Risks of Propyzamide Use to Federally
Threatened California Red-legged Frog
(Rana aurora draytonii)
Pesticide Effects Determination
Environmental Fate and Effects Division
Office of Pesticide Programs
Washington, D.C. 20460
February 7,2008
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Primary Authors
Greg Orrick, Environmental Scientist
Thomas Steeger, Ph.D., Senior Biologist
Reviewers
Anita Pease, Senior Biologist
Marietta Echeverria, Risk Assessment Process Leader
Branch Chief, Environmental Risk Branch 4
Elizabeth Behl
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Acknowledgement
The propyzamide chemical team would like to acknowledge the contribution of the
California red-legged frog Steering Committee in compiling detailed information on the
threatened species. Additionally, the Steering Committee has provided invaluable
guidance toward achieving greater consistency in format and content between chemicals
being assessed. We acknowledge the contribution of Ms. Michelle Thawley, Mr. Kurt
Pluntke, and Ms. Megan Thynge in providing the Geographic Information System
analysis used to define the potential overlap between California red-legged frog and their
designated critical habitat within the action area.
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Table of Contents
1. Executive Summary 10
2. Problem Formulation 17
2.1 Purpose 17
2.2 Scope 19
2.3 Previous Assessments 20
2.4 Stressor Source and Distribution 20
2.4.1 Environmental Fate Properties 20
2.4.1 Environmental Transport Mechanisms 22
2.4.2 Mechanism of Action 22
2.4.3 Use Characterization 22
2.5 Assessed Species 26
2.5.1 Distribution 27
2.5.2 Reproduction 32
2.5.3 Diet 32
2.5.4 Habitat 33
2.8 Assessment Endpoints and Measures of Ecological Effect 43
2.8.1. Assessment Endpoints for the CRLF 43
2.8.2 Assessment Endpoints for Designated Critical Habitat 44
2.9 Conceptual Model 47
2.9.1 Risk Hypotheses 47
2.9.2 Diagram 47
2.10 AnalysisPlan 50
2.10.1 Measures to Evaluate the Risk Hypothesis and Conceptual Model 50
2.10.1.1 Measures of Exposure 50
2.10.1.2 Measures of Effect 52
2.10.1.3 Integration of Exposure and Effects 53
2.10.2 Data Gaps 54
3.1 Label Application Rates and Intervals 54
3.2 Aquatic Exposure Assessment 55
3.2.1 Modeling Approach 55
3.2.2 Model Inputs 56
3.2.3 Results 57
3.2.4 Existing Monitoring Data 58
3.2.4.1 California Department of Pesticide Regulation Data 58
3.2.4.2 USGS NAWQA Data 58
3.2.4.3 USGS NASQ.W Data 60
3.2.4.3 USEPA STORET Data 61
3.2.4.4 Other Monitoring Data 61
3.2.5 Spray Drift Buffer Analysis 62
3.2.6 Downstream Dilution Analysis 64
3.2 Terrestrial Animal Exposure Assessment 64
3.3 Terrestrial Plant Exposure Assessment 66
4. Effects Assessment 67
4.1 Toxicity of Propyzamide to Aquatic Organisms 69
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4.1.1 Toxicity to Freshwater Fish 70
4.1.1.1 Freshwater Fish: Acute Exposure (Mortality) Studies 70
4.1.1.2 Freshwater Fish: Chronic Exposure (Growth/Reproduction) Studies 70
4.1.1.3 Freshwater Fish: Sublethal Effects and Additional Open Literature
Information 71
4.1.1.4 Aquatic-phase Amphibian: Acute and Chronic Studies 71
4.1.2 Toxicity to Freshwater Invertebrates 71
4.1.2.1 Freshwater Invertebrates: Acute Exposure Studies 71
4.1.2.2 Freshwater Invertebrates: Chronic Exposure Studies 71
4.1.2.3 Freshwater Invertebrates: Open Literature Data 72
4.1.3 Toxicity to Aquatic Plants 72
4.1.3.1 Aquatic Plants: Laboratory Data 72
4.1.4 Freshwater Field/Mesocosm Studies 72
4.2 Toxicity of Propyzamide to Terrestrial Organisms 72
4.2.1 Toxicity to Birds 74
4.2.1.1 Birds: Acute Exposure (Mortality) Studies 74
4.2.1.2 Birds: Chronic Exposure (Growth, Reproduction) Studies 75
4.2.1.3 Terrestrial-phase Amphibian Acute and Chronic Studies 75
4.2.2 Toxicity to Mammals 75
4.2.2.1 Mammals: Acute Exposure (Mortality) Studies 75
4.2.2.2 Mammals: Chronic Exposure (Growth, Reproduction) Studies 75
4.2.3 Toxicity to Terrestrial Invertebrates 76
4.2.3.1 Terrestrial Invertebrates: Acute Exposure (Mortality) Studies 76
4.2.3.2 Terrestrial Invertebrates: Open Literature Studies 76
4.2.4 Toxicity to Terrestrial Plants 76
4.3 Use of Probit Slope Response Relationship to Provide Information on the Endangered
Species Levels of Concern 77
4.4 Incident Database Review 78
4.4.1 Terrestrial Incidents 78
4.4.2 Plant Incidents 78
4.4.3 Aquatic Incidents 78
5. Risk Characterization 78
5.1 Risk Estimation 78
5.1.1 Exposures in the Aquatic Habitat 79
5.1.1.1 Direct Effects to Aquatic-Phase CRLF 79
5.1.1.2 Indirect Effects to Aquatic-Phase CRLF via Reduction in Prey (non-
vascular aquatic plants, aquatic invertebrates, fish, and frogs) 80
5.1.1.3 Indirect Effects to CRLF via Reduction in Habitat and/or Primary
Productivity (Freshwater Aquatic Plants) 81
5.1.2 Exposures in the Terrestrial Habitat 82
5.1.2.1 Direct Effects to Terrestrial-phase CRLF 82
5.1.2.2 Indirect Effects to Terrestrial-Phase CRLF via Reduction in Prey
(terrestrial invertebrates, mammals, and frogs) 83
5.1.2.3 Indirect Effects to CRLF via Reduction in Terrestrial Plant Community
(Riparian and Upland Habitat) 85
5.1.3 Primary Constituent Elements of Designated Critical Habitat 86
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5.1.3.1 Aquatic-Phase (Aquatic Breeding Habitat and Aquatic Non-Breeding
Habitat) 86
5.1.3.2 Terrestrial-Phase (Upland Habitat and Dispersal Habitat) 87
5.2 Risk Description 88
5.2.1 Direct Effects 91
5.2.1.1 Aquati c-Phase CRLF 91
5.2.1.2 Terrestrial-Phase CRLF 92
5.2.2 Indirect Effects (via Reductions in Prey Base) 93
5.2.2.1 Algae (non-vascular plants) 93
5.2.2.2 Aquatic Invertebrates 93
5.2.2.3 Fish and Aquatic-phase Frogs 93
5.2.2.4 Terrestrial Invertebrates 94
5.2.2.5 Mammals 94
5.2.2.6 Terrestrial-phase Amphibians 94
5.2.3 Indirect Effects (via Habitat Effects) 94
5.2.3.1 Aquatic Plants (Vascular and Non-vascular) 94
5.2.3.2 Terrestrial Plants 95
5.2.4 Modification to Designated Critical Habitat 95
5.2.4.1 Aquatic-Phase PCEs 95
5.2.4.2 Terrestrial-Phase PCEs 96
6. Uncertainties 97
6.1 Exposure Assessment Uncertainties 97
6.1.1 Maximum Use Scenario 97
6.1.2 Aquatic Exposure Modeling of Propyzamide 97
6.1.3 Action Area Uncertainties 99
6.1.4 Usage Uncertainties 100
6.1.5 Terrestrial Exposure Modeling of Propyzamide 100
6.2 Effects Assessment Uncertainties 102
6.2.1 Age Class and Sensitivity of Effects Thresholds 102
6.2.2 Use of Surrogate Species Effects Data 102
6.2.3 Sublethal Effects 103
6.2.4 Location of Wildlife Species 103
6.2.5 Location of Wildlife Species 103
6.2.6 Absence of Chronic Toxicity Data 104
6.2.7 Mechanism of Action 104
7. Risk Conclusions 104
7.1 Action Area 109
7.1.1 Areas indirectly affected by the Federal action 109
7.1.2 Areas indirectly affected by the Federal action 109
111
8. References 119
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Appendices
A. Aquatic and Terrestrial Animal Acute Toxicity Data Probit Dose-Response Analysis
B. Aquatic Exposure Modeling Inputs
C. LOCs & RQ Method
D. Spatial Analysis of Action Area
E. T-REX Output
F. TerrPlant Output
G. ECOTOXList
H. EIIS Summary
I. T-HERPS Output
J. IECV Output
K. Degradate Summary
Attachments
1. Status and Life History of California Red-Legged Frog
2. Baseline Status and Cumulative Effects for the California Red-legged Frog
List of Tables
Table 1.1 Effects Determination Summary for Direct and Indirect Effects of
propyzamide on the CRLF 13
Table 1.2 Effects Determination Summary for the Critical Habitat Impact Analysis 15
Table 2.2 Summary of Propyzamide Environmental Fate Properties 21
Table 2.4 Summary of California Department of Pesticide Registration (CDPR) Pesticide
Use Reporting (PUR) Data from 2002 to 2005 for Currently Registered
Propyzamide Uses 25
Table 2.5 California Red-legged Frog Recovery Units with Overlapping Core Areas and
Designated Critical Habitat 29
Table 2.7 Assessment Endpoints and Measures of Ecological Effects 44
Table 2.8 Summary of Assessment Endpoints and Measures of Ecological Effect for
Primary Constituent Elements of Designated Critical Habitata 46
Table 3.1 Propyzamide Maximum Use Patterns in the CRLF Action Area 55
Table 3.10 Upper-bound Kenega Nomogram EECs for Dietary- and Dose-based
Exposures of the CRLF and its Prey to propyzamide 66
Table 3.11 EECs (ppm) for Indirect Effects to the Terrestrial-Phase CRLF via Effects to
Terrestrial Invertebrate Prey Items 66
Table 3.12 TerrPlant Inputs and Resulting EECs for Plants Inhabiting Dry and Semi-
aquatic Areas Exposed to propyzamide via Runoff and Drift 67
Table 4.1 Freshwater Aquatic Toxicity Profile for Propyzamide 69
Table 4.2 Categories of Acute Toxicity for Aquatic Organisms 70
Table 4.3 Terrestrial Toxicity Profile for Propyzamide 73
Table 4.4 Categories of Acute Toxicity for Avian and Mammalian Studies 74
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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) 81
Table 5.6 Summary of RQs Used to Estimate Indirect Effects to the Terrestrial-phase
CRLF via Direct Effects on Terrestrial Invertebrates as Dietary Food
Items 83
Table 5.7 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 84
Table 5.8 RQs* for Monocots Inhabiting Dry and Semi-Aquatic Areas Exposed to
Propyzamide via Runoff and Drift 85
Table 5.9 RQs* for Dicots Inhabiting Dry and Semi-Aquatic Areas Exposed to
Propyzamide via Runoff and Drift 86
Table 5.10 Preliminary Effects Determination Summary for propyzamide - Direct and
Indirect Effects to CRLF 89
Table 5.11 Preliminary Effects Determination Summary for propyzamide - PCEs of
Designated Critical Habitat for the CRLF 90
Table 7.1 Effects Determination Summary for Direct and Indirect Effects of
propyzamide on the CRLF 105
Table 7.2 Effects Determination Summary for the Critical Habitat Impact Analysis 107
Table 7.3. Spray drift buffer distances used to determine the extent of terrestrial action
area for uses of propyzamide 109
Table 7.4. Spray drift action area & CRLF habitat overlap spatial summary results by
recovery unit 117
List of Figures
Figure 2.1 National Propyzamide Usage in 2002 (USGS 2007) 24
Figure 2.2 Recovery Unit, Core Area, Critical Habitat, and Occurrence Designations for
CRLF 31
Figure 2.9 Conceptual Model for Aquatic-Phase of the CRLF 48
49
Figure 2.10 Conceptual Model for Terrestrial-Phase of the CRLF 49
Figure 2.11 Conceptual Model for Pesticide Effects on Aquatic Component of CRLF
Critical Habitat 49
Figure 2.12 Conceptual Model for Pesticide Effects on Terrestrial Component of CRLF
Critical Habitat 50
Table 5.1 Summary of Direct Effect RQs for the Aquatic-phase CRLF 80
Figure 7.1. Final action area for agricultural uses of propyzamide Ill
Figure 7.2. Final action area for orchard and vineyard uses of propyzamide 112
Figure 7.3. Final action area for pasture uses of propyzamide 113
Figure 7.4. Final action area for turf uses of propyzamide 114
Figure 7.5. Recovery units and areas relevant to the CRLF 116
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Figure 7.6. Map of overlap between action area for propyzamide and CRLF core areas
and critical habitat 118
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1. Executive Summary
The purpose of this assessment is to evaluate potential direct and indirect effects on the
California red-legged frog (Rana aurora draytonii) (CRLF) arising from Federal
Insecticide, Fungicide, and Rodenticide Act (FIFRA) regulatory actions regarding use of
propyzamide on agricultural and non-agricultural sites. In addition, this assessment
evaluates whether these actions can be expected to result in modification of the species'
designated critical habitat. This assessment was completed in accordance with the U.S.
Fish and Wildlife Service (USFWS) and National Marine Fisheries Service (NMFS)
Endangered Species Consultation Handbook (USFWS/NMFS 1998) and procedures
outlined in the Agency's Overview Document (USEPA 2004).
The CRLF was listed as a threatened species by USFWS in 1996. The species is endemic
to California and Baja California (Mexico) and inhabits both coastal and interior
mountain ranges. A total of 243 streams or drainages are believed to be currently
occupied by the species, with the greatest numbers in Monterey, San Luis Obispo, and
Santa Barbara counties (USFWS 1996) in California.
Propyzamide is a selective, systemic, restricted-use, organochlorine herbicide that is
currently labeled for use on artichokes, cane berries, blueberries, alfalfa and related feed
crops, lettuce and related leafy greens, rhubarb, pome and stone fruit, grapes, winter peas,
sod, turf, fallow land, conservation reserve land, Christmas trees, and ornamentals.
Propyzamide is not labeled for use on cane berries, winter peas, rhubarb, or conservation
reserves in California. The remaining current uses are considered as part of the federal
action evaluated in this assessment.
Propyzamide has relatively low volatility and is soluble in water. Therefore, potential
transport mechanisms considered in this assessment include spray drift and runoff, as
volatilization and atmospheric transport are not expected to occur. The compound is
stable to hydrolysis, mobile in some soils, and has been detected in surface water and
ground water monitoring studies. The major routes of degradation appear to be aerobic
metabolism in soil and photolysis in water. In anaerobic environments, propyzamide
may be moderately persistent.
Toxicity data are not available for degradates of propyzamide; however, all identified
degradates other than carbon dioxide retain the 3,5-dichlorobenzoyl moiety and in the
absence of data to the contrary are considered residues of concern for mammals.
Therefore, a total residues of concern (TRC) approach was used to evaluate the potential
exposure to the residues of risk concern, which include propyzamide and all identified
degradates other than carbon dioxide.
Since CRLFs exist within aquatic and terrestrial habitats, exposure of the CRLF, its prey
and its habitats to propyzamide are assessed separately for the two habitats. The Tier-II
aquatic exposure models Pesticide Root Zone Model (PRZM) and Exposure Analysis
Modeling System (EXAMS) are used to estimate high-end exposures of propyzamide in
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aquatic habitats resulting from runoff and spray drift from different uses. Peak aquatic
model-estimated environmental concentrations (EEC) of total residues resulting from
different propyzamide uses range from 13.9 to 225 |ig/L. These estimates are
supplemented with analysis of available California surface water monitoring data from
the U. S. Geological Survey's National Water Quality Assessment (NAWQA) program
and the California Department of Pesticide Regulation (DPR) surface water database.
However, exposure estimates cannot be directly evaluated with the monitoring data
because the parent compound alone is monitored, whereas all residues of concern are
estimated in modeling. The maximum concentration of propyzamide reported by the
California Department of Pesticide Regulation surface water database from 1990-2005 is
0.25 |ig/L. The maximum concentration of propyzamide reported by NAWQA from
1992-2005 for California surface waters with agricultural watersheds is 0.11 |ig/L. These
values are three orders of magnitude less than the maximum model-estimated
environmental concentration of total residues, but not inconsistent with the peak (3.7-10.3
|ig/L) and annual mean (0.53-4.45 |ig/L) drinking water exposure estimates of
propyzamide per se that were generated in support the 2002 Tolerance Reregi strati on
Eligibility Decision (TRED) (USEPA 2002a).
To estimate propyzamide exposures to the terrestrial-phase CRLF, and its potential prey
resulting from uses involving propyzamide applications, the Terrestrial Residue
EXposure (T-REX) model is used for foliar treatment uses. The AGricultural DISPersal
(AGDISP) model is used to estimate deposition of propyzamide on terrestrial and aquatic
habitats from spray drift. The TerrPlant model is used to estimate propyzamide
exposures to terrestrial-phase CRLF habitat, including plants inhabiting semi-aquatic and
dry areas, resulting from uses involving foliar propyzamide applications. The Terrestrial
Herptafaunal Exposure and Residue Program Simulation (T-HERPS) model is used to
allow for further characterization of dietary exposures of terrestrial-phase CRLFs.
The assessment endpoints for the CRLF include direct toxic effects on the survival,
reproduction, and growth of the CRLF itself, as well as indirect effects, such as reduction
of the prey base 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 propyzamide use within the action area has the potential to
adversely affect the CRLF and its designated critical habitat via direct toxicity or
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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 a particular type of effect are
below LOCs, the pesticide is determined to have "no effect" on the subject species.
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 propyzamide use
within the action area "may affect" the CRLF and its designated critical habitat,
additional information is considered to refine the potential for exposure and effects, and
the best available information is used to distinguish those actions that "may affect, but are
not likely to adversely affect" (NLAA) from those actions that are "likely to adversely
affect" (LAA) the CRLF and its critical habitat.
Based on the best available information, the Agency makes a Likely to Adversely Affect
determination for the CRLF from the use of propyzamide. Additionally, the Agency has
determined that there is the potential for modification of CRLF designated critical habitat
from the use of the chemical. The use of propyzamide as an herbicide is likely to
adversely affect terrestrial-phase CRLF through chronic effects. Additionally, as an
herbicide, propyzamide is likely to adversely affect the terrestrial-phase CRLF through
reductions in terrestrial plants that serve as cover. The decrease in terrestrial plants along
riparian zones is also likely to adversely affect the aquatic-phase CRLF through indirect
effects on water quality. The use of propyzamide is also likely to modify the principle
constituent elements (PCEs) of designated critical habitat for both aquatic- and terrestrial-
phase CRLF. A summary of the risk conclusions and effects determinations for the
CRLF and its critical habitat is presented in Tables 1.1 and 1.2. Further information on
the results of the effects determination is included as part of the Risk Description in
Section 5.2.
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Table 1.1 Effects Determination Summary for Direct and Indirect Effects of propyzamide on the
CRLF
Assessment Endpoint
Effects
Determination1
Basis for Determination
Aquatic-Phase CRLF
(Eggs, Larvae, and Adults)
Direct Effects:
Survival, growth, and reproduction of
CRLF individuals via direct effects on
aquatic phases
NE
RQ values for CRLF are below acute and chronic LOCs.
Indirect Effects:
Survival, growth, and reproduction of
CRLF individuals via effects to food
supply (i.e., freshwater invertebrates,
non-vascular plants, fish, and frogs)
Freshwater
invertebrates: NE
RQ values for freshwater invertebrates are below acute and
chronic LOCs
Non-vascular aauatic
plants: NE
RQ values for non-vascular aquatic plants are below the LOC.
Fish and froas:
NE
RQ values for freshwater vertebrates (fish and amphibians) are
below acute and chronic LOCs.
Indirect Effects:
Survival, growth, and reproduction of
CRLF individuals via indirect effects on
habitat, cover, and/or primary
productivity (i.e., aquatic plant
community)
Non-vascular aauatic
plants:
NE
RQ values for non-vascular aquatic plants are below the LOC.
Vascular aauatic
plants:
NE
RQ values for vascular aquatic plants are below the LOC.
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.
LAA
Lerrestrial plant RQ values exceeded and riparian vegetation is
likely to be adversely affected which in turn could indirectly
affect water quality and habitat in ponds and streams
comprising the species' current range.
Terrestrial-Phase CRLF
(Juveniles and adults)
Direct Effects:
Survival, growth, and reproduction of CRLF
individuals via direct effects on terrestrial
phase adults and juveniles
LAA
Chronic RQ values exceed the chronic risk LOC.
Indirect Effects:
Survival, growth, and reproduction of CRLF
individuals via effects on prey (i.e., terrestrial
invertebrates, small terrestrial vertebrates,
including mammals and terrestrial phase
amphibians)
Lerrestrial
invertebrates: NLAA
Lerrestrial insects serving as prey would have a likelihood of
individual mortality of 1 in 20. Based on this relatively low
likelihood of mortality, the potential effect is considered
insignificant and the determination is for a not likely to
adversely affect (NLAA)
Mammals: LAA
None of the RQ values exceed the acute risk LOC while both
dose-based and dietary-based chronic RQ values exceed the
chronic risk LOC. No additional information is available to
refine these initial chronic risk estimates; therefore, the
determination is for a likely to adversely affect (LAA)
terrestrial-phase CRLF based on indirect adverse chronic
effects on mammals serving as food for terrestrial-phase CRLF
Froas:
LAA
Lhere is uncertainty regarding the chronic toxicity endpoint
used to assess direct chronic risk to terrestrial-phase CRLF.
Lhis same uncertainty would apply to other terrestrial-phase
amphibians and therefore, the determination is for a likely to
adversely affect (LAA) terrestrial-phase CRLF through indirect
chronic effects on other terrestrial-phase frogs serving as prey
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Indirect Effects:
Survival, growth, and reproduction of CRLF
LAA
Terrestrial plant RQ values for semi-aquatic and dry areas
individuals via indirect effects on habitat (i.e.,
exceed the LOC.
riparian vegetation)
1 NE = no effect; NLAA = may affect, but not likely to adversely affect; LAA = likely to adversely affect
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Table 1.2 Effects Determination Summary for the Critical Habitat Impact Analysis
Assessment Endpoint
Effects
Determination1
Basis for Determination
Aquatic-Phase CRLF PCEs
(Aquatic Breeding Habitat and Aquatic Non-Breeding Habitat)
Alteration of channel/pond morphology or geometry
and/or increase in sediment deposition within the stream
channel or pond: aquatic habitat (including riparian
vegetation) provides for shelter, foraging, predator
avoidance, and aquatic dispersal for iuvenile and adult
CRLFs.
HM
Although aquatic plants are not affected by the assessed
uses of propyzamide, terrestrial plants are likely to be
adversely affected from the use of the herbicide.
Reductions in the extent of riparian cover may lead to
reductions in water quality due to increased runoff of
sediments, decreased shading leading to increased water
temperatures, and decreased structure
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.1
HM
Alteration of other chemical characteristics necessary for
normal growth and viability of CRLFs and their food
source.
HM
Reduction and/or modification of aquatic-based food
sources for pre-metamorphs (e.g., algae)
NE
RQ values for freshwater vertebrates (fish and
amphibians) and aquatic nonvascular plants are below
acute and chronic LOCs.
Terrestrial-Phase CRLF PCEs
(Upland Habitat and Dispersal Habitat)
Elimination and/or disturbance of upland habitat; ability of
habitat to support food source of CRLFs: Upland areas
within 200 ft of the edge of the riparian vegetation or
dripline surrounding aquatic and riparian habitat that are
comprised of grasslands, woodlands, and/or
wetland/riparian plant species that provides the CRLF
shelter, forage, and predator avoidance
HM
Terrestrial plant RQ values exceed the LOC. Terrestrial
plants are adversely affected by propyzamide and the
determination is for a likely to adversely affect the two
terrestrial-phase PCE through disturbance of upland
habitat to support food sources of CRLF and through
elimination and/or disturbance of dispersal habitat.
Elimination and/or disturbance of dispersal habitat:
Upland or riparian dispersal habitat within designated units
and between occupied locations within 0.7 mi of each
other that allow for movement between sites including
both natural and altered sites which do not contain barriers
to dispersal
HM
Reduction and/or modification of food sources for
terrestrial phase juveniles and adults
HM
The likelihood of reductions in the prey base of
terrestrial-phase CRLF cannot be discounted; therefore,
the determination is for a likely to adversely affect
(LAA) the third terrestrial-phase CRLF PCE through
reduction and/or modification of food sources for
terrestrial-phase juvenile and adult CRLF.
Alteration of chemical characteristics necessary for normal
growth and viability of juvenile and adult CRLFs and their
food source.
HM
Although direct effects to the terrestrial-phase CRLF are
not considered likely, indirect effects through reductions
in the availability of its food items are considered likely
to adversely affect the species; therefore, the
determination is for a likely to adversely affect (LAA)
the fourth terrestrial-phase PCE.
1 NE = No effect; HM = Habitat modification
Based on the conclusions of this assessment, a formal consultation with the U. S. Fish
and Wildlife Service under Section 7 of the Endangered Species Act should be initiated.
1 Physico-chemical water quality parameters such as salinity, pH, mid hardness are not evaluated because these processes are not
biologically mediated and, therefore, are not relevant to the endpoints included in this assessment.
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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 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. Problem Formulation
Problem formulation is intended to provide a strategic framework for an ecological risk
assessment. By identifying the important components of potential ecological risk, it
focuses the assessment on the most relevant life history stages of affected organisms,
habitat components, chemical properties, exposure routes, and endpoints. The structure
of this ecological risk assessment is based on guidance contained in U.S. EPA's
Guidance for Ecological Risk Assessment (USEPA 1998), the Services' Endangered
Species Consultation Handbook (USFWS/NMFS 1998) and is consistent with procedures
and methodology outlined in the Overview Document (USEPA 2004) and reviewed by
the U.S. Fish and Wildlife Service and National Marine Fisheries Service
(USFWS/NMFS 2004).
2.1 Purpose
The purpose of this threatened species assessment is to evaluate potential direct and
indirect effects on individuals of the federally-listed threatened California red-legged frog
(Rana aurora draytonii) (CRLF) arising from FIFRA regulatory actions regarding use of
propyzamide on artichokes, blueberries, alfalfa and related feed crops, lettuce and related
leafy greens, pome and stone fruit, grapes, sod, turf, fallow land, Christmas trees, and
ornamentals. In addition, this assessment evaluates whether use on these crops or areas 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) us. 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 (USEPA 2004). Screening level methods include use
of standard models such as PRZM-EXAMS, T-REX, TerrPlant, and AGDISP, all of
which are described at length in the Overview Document. Additional refinements
include an analysis of the usage data, a spatial analysis, and use of the T-HERPS model
to predict concentrations of propyzamide on terrestrial-phase CRLF food items. Use of
such information is consistent with the methodology described in the Overview
Document (USEPA 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
USEPA 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 propyzamide 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 propyzamide may
17
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potentially involve numerous areas throughout the United States and its Territories.
However, for the purposes of this assessment, attention will be focused on relevant
sections of the action area including those geographic areas associated with locations of
the CRLF and its designated critical habitat within the state of California.
As part of the "effects determination," one of the following three conclusions will be
reached regarding the potential use of propyzamide 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 LOC exceedances) upon individual CRLFs or upon the PCEs of the species'
designated critical habitat, a "no effect" determination is made for use of propyzamide 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 propyzamide.
If a determination is made that use of propyzamide 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 propyzamide use sites) and further evaluation of the potential impact of
propyzamide 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 propyzamide is expected to directly impact living organisms within the action
area (defined in Section 2.7), critical habitat analysis for propyzamide 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
18
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requirements for the listed species associated with the critical habitat or important
physical aspects of the habitat that may be reasonably influenced through biological
processes). Activities that may modify critical habitat are those that alter the PCEs and
appreciably diminish the value of the habitat. Evaluation of actions related to use of
propyzamide that may alter the PCEs of the CRLFs critical habitat form the basis of the
critical habitat impact analysis. Actions that may affect the CRLF's designated critical
habitat have been identified by the Services and are discussed further in Section 2.6.
2.2 Scope
Propyzamide is a selective, systemic, restricted-use, organochlorine herbicide that is
formulated as a wettable powder in water soluble pouches and can be applied pre-plant,
pre-emergence, or post-emergence by ground or aerial spray equipment, depending on
the use. Wetting in of applications is recommended with rainfall or irrigation so that the
compound is available for uptake into the root system. Most application timing occurs in
the fall or early winter prior to freezing. Propyzamide is currently registered for use on a
variety of outdoor crops, orchards, and other areas.
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 propyzamide in accordance with the approved product labels for
California is "the action" relevant to this ecological risk assessment.
Although current registrations of propyzamide allow for use nationwide on most crops,
this ecological risk assessment and effects determination addresses currently registered
uses of propyzamide in portions of the action area that are reasonably assumed to be
biologically relevant to the CRLF and its designated critical habitat. Further discussion
of the action area for the CRLF and its critical habitat is provided in Section 2.7.
This assessment analyzes potential exposure to the total residues of concern (TRC) of
propyzamide. A tolerance reregi strati on eligibility decision (TRED) completed in 2002
identified the residues of concern for dietary risk assessment as propyzamide and its
degradates containing the 3,5-dichlorobenzoyl moiety, which includes all identified
degradates other than carbon dioxide (USEPA 2002). These degradates were assumed to
be no more or less toxic than the parent compound in the absence of toxicity data.
Similarly, propyzamide and its degradates containing the 3,5-dichlorobenzoyl moiety are
the residues of concern for all taxa for this assessment, with the toxicities of the residues
of concern assumed to be similar to the parent compound.
There are no registered products that contain propyzamide along with other active
ingredients. Therefore, this analysis is based on the toxicity of the single active
ingredient, propyzamide, as it extends to the total residues of concern.
19
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2.3 Previous Assessments
Ecological risk assessments completed for propyzamide include two emergency
exemption (FIFRA Section 18) assessments conducted in 1994 for use on grass grown for
seed in Oregon and in 1998 for use on cranberries in Massachusetts. The FIFRA Section
18 assessment for use on grass grown for seed identified potential risk to terrestrial and
wetland plants, including the listed plant Bradshaw's Lomatium, and identified significant
data gaps for aquatic plants and other taxa. The FIFRA Section 18 assessment for use on
cranberries in Massachusetts found no potential risk to listed or nonlisted organisms.
A Reregi strati on Eligibility Decision (RED) document was prepared for pronamide
(propyzamide) in 1994 (USEPA 1994). The RED identified no potential risk to terrestrial
animals, aquatic animals, or aquatic plants. Studies of toxicity to aquatic invertebrates
(chronic), aquatic plants, and terrestrial dicots were requested to eliminate data gaps.
Potential risk to terrestrial monocots was identified from all registered uses.
An ecological risk assessment of proposed uses on chicory, Belgian endive, dandelion,
and berries was completed in 2007. This assessment identified potential chronic risk to
mammals and potential risk to terrestrial and semi-aquatic plants. Potential risk of direct
effects was identified to listed mammals, birds, estuarine invertebrates, and terrestrial and
semi-aquatic plants. Potential risk of indirect effects was identified for most taxa due to
potential risk to plants. An addendum to the ecological risk assessment indicated no
potential risk to listed estuarine invertebrates.
2.4 Stressor Source and Distribution
2.4.1 Environmental Fate Properties
Propyzamide [3,5-dichloro-N-(l,l-dimethylprop-2-ynyl)benzamide] is a moderately to
slightly mobile chemical that is expected to dissipate in terrestrial and aquatic aerobic
environments over weeks or possibly months. The compound is expected to persist
longer in terrestrial and aquatic anaerobic environments, dissipating over months to more
than one year.
Propyzamide is soluble in water up to 15 mg/L at 25°C (USEPA 1994) and is not
expected to volatilize significantly due to the compound's relatively low vapor pressure
of 8.5 x 10"5 torr at 25°C (USEPA 1994). The compound is moderately mobile in organic
carbon-poor soils and slightly mobile in other soils, with organic carbon-normalized
Freundlich adsorption coefficients that range from 548 to 1340 L/kgoc for six soils
(MRID 40211103). Mobility is partially explained by affinity to organic matter, as the
coefficient of variation (CV) across six soils for KFoc (40%) is less than that for KF
(47%). Due to low fish bioconcentration factors (range of 21-77), propyzamide is not
expected to bioconcentrate in aquatic environments (MRID 43196701). General
chemical properties of the compound are summarized in Table 2.1.
20
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Table 2.1 General Chemical Properties of Propyzamide
Chcmical/Fatc Parameter
Value
Sou rec
Structure
cin^%jAbX^
CI
USEPA 1994
Molecular mass
256.13 g/mol
USEPA 1994
Vapor pressure (25°C)
8.5 x 10"5 torr
USEPA 1994
Solubility (25°C)
15 mg/L
USEPA 1994
Octanol-water partition coefficient (Kow)
427-1600
MRID 46284603
MRID 46413408
Freundlich adsorption coefficient (KF_ads);
Organic carbon-normalized Freundlich
adsorption coefficient (KFOc-ads)
3.15 (l/n=1.22); 1340L/kgoc
3.47 (l/n=1.14); 1180 L/kgoc
4.85 (l/n=1.10); 688L/kg0C
5.16 (l/n=1.07); 548 L/kgoc
8.05 (l/n=1.01); 578 L/kgoc
10.1 (l/n=1.00); 714 L/kgoc
MRID 40211103
Fish Bioconcentration Factor
21 (edible)
77 (non-edible)
50 (whole fish)
MRID 43196701
Propyzamide undergoes both biotic (aerobic metabolism) and abiotic (aqueous
photolysis) degradation on the order of weeks to months. Half-lives for total residues of
concern, however, are estimated to be on the order of months to years (all identified
degradates except carbon dioxide are presumed to be of toxicological concern). Table
2.2 lists the environmental fate properties of propyzamide, along with the major and
minor degradates detected in the submitted environmental fate and transport studies. The
maximum reported amounts of propyzamide's degradates are listed in Table K1 and the
structures of the degradates are listed in Table K2 of Appendix K.
Table 2.2 Summary of Propyzamide Environmental Fate Properties
Study
Value (units)
Major Degradates
(Minor Degradates)
MRID#
Study Status
Hydrolysis
No significant degradation at pH 4.7,
7.4, or 8.8 (20°C)
None
00107980
Acceptable
Aqueous
Photolysis
ti/2 = 41.7 d (parent)
217 d (TRC)
RH-26059 (RH-24644,
RH-20839, RH-24580,
RH-25891, RH-26702,
3,5 -dichlorobenzamide)
40420301,
40320601
Acceptable
(supplement)
Soil Photolysis
ti/2 = 249 d (parent)
Stable (TRC)
RH-24580 (RH-24644,
RH-26702)
41913504
Acceptable
Aerobic Soil
Metabolism
t1/2 = 20.1, 21.5, 44.6, 392 d (parent)
64.9, 96.6, 166, 2340 d (TRC)
RH-24644, RH-24580,
carbon dioxide (RH-
20839, RH-26521)
41568901
46413407
Supplemental
(in review)
Anaerobic Soil
Metabolism
ti/2 = 450 d (parent)
Stable (TRC)
RH-24644, RH-24580
(RH-25891)
41913505
263649
(accsn. #)
Acceptable
Supplemental
21
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Table 2.2 Summary of Propyzamide Environmental Fate Properties
Study
Value (units)
Major Dcgradatcs
(Minor Dcjjradatcs)
MRID #
Study Status
Anaerobic Aquatic
Metabolism
ti/2 = 127 d (parent)
402 d (TRC)
RH-24644 (RH-24655,
RH-20839, RH-24580,
RH- 26521, M5,M6,M8,
M10, Mil, carbon
dioxide)
46413408
(in review)
Aerobic Aquatic
Metabolism
ti/2 = 69.0, 119 d (parent)
899, 782 d (TRC)
RH-24655 (RH-24644,
RH-24580, RH-26521,
UK 1, UK 3)
46427901
(in review)
Terrestrial Field
Dissipation
ti/2 = 31 d (sandy loam), 56 d (loam)
(RH-24644, RH-24580)
44078601
Supplemental
2.4.1 Environmental Transport Mechanisms
Potential transport mechanisms include pesticide surface water runoff, spray drift, and
secondary drift of volatilized or soil-bound residues leading to deposition onto nearby or
more distant ecosystems. Secondary drift of propyzamide is not expected to significantly
occur due to the compound's water solubility and relatively low vapor pressure. Surface
water runoff and spray drift are expected to be the major routes of exposure for the
compound.
2.4.2 Mechanism of Action
Propyzamide is a selective, systemic, restricted-use herbicide. The compound is
absorbed by plants via the root system and distributed throughout the plant. The mode of
action of propyzamide is largely unknown although it has been shown to inhibit cell
division by preventing the formation of spindle fibers during mitosis via binding to
proteins associated with microtubule assembly (Griffen 2003). The details regarding the
active site of the chemical are not known.
2.4.3 Use Characterization
Analysis of labeled use information is the critical first step in evaluating the federal
action. The current labels for propyzamide represent the FIFRA regulatory action;
therefore, labeled uses and application rates specified on the labels 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.
Current labels allow use of propyzamide on blueberries, alfalfa, clover, birdsfoot trefoil,
crown vetch, sainfoin, lettuce, endive, escarole, radicchio, apples, apricots, cherries,
nectarines, peaches, pears, plums, prunes, grapes, sod, turf, fallow land, Christmas trees,
and ornamentals without restriction to the region of application (EPA Reg. No. 62719-
397, 70506-78). Current labels also allow the following uses of propyzamide within the
specified States: globe artichokes in California, leaf lettuce in California and Arizona,
cane berries and rhubarb in Oregon and Washington, and winter peas and conservation
22
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reserves in Idaho, Oregon, and Washington. There are no indoor uses of propyzamide.
Unlike EPA Reg. No. 70506-78, EPA Reg. No. 62719-397 does not restrict use on turf to
non-residential sites. Neither label restricts use on ornamentals to non-residential sites.
Because cane berries, rhubarb, winter peas, and conservation reserves are not labeled for
use in California, use on these crops/areas is not evaluated in this assessment. The
remaining crops are evaluated as part of the exposure analysis for the CRLF.
Table 2.3 presents the uses and corresponding application rates considered in this
assessment. Leafy vegetables treated by propyzamide were assumed to be cropped twice
per year because rotation was expected to occur during the year with other crops. Alfalfa
crops were labeled for use in fall or winter, followed by a use on alfalfa grown for seed in
the spring. Therefore, two seasons were assumed to occur per year (winter and spring).
Turf uses were labeled for control of annual bluegrass (Poa Annua), which is expected to
occur in fall or winter (UCANR 2003), and control of perennial rye grass (Lolium
perenne) in the spring. Therefore, three seasons of use were assumed for turf (fall,
winter, and spring).
Table 2.3 Propyzamide Uses Assessed for the CRLF
Use Group
Current Uses
Max. Single Appl.
Rate (lbs a.i./A)
Max. Number of
Applieations per Year
Leafy vegetables
Lettuce, leaf lettuce, endive,
escarole, radicchio
2.00 (per crop)
2 (assuming two
crops/year)
Root and tuber
vegetables
Globe artichokes
4.08
2
Fruit
Apples, pears, apricots, cherries,
nectarines, peaches, plums, prunes,
grapes (including wine grapes)
4.08
1
Berries
Blueberries
2.04
1
Forage, feed, and
seed crops
Alfalfa, clover, birdsfoot trefoil,
crown vetch, sainfoin
2.00 (per season)
2 (assuming two
seasons/year)
Ornamentals1
Ornamental trees, plants, and shrubs,
Christmas trees
2.04
1
Turf1
Sod, turf
1.53 (per season)
3 (assuming three
seasons/year)
Fallow areas
Fallow land
0.510
1
1 This Use Group may include residential as well as non-residential uses.
Figure 2.1 presents the national usage pattern of propyzamide in 2002. Usage was
concentrated in California, the Pacific Northwest, and a few states in the eastern U.S.
Note that lettuce was estimated to represent 61% of propyzamide usage at that time.
Alfalfa and other field crops accounted for an additional 29% of propyzamide usage
(USGS 2007).
23
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PRONAMIDE - herbicide
2002 estimated annual agricultural use
Crops
Total
Percent
pounds applied
national use
lettuce
125610
61.27
alfalfa hay
30618
14.94
field and grass seed crop
29151
14.22
cropland in summer fallow
15205
7.42
artichokes
2066
1.01
grapes
1868
0.91
sod harvested
451
0.22
blueberries
22
0.01
beets
13
0.01
Average annual use of
active ingredient
(pounds par square mile of agricultural
land in county)
D no estimated use
~ 0.001 to 0.003
~ 0.004 to 0.012
~ 0.013 to 0.056
~ 0.057 to 0.371
¦ >=0.372
Figure 2.1 National Propyzamide Usage in 2002 (USGS 2007)
The Agency's Biological and Economic Analysis Division (BEAD) provides an analysis
of both national- and county-level usage information (Kaul and Jones 2006) using state-
level usage data obtained from the U. S. Department of Agriculture (USDA) National
Agricultural Statistics Service (NASS)2, Doane (www.doane.com; the full dataset is not
provided due to its proprietary nature) and the California's Department of Pesticide
Regulation (CDPR) Pesticide Use Reporting (PUR) database3. CDPR PUR is considered
a more comprehensive source of usage data than USD A NASS or EPA proprietary
databases, and thus the usage data reported for propyzamide by county in this California-
specific assessment were generated using CDPR PUR data. Four years (2002-2005) 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
2 United States Department of Agriculture (USDA), National Agricultural Statistics Service (NASS)
Chemical Use Reports provide summary pesticide usage statistics for select agricultural use sites by
chemical, crop and state. See http://www.usda.gOv/nass/pubs/estindxl.htm#agchem.
3 The California Department of Pesticide Regulation's (CDPR) Pesticide Use Reporting (PUR) database
provides a census of pesticide applications in the state. See http://www.cdpr.ca.gov/docs/pur/punnain.htm.
24
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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 four years.
A summary of propyzamide usage for all California use sites based on CDPR PUR data
is provided below in Table 2.4. The use sites of highest average annual usage in
California are head lettuce (55,000 lbs) and leaf lettuce (48,000 lbs). These use sites are
followed by globe artichokes and landscape maintenance at approximately 2,000 lbs, and
endive/escarole, chicory, and turf/sod at approximately 1,000 lbs. High reported
maximum application rates, such as for chicory, may reflect reporting errors or misuse of
the product. Because commercial applicators are required to report their usage, these
data are believed to be of high quality; the number of records reported for each site is
likely to reflect the actual number of commercial uses on that site in California from 2002
to 2005.
Table 2.4 Summary of California Department of Pesticide Registration (CDPR) Pesticide
Use Reporting (PUR) Data from 2002 to 2005 for Currently Registered Propyzamide Uses
Site Name (number of rceords)
Avjj Annual
Applieation
(lbs a.i.)
Avjj App
Rate (lbs
a.i./A)
95th %-ile
App Rate
(lbs a.i./A)
99th %-ile
App Rate
(lbs a.i./A)
Max App
Rate (lbs
a.i./A)
Alfalfa (22)
193
0.92
1.03
1.03
1.53
Apples (1)
2.30
1.15
1.15
1.15
1.15
Arrugula (1)
0.31
1.89
1.89
1.89
1.89
Artichoke, globe (511)
1,939
0.98
1.65
1.65
2.04
Beets (2)
6.26
2.04
2.04
2.04
2.04
Blueberries (1)
6.63
0.51
0.51
0.51
0.51
Bok choy (11)
14.6
1.79
1.79
1.79
2.04
Broccoli (39)
87.8
0.86
3.17
3.21
7.09
Cabbage (7)
15.2
1.21
1.22
1.22
2.06
Carrots (3)
1.48
1.59
2.00
2.00
2.00
Cauliflower (14)
15.8
0.45
1.02
1.02
1.02
Celery (4)
6.98
0.72
0.72
0.72
1.28
Chicory (484)
991
1.17
1.69
2.90
20.83
Chinese cabbage (1)
1.28
1.02
1.02
1.02
1.02
Chinese greens (11)
19.7
1.28
1.28
1.28
2.04
Christmas trees (3)
18.2
0.64
0.64
0.64
0.77
Clover (39)
410
0.97
1.02
1.02
1.02
Coconuts (1)
1.14
0.38
0.38
0.38
0.38
Corn (1)
0.13
1.02
1.02
1.02
1.02
Endive/escarole (1,492)
1,338
1.05
0.46
0.73
20.0
Fennel (1)
0.50
2.00
2.00
2.00
2.00
Grapes (1)
0.13
0.51
0.51
0.51
0.51
Grapes, wine (45)
73.2
0.64
1.26
4.26
19.5
Kale (1)
0.38
0.47
0.47
0.47
0.47
25
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Table 2.4 Summary of California Department of Pesticide Registration (CDPR) Pesticide
Use Reporting (PUR) Data from 2002 to 2005 for Currently Registered Propyzamide Uses
Site Name (number of rceords)
Avjj Annual
Applieation
(lbs a.i.)
Avjj App
Rate (lbs
a.i./A)
95th %-ile
App Rate
(lbs a.i./A)
99th %-ile
App Rate
(lbs a.i./A)
Max App
Rate (lbs
a.i./A)
Landscape maintenance (520)
1,910
Not reported
Not reported
Not reported
Not reported
Leeks (1)
0.89
2.10
2.10
2.10
2.10
Lettuce, head (20,897)
55,021
0.90
1.32
1.51
10.2
Lettuce, leaf (24,577)
48,222
0.95
1.43
1.76
6.22
Mizuna (1)
0.33
0.66
0.66
0.66
0.66
Mustard (9)
31.1
2.05
2.15
2.15
2.15
Nectarine (1)
0.13
1.55
1.55
1.55
1.55
Outdoor flowers (4)
0.63
1.03
1.34
1.34
1.53
Outdoor plants in containers (14)
161
1.25
2.04
2.04
2.04
Outdoor transplants (17)
14.1
0.27
0.38
0.38
1.02
Onions, dry (1)
0.38
1.53
1.53
1.53
1.53
Peaches(1)
0.26
1.02
1.02
1.02
1.02
Peppers, spice (1)
12.8
5.10
5.10
5.10
5.10
Pumpkins (1)
0.59
0.38
0.38
0.38
0.38
Radishes (1)
0.06
1.92
1.92
1.92
1.92
Range la nd (2)
0.38
1.79
2.04
2.04
2.04
Research commodity (584bs, 4-
rates)
26.6
1.22
2.18
2.18
2.32
Rights of way (14-lbs, 2-rates)
39.9
0.52
0.52
0.52
1.02
Soil fumigation/preplant (25)
49.9
1.09
1.23
1.23
2.04
Spinach (6)
10.2
0.96
1.19
1.19
1.53
Structural pest control (1)
0.89
Not reported
Not reported
Not reported
Not reported
Swiss chard (2)
2.13
1.05
1.05
1.05
2.04
Tropical/subtropical fruit (1)
3.83
0.76
0.76
0.76
0.76
Turf/sod (138)
921
1.36
3.65
3.84
17.6
Turnip (2)
0.50
1.52
1.52
1.52
1.52
Uncultivated agriculture (3)
5.29
2.60
2.74
2.74
3.40
Unknown (16)
79.1
1.16
1.56
1.56
2.81
Vegetables, leafy (10)
95.8
1.46
1.74
1.74
2.00
Vertebrate control (2)
2.75
0.79
1.02
1.02
1.02
2.5 Assessed Species
The CRLF was federally listed as a threatened species by USFWS effective June 24,
1996 (USFWS 1996). It is one of two subspecies of the red-legged frog and is the largest
native frog in the western United States (USFWS 2002). A brief summary of information
regarding CRLF distribution, reproduction, diet, and habitat requirements is provided in
Sections 2.5.1 through 2.5.4, respectively. Further information on the status, distribution,
and life history of and specific threats to the CRLF is provided in Attachment 1.
26
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Final critical habitat for the CRLF was designated by USFWS on April 13, 2006
(USFWS 2006; 71 FR 19244-19346). Further information on designated critical habitat
for the CRLF is provided in Section 2.6.
2.5.1 Distribution
The CRLF is endemic to California and Baja California (Mexico) and historically
inhabited 46 counties in California including the Central Valley and both coastal and
interior mountain ranges (USFWS 1996). Its range has been reduced by about 70%, and
the species currently resides in 22 counties in California (USFWS 1996). The species has
an elevational range of near sea level to 1,500 meters (5,200 feet) (Jennings and Hayes,
1994); however, nearly all of the known CRLF populations have been documented below
1,050 meters (3,500 feet) (USFWS 2002).
Populations currently exist along the northern California coast, northern Transverse
Ranges (USFWS 2002), foothills of the Sierra Nevada (5-6 populations), and in southern
California south of Santa Barbara (two populations) (Fellers, 2005a). Relatively larger
numbers of CRLFs are located between Marin and Santa Barbara Counties (Jennings and
Hayes, 1994). A total of 243 streams or drainages are believed to be currently occupied
by the species, with the greatest numbers in Monterey, San Luis Obispo, and Santa
Barbara counties (USFWS 1996). Occupied drainages or watersheds include all bodies
of water that support CRLFs (i.e., streams, creeks, tributaries, associated natural and
artificial ponds, and adjacent drainages), and habitats through which CRLFs can move
(i.e., riparian vegetation, uplands) (USFWS 2002).
The distribution of CRLFs within California is addressed in this assessment using four
categories of location including recovery units, core areas, designated critical habitat, and
known occurrences of the CRLF reported in the California Natural Diversity Database
(CNDDB) that are not included within core areas and/or designated critical habitat (see
Figure 2.2). Recovery units, core areas, and other known occurrences of the CRLF from
the CNDDB are described in further detail in this section, and designated critical habitat
is addressed in Section 2.6. Recovery units are large areas defined at the watershed level
that have similar conservation needs and management strategies. The recovery unit is
primarily an administrative designation, and land area within the recovery unit boundary
is not exclusively CRLF habitat. Core areas are smaller areas within the recovery units
that comprise portions of the species' historic and current range and have been
determined by USFWS to be important in the preservation of the species. Designated
critical habitat is generally contained within the core areas, although a number of critical
habitat units are outside the boundaries of core areas, but within the boundaries of the
recovery units. Additional information on CRLF occurrences from the CNDDB is used
to cover the current range of the species not included in core areas and/or designated
critical habitat, but within the recovery units.
27
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Recovery Units
Eight recovery units have been established by USFWS for the CRLF. These areas are
considered essential to the recovery of the species, and the status of the CRLF "may be
considered within the smaller scale of the recovery units, as opposed to the statewide
range" (USFWS 2002). Recovery units reflect areas with similar conservation needs and
population statuses, and therefore, similar recovery goals. The eight units described for
the CRLF are delineated by watershed boundaries defined by US Geological Survey
hydrologic units and are limited to the elevational maximum for the species of 1,500 m
above sea level. The eight recovery units for the CRLF are listed in Table 2.5 and shown
in Figure 2.2.
Core Areas
USFWS has designated 35 core areas across the eight recovery units to focus their
recovery efforts for the CRLF (see Figure 2.2). Table 2.5 summarizes the geographical
relationship among recovery units, core areas, and designated critical habitat. The core
areas, which are distributed throughout portions of the historic and current range of the
species, represent areas that allow for long-term viability of existing populations and
reestablishment of populations within historic range. These areas were selected because
they: 1) contain existing viable populations; or 2) they contribute to the connectivity of
other habitat areas (USFWS 2002). Core area protection and enhancement are vital for
maintenance and expansion of the CRLF's distribution and population throughout its
range.
For purposes of this assessment, designated critical habitat, currently occupied (post-
1985) core areas, and additional known occurrences of the CRLF from the CNDDB are
considered. Each type of locational information is evaluated within the broader context
of recovery units. For example, if no labeled uses of propyzamide occur (or if labeled
uses occur at predicted exposures less than the Agency's LOCs) within an entire recovery
unit, a "no effect" determination would be made for all designated critical habitat,
currently occupied core areas, and other known CNDDB occurrences within that
recovery unit. Historically occupied sections of the core areas are not evaluated as part of
this assessment because the USFWS Recovery Plan (USFWS 2002) indicates that CRLFs
are extirpated from these areas. A summary of currently and historically occupied core
areas is provided in Table 2.5 (currently occupied core areas are bolded). While core
areas are considered essential for recovery of the CRLF, core areas are not federally-
designated critical habitat, although designated critical habitat is generally contained
within these core recovery areas. It should be noted, however, that several critical habitat
units are located outside of the core areas, but within the recovery units. The focus of
this assessment is currently occupied core areas, designated critical habitat, and other
known CNDDB CRLF occurrences within the recovery units. Federally-designated
critical habitat for the CRLF is further explained in Section 2.6.
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Table 2.5 California Red-legged Frog Recovery Units with Overlapping Core
Areas and Designated Critical Habitat
Recovery Unit1
(Figure 2.a)
Core Areas 2,1 (Figure 2.a)
Critical Habitat
Units3
Currently
Occu|)icd
(post-1985)4
Historically
Occupied 4
Cottonwood Creek (partial)
(8)
Feather River (1)
BUT-1A-B
Yuba River-S. Fork Feather
YUB-1
Sierra Nevada
River (2)
Foothills and Central
--
NEV-16
Valley (1)
Traverse Creek/Middle Fork
(eastern boundary is
American River/Rubicon (3)
the 1,500m elevation
Consumnes River (4)
ELD-1
line)
S. Fork Calaveras River (5)
--
Tuolumne River (6)
--
Piney Creek (7)
--
East San Francisco Bay
(partial)(16)
Cottonwood Creek (8)
--
Putah Creek-Cache Creek (9)
--
North Coast Range
Foothills and
Western Sacramento
River Valley (2)
Jameson Canyon - Lower
Napa Valley (partial) (15)
--
Belvedere Lagoon (partial)
(14)
--
Pt. Reyes Peninsula (partial)
(13)
--
Putah Creek-Cache Creek
(partial) (9)
Lake Berryessa Tributaries
(10)
NAP-1
North Coast and
Upper Sonoma Creek (11)
--
North San Francisco
Petaluma Creek-Sonoma
Bay (3)
Creek (12)
Pt. Reyes Peninsula (13)
MRN-1, MRN-2
Belvedere Lagoon (14)
--
Jameson Canyon-Lower
Napa River (15)
SOL-1
--
CCS-1A6
East San Francisco Bay
ALA-1A, ALA-
South and East San
(partial) (16)
IB, STC-1B
Francisco Bay (4)
--
STC-1A6
South San Francisco Bay
(partial) (18)
SNM-1A
Central Coast (5)
South San Francisco Bay
(partial) (18)
SNM-1A, SNM-
2C, SCZ-1
Watsonville Slough- Elkhorn
Slough (partial) (19)
SCZ-2 5
Carmel River-Santa Lucia
MNT-2
(20)
Estero Bay (22)
~
29
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Table 2.5 California Red-legged Frog Recovery Units with Overlapping Core
Areas and Designated Critical Habitat
Recovery Unit1
(Figure 2.a)
Core Areas 2,1 (Figure 2.a)
Critical Habitat
Units3
Currently
Occupied
(post-1985)4
Historically
Occupied 4
--
SLO-86
Arroyo Grande Creek (23)
--
Santa Maria River-Santa
Ynez River (24)
East San Francisco Bay
MER-1A-B,
(partial) (16)
STC-1B
--
SNB-16, SNB-26
Diablo Range and
Salinas Valley (6)
Santa Clara Valley (17)
--
Watsonville Slough- Elkhorn
Slough (partial)(19)
MNT-1
Carmel River-Santa Lucia
(partial)(20)
Gablan Range (21)
SNB-3
Estrella River (28)
SLO-1A-B
--
SLO-86
Northern Transverse
Ranges and
Tehachapi Mountains
(7)
Santa Maria River-Santa
STB-4, STB-5,
Ynez River (24)
STB-7
Sisquoc River (25)
STB-1, STB-3
Ventura River-Santa Clara
VEN-1, VEN-2,
River (26)
VEN-3
--
LOS-16
Santa Monica Bay-Ventura
Coastal Streams (27)
San Gabriel Mountain (29)
--
Southern Transverse
Forks of the Mojave (30)
--
and Peninsular
Santa Ana Mountain (31)
--
Ranges (8)
Santa Rosa Plateau (32)
--
San Luis Rey (33)
--
Sweetwater (34)
--
Laguna Mountain (35)
--
1 Recovery units designated by the USFWS (USFWS 2000, pg 49).
2 Core areas designated by the USFWS (USFWS 2000, pg 51).
3 Critical habitat units designated by the USFWS on April 13, 2006 (USFWS 2006; 71 FR 19244-19346).
4 Currently occupied (post-1985) and historically occupied core areas as designated by the USFWS (USFWS 2002, pg 54).
5 Critical habitat unit where identified threats specifically included pesticides or agricultural runoff (USFWS 2002).
6 Critical habitat units that are outside of core areas, but within recovery units.
7 Currently occupied core areas that are included in this effects determination are bolded.
30
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Recovery Units
Sierra Nevada Foothills and Central Valley
North Coast Range Foothills and Western
Sacramento River Valley
North Coast and North San Francisco Bay
South and East San Francisco Bay
Central Coast
Diablo Range and Salinas Valley
Northern Transverse Ranges and Tehachapi
Mountains
Southern Transverse and Peninsular Ranges
Legend
] Recovery Unit Boundaries
Currently Occupied Core Areas
| Critical Habitat
| CNDDB Occurence Sections
County Boundaries
Figure 2.2 Recovery Unit, Core Area, Critical Habitat, and Occurrence
Designations for CRLF
Core Areas
1.
Feather River
20.
Carmel River - Santa Lucia
2.
Yuba River- S. Fork Feather River
21.
Gablan Range
3.
Traverse Creek/ Middle Fork/ American R. Rubicon
22.
Estero Bay
4.
Cosumnes River
23.
Arroyo Grange River
5.
South Fork Calaveras River*
24.
Santa Maria River - Santa Ynez River
6.
Tuolumne River*
25.
Sisquoc River
7.
Piney Creek*
26.
Ventura River - Santa Clara River
8.
Cottonwood Creek
27.
Santa Monica Bay - Venura Coastal Streams
9.
Putah Creek - Cache Creek*
28.
Estrella River
10.
Lake Berryessa Tributaries
29.
San Gabriel Mountain*
11.
Upper Sonoma Creek
30.
Forks of the Mojave*
12.
Petaluma Creek - Sonoma Creek
31.
Santa Ana Mountain*
13.
Pt. Reyes Peninsula
32.
Santa Rosa Plateau
14.
Belvedere Lagoon
33.
San Luis Ray*
15.
Jameson Canyon - Lower Napa River
34.
Sweetwater*
16.
East San Francisco Bay
35.
Laguna Mountain*
17.
Santa Clara Valley
18.
South San Francisco Bay
* Core areas that were historically occupied by the Califi
19.
Watsonville Slough-Elkhorn Slough
red-legged frog are not included in the map
31
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Other Known Occurrences from the CNDBB
The CNDDB provides location and natural history information on species found in
California. The CNDDB serves as a repository for historical and current species location
sightings. Information regarding known occurrences of CRLFs outside of the currently
occupied core areas and designated critical habitat is considered in defining the current
range of the CRLF. See: http://www.dfg.ca.gov/bdb/html/cnddb info.html for additional
information on the CNDDB.
2.5.2 Reproduction
CRLFs breed primarily in ponds; however, they may also breed in quiescent streams,
marshes, and lagoons (Fellers 2005a). According to the Recovery Plan (USFWS 2002),
CRLFs breed from November through late April. Peaks in spawning activity vary
geographically; Fellers (2005b) reports peak spawning as early as January in parts of
coastal central California. Eggs are fertilized as they are being laid. Egg masses are
typically attached to emergent vegetation, such as bulrushes (Scirpus spp.) and cattails
(Typha spp.) or roots and twigs, and float on or near the surface of the water (Hayes and
Miyamoto 1984). Egg masses contain approximately 2000 to 6000 eggs ranging in size
between 2 and 2.8 mm (Jennings and Hayes 1994). Embryos hatch 10 to 14 days after
fertilization (Fellers 2005a) depending on water temperature. Egg predation is reported
to be infrequent and most mortality is associated with the larval stage (particularly
through predation by fish); however, predation on eggs by newts has also been reported
(Rathburn 1998). Tadpoles require 11 to 28 weeks to metamorphose into juveniles
(terrestrial-phase), typically between May and September (Jennings and Hayes 1994,
USFWS 2002); tadpoles have been observed to over-winter (delay metamorphosis until
the following year) (Fellers 2005b; USFWS 2002). Males reach sexual maturity at 2
years, and females reach sexual maturity at 3 years of age; adults have been reported to
live 8 to 10 years (USFWS 2002). Figure 2.3 depicts CRLF annual reproductive timing.
Figure 2.3 CRLF Reproductive Events by Month
J
F
M
A
M
J
J
A
S
o
N
D
Light Blue = Breeding/Egg Masses
Green = Tadpoles (except those that over-winter)
Orange =
Adults and juveniles can be present all year
2.5.3 Diet
Although the diet of CRLF aquatic-phase larvae (tadpoles) has not been studied
specifically, it is assumed that their diet is similar to that of other frog species, with the
aquatic phase feeding exclusively in water and consuming diatoms, algae, and detritus
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(USFWS 2002). Tadpoles filter and entrap suspended algae (Seale and Beckvar 1980)
via mouthparts designed for effective grazing of periphyton (Wassersug 1984;
Kupferberg et al. 1994; Kupferberg 1997; Altig 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
examining the gut content of 35 juvenile and adult CRLFs, that the species feeds on as
many as 42 different invertebrate taxa, including Arachnida, Amphipoda, Isopoda,
Insecta, and Mollusca. The most commonly observed prey species were larval alderflies
(Sialis cf. californica), pillbugs (Armadilliadrium vulgare), and water striders (Gerris sp).
The preferred prey species, however, was the sowbug (Hayes and Tennant 1985). This
study suggests that CRLFs forage primarily above water, although the authors note other
data reporting that adults also feed under water, are cannibalistic, and consume fish. For
larger CRLFs, over 50% of the prey mass may consists of vertebrates such as mice, frogs,
and fish, although aquatic and terrestrial invertebrates were the most numerous food
items (Hayes and Tennant 1985). For adults, feeding activity takes place primarily at
night; for juveniles feeding occurs during the day and at night (Hayes and Tennant 1985).
2.5.4 Habitat
CRLFs require aquatic habitat for breeding, but also use other habitat types including
riparian and upland areas throughout their life cycle. CRLF use of their environment
varies; they may complete their entire life cycle in a particular habitat or they may utilize
multiple habitat types. Overall, populations are most likely to exist where multiple
breeding areas are embedded within varying habitats used for dispersal (USFWS 2002).
Generally, CRLFs utilize habitat with perennial or near-perennial water (Jennings et al.
1997). Dense vegetation close to water, shading, and water of moderate depth are habitat
features that appear especially important for CRLF (Hayes and Jennings 1988).
Breeding sites include streams, deep pools, backwaters within streams and creeks, ponds,
marshes, sag ponds (land depressions between fault zones that have filled with water),
dune ponds, and lagoons. Breeding adults have been found near deep (0.7 m) still or
slow moving water surrounded by dense vegetation (USFWS 2002); however, the largest
number of tadpoles have been found in shallower pools (0.26 - 0.5 m) (Reis 1999). Data
indicate that CRLFs do not frequently inhabit vernal pools, as conditions in these habitats
generally are not suitable (Hayes and Jennings 1988).
CRLFs also frequently breed in artificial impoundments such as stock ponds, although
additional research is needed to identify habitat requirements within artificial ponds
(USFWS 2002). Adult CRLFs use dense, shrubby, or emergent vegetation closely
associated with deep-water pools bordered with cattails and dense stands of overhanging
vegetation (http://www.fws.gov/endangered/features/rl frog/rlfrog.html#where).
In general, dispersal and habitat use depends on climatic conditions, habitat suitability,
and life stage. Adults rely on riparian vegetation for resting, feeding, and dispersal. The
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foraging quality of the riparian habitat depends on moisture, composition of the plant
community, and presence of pools and backwater aquatic areas for breeding. CRLFs can
be found living within streams at distances up to 3 km (2 miles) from their breeding site
and have been found up to 30 m (100 feet) from water in dense riparian vegetation for up
to 77 days (USFWS 2002).
During dry periods, the CRLF is rarely found far from water, although it will sometimes
disperse from its breeding habitat to forage and seek other suitable habitat under downed
trees or logs, industrial debris, and agricultural features (UWFWS 2002). According to
Jennings and Hayes (1994), CRLFs also use small mammal burrows and moist leaf litter
as habitat. In addition, CRLFs may also use large cracks in the bottom of dried ponds as
refugia; these cracks may provide moisture for individuals avoiding predation and solar
exposure (Alvarez 2000).
2.6 Designated Critical Habitat
In a final rule published on April 13, 2006, 34 separate units of critical habitat were
designated for the CRLF by USFWS (USFWS 2006; FR 51 19244-19346). A summary
of the 34 critical habitat units relative to USFWS-designated recovery units and core
areas (previously discussed in Section 2.5.1) is provided in Table 2.5.
'Critical habitat' is defined in the ESA as the geographic area occupied by the species at
the time of the listing where the physical and biological features necessary for the
conservation of the species exist, and there is a need for special management to protect
the listed species. It may also include areas outside the occupied area at the time of
listing if such areas are 'essential to the conservation of the species.' All designated
critical habitat for the CRLF was occupied at the time of listing. Critical habitat receives
protection under Section 7 of the ESA through prohibition against destruction or adverse
modification with regard to actions carried out, funded, or authorized by a federal
Agency. Section 7 requires consultation on federal actions that are likely to result in the
destruction or adverse modification of critical habitat.
To be included in a critical habitat designation, the habitat must be 'essential to the
conservation of the species.' Critical habitat designations identify, to the extent known
using the best scientific and commercial data available, habitat areas that provide
essential life cycle needs of the species or areas that contain certain primary constituent
elements (PCEs) (as defined in 50 CFR 414.12(b)). PCEs include, but are not limited to,
space for individual and population growth and for normal behavior; food, water, air,
light, minerals, or other nutritional or physiological requirements; cover or shelter; sites
for breeding, reproduction, rearing (or development) of offspring; and habitats that are
protected from disturbance or are representative of the historic geographical and
ecological distributions of a species. The designated critical habitat areas for the CRLF
are considered to have the following PCEs that justify critical habitat designation:
• Breeding aquatic habitat;
• Non-breeding aquatic habitat;
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• Upland habitat; and
• Dispersal habitat.
Further description of these habitat types is provided in Attachment 1.
Occupied habitat may be included in the critical habitat only if essential features within
the habitat may require special management or protection. Therefore, USFWS does not
include areas where existing management is sufficient to conserve the species. Critical
habitat is designated outside the geographic area presently occupied by the species only
when a designation limited to its present range would be inadequate to ensure the
conservation of the species. For the CRLF, all designated critical habitat units contain all
four of the PCEs, and were occupied by the CRLF at the time of FR listing notice in
April 2006. The FR notice designating critical habitat for the CRLF includes a special
rule exempting routine ranching activities associated with livestock ranching from
incidental take prohibitions. The purpose of this exemption is to promote the
conservation of rangelands, which could be beneficial to the CRLF, and to reduce the rate
of conversion to other land uses that are incompatible with CRLF conservation. Please
see Attachment 1 for a full explanation on this special rule.
USFWS has established adverse modification standards for designated critical habitat
(USFWS 2006). Activities that may destroy or adversely modify critical habitat are those
that alter the PCEs and jeopardize the continued existence of the species. Evaluation of
actions related to use of propyzamide that may alter the PCEs of the CRLF's critical
habitat form the basis of the critical habitat impact analysis. According to USFWS
(2006), activities that may affect critical habitat and therefore result in adverse effects to
the CRLF include, but are not limited to the following:
(1) Significant alteration of water chemistry or temperature to levels beyond the
tolerances of the CRLF that result in direct or cumulative adverse effects to
individuals and their life-cycles.
(2) Significant increase in sediment deposition within the stream channel or pond or
disturbance of upland foraging and dispersal habitat that could result in
elimination or reduction of habitat necessary for the growth and reproduction of
the CRLF by increasing the sediment deposition to levels that would adversely
affect their ability to complete their life cycles.
(3) Significant alteration of channel/pond morphology or geometry that may lead to
changes to the hydrologic functioning of the stream or pond and alter the timing,
duration, water flows, and levels that would degrade or eliminate the CRLF
and/or its habitat. Such an effect could also lead to increased sedimentation and
degradation in water quality to levels that are beyond the CRLF's tolerances.
(4) Elimination of upland foraging and/or aestivating habitat or dispersal habitat.
(5) Introduction, spread, or augmentation of non-native aquatic species in stream
segments or ponds used by the CRLF.
(6) Alteration or elimination of the CRLF's food sources or prey base (also
evaluated as indirect effects to the CRLF).
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As previously noted in Section 2.1, the Agency believes that the analysis of direct and
indirect effects to listed species provides the basis for an analysis of potential effects on
the designated critical habitat. Because propyzamide is expected to directly impact living
organisms within the action area, critical habitat analysis for propyzamide is limited in a
practical sense to those PCEs of critical habitat that are biological or that can be
reasonably linked to biologically mediated processes.
2.7 Action Area
For listed species assessment purposes, the action area is considered to be the area
affected directly or indirectly by the federal action and not merely the immediate area
involved in the action (50 CFR 402.02). It is recognized that the overall action area for
the national registration of propyzamide is likely to encompass considerable portions of
the United States based on its uses. However, the scope of this assessment limits
consideration of the overall action area to those portions that may be applicable to the
protection of the CRLF and its designated critical habitat within the state of California.
Deriving the geographical extent of this portion of the action area is the product of
consideration of the types of effects that propyzamide may be expected to have on the
environment, the exposure levels to propyzamide that are associated with those effects,
and the best available information concerning the use of propyzamide and its fate and
transport within the state of California.
The definition of action area requires a stepwise approach that begins with an
understanding of the federal action. As discussed earlier, the federal action is defined by
the currently labeled uses for propyzamide. An analysis of labeled uses and review of
available product labels was completed. This analysis indicates that the following uses
are considered as part of the federal action evaluated in this assessment: artichokes,
stone/pome fruit, grapes, alfalfa, clover, trefoil, crown vetch, sainfoin, blueberries,
lettuce, turf/grass for seed, ornamental trees/plants/shrubs, Christmas trees, and fallow
land.
After determination of which uses will be assessed, an evaluation of the potential
"footprint" of the use pattern is determined. This "footprint" represents the initial area of
concern and is typically based on available land cover data. Local land cover data
available for the state of California were analyzed to refine the understanding of potential
propyzamide uses. The initial area of concern is defined as all land cover types that
represent the labeled uses described above. The initial area of concern is represented by
1) agricultural land covers, which are assumed to represent vegetable and non-orchard
fruit crops as well as ornamental crops; 2) orchard and vineyard land covers; (3) pasture;
and (4) turf. The specific uses which correspond to each of these land covers are
depicted in Table 2.6. Maps representing the land cover types that make up the initial
areas of concern for these separate uses are depicted in Figures 2.4-2.7, These maps
represent the areas that may be directly affected by the federal action. It should be noted
that the action area for propyzamide is based on the endangered species LOCs for aquatic
and terrestrial plants. However, the portion of the action area that is relevant to the CRLF
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is based on the non-listed species LOCs for aquatic and terrestrial plants because the
CRLF does not have an obligate relationship w/plants.
Table 2.6 Propyzamide uses and their respective GIS land covers used to
depict the initial propyzamide action area for this assessment.
GIS Land Cover
Uses
Orchards/vineyards
Stone fruit, pome fruit, grapes, wine grapes
Cultivated Crops
Alfalfa and related crops, artichokes, blueberries, lettuce and leafy greens,
ornamentals
Pasture
Fallow land
Turf
Turf, grass for seed
Once the initial area of concern is defined, the next step is to compare the extent of that
area with the results of the screening-level risk assessment. In this assessment, transport
of propyzamide through runoff and spray drift is considered in deriving quantitative
estimates of propyzamide exposure to CRLF, its prey and its habitats.
Since this screening-level risk assessment defines taxa that are predicted to be exposed
through runoff and drift to propyzamide at concentrations above the Agency's Levels of
Concern (LOC), there is need to expand the action area to include areas that are affected
indirectly by this federal action. Two methods are employed to define the areas
indirectly affected by the federal action, and thus the total action area. These are the
down stream dilution assessment for determining the extent of the affected lotic aquatic
habitats (flowing water) and the spray drift assessment for determining the extent of the
affected terrestrial habitats and lentic aquatic habitats (non-flowing water). In order to
define the final action area relevant to uses of propyzamide, it is necessary to combine
areas directly affected, as well as aquatic and terrestrial habitats indirectly affected by the
federal action. It is assumed that lentic (standing water) aquatic habitats (e.g. ponds,
pools, marshes) overlapping with the terrestrial areas are also indirectly affected by the
federal action. The analysis of areas indirectly affected by the federal action, as well
as the determination of the final action area for propyzamide is described in the risk
discussion (Section 7.1). The action area for propyzamide, including the full extent
(based on the listed species LOCs) of the action area that is relevant for the CRLF is
presented graphically in Figure 2.8. Additional analysis related to the intersection of the
propyzamide action area and CRLF habitat used in determining the final action area is
described in Appendix D.
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Compiled from California County boundaries (ESRI, 2002),
USDA National Agriculture Statistical Service (NASS.2002)
Gap Analysis Program Orchard/Vineyard Landcover (GAP)
National Land Cover Database (NLCD) (MRLC.2001)
Map created by U.S. Environmental Protection Agency,
Office of Pesticides Programs, Environmental Fate and
Effects Division. April 11, 2007.
Projection: Albers Equal Area Conic USGS,
North American Datum of 1983 (NAD 1983)
Figure 2.4 Initial area of concern for crops described by orchard/vineyard land cover which
corresponds to potential propyzamide use sites. This map represents the area potentially directly
affected by the federal action.
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N
Legend
Agricultural La rid cove
County Boundary
90 45 0
90 Miles
Compiled from California County boundaries (ESRI, 2002),
USDA National Agriculture Statistical Service (NASS.2002)
Gap Analysis Program Orchard/Vineyard Landcover (GAP)
National Land Cover Database (NLCD) (MRLC, 2001)
Map created by U.S. Environmental Protection Agency,
Office of Pesticides Programs, Environmental Fate and
Effects Division. April 11, 2007.
Projection: Albers Equal Area Conic USGS,
North American Datum of 1983 (NAD 1983)
Figure 2.5 Initial area of concern for crops described by agricultural land cover which corresponds
to potential propyzamide use sites. This map represents the area potentially directly affected by the
federal action.
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-------
Compiled from California County boundaries (ESRI.2002),
USDA National Agriculture Statistical Service (NASS.2002)
Gap Analysis Program Orchard/Vineyard Landcover (GAP)
National Land Cover Database (NLCD) (MRLC,2001)
Map created by U.S. Environmental Protection Agency,
Office of Pesticides Programs, Environmental Fate and
Effects Division. April 11, 2007.
Projection: Albers Equal Area Conic USGS,
North American Datum of 1983 (NAD 1983)
Figure 2.6 Initial area of concern for crops described by pasture land cover which corresponds to
potential propyzamide use sites. This map represents the area potentially directly affected by the
federal action.
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Propyzamide Turf Initial Area of Concern
Compiled from California County boundaries (ESRI, 2002), Map created by US Environmental Protection Agency, Office
USCA National Agriculture Statistical Service (NASS, 2002) of Pesticides Programs, Environmental Fate and Effects Division.
Gap Analysis Program Orchard/ Vineyard Landcover (GAP) Projection: Albers Equal Area Conic USGS, North American
National Land Cover Database (NLCD) (MRLC, 2001) Datum of 1933 (NAD 1983).
Produced 1 >2/2008
Figure 2.7 Initial area of concern for crops described by turf land cover which corresponds to
potential propyzamide use sites. This map represents the area potentially directly affected by the
federal action.
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Propyzamide Action Area for All Uses
Legend
| propyzamide All Uses Buffered
| Critical habitat
Core areas
CNDDB overlap
~~I CNDDB occurence sections
Recovery units
County boundaries
Custom layout
0 25 50 100
M Kilometers
150 200
Compiled from California County boundaries (ESRI, 2002),
USDA National Agriculture Statistical Service (NASS, 2002)
Gap Analysis Program Orchard/Vineyard Landcover (GAP)
National Land Ccwer Database (NLCD) (MRLC, 2001)
Figure 2.8 Total action area for all propyzamide uses,
directly and indirectly affected by the federal action.
Map created by US Environmental Protection Agency, Office
of Pesticides Programs, Environmental Fate and Effects Dwision.
Projection: Albers Equal Area Conic USGS, NorthArnerican
Datum of 1983 (NAD 1983).
Produced 1/17/2008
This map represents the area potentially
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2.8 Assessment Endpoints and Measures of Ecological Effect
Assessment endpoints are defined as "explicit expressions of the actual environmental
value that is to be protected."4 Selection of the assessment endpoints is based on valued
entities (e.g., CRLF, organisms important in the life cycle of the CRLF, and the PCEs of
its designated critical habitat), the ecosystems potentially at risk (e.g., waterbodies,
riparian vegetation, and upland and dispersal habitats), the migration pathways of
propyzamide (e.g., runoff, spray drift, etc.), and the routes by which ecological receptors
are exposed to propyzamide (e.g., direct contact, etc.).
2.8.1. Assessment Endpoints for the CRLF
Assessment endpoints for the CRLF include direct toxic effects on the survival,
reproduction, and growth of the CRLF, as well as indirect effects, such as reduction of
the prey base or modification of its habitat. In addition, potential modification of critical
habitat is assessed by evaluating potential effects to PCEs, which are components of the
habitat areas that provide essential life cycle needs of the CRLF. Each assessment
endpoint requires one or more "measures of ecological effect," defined as changes in the
attributes of an assessment endpoint or changes in a surrogate entity or attribute in
response to exposure to a pesticide. Specific measures of ecological effect are generally
evaluated based on acute and chronic toxicity information from registrant-submitted
guideline tests that are performed on a limited number of organisms. Additional
ecological effects data from the open literature are also considered.
A complete discussion of all the toxicity data available for this risk assessment, including
resulting measures of ecological effect selected for each taxonomic group of concern, is
included in Section 4 of this document. A summary of the assessment endpoints and
measures of ecological effect selected to characterize potential assessed direct and
indirect CRLF risks associated with exposure to propyzamide is provided in Table 2.7.
4FromU.S. EPA (1992). Framework for Ecological Risk Assessment. EPA/630/R-92/001.
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Table 2.7 Assessment Endpoints and Measures of Ecological Effects
Assessment Endpoint
IMcasu res of Ecological Effects
Aquatic-Phase CRLF
(Eggs, larvae, and adults)3
Direct Effects
1. Survival, growth, and reproduction of CRLF
la. Most sensitive fish acute LC50 (guideline study)
since no suitable amphibian data are available
lb. Estimated fish chronic NOAEC (based on
freshwater invertebrate acute-to-chronic ratio)
Indirect Effects and Critical Habitat Effects
2. Survival, growth, and reproduction of CRLF
individuals via indirect effects on aquatic prey food
supply (i.e., fish, freshwater invertebrates, non-
vascular plants)
2a. Most sensitive fish, aquatic invertebrate, and
aquatic plant EC50 or LC50 (guideline studies)
2b. Most sensitive aquatic invertebrate and fish
chronic NOAEC (fish NOAEC based on estimate
using mammalian acute-to-chronic ratio)
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)
3a. Vascular plant acute EC50 (duckweed guideline
test)
3b. Non-vascular plant acute EC50 (freshwater
algae)
4. Survival, growth, and reproduction of CRLF
individuals via effects to riparian vegetation
4a. Most sensitive EC25 values for monocots
(guideline seedling emergence and vegetative vigor
studies)
4b. Most sensitive EC25 values for dicots (guideline
seedling emergence and vegetative vigor studies)
Terrestrial-Phase CRLF
(Juveniles and adults)
Direct Effects
5. Survival, growth, and reproduction of CRLF
individuals via direct effects on terrestrial phase
adults and juveniles
5a. Most sensitive birdb acute LD50 (guideline
study)
5b. Most sensitive birdb chronic NOAEC
(estimated using mammalian acute-to-chronic ratio)
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)
6a. Most sensitive terrestrial invertebrate and
vertebrate acute EC50 or LC50 (guideline studies)0
6b. Most sensitive terrestrial invertebrate and
vertebrate chronic NOAEC (guideline studies)
7. Survival, growth, and reproduction of CRLF
individuals via indirect effects on habitat (i.e.,
riparian and upland vegetation)
7a. Most sensitive EC25 for monocots (guideline
seedling emergence and vegetative vigor studies)
7b. Most sensitive EC25 for dicots (guideline
seedling emergence and vegetative vigor studies)
a Adult frogs are no longer in the "aquatic-phase" of the amphibian life cycle; however, submerged adult
frogs are considered "aquatic" for the purposes of this assessment because exposure pathways in the water
are considerably different that exposure pathways on land.
b Birds are used as surrogates for terrestrial-phase amphibians.
2.8.2 Assessment Endpoints for Designated Critical Habitat
As previously discussed, designated critical habitat is assessed to evaluate actions related
to the use of propyzamide that may alter the PCEs of the CRLFs critical habitat. PCEs
for the CRLF were previously described in Section 2.6. Actions that may modify critical
habitat are those that alter the PCEs and jeopardize the continued existence of the CRLF.
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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 propyzamide effects data are available.
Adverse modification to the critical habitat of the CRLF includes, but is not limited to,
the following, as specified by USFWS (2006):
1. Alteration of water chemistry/quality including temperature, turbidity, and
oxygen content necessary for normal growth and viability of juvenile and
adult CRLFs.
2. Alteration of chemical characteristics necessary for normal growth and
viability of juvenile and adult CRLFs.
3. Significant increase in sediment deposition within the stream channel or pond
or disturbance of upland foraging and dispersal habitat.
4. Significant alteration of channel/pond morphology or geometry.
5. Elimination of upland foraging and/or aestivating habitat, as well as dispersal
habitat.
6. Introduction, spread, or augmentation of non-native aquatic species in stream
segments or ponds used by the CRLF.
7. Alteration or elimination of the CRLF's food sources or prey base.
Measures of such possible effects by labeled use of propyzamide on critical habitat of the
CRLF are described in Table 2.8. Some components of these PCEs are associated with
physical abiotic features {e.g., presence and/or depth of a water body, or distance between
two sites), which are not expected to be measurably altered by use of pesticides.
Assessment endpoints used for the analysis of designated critical habitat are based on the
adverse modification standard established by USFWS (2006).
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Table 2.8 Summary of Assessment Endpoints and Measures of Ecological Effect for
Primary Constituent Elements of Designated Critical Habitat"
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.
a. Most sensitive EC50 values for aquatic plants (guideline
studies)
b. Most sensitive EC25 values for terrestrial monocots
(guideline seedling emergence and vegetative vigor studies)
c. Most sensitive EC25 values for terrestrial dicots
(guideline seedling emergence and vegetative vigor studies)
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.
a. Most sensitive EC50 or LC50 values for fish and aquatic
invertebrates (guideline studies)
b. Most sensitive NOAEC values for fish and aquatic
invertebrates (guideline studies). Chronic NOAEC for fish
based on estimate derived using mammalian acute-to-
chronic ratio.
Reduction and/or modification of aquatic-based food
sources for pre-metamorphs (e.g., algae)
a. Most sensitive aquatic plant EC50 (guideline study)
Terrestrial-Phase CRLF PCEs
(Upland Habitat and Dispersal Habitat)
Elimination and/or disturbance of upland habitat;
ability of habitat to support food source of CRLFs:
Upland areas within 200 ft of the edge of the riparian
vegetation or dripline surrounding aquatic and riparian
habitat that are comprised of grasslands, woodlands,
and/or wetland/riparian plant species that provides the
CRLF shelter, forage, and predator avoidance
a. Most sensitive EC25 values for monocots (guideline
seedling emergence and vegetative vigor studies)
b. Most sensitive EC25 values for dicots (guideline seedling
emergence and vegetative vigor studies)
c. Most sensitive food source acute EC50/LC50 and NOAEC
values for terrestrial vertebrates (mammals) and
invertebrates, birds, and freshwater fish. (NOAEC for birds
and fish derived using mammalian acute-to-chronic ratio)
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.
a Physico-chemical water quality parameters such as salinity, pH, and hardness are not evaluated because these processes are not
biologically mediated and, therefore, are not relevant to the endpoints included in this assessment.
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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 (USEPA 1998). For this assessment, the risk
is stressor-linked, where the stressor is the release of propyzamide to the environment.
The following risk hypotheses are presumed for this endangered species assessment:
The labeled use of propyzamide 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.
• 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 propyzamide release mechanisms, biological receptor types, and effects
endpoints of potential concern. The conceptual models for aquatic and terrestrial phases
of the CRLF are shown in Figures 2.9 and 2.10, respectively, and the conceptual models
for the aquatic and terrestrial PCE components of critical habitat are shown in Figures
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2.11 and 2.12, respectively. 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.
Figure 2.9 Conceptual Model for Aquatic-Phase of the CRLF
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^ropyzamicteapplied to agricultural and non-agricultural use sites in California |
Stressor
Figure 2.10 Conceptual Model for Terrestrial-Phase of the CRLF
Figure 2.11 Conceptual Model for Pesticide Effects on Aquatic Component of
CRLF Critical Habitat
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Figure 2.12 Conceptual Model for Pesticide Effects on Terrestrial Component of
CRLF Critical Habitat
2.10 Analysis Plan
In order to address the risk hypothesis, the potential for direct and indirect effects to the
CRLF, its prey, and its habitat is estimated. In the following sections, the use,
environmental fate, and ecological effects of propyzamide 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 (USEPA 2004), the
likelihood of effects to individual organisms from particular uses of propyzamide is
estimated using the probit dose-response slope and either the level of concern (discussed
below) or actual calculated risk quotient value.
2.10.1 Measures to Evaluate the Risk Hypothesis and Conceptual Model
2.10.1.1 Measures of Exposure
The environmental fate properties of propyzamide along with available monitoring data
indicate that runoff and spray drift are the principle potential transport mechanisms of
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propyzamide to the aquatic and terrestrial habitats of the CRLF. Due to the water
solubility and relatively low vapor pressure of propyzamide, atmospheric transport is
considered unlikely. In this assessment, transport of propyzamide through runoff and
spray drift is considered in deriving quantitative estimates of exposure to CRLF, its prey
and its habitats.
Measures of exposure are based on aquatic and terrestrial models that predict estimated
environmental concentrations (EECs) of propyzamide using maximum labeled
application rates and methods of application. The models used to predict aquatic EECs
are the Pesticide Root Zone Model coupled with the Exposure Analysis Modeling
System (PRZM/EXAMS). The model used to predict terrestrial EECs on food items is
Terrestrial Residue Exposure (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, 5/12/2005) and EXAMS (v2.98.4.6, 4/25/2005) are screening simulation
models coupled with the input shell PE (v5.0, 11/15/2006) to generate daily exposures
and l-in-10 year EECs of propyzamide that may occur in surface water bodies adjacent to
application sites receiving propyzamide 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 propyzamide. 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 1-in-10-year 60-day mean is
used for assessing chronic exposure to the CRLF and fish and frogs serving as prey
items; the 1-in-10-year 21-day mean is used for assessing chronic exposure for aquatic
invertebrates, which are also potential prey items.
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 are derived using the T-REX model (vl.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 propyzamide through contaminated food are estimated using the EECs for
the small bird (20 g) which consumes small insects. Dietary-based and dose-based
exposures of potential prey (small mammals) are assessed using the small mammal (15 g)
which consumes short grass. The small bird (20g) consuming small insects and the small
mammal (15g) consuming short grass are used because these categories represent the
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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
propyzamide 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. 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
(vl.3.1) has been refined to the Terrestrial Herptafaunal Exposure and Residue Program
Simulation (T-HERPS) model (vl.O, 5/15/2007), which allows for an estimation of food
intake for poikilotherms using the same basic procedure as T-REX to estimate food
intake.
EECs for terrestrial plants inhabiting dry and wetland areas are derived using TerrPlant
(vl.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.
The spray drift model AGricultural DISPersal (AGDISP v8.15; 5/12/2005) was used to
assess exposures of terrestrial-phase CRLF and its prey to propyzamide deposited on
terrestrial and aquatic lentic habitats by spray drift (Teske and Curbishley 2003).
AGDISP was used to simulate aerial and ground applications using the Gaussian farfield
extension. The mechanistic ground boom component of AGDISP has not been approved
for use in risk assessment and, therefore, generates exposure estimates of greater
uncertainty than those based on aerial applications. Due to this uncertainty, exposure
estimates from aerial application were used to characterize exposure estimates based on
ground applications.
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 chemical toxicity data for aquatic
life, terrestrial plants, and wildlife. ECOTOX was created and is maintained by the
USEPA, Office of Research and Development, and the National Health and
Environmental Effects Research Laboratory's Mid-Continent Ecology Division.
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The assessment of risk for direct effects to the terrestrial-phase CRLF makes the
assumption that toxicity of propyzamide 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 LC50 is the concentration of a chemical that is
estimated to kill 50% of the test organisms. EC stands for "Effective Concentration" and
the EC50 is the concentration of a chemical that is estimated to produce a specific effect in
50% of the test organisms. Endpoints for chronic measures of exposure for listed and
non-listed animals are the NOAEL/NOAEC and NOEC. NOAEL stands for "No
Ob served-Adverse-Effect-Level" and refers to the highest tested dose of a substance that
has been reported to have no harmful (adverse) effects on test organisms. The NOAEC
(i.e., "No-Observed-Adverse-Effect-Concentration") is the highest test concentration at
which none of the observed effects were statistically different from the control. The
NOEC is the No-Observed-Effects-Concentration. For non-listed plants, only acute
exposures are assessed (i.e., EC25 for terrestrial plants and EC50 for aquatic plants).
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
propyzamide, 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 propyzamide risks, the risk quotient (RQ) method is used to compare exposure and
measured toxicity values. EECs are divided by acute and chronic toxicity values. The
resulting RQs are then compared to the Agency's levels of concern (LOCs) (USEPA
2004) (see Appendix C).
For this endangered species assessment, LOCs are used for comparing RQ values for
acute and chronic exposures of propyzamide to the CRLF and its habitat. If estimated
exposures of propyzamide resulting from a particular use are sufficient to exceed the
listed species LOC, then the effects determination for that use is "may affect". When
considering indirect effects to the CRLF due to effects to animal prey (aquatic and
terrestrial invertebrates, fish, frogs, and mice), the listed species LOCs are also used. If
estimated exposures to CRLF prey of propyzamide resulting from a particular use are
sufficient to exceed the listed species LOC, then the effects determination for that use is a
"may affect." If the RQ being considered also exceeds the non-listed species acute risk
LOC, then the effects determination is a LAA. If the acute RQ is between the listed
species LOC and the non-listed acute risk species LOC, further lines of evidence (i.e.
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probability of individual effects, species sensitivity distributions) are considered in
distinguishing between a determination of NLAA and a LAA. When considering indirect
effects to the CRLF due to effects to algae as dietary items or plants as habitat, the non-
listed species LOC for plants is used because the CRLF does not have an obligate
relationship with any particular aquatic and/or terrestrial plant. If the RQ being
considered for a particular use exceeds the non-listed species LOC for plants, the effects
determination is "may affect". Further information on LOCs is provided in Appendix C.
2.10.2 Data Gaps
Neither acute nor chronic amphibian toxicity data are available for propyzamide;
therefore, surrogate species are used for estimating the toxicity of propyzamide to
amphibians. Chronic toxicity data are not available for fish and birds, which serve as
surrogates for aquatic-phase and terrestrial-phase amphibians, respectively. In the
absence of these data, an acute to chronic ratio was developed (see Section 4.2.2.2) and
used to estimate the chronic toxicity of propyzamide to birds and fish.
3. Exposure Assessment
Propyzamide is formulated as a wettable powder in water soluble pouches and can be
applied pre-plant, pre-emergence, and post-emergence by ground or aerial spray
equipment, depending on the use. Wetting in of applications is recommended with
rainfall or irrigation so that the compound is available for uptake into the root system.
Most application timing occurs in the fall or early winter prior to freezing. The
maximum annual application rate for current propyzamide uses is 8.16 pounds of active
ingredient per acre (lbs a.i./A).
3.1 Label Application Rates and Intervals
Propyzamide labels may be categorized into two types: labels for manufacturing uses
(including technical grade propyzamide and its formulated products) and end-use
products. While technical products, which contain propyzamide of high purity, are
not used directly in the environment, they are used to make formulated products,
which can then be applied in specific areas to control weeds. The formulated product
labels legally limit propyzamide's potential use to only those sites that are specified
on the labels.
Currently registered agricultural and non-agricultural uses of propyzamide within
California include those listed in Table 2.3. The maximum use patterns being
assessed are summarized in Table 3.1.
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Table 3.1 Propyzamide Maximum Use Patterns in the C.RLF Action Area
Use(s)
Max. Single
App. Rate
(lbs a.i./A)
Number of
App. per Year
Annual
App. Rate
(lbs a.i./A)
App. Interval
(days)
App. Method
Stone fruit, pome fruit,
grapes
4.08
1
4.08
Not applicable
Ground
Blueberries
2.04
1
2.04
Not applicable
Ground
Artichokes
4.08
2
8.16
Not specified
Aerial/ground
Lettuce, endive, escarole
and radicchio
2.00 (per
crop)
2 (assuming two
crops/year)
4.00
Not specified
Ground
Alfalfa, clover, trefoil,
crown vetch, sainfoin
2.00 (per
season)
2 (assuming two
seasons/year)
4.00
Not specified
Ground
Turf, grass for seed
1.53
3 (assuming
three
seasons/year)
4.59
Not specified
Ground
Ornamental trees, plants,
shrubs and Christmas
trees
2.04
1
2.04
Not applicable
Ground
Fallow land
0.510
1
0.510
Not applicable
Aerial/ ground
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 propyzamide 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
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 larger 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 propyzamide were
used for modeling, including application rates, number of applications per year,
application intervals, and the first application date for each crop. Application dates and
- 55 -
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intervals were developed based on several sources of information including product
labels, crop profiles maintained by the USDA (USDA 2007), and publications maintained
by the University of California (UCANR 2003).
3.2.2 Model Inputs
The model input parameters used in PRZM/EXAMS to simulate propyzamide application
and crop management practices are listed in Table 3.2. The input files used for modeling
are listed in Appendix B. Grapes were modeled with each applicable scenario to
estimate exposure from use on table grapes and wine grapes. Alfalfa and related crops
were modeled with the representative alfalfa application scenario for both seed and
forage uses and not with the more vulnerable rangeland scenario for forage uses because
the latter was not representative of legume crops.
Applications to ornamentals were timed to precede leaf drop. Applications to Christmas
trees, fallow land, berries, and fruit were timed to occur in the fall prior to ground
freezing. Leafy vegetables treated by propyzamide were assumed to be cropped twice
per year because rotation was expected to occur during the year with other crops.
Applications were modeled in February and August. Alfalfa crops are labeled for use in
fall or winter, followed by a use on alfalfa grown for seed in the spring. Therefore, two
seasons were assumed to occur per year (winter and spring), with applications modeled in
January and April. Turf uses are labeled for control of annual bluegrass (Poa Annua),
which is expected to occur in fall or winter (UCANR 2003), and control of perennial rye
grass (Lolium perenne) in the spring. Therefore, three seasons of use were assumed for
turf (fall, winter, and spring), with applications modeled in March, September, and
December. Ground application equipment is required for all uses except for use on
artichokes and fallow land.
Table 3.2 PRZM/EXAMS Cro
j Input Parameters for Propyzamide
Use Pattcrn(s)
Scenario
A pp. Rate in
lbs a.i./A
(kjj a.i./ha)
App.
per
Year
App.
Interval
(days)
Date of
Initial
App.
App.
Method
CAM
Input
IPSCND
Input
Artichoke
CArowcropRLF
4.08 (4.57)
2
120 d
Jan. 15
Aerial
2
1
Stone fruit,
pome fruit
CAfruitSTD
4.08 (4.57)
1
N/A
Nov. 21
Ground
1
3
Grapes, wine
grapes1
CAgrapesSTD,
CAwinegrapesRLF
4.08 (4.57)
1
N/A
Nov. 21
Ground
1
1
Alfalfa, clover,
trefoil, crown
vetch, sainfoin
CAalfalfaOP
2.00 (2.24)
2
98 d
Jan. 7
Ground
1
1
Blueberries
CAwinegrapesRLF
2.04 (2.29)
1
N/A
Nov. 21
Ground
1
3
Lettuce
CAlettuceSTD
2.00 (2.24)
2
180 d
Feb. 2
Ground
1
1
Turf, grass for
seed
CAturfRLF
1.53 (1.72)
3
180 d,
90 d
Mar. 15
Ground
2
1
Ornamentals
CAnurserySTD
2.04 (2.29)
1
N/A
Nov. 1
Ground
2
1
- 56 -
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Table 3.2 PRZM/EXAMS Cro
j Input Parameters for Propyzamide
Use Pattcrn(s)
Scenario
App. Rate in
lbs a.i./A
(k«i a.i./ha)
App.
per
Year
App.
Interval
(days)
Date of
Initial
App.
App.
Method
CAM
Input
IPSCND
Input
Christmas trees
CAforestryRLF
2.04 (2.29)
1
N/A
Nov. 21
Ground
2
1
Fallow land
CArangelandRLF
0.510 (0.572)
1
N/A
Nov. 21
Aerial
1
1
1 Both scenarios available for use on grapes were modeled.
The general chemical and environmental fate data for propyzamide listed in Table 3.3
were used for generating model input parameters for PRZM/EXAMS. The chemical and
mobility inputs were based on propyzamide parent and used as representative estimates
for the residues of concern. Degradation half-lives were calculated directly accounting
for the residues of concern. High-end confidence bounds on the mean half-life for total
residues were used to represent biodegradation half-life inputs.
Table 3.3 PRZM/EXAMS Chemical Input Parameters for Propyzamide Based on Total
Residues.
Input Parameter
Value
Justification
Source
Molecular Mass (g/mol)
256.13
Product chemistry data
USEPA 1994
Vapor Pressure at 25°C
(torr)
8.5 x 10"5
Study value
USEPA 1994
Solubility in Water at 25°C
(mg/L)
150
Represents lOx the measured water
solubility value.
USEPA 1994
Freundlich Organic Carbon
Partition Coefficient (KFOc)
(L/kgoc)
841
Represents the average KFOc-
MRID 40211103
Aerobic Soil Metabolism
Half-life (days)
1580
Represents the 90th percentile confidence
bound on the mean total residue half-life.
MRID 41568901
MRID 46413407
Aerobic Aquatic
Metabolism Half-life (days)
1020
Represents the 90th percentile confidence
bound on the mean total residue half-life.
MRID 46427901
Anaerobic Aquatic
Metabolism Half-life (days)
1210
Represents 3 times a single total residue
half-life.
MRID 46413408
Hydrolysis Half-lives (days)
Stable (pH 5)
Stable (pH 7)
Stable (pH 9)
Study values
MRID 00107980
Aqueous Photolysis
Half-life (days)
217
Represents the single environmental
phototransformation total residue half-life.
MRID 40420301
3.2.3 Results
The aquatic total residue EECs for the various scenarios and application practices are
listed in Table 3.4. The highest exposure estimates are for lettuce, although this use does
not have the highest use rate in terms of pounds of active ingredient per acre (lbs a.i./A).
- 57 -
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Table 3.4 Surface Water l-in-10-year Total Residue EECs of Propyzamide from Use
Patterns in the CRLF Action Area (maximum values in bold)
Crop
Annual
A pp. Rate
(lbs a.i./A)
Peak EEC
(ppb)
4-Dav Avjj
EEC (ppb)
21-Day Avjj
EEC (ppb)
60-Dav Avjj
EEC (ppb)
90-Dav Av«
EEC (ppb)
Artichokes
8.16
155
154
150
145
143
Stone fruit, pome fruit
4.08
35.4
35.0
32.9
29.6
28.7
Grapes
4.08
37.2
36.8
33.2
30.8
30.0
Wine grapes
4.08
64.9
61.4
57.3
54.5
53.3
Blueberries
2.04
32.4
30.7
28.7
27.3
26.6
Alfalfa, clover, trefoil,
crown vetch, sainfoin
4.00
31.2
30.9
30.0
28.7
28.2
Lettuce
4.00
225
225
220
211
207
Turf, grass for seed
4.59
40.8
40.7
40.1
39.1
38.6
Ornamentals
2.04
51.8
51.4
50.0
47.7
45.7
Christmas trees
2.04
47.0
46.7
45.4
40.6
39.8
Fallow land
0.510
13.9
13.8
13.4
12.9
12.6
3.2.4 Existing Monitoring Data
Reviews of both ground water and surface water monitoring data on propyzamide were
conducted for the 2002 TRED (USEPA 2002a) and the 2007 new use drinking water
exposure assessment (USEPA 2007). This assessment contains additional cursory review
of currently available monitoring data. The available monitoring data are consistent with
the peak (3.7-10.3 |ig/L) and annual mean (0.53-4.45 |ig/L) exposure estimates of
propyzamide per se in support the 2002 TRED (USEPA 2002a). Monitoring data are not
available on the degradates of propyzamide. Therefore, exposure estimates of total
residues of concern (which are up to three orders of magnitude higher than detected
concentrations of the parent compound) cannot be predicted with monitoring data.
3.2.4.1 California Department of Pesticide Regulation Data
The California Department of Pesticide Regulation (DPR) Surface Water Database
contains monitoring data of pesticides in California from 1990 to 2005 (CDPR 2006).
Propyzamide was detected in 8% of 1,678 samples in the state, with the majority of
detections occurring in water bodies of the Sacramento Valley. The maximum
concentration of propyzamide reported in this database was 0.25 |ig/L, detected in Yolo
County in February, 1994.
3.2.4.2 USGS NAWQA Data
The USGS NAWQA national database currently contains monitoring data of pesticides
from 1992 through 2005 (USGS 2006). In surface water, propyzamide was detected
above the level of quantitation (0.003 |ig/L) in 2.2% of samples (459 of 20,720 samples).
- 58 -
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The maximum measured surface water concentration was 1.12 |ig/L in Shelby County,
Tennessee in January, 2003. In ground water, propyzamide was detected above the level
of quantitation in 0.05% of samples (5 of 9,624 samples). The maximum measured
ground water concentration was 0.820 |ig/L in Benton County, Arkansas in April, 1994.
Propyzamide was analyzed in surface water within the State of California 2,003 times,
yielding 71 detections (3.5%). Table 3.5 lists the water body sites where detections of
propyzamide occurred. Concentrations at these sites were often near the detection limits
of 0.0030-0.0041 |ig/L and as high as 0.110 |ig/L (Stanislaus County). The highest
detection rates tended to occur at sites within Yolo and Merced Counties.
Table 3.5 California Water Body Sites with Detections of Propyzamide Reported
in NAWQA (USGS 2006)
Sites Name
County
# Samples
Detection
Rate
Sampling
Dates
Detected
Conccntration(s)
(HS/L)
CULVERT DISCHARGE TO
MUSTANG C AT MONTE
VISTA AVE
MERCED
26
3.8%
Dec. 2002 -
Feb. 2004
0.00670
MUD SLOUGH NR GUSTINE
CA
MERCED
24
4.2%
Jim. 1994 -
Aug. 2001
0.00388
MUSTANG C AT MONTE
VISTA AVE NR
MONTPELIER CA
MERCED
23
8.7%
Dec. 2002 -
Mar. 2004
0.00730, 0.00860
MUSTANG C AT NEWPORT
RD NR BALLICO CA
MERCED
7
29%
Nov. 2002 -
Dec. 2002
0.00390, 0.00480
SALT SLOUGH AT HWY 165
NR STEVINSON CA
MERCED
49
18%
Jan. 1993 -
Aug. 2001
0.00330-0.0414
SAN JOAQUIN RNR
STE VINSON CA
MERCED
62
9.7%
Jun. 1994 -
Aug. 2001
0.00374-0.0298
SANTA ANA R BL PRADO
DAM CA
RIVERSIDE
44
2.3%
Jul. 2000 -
Aug. 2005
0.0367
SACRAMENTO RAT
FREEPORT CA
SACRAMENTO
105
0.95%
Nov. 1996 -
Sep. 2005
0.00414
SAN JOAQUIN RNR
VERNALIS CA
SAN JOAQUIN
300
0.67%
Apr. 1992 -
Aug. 2005
0.00250-0.00530
HARDING DRAIN AT
CARPENTER RDNR
PATTERSON CA
STANISLAUS
37
2.7%
Apr. 1992 -
Aug. 2001
0.110
ORESTIMBA CR AT RIVER
RD NR CROWS LANDING
CA
STANISLAUS
271
5.5%
Apr. 1992 -
Sep. 2005
0.0030-0.0070
SAN JOAQUIN RAT
PATTERSON BR NR
PATTERSON CA
STANISLAUS
47
8.5%
Jun. 1994 -
Aug. 2001
0.00796, 0.00907,
0.0126, 0.0158
STANISLAUS RAT
CASWELL STATE PARK NR
RIPON CA
STANISLAUS
64
3.1%
Feb. 1994 -
Aug. 2001
0.00502,0.0107
SACRAMENTO SLOUGH NR
KNIGHTS LANDING CA
SUTTER
35
2.9%
Nov. 1996 -
Sep. 2004
0.0030
- 59 -
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Table 3.5 California Water Body Sites with Detections of Propyzamide Reported
in NAWQA (USGS 2006)
Sites Name
County
# Samples
Dctcetion
Rate
Sampling
Dates
Deteeted
Coneentration(s)
(Mg/L)
COLUSA BASIN DR AT RD
99E NR KNIGHTS LANDING
CA
YOLO
21
38%
Nov. 1996 -
Apr. 1998
0.00941 -0.0347
YOLO BYPASS AT 1-80 NR W
SACRAMENTO CA
YOLO
7
14%
Jan. 1997 -
Mar. 2004
0.00307
NAWQA reports 678 analyses of propyzamide in ground water within the State of
California from August 1992 to September 2005. No detections were found above
detection limits (0.0030-0.0041 |ig/L).
The NAWQA program is designed to broadly characterize water quality and is thus not
targeted to any particular pesticide or use site. Surface water sites are almost exclusively
on flowing water bodies and the majority of these are third-order streams or higher.
NAWQA water sampling for pesticides is biased toward sampling during the spring and
summer, which is when most pesticide applications are expected to occur. This would be
sub-optimal for propyzamide, as it usually applied in the fall and early winter.
3.2.4.3 USGS NASQAN Data
The USGS NASQAN national database contains monitoring data of pesticides by
regional basin from 1996 to 2000 (USGS 2006a). The maximum concentration of
propyzamide detected in this program was 0.125 |ig/L in the Colorado Basin in June,
1997. Concentrations of propyzamide were detected above the reporting limit in the
Columbia, Colorado, Rio Grande, and Mississippi Basins; however, detections only
occurred in the Northwest and Southwest at sites outside of the State of California, as
shown in Figure 3.1.
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REGIONAL BASINS DEFINED BY NASQAN STATIONS SHOWING PERCENTAGE OF WATER
SAMPLES HAVING CONCENTRATION ABOVE REPORTING LIMIT FOR
EXPLANATION
PERCENTAGE.
CONCENTRATION ABOVE
REPORTING UMIT
¦ 0
¦ 1-10
¦ 11-25
¦ 26 - BO
51-75
75 -99
10G
No data
SAMPLING STATION
Figure 3.1 Percent Detection Map for Propyzamide Based on the USGS NASQAN
Database (USGS 2006a)
3.2.4.3 USEPA STORET Data
The USEPA STORET database reports 2,194 analyses of propyzamide in surface waters
and wells found in Arizona, Florida, Indiana, Kentucky, Minnesota, Tennessee, and
Virginia. Only three detections are reported above detection limits (0.011—0.715 |ig/L),
originating from a surface water stream in Yuba County, Arizona in 2001 and 2002
(USEPA 2007c); there were no detections above the detection limits in California.
3.2.4.4 Other Monitoring Data
Propyzamide was detected in one Oklahoma reservoir out of twelve, which were
monitored in the Pilot Reservoir Monitoring Program due to their particular vulnerability
to pesticide contamination (USEPA 2002a). The compound was detected at up to 0.044
|ig/L in 83% of 41 raw water samples and up to 0.012 |ig/L in 42% of 19 finished water
samples.
PRONAMIDE (82676)
-61 -
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Propyzamide was not detected in 432 wells from 1984 to 1990, according to the EPA
Pesticides in Ground Water Database (USEPA 1992). Propyzamide is not a regulated
chemical under the Safe Water Drinking Act (SWDA) or related statutes. Therefore, it is
not listed in the EPA Safe Drinking Water Information System (SDWIS/FED) database
(USEPA 2007a) nor is it found in the EPA Unregulated Contaminants Monitoring Rules
(UCMR) chemical monitoring database (USEPA 2006b).
3.2.5 Spray Drift Buffer Analysis
In order to determine terrestrial and aquatic habitats of concern due to propyzamide
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
AGDISP (v8.15; 5/12/2005) and the Gaussian extension to AGDISP.
For the terrestrial-phase CRLF, this analysis was conducted using the most sensitive
terrestrial endpoint, i.e., vegetative vigor ECos for terrestrial monocots (ECo5=0.0001 lbs
a.i./acre). This endpoint was used to identify those locations where terrestrial and lentic
aquatic landscapes can be impacted by spray drift deposition alone (no runoff considered)
at concentrations above the listed species LOC for terrestrial plants (RQ>1.0).
NLCD land covers were used to represent the NASS use patterns of propyzamide labeled
for California. Table 3.6 lists the land covers used, which use patterns they include, and
the maximum application rate per land cover.
Table 3.6 NLCD Land Covers and Maximum Use Patterns for Propyzamide in the
State of California
GIS Land Cover
Use Pattern
Max App. Rate
Spray Method
Cultivated Crops
Artichokes, blueberries, alfalfa and
related crops, lettuce and leafy greens,
ornamental trees, plants, and shrubs
4.08 lbs a.i./A
Aerial
Orchards/vineyards
Stone fruit, pome fruit, grapes
4.08 lbs a.i./A
Ground
Turf
Turf, grass for seed
1.53 lbs a.i./A
Ground
Pasture
Fallow land
0.510 lbs a.i./A
Aerial
For propyzamide 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 for the Tier I ground
mode (no higher tier modeling for ground applications is available in AgDrift) and the
extent of the original AGDISP model. Subsequently, the AGDISP model and its
Gaussian extension for longer-range transport were used to evaluate potential distances
beyond which exposures would be expected to be below the LOC.
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The AGDISP model was run in ground mode and aerial mode with the following settings
listed in Table 3.7 beyond the standard default settings. Modeled release heights were
the highest allowed for each use pattern, which were assumed to be 4 feet and 15 feet for
ground and aerial applications, respectively. In the absence of a labeled maximum wind
speed, 15 mph was assumed. Modeled spray droplet size distributions and tank spray
volume rates were the finest and miminum, respectively, permitted on the label for each
use pattern (EPA Reg. No. 70506-78). Nonvolatile fractions of spray were calculated by
dividing the maximum application rate of product by the minimum spray volume rate.
Active fractions of spray were calculated by multiplying the active fraction of product by
the nonvolatile fraction of spray. No canopy was assumed. The bulk density of
propyzamide was reported in product chemistry submissions (MRID 46284603).
Because the ground mode has not been approved for use in risk assessment, the model
was run in both modes for ground applications to characterize buffer distance outputs.
Table 3.7 AGDISP Non-default
nput Parameters for Propyzamide
Land cover
App.
method
Release
height
(ft)
Wind
speed
(mph)
Droplet size
dist.
Tank spray
volume rate
(gal H20/A)
Nonvol.
fraction
Active
fraction
Canopy
Type
Bulk
Densitv
(kg/L)
Cultivated
Crops
Aerial
15
15
ASAE
coarse
10
0.1084
0.0614
None
0.796
Orchards/
vineyards
Ground
4
15
ASAE very
fine to fine
40
0.0271
0.0154
None
0.796
Turf
Ground
4
15
ASAE very
fine to fine
20
0.0203
0.0115
None
0.796
Pasture
Aerial
15
15
ASAE
coarse
10
0.0136
0.0077
None
0.796
When modeling ground applications, the aerial mode of AGDISP yielded shorter buffer
distances than the ground mode. Therefore, the outputs from the ground mode were
considered conservative for this analysis regardless of the uncertainty in their values. A
summary of the modeled spray drift buffer distances required for deposition levels below
the LOC for the maximum application rate per land cover is presented in Table 3.8.
Table 3.8 Spray Drift Buffer Distances per Land Cover for the Maximum Use
Patterns of Propyzamide in the State of California
Land Cover
Max App. Rate
Spray Method
Buffer Distance
Cultivated Crops
4.08 lbs a.i./A
Aerial
11,000 ft
Orchards/vineyards
4.08 lbs a.i./A
Ground
16,200 ft
Turf
1.53 lbs a.i./A
Ground
9,620 ft
Pasture
0.510 lbs a.i./A
Aerial
4,240 ft
The modeled buffer distances were added to their respective land covers to define the
action area (i.e., these buffer distances were added to the initial areas of concern depicted
in Figures 2.4-2.7),
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3.2.6 Downstream Dilution Analysis
The final step in defining the action area is 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 toxicity LOC. Using an assumption of uniform runoff
across the landscape, it is assumed that streams flowing through treated areas {i.e., the
initial area of concern) are represented by the modeled EECs; as those waters move
downstream, it is assumed that the influx of non-impacted water will dilute the
concentrations of propyzamide present, as the area of watershed upstream increases and
its percent crop area (PCA) likely decreases. The lowest LOC/RQ ratio (or inverse of the
highest RQ/LOC ratio) for any aquatic organism for which toxicity data are available is
used to represent the lowest percent crop area (PCA) of watershed upstream of water
bodies potentially of concern. In other words, stream reaches downstream of watershed
areas with PCA equal to or higher than the lowest LOC/RQ ratio are potentially of
concern and are included in and expand the action area. Stream reaches downstream of
watershed areas with PCA below the lowest LOC/RQ ratio are not of concern and are not
included in the action area.
No LOCs were exceeded for aquatic organisms using the exposure estimates for the
highest use patterns of propyzamide. Therefore, all LOC/RQ ratios were greater than one
{i.e., the target percent crop area (PCA) is >100%), which means that no waterbodies
downstream from the initial area of concern were included in the action area.
3.2 Terrestrial Animal Exposure Assessment
T-REX (Version 1.3.1) is used to calculate dietary and dose-based EECs of propyzamide
for the CRLF and its potential prey {e.g. small mammals and terrestrial insects)
inhabiting terrestrial areas. EECs used to represent the CRLF are also used to represent
exposure values for frogs serving as potential prey of CRLF adults. T-REX simulates a 1-
year time period. For this assessment, spray applications of propyzamide are considered,
as discussed in below.
Terrestrial EECs for foliar formulations of propyzamide were derived for the uses
summarized in Table 3.7. Given that no data on interception and subsequent dissipation
from foliar surfaces is available for propyzamide, 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 3.9. An example output from T-REX is available in Appendix E.
Unlike aquatic exposure estimates, terrestrial exposure is not based on total residues of
concern; however, the use of a 35-day foliar dissipation value is conservative and likely
accounts for degradates that may form.
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Table 3.9 Input Parameters for Foliar Applications Used to Derive Terrestrial
EECs for Propyzamide with T-REX
Use (Application method)
Application
rate
(lbs ai/A)
Number of
Applications
Reapplication Interval
(days)
Artichoke
4.08
2
120
Stone fruit, pome fruit, grapes
4.08
1
NA
Alfalfa, clover, trefoil, crown
fetch, sainfoin
2.0
2
98
Blueberries, ornamental trees,
plants and shrubs, Christmas
trees
2.04
1
NA
Lettuce
2.0
2
180
Turf grass
1.53
3
90
Fallow land
0.510
1
NA
NA—not applicable since only one application per year.
T-REX is also used to calculate EECs for terrestrial insects exposed to propyzamide.
Dietary-based EECs calculated by T-REX for small and large insects (units of a.i./g) are
used to bound an estimate of exposure to bees. Available acute contact toxicity data for
bees exposed to propyzamide (in units of |ig a.i./bee), are converted to |ig a.i./g (of bee)
by multiplying by 1 bee/0.128 g. The EECs are later compared to the adjusted acute
contact toxicity data for bees in order to derive RQs.
For modeling purposes, exposures of the CRLF to propyzamide 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 3.10). Dietary-based EECs for small and
large insects reported by T-REX as well as the resulting adjusted EECs are available in
Table 3.11. An example output from T-REX v. 1.3.1 is available in Appendix E.
-65 -
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Table 3.10 Upper-bound Kenega Nomogram EECs for Dietary- and Dose-based
Exposures of the CRLF and its Prey to propyzamide
Use
EECs for CRLF
EECs for Prcv
(small mammals)
Dietary-based
EEC (ppm)
Dosc-bascd EEC
(m«/k«-l)\v)
Dietary-based
EEC (ppm)
Dosc-bascd EEC
(mjj/kjj-bw)
Artichokes
602
686
1070
1,020
Stone fruit, pome fruit,
grapes
551
627
979
934
Alfalfa, clover, trefoil, crown
vetch, sainfoin
309
352
549
523
Blueberries, ornamental
trees, plants and shrubs,
Christmas trees
275
314
490
467
Lettuce
278
316
494
471
Turf
247
281
439
419
Fallow land
69
78
122
117
Table 3.11 EECs (ppm) for Indirect Effects to the Terrestrial-Phase CRLF via Effects
to Terrestrial Invertebrate Prey Items
Use
Small Insect
Larjjc Insect
Artichokes
602
67
Stone fruit, pome fruit, grapes
551
61
Alfalfa, clover, trefoil, crown vetch, sainfoin
309
34
Blueberries, ornamental trees, plants and shrubs, Christmas trees
275
31
Lettuce
278
31
Turf
247
27
Fallow land
69
7.7
3.3 Terrestrial Plant Exposure Assessment
TerrPlant (Version 1.1.2) is used to calculate EECs for non-target plant species inhabiting
dry and semi-aquatic areas. Parameter values for application rate, drift assumption and
incorporation depth are based upon the use and related application method (Table 3.12).
A runoff value of 2% is utilized based on propyzamide's solubility, which is classified by
TerrPlant as 15 mg/L. For aerial and ground application methods, drift is assumed to be
5% and 1%, respectively. EECs relevant to terrestrial plants consider pesticide
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concentrations in drift and in runoff. These EECs are listed by use in Table 3.12. An
example output from TerrPlant v. 1.2.2 is available in Appendix F.
Table 3.12 TerrPlant Inputs and Resulting EECs for Plants Inhabiting Dry and Semi-aquatic
Areas Exposed to propyzamide via Runoff and
Drift
Use
Application
rate
(lbs a.i./A)
Application
method
Drift
Value
(%)
Spray drift
EEC
(lbs a.i./A)
Dry area
EEC
(lbs a.i./A)
Semi-aquatic
area EEC
(lbs a.i./A)
Artichokes
4.08
Foliar - aerial
5%
0.204
0.29
1.02
Stone fruit, pome fruit,
grapes
4.08
Foliar - ground
1%
0.041
0.12
0.86
Alfalfa, clover, trefoil,
crown vetch, sainfoin,
2.0
Foliar - ground
1%
0.02
0.06
0.42
lettuce
Blueberries,
ornamental trees, plants
and shrubs, Christmas
2.04
Foliar - ground
1%
0.02
0.06
0.42
trees
Turf, grass for seed
1.53
Foliar - ground
1%
0.02
0.05
0.32
Fallow land
0.51
Foliar - aerial
5%
0.03
0.04
0.13
4. Effects Assessment
This assessment evaluates the potential for propyzamide 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 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, given that birds are generally
used as a surrogate for terrestrial-phase amphibians. Because the frog's prey items and
habitat requirements are dependent on the availability of freshwater fish and
invertebrates, small mammals, terrestrial 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 propyzamide.
As described in the Agency's Overview Document (USEPA 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
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Development (ORD) (U.S. EPA, 2004). Open literature data presented in this assessment
were obtained from the 1994 RED (USEPA 1994) and recently completed new use
evaluations (DP Barcode D329358) as well as ECOTOX information obtained on June
30, 2007. 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;
(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 is dependent on 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.
Citations of all open literature not considered as part of this assessment because they
were either rejected by the ECOTOX screen or accepted by ECOTOX but not used (e.g.,
the endpoint is less sensitive and/or not appropriate for use in this assessment) are
included in Appendix G. Appendix G also includes 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.
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 propyzamide. A summary of the available aquatic
and terrestrial ecotoxicity information, use of the probit dose response relationship, and
the incident information for propyzamide are provided in Sections 4.1 through 4.4,
respectively.
No data were available on the toxicity of the major degradates of propyzamide.
No toxicity data were available on propyzamide mixtures with other pesticides.
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4.1 Toxicity of Propyzamide to Aquatic Organisms
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
on the probit dose-response relationships for selected species is provided in Appendix A.
Table 4.1 Freshwater Aquatic Toxicity Profile for Propyzamide
Assessment Endpoint
Species
(Common Name)
Endpoint
Mean
Concentration
(mg/L)
Reference
(MRID)
Acute Direct Toxicity to
Aquatic-Phase CRLF
Oncorhyncus
mykiss
(Rainbow Trout)
96-hr LC50
72a
001079-96
Chronic Direct Toxicity
to Aquatic-Phase CRLF
Oncorhyncus
mykiss
(Rainbow Trout)
NOAEC
7.7b
Estimated
Indirect Toxicity to
Aquatic-Phase CRLF
via Acute Toxicity to
Freshwater
Invertebrates (i.e. prey
items)
Daphnia magna
48-hr EC50
>5.6
98313
(Waterflea)
Indirect Toxicity to
Aquatic-Phase CRLF
via Chronic Toxicity to
Freshwater
Invertebrates (i.e. prey
items)
Daphnia magna
NOAEC/LOAEC
0.60/1.2
436799-01
(Waterflea)
Indirect Toxicity to
Aquatic-Phase CRLF
via Acute Toxicity to
Non-vascular Aquatic
Plants
Anabaena flos-
aquae
(Blue-green algae)
5-day EC50
NOAEC
>4.0
0.39
437383-04
Indirect Toxicity to
Aquatic-Phase CRLF
via Acute Toxicity to
Vascular Aquatic Plants
Lemna gibba
(Duckweed)
14-day EC50
NOAEC
1.18
0.56
437383-01
Rainbow trout acute toxicity study conducted using formulated endproduct 75% a.i.
b
Freshwater invertebrate acute to chronic ratio (ACR=9.3) used to estimate fish chronic toxicity value since no chronic toxicity data
are available for fish.
Toxicity to aquatic fish and invertebrates is categorized using the system shown in Table
4.2 (U.S. EPA, 2004). Toxicity categories for aquatic plants have not been defined.
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Table 4.2 Categories of Acute Toxicity for Aquatic Organisms
LC5„ (ppm)
Toxicity Category
<0.1
Very highly toxic
>0.1-1
Highly toxic
>1-10
Moderately toxic
> 10 - 100
Slightly toxic
> 100
Practically nontoxic
4.1.1 Toxicity to Freshwater Fish
Given that no propyzamide 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 propyzamide to the CRLF. Effects to freshwater fish resulting from exposure to
propyzamide could 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
There are several reviewed studies that have evaluated the acute toxicity of propyzamide
to freshwater fish. Based on reported study results, 96-hr LC50s ranged from 72 mg/L for
rainbow trout, (Oncorhynchus mykiss) to 350 mg/L for goldfish (Carassius auratus)
(Table 8) There are several uncertainties, however, associated with the acute fish
studies and all were classified as supplemental. Notably, for all tests, nominal
concentrations were reported despite the solubility of propyzamide (15 mg/L; USEPA
1994) and formulated product was used instead of technical grade active ingredient. No
data are available for freshwater fish to determine the toxicity of technical grade active
ingredient relative to formulated product. Given the use of nominal concentrations
instead of measured and the reported low solubility of propyzamide, it is likely that actual
exposure concentrations were lower than the reported nominal concentrations; however,
it is not possible to guage the extent to which propyzamide was in solution without
measured concentrations. The toxicity categorization of propyzamide based on nominal
concentrations is slightly toxic to freshwater fish on an acute exposure basis.
4.1.1.2 Freshwater Fish: Chronic Exposure (Growth/Reproduction)
Studies
No studies on the chronic toxicity of propyzamide to freshwater fish were conducted due
to the apparent low acute toxicity. To estimate the chronic toxicity endpoint for fish, an
acute-to-chronic ratio of 9.3, derived for freshwater invertebrates and discussed below,
was used. The estimated NOAEC for fish is 7.7 mg/L and is less sensitive than the
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chronic toxicity endpoint for freshwater invertebrates (NOAEC=0.6 mg/L) discussed
below.
4.1.1.3 Freshwater Fish: Sublethal Effects and Additional Open
Literature Information
No data are available on either the acute or chronic sublethal toxicity of propyzamide to
freshwater fish.
4.1.1.4 Aquatic-phase Amphibian: Acute and Chronic Studies
No registrant-submitted nor ECOTOX data are available on either the acute or chronic
toxicity of propyzamide to aquatic-phase amphibians.
4.1.2 Toxicity to Freshwater Invertebrates
Freshwater aquatic invertebrate toxicity data were used to assess potential indirect effects
of propyzamide to the CRLF. Effects to freshwater invertebrates resulting from exposure
to propyzamide could 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.
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 Studies
There is one study on the acute toxicity of propyzamide to freshwater aquatic
invertebrates, i.e., waterfleas (Daphnia magna). The EC50 is greater than 5.6 mg/L, the
highest tested concentration tested, which categorizes propyzamide as moderately toxic
to freshwater invertebrates on an acute exposure basis. No daphnid mortality was
observed at the highest concentration tested; therefore, the acute NOAEC is 5.6 mg/L.
No additional data are available on sublethal effects to aquatic invertebrates.
4.1.2.2 Freshwater Invertebrates: Chronic Exposure Studies
Data from a flow-through life-cycle test with D. magna were reviewed. There were
effects of propyzamide on daphnid egg production (20% reduction at 2.4 mg/L) and
larval survival (28% reduction at 1.2 ppm). The NOAEC for the daphnid life-cycle test is
0.6 mg/L. This chronic toxicity endpoint for freshwater invertebrates was used to
develop an acute-to-chronic ratio for aquatic animals. The ratio of the acute NOAEC to
the chronic NOAEC is 5.6/0.6 or 9.3.
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4.1.2.3 Freshwater Invertebrates: Open Literature Data
No data are available in the open literature to characterize the toxicty of propyzamide to
freshwater invertebrates.
4.1.3 Toxicity to Aquatic Plants
Aquatic plant toxicity studies were used as one of the measures of effect to evaluate
whether propyzamide could 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.
Laboratory studies were used to determine whether propyzamide may cause direct
effects to aquatic plants. A summary of the laboratory data for aquatic plants is provided
in Section 4.1.3.1; no field/mesocosm data are available to evaluate the toxicity of
propyzamide to aquatic plants.
4.1.3.1 Aquatic Plants: Laboratory Data
Several studies on the toxicity of propyzamide to freshwater and marine aquatic plants
were submitted for review. A 14-day EC50 was estimated only for the aquatic vascular
plant, duckweed (Lemna gibba) and is 1.18 mg/L; the associated NOAEC is 0.56 mg/L.
For the other three non-vascular aquatic plant species, an EC50 could not be estimated
because effects did not exceed the 50% level; in all three cases, the EC50 is greater than
the highest tested concentration (4 mg/L). There were, however, estimated NOAECs
(0.39 mg/L) associated with the freshwater blue-green algae, Anabaena flos-aquae.
4.1.4 Freshwater Field/Mesocosm Studies
No freshwater field and/or mesocosm studies are available for propyzamide.
4.2 Toxicity of Propyzamide 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.
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Table 4.3 Terrestrial Toxicity Profile for Propyzamide
End point
Species
Endpoint
Mean Concentration
Reference (MRID)
Acute Direct
Toxicity to
Terrestrial-Phase
CRLF (LD5o)
Coturnex
japonica
Japanese Quail
24-hr LD5o
8870 mg/kg bwa
001079-97
Acute Direct
Toxicity to
Terrestrial-Phase
CRLF (LC5o)
Colinus
virginianus
Bobwhite
Quail
8-day LC50
>10,000 mg/kg diet
001080-03
Chronic Direct
Toxicity to
Terrestrial-Phase
CRLF
Estimated
based on
mammalian
ACR
NOAEC
267 ppm
20b mg/kg day
--
Indirect Toxicity to
Terrestrial-Phase
CRLF (via acute
toxicity to
mammalian prey
items)
Laboratory rat
96-hr LD5o
5620 mg/kg bw
000855-05
Indirect Toxicity to
Terrestrial-Phase
CRLF (via chronic
toxicity to
mammalian prey
items)
Laboratory rat
NOAEC/
LOAEC
200 ppm / 1500 ppm
15 mg/kg/day /114 mg/kg/day)
415403-01
Indirect Toxicity to
Terrestrial-Phase
CRLF (via acute
toxicity to
terrestrial
invertebrate prey
items)
Apis mellifera
Honey bee
48-hr LD5o
>181 (ig/bee
00028772
Indirect Toxicity to
Terrestrial- and
Aquatic-Phase
CRLF (via toxicity
to terrestrial plants)
Seedlins
Emersence
Monocots
14-day EC25 /
EC05
0.03/0.015 lbs a.i./A
421768-01
Seedlins
Emersence
Dicots
14-day EC25 /
EC05
0.015/0.004 lbs a..i./A
440290-01
Vesetative
Visor
Monocots
EC25/ECo5
0.088/0.0001 lbs a.i./A
421768-01
Vesetative
Visor
Dicots
EC25/ECo5
0.0104/0.0079 lbs a.i./A
421768-01
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Japanese quail acute oral toxicity study conducted with formulated endproduct 75% a.i.
b
chronic toxicity endpoint based on mammalian acute to chronic ratio of 436
Acute toxicity to terrestrial animals is categorized using the classification system shown
in Table 4.4 (U.S. EPA, 2004). Toxicity categories for terrestrial plants have not been
defined.
Table 4.4 Categories of Acute Toxicity for Avian and Mammalian Studies
Toxicity Category
Oral LD50
Dietary LC50
Very highly toxic
<10 mg/kg
< 50 ppm
Highly toxic
10-50 mg/kg
50 - 500 ppm
Moderately toxic
51 -500 mg/kg
501 - 1000 ppm
Slightly toxic
501 - 2000 mg/kg
1001 - 5000 ppm
Practically non-toxic
> 2000 mg/kg
> 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 propyzamide; therefore,
acute and chronic bird toxicity data are used to assess the potential direct effects of
propyzamide to terrestrial-phase CRLFs.
4.2.1.1 Birds: Acute Exposure (Mortality) Studies
Avian acute toxicity tests show that a formulated product of propyzamide (RH-315, 75%
ai) is practically nontoxic to birds on an acute oral exposure basis. The LD50 is 8770
mg/kg bw for Japanese quail (Coturnix japonica) and >14,000 mg/kg bw for mallard
ducks (Anas platyrhynchos). Although these supplemental studies provide some insight
into the acute toxicity of propyzamide to avian species, the studies deviated from
guidelines because; (1) formulated product was used instead of technical product, (2)
Japanese quail are not considered a suitable representative species for an upland game
bird, and (3) less than 10 birds per treatment were used. No acute sublethal effects were
reported.
In addition to the oral acute studies, four subacute dietary studies were submitted as well.
Three bobwhite and one mallard study showed that propyzamide (technical grade ai) is
practially nontoxic to avian species on a subacute dietary exposures basis with LC50
values ranging from >30 to >10000 mg/kg diet. Note that for the LC50 of >30 mg/kg diet,
this value represented the highest exposure level tested and subsequent studies in the
same species (Bobwhite quail) indicate that the LC50 is at least >4000 mg/kg diet and
likely exceeds 10,000 mg/kg diet. No sublethal subacute effects were reported.
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4.2.1.2 Birds: Chronic Exposure (Growth, Reproduction) Studies
There are no chronic toxicity data available on propyzamide from either registrant-
submitted studies or ECOTOX. Since there are no chronic toxicity data for birds, the
acute-to-chronic ratio (ACR=436) for mammals (discussed below) was used to estimate a
chronic toxicity value for birds. Based on an avian acute oral toxicity of 8870 mg/kg
bw, the estimated chronic toxicity endpoint for birds is 20 mg/kg (267 mg/kg diet).
4.2.1.3 Terrestrial-phase Amphibian Acute and Chronic Studies
There are no acute or chronic toxicity data for terrestrial-phase amphibians available from
either registrant-submitted studies or ECOTOX.
4.2.2 Toxicity to Mammals
Mammalian toxicity data are used to assess potential indirect effects of propyzamide to
the terrestrial-phase CRLF. Effects to small mammals resulting from exposure to
propyzamide could also 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).
4.2.2.1 Mammals: Acute Exposure (Mortality) Studies
The acute oral LD50 for rats dosed with propyzamide is 8350 mg/kg bw for males and
5620 mg/kg bw for females, which classifies propyzamide as practically non-toxic to
mammals on an acute oral exposure basis.
4.2.2.2 Mammals: Chronic Exposure (Growth, Reproduction) Studies
A 2-generation reproduction study in rats showed that propyzamide caused effects on
adult and offspring body size at the highest exposure level of 1500 ppm (114 mg/kg bw
males, 127.3 mg/kg bw females), which is the LOAEC. There was a 7-13% reduction in
male body weights and a 12-18% reduction in female body weights for rats exposed to
1500 ppm. The NOAEC is the next lowest exposure level of 200 ppm (15.4 mg/kg bw
males, 16.5 mg/kg bw females) where no adverse effects were observed. The large
difference in the LOAEC and the NOAEC is due to the chosen experimental design. In
all likelihood, the NOAEC, or the threshold where effects may become ecologically
relevant, is higher than 200 ppm. For the purposes of this screening-level assessment,
however, 200 ppm is used to estimate chronic risks to mammals.
An acute-to-chronic ratio (ACR) was determined for mammals using the mean (average
of male and female) acute oral LD50 (6985 mg/kg bw) and the mean (average of male and
female) chronic NOAEC (16 mg/kg/day) yielding an ACR of 437.
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4.2.3 Toxicity to Terrestrial Invertebrates
Terrestrial invertebrate toxicity data are used to assess potential indirect effects of
propyzamide to the terrestrial-phase CRLF. Effects to terrestrial invertebrates resulting
from exposure to propyzamide could also indirectly affect the CRLF via reduction in
available food.
4.2.3.1 Terrestrial Invertebrates: Acute Exposure (Mortality) Studies
Propyzamide is characterized as practically nontoxic to terrestrial insects (honeybee acute
contact LD5o=181 (j,g/bee); mortality in the highest dose (181 (j,g/bee) was 4.9%. For the
purposes of this assessment, the honeybee endpoint is used to derive RQs. This toxicity
value is converted to units of ^ig a.i./g (of bee) by multiplying by 1 bee/0.128 g thereby
resulting in an LD50 = 1414 jag a.i./g.
4.2.3.2 Terrestrial Invertebrates: Open Literature Studies
There are no data on the toxicity of propyzamide to terrestrial invertebrates in the open
literature available through ECOTOX.
4.2.4 Toxicity to Terrestrial Plants
Terrestrial plant toxicity data are used to evaluate the potential for propyzamide 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 of
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 were 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. A drawback to
these tests is that they 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 propyzamide, 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.
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The effects of propyzamide on terrestrial monocotyledonous and dicotyledonous plants
were tested in Tier II seedling emergence and vegetative vigor tests. Results of the Tier
II seedling emergence study identify cucumber as the most sensitive dicot with an EC25
and NOAEC of 0.015 and 0.004 lb ai/A, respectively, based on a decrease in shoot length
compared to the control (MRID 440290-01). The most sensitive monocot, based on
seedling emergence, is ryegrass with an EC25 of 0.03 lb ai/A and a NOAEC of 0.015 lb
ai/A, based on a decrease in percent emergence.
Results of the Tier II vegetative vigor studies identify oat as the most sensitive monocot
and tomato as the most sensitive dicot, with decreased shoot weight and root weight,
respectively, as the most sensitive endpoints. The EC0s and EC25 values of 0.0001 lbs
a.i./A and 0.088 lbs a.i./A, respectively, for oat, and the EC05 and EC25 values of 0.0079
lbs a.i./A and 0.0104 lbs a.i./A, respectively, for tomato, are used to assess the effects of
exposure to propyzamide on vegetative vigor in non-listed and listed terrestrial plants.
No data more sensitive than those discussed above from registrant-submitted guideline
studies were available through the open literature.
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 propyzamide 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. Dose response slopes used in determing the acute 96-hr LC50
for rainbow trout and the acute oral LD50 for Japanes quail are 2.55 and 8.18,
respectively. An example of the IECV model output is in Appendix I.
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4.4 Incident Database Review
A review of the Ecological Incident Information System (EIIS) database for ecological
incidents involving propyzamide was completed on December 3, 2007. 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 propyzamide
including associated uncertainties is included as Appendix H.
4.4.1 Terrestrial Incidents
No incidents have been reported involving terrestrial animals from the use of
propyzamide.
4.4.2 Plant Incidents
A total of three incidents involving terrestrial plants are reported in the EIIS database
over the period of 2001 through 2004. Two incidents (1014702-047 and 1012525-008)
occurred from the registered use of propyzamide on lettuce (Lactuca sativa) in California
and Arizona. The third incident (IO 16962-004) resulted from the registered use of
propyzamide on broccoli (Brassica oleracea) in Japan.
4.4.3 Aquatic Incidents
No incidents involving aquatic animals have been reported for the use of propyzamide.
5. 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
propyzamide 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 LOC
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is 0.05. For acute exposures to the CRLF and mammals, the LOC is 0.1. The LOC for
chronic exposures to CRLF and its prey, as well as acute exposures to plants is 1.0.
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 labeled propyzamide 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 propyzamide (Tables 3.5 through 3.6) and the appropriate toxicity endpoint from
Table 4.3. Exposures are also derived for terrestrial plants, as discussed in Section 3.3
and summarized in Table 3.7, based on the highest application rates of propyzamide 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, i.e., LC50 of 72 mg/L or 72,000
[j,g/L. In order to assess direct chronic risks to the CRLF, 60-day EECs and the lowest
chronic toxicity value for freshwater fish are used. Since chronic toxicity data are not
available for freshwater fish, the freshwater invertebrate acute-to-chronic ratio
(ACR=9.3) was used to estimate a chronic toxicity value. Based on the highest estimated
acute exposure value and the most sensitive toxicity endpoint the acute endangered
species LOC is not exceeded; therefore, the determination is for a "no effect" based on
potential direct acute effects to aquatic-phase CRLF. Although there is uncertainty
regarding the use of a nominal toxicity endpoint based on formulated endproduct when
that value exceeds the solubility limit of propyzamide (15 mg/L), even if the RQ had
been based on the solubility limit, the RQ value (RQ=0.02) would still not exceed the
acute LOC.
Based on the highest 60-day chronic exposure value and the estimated chronic toxicity
value for freshwater fish (NOAEC=7,700 (J,g/L), the risk quotient is below the chronic
risk LOC. Based on the estimated exposure values presented in Table 3.4, none of the
propyzamide uses evaluated exceed the chronic risk LOC. The determination is a "no
effect" based on potential direct chronic effects to aquatic-phase CRLF.
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Table 5.1 Summary of t
>irect Effect RQs for the Aquatic-phase CRLF
Direct Effects
to CRLF'1
Surrogate
Species
Toxicity
Value
(Hg/L)
EEC
(Hg/L)b
RQ
Probability of
Individual
Effect'
LOC
Excccdancc
and Risk
Interpretation
Acute Direct
Toxicity
Trout
lc50 =
72,000
Peak:225
0.003
1 in 1.6 X1010
Nod
Chronic Direct
Toxicity
7,700e
60-day: 211
0.03
NA
No
a RQs associated with acute and chronic 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 foliar use of propyzamide on lettuce at 4.00 lbs a.i./A (see Table 3.4).
0 A probit slope value for the acute fathead minnow 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).
d RQ < acute endangered species LOC of 0.05.
e Chronic toxicity endpoint estimated using the mammalian acute to chronic ratio.
5.1.1.2 Indirect Effects to Aquatic-Phase CRLF via Reduction in Prey
(non-vascular aquatic plants, aquatic invertebrates, fish, and frogs)
Non-vascular Aquatic Plants
Indirect effects of propyzamide 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 most sensitive
nonvascular aquatic plant toxicity estimate is for blue-green algae with an EC5o>4,000
[j,g/L. At the peak estimated environmental concentration of 225 |ig/L, the acute RQ is
well below the LOC. Even if the NOAEC for blue-green algae (390 (J,g/L) is used to
calculate the RQ, the RQ (0.57) is below the LOC. The determination is "no effect" for
indirect effects to aquatic-phase CRLF through reductions in non-vascular plant food
items.
Table 5.2 Summary of Acute 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)
Uses
Application rate (lb
ai/A) and type
Peak EEC
Gig/L)
Indirect effects RQ*
(food and habitat)
Lettuce
4.0
225a
<0.056
a Highest estimated environmental concentration based on propyzamide use on lettuce.
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 (EC5o>5600 (J,g/L) for freshwater invertebrates. For chronic risks, 21-day
EECs and the lowest chronic toxicity value for invertebrates (NOAEC=600 (J,g/L) are
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used to derive RQs. 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.
Based on the highest estimated environmental concentrations, neither acute nor chronic
risk LOCs are exceeded. Therefore, the determination is for a "no effect" for indirect
effect to aquatic-phase CRLF for effects to prey in aquatic habitats.
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)
Uses
Application rate
(lb ai/A) and
type
Peak EEC
Oig/L)
21-dav
EEC
(Hg/L)
Indirect
Effects
Acute RQ"
Indirect
Effects
Chronic RQb
Lettuce
4.0
225
220
<0.04
0.37
a Acute RQ value based on most sensitive freshwater invertebrate (Daphnia magna EC50>5,600 (ig/L.
b Chronic RQ value based on most sensitive freshwater invertebrat (I). magna NOAEC=600 |ig/L)
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. Since at the highest estimated environmental concentration, acute
and chronic RQ values are below the acute and chronic risk LOCs, the determination is
"no effect" on fish and frogs.
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. As discussed in
Section 5.1.1.2, RQ values for aquatic nonvascular plants do not exceed the LOC. The
most sensitive vascular aquatic plant toxicity estimate is for duckweed with an EC50 of
1,180 (J,g/L. At the peak estimated environmental concentration of 225 |ig/L, the acute
RQ is well below the LOC. Therefore, the determination is "no effect" for indirect
effects to CRLF via reduction in habitat and/or primary productivity through adverse
effects on freshwater [aquatic] vascular and nonvascular plants.
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Table 5.4 Summary of Acute RQs Used to Estimate Indirect Effects to the CRLF via
Effects to Vascular Aquatic Plants (habitat of aquatic-phase CRLF)"
Uses
Application rate (lb
ai/A) and type
Peak EEC
(Hg/L)
Indirect effects RQ*
(food and habitat)
Lettuce
4.0
225a
0.19
a highest estimated environmental concentration based on propyzamide use on lettuce.
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 applications of propyzamide.
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 3.10) and acute oral and subacute dietary toxicity endpoints
for avian species. Results are presented in Table 5.5 and indicate that at the current
maximum application rates for propyzamide on artichokes and orchard/vineyard crops,
the acute dose-based RQ exceeds the acute risk to endangered species LOC (RQ>0.1).
The determination is for a "may affect" for direct acute effects to the terrestrial-phase
CRLF.
Table 5.5 Acute and chronic, dietary-based RQs and dose-based RQs
for direct effects to the terrestrial-phase CRLF. RQs calculated using T-
REX.
Crop Group1
Acute
Dose-
Based RQ2
Dietary -
Based, acute
RQJ
Dietary-based, chronic RQ""'
Artichokes
0.114
0.06
2.36
Stone fruit, pome fruit, grapes
0.104
0.06
2.16
Alfalfa, clover, trefoil, crown
vetch, sainfoin
0.06
0.03
1.26
Blueberries, ornamental trees,
plants and shrubs, Christmas
trees
0.05
0.03
1.06
Lettuce
0.05
0.03
1.06
Turf
0.04
0.02
0.93
Fallow land
0.01
0.01
0.26
'For specific uses associated with each crop group see Table 5.
2Based on LD50 8870 ppm (for Japanese quail)
3 Based on LC50 >10,000 ppm (for Bobwhite quail)
4Exceeds acute listed species LOC (RQ>0.1)
5Based on estimated NOAEC = 20 ppm (for Bobwhite quail)
6Exceeds chronic listed species LOC (RQ>1.0)
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Potential direct chronic effects of propyzamide 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. Using the estimated avian NOAEC (based on the acute-to-chronic ratio
derived for mammals), dietary-based RQ values for all of the current modeled uses
exceed the chronic risk LOC (RQ>1.0) (Table 5.5).
Estimates of potential direct effects on the terrestrial-phase CRLF were further refined
using the T-HERPS spreadsheet. Based on this refinement no acute (dose-based or
dietary-based) RQ (RQ<0.06) exceeds the acute risk to listed species LOC for direct
effects on terrestrial-phase CRLF foraging on small insects. However, the chronic risk
LOC is still exceeded (RQ range 1 - 2.3) for all uses except turf and fallow land.
5.1.2.2 Indirect Effects to Terrestrial-Phase CRLF via Reduction in
Prey (terrestrial invertebrates, mammals, and frogs)
5.1.2.2.1 Terrestrial Invertebrates
In order to assess the risks of propyzamide 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 LD50 of >181 |ig a.i./bee by 1 bee/0.128g,
which is based on the weight of an adult honey bee. EECs calculated by T-REX for small
and large insects (see Table 3.11) are divided by the calculated toxicity value for
terrestrial invertebrates, which is >1,414 |ig a.i./g of bee. All of the modeled uses, at the
maximum application rate, exceed the acute risk to endangered species LOC (RQ>0.05),
based on small insect forage items except at the maximum application rate used on fallow
ground. None of the RQ vales for large insect forage items exceed the acute risk LOC.
The determination is "may affect" for indirect effects to terrestrial-phase CRLF via direct
effects on small insects as dietary food items.
Table 5.6 Summary of RQs Used to Estimate Indirect Effects to the Terrestrial-
phase CRLF via Direct Effects on Terrestrial Invertebrates as Dietary Food
Items
Use
Small Insect RQ*
Large Insect RQ*
Artichokes
0.43
0.04
Stone fruit, pome fruit, grapes
0.39
0.04
Alfalfa, clover, trefoil, crown vetch,
sainfoin
0.22
0.02
Blueberries, ornamental trees, plants and
shrubs, Christmas trees
0.19
0.02
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Lettuce
0.20
0.02
Turf
0.17
0.02
Fallow land
0.04
0.01
* = LOC exceedances (RQ > 0.05) are bolded and shaded.
5.1.2.2.2 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. EECs (Table 3.11) are divided by the toxicity
value to estimate acute and chronic dose-based RQs as well as chronic dietary-based
RQs. None of the modelded uses exceed the acute LOC while both dose-based and
dietary-based chronic RQ values exceed the chronic risk LOC except for the dietary-
based chronic RQ value for use of propyzamide on fallow land.
Table 5.7 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.
Use
(Application Rate)
Chronic RQ
Acute RQ
Dosc-bascd Chronic RQ1
Dietary-based
Chronic RQ2
Dosc-bascd Acute RQ3
Artichokes
31
5.4
0.08
Stone fruit, pome fruit, grapes
28
4.9
0.08
Alfalfa, clover, trefoil, crown
vetch, sainfoin
16
2.7
0.04
Blueberries, ornamental trees,
plants and shrubs, Christmas
trees
14
2.5
0.04
Lettuce
14
2.5
0.04
Turf
13
2.2
0.03
Fallow land
3.5
0.61
0.01
* = LOC exceedances (acute RQ >0.1 and chronic RQ > 1) are bolded and shaded.
1 Based on dose-based EEC and propyzamide rat NOAEL = 200 mg/kg-bw.
2 Based on dietary-based EEC and propyzamide rat NOAEC = 15 mg/kg-diet.
3 Based on dose-based EEC and propyzamide rat acute oral LD50 = 5,620 mg/kg-bw.
Risk estimates for potential indirect effects to terrestrial-phase CRLF via direct effects on
small mammals serving as prey were further refined using T-HERPS; however, the
chronic risk LOC was still exceeded. Dietary-based chronic RQ values for small
insectivorous mammals ranged from 0.61 to 5.4 and exceed the chronic risk LOC for all
uses except fallow land. Dietary-based chronic risk quotients for small herbivorous
mammals ranged from 3.5 to 31 across all of the uses evaluated. Based on these results
the determination is "may affect" based on indirect effects to terrestrial-phase CRLF from
chronic effects on small mammals serving as prey.
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5.1.2.2.3
Frogs
An additional prey item of the adult terrestrial-phase CRLF is other frogs. In order to
assess risks to these organisms, dietary-based and dose-based exposures modeled in T-
REX for a small bird (20g) consuming small invertebrates are used. As indicated by RQ
values for direct effects to terrestrial-phase frogs (Table 5.5), at current maximum
application rates, acute dose-based RQ values exceed the acute risk to endangered species
LOC (RQ>0.1) at rates equivalent to those used on artichokes and stone fruits.
Additionally, dietary-based chronic RQ values exceed the chronic risk LOC across all
uses except turf and fallow land.
Risk estimates for small amphibians were further refined using T-HERPS. Based on this
refinement, all of acute RQ values dropped below the acute risk LOC. The chronic risk
LOC was only exceeded for the use of propyzamide on artichokes (RQ=1.04). The
determination is a "may affect" for direct chronic effects on terrestrial-phase frogs.
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 semi-aquatic,
riparian and upland vegetation, i.e., primary constituent elements of CRLF habitat, are
assessed using RQs from terrestrial plant seedling emergence and vegetative vigor EC25
data as a screen. Based on RQ values, the LOC (RQ>1) is exceeded for terrestrial
monocotyledonous plants inhabiting semi-aquatic and dry areas for all of the uses
evaluated. For use of propyzamide on artichokes and orchard crops/vineyards at the
highest maximum application rate of 4.08 lbs a.i./A alone, RQ values for spray drift
exceed the LOC (Table 5.8). For terrestrial dicotyledonous plants inhabiting semi-
aquatic and dry areas and for spray drift, RQ values exceed the LOC across all of the uses
evaluated (Table 5.9). Example output from TerrPlant v. 1.2.2 is provided in Appendix
F. Based on these results, the determination is "may affect" for indirect effects to the
terrestrial and aquatic-phase CRLF via reductions in terrestrial plant communities.
Table 5.8 RQs* for Monocots Inhabiting Dry and Semi-Aquatic Areas Exposed to Propyzamide
via Runoff and Drift
Use
Application
rate
(lbs a.i./A)
Application
method
Drift
Value
(%)
Sprav drift
RQ
Drv area
RQ
Semi-aquatic
area RQ
Artichokes
4.08
Foliar - aerial
5
6.8
9.5
34
Stone fruit, pome fruit,
grapes
4.08
Foliar - ground
1
1.4
4.1
29
Alfalfa, clover, trefoil,
crown vetch, sainfoin,
lettuce
2.0
Foliar - ground
1
0.67
2.0
14
Blueberries,
2.04
Foliar - ground
1
0.68
2.0
14
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ornamental trees, plants
and shrubs, Christmas
trees
Turf
1.53
Foliar - ground
1
0.51
1.5
11
Fallow land
0.51
Foliar - aerial
5
0.85
1.2
4.3
* = LOC exceedances (RQ > 1) are bolded and shaded.
Table 5.9 RQs* for Dicots Inhabiting Dry and Semi-Aquatic Areas Exposed to Propyzamide via
Runoff and Drift
Use
Application
rate
(lbs a.i./A)
Application
method
Drift
Value
(%)
Sprav drift
RQ
Drv area
RQ
Semi-aquatic
area RQ
Artichokes
4.08
Foliar - aerial
5
20
19
68
Stone fruit, pome fruit,
grapes
4.08
Foliar - ground
1
3.9
8.2
57
Alfalfa, clover, trefoil,
crown vetch, sainfoin,
lettuce
2.0
Foliar - ground
1
1.9
4.0
28
Blueberries,
ornamental trees, plants
and shrubs, Christmas
trees
2.04
Foliar - ground
1
2.0
4.1
29
Turf
1.53
Foliar - ground
1
1.5
3.1
21
Fallow land
0.51
Foliar - aerial
5
2.5
2.4
8.5
* = LOC exceedances (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.
• Reduction and/or modification of aquatic-based food sources for pre-metamorphs
(e.g., algae).
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The preliminary effects determination for aquatic-phase PCEs of designated habitat
related to potential effects on aquatic is "no effect", however, effects on designated
habitat due to potential effects on terrestrial plants is a "may affect", based on the risk
estimation provided in Sections 5.1.1.2, 5.1.1.3, and 5.1.2.3.
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 propyzamide on this PCE, 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. Neither acute nor chronic risk LOC is exceeded for aquatic nonvascular
plants and/or animals; therefore, the determination is that use will not modify aquatic-
phase PCEs.
5.1.3.2 Terrestrial-Phase (Upland Habitat and Dispersal Habitat)
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 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
The preliminary effects determination for terrestrial-phase PCEs of designated habitat
related to potential effects on terrestrial plants is habitat modification, based on the risk
estimation provided in Section 5.1.2.3.
The third terrestrial-phase PCE is "reduction and/or modification of food sources for
terrestrial-phase juveniles and adults." To assess the impact of propyzamide 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.
The habitat modification determination of the terrestial-phase PCE is based on
modifications of food items.
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. As discussed previously, the acute risk LOC is exceeded for terrestrial-
phase amphibians at the maximum application rates for artichokes and orchard/vineyard
crops. The acute risk LOC is exceeded for terrestrial invertebrates. Additionally, the
chronic risk LOC is exceeded across all uses evaluated for terrestrial-phase amphibians
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and for mammalian food items. Based on these exceedances, the determination is habitat
modification based on alteration of chemical characteristics necessary for normal growth
and vaiability of juvenile and adult CRLF and their food source.
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 whether designated
critical habitat may be adversely modified.
If the RQs presented in the Risk Estimation (Section 5.1) show no direct or indirect
effects for the CRLF, and no modification to PCEs of the CRLF's designated critical
habitat, a "no effect" determination is made, based on the use of propyzamide within the
action area. However, if direct or indirect effect LOCs are exceeded or 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 propyzamide. A
summary of the results of the risk estimation (i.e., "no effect" or "may affect" finding) is
provided in Table 5.10 for direct and indirect effects to the CRLF and in Table 5.11 for
the PCEs of designated critical habitat for the CRLF.
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Table 5.10 Preliminary Effects Determination Summary for propyzamide - Direct and Indirect
Effects to CRLF
Assessment Endpoint
Preliminary
Effects
Determination
Basis For Preliminary Determination
Aquatic-Phase
(eggs, larvae, tadpoles, juveniles, and adults)
Survival, growth, and reproduction
of CRLF individuals via direct
effects on aquatic phases
no effect
RQ values for aquatic-phase CRLF are below the acute and
chronic risk LOCs
Survival, growth, and reproduction
of CRLF individuals via effects to
food supply (i.e., freshwater
invertebrates, non-vascular plants)
no effect
RQ values for aquatic invertebrates and aquatic plants are
below the LOC
Survival, growth, and reproduction
of CRLF individuals via indirect
effects on habitat, cover, and/or
primary productivity (i.e., aquatic
plant community)
no effect
RQ values for aquatic plants (vascular and nonvascular) are
below the LOC
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.
may affect
RQ values for terrestrial plants in riparian habitat exceed the
LOC.
Terrestria- Phase
(Juveniles and adults)
Survival, growth, and reproduction
of CRLF individuals via direct
effects on terrestrial phase adults and
juveniles
may affect
RQ values exceed the acute risk LOC for terrestrial-phase
CRLF at the highest maximum application rates for artichokes
and orchard/vineyard uses.
RQ values exceed the chronic risk LOC for terrestrial-phase
CRLF across all of the uses evaluated.
Survival, growth, and reproduction
of CRLF individuals via effects on
prey (i.e., terrestrial invertebrates,
small terrestrial mammals and
terrestrial phase amphibians)
may affect
RQ values exceed LOC for small insect forage items; chronic
risk LOC exceeded for mammalian prey items; acute and
chronic RQ values exceed for terrestrial amphibians serving as
food for terrestrial-phase CRLF.
Survival, growth, and reproduction
of CRLF individuals via indirect
effects on habitat (i.e., riparian
vegetation)
may affect
RQ values exceed LOC for terrestrial plants in terrestrial-phase
CRLF habitat.
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Table 5.11 Preliminary Effects Determination Summary for propyzamide - PCEs of Designated
Critical Habitat for the CRLF
Assessment Endpoint
Preliminary Effects
Determination
Basis For Preliminary Determination
Aquatic-Phase CRLF PCEs
(Aquatic Breeding Habitat and Aquatic Non-Breeding Habitat)
Alteration of channel/pond morphology or
geometry and/or increase in sediment
deposition within the stream channel or
pond: aquatic habitat (including riparian
vegetation) provides for shelter, foraging,
predator avoidance, and aquatic dispersal
for juvenile and adult CRLFs.
may affect
Terrestrial plant (riparian vegetation) RQ values
exceed the LOC.
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.
may affect
Terrestrial plant (riparian vegetation) RQ values
exceed the LOC.
Alteration of other chemical characteristics
necessary for normal growth and viability of
CRLFs and their food source.
may affect
Terrestrial plant (riparian vegetation) RQ values
exceed the LOC.
Reduction and/or modification of aquatic-
based food sources for pre-metamorphs
(e.g., algae)
no effect
Aquatic non-vascular plant RQ values are below the
LOC.
Terrestrial-Phase CRLF PCEs
(Upland Habitat and Dispersal Habitat)
Elimination and/or disturbance of upland
habitat; ability of habitat to support food
source of CRLFs: Upland areas within 200
ft of the edge of the riparian vegetation or
dripline surrounding aquatic and riparian
habitat that are comprised of grasslands,
woodlands, and/or wetland/riparian plant
species that provides the CRLF shelter,
forage, and predator avoidance
habitat
modification
Terrestrial plant (riparian vegetation) RQ values
exceed the LOC.
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
habitat
modification
Terrestrial plant (riparian vegetation) RQ values
exceed the LOC.
Reduction and/or modification of food
sources for terrestrial-phase juveniles and
adults
habitat
modification
Terrestrial plant (riparian vegetation) RQ values
exceed the LOC. RQ values exceed chronic risk
LOC for terrestrial insects, mammals and small
amphibian serving as prey for terrestrial-phase
CRLF.
Alteration of chemical characteristics
necessary for normal growth and viability of
habitat
modification
Terrestrial plant (riparian vegetation) RQ values
exceed the LOC.
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Table 5.11 Preliminary Effects Determination Summary for propyzamide - PCEs of Designated
Critical Habitat for the CRLF
Assessment Endpoint
Preliminary Effects
Determination
Basis For Preliminary Determination
juvenile and adult CRLFs and their food
source.
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 or modify 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,
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 propyzamide. As discussed previously, with a dose-response slope
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of 2.55 and at the highest acute RQ value (lettuce RQ=0.003) for freshwater fish, i.e, the
surrogate for aquatic-phase amphibians, the likelihood of an individual effect is 1 in 1.6 x
1010. This low likelihood individual acute mortality further supports the no effect
determination for aquatic-phase amphibians based on acute effects.
Chronic RQs discussed in Section 5.1.1.1 and Table 5.1 indicate that across all of the
uses evaluated, the chronic risk LOC is not exceeded. The highest chronic RQ value
(RQ=0.03) is well below the chronic risk LOC. However, there is considerable
uncertainty regarding the chronic toxicity of propyzamide to aquatic vertebrates because
no chronic toxicity data are available to assess risk. Rather, the freshwater invertebrate
acute-to-chronic ratio was used to estimate a chronic toxicity value for fish. The
resulting estimate (NOAEC=7.7 mg/L) is roughly an order of magnitude less sensitive
than the measured NOAEC for aquatic invertebrates (NOAEC=0.6 mg/L). Although
propyzaimde is used as a herbicide and aquatic animals are not expected to be
particularly sensitive, the mode of action of propyzamide is uncertain. The hypothesized
mode of action, i.e., inhibition of spindle fiber formation during mitosis, involves a
process that is common to both plants and animals and as such, the effects of
propyzamide may not be limited to plants alone.
The estimated NOAEC for aquatic-phase amphibians also depends on the acute toxicity
of propyzamide to fish; however, the most sensitive acute toxicity value (rainbow trout
LC50= 72 mg/L) was used in the assessment. The rainbow trout acute toxicity estimate is
roughly 50% more sensitive that the next most sensitive species, i.e., guppy LC5o=l50
mg/L and roughly 5 times more sensitive than the third most sensitive species, i.e.,
goldfish LC5o=350 mg/L. If the chronic toxicity value for freshwater fish had been
estimated using the mean of the three lowest toxicity values, i.e., 190 mg/L, the estimated
NOAEC would be 20 mg/L and would be more 30 times less sensitive than what was
measured for chronic toxicity to freshwater invertebrates.
5.2.1.2 Terrestrial-Phase CRLF
RQ values exceed the acute risk LOC for terrestrial-phase amphibians for use of
propyzamide at the highest maximum application rate for use on artichokes and
orchard/vineyard crops. However, a more refined assessment using T-HERPS indicates a
"not likely to adversely affect" determination since RQ values are below the acute risk
LOC for all of the uses evaluated.
Initially, chronic RQ values exceeded the chronic risk LOC for all of the uses evaluated.
A refined assessment using T-HERPS indicates that all but propyzamide use on fallow
land exceeds the chronic risk LOC. As was the case for evaluating potential chronic risk
to aquatic-phase CRLF, no chronic toxicity data are available with which to evaluate
chronic risk to the terrestrial-phase CRLF. Again, the chronic toxicity endpoint had to be
estimated using the acute-to-chronic ratio developed using mammalian toxicity data. The
estimated NOAEC (20 mg/kg/day) is based on the acute 24-hr LD50 (8870 mg/kg bw) for
Japanese quail; however, there are no other definitive acute or subacute dietary toxicity
studies available. Therefore, the degree of conservatism in the estimated chronic toxicity
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value is uncertain. Because of this uncertainty, the chronic toxicity estimate cannot be
further refined and the determination is likely to adversely affect (LAA) the terrestrial-
phase CRLF through direct chronic effects.
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. None of the uses assessed
exceed the LOC for nonvascular plants, therefore, the determination is "no effect" for
indirect effects to aquatic-phase CRLF based in reductions in algae/diatoms serving as
food.
5.2.2.2 Aquatic Invertebrates
The potential for propyzamide 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.
As discussed in Section 5.1.1.2 (Table 5.3), acute RQs < 0.05 and are below the LOC;
therefore, the determination is "no effect" for indirect effects to aquatic-phase CRLF due
to reductions in aquatic invertebrates serving as food.
5.2.2.3 Fish and Aquatic-phase Frogs
Similar to the direct effects discussion for aquatic-phase CRLFs, the potential indirect
acute effects to aquatic-phase CRLF from reductions in fish and other frogs serving as
prey is determined to be a "no effect".
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5.2.2.4 Terrestrial Invertebrates
When the terrestrial-phase CRLF reaches juvenile and adult stages, its diet is mainly
composed of terrestrial invertebrates. As discussed in Section 5.1.2.2.1, all of the
modeled uses, with the exception of fallow land, exceed the acute risk to endangered
species LOC (RQ>0.05), based on small insect forage items. However, there is
considerable uncertainty regarding the toxicity of propyzamide to terrestrial
invertebrates; the available data indicate that the 48-hr LD50 exceeded the highest
concentration tested (LD50>181 (j,g/bee). It is uncertain how much higher the
concentration would have to be to result in bee mortality though. Based on a default
dose-response slope of 4.5 and at the highest RQ values (RQ=0.43), terrestrial insects
serving as prey would have a likelihood of individual mortality of 1 in 20. Based on this
relatively low likelihood of mortality and the fact that the LD50 value exceeded the
highest concentration tested, the potential effect is considered insignificant and the
determination is not likely to adversely affect (NLAA).
5.2.2.5 Mammals
Life history data for terrestrial-phase CRLFs indicate that large adult frogs consume
terrestrial vertebrates, including mice. Based on the assessed uses or propyzamide, none
of the RQ values exceed the acute risk LOC while both dose-based and dietary-based
chronic RQ values exceed the chronic risk LOC. There is uncertainty though in the wide
difference between the observed NOAEC (200 ppm) and LOAEC (1500 ppm) for the
chronic rat reproduction study. It is likely that the NOAEC is higher than reported;
however, the extent to which it is higher is uncertain. No additional information is
available to refine these initial chronic risk estimates; therefore, the determination is
likely to adversely affect (LAA) terrestrial-phase CRLF based on indirect adverse chronic
effects on mammals serving as food for terrestrial-phase CRLF.
5.2.2.6 Terrestrial-phase Amphibians
Terrestrial-phase adult CRLFs also consume frogs. RQ values representing direct
exposures of propyzamide to terrestrial-phase CRLFs are used to represent exposures of
propyzamide to frogs in terrestrial habitats. As discussed previously, there is uncertainty
regarding the chronic toxicity endpoint used to assess direct chronic risk to terrestrial-
phase CRLF. This same uncertainty would apply to other terrestrial-phase amphibians
and therefore, the determination is likely to adversely affect (LAA) terrestrial-phase
CRLF through indirect chronic effects on other terrestrial-phase frogs serving as prey.
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, rather than energy, to the system,
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as attachment sites for many aquatic invertebrates, and refugia for juvenile organisms,
such as fish and frogs. Emergent 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. None of the RQ values for either vascular on non-vascular aquatic plants
exceed the LOC, therefore the determination is "no effect" via indirect effects on the
aquatic-phase CRLF through reductions in primary productivity and/or emergent
vegetation.
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. 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.
Propyzamide is toxic to both monocotyledonous and dicotyledonous plants. RQ values
for both groups exceed LOCs for plants in dry and semi-aquatic habitats. Therefore, the
determination is likely to adversely affect (LAA) the CRLF through indirect effects on
terrestrial plant habitats.
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).
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The effects determinations for indirect effects to the CRLF via direct effects to aquatic
and terrestrial plants are used to determine whether modification to critical habitat may
occur. Although aquatic plants are not affected by the assessed uses of propyzamide,
terrestrial plants are likely to be adversely affected from the use of the herbicide.
Reductions in the extent of riparian cover may lead to reductions in water quality due to
increased runoff of sediments, decreased shading leading to increased water
temperatures, and decreased structure.
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 the
fact that acute and chronic RQ values are below LOCs, current registered uses of
propyzaimide are expected to have no effect on the remaining aquatic-phase PCE.
Therefore, the determination is "no effect".
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.
As discussed previously, terrestrial plants are adversely affected by propyzamide and the
determination is habitat modification for the two terrestrial-phase PCE through
disturbance of upland habitat to support food sources of CRLF and through elimination
and/or disturbance of dispersal habitat.
The third terrestrial-phase PCE is "reduction and/or modification of food sources for
terrestrial-phase juveniles and adults." To assess the impact of propyzamide on this PCE,
acute and chronic toxicity endpoints for terrestrial invertebrates, mammals, and
terrestrial-phase frogs are used as measures of effects. As discussed previously, the
likelihood of reductions in the prey base of terrestrial-phase CRLF cannot be discounted;
therefore, the determination is habitat modification for the third terrestrial-phase CRLF
PCE through reduction and/or modification of food sources for terrestrial-phase juvenile
and adult CRLF.
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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. Although direct effects to the terrestrial-phase CRLF are not considered likely,
indirect effects through reductions in the availability of its food items are considered
likely to adversely affect the species; therefore, the determination is habitat modification
for the fourth terrestrial-phase PCE.
6. Uncertainties
As discussed in the problem formulation, the process used in assessing the risks
associated with the currently labeled uses of propyzamide is consistent with that
discussed in the Agency's document entitled "Overview of the Ecological Risk
Assessment Process in the Office of Pesticide Programs'"
(http://www.epa.gov/oppfeadl/endanger/consultation/ecorisk-overview.pdf ). Throughout this
document a number of uncertainties have been characterized. These uncertainties arise
from a lack of data and in lieu of data the Agency relies on standard assumptions. The
Overview Document provides a relatively thorough review of the uncertainties and
underlying assumptions associated with screening-level risk assessments; however, some
areas of uncertainty are also described below.
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 Propyzamide
The standard ecological water body scenario (standard farm 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 standard farm 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 standard farm 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 standard farm pond. These water
bodies will be either smaller in size or have larger drainage areas. Smaller water bodies
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have limited storage capacity and thus may overflow and carry pesticide in the discharge,
whereas the standard farm 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 standard farm 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 standard farm 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 standard farm pond is assumed to be
representative of exposure to aquatic-phase CRLFs. In addition, the Services agree that
the existing standard farm pond represents the best currently available approach for
estimating aquatic exposure to pesticides (USFWS/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.
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.
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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
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, PRZM/EXAMS acute and
chronic exposure estimates were evaluated with the available monitoring data. Modeled
exposure estimates reflect total residues of concern, whereas monitoring data reflect
detections of propyzamide parent only. Therefore, the evaluative power of the
monitoring data is poor. Peak and 90-day average total residue EECs from the maximum
use pattern of each potential propyzamide use in California range from 13.9-225 |ig/L
and 12.6-207 |ig/L, respectively. The maximum concentrations of propyzamide detected
in California reported in the California DPR surface water database and NAWQA are
0.25 |ig/L and 0.11 |ig/L, respectively. These values for propyzamide per se are 2-3
orders of magnitude below those estimated for the total residues. However, they are
consistent with the peak (3.7-10.3 |ig/L) and annual mean (0.53-4.45 |ig/L) drinking
water exposure estimates of propyzamide per se that were generated in support the 2002
TRED (USEPA 2002a). The modeled total residue exposure estimates of this assessment
are, therefore, expected to be reasonably conservative measures of exposure.
6.1.3 Action Area Uncertainties
An example of an important simplifying assumption that may require future refinement is
the assumption of uniform runoff characteristics throughout a landscape. It is well
documented that runoff characteristics are highly non-uniform and anisotropic, and
become increasingly so as the area under consideration becomes larger. The assumption
made for estimating the aquatic action area (based on predicted in-stream dilution) was
that the entire landscape exhibited runoff properties identical to those commonly found in
agricultural lands in this region. However, considering the vastly different runoff
characteristics of: a) undeveloped (especially forested) areas, which exhibit the least
amount of surface runoff but the greatest amount of groundwater recharge; b)
suburban/residential areas, which are dominated by the relationship between
impermeable surfaces (roads, lots) and grassed/other areas (lawns) plus local drainage
management; c) urban areas, that are dominated by managed storm drainage and
impermeable surfaces; and d) agricultural areas dominated by Hortonian and focused
runoff (especially with row crops), a refined assessment should incorporate these
differences for modeled stream flow generation. As the zone around the immediate
(application) target area expands, there will be greater variability in the landscape; in the
context of a risk assessment, the runoff potential that is assumed for the expanding area
will be a crucial variable (since dilution at the outflow point is determined by the size of
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the expanding area). Thus, it is important to know at least some approximate estimate of
types of land use within that region. Runoff from forested areas ranges from 45 -
2,700% less than from agricultural areas; in most studies, runoff was 2.5 to 7 times higher
in agricultural areas (e.g., Okisaka el al., 1997; Karvonen el al., 1999; McDonald el al.,
2002; Phuong and van Dam 2002). Differences in runoff potential between
urban/suburban areas and agricultural areas are generally less than between agricultural
and forested areas. In terms of likely runoff potential (other variables - such as
topography and rainfall - being equal), the relationship is generally as follows (going
from lowest to highest runoff potential):
Three-tiered forest < agroforestry < suburban < row-crop agriculture < urban.
There are, however, other uncertainties that should serve to counteract the effects of the
aforementioned issue. For example, the dilution model considers that 100% of the
agricultural area has the chemical applied, which is almost certainly a gross over-
estimation. Thus, there will be assumed chemical contributions from agricultural areas
that will actually be contributing only runoff water (dilutant); so some contributions to
total contaminant load will really serve to lessen rather than increase aquatic
concentrations. In light of these (and other) confounding factors, the Agency believes
that this model gives us the best available estimates under current circumstances.
6.1.4 Usage Uncertainties
County-level usage data were obtained from California's Department of Pesticide
Regulation Pesticide Use Reporting (CDPR PUR) database. Four years of data (2002 -
2005) 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 Propyzamide
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
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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%
(U.S. Environmental Protection Agency, 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.
6.1.6 Spray Drift Modeling
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 propyzamide from multiple applications, each application of
propyzamide would have to occur under identical atmospheric conditions (e.g., same
wind speed and same wind direction) and (if it is an animal) the animal being exposed
would have to be located in the same location (which receives the maximum amount of
spray drift) after each application. Additionally, other factors, including variations in
topography, cover, and meteorological conditions over the transport distance are not
accounted for by the AGDISP 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 AGDISP may
overestimate exposure, especially as the distance increases from the site of application,
since the model does not account for potential obstructions (e.g., large hills, berms,
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buildings, trees, etc.). Furthermore, conservative assumptions are made regarding the
droplet size distributions being modeled ('ASAE Very Fine to Fine' for ground
applications), the application method, release heights, and wind speeds, if not specified
on the labels. Alterations in any of these inputs could decrease the area of potential
effect.
AGDISP has not been validated for modeling ground applications. Therefore, estimates
generated from the ground application mode carry higher uncertainty than those of the
aerial application mode. However, the aerial mode of AGDISP yielded shorter buffer
distances than the ground mode when modeling ground applications. Therefore, the
outputs from the ground mode were considered conservative for this analysis regardless
of the uncertainty in their values.
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 tests and open literature data on propyzamide are not available for
frogs or any other aquatic-phase amphibian; therefore, freshwater fish are used as
surrogate species for aquatic-phase amphibians. 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.
As discussed previously, there is considerable uncertainty regarding the potential chronic
toxicity of propyzamide. Estimates of chronic toxicity to aquatic-phase and terrestrial-
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phase CRLF in this assessment are based on the acute-to-chronic ratio developed for
mammalian toxicity studies. The extent to which this ratio results in reasonable estimates
of chronic toxicity values for surrogate fish and birds is uncertain.
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
testing of species response to chronic exposure conditions and subsequent chronic risk
assessment. Consideration of additional sublethal data in the assessment 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.
No data are available on the sublethal effects of propyzamide; however, the absence of
data cannot be construed as the absence of effects. To the extent to which sublethal
effects are not considered in this assessment, the potential direct and indirect effects of
propyzamide 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.
6.2.5 Location of Wildlife Species
There is uncertainty regarding the toxicity of technical grade active ingredient relative to
that of formulated endproduct. The acute toxicity estimates for freshwater fish are based
on nominal concentrations from studies of formulated endproduct rather than technical
grade active ingredient and these toxicity estimates exceed the solubility limit (i.e., 15
mg/L) of propyzamide. However, as discussed previously, even if acute toxicity
estimates had been based on the solubility limit, RQ values would have been well below
the acute risk LOC.
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6.2.6 Absence of Chronic Toxicity Data
This assessment has had to rely on acute-to-chronic ratios to estimate chronic toxicity
endpoints for freshwater fish (serving as surrogates for aquatic-phase amphibians) and for
birds (serving as surrogates for terrestrial-phase amphibians and reptiles). In the absence
of data, the ACR provides a means to take advantage of the best available data to address
data gaps.
6.2.7 Mechanism of Action
Propyzamide is proposed to inhibit cell division by preventing the formation of spindle
fibers during mitosis via binding to proteins associated with microtubule assembly
(Griffen 2003). Since the role of spindle fibers in mitosis is common to plants and
animals, it is unclear why animals would not be as susceptible to propyzamide as plants;
however, the avaialbe toxicity data suggest that animals are not particularly sensitive to
this compound.
7. 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 propyzamide to the CRLF and its
designated critical habitat.
Based on the best available information, the Agency makes a Likely to Adversely Affect
determination for the CRLF from the use of propyzamide. Additionally, the Agency has
determined that there is the potential for modification of CRLF designated critical habitat
from the use of the chemical.
Based on the conclusions of this assessment, a formal consultation with the U. S. Fish
and Wildlife Service under Section 7 of the Endangered Species Act should be initiated.
Attachment 2, which includes information on the baseline status and cumulative effects
for the CRLF, can be used during this consultation to provide background information on
past US Fish and Wildlife Services biological opinions associated with the CRLF.
A summary of the risk conclusions and effects determinations for the CRLF and its
critical habitat, given the uncertainties discussed in Section 6, is presented in Tables 7.1
and 7.2.
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Table 7.1 Effects Determination Summary for Direct and Indirect Effects of propyzamide on the
CRLF
Assessment Endpoint
Effects
Determination1
Basis for Determination
Aquatic-Phase CRLF
(Eggs, Larvae, and Adults)
Direct Effects:
Survival, growth, and reproduction of
CRLF individuals via direct effects on
aquatic phases
NE
RQ values for CRLF are below acute and chronic LOCs.
Indirect Effects:
Survival, growth, and reproduction of
CRLF individuals via effects to food
supply (i.e., freshwater invertebrates,
non-vascular plants, fish, and frogs)
Freshwater
invertebrates: NE
RQ values for freshwater invertebrates are below acute
and chronic LOCs
Non-vascular aauatic
olants: NE
RQ values for non-vascular aquatic plants are below the
LOC.
Fish and froes:
NE
RQ values for freshwater vertebrates (fish and
amphibians) are below acute and chronic LOCs.
Indirect Effects:
Survival, growth, and reproduction of
CRLF individuals via indirect effects on
habitat, cover, and/or primary
productivity (i.e., aquatic plant
community)
Non-vascular
aauatic olants:
NE
RQ values for non-vascular aquatic plants are below the
LOC.
Vascular aauatic
olants:
NE
RQ values for vascular aquatic plants are below the
LOC.
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.
LAA
Terrestrial plant RQ values exceeded and riparian
vegetation is likely to be adversely affected which in turn
could indirectly affect water quality and habitat in ponds
and streams comprising the species' current range.
Terrestrial-Phase CRLF
(Juveniles and adults)
Direct Effects:
Survival, growth, and reproduction of
CRLF individuals via direct effects on
terrestrial phase adults and juveniles
LAA
Chronic RQ values exceed the chronic risk LOC.
Indirect Effects:
Survival, growth, and reproduction of
CRLF individuals via effects on prey (i.e.,
terrestrial invertebrates, small terrestrial
vertebrates, including mammals and
terrestrial phase amphibians)
Terrestrial
invertebrates: NLAA
Terrestrial insects serving as prey would have a
likelihood of individual mortality of 1 in 20. Based on
this relatively low likelihood of mortality, the potential
effect is considered insignificant and the determination is
for a not likely to adversely affect (NLAA)
Mammals: LAA
None of the RQ values exceed the acute risk LOC while
both dose-based and dietary-based chronic RQ values
exceed the chronic risk LOC. No additional information
is available to refine these initial chronic risk estimates;
therefore, the determination is for a likely to adversely
affect (LAA) terrestrial-phase CRLF based on indirect
adverse chronic effects on mammals serving as food for
terrestrial-phase CRLF
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Fross:
LAA
There is uncertainty regarding the chronic toxicity
endpoint used to assess direct chronic risk to terrestrial-
phase CRLF. This same uncertainty would apply to
other terrestrial-phase amphibians and therefore, the
determination is for a likely to adversely affect (LAA)
terrestrial-phase CRLF through indirect chronic effects
on other terrestrial-phase frogs serving as prey
Indirect Effects:
Survival, growth, and reproduction of
CRLF individuals via indirect effects on
habitat (i.e., riparian vegetation)
LAA
Terrestrial plant RQ values for semi-aquatic and dry
areas exceed the LOC.
1 NE = no effect; NLAA = may affect, but not likely to adversely affect; LAA = likely to adversely affect
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Table 7.2 Effects Determination Summary for the Critical Habitat Impact Analysis
Assessment Endpoint
Effects
Determination1
Basis for Determination
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.
HM
Although aquatic plants are not affected by the
assessed uses of propyzamide, terrestrial plants are
likely to be adversely affected from the use of the
herbicide. Reductions in the extent of riparian
cover may lead to reductions in water quality due
to increased runoff of sediments, decreased
shading leading to increased water temperatures,
and decreased structure
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.5
HM
Alteration of other chemical characteristics necessary
for normal growth and viability of CRLFs and their
food source.
HM
Reduction and/or modification of aquatic-based food
sources for pre-metamorphs (e.g., algae)
NE
RQ values for freshwater vertebrates (fish and
amphibians) and aquatic nonvascular plants are
below acute and chronic LOCs.
Terrestrial-Phase CRLF PCEs
(Upland Habitat and Dispersal Habitat)
Elimination and/or disturbance of upland habitat;
ability of habitat to support food source of CRLFs:
Upland areas within 200 ft of the edge of the riparian
vegetation or dripline surrounding aquatic and
riparian habitat that are comprised of grasslands,
woodlands, and/or wetland/riparian plant species that
provides the CRLF shelter, forage, and predator
avoidance
HM
Terrestrial plant RQ values exceed the LOC.
Terrestrial plants are adversely affected by
propyzamide and the determination is for a likely
to adversely affect the two terrestrial-phase PCE
through disturbance of upland habitat to support
food sources of CRLF and through elimination
and/or disturbance of dispersal habitat.
Elimination and/or disturbance of dispersal habitat:
Upland or riparian dispersal habitat within
designated units and between occupied locations
within 0.7 mi of each other that allow for movement
between sites including both natural and altered sites
which do not contain barriers to dispersal
HM
Reduction and/or modification of food sources for
terrestrial phase juveniles and adults
HM
The likelihood of reductions in the prey base of
terrestrial-phase CRLF cannot be discounted;
therefore, the determination is for a likely to
adversely affect (LAA) the third terrestrial-phase
CRLF PCE through reduction and/or modification
of food sources for terrestrial-phase juvenile and
adult CRLF.
Alteration of chemical characteristics necessary for
normal growth and viability of juvenile and adult
CRLFs and their food source.
HM
Although direct effects to the terrestrial-phase
CRLF are not considered likely, indirect effects
through reductions in the availability of its food
items are considered likely to adversely affect the
species; therefore, the determination is for a likely
to adversely affect (LAA) the fourth terrestrial-
phase PCE.
5 Physico-chemical water quality parameters such as salinity, pH, mid hardness are not evaluated because these processes are not
biologically mediated and, therefore, are not relevant to the endpoints included in this assessment.
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1 NE = No effect; HM = Habitat modification
The overall determination for the effects of propyzamide on the CRLF is LAA. Based on
the conclusions of this assessment, a formal consultation with the U. S. Fish and Wildlife
Service under Section 7 of the Endangered Species Act should be initiated.
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 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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7.1 Action Area
7.1.1 Areas indirectly affected by the Federal action
The initial action area for propyzamide was previously discussed in Section 2.7 and
depicted in Figure 2.8 of the problem formulation. Typically, in order to determine the
extent of the action area in lotic (flowing) aquatic habitats, uses resulting in the greatest
ratios of the RQ to the LOC for any endpoint for aquatic organisms is used to determine
the distance downstream for concentrations to be diluted below levels that would be of
concern {i.e. result in RQs above the LOC). However, since none of the aquatic
organism RQ values exceeded LOCs, downstream dilution is not considered in this
assessment.
When considering the terrestrial habitats of the CRLF, spray drift from use sites onto
non-target areas could potentially result in exposures of the CRLF, its prey and its habitat
to propyzamide. Therefore, it is necessary to estimate the distance from the application
site where spray drift exposures do not result in LOC exceedances for organisms within
the terrestrial habitat. To account for this, first, the propyzamide application rate that
does not result in an LOC exceedance is calculated for each terrestrial taxa of concern.
The Gaussian extension of AGDISP is then used to determine the distance required to
reach EECs not exceeding any LOCs. These values are defined for each use in Table
7.3.
Table 7.3. Spray drift buffer distances used to determine the extent of terrestrial action
area for uses of propyzamide.
Land Cover
Max App. Rate
Spray Method
Buffer Distanee
Cultivated Crops
4.08 lbs a.i./A
Aerial
11,000 ft
Orchards/vineyards
4.08 lbs a.i./A
Ground
16,200 ft
Turf
1.53 lbs a.i./A
Ground
9,620 ft
Pasture
0.510 lbs a.i./A
Aerial
4,240 ft
To understand the area indirectly affected by the federal action due to spray drift from
application areas of propyzamide, land covers are considered as potential application
areas. These areas are "buffered" using ArcGIS 9.2. In this process, the original land
cover is modified by expanding the border of each polygon representing a field out to a
designated distance, which in this case, is the distance estimated where propyzamide in
spray drift does not exceed any LOCs. This effectively expands the action area relevant
to terrestrial habitats so that it includes the area directly affected by the federal action,
and the area indirectly affected by the federal action.
7.1.2 Areas indirectly affected by the Federal action
In order to define the final action areas relevant to uses of propyzamide, it is necessary to
combine areas directly affected, as well as aquatic and terrestrial habitats indirectly
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affected by the federal action. This is done separately for each use with ArcGIS 9.2.
Landcovers representing areas directly affected by propyzamide applications are
overlapped with indirectly affected aquatic habitats (if determined by down stream
dilution modeling) and with indirectly affected terrestrial habitats (if determined by spray
drift modeling). It is assumed that lentic (standing water) aquatic habitats (e.g. ponds,
pools, marshes) overlapping with the terrestrial areas are also indirectly affected by the
federal action. The result is a final action area for propyzamide uses on agricultural lands,
orchards and vineyards, pastures, and turf. The final action areas of concern for this
assessment are depicted for each land cover in Figures 7.1-7.4,
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Propyzamide Cultivated Crop Action Area
Legend
propyzamide Cultivated (11000ft)
Recovery units
County boundaries
Compiled from California County boundaries (ESRI, 2002),
US DA National Agriculture Statistical Service (NASS, 2002)
Gap Analysis program Orchard* Vineyard Landcwer (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).
Produced 1/17/2008
Figure 7.1. Final action area for agricultural uses of propyzamide.
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Propyzamide Action Area for Orchard
Legend
| Propyzamide Orchard 16200ft Buffer
Recovery units
0 25 50 100 150 200
Compiled from California County boundaries (ESRI, 2002),
USCA National Agriculture Statistical Service (NASS, 2002)
Gap Analysis Program Orchard/ Vineyard Landccwer (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 1333 (NAD 1 983).
Produced 1/17/2008
Figure 7.2. Final action area for orchard and vineyard uses of propyzamide.
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Propyzamide Action Area for Pasture
Legend
Propyzamide Pasture 4240ft Buffer
~ Recovery units
Kilometers
0 25 50 100 150 200
Compiled from California County boundaries (ESRI, 2002),
USQA National Agriculture Statistical Service (NASS, 2002)
Gap Anat/sis 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).
Produced 1/17/2008
Figure 7.3. Final action area for pasture uses of propyzamide.
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Propyzamide Action Area for Turf
Legend
Propyzamide Turf9620ft Buffer
Recovery units
0 25 50 100 150 200
Compiled from California County boundaries (ESRI, 2002),
USDA National Agriculture Statistical Service (NASS, 2002)
Gap Anatysis Program Orchard/Vineyard Landco/er (GAP)
National Land Cover Databaas (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 1933 (NAD 1983).
Produced 1/17/2008
Figure 7.4. Final action area for turf uses of propyzamide.
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7.1.2 Determination of overlap between propyzamide action area and
CRLF habitat
There are three types of CRLF habitat areas considered in this assessment: Critical
Habitat (CH); Core Areas; and California Natural Diversity Database (CNDDB)
occurrence sections (EPA Region 9) (Figure 7.5). Critical habitat areas were obtained
from the U.S. Fish and Wildlife Service's (USFWS) final designation of critical habitat
for the CRLF (USFWS 2006). Core areas were obtained from USFWS's Recovery Plan
for the CRLF (USFWS 2002). The occurrence sections represent an EPA-derived subset
of occurrences noted in the CNDDB. They are generalized by the Meridian Range and
Township Section (MTRS) one square mile units so that individual habitat areas are
obfuscated. As such, only occurrence section counts are provided and not the area
potentially affected.
In order to confirm that uses of propyzamide have the potential to affect CRLF through
direct applications to target areas and runoff and spray drift to non-target areas, it is
necessary to determine whether or not the final action areas for propyzamide uses overlap
with CRLF habitats. Spatial analysis using ArcGIS 9.2 indicates that terrestrial habitats
(and potentially lentic aquatic habitats) of the final action areas overlap with the core
areas, critical habitat and available occurrence data for CRLF. The spatial overlap of
each land cover on each recovery unit is listed in Table 7.4 followed by more detailed
tabulation on the county scale. The overlap of CRLF core areas, critical habitat,
occurrences, and the total California action area are depicted in Figure 7.6, with
magnified layouts of the recovery units depicted in Appendix D. Limitations and
constraints associated with the geographic data sets used to assess the action area are
discussed in Appendix D.
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CRLF Recovery Units and Habitat Areas
Sierra Neva<
=oothills <1)
Diablo Range
Salinas Valley (6)
North Coast foothills
Western Sacramento River (
North San Francisco BaV
North Coast (3)
South and East
San Francisco Bay (4)
Central Coast (5)
Northern Transverse Range
Techachapi Mountains (7)
Legend
H CA counties
~ CRLF Recovery Units
| | CNDDB occurrence sections
| Critical habitat
Core areas
e Re
Southern Transverse Range
Peninsular ranges (8)
l Kilometers
0 2040 80 120 160
Compiled from California County boundaries (ESRI, 2002),
USDA National Agriculture Statistical Service (NASS, 2002)
Gap Analysis Program Orchard/Vineyard Landcover (GAP)
National Land Cover Database (NLCD) (MRLC, 2001)
Map created by US Environmental Protection Agency, Office
of Pesticides Programs, Environmental Fate and Effects Division.
June, 2007. Projection: Albers Equal Area Conic USGS, North
American Datum of 1983 (NAD 1983)
Figure 7.5. Recovery units and areas relevant to the CRLF.
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Table 7.4. Spray drift action area & CRLF habitat overlap spatial summary results
by recovery unit.
Measure
RU1
RU2
RU3
RU4
RU5
RU6
RU7
RU8
Total
Established species habitat area
(CH plus core in sq km)
2894
1224
1244
3228
3712
4921
4840
1377
23440
Established occurrence sections
(972 total; 30 outside recovery
units)
13
3
70
328
281
122
92
33
942
Cultivated crop use (11,000-ft buffer)
Overlapping habitat area (sq
km)
761
65
254
953
2305
1931
2466
404
9142
Percent area affected
26%
5%
20%
30%
62%
39%
51%
29%
39%
# Occurrence sections affected
2
0
32
144
243
81
80
28
610
Orchard/vineyard use (16,200-ft buffer)
Overlapping habitat area (sq
km)
393
0
47
354
147
375
1241
517
3074
Percent area affected
14%
0%
4%
11%
4%
8%
26%
28%
13%
# Occurrence sections affected
2
0
17
93
27
16
27
4
186
Pasture use (4,240-ft buffer)
Overlapping habitat area (sq
km)
155
216
27
120
539
579
1082
100
2818
Percent area affected
5%
18%
2%
4%
15%
12%
22%
7%>
12%
# Occurrence sections affected
2
0
4
45
99
38
54
14
256
Turf use (9,620-ft buff er)
Overlapping habitat area (sq
km)
378
108
530
1764
1400
878
1370
778
7006
Percent area affected
13%
9%
43%
55%
38%
18%
28%
57%
30%
# Occurrence sections affected
5
1
53
239
192
51
69
26
636
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Propyzamide Action Area for All Uses
Legend
| propyzamide All Uses Buffered
| Critical habitat
Core areas
~~| CNDDB overlap
CNDDB occurence sections
Recovery units
County boundaries
Custom layout
M Kilometers
150 200
Compiled from California County boundaries (ESRI, 2002),
US DA National Agriculture Statistical Service (NASS, 2002)
Gap Analysis Program Orchard; Vineyard Uandcover (GAP)
National Land Cover Database (NLCD) (MRLC, 2001)
Map created by US Environmental Protection Agency, Office
of Pesticides Programs, Erwinonmental Fate and Effects Division.
Projection: Albers Equal Area Conic USGS, North American
Datum of 1983 (NAD 1 333).
Produced 1/17/2008
Figure 7.6. Map of overlap between action area for propyzamide and CRLF core
areas and critical habitat.
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8. References
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R.W. McDiarmid and R. Altig (Eds.), Tadpoles: The Biology of Anuran
Larvae.University of Chicago Press, Chicago, pp. 24-51.
Alvarez, J. 2000. Letter to the U.S. Fish and Wildlife Service providing comments on
the Draft California Red-legged Frog Recovery Plan.
Atkins. E.L., E.A. Greywood, and R.L. MacDonald. 1975. Toxicity of pesticides and
other agricultural chemicals to honey bees. Laboratory studies. Univ. of Calif.,
Div. Agric. Sci. Leaflet 2287. 38 pp. (MRID# 000369-35).
Burns, L.A. 1997. Exposure Analysis Modeling System (EXAMSII) Users Guide for
Version 2.97.5, Environmental Research Laboratory, Office of Research and
Development, U.S. Environmental Protection Agency, Athens, GA.
Carsel, R.F. , J.C. Imhoff, P.R. Hummel, J.M. Cheplick and J.S. Donigian, Jr. 1997.
PRZM-3, A Model for Predicting Pesticide and Nitrogen Fate in Crop Root and
Unsaturated Soil Zones: Users Manual for Release 3.0; Environmental Research
Laboratory, Office of Research and Development, U.S. Environmental Protection
Agency, Athens, GA.
CDPR. 2006. Surface Water Database. California Department of Pesticide Regulation,
Surface Water Protection Program. Online at:
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