assessment. Consideration of additional sublethal data in the effects determination t is
exercised on a case-by-case basis and only after careful consideration of the nature of the
sublethal effect measured and the extent and quality of available data to support
establishing a plausible relationship between the measure of effect (sublethal endpoint)
and the assessment endpoints. However, the full suite of sublethal effects from valid
open literature studies is considered for the purposes of defining the action area.
No open literature data on sublethal effects more toxic than the most sensitive endpoint
were found. However, mammalian reproductive and sublethal effects (including
increased incidence of F2 pups with exencephaly and ablepharia) were observed in
chronic mammalian toxicity studies (Appendix M). Without the inclusion of sublethal
effects potential direct and indirect effects of triclopyr on CRLF may be underestimated.
6.2.4 Location of Wildlife Species
For the terrestrial exposure analysis of this risk assessment, a generic bird or mammal
was assumed to occupy either the treated field or adjacent areas receiving a treatment rate
on the field. Actual habitat requirements of any particular terrestrial species were not
considered, and it was assumed that species occupy, exclusively and permanently, the
modeled treatment area. Spray drift model predictions suggest that this assumption leads
to an overestimation of exposure to species that do not occupy the treated field
exclusively and permanently.
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7.0 Risk Conclusions
In fulfilling its obligations under Section 7(a)(2) of the Endangered Species Act, the
information presented in this endangered species risk assessment represents the best data
currently available to assess the potential risks of triclopyr to the CRLF and its designated
critical habitat.
Based on the best available information, the Agency makes a May Affect, and Likely to
Adversely Affect determination for the CRLF based on the direct and indirect
effects to the aquatic and terrestrial-phase CRLF from the use of triclopyr. The
Agency has determined that there is the potential for modification of CRLF designated
critical habitat from the use of the chemical. The direct effect and habitat modification
determinations are summarized in Table 7-1 and Table 7-2, respectively. Given the LAA
determination for the CRLF and potential effects to designated critical habitat, a
description of the baseline status and cumulative effects for the CRLF is provided in
Attachment II.
The LAA effects determination applies to those areas where it is expected that the
pesticide's use will directly or indirectly affect the CRLF or its designated critical habitat.
To determine this area, the footprint of triclopyr's use pattern is identified, using land
cover data that correspond to triclopyr's use pattern. The spatial extent of the LAA
effects determination also includes areas beyond the initial area of concern that may be
impacted by runoff and/or spray drift. The identified direct and indirect effects and
modification to critical habitat are anticipated to occur only for those currently occupied
core habitat areas, CNDDB occurrence sections, and designated critical habitat for the
CRLF that overlap with the initial area of concern plus 1000 feet buffer from its
boundary (for terrestrial uses). A buffer for aquatic uses could not be established due to
having direct applications to water. For a further analysis of how the buffer was
determined, please see Section 5.2.5. It is assumed that non-flowing waterbodies (or
potential CRLF habitat) are included within this area.
Due to having direct applications to water bodies for triclopyr acid, triclopyr is not just
being transported as runoff across the landscape, into non-impacted water (which is what
is assumed for downstream dilution). As a result, the water body may be directly
impacted already, possibly increasing the concentration downstream and not diluting it.
For further information on the downstream dilution analysis, please see Section 5.1.4. If
any of these streams reaches flow into CRLF habitat, there is potential to affect either the
CRLF or modify its habitat. These lotic aquatic habitats within the CRLF core areas and
critical habitats potentially contain concentrations of triclopyr sufficient to result in LAA
determination or modification of critical habitat.
Appendix D provides maps of the initial area of concern, along with CRLF habitat areas,
including currently occupied core areas, CNDDB occurrence sections, and designated
critical habitat. It is expected that any additional areas of CRLF habitat that are located at
least 1,000 ft (to account for offsite migration via spray drift for terrestrial uses) outside
the initial area of concern may also be impacted and are part of the full spatial extent of
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the LAA/modification of critical habitat effects determination. Due to direct application
for aquatic uses, triclopyr may be applied directly to the area of concern.
A summary of the risk conclusions and effects determinations for the CRLF and its
critical habitat, given the uncertainties discussed in Section 6.0, is presented in Table 7-1
and Table 7-2.
Table 7-1. Effects Determination Summary for Triclopyr Use and the CRLF
Assessment
Eiulpoint
Effects
Determination 1
Basis for Determination
Survival, growth,
and/or reproduction
of CRLF
individuals
Potential for Direct Effects
LAA
LAA
Aquatic-phase (Eggs, Larvae, and Adults):
The aquatic phase amphibian acute LOCs for listed species (0.05) are exceeded
for most uses of triclopyr in California. The chance of individual mortality for
which the RQs exceed the LOG (0.05) range from approximately 1 in 2.51* 106
(<1%) at an RQ of 0.08 (Ornamental sod farm, turf) to 1 in 1 (100%) at an RQ of
9.62 (Lakes/ponds/reservoirs). The chronic RQs for most uses of triclopyr
exceed the chronic species LOG (1.0), and range from 131.58
(Lakes/ponds/reservoirs) to 0.21 for (Ornamental lawns and turf).
Terrestrial-phase (Juveniles and Adults):
Acute dietary-based RQs exceed the acute listed species LOG (0.1) for all uses of
triclopyr except rice. The chance of individual mortality for which the RQs
exceed the LOG (0.1) range from approximately 1 in 1.21*103 (<1%) at anRQ
0.20 (Douglas-Fir, Forest/Shelterbelt) to approximately 1 in 1.03 (100%) at an
RQ of 2.70 (Agricultural Uncultivated Areas).
For refined dose-based RQs for CRLFs of varying weights (1.4g, 37g, and 238g)
the chance of individual mortality for which the RQs exceed the LOG (0.1) range
from approximately 1 in 2.94*105 (<1%) at an RQ of 0.10 (Agricultural
Uncultivated Areas, small insectivore mammals weighing 15g, 238g CRLF) to
approximately 1 in 1 (100%) at anRQ of 10.3 (Agricultural Uncultivated Areas,
small herbivore mammals weighing 15g, 37g CRLF), and from approximately 1
in 9.56* 103 (<1%) at an RQ 0.15 (Forest Tree/Pest Management, small insects
238 g CRLF) to approximately 1 in 1 (100%) at an RQ of 16.61 (Agricultural
Uncultivated Areas, small herbivore mammals weighing 35g, 37g CRLF). These
ranges of RQs is relevant to all sizes of CRLF consuming small insects, and
small herbivore and insectivore mammals (mammals weighing 15g or 35g), for
uses in which there were exceedances.
Refined chronic dietary-based RQs for CRLFs consuming small insects exceed
the chronic species LOG (1.0) for all foliar application uses of triclopyr except
rice. Refined chronic dietary-based RQs for CRLFs consuming small herbivore
mammals (either 15g or 35g) exceed the chronic species LOG (1.0) for all foliar
application uses of triclopyr. Refined chronic dietary-based RQs for CRLFs
consuming large insects, small insectivore mammals (either 15g or 35g), and
small terrestrial-phase amphibians (weighing 2.3g) exceed the chronic species
LOG (1.0) for foliar uses of triclopyr with application rates greater than or equal
to 8 Ib ae/A.
For granular uses of triclopyr the resulting LD50/ft2s for all granular application
uses of triclopyr exceed the Agency's acute endangered species LOG of 0.1 for
birds weighing 20 and lOOg, ranging from 2.05 (Commercial/Industrial Lawns)
to 0.32 (Ornamental Lawns and Turf) for 20g birds, and 1.04
(Commercial/Industrial Lawns) to 0.16 (Ornamental Lawns and Turf) for lOOg
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Assessment
Eiulpoint
Effects
Determination 1
Basis for Determination
LAA
LAA
birds. The probability of individual effect at the endangered species LOG (0.1)
ranges from 1 in 1.09 (92%) at anRQ of 2.05 (Commercial/Industrial Lawns) to
1 in 1.88 (53%) at anRQ of 1.04 (Ornamental Lawns and Turf) for birds
weighing 20g. For birds weighing 100 g LD50/ft2 the probability of individual
effect at the endangered species LOG (0.1) ranges from 1 in 7.70*101 (1.3%) at
an RQ of 0.32 (Commercial/Industrial Lawns) to 1 in 5.85* 103 (0.02%) at an RQ
of 0.16 (Ornamental Lawns and Turf).
Potential for Indirect Effects
Aquatic prey items, aquatic habitat, cover and/or primary productivity
LOCs for non-vascular plants are exceeded for most uses of triclopyr. The non-
vascular plant RQs range from 35.71 for lakes/ponds/reservoirs to 0.08 for
ornamental lawns and turf.
LOCs for vascular plants are exceeded for many uses of triclopyr. The vascular
plant RQs range from 2.91 for lakes/ponds/reservoirs to 0.01 for ornamental
lawns and turf.
LOCs for aquatic invertebrates are exceeded for most uses of triclopyr. The acute
RQs range from 10.00 (Lakes/ponds/reservoirs) to 0.02 (Ornamental lawns and
turf). Population reduction in aquatic invertebrate prey items for the CRLF from
application of triclopyr ranges from 100% (Lakes/ponds/reservoirs) to < 0.1%
(Ornamental lawns and turf). The chronic RQs range from 0.10 for
lakes/ponds/reservoirs to <0.01 for ornamental lawns and turf.
For fish/and aquatic-phase amphibians most uses of triclopyr exceed the acute
and chronic LOCs for listed species (acute, 0.05 and chronic, 1.0). The RQs
range from 0.02 (Ornamental lawns and turf) to 9.62 (Lakes/ponds/reservoirs).
The chronic RQs range from 131.58 (Lakes/ponds/reservoirs) to 0.21 for
(Ornamental lawns and turf).
Terrestrial prey items, riparian habitat
RQs could not be calculated for terrestrial invertebrates as the toxicity endpoint
was not a definitive value. But because the calculated terrestrial small insect
EEC's exceed the highest levels tested, there is a potential indirect impact to the
terrestrial-phase CRLF from a reduction of invertebrate food items.
For small terrestrial mammals, the acute dose-based RQs exceed the acute risk
LOG (0.1) for all foliar application uses of triclopyr ranging from 10.7
(Agricultural Uncultivated Areas) to 0.11 (Rice). Both dietary and dose-based
chronic RQs exceed the chronic risk LOG (1.0) for all foliar application uses of
triclopyr ranging from 1222.9 (Agricultural Uncultivated Areas) to 13.1 (Rice)
[Dose-based] and 141 (Agricultural Uncultivated Areas) to 1.51 (Rice) [Dietary-
based]. Population reduction in small mammal prey items for the CRLF from
application of triclopyr ranges from 100% (agricultural uncultivated areas) to
0.0008% (rice) for foliar applications of triclopyr.
For granular uses of triclopyr the resulting LD50/ft2s for all granular application
uses of triclopyr exceed the Agency's acute endangered species LOG of 0.1 for
mammals weighing 15g and 35g, ranging from 0.83 (Commercial/Industrial
Lawns) to 0.42 (Ornamental Lawns and Turf) for mammals weighing 15g, and
0.44 (Commercial/Industrial Lawns) to 0.22 (Ornamental Lawns and Turf) for
mammals weighing 35g. Population reduction in small mammal prey items for
the CRLF from application of triclopyr ranges from 36% (Commercial/Industrial
Lawns) to 0.15% (Ornamental Lawns and Turf) for granular applications of
140
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Assessment
Eiulpoint
Effects
Determination 1
Basis for Determination
triclopyrto mammals weighing 15g and 35g.
The refined acute RQs (dietary- and dose-based) for small terrestrial-phase
amphibians did not exceed the listed species LOG (0.1) for any use of triclopyr.
However, the refined chronic dietary-based RQs exceed the chronic species LOG
(1.0) for small terrestrial-phase amphibians (weighing 2.3g) for foliar uses of
triclopyr with application rates greater than or equal to 8 Ib ae/A. Reduction in
amphibian prey items, specifically other frogs may potentially be affected from
chronic exposure of triclopyr as the result of triclopyr use.
The RQs for non-target terrestrial monocots and dicot plants inhabiting semi-
aquatic areas exceed the Agency's risk to terrestrial plant LOG (1.0) for all uses
of triclopyr both foliar (aerial and ground) and granular applications. RQs for
non-target terrestrial monocots and dicot plants inhabiting upland dry areas
exceed the Agency's risk to terrestrial plant LOG (1.0) for all uses of triclopyr
except rice both foliar (aerial and ground) and granular applications. Aerial
foliar applications of triclopyr result in spray drift RQ exceedances for dicot non-
target species for all uses of triclopyr. Aerial foliar applications of triclopyr
result in spray drift RQ exceedances for monocots for all uses except rice uses.
Ground foliar applications result in spray drift RQ exceedances for both
monocots and dicots for all uses except rice.
1 No effect (NE); May affect, but not likely to adversely affect (NLAA); May affect, likely to adversely
affect (LAA)
Table 7-2. Effects Determination Summary for Triclopyr Use and CRLF Critical
Habitat Impact Analysis
Assessment
Eiulpoint
Effects
Determination 1
Basis for Determination
Modification of
aquatic-phase PCE
Habitat
Modification
Due to aquatic vascular and terrestrial plant communities being reduced from a
majority of use sites, there is potential for alteration of channel/pond morphology
or geometry and/or increase in sediment deposition within the stream channel or
pond. These plant communities provide shelter, foraging, predator avoidance,
and aquatic dispersal for juvenile and adult CRLFs. In addition, there is potential
for 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.
LOCs are exceeded for terrestrial riparian plants and for aquatic vascular plants
from exposure to triclopyr from spray drift. LOCs for non-vascular plants are
exceeded for many uses of triclopyr.
Modification of
terrestrial-phase
PCE
Habitat
Modification
The use of triclopyr at all sites may create the following effects to PCE:
elimination and/or disturbance of upland habitat; ability of habitat to support
food source of CRLFs, elimination and/or disturbance of dispersal habitat,
reduction and/or modification of food sources for terrestrial phase juveniles and
adults, and alteration of chemical characteristics necessary for normal growth
and viability of juvenile and adult CRLFs and their food source.
The RQs for non-target terrestrial monocots and dicot plants inhabiting semi-
aquatic areas exceed the Agency's risk to terrestrial plant LOG (1.0) for all uses
of triclopyr both foliar (aerial and ground) and granular applications. RQs for
non-target terrestrial monocots and dicot plants inhabiting upland dry areas
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exceed the Agency's risk to terrestrial plant LOG (1.0) for all uses of triclopyr
except rice both foliar (aerial and ground) and granular applications. Aerial
foliar applications of triclopyr result in spray drift RQ exceedances for dicot non-
target species for all uses of triclopyr. Aerial foliar applications of triclopyr
result in spray drift RQ exceedances for monocots for all uses except rice.
Ground foliar applications result in spray drift RQ exceedances for both
monocots and dicots for all uses except rice.
The use of triclopyr on most use sites will exceed the refined acute dietary- and
dose-based LOG and chronic LOG for prey food items of small mammals, and
invertebrates (foliar and granular applications). Food sources for the CRLF are
reduced, and the CRLF is indirectly affected from this reduction.
Habitat Modification or No effect (NE)
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 direct/indirect and adverse
habitat modification effects determinations, it is important to note that pesticide
exposures and predicted risks to the species and its resources (i.e., food and habitat) are
not expected to be uniform across the action area. In fact, given the assumptions of drift
and downstream transport (i.e., attenuation with distance), pesticide exposure and
associated risks to the species and its resources are expected to decrease with increasing
distance away from the treated field or site of application. Evaluation of the implication
of this non-uniform distribution of risk to the species would require information and
assessment techniques that are not currently available. Examples of such information and
methodology required for this type of analysis would include the following:
• Enhanced information on the density and distribution of CRLF life stages within
specific recovery units and/or designated critical habitat within the action area.
This information would allow for quantitative extrapolation of the present risk
assessment's predictions of individual effects to the proportion of the population
extant within geographical areas where those effects are predicted. Furthermore,
such population information would allow for a more comprehensive evaluation of
the significance of potential resource impairment to individuals of the species.
• Quantitative information on prey base requirements for individual aquatic- and
terrestrial-phase frogs. While existing information provides a preliminary picture
of the types of food sources utilized by the frog, it does not establish minimal
requirements to sustain healthy individuals at varying life stages. Such
information could be used to establish biologically relevant thresholds of effects
on the prey base, and ultimately establish geographical limits to those effects.
This information could be used together with the density data discussed above to
characterize the likelihood of adverse effects to individuals.
• Information on population responses of prey base organisms to the pesticide.
Currently, methodologies are limited to predicting exposures and likely levels of
direct mortality, growth or reproductive impairment immediately following
exposure to the pesticide. The degree to which repeated exposure events and the
inherent demographic characteristics of the prey population play into the extent to
which prey resources may recover is not predictable. An enhanced understanding
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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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8.0 References
Alvarez, J. 2000. Letter to the U.S. Fish and Wildlife Service providing comments on
the Draft California Red-legged Frog Recovery Plan.
Altig, R.; R.W. McDiarmid. 1999. Body Plan: Development and Morphology. In R.W.
McDiarmid and R. Altig (Eds.), Tadpoles: The Biology ofAnuran Larvae.
University of Chicago Press, Chicago, pp. 24-51.
Fellers, G.M, L.L. McConnell, D. Pratt, S. Datta. 2004. Pesticides in Mountain Yellow-
Legged Frogs (Rana Mucosa) from the Sierra Nevada Mountains of California,
USA. Environmental Toxicology & Chemistry 23 (9): 2170-2177.
Fellers, G. M. 2005a. Rana draytonii Baird and Girard 1852. California Red-legged Frog.
Pages 552-554. In: M. Lannoo (ed.) Amphibian Declines: The Conservation
Status of United States Species, Vol. 2: Species Accounts. University of
California Press, Berkeley, California, xxi+1094 pp.
(http://www.werc.usgs.gov/pt-reyes/pdfs/Rana%20draytonii.PDF)
Fellers, G. M. 2005b. California red-legged frog, Rana draytonii Baird and Girard. Pages
198-201. Irr. L.L.C. Jones, et al (eds.) Amphibians of the Pacific Northwest.
xxi+227.
Fletcher J.S.; I.E. Nellessen; T.G. Pfleeger. 1994. Literature Review and Evaluation of
the EPA Food-chain (Kenaga) Nomogram, an Instrument for Estimating Pesticide
Residues on Plants. Environmental Toxicology and Chemistry., 13:9 (13 83-1391).
Hayes, M. P.; M. R. Jennings. 1988. Habitat correlates of distribution of the California
redlegged frog (Rana aurora draytonii) and the foothill yellow-legged frog (Rana
boylii): Implications for management. Pages 144-158 In: R. Sarzo, K. E.
Severson, and D. R. Patton (technical coordinators). Proceedings of the
Symposium on the Management of Amphibians, Reptiles, and small mammals in
NorthAmerica. U.S.D.A. Forest Service General Technical Report RM-166.
Hayes, M.P. and M.M. Miyamoto. 1984. Biochemical, behavioral and body size
differences between Rana aurora aurora and R. a. draytonii. Copeia 1984(4):
1018-22.
Hayes, M.P.; M.R. Tennant. 1985. Diet and feeding behavior of the California red-
legged frog. The Southwestern Naturalist 30(4): 601-605.
Hoerger, F.; E. E. Kenaga. 1972. Pesticide residues on plants; Correlation of
representative data as a basis for estimation of their magnitude in the
144
-------
environment. In. F. Coulston and F. Korte, Eds., Environmental Quality and
Safety: Chemistry, Toxicology, and Technology. George Thieme Publishers,
Stuttgart, West Germany, pp. 9-28.
Jennings, M.R.; M.P. Hayes. 1985. Pre-1900 overharvest of California red-legged frogs
(Rana aurora draytonii): The inducement for bullfrog (Rana catesbeiand)
introduction. HerpetologicalReview 31(1): 94-103.
Jennings, M.R.; M.P. Hayes. 1994. Amphibian and reptile species of special concern in
California. Report prepared for the California Department of Fish and Game,
Inland Fisheries Division, Rancho Cordova, California. 255 pp.
Jennings, M.R.; S. Townsend; R.R. Duke. 1997. Santa Clara Valley Water District
California red-legged frog distribution and status - 1997. Final Report prepared
by H.T. Harvey & Associates, Alviso, California. 22 pp.
Kupferberg, S. 1997. Facilitation of periphyton production by tadpole grazing: Functional
differences between species. Freshwater Biology 37:427-439.
Karvonen, T.; H. Koivusalo; M. Jauhiainen; J. Palko; K. Weppling. 1999. A hydrological
model for predicting runoff from different land use areas, Journal of Hydrology,
217(3-4): 253-265.
Kupferberg, S.J.; J.C. Marks and M.E. Power. 1994. Effects of variation in natural algal
and detrital diets on larval anuran (Hyla regilla) life-history traits. Copeia 1994:
446-457.
LeNoir, J.S., L.L. McConnell, G.M. Fellers, T.M. Cahill, J.N. Seiber. 1999.
Summertime Transport of Current-use pesticides from California's Central Valley
to the Sierra Nevada Mountain Range,USA. Environmental Toxicology &
Chemistry 18(12): 2715-2722.
McConnell, L.L., J.S. LeNoir, S. Datta, J.N. Seiber. 1998. Wet deposition of current-use
pesticides in the Sierra Nevada mountain range, California, USA. Environmental
Toxicology & Chemistry 17(10): 1908-1916.
McDonald M.A.I; J.R. Healey; P. A. Stevens. 2002. The effects of secondary forest
clearance and subsequent land-use on erosion losses and soil properties in the
Blue Mountains of Jamaica. Agriculture, Ecosystems & Environment, Volume 92,
Number 1: 1-19.
Okisaka S.; A. Murakami; A. Mizukawa; J. Ito; S.A. Vakulenko; LA. Molotkov; C.W.
Corbett; M. Wahl; D.E. Porter; D. Edwards; C. Moise. 1997. Nonpoint source
runoff modeling: A comparison of a forested watershed and an urban watershed
on the South Carolina coast. Journal of Experimental Marine Biology and
Ecology, Volume 213, Number 1: 133-149.
145
-------
Phuong V.T.; J. van Dam. 2002. Linkages between forests and water: A review of
research evidence in Vietnam. In. Forests, Water and Livelihoods European
Tropical Forest Research Network. ETFRN NEWS (3pp).
Rathburn, G.B. 1998. Rana aurora draytonii egg predation. Herpetological Review
29(3): 165.
Reis, D.K. Habitat characteristics of California red-legged frogs (Rana aurora
draytonii): Ecological differences between eggs, tadpoles, and adults in a coastal
brackish and freshwater system. M.S. Thesis. San Jose State University. 58 pp.
Seale, D. B., and N. Beckvar. 1980. The comparative ability of anuran larvae (genera:
Hyla, Bufo, and Rand) to ingest suspended blue-green algae. Copeia 1980: 495-
503.
Sparling, D.W.; G.M. Fellers, L.L. McConnell. 2001. Pesticides and amphibian
population declines in California, USA. Environmental Toxicology & Chemistry
20(7): 1591-1595.
Teske M.E. and Curbishley 2003. ADGISP Version 8.07 User Manual. C.D.I Technical
Note No. 02-06. Prepared for USDA Forest Service. Continuum Dynamics, Inc.
Ewing, NJ08618
Urban, DJ. and NJ. Cook, 1986. Hazard Evaluation Division Standard Evaluation
Procedure Ecological Risk Assessment. EPA 540/9-85-001. U.S. Environmental
Protection Agency, Office of Pesticide Programs, Washington D.C.
U.S. Environmental Protection Agency. (U.S. EPA). 1992. Comparative analysis of
acute avian risk from granular pesticides. Office of Pesticide Programs. USEPA.
March 1992.
U.S. Environmental Protection Agency. (U.S. EPA). 1993. Wildlife Exposure Factors
Handbook. EPA/600/R-13/187a, Office of Research and Development,
Washington, DC.
U.S. EPA. 1998. Guidance for Ecological Risk Assessment. Risk Assessment Forum.
EPA/630/R-95/002F, April 1998.
U.S. EPA. 2004. Overview of the Ecological Risk Assessment Process in the Office of
Pesticide Programs. Office of Prevention, Pesticides, and Toxic Substances.
Office of Pesticide Programs. Washington, D.C. January 23, 2004.
U.S. Fish and Wildlife Service (U.S. FWS). 1996. Endangered and threatened wildlife
and plants: determination of threatened status for the California red-legged frog.
Federal Register 61(101):25813-25833.
146
-------
U.S. FWS and National Marine Fisheries Service (NMFS). 1998. Endangered Species
Consultation Handbook: Procedures for Conducting Consultation and Conference
Activities Under Section 7 of the Endangered Species Act. Final Draft. March
1998.
U.S. FWS. 2002. Recovery Plan for the California Red-legged Frog (Rana aurora
draytonif). Region 1, USFWS, Portland, Oregon.
(http://ecos.fws.gov/doc/recovery plans/2002/020528.pdf)
U.S. FWS/NMFS. 2004. 50 CFR Part 402. Joint Counterpart Endangered Species Act
Section 7 Consultation Regulations; Final Rule. 69 Federal Register 47732-
47762.
U.S. FWS. 2006. Endangered and threatened wildlife and plants: determination of critical
habitat for the California red-legged frog. 71 Federal Register 19244-19346.
U.S. FWS. Website accessed: 30 December 2006.
http://www.fws.gov/endangered/features/rl frog/rlfrog.html#where
Wassersug, R. 1984. Why tadpoles love fast food. Natural History 4/84.
Willis, G. H.; L.L. McDowell. 1987. Pesticide persistence on foliage. Reviews of
Environmental Contamination and Toxicology 100: 23-73.
147
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